Wikipedia:Reference desk archive/Science/2006 July 16

From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Humanities Science Mathematics Computing/IT Language Miscellaneous Archives
The page you are currently viewing is an archive page. Whilst you can leave answers for any questions shown below, please ask new questions at one of the pages linked to above. This will insure that your question is answered more quickly.

< July 15 Science desk archive July 17 >


Chemical formula[edit]

Give the chemical formula of fucitol.

Try our article fucitol, and notice the little link there to fucitol (data page). If you think the name is silly, this might amuse you.-gadfium 01:13, 16 July 2006 (UTC)
How enjoyable! I particularly liked Furfuryl Furfurate, surely a candidate for "The Greatest Furphy of All Time". JackofOz 03:30, 16 July 2006 (UTC)
I like the shape of Cubane. It's the projection of a 'four-dimensional cube' (what's that called again?) in the third dimension. Well, on the image on the page you linked to, not the presentation in our article, alas. Maybe a hint that Cuba is from a different dimension?
Continuing the off-topicity - on the STNG credit titles there is someone named 'Fukuto'. DirkvdM 09:34, 16 July 2006 (UTC)
A four-dimension cube is probably best known as a tesseract or a 4D hypercube. Other synonyms are in the tesseract article. But cubane seems just to be a 3D Cube! -Nunh-huh 09:39, 16 July 2006 (UTC)
Yep, that's the one I was thinking of. Like I said, don't look at the Wikipedia article for Cubane, but follow gadfium's link and look at the Cubane pic there. DirkvdM 19:05, 16 July 2006 (UTC)
I like Draculin, myself. The protein in the saliva of vampire bats which keeps their prey's blood from coagulating. User:Zoe|(talk) 21:00, 16 July 2006 (UTC)
arsole any one? Xcomradex 01:36, 17 July 2006 (UTC)

Citric acid in lime[edit]

What is the percentage of citric acid in lime?--70.231.63.41 00:52, 16 July 2006 (UTC)

Wikipedia says "Citric acid exists in a variety of fruits and vegetables, but it is most concentrated in lemons and limes, where it can comprise as much as 8% of the dry weight of the fruit." Read more here and here.  Killfest 01:31, 16 July 2006 (UTC)
Why shout? DirkvdM 09:36, 16 July 2006 (UTC)
they're excited? Xcomradex 01:39, 17 July 2006 (UTC)

mammals[edit]

What's a mammal?

According to good ol' Wikipedia, mammals are "the class of vertebrate animals characterized by the presence of mammary glands, which in females produce milk for the nourishment of young; the presence of hair or fur; and endothermic or "warm-blooded" bodies". Read more here.  Killfest 01:29, 16 July 2006 (UTC)
Give a man a fish... —Keenan Pepper 02:20, 16 July 2006 (UTC)
...and he'll get a totally wrong idea about what a mammal is. Weregerbil 14:59, 16 July 2006 (UTC)
But if you teach a man to fish, he might catch a dolphin. Digfarenough 17:19, 16 July 2006 (UTC)
And if you teach a man to dolphin ... DirkvdM 19:06, 16 July 2006 (UTC)
And? User:Zoe|(talk) 21:02, 16 July 2006 (UTC)
And he'll probably never return to appreciate the wit we've produced on his behalf. Black Carrot 04:46, 17 July 2006 (UTC)
Why learn to swim when you can rent a fish? Grutness...wha? 09:30, 17 July 2006 (UTC)
Anyone here ever seen Red Dwarf? This begins to remind me of Rimmer's tenth astrophysics exam. Black Carrot 19:32, 18 July 2006 (UTC)
I thought the saying was "Give a man a match and he'll be warm for a day. Light him on fire, and he'll be warm for the rest of his life." 80.242.161.211 08:52, 20 July 2006 (UTC)
...however short the rest of that life may be! :D

C++ Compiler[edit]

I know that I can type HTML code in Notepad and then save it as an HTML file to see the desired output.

My computer has Windows XP; in what program do I enter C++ source code?

#include <iostream>

class Bird                 // the "generic" base class
{
public:
  virtual void OutputName() {std::cout << "a bird";}
  virtual ~Bird() {}
};

class Swan : public Bird   // Swan derives from Bird
{ 
public:
  void OutputName() {std::cout << "a swan";} // overrides virtual function
};

int main()
{
  Bird* myBird = new Swan; // Declares a pointer to a generic Bird,
                           // and sets it pointing to a newly-created Swan.

  myBird->OutputName();    // This will output "a swan", not "a bird".

  delete myBird;

  return 0;
}

Where do I go to paste this code and see its output. I have no clue about programming, yet I very much want to know this.--71.107.225.71 03:07, 16 July 2006 (UTC)

You can type the code in Notepad or any text editor, and save it with an extension of .cpp or .cc. You then need a C++ compiler to turn it into a .exe file. You can get such a compiler for Windows XP from cygwin for free, or you can download free versions of the Borland C++ or Microsoft Visual C++ compilers (which don't have all the features of the for-money compilers, but which will suit your purpose). The Microsoft compiler includes an editing environment. The Borland one may do. Cygwin is more bare bones, and comes from the Unix tradition. If you have no initial preference, you'll probably find the Microsoft one easiest to begin with. There are links to it from Visual C++ 2005 Express Edition.
I would suggest you use Mingw as it makes things less complicated to deploy than cygwin does. helohe (talk) 00:20, 21 July 2006 (UTC)
C++ is not the easiest language to start with if you have no previous programming experience, but good luck!-gadfium 03:55, 16 July 2006 (UTC)
A correction: it seems that the Borland compiler, now called C++ Builder, is not available for download, although some magazines give an older version of it away. I've put tags around the code above so it displays more correctly.-gadfium 04:04, 16 July 2006 (UTC)

Thank you.--71.107.225.71 04:18, 16 July 2006 (UTC)

Note that Gadfium said 'any text editor'. That means 'no word processor' - the ones with all the make-up buttons that add stuff to the source, which messes up your code. DirkvdM 09:41, 16 July 2006 (UTC)
Does anybody have a favorite free text editor? I suppose Notepad serves, but I like the bells and whistles associated with EditPlus, which, unfortunately, is only free for 30 days. User:Zoe|(talk) 21:04, 16 July 2006 (UTC)
I like vim, but I warn you that most people who don't have a Unix background find it difficult to use, and some people who do have a Unix background prefer Emacs. See editor war.-gadfium 07:44, 17 July 2006 (UTC)
I have been pleased with emacs, but I do all my programming in Pico . . . and if you thought Notepad was basic, try Pico Registrar

Increasing resting metabolic rate[edit]

How can I increase my resting metabolic rate? (Foods, action, etc. would be helpful...) Thanks! --Un sogno modesto 06:42, 16 July 2006 (UTC)

Increasing you muscle mass should do it. Load bearing exercise, weight training that sort of thing. Theresa Knott | Taste the Korn 08:31, 16 July 2006 (UTC)
Yeah, but then you grow ugly. If you want muscles that don't make you look like an idiot, try hiking. Get away from it all for a few days, breathing fresh air, enjoying nice views. And bring loads of food to increase the weight of your pack, so you have to work hard and build up muscles - useful ones. DirkvdM 09:46, 16 July 2006 (UTC)
"If you want muscles that don't make you look like an idiot". Don't feed the troll. GTubio 17:42, 16 July 2006 (UTC)

You could turn the heating off and wear less clothing. Decades ago (at least in the UK) people ate more calories than we do now, yet were thinner. In part this may have been due to them taking more exercise as a result of not having so much access to cars or mechanical aids such as washing machines or grass mowers, but I think it was mostly due to the lack of central heating and consequently the body thermoregulates by producing more heat.

This has reminded me of reading a non-fiction contemporary account of a sailing ship voyage through a passage at the extreme southern tip of South America. It might have been Darwin's Voyage Of The Beagle, Dana's Two Years Before The Mast, Cole's Tracks Of A Rolling Stone, Slocum, or something else in the 18th. or 19th. centuries. The author described how the natives, who came to the ships in canoes to trade, where wearing no clothing at all yet were comfortable even when it was snowing. They must have had very high basal metabolisms to prodce enough body heat. So you could increase basal metabolism by becoming a nudist! --62.253.52.46 10:49, 16 July 2006 (UTC)

You could also try drinking more coffee or tea, at least for a short metabolic rate increase. Also i'm not sure if the reason is for dieting but if it is please don't go missing meals it'll seriously slow your metabolic rate down. Benbread 11:38, 16 July 2006 (UTC)

Tame birds vs. domesticated birds?[edit]

What's the difference? I was talking to someone online about my hyacinth macaw yesterday. I can't remember how the conversation got onto this but he stated that while I have 'tamed' my parrot, I have not 'domesticated' him. What's the difference?

According to our article, domestication is something that happens to a species or breed over many generations; taming is what you do to one particular animal. I'd consider an animal 'tame' if it didn't try to eat me or run away; domestication involves much more. HenryFlower 14:11, 16 July 2006 (UTC)
Yeah. Your parrot is probably at most three generations from the wild and there is probably very little difference between his behaviour and that of his wild bretheren, aside from the fact that you've taught him to trust humans. --Kurt Shaped Box 18:21, 16 July 2006 (UTC)

EDIT: Just created a redirect from 'Hyacinth macaw' -> 'Hyacinth Macaw'. That should really have been there already... --Kurt Shaped Box 18:30, 16 July 2006 (UTC)

What is optimum rate of a having a rare treat to maximise pleasure?[edit]

I am very nutrition concious, and careful about my weight, but sometimes despite the guilt I allow myself to eat a small tub of ice-cream. I eat it all in one go.

This has made me think - what would be the optimum rate per year of indulging in such a treat to maximise my pleasure?

If I ate a tub a week then it would no longer be much of a treat as it would become routine and expected. The rarer the treat is, the more pleasure that treat gives.

On the other-hand, if I only ate it once a year then I wouldnt get as much total pleasure per year as if I ate it twice a year. Yet if I ate it too many times a year the pleasure would dull (plus more guilt).

So there must be some optimum number of eatings per year to maximise pleasure.

Anyone got any thoughts on what this number n per year would be, or how to determine it?

(Anyone like to have a bash at producing a mathematical model for the rareness/boredom and guilt tradeoffs?) --81.104.12.11 14:03, 16 July 2006 (UTC)

I'm pretty sure this is waaaaaaay too subjective to be quantified, but it should be amusing to see what kind of responses we can come up with... Isopropyl 11:50, 16 July 2006 (UTC)
Experimentation on this should be fun. How about getting a random number generator to tell you how long to wait? Thus the delay would never become routine. —Daniel (‽) 13:22, 16 July 2006 (UTC)
I had also thought that I could throw a dice (or is it 'die' singular?) and only buy if 6 came up. --81.104.12.11 14:03, 16 July 2006 (UTC)
Die is indeed the singular. You might also consider getting a die with more than 6 sides (they come in 4, 6, 8, 10, 12, and 20 that I've seen... probably there are others), if you want it to happen less often. But if you're anything like me, you may end up ignoring the die when you really want ice cream (and maybe that's ok), but what I've always wanted is a sort of safe that, once a day, you could try to open and it would randomly open with a pre-set probability, to prevent cheating. I'm weak willed :) Digfarenough 17:24, 16 July 2006 (UTC)
I think only you can answer this question. My own "system" (although I have never thought about it in as much detail as you just wrote) is loosely based on the time since my last indulgence and cravings. --Ginkgo100 talk · contribs · e@ 20:48, 16 July 2006 (UTC)
I agree that it's pretty personal, but I'll tell you my opinion anyway! ;-) I think the maximum satisfaction is to be derived from treating yourself when you've forgotten the last instance of being treated. Put another way, I think that you wouldn't derive more satisfaction from one treat a year than two, and it all comes down to how long it will take you to 'forget' your last experience (not actually forget what premium ice cream tastes like, but just to the point where - BTW I'm thinking and this is true for me right now - you can't actually remember eating the most recent tub you ate). This might be 3 weeks (the minimum amount of time necessary to develop a new habit or get used to the absence of something) to - I'd predict a maximum of - 2 months. As I mentioned, I also think 'habituating' yourself to not having the treat is part of the process too. But, to reiterate, I think once you have 'forgotten', your potential pleasure is maximised and waiting longer won't increase it.--Anchoress 21:29, 16 July 2006 (UTC)

biophyscics[edit]

'How do atomic force microscopy works?'

Type "atomic force microscopy" into the search box at the left hand side of this page. Click the "Go" button. Please ask here if you need more details. Weregerbil 15:08, 16 July 2006 (UTC)
Or type in "I'm just asking a homework question."

gemeology[edit]

how rare are gem diamonds?

See diamond. Does it answer your question? Weregerbil 17:01, 16 July 2006 (UTC)
Also, it's Gemology or Genealogy. Registrar

Diseases[edit]

How many diseases that affect only on women and that affect only on men?

See Sex and illness. Do you need an actual number? Weregerbil 17:00, 16 July 2006 (UTC)

Many if not most diseases affect males and females at different rates. However, the only diseases that affect only one sex are the diseases of the body parts possessed by only one sex, or diseases that are associated with an exposure to environmental agent or situation which gender role restricts to one sex. There are many diseases in both of these categories. alteripse 01:34, 17 July 2006 (UTC)

I believe there are genetic diseases carried only on the Y chromosome. Black Carrot 04:44, 17 July 2006 (UTC)
Good suggestion. While I can't think of any diseases of Y chromosome genes that are not diseases of sexual development (i.e., "a disease of the body part possessed by only one sex"), there are many X-linked diseases affecting only males. Also the syndromes of aneuploidy affect many body parts and only affect a single sex: XYY syndrome, XXY (Klinefelter syndrome), etc only affect males, while Turner syndrome, XXX syndrome, etc, only affect females. alteripse 04:50, 17 July 2006 (UTC)
The Y chromosome carries very little of functional importance, because, after all, half of the population doesn't have one. Instead, most gender-specific diseases are recessive and linked to the X-Chromosome, but they rarely affect females because they would need two copies of the gene to have the disease, one of which would have been inherited from the father. In some cases, this is impossible because of the nature of the disease doesn't allow a male to pass on his genes. There are, however, some examples of diseases caused by the Y-chromosome; see Y_chromosome#Chromosome-linked_diseases - Registrar

Units of Measure[edit]

What are the base SI / Derived units of measures for the following

II X-ray to candela conversion factor Candela per square metre, Decibel, Degree per second, Hounsfield unit, Line pairs per centimetre, Line pairs per millimetre, Illuminance, Milliampere second, Milligray, Milligray per square centimetre, Milligray per milliampere second, Milligray per second, Milliohm, Nanofarad, Microampere, Microgray, Transmission Kerma index (IEC 61223-3-1), Microgray per frame, Microgray per miliampere second, Microgray per second, Microlitre, Millilitre per minute, Conventional millimetre of mercury, Litre per minute, Revolutions per minute, Heartbeats per minute,

×Surendra Birje--Surendrabirje 16:37, 16 July 2006 (UTC)Suren

You could just look them all up (search box at the top left). I'm certainly not going to do all those for you. :) Also make sure to have a look at the SI article. There, you can find all the base units. Just 7 - isn't it a wonderful system? If you can't reduce a unit to these units, it's not a derived SI unit and you have to convert it. Of course, minutes need to be converted to seconds (60 of 'm) and a litre is 1 dm3 = 0.001 m3. The rest you'll have to do yourself. After all, this sounds like a homework question and we're not allowed to do that for you. DirkvdM 19:18, 16 July 2006 (UTC)

Emailing photos[edit]

Several friends of mine send me photos by email, but they are huge, typically over 3Mb each, and I have to load them into a picture editor and reduce them before I can view them. I know nothing about digital cameras and I don't know what software they use, and these people are not very knowledgeable about IT. Is there something simple I can tell them to do in order to reduce the size of their picture files?--Shantavira 18:15, 16 July 2006 (UTC)

You're best off asking them what type of software they use and then figuring it out for them. "Click X, click Y, click OK". There is no magic or automatic way to resize images. --Fastfission 18:27, 16 July 2006 (UTC)
Ask them to take pictures in a lower resolution (tell them to check the camera manual if they don't know how to do it). If they're knowledgeable enough to need a higher resolution, then I'm sure they'd know how to resize them. ☢ Ҡiff 19:05, 16 July 2006 (UTC)
No, that's never a good idea. It's not only the "knowledeable" people who need high resolution--if you "accidentally" take a very good picture, and you later want to make a print out of it, it'll be a shame if the print doesn't look nice simply because you set the resolution too low. --Bowlhover 23:50, 16 July 2006 (UTC)
Is the problem the file size (takes too long to download and your mailbox gets filled up pretty quickly) or the image size (doesn't fit onto your screen)? If it's the former, the best thing to do is to compress them (further) as jpegs. That is much better for the quality of the image. If it's the latter, I'm not sure what the problem is. Don't you have an image viewer like Kuickshow or such? It all depends on what software you use. And what operating system. If you need to convert images, most Linux distros come with the gimp. And MacOS is bound to have something like that too. Don't know about msWindows. DirkvdM 19:31, 16 July 2006 (UTC)
Windows has a free and handy tool for resizing images. Go to Microsoft's website and search for "Power Tools" then "Image Resizer". It will install a small application (yeah, yeah, MS haters!) that resized images. What your friends will need to do (they will be the ones to install it) is save the desired images to their computer (My Documents-My Pictures would be a good place), then right-click on an image's file name and select "Resize" from the pop-up menu. They have three choices, which are basically small, medium, and large. The image will be copied as a new, smaller image with the filename modified appropriately.
Here is Microsoft's Image Resizer:
http://download.microsoft.com/download/whistler/Install/2/WXP/EN-US/ImageResizerPowertoySetup.exe
I suggest that your friends resize their images to 1024 pixels by 768 pixels--640 by 480 is, by my standards, unacceptably low quality. --Bowlhover 01:03, 17 July 2006 (UTC)
File:Resize-1.JPG
MS Power Toy menu flyout
File:Resize-2.JPG
MS Power Toy Image Resizer
You have to install that? How primitive! DirkvdM 19:12, 17 July 2006 (UTC)

Why do some creatures live longer than others?[edit]

Sorry if this is a really obvious question but why is it that some animals live much longer than others - how is this 'decided'? I found my first (and oldest) budgie dead on the bottom of his aviary yesterday. He was at least 19 (he wasn't even a baby when I got him), which is a very good age for his species and he lived a good and healthy life (he must have hundreds of descendents now) - still, I'm really upset. I'd grown really attached to that little bird I can't help asking 'why?' and 'what's the deal with this?'. --Kurt Shaped Box 19:14, 16 July 2006 (UTC)

I'm sorry to hear about the loss of your budgie. Nineteen is quite old for this type of bird, so you were quite lucky to have him with you for so long, although I know this is small comfort. As to your question, the life expectancies of various animals typically vary by size, with larger animals usually having a longer life expectancy than smaller ones (this is why a budgie's life expectancy is about 10-15 years while a macaw's is nearly 100). An exception is dogs, in which the smallest breeds have a longer life expectancy than the largest. Another exception is seasonal animals, such as killifish, which have a life cycle similar to that of annual plants. Also see maximum life span. --Ginkgo100 talk · contribs · e@ 20:43, 16 July 2006 (UTC)
I knew he was knocking on and wouldn't be around forever but the funny thing about budgies is that they never look any older or behave any differently, so he never 'seemed' old. Most of my flock contains his bloodline - I actually have many of his great-great-great-great-great-(etc.)-grandsons and daughters in my aviary at the moment. I guess it's fair to say that he fulfilled his evolutionary purpose many times over... :)

Anyhow, does anyone know why it is that smaller animals don't generally live as long as larger ones? A matter of more delicate construction? --Kurt Shaped Box 21:18, 16 July 2006 (UTC)

I read somewhere that a species' life expectancy correlates quite closely with its pulserate- that you 'start out' with a certain number of heartbeats (the figure was 8 and lots of 0s) and the faster you use them up, the shorter your lifespan. Humans, however, live longer than they ought to by this formula. Whether this is true and if so why, I can't say. HenryFlower 21:21, 16 July 2006 (UTC)

This link gives a lot of correlations. [1] The only animal that can out-beat a human is a chicken! --Zeizmic 00:50, 17 July 2006 (UTC)

Wow. I never even knew that chickens masturbated. The things you learn at Wikipedia! JackofOz 01:37, 17 July 2006 (UTC)
*Coy girlish giggle* [2] ;) Black Carrot 04:42, 17 July 2006 (UTC)
In Thailand I once witnessed some ritual that involved killing a chicken and tossing it over the shoulder. A rooster walked by, saw a wonderful opportunity and jumped the dead chicken. So necrophilia isn't limited to humans either. DirkvdM 19:24, 17 July 2006 (UTC)
  • Life expectancy is a mix of multiple factors. I think one that wasn't mentioned yet is telomeres. They cap the ends of your chromosomes to stop the ends from degrading. I think it was that they became smaller with each replication because the proteins can't go all the way to the end. Anyway, once the telomeres wear off, your DNA is affected and you start dying (not neccesarily in a visible manner). I guess smaller animals have smaller telomeres. - Mgm|(talk) 23:39, 17 July 2006 (UTC)

Cornstarch vs Baby Powder[edit]

I use baby powder to keep my crotch area a little dryer because its so hot here. But recently I noticed corn starch in the same container right next to it in the market. Which one is more effective? Thanks

They'd probably work equally well for dryness. There are two things to consider: First, some baby powders have addtional medication in them to treat rashes and all that. Second, talc, the primary ingredient in baby powerders, has been tentatively linked to some cancers, as you can read in our talc article. If you're the cautious sort, you might want to look into it. --George 20:25, 16 July 2006 (UTC)
see "I've Used Cornstarch on my balls for years!" , by Ken Kesey, The Last Supplement to the Whole Earth Catalog," Portola Institute, 1971. (Reprinted in Ken Kesey's Garage Sale). He endorses corn starch, "keeps things sliding when you're in court, say, and can't unzip to let things air out." --GangofOne 22:54, 16 July 2006 (UTC)
The above quote is only approximate, based on my memory. In the interests of encyclopediatic accuracy, and thus so scholars may have confidence in the scholarly intellectual value of Wikipedia, I have located the printed original from March , 1971, which has no proper copyright notice and thus may be in the public domain. Ask a lawyer. On the inside back cover under 4 images of Mr Kesey demostrating application technique we read:
"I've used Cornstarch on my balls for years!" states noted author and theocologist, Ken Kesey. "Y' know how it is when you're swarthy anyway and maybe nervous like on a long freeway drive or say you're in court where you can't unzip to air things out, and your clammy old nuts stick to your legs? Well, a little handful of plain old cornstarch in the morning will keep things dry and sliding the whole hot day long. Works better than talcum and you don't smell like a nursery. Also good for underarms, feet, pulling on neopreme wet suits and soothing babies' bottoms. And it's biodegradable."
The above is not medical advice. For medical advice, seek the consul of a licensed medical testesologist or gynecologist. --GangofOne 04:21, 17 July 2006 (UTC)
That's quite an ambassadorial injunction, I must say.  :--) JackofOz 04:23, 17 July 2006 (UTC)

Python question[edit]

If I have a long number, say pow(2,199), how do I access individual digits in that number?

-convert it to a string and use a mid() function? -use some mod() functions?

Thanks .

(Disclaimer: I don't actually know Python, but the principle will be the same in any language.) You could do it by converting to a string and using mid(), but it's probably more efficent to do it mathematically: For a number x, you can get the ith (counting from the right) decimal digit by calculating , where is the floor function (for a non-decimal base, replace both 10s with the base b.) -- AJR | Talk 22:30, 16 July 2006 (UTC)
You can do this:
s = str(pow(2,199))
Individual digits of the result can be accessed as s[0], s[1], s[2], and so on. --71.246.9.190 02:14, 17 July 2006 (UTC)
>>> s=str(pow(2,199))
>>> r=list(s) 
>>> r.reverse()
>>> r = "".join(r)
>>> print r[0],r[1],r[2],r[3],r[4],r[5],r[6],r[7],r[8],r[9]
8 8 6 0 5 6 7 1 4 6

Ohanian 00:51, 18 July 2006 (UTC)


Thanks guys!

Kuru and prions[edit]

I'm doing a research project on the Kuru disease and I'd like to know what exactly prions do that cause the brain to get "spongy".

Now, from reading the Prion article in Wikipedia, I get that the PrP^Sc protein contains a lot more of the amino acid structure called "beta sheets" than the normal PrP^C proteins. Now assuming that HuPrP^Sc kuru protein is somewhat related to the PrP^Sc protein, these "beta sheets" allow the proteins to form insoluble fibrils called amyloid aggregations. How do these fibres cause problems? I'm only a grade 10 student, so I'd like a somewhat simplified answer so that I can understand what you are saying without having to research every word I don't understand. :)

I'd also like to know what exactly amyloid aggregations are. From what I can understand so far, they are structures formed by the prions that cause a heck of a lot of problems. Would I be correct? The article on amyloids in Wikipedia tells me that they are responsible for many neurodegenerative diseases, but it doesn't tell me how the amyloid aggregations cause the problems. Doing some more research on Wikipedia, I found that amyloid aggregations cause problems in people with Alzheimers by breaking down blood vessels. Does the same sort of thing happen in Kuru?

In addition, I got this picture of encephalopathies on the internet, but I don't understand which part of it is the actual proteins. Is it the white stuff? (http://w3.jouy.inra.fr/unites/vim/prion/histo.jpg)

I would really appreciate your help.

The amyloid is stained pink to red with congo red. Under a polarizing microscope, it displays an apple-green birefringence (which of course won't help on jpegs!) The white areas you allude to are vacant spaces - vacuoles - where brain matter once was. - Nunh-huh 23:10, 16 July 2006 (UTC)
Honestly, we don't really know exactly how the relationship between amyloid plaques and neurodegeneration works. There's actually some evidence that suggests plaque formation is a protective mechanism: a way for the body to package up toxic proteins and keep them from doing further harm. Some researchers now suspect that smaller, soluble protein oligomers (small clusters of protein) are actually the toxic species. The way in which amyloid diseases kill cells is very poorly understood. TenOfAllTrades(talk) 00:46, 17 July 2006 (UTC)

Headrush![edit]

Is there a scientific name for the "headrush" experienced during Orthostatic hypotension? Philc TECI 23:42, 16 July 2006 (UTC)

Yes, that's it. 71.132.139.12 04:51, 18 July 2006 (UTC)
Hm it seems to be, but Orthostatic hypotension is the blood pressure drop, whilst head rush is the experience. Its a bit like saying a heart attack and sever chest pains are the same, but there not really. Philc TECI 20:00, 18 July 2006 (UTC)