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December 19

Did anyone ever make a weird mathematical treatment of physics with extra dimensions of time?

Where every possible spacetime really exists, more than that universes just like ours except one electron was on the other side of the electron cloud at 10^61 Planck times exist (if you even looked at it at the wrong time (slightly before 10^61), you couldn't distinguish the universes anyway, even in theory, it's almost not even a different universe). Of course people make weird unfalsifiable, Occam's Law-violating or even debunked physics theories all the time, a theory existing doesn't mean that it deserves serious thought. Sagittarian Milky Way (talk) 00:30, 19 December 2014 (UTC)

Imaginary time. μηδείς (talk) 01:21, 19 December 2014 (UTC)

OK...the title here is a question - the answer to which is "Yes...several versions of String theory suggest multiple time dimensions." The rest is not. But to comment on what you have to say:

1. Certainly if the Many worlds interpretation of quantum theory turns out to be true, then many universes are seemingly (or actually) completely identical. There is no problem with that - if a quantum-mechanical event causes a universe to split into two parallel paths, then one of them can go on to have another event that perfectly undoes the first one - and now you have a pair of parallel universes that are utterly identical. This causes no specific problems - if the hypothesis is true, then there would be vastly more universes than there are atoms in our universe - there would be no shortage of them and no 'cost' to creating new ones. We could even imagine that there are an infinite number of them.

Isn't the many worlds universe be more like an "exploding cone-time" where the Big Bang is a point, BB+1 Planck time is x wide, the third Planck time is x*x wide, the fourth Planck time is x*x*x wide and so on? That is not usually what two dimensions means. In 2-D time with perpendicular axes the Big Bang would be a line at the left edge and universes that won't split from ours for trillions of years would start already separated. Sagittarian Milky Way (talk) 18:11, 19 December 2014 (UTC)

1. The many worlds hypothesis may very well be unfalsifiable. We define "the universe" as "all of spacetime and everything that exists therein, including all planets, stars, galaxies, the contents of intergalactic space, the smallest subatomic particles, and all matter and energy." So anything we could detect or measure about these "parallel universes" would make them be a part of our universe. So by the very definition of the word "universe", anything that happens in a different one in undetectable. For this reason, the many worlds hypothesis must seemingly be unfalsifiable. That doesn't mean that it's "false" - it just means that we may never be able to prove or disprove it.
2. Occam's Razor isn't a "law" - it's not even a hypothesis - and it's not always true. It's just a handy guide that you can employ when there are many possible explanations for something and you want to pick the most likely one. So, if I can't find my TV remote, it might have fallen behind the sofa cushion, or it might be that a team of crack commandoes from North Korea may have broken into my home and removed the remote just to be really REALLY sure that I can never watch "The Interview". In terms of the science, I may not be able to decide which of those hypotheses are true right now...but Occam's razor suggests that I should probably do the experiment of looking behind the sofa cushion BEFORE I contact Homeland Security. It should be called "Occam's Very Rough Rule of Thumb" or something.

I hardly gave any thought whatsoever while writing those two words, if I knew that wasn't a common name for the idea then I wouldn't bothered to Google Occam. I knew it wasn't utterly unable to be wrong. Sagittarian Milky Way (talk) 18:11, 19 December 2014 (UTC)

1. A "theory" (the scientific term, meaning something that's proven and widely accepted) does deserve serious thought. Most useful hypotheses (thing that we think are good explanations, but are not yet proven) are sometimes worthy of serious thought - and sometimes not. Many Worlds is a pretty good hypothesis that could certainly explain bizarre stuff like Schrödinger's cat - and is taken seriously by many reputable physicists. So I think it does deserve serious thought, even though it's not proven, may never be proven, and may very well be unfalsifiable.

But physics "theories" (in quotation marks) go all the way to "the sun is made of iron" and Time Cube. Even if no one with a degree in a relevant field takes it seriously (note that I didn't say that's the case) it might be easy enough to add the terms needed to make Einstein's theory 3+2 dimensional (I haven't studied the equations, I can't tell) but have little enough physics sense to take it seriously. Sagittarian Milky Way (talk) 18:11, 19 December 2014 (UTC)

Is it possible that stored memory could be misinterpreted as another time dimension?165.212.189.187 (talk) 16:43, 19 December 2014 (UTC)

No. --Jayron32 18:37, 19 December 2014 (UTC)

One recent proponent is Itzhak Bars who had an article in New Scientist some years ago. We have an article Multiple time dimensions. I remember reading a discussion of likelihood of multiple time dimensions in a popular science book (i.e. if there are Compact dimensions are they spacelike or timelike or both) a while ago, possibly The Road to Reality by Roger Penrose? JMiall₰ 10:59, 20 December 2014 (UTC)

Is the heart's valves made of cartilage?

I read the articles here and eventually I don't understand if yes or not149.78.45.16 (talk) 02:53, 19 December 2014 (UTC)

No. See cartilage and heart.--Shantavira|^{feed me} 12:03, 19 December 2014 (UTC)

Is it true that any tendon has two sides - one connected to muscle and the other to the bone or cartilage?

Is it true that any tendon has two sides - one connected to muscle and the other to the bone or cartilage? another sentence that I think about is that always tendon needs to be connected to the muscle or the bone. not? 149.78.45.16 (talk) 02:58, 19 December 2014 (UTC)

Wikipedia has an article titled Tendon which may be able to help you learn more about tendons. --Jayron32 03:56, 19 December 2014 (UTC)

There may be special cases (Patellar tendon), but the answer to your initial question is generally 'yes', as is stated in the first sentence in the lede of the article that Jayron32 linked to. --NorwegianBlue ^talk 23:38, 19 December 2014 (UTC)

how many people with gonorhea eventually go on to develop prostatitis?

close trolling by blocked sock
The following discussion has been closed. Please do not modify it.
Or maybe a better question to ask is, how common is acute prostatitis, and of those with it, how many test positive for gonorrhea? — Preceding unsigned comment added by 199.119.235.174 (talk • contribs) What's taking so long?Whereismylunch (talk) 4:20 pm, Today (UTC−5) Assuming it is not developing prostatitis you are in a hurry for, you can google "gonorrhea percentage prostatitis". μηδείς (talk) 21:26, 19 December 2014 (UTC) Hard to find an answer, compared to when I looked many weeks ago percentage of oropharyngeal cancer patients positive for hpv.Whereismylunch (talk) 22:27, 19 December 2014 (UTC) According to UpToDate [1], The pathogens associated with acute prostatitis reflect the spectrum of organisms causing cystitis, urethritis, and deeper genital tract infections (such as epididymitis). Gram-negative infections, especially with Enterobacteriaceae (typically E. coli or Proteus species), are the most common. In retrospective studies of men with acute bacterial prostatitis, such pathogens have been identified in positive urine cultures at the following frequencies: E. coli – 58 to 88 percent Proteus species – 3 to 6 percent Other Enterobacteriaceae (Klebsiella, Enterobacter, and Serratia species) – 3 to 11 percent Pseudomonas aeruginosa – 3 to 7 percent Sexually active men may have sexually transmitted urogenital infections, which also acutely involve the prostate, in which case Neisseria gonorrhoeae and Chlamydia trachomatis are important pathogens. --NorwegianBlue talk 23:29, 19 December 2014 (UTC) At what frequency has gonorrhoeae been identified in positive urine cultures?Whereismylunch (talk) 01:19, 20 December 2014 (UTC) I figured this was a troll when I saw he edited in a signature over the unsigned IP address, and he has been indeffed. μηδείς (talk) 03:35, 20 December 2014 (UTC)

HIV testing

I know about the window period for HIV testing, but (and I'm asking this question without much scientific knowledge so bear with my ignorance) is there a particular point at which testing will pick up HIV?

Am I right in thinking that HIV tests will test positive after seroconversion occurs? Is seroconversion the same as acute HIV infection (early HIV symptoms)? After the acute HIV infection, is the patient seroconverted and the HIV detectable?

What about during the acute HIV infection?36.224.250.37 (talk) 18:20, 19 December 2014 (UTC)

Seroconversion. μηδείς (talk) 21:17, 19 December 2014 (UTC)

"Seroconversion" occurs when the infected person produces antibodies against HIV antigens in sufficient amounts to be detected. Tests that detect the HIV virus itself will usually be positive a few days before seroconversion. There are tests that detect HIV proteins and tests that detect HIV nucleic acids. See Diagnosis of HIV/AIDS for details. According to that article, nucleic acid testing (NAT) appears to be preferred in the EU for blood donor screening (somewhat unclear in the article). I doubt that that is generally true, although it may be true in some EU countries (I know that it's true in Denmark). The EU blood directive [2] does not mandate the use of NAT testing for HIV. In Norway (which is not technically part of the EU, but which through the EEA agreement is more faithful to EU regulations than most EU countries), combined tests (that detect both HIV proteins and antibodies against HIV) are used in blood donor screening. --NorwegianBlue ^talk 23:03, 19 December 2014 (UTC)

What is the nature of the relationship between seroconversion and the acute HIV infection? Does seroconversion occur while a patient is having primary HIV symptoms (if any)?36.226.148.49 (talk) 04:33, 20 December 2014 (UTC)

The HIV/AIDS article gives the symptoms of the initial acute phase of the infection. Have you understood the seroconversion article? μηδείς (talk) 05:58, 20 December 2014 (UTC)

Relative concentration of Chitinase in various fruits

Chitinase#Presence in food says:

Bananas, chestnuts, kiwis, avocados, papaya, and tomatoes, for example, all contain significant levels of chitinase.

Where can I find the relative concentration of Chitinase in these and other fruits? -- ToE 20:08, 19 December 2014 (UTC)

I don't know, but this pdf would be a decent ref for that sentence if you care to add it [3]. SemanticMantis (talk) 20:35, 19 December 2014 (UTC)

If you are interested in chitinases as food allergens, this web search may be of interest. --NorwegianBlue ^talk 23:14, 19 December 2014 (UTC)

Thanks so far. The food-allergens.de page says: "almost 50% of these allergic [latex alergy] patients also show hypersensitivity to some plant foods, especially chestnut, banana, and avocado, but also to kiwi, papaya, tomato and others." I don't know if that is because the former three have a greater concentration than the latter, or because they have different forms of Chitinase, which I understand describes a group of enzymes.

The allergen.org site gives specific allergens, such as Mus a 2 from banana, a "Class 1 chitinase", and Ziz m 1 from Chinese-date, a "Class III chitinase", but it doesn't seem to give the typical concentrations in the food source and doesn't explain the difference between the chitinase classes. -- ToE 12:33, 20 December 2014 (UTC)

December 20

Tiny islands

Google Maps (I have no real data to back this up) makes it look as if there are many mountains in the sea of which just the top is above sea level. So if the sea level would go up a little, say 300 ft, many of them would disappear, where if it would go down a little, again 300 ft, a lot less new islands would appear. Is that true, and if so how come? Erosion perhaps? Joepnl (talk) 00:04, 20 December 2014 (UTC)

Yes, there are lots of different types of islands. Some are newly created by undersea volcanic activity, others are the remains of eroded rock, and yet others are mountaintops from before the last post-glacial rise in sea level. See New islands and Sea level#Changes through geologic time for a few details. I'm sure some experts here can add further to this reply. Dbfirs 00:14, 20 December 2014 (UTC)

Other relevant articles include seamount and guyot.--Jayron32 00:56, 20 December 2014 (UTC)

(edit conflict) When a new volcanic island forms, a thin ring of coral forms around the edges. The volcano becomes extinct (often cause the crust leaves the hotspot of the mantle that caused the volcano behind), the mountain erodes and/or subsides, leaving behind a coral reef on top of a submerged mountain. The corals cannot live where it's too dark (tens of feet or meters, it's one of those, I don't remember) and will die if they're not wet. But no problem, if they die from depth new ones build their exoskeletons on top of the dead ones until they reach the tide level and can't grow up anymore, so they are always right below the sea level if they've been there enough millennia. 100,000 years ago the sea level was 20 feet higher than now in one of the hottest periods in millions of years (though I think this would happen (if not double) if we burn the carbon till 2100 or something and then wait for the ice to stop melting (centuries), so not especially hot by 2014 standards), the highest sea level in at least 400,000 years and maybe millions (I don't remember), 100 Kyr is short enough that the coral reefs killed by the low sea level of the last ice age have not have time to be eroded away yet and are still there as islands. Sagittarian Milky Way (talk) 01:27, 20 December 2014 (UTC)

Also, it is often in the nature of land to be barely above sea level (wave and freak 5000 year hurricane created islands like Coney Island and the more well known Atlantic City island, river deltas, river islands, coastal wetlands.. Those don't look like mountains on Google Earth, though. Sagittarian Milky Way (talk) 01:38, 20 December 2014 (UTC)

• If the surface of the Earth were randomly bumpy, the greatest number of islands would exist when the sea covered half its surface (for a proof of this, ask at the math desk). If the sea level sank, so that more than half of the surface was land, more of the random islands would become part of the mainland. If the sea level rose so that more than half the random surface was covered with water, more islands would sink below the surface.
  

The Earth has two great differences: the ocean covers 71 percent of it, and its surface is far from random. So the question is an empirical one which I cant answer. But see Zealandia and Kerguelen Plateau for interesting reading. μηδείς (talk) 04:18, 20 December 2014 (UTC)

If Venus were terraformed and given an ocean would probably have to be made of comets) Earth would likely have almost 50% more land by percentage and many more islands (Venus has only two continents). If Mars was terraformed it would likely be only 33% water in one ocean and have few islands. Go figure. Sagittarian Milky Way (talk) 16:29, 20 December 2014 (UTC)

You seem to be assuming arbitrary water levels? Wnt (talk) 17:38, 20 December 2014 (UTC)

@Wnt, if anyone still cares, I was assuming that staying indoors when the weeks long days cause jet lag would be annoying enough, they wouldn't want depressing near-constant heat-shielding cloud on top of that (even if all the comets or moons hit on the side that increases spin the day will be long) So you would want to avoid deserts caused by too large landmasses. Deserts next to water cause the highest heat indexes on Earth. Thin air would be good for reducing the avg temperature of high latitudes, as is the low axis tilt, but a lot of water would be needed to reduce the day-night temperature differences. Do might as well just keep Ishtar Terra and Aphrodite Terra above water. I'm not sure if the tropical one would be habitable, maybe to genetically engineered rainforests? I would want low albedo = high land on Mars, and the thick greenhouse effect of extra GHGs should trap heat and keep the continentality from getting extreme. It also avoids wasting land and fills in the ocean to its original beachline. See: File:Mars_topography_(MOLA_dataset)_with_poles_HiRes.jpg and Oceanus Borealis. Sagittarian Milky Way (talk) 01:47, 23 December 2014 (UTC)

Were blacksmiths losing their hearing?

I'm not sure whether I'm in the right section of RD, my question is rather between history, trade and medicine. Traditional blacksmiths of the past were being exposed to constant metallic noise during their life, but did that make any impact on their hearing? Were they losing their hearing during their life? Do blacksmiths use any protection for their ears today?--Lüboslóv Yęzýkin (talk) 08:47, 20 December 2014 (UTC)

In the introduction to An Inevitable Consequence: The story of industrial deafness (if you google that title you will find an online PDF copy) Dick Bowlder writes "There are references going back over several hundred years to the fact that some noisy occupations - in particular those involving the hammering of metal - will cause permanent deafness or tinnitus. Tinsmiths in the middle ages had “ringing in the ears”. But the first authoritative reference was in 1831 when Dr Fosbroke, writing in The Lancet, states that "Blacksmith's deafness is a consequence of employment.” And yes, blacksmiths today use hearing protection [4][5] Richerman (talk) 11:13, 20 December 2014 (UTC)

See Google Books for Fosbroke's original article, and here for Bowdler's paper. Fosbroke cites Daniel Sennert (in Latin) for his own historical reference on the subject. Tevildo (talk) 11:17, 20 December 2014 (UTC)

Thank you both! My grand-dad (unfortunately he died long before my birth) was both a skilful blacksmith and a talented musician who played the button accordion. I wonder how these two activities could combine. Probably he played music deliberately as a compensation to his noisy work. Interesting how many blacksmith-musicians there were (and are).--Lüboslóv Yęzýkin (talk) 00:10, 21 December 2014 (UTC)

So, after a while a blacksmith's hammers and anvils would wear out ? :-) StuRat (talk) 00:31, 21 December 2014 (UTC)

Is not keeping bread in a fridge really a good piece of advice?

It is commonly stated (including in the WP article: Staling) that keeping bread in a fridge makes it go stale (or more precisely: speeds up the staling process).

This contradicts my own experience: I keep my bread in a fridge at between 0 and 5 Celsius. I keep it in the fridge to stop it going mouldy (or more precisely: to slow down the going mouldy process) and I have not experienced my bread going stale, (even if I keep it long enough to start going mouldy even in the fridge).

Some possibilities:

• it depends on the type of bread (though the advice I constantly come across does not refer to particular types of bread),
• the staling referred to is not something that bothers me.

I have come across one person checking for themselves [6] , but they used white baguette loaves from a local bakery, which is probably not the most commonly consumed type of bread (in the UK, and many other countries, at least).

The type of bread I am referring to as not seeming to go stale in the fridge is cheap supermarket own-brand, medium sliced, wholemeal, in a plastic bag with no holes, bought in the UK. Ingredients: Wholemeal Wheat Flour, Water, Yeast, Salt, Spirit Vinegar, Emulsifier (Mono- and Di- Acetyltartaric Esters of Mono- and Di-Glycerides of Fatty Acids, Sodium Stearoyl-2-Lactylate), Soya Flour, Rapeseed Oil, Preservative (Calcium Propionate), Palm Fat, Flour Treatment Agent (Ascorbic Acid).

I notice that some of these ingredients are mentioned as anti-staling agents in the Staling article.

Why does this issue matter? People might be wasting bread because they believe the advice about not keeping bread in a fridge, and thereby having it go mouldy. (Advice is often given that bread can be frozen instead, and not go stale or mouldy, but this is less convenient and so less likely to be done.)

Note that this is not a question about why refrigerating bread makes it go stale (I have found copious information about that), but whether it is really true and a significant effect for all types of bread, and therefore whether saying not to put bread in the fridge, without further qualification, is a good piece of general advice. FrankSier (talk) 12:58, 20 December 2014 (UTC)

I'm from the UK and my family doesn't keep bread in the fridge - not because of anything we've been told, but simply because we have a bread bin, and the fridge has other things in it which need to be kept in there. We do, however, keep bread in the freezer, then bring it out when we need it (thawing it out first, of course), and that has never affected the bread in any way. I think this idea of bread going stale when put in the fridge comes from people putting sandwiches in the fridge (sometimes half eaten), so, being exposed to the air, they will go stale (whether they are in the fridge or not). Putting cling-film over them helps to preserve the bread, in my experience. KägeTorä - (^影_虎) (Chin Wag) 17:52, 20 December 2014 (UTC)

@FrankSier: The Staling page is not well referenced, having only one footnote to a ten year old book, though the first rather technical external link is downloadable for free. It does say bread "... stales most rapidly at temperatures just above freezing" Perhaps the chemical composition of bread has changed in the last ten years, and this is no longer accurate? Then again, a quick Google turned up heaps of sites saying that bread does indeed go stale faster if stored in a fridge! By up to six times! [7]

• It certainly appears that the prevailing advice is to store bread at 'room' temperature. (or freeze it)
• Comment on mold. Totally personal OR, avoid touching the bread with your hands and you will get far less mold. You might want to try it, get a piece and put your thumb on it, then leave it to 'moulder'. There is a very high likelihood that you will get a thumb shaped patch of green.
• More OR, there are many types of bread and I have found that some types, IIRC unsliced wholegrain are more resistant to going stale (and to mould) Though often the mould gets the bread before the 'stale' (especially in humid summer weather as here in Australia. Ǝ 220 of ^Borg 18:03, 20 December 2014 (UTC)

• Wikipedia has an article on this! Retrogradation (starch) explains the temp effect. The solution is to buy that white plastic foam stuff from the mall that comes in plastic bags, often miss-labeled as bread. It has additives to ensure that it remains as tasteless and bland as the day you purchased it. Enjoy. --Aspro (talk) 20:10, 20 December 2014 (UTC)

Note that the type of refrigerator also makes a difference. Cheap frost-free freezer/fridge combo units periodically heat the freezer to drive off the frost, and that might affect the fridge compartment temperature, too. You want a stable temperature to retain moisture. Constantly changing the temp will tend to cause water migration, causing bread to either get stale or soggy (and probably moldy, too). StuRat (talk) 20:28, 20 December 2014 (UTC)

Linguistic tangent here — to the best of my recollection, this is the first time I have ever encountered the word "staling". Is it technical jargon among food scientists? Or maybe a UK thing? --Trovatore (talk) 20:15, 20 December 2014 (UTC)

Same here (Detroit). I would say "going stale". StuRat (talk) 20:24, 20 December 2014 (UTC)

Don't know if any of you folks have heard of a little amateur project called Wikipedia but they have an article on Staling :-¬ ) P.S. Stu, you forgot a “/” before 'small' in your last post. --Aspro (talk) 20:37, 20 December 2014 (UTC)

Thanks, but our article doesn't discuss the linguistic aspects of the term. I would guess "staling" is UK-English, while "going stale" is US-English. StuRat (talk) 21:05, 20 December 2014 (UTC)

How about verbification then? Or the American habit of turning a noun into a verb in order to avoiding having to learn correct English grammar.--Aspro (talk) 21:24, 20 December 2014 (UTC)

[8]? DMacks (talk) 21:28, 20 December 2014 (UTC)

No, StuRat, the verb "to stale" does not exist in British English with that meaning. I thought it must be American when I saw the article. Staling in British English means putting rungs on a ladder (or possibly urinating if you are talking about horses). Dbfirs 22:20, 20 December 2014 (UTC)

Then what is it, Australian English ? Wiktionary lists it, but not where on Earth it's used: staling. StuRat (talk) 22:27, 20 December 2014 (UTC)

@StuRat: I haven't head the term in Oztralia either, so not common Oz-English either. Definitions of terminology are important though, see [9]
Oh, here's what a google for "staling" turned up, [10] appears it is a baking industry technical term. 220 of ^Borg 05:22, 21 December 2014 (UTC)

I was wrong to say that it doesn't exist, but it's certainly not used in modern British English. The OED has a sense "To grow stale; get out of fashion, become uninteresting" with a couple of cites from the nineteenth century. I'm puzzled to understand why Wikipedia has an article that doesn't use modern English. Merriam-Webster has "to become stale" but, from the reactions above, I deduce that the verb is as rare in America as it is in the UK. Google Books seems to indicate that the verb is used of bread by food scientists, though many of the authors have non-English surnames. A couple of authors with English surnames have published books in America with this usage. Google ngrams seems to indicate that the word is used in both American and British English, but is similarly rare in both. Perhaps it's just restricted to food science? Dbfirs 22:50, 20 December 2014 (UTC)

I suspect that the reason for the article name is that the alternative "Going stale" is an unusual form for an article name. StuRat (talk) 23:21, 20 December 2014 (UTC)

Staleness would be a much better article name, IMO, and the redirect already exists. I was only aware of the equine usage until now - thanks to Dbfirs for informing us of the ladder usage. Should this go to WP:RM? Tevildo (talk) 23:44, 20 December 2014 (UTC)

Ironically, the ladder usage is not the latter usage. StuRat (talk) 23:49, 20 December 2014 (UTC)

"Staleness"? don't be silly. Hale is to health as stale is to stealth. μηδείς (talk) 00:34, 21 December 2014 (UTC)

...and wale is to wealth ? :-) StuRat (talk) 00:40, 21 December 2014 (UTC)

Don't be silly, that is as weal is to wealth. μηδείς (talk) 05:40, 21 December 2014 (UTC)

@Aspro: Our OP actually mentions the Staling page in their post, about 'para' 6. Concur about the mislabelled 'foam'. A major supermarket here (Oz) got taken to court for advertising their 'foam' as "fresh bread" when it had actually been partly baked up to 6 months before! [11] [12]. 220 of ^Borg 05:22, 21 December 2014 (UTC)

FrankSier On the "Bread and the technology of bread production" webpage, 'Section 3.3. Staling of bread' says

"Storage temperature is an important factor to be considered in any discussion of bread staling. Staling becomes more rapid as the temperature of storage is reduced from room temperature to 35°F. Below 35°F., staling becomes slower as temperature is lowered, until at 0°F. [frozen] it is very slow, and bread products will keep for months without apparent staling." [13] www.classofoods.com

Nb. 35 °Fahrenheit =1.67 °Celsius. So I hope that helps, though it apparently contradicts a lot of websites and the earlier quote "... stales most rapidly at temperatures just above freezing". Keeping your refrigerator at a constant say 1.0 °C is likely to be a problem, which might be why conventionally people are saying to not put bread in the fridge to keep it 'fresh'. Likely it will either be slightly too warm or freeze. The page also gives technical descriptions of the staling process that may be easier to follow than some of the scientific papers I linked to earlier. 220 of ^Borg 05:22, 21 December 2014 (UTC)

A to D s

What sort of A/D s are used in GHz sampling rate digital scopes ?--86.169.152.43 (talk) 13:31, 20 December 2014 (UTC)

Fast ones? The usual suspects (Analog Devices, Maxim, TI) all sell ADCs in that sort of range. The exact model used in a particular scope will generally be commercially sensitive. Tevildo (talk) 19:34, 20 December 2014 (UTC)

David L. Jones does a teardown of two Agilent scopes in these YouTube videos - the 3000 series and the incredibly expensive 90000 series. You can search his site for teardowns of different scopes and other pieces of test and analysis equipment. -- Finlay McWalterᚠTalk 19:46, 20 December 2014 (UTC)

Could fat tissue be a beneficial cancer?

Naybe the ancestral version of the fat cell was a more harmful cell, and it evolved to be more beneficial? Thanks.2601:7:6580:5E3:7CBD:D2E0:7058:C21D (talk) 18:00, 20 December 2014 (UTC)

Neigh be my answer to that possibility. Why would you think that ? StuRat (talk) 20:30, 20 December 2014 (UTC)

• Fat cells aren't an infection, they are cells which develop normally in various differentiations from the body's stem cells, originating with a single fertilized egg. See also cell type, lipoma, and liposarcoma. Under the article cell type expand the mesoderm] section, you will see that fat cells (Lipoblast → Adipocyte) and muscle cells differentiate from the same progenitore as bone and cartilage cells. μηδείς (talk) 20:51, 20 December 2014 (UTC)

As explained in the article, adipocytes famously don't replicate under most circumstances, including weight gain. This actually puts them at the far end of the spectrum from cancer cells that undergo uncontrolled replication. (of course, liposarcomas do manage to replicate, or they wouldn't be cancer) Wnt (talk) 23:53, 20 December 2014 (UTC)

adipose tissue excretes estrogen and the latter appears to be a risk factor for a number of cancers. I believe overweight people are more susceptible to the latter. --AboutFace 22 (talk) 23:30, 21 December 2014 (UTC)

Could slow-growing cases of prostate cancer be beneficial in some cases?

Note:i'm not asking about if a gene that causes or predisposes to prostate cancer also has beneficial effects. I mean does the cancer it self help in some way, for example, like kicking in increased ability of sperm to impregnate.I suspect a counterargument will be that it occurs at advanced age that we haven't until the last few thousand years survived to, so we haven't had time to evolve to make it serve a purpose. But it could have been triggered at a younger age back when we lived less long. thanks.Rich (talk) 18:23, 20 December 2014 (UTC)

I doubt that, but I've noticed that organs which change their function during our lives are quite prone to cancer and/or benign tumors. This would include our reproductive organs and female breasts, which change during puberty and again during pregnancy. They all have a built-in design to "wait until you get the signal, then grow rapidly", so it's not that surprisingly that the "wait until you get the signal" part gets ignored at times. StuRat (talk) 20:36, 20 December 2014 (UTC)

The genes in prostate tissue that are blamed for cancer are the result of natural selection, thus likely (though not absolutely certainly) beneficial. (An example of why they wouldn't be is if environment has changed or if there has been rapid selection for change at some other site in the genome that makes their present form maladaptive) Now as prostate cancer runs through the gamut of the Gleason Grading System, it gradually goes from being pretty much harmless (except by implication of what will happen) to outright dangerous; this requires mutations that benefit the individual cells but are definitely not part of the starting genome. You can argue that the genetic code that makes such mutations possible is also selected for; but whether that makes these mutations 'part of the plan' is sort of a philosophical question. Like a lot of theoretical questions in biology, it seems to become something of a mirage the more closely you look at it. Wnt (talk) 00:00, 21 December 2014 (UTC)

Re: "The genes in prostate tissue that are blamed for cancer are the result of natural selection, thus likely (though not absolutely certainly) beneficial." By that logic most genetic diseases would be beneficial. The sickle-cell gene is one of the few where this seems to be the case.

Mutations naturally occur, some of which cause genetic diseases. If they prevent reproduction, then they won't be passed on, but the same mutation can always recur. Since prostate cancer often occurs late in life and is fatal, if ever, even later still, there wouldn't be much evolutionary pressure to prevent it. StuRat (talk) 00:06, 21 December 2014 (UTC)

What's the top of the Gleason scale labeled ? "To the Moon, Alice". :-) StuRat (talk) 00:08, 21 December 2014 (UTC)

Well, for example, metformin appears to reduce the risk by turning down the production of c-MYC protein. [14] The prostate could have evolved to have lower levels of c-MYC on its own, without prompting. Now, does that mean that there is a compensating advantage, maybe the man produces more nutritious semen that puts more of a spring in the step of his spermatozoa? Or does some aspect of the modern diet of processed food or endocrine disruptors have toxicity that metformin reverses by the same means as it tends to oppose high blood sugar? Or is it some unintentional negative aspect of the continual rapid evolution of sperm in competition with other males? Well, if I looked it up harder on PubMed I could likely find out, but for purposes of discussion here, well, the point is, it could be a number of things. The point is, the organ doesn't come ready made to be cancer proof as its only priority, or else prostate cancer would be a lot less common - and by extension, it is possible to look for treatments that will reduce the risk, though there may be unintended side effects. Wnt (talk) 00:33, 21 December 2014 (UTC)

Electrical wiring – wrapping electrical tape around swtiches and receptales

Is wrapping electrical tape around switches and receptacles (inside electrical boxes) required, recommended, or prohibited? I've seen wiring done either way, i.e. with and without taping. I've done some searching; it seems that even among electricians there's no clear-cut answer. Many seem to be of the opinion that it's unnecessary, but some say it may be beneficial sometimes. Does the National Electrical Code say anything about the practice? What is the common/recommended/prescribed practice in other parts of the world? Thanks. --173.49.11.192 (talk) 19:44, 20 December 2014 (UTC):

Visitors to the US often suffer a culture shock. On the one-hand everything’s all hi-tech, then on the other-hand, the electrical practices and mains power quality are third world. This is a UK site on DIY: Electrical connection--Aspro (talk) 20:26, 20 December 2014 (UTC)

It seems like it could be counter-productive, to me. Specifically, it could act as a thermal insulator, allowing the wires to overheat, especially if there's an intermittent connection inside the box. Also, I don't expect electrical tape would last for decades, and once it gets old, then what do you do, open up all your walls and replace it ? StuRat (talk) 20:41, 20 December 2014 (UTC)

??? There is no thermal insulation issue at all. If you have an intermittent connection you have bigger problems, the tape certainly won't hurt. And yes, the tape will last for decades, but it doesn't matter - the tape is really only for the 5 minutes when you put the outlet back in the wall, and you are working live, otherwise you don't need it. Ariel. (talk) 20:19, 21 December 2014 (UTC)

I disagree with you there. Especially in old homes, they specifically tell you not to add blown in insulation, as this can cause the wires to overheat. Wrapping electrical tape around everything is sure to add some thermal insulation, even if just by blocking air flow. And yes, if you are aware of an intermittent connection, you should have it repaired, but not everybody is aware in time to prevent a fire, or can afford to have it fixed. (I have an intermittent connection in the bathroom overhead lights of my 1920's house, and, not wanting to pay an electrician hundreds of dollars to rip open my stucco ceiling to make repairs, I just disabled them at the wall switch and put a floor lamp in that room.) StuRat (talk) 15:38, 22 December 2014 (UTC)

The US home improvement show This Old House has a video about this. The wrapping with electrical tape is shown beginning at minute 2. I think the thermal insulation issue would be minimal for the method shown in the video; it isn't "wrapping electrical tape around everything". Personally, I think I'd rather have my circuit breaker trip if some stray piece of metal touched one of the hot screws, rather than having a single layer of old electrical tape provide partial protection. Jc3s5h (talk) 16:30, 22 December 2014 (UTC)

I'll second Aspro's answer. The question amazes me. Required? No. Reccommended? Not in this neck of the wood. Prohibited? Possibly, though there are things that are so ridiculous, that no-one will contemplate makings laws explicitly stating that they are prohibited. Dangerous? Hmm, it depends. I'd guess that it usually isn't, except when it is. Clearly difficult to regulate. Third world? Definitely. --NorwegianBlue ^talk 21:07, 20 December 2014 (UTC)

Thanks for the replies so far. About the comment that US electrical practices look third-world to visitors, I'm not sure about that. People here are not dying in droves in electrical fires or of electrocution. I take that as empirical evidence that the electrical practices here are at least reasonable. On the comment that there are things so ridiculous that no-one would contemplate making laws explicitly against them, my belief is that if something is ridiculously dangerous, it will be prohibited under some general rules, if not detailed, specific ones. --173.49.11.192 (talk) 22:10, 20 December 2014 (UTC)

Yes, beyond a certain point more safety regulations may actually make things less safe. For example, if you require smoke detectors that are so sensitive they go off every time you cook, then people will disable them and be less safe. StuRat (talk) 22:22, 20 December 2014 (UTC)

"people are not dying in droves in electrical fires"...oh, some *on*. It took me about 60 seconds to fact-check your comment (something which you should have done before making it). the ESFi report for 2014 says: "In the United States, 50,900 fires each year are attributed to electrical failure or malfunction, resulting in 490 deaths and 1,440 injuries. Arcing faults are a major cause of these fires."...is 490 per year a 'drove'? I think so. In the UK, there were 25 deaths due to electrical fault fires in 2012. The US population is five times larger than the UK, but still, that suggests that deaths in house fires due to electrical faults are three times more common in the USA than the UK...and that's despite the fact that the US supply is only 110 volts rather than 240 volts. So, the US standards clearly aren't "reasonable" - I think the word "terrible" would be a better choice! Sorry, User:173.49.11.192 you could not be more incorrect. SteveBaker (talk) 00:10, 21 December 2014 (UTC)

There could be other reasons for the difference, such as a larger portion of people living in poverty in the US, who can't afford to keep the gas on, so end up using iffy electrical space heaters, instead. I would guess deaths from kerosene heaters are also higher in the US, for the same reason. StuRat (talk) 00:36, 21 December 2014 (UTC)

There's also a much higher occurrence of wooden or wood-shingle construction in the US (at least from my familiarity with CA and MA homes) than the UK (where essentially no-one lives in a wooden building). Postulating the same incidence of electrical fires between the two, you would expect a higher death rate among the people in the wood buildings than the people in the brick buildings. So a higher death rate from electrically-started fires does not necessarily indicate more dangerous electrics, but may indicate more inflammable houses. -- Finlay McWalterᚠTalk 01:11, 21 December 2014 (UTC)

I didn't look up the statistics when I made my comment. If your figures are correct, the UK is doing significantly better than the US in terms of preventing electrical fire deaths. However, and not to make light of the personal tragedies behind the statistic, I won't call 560 deaths per year among a population of 300+ millions "dying in droves". By comparison, the number of deaths from road accidents dwarfs that figure, and the risk of road accidents is something that people routinely tolerate. --173.49.11.192 (talk) 00:58, 21 December 2014 (UTC)

Well, it's a matter of cost-effectiveness. Making cars significantly safer is usually difficult & costly compared to the cost of a car. When we do find a measurable improvement (such as rear-view cameras, and tire pressure sensors), the law does change to force those improvements to become universal. Mandating improved house wiring standards would make an utterly negligible percentage difference to the cost of a house. That said, have you heard the kerfuffle about faulty car airbags - which have only caused maybe 6 deaths and 130 injuries? Government is holding inquiries and all manner of remedies have been proposed. But everyone is silent about the 4x larger death rate from electrical faults. It really doesn't make a whole lot of sense. SteveBaker (talk) 01:56, 21 December 2014 (UTC)

I think the airbag deaths are considerably higher, they just are going slow on "processing" the claims so it doesn't seem as bad as it is. And a safety device blasting shrapnel into your face seems a lot worse than one which simply fails to stop a fire from spreading. The first is causing death or injury, while the second is only failing to prevent it. StuRat (talk) 07:24, 21 December 2014 (UTC)

I thought this discussion was about poor electrical practices leading to faults which may cause fires? When did it become about stuff which fail to stop a fire from spreading? Nil Einne (talk) 12:23, 21 December 2014 (UTC)

I was referring to the wood construction of houses in the US, with no corresponding safety feature required, like sprinklers, which allows electrical fires to spread and become more dangerous. This was part of my explanation for why exploding airbags are more of a concern to the public than house fires. StuRat (talk) 15:27, 22 December 2014 (UTC)

It was suggested above that 110 V is safer than 240 V. This may be true for the electrocution risk, but the reverse is true for the fire risk. Fewer volts means more amps to deliver the required watts. More amps means more heating of the wiring. That's why in the UK ELV (12 V) halogen downlighters are more strictly regulated than 240 V ones. --catslash (talk) 16:32, 21 December 2014 (UTC)

Steve, You are mixing old installation with new. The new boxes and outlets are very safe, but the US has a lot of old houses, and it's mostly those that have issues. If everyone had the money to upgrade there would be much fewer problems. So it's not that people ignore it - it's that it takes a long long time for upgrades and improvements. Ariel. (talk) 20:34, 21 December 2014 (UTC)

Going back to the original question, does anyone know if the NEC has anything to say about the practice of wrapping electrical tape around switches and receptacles? --173.49.11.192 (talk) 17:08, 21 December 2014 (UTC)

It's completely unnecessary, but many people do it anyway. The worry is if the outlet moves in the wall it might contact the box and short, (or if you want to work on it live, it's easier if it's covered). If you have to work with old boxes, the threads for the screws are worn sometimes, but the outlet might move and touch, but it's definitely not necessary with new boxes. If you plan to work on it live, then you need the tape when you put it back in the wall. In short: If you are working live, do it. If not, then with new stuff don't do it. If you have 100 year old electrical boxes then consider it. Ariel. (talk) 20:19, 21 December 2014 (UTC)

• My understanding regarding fires in American homes due to electricity is that it is in no small part caused by the abortive switch from copper to aluminum wiring (and back to copper) in the second half of the last century and homes with hybrid wiring, which causes corrosion and heating and fires due to the resulting resistance. This article mentions the issue.

Why does running water cause the need to urinate?

Why does the sound of running water cause a person to need to urinate? Or is that just an urban legend? Thanks. Joseph A. Spadaro (talk) 23:50, 20 December 2014 (UTC)

I think it's real. See mirror neuron. (A zoo moved it's water fountain by the bathrooms and added a plaque saying it was relocated there "due to it's inspiration effect on small children".) As for why this might have evolved in humans, a group of people traveling on foot would stay together and make better time if they all stopped to urinate at the same time. They would also be harder to track by predators, such as wolves, than if they left small puddles of urine every mile. StuRat (talk) 23:52, 20 December 2014 (UTC)

You might find your answers in our article Classical conditioning. I have the same problem when some post a question about diets and it reminds me that its time to make sure that the food in the fridge is not getting out of date (well that's my excuse) and if someone asks about sex, the wife suddenly remembers she promised to pop over and see her mother.--Aspro (talk) 00:01, 21 December 2014 (UTC)

OR alert! - In later life I have found that when I run the tap to do the washing up I usually need to go for a pee - maybe it's to put off doing that boring job! I used to think it was just the power of suggestion until a veterinary friend of mine told me that the best way to get a cow to urinate, so you can get a urine sample, is to run a tap. Richerman (talk) 01:10, 21 December 2014 (UTC)

There's also scent marking in other mammals, such as dogs, which try to urinate to stake their claim whenever they detect urine from another animal. Perhaps we inherited a remnant of that behavior. StuRat (talk) 02:47, 21 December 2014 (UTC)

December 21

First date similarity to job interview

Is there scientific basis when people say that a first date is exactly the same or similar to a job interview

In what ways are they supposed to be the same? (It can't be every possible way--I don't think many people submit a resume before going on a first date.) --173.49.11.192 (talk) 01:04, 21 December 2014 (UTC)

(e/c)It doesn't sound like the sort of thing scientists would spend much time on. Not much grant money in it. Typing first date interview in Google, brought up a bunch of hits with some explanations, such as this one. Matt Deres (talk) 01:05, 21 December 2014 (UTC)

Strength of 3D Printer Plastic

They printed a wrench on the International Space Station. For the printer and source material they use for that printer that they have there, what's the spec on the shear stress a wrench made with it is likely to be able to take before it bends and breaks? 75.75.42.89 (talk) 02:30, 21 December 2014 (UTC)

I can't give you numbers, but I can say that the printer, designed by Made in Space inc., "uses an extrusion based method that layers hot liquefied ABS plastic to build a defined object". So they're in the envelope of what acrylonitrile butadiene styrene can do. -- Finlay McWalterᚠTalk 02:59, 21 December 2014 (UTC)

Yeah - but this is more of a test than an effort to make a useful tool. They actually plan to ship the wrench back to earth as soon as possible to test it's strength compared to one made on an identical machine here on earth.

But there are 3D printing technologies that produce really strong nylon parts - and laser-assisted metal sintering can produce metal parts in several useful metals. These are early days for zero-g 3D printing and because most (all?) normal 3D printers rely on gravity, it'll probably take many iterations of this technology before they can use it "for real".

In many respects, 3D printing in space is actually easier than here on earth. The need for "support materials" in earthly 3D printing is reduced or even eliminated in zero-g - and without the effects of convection on heat flow, it may be easier to control some kinds of materials.

SteveBaker (talk) 07:28, 21 December 2014 (UTC)

The article describes it as a "ratcheting socket wrench". Do we know if it functions as such, or does it just have the exterior resemblance of of a socket wrench? If it truly ratchets, do we know how many parts it is comprised of, what assembly was required, and whether any surfaces need post-printing finishing? A typical ratcheting socket wrench is composed of many parts, including bearing and springs, although I could imagine an ersatz, non-reversible (or perhaps double-sided, reverse by flipping), plastic wrench with only two pieces which snap together. -- ToE 12:59, 21 December 2014 (UTC)

See for example this article, which says the wrench consists of "...a sequence of 21 prints..." that resulted in "...a working socket wrench complete with ratchet action...". As an aside, there are a few simple ratchet wrenches over at Thingiverse that shows ways to make one with fewer parts. WegianWarrior (talk) 13:08, 21 December 2014 (UTC)

Thanks WegianWarrior. It's nice to hear that the thing actually ratchets. FWIW, it's not clear that that tool itself took 21 prints. Instead, it appears to have been amongst the items manufactured during a sequence of 21 prints. "It also marks the end of our first experiment – a sequence of 21 prints that together make up the first tools and objects ever manufactured off the surface of the Earth." -- ToE 17:50, 21 December 2014 (UTC)

Made in Space's blog entry gives some more details: "The ratchet was designed as one print with moveable parts without any support material. The parts and mechanisms of the ratchet had to be enclosed to prevent pieces from floating in the microgravity environment." and "The ratchet took 4 hours to print ...". It also has a detailed image of the a copy printed on earth, showing that the handle is labeled "3 in-lb"-- ToE 12:34, 22 December 2014 (UTC)

I wonder how enclosed interlocking/ratcheting parts were made separately without support material without getting stuck together during creation. 75.75.42.89 (talk) 13:03, 22 December 2014 (UTC)

My impression is that it was made from a number of separate parts that snap together somehow. This is entirely feasible. Also, you may not need much in the way of support materials in zero g. If I was tasked with making it in one piece - I'd have a very thin piece that would be extruded just to prevent the parts from drifting around during printing that could maybe be designed to simply snap the first time any significant amount of force is applied to the ratchet, leaving all of the moving parts free thereafter. With that approach, there would be no loose parts and no need to actually assemble it. But I have no way to know whether that's what they actually did. I think it's a shame that they haven't published the files they used for printing it. I'm sure a LOT of 3D printer owners would love to take a shot at making it. SteveBaker (talk) 18:29, 23 December 2014 (UTC)

I see, kind of like how plastic model car/airplane/whatever pieces are held to a plastic frame in the kit and meant to be disconnected. 75.75.42.89 (talk) 22:14, 23 December 2014 (UTC)

Physics in the movie Gravity

I just finished watching the movie Gravity. I was surprised that it actually portrayed the physics relatively realistically compared to other Hollywood films, but there was one particular scene that I found a bit odd. When Sandra Bullock's and George Clooney's characters arrive at the International Space Station using Clooney's MMU, their velocity relative to the station is too great and they have only a limited amount of fuel left to both correct their course and slow down enough to grab onto the external handles. Because of the bumpy landing neither character get a permanent hold, but Bullock's foot is tangled in some ropes while she grasps a tether that keeps Clooney suspended away from her. If I didn't describe that very well it looks something like this:

0[ISS]0-----------------8[Bullock]8--------------C[Clooney]C

Now at this point with both the ropes and the tether pulled tight and all of the objects at rest with respect to each other, as I see it there is no force on Clooney or Bullock and she should be able to reel his tether in and climb up the cables to the ISS. But instead of that Clooney makes some bizarre statement about him pulling her with him and ends up letting go and flying off into space. Is there any possible force that would have been causing him to drag her and then push him off into space once he let go? 139.195.41.154 (talk) 11:57, 21 December 2014 (UTC)

If the tether is pulled taut, there will be some pent-up potential energy in the tension of the tether, like a rubber band pulled taut. Being at "rest" may mean that all forces are balanced, but it doesn't mean that all energy is nil. Just like a stretched rubber band can be motionless and under balanced forces, when one end is let go, the other end flies off in the other direction. Clooney's character was screwed either way: If the line holding Bullock to the ISS broke, the both of them would be pushed out into space. If the line between Clooney and Bullock broke, Clooney drifts out into space, and Bullock drifts towards the ISS. He's a goner either way, but by letting his end of the rope go, he saves her. --Jayron32 14:14, 21 December 2014 (UTC)

I also thought that scene was a terrible exception to a very good movie. It looked like Clooney had reached the end of his tether, was motionless in space, but some malignant ongoing force was hell-bent on pulling him away as a plot device. It should be apparent that once Clooney was truly motionless relative to Bullock his inertia could not add additional tension to the tether between them, and once Bullock was truly motionless relative to the shuttle the tension on her tether couldn't increase. Now there are a hundred ways you can try to salvage the physics by saying that X wasn't really motionless, the cables were about to slip, the tether was unravelling like the rope in a Western cliffhanger, there was a leak in the jetpack, there were extra dimensions of spin and revolution that weren't immediately obvious, whatever... but the scene just didn't carry over that message to me as a viewer. It didn't feel right. Wnt (talk) 16:28, 21 December 2014 (UTC)

Forgetting for the moment the truly appalling acting, that film was marred by continual glaring physics errors. To move from a Hubble orbit to an ISS orbit to a Tiangong orbit will take enormous amounts of delta-V, certainly not possible the way it was depicted. MMU from Hubble to ISS? Please. For a film claiming to realistically depict spaceflight, it was deeply disappointing. Fgf10 (talk) 19:40, 21 December 2014 (UTC)

• That is not a physics error, it's a "geography" error. They are simply pretending that those satellites are all in similar orbits. --65.94.50.4 (talk) 02:01, 22 December 2014 (UTC)

I don't know that they ever claimed 100%. They had to take more than a little dramatic licence to make it happen. Mingmingla (talk) 23:56, 21 December 2014 (UTC)

I could excuse this because we can't rule out (well, at least not with certainty) that one or more satellites might have been moved prior to the events depicted. Of course, that would be unlikely to actually be done... Wnt (talk) 01:13, 22 December 2014 (UTC)

This "strange" force is called tidal force and can be quite strong is the rope is long enough. Ruslik_Zero 20:50, 21 December 2014 (UTC)

It's not at all difficult to calculate. Assume a tether 650 m long. Picked out of the air as one ten thousanth the distance to Earth center. Inverse square law, the g differential is 0.0002 which means 100 kg George is being pulled by 20 grams force. Yeah, I know grams are not force. So, if he's strong enough to pick up a pencil on Earth, he's strong enough to pull himself up and join Sandra. And if the cable is a lot less than half a mile, then it's a lot less force. Grade for the movie as lesson in orbital mechanics, B. That is, 'way above average, given the miserably low standards of Hollywood in this regard. Jim.henderson (talk) 21:12, 21 December 2014 (UTC)

It's been a while since I saw the movie, but the way I remember that scene was that there wasn't enough strength in the ropes to bring both of the two characters to a stop (relative to the station); they were starting to part or untangle or whatever, and the two people were still moving. If so, there is no problem; Clooney lets go and the ropes are strong enough to stop one person. Does the scene really show them coming to a stop, or are people being fooled by perspective or something? --65.94.50.4 (talk) 02:07, 22 December 2014 (UTC)

Here's the scene. I think this counts as fair use from our perspective, if not the Youtube uploader's. There's a moment early on at which the rope holding Bullock and Clooney jerks and they seem to come to rest relative to the station. Seemingly they should then have bounced back and started drifting toward each other. But later shots (especially the long shots) seem to show them both drifting away from the station again, at a constant distance from each other, with the rope between them still taut for some reason. When Clooney lets go he immediately "falls", the rope goes slack, and Bullock starts moving rather rapidly toward the station. It's not a tidal force—there's only about 6m of rope between them, and ~20m from Bullock to the station, and anyway the rope is oriented tangentially to Earth, not radially, so the tidal force would bring them together, not apart. There's not enough rotation for it to be a centrifugal force. And of course no gravitational/fictitious force could pull one person toward the station and the other away. Maybe it was magnets. -- BenRG (talk) 04:17, 22 December 2014 (UTC)

Or was there any rotation involved (both of them revolving around ISS)? Was it supposed to be the centrifugal force that was pulling JC away ? (In that case, the rope should have wound round the ISS). I don't recollect the mention of rotation in the scene, though - WikiCheng | Talk 12:09, 22 December 2014 (UTC)

With particular reference to the OP's question: [15]. And some other sources representing how the film became a bit of a whipping-boy for physicists, engineers, astronauts and other relevant experts in the wake of its original theatrical release: [16], [17], [18], [19], [20]. But for my money, it was comedian Louis C.K. who struck on one of the more glaring oddities that make it hard to suspend disbelief and follow the narrative: starting at 0:47. Snow talk 23:25, 22 December 2014 (UTC)

These are all valid complaints. But watching the movie, I found myself tending to rationalize them all away with the same thing: I kept thinking that this had to be fairly far in the future. The various old hardware hanging around was more for historic interest than cutting edge science, propellant had become much cheaper (I was thinking of an orbital skyhook, not a true space elevator but capable of assisting loads to greatly reduce cost), and, yes, even reluctant astronauts were being pulled into service. (Though the endless parade of people succumbing to the much more mundane "light grenade" lure of Mount Everest does admittedly cast doubt on the idea that we'd ever run out of people looking to be put at hazard) Wnt (talk) 21:39, 23 December 2014 (UTC)

Not quite a robot, so what do you call it?

I recently bought a kiddie Build-Your-Own-Robot kit on a whim, thinking it would amuse my cats. This so-called "robot" is made up of a hollow sphere that pops into a little square frame with a dome on top. Within the sphere is a simple motor with a weight attached. The motor causes the sphere to spin, and the weight keeps it off-balance so that it can turn and move around obstacles. Basically it just skitters around the floor bumping into things. It certainly isn't a robot, but is there a word in science/robotics for something like this?146.235.130.59 (talk) 22:52, 21 December 2014 (UTC)

Why isn't it a robot? It's certainly not a complicated one, but it behaves just as our wikipedia article on robots indicates that it should. Mingmingla (talk) 23:54, 21 December 2014 (UTC)

I wouldn't call it a robot simply because there is no way to give it data or receive data from it. It's just a motor in a plastic shell. It can't see, hear, make decisions, or be programmed to perform a task. It's like the engine in a car or a clock, just a series of moving parts. Clocks and car engines aren't robots, surely?146.235.130.59 (talk) 13:35, 22 December 2014 (UTC)

It sounds like a Marvelous Toy. ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:41, 22 December 2014 (UTC)

Robots are usually presumed to do some sort of work, the word comes from the Slavic robotiti to work as in slave labor. μηδείς (talk) 04:39, 22 December 2014 (UTC)

Like entertain cats? Nil Einne (talk) 14:00, 22 December 2014 (UTC)

I think the def of a robot they are using here is that it must change position on it's own, without control by a person. Compare it to Roomba, an only slightly more sophisticated robot. (talk) 15:16, 22 December 2014 (UTC)

Good point, StuRat. So at what point does something stop being a wind-up toy and start being a robot? The specific "robot" I am talking about is just a motor in a plastic case. The motor alone wouldn't be called a robot, neither would the case. If I take out the motor and turn it on it just sits there spinng, and the case is just an empty piece of plastic. Put the two of them together and neither one of them is changed at all. The motor just spins, the case is just a case, but together they give the illusion of intelligent movement. Is that enough to call it a robot?146.235.130.59 (talk) 19:41, 22 December 2014 (UTC)

Still similar to a Roomba. It has a chip in it that tells it to change direction when it runs into something. If you took that out it would just run into a wall and stay there. So, probably not enough to call it a robot at that point (a powered-wheel lawn mower would do that much, if you disabled the dead man switch). StuRat (talk) 01:58, 23 December 2014 (UTC)

How do we feel about using "automaton" in this context? {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 20:14, 22 December 2014 (UTC)

Well now I just feel stupid for not thinking of that before. This toy certainly seems to fit the description, in that it's just a mechanically animated object that gives the illusion of life/intelligence.146.235.130.59 (talk) 13:41, 23 December 2014 (UTC)

• We're making a mistake by looking for a Platonic ideal of the meaning of the concept "robot". Concepts are used and defined in context. Obviously a cat toy is not a "robot" displacing unskilled laborers from factories. A toy salesman, however, might find the cachet of a robotic cat toy pleasing. The etymology has been given. We can't provide the metaphysical Answer. For closely related words, google "robot synonym". μηδείς (talk) 02:55, 23 December 2014 (UTC)

There is certainly a divide between the technical meaning (something like "A computer that can take physical actions in the world") and the general public's idea of something mechanical that seems to move around by itself. But when you come across things like Robot combat where the machines are generally just radio controlled by humans - or your cat toy, it's clear that the common-use term has diverged from the technical meaning. People who build things like 3D printers describe the moving parts of those things as "robots" - but to casual users of the term, they are no more robots than a microwave oven would be. So language changes. "Computer" used to mean "Person who does calculations for a living" - but not anymore. Right now, if you want to describe machines of this nature accurately, you need to start layering on more description. "Autonomous robot" might describe the Roomba vacuum cleaner - but exclude the cat toy. But then we know that the Roomba doesn't do much other than driving in random directions until it hits something, then turning through a random angle and trying again. That's something that mechanical childrens' toys have been doing for at least a century - so no computers required. (My favorite toy in the late 1950's was a "Tricky Tommy Tractor" [21] which did more or less what the Roomba does with just a single motor and a differential-drive gear). On the other hand my Neato Robotics vacuum cleaner has a laser sensor that maps out the shape of your rooms, intelligence to plan a route through that environment and a stack of algorithms it uses as strategies for getting out of a jam, a memory of where it got stuck and had to be rescued - with a sense of "danger" to avoid those places in the future. It even automatically returns to its charging station to 'feed' when it's battery gets low. The Neato comes close to behaving like a live animal - and certainly lays claim to the name "robot" in every sense of that word. However, a regular inkjet printer also meets most of the criteria to be a robot - and yet I can't think of anyone who'd describe that way.

It all comes down to the steady evolution of language...as annoying as that can sometimes be. SteveBaker (talk) 18:04, 23 December 2014 (UTC)

Yes, of course, Steve. The alarm clock that wakes me up each morning is a robot, as is the train I take to work. This is what's called special pleading. μηδείς (talk) 01:43, 24 December 2014 (UTC)

I think being able to change it's location is key to the definition of "robot", excluding the printer. However, I take "robotic" to mean "similar to a robot", in that it can move, but not necessarily change location, so a "robotic arm" is correct, but you wouldn't call the arm a "robot" by itself, since it can't change it's location. So, you could call a printer a "robotic printer", but that would be redundant, unless used in a context where there's also some type of non-robotic printers (printmakers ?). Then there's the word "bot", which to me means automated software, with no physical movement involved. StuRat (talk) 18:16, 23 December 2014 (UTC)

...and "robo" as in robocall...where, again, no physical action is involved, but a sense of an automatic machine doing the work of a person is present. We also use the word "robotic" in the sense of being poorly capable...a bad actor may speak his lines 'robotically' - or someone might dance the Robot (dance) by moving in a rough, jerky manner. Yet we might also say that a sniper picked off the enemy with robot-like precision...which is kinda opposite to dancing robotically. This word is clearly changing meaning too fast for dictionaries and hard definitions to keep up. So we just hold on and see where it takes us...I think this word is in for a rough ride before it finally settles into a new set of meanings. SteveBaker (talk) 21:34, 23 December 2014 (UTC)

I think that meaning of robotic is "gets the job done, but inelegantly". Or, as might be said of a musician "technically proficient, but lacking 'heart' ". We are finally starting to get some robots that don't move and speak in a jerky motion, so that might eventually make that "inelegantly" part fade away. StuRat (talk) 00:34, 24 December 2014 (UTC)

• Note that in South Africa, "robot" can refer to a robot policeman, i.e. a traffic light. As I hold to the view that the nation of South Africa is as entitled to add words to English as music promoters, I regard this as a fair usage anywhere. Wnt (talk) 05:26, 24 December 2014 (UTC)

December 22

What is the difference between tap water to the physiology solution?

I know the tap water is hypotonic, but what are the values of the tap water compared to physiology solution? 5.28.180.110 (talk) 04:04, 22 December 2014 (UTC)

I assume you are talking about blood? See isotonicity which gives you (grams of NaCl/L water) and human serum albumin. μηδείς (talk) 04:35, 22 December 2014 (UTC)

When I take a shower does I lose my body water?

asked and answered
The following discussion has been closed. Please do not modify it.
I don't understand if it depends on the temperature? (I mean if it's always true that you lose your body water when you take a shower, even when the temperatures are high or the same of the body temperature). 5.28.180.110 (talk) 04:12, 22 December 2014 (UTC) Same question by Tel Aviv IP, see prior answer: https://en.wikipedia.org/wiki/Wikipedia:Reference_desk/Archives/Science/2014_December_15#When_taking_a_shower.2C_does_the_body_loses_liquids_.28.2Fwater.29.3F μηδείς (talk) 04:21, 22 December 2014 (UTC)

Why weren't compound bows invented much sooner?

Leonardo's crossbow was a very simple design scaled up massively, but it still looks like a crossbow. Yet in the 1960s there was a sudden profusion of many different designs for compound bows with pulleys/eccentric pulleys/cams, extra limbs, and many other creative features. Reading [22] it sounds like "modern glues and fibreglass" was a key advance, but..... was it really necessary for the invention? Aluminum alloys are used, but wouldn't steel or even bronze have worked in ancient times? Ultra-high-molecular-weight polyethylene is used for the cables, but is there no classical sort of ultra-strong "thong from the hide of the yellow ox" that might have done the job? And Leonardo didn't merely fail to make a compound bow... he failed to try. I just don't get how people missed such innovations for so long only to end the drought so abruptly; can it be explained scientifically?

I'll admit that I haven't used a compound bow and there are many aspects of the eccentric/cam design that aren't obvious to me, so more general explanations (or preferably better clarification in the article itself!) would be very welcome also. Wnt (talk) 04:49, 22 December 2014 (UTC)

This is an old design infact. See Laminated bow or Yumi#Shape. Such products seem much more result of an artisan tradition than result of one ingeniouse inventor. --Kharon (talk) 13:21, 22 December 2014 (UTC)

The main purposes of the compound bow are to reduce the accelerated mass of the limbs, and to get a better force/draw curve. I don't think the theory the first idea was obvious before Isaac Newton. You can get a lot of the second advantage with less hassle and less complex engineering with a composite bow. --Stephan Schulz (talk) 14:46, 22 December 2014 (UTC)

I think there's a couple of things at play here. At the article notes, compound bows are complicated to make and consist of some rather specialized kinds of materials including rubbers, plastics, aluminum, carbon fibers, and other goodies. By the time these were in regular use, the problems of making easier to use bows had already been solved with guns. It wasn't until relatively recently that guns became deadlier than bows for an expert to use, but they've long had advantages in being simpler to use. The original point and click program! The end result being that the iron mongers that might have spent their time and expertise making bows easier to use (i.e. making them into compound bows) instead put their skills into developing rifling and tweaking the cross-section of bullets. Matt Deres (talk) 14:51, 22 December 2014 (UTC)

Hmmm, I'm getting the feeling from this that the compound bow is an emergent property of modern technology. With the accompanying skepticism of whether emergent properties are really real and meaningful... but nonetheless, an interesting representative. Wnt (talk) 00:27, 23 December 2014 (UTC)

I see the compound bow as a very sophisticated hobbyist development. Guns long ago rendered bows obsolete for military and subsistence hunting purposes. Use of bows continued for aesthetic reasons, for target shooting and in a subset of hunting for pleasure as a hobby or a sport. As leisure time and the money available for hobby and sport activities increased in the 20th century, the equipment used in hobbies and sports became ever more sophisticated, incorporating cutting edge technologies. A modern America's Cup yacht is perhaps the ultimate example, with the compound bow representing a more economical but still very sophisticated example. Cullen³²⁸ Let's discuss it 01:47, 23 December 2014 (UTC)

It think there are other reasons to want a bow rather than a gun. For starters, you don't have to buy ammunition - for another, they are virtually silent (which could have MANY advantages) - for yet another, there are many places in the world where private possession of guns is illegal, but bows are OK. SteveBaker (talk) 17:49, 23 December 2014 (UTC)

I think the "hobbyist" aspect is a bit of a side-track, because what I was really wondering is why Leonardo da Vinci or one of the earlier Chinese inventors didn't come up with a similar design, at a time when one might have made a hobby of killing people with them. Unlike racing yachts, compound bows aren't tremendously expensive, nor are they specialized for only one purpose; hunters in general actually tend to like them for routine tasks, whereas you don't see a racing yacht put to use as a water taxi or passenger ferry. Wnt (talk) 18:27, 23 December 2014 (UTC)

It's hard to guess why someone DIDN'T think of something clever. Even if all of the necessary underpinnings of an idea are present - sometimes nobody puts two and two together for many, many generations. Why didn't DaVinci think of negative numbers? Why didn't anyone in Georgian England come up with the idea of Evolution? Why wasn't sliced bread invented until 1912? Why weren't retro-reflective Cat's eye (road) used in road construction before 1933? Who knows why some people come up with bright ideas and others don't? It's not something you need a reason for. Some ideas are just not obvious, and even with millions of human brains contemplating how to make a better bow, it's perfectly possible that nobody ever thought of using pulleys to help pull it...until the day that somebody did. SteveBaker (talk) 21:25, 23 December 2014 (UTC)

Actually, they were indeed created much sooner than they were. Originally, they weren't scheduled until the Fall of 2041. μηδείς (talk) 02:29, 24 December 2014 (UTC)

I don't want to discount your points, which are entirely valid (why didn't New World civilizations invent the wheel, why didn't Europeans invent paper), but I think there's a very real issue of availability in this case. At the risk of over-generalizing, by the time the materials and craftsmanship that are needed to go into compound bow production became available, the bow had largely been superseded. To respond to your earlier point above, while bows have some obvious advantages, history seems to show that the negatives outweigh them. The chief problem comes down to skill and ability; it takes a lot of training to use a bow well; not just to work on your aim, but also to develop the large shoulder and back muscles you need. Even the skeleton was noticeably warped by the intensity. Compare that with pulling your trigger finger! Matt Deres (talk) 04:02, 24 December 2014 (UTC)

many versions forms of the arm veins

In the past, someone gave me here (in our page) a link for site or book that shows how many versions there are in the forms of the arms veins. I looked for it and I couldn't find it. I would like to get help. 5.28.180.110 (talk) 07:43, 22 December 2014 (UTC)

Well, we have the illustration File:Sobo 1909 597.png, which may be of some help. This page discusses some of the observed variations. Are these of any use to you? Deor (talk) 19:07, 22 December 2014 (UTC)

Yes. these are. Thank you! But I looked for the information that was given here before :) I remember that there are more than three versions (I think even 50 or something like that) 5.28.180.110 (talk) 23:22, 22 December 2014 (UTC)

Was this your previous question? Deor (talk) 23:53, 22 December 2014 (UTC)

Yes, it is! Thank you deeply :) (How could you do that?!...)5.28.180.110 (talk) 04:24, 23 December 2014 (UTC)

I don't like to destroy my reputation as a man of mystery. ... However, in this case I just entered arm veins in the reference-desk search box at the top of this page, and that thread came up third in the list of results. Deor (talk) 04:57, 23 December 2014 (UTC)

If so, I don't have a good answer for that :/ I looked for this and I saw a lot of results. 5.28.180.110 (talk) 12:18, 23 December 2014 (UTC)

Given a perfectly sealed airship, could it remain in the air for years?

Would an airship, or a kind of balloon, made with a tough material, with the same density as air at 10,000 m, ever fall back to Earth? --Noopolo (talk) 18:46, 22 December 2014 (UTC)

There's be some diffusion across the material of the gas-bag in the long term. So even "perfectly sealed" it would slowly lose lifting gas.

But the reality is that most airships that don't crash or get shot down, are eventually lost to storms. List_of_airship_accidents APL (talk) 19:41, 22 December 2014 (UTC)

Are you presuming the balloon contains lighter-than-air gas such as hydrogen or helium? ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:05, 22 December 2014 (UTC)

Yes, and the balloon is made of something really tough, like a thin sheet of titanium. Noopolo (talk) 20:09, 22 December 2014 (UTC)

First, let's just suppose it were possible to create a perfectly sealed container that's lightweight and durable. Did you want the balloon to maintain a certain usable altitude? Or just to rise until it reaches some kind of equilibrium and "hangs" there? ←Baseball Bugs ^{What's up, Doc?} carrots→ 20:51, 22 December 2014 (UTC)

In theory yes, in reality, no. Lightning, UV light, hurricanes, tornadoes, etc., would get it eventually. StuRat (talk) 02:01, 23 December 2014 (UTC)

Obviously a calamity could occur. The question seems to be what happens if there is no calamity. Would it rise clear out into space and drift away? Or would it reach some sort of equilibrium and hang there? Of course, any sort of wind would move it around. But would it stay at a more-or-less fixed altitude? ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:51, 23 December 2014 (UTC)

Even hydrogen has mass, so obviously it would reach equilibrium even with the lightest of containers. The greatest equilibrium height that has been achieved in practice seems to be around 25 miles. Dbfirs 08:57, 23 December 2014 (UTC)

OK, so at some point, it would become as heavy as the air around it, and would rise no further. So, barring calamity, it would float around in the upper atmosphere indefinitely, right? ←Baseball Bugs ^{What's up, Doc?} carrots→ 14:58, 23 December 2014 (UTC)

In a universe with no UV light where materials last forever, yes. In the real world, no. StuRat (talk) 16:22, 23 December 2014 (UTC)

The start of the question, "Given a perfectly sealed airship..." presumes an ideal situation rather than real-world. Even forgetting that, the questions asks both "for years" and whether it would "ever fall back to Earth." So in the real world, a sufficiently sealed balloon could stay aloft for a lengthy time, but just how long would depend on many factors. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:33, 23 December 2014 (UTC)

I take "a perfectly sealed airship" to mean that it was initially perfectly sealed, not that it would remain so forever, which would require changing the nature of the universe. StuRat (talk) 17:04, 23 December 2014 (UTC)

The practical problem is that the available lighter-than-air gasses all have very small molecules (especially hydrogen and helium) - and they'll leak through any reasonable material - especially because the pressure inside the balloon is likely to be higher than outside. A hot-air balloon wouldn't have that problem - but keeping it hot would likely be impossible. So as a practical matter, the answer is definitely "No!". But as a thought-experiment, then with a material that was somehow magically impervious to hydrogen or helium would be able to stay aloft indefinitely.

If we're getting picky about "indefinitely" and "exactly the same density of air at 10,000 meters" then there might be other issues. List of birds by flight heights indicates that there are a couple of bird species that can fly that high - and if one of them decided to land on the perfectly set up craft, then it would start to slowly fall back to earth and find a new equilibrium at a lower altitude where other birds could reach it and push it down further...unlikely to happen...but "indefinitely" is a very long time! At least at 10,000 meters, you're above obvious obstructions like mountains and man-made structures. SteveBaker (talk) 17:43, 23 December 2014 (UTC)

The OP contradicts himself, between "for years" and "would it ever", the latter implying "forever". However, it looks like he's got ample information from various responders. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:36, 23 December 2014 (UTC)

While it's possible that wind phenomena could "bring it to Earth" at high mountains like the Himalayas, the real answer is probably that xeric plants like lichens would grow on it, accumulate dust, get some moss or grass growing, until it was so encrusted that it came to rest. Weary travellers would doubtless decamp on this raised soft and verdant spot in the otherwise barren Tibetan plain, until this modern-day sinking island, without warning, would pitch off some of its burden and bear its hapless passengers away to the depths of the sky, never to return. Wnt (talk) 22:29, 23 December 2014 (UTC)

Maybe. I was imagining a balloon the size of a beach ball. ←Baseball Bugs ^{What's up, Doc?} carrots→ 23:15, 23 December 2014 (UTC)

• You get a better buoyancy/weight ratio with a larger balloon, see surface-area-to-volume ratio. You need one that will pass over the highest mountains (The Andes and the Himalayas) over which the jet streams pass. You can calculate this from the air pressure at the top of Mount Everest. You'll get the best results from a high-entropy alloy like AlLiMgTiSc which is as light as aluminum and as strong as titanium. You should be able to fill this with H₂ at a partial pressure less than the air at the same altitude at which it will fly. μηδείς (talk) 01:37, 24 December 2014 (UTC)

Baumgartner's video

Why in this particular Red Bull's video the altimeter shows something like 4,469 ft (1,363 m) when Felix had already landed (although the airspeed looks correct)? Aren't they live-streamed parameters? Brandmeister^talk 21:10, 22 December 2014 (UTC)

Because that's the altitude of the place, 40 miles east of Roswell, where he landed. Google Earth gives an altitude of 4462 ft at the landing location given in the Red Bull Stratos article. -- Finlay McWalterᚠTalk 21:41, 22 December 2014 (UTC)

QNH is the technical term. Tevildo (talk) 22:23, 22 December 2014 (UTC)

....Although, I have never heard of "QNH" in common use as an aviator in the United States. I think you would get a lot of blank stares if you used that terminology at an airfield in New Mexico. Here, we use "flight level," and only when appropriate (generally, for Class A airspace, above 18,000 feet MSL). Perhaps the Q code terminology is more common in Europe or elsewhere. Nimur (talk) 15:08, 23 December 2014 (UTC)

The longest half life medication is known?

asked and answered
The following discussion has been closed. Please do not modify it.
5.28.180.110 (talk) 23:23, 22 December 2014 (UTC) See answers to a similar question at Wikipedia:Reference desk/Archives/Science/2014 December 16#Is it known which drug is with the longest half life. Plasmic Physics (talk) 02:15, 23 December 2014 (UTC) This Tel Aviv IP is repeatedly asking the same questions multiple times, over and over again, redundantly. μηδείς (talk) 02:48, 23 December 2014 (UTC)

December 23

Why insulin is not taken oral but in injection?

5.28.180.110 (talk) 12:20, 23 December 2014 (UTC)

It would be destoyed by digestion. Roger (Dodger67) (talk) 14:00, 23 December 2014 (UTC)

Yes, as described at the end of Insulin#Medication uses:

Unlike many medicines, insulin currently cannot be taken orally because, like nearly all other proteins introduced into the gastrointestinal tract, it is reduced to fragments (even single amino acid components), whereupon all activity is lost. There has been some research into ways to protect insulin from the digestive tract, so that it can be administered orally or sublingually. While experimental, several companies now have various formulations in human clinical trials, and one, the India-based Biocon, has formed an agreement with BMS to produce an oral-insulin alternative.

The questioner may also wish to read anti-diabetic medication, which mentions many drugs, such as the commonly prescribed metformin, which can be taken orally. -- ToE 14:03, 23 December 2014 (UTC)

Isn't "anti-diabetes medication" a better term ? "Anti-diabetic medication" sounds like it's designed to eliminate diabetics, not treat diabetes. StuRat (talk) 16:18, 23 December 2014 (UTC)

Yes, it sounds like a candidate for a move. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:28, 23 December 2014 (UTC)

While both terms are used in the literature, anti-diabetic appears to be used much more commonly than anti-diabetes. -- ToE 22:25, 23 December 2014 (UTC)

The problem is that people with diabetes are called "diabetics", so "anti-diabetic" can mean "against people with diabetics". StuRat (talk) 00:19, 24 December 2014 (UTC)

It could. And yet it doesn't. There's no reason to deviate from standard terminology. - Nunh-huh 00:48, 24 December 2014 (UTC)

The problem is that "diabetic" is an adjective which has been co-opted as shorthand for "people with diabetes". ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:33, 24 December 2014 (UTC)

I don't think it deviates either. You would have "anti-cancer medication" not "anti-carcinogenic medicine", which, again, would mean something else. StuRat (talk) 05:21, 24 December 2014 (UTC)

Custom books on water- and tear- resistant paper

I've seen pocket-size reference books printed on paper that's water-resistant. I think the paper is tear-resistant too but I'm less certain about that. Can you print custom books inexpensively in very small quantities (1 or several) on that kind of paper? I've seen notebooks made of rain-resistant paper, but you will have to write the content with a pen; that's not what I'm looking for. --173.49.11.192 (talk) 15:19, 23 December 2014 (UTC)

Regular printers can handle overhead projection slides, which are certainly waterproof, and I imagine an opaque version can be made. However, the ink is another issue, with ink-jet printer ink being water soluble. I think laser jet toner may hold up better to water. StuRat (talk) 16:14, 23 December 2014 (UTC)

I've had success using a laser cutter to etch text onto all sorts of materials. The marks it makes are essentially impossible to remove by any means - and most materials can be etched (albeit with some difficulty). But it would be time-consuming to make a book with a lot of text in it that way. I guess you'd have to contact businesses like CafePress who specialize in on-demand printing. SteveBaker (talk) 17:27, 23 December 2014 (UTC)

On the 'Net, I found "weatherproof paper" made by a company called iGage. The product seems to be for print custom maps for outdoor activities and seems to be made of a tough material. It's supposed to work with some inkject and laser printers. The downside to it is that it's very expensive—something like 75¢ per sheet! If someone knows of a cheaper/better solution, please share the info. Thanks. --173.49.11.192 (talk) 18:03, 23 December 2014 (UTC)

Vellum (the plasticized cotton version) is what's used for blueprints, so that can be taken to job sites and not dissolve in the rain. It seems to cost about 15¢ per sheet: [23]. Some of their products contain warnings not to use them in a normal printer: [24], but others do not. You might want to contact them and ask specifically which will work in a given printer. StuRat (talk) 18:23, 23 December 2014 (UTC)

I've used Aquascribe paper before to photocopy detailed maps for geological mapping - you could write under water with that stuff and it was tear-resistant. Here's the website - £33.80 (so about $22) about for 250 A4 sheets, more expensive of course in smaller quantities. Mikenorton (talk) 20:38, 23 December 2014 (UTC)

The currency markets have been a bit crazy recently with Russia, but not that crazy. Apparently it's roughly 1.55 USD per pound sterling, so $52 or so, so that would be 21 cents a sheet. Wnt (talk) 21:24, 23 December 2014 (UTC)

Oops, should have multiplied rather than dividing by 1.55, just as well I don't work in finance. Mikenorton (talk) 23:29, 23 December 2014 (UTC)

I've also seen books for toddlers made to be waterproof, so they don't have to be thrown out the first time a lollipop ends up stuck to a page. StuRat (talk) 00:36, 24 December 2014 (UTC)

Is it dangerous to drink pure water (H2O)?

If so, what is the amount that can make damage? (it can help for example for someone who has only air conditioner or for someone in the desert - by collecting the water from the air) 5.28.180.110 (talk) 15:42, 23 December 2014 (UTC)

This WHO report explores the issues with drinking demineralised water - the lack of magnesium and calcium are the main potential problems, although this is with long term use. Mikenorton (talk) 16:07, 23 December 2014 (UTC)

And note that condensate is not pure water by any means. All the dust in the air tends to stick to the droplets that form, making it quite full of minerals, bacteria, etc. So, whether drinking condensate water is OK is another question. I should think that the longer the condensate sits, the more the bacteria in it would grow. StuRat (talk) 16:10, 23 December 2014 (UTC)

Distilled water seems to be about the closest you can get to "pure" water. As noted above, you probably don't want to consume it as a long term standard, but if you're desperate for water, it's better than nothing. The lack of minerals in it makes it very bland-tasting. One of the episodes of Going Deep With David Rees was about water, and he commented on that. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:26, 23 December 2014 (UTC)

Water intoxication sets an upper limit of around 0.8 liters per hour for short-term consumption (assuming an otherwise healthy person, etc, etc) - but that applies to all water, not just the super-pure stuff - and I don't think that's the scenario you're concerned about. Drinking water without the usual minerals in it isn't going to cause problems in the very short term - and it can only cause longer-term problems if you don't have sufficient of those minerals in your diet from someplace else. So the answer to this question is complicated - it depends on what food you eat and for how long you drink the stuff.

That said, the WHO report (linked to above) says that demineralized water tends to pick up more impurities (eg from the containers it's stored in) than mineralized water - so there could be an issue if this water is stored inappropriately.

SteveBaker (talk) 17:20, 23 December 2014 (UTC)

I thought drinking of distilled water can causes to hypocalemia and hyponatrmia, because its low density. 5.28.175.146 (talk) 02:20, 24 December 2014 (UTC)

Not if you are also eating food. You need calcium and sodium from anywhere - it doesn't have to be water. Ariel. (talk) 06:23, 24 December 2014 (UTC)

Diving with TLB technology

Supposing that Total Liquid Breathing (TLB) technology is used in diving, what is the highest pressure that the human body can endure, while maintaining consciousness? Plasmic Physics (talk) 23:22, 23 December 2014 (UTC)

The deeper one dives the more readily the calcium in one's bones dissolve. So 'perhaps' one could remain conscious at the depths deep enough to reduce one to a blob of jelly. In the advancement of science -do we have a volunteer here?--Aspro (talk) 00:23, 24 December 2014 (UTC)

As we share 90% of our DNA with fish, maybe the limiting factor is the efficiency of our enzymes at depth. The Biology of the Deep Ocean By Peter Herring Think we need a volunteer to discover that point. With nitrogen psychosis, some divers can cope at depths below which others succumb to it. So survival may be possible for days with with TLB or just minutes, depending on the individual but we wont know until someone volunteers themselves in the name of science.--Aspro (talk) 00:59, 24 December 2014 (UTC)

Our article on liquid breathing cites a surprisingly high 10 liter per minute rate for fluid exchange using the current liquids. It's amazing that an animal with lungs can breathe any liquid, but to use it in diving it sounds like they need a better liquid than what they have.

FWIW, I'm gonna guess graphene. (To trap gas in a compressed state in perfluoro solution) You can do anything with graphene, if you could do anything with graphene! Wnt (talk) 01:56, 24 December 2014 (UTC)

These are technological challenges that lies beyond the scope of this query. Plasmic Physics (talk) 08:56, 24 December 2014 (UTC)

Yes, I do think that is a limiting factor, but is it the limiting factor? Plasmic Physics (talk) 08:56, 24 December 2014 (UTC)

December 24

What is the reason for the red color of SEDURAL that appears in the urine of the patient?

What is the reason for the red color of SEDURAL that appear in the urine of the patient? The pharmacy companies couldn't create it without this color? Is there any purpose for this color? — Preceding unsigned comment added by 5.28.174.110 (talk) 01:32, 24 December 2014 (UTC)

I'm only answering quickly here and so some of this is a guess, but note that Phenazopyridine is an azo dye that was invented by Bernhard Joos in 1932, after which he founded Cilag. I presume that this was a part of the general realization that "vital dyes" could have specific pharmacological effects -- scientists had noted that the dyes they developed might stain different kinds of organic molecules, and deduced that a dye that stained one part of a cell but not another, or better yet stained a bacterium more than it stained the host cell, might have a medicinal effect. This is closely akin to the notion of binding affinity (which may or may not imply IC50), and soon the scientists realized they didn't have to actually see the compound bind to a specific structure for it to have the potential to do so. Still, seeing a dye light up unwanted bacteria must have quickened many a pulse in the old days as people wondered if they might use them as "magic bullets" to kill the disease without touching the host. Now this compound isn't anti-infectious but analgesic, which can be compared to some other small aromatic molecules like aspirin, but of course it is still useful. Many other compounds with similar effects have been identified, but redesigning this one would be hard because the whole point of an azo structure is to create color, by linking two aromatic rings with the nitrogen bridge; to make it colorless implies a total chemical redesign, almost from end to end of the molecule. Wnt (talk) 01:45, 24 December 2014 (UTC)

Thank you for the explanation, but I didn't understand the reason about the color. 5.28.175.146 (talk) 02:54, 24 December 2014 (UTC)

Well, there are two ways to look at it. Historically, scientists started out trying their best to make dyes, came up with a bunch of them, then started to examine their effects, which is why an old medicine turned out to be a dye. Scientifically, the reason why this chemical is a dye is that it has a long system of conjugated double bonds. To give you an idea (I'm glossing over a lot, like Hückel's rule...) if you have something that is N-C=C-N=N-C=C, it could also be N⁺=C-C=N-N=C-C^-. That means that the longer the conjugated double bond set, the further the molecule can conduct an electron from one end to the other like a little wire. And like a simple antenna of a certain length that picks up a certain radio station, these molecules pick up light of a certain frequency. (It's not really that simple, in that the molecule is much, much shorter than the wavelength of the light it absorbs; you can use Woodward's rules and see that adding a bit under 3 angstroms to the molecule length means adding 300 angstroms to the wavelength. The absorption goes by the energy of the photon in the molecular orbital - I'm not sure, but I think ultimately you can work out the math as somehow equivalent to the classical picture of an electron oscillating back and forth with the same frequency as the light, in a constrained environment, but honestly I don't think I ever was particularly clear on whether that's really true or not!) Wnt (talk) 04:20, 24 December 2014 (UTC)

Dealing with a difficult “educator”

Hello everyone.

I am posting here for advice regarding professionally handling an “educator’s” conduct which I’m questioning. To remain within the guidelines, I won’t mention any names, nor will I ask for any opinions [even if it sounds at times that my post may invite such], but will write, in good faith, whatever I believe is allowed here for the purpose of obtaining information about standard professional guidelines within the intellectual community including professional conduct guidelines. This post is only intended to address the claims and the conduct in itself in reference to professional standards and guidelines, with no identities mentioned to avoid WP:BATTLE.

To avoid giving any personal information, I will keep things as general as possible.

I had recently struck up a conversation regarding various scientific disciplines with somebody who works for an organization. He claimed to have training in meteorology, biology, social science, and some medical science. He began making claims and claimed that he “enjoyed speaking”, but completely refused to provide any sources when I asked, even smirking with an “elementary school” smirk, demanding that I accept the claims he makes, stating “No! I don’t need to [cite sources]!”

A few true examples of claims he has made which I can recall off the top of my head:

• “Soap makes water wetter”
• It would be significantly harder for the average person to breathe in Denver, Colorado than in most other U.S. cities, following it with commentary, “I don’t care what else you say”, unless acclimated over a period of time.
• A cold front, when travelling south from the arctic, descends in altitude, and travels (word for word) “like syrup poured onto a plate”, claiming that cold air is literally “piled up high” in the arctic, then loses altitude as it spreads horizontally to lower latitudes.
• [In response to my own comment that the dewpoint is how meteorologists measure absolute atmospheric moisture content], he stated “No! The dewpoint is not a measure of absolute moisture. It is only the effect of the absolute moisture. The absolute moisture is measured using various other scientific measurements”, such as grams per milliliter if I remember correctly.
• [Also some claims regarding sexuality which I don’t feel comfortable posting without being given the “OK”, and may or may not even want to post at all].

He also said, based on some beliefs that I have expressed in regards to the eugenics movement (will not go into detail), that “I think your ideas have some similarities to the fascist regime”. When I later complained about his statement, in that I felt that he referred to me as a fascist he then returned, stating that I made a false complaint, commenting to me, “the way you perceive things is [erroneous]”, arguing “I did not call you a fascist; I said that your ideas had some similarities, which is different!” But nevertheless, I still stand behind my view (references regarding usage of the word fascist in this regard would be useful just for the sake of it).

Furthermore, in regards to some views that I have expressed, in fact, with stress, about morality in our society (sensitive, so will not go into detail), he stated, word for word, with the “elementary school” smirk again, “See how you have that RAISED tone of voice? That means you are predicating your happiness on other peoples’ actions, and that is by definition control!”, also raising his voice slightly, and claiming that it was an analysis of my behavior based on his psychology training. Since he did claim to be a “counselor” on top of all of the other educational qualifications he claimed to have, I was in fact open to a certain extent for discussions regarding morality, but later wasn’t sure if that was a good choice to make. On a future occasion, he later gave a slightly reworded variant, stating “You are predicating your happiness on the thoughts, feelings, and actions of others”.

Given that a definition is easy to lookup, I found no formal definition even close to this statement, but would be interested in any sources which may even be remotely close to this “definition”, and additionally, would be interested in knowing the formal terminology and guidelines that describe “making up definitions” from an intellectual community perspective.

Sources consisting of the subject matters discussed as well as any covering standard professional guidelines are requested. Thanks in advance. 2602:304:59B8:4149:207E:1B06:3FB7:5FEA (talk) 01:55, 24 December 2014 (UTC) (Last edited by 2602:304:59B8:4149:207E:1B06:3FB7:5FEA (talk) 01:59, 24 December 2014 (UTC), reason: Punctuation)

Well, for starters, soap does indeed "make water wetter", by cutting back on its Surface tension. This explains in more depth.

The Denver Post has a writeup on how to deal with altitude sickness, which is apparently not a small problem in Denver. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:05, 24 December 2014 (UTC)

• Soap can form a micelle or layer that makes a firm contact between a hydrophobic substance and water, and so (to such molecules) maybe it makes water wetter (though obviously that can be defined to be meaningless)
• There is less air in Denver relative to other U.S. cities. I remember flying there and it was like they never let the air back into the plane. Of course, that means you can actually puff more of the thin air than you could of thick sea level air, but I kind of like the latter anyway. :)
• A cold front does approach with the cold air fanned out in a wedge in front of it, close to the ground, like syrup on a plate. They often are described as "arctic air" in provenance, though of course they can approach from non north directions.
• The dew point is indeed related to one way to measure humidity with a wet bulb thermometer; many other methods exist including calibrating the shrinkage of a hair from your head. I think he has a point that at some point somebody had to measure how much water was actually in a sample of air to know what it meant.

Based on these things, I would say that he is trying to make approachable generalities to describe scientific concepts, but they may confuse some people rather than enlighten them. Your differences may be more personal than scientific in nature, with neither of you giving the other a full chance to be understood. Wnt (talk) 02:09, 24 December 2014 (UTC)

@Wnt: Thanks for responding. The ultimate concern that I had was the issue regarding proper procedure in the intellectual community, and how I should respond (from a scientist's perspective) to somebody who literally becomes rude to avoid citing sources, which I politely requested, and who also uses questionable definitions to make personal attacks, for which, just out of curiosity, I wanted to know if there even was any validity behind that "control definition", and ultimately wanted to improve my professional skills in dealing with "educators" like this in the future to avoid being in an awkward position, besides the fact that I questioned the validity of the content given the other party's response to my request for sources. There were also other profane remarks which I didn't feel comfortable posting which also undermined his credibility in my mind. Ultimately after finding myself in this difficult and awkward position I would like to feel that I would be able to respond to it more professionally if it ever arose in the future. 2602:304:59B8:4149:207E:1B06:3FB7:5FEA (talk) 02:30, 24 December 2014 (UTC)

Well, for one thing, if he ever repeats any of these truisms, you could say, "Yes, I know, I was just reading about it." ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:46, 24 December 2014 (UTC)

Well, professionally, you know how it is: there's nothing to be gained from a 'political' struggle (in the petty sense). If you get into a fistfight with a whore it doesn't matter if she started it, it still looks bad for you. Now in this case my gut sympathy is with the other guy; I have a feeling I'd like him ... all the more reason not to try to bring things to a head. Wnt (talk) 04:24, 24 December 2014 (UTC)

Not fighting. On the contrary, this would be kind of kissing up. Stroking his ego, as it were. ←Baseball Bugs ^{What's up, Doc?} carrots→ 04:27, 24 December 2014 (UTC)

It is true that Denver is the highest altitude major city in the United States, and it is the "mile high city" at over 5,200 feet elevation. So, yes, if you fly from sea level to Denver, you may notice some minor breathlessness at first. Most people will adapt quickly. Mexico City is about 2000 feet higher, and there was concern about altitude sickness before the 1968 Olympics, but the concerns were pretty much unfounded. True altitude sickness is rare below 8000 feet elevation, and there are towns in Colorado such as Leadville at elevations above 10,000 feet. Personally, I have spent many weeks camping in California at altitudes above 10,000 feet, and really have difficulties only when climbing well above 13,000 feet. But I have climbed two 14,000'+ peaks in my 50s, namely Mount Shasta and Mount Whitney. Skilled Himalayan mountaineers can function, briefly, at altitudes twice that high. Careful acclimatization is essential at very high altitudes. Cullen³²⁸ Let's discuss it 07:02, 24 December 2014 (UTC)

Depending on where you live, and what the eugenic views you were expressing were, commenting that your views were similar to those espoused in the fascist regime might be considered helpful, since you were presumably unaware of the history and connotations of your views. That you took that as them calling you a facist, and took offense, indicates that the problem is not simply with them not citing sources. 86.156.148.98 (talk) 10:04, 24 December 2014 (UTC)

When cheeking blood for glucose- how many types of molecules of glucose does it cheeks?

When cheeking blood test it cheek only one types of molecules (of glucose) or only one? 5.28.175.146 (talk) 02:17, 24 December 2014 (UTC)

Have you read our article on glucose? μηδείς (talk) 02:32, 24 December 2014 (UTC)

Yes, I have. Maybe I didn't understand something? I know the famous form of glucose (C6H12O6) but it's not clear to me what are the types of glucose that cheeked in the laboratory or in the glucometers. I didn't see something about on the article. 5.28.175.146 (talk) 03:07, 24 December 2014 (UTC)

Are you, perhaps, asking if all of the isomers of glucose are checked equally by a glucometer? Perhaps one of our chemical-minded editors will be able to answer. -- ToE 03:21, 24 December 2014 (UTC)

Yes, I am. Thank you. 5.28.175.146 (talk) 03:56, 24 December 2014 (UTC)

Among the isomers of glucose, several are different transient states of the same thing. For any single stereoisomer (there are two enantiomers), the straight-chain form and the various closed-ring pyranose and furanose forms can easily and rapidly interconvert when dissolved in water. They are therefore not distinguishably "different chemicals" in many testing scenarios with biological samples--a test for any one of them would suffice. But only one of the two enantiomers is noticeably present in...well, much of anything at all in nature, let alone commonly encountered as a nutrient or blood component. Therefore the test only needs to detect that one (D), but it would not be a problem if the test were not able to distinguish or detect specifically that one between the two because the "other one" (L) is not present. The other aldohexose steroisomers are not glucose at all. I don't know if they have noticeable and noticeably-variable presence in blood, the details that would determine whether a "glucose" test would need to avoid detecting them. DMacks (talk) 05:00, 24 December 2014 (UTC)

The different enantiomers of glucose convert rapidly among one another in solution, and as the standard glucose meter oxidizes glucose to gluconolactone catalyzed by glucose oxidase (sometimes known as GOx) the remaining enantiomers will spontaneously convert to D-Glucose. So, directly or indirectly the meter will detect the four standard D- enantiomers of glucose present. μηδείς (talk) 05:27, 24 December 2014 (UTC)

Glucometer#Technology mentions some specific enzymes that are used in some of the common test equipment. They seem to be specific to glucose rather than other aldohexose isomers of it. The article about glucose oxidase even discusses how the various forms of the relevant enantiomer of glucose interconvert easily enough to be all detected together. Medeis is not correct that enantiomers convert between each other. Within one enantiomeric form, certain structural and epimeric forms interconvert. The other enantiomeric form would have its own equivalent set of forms, but there is no crossover betwen one enantiomer and the other. The enzyme is specific for one enantiomeric form, but, being a biologically derived material, it is already tuned for the biologically relevant enantiomer of glucose (the un-natural enantiomer of the enzyme, if one were to make it, would be specific for the un-natural enantiomer of glucose). DMacks (talk) 05:32, 24 December 2014 (UTC)

I hope you won't find me cheeky if I point out the words you want are "checking" and "checks". StuRat (talk) 05:15, 24 December 2014 (UTC)

Insulin and other hormones

I read in our article Insulin that "Unlike many medicines, insulin currently cannot be taken orally because, like nearly all other proteins introduced into the gastrointestinal tract, it is reduced to fragments". Is it not wonder to say that Insulin can not administrated by oral way because "it is reduced to fragments", while many hormones administrated by oral way? 5.28.175.146 (talk) 04:08, 24 December 2014 (UTC)

Insulin is a protein. We eat organisms made of many proteins with many different purposes and if we let them into our bodies it would be chaos (then death). So the digestive system chops them up in little bits, and doesn't let anything of them in except what has been chopped up into little bits. With... lots of clever little exceptions (if your intestine isn't virus-proof or even roundworm-proof, it's not protein-proof!), but so far, nothing really good enough to let people take insulin orally. It is, however, not actually impossible to come up with a way, and that might happen fairly soon. Wnt (talk) 04:28, 24 December 2014 (UTC)