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April 16

Ice age

Here it says how the three main causes of ice ages are: The earth's orbit around the sun changing; the atmosphere changing; and the "arrangment of the continents". I heard how scientists say there will be another ice age in about five million years from now. How do they know that? Jonathan ^talk File:Canada flag 300.png 00:40, 16 April 2006 (UTC)

They are estimating based on the past. They find evidence of changes in Ice cores and from those changes they try to predict what is likely to happen. Admittedly, the "arrangement of the continents" reason sounds suspicious. I will have a look at that one. The orbit around the sun can be predicted with a very high degree of accuracy, and its effect on the amount of heat the earth receives, and the rates at which it receives the heat will affect when the next ice age will occur. Ansell 00:58, 16 April 2006 (UTC)

The arrangement of the continents is very important. The arrangement of land is relevant as it affects the circulation of the oceans, which has a strong modifying effect on climate - ice ages are far more likely in some continental arrangements than others. It only sounds like an odd reason because we normally think of "The Ice ages" as occurring only in the last few million years, during which time the continents have been roughly in the same places - but they've actually been going on intermittently for hundreds of millions of years. Sometimes there are long periods with no ice ages or long periods with many ice ages - the reason for these two distinct climatic histories is the positions of the land masses. Grutness...wha? 01:32, 16 April 2006 (UTC)

A follow-up to that from the BBC... [[1]] Grutness...wha? 04:59, 22 April 2006 (UTC)

While I have no doubt that a significant change in the Earth's orbit could cause an ice age, what makes them think the Earth's orbit has ever changed significantly ? StuRat 23:36, 17 April 2006 (UTC)

Thanks for all the answers. (Does anyone think my signature is ugly?) Jonathan ^talk File:Canada flag 300.png 14:23, 18 April 2006 (UTC)

I do (at least the name part, the Canadian flag is OK). StuRat 09:11, 20 April 2006 (UTC)

black people

Do they tan or is their skin always the same color? A Clown in the Dark 01:47, 16 April 2006 (UTC)

Sun tanning is simply the skin activating chemicals that are already in our skin. People who have those compounds activated because of their genes, may get slightly more tanned, however, I am not sure it would be easy to tell the difference as their extra level of activation may be very minor. Ansell 02:48, 16 April 2006 (UTC)

Black skin is not, however, immune to burning, and more to the point, it's not immune to skin cancer (though it less prone to certain types of skin cancer than lighter skin.) --jpgordon∇∆∇∆ 02:58, 16 April 2006 (UTC)

Yes, black people tan. WAS 4.250 17:32, 16 April 2006 (UTC)

They are susceptible to tanning and burning, and the effect can be just as dramatic as in whites. Bhumiya (said/done) 21:22, 16 April 2006 (UTC)

Though, as one would expect, it's much easier to notice the difference in a 1% shade to 11% shade change than a 30% shade to 40% shade change. In other words, your big fat white Uncle Al would look quite a bit more rediculous with a light burn than your dark muscular Aunt Franco.  freshgavinΓΛĿЌ  05:20, 17 April 2006 (UTC)

Yes, they do tan, though the effect is considerably much less noticeable because of the high melanin level found naturally in their skin in the firs place. Luthinya 10:36, 17 April 2006 (UTC)

Drive Arrays In Proliant 3000

Since linux doesn't treat my HD very separately and treats them as one big 'hda', what does that mean if one drive fails on start up?

Similarly, if I erase my server and treat the drives as one big "logical drive" does that enhance risk of data loss in the event that one drive fails? Would they be better all as separate logical drives? Also, what is the meaning of a an array - why are my logical drives arranged under the umbrella of an 'array'?

I would like to make use of the maximum amount of space with the minimum risk of failure which I think is RAID 0, all HDs treated separately. Also, why if one drive fails, should the server demand that it is replaced before starting up? Even if it is replaced, the data isn't going to be there...? --Username132 (talk) 01:50, 16 April 2006 (UTC)

Maximum space doesn't go with minimum failure. You choose which one you are more worried about and go with that. I would personally choose RAID 0 for speed, but with the knowledge that because it is one logical drive, if one fails, there is no backup. However, if you want minimum failure, look at RAID 1, where you get everything put down twice on separate hard drives so if one fails you can still use the other one.

Linux only treats them as one big hda if they are all put together in RAID, or if you are using Logical Volume Management, or any of the alternatives. If you put two non-RAID hard drives in Linux is likely to assign one the hda and one the hdb, unless they are SCSI in which case they will be sda and sdb.

If one drive in a RAID 1 array fails on startup nothing bad happens, your computer will boot as normal. However, if you have RAID 0, you have just lost half of the data on your computer. Ansell 02:44, 16 April 2006 (UTC)

Well I want to use 8 (18.2 GB) drives. I figure I could split this into two logical arrays - one consisting of a single HD for the OS(es) and another for storage. But if 7 drives are in one logical drive does that mean that they're all one partition? I the logical drive entry doesn't explain what would happen if one drive failed? Would I be better off having 8 logical drives or the two like I just mentioned?

If you have a large number of drives your best bet is RAID 5 - this will strip data across multiple drives, but will add a parity drive so that you have one level of redundancy - a failure in any single drive will result in no loss of data. As you add drives your chances of having a failure go up - with seven drives you are definitely in a high-risk position with RAID 0. With RAID 0 your space available is the sum of all drives. With RAID 1 it is the size of one drive. With RAID 5 it is the sum of all drives minus 1. Performance of RAID 5 is less than RAID 0 or 1, but better than single drive performance. Raid can be implemented both in hardware (which is common on server-class hardware like a Proliant), or by software (LVM, etc). Rich0 12:37, 23 April 2006 (UTC)

When did RAID come into existence? The computer I'm referring to is about 8 years old and uses hot-pluggable SCSI drives in their own little caddies. When I use Compaq SmartStart to configure 'the array', it invariably wants to put them all into one big logical drive and the "array condiguration utility" gives me a graphic kind of like this;

Controller
    |
   Array
       |
       Logical drive 1
       Logical drive 2

What's this array nonsense? I don't want any arrays... :( --Username132 (talk) 03:43, 16 April 2006 (UTC)

See Redundant array of independent disks for history and more. Servers such as yours have had RAID controllers for long, it seems, but common PCs/Desktops generally only for the past 3-4 years. Max space / Min failure would seem at it simplest to correspond to a RAID 1 setup, 2 logical drives of 4 identical physical disks each = 100% duplication. --Seejyb 14:06, 16 April 2006 (UTC)

P2P Malware

If you download a linux distro from a p2p network, couldn't someone have altered the code to add some malware and control your computer remotely? --Username132 (talk) 02:16, 16 April 2006 (UTC)

Depends on where you got the source from. If you get the link from the distro's website, then no it's fine.

You can run md5sum on the downloaded file and compare this to the sum that is given on the distro's website to confirm that your copy has not been tampered with. They may even have digitally signed the file and you can confirm it that way as well. Ansell 02:38, 16 April 2006 (UTC)

Thanks :) --Username132 (talk) 03:28, 16 April 2006 (UTC)

Forum on IMDB working?

Here is a link to the [Chinatown (1974) entry on IMDB. The forum links aren't working for me. How are they for you? -Username132 (talk) 03:44, 16 April 2006 (UTC)

Did you register? Going to the message board came up with a "Free Registration" window for me, but I don't see the need to give away my details, so i didn't proceed. The user comments were working for me. Is that what you meant? Ansell 04:47, 16 April 2006 (UTC)

Yeah, I'm registered. It even gives my login name in the top right, but when I click on the link to go to a forum (not comments), the browser load bar appears and then makes no progress... indefinately. Thanks for trying anyway. --Username132 (talk) 04:57, 16 April 2006 (UTC)

I'm having no trouble with the link. I'm registered with IMDb, and I went to the main movie page, the main forums page for the movie, and the top topic in the forums list with no problems. Was it perhaps a particular thread that you were having trouble with?--Anchoress 11:38, 16 April 2006 (UTC)

It was a whole forum that wouldn't work. Couldn't get to the forum, or the selected threads on the main movie page. It's spontaneously resolved now, but I don't know why. --Username132 (talk) 18:29, 16 April 2006 (UTC)

I frequently have problems with imdb where it loads a blank page and stops, and I have to refresh to get the info to show up. User:Zoe|^(talk) 21:31, 16 April 2006 (UTC)

Statistics - type 2 error (oh noes!)

According to false negative;

"In statistics, a false negative, also called a Type II error or miss, exists when a test incorrectly reports that a result was not detected, when it was really present. (Alternatively, a Type 2 error can be thought of as a failure by accepting the alternative hypothesis when the null hypothesis was truly false.)"

So what it says at first is that a type 2 error is accepting the null hypothesis when the alternative hypothesis was correct? And then it contradicts itself by saying alternatively, a type 2 error is accepting the alternative hypothesis EVEN THOUGH the null hypothesis is actually wrong? Putting the word 'truly' before false is also stupid. I'm changing it to 'actually'... -Username132 (talk) 04:54, 16 April 2006 (UTC)

The "clarification" inside parentheses is wrong! A type 2 error is an erroneous rejection of the alternative hypothesis. (In other word, the null hypothesis is false but one fails to reject it.) --68.238.254.236 15:20, 16 April 2006 (UTC)

How long before a feral animal becomes a native?

Hey people. I was wondering if there was a hard and fast rule in place about how long a species of feral animal has existed before it is referred to as a native. For example, the dingo was introduced to Australia about 15000 - 30000 years ago and today is generally considered a native animal to Australia. Meanwhile, the feral cats that one sees in outback Australia are as different to domesticated cats that one would consider them a different species (my mother, who used to work in rural Australia, saw examples of feral cats that looked twice as big as a domesticated cat and whose faces looked considerably different). Some of these cats can trace their ancestory in Australia back 400 or so years, leaving one to ask the question, "how long until feral cats are considered native to Australia?"

Cheers --Roisterer 06:12, 16 April 2006 (UTC)

I'm not sure that dingoes can be considered native to Australia. See introduced species for clarification; since the feral cats were introduced, by definition they cannot be native. As far as species is concerned, if these feral cats can still breed with their domestic counterparts and produce fertile offspring, they'll probably be considered the same species. Hope this helps. Isopropyl 06:32, 16 April 2006 (UTC)

You realize that you are asking a question about semantics, not natural fact? Native is an especially slippery word, but in this type of context native usually means only that things or people of its kind were already present in that place when people speaking a European language first arrived. Much evidence suggests that nearly all people and animals and plants have not existed forever in a particular place but arrived at that place at some time in the past. There is no precise answer to "how long should x have existed there before we can call it "native". alteripse 12:09, 16 April 2006 (UTC)

Eyes and sunlight

Why are eyes so heavily affected by sunlight? All it is is just a bunch of photons, it shouldn't be all that harmful.

Gamma radiation is "just a bunch of photons", too. --BluePlatypus 06:34, 16 April 2006 (UTC)

See Sun#Sun observation and eye damage. —Keenan Pepper 07:45, 16 April 2006 (UTC)

The problem is the photons are at too high of an intensity in number that the eye is built to handle... not that the eye was built. -- Mac Davis] ⌇☢ ญƛ. 11:29, 16 April 2006 (UTC)

A photon is pure energy. The eye is a delicate instrument that aquires, measures, and organizes information on that pure energy. If that pure energy is too much energy, then it damages the sensitive parts of that delicate instrumnet. WAS 4.250 17:38, 16 April 2006 (UTC)

Its just like cooking something....as long as the flame is under control the food gets cooked properly....but if you increase the flame or the heat given to it, it gets over cooked and in extreme cases, burnt... our eye is like the food....we dont want it to get burnt..... Jayant,17 Years, India • contribs 17:51, 16 April 2006 (UTC)

As our article says our eyes have evolved to stand directly looking at the sun by accident with little chance of permanent damage. Light concentrating optics and partial solar eclipses are where the real danger lies. The former can hardly be called part of our natural environment and the later is a pretty rare event. Plugwash 17:59, 16 April 2006 (UTC)

The human brain is also probably part of the reason. Just like pain receptors reacting though no damage is being done, the brain has probably evolved to make it seem that our eyes are very sensitive to the sun, in order to teach our less intelligent ancestors a lesson before they started making hobbies of looking at bright yellow balls.  freshgavinΓΛĿЌ  05:12, 17 April 2006 (UTC)

Photons are massless particles, therefore may be said as pure energy. Too much energy in the eyes- ouch! Luthinya 10:37, 17 April 2006 (UTC)

Squiggly shapes in the eyes

In certain lighting conditions I can discern small transparent shapes in my eyes. i guess they are suspended in the sclera, as any attempt to look directly at them results in them moving away in relation to the movement of the eye (a rather comical situation). The shapes are varied, but range from small spots to squiggly-amoeboid shapes, all very small.

Other people seem to have them as well. I looked but couldn't find what I was looking for under disorders of the eye.

What are they, are they bad, and is there any way to remove them? Cheers, Wapatista 09:01, 16 April 2006 (UTC)

See Floater. — Knowledge Seeker দ 09:08, 16 April 2006 (UTC)

They are normal, don't worry about it. Also see Phosphene -- Mac Davis] ⌇☢ ญƛ. 11:28, 16 April 2006 (UTC)

I've been seeing them for more than 10 years now... if they are really bugging you, try not to concentrate on them and look at some dark area... Jayant,17 Years, India • contribs 14:36, 16 April 2006 (UTC)

Also, if you wear contact lenses, they may just need cleaning or replacing. Little spots on them can behave the same way. StuRat 21:56, 17 April 2006 (UTC)

Then again, if you don't wear contacts, try removing your corneas and giving them a good cleaning, LOL. StuRat 00:35, 22 April 2006 (UTC)

Center of Mass & Center of Gravity

I have a conceptual question about a roll of toilet tissue. Are its center of mass and center of gravity the same? Also, could they located in the hollow inside of the roll?Patchouli 14:16, 16 April 2006 (UTC)

Assuming that the roll is in a uniform gravitational field, the center of mass equals the center of gravity, and they are at the center of the roll, in the hollow inside of it. --Andreas Rejbrand 14:22, 16 April 2006 (UTC)

Wow, that center of gravity article is a travesty. We've gotta fix that. Melchoir 06:22, 17 April 2006 (UTC)

Evolution-based explanation for physical differences among races

Native inhabitants of difference parts of the world have different physical features. For example, Europeans tend to have lighter skin/eye/hair colors and "pointier" nose shapes etc. Africans, on the other hand, tend to have darker skin/eye/hair colors, bigger and rounder noses, and hair with very small curls. From the standpoint of evolution, these differences should be explainable in terms of adaptations to the environment and evolutionary advantages. I've tried to come up with an evolution-based explanation for the differences in nose shapes and hair texture, but I couldn't tie these differences to evolutionary advantages. Is there a consensus among scientists as to how nose shapes and hair texture affect survival in different geographic regions?

There is a process called genetic drift by which traits can become common in a population by "chance" without there being a "reason". You can speculate about "reasons" for traits that might lead to active selection, but it is often hard to know if you have found the real cause of a trait being selected in a population. --JWSchmidt 17:09, 16 April 2006 (UTC)

There is no consensus. There are a lot of "just-so" stories ;some are nonsense; some are probably true. Current genetic studies are being done that are beginning to provide scientific evidence that address these issues. We are a long way from having it all figured out. WAS 4.250 17:46, 16 April 2006 (UTC)

Sunlight is used by the skin to synthesize vitamin D. However, too much sunlight causes skin damage. So, in the tropics, where sunlight is abundant, melanin is needed in the skin to absorb most of the sunlight, while in temperate zones, light skin is needed to let the lower quantity of light in. Large nostrils are helpful for breathing, especially when hot. However, large nostrils in cold areas would allow too much cold air in and damage air passages. Straight hair is better at retaining heat and curly hair is better at cooling. StuRat 23:23, 17 April 2006 (UTC)

Soft fatty waist-lines are ideal for balancing opened cans of beer in a sitting position.  freshgavinΓΛĿЌ  07:00, 18 April 2006 (UTC)

EMF (or WMF) to SVG converter

Does anyone know any free software able to convert EMF (or WMF) images to SVG files? --Andreas Rejbrand 14:17, 16 April 2006 (UTC)

You mean, apart from the programs listed by typing "wmf to svg converter" into Google? --Heron 16:32, 16 April 2006 (UTC)

Well, I thought most of them weren't free (it isn't the first time I'm looking for a free converter app.), but I'll have a more carefull look at them. --Andreas Rejbrand 17:01, 16 April 2006 (UTC)

JPEG thumbnail

After installing some software, my computer (Windows ME) no longer shows a thumbnails for jpegs in Explorer. Is there a registry class I should edit to bring it back again.--Bjwebb (talk) 14:37, 16 April 2006 (UTC)

That happens when the ShellEx settings go wonky. Admittedly my WinME install, in Virtual PC is very old, but if you put the following into a .reg file it should, hopefully, do the trick. I take no responsibility if this causes the heat death of the universe. --Blowdart 08:23, 18 April 2006 (UTC)

Do you mean .reg? --WhiteDragon 19:00, 20 April 2006 (UTC)

Err yes :)N --Blowdart 03:21, 22 April 2006 (UTC)

REGEDIT4

[HKEY_CLASSES_ROOT\.jpg\ShellEx]

[HKEY_CLASSES_ROOT\.jpg\ShellEx\{BB2E617C-0920-11d1-9A0B-00C04FC2D6C1}]
@="{7376D660-C583-11d0-A3A5-00C04FD706EC}"

Rapyrox

In a book I was reading, a old lady held an injection of 'rapyrox' against some guy's leg and held him hostage that way. What is rapyrox? I've done google searches, and I get nothing. Recon0. (talk) 14:47, 16 April 2006 (UTC)

I have tried to search for 'rapyrox' using several search engines but havn't found anything. Hence, it is most likely that the word has no real meaning, but is only a "invention" of the author. --Andreas Rejbrand 14:52, 16 April 2006 (UTC)

An Unusual Error in Matlab Program.

Hi, i was trying to create a program to find out the sum of the digits of a given number until the sum was a single digit. For example, if i find sum of digits of the number "15", then it would be 1+5=6. But for "47", it should be 4+7=11 and 1+1=2. so i just wanted to write such a program. First i tried in C, but there handling of floating point variables would have posed problems, so i tried in Matlab. The following is the code which i wrote in Matlab. Please note that in the following code, "type" is the variable whose sum of digits i want to find out. And the variable "sumfinal" stores the final value of sum of digits.

THERE IS A PROBLEM WITH WIKIPEDIA'S CODE DISPLAYING METHODS, I HAVE MODIFIED THIS CODE ON THIS PAGE SO THAT IT SEEMS EXACTLY AS IT IS, BUT WIKIPEDIA ITSELF CREATES NEW INDENTS AND MAKES IT QUITE CLUMSY.

%%%%%%%%%%%%%%BEGINNING OF CODE%%%%%%%%%%%%%%%%
clear
format long
sum=0;
temp=0;
num=2222222222222222222;  % this is the number
while temp==0
    while num~=0        
        digit=mod(num,10);
        sum=sum+digit;
        num=(num-digit)/10;
        sum
    end
    
    
    if sum>9
        num=sum;
        sum=0;
        
    else
        break
    end
    
    
end

sumfinal=sum;
sumfinal
%%%%%%%%%%%%%%%%%%%% END OF CODE %%%%%%%%%%%%%%%%%%%%%

Now, the problem is that i tried out various combinations of numbers and all of them worked out well, but suddenly i found out that whenever i was entering numbers in multiples of "19", the results were not correct. For example, when i entered "1" nineteen times, the correct result displayed by "sumfinal" should be "1", but it shows "9". So i tried it with "2" nineteen times, even then the result was "9", though the correct result should be "2". And surprisingly for "3" nineteen times the result was "-456". So could anyone please help me with this problem. And could you also provide with the bug-free code for this problem of summation of digits. PS: I have been programming in matlab since last 8 months or so, so i am quite experienced in that. secondly, if anyone says that "2" repeated nineteen times is large number , and will not be handled correctly by matlab, then its incorrect to say so, because for simple calculations also, extremely large numbers beyond imagination can be handled. So the "range" is not a problem. I use Matlab 7.

To show code in html enclose it within <pre>...</pre> elements. Can't help you with matlab, but here's some C code that i think does what you want.

void add_digit(char* a,int c) {

  if(!*a) *a = '0';

  c += *a - '0';
  *a = '0' + c % 10;

  c = (c - (c%10))/10;
  if(c>0) add_digit(++a,c);
}

void sum_digits(char* a) {

  char* sum = a++;
  while(*a) {
    int c = *a - '0';
    *a++ = '\0';
    add_digit(sum,c);
  }
}

int main() {
  char num[256] = "2222222222222222222";
  do {
    sum_digits(num);
    printf("sum digits: %s\n",num);
  }while(num[1]);
  return 0;
}

This works, as long as you don't mind reading the interim sums right to left.EricR 17:23, 16 April 2006 (UTC)

Good evening! I happen to believe that the sum of the digits of any number (base 10) is mod(num,9) where mod is the modulo function. If you have it, use it. --DLL 18:49, 16 April 2006 (UTC)

It took me forever to see why the mod 9 method didn't look right to me. It requires an extra check. If it returns 0 and the initial number was not 0, you need to change it to 9. Otherwise, the mod 9 should be correct. --Kainaw ^(talk) 18:59, 19 April 2006 (UTC)

A simple one-line solution would be: "while(number > 9) { number = (number % 10) + (number / 10) }" This assume integer division on "number / 10". If you don't have that, use "floor(number/10)". In the end, "number" will be the one-digit sum. I didn't check this with a lot of numbers, but it worked for a handfull of them. --Kainaw ^(talk) 19:11, 16 April 2006 (UTC)

Well, if you've got arbitrary sized integers that works great. Try a few > 2^32 or 2^64. EricR 20:12, 16 April 2006 (UTC)

culd store them in a string as well and split it up etc --24.193.235.188 07:04, 17 April 2006 (UTC)

Face-to-face intercourse in animals

What animals, if any, engage in sexual intercourse face-to-face other than humans? (Subquestion: Does it even make sense to consider non-mammals?) Off the top of my head, it seems like most mammals go with a rear mounting, 'doggy style' if you will. Seems like whales and dolphins would have to go face-to-face, or belly-to-belly as it were. Seems like the other primates might be the only other animals capable of face-to-face intercourse, but I think they don't. Any information out there? --Ananda

• Bonobos face each other when copulating and are rather famous for it. --Fastfission 17:08, 16 April 2006 (UTC)
• From Missionary position, there's also armadillos. I could swear there was also an insect that uses the position; I thought it was aphids but Google isn't helping me there. Melchoir 04:31, 17 April 2006 (UTC)

Worms don't have faces, but they screw belly up front.  freshgavinΓΛĿЌ  06:56, 18 April 2006 (UTC)

You may be interested in Non-human_animal_sexuality and Canidae#Canine_copulation. Black Carrot 02:56, 19 April 2006 (UTC)

I don't have a reference, but I believe that somebody did a study on the origins of the spread of genital diseases to the mouth to figure out when the switchover occurred for humans. Rich0 12:41, 23 April 2006 (UTC)

SSL CRT

What is the difference between a CRT that I generate using Cpanel and one that I can buy from Verisign (and others) and later insert into Cpanel? — Ilyanep (Talk) 16:45, 16 April 2006 (UTC)

A certificate Cpanel generates is a self-signed certificate, which means a client program connecting to a server using such a certificate has absolutely no assurance the server is not an impostor (sure, I'm amazon.com, trust me, I say so myself, now, what was your credit card number?). Verisign is one of a number of certificate authorities that issue X.509 certificates. To get a certificate authority to issue a certificate you have to prove you're the owner of the IP address the server will run on, so if you trust the CA you can trust that you're not talking to an impostor - for more on this please see the articles on X.509 certificates and certificate authorities. -- Rick Block (talk) 22:56, 16 April 2006 (UTC)

Simple Javascript question

I'm trying to do some simple Javascript and I seem to have forgotten how to do use the DOM correctly. All I want is a function which will cycle through all of the checkbox elements with an id of "record" and set their "checked" property to "true". What's the best way to cycle through them all? I'm frustrated and not finding easy answers Googling around. --Fastfission 16:54, 16 April 2006 (UTC)

Could you just traverse the DOM tree?

function topDownTraverse(n) {

  // do something w/ the node

  for(var m = n.firstChild; m != null; m = m.nextSibling) {
    topDownTraverse(m);
  }
}

EricR 22:16, 16 April 2006 (UTC)

I'm not sure what you're referring to with the traversing, but I know that checkbox elements have a property called "checked", which it shouldn't be too difficult to set to true. You can use the "forms" array builtin to the DOM to cycle through the forms, and if there is more than one element "record", it will be an array and a property of forms[]. Try something like:

function checkallrecord() {
	i = 0;
	j = 0;
	while (document.forms[i]) {
		while (document.forms[i].record[j]) {
			document.forms[i].record[j].checked = true;
			j++;
		}
		i++;
	}
}

Note that this won't work with only 1 checkbox called "record". For anything more than 1, it should be fine. It also doesn't work if the checkboxes aren't encased in 1 or more <form> tags. Hope this helps. -- Daverocks (talk) 11:38, 17 April 2006 (UTC)

A tree traversal algorithm can be used to visit each node of a tree (data structure). The DOM represents parsed documents as trees. During the traversal it's easy to check the node type, name and id, then set any properties you like. EricR 17:25, 17 April 2006 (UTC)

Solar Power

I'm wondering if anybody out there is very experienced with solar power.

I'm not very familiar with the terms involved with electricity and magnetism, so please bear with with me.

Approximately how large would a solar panel have to be, given the approximate average amount of sunlight available in North America, to keep a recharchable battery powerful enough to power a five watt light bulb, sufficiently charged to constantly have power available to turn the light on whenever needed?

If my question is confusing, if I'm using the term "watt" incorrectly or if I'm leaving out some other variable I'll gladly clarify it to the best of my ability. Thanks to anyone who can help me with this. Loomis51 17:06, 16 April 2006 (UTC)

Your question is perfectly alright...:-D ....and from the solar cell article:

When exposed to direct sunlight, a 6-centimeter diameter silicon cell can produce a current of about 0.5 ampere at 0.5 volt (equivalent to about 90 W/m² average, range is usually between 50-150 W/m², depending on sun brightness and solar cell efficiency).

So..i'd guess that'd give you a good idea of how big the panel has to be... Jayant,17 Years, India • contribs 17:45, 16 April 2006 (UTC)

Thanks for the link, but as I said, my knowledge of electricity and magnetism is very poor, so I can't really make sense of all the terminology. Could you tell me how all of that translates into the actual size necessary for the panel? And if I can ask a further question, would you have a rough estimate of what the cost of the panel and the battery would be? (Nevermind the bulb) Thanks! Loomis51 18:13, 16 April 2006 (UTC)

You are welcome... The terminology (90W/m^2) means that for every square meter of a silicon solar cell it produces about 90 W.... so..if you want to recharge a 5 watt bulb..... the area should be 0.055 square meters..... so the area should be around 60-100 square centimeters.... and as for the cost, i dont know about the price in North America since i dont live there...i'll try to search for the price on the internet and put it over here... Jayant,17 Years, India • contribs 21:09, 16 April 2006 (UTC)

Yeah...here we go... that site gives a lot of information on solar panels...and gives you some models for sale..... hope you find them useful...try calling up some of the phone numbers on the website and talk to them...... if you want more information, just ask...:-D ..Jayant,17 Years, India • contribs 21:18, 16 April 2006 (UTC)

Thanks Jayant, you've been a great help! If only all Wikipedians were as courteous and helpful as you. I'm sure I'll have a few more questions in the near future, but for now I'll check out the sites you mentioned. Thanks again! Loomis51 00:22, 17 April 2006 (UTC)

This is a very easy question. All you have to do is think in terms of ENERGY. A 5 watt light bulb comsumes 5 joules of energy per second. Assume that you need the bulb to be on 24 hours per day. 1 day = 24 * 60 * 60 seconds or 86400 seconds.

Therefore a 5 watt bulb requires 5 * 86400 or 432000 joules per day. So all you need to do is to calculate the (area) amount of solar panels to generate as least 432000 joules of electrical energy per day.

Solar panels tells you how much power (in watts) they generate in the "best case senario" so you need to account for the "worse case senario". Also remember that there is no sun light at night. So multiple the "watts" of the solar panel by the amount of sunlight in seconds and make sure you includes some redundancy for cloudy periods to get the amount of energy stored per day.Ohanian 04:43, 17 April 2006 (UTC)

Well, you cannot really charge up a light. What you can do is charge up a battery which can run the light. A standard rechargable battery (type D, C, AA or AAA) can be charged up using three of the above solar cells in series to deliver 1.5 volts. Make sure you leave it in strong sunlight, and only use a light bulb intended for 1.5 volts. You might also want to put a rectifier in the circuit to make sure it does not discharge itself when it is dark. One other problem is the battery will tend to lose its ability to discharge if left charged up for a long time. Have you heard about the Faraday Flashlight?

I have got one for emergencies, not a bad deal.

Which Test To Find P-value And How Many Freedom Degrees?

I've done an experiment where we took ONE SAMPLE of neurones, extracted something from them, split it into two samples and measured the quantity of a chemical in the solution, comparing it to a control set of neurones which were treated more nicely during incubation. Do I have one or zero degrees freedom? Although a repeat was performed, it was using the same sample extracted from one set of neurones? How do I know which is the appropriate statistical test to find a p-value? -Username132 (talk) 17:54, 16 April 2006 (UTC)

It sounds like there is one degree of freedom, whether it was treated "nicely", or not, as you put it. StuRat 23:03, 17 April 2006 (UTC)

What I meant was that there were some control neurones which were incubated with nothing special added to them, and some others (the mistreated ones) where we added NMDA. Here's how the experiment went down;

One control sample > split into two > chemical measured > average taken

One NMDA sample  > split into two > chemical measured > average taken

The two averages were then compared. Since we only took one sample of neurones for each the control and NMDA treated neurones (i.e. one rat) and split the sample into two, I think because there was only one rat involved (out of the entire global population), there are zero degress of freedom. You understand what I'm saying?

Either way though, what is the test used to compare to values in this way? --Username132 (talk) 00:31, 18 April 2006 (UTC)

I don't believe any statistical significance test can function with a sample size of 2 (assuming "split into two" means they're meant to function as seperate samples). It seems like they generally need at least a dozen. Without that, there's no way to guess at how wide the standard deviation is. If I understand degrees of freedom right (a big if), I think you have one. I think there are two variables being measured (one categorical and one numerical), and that only the dependent variable (the numerical one) is counted as a degree of freedom. If you get a bigger sample size, the t-test is what you want. Whether it should be paired-sample or not is a bit trickier. All the samples come from one rat, which means they're related, but within that rat the neurons are (I assume) randomly chosen. You'd use an independent sample test (testing the relationship between two well-distributed, unconnected sets of samples) and then, to take into account the effects of the single rat, state in your conclusion that your results only apply to the rat tested and can not necessarily be extended to the general population of rats. If you don't want to go back and get a larger sample, you could of course fake your results (not recommended), use the test anyway (equivalent to faking results, but without as much of a stigma attached), or just subtract one average from the other and mention in your conclusion that the results may or may not be representative. Black Carrot 02:27, 19 April 2006 (UTC)

One further thought: I'm not actually at all sure you did choose the neurons randomly. You certainly wouldn't have gotten a randomly distributed sample from throughout the brain; I'd expect you to just cut out a small section that looks similar to the rest. That means that the results would apply only to whatever particular types of cells made it into the sample. Also, there's an important difference between simply cutting that sample into pieces and mixing it up, then seperating it into equal amounts. The second would be random (but might damage the cells), and the first would not. Unless you can ensure that the cells in the sample are identical (well, that the inevitable differences between them are negligible), which would be difficult, no statistical test can be really reliably performed. Black Carrot 16:07, 19 April 2006 (UTC)

Thanks! The neurone sampling was done by the technicians (I actually recon there are no neurones involved and they just did it with chemicals - a lot more predictable, cheaper and more suitable for a university experiment). If the results are insufficient to perform a statistical test, I'll just include this in my critical assesment of the experiment which is a lot easier for me!

When you mentioned result fudging (my result-fudging days are over I hope!) did you mean to infer that it goes on in the real world by actual research groups? If so, how frequently does this occur? And what are the motivations, aside from having an investment in the company selling a certain product?

The biggest fudge I ever did was to draw the graph I wanted, plot points around the line, take those points as my averages and make up three repeats that gave that mean average!! Those were the days... -Username132 (talk) 08:09, 23 April 2006 (UTC)

Chronology / Inability to locate events in time or to remember dates

I stumbled across an interesting phenomenon: While I was trying to locate a painting to a particular epoch, I asked a friend. This friend told me that she cannot remember dates and does not have the ability to juxtapose events in for example political history with events in art history. In other words, a poem written in 1917 in England would not remind her of WWI and a possible connection, although she has had several curriculi in which WWI was a topic. She coined it - amusingly - date dyslexia. Now I am asking myself if there is an official expression for this "condition". Please do not propose laziness. Thank you! Don420 19:10, 16 April 2006 (UTC)

I don't know, I am inclined to think laziness, or at least an inattentiveness to context. ;-) --Fastfission 21:35, 16 April 2006 (UTC)

I'm a little confused. Would she be able to recognize a painting as one of WWI, from the style and content (no dates involved)?  freshgavinΓΛĿЌ  05:02, 17 April 2006 (UTC)

Good point. Your question with regard to WWI may be a difficult one since the telltale signs will be predominantly technical - trenches, weapons, radios, gas-masks, tanks, etc. These are elements generally not of interest to her. During my initial surprise at the phenomenon, I asked "when did Picasso live and when was his influential work done?" - having had art history during her education as a photographer and graphic designer - she was not able to say. For the exams she took, she had to learn the dates by heart. At the moment she is working on a Jugendstil design, taking inspiration and researching in numerous books. When asked about the time Jugendstil was active, she could not say except early 20th century. Louis XIV, Biedermeier or Manerism - no clue as to the dates, but she may be able to recognize the styles without the ability to place them in a chronology. Don420 09:58, 17 April 2006 (UTC)

Then it sounds like she just has a serious problem remembering dates, which seems plausible enough. I still don't understand why she didn't get the poem was about WWI, if it included WWI details. The date 1917 doesn't really seem to relate. If you read me a poem written in 1917, I wouldn't be able to tell you when it was written either!  freshgavinΓΛĿЌ  06:54, 18 April 2006 (UTC)

It is probably just this simple, then... Thank you both for your time and help! Don420 09:13, 18 April 2006 (UTC)

One Line C Program Signatures

Hey There

I've seen around a lot some seriously funky 1 line C/C++ programs that are commonly found in signatures that when compiled produce a really nice pattern or shape, such as:

main(c,r){for(r=32;r;) printf(++c>31?c=!r--,"\n":c<r?" ":~c&r?" `":" #");}

Is there a name for these, and if so, does Wikipedia have an article on them, or does anyone know of a place that lists them? I'd really like to know as i find them extremely interesting and astonishing how one loop can produce such amazing results. Thanks :) -Benbread 21:46, 16 April 2006 (UTC)

Yes. That's mainly due to the language. In this particular case the ?: operator plays a vital role as it allows a single expression to replace a set of much verboser if-else. Also, implicit comparison with zero and operators precedence play a (minor) role. Just to give you an idea, a spelled out version of the program could be:

#include <stdio.h>
int main(){


    int c = 0;
    int r = 32;

    while (r != 0) {

        c = c + 1;
        if (c > 31) {
            c = !r;   /* same as c = 0 */
            r = r - 1;
            printf("\n");
        }
        else {
            if (c < r) {
                printf(" ");
            }
            else {
                if ((~c & r) != 0) {
                    printf(" `");
                }
                else {
                    printf(" #");
                }
            }
        }

    }
}

--Gennaro Prota 13:03, 17 April 2006 (UTC)

These are called signature programs, and there is no Wikipedia article on them (yet). One place with a list is http://www.iwriteiam.nl/SigProg.html. -- Rick Block (talk) 22:36, 16 April 2006 (UTC)

What a headbangingly obvious name. Thanks very much - I think i'll start working on that wikipedia article tomorrow (well, today, after i go to bed) -Benbread 23:13, 16 April 2006 (UTC)

Please, keep in mind however that most of these are pre-standard programs, more than often relying on the particular and possibly undocumented behavior of a particular compiler (usually gcc at the time of writing the program). In the best of the hypotheses they lack the necessary includes, but usually it's worse than that. The example above, besides lacking #include <stdio.h>, doesn't specify the return type in the declaration of main, has an absolutely non-standard "main(c,r)" incipit and other subtleties. And it would require a quite careful analysis to see if it doesn't invoke undefined behavior (note in particular the increment of c without initialization).

P.S.: I was almost forgetting... if you write an article on this, please, never write "C/C++". That expression makes many C and C++ programmers literally fly off the handle :)

--Gennaro Prota 12:40, 17 April 2006 (UTC)

I was just wondering...can you tell me what the output of the program would be.. I know a bit of C/C++ but i dont have the language on my computer to try it out..Thanks a lot. Jayant,17 Years, India • contribs 09:05, 17 April 2006 (UTC)

This is what the output of the above program looks like. -- Daverocks (talk) 11:51, 17 April 2006 (UTC)

Tech savvy teenagers! What would Wikipedia be without you? :-) See, it's this sort of stuff that makes it interesting to come back to the reference desk over and over and over! --HappyCamper 17:42, 17 April 2006 (UTC)

Thanks a lot for that!! and its a pretty cool program..i must admit...;-D ..Jayant,17 Years, India • contribs 19:06, 17 April 2006 (UTC)

BTW, it could be easily generalized. And a couple of changes would make it strictly portable (such as replacing ~c&r with (31-c)&r or in general (h-1-c)&r; note that I declared c as int and left ~c in my code: it was meant to be a faithful "rewording" of the original, not a fix). In any case I guess the intent was for r to start from 31; when it starts from 32 it will just produce an additional "all-space row" at the beginning.

P.S. for HappyCamper: if you liked this you might enjoy googling for "IOCCC" :)

Cheers. --Gennaro Prota 21:17, 17 April 2006 (UTC)

Excellent answers thanks - About the whole C/C++ thing, sorry about that, in my spare time i do write a little C++, but wasn't aware it annoyed many people to see the usage of the above, but I can see why. Thanks again, everyone, particually Gennaro Prota :) -Benbread 23:50, 17 April 2006 (UTC)

You are welcome :) About "C/C++" no need to apologise, I was just pointing out the mainstream attitude, so to speak, which you can read about at http://www.faqs.org/faqs/C-faq/learn/, under "What is C/C++?". In any case the best answer is that by Rick Block, I just went off at a tangent :) We could clean this up a bit for the archive. I was thinking to insert a brief introduction to Sierpinski triangles (or references, preferably internal to Wikipedia) and explain how the expression ~c&r originates, from a mathematical point of view. --Gennaro Prota 11:41, 18 April 2006 (UTC)

I've created the starting point of a Signature program article. Many thanks to everyone whos information has helped to make it. I've linked to this question in the talk page to show credit where it's due, as well as thanking some members personally. If you oppose to me rewriting some of your information (but it's public domain anyway) feel free to remove my information and repost it as your own. Thanks again for helping me and making wikipedia a better place :) -Benbread 16:41, 18 April 2006 (UTC)

I had a quick look. The overall style and prose is very good to me. Some details are wrong (for instance, such programs are rarely "optimized"; the example above for instance, outputs all the leading space of a line one after another, even if a single string of appropriate lenght could be printf'd in one shot); they are just "terse" (you could say they optimize (minimize) the number of keystrokes :)). But don't worry, I'll fix it in the next days. What matters is the overall structure which is IMHO very good. As to the example program I don't know if it is copyrighted or not and considered that it has some errors (such as not printing the last line of the triangle) I think I'll replace it with a correct version. If one doesn't care having a spurious space after the '#' that terminates each line it could be quickly fixed as here:

/* Pass a power of 4 as argument for h */
void print_it (unsigned h)
{
    const unsigned n=-1;
    unsigned c = n;
    signed   r = h-1;

    while (r>=0) printf(++c>=h?c=n,--r,"\n":c<r?" ":~c&r?"` ":"# ");
}

but of course it can still be improved. I'll try writing a version of my own without looking at external sources, so that we can't have copyright problems. Ah, I also moved the article, to conform to our usual naming convention ("Signature program", with a lowercase 'p'). And thanks to *you* for your good job :) --Gennaro Prota 18:22, 18 April 2006 (UTC)

Microsoft Excel

Is there a way so that I can write something in a cell without it continuing into next cell. It just stays in the cell you are typing in.

I don't have a copy of Excel available to me right now as I'm on a Linux system, but you should be able to choose Cell properties->Text format (or text alignment?)->wrap text, or something very similar, and any text which is too long for the cell will display over multiple lines. If the row height is standard, then you won't be able to see these lines, but you can adjust the row height should you wish. In OpenOffice.org, it's Format cells->alignment->Wrap text automatically, and you also have to choose Format cells->alignment->Vertical->top to get exactly the same result.

An alternative way of stopping long text in one cell from extending over the next (blank) one is to put a space in the next cell.

Is this what you wanted, or am I misunderstanding the question?-gadfium 23:20, 16 April 2006 (UTC)

It's under 'format cells', 'alignment' to wrap text. The other suggestion, putting invisible content in subsequent cells, will also work but is not recommended (most notably because excel deems any edited cell to be part of the: print area, edited area (for when you use the home/end keys to navigate, etc) and also for formula-related issues.--Anchoress 05:11, 17 April 2006 (UTC)

Thanks, I learned something too!-gadfium 05:30, 17 April 2006 (UTC)

No problem! If you ever have a short Excel spreadsheet that outputs pages of blank cells on printing, you may infer that at some point cells elsewhere in the sheet have been edited. Using the keystroke, 'CTRL+END' will take you to the bottom-right-most edited cell, which will give you an idea of where the extra edits might have occurred.--Anchoress 06:34, 17 April 2006 (UTC)

April 17

Ramjet Project

I have been for three days attempting to build and test a stationary ramjet with no luck, I have read the ramjet article twice but I am still confused on the construction of the ramjet. So I was wondering if anyone could point me in the right direction or give me a link that explains the construction of a ramjet? I am looking for things like types of fuel ignition methods and just bassically anything on ramjets. Thank You. Patrick Kreidt

For one thing, I thought "stationary ramjet" was an oxymoron. The design requires it to be moving very fast through some medium. —Keenan Pepper 00:43, 17 April 2006 (UTC)

I agree with Keenan Pepper. A ramjet is probably not what you want. The external links on pulse jet engines might be useful to you.-gadfium 01:52, 17 April 2006 (UTC)

Well it can be stationary if you have a constant airflow, but that isnt my problem.

Not to be useless, but I'd imagine it would be pretty difficult to find any specific instructions for building a ramjet, simply because it's not the kind of thing people build from kits and most of the plans would be either highly top-secret or simply confidential.  freshgavinΓΛĿЌ  04:54, 17 April 2006 (UTC)

Ramjet engines are not that hard to build and not top secret. Keenan is right in that it needs a flow of air to work. All you need for a stationary one is a large pipe with a one way valve at one end. Have some sort of pump to deliver a find mist of fuel inside, a fan to keep air pressure flowing through the valve and a sparker (like a spark plug) to ignite it. Don't blow yourself up.

I could be wrong, but I wasn't aware that companies like Boeing, NASA, etc., reveal the entire technicalities of their prototype designs.  freshgavinΓΛĿЌ  06:50, 18 April 2006 (UTC)

Thanks

Can a substance conduct heat well but not eletricity (and vice versa)

Title says it all, but if it is true could you explain how. It's not hw and any help would be apprecaited.

I believe epoxy was designed for just that. I just can't remember whether it's excellent at conducting heat but not electricity or the other way around. Loomis51 01:24, 17 April 2006 (UTC)

A material is electrically conductive if it contains charged particles that are free to move around, like electrons in a metal or ions in a salt solution. A material is thermally conductive if mechanical vibrations (heat) are quickly transferred. Diamond and deionized water are both thermal conductors but electrical insulators, because their particles are strongly attracted to each other and spread vibrations quickly, but there are no mobile charged particles to conduct electricity. I can't think of a good electrical conductor that is also a thermal insulator, but I can't say for sure there aren't any. It might be because the charged carriers also conduct heat... —Keenan Pepper 01:29, 17 April 2006 (UTC)

Thanks.

Possible. One of the best examples would be the mica used as electrical insulator but thermal conductor in the electric irons - Wikicheng 06:11, 17 April 2006 (UTC)

Good thermal conductivity without electrical conductivity is somewhat unusual. Try http://en.wikipedia.org/wiki/Beryllium, it talks about Berylium Oxide as having this property, but the Berylium Oxide article leaves it out.

Physics Problem

You place a 7.50 kg television set on a spring scale. if the scale read 78.4 N, what ist he acceleration of gravity at that location? Seems easy enough, I get an answer butr that isn't what the answer key "says". I went F = ma, F/m = a.... a = 10.45m/s/s.

The answer I'm given is 9.973m/s/s, and I have no idea how that's derived. Anyone know if I missed something or if I'm right? Thanks.

00:58, 17 April 2006 (UTC)

Perhaps a dyslexic teacher? As far as I can tell if the answer is 9.973 the scale should say 74.8N. -- Rick Block (talk) 01:22, 17 April 2006 (UTC)

Haha very nice. I have another question where I inexplicably get 312 instead of 321.....I'll assume it's right. Thanks.

01:30, 17 April 2006 (UTC)

Your answer is correct for the given problem. If m = 7.50 kg and F = 78.4 N the acceleration due to gravity is a = F / m = 10.45 ms^(-2) Cedars 10:22, 17 April 2006 (UTC)

Electromagnetic spectrum upside down?

Usually on a vertical scale the smallest number is on the bottom and the largest number is on the top or if the scale is horizontal the smallest number is on the left and the largest is on the right. The electromagnetic spectrum is always shown with the longest wavelengths (long electric waves, radio waves) on the bottom/left and the shortest wavelengths (X-rays, Gamma rays) on the top/right. I am wondering what is the scientific reason for doing this. Llarsson 01:20, 17 April 2006 (UTC)

I think it's probably due to increasing frequency (and therefore, energy) as you go up the scale. — Knowledge Seeker দ 01:24, 17 April 2006 (UTC)

It really doesn't matter. Frequency goes down as wavelength goes up, so either way you put it, one of the scales would go the "wrong" way. —Keenan Pepper 01:31, 17 April 2006 (UTC)

I understand that as wavelength increases, frequency decreases so one scale would go the "wrong" way. It seems to me though that since the electromagnetic spectrum shows waves and not frequency that one would lay out the scale to show wavelength increasing. Since it does not I wonder if it is more than just a 50-50 chance that it is laid out that way. Llarsson 01:50, 17 April 2006 (UTC)

As the whole spectrum is continuous, there's no real right or wrong way to view it. Luthinya 10:40, 17 April 2006 (UTC)

BitTorrent

I need help with BitTorrent.

I downloaded a file from a search and then downloaded BitTorrent and opened the file with the program. It's finished downloading and I don't know where to go now so that I can view the video.

Thanks.

When you opened the Torrent file, you told it where to download the file to. Remember where you saved it, and use that location to open the file. Simple. Here7ic 04:16, 17 April 2006 (UTC)

Never lose porno, especially not when it is on a computer that other people also use. Open your downloads window and click the button that reveals the file location that you downloaded. Assuming that you haven't cleared the list, or do not use internet explorer. -- Mac Davis] ⌇☢ ญƛ. 06:11, 17 April 2006 (UTC)

is there a name for the tendency to see patterns?

I seem to remember at some point learning a name for the principle that humans tend to see patterns in random data where there are no patterns. Constellations, inkblot tests, that sort of thing. I seem to think there is someone's name associated to it, like "someone's law" or "someone's principle". Searching on the internet for a while provided nothing, and I'm starting to think that maybe I'm imagining it. Is there such a name? -lethe ^{talk +} 03:35, 17 April 2006 (UTC)

Gestalt psychology? —Keenan Pepper 03:57, 17 April 2006 (UTC)

Ink blots are the Rorshasch test. Probably not what you seek. GangofOne 05:15, 17 April 2006 (UTC)

pareidolia --Femto 13:51, 17 April 2006 (UTC)

Also, the specific case where patterns of human behaviour are seen where none actually exist, is called anthropomorphization. That's the longest word I commonly use, BTW. StuRat 21:41, 17 April 2006 (UTC)

The question used the interesting phrase "where there are no patterns". Who says there are no patterns? Nobody has ever suggested that the Southern Cross was consciously designed to appear this way to people in the southern hemisphere of planet Earth, so it's just a random occurrence. But there's still a pattern there, because my brain says there is. To someone who can't discern the cross (and I know some people who just can't see it), there is no pattern. So is there a pattern there or not? It seems to depend on the viewer's perception. JackofOz 02:40, 18 April 2006 (UTC)

I would say the pattern is all in your mind. It's interesting how culture shapes the perception of patterns, as well. For example, the Big Dipper constellation looks like different things to different cultures. StuRat 02:00, 19 April 2006 (UTC)

All patterns are "all in the mind" of the observer, as your Big Dipper example demonstrates. All so-called reality is an illusion (albeit, as Einstein said, a very persistent one). JackofOz 02:28, 19 April 2006 (UTC)

I disagree. When looking at an actual large ladle, you really are looking at a "big dipper", not just imagining one (as when you look at collections of randomly located stars). StuRat 09:18, 20 April 2006 (UTC)

It doesn't matter what the constellation is called from culture to culture, or what individuals imagine it looks like. In the context of this question, all that matters is that humans tend to notice patterns in such things as random collection of stars. I'm not imputing anything divine or mystic in that, but to say "where there are no patterns" is to deny the experience of billions of humans over a vast period of time. And from a mathematical point of view, to suggest there are no patterns in a bunch of millions of randomly scattered stars in a particular field of view would be utterly absurd. It's a wonder humans haven't noticed far more patterns in the sky than they actually have; they're all there just waiting to be noticed. JackofOz 11:03, 21 April 2006 (UTC)

And there is a name for the tendency not to see patterns : atheism, or Darwinism. Also, written patterns are hard to decipher, so I'll add :) --DLL 19:40, 18 April 2006 (UTC)

I don't think there's a specific term for this other than pattern matching or pattern recognition. The human brain is hardwired to see patterns all over the place, it is a decent evolutionary advantage though it sometimes goes pretty haywire. --Fastfission 02:33, 20 April 2006 (UTC)

We're particularly good at seeing faces - so much so that we even once thought there may be a face on Mars. Some idiotspeople still think so. — QuantumEleven | (talk) 11:54, 20 April 2006 (UTC)

It wasn't anything like that, it was actually a pirated motion picture.

I seem to recall learning in a psychology class about a study where subjects listened to a steady beats of a certain sound. They naturally heard them as organized into groups of two or three even though the tones were in fact all at regular intervals. Can't seem to find mention of it on the internet. Will continue searching. -Wiccan Quagga 00:37, 23 April 2006 (UTC)

Temperature of innerstellar or innerplanetary space.

I'm probably missing something here, but I can't find the temperature of either spaces. Help? Here7ic 04:14, 17 April 2006 (UTC)

The space itself has no temperature, though you can measure it by placing objects into the space. Google says that the temperature of a perfectly conducting object at the distance of Earth from the sun will reach about 280K/7C, and you can expect objects at interstellar distances to experience near zero-K temperatures, though I'm not sure how near.  freshgavinΓΛĿЌ  04:45, 17 April 2006 (UTC)

Edit: Google also says that an object very far from galaxies and stars will probably reach a temperature of about 2.7K. Cold!  freshgavinΓΛĿЌ  04:46, 17 April 2006 (UTC)

The thing about temperature is that there has to be some matter for which you're measuring the temperature of. Temperature, at the molecular level, is basically the speed at which the molecules within matter move. Space, by definition, is a vacuum. It's devoid of matter. Therefore, no matter = no temperature. It's true, some will tell you that there may be fine dust particles in space, but then you'd be measuring the temperature of the dust particles, not the space itself. Others will say that the temperature of space is absolute zero, absolute zero (theoretically) being the state where the molecules within matter are absolutely motionless. But still, there must be matter to be measured. Space being a vacuum, there is no matter within which molecules are motionless, so absolute zero is not the answer either. Bottom line: difficult as it may be to explain or comprehend, space has no temperature. Loomis51 05:08, 17 April 2006 (UTC)

Have to disagree about the neccessity for the presence of matter. What you say seems plausible, but not true. Even matterless space is filled with electromagnetic radiation that has a characteristic spectrum, (Black body spectrum). This is what's left of the big bang, when things were hotter and closer together. After expansion, the temperature of space is now, as was said above, 2.7K. It is literally, "the echo of the Big Bang". The discoverers of this b.b. radiation got the Nobel prize. It shows up most prominently in the microwave frequecies. B.B. radiation is a fetish object for cosmologists, a lot can be determined cosmologically from studing it; the exact spectrum is known to be identical to a standard black body spectrum. Some recent satellites that study it are COBE and WMAP. If the space in question HAS a gas in it as well, the gas molecules will have a range of velocites in a certain distribution. It is computed that the e.m. radiation (better spoken of as photons) with a black body spectrum would hit gas molecules in just the right proportions to give them the velocity distribution that they indeed have. If you like, you can think of so-called "empty space" as a "photon gas"; this is not an eccentric concept in physics terminology, but a conventional one. The explanation of b.b. radiation started with Max Planck, and was the start of quantum theory, so it's a big deal, not a minor detail. (Of course if you happen to be near a star, then the photon stream is larger and you have a higher T, as Google says.) GangofOne 05:41, 17 April 2006 (UTC)

You're wrong. The definition of temperature is the average molecular kinetic energy of the matter within a given volume. No matter means no temperature, by definition.

Nor, for the record, has anyone pointed out the fact that space is not, in fact, a pure vacuum; space is actually a rather bad vacuum - there's all kinds of particulate matter there. (See here for the various measures of the density of space). We can produce much better vacuums on earth with relatively simple vacuum pumps. If space were a perfect vacuum, space-craft would not need heating systems (because there would be nothing to conduct heat from the aircraft into space). So, getting back to the question at hand, the 2.7 degree kelvin measurement is almost certainly a reference to the temperature of this interspacial matter. Raul654 06:08, 17 April 2006 (UTC)

(two edit conflicts) Temperature can be defined for lots of systems, including the electromagnetic field. Thermodynamics has come a long way since the ideal gas law. And in a perfect vacuum, you still radiate. Melchoir 06:17, 17 April 2006 (UTC)

No, Gang of One is right. The real definition of temperature has to do with the rate of change of entropy when you increase or decrease the internal energy; see thermodynamic temperature.

Spacecraft do not lose heat primarily by convection, but by radiation; there doesn't have to be anything touching them for them to get cold. See black body radiation. The 2.7 kelvin temperature refers to temperature of the black body background radiation of the universe, not to the interstellar medium per se. --Trovatore 06:17, 17 April 2006 (UTC)

Dang, it's a game of seconds out here! Melchoir 06:19, 17 April 2006 (UTC)

[Edit conflict, didn't read Raul's comment] You obviously know a lot more about what we're talking about than I do, so I'm sticking my foot out by saying that I find it hard to agree with you. I'm getting everything except the fact that you say the radiation left over from the big bang makes space itself 2.7K. It may be a semantic argument ... to experience or measure temperature (sense heat) requires absorption (loss) of heat in some way, and since space doesn't absorb heat or energy (as far as I know), I find it difficult to think that it could possibly have any, as you imply when you say the temperature of space is 2.7K. I'm having trouble finding the words but I feel like I'm dealing with a tree falling in the woods with nobody there to hear it.  freshgavinΓΛĿЌ  06:16, 17 April 2006 (UTC)

So I guess, in a sense, the vacuum does "absorb heat"; that is, you can add heat to the vacuum by increasing its content of photons in a distribution corresponding to the black-body law. See how much energy it takes to add those photons corresponding to a given increase in temperature, and you have a reasonable definition of the heat capacity of the vacuum. I think this is a standard notion but I'm a little out of my depth here; maybe Melchoir could explain it better. --Trovatore 06:28, 17 April 2006 (UTC)

Well... if you want to talk about the energy contributed by a new photon, that sounds like a chemical potential. (eh, I misread you) The volumetric heat capacity is pretty simple to define, though; it's just the temperature to the third power, modulo factors of c and hbar. Melchoir 06:55, 17 April 2006 (UTC)

Here is a link [2]. The temperatures of space differ greatly. Space near a star is a lot hotter than space far away from any galaxy. -- Mac Davis] ⌇☢ ญƛ. 06:15, 17 April 2006 (UTC)

Melchoir, I did specifically refer to the fact that within what we normally term "space" there are may indeed be particles. I suppose it's a matter of semantics. If you define space, as I do, as the absence of matter, then by definition, it's a vacuum. If there are stray particles, we're not strictly speaking about space anymore. Of course those particles have temperature. When I speak of "space", I speak of any area devoid of matter. In other words, Space=Vacuum, and Vacuum=no temperature. Loomis51 06:31, 17 April 2006 (UTC)

Actually, I have no problem with what you wrote. There's a bit of ambiguity about whether you're considering photons as matter, but we probably don't have to get into that. Melchoir 07:00, 17 April 2006 (UTC)

Okay, allow me to elaborate on my question to clear things up. What would the average surface temperature of the Earth be if it had no atmosphere and the sun was a white dwarf of, oh, .6 solar masses? Here7ic 06:49, 17 April 2006 (UTC)

I assume you'll also want to paint the Earth black and shut down its radioactivity? (Not that I feel like doing the work on this question, just saying.) Melchoir 07:03, 17 April 2006 (UTC)

Raul654 mentions the particles in space and says man-made vacuums are superior, which is wrong, terrestial vacuums are no where NEAR as good as space, as the link he provides even says: "Space is a nearly perfect vacuum, even better than the best ones made in labs on earth," (One complication that wasn't mentioned was that the black body spectrum refers to "thermodymanic equilibrium", the state without macroscopic changes. There are cosmic rays and stuff moving through space that are NOT in equilibrium. Just mentioning that in passing.) The link from the straightdope that MacDavis provided is excellent. And now, an experiment. A thought experiment. Let's consider a region of space that is a perfect vacuum that is in a chamber. That is, an enclosed space that is a vacuum. The walls are obviously made of matter; but the matter is AT SOME TEMPERATURE. Let's say we have a regular themometer, made of materials suitable for the temperatures we are about to measure. The bulb is painted black. The thermometer extends into the chamber, and it's readings can be recorded somehow. So, heat up the box to 2000 deg. C so that the walls of the chamber are at 2000degC. Remember, it's a perfect vacuum. (And the themometer is isulated from the sides of the chamber.) What temperature does the thermometer read? Absolute 0, -273degC, ie no temperature? As you change the T of the walls of the chamber, from the lowest to the highest, what temperature does the thermometer read? Is it plausible that it is absolute zero? --GangofOne 07:22, 17 April 2006 (UTC)

freshgavin says "...and since space doesn't absorb heat or energy (as far as I know)..." Well, let's say you shine a flashlight toward the Big Dipper. Energy came out of the flashlight, and it went somewhere. It went into space. So space absorbed it. The sun shines. The light that came off the sun isn't on the sun. It's in space now. So space "absorbed" it. So at the big bang, when the universe was as small a point as you can conceive, it was really hot, but then is expanded out, and the energy that made it hot was spread around as the size of the universe became larger, so the INTENSITY of the heat at a given spot became less, ie it cooled. It's expanded so much that the temperature of the energy that was in the big bang is now a uniform 2.7K. At least that's what the cosmologists say, anyway. It's some pretty mind streching stuff. --GangofOne 07:51, 17 April 2006 (UTC)

A true vacuum would only transmit heat, not absorb it. That is, while radiation could pass thru it, there would be nothing in it to absorb the heat. So, eventually that flashlight beam will heat some distant matter, depending on whether you believe in a collapsing universe, etc. Also note that space has a very low density of matter, so has a low, but not zero, capacity to store heat. So, you could heat up a large volume of space with very little energy. StuRat 21:20, 17 April 2006 (UTC)

Yes, though I'm not sure which side StuRat is supporting. I still don't really get you GangofOne. If you shine a light through me, or any other type of matter, I experience a slight increase in temperature, I may even be able to feel it, and much of the light is reflected but almost none of it goes through to the other side of me. There is a noticeable loss of energy as the light beam hits me. If you shine that same flashlight into vacuumed space, the beam travels through and there is no loss of energy so I don't see how you can use the word "absorbed".
Someone said that temperature had to do with "the rate of change of entropy when you increase or decrease the internal energy", but the article he linked to states simply that temperature is the relative molecular activity, which would support the fact that temperature doesn't exist in a vacuum.
I do believe what you say about constant levels of b.b. radition, but I would consider those as potential temperature, or unabsorbed energy. There's probably a more scientific way to say that : [.  freshgavinΓΛĿЌ  06:47, 18 April 2006 (UTC)

Light is energy. When the light leaves the flashlight it enters the space. That's all I mean by absorb. Just what thing has it.

The article you refer to thermodynamic temperature Says: "Strictly speaking, the temperature of a system is well-defined only if its particles (atoms, molecules, electrons, photons) are at equilibrium." Note that it is allowing the case where the "particles" are photons and only photons; "electromagnetic radiation" is the older way to express what is also called photons. Conventionally, they aren't considered "matter" (although if you did, the problem in question would define itself away, because the so-called vacuum now has "particles" in it.) Anyway, I feel I have to somehow to convey to you is that "empty space" with no light going through it is different from "empty space" with light going through it. In the later case, the space has energy that's not in the former. And if it's in the special case of "thermodynamic equilibrium" then it has a well defined number which characterises its intensity, know as its 'temperature'. What your intuitions is telling you (when you say "I would consider those as potential temperature, or unabsorbed energy.") is that without matter there, there is no temperature. What I am attempting to convey is that just the presense of photons and nothing else, has a temperature. In the thought experiment above I attempted to make it more intuitive by considering a closed evacuated cavity. It has a well defined temperature that you can measure. You can stick your hand in and sense it. A thermometer isolated from the sides reads the same temperature as a thermometer measuring the side of the cavity. The only connection of the thermometers is via the photons. (This cavity I discribe is the paradigmatic black body that's in all the textbooks.) Try me again if still obscure. GangofOne 07:27, 18 April 2006 (UTC)

Yes, you're making yourself perfectly clear. Like I said above this seems much like an argument in semantics. Even your vaccuum box thought experiment could be argued by me as containing unabsorbed energy that is absorbed by the walls and the thermometer thus bringing about a non-zero temperature. It could just as easily be argued your way. I guess that's one reason why people want to figure out if photons should be considered matter or not.  freshgavinΓΛĿЌ  05:43, 19 April 2006 (UTC)

Street Lights

Would anyone know how bright a basic street light is in lumens? Not a traffic light but one of those lights that illuminate streets and highways after dark. I'm sure they're not all the same, so a reasonable range would do quite fine. Thanks! Loomis51 04:43, 17 April 2006 (UTC)

According to this site.. its says that a good street light is 20 lumens per square meter (or 1.2 candela per square meter) while for a poor street light is 0.1 lumens per square meter (or 0.006 candela per square meter).... Hope that helped... :-D .... Jayant,17 Years, India • contribs 09:12, 17 April 2006 (UTC)

Once again, Jayant, your level of knowledge is beyond mine. I'm not sure what to make of the "per square meter" part. From what I understand, 20 lumens is not very bright at all ... it's about the brightness of a flashlight if my information is correct.

I know you've been very generous with your time, but the information I need is:

1) What type of bulb is in a standard street light. Incandesent? Fluoresent? 2) How much brightness does it produce? 3) How many watts of energy does it require?

Thanks again! Loomis51 17:25, 17 April 2006 (UTC)

I can understand your confusion in understanding the units... The brightness of a light source is measured in Illuminance which is lumens per meter square... generally when we normally use lumens, we actually mean lumens per meter square...but we unwittingly drop the per meter square part... and i think the 20 lumens (per square meter) is wrong.... and i also think i might have found out the answers for all the other questions as well.... Here it goes...

1) According to the article Street light, Today, street lighting is most commonly achieved using high-intensity discharge lamps, often sodium vapor lamps. Such lamps provide the greatest amount of illumination for the least consumption of electricity.

2) & 3) I had a bit of trouble finding about the brightness of a street lamp since brightness is a vague term...nevertheless, i found this site which lists the brightness and the wattage required for different lamps in a table...it also lists some extra information as well... i think you would be more interested in the metal halide and the low and high pressure sodium lamps as they are the most commonly used nowadays...

I hope that you find that information helpful...and i once again apologise for the 20 lumens per meter square information... If you have anymore questions please dont hesitate to ask me..Cheers!! Jayant,17 Years, India • contribs 18:35, 17 April 2006 (UTC)

I believe the confusion here is that the asker asked how bright the light SOURCE is, which would be in lumens, and the reply was in terms of how brightly the street was lit, which would be in lumens per square meter. The height of the light, among other things, would effect the density of light on the street, even when the brightness of the light source is held constant. StuRat 20:39, 17 April 2006 (UTC)

Thanks again, Jayant. (Thanks to StuRat too.) I'll need some time to digest all this information so I probably won't bother you with more questions until I have all this figured out more or less in my head.Loomis51 00:56, 18 April 2006 (UTC)

It works like this. Briefly, you get a certain amount of light out of the bulb: a certain number of lumens to play with. Now, when you're illuminating something – a street, for example – that light gets spread out over a certain area. If you mount the lamp up higher, you can illuminate a larger area, but each unit of area gets a smaller fraction of your total light. The amount of light each unit of area receives is measured in lumens per square meter; it tells you how brightly illuminated a given patch of ground is.

The metal halide and sodium vapour lamps used for street lighting range in brightness from a few thousand to upwards of a hundred thousand lumens, depending on the location and application. A 100 watt incandescent light bulb, for reference, delivers about 1700 lumens. You may find these tables useful: [3]. TenOfAllTrades(talk) 01:29, 18 April 2006 (UTC)

If you want a little more information, I can add that, at least here in my home state the illumination guidelines for the level of illumination on the road surface is recommended to be an average of about 0.6 foot-candles to about 1.5 foot-candles. It depends on the function of the road (residential, arterial, highway/freeway).

I can also bring home a table of lamp wattage and lumen output and add it here tomorrow. One that I can remember off the top of my head is that a 200 Watt lamp has an output of 22,000 lumens. In design practice the output is depreciated to 62% of that. The two depreciation factors are first that a lamp will gradually decrease in output over its lifetime, and also that the fixture will become dirty over the life of the lamp. The heating and cooling cycles cause the fixture to breathe, and dirt accumulates on the lamp and the reflector. So a design that requires 0.6 fc on a roadway using 200W lamps will actually be illuminated to a higher level when everything is brand new, but the average illumination over the lifetime of the system will be closer to the design target value.

HPS bulb output values:

Historically Traffic Ops used values which were reduced to 62% of total output, to account for ballast and dirt depreciation. Newer analysis software handles the depreciation automatically, so the full initial light output value must be known.

The total Lamp Lumen Factor (also called Maintenance Factor) is calculated as:

           LLF = LLD x LDD x BF

                       LLD = Lamp Lumen Depreciation, = 73%

                       LDD = Lamp Dirt Depreciation = 85%

                       BF = Ballast Fac tor

           LLF = 73% x 85% = 62%

Lamp size, Watts

Lumens (full output) 
Lumens (reduced to 62%)

100 W 8900 5500

150 W 16000 9920

175 W

200 W 22000 13640

250 W 275000 17050

310 W 37000 22950

400 W 49000 30400

Luminaire classifications:

Short – Medium – Long

Cutoff- Semi-cutoff – Non-cutoff

Type II – Type III – Type IV

Short, Medium, and Long refer to how far light is directed up and down the roadway.  Guidelines for use: Spacings given as multiples of the mounting height (MH)

Short: 4.5 MH

Medium: 7.5 MH

Long: 12.0 MH

Cutoff describes how much glare is to be expected from the fixture.

Type II, III, and IV designations indicate how far the fixture directs light across the width of the roadway. Type II = narrow, and Type IV is widest.

Lamp mounting height: Wattage Mounting height (ft)

70 15 100 20 200 25 250 30 310 35 400 40

Lighting conversion formulae: Lumens / sq. ft. = Ft-Candles

Ft-Candles x 10.7639 = Lux Lux x 0.0929 = Ft-Candles

Illuminating Engineering Society of North America

www.iesna.org

Roadway Lighting, book no. RP-8-00

Electric Charges

Why does positive charge attracts negative charge and negative charge repels negative charge? I know it does but why? Does it have something to do with Quantum Electrodynamics?

It sure does! In quantum field theory, like charges attract if they couple to a spin-0 or spin-2 field, and they repel if they couple to a spin-1 field. The photon of quantum electrodynamics is a spin-1 particle, so like electric charges repel. The graviton is a spin-2 particle, so masses attract. Melchoir 07:30, 17 April 2006 (UTC)

Thanks for replying but what does couple mean? Also I'm a bit confused when you say spin-0 and stuff but thanks anyway!

• how come photons has to do with electric charges?

Some of the terminology is explained a bit at Coupling (physics) and Scalar field. Photons are the carriers of the electromagnetic force, so electric charges interact by exchanging photons. It takes years to learn all the subtleties behind these concepts, and I'm not quite there yet! Melchoir 18:51, 17 April 2006 (UTC)

The simplest illustration (that I'm aware of) of the relationship between spin and attraction/repulsion is in chapter I of Anthony Zee's Quantum Field Theory in a Nutshell. The book, although likely the simplest text on Quantum Field Theory, is by no means accessible to a general audience—and it looks (from skimming the section) like it relies on the particular forms of the scalar, photon, and graviton propagators—so I fear there's no way to explain this phenomenon convincingly in words. -- SCZenz 23:48, 17 April 2006 (UTC)

Word. It's also at the end of Peskin and Schroeder ch.4. Melchoir 00:16, 18 April 2006 (UTC)

Mozilla Firefox

I use Firefox and I want to conserve my "Favourites" list. How can I save it somehow? (I have a complicated structure with overlapping bookmarks in different folders.) Thanks! ttse92

Click on 'Favourites/Bookmarks', then click 'Manage favourites/bookmarks' - a window should open. In it, in the menu bar, click File -> Export.

I hope this is accurate, I'm re-translating Firefox from Polish into English right now :) --Ouro 08:47, 17 April 2006 (UTC)

Right got that thanks!

Alcohol and medicine

Is it safe to consume alcohol while taking prescribed medication ? Some people tell me that the alcohol dilutes the medication and flushes it out of my system too soon for it to have any worthwile effect, while others say it agravates the illness and make it worse. Yet others wil say it makes no difference. Can you please clarify this for me ?

It depends on what kind of medicine you are taking, the type and why you are taking it. In general, it is advisable to avoid alcohol consumption during medical treatment. Alcohol may have a different effect on anything you take, depending on the chemical structure of the medicine. Always read the label. --Ouro 08:50, 17 April 2006 (UTC)

Generic redundant answer. You really should consult your physician or pharmacist before consuming alcohol with your specific medication. Some medications do not react with alcohol and some do. Also an interaction could possibly be caused by multiple medications with alcohol. Only your doctor or pharmacist knows what medications you are on, and which interactions should give you worry.--Tollwutig 14:23, 17 April 2006 (UTC)

You didn't say what kind of medication you're taking, so I can't help you. Erik the Rude 16:12, 17 April 2006 (UTC)

If you ask this question to a medical professional they will look up both drugs (alcohol and whatever else it is) in a huge table of known drug interactions and contraindications. For great justice. 18:30, 17 April 2006 (UTC)

Another factor not mentioned above is that some medications have their first pass through the liver - the same route to the bloodstream used by alcohol. If the liver is busy with one task it can be far less effective on the other - or worse, you can overstress your liver, not something you want to contemplate. This is even true with some simple household medications (ISTR paracetamol and alcohol is a very bad combination, for instance). But in any case, without knowing what the drugs are, we're left with generic answers, and even if we knew the type of drug our advice would be nowhere near as good as advice your doctor or pharmacist could give. Pop into your local chemist's/pharmacist's and ask there. Grutness...wha? 01:45, 18 April 2006 (UTC)

Thank you all for your kind contributions and explanations. I was recently prescribed Co-Amoxiclav Tablets BP (500/125mg) for 5 days for a bad phlegm-producing cough and slight elevation in temperature accompanied by aches and pains, runny nose and sore/inflamed throat from the coughing. I have not started to flap my arms yet !! The doctor also gave me cough syrup to get rid of the phlegm and Paracetemol for the aches and pains and to reduce inflamation. When I asked the doc about alcohol I was told it differs with patient's strength, mental wellbeing and tollerance of the medication and the strength and type of alcohol. I avoided the alcohol but was always curious as to why we were given different advise from different people especially those non-doctors who advocate hot whiskey with sugar and lemon while yet others recommend a glass of red wine daily regardless of doctors orders. Once again thank you all for your advise. - Futiwali

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Complementary to the answers already provided, alcohol/medication combination issues can be explained in a large part by drug-drug interaction. One of the main components of drug metabolism is the liver. What makes the liver so special is that it contains a wide variety of enzymes in the cytochrome P450 family. (You can find here everything you ever want to know about P450 enzymes.)

More specifically, alcohol (i.e. ethanol) is metabolized in the liver by the CYP2E1 (or cytochrome P450 allele 2E1) enzyme. At any given time, your liver has only a limited reserve of CYP2E1, so when you consume alcohol, a significant quantity of this enzyme is used to metabolize the ethanol. Say that at the same time, you take a drug that also needs the same enzyme for its metabolism, for example acetaminophen (or Tylenol). You can now see the problem: alcohol mixed with Tylenol will deplete your liver of CYP2E1 thus letting through a toxic quantity of ethanol and acetaminophen, which is not healthy. The complete drug metabolism process is much more complex, of course, but I hope that this can illustrate the mechanism involved.--JLdesAlpins 23:24, 19 April 2006 (UTC)

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How do people lose mass?

When someone loses weight, how exactly does it leave the body? It seems unlikely that it's moved from fat cells or whatnot into the digestive tract; are waste chemicals from fat metabolism filtered through the kidneys and urinated out? Is the carbon bonded to oxygen and breathed out as CO2? grendel|khan 09:16, 17 April 2006 (UTC)

The fat cells contribute a lot of the weight of the human body..so when you are exercising, the fat gets converted into energy...so the weight of the body decreases... Jayant,17 Years, India • contribs 09:26, 17 April 2006 (UTC)

What, like e=mc^2 converted to energy? Given the figure of 3500 kCal per pound of human mass gained or lost that I've been given (around 15 MJ), compared to the energy in that mass were it actually converted into energy (around 4.1*10^10 MJ), you're about nine orders of magnitude off. I don't think it works like that. grendel|khan 10:48, 17 April 2006 (UTC)

This is not true. Mass is only converted to energy in a nuclear reaction. In the body, fat is broken down into fatty acids through the process of catabolism. This involves chemical reactions that release chemical potential energy. I believe these fatty acids are then passed out through the body as urine or excrement. I believe this is the correct explaination but I am not sure - I just wanted to correct the perception that fat is converted directly to energy and this reduces a person's mass. Cedars 10:51, 17 April 2006 (UTC)

(Edit conflit with Cedars) Um, no. e=mc^2 only applies to nuclear reactions (a nuclear reaction is one where the nucleus of an atom changes). Fats (adipose tissue) store energy in the form of chemical bonds. Breaking those bonds (and discharing the left-over waste molecules) is how the body loses weight. Raul654 10:51, 17 April 2006 (UTC)

Um, no. E=mc^2 applies perfectly well to chemical reactions. It is just not a significant effect given the amounts of energy involved in breaking and forming chemical bonds. Relativistic effects are significant for heavy-element chemistry though, as the innermost electrons of atoms with high nuclear charges move fast enough to have a significant relativistic mass. Which in turn leads to a contraction of the atomic radius. A practical example is the color of gold. An energy level difference which otherwise (and in lighter metals) would be in the UV range is shifted down to blue part of the spectrum. Leading to absorption of blue light and the yellowish color. Now, to answer the original question here: The main products of fat metabolism is CO2 and water - I think you can guess the respective ways those leave the body. --BluePlatypus 12:29, 17 April 2006 (UTC)

Um but cellular respiration does not include many heavy metals. Thankfully you did answer the question. Fat metabolism creates water and fatty acides. Cellular respiration of those fatty acids creats CO2 and more water. Molecularly water is rather heavy. Generally the human bladder which holds only several fluid ounces can at the same time hold half a pound of weight. (Want to know how much you bladder holds. Measure yourself with a digital scale before and after urinating.) --Tollwutig 14:30, 17 April 2006 (UTC)

Nobody said cellular respiration included heavy metals. I was making the point that relativistic effects do occur in chemistry. I didn't say that you needed heavy metals for the energy of a chemical reaction to lead to a E=mc^2 loss of mass. All chemical reactions give that loss of mass, it's just not significant, as I said. That particular relativistic effect is not more significant for heavy elements than for light ones, because the electrons involved in chemical reactions are the outermost (valence) electrons, not the innermost ones. In fact, that effect is smaller for heavy elements, because their valence electrons have lower kinetic energy than those of light elements. (Also, water isn't particularily heavy in a physiological perspective. The density of the human body is very close to that of water, since we're mostly made of it) --BluePlatypus 19:05, 17 April 2006 (UTC)

So all the relativity stuff is fascinating, but the answer to the original question is, yes, the fat gets oxidized and thereby converted to CO2 and water, which is disposed of in the usual ways, through the lungs, skin, and excretory organs. That overwhelmingly accounts for the accounts-payable side of the mass-balance ledger; the loss of mass corresponding to chemical energy is a negligible effect. --Trovatore 19:11, 17 April 2006 (UTC)

Why are there no EOS-compatible third-party camera bodies?

There are a variety of third-party EF lens mount camera lenses available from manufacturers like Tamron or Sigma, made to fit the Canon EOS system, specifically Canon EOS cameras. The EF lens mount uses an electrical-only system to adjust the aperture and focus from the body. (There's a nice picture

First, why can't I find any information about the electrical properties or data structures used by those electrical contacts? Are all third-party lens manufacturers under NDA with Canon? Why would they not make these specifications public?

Secondly, why are there third-party lenses manufactured, but not third-party camera bodies? I've seen interest in things like monochrome-only sensors (getting black and white from a color sensor involves dealing with the Bayer filter and interpolation), or in-body image stabilization, or real-time previewing, the last two of which are available in other SLR bodies, just not the ones that Canon makes. So why doesn't Sigma or Tamron make an EF-compatible body? grendel|khan 10:40, 17 April 2006 (UTC)

Perhaps it's because of licensing and patents? Obviously Canon don't want other manufacturers using Canon's technology to sell their competitors' cameras. Perhaps (I'm guessing) the vital, patentable parts of the EF mount system are all in the body, while making EF-compatible lenses is just a matter of "coincidentally" having the contacts in the right place on your lens. Alternatively, perhaps Canon make their money selling cameras, and don't make so much on their lenses. Then they'd have an interest in allowing third parties to produce lenses, so making their cameras more attractive propositions. Henry^Flower 12:23, 17 April 2006 (UTC)

Could any patents on the original lens design be in effect? The spec was released in 1987 (according to Canon EF lens mount), so that any patents would be at least nineteen years old now. I'm sure they have new patents on image stabilization and diffractive optics, or whatever their shiny new toys are, but the mount itself can't still be under patent, can it? grendel|khan 02:44, 18 April 2006 (UTC)

Another posibile reason why the lens specs aren't available is that if the third-party manufacturers don't get any specs from Canon then they will have spent time and money reverse engineering the spec and don't want their competitors benefiting from their work and so are keeping their (reverse engineered) specs secret. -- AJR | Talk 23:42, 17 April 2006 (UTC)

First use of taps/faucets

When did taps/faucets first become used in domestic settings in Europe? ~M Cain

Hint : the french name is robinet, and the same in Bahasa, Galego and Greek. It's coming from Robin, a person name and the name of the lamb in the chanson de Renard, which (the story) gave names to other animals, as renard (fox), that was goupil (latin vulpes) before.

So ... the object came after the period when family names were formed. --DLL 19:34, 18 April 2006 (UTC)

Eh, what? That makes no sense to me. Anyway, the palace of Knossos had plumbing a few thousand years ago, and the Romans also had plumbing (the word refers to that- since Romans used lead pipes, 'plumbum' being lead.). --BluePlatypus 20:16, 19 April 2006 (UTC)

Comment about a Wikipedia Science Entry

The Wikipedia entry for Paracelsus makes no mention of the fact that Paracelsus invented a medical term. Specifically, Paracelsus invented the term 'synovia'. Credit is given to Paracelsus for inventing the medical term 'synovia' in the Definition given at the following URL: http://www.medterms.com/script/main/art.asp?articlekey=5684.

If you would, please examine the given URL references and update your various Wikipedia Online Resources accordingly. —The preceding unsigned comment was added by 66.24.11.3 (talk • contribs) 12:55, 17 April 2006.

Interesting! I don't think that's a reliable source, but you can always bring it up on Talk:Paracelsus or Talk:Synovium and see what others think. Melchoir 20:07, 17 April 2006 (UTC)

Why does Cola go flat quicker in a mug than in a glass?

I, and a few friends, have noticed that Cola and, to a lesser extent, other fizzy drinks seem to lose their "fizz" quicker when you pour them into a ceramic mug than when they are in a glass. We thought initially it was the thickness of the vessel that made the difference as mugs are generally thicker than glass tumblers. But when a very thick glass tankard is used the drink still stays fizzy.

I thought it might be something to do with the amount of imperfections in the glaze on the ceramic mug compared to those in the glass.

I'm sure my friend's nonesensical suggestion that the bubbles can't 'see' out of a ceramic mug and therefore get scared and pop quicker, is not the answer. So can anyone offer a sensible solution? --Ukdan999 16:54, 17 April 2006 (UTC)

I guess maybe its because the carbon-di-oxide in the coke reacts with the ceramic and the coke becomes flat faster...or it could be because of the ceramic mug is porous and it might allow the gas to escape out of its walls... Jayant,17 Years, India • contribs

I don't know the answer, but I think you are on the right track to wonder about the "imperfections" in the glaze. The bubbles tend to form around nucleation sites, typically any sort of relatively rougher surface. As an extreme example, my hypothesis is that if you poured coca cola into a cup lined with sandpaper, it would go flat much much quicker. As an aside, there were experiments done with boiling water - the behaviour of boiling is quite different if water is boiled in a nearly perfectly smooth container...but this is a digression. --HappyCamper 17:38, 17 April 2006 (UTC)

While not a total answer probably it has something to do with this http://www.coolquiz.com/trivia/explain/docs/drinks.asp . The porous nature of ceramic would allow more CO2 to escape through the sides than glass.--Tollwutig 17:45, 17 April 2006 (UTC)

Would the ceramic still be porous even though it is glazed? --Ukdan999 18:31, 17 April 2006 (UTC)

I think the much more plausible explanation is that your mug is wider than the glass, which provides more surface area, which lets the gas escape faster. I doubt it's a chemical reaction - both glass and ceramic materials are inert, at least with respect to the contents of a soft-drink. The nucleation-site idea is a thought, but a glazed ceramic surface isn't really much less smooth than a glass one. --BluePlatypus 18:53, 17 April 2006 (UTC)

I don't think it's down to the surface area as the effect still happens when I use a ceramic mug and an almost identically-sized glass/pyrex mug. Even using a very wide glass tankard, the coke still stays fizzy longer than when it's in a standard coffee/tea mug. --Ukdan999 19:15, 17 April 2006 (UTC)

Let me suggest a psychological reason. Since you see the bubbles on the sides of a glass container, it seems "fizzier" than if in an opaque container where you can't see the sides. This effect would be more pronounced with an opaque liquid. I suggest you try a clear carbonated beverage and see if this reduces the effect. Also, try evaluating the "fizziness" while blindfolded, to try to mask this effect. StuRat 20:20, 17 April 2006 (UTC)

I think the key is in HappyCamper's answer; the idea of a reaction surface or nucleation site is often used in chemistry - in my chemistry class we found that the reactions were faster in scratched glassware as there was somewhere that the reaction could occur.

While I agree that a rougher surface will provide more nucleation sites, I don't agree that glazed ceramics are rougher than glass. StuRat 22:20, 17 April 2006 (UTC)

The answer is definitely because of nucleation sites--once bubbles begin to form at a rough point in the surface, they draw more C0² molecules to the site. The bubbles grow larger and soon attain enough buoyancy to break free and rise to the top. This process continues until the soda reaches equilibrium; with many more nucleation sites, the soda goes flat much quicker. Your typical ceramic mug is much rougher than glass. As an example of this in action, if you were to drop a Mentos in a soda, for instance, the soda will boil over releasing its CO2 in a flash because Mentos provide an incredibly rough surface area, and as it quickly melts away, it's constantly exposing more nucleation sites for the gas to come out of solution.--Fuhghettaboutit 22:33, 17 April 2006 (UTC)

I think it might be because the ceramic is rougher, than the glass and thus has more nucleation sites, there is more surface area, and the roughness is prime. Oh, Fugettaboutit already said that. -- Mac Davis] ⌇☢ ญƛ. 05:19, 18 April 2006 (UTC)

The fact that you believe the effect is more pronounced with coke than with clear fizzy drinks prompts me to side with StuRat on this. Sounds like you're a victim of the placebo effect.  freshgavinΓΛĿЌ  06:27, 18 April 2006 (UTC)

Admittedly I haven't tried this with other fizzy drinks - not recently at least - but I really don't think placebo is involved as the difference between the mug and the glass is very clear. --Ukdan999 21:19, 19 April 2006 (UTC)

A mystery chemical...

I've heard that there is a chemical you can taste or not taste based on genetics.

In fact, I've been in an expiriment where this had happened. The Science class went around to the other classes at the school with pieces of paper with the chemical on it. They gave a piece of paper to each of us, and asked us if we could taste it. Unfortunately, I could. I remember the chemical having an intense bitter taste.

Does anybody here know what chemical this is? Thanks in advance. --P. B. Mann 17:27, 17 April 2006 (UTC)

Ah yes, that chemical is PTC, or phenylthiocarbamide. --HappyCamper 17:33, 17 April 2006 (UTC)

I've heard/read (possibly even on this very website) that some people are unable to taste or smell cyanide due to a certain gene. --Ukdan999 18:35, 17 April 2006 (UTC)

In regard to the cyanide answer, for people who can smell it, it smells like walnuts or other assorted nuts. Very helpful for a person who conducts autopsys on a regular basis.

That's the one. Thanks HappyCamper! --P. B. Mann 18:45, 17 April 2006 (UTC)

Geez, I sure hope they weren't giving you cyanide in class, that's poisonous ! I've also heard that Asians have receptors to taste monosodium glutamate which the rest of us lack. StuRat 20:10, 17 April 2006 (UTC)

heh --Froth 21:44, 17 April 2006 (UTC)

Umami? Nah. It's only that in East Asia they have a name for the savory flavour. All humans have the protein receptor in their tongues. C'mon, mostly everyone here will have tasted broth. Dr Zak 19:58, 19 April 2006 (UTC)

There's also the so-called Asparagus Gene. Asparagus makes urine smell different. Sometimes. But scientists don't know if the reason why only some asparagus-y urine smells different is because only some people possess the genetic ability to process the asparagus into the odd smell, or if it is because only some people possess the genetic ability to smell asparagus-y urine.--Anchoress 02:21, 18 April 2006 (UTC)

I would say there is a smelly chemical in asparagus which is not broken down, but comes out in urine smelling the same. You could just have people smell other people's "asparagus urine" to determine if some people lack the smelly urine or if some lack the ability to smell it. StuRat 03:31, 19 April 2006 (UTC)

• I believe this experiment was in fact done. The results, if I recall, were that some people produce the Asparagus Urine Scent, and others don't. Meanwhile, some people - not necessarily the same people - can smell the Asparagus Urine Scent, and others can't. The experiment was mentioned in a book, maybe one by Ira Flatow. -- Filliam H Muffman 20:17, 21 April 2006 (UTC)

Smartness

Is smartness innate, or is something that can change? The word, smartness, seems so subjective and imaginary. Is there any scientific definition of smartness? I am working on a topic about the smartness of nowadays people. I can only think of one agreement, income is direct proportional to intelligence. Does anyone have any suggestions of agreement, that can find data to support it instead of theoretical support?

Are you speaking of IQ or general knowledge? IQ of an individual while it varies is usually relatively the same. (Someone with a Low IQ isn't likely to become a genius, and unless there is physical damage someone with a high IQ usually doesn't dramatically lower their IQ.) Children do tend to have a higher ability to learn than adults. As for overall knowledge this can vary greatly, depending on IQ, age, education level, and socio-economical background.--Tollwutig 17:54, 17 April 2006 (UTC)

Actually, my exact topic is "are people getting smarter?" and this is a statistical project, so I do not specifically talk about IQ or general knowledge. What I asked to do is finding agreements and related data to support my answer to the question. At first, I thought about finding data of IQ score, but most of the data of IQ score I can find is estimated. Now, I am working on income, if people earn more money, they are possibly smarter. So is there any suggestions of things like income that have a relationship with smartness?

Again define your concept of smartness. This is the problem with your question. Undoubtedly dealing with financial issues, Richer people are smarter, but can those same rich people say fix a computer, or their automobile? Both of which require a good bit of smartness, both in knowledge and logical thought processes, but are not going to be as rich as a CEO per se. Smartness comes in different forms. And I do not think wealth is a good indicator of smartness.-Tollwutig 18:26, 17 April 2006 (UTC)

Other than wealth and education level, any suggestion of being a good indicator of smartness? Thanks.

IQ is your best bet, but there are still problems. There just isn't a really good mathematical statistic for how smart someone is as different people learn differently, and have different affinities for how and what they learn. --Tollwutig 19:36, 17 April 2006 (UTC)

IQ is okay for some purposes, but it's always being normalised, so it won't be of much help if you want to determine a population's average trend in intelligence over time. Tollwutig O questioner, were you given "are people getting smarter?" as a project, or did you choose it? If it's the latter, I'd actually advise you to change your project to something a little more concrete. Melchoir 20:49, 17 April 2006 (UTC)

Start here: The Bell Curve. WAS 4.250 21:04, 17 April 2006 (UTC)

I can't believe nobody's mentioned the Flynn effect. Oh, and the Bell Curve is an enormously controversial book. --Robert Merkel 21:33, 17 April 2006 (UTC)

Smartness can also be interpreted as how you use what you have to achieve a satisfying life. Last year The Economist had an article about their own measurement of what they called a Quality of Life Index. One could argue that A is smarter than B because she achieves a better QOL with the same resources, (or the same QOL with fewer resources). Maybe the figures required for such calculations would be easier to lay your hands on. --Seejyb 22:18, 17 April 2006 (UTC)

I saw that and immediately thought that The Economist ripped off Douglas Adam's observation (paraphrasing from distant memory): Humans always thought themselves smarter than dolphins because humans had cities, computers, war, and all dolphins ever did was muck about in the water playing games all day. Conversely, dolphins thought themselves smarter for exactly the same reason. --Kainaw ^(talk) 01:14, 18 April 2006 (UTC)

That's a remarkably accurate quote. I doubt he's the only person who's thought along those lines, though. Regarding other "good indicator[s] of smartness," consider perhaps IQ of parents, IQ of siblings, IQ of children, IQ of friends, education level, SAT scores... Black Carrot 03:07, 21 April 2006 (UTC)

Platinum as a catalyst for Hydrogen Combustion

I am having trouble finding a source that verifies that platinum or palladium causes hydrogen to combust in air without a flame. Could someone point me in the right direction? --Joe 20:03, 17 April 2006 (UTC)

Perhaps you mean hydrogenation? Isopropyl 20:38, 17 April 2006 (UTC)

In the presence of oxygen, the platinum and palladium catalysts used for hydrogenation may "spark". If hydrogen is present too, it will combust. Hydrogen will normally burn with a flame that is not visible. Here's an example [4] (item 17 on list) of a warning of this danger, but you can probably find others on Google. --Ed (Edgar181) 21:36, 17 April 2006 (UTC)

You might wish to read the article on Döbereiner's lamp - a lighter built on that principle. Dr Zak 19:38, 19 April 2006 (UTC)

Basically, I am looking to coat a surface with Pt to heat it up when hydrogen comes in contact with it. Is this feasible and how would i calculate the heat flux based on the surface area of the Pt deposit? Thanks, --Joe 21:56, 17 April 2006 (UTC)

So what's it you are after? The idea is to measure hydrogen in a gas stream? At what concentration and temperature? What is the source of the gas? Dr Zak 19:38, 19 April 2006 (UTC)

I want to be able to calculate the heat created on the substrate if I have a given Pt surface area, H2 concentration of M and H2 pressure of P. The H2 is coming from a Tank and is at a steady state. --Joe 05:39, 20 April 2006 (UTC)

Fixing a broken monitor

I've managed to break my monitor - it now renders red to black, and green to yellow. After an investigation, I found the culprit: a severely bent pin in the plug (I knew using the hammer was a bad idea...), and after some more googling I've found that many other people have had similar problems, and I've also heard tell of replacing either the cable itself, or the broken plug, but no instructions on how to do either. The monitor is a Dell; an M991 according to the sticker on the back, and I can get my hands on a replacement cable/plug easily enough (ripping it out of another Dell monitor upstairs - and no, I want to continue using this one because it's bigger), but I don't know how to remove nor install either. Any relief from this blue/yellow world is appreciated, Sam Pointon United FC 20:30, 17 April 2006 (UTC).

The first thing I would try is bending the pin back to the proper position using needle nosed pliers. You will likely need to bend it past the correct position to account for spring back. The pin might break off, in which case you really will need to replace it, but it's still worth a try. StuRat 22:12, 17 April 2006 (UTC)

First, realize that messing around with crt monitors is potentially dangerous. Which plug are you talking about? Can you post some photos? For great justice. 22:20, 17 April 2006 (UTC)

Unfortunately, the pin is bent awkwardly (a double-bend, and right up against the side and bottom), so my efforts to reshape it have shown this avenue to be impractical if not impossible. --Sam Pointon United FC 22:22, 17 April 2006 (UTC)

I don't have a digital camera, so here is an approximation of the monitor's back in ASCII art:

      -----------------------
     /         (1)           \
    |      |-----------|     |
   /       |           |      \
   |       |  (2)      |      |
  /        -------------       \
 ###############################
 |             [o](4)           |
 |  <W>(3)                      |
 --------------------------------

Key: 1 = raised section.
     2 = label w/ model info, serial number, etc.
     3 = power cable
     4 = signal cable - the offender.

I think that the signal cable is removeable, because it is not actually fixed in, but rather is plugged into a slot (albeit one I don't know how to take it out from), and there's just enough leeway to move it slightly in said slot. --Sam Pointon United FC 22:33, 17 April 2006 (UTC)

Oh, also, to answer what you actually asked, the plug I was talking about was the one that goes into the graphics card. --Sam Pointon United FC 22:38, 17 April 2006 (UTC)

OK, so the easiest way to do this is going to be to get a replacement cable, and then cut them both in half, and join each wire in the cable to the corresponding one, so you end up with a new plug on the end of the old cable. For great justice. 22:40, 17 April 2006 (UTC)

... But don't fiddle with the cable where it enters the monitor casing. The Dell M911 cannot be unplugged on the monitor side. The wires are connected inside the monitor casing - no plug, and dangerous and difficult to connect. For me, fitting a new computer-side plug would be the reasonable DIY way to go, but splicing the cable may be technically easier. Good luck with your efforts. --Seejyb 22:55, 17 April 2006 (UTC)

I agree - you may be able to lop the plug off, and fit another one, but most of the modern ones are molded and not as friendly to DIYers as the old days, so I assumed cable splicing would be easier... For great justice. 00:04, 18 April 2006 (UTC)

The problem with cable splicing is that you'll probably be left in the dark about the pin assignments of the wires. So I'd really recommend splitting open the computer-end plug and replacing it that way, even though it'd probably require a bit of cutting and prying. --BluePlatypus 09:12, 18 April 2006 (UTC)

Seagull

What is teh exact species (just one? or more than one?) of "seagull" that is most commonly found in Toronto? What about New Brunswick?--Sonjaaa 21:09, 17 April 2006 (UTC)

Turns out this is a little more complicated than it first seems; apparently gulls are a wide variety of birds with subtle variations and overlapping ranges, and there's not even a firm conclusion on exactly how many gull species there are or where the lines are drawn. Some species also interbreed - believe it or not, we have an article (okay, stub) on the hybridisation in gulls. Looks like your best bets may be the Herring Gull, Great Black-backed Gull and/or the Ring-billed Gull. Looks like there's a gull out there for everyone. --ByeByeBaby 23:02, 17 April 2006 (UTC)

And if they're not happy, let them write a gull libel. --DLL 19:21, 18 April 2006 (UTC)

Which reminds me that "gullible" is the only common English word that's not in any dictionary. JackofOz 02:19, 19 April 2006 (UTC)

Psychotherapy and talk therapy

Are psychotherapy and talk therapy synonymous? I'm working on treatment of mental illness. --Neutrality^talk 21:44, 17 April 2006 (UTC)

I don't think they are quite the same. Most forms of psychotherapy are directed in some way, such as the classic "tell me about your relationship with your mother", while I think of talk therapy as undirected. That is, just talking about a problem, with no particular guidance, also helps people out, to some extent. Note that no specific training is needed for this method. StuRat 21:47, 17 April 2006 (UTC)

The Mayo Clinic seems to consider talk therapy to be another name for psychotherapy. See [5] --Seejyb 22:35, 17 April 2006 (UTC)

You can imagine the benefits of advertizing "talk therapy" over "psychotherapy".  freshgavinΓΛĿЌ  06:20, 18 April 2006 (UTC)

No. Psychotherapy can be any form of psychiatric therapy, (which may or may not actually be therapeutic). Some of it involves talking, some of it doesn't. Cognitive therapy for treating phobias can be quite hands-on. (actually confronting whatever you're afraid of) Note that "psychotherapy" and "psychotherapist" are quite loose terms, and you often don't need any formal qualifications to call yourself a psychotherapist. Which basically means there's a lot of nutty ideas out there in this field. (So that article is wrong- methods described as psychotherapy may not be based on any credible psychological theory) Contrast this to a psychiatrist who is usually a medical doctor trained in the mental health field. --BluePlatypus 18:12, 19 April 2006 (UTC)

pushing on your eye

What is the name of the "kaleidoscope" effect you see when you push gently on your eye for several seconds?

-Froth 21:43, 17 April 2006 (UTC)

Phosphene. Melchoir 21:51, 17 April 2006 (UTC)

April 18

Do blind people dream?

I've had a look at the Dream article but can't seem to find any information: Some friends and myself were having an interesting conversation of what people who are blinds - of which have no knowledge of any kind of visual anything, e.g blind since they were born - dreams are like, if these happen at all. I understand dreams tend to show previous actions or feelings, and i see the main way of showing this is via sight, so what would a person who has no visual perception of shapes, colours etc dream like. Would/Do they involve colours, emotions, tastes, smells, etc to a greater extent to that of a non-blind person? I really would like to hear peoples feelings on this. And I am gravely sorry if my question has gone to offend anyone. -Benbread 00:04, 18 April 2006 (UTC)

Blind people, from my experience have particularly heightened hearing senses. They may dream purely in sounds. I doubt that your query will offend people. It seems very genuine to me. Ansell 01:26, 18 April 2006 (UTC)

Although they might get offended at being called blinds!  freshgavinΓΛĿЌ  06:17, 18 April 2006 (UTC)

If you google "blind dreaming" you'll find there is a lot of research on this, i.e. [6][7] [8]. Seems like a hot question in cog sci research. --Fastfission 02:43, 18 April 2006 (UTC)

Gravely sorry! Are you saying you are sorry enough to kill yourself?? -- Mac Davis] ⌇☢ ญƛ. 05:16, 18 April 2006 (UTC)

Fascinating question. Thanks. Being blind means having a limited or non-existent capacity to use one's eyes. Dreaming has nothing to do with the eyes, because it has nothing to do with seeing external objects. If a blind person can imagine anything at all - and of course they can - they imagine it in symbols as everyone else does. They may not have the rich array of images that a sighted person has, and the images they do have may not accurately represent physical objects, but they can still feel the shape of objects and have a sense of what they look like. Those "feeling images" would constitute their core stock of images that come to them in dreams. And as most sighted people know, dreams can often produce images of things one has never seen in real life, so why shouldn't this happen to blind people as well? JackofOz 09:02, 18 April 2006 (UTC)

Thanks for the help everyone - Sorry about the use of "blinds", that was likely a typo on my part, I wrote that question rather late at night last night feeling rather tired - See why I needed the comment on trying not to offend anyone? ;) In regards to your comment, JackofOz, I get the feeling that if a blind person cannot comprehend what a colour is (not that colours are anything but our interpretation of light radiating at different wavelengths, and theres plenty of information on some people who are blind are able to see colours), would these dreams have no visual element to them at all, or would it be a simulation of what someone would see, but without colours, or would it just involve other senses? As i cannot imagine someone who has never used their eyes before would know what this feeling would be like, just as people cannot understand what a bat or dophins "sonar" senses are like, except by watching simulated images. Again, thanks a lot, and i'll take a look at those links :) It'd be nice to see the Dreaming article have some information on this, assuming that i haven't missed its appearance since i last fully read that article. -Benbread 10:21, 18 April 2006 (UTC)

Well, the world had no trouble accepting monochrome TV, so the absence of colour per se does not seem to be a big problem in visualising images. How about this for a counter-question: Do babies in utero dream? And if so, what would they dream about? They've never used their eyes either. JackofOz 02:17, 19 April 2006 (UTC)

music software and poison question

Is there software (relatively cheap) where you can cut and paste parts of a music track? Say like you only want 3 min. of a 35 min. song. Where can I get more information on this product? Also, a totally unrelated question: is there in existence a potion or chemical or whatever like that used by Juliet in Romeo and Juliet? Thanks. schyler 03:02, 18 April 2006 (UTC)

To answer your first question, audacity is your friend. Raul654 04:17, 18 April 2006 (UTC)

You mean like Audacity? Actually I just use SoX but it only has a command-line interface and might be hard to install on your platform (which you forgot to mention). —Keenan Pepper 04:19, 18 April 2006 (UTC)

And yes, sure, there are chemicals in existence which can knock people out like it did to Juliet. I can't think of any specific names at the moment, though. -- Daverocks (talk) 09:47, 19 April 2006 (UTC)

If the Speed is C.

If the Velocity of an Object is equal or greater than the Velocity of Light. The Mass is infinitve as per the equation m = Mass at Rest / (1 -( ʃV*V / C*C)). Does infinitive here it keeps on changing ? Please explain and sorry for my BAD Formulae Qutoing I am new to Wiki.

I think you mean this formula, similar to those at Relativistic mass:

$M=\gamma m={{m} \over {\sqrt {1-{{v^{2}} \over {c^{2}}}}}}$

As v approaches c from below, the relativistic mass increases without bound, assuming that m isn't zero. To accelerate a massive object to the speed of light, then, requires an infinite amount of energy. There's no meaning to going beyond c. Melchoir 04:22, 18 April 2006 (UTC)

Have you read Introduction to special relativity? —Keenan Pepper04:26, 18 April 2006 (UTC)

Thanks For That. Yes I meant that formulae itself. Till now Science havent managed to defeat the velocity of Light. But I hope there will be a time for that. So if the speed is C. no need to exceed it. Then $V^{2}-C^{2}$ would give 1 and then 1 - 1 would give 0. Then No amount of Mass at rest would give Infinite. But Every Object Occupies space and has Mass. THen What will be the Mass. One more question why does the Mass change when Velocity changes. Even though it notably changes for 3 X 10^6 m/sec^2 there is always a small change. Plz explicate very easily and understandingly for the age of 15. Thanks in advance.

Every particle that can be observed at rest has a rest mass, which is a constant property. If you want to think about what the relativistic mass - the one which increases with velocity - means, then think of it in Newtonian terms: mass is an object's resistance to acceleration. So the faster an object goes, the more energy you need to make it go even faster, which (appears as though/means that) its mass is increasing. Yes, if you could accelerate something from rest to c, then it would have an infinite mass, but it would require an infinite amount of energy to do so. The only objects to travel at the speed of light - photons, etc. - cannot be brought to travel at any other speed, because they have effectively zero rest mass. Confusing Manifestation 09:02, 19 April 2006 (UTC)

Thanks for Everything. One More Doubt you said " but it would require an infinite amount of energy to do so" So are you truing to say that that is not possible.--Oasa 10:34, 20 April 2006 (UTC)

(No heading)

Sir, i want to know details about GIS and also wnat to know there is any job vaccancy is there.

Please send me complete details

Thanking You,

My e-mail id is (email removed to protect you from spam)

Depends on what you mean by GIS. We have articles about Gruppo di Intervento Speciale, an Italian special operations unit, and Groupe d'Intervention Spécial, an Algerian one. –Mysid 11:26, 18 April 2006 (UTC)

And if you want a job then email Jimbo.

And if you want people to take you seriously, use a spell checker when you apply for jobs. Phileas 02:32, 19 April 2006 (UTC)

(IATA: GIS) is clearly Gisborne Airport. For details, you could check a Geographic Information System here, or even do a Google Image Search here. The airport is operated by the Gisborne Regional Council, but sadly they currently have no job vacancies. But why are you asking, anyways? If you have a Guaranteed Income Supplement, as you seem to be claiming, it seems to me that you hardly need a job. --ByeByeBaby 06:09, 20 April 2006 (UTC)

Dieting, metabolism and "starvation mode".

I've heard lots of people saying that if you skip meals or stop eating as a way of losing weight, it doesn't work. The reason they give for this is that your body goes into "starvation mode" and your metabolism slows down, meaning that your body works more efficiently and you don't use up as many calories. To clarify - say you burn 300 calories from an hour of exercise normally, (according to their reasoning) you would burn fewer calories than this if you hadn't eaten for 24 hours beforehand. I'm slightly sceptical as no one seems to be able to give me a reason for why your body does this. So - is this "starvation mode" a scientific fact, or is it something they tell teenage girls in the hope it will prevent eating disorders? How much difference does this "starvation mode" make? And, if it's more efficient, why doesn't your body run on "starvation mode" all the time? Not trying to diet myself, I was just wondering. Thanks in advance. Bodil 08:44, 18 April 2006 (UTC)

You're absolutely right, if someone continues to miss meals and starve themselves, their rate of motabolism will go down, and they will use less energy. This is most evident in the amount of energy you're using "ticking over", for example when sleeping, just staying alive. So, by effectively starving yourself you're still losing a lot of weight because you're simply not inputting any calories into your body, but still using less calories overall - Still if your eating less calories than you're using, regardless of how slowed your metabolism is, you'll still lose weight, but it's far from ideal, or safe.

In regards to healthy dieting, the reason people are overweight is because they're eating too many calories and not using them up enough by not exercising (or by exercising a lot, but eating an incorrect diet), and thus these excess calories are stored as fats. Thus by eating only the calories you require and then exercising to burn calories and increase your metabolic rate your body wont go into starvation mode, but you've got to be eating regular meals, eating small regular meals is a great way to not feel "starving" while still eating less. I'm no dietition, but I hope i have helped you. -Benbread 10:11, 18 April 2006 (UTC)

Thanks, Benbread - that helped clarify things :-). Bodil 11:18, 18 April 2006 (UTC)

Also note that when you do go into "stavation mode" you're likely to put fat back on when you do eating regularly again as the body tries to replenish it's reserves. The best formula for dieting is calories burned > calories gained = weight loss. Thats overly simplistic but true. Better than cutting out meals it's best to eat less. Stop eating when you're about 80% full it takes a while for your brain to catch up to your stomach. The best way to lose weight is to consult your Doctor or a nutritionist.--Tollwutig 13:56, 18 April 2006 (UTC)

Thank you for your answer Tollwutig, I appreciate it :). Bodil 21:19, 19 April 2006 (UTC)

Regarding your question about why people don't just operate in starvation mode all the time for max efficiency, the reason is there is a substantial cost, your body shuts down or reduces all nonessential functions to survive the period of starvation. Your body produces less heat, so you will need to wear more clothes or turn the heat up, it's harder to concentrate, so you won't do as well at complex mental tasks, growth may stop altogether in children, sleep duration will increase, and menstruation will stop in women and sperm production in men. StuRat 01:40, 19 April 2006 (UTC)

Thanks, StuRat - a great, clear answer with interesting points. This reference desk thing is brilliant, I feel a lot more informed now! Bodil 21:19, 19 April 2006 (UTC)

You're quite welcome. :-) StuRat 09:31, 20 April 2006 (UTC)

Electrical Engineering

In a potential or current transformer,is the induced current/potential out of phase or in phase? Because i have come across two books conveying different meaning....

It depends on which way it's connected. - 128.32.48.131 00:49, 19 April 2006 (UTC)

As said above it all depends on how you label your diagram of the transformer core. Plugwash 22:07, 22 April 2006 (UTC)

Ballistics

Does the effect of ballistics apply only due to air resistance present on earth and absent in space?is it because of the fact that a projectile would be able to pierce the air better if rotating than if not rotating about its axis parallel to direction of motion...

Once again, please remember that this place is an encyclopedia (really, really!). I just checked out the entry on ballistics, perhaps you will be much happier doing it yourself? --Zeizmic 12:09, 18 April 2006 (UTC)

Take your coat off or you won't feel the benefit

This is something people often say to me if I keep my coat on when I sit down in a coldish bar or cafe, presumably meaning that I should save my coat for when it's really needed, ie when I go outside again. Personally, I can't see the logic in it, but when I question its wisdom people look at me like I must be crazy. Could someone spell out the logic/science please, so that I can refute the myth (if indeed it is a myth) next time it happens? Thanks, John Walker

There's a little thing in here about the myth. [9] I'm a skinny guy who gets cold a lot, so I know it is important to maintain your core temperature, and build up a heat reserve. --Zeizmic 12:05, 18 April 2006 (UTC)

I agree that the idea of taking your coat off to feel warmer seems sort of silly, but what I'd like to know is where you find coldish bars or cafes in wintertime. In my experience, in places with cold winters, they tend to keep it far too hot inside when it's cold outside. The reverse phenomenon can be noted in the summer. It irritates me because I have to keep stripping and re-bundling. --Trovatore 17:24, 18 April 2006 (UTC)

The only way I can see that they would be correct is if you overheat with your coat on, then sweat, then go outside soaked with sweat, which would make you colder. So, put your coat on when you are cold, and take it off when you get hot, and you should be fine. StuRat 01:29, 19 April 2006 (UTC)

You could tell them to mind their own business. Seriously, why would anyone even say that to you? Black Carrot 15:51, 19 April 2006 (UTC)

When I visit the house of somebody who keeps it cold inside, I am reluctant to wear my coat, as that seems to be a criticism of them keeping their house so cold. However, if it's really cold, I don't care if I insult them. StuRat 20:37, 19 April 2006 (UTC)

"I must be coming down with something; I'm feeling cold all the time. Think I'll keep my coat on." - Couldn't care less if they feel insulted by that - it's my health. Gardar Rurak 06:20, 22 April 2006 (UTC)

The World

How many people are in the world as of 2006?

The US Census Bureau has webpage estimating US and world populations. [10] --Ed (Edgar181) 12:10, 18 April 2006 (UTC)

List_of_countries_by_population also tells you - Notice the search bar on the left. -Benbread 12:16, 18 April 2006 (UTC)

6,506,930,627 WAS 4.250 18:20, 18 April 2006 (UTC)

No, sorry, it's 6,506,930,644 now. User:Zoe|^(talk) 02:17, 19 April 2006 (UTC)

Necessary truths

Most scientists (I think) would agree that there are certain necessary truths. For instance, the Pythagorean theorem seems axiomatic: we couldn't imagine a universe (I assume) where it wouldn't be true. Are the more complex physical laws necessary truths? For instance, a body's kinetic energy increases with the square of the body's velocity: is that a necessary truth, or could the universe have been constructed so that it weren't true? — Asbestos | Talk (RFC) 14:07, 18 April 2006 (UTC)

Well, the pythagorean theorem is derived from axioms. The axioms have to be taken for granted, but the derivation does not. There are no axioms in the physical science, but useful things can be done, predicted, and made using the theories we have. Indeed, the "truth" you cite demonstrates that useful things can be done with inaccurate theories: the kinetic energy formula is surely pre-relativity? Notinasnaid 14:29, 18 April 2006 (UTC)

One can imagine a universe existing with any number of different values/properties/laws/etc. The question is whether or not it would develop into what we would consider a universe or not. Two articles which might be of interest in these regards are anthropic principle ("If the properties of the universe were different, would we be here to contemplate it?") and Gödel's incompleteness theorems ("Can an all-encompassing axiomatic system be constructed which can prove all mathematical truths?"). --Fastfission 15:09, 18 April 2006 (UTC)

Start here: Philosophical skepticism WAS 4.250 18:16, 18 April 2006 (UTC)

I should point out that the Pythagorean theorem does not hold for non-Euclidean geometry and so almost certainly is not strictly "true" in our universe; but on small scales and away from strong gravitational fields, space is nearly flat and so it almost completel accurate. — Knowledge Seeker দ 01:39, 19 April 2006 (UTC)

how can someone kill themselves in...

Ok if i was in a padded room, naked, fed and watered, (can't drown myself or resist to eat) and temperature is room temperature how could one kill themselves? I can't hold my breath because i would simply be unconcious and start to breath.86.129.71.11 15:35, 18 April 2006 (UTC)

• Old age. Seriously, self-inflicted neck injury or slashing wrists with fingernails, but I don't think there is a method that is reliable. But if you're suicidal, that might explain the padded room in the first place. Peter Grey 16:05, 18 April 2006 (UTC)
  • Regarding the wrists, it might be easier to use your teeth. Fredrik Johansson 16:55, 18 April 2006 (UTC)
    • Usually you do this in a bath : gore might fill in the wounds, so remember to gnaw more before fainting. --DLL 17:19, 18 April 2006 (UTC)

Bite your tongue and swallow the blood and keep the wound open and flowing with your teeth. Nobody will see you are injured until you've bled enough that there is little likelyhood that they can help. --Kainaw ^(talk) 18:24, 18 April 2006 (UTC)

Eat your own head. A Clown in the Dark 21:53, 18 April 2006 (UTC)

how bout, death by peanutbutter, what? no article? (;205.188.116.74 23:43, 18 April 2006 (UTC)

Oh, come on guys, you can do better than that! Jesus tap-dancing Christ! Tearing at your wrists, indeed! Why not just tear your own throat out? It's a hell of a lot more delicate, and nearly impossible to fix. Of course, to do it properly would require a bit more hand strength than you probably have, but it's not like there's any shortage of excercise time in a padded room. I would suggest tearing off something even more delicate, but it'd be a lot more painful. I like the 'biting the tongue' idea too. If you'd like something more challenging, you could also tear open some of the pads, tie the cloth into a rope, and strangle yourself. Or, for an even bigger challenge, you could try drowning yourself. If you can master your coughing reflex, you could inhale all your water instead of drinking it, which should quickly fill your lungs. Even once you passed out, you would still be getting inadequate oxygen, and should slowly asphyxiate. BTW, you never mentioned them removing your waste, and death by disease is a time-honored tradition among prisoners. Black Carrot 01:53, 19 April 2006 (UTC)

I'm not sure if it'd be possible in the situation you've given, but another approach is to try and break whatever light source they give you and use the glass as a razor. --Fastfission 01:58, 19 April 2006 (UTC)

If you lean yourself up against the wall in such a way that your head is bent forward with your chin into your chest, I'd say it would be pretty easy to damage your spine by letting your body drop down off the wall, thus putting a lot of strain on the back of your neck.
I'm not sure if this is possible but I've always wondered; if you sit kneeling on your heels for long enough, you lose circulation. If you maintain the position for long enough, couldn't you get gangrene or something?  freshgavinΓΛĿЌ  05:22, 19 April 2006 (UTC)

If you think of the situation the world is in long enough you'll die of a broken heart.

In response to the tounge biting/blood response, Japanese ninjas, secret agents, and other assorted spies have been instructed to bite off their own tounges. They would use the severed tounge to choke themselves, should they ever encounter such a situation. This has been proven to be pretty darned effective; seeing that it's hard to prevent against and fairly easy to execute when you've been told how to do it. 68.52.56.111 03:23, 20 April 2006 (UTC)

How about intentionally choking on your food? Just toss in a chicken wing while taking a deep breath.  freshgavinΓΛĿЌ  03:36, 20 April 2006 (UTC)

Pretty possible to do, if you had something big enough (i.e. a chicken wing). Seeing as how I have a varying degree of knowledge on the subject, it's time to end this question once and for all:

1. If you are in a psychiatric ward with padded walls, naked, fed, and watered, it isn't uncommon for them to force-feed you liquid based food, sometimes even introveinously if you are a really obnoxiously suicidal patient. So, you can't choke yourself with your own food, nor can you drown yourself with water, as they will NOT allow you to eat/drink your own sustinance.

2. The light-breaking method is impossible, as the light fixtures (that is, if you HAVE one) are made of polycarbinate glass that WILL not shatter. So, you can't cut youself.

3. Also, please note that many times if you are in what the docs call the 'unreactive' section of a psyche ward, you are in a straightjacket 24 hours a day, 7 days a week. This elimates the ability to slash your own wrists, pull out your neck, or gore/self-mutilate yourself to death in any way. Even the idea of damaging your spine as mentioned above is practically impossible in a straight jacket, as is the idea of losing circulation, or consuming your own feces. It is possible to escape from a straightjacket by A) dislocating your shoulder [easiest overall], B) Using cutting tools , or C) wearing the fabric down [this takes the longest]. However, I don't think the average person would be able to get out of one. If you did happen to get out of the straightjacket, you could practically beat yourself to death if you wanted to, among other things. The choices of death are pretty much endless once your get access to your limbs.

4. The only real choice you have left is what has already been mentioned: bite your own toungue, casuing you to choke on your own blood, or to bite your tounge off completely and use it to choke yourself. Even this has been contemplated for in some cases, when a white plastic attatchment is put on the tounge in some psyhe offices, which prevents you from biting your own tounge. But, that is pretty rare.

5. Please also keep in mind that most of the time when you are in a psyhe ward you are heavily sedateded and heavily medicated with drugs that will affect your mental state towards thoughts of not killing youself. It'll be pretty hard to kill yourself (or even THINK, really) when you are full of what is comically close to horse tranqilizers and 100x doses of prozac/zoloft.

So, in the end, it's quite possible, but pretty damned hard to kill yourself in a situation like that. It would probably be easier to escape from a psyche ward than it would to kill yourself in one. If there are any other questions on anything related escapeology, feel free to bounce questions off of me anytime. The Linguist 04:33, 20 April 2006 (UTC)

How do you bury yourself in a chained and locked coffin under cement and dirt for four days and come out alive?  freshgavinΓΛĿЌ  06:18, 20 April 2006 (UTC)

That one is actually simpler than you might think. There are two parts to any good con: deception and stealth.

1. Was the coffin inspected (I mean THROUGHLY inspected) before the guy got into it? There could be tools inside of it like a pick, flashlight, trowel, lock-picking tools, oxygen tanks, a knife, or etc. Many times they hide these under the frilly/padded sections on the bottom of the coffin. They just tug on the pads really hard to expose hidden compartments underneath.

2. Was the magician inspected? The most common place for them to hide tools is in their shoes (boots), although in the underarm and the hair is fairly common as well. Sometimes even the mouth is used.

3. The guy really isn't IN the coffin for four days. Many times, the spot where the trick is going to be preformed has been picked weeks in advance (despite what you may have been led to believe). The common way to do it is just dig a tunnel underground below where the coffin will be buried, then when the guy is buried he digs DOWN instead of up (before the cement can really harden) to get to the secret chamber below. I remember that one guy who did it (it might have been Chris Angel) even had a television down there for him (and the two guys helping him) to watch while they were waiting.

4. So, the guy basicly stays in the coffin for 2-3 hours MAX while digging himself out, then sits around for 3 and 3/4 days underneath the ground.

There might be more complicated ways to do it, but that is the most expedient way to get it done. 68.52.56.111 17:50, 20 April 2006 (UTC)

Animal Dream

Do animals dream ?

How could we possibly know if they did? Rapid eye movement occurs in all mammals and birds, but that doesn't mean much. —Keenan Pepper 17:13, 18 April 2006 (UTC)

Why would that not mean much? It occurs in all mammals and birds, but isn't known to occur in any other animals. That does mean something: Given that we (mammals) all act the same (eye movements, twiches, EEG patterns of brain and muscle activity, irregular heartbeat, etc) during what we call REM sleep, given that we know humans dream during REM sleep and given that we know REM sleep is more similar to the awake state than NREM sleep, it seems more reasonable to assume that all REM-sleeping animals dream than the opposite. There's also the nature of the motor activity, we know humans move in their dreams (although normally with restricted motor control). Anyone who's seen their sleeping cat paw at thin air instinctively draws the conclusion they're dreaming. Baby platypuses tend to make swimming motions with their forepaws while sleeping. The platypus is also the animal that has the most REM sleep. :) ("Monotremes and the evolution of REM sleep", Siegel et al, Phil. Trans. R. Soc. Lond. B, 353, 1147-1157) --BluePlatypus 18:23, 18 April 2006 (UTC)

Yes, animals dream. WAS 4.250 18:08, 18 April 2006 (UTC)

Yes, they do dream according to this and this... Jayant,17 Years, India • contribs 18:13, 18 April 2006 (UTC)

Yes. Indeed, research with mice show that the same signals are sent out by the motor cortex while the mouse is sleeping as when the mouse is awake, except that this isn't transformeded into movement due to sleep paralysis (or the mousey equivalent). If you're training a mouse to go through a maze, you can not only tell that he is dreaming about walking through the maze, but even where in the maze the mouse is in his dreams! If you need a citation for the paper I may be able to find it, but it's been a while. [Edit: I guess a similar study is referenced in Jayant's second link]

That said, we don't know anything about the mouse's experience of dreaming. We don't know if the mouse is "seeing" himself go through the maze, or if the brain is just rehearsing the steps it needs to go through the maze, without any attached conscious experience. This distinction is currently outside the realm of modern science to evaluate. — Asbestos | Talk (RFC) 20:00, 18 April 2006 (UTC)

Yes, animals dream, though their dream sleep seems to be different to human dream sleep and more attuned to rehearsing survival skills, IIRC. Anyone with a cat will know that they dream - occasionally you can see them mimicking their awake movements while sleeping (I've even seen one bat an invisible mouse backwards and forwards before "dream chewing"!) Grutness...wha? 06:24, 19 April 2006 (UTC)

Who builds the best cars?

Can someone tell me which car company builds the best cars in terms of build quality and reliability? I am guessing it is the Toyota/Lexus brand but I am not sure.

It depends on what you mean by the best in quality...its a personal choice... and from the cars i have seen or handled (which is not many, considering that i am not allowed to drive yet) i've found the Toyota and the Nissan brands to be quite suiting to my taste..Jayant,17 Years, India • contribs 17:28, 18 April 2006 (UTC)

Consumer Reports does a number of surveys on things like automobile quality. You could check the latest Buyers' Guide or the most recent car buyers' issue of the magazine, and see which brands and specific models have the lowest rate of reported problems. --Serie 21:17, 18 April 2006 (UTC)

It varies greatly in time and by model. Short answer: there is no good way to tell, every brand / company has its strengths and weaknesses. Find the car you like, with the features you want, at a price you're willing to pay. — QuantumEleven | (talk) 11:32, 20 April 2006 (UTC)

Well, it usually goes something like this.

Foreign Car = takes way longer to break down (esp. asian-made) = charge you out the ass for replacement parts American car = breaks down way sooner = replacement parts are cheap

So, the question is, do you want to pay incrementally over time (american made cars) or just a large sum whenever something goes wrong (foreign)? 68.52.56.111 18:06, 20 April 2006 (UTC)

(Limiting the scope of the question to rugged terrain) A series of field tests performed by the Canadian Forces equipment testing facilities (somewhere around Ottawa, Ontario) in the mid-'90s came up with an interesting findings: The two toughest commercial cars (SUV type) were the Range Roover and the Hummer. What was surprising is that even though these two cars have dramatically different design (the Roover is a mobile living room while the HUMVEE is a nut-cracker), they perform equally in all tests (60-degree slope braking, 45-degree sideway inclines, 3-foot mud pits etc.) only but for one test. The Roover failed the "deep-V" gutter test, because the front bumper prevented the front wheel to make contact with the wall on the other side of the V-shape gutter. (The HUMVEE, given that its front wheels are far forward could gain traction on the other side of the gutter and climb back out.) Therefore, if you expect to navigate through a lot of deep-V gutters, the Hummer is your best car. If you prefer utter comfort, go for the Roover.--JLdesAlpins 18:08, 21 April 2006 (UTC)

current affect of technology

Use of technology has resulted in abuse in nature and man himself: if yes then how; if no then how?

Hello! Glad to help. See Prometheus first. Goodbye and thank you for your question. --DLL 17:06, 18 April 2006 (UTC)

The question presupposes that man is unnatural or somehow outside of nature; that technology is unnatural or somehow outside of nature. Realizing that man and technology are as natural as beavers building damns and birds building nests and ants farming aphids results in the understanding that "abuse of nature" is merely a trickery with words designed to support a position not supported by the facts. Then again, the facts do support the idea that man is altering both himself and the world around him in unprecedented ways achieving effects both wonderful and frightening. WAS 4.250 21:11, 19 April 2006 (UTC)

I don't know if you're talking about facts or words. Yes, beavers use technology. This is not what people mean though when they speak of the ails of technology, by which they usually mean human-made-technology post-industrial revolution, which I think we can all agree on as being in many respects quite different than beaver dams. I think the man/nature divide in this sense is not meant to be a statement about whether or not man is a part of nature, but to differentiate for the purposes of accountability/responsibility. In any case... Heidegger's The Question Concerning Technology would make for the most interesting answer to this assignment. It's not the easiest read for someone not used to Heidegger though, but there's a pretty nifty guide available on the web which goes through the argument step by step... --Fastfission 01:54, 20 April 2006 (UTC)

brain cramp

If muscle cells are required to function anaerobically, they will convert pyruvate to lactic acid to regenerate the NAD+ needed to continue glycolysis. This build up of lactic acid can cause muscles to “burn” or even cramps to develop. If you think really hard, harder than you have ever thought before and don’t breathe, can you get a “brain cramp”?

The brain doesn't really work like a muscle, so no. A Clown in the Dark 21:50, 18 April 2006 (UTC)

Brain cells can't function by anaerobic metabolism. If you think hard and don't breathe, you get what people refer to as "brain dead". --Serie 21:51, 18 April 2006 (UTC)

I have experienced something like this, but it's more of a dull ache than a sharp muscle pain. I attribute it to having used up the available glucose in a portion of the brain. StuRat 01:17, 19 April 2006 (UTC)

Human Cloning.

Hi there, I wonder if anyone would be kind enough to answer my question, which is:

Let us assume that human cloning is now possible. Let us assume that a human has been made infertile (unable to reproduce) due to being irradiated by, lets say, a massive amount of gamma rays. Would the clone of that human being be fertile or infertile?

Thank you, Norman Crompton. Lancashire, England.

Fertile. Infertility by mechanical damage (castration, gamma radiation, or any other means) isn't inheritable. --Serie 21:54, 18 April 2006 (UTC)

Infertility isn't really inheritable, if you think about it. Just because a person is infertile does not necessarily mean that every cell is infertile. If the gamma rays that the person was exposed to damaged the particular cell that was used to harvest the cloned DNA, and if the genetic damage was sufficient to affect the reproductive capabilities of the person, it is conceivable that the clone could also be infertile. Isopropyl 23:53, 18 April 2006 (UTC)

There are types of infertility that are medically correctable, so in that case the infertility could still be inheritable.

the clone could also be infertile -- true, but in this case the infertility would be entirely unrelated, unless the cell used for the cloning was also responsible for gamete production in the original person. The damage done to each cell is different, so the gamete cells could, say, be unable to produce energy, but some other cell might have become triploid or so. Then the clone might be all triploid and infertile for that unrelated reason. Of course, this means that irradiating part of a person, then cloning them from the damaged tissue could create the opposite condition: an infertile clone of a still-fertile person, even if the clone was made from reproductive tissue. Damage from the irradiation could cause the cell to no longer code for a fertile human without preventing it from being fertile where it was. --Tardis 21:23, 19 April 2006 (UTC)

Note, however, that if the individual was exposed to a level of radiation sufficient to cause sterility it would likely also cause genetic damage. Thus, any clone would be more likely to have mutations. Not the ability to see through walls, as in a sci-fi story, but perhaps an increased risk of cancer might be observed. StuRat 01:11, 19 April 2006 (UTC)

stove hood electric motors

I have bought a stove hood from Germany but I live in Canada. I have ran the proper 240 V cable and 15 A breakers, but the fan runs on 50 Hz compared to 60 Hz in Canada. Can the fan operate properly with no ill effect to either the motor or the electronic side of it? Thank you in advance. Nanika

The 20% faster AC frequency will only drive the fan a little faster in practice. It probably is a DC fan with a rectifier because you don't want to use an AC motor in a variable load situation anyway. Just run it for five minutes, then turn it off and feel it. As long as it's not too hot to touch, you should be fine. --James S. 00:51, 19 April 2006 (UTC)

Either that or its a universal motor. Indeed i strongly suspect that it is. In any case the advice above is sound, run it for a bit and if nothing gets worryingly hot it should be fine. Plugwash 22:15, 22 April 2006 (UTC)

Air embolism?

Hello! I am concerned with one thing that hapened to me when I was doing one endovenous injection , I injected 2ml of air in the blood circulatory sistem of a pacient. It was error, because someone who prepared the seryng didn't purged the extensor device.

It could make any damages? How long it take the damages to ocour? How much air in the blood can provoque an emboli by gas?

I contacted the paciente 5 days latter and he was working and fine, should I concerned more with this incident?

Thank you.

Air embolism says: Small amounts of air often get into the blood circulation accidentally during surgery and other medical procedures, but an air embolism which shows symptoms is relatively rare.... Air can be injected directly into the veins either accidentally or as a deliberate act. Examples include misuse of a syringe, and industrial injury resulting from use of compressed air. However, usually this will neither suddenly stop the heart nor cause instant death, unlike in fiction stories where this is used as a method of murder.... Symptoms of an air embolism depend on where the bubbles lodge. They range from skin rashes, joint pain, visual disturbances, balance disturbances, breathing difficulties, extreme fatigue/lack of strength, numbness, paralysis, unconsciousness and death. If the embolism occurs in the coronary arteries of the heart, a heart attack will occur. If it lodges in the lungs, a pulmonary embolism will occur, resulting in shortness of breath and chest pain.

This source says: Frequency of clinically recognized VAE (venous air embolism) following CV (central venous) cannulation is less than 2%.

So, it seems you're probably fine, especially if the patient has none of the symptoms. --James S. 00:09, 19 April 2006 (UTC)

April 19

Potato diet

Is it possible to live on a diet of just potatoes and water? What would the potential adverse effects of such a diet be?

Thankyou

Death probablly though that would likely take a while. Off the top of my head you'd end up with at least scurvy and lack of Essential amino acids to deal with. Almost certainly other issues too. Plugwash

Apparently there is vitiman C in there though it may be lost depending on how the potatos are stored and treated. but in the long term living on any one food is likely to leave you difficiant in something. Plugwash 00:46, 19 April 2006 (UTC)

You might not get scurvy but you would get beriberi, kwashiorkor, osteomalacia, pellagra and most of the other maladies in Category:Malnutrition. —Keenan Pepper 02:41, 19 April 2006 (UTC)

Taking just one of these: beriberi seems to be caused by a thiamine deficiency, but is most common in those that subsist on rice. Indeed, potato suggests there is thiamine in potatoes: 0.11 mg per 100g. This is around 10% of the RDA, so 1 kg of potatoes would ward off beriberi. Of course, that amount of green potato could kill you. Notinasnaid 08:45, 19 April 2006 (UTC)

Not to mention you'd be sick of eating potatoes.  freshgavinΓΛĿЌ  05:10, 19 April 2006 (UTC)

Let's not forget that such a High starch diet would quickly steer the individual towards lots of fat build up. Which leads to it's own set of problems. Obese but mal-nurished.--Tollwutig 15:39, 19 April 2006 (UTC)

I don't agree on the obesity part. The Irish poor existed almost exclusively on potatoes for quite some time with very little obesity incidence. StuRat 20:32, 19 April 2006 (UTC)

What nutritional disorders were common among the Irish? —Keenan Pepper 21:39, 19 April 2006 (UTC)

If what is written across the 'pedia is to be trusted, there must have been little adverse effects to the Irish potato centered diet in the 17-1800s. Seems that there wasn't much of a problem (relatively speaking) until they started running out of potatoes.  freshgavinΓΛĿЌ  06:13, 20 April 2006 (UTC)

I suspect that, even if the Irish diet was 90% potatoes, the remaining 10% (beer ?), must have been enough to prevent nutritional disorders. Although this diet probably did have long term consequences, contributing to the rather low life expectancy at Ireland at the time. StuRat 00:45, 22 April 2006 (UTC)

Not if the potato and water are pure. But dirty water , dirty and maggoty potatos, yes. (Same with pure white bread vs. bread made from vermin infested grain. Prisoners really could live on bread and water when the bread was not pure.) WAS 4.250 21:22, 19 April 2006 (UTC)

Good point. Maggots especially are full of valuable protein. —Keenan Pepper 21:39, 19 April 2006 (UTC)

I'm anosmic and as such I can tell you fairly accurately what happens when you don't vary your food intake. With my 'handicap' food is a nuisance rather than a pleasure so I have more or less done this although never with potatoes - too much of a hassle. My worst experience was spaghetti and nothing else over the course of 4-5 months. The high amount of starch is comparable although potatoes also contain various minerals and vitamins which might prolong the effects.

1. First you loose muscle mass, most of it over the first 3 months at an impressive rate - you don't gain weight (fat) unless you're eating a lot of it. I only ate once a day so it wasn’t an issue for me although it may be if you eat 4-5 times daily.
2. Then your immune system gradually deteriorates - you will become sick much more easily. I had a cold almost constantly for the last month and I think wounds and bruises took much, much longer to heal although that may just be paranoia.
3. Fatigue and laziness ensues after 2-3 months and increases steadily - you sleep more, can focus for shorter periods of time and start having headaches when you concentrate. You reach a point where reading a book becomes difficult because you can't remember what happened ½ paragraph up. And no, I'm not a bad reader... I read a fair bit at a civilized rate.
4. Then you reach the point where if you get up quickly you will feel dizzy and woozy; your vision “blackens” and you loose balance and coherence. First only for a few seconds but later it will increase to as much as a few minutes. You learn to not hurry…
5. Then you start to pass out whenever anything more demanding than processing spaghetti occurs to your body – i.e.. drink a beer, smoke a cigarette. It’s not a gradual thing either – maybe you light up a cigarette one day – and it’s like switching off a machine. Bang, you’re out.
6. You wake up in the hospital after you passed out at the bus stop.
7. You expand your food budget.

That’s pretty much it. I’m sure you can prolong any of these effects by eating vitamin pills, supplementing with small amounts of meat or just eating a fruit once in a while – but I’d advice you to eat varied – there’s probably a ton of side effects which isn’t immediately obvious or may only become harmful after longer periods of time. There's a reason why some people live til they are 60 and others till they are 110 - and genes aren't all of it. Regards, Gardar Rurak 03:38, 22 April 2006 (UTC)

Embryo in an Egg

In which part of a bird's egg, would you find the embryo? In the White or in the Yolk? Thanks Adrian - Malta 212.56.130.105 04:29, 19 April 2006 (UTC)

• You don't, if you're talking about chicken eggs, they're not only sterile, but unfertilized, so no zygote to be found--64.12.116.74 04:35, 19 April 2006 (UTC)
  • Perhaps you might be interested in reading Egg white ad Egg yolk. -- Rick Block (talk) 04:46, 19 April 2006 (UTC)
  • Free range chicken eggs are sometimes fertilised (presumably only if there's a rooster around). It's no problem, just a little speck of colour in the yolk.-gadfium 06:47, 19 April 2006 (UTC)
• In the yolk, if the embryo is present. The white is mainly for protection and nutrition for the embryo Wikicheng 06:42, 19 April 2006 (UTC)
  • I always thought the embryo rests on the yolk, so you would find it at the interface between the white and yolk --Dunstan 11:26, 20 April 2006 (UTC)

3D modelling techniques

It is easy to comprehend a printer printing a 2D image, but how does the 3D polymer model maker work?

One way of modeling is building up layers of material. Basically, the printer deposits a uniformly thick 2-D layer on a substrate. This substrate is moved down a little bit and the printer deposits another layer on top. The layers build until there is a 3-D model. Refer to Fused deposition modeling or Stereolithography for more detail. --Joe 16:49, 19 April 2006 (UTC)

A CNC machine can also carve a 3D model out of block of material, such as steel, while an LOM machine cuts layers of paper and glues them together to form an approximate "wooden" model. StuRat 20:22, 19 April 2006 (UTC)

Diagrammatic

What is this and who is it named after?

http://img106.imageshack.us/img106/7508/tb44ri.gif

Thanks

that looks like a diagram describing how an electron (the left arrows) is transformed into a positron (the right arrows), first by emitting a gamma ray (the lower purple line) and then by interacting with a 'q'. That's all I can work out sorry, hopefully someone else can shed some light on it --Dyn.iinet.net.au 16:24, 19 April 2006 (UTC)

That's a Feynman diagram, obviously named after Tina Fey and Iman. No, wait: Richard Feynman. --ByeByeBaby 19:45, 19 April 2006 (UTC)

Thank you very much

Psychology: processes in mind when man meets an unexpected thing

While a talk at science fiction-related forum, we encountered a question without clear answer. Whatever an abstract question, it interests us. Imagine you have suddenly met a real extraterrestrial. What will happen in a man's mind who sees something that "defies all logic"?

We have various POVs:

• a) "Would any normal mind be forever snapped if something so incongruent suddenly popped in front of my face?" + "Perhaps they are so incongruent from what we can handle that our minds simply block them out."
• b) Man will experience a "shock", which will wear off after some time(may be, a matter of hours, days or weeks).
• c) "Most people would completely freak out if they were confronted with anything outside of the expected." + "Some people stay in shock for the rest of their lives."

It would be especially interesting to hear a comment of a psychologist. ellol 16:28, 19 April 2006 (UTC)

I don't think any of those things would happen. A life form relatively like ours would take some getting used to, that's all. A totally different life form may not be recognized at all, however. For example, if the electromagnetic storms on the Sun are some form of life, we may never recognize them as such, especially if they only have one "thought" every million years. StuRat 20:10, 19 April 2006 (UTC)

I don't think people would have any problems at all. They'd have a little disbelief for a while, that's all. We've encountered plenty of new species, (although none extraterrestrial). The first time Europeans encountered the platypus the immedate reaction was "Oh that's a fake! Who put that duck-beak on a beaver?". Which also shows how we immedately try to fit new things into the things we already know. When Marco Polo first saw a Rhinoceros in Sumatra, he immediately went through the "list of known animals" in his head, found the closest match and drew the completely wrong conclusion: "That's a very ugly unicorn." of course, with more experience we all know that platypi are perfectly normal platypi and not mutilated beavers and rhinos are just rhinos and not obese unicorns. Similarily we'd pretty soon accept an alien being for what it was. It's worth pointing out that unicorns don't actually exist. That didn't stop Marco Polo from accepting it once he saw something he thought was one. So presumably, most of us today have read enough about extraterrestrials to be prepared to accept the fact if we did actually run into one. --BluePlatypus 20:35, 19 April 2006 (UTC)

Now that I think about it, it's noteworthy that there's are a lot of people who are so prepared to accept extraterrestrials that they'll choose them to explain things even when there are other, far more likely, explanations. :) --BluePlatypus 00:49, 20 April 2006 (UTC)

Thank you for the interesting answer :-) Sometimes people have a too pessimistic outlook on future progress. E.g., I've heard that before the first human flight into space, there were claims that a man couldn't live in weightlessness. ellol 05:51, 20 April 2006 (UTC)

The idea of "snapping" or "shocking" the mind with such an event seems to be related to the motif of harmful sensation. There's very little in the way of substance to it. --Tardis 21:31, 19 April 2006 (UTC)

Thank you. And I've posted your answers in forum at distantworlds.net . ellol 06:04, 20 April 2006 (UTC)

• This is Wikipedia. Things that "defy all logic" happen all the time here. -- Filliam H Muffman 20:27, 21 April 2006 (UTC)

Evolution of sex

How were male and female sexes developed from single cell organism thru evolutionary process?

Check out our article on sex, which links to our article on evolution of sex. TenOfAllTrades(talk) 18:18, 19 April 2006 (UTC)

Point in ocean most distant from any land mass?

I was wondering whether anyone has calculated the GPS coordinates of the point on the world's oceans furthest removed from any land mass. I am guessing that Bouvetoya qualifies as the most removed island from any other landmass, but as for the maritime point I'm guessing it's somewhere in the North Pacific or the Arctic. If you've figured this out, please let me know. Thanks!

Check out extreme points of the world#Remoteness; it sounds like you want "Point Nemo". — Lomn Talk 21:15, 19 April 2006 (UTC)

Thanks! I should have found that...

Mistake In The Way Wikipedia Search Handles Escape Code %27?

I put "MacConkey's agar" into the Wikipedia search box built into my web browser (Opera) and I was taken the search page as though I'd search for "MacConkey%27s agar". I clicked on the 'MacConkey%27s agar' link to make a page called 'MacConkey%27s agar', and it instead took me straight to MacConkey's agar. I think this is a mistake, no? --Username132 (talk) 20:11, 19 April 2006 (UTC)

Congratulations, it looks like you've discovered a bug in MediaWiki's search not escaping the "%" character. Someone should probably report this on the MediaWiki bug tracker, but I don't particularly like the premise of having to do the song and dance of registering just to report a bug - surely a valid email address should be all that's needed? --Sam Pointon United FC 21:39, 19 April 2006 (UTC)

Actually - scratch that, it looks like a deliberate thing done by the string-to-link converter, automatically expanding/collapsing out %xx escape codes. Don't blame me, it looked like a bug at first. --Sam Pointon United FC 21:42, 19 April 2006 (UTC)

My guess is that your Opera Wikipedia box expands all the advanced characters and then directly tries to access the page, which bypasses Mediawiki's expanding/collapsing automaticisms. Rather silly thing for a search box to do, but it doesn't appear to me that Mediawiki is doing anything strange.  freshgavinΓΛĿЌ  03:48, 20 April 2006 (UTC)

How To Get Free Clean Water?

I was wondering how travellers get their clean water? -Username132 (talk) 20:18, 19 April 2006 (UTC)

Usually using money. WAS 4.250 21:27, 19 April 2006 (UTC)

Usual methods include boiling, filtration, and chemical disinfection (iodine or chlorine pills). Visit a place that sells camping gear (like REI, or see rei.com) and they'll have tons of stuff like this. Most developed countries have drinkable tap water though. Phr 21:29, 19 April 2006 (UTC)

Sorry, I didn't mean like that, I meant the travellers that move around the UK and other devloped countries in caravans. Some have let themselves in to a disused industrial site. I'm wondering how they tap in to the mains supply? --Username132 (talk) 22:51, 19 April 2006 (UTC)

At a guess, there may well be standpipes or fire hydrants accessible, or just random mains plumbing that can be used if they find the right tap to turn it on. -- AJR | Talk 00:11, 20 April 2006 (UTC)

And that's assuming that they're health concious. I'm sure a good number of them don't get clean water, and just deal with the side effects.  freshgavinΓΛĿЌ  03:43, 20 April 2006 (UTC)

Does too much water make you poo?

I've heard a theory that drinking "too much" water can make you need to defecate. Is this possible? --Ukdan999 21:23, 19 April 2006 (UTC)

Try it and see; then give us your report. GangofOne 21:29, 19 April 2006 (UTC)

Not in my experience. If you drink too much water, it upsets your electrolyte balance and your kidneys excrete it as clear urine. See Water intoxication. —Keenan Pepper 21:46, 19 April 2006 (UTC)

Not true, but abstaining from liquid can constipate you. Brian G. Crawford 23:34, 19 April 2006 (UTC)

Why are no land animals bigger than elephants?

Long ago there were dinosaurs maybe 5x the size of today's elephants. They all got wiped out by a meteor, but so did everything else that was large, and it all had to evolve again. Is there some reason that elephants are the biggest that we have now? Could dinosaurs survive anyplace in today's ecosystem? Or is there just not enough oxygen in the atmosphere or something like that? We do have aquatic mammals (whales) that are even bigger than dinosaurs were. Phr 21:33, 19 April 2006 (UTC)

I'm not an evolutionary biologist, but today's dominant creatures appear to all be warm-blooded. It takes an absurd amount of energy to keep an elephant warm, and it only gets worse as the animal gets larger, so that won't happen without a good reason. Presumably we could re-develop gigantic exotherms, but the speed and adaptability advantages of the endothermic mode would likely prevent the megalizards or so from competing well. --Tardis 21:49, 19 April 2006 (UTC)

see Paul Colinvaux, Why Big Fierce Animals are Rare, mentioned in overpopulation and see also http://courses.washington.edu/anth457/energy.htm ; it's about thermodynamic efficiency, like Tardis says. Also, bigger land mammals would have to be slow moving, and thus at a disadvantage. --GangofOne 22:32, 19 April 2006 (UTC)

Two other notes are that the Cenozoic era has only been going for 65 million years, where the dinosaurs had the Mesozoic, which lasted for 180 million years, so they had a lot longer to evolve bigger. Elephants are the biggest land mammals ever, so it's not like mammals are regressing in size. (Of course, early humans probably killed most of the megafauna, so there did use to be a greater variety of big animals.)

I thought mammoths were an older, larger version of the elephant. StuRat 01:02, 20 April 2006 (UTC)

The second note as far as a possible limiting factor is that there's also a structural element involved; bones, muscles, tendons, etc. have a certain strength. The strength of a bone is more-or-less proportional to the cross sectional area, but the weight of an animal is proportional to the volume. So if you made an elephant twice the size (i.e. doubled every dimension), the bones would have roughly four times the strength of the original ones, but they would have to support a creature that was eight times as heavy. This is one of the reasons why the largest organisms tend to be marine; the salt water counters the effect of gravity. So we have whales versus elephants; large insects versus lobsters and so on. --ByeByeBaby 23:46, 19 April 2006 (UTC)

Thanks, yes, I understand about how the square-cube law affects elephants, and GangofOne's remarks about energy efficiency and overpopulation make sense. But those lead to back to the original question (recast): if elephants are about as big as land animals can get, how could there ever have been dinosaurs? What was different? Phr 00:05, 20 April 2006 (UTC)

Note that he said elephants (or mammoths, according to StuRat) were the largest land mammals. Dinosaurs were not mammals. — QuantumEleven | (talk) 11:18, 20 April 2006 (UTC)

Well, some constraints on size are cooling systems, bones that can supports one's mass, getting sufficient oxygen, getting sufficient food, and a nervous systems fast enough to react in time to prevent disasters. As for nervous systems, even humans need a somewhat distributed nervous system, where reflexes act quicker than the brain can react. Without this we would step on a nail and have it go all the way through our foot before we reacted. In a much larger animal, you would need local nerve centers to control things like walking, independently from the brain. While these abilities probably existed in dinos, they were lost when they were wiped out. They could evolve again, and likely would have in another hundred million years. But, since people get nervous around animals much larger than them, we aren't likely to permit evolution of larger animals to continue. StuRat 01:02, 20 April 2006 (UTC)

It's all a question of ecology, not physiology. If it was the latter, we wouldn't have had dinos in the first place. From what we know, the climate and atmosphere aren't really terribly different from back when the dinosaurs lived, so that's not the problem. The likely (IMHO) reason is that when the dinos got knocked out, it was followed by (or consisted of) a period of cold climates. During that critical period, only the small lizards survived, but the mammals apparently did better. Today, while the climate can once again support larger lizards, the ecological pressure from the mammals presumably doesn't permit them to evolve that way. --BluePlatypus 03:22, 20 April 2006 (UTC)

No one knows and there is a lot of debate among the experts. See Giantism.html. WAS 4.250 20:36, 20 April 2006 (UTC)

Cylinder Gap

What are the advantages of having a wide/short cylinder gap when tuning up a revolver? The booklet I read gave very leinant settings, from .002-.009. What is the difference between the varying settings? What setting makes a revolver function correctly for the longest period of time? Does it vary from revolver to revolver? Thanks, 161.45.196.221 21:44, 19 April 2006 (UTC)

From Speer Reloading Manual: Number Thirteen:

Industry specs call for a MAXIMUM gap of 0.012 inch. Unfortunately, there are many revolvers in use, both originals and replicas, that exceed this value. Realistically, 0.012" is quite generous. For light loads, this gap should be much smaller–close to the minimum dimension that still allows a cylinder to freely rotate when it is dirty...An excessive gap allows too much gas to escape. There isn't enough pressure left to push the bullet down the bore. The lighter the load, the more likely that a large gap will cause a bullet to stop in the bore.

Hope that helps. EricR 23:05, 19 April 2006 (UTC)

Ah, I see. Thank you for responding so throughly. So that would mean that the gap for a standard FMJ round would be smaller than when using a hot-loaded round of the same type due to the fact that a hot-loaded round would produce more pressure and therefore need a bigger gap; however the gap for an unjacketed round would be smaller than the gap for a standard FMJ round due to the decreased size of the bullet and therefore less pressure required to push it down the bore/barrell.

I do have one more question, though. How does the cylinder gap come into play when firing an unjacketed round? I have encountered 'leadening' before, where firing too many unjacketed rounds causes excess lead and grit to foul the bore of the revolver and cause malfunctions (namely, the hammer refuses to operate). If one set the cylinder gap to a wider setting as opposed to a shorter one, would this problem be avoided more easily? I am aware that 'leadening' is a unavoidable eventuality when firing unjacketed rounds, but would a longer cylinder gap postpone the onset of it when firing the rounds?

Thanks, 68.52.56.111 02:42, 20 April 2006 (UTC)

.wav to .ogg

I have the .ogg software installed on my computer, and I have no difficulty listening to .ogg files. However, I have a .wav file on my desktop; I open the file and try to save it as .ogg, but the .ogg option is not available.

How do I change the sound file to .ogg and save it on my desktop again? I have interested in uploading the file to Wikimedia which does not accept .wav files.Patchouli

Use Audacity. Henry^Flower 23:05, 19 April 2006 (UTC)

• Thank you.Patchouli 23:42, 19 April 2006 (UTC)
• Or Foobar 2000. - 131.211.210.15 07:58, 20 April 2006 (UTC)

Waxwing Birds

is the cedar waxwing bird extinct? healthy? is it's species healthy? thank you

The Cedar Waxwing is doing fine, and sends it's regards. The Japanese Waxwing] is listed as a nearly threatened species, however. --ByeByeBaby 23:21, 19 April 2006 (UTC)

April 20

chainmail armour?

how did they make this even before they had metal working tools?Cyoda mackbuy 21:27, 7 April 2006 (UTC) (copied from the archives page, where it was wrongly asked zafiroblue05 | Talk 00:48, 20 April 2006 (UTC))

See chainmail-gadfium 01:37, 20 April 2006 (UTC)

• Very slowly and at great expense. Although in a broad sense, they would have had some metal working tools as soon as they had metal. Even today, making chainmail is expensive and labour-intensive compared to ordinary fabrics. Peter Grey 06:25, 20 April 2006 (UTC)

Fatal Blood Loss

How much blood can a person lose and still survive? At what point (i.e. how many pints or liters, considering normal is ~9 pints or ~5 liters) does blood loss become fatal? KT24.124.51.110 01:16, 20 April 2006 (UTC)

Well, off the top of my head, a hemorrage is any blood loss of more of 500 ml, and our article on bleeding says that after 1 liter lost, it can be fatal. Titoxd^{(?!? - help us)} 03:53, 20 April 2006 (UTC)

"Hemorrhage" refers to any amount of bleeding. How much blood can someone lose and still survive depends on a number of factors: their general health, presence of underlying medical conditions (for example, coronary artery disease, how much blood they started with, and if they receive timely resuscitation or transfusion. - Cybergoth 01:30, 21 April 2006 (UTC)

Script for Wikipedia

Is there a script that can change my homepage (using Opera) to the wikipedia page relative to that day? (IE, it's April 20th, therefore my homepage is set to http://en.wikipedia.org/wiki/April_20). I was wondering if one existed, or if this already exists serverside (like a "Special:Date" page that does this). If not, what would be the easiest way to write a script/program to do this? I was thinking of using either Javascript or Java. - BlazeWizard (Not registered) - 3:58 PM.

I believe you can do it if you create a template in your user space that redirects to the page of the date, and there is a variable in mediawiki that gives you the date. Let me check it out.  freshgavinΓΛĿЌ  05:51, 20 April 2006 (UTC)

Like this: User:freshgavin/Sandbox/Redirect to date page. It was much easier than I expected.  freshgavinΓΛĿЌ  05:55, 20 April 2006 (UTC)

That doesn't redirect, though — at least not for me. It seems that mediawiki isn't recognizing the redirect construct and is instead just treating it as a list. — Asbestos | Talk (RFC) 15:45, 20 April 2006 (UTC)

Yeah I noticed that and I was looking through MediaWiki to see why it doesn't recognize it. Apparently in a case like this (it is treated as a special page) redirects are ignored by MediaWiki, even with the ?redirects=yes tag. I'm pretty sure there's no way without JS or bruter, as described below.  freshgavinΓΛĿЌ  07:02, 21 April 2006 (UTC)

Thanks for the replies guys, I did however come to a very simple solution to do this. Simply create my own html page with a javascript that uses my computer's date to generate a url, then redirect to that url. Here:http://en.wikipedia.org/wiki/User:BlazeWizard - BlazeWizard 7:447 20 April 2006 (UTC)

Speed of Light

I actually have two questions:

1) Has any headway been made in the field of quantum physics suggesting that Einstein's assertion that the speed of light is the definitive speed limit that any object can move is no longer accurate? (sorry for the run-on sentence!)

2) This may be a silly question, but bear with me. When at a concert or some other event where "flood lights" are used, it appears to my eye that the lights actually "flood" from there source to their destination. In other words, it appears that I'm witnessing light travel from its source (the flood lights) to its destination (the stage). I'm sure I can't possibly be witnessing the actual speed of light in action. That can't be right. Yet it still appears that the light beam, in a split second, is travelling from its source to its destination. Assuming I'm not actually witnessing the light travel, what optical illusion is at work here?Loomis51 04:18, 20 April 2006 (UTC)

1) It's not an assertion, it's a consequence of certain postulates. (which could be called assertions) It can only be false if A) Nature suddenly starts ignoring the rules of logic we've used to describe it so far (In which case Science is useless and we shoud all just go home) or B) One of the postulates of relativity is false. AFAIK, nothing in QM has invalidated those postulates.

2) Presumably you're just seeing the light intensity increase to its maximum as the bulb gets warmed up. --BluePlatypus 05:17, 20 April 2006 (UTC)

To expand on BluePlatypus' answer to 2), your eye can probably see the bulb (begin to) light up before it is bright enough to (noticeably) spread light to the surrounding surfaces, and your brain fills in the sequence by assuming that the light flows from the bulb (which appeared brightly first) to the surrounding surfaces.  freshgavinΓΛĿЌ  06:33, 20 April 2006 (UTC)

Also... in general, when a light illuminates a distant object you should be able to see only the light itself and the object. You shouldn't see the light passing between. If you do, it's because the light is bouncing off (and illuminating) something between. Outdoors, there is often water vapour in the air. For indoor concerts there may be deliberate smoke or mist for atmosphere. So when a floodlight it turned on, it looks as if you are seeing the light "pass through the air". In some cases the heat of the light will change the character of the things in the air close to them, as well. Notinasnaid 10:57, 20 April 2006 (UTC)

Camparison of 1st magnitude star and light bulb

I'm trying to give a someone comparison of brightness. Approximately how far away would a 60-watt light bulb have to be to have the same aparant brightness as a first-magnitude star? Bubba73 (talk), 04:21, 20 April 2006 (UTC)

First of all, as I've recently learned (thanks to Jayant!) wattage is not a measure of brightness, it's a measure of electricity required. Nonetheless, it would appear to me that you could virtually stick the 60-watt bulb in your eye and it still wouldn't compare to the brightness of a first-magnitude star. Loomis51 04:41, 20 April 2006 (UTC)

A first-magnitude star isn't really all that bright, if I'm reading apparent magnitude and absolute magnitude correctly. However, intensity decreases with the square of the radius...that probably factors in somehow. I'm not a physicist, but that's my shot at it. Isopropyl 04:48, 20 April 2006 (UTC)

Right - wattage is the energy used, not the brightness. So suppose the light bulb is 1,000 lumens. How far away would that have to be to have the aparant brightness of a first magnitude star? Bubba73 (talk), 05:19, 20 April 2006 (UTC)

Well, I've found the figures I need to do the calculation, which I'll do tomorrow. Bubba73 (talk), 05:26, 20 April 2006 (UTC)

Since you're giving someone a comparison, why not turn on a 60-watt light bulb, look at it, go outside, and look at a first-magnitude star? I'd recommend Spica from Virgo, or Pollux from Gemini. --Bowlhover 15:49, 20 April 2006 (UTC)

Because I want to know at what distance the light bulb would have to be to be as bright as an aparant first magnitude star. I guess I could try different distances and approximately determine it, but I'd rather just calculate it. Bubba73 (talk), 17:26, 20 April 2006 (UTC)

In order to represent the brightness of a star in "human" units like lumens instead of "objective" units like watts, you need to know the spectrum of the objects involved. The reason that a 100-watt light bulb doesn't produce "100 watts of light" is that its emissions follow a blackbody spectrum (like most everything) and most of it isn't visible; moreover, it doesn't even quite radiate 100 watts of photons because it conducts some of its energy away through the air. But we can try a couple of very very rough approximations:

1. Just compare the total radiance of the two sources, neglecting conduction for the bulb and the differences in the spectra (which are not necessarily all that great; tungsten light bulbs can be run at up to 3000 K, and the Sun's photosphere is "only" 5800 K — but remember that we could be talking about a blue supergiant star at great distance from us, too).
2. Consider the maximum theoretical luminous efficiency as noted in the light bulb article, and compare that with the known luminous output of the light bulb (850 lumens, from the article).

For either of these we need the luminosity of your first-magnitude star at some distance. Let's suppose (very unphysically; this part is just bookkeeping, not physics) that the star is at the distance of the Sun but still appears first magnitude, so its luminosity (output at all wavelengths) is $100^{(-26.73-1)/5}L_{\bigodot }=3.096\times 10^{15}{\mbox{ W}}$.

1. This is obviously $5.16\times 10^{13}$ times the output of the bulb. The inverse square law says that to get equivalent brightnesses, we need a distance ratio of $7.183\times 10^{6}$, so the bulb should be at $1{\mbox{ AU}}/7.183\times 10^{6}=20.83{\mbox{ km}}$ distance.
2. Alternatively, rate the star (with $95{\mbox{ lm/W}}$) at $2.941\times 10^{17}{\mbox{ lm}}$, which is $3.46\times 10^{14}$ times the output of the bulb, giving $8042{\mbox{ m}}$ as the appropriate distance.

So "across town" (for some size of town) is probably the best we're going to be able to say without considering the luminosity function. Hope this helps. --Tardis 17:59, 20 April 2006 (UTC)

Yes it does. I have just done my calculations by a different route, and I got about 13 miles (20.6 km). Bubba73 (talk), 18:06, 20 April 2006 (UTC)

My calculation: I found on a website that the Sun is 10^24 times as bright as a 400 watt bulb. I took that to be approx 6.7 x 10^24 times as bright as a 60-watt bulb. That is a 62.06 difference in magnitude between the sun and bilb, putting the bulb's absolute magnitude at 66.86. Distance for that to have an aparant magnitude of 1 puts it 6.73 x 10(-13) parsecs away, 12.9 miles. Bubba73 (talk), 18:13, 20 April 2006 (UTC)

Google Calendar-Palm synchronization

The new Google Calendar is absolutely amazing, but of course a glaringly lacking feature is the ability to communicate with or syncrhonize with PDAs. I use my Palm Treo extensively, and despite the advantages of an online calendar like Google's there is no way I can switch to using it if it can't talk with my Palm. I Do you think that Google is working on a way to enable synchronization? Does anyone have any ad hoc solutions? I was thinking about synchronizing my Palm with Outlook instead, then exporting the data to GCal, but I'm not sure how the reverse would work. I think I could use Outlook to pick up the data from Google's Ical web page, but it would be a pain to manually re-synchronize every day and besides, I worry that just copying the entries back and forth would lead to errors, such as multiple copies of an event appearing each time the data are imported. Any ideas or suggestions? — Knowledge Seeker দ 06:57, 20 April 2006 (UTC)

Right now, I don't know of any solutions, but given the way additional utilities like Gmail Drive have been created by third-party users (not to mention the plethora of sites using Google Maps), my tendency would be to wait for a couple of months; I'm sure that Google knows that PDA sync is a big missing feature, and I'm equally sure there's a thousand good hackers who really want to sync Palms with Google calendar. I've had a multiple-copies of events problem with a Palm in the past (in fact, there were a couple of bad syncs, so I wound up with four copies of everything). Personally, I'd be tempted to see if a good solution isn't right around the corner, either from clever open-source hackers or Google itself. I know it's not the answer you're looking for, but I'd rather keep with the old system until June rather than risk screwing up all my schedule data. --ByeByeBaby 23:33, 20 April 2006 (UTC)

Optimal Resolution For Graphics Card

My old graphics card allows 1024 x 800 at 70 Hz, but down at 800 x 600 only 60 Hz. Now I thought that a lower resolution would be easier on the graphics card and allow a higher frequency - do graphics cards find higher resolutions easier to produce? --Username132 (talk) 07:15, 20 April 2006 (UTC)

Generally, a higher res will have a lower refresh rate, but there are exceptions. Maybe someone else can explain the exceptions. StuRat 08:02, 20 April 2006 (UTC)

The refresh rate is the rate the screen is refreshed. in LCD/TFT screens where only changes alter the image it is not very important in Cathode ray tubescreens it does matter since a low refresh rate can be visable to the eye in the form of a "flickering" image. Generally speaking a higher refresh rate is easier for your eyes. Monitors/video cards however have trouble displaying higher resolutions at high refresh rates. It is recommended to use a refresh rate of at least 75Hz on a CRT monitor. The actual digital signal of a Video card is converted to a analog one via the videocards RAMDAC video cards with a old/low quality ramdac might have trouble displaying high resolutions with a high refresh rate (higher datastream)But to sum op your question. No they should not find it easier.. try setting the refresh rate manually ;) --Magicmasta 12:44, 20 April 2006 (UTC)

Basically, 800x600 and lower resolutions are for some reason different than higher ones, and have been like that for a while, though it didn't always used to be that way. 640x480 and 800x600 are often limited to low refresh rates with new video cards/on new monitors and I don't really know why but I've always assumed it was because 800x600 and lower resolutions were no longer "priority resolution ranges" for monitor companies and so they don't bother programming them to perform with optimal settings. Notice that the color range is also limited with low-res settings, thought that may be because of a completely different reason.
There may be a technical reason that high-res monitors/video cards can't handle high-freq/high-color settings with low-resolutions, possibly to do with pixel size, but unfortunately I know little about electronics so I can't give you a straight answer : (.  freshgavinΓΛĿЌ  05:25, 21 April 2006 (UTC)

Quantum Electrodynamics

An electron (1) repels an electron (2) because one of them (1) emits a virtual photon which alters the other's path (2) and thus recoils (1). Why does it "know" when to emit the photon when encounters another electron? Also, is it that the electron created the virtual photon from nowhere? Can anyone also explain why an electron attracts a proton? Is it similar to the previous phenomenon? Thanks! - Just Love Science

It doesn't have to know "when" to trade a virtual photon. The way it actually works is that the probability for the repulsion of the two electrons is given by a sum of all possible ways for the virtual particle to get exchanged. This is an example of quantum weirdness, it's a general phenomenon in quantum theory: you get from the initial state to the final state by summing the amplitudes for all possible paths between. The electron scattering has to sum not only over all the ways to trade a photon, but also the ways to trade two photons, three photons, a photon that splits and recombines in the middle, etc, etc, etc. As for the difference with attractive forces (like between a proton and electron), there really isn't a difference. The minus sign from the charge ends up determining the direction of the momentum transfer, so it goes in the other direction, but it's still a virtual photon exchange. -lethe ^{talk +} 07:44, 20 April 2006 (UTC)

You might enjoy this article from the physics FAQ. -lethe ^{talk +} 07:51, 20 April 2006 (UTC)

Apollo Missions Purifying Agent

Given that the sodium salt of the purifying agent is cheaper and more commonplace why do you think it wasn't used on the Apollo missions?

I assume you mean the carbon-dioxide absorbing filters for the air, which IIRC used lithium hydroxide. I always thought that was to save every gram of weight possible -- 1 mole of sodium hydroxide weighs 40g, 1 mole of lithium hydroxide weighs 23 grams. i.e substituting lithium for sodium gives you the same CO₂ absorbtion capacity for 0.575 the mass. Malcolm Farmer 09:19, 20 April 2006 (UTC)

In addition to the weight issue, sodium hydroxide is extremely hygroscopic—it very readily absorbs water from the air. If you leave a pellet of sodium hydroxide (NaOH) on the lab bench, it will sit there absorbing water until it dissolves into a little puddle of concentrated NaOH solution. Obviously this would present handling problems, particularly in space. While LiOH is also hygroscopic, it is to a much lesser extent. So safety and ease of handling are a couple more reasons to use lithium hydroxide. TenOfAllTrades(talk) 13:26, 20 April 2006 (UTC)

Virtual LBW accurate ?

Well if you watch Cricket matches. You would possibly see a LBW appeal. Then the T.V. Broadcaster or the necessary concerned would show a virtual Field with no Batsman. And the Ball would be in motion to show whether it was really Leg Before Wicket (LBW).But is it 100% accurate ? Will it be able to take completely the wsing, the pitch , the wind etc. --Oasa 10:48, 20 April 2006 (UTC)

I don't think anyone would claim it's 100% accurate. I would imagine that issues like wind shouldn't be important, though, because the trajectory is presumably based on the video of the ball -- any effects like that would be already present in the data used for the extrapolation. But I don't know for sure how they come up with the projection. --Bth 11:02, 20 April 2006 (UTC)

I heard somewhere that, that technology was used to track missiles... so, i guess its pretty accurate...but if a batsman happens to come forward and hit the ball on full toss...the technology might fail in predicting the balls movement after if it had bounced... Jayant,17 Years, India • contribs 15:31, 20 April 2006 (UTC)

The system is called Hawk-Eye, and its accuracy is apparently "measured in milimetres"[11] (that claim comes from the people who make the software for it, so should perhaps be seasoned to taste.) -- AJR | Talk 23:55, 20 April 2006 (UTC)

Eggs

I feel very daft asking this, as I'm sure there is a very simple explanation: When chicken hens lay eggs, are they already fertilised (ie if you keep them in a warm place they will eventually hatch), or are they only fertilised later? If the latter is true, how (as the egg is enclosed in its shell and sealed off from the outside, save for very small pores for breathing)? And what is the biological point of hens laying unfertilised eggs with no rooster around (as I presume is the case in most commercial egg production factories), as they will not get any chicks out of them? — QuantumEleven | (talk) 11:27, 20 April 2006 (UTC)

The eggs are internally fertilized. That's what sex is for. Most aquatic organisms however, do external fertilization, like salmon for instance. English I presume? -- Mac Davis] ⌇☢ ญƛ. 11:54, 20 April 2006 (UTC)

More specifically, the fertilisation happens in the oviduct before the egg is surrounded by the yolk,albumen, shell, etc. As for the "biological point" of laying unfertilised eggs, I'm not sure, but given that the tendency exists it's certainly been bred for over millennia of domestication (and of course in general the trait only has to not be selected against once present -- there doesn't necessarily have to be a positive "point"). (Some info here but none on the "point" of laying unfertilised eggs. Semi-interestingly, searching for this brought up a vast amount of abstruse controversy about vegetarians about whether eggs are veggie-kosher and if so which sort.) --Bth 12:15, 20 April 2006 (UTC)

As a moment of wild speculation, I might guess that the purpose of laying unfertilised eggs is somewhat similar to the purpose of menstruation - to make sure that everything is in prime condition (dare I say it, "fresh") for fertilisation. Confusing Manifestation 12:18, 20 April 2006 (UTC)

Heh, you have edit conflicted me as I was adding that to my answer. --Bth 12:23, 20 April 2006 (UTC)

It is most certainly a trait which was specifically bred for -- there is very little evolutionary advantage that I can see in laying unfertilized eggs (though perhaps if you were expecting predators to steal a few, having "extra" eggs might decrease the likelihood of them getting one of the fertilized ones). In any case, in the case of modern chicken breeds (such as the Leghorn (chicken)), they have been specifically bred to be able to produce high volumes of unfertilized eggs. --Fastfission 15:36, 20 April 2006 (UTC)

White spots in nails

I sometimes have white spots in my nails. People say it's due to a lack of calcium, but I'm not sure whether that's true or not. What do you think?

Here's a nice article. [[12]] There are, apparently, zillions of possible causes. --Zeizmic 14:04, 20 April 2006 (UTC)

It is not a sign that you lack calcium. - Cybergoth 01:45, 21 April 2006 (UTC)

about jobs inbioinformatics in india

Sir , I want to know that can an computer engineer can enter in bioinformatics field.If so then how . Please guide me .

Sure. If you look at the bioinformatics article, you'll see all the other field that relate to it. Having some knowledge of statistics, DNA, protein folding and evolution will probably put you at an advantage. I know, though, that the Bioinformatics Master's course at my old university, Edinburgh University, really only expected knowledge of coputer science. I'd recommend looking at the department websites for universities in your area. — Asbestos | Talk (RFC) 15:38, 20 April 2006 (UTC)

Calculating the curve when one wheel is faster than the other

I'm writing a little program modelling a simple robot. The robot has two wheels, one on either side. It turns by making one wheel faster than the other. I'm just taking into account absolute speed — acceleration is instantaneous. If the left wheel is at speed x, and the right wheel at speed y, how do I calculate the robot's position and orientation at time t + 1?

Any advice would be really helpful! --Mary

Depends upon how far apart the wheels are.

Ok, set any distance: one unit. --Mary

Assume y>x without loss of generalization. Hence the robot translates along a straight line (in the direction of x in the last time step) with speed x. Also the wheel with speed y will try to rotate with an angular velocity (y-x)/d. Where d is the distance between the wheels. You can superpose these motions together to find the position at the next time step. Hope that helps. --coolmallu 16:45, 20 April 2006 (UTC)

Well, I worked it out using the info at http://rossum.sourceforge.net/papers/DiffSteer/. Rather complicated, but I think I got it. Thanks, --Mary

I didn't understand your comment that "acceleration is instantaneous". That's impossible, an infinite accel would require an infinite force or zero mass using F = ma. StuRat 17:30, 20 April 2006 (UTC)

Not it is not, all you do start the time when the robot is moving at top speed, then the accelleration is zero.

I think she means to use the simple approximation that the robot starts at rest at position 0, but then instantly starts off with the wheels going at speeds x and y, so you don't have to worry about the effects of gradual speeding-up. You could just consider starting with the robot already moving. Confusing Manifestation 18:15, 20 April 2006 (UTC)

She never said she was actually building the robot. It's just a computer model.  freshgavinΓΛĿЌ  05:12, 21 April 2006 (UTC)

bromine

how the bromine produced industrially?

Bromine is a chemical element, so it might be more appropriate to ask how it's extracted than how it's produced. Bromine#occurrence does have some details about the extraction methods. StuRat 17:15, 20 April 2006 (UTC)

The question was probably about the substance Br₂, which is produced from brine by electrolysis. —Keenan Pepper 17:26, 20 April 2006 (UTC)

Ironic since you can produce brine from bromine by extracting the "om". Grutness...wha? 02:42, 21 April 2006 (UTC) (OK, I'll shut up now)

I was just going to say RTFL Bromine, but gosh-golly it doesn't say. I got this from a USGS report:

Based upon USGS estimates of quantities produced during 2000, Arkansas continued to be the leading bromine-producing State, accounting for most U.S. production. Michigan was the only other State that produced bromine. Mining operations in both States extracted subsurface, bromine-rich natural brines by submersible pump for subsequent processing. --Zeizmic 17:17, 20 April 2006 (UTC)

Keratin

What is the chemical formual for keratin? Like, water is H2O, and the hydrogens connect to the oxygen at the 100 degree angle. 64.198.112.210 15:57, 20 April 2006 (UTC)

First off, Keratin isn't a molecule in the same sense that water is, it's a protein. Proteins are chains (sometimes balls of tangeld-up chains) of amino acids linked together. I can give you some clues on which elements it contains, though:

All amino acids contain Carbon, Hydrogen, Oxygen and Nitrogen, furthermore, keratin is a textbook example of a protein rich in Sulfur, 24% of it being made up from Cysteine, a Sulfur-containing amino acid. -Obli (Talk)^? 16:10, 20 April 2006 (UTC)

I mean chemical structure, sorry. And more like the pictures that you draw to show how molecules built, like the third part of the first picture in molecule. 64.198.112.210 16:01, 20 April 2006 (UTC)

As stated in my previous answer (which was answering the wrong question), Keratin is made up from numerous amino acids, the sequence of them detemining how they will attract each other and how the chain will bend. I found this picture of how amino acids interact, it's not the structure of keratin, but it shows the general makeup of a protein. -Obli (Talk)^? 16:23, 20 April 2006 (UTC)

Proteins have four levels of structure: primary, secondary, tertiary, and quarternary. For this reason, models of proteins tend to be very complex. Is there a specific reason you need the crystal structure of keratin? Perhaps the information might be found in other ways. Isopropyl 00:31, 21 April 2006 (UTC)

Three-dimensional structures of proteins (determined mostly by x-ray crystallography, sometimes by NMR methods) are deposited in the Protein Data Bank. That article also tells where one can find viewers. (I like pymol). Unfortunately, when one throws the keyword "keratin" at the database, no hits come up. If you are interested only in the amino acid sequence you will want to look at the Swiss-Prot sequence database. Dr Zak 02:33, 21 April 2006 (UTC)

Intermittent hormone therapy

I am trying to find information on: intermittent hormone therapy treatment for Prostate Cancer.

Thank you. -------

Are you talking about testosterone blockers ? StuRat 17:09, 20 April 2006 (UTC)

I always thought nowadays uses compounds that decrease the level of testosterone in the body. GnRH is the first hormone in the regulatory chain, then come FSH and LH, which in turn act on the level of steroid hormones. GNRH1 analog is another good keyword. And look out for the name of Ralph Hirschmann at the University of Pennsylvania. He had a hand in the research during his tenure at Merck. Dr Zak 22:50, 20 April 2006 (UTC)

According to Dr. Peter Scardino, who is the chairman of urology at New York's Sloan-Kettering Cancer Center, intermittent hormone therapy is intended to balance the benefits of hormonal control along with a reduction in unpleasant side-effects. As the name implies, it involves periods of hormone therapy alternating with periods where the drugs are interrupted. The hormones are resumed when levels of prostate-specific antigen (PSA) begin to rise.

Doctor Scardino seems less than impressed with this method, since the side effects of hormone therapy only begin to abate by the time the drugs must be resumed. Since the drug-free periods tend to shorten over time, the implication is also that interruption allows the cancer to progress more rapidly or even develop resistance to hormones more rapidly. Here's a link to his book: Dr. Peter Scardino's Prostate Book--Mark Bornfeld DDS 16:01, 21 April 2006 (UTC)

Really dumb java question

I can't seem to import correctly in my Main method. My main method is in package a. I have a number of classes in package a.b, including MyObject. When I say

package a;

import a.b.*;


public class Main {

    public static void main(String[] args) {
           
        MyObject o = new MyObject();      
    }
    
}

it says "Cannot find symbol: constructor MyObject() in location a.MyObject.
If I change the import line to

import a.b.MyObject;

it works fine. Note also that importing, say, Java.util.* works fine. I'm using the NeBeans IDE.

I know this is dumb, but I can't work out what's wrong. Any help? --Mary

Sounds like you have a name conflict between packages a and a.b. Perhaps there is a MyObject in each? Or else you moved classes around and have stale .class files. It also sounds like you changed the names for the question; I'd try making a new, clean test with just two classes in new packages, and then gradually make them look more like what you want the real code to be until the problem occurs (at which point the cause should be clearer). (Also, note that computer science questions are now supposed to go on the math desk.) --Tardis 18:12, 20 April 2006 (UTC)

I guess that was it. There were no other .java or .class files in the folder that I could see, but when I performed a 'Clean and Build' in NetBeans it worked. I guess I don't really understand where NetBeans is keeping its class files, but that seemed to solve it. Thanks! --Mary

Backing up DVDs

This may or may not be appropriate for this reference desk, but can anyone recommend a piece of widely available, layman-accessible software that I could use to make a few copies of my DVDs (I'm leaving for college and don't want to risk losing my entire collection). I haven't got any nefarious designs, but I expect it's probably illegal anyway. Any suggestions? Bhumiya (said/done) 17:34, 20 April 2006 (UTC)

Not a lawyer, of course, but as I understand US law (US from your user page), there's nothing illegal about simply copying a DVD for personal use; see fair use. If you decrypt the DVD's contents, you can run afoul of the DMCA, but that's not inherent to copying. The DMCA might also have something to say if you have to "circumvent" (whatever that means) other copy-protection on the disc. I believe that standard DVD burners like, say, Toast for OS X are capable of doing what you want, but I don't have a list of those handy... maybe optical disc authoring software and its links would help? --Tardis 18:30, 20 April 2006 (UTC)

You may want to check out the comprehensive guides on DVD-Backup from Doom9, accessible here. All the software you need can be found in the "downloads" section of the site. --Aramգուտանգ 19:09, 20 April 2006 (UTC)

The problem you will run into is that most commercial DVDs are dual-layer, and so hold more information than the single-layer DVDs that you probably have the equipment to burn. There are ways around this, but they're not perfect and not very simple. Henry^Flower 21:45, 20 April 2006 (UTC)

Impurities

What are the effects of impurities (like Arsenic,Antimoney,Bismuth) Copper. Please explain in detail?

What are the circumstances? Are you asking how these impurities are found in copper or how you would remove those impurities or what are the properties of impure copper metal, etc? --Chris 19:24, 20 April 2006 (UTC)

A/D converters

What are the characteristics of A/D converters in data acuisition?

THANK You

If you type "A/D converter" into the search box up there $\uparrow$, you will be taken to our article about Analog-to-digital converters, which tells you a lot about them. -- AJR | Talk 00:28, 21 April 2006 (UTC)

Allergy

I bought a Hot Tub last year for use in our Scottish Garden. The Tub was made in California by a reputable manufacturer and distributed in Scotland by a highly responsible specialist dealer. My wife and family, as well as several friends, use it regularly and enjoy it immensely. But me? Every time I use it I break out within hours with an incredibly itchy skin, mainly on my back but also on my arms and legs. I have consulted both the manufacturer and distributor and have had great support from them in trying alternatives to the stabilised chlorine granules they normally recommend. These alternatives have included non-chlorine monopersulfate granules. But alas, to no beneficial effect. I religiously clean the filter and monitor the PH, Alkalinity, and Water Hardness and dose them accordingly, and I always shower thoroughly after each Hot Tub. But of all my family and friends, I seem the only one affected. My question is this; Is there a way of treating the water so that I can enjoy the use of the Tub without the adverse side effects described above, or am I consigned for all time coming to be on the outside looking in? The others are quite happy with that latter situation as I make a very good Gin and Tonic for them to enjoy whilst bathing. My Hot Tub suppliers claim not to know of any other similar sufferers in Scotland. Sorry for the length of this whine but thanks in anticipation for any advice.195.93.21.42 18:46, 20 April 2006 (UTC)

Would you like some cheese with that whine? Hehehe. Could you be more specific as to what chemicals you are using to treat the water? There is obviously more than just chlorine that you could be reacting to. It may even be something as crazy as what material the hot tub is made out of. You may also want to consider seeking the advice of a physician, perhaps a dermatologist or allergy specialist. --Chris 19:20, 20 April 2006 (UTC)

I would think that bromide and ozonation would be two alternatives --WhiteDragon 19:41, 20 April 2006 (UTC)

Indeed, I use bromine tablets in my hot tub. Switching over from chlorine to bromine probably would require draining and refilling the tub, however. I believe that with ozonators, it is still necessary to use a sanitizing chemical, albeit in smaller quantities. --LarryMac 19:50, 20 April 2006 (UTC)

You could pay big bucks and convert to a saline spa. These are very mild with almost no irritation. We don't have an article on it, but basically the water is salted to 1/6 of seawater, and an electrolyser produces pure sodium hypochlorite. I've seen them, and they don't produce the halide by-products that are so nasty. --Zeizmic 20:19, 20 April 2006 (UTC)

My opinion is that if the manufacturers do not have any helpful suggestions you are probably out of luck. Talk to your Physician. Maybe you are hypersentitive to something else?

It does seem like an allergic reaction, and it could be quite beneficial to find out what exactly it is. Contacting your physician for an allergy test would be a wise course. If whatever is causing it is in one product, chances are good it's out there in other forms as well. (Basicly they test you for a large number of allergens, i believe by exposing your skin to tiny amounts, see if you have any uncommon response) SanderJK 22:41, 20 April 2006 (UTC)

Are you sensitive to the water temperature (ie. is the water too hot for you)? - Cybergoth 01:52, 21 April 2006 (UTC)

I suggest you dump the old water, carefully rinse the hot tub out, then refill it, but don't add chemicals. Then try it and see if you get the same reaction. This will tell you if it was something in the water causing the problem or perhaps just a reaction to hot water. I've often thought that a distillation process would allow the water to be cleaned without any nasty chemicals. This method would require an exterior tank to keep the distilled water separate from the dirty water, and would require lots of heat, but that wouldn't be so bad if you needed to heat the water anyway. Perhaps a timer could be set to run the distillation process right before you plan to use it. Time to file my patent ! StuRat 07:03, 21 April 2006 (UTC)

I think your skin is reacting to whatever the tub is made of or coated with. As a test, sit in a regular bathtub with the same temperature and add the same chemicals, but don't transfer water from the california hottub. Maybe some sort of coating on your hottub would help. Or a liner? WAS 4.250 10:12, 21 April 2006 (UTC)

Planet Orbits

On diagrams and pictures, all the planets seem to orbit on one level plane (with the exception of Pluto). Is this correct? Why do all the planets roughly orbit the sun on the same plane? I thought the effects of gravity worked on all planes.

Mainly because the accretion disk theory says that the planets form from a flattish blob of matter, rather than a spherical one. Pluto tends to be the odd one out in these things, which is why its status as a proper planet tends to be in dispute. Confusing Manifestation 20:02, 20 April 2006 (UTC)

As an aside, Pluto has lots of other problems too. It's not a gas giant despite the fact that it's on the outer part of the solar system, and it's actually part of the Kuiper Belt, which has many large objects, at least one of which is probably larger than Pluto. There's plenty of more information on those pages and several more I'm sure. EWS23 | (Leave me a message!) 20:13, 20 April 2006 (UTC)

Also take into account the theory of gravity - the planets will pull each other closer. They may have started on a tilted plane, but when they near each other in orbit, they will pull the plane of their orbits closer. Also, there is the spin of the sun. It is most likely not a coincidence that the planets orbit in the same plane that the sun spins. --Kainaw ^(talk) 20:52, 20 April 2006 (UTC)

And the planets all orbit in the same direction the Sun spins (except Pluto) right?

Yes, all planets in our solar system (including Pluto, actually) orbit in the same direction. Most of the planets also rotate in the same direction, but Venus, Uranus, and Pluto all exhibit retrograde rotation. Prograde and retrograde motion is a good read. EWS23 | (Leave me a message!) 00:39, 21 April 2006 (UTC)

If memory serves, Uranus is a weird one in that the direction of rotation is a bit of a guess. The best description of it is that it rolls around the orbit. The axis of rotation point directly toward the sun (or directly away from it - depending on your point of view). Since neither axis points "north", it is not easy to say which way it is rotating. --Kainaw ^(talk) 01:10, 21 April 2006 (UTC)

Well remembered. The page that I linked above says:

Uranus rotates nearly on its side relative to its orbit. It has been described as having an axial tilt of 82° and a negative rotation of −17 hours, or, equivalently, of having an axis tilted at 98° and a positive rotation. Since current speculation is that Uranus started off with a typical prograde orientation and was knocked on its side by a large impact early in its history, it is most commonly described as having the higher axial tilt and positive rotation.

EWS23 | (Leave me a message!) 03:30, 21 April 2006 (UTC)

A couple of other pages of relevance: ecliptic plane and invariable plane. --Bth 23:12, 20 April 2006 (UTC)

Ocean Trenches

I can't find how they are formed. How are they formed? I am in grade school so i don't know how all of this wikipedia works.

Read Oceanic trench and subduction. They might be a little heavy going for you, but try them and then ask again back here if there are things you don't understand.-gadfium 22:53, 20 April 2006 (UTC)

They form when one piece of the Earth ends up going under another through subduction, then there's a crack. -- Mac Davis] ⌇☢ ญƛ. 04:20, 21 April 2006 (UTC)

The hardest part is geting the scale of things to make sense in your mind. The continents (land) and oceans are just a thin film on a very hot slow rolling "boil" that over billions of years causes the thin surface light-in-weight rock to move like some thin film on the surface of water being boiled in a pot. The relative thinness of the surface of the Earth and the vast stretches of time involved in shaping it are hard to come to grips with for many people. WAS 4.250 09:55, 21 April 2006 (UTC)

We need a Wikly-pedia for late grade school to early highschool. I find that many of the science articles are somewhat ridiculously post-graduate. --Zeizmic 13:06, 21 April 2006 (UTC)

Hardly, most are barely under-graduate--152.163.100.74 20:50, 22 April 2006 (UTC)

Yeah...for anything above that, click the links at the bottom of the "heavier" articles :)

April 21

where do baby internet trolls come from?

surely the adult form doesn't find any time to reproduce, so where do the little ones come from?5r75r 00:10, 21 April 2006 (UTC)

The stork leaves them under cots -- AJR | Talk 00:38, 21 April 2006 (UTC)

Trolls are like prions; they twist innocents into their own shape.-gadfium 00:57, 21 April 2006 (UTC)

Funny thing - I was accused of being a troll just a couple days ago because I said Americans can be just as stupid as African "savages". Then, later, I said the United States can be (and has been) just as imperialistic as China. Since I disagree with the accepted notions that Africans are inferior to Americans (especially the white ones) and China's government is pure evil, I suddenly became a newborn troll. Now, I don't know what to do. Should I continue thinking for myself and becoming more and more of a troll - or should I dump my brain in the garbage and start making more palatable posts? --Kainaw ^(talk) 01:18, 21 April 2006 (UTC)

I was the one refuting your absurd accusations that Hawaii is under a military occupation equivalent to that of Tibet by China. However, I never called you a troll, although I do question whether you should be permitted out at night by yourself, LOL. StuRat 06:49, 21 April 2006 (UTC)

I did not intend to imply that you called me a troll. You are a well-respected Reference Desk user. It was an anonymous-coward who called me a troll. Because I feel that nobody else is interested, I will attempt to explain my theory of the Hawaii-Tibet relation on your talk page. Cool? --Kainaw ^(talk) 12:15, 21 April 2006 (UTC)

Must be a spontaneous mutation. - Cybergoth 01:54, 21 April 2006 (UTC)

Or just a dormant trait.  freshgavinΓΛĿЌ  05:04, 21 April 2006 (UTC)

Everyone knows that internet trolls come from under internet bridges. M@$+@ Ju ~ ♠ 22:30, 21 April 2006 (UTC)

help me get into a med school!

I know a lot of the scholarly types visit this place so i was wondering, i want to get into medical school so i can grow up to be rich and famous. the question is, what do you think is the best way top get into a med school? im not very smart. easily confused. and not very motivated. although im sporting a 2.9 gpa in my 5th year as an undergrad so not too shabby. im one of those not very motiveated ppl who neevr fit the cookie cutter nerd mold. and i dont like scinece or biology or math very much. but im a real social out going guy who loves to party and lives off his parents considerable finances so i should have no trouble overcoming my shortcomings. plus i have a convertable bmw and im only 26 years old. not to mention i love to network and have lots of people skillz. could do mad well in the business world but i want to help people. question is. how would my parents money best be spent in helping me get into medical school on my own merit? i dont like tutors mind you their some boring no life book nerd who never get good results anyway. and i do poor on placemnts. question, help me get into med school. also i hate lecturs and lavs bunch of bullshit book learning never got anyone street smarts in medical school--Iwantasportscar 00:18, 21 April 2006 (UTC)

Consider not going to med school unless you can make yourself study for the MCAT. Isopropyl 00:24, 21 April 2006 (UTC)

you think i could hire someone else to take the test for me. i mean the mcat ppl dont really know what i look like anyway how are they going to know who really took the test or not--Iwantasportscar 00:31, 21 April 2006 (UTC)

I agree. No offence, but if you just want to be "rich and famous", try to find a profession in which people don't die if you screw up. If you "dont like scinece or biology or math very much", you probably won't enjoy a medical job anyway. —Keenan Pepper 00:30, 21 April 2006 (UTC)

Also, if you fail your MCAT, you likely will be sued for malpractice multiple times. So, you will never get rich, but you may get famous for your ineptitude. You should consider advice a Norwegian woman told me when I was in Tromsø: Being successful in America is easy. Just go to medical school and be a doctor. If you are too stupid to be a doctor, go to law school and be a lawyer. If you are too stupid to be a lawyer, just be a politician. --Kainaw ^(talk) 01:24, 21 April 2006 (UTC)

I think Iwantasportscar really wants to be a writer, and this question is a little exercise. (See also the previous question.) Clearly you have enough talent to get published on USENET --GangofOne 01:42, 21 April 2006 (UTC)

You could always sell your BMW and buy a hot-dog mobile. You'd be relatively rich (fifty grand in your pocket) and somebody would probably take a picture of you and put you in the paper for being a moron and driving in a hot-dog mobile, thus making you sub-famous for a few days.  freshgavinΓΛĿЌ  05:02, 21 April 2006 (UTC)

I apologize but are you serious about this question? If you are as you describe, going to Med school will NOT make you rich and famous. It doesn’t sound like you really have the passion, desire or discipline required for Med School. You have to love what you do and do it well.

Maybe you could ask a real doctor? "Wow you are the dumbest fucking idiot ever. Instead of your stupid ws.arin.net why don't you try ip2location.com. As for the location in Virginia--that is WHERE VERIZON is headquartered! Put the IP that I used at work into ip2location.com and it comes up LOS ANGELES. You dumb fuck. Speaking of idiots...you are using AOL. And what is your obsession with me? Are you so jealous? Did you aspire to be a doctor but failed? I look forward to you agreeing with me that you are the dumbest fucking idiot ever. I had to say that twice because maybe it didn't get through your thick skull. More about me: I make about 270K per year, and live in a million dollar home. All at the age of 31! :) User:ER MD 10:46, 31 March 2006" (UTC)[13] --GangofOne 19:49, 21 April 2006 (UTC)

Schizoaffective disorder

Do shizoaffectives have cycles of mania and depression like bipolar people do?

There are apparently two types, "bipolar schizoaffective disorder" and "depressive". Why don't you take a look at the schizoaffective disorder article? - Cybergoth 02:48, 21 April 2006 (UTC)

Old people

Why do old (70+) women develop facial hair? I know they've always had facial hair, but some old ladies are about as hairy as pubscent boys. A Clown in the Dark 01:14, 21 April 2006 (UTC)

Lack of estrogen after menopause. Men with estrogen treatment stop growing as much facial hair. --Kainaw ^(talk) 01:20, 21 April 2006 (UTC)

I believe the ratio of testosterone to estrogen controls facial hair growth, among other things. StuRat 06:40, 21 April 2006 (UTC)

Anatomy

Acidosis occurs when arterial blood pH drops below what?

7.35. I recommend you read Acidosis. A Clown in the Dark 01:49, 21 April 2006 (UTC)

Actually, you've got causality a bit mixed up there. Acidemia is when plasma pH is less than 7.35. Acidosis is the underlying disorder that caused the acidemia. --David Iberri (talk) 03:04, 21 April 2006 (UTC)

Anatomy

The predominant extracellular cation is the what?

What is Sodium? - Cybergoth 01:58, 21 April 2006 (UTC) ("I'll take Anatomy for 400, Alex")

Correct goth, Potassium would also be accepted. :P -- Mac Davis] ⌇☢ ญƛ. 04:24, 21 April 2006 (UTC)

I certainly hope Alex would know enough to respond, "No, sorry" to potassium. THe predominant extracellular cation is sodium. The predominant intracellular cation is potassium. That's the whole point of the question! - Nunh-huh 04:32, 21 April 2006 (UTC)

Orca distribution

According to Wikipedia "The orca is the second-most widely distributed mammal in the world, after the human." but surely rats must be a candidate for this title? Thank you

This is due to it huge area that the orca has. The ocean is a big place. Some kind of insect would probably come after, or other kinds of whales. -- Mac Davis] ⌇☢ ญƛ. 04:28, 21 April 2006 (UTC)

Insects aren't mammals.-gadfium 06:39, 21 April 2006 (UTC)

But they are animals. Oh, on the page it says animal. -- Mac Davis] ⌇☢ ญƛ. 11:28, 21 April 2006 (UTC)

Aeration treatment

I want to know about the "aeration treatment" which is extensively used in water treatment systems. If anyone can answer to the following question regarding the aeration systems,it will be a great help for anyone who searching information about that.

1. How does the aeration affect in treating sewage or waste water?

(What will happen to the waste water in the aeration process?)

1. Specifications of the aerators used in various occations?
2. How does it reduce the BOD & COD level of waste waters?

IF anyone can publish an article about this, It would be great..!!! (Sithara from Sri Lanka)

Basically, it gives the microorganisms in the water all the oxygen that they use up while breaking down (oxidising) the wastes. Biological Oxygen Demand is a measure of how much oxygen is used up by organisms as they try to consume the waste, the end result of aeration should be reduction of the BOD as the wastes have been removed. Sewage treatment should answer your questions. Malcolm Farmer 19:27, 21 April 2006 (UTC)

Basic mechanical reference.

Doubtless, you are aware of how mindbogling an array there is of guages, types and other descriptions of basic items like screws and threads and wires sizes and so on. Is there any central location (web or print) that has all of it in an easily cross-referenced format? I plan to make excel files eventually, unless someone has them. Thanks! Feel free to respond directly. (email excluded)

Dunno if there's a counterpart on the web, but as far as print goes, you can buy a copy of the current edition of "Machinery's Handbook". Erik Oberg, Franklin D. Jones, Holbrook L. Horton, and Henry H Ryffel are the authors, the publisher is Industrial Press, Inc., New York. It's 2,640 pages, and the ISBN is (at least for the 26th Edition) 0-8311-2625-6.

A much cheaper version is the "Pocket Reference" booklet written by Thomas J. Glover, and published by Sequoia Publishing, Littleton, CO. ISBN 1-885071-00-0 —The preceding unsigned comment was added by 216.163.128.130 (talk • contribs) 13:50, 21 April 2006.

I have no idea if you care, but there's a biological equivalent: Registry of Standard Biological Parts. Isopropyl 04:53, 21 April 2006 (UTC)

Body decomposition rate

How long does a body in a fancy tomb take to decompose, versus a body buried simply in a casket in the earth? And does the casket affect the rate? Thank you. PatrickJ83 05:12, 21 April 2006 (UTC)

I don't know about the rate, but the casket and surrounding concrete vault will most definitely slow decomposition by keeping water and organisms out. Embalming also greatly retards the decomp rate. StuRat 06:34, 21 April 2006 (UTC)

The decomposition rate is determined by things other than how "fancy" the tomb is: temperature, humidity, acidity, being eaten or not by whatever from bacteria to dogs, method of body preparation. Burial of executed criminals in no casket at all in north european peat bogs was extemely preservative of the bodies. WAS 4.250 09:32, 21 April 2006 (UTC)

Thank you, but do u think it takes, say, 50 years for the soft tissue to decompose in a 'fancy' tomb above ground and maybe 10 years in a coffin in the Earth? This is under normal circumstances, no preserative beat bogs or anything. Without embalming. Thanks PatrickJ83 17:43, 21 April 2006 (UTC)

It depends. Louisiana or Montana or Nevada? Humdity and temperature matter. How safe from flys and worms. Buried in clay could be safe from worms, above ground could be fly food. How decomposed is "decomposed"? I recommend you take a piece of meat and put it somewhere and look at every day or so. Maybe even write down your observations. Maybe even have a few pieces of meat; one outside, one in the dark, one in the light... WAS 4.250 18:14, 21 April 2006 (UTC)

Would a piece of meat really be a good experiment to contrast with a human body? I would have to bury the piece in a coffin in the ground and then bury another piece of meat in a marble tomb, HA! Anyway I digress. The reason I asked this question in the first place is because I was reading in a magazine about a newish trend of people buying above-ground tombs for themselves instead of being buried in the ground as they think it's more noble. But does this slow down decomposition rate? Would a body buried in a marble tomb in a church take, say, 100 years to decompose to skeletal remains? That's really what my question boils down to. Thanks you guys! PatrickJ83 21:34, 21 April 2006 (UTC)

Why does some chewing gum disintegrate in your mouth?

Example: Altoids Sour Apple Chewing Gun disintegrates in your mouth after chewing it for 5 - 15 mins.

Description of phenomenon: The Gum looses all flavor and it begins to get really soft as you chew it...the texture and the elasticity is gone. It them becomes like a glob of paste and disintegrate in your mouth.

Possible answer found on on HighBeam Research but did not have full access to read the article (Chemistry and Industry, May 2, 2005): "Chewing gum can be a disappointing experience of short-lived flavour or grainy texture, largely due to the method of manufacture. There are two basic processes: the first is to mechanically mix gum base compounds/polymers. This tends to produce a nice texture, but can destroy encapsulated flavours, The second method is to compress discrete gum base particles, a process that is gentler on the additives but can result in gum that disintegrates too easily on chewing."

Question: Can some elaborate or confirm if the explanation is true?

I like that stuff! I think its because there are almost no purposeful elasticity agents in the gum. Its not really gum, its just sugary soury stuff that is like a chewy sweet tart. Most gums have stuff like chicle or plastic-like substances to make them elastic, for the pleasing feeling for the chewer. Sort of how people love chocolate for one reason that it melts just under your mouth's temperature. Mmmmm. -- Mac Davis] ⌇☢ ญƛ. 11:33, 21 April 2006 (UTC)

Not exactly your question, but certainly related: http://www.straightdope.com/classics/a2_201.html —Keenan Pepper 14:53, 21 April 2006 (UTC)

Fantastic. Now we can work on that other important question, "Does your chewing gum lose its flavor (on the bed-post overnight)?" Confusing Manifestation 12:34, 22 April 2006 (UTC)

Speed of Heat through Space

My question is .." Does heat travel through space at the same speed as Light (close to 300,000 Kilometers per second)?" if it does can I have a reason Thanks Tony Stevenson

Someone else will no doubt have better information on this than me, but ISTR that both heat and light are radiant energy by-products of electromagnetic radiation and therefore travel through vacuum at the same rate. Grutness...wha? 09:17, 21 April 2006 (UTC)

Heat in the form of thermal radiation and all light is EM radiation, not a byproduct. But note that heat can take many different forms, not all of which are radiative. Light on the other hand is, well, light, and is always radiative. However, in a vacuum the only transfer of heat is via photons, so yes, through space heat and light are identical in almost every respect (aside from visibility to humans and a reasonable difference in energy per photon). --Tardis 18:23, 21 April 2006 (UTC)

Thanks for the answer, I still don't understand why the heat from the sun in the morning takes a while to heat the earth.. if an atomic bomb was to be let off in space would a spaceman say 600,000 kilometers away be burnt to a cinder in 2 seconds? surely he would see the light before being burnt?

The time taken to heat up in the morning is nothing to do with the speed of the heat. After all, the heat already left the sun, and has arrived by dawn. The time taken is because there is only so much heat available, and because there is an awful lot to heat up. Notinasnaid 10:15, 21 April 2006 (UTC)

Assuming the spaceman is not hindered by anatomical difficulties that regulates the speed of which he observes, but instead acts like a neutral, single-photon sensitive sensor, an answer can be given that hopefully isn't very bad. The explosion takes place, and photons will be emitted spherically. Now, after two seconds, ONE photon is destined to arrive at the spaceman before the others, or along with a couple of others. He will detect this photon. Within very little time, other photons will also arrive. Remember that photons will one by one clash into the spaceman, and heat him up until being burnt dead (assuming that is the effect of a nuclear bomb at 600,000 km). The answer to the question is then that yes, he will detect light before being burnt. However, another answer, equally true, says that AS HE DETECTS the first photon, a part of him, even if only an electron or something, will be affected ("burnt"). If you like, he is burnt, but on a very, very small level, because as soon as a photon hits him, energy is transferred, and heat is created on a very, very tiny level. The difference between this and actually having the hole man burn up, is just a matter of how many photons are needed to clash into all of him. Likewise, your earth is heated up as soon as a photon hits, but the more photons arrive over a longer duration, the more heat it gets. 213.161.190.228 10:34, 21 April 2006 (UTC) Henning

Just to give a sense of scale, any normal nuke at that range will have little to no effect; that distance is nearly one hundred Earth radii. A human (taken to have a ridiculously large presented surface area of 2 square meters) will intercept approximately 4 mJ of radiation of various kinds from a multi-megaton explosion at a range of $6\times 10^{8}{\mbox{ m}}$. This energy, if evenly distributed, will raise the person's temperature by some 15 nK -- entirely insignificant. There might still be some concerns from, say, gamma irradiation damage, especially since there's very little material present to convert the initial reaction radiation into lower-energy forms (like molecular motion or thermal photons), but I suspect that a man on the Moon would be quite safe from all effects of nuclear explosion taking place very nearly on the opposite side of the Moon's orbit (but in line-of-sight; not talking about Earth as a shield here). --Tardis 18:23, 21 April 2006 (UTC)

It is a good answer but not the one I wanted to read... so I lose the bet.. Thanks again Tony

Heat can be transmitted in two ways: One is convection/conduction, where the heat is transmitted in the form of the motion of atoms and molecules. In that case the theoretically fastest speed it could move at would be the speed of sound in that medium, although it's usually much slower. The second way (and the way the heat of the sun gets here) is through infrared radiation (which, when absorbed by molecules turns into kinetic energy), in that case the heat moves at the speed of light. As for why it takes a while to heat up the earth, that's the same answer as for why it takes a while to heat up a pot on a stove. Note that in the morning/evening, the light is coming in at an angle, and there's less incident light, and more of it is getting absorbed by the atmosphere and not making it down to ground-level. Which is also why we have seasons and why it's colder near the poles. --BluePlatypus 12:14, 21 April 2006 (UTC)

We're dealing with separate phenomena here. The reason that it takes a while for the Earth to warm up is because of its specific heat. The way that heat is transferred to the Earth by the Sun is not by direct conduction (as there is very little matter in between) but by electromagnetic radiation. The amount of energy delivered is inversely proportional to the wavelength of the light. Tying this to the atomic bomb thing, the reason you don't die when you're so far away from the bomb is because intensity decreases with the square of the radius; doubling the distance cuts the intensity to a quarter. Also, bombs propogate shock waves as fast as possible through their surrounding media, approximately the speed of sound. Isopropyl 13:58, 21 April 2006 (UTC)

...But note in case of confusion that shock waves exist only when dealing with matter: A bomb in space would produce no shock wave. — Asbestos | Talk (RFC) 20:19, 21 April 2006 (UTC)

In a pure vacuum, heat would radiate at the speed of light, and there would be no convection or conduction of heat. Space, however, isn't quite a pure vacuum, so, while most heat would radiate at the speed of light (as infrared radiation), some would be absorbed by matter in space, and later radiated back. So, there would be some lagging heat which could arrive considerable later. I'm not sure if the amount of lagging heat would be significant or not. StuRat 22:08, 21 April 2006 (UTC)

palaeanthropus palestiensis

My Harpers Bible Dictionary refers to eight giant human skeletons from around 100,000 years ago being found in a cave on Mt Carmel and calls them Palaeanthropus Palestinensis. I am unable to find any further info on them, could someone direct me onwards. Thamks Hatch

Never heard of it before, but some research suggests that "Palaeanthropus" is considered a simple synonym of "homo sapiens". http://www.jewishvirtuallibrary.org/jsource/Archaeology/carmel.html talks about the caves of Carmel. The cave may well be "Skhul". http://www.archaeologyinfo.com/homosapiens.htm talks a lot about it, but doesn't talk of giants: "the site is an extremely important one" "The site has been dated from 120 kyr up to 40 kyr by various methods" "This led to the false impression of large cranial capacity". Notinasnaid 10:28, 21 April 2006 (UTC)

It was made up, there never were any race or species of "giant" humans. -- Mac Davis] ⌇☢ ญƛ. 12:23, 21 April 2006 (UTC)

Start here: Mount Carmel, Israel and here WAS 4.250 12:39, 21 April 2006 (UTC)

How do I obtain a list of the richest person in Microsoft Access?

Let's say I have a database of people on earth that has following data fields:

• Continent: Asia, N America, ...
• Country: Australia, ..., Zaire, ...
• Province or State: ...
• City: ...
• Name: ...
• Net worth: ...

I want to know who is the richest person in each country's each province. And I also want to know where can I find him/her (which city). I think I can create a query like this:

Continent	Country	Province	City	Name	Net worth
Group by	Group by	Group by	do nothing	do nothing	Max

However, in Microsoft Access, you can only do:

Continent	Country	Province	City	Name	Net worth
Group by	Group by	Group by	Group by	Group by	Max

It results in a very long list also grouped by cities and names. I end up to have a list of the richest Johns, Marys, Toms, ... in each seaside little town. Can I fix it with some SQL commands? -- Toytoy 13:04, 21 April 2006 (UTC)

yea you can and i could help you with the commands. im just a little confused about exactly what you want, could you elaborate a little bit- like what tables you already have and what the different fields are. --modesty 17:04, 21 April 2006 (UTC)

I would switch to SQL mode in the query window and cut those extra 'group by' statements, that's what's throwing it off. Access usually accepts hand made SQL as well as anything.

One way you could do this is: (you seem to have some Access knowledge, so I'm skipping all the little details of building queries, linking and so on - let me know, and I'll add them in)

• First run a query, with Continent, Country and Province set to Group by, and Net Worth to Max. Don't include the City or Name fields at all. Save the query, I'll call it Max_Worth, which gives you the maximum net worth in every province -- with no name or city information.
• Second, start a new query. Add the base table, plus the Max_Worth query. Link the Continent, Country and Province fields from the base table and the Max_Worth query. Next, link the Net Worth field from the base table with the last field in the query; it'll be called something like MaxOfNetWorth. Add all the fields in the base table to the query; have all of them set to Group By.

That should give you a list of every field that matches the maximum net worth for their particular province, with all of the information you need. --ByeByeBaby 03:29, 22 April 2006 (UTC)

Could a planet succesfully orbit a black hole?

My understanding of black holes is that they are essentially stars that have mass so great that light/matter can't escape it's gravity. So essentially they work like vacuum cleaners sucking up anything that crosses within their gravitational threshold. Presumably this also would mean that their mass would continue to grow as would their gravitational attraction as they "hoover up stuff". All that said, could a planet (or planets) orbit a black hole safely as our planets orbit the Sun? Or would they gradually be pulled towards the black hole and consumed because of it's ever increasing mass?

I would imagine that the process of a star becoming a black hole would no doubt destroy any orbitting planets of the star, but even so I'm still curious in the hypothetical case. Thanks in advance. Gallaghp 15:21, 21 April 2006 (GMT)

By the divergence theorem, a spherically symmetric object of a given mass has the same external gravitational field regardless of its radius. If the Sun were replaced by a black hole with the same mass, all the planets would continue to orbit the same way. —Keenan Pepper 14:50, 21 April 2006 (UTC)

Yeah, that's the common but somewhat incorrect perception. Black holes aren't vacuum cleaners, their gravity works just like that of any other stellar body up until the Schwarzschild radius. That radius is much smaller than the average planetary orbit, so any object could orbit a black hole just as easily as any other stellar object. The thing about a black hole (but not limited to them) is that most of them probably have an accretion disc with matter that's been drawn into orbit. In that disc they'll bump into eachother and the energy loss to friction will lead to them falling in eventually. But the rules for orbiting a black hole are the same for any other object. (Except for within the Schwartzchild radius). --BluePlatypus 14:53, 21 April 2006 (UTC)

Actually, Gallaghp's question seems perfectly rational to me. I'm not sure that the two answers above me noticed that the question was asking whether a black hole's mass (and thus the Schwarzschild radius) continues to increase, which would thus endanger any orbiting planet. In the general sense, I would assume that the answer is 'yes, the mass will continue to increase and so...'. However, if, say, the Earth were to turn into a black hole, its mass would increase no faster than if it just stayed being the earth (with random meteorites adding to its mass). In fact, it would probably increase in mass slower, as the Schwarzschild radius would be inside the original radius of the earth (so some debris which would have hit the Earth would miss the black hole). — Asbestos | Talk (RFC) 20:15, 21 April 2006 (UTC)

In order to form a traditional astronomical black hole, it would have to be super-massive, which means it would have a much larger gravity well than a typical star and pull in passing objects from much farther away. However, I can imagine a period after which all nearby matter had been pulled in, and the black hole could then capture a passing planet (not sure why a planet would be just flying around the universe, but let's ignore that for now). This would be quite difficult to detect, since not only would there be no light given off, but the gamma ray jets associated with the accretion disk would also be absent. A gravitational lens effect could still be detected, however, on objects behind the black hole from our POV. StuRat 21:39, 21 April 2006 (UTC)

Actually I'm pretty sure that the capture of a planet by a black hole would release an enormous amount of energy. Some of it would be released as light when the planet was destroyed, outside the event horizon, by the tidal forces; that should heat up the matter to the point that it would give off quite a lot of light, unless the black hole were truly huge. Given a black hole so large that a planet could slip past the event horizon without being vaporized first (anyone care to figure out how big that would be?) I would still expect a massive energy release, but it might be in the form of gravititational waves, which are pretty hard to detect. --Trovatore 22:18, 21 April 2006 (UTC)

I don't think you are taking "capture" to mean the same thing I meant. I meant the planet would orbit in a stable manner, perhaps at a rather extreme distance, like billions, or even trillions, of miles. StuRat 01:01, 22 April 2006 (UTC)

Oh, I see. Sure, I don't see any reason that couldn't happen. Of course some of the planet's energy has to be dissipated the first time it approaches, or it'll just fly off again, but I suppose there are ways that could happen. --Trovatore 01:15, 22 April 2006 (UTC)

As I understand it, a light object on a nonintercepting course with another far more massive object, in space, will do one of the following things:

• If the speed of the light object is much less than the orbital speed at that distance, the light object will spiral inward and eventually collide with the massive object.

• If the speed of the light object is somewhat less than the orbital speed at that distance, the light object will spiral inward toward the massive object until the speed is sufficient for a stable orbit, and the light object will then enter that stable orbit.

• If the speed of the light object is exactly the orbital speed at that distance, the light object will immediately fall into a stable orbit. This, however, is extremely unlikely.

• If the speed of the light object is slightly more than the orbital speed at that distance, the light object will spiral outward until the speed is sufficient for a stable orbit, and the light object will then enter that stable orbit.

• If the speed of the light object is much more than the orbital speed at that distance, the light object will slingshot around the massive object in a parabolic path and then continue on it's way. In an extreme example, the deflection is so slight that the path of the light object appears to be a straight line.

So, 3 or the 5 cases would result in a stable orbit, eventually, again assuming there is no accretion disk in the way of all this happening. StuRat 01:39, 22 April 2006 (UTC)

No, in the simple case (no energy transfer), there is no "spiraling". The light object coming "from infinity", or more to the point having a speed at least equal to the escape velocity, will trace out a hyperbolic (or parabolic) orbit past the heavy object, and escape to infinity, unless the perigee of that orbit is smaller than the radius of the heavy object, in which case it will crash.

To get any other pattern, energy somehow has to be transferred between the two objects, or between the light object and other bodies in the system (moons, accretion disk, etc). I think this might be a plausible mechanism for energy transfer between the planet and the black hole: Tidal forces could act on the planet, changing its spin and therefore its angular momentum, and the angular momentum of the hole would have to change to balance the books, with a concomitant change in its rotational kinetic energy. But the precise calculations would get into general relativity and are quite beyond me. --Trovatore 01:53, 22 April 2006 (UTC)

Vacuum Extraction

Hello, I've heard of a procedure I'd like to find out more about, apparently Vacuum Extraction is "a new method of non intrusive exploratory digging without the risks associated with normal digging. In the USA legislation has been passed preventing mechanical digging due to costs associated with litigation following damage caused to underground pipes and cables. The method of exploration starts with high pressure water making a hole of up to 8 cms and a vacum system that draws out the debris The cable avoidance ground radar identifies hazards before damage occurs. The waste is held in a tank to be used as back fill or disposed of at water treatment plants if necessary." All I've been able to find on google under Vacuum Extraction relates to a medical procedure used in childbirth so I wonder if this is known by another name. Can anyone help me find out more about this method of digging? Thanks. AllanHainey 14:33, 21 April 2006 (UTC)

Vacuum excavation? It seems to give a lot of hits. --BluePlatypus 14:45, 21 April 2006 (UTC)

This method sounds like it would have some limitations, especially when dealing with underground water. Only 32 feet/10 meters of water can be supported by a pure vacuum, so a hole with water at more than that depth (or any depth of water continuously leaching in from the sides faster than the vacuum can remove it) would be an impassable obstacle. As a practical matter, the pump impeller would cavitate and fail at far shallower depths. A traditional drill would have no trouble with the water, and could actually benefit from the cooling. I would also think sharp chunks of quartz and such would damage the vacuum, or at least wear it out quickly. StuRat 21:06, 21 April 2006 (UTC)

We call this 'daylighting' over in the boonies of Ontario. It's only for shallow excavations around existing pipes and such. There is no reason to go deep. --Zeizmic 23:56, 21 April 2006 (UTC)

You don't necessarily have to suck from the surface. You could always pump compressed air or liquid down to push the dirt out. Alternately, you could build the pump into the drill head, and again push from the bottom rather than pulling from the top. Of course, as Zeizmic says, this technique is really only used or likely to be useful for shallow work. If you're going to go deeper than pipes or cables are buried, then you can switch to conventional drilling equipment once you've got the first few meters of hole opened up. TenOfAllTrades(talk) 03:24, 22 April 2006 (UTC)

Martial Arts feats

I have seen buddist monks, martial artists, and other assorted people stand on very sharp things (i.e. a sharp edge of a katana) and not be cut by them. Similarly, I have seen people stand on a single sheet of rice paper without breaking it.

Is it some kind of trick, or are they really able to do it? Is they are, how? I'm not into 'Ki' or 'Qui' or whatever the popular word is for it now; I would prefer a scientific explanation above all else.

Thanks! 68.52.56.111 15:30, 21 April 2006 (UTC)

Hmm, I know it's possible to support your weight on a lot of sharp things together, like a bed of nails, but not a single sharp thing by itself. Were they standing on a whole bunch of katana, or just one? Also, if a sheet of rice paper is curved just the right way, it might spread the forces out and support the weight of a person. By the way, it's spelled qi in pinyin. —Keenan Pepper 15:40, 21 April 2006 (UTC)

Similar to this monk. Unfortunately, I can't answer your question. Thank me for being useless. --Chris 16:48, 21 April 2006 (UTC)

I was actually present when a guy (martial artist, cannot attest to the style though) stood with his feet on two katanas. How do I explain this...eh...he stood where the two blades of the katanas were both hitting his feet, as if he were standing on two telephone wires that were next to (parallel to) each other. So I guess the force could have been spread out along both of the katanas. I cannot verify the sharpness of the katanas to you, but he had what I assumed was a Aikido, Iaido, or Kenjutsu (or the like) practioner do a tameshigiri on some rolled up bamboo poles with both of them before he stood on them. Maybe that's the secret to it - he had something in the mats to secretly blunt the swords. However, if the guy was on the up and up, I would like to know how he did it. Thanks. 68.52.56.111 18:45, 21 April 2006 (UTC)

Some thoughts:

• The bamboo was probably struck at high speed with the swords, while his feet were only slowly placed on them. Thus, a much greater force was applied to the bamboo. Perhaps, even impact force was applied to the bamboo by the high speed.

• The bamboo might have also been considerably softer than it appeared, say if it had been soaked in something to make it pliable and/or cut most of the way through.

• He may have had thick callouses on his feet, making them much tougher than they appeared.

StuRat 20:50, 21 April 2006 (UTC)

Seperating Chemicals

I noticed that in my first aid kit there are electolyte tablets that have 220 mg of NaCl, 15mg of KCl, and 18mg of CaCO2. Just out of curiosity, how would I got about seperating these 3, especially the NaCl from the KCl? --Chris 16:48, 21 April 2006 (UTC)

The CaCO₂ is easy. Just dissolve the tablet in water and it will precipitate out, especially if the pH is raised. Separating Na⁺ from K⁺ is much harder. Chromatography and ion exchange come to mind... —Keenan Pepper 17:10, 21 April 2006 (UTC)

[This http://www.corrosion-doctors.org/Biographies/DavyBio.htm] is interesting. It indicates that Humphry Davy developed a method back around the beginning of the 19th century to separate potassium from sodium. It used the fact that sodium perchlorate is soluble in 97% ethanol whereas potassium perchlorate is not. (You're going to need perchloric acid, ethanol, and patience....)

A technique used commmercially is called recrystallization. Again, it relies on manipulating the relative solubilities of the potassium and sodium salts. Starting with a room-temperature saturated solution of sodium and potassium chlorides, add your mixture of salts and heat to high temperature; mix until no more powder dissolves. The solubility of NaCl in water is very nearly constant regardless of temperature, whereas the solubility of KCl increases substantially when the water is heated. Consequently, adding your powder to the hot solution will dissolve KCl and leave powder enriched in NaCl.

Step two is to filter this solution to collect your NaCl-enriched powder from the hot solution. Step three is to cool the solution back to room temperature. The excess dissolved KCl will precipitate; you can collect it by filtration. TenOfAllTrades(talk) 03:18, 22 April 2006 (UTC)

I assume it's CaCO3 that's meant? --BluePlatypus 17:27, 21 April 2006 (UTC)

Hmm, right, wonder why I didn't notice that. CO₂²⁻ would be the impossible ion carbonite. —Keenan Pepper 17:36, 21 April 2006 (UTC)

Yes, CO₂²⁻. Carbonate... sorry. --Chris 21:10, 21 April 2006 (UTC)

History of psychiatry

Hello, I've been wondering about one specific topic : the evolution of the concept of late schizophrenia. European nosology (early 20th) used a specific concept : "psychose hallucinatoire chronique" (PHC) that is still widely used in France for instance. Modern nosology only uses the concept of late schyzophrenia...so here are my questions :

• is late schyzophreia an accurate replacement concept for PHC ?
• how to explain that despite the DSM-4 and CIM-10, that specific concept of PHC is still used ?

So if you guys have any link / reference article / answer / suggestion... it would be greatly appreciated !

Alkaline seafood dishes

Is lutefisk the only alkaline seafood dish? I remember reading somewhere that most cultures developed acidic seafood dishes (e.g. Western fish with lemon, Japanese sushi with vinegar...) because that converts the amines like cadaverine and putrescine into their ammonium salt forms and thereby reduces the rotten fish smell. How come the Scandinavians didn't catch on to this? —Keenan Pepper 17:18, 21 April 2006 (UTC)

Perhaps not the only, but probably the most alkaline. :) Lutefisk isn't rotten and doesn't smell much though, that's Surströmming. They do eat acidic fish too, in the form of pickled herring. Between the salting, smoking, drying, drying-with-lye, pickling and fermenting.. I think they pretty much used up every form of preservation available to them. My guess is that if they had had vinegar, they would've pickled the herring instead of fermenting it. --BluePlatypus 17:42, 21 April 2006 (UTC)

Seahorses!

Hi. I am doing a project on seahorses in my marine biology class. I was wondering what the digestive, skeletal, and circulatory systems were for seahorses. Can someone help me out? Thanks for your time!

I hate to sound so much like the others...but try searching for 'Seahorses' on Wikipedia, perhaps?

-I already did, but it didn't say anything about the systems...thanks anyway.

Try this Google search --LarryMac 19:35, 21 April 2006 (UTC)

18 months back I visited a seahorse farm in Port Lincoln, South Australia, and afterwards did some of my own research on the syngnathidae. The folks at syngnathid.org were really helpful (so I now know sea horses have only one “kidney”, without glomeruli, on the right side – wow!). The site is dedicated to info about these creatures, mainly related to their breeding in captivity, with the aim of conserving wild populations. Collectively they have thorough knowledge of the sea horses' normal and pathological structure and function. Try asking on that site; people who are fanatic about conservation (in a good and necessary sense) are usually good for asking questions of, since their main weapon is education. --Seejyb 20:42, 21 April 2006 (UTC)

Lucid Dreaming

Is it possible to induce lucid dreaming with a tape recording that says "YOU ARE DREAMING" over and over?

Sounds like an experiment! Melchoir 21:21, 21 April 2006 (UTC)

It would work for me, I know in light sleep, I can hear what is going on while I am sleeping at times. Good experiemnt. See if the Lucidity Institute has done it before. -- Mac Davis] ⌇☢ ญƛ. 03:24, 22 April 2006 (UTC)

I would think something like a taped conversation or animal sounds would be more likely to start a dream. Physical sensations also seem able to cause a dream, like a bandage (or "plaster", for the Brits) once made me dream I had a leach on my arm. StuRat 04:55, 22 April 2006 (UTC)

The point is not to start a dream, but to start a lucid dream (which the OP helpfully linked above). Melchoir, as I recall, this isn;t so good, as your brain will eventually tune out the sounds of the tape if its keeps hearing the same thing. People who use tapes usually try to time the voices to come on when they expect to be in REM sleep, somewhere around 90 minutes after you fall asleep. If you look online, you'll find all the common methods (looking and your hands and stuff) that are pretty tried-and-true. — Asbestos | Talk (RFC) 23:05, 22 April 2006 (UTC)

Government Suppression

Is there any eveidence besides reviewing endless lists of patents, to understand, or gain information about, how the government exercises an ability to suppress technological innovations, certain inventions, or scientific data to control the public more than it should. I'm not trying to be some conspiracy theorist, but I have already found astonishing evidence about things I can barely believe in relation to the vagueness listed above. Anyone can go and read some writing about or by tom bearden to see a little bit of what i mean. I can understand the implications of monopolies blah blah and all that. but when something has the potential to beifit all of mankind in profound ways then why else does this seeming oppression prevail?

and does anyone know what this means: e=±((square root symbol) since i couldn't find it)α(multiplied by something that looks like an h with the stem(top part)crossed through with a small line)finally multiplied next by c (the speed of light of course) lastly maybe someone can give me a vague explanation of non-linear optic effect

Retrieved from "http://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Miscellaneous"

This has been taken up over at Misc. --Zeizmic 23:48, 21 April 2006 (UTC)

Absolute pitch

I _need_ an absolute pitch. It can be developped. Has anyone got any idea about how to/the best way to attain this target? Thanks. —The preceding unsigned comment was added by 85.50.33.189 (talk • contribs) 21:53, 21 April 2006 (UTC)

You're one up on me if you have information that absolute pitch can be learned; I always thought you pretty much have it or you don't. Certainly, you can learn some tricks for approximating absolute pitch (for example, learning how particular notes feel in your throat), but I don't think that's quite the same thing.

Absolute pitch is a mixed blessing for a singer anyway; good relative pitch is much more useful IMO. Absolute pitch can be a particular handicap to an ensemble singer, as it can make it difficult for him to match pitch with the rest of the group. --Trovatore 22:33, 21 April 2006 (UTC)

Holy cow batman! We actually have an article on Absolute pitch! --Zeizmic 23:52, 21 April 2006 (UTC)

It is entirely possible to learn absolute pitch. The problem is that it is generally considered impossible after the age of Five. This is not true for all people, but is a good standard to go by. Unless you are asking on behalf of your child or a younger person who falls into the "under age Five" category, I would assume that you are over such age, and not in that category, so it may be impossible for absolute pitch to be attained. yaninass2 04:55, 22 April 2006 (UTC)

It's not as difficult as you think. For me, I can always sing a C to myself, without reference. Using that alone, I can simply relatively pitch other notes. It's not like you need to be able to recognise every note. I think I read about studies which showed that if people listened to a particular song many, many times, then whenever they sung the song to themselves, they would sing it in the correct key, without reference. However, that was only after a lot of listens. So I'm pretty sure it can be learnt through intense practice. As far as I can remember, that's how I seemed to develop it. -- Daverocks (talk) 05:27, 22 April 2006 (UTC)

April 22

Cannabis cultivation

I have recently become interested in botany and I was wondering - in regards of the cannabis plant - how do I distinguish the female from the male? Regards, Gardar Rurak 02:13, 22 April 2006 (UTC)

Erowid should have all the answers you need on their Cannabis cultivation page, specifically these two illustrated articles linked from it. Also, you may be interested in our Cannabis (drug) cultivation article. --Aramգուտանգ 02:59, 22 April 2006 (UTC)

• And just why do you want to know? A Clown in the Dark 03:05, 22 April 2006 (UTC)

Perhaps he's investigating traditional methods of making hemp rope, and wants to make sure there's no THC in the final product, so he needs to know which ones are female so he can discard them :) Remember, assume good faith. --Aramգուտանգ 03:23, 22 April 2006 (UTC)

Yes - I'm starting a hemp shop selling hemp-tshirts and hemp-slippers and I need to sort out the products of the evil one. Thanks or the reply, it's very informative. Gardar Rurak 03:45, 22 April 2006 (UTC)

Yes, and I'm sure you will burn the evil ones. Of course, to ensure proper fire safety, you will need to burn them in small quantities. These small quantities should be in wrapping papers to properly contain the fire, and you will need to pull air over the marijuana by inhaling at one end of each unit for proper combustion. Your devotion to fire safety is admirable ! StuRat 04:45, 22 April 2006 (UTC)

If he really wants to make hemp rope, he should read the hemp article. The proper way to make hemp would be to cultivate the right variety and to use the right part of the plants. this would ensure the final product contains no THC far better then using only males plants (not to mention he won't be very successful if he discards all female plants since he will need to grow more plants which he can't do if he destroys one sex). However it is common practice to remove male plants to increase the amount of THC. If he wishes to do so I really couldn't give a damn but he should be honest or at least not lie about his intentions. If he does wish to lie, and you wish to help him, at least come up with a more plausible lie that actually makes sense. Nil Einne 05:22, 22 April 2006 (UTC)

If you're worrying about male and female plants, maybe you've already been around cannabis too long. Peter Grey 04:52, 22 April 2006 (UTC)

Take it easy... I got an answer to my question and everything was all dandy. Look, I live in a society where it is legal and acceptable to grow these plants for personal use so I see no reason why I should lie about it which was indeed never my intention. I realize sarcasm is not easily communicated through text and may not be as prevalent in other cultures as a form of humour - that is regrettable and for this I do apologize. I have previously made my own beer, wine and alcohol - now I want to try this - it does not mean that I am an alcoholic or a pothead - in fact I rarely even drink coffee much less alcohol or pot. Still, as a hobby it's a lot more interesting than sitting on your ass watching sitcoms or collecting stamps all day. You can judge me all you want - that's your business. Gardar Rurak 06:45, 22 April 2006 (UTC)

Since you are out of the Nasty States, you can grow small amounts for personal use (or you have a medical permit). I had fun with that for a while. There are lots of seed shops. Get the best hybrid you can afford. Put the seeds in little peat seed cups to start. Lighting is the toughest thing to get right. You also have to go through 2 generations to get a good crop, by eliminating the males, and taking cuttings from the females. I don't smoke, and followed the recipes for heating in olive oil, but shortly I started reacting with migraines, and gave it up. --Zeizmic 12:51, 22 April 2006 (UTC)

Price of medicines

I noticed this in the U.S.-Australia Free Trade Agreement#Pharmaceutical Benefits Scheme 2 article:

The scheme involves subsidy of the price of certain "listed drugs", with the result that consumer prices for many common medications are a great deal cheaper than elsewhere in the world.

It sounds to me like this claim is most definitely wrong. AFAIK, while the price of these common medications are cheaper then in the US and in other countries without subsidy schemes, the prices are comparable (definitely not a great deal cheaper) then the prices in other countries with similar agencies that subsidy and negoiate for cheaper drugs, e.g. NZ, UK etc. Can anyone confirm this? Nil Einne 05:01, 22 April 2006 (UTC)

Stars on the southern cross - why do some have 7 points and one has 5 points?

I have been researching the stars of the southern cross, and was wondering why,when you draw these stars on things such as the Australian flag, are the four main stars (Alpha crucis, Beta crucis, Gamma crucis, Delta crucis) represented as 7 pointed stars, and the smaller (epsilon crucis) is represented as a 5 pointed star?? I am guessing it has something to do with double stars and red dwarfs, but I was wondering if there are conventions for this and where I can find info about the rules when drawing a star? Thanks for your help!!

I would guess it's just a way to differentiate between the brighter and dimmer stars. StuRat 08:30, 22 April 2006 (UTC)

The seven points on the stars on the Australian flag represent the number of states and territories present at Federation (six states, and one point representing all territories). I'm not sure what the 5-point star is meant to represent, and I'm not aware of any specific conventions for drawing stars. Our article on Flag of Australia has a lot of information you might find useful. -- Daverocks (talk) 08:35, 22 April 2006 (UTC)

The 6 states and the territories are represented by the 7-pointed large Federation Star (or Commonwealth Star) beneath the Union Jack, not by the stars in the Southern Cross itself. To quote the article:

• "The number of points on the stars of the Southern Cross on today's Australian flag differs from the original design in that the stars varied between five and nine, reflecting the relative brightness of each in the night sky. The British Admiralty, to increase ease of manufacture, standardised the Southern Cross by giving the four biggest stars seven points and five for the faintest Epsilon Crucis. The Commonwealth Star originally had only 6 points, representing the six federating colonies. However, this changed in 1908 when a seventh point was added to symbolise the Territory of Papua." JackofOz 09:03, 22 April 2006 (UTC)

All a bit silly really. As everyone knows, the main four stars only hav five points each (and you can ignore the fifth one :). As far as the Aussie flag is concerned though, as Jack (there's an ironic name, considering the topic) points out, the points represent the states and territories. Originally Alpha Crucis was given nine points, Beta eight, and so on down to epsilon with five. When the flag was altered in 1908, the four larger stars had the number standardised to seven. The number of points on the smallest star remained at five, possibly for ease of manufacture rather than any more esoteric reason. You might also like to check out the Flags of the world website, which has considerably more information. BTW, Australia is not the only country which has an unusual number of points on its stars for the purposes of representing subnational regions. Malaysia and the Marshall Islands are two others which spring to mind which also do this. Grutness...wha? 10:27, 22 April 2006 (UTC)

Grutness, I hate to disabuse my trans-Tasman cousins, but you seem to have somewhat confused the New Zealand flag and the Australian flag.

• The NZ flag has four stars in the shape of the Southern Cross. All four stars have 5 points.
• The Aussie flag has six stars. The smallest star Epsilon crucis has 5 points, and all of the remaining stars have 7 points.
• The Aussie Southern Cross comprises 5 stars: four of 7 points and Epsilon crucis.
• There is a separate Commonwealth Star that appears beneath the Union Jack (I could almost call it the Union JackofOz)
• The stars in the SC do not represent anything other than themselves.
• The only star on the flag that represents the states and territories is the Commonwealth Star. JackofOz 03:00, 23 April 2006 (UTC)

work, energy and power

How much is the power required to raise 300 liters of water per minute through a height of 6 m using a pipe of diameter 2.4 cm if acceleration due to gravity is 10m/s*s ?

Per guidelines that are up at the top of the page, we don't answer homework questions here. Otherwise, it would be a homework help desk. What forumlae and knowledge can you apply? Did your teacher tell you anything in class about hints to solve it? I'll hint you some. You'll need to know the weight of the water through w=mg. Check the water article for its mass, and convert. Apply the formulas at work and power. Your angle is 90 degrees. The pipe diameter doesn't matter, its there to fool you. Good luck ;) -- Mac Davis] ⌇☢ ญƛ. 07:19, 22 April 2006 (UTC)

Light

A spherical soap bubble of radius 2cm attached to the outside of a spherical bubble radius 4cm. What is the radius of curvature of the common suraface?

Per guidelines up at the top of the page we don't answer homework questions here, otherwise it would turn into a homework help desk. See this for help. -- Mac Davis] ⌇☢ ญƛ. 07:21, 22 April 2006 (UTC)

If the header is anything to go by, the answer is about 300,000 km/s. Grutness...wha? 10:35, 22 April 2006 (UTC)

Bound charge density

Can anybody tell me what is the bound charge density for a uniformly polarized sphere.Is it zero?Thanks!

Need more info. Solid sphere? Hollow? Conductor/insulator? Isopropyl 15:54, 22 April 2006 (UTC)

For a solid sphere.Thanks.

Well, you should look up bound charge (which redirects to polarization but does discuss it properly). Then you should think about what "uniformly polarized" means, and apply the formulas. But make sure to consider the surface of the sphere separately, if you care about the surface: assuming that there is nothing outside the sphere, the polarization is certainly not uniform when there's a sphere on one side of you and vacuum on the other! --Tardis 19:30, 22 April 2006 (UTC)

Centre of Gravity

this might sound adsurd to ask but why is a 4 legged stool more stable than a 3 legged stool? I think it has something to do with the centre of gravity.

That depends on how you define "stable". If you have an identical stool and you mount four legs on it rather than three, it will be less stable. The reason for this is that a tripod (three legs) is always stable on nearly any surface (try it!). A four-legged stool will always have one leg free in the air on any surface except a perfectly flat one (assuming the four legs are equally long). — QuantumEleven 14:07, 22 April 2006 (UTC)

It does indeed depend on what you mean by stable. Quantum's answer assumes that it means "not wobbly", whereas I think the questioner means "unlikely to fall over", which is different. With the latter definition, the stability of an object can be defined as the angle by which you need to tilt it before it falls over. This is the angle at which the object's centre of gravity ceases to be above the object's footprint. The further the COG has to shift sideways before it falls outside the footprint, the larger this angle and therefore the more stable the object. A three-legged stool has a triangular footprint, while a four-legged stool has a square one. Take two stools of the same seat size, one with three legs and the other with four, and draw their footprints - a triangle and a square. You will find that the distance from the centre of the triangle to the nearest point on any edge is shorter than the corresponding distance for the square. So, the COG of the three-legged stool has less far to travel to the edge of its footprint than the COG of the four-legged stool. In turn, this means that the three-legged stool has to tip through a smaller angle than the four-legged one before it falls over. This makes it more less stable. --Heron 17:18, 22 April 2006 (UTC)

That's an excellent response, although I think you meant to say that the 3 leg stool is "less stable", at the end. Another "stability" concern is the ability to resist tipping over if one or more legs collapses. With a 3 leg stool, losing any one leg will cause it to collapse. With a 4 leg stool, if the CG remains above the triangle formed by the remaining 3 legs, which is basically a 50/50 shot, then it will remain upright. 5 or more legs would make it even more stable (with 5 legs, any two legs could fail without causing the stool to collapse). So why don't stools typically have more legs ? That would add expense and weight and chair legs don't collapse all that often. Also note that the wobble problem with more than 3 legs is easily fixed with rubber feet on the stool, which will, in effect, adjust the height of each leg (within limits), to compensate for a lumpy floor. 3 leg stools also typically spread the legs out farther than 4 leg stools, to compensate for the "tippiness" inherent in a 3 leg design. The inherent instability of 3-wheel ATVs (all terrain vehicles) actually led to them being banned in many places due to fatal rollover crashes. 4-wheel ATVs are much safer. StuRat 18:27, 22 April 2006 (UTC)

Minor point: a uniform stool with five legs in a regular pentagon arrangement would fall over if two adjacent legs were lost. --Tardis 19:50, 22 April 2006 (UTC)

Well, yes. But you could have a regular square stool, with the fifth leg in the center. GeeJo ^(t)⁄_(c) • 14:12, 23 April 2006 (UTC)

Photon mass

Photons are massless, but according to E=MC^2, if photons' mass is 0, 0 times the speed of light squared is also zero. how about its energy? photons have energy i think? (2nd part of question moved to next section below.)

Photons have some amount of mass; see photon. As for atoms, see electron configuration for an overview of orbital theory. Isopropyl 13:51, 22 April 2006 (UTC)

The E=mc² equation is actually a simplification of Einstein's result. You can start at Energy-momentum relation for more details. Essentially, there is another term that relates to momentum and not just mass; this is where the energy of a photon is represented. (Despite having a zero rest mass, photons do indeed have momentum.) TenOfAllTrades(talk) 13:53, 22 April 2006 (UTC)

hmm, photons aren't massless for one thing--152.163.100.74 20:32, 22 April 2006 (UTC)

Photons are quite massless; I don't know where you and Isopropyl are getting that. Melchoir 20:40, 22 April 2006 (UTC)

Photons are exactly massless. The formula E=mc² relates the energy with mass of a massive particle in its rest frame where its momentum is vanishing. However in the case of a zero mass particle, this rest frame simply doesn't exist (a photon never has zero momentum)which forbids one from applying this formula to the photon. For a photon propagating with pulsation w then its energy is given by E= hcw² with h the Planck constant LeYaYa 21:22, 22 April 2006 (UTC)

What's pulsation? If you mean angular frequency, the formula is

$E=\hbar c\omega .\,$

If you mean ordinary frequency, the formula is

$E=hc\nu .\,$

Nothing is squared. Melchoir 21:58, 22 April 2006 (UTC)

Atomic Model

My chemistry teacher says that electrons orbit around the nucleus, and my physics teacher says taht it would lose energy if it does. How does the atomic model actually work?

I've split your question in two, hope you don't mind (makes it easier to answer). Have you read our excellent article on atoms? The short answer is that "electrons orbiting around a nucleus" (in the manner of planets around a sun) was a model of the atom used a long time ago (I seem to recall that it was developed by Niels Bohr, but I could be wrong), and while it's not technically correct per se (your physics teacher is correct, electrons orbiting a nucleus would lose energy and spiral in), it's a useful model for much of chemistry, as, below a certain level of complexity, it can explain effects observed in chemistry perfectly well (in school, it usually lasts until the last years of high school). As for what 'really' happens in an atom, things get a bit hairy... electrons behave in very strange ways, a bit like particles and a bit like waves (check out wave-particle duality if you're interested). Because of the Heisenberg uncertainty principle, we can never know exactly where an electron is, only that it's somewhere near the nucleus. Take a look at the picture at the top of atom - the dark regions (called orbitals) around the nucleus (the dot in the middle) are the regions where the electrons of a Helium atom are most likely to be found, but we don't know where in that region they are at any one time.

You'd be right to think that this is all very odd - it is. Also, I've greatly simplified things, if you're interested in more detail, ask again, and I'm sure someone with better knowledge of the subject will be able to help you. Have you tried asking your two teachers to sort out their apparent contradiction...? :) — QuantumEleven 14:04, 22 April 2006 (UTC)

As indicated above, the "real" answer (where real is the best current understanding, not an ultimate truth) is very complex, as well as counterintuitive making it hard to understand. Your chemistry teacher is using a model of the atom that is sufficient to explain most of chemistries dealings with atoms and electrons, probably the Bohr model, without burdening the class with the hard math and strange effects of quantum mechanics. Your physics teacher appears to have started on explaining quantum mechanics, and has indeed touched one of the primary reasons the theory was developed in the first place, because before it no satisfying atomic model existed. SanderJK 14:29, 22 April 2006 (UTC)

I would assume that the physics proffesor in question is probably explaining simple waves, accelerating charges around a point mass, etc... probably EM waves, but no quantum mechanics at all. am I right? and the bit about electrons falling into a nucleus is probably just a throw away example about moving charges generating waves? something about how if the classical model of the atom were correct atoms would just generate bright EM flashes then disappear into nothingness?--152.163.100.74 20:40, 22 April 2006 (UTC)

Actually, the planetary model is insufficient for chemistry. How can it explain bonding? A decent chemistry class will have much to say about quantum-mechanical orbitals. Melchoir 19:52, 22 April 2006 (UTC)

Well, it's true that the electrons would lose energy if they orbited the atom - if you described them as moving charged particles in the classical physics context. However, classical physics don't work on the atomic scale. You need quantum physics for that. Now, from the quantum physics viewpoint, the electrons do orbit the nucleus moving in what's called 'orbitals' - unlike in classical physics they can't have any energy, only certain discrete energy levels which each correspond to a pattern of motion. Motion in this sense is a bit strange concept though. - The electrons have momentum and angular momentum and so on, but they don't "move" in the classical sense of following some trajectory. Rather, all you have is a "probability cloud", that is a given probability that the electron will be at some point in space. So in summary, yes they orbit the nucleus, but they don't do it in any way which is similar to what we usually mean by 'orbit' as in planets. --BluePlatypus 16:18, 22 April 2006 (UTC)

your general chem proffesor is just teaching you the classical atomic model, and your physics proffesor is doing the same thing, short answer, the classical model was wrong, they don't teach you that in general chem, because general chem is basically just a test to see what percentage of the premeds actually have the patience to get through a chemistry course, most don't, just accept that everything they teach you between your first semester of general chem, and your second semester of organic is basically over simplified material designed to catch up students who may not have ever taken high school chemistry, or come from regions of the country with inferior public education systems--152.163.100.74 20:37, 22 April 2006 (UTC)

What experiments can I run of a polluted water sources (e.g collected from a heavily polluter river)?

At the beginning, i would like to say sorry to all users that i ask the question such directly since i am in hurry, please forgive my rudeness. Question:

Can any Wikipedia users give me some suggestions of experiments or test that i can do unto a pulluted water sources in a simple secondary school laboratry. My teachers do have some suggestion to me:

Listed below: 1.dissolved oxygen 2.quantity of chlorin ion,phosphate,magnesium ion

However, my teacher told us that if we can run extra experiments that beyond his suggestion list, then we can possiblely score a higher marks in this assessment. By this reasons, i am here to please for your helps to suggest some others experiments that i can carry out. If it don't touble you please also give the steps and equipments require for your sugested experiment. Please remenber that my school's laboratry is not quite well equiped.Thanks~

Timmy Ho From Hong Kong

A simple litmus test can give you the relative pH of the water. It's not too difficult and the supplies are cheap. Isopropyl 15:52, 22 April 2006 (UTC)

You could boil off the water and mass the remaining material. Really cheap and easy. Leonardo 16:16, 22 April 2006 (UTC)

Shake it vigorously, and watch for the formation of suds. These are a good indication of certain types of pollutants, such as phosphates. Compare how long it takes the suds to dissipate with an unpolluted control sample. StuRat 18:03, 22 April 2006 (UTC)

weight on planets

suppose you weigh 50 kilograms, or about 110 pounds.What would you weigh on Mars.

The same, if your scales were calibrated correctly. --Heron 17:23, 22 April 2006 (UTC)

No, you'd have the same mass if your scales were calculated correctly. You'd still have a mass of 50 kilograms, as a kilogram is a unit of mass, but you'd no longer weigh 110 pounds, due to the lower gravity. Our article on Weight has a handy table of interplanetary conversion factors, and a weight of 110 pounds on Earth (I'm assuming this part -- if you weigh 110 pounds on, say, Jupiter, the answer is different) would weigh 0.377 times as much on Mars which is about 41.5 pounds. Our Weight article has a very good description of the difference between weight and mass, if you're confused about that bit. --ByeByeBaby 17:54, 22 April 2006 (UTC)

(Edit conflict) That's not true. Weight refers to the force exerted by gravity, so that changes on different planets. The confusion here is because 50 kilograms is a unit of mass, which does not change from planet to planet. So if you weigh 110 pounds, according to this page, on Mars you would weigh 41.5. (In proper metric units, you used to weigh about 490 newtons, and now weigh about 180. It's a bit confusing that many places using metric units refer to peoples' "weights" in units of mass.) -- SCZenz 17:56, 22 April 2006 (UTC)

My answer was deliberately oblique because I didn't want to do the questioner's arithmetic for him. Besides, I was making the semi-serious point that scales on Mars should either read mass in kilograms, or force in newtons. Imagine you're a cook in a Martian colony. You would want a kilogram of potatoes to register "1 kg" on the scale, not "377 g". After all, you want to know how many stomachs they are going to fill, not how heavy they feel. If the scales corrected did not correct for the difference in gravity, then recipes would all have to be different depending on the planet you were on. (Or they could all be translated into moles, which would be even weirder.) Our attempt to colonise the galaxy would collapse in confusion, I tell you! --Heron 18:47, 22 April 2006 (UTC)

If you weigh 110 pounds, you belong either in school or in the kitchen; since neither institution is available on Mars, the question is moot. (runs away) Melchoir 20:06, 22 April 2006 (UTC)

If we're getting into terminological exactitude, bear the following in mind. When a person says "I weigh 100 kgs on Earth but only 37.7 kgs on Mars", they're really saying:

• My mass is 100 kgs (everywhere in the universe).
• My weight here on Earth at sea level is 100 kgs weight.
• My weight on Mars would be 37.7 kgs weight". JackofOz 02:30, 23 April 2006 (UTC)

Long bones

how do you determine right or left humerus, femur and tibia long bones?

I believe that right and left in the anatomical sense refers to the right and left of the patient; for instance, this image is looking at the heart from the front, and the right and left sides labelled are those of the patient, not of the observer. There is only one humerus in each arm, and the right and left humerus..es? would be mirror images of each other. The same goes for the femur and the tibia - there is one of each in each leg. As can be seen from the images in the articles linked, all these bones have different shapes, and could hence be differentiated from each other. -- Mithent 20:15, 22 April 2006 (UTC)

Car Tires

Funny story: my friend's dad accidentally ran over her foot with a Ford Explorer this morning. What is really unusual in my opinion, however, is that she says that it didn't hurt that much, except for a little throbbing afterwards. The bones of her foot are all intact, etc. How does this happen? Does the weight of the car redistribute itself somehow to the other three tires? What is the exact mechanism that doesn't cause one-fourth the weight of the car to bear down upon a foot that is being run over? JianLi 19:16, 22 April 2006 (UTC)

There is no magical mechanism required. A tire can only exert 35 psi (the tire pressure) on anything it runs over. The lower part (toes mainly) can easily take this. If it runs up higher, the ankle smashes and the foot is a total wreck. --Zeizmic 19:34, 22 April 2006 (UTC)

Er, that 35 psi business isn't right. Think about an elephant sitting on a unicycle. Certainly not just a few psi there, even if the tire was inflated just to that. Partly, the tire is compressed, so the pressure (and/or temperature) will increase. Also, the material strength of the tire is available to provide force beyond the air pressure. As for foot survival: I'm not sure how the suspension on the car might affect it, but obviously if her foot was level with the road (in a foot-shaped hole, for instance), the car has no way of "knowing" that one of its tires is on a foot, so I would expect approximately 1/4 the car's weight to, er, participate. But it's not like throwing 1/4 of a car at someone's foot; very little energy and momentum is involved, just force. And think about standing, or even hopping, on tiptoes of one foot while carrying a heavy backpack — it's quite possible to generate over a kN of force that way, and the car won't exert that much more. Moreover, that's on tiptoes, not with the foot flat and well-supported. And you'll get a little help if you're wearing anything more than sandals. I don't know what the maximum load on a flat foot is, but hopefully this helps you see how it's possible to be this great. --Tardis 20:10, 22 April 2006 (UTC)

The 35psi is correct. Consider an 8-inch wide tire. Press down until you have approximately an 8x8-inch square in contact with the ground. That is 64 square inches. At 35psi, that one tire supports over 2,000 pounds. So, it will take over 2,000 pounds to get a 35psi tire to form an 8x8 footprint. At less weight, the footprint shrinks to something like 4x8 (slightly over 1,000 pounds). As you put more weight on a tire, more of the tire comes in contact with the ground, so the psi multiplies to support the weight. The less weight, the less tire in contact with the ground. So, regardless of the weight in the vehicle, when it runs over your foot you get 35psi on every square inch of your foot. Side note: my bike uses 60psi, not 35. Mainly, the tire is skinnier so it needs to be higher. As for weight on a flat foot - the toes can handle a lot of weight. As mentioned eariler, the arch of the foot will compress and get damaged. --Kainaw ^(talk) 00:13, 23 April 2006 (UTC)

thanks for your responses! has anyone ever had a similar experience?JianLi 01:11, 23 April 2006 (UTC)

I think when I was ~8 I put my besandled foot in the path of my dad's sports car. Didn't feel hardly a thing, but it may be confabulation caused by dreaming, happens to me a lot. -- Mac Davis] ⌇☢ ญƛ. 01:40, 23 April 2006 (UTC)

The 35 psi doesn't sound instinctively right, but the arguments are pretty good: and 35 psi can hold a lot of weight. And if you think of a 35 pound weight, formed into rod one inch across, that's a fairly heavy thing. Pile up rods like this on end to cover your foot, and it would be uncomfortable, though not crush your foot like a bug. (Not that all bugs crush well.) The elephant on the Unicycle? If the tyres were not large enough or the pressure not high enough, the tyre would first compress, increasing its pressure. Then, because there is more tyre above for the air to go, the tyre would flatten until the wheel was resting on its rim; the tyre may or may not be damaged. So if the elephant ran over your foot, what runs you over is the wheel rims directly, which have a small area of contact and very high pressure: worse than the elephant standing on your foot, which spreads the load. According to some back-of-the-envelope studies, elephants are nothing compared to stilleto heels, which can give "hundreds" of times the pressure on your foot. I think these studies tend to oversimplify (e.g. by measuring pressure on the ground over the entire large foot, then assuming that the parts of the foot in contact with your shoe apply the same pressure; and by ignoring the profile of the sole of the foot, assuming it is a flat surface). Notinasnaid 07:26, 23 April 2006 (UTC)

Sodium Usnate

Can anyone possibly draw, create or show me the strucutural formula for the monosodium salt of Usnic acid. I asked my chemistry teacher but it is beyound the scope of her knowledge. Tahnk you, Christopher

Google image search shows us these two diagrams for usnic acid. It appears to be a phenol with three hydroxyl groups; presumably it donates a proton from one of them, but I don't know how to guess which one is the weakest. Melchoir 22:25, 22 April 2006 (UTC)

My best guess would be that the OH group on the right in the first link is more likely to lose it's H then the other two, since it is close to two doublebonded oxygens, connected via sp2 C-C / C=O hybrid bonds. The double bonded oxygen is very electronegative, and the sp2 hybrid structure would be able to spread the extra electron from a hydrogen dissociation over a high number of relatively low energy states of the molecule, lowering the overall dissociation energy. However, i would not be surprised if the dissociation energies were close enough to each other that in reality a mixture of 3 salts would occur (with fraction depending on the relative dissociation energy of each O-H bond). SanderJK 23:47, 22 April 2006 (UTC)

Hmm... it sounds like you're describing the one of the left here, the one that's alone on its ring? It's the lone OH that loses its proton in this diagram, which I just found. Melchoir 00:18, 23 April 2006 (UTC)

Yeah, that's the one i expected, thanks, i meant second link not first i now see. I did some further digging on the subject, it seems the monosodium salt of usnic acid has the trivial name of Binan, and is denoted as C18H15NaO7 . 2.5 H2O in at least 2 references. I also found a link to a resolved crystal structure of Binan, but it isn't really my field of expertise, can't say for sure what exactly it is saying about the structure here. SanderJK 00:34, 23 April 2006 (UTC)

Smoking vs. Chewing

I have a medical question. Now before you all go on about how I'd be better off asking a doctor, let me just say that I've asked many doctors, and none seem to be willing or able to give me a straight answer.

I'm a former smoker. I finally quit smoking by chewing nicotine gum. The transition was actually quite easy. Now I hardly think of having a cigarette as I find chewing the gum to be more pleasant, both for me, and those around me (no smoke to irritate my eyes, no second hand smoke to irritate the people around me.)

The problem is, unfortunately, quitting the gum is proving to be far more difficult than quitting "smoking" the nicotine.

From what I understand (and correct me if I'm wrong...that's the point of my question), the vast majority of all (or most) of the ill effects of smoking, such as cancer, heart disease, etc... etc... etc... are not the result of the nicotine (the addictive substance in tobacco) but the result of other, non-addictive yet deadly substances, such as tar, carbon monoxide, even certain forms of cyanide (I once read somewhere that there are dozens if not hundreds of different deadly substances in cigarettes.)

Nonetheless, I fully understand that nicotine itself is not the healthiest thing in the world and should be avoided as well.

I'll put my question this way: Let's say on a scale of 1 to 10 we place cigarette smoking as a 10 when it comes to being harmful for one's health. Where then should we put chewing nicotine gum? Is it only half as harmful as smoking, in which case we'd give it a 5? Or is it actually 80% as harmful as smoking in which case we'd give it an 8? Or is chewing nicotine so much less harmful than smoking that we'd give it a 1 or less? Thanks to anyone who may have knowledge to share. Loomis51 21:19, 22 April 2006 (UTC)

You won't get cancer from nicotine gum. Brian G. Crawford 21:24, 22 April 2006 (UTC)

• You are correct, the vast majority of bad effects of smoking are from the smoke itself and not the nicotine. I'm not sure the long-term effects of nicotine gum have been studied, but non-smoking tobacco products like the Scandinavian Snus have been studied intensely, with the conclusion that they're not risk-free but certainly much better than smoking. (There's public debate in those countries whether it should be recommended by physicians as an alternative to smoking, basically the old Harm reduction debate). While these substances are probably still carcinogenic and the risk of cancer can't be ruled out, it's worth noting that the smaller the risk, the more difficult it is to establish the correlation. --BluePlatypus 21:34, 22 April 2006 (UTC)

I'll concur with what BluePlatypus said. While nicotine in large quantities is an acute toxin, long-term exposure to low levels is certainly a lot easier on your system than smoking. Nicotine raises heart rate and blood pressure, though probably not to a dangerous extent in an otherwise healthy individual. Nicotine is not a known carcinogen, but there is some research to suggest that it may be metabolized to carcinogens within the body: [14].

Nicotine messes with your brain chemistry in ways that are not fully understood. There is debate (see our nicotine article) about its relationship with disorders including schizophrenia, Parkinson's disease, and Alzheimer's disease. (In some cases it is thought to be a potential risk factor, in others it is being investigated as part of a treatment regimen.)

Regardless, your health will be better if nicotine is the only toxic substance you're putting into your body, rather than nicotine plus other poisons and carcinogens. You'll dramatically cut your risk of lung ailments, particularly emphysema and lung cancer. You'll lower your risk of COPD and other cardiovascular ailments, too. Finally, you're likely to be happier—you won't smell bad to people around you.

I don't know if there any long-term studies exist on the risks and effects of chronic nicotine usage. I'm willing to go out on a limb and say that you'll significantly lengthen – and improve the quality of – your life by switching from cigarettes to gum. TenOfAllTrades(talk) 21:58, 22 April 2006 (UTC)

Snus is still tobacco and despite the fact that it isn't smoked, it is still carcinogenic just as chewing-tobacco is. The only difference is that "chewing" tobacco results in cancer of the mouth rather than that of the lungs. It's still carcinogenic, and as such it may be different from nicotine gum. What I'd like to know is the ill effects of nicotine alone when compared to tobacco (whether smoked or chewed.) This leads me to wonder why doctors in Scandinavian countries would recommend snus rather than simple nicotine gum.Loomis51 22:10, 22 April 2006 (UTC)

Twenty years ago, as I lay on the emergency department trolley, watching my clothes being ripped off by nursing and other medical staff, the admitting doctor, who was a friend of my accompanying wife, who was a nursing sister in the same hospital, told her it might not be a bad idea to call all our family and friends as, "I have never seen anyone survive a blood pressure reading as high as this without either a major heart attack or stroke resulting". I was in intensive care for 3 weeks thereafter. But the cardiologist in charge of my case (a saint) told my wife that as he had spent so much time and effort in keeping me alive, the least I could do would be to give up smoking the 60 a day habit I had developed over the preceding 20 years. I see him every 3 months or so and his first question is always the same, "How much money have you saved since you stopped smoking?". At today's prices for a packet of 20 Benson and Hedges King Size being £4.85 - say $7.46, I am always happy to tell him I have saved about £106,205 or $163.392 (to date). Forget the chewing gum - the best advice I got was to choose whether to live or smoke - "you can't do both". Or even better, "Stopping smoking is easy - all you need to do is cut out the first cigarette of the day".195.93.21.7 23:38, 22 April 2006 (UTC)

Loomis51, Snus has not been conclusively shown to cause cancer, after a number of long-term studies, including oral cancers of the types caused by chewing tobacco. It does contain carcinogenic substances. However, that doesn't necessarily means it causes cancer to any significant effect. (Plenty of everyday foods contain carcinogens as well.) --BluePlatypus 01:40, 23 April 2006 (UTC)

Nicotine is a powerful anti-anxiety, anti-depressant drug. I would discuss with the doctor to try to flip over to another drug, such as zoloft or celexa. --Zeizmic 12:00, 23 April 2006 (UTC)

planets and the solar system

on which planet would you weigh the least. on which planet would you weigh the most. on which planets would you weigh more than you weigh on Earth on which planets would youweigh less than you weigh on Earth on Venus the apples are the ripest in the solar system.You need 5 pounds.[Earthweight].How much should you have the clerk weigh out for you. If you also pick up 10 pounds of pickles and 7 pounds of cole slaw and pickles will you have when you arrive on Mercury. MERCURY VENUS MARS JUPITER SATURN URANUS NEPTUNE ANSWER THIS PLEASE.

Do your own homework. If you need help with a specific part or concept of your homework, feel free to ask, but please do not post entire homework questions and expect us to give you the answers. Melchoir 22:39, 22 April 2006 (UTC)

In any form of reality where the apples on Venus are the best in the solar system the planets will almost certainly have different physical characteristics to those in our reality. because of that, it is impossible to determine the answer to the first few questions without first knowing those different characteristics. As to the last question, when you arrive on Mercury you would have lunch. Grutness...wha? 23:32, 22 April 2006 (UTC)

Spermy Vegetation

I visited college in New Haven this weekend, and I noticed the smell of sperm every time I passed some trees, so I assumed it was coming from the trees or some vegetation around them. (and no, it wasn't college kids, because this happened near too many trees). I thought I was just being stupid/delusional, so I didn't say anything, but later, some other guy said he noticed it too. I've noticed this smell before around trees around blossoming time. What causes this spermy smell, and why is it so similar to human sperm? I know plants have sperm, but their sperm is analogous, not homologous, so there'd be no reason for the smell to be similar, right? JianLi 01:05, 23 April 2006 (UTC)

Have you checked the wikipedia article on 'spermy vegetation'? --Username132 (talk) 01:46, 23 April 2006 (UTC)

Please don't refer people to nonexistant articles. —Keenan Pepper 02:57, 23 April 2006 (UTC)

The plants are probably exreting some kind of polyamines. It's the type of chemical (Spermine and Spermidine in particular) that give semen its smell. --BluePlatypus 01:49, 23 April 2006 (UTC)

Take a look at [15] Black Carrot 03:05, 23 April 2006 (UTC)

Internet Radio Player - Alternative To WinAmp

Can anyone suggest an alternative to WinAmp that will let me search through and play streaming radio stations from around the world for free? WinAmp has packed in and the others I've tried seem to want me to use a website to initiate the streaming; I'd like it be done from within the program itself like WinAmp used to when it still worked. --Username132 (talk) 01:44, 23 April 2006 (UTC)

Nullsofts site is the best for internet radio directory

facts....

i just need facts about Xenontime! I already have this much:

Xenotime is very rare. It forms a solid solution series. Xenotime is used mainly as a source of crystal specimens which are valued by collectors. Occasionally, gemstones are also cut from the finer xenotime crystals.

What are you talking about? Those are just random sentences from the introduction of Xenotime. Melchoir 02:46, 23 April 2006 (UTC)

Google makes some things very easy. See: [16], [17], [18] and lo and behold, we have an article here on it: Xenotime.--Fuhghettaboutit 02:49, 23 April 2006 (UTC)

Outdoor Air Quality meters

Where can I buy outdoor air quality meters? (what brands?; what models?)

Physics

A fisherman yanks a fish out of the water with an acceleration of 4.5m/s/s using very light fishing line that has a "test" value of 100 N. The finsherman loses the fish as the line snaps. what can you say about the mass of the fish?

So okay, this is surely wrong, but I have to show some work here:

F = ma
FA - FG = 4.5m
FA/4.5 - FG/4.5 = m

Yeah I have no idea what's going on there....absolutely have nothing on this besides the answers ( > 7.0 kg) but I need to know how to do it. Thanks

05:13, 23 April 2006 (UTC)

Okay, assuming he's pulling it straight up out of the water (not sideways), the force on the line is the weight of the fish plus the force required to accelerate it at 4.5 m/s², so

F = m * 9.8 m/s² + m * 4.5 m/s²

(9.8 m/s² is the acceleration of gravity on Earth's surface). If the line snapped, that means F > 100 N. —Keenan Pepper 05:32, 23 April 2006 (UTC)

Thanks a lot Keenan Pepper. I have one question though, the acceleration is going into the opposite direction from gravity, wouldn't you subtract? I know it's obviously wrong, what I'm saying, but I don't know why. So that's like having it as F = 13.41m which gives the correct answer, but I don't get how that works. If you could kindly explain that, thank you.

05:49, 23 April 2006 (UTC)

Well, yes, you can subtract the weight from the tension to get the acceleration, T-W=ma. But you want to solve for T, so you rearrange: T=ma+W. Melchoir 06:01, 23 April 2006 (UTC)

Oh right, that's what I was doing, but I completely forgot I had tension there, stupid me. Thanks a lot!!! 06:06, 23 April 2006 (UTC)

• The fish isn't even struggling? - Mgm|^(talk) 10:24, 23 April 2006 (UTC)

Linear regulator explanation or diagram

I had a compelling discussion with an engineer friend of mine about linear regulators based on NPN transistors. The articles on these are pretty descriptive but he had a pressing question, which is that in the case of a linear regulator which is designed to allow a specific voltage and current to propogate on the emitter, regardless of input voltage (above a certain point), what specifically causes the output voltage and current to be so well regulated, specifically when energy is wasted where does it go and why? We are looking for a description at the electron level, and hopefully a good way to explain this to to electrical engineers who don't necessarily have a expert understanding of the chemistry of transistors. Anyone got a good idea where to start? There are many articles on transistors in general but i've seen none that deal with the behavior of a linear regulator at a low level. Thanks! --24.210.51.36 05:23, 23 April 2006 (UTC)

Codeine

If i purchased Codeine from my doctor, and it was back in 2001- Will it have expired by now?

I would think so, yes. StuRat 06:19, 23 April 2006 (UTC)

It's really not a good idea to get health advice over the internet; if it were me I'd take the codeine anyway (in fact I have done exactly that), but I am NOT recommending you do the same. My advice is to either call an all-night pharmacy, or go to the front of your phone book and call a community health nurse or poison control hotline. They usually operate 24 hours a day, so you can get advice now if you like.--Anchoress 07:25, 23 April 2006 (UTC)

The "do as I say, not what I do" approach is fraught with difficulties and is best avoided, Anchoress. Why is the advice you give to the questioner not something you would follow yourself?  :--) JackofOz 14:12, 23 April 2006 (UTC)

It may also not be a good idea to self-medicate with narcotics. If you're in sufficient pain to need codeine (that is, the regular over the counter painkillers like acetaminophen/paracetamol, ibuprofen, and ASA/aspirin won't cut it) you might want to seek professional medical assistance anyway. TenOfAllTrades(talk) 12:03, 23 April 2006 (UTC)

Expired, yes; in as much as the "use before" date has probably been passed. That said, it should still retain most of its activity (% unknown), if it has not been exposed to moisture, heat or light. There are no reports of "old codeine" causing any illness ascribed to a changed chemistry.. --Seejyb 15:56, 23 April 2006 (UTC)

The Hydrological Cycle

Hello, I would like to known how does the hydrological cycle of a drainage basin in the tropical landscape differ from that in the tropical desert landscape. Is there anyone can help me? Thank you very much! I have to finish this Easter assignment on time!

Since we can't actually do your assignment for you, can you let us know what research you've already done, and where you are stuck or puzzled? Do you know what a hydrological cycle is, to start with? Notinasnaid 10:19, 23 April 2006 (UTC)

You won't find the exact answer to your question, but you might find the article here, Water cycle useful in understanding what is involved. Note: pure serendipity-- water cycle just happened to be a link from the article I gave in my answer to the next question below on water bonding --Fuhghettaboutit 11:04, 23 April 2006 (UTC)

Drainage basin -- Mac Davis] ⌇☢ ญƛ. 11:24, 23 April 2006 (UTC)

The molecular bonding of water

Hello everyone,

I am a Standard Grade Chemistry student and, as it is nearing the time for my final examination, I was wondering if anybody could help to clarify something for me - Is water COVALENTLY or IONICALLY bonded? - as I have conflicting information in my course notes.

Any help would be greatly appreciated. Thank you.

195.188.152.16 10:30, 23 April 2006 (UTC)

Water is made up of polar covalently bonded molecules. However, Hydrogen bonding is also at play and explains many of water's properties such as its relatively high melting and boiling points. Much more information can be found at Water (molecule)--Fuhghettaboutit 10:41, 23 April 2006 (UTC)

you know, for a second i thought you said you were a grad student, i really should wear my glasses whilest browsing the interent--152.163.100.74 14:50, 23 April 2006 (UTC)

The confusion may be due to learning about the Self-ionization of water - though covalently bonded, water form ions when dissolved in itself. Yet one does not refer to the water molecule as being ionically bonded. --Seejyb 16:33, 23 April 2006 (UTC)

Max keys pressed simultaneously

While playing some 2 player fighting games, the fact that just a number of maximum keys can be pressed simultaneously is damn annoying. I've read it's about the architecture and design of the keyboard. Is there any implication of the software running in this issue? Can anyone give me some information about how keyboards work (in a sense suitable to my question)? Any advice (apart from the obvious) of getting around this problem? Thanks.

Upper limit for ships

Okay, two questions today, I'll put them in sepearate sections.

The first is about the Freedom Ship. It says on that page that ships cannot be made realistically larger because of sagging and hogging. However, those types of issues arise (according their own respective pages) when the ship is about the same length as the waves. Surely waves are not ~1 mile in length? Thus, the stresses put on a ship that long would not be all put on the middle; there would instead be several points of stress on the hull. (Crude ascii drawing follows... I apologize in advance)

^ indicates point of stress (crest of wave) Normal ships:

====================

____^

Freedom ship:

=========================================================================

___^_____^______^________^______^_______^______^

Each point of stess would be the crest of a wave. So would the Freedom ship be possible (financing, etc aside). I would think that unless a half-mile long wave comes along, the Freedom ship would handle waves as well as a normal ship. Is this right? And, more generally, what are the practical, and the theoretical, limits on the sizes of ships?--AK7 14:49, 23 April 2006 (UTC)

I think the problem with building huge ships is due to the fact that they are magnetically attracted to icebergs... (what, too soon?). Seriously though, the problem with building anything on that scale is that as the strength of construction materials scales linearly (build steel twice as thick and it can carry 2x the weight) the demand for srength scales geometrically (make a ship twice as long and it requires length^3 strength) It's the same limitation that forms the upper boundary of animal size, barring special adaptation by nature. So in summary, yes it can be done but it requires a complete rethinking of the way ships are structured, its not as easy as taking blueprints and blowing them to 10x size and making a ship. --24.210.26.146 15:08, 23 April 2006 (UTC)

Freak or rogue waves can be huge, with long wavelengths. Here is an interesting link [19] If a large ship catches one, it has to act as a bridge. This is generally impossible with the limitations of cross-section needed for propulsion and navigation. --Zeizmic 15:31, 23 April 2006 (UTC)

Good points... couldn't the ship be built in sections, though? We've all seen those buses can bend in the middle, allowing them to turn corners while still being very, very long. Could the same concept be applied in the vertical dimension to a ship? --AK7 15:38, 23 April 2006 (UTC)

I assume you mean the horizontal dimension. I believe it could, but then they would each need their own propulsion and steering system, so the cost of a ten segment ship would be almost as much as ten separate ships (with perhaps some savings by only have one captain and crew, instead of ten). Some software would be needed to execute a turn by moving the rudders on each ship at different times, as turning them all at once wouldn't work, but that seems doable. Such a system would allow the "train" of ships to turn as sharply as any one can turn. The problem is that this slightly lower cost may not justify the loss of flexibility you would have with ten separate ships. One way around this would be to make the ships capable of operating either together or apart. Incidentally, the ships may not need to be physically connected, but only connected by electronic communications, although tow lines might be needed in case one segment breaks down. StuRat 16:40, 23 April 2006 (UTC)

Maximum daily water

How much water can one safely drink daily? I know about Water intoxication and all, but I'm not asking about that, strictly. Rather, I keep a water bottle next to my desk and drink from it often; I realized a couple days ago that I had gone through 5 liters in a day, and would have reached 8 if I hadn't conciously stopped at that point. It typically takes 1-2 hours to drink a liter (within the 1.5 ltr\hour limit cited on the water intoxication page). But, even if it is safe, is it desiriable to drink that much water? Does it put my kidneys under extra stress? And, if there are impurities in the water (there probably aren't, but just for future reference), is the stress on my kidneys based on the concentration of impurities, or the total amount (which would increase with more water, obviously.) There are thousands of pages telling us to drink more water... at what point does the law of diminishing returns kick in?--AK7 15:06, 23 April 2006 (UTC)

The need for so much water was a misunderstanding of some old report, and has now become a myth. [20]. I have never seen anything scientific on this. In fact, if you believe that you should lean towards the 'human evolution' ideal, most of our millions of years were spent on the dry savanna. All the water makes you pee a lot, and have to visit the filthy, stinky washroom (we've got 'waterless' stinky urinals!), picking up bird flu, and sending more water into the sewers. --Zeizmic 15:41, 23 April 2006 (UTC)

High water intake may be a sign of a medical problem or high sodium intake. Try reducing the amount of salt in your diet and mention the high water intake to your doctor, during your next checkup. StuRat 16:25, 23 April 2006 (UTC)

One danger of bottled water is that toxic chemicals leach into the water from the plastic containers over time. So, drinking old bottled water, especially if stored in hot areas, in quantity, can expose you to lots of toxic chemicals. That's why bottled water has expiration dates on it. You can sometimes taste the chemicals in the water, too. I suggest you use filtered tap water and store it in glass containers, for optimal safety. If you must use plastic containers, refilling them (with filtered tap water) right before you use them will limit the accumulation of toxic chemicals in the water. StuRat 16:25, 23 April 2006 (UTC)

Touch and Yawn

When my cats are relaxing (that is, most of their waking hours), most often, when I give them a pet, they start yawning. What could possibly be the connection between the physical soft contact of a big human hand and the taking of a deep breath with widespead jaws?--JLdesAlpins 15:39, 23 April 2006 (UTC)

I believe yawning is to increase blood flow to the brain to make the human or other animal more aware. If they are going to do something, in this case just interacting with a human, they need to wake up a bit, hence the yawn. What's really fun is when they myawn (start a meow and end up yawning). StuRat 16:15, 23 April 2006 (UTC)

Leeches in USA Ponds

I have a pond that a blue heron has decided to visit. He has brought with him a leech. I have only found one so far and it was swimming. Does anyone know which type of leech this would be and how often it multiplies? I am about 45 miles northeast of San Francisco. Any help would be appreciated. Thanks. Terrill

Photosynthesis

Recently, I have been reading about photosynthesis, but there is a part - the effect of carbon dioxide concentration on the rate of photosynthesis - which I cannot understand. Could anybody please explain it to me in a simple way? Thanks