Welcome to the science section
of the Wikipedia reference desk.

Select a section:

WP:RD/S

Want a faster answer?

Main page: Help searching Wikipedia

How can I get my question answered?

Select the section of the desk that best fits the general topic of your question (see the navigation column to the right).
Post your question to only one section, providing a short header that gives the topic of your question.
Type '~~~~' (that is, four tilde characters) at the end – this signs and dates your contribution so we know who wrote what and when.
Don't post personal contact information – it will be removed. Any answers will be provided here.
Please be as specific as possible, and include all relevant context – the usefulness of answers may depend on the context.
Note:
- We don't answer (and may remove) questions that require medical diagnosis or legal advice.
- We don't answer requests for opinions, predictions or debate.
- We don't do your homework for you, though we'll help you past the stuck point.
- We don't conduct original research or provide a free source of ideas, but we'll help you find information you need.

Ready? Ask a new question!

How do I answer a question?

Main page: Wikipedia:Reference desk/Guidelines

The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.

December 15

How much would it cost to build the space colonies from Mobile Suit Gundam?

I'm sure someones asked about the mobile suits themselves, but I'm curious about the orbital colonies from the original series. I know people have estimated the cost of the Deathstar in U.S. dollars, but space colonies sound more practical, if potentially devastating when dropped. I assume asking how much science costs is a science question. CensoredScribe (talk) 04:26, 15 December 2013 (UTC)[reply]

Ummm, just in case some of us were a little ... rusty ... about this Mobile Suit Gundam, could you explain where and what they are? I see something about an O'Neill cylinder in that article but tell us how big you want it. Wnt (talk) 04:48, 15 December 2013 (UTC)[reply]

Sure thing, according to the setting notes from Sunrise (company), 36 million people can live inside of a cylinder 32 kilometers long and 6.3 kilometers in diameter; these space colonies are situated at the Lagrangian points. [1] Lets say the power is being provided by nuclear fission instead of nuclear fusion, as we don't have nuclear fusion reactors that provide net energy yet. They can only use electric cars and electric rails; and have enough water and agricultural land for the colony to comfortably sustain it's self. It's a shame they never let you do something as cool as building this in SimCity; thank you for answering this question. CensoredScribe (talk) 23:40, 15 December 2013 (UTC)[reply]

The biggest cost of building space colonies is lifting raw material off the face of Earth. You can keep the cost down by using raw material from Asteroids instead of raw material from the Earth's surface. Furthermore you can keep the cost of the colonists down by sending them up when they were sperm and ovums as these are pretty light. Then raise the colonists using robots until they achieved adulthood. And this is the cheapest way of building the space colonies. 202.177.218.59 (talk) 04:01, 16 December 2013 (UTC)[reply]

But would a person raised by robots be fully psychologically developed? I strongly suspect that, at the very least, such a person would completely lack emotional intelligence and would have major problems interacting with other people -- which would lead to severe social problems in the colony in the long run! 67.169.80.238 (talk) 05:40, 16 December 2013 (UTC)[reply]

Maybe these robots raised spacenoids would want to drop space colonies and big rocks on Earth. Sieg Zeon! 202.177.218.59 (talk) 06:05, 16 December 2013 (UTC)[reply]

The short answer is that no amount of money can do it - I don't think anyone has plans to build a 20 km span of more or less unsupported suspension bridge anytime soon, which is what that space environment is (at least, if it has gravity anything like Earth). The somewhat longer answer is that we'd build it out of space resources, which would be on their own monetary system. For example, there's only a very limited amount of water at the poles of the Moon. If it ends up being owned by, say, the PRC, then they can use it for free, nobody else can use it at any price. So you'd have to have a market, and then it would depend on exchange rate, which could vary greatly. The value of a ton of water in space is pretty much "a ton of water in space" :) The idea of taking that many resources out away from Earth is absurd though - if we had the technology to use that much stuff in space, we'd have the technology to make it in space. Wnt (talk) 05:05, 18 December 2013 (UTC)[reply]

Formation of memories

If I give you a sequence of numbers to remember, say 1548, what changes in your brain (in the space of a second!) so that you can recall that sequence? Surely no new synapses form in that space of time? Gene expression also, can't respond so quickly? — Preceding unsigned comment added by 78.148.110.243 (talk) 16:38, 15 December 2013 (UTC)[reply]

I haven't kept up well with developments here, but [2] still references a 2008 publication [3] which is free with registration. Only somehow I forgot the password, so until I check my e-mail I'll leave it there. (Come to think of it, odds are it was whatever it said in the last forgotten password note sent to my email...) The gist, though, is that you can let calcium ions into the cell. My impression is that in general, calcium ions are a sort of alarm signal of a damaged cell membrane, because if allowed to lurk around long enough they would tend to create problems (insoluble compounds) and so every cell pumps them out. But in cells that respond to stimuli (not just neurons, but many other types) they can also be used then as a way of giving a signal that something has changed, and then the cell works pretty quickly to get them back out, but it still can be slow enough to take many seconds. Wnt (talk) 18:11, 15 December 2013 (UTC)[reply]

(ec) The answer is not well known for humans. You can start at this section of our article on human memory. Generally, most scientists believe that there is a biochemical change at the very micro-microscopic level; and a corresponding emergent change in electrical response and cell-structure at the cellular level (still microscopic, but much larger than the former). But this topic is difficult to study, and answers are subject to change as scientists learn more.

Contrast this with a computer, which is much simpler (and for which we know the design): memory is committed and stored when a finite state machine uniquely addresses a specific part of an array of storage circuits - and this allows the circuit to store electrons on a capacitor (or to magnetize a crystalline substrate, or to etch a visible mark in a reflective layer). In these machines, there is always a state machine that controls where information will be committed; there is always some physical change that occurs at a specific spatial location; and the information is stored in serial form, one bit at a time. This is very convenient for the design of machines, and as a computer scientist, I commonly make similar assumptions about human memory; but in fact, we have no present ability to prove that human memory is addressable, or serialized, or spatially localized; and we cannot prove exactly which physical change corresponds to storing memory. Nimur (talk) 18:15, 15 December 2013 (UTC)[reply]

As Nimur says, surely something physical changes, at at least the molecular level, for you to be able to store and recall memories; however we're really unsure how it works exactly. There is a Wikipedia article titled Neuroanatomy of memory which does give you some broad strokes. --Jayron32 22:28, 15 December 2013 (UTC)[reply]

To begin with, you have to be aware that there are short-lasting forms of dynamic memory that allow information to circulate long enough to affect brain structure. One of the most basic is the so-called phonological loop -- a fancy term for the fact that we can hold information in our minds for a period of time by repeating it to ourselves over and over again. The best candidate for a long-lasting synaptic change mechanism is a process called long-term potentiation, usually abbreviated LTP. LTP can be induced by signals that last less than a second, though longer-lasting signals produce much stronger traces. It has two phases, an early phase that lasts a few hours and does not depend on protein expression, and a second "consolidation" phase that does depend on protein expression and can last for months or longer. Looie496 (talk) 00:38, 16 December 2013 (UTC)[reply]
This reference should answer the question (it's open access). Arnsten et al. (2010). Dynamic Network Connectivity: A new form of neuroplasticity. Trends Cogn Sci. 14(8):365-75.. The primate experiments are based on spatial working memory but it's very likely that verbal working memory works in a similar way in terms of synaptic fundamentals. Markr4 (talk) 10:26, 16 December 2013 (UTC)[reply]

Libido

Is libido reduced by only chronic tiredness or can it also be affected by temporary tiredness after alot of physical activity, lack of sleep etc? — Preceding unsigned comment added by Clover345 (talk • contribs) 22:12, 15 December 2013 (UTC)[reply]

We cannot give any advice or diagnosis of any medical conditions, in the specific or in the general. You can read the Wikipedia article titled Libido which discusses things which affect libido. --Jayron32 22:25, 15 December 2013 (UTC)[reply]

I wasn't asking for medical advice. It's a general question related to human biology. — Preceding unsigned comment added by Clover345 (talk • contribs) 23:54, 15 December 2013 (UTC)[reply]

The answer is so obviously yes that I have a hard time seeing anything evil about the question (or anything valuable either)> Looie496 (talk) 01:22, 16 December 2013 (UTC)[reply]

And what is the biochemical reason for this? Clover345 (talk) 14:03, 16 December 2013 (UTC)[reply]

Have you had a look at the article libido? Dmcq (talk) 14:55, 16 December 2013 (UTC)[reply]

December 16

Chopper crash

Are there some subtle early signs of an impending engine and/or main transmission gearbox failure in a turbine-powered helo (in particular, a heavy, multi-engine, twin-rotor type such as the Sea Knight or the Chinook)? If so, what are they? Thanks in advance! 67.169.80.238 (talk) 05:45, 16 December 2013 (UTC)[reply]

The generic early warning sign of just about any sort of drive system failure is an unusual noise or vibration. Looie496 (talk) 06:32, 16 December 2013 (UTC)[reply]

Large aircraft, including helicopters, usually have an indicator on the instrument panel that provides a continuous display of engine vibration. Also, engines in this class of aircraft are equipped with magnetic chip detectors. Engine and gearbox oil passes over the chip detector on its return to the oil reservoir or oil cooler. Any chips of iron or steel that have been picked up by the oil will be captured by the magnetic chip detector which then transmits a warning signal to the instrument panel to warn the crew that the engine or gearbox is breaking up. Dolphin (t) 07:00, 16 December 2013 (UTC)[reply]

See Structural health monitoring for the general topic. Vibration health monitoring is very effective at detecting incipient problems in all sorts of machines. Dmcq (talk) 14:36, 16 December 2013 (UTC)[reply]

Thanks, everyone! But might there be signs so subtle and generic that they might be mistaken for something else? Also, is it possible for the engine or gearbox to fail catastrophically without first triggering the chip detector? Because I'd like my characters to suspect some other less serious problem, and then be blindsided by a catastrophic failure, if possible. 67.169.80.238 (talk) 07:41, 17 December 2013 (UTC)[reply]

[Banned user's comment removed]

Mining equipment

How heavy is a typical bulldozer used in surface mining? Would it be possible for a heavy-lifter helicopter such as a Chinook or a Super Stallion to carry one of those as a sling load? Thanks in advance! 67.169.80.238 (talk) 06:13, 16 December 2013 (UTC)[reply]

I don't know the numerical answer, but a Google image search for chinook carrying a bulldoxer to find multiple examples of that specific case being possible. DMacks (talk) 06:26, 16 December 2013 (UTC)[reply]

Well, Boeing's specs for the Chinook give a maximum lifting capacity of "more than 7 tons". Meanwhile, Caterpiller's lightest dozer appears to weigh over 8.5 tons, and our Caterpillar D11 article says it's a "large bulldozer ... mainly used in the mining industry" which weighs over 130 tons. Clarityfiend (talk) 07:55, 16 December 2013 (UTC)[reply]

Yes, I don't see any bulldozers in those images, just a few relatively lightweight excavators.--Shantavira|^{feed me} 10:35, 16 December 2013 (UTC)[reply]

There's certainly some helicopters that could carry a normal medium sized bulldozer, I know of one person who was getting a big Russian helicopter to carry something of about that weight. Surface mining though sounds like it uses super heavyweight equipment like drag line excavators. Dmcq (talk) 12:35, 16 December 2013 (UTC)[reply]

The Mil Mi-26 holds the lift record of 56,768.8 kg (equals 62 of those funny American tons or nearly 56 proper Imperial ones). Presumably most of that wasn't underslung. Here is a picture of a bulldozer being loaded inside an Mi-26 and here is a video of an Mi-26 lifting an underslung Chinook. Alansplodge (talk) 14:01, 16 December 2013 (UTC)[reply]

I just found this YouTube video of an Mi-26 lifting a "350 John Deere hoe" which (if I've got the right thing) weighs 77,970.9 lb or 35,367 kg.[4] Alansplodge (talk) 14:14, 16 December 2013 (UTC)[reply]

Thanks, everyone! So, a construction dozer could be carried, but a mining dozer would be way too heavy, right? 67.169.80.238 (talk) 07:43, 17 December 2013 (UTC)[reply]

You might be interested in this article [5] about the possibility of using airships instead of planes. They only carry 50 tons but could probably be scaled up to more than a transport plane could carry. Dmcq (talk) 11:00, 17 December 2013 (UTC)[reply]

The Hindenburg and Graf Zeppelin could have carried a D11 bulldozer each. --Carnildo (talk) 03:56, 18 December 2013 (UTC)[reply]

The Climate Reality Project versus The Weather Conspiracy report (book 1977) on the coming of the new ice age.

CIA's indepth analysis of future weather predictions tends to have more convincing evidence that our future weather leans towards an Ice Age.

I always use your site because it is more accurate than say a group that sponsors a subject and therefore has a vested interest in the subject. Example: you don't ask a question on religion because you only get answers pertaining to the interest of a certain denomination. — Preceding unsigned comment added by 70.194.130.31 (talk) 14:05, 16 December 2013 (UTC)[reply]

I took the liberty of creating a new section for this, but I'm not terribly certain what the question is... Alansplodge (talk) 14:11, 16 December 2013 (UTC)[reply]

You don't go to the CIA to get your health checked or ask them about fertilizer do you? What on earth makes you think they are a reliable source about climate? What has it got to do with their remit? At least the army has to do some planning about possible temperatures in the future in regions it might operate in! Dmcq (talk) 14:43, 16 December 2013 (UTC)[reply]

By the way in 1977 cooling would have been the correct prediction, just scientists have learnt a lot more since and it is practically certain temperatures are headed the other way. Dmcq (talk) 14:51, 16 December 2013 (UTC)[reply]

Even that is probably over-stating the 1970s view. See our article on global cooling:

Global cooling was a conjecture during the 1970s of imminent cooling of the Earth's surface and atmosphere culminating in a period of extensive glaciation. This hypothesis had little support in the scientific community, but gained temporary popular attention due to a combination of a slight downward trend of temperatures from the 1940s to the early 1970s and press reports that did not accurately reflect the full scope of the scientific climate literature, i.e., a larger and faster-growing body of literature projecting future warming due to greenhouse gas emissions.

And particularly the footnote from that article: Peterson, T., Connolley, W. and Fleck, J. (September 2008). "The Myth of the 1970s Global Cooling Scientific Consensus". Bulletin of the American Meteorological Society 89(9):1325–37. In the 1970s, there were more scientific papers predicting warming than cooling, and the papers predicting warming were cited more often. Indeed, it wasn't even close. TenOfAllTrades(talk) 15:03, 16 December 2013 (UTC)[reply]

And that paper is nonsense because climatology wasn't even an academic science at that point. Even in 1979, Carl Sagan's Cosmos juxtaposed increased albedo of clear cutting with CO2 from fossil fuels and came to no conclusion. There certainly scientists predicting a cooling trend just as by 1980, there were scientists predicting a warming trend. In general though, we are between interglacial periods. We will return to glaciation but not in anyone's lifetime. The current focus of climatology is about 100 years from now. But thousands of years from now, it is quit clear that glaciation will re-occur. The question isn't "if", it's "when". --DHeyward (talk) 05:06, 17 December 2013 (UTC)[reply]

And that post is nonsense because I worked with people called climatologists employed by the Australian government in the 1970s. HiLo48 (talk) 05:33, 17 December 2013 (UTC)[reply]

[banned user]

Yep. Great library. I remember the Encyplopedia Britannica from 18something, with one volume missing. Gee the librarian hated that. HiLo48 (talk) 09:20, 17 December 2013 (UTC)[reply]

There's also some kind of combination idea where warming causes an ice age. I remember reading this shaggy dog story just once maybe fifteen or twenty years ago, in Nature I think, maybe Science, where supposedly the melting of all the Arctic ice was going to turn it into a "freshwater sea" at the surface where algae or plants would flourish, then sink to the salty bottom as a carbon sink until suddenly we were headed for global glaciation. Anyone remember that one? (I'm not saying it's true 😃) Wnt (talk) 21:31, 16 December 2013 (UTC)[reply]

I worked for Australia's Bureau of Meteorology in the 1970s. It's a government body, no commercial involvement. At that time the popular press would sometimes talk of the coming ice age, but the scientists I knew were beginning to predict major climate change with a tendency to much greater variability and a warming trend, but with that trend often to be masked by the massive variability. The longer I have watched, the more respect I've gained for those folks. HiLo48 (talk) 22:49, 16 December 2013 (UTC)[reply]

Astronauts' seats on their way back home

To withstand G force, an astronaut is placed inside a seat cushion made exactly to fit his/her body form.

How do they transfer their seat cushions between different vehicles? e.g., Expedition 1: flight up: Soyuz TM-31; flight down: STS-102-- Toytoy (talk) 15:25, 16 December 2013 (UTC)[reply]

Not sure, but "seat cushions" could just be some small inserts which are highly portable. StuRat (talk) 15:40, 16 December 2013 (UTC)[reply]

Ask the user Bubba73. He knows a lot about the space program and its history. ←Baseball Bugs ^{What's up, Doc?} carrots→ 15:44, 16 December 2013 (UTC)[reply]

Space Shuttle Orbiter no longer flies, but there is still a lot of information available. NASA Human Space Flight Shuttle Reference says: "Each mission and payload specialist's seat has two shoulder harnesses and a lap belt for restraints. The specialists' seats have controls to manually lock and unlock the tilt of the seat back. Each seat has removable seat cushions and mounting provisions for oxygen and communications connections to the CAPS. The specialists' seats are removed and stowed in the middeck on orbit. No tools are required since the legs of each seat have quick-disconnect fittings. Each seat is 25.5 inches long, 15.5 inches wide and 11 inches high when folded for stowage."

The Pilot and the Commander have adjustable seats (sort of like a luxury sedan!) But, I see nothing about custom-molded seats; I never heard of such a feature. In fact it was a feature of the Soyuz: "The liners are made preflight, individually molded to fit each person's body -- this ensures a tight, comfortable fit when the module lands on the Earth. When crew members were brought to the station aboard the space shuttle, their seat liners were delivered with them and transferred to the existing Soyuz spacecraft as part of crew handover activities." No doubt, if you read mission transcripts and schedules, you can find out exactly when these seat liners were transferred. Nimur (talk) 16:07, 16 December 2013 (UTC)[reply]

The seat liners are not very thick, as can be seen here and here. Part of the process of making one can be seen here.

NASA utilized a similar concept in the Mercury spacecraft, as detailed in This new Ocean, chapter 6-4 and elsewhere in the document. WegianWarrior (talk) 16:26, 16 December 2013 (UTC)[reply]

The maximum g force one should experience on a space shuttle is 3g, per g-force, both on launch and reentry. On an ordinary Soyuz launch, g force is up to 4.2g (per Yuri Gagarin Cosmonaut Training Center here) and up to 5g on reentry (ref). But various cosmonauts have experienced much more acceleration aboard various flights: the occupants of Soyuz 7K-ST No.16L experienced somewhere between 10 and 17g when their launch escape tower fired; the occupants of Soyuz TMA-1 experienced about 10g on reentry; and the occupants of Soyuz 7K-T No.39 endured an astonishing 21g. So I don't think you need a custom cushion on a space shuttle, and really it's there on the Soyuz to handle all those scary excursions from normal flight. It is true that cosmonauts frequently land in a different Soyuz than they took off on (and have done since at least the Salyut-7 period; e.g. Soyuz T-11), so your question still holds - I think they move the pad, but I don't have a reference for that. edit: nevermind, Nimur addressed that. -- Finlay McWalterჷTalk 16:57, 16 December 2013 (UTC)[reply]

Deadly overdose of SSRI's

Is it possible?--78.156.109.166 (talk) 20:11, 16 December 2013 (UTC)[reply]

Some information is given at Selective_serotonin_reuptake_inhibitor#Overdose, with other mention in the article of effects including heart attacks being conceivable, but not very likely. Given the drug-specific nature of the overdose effects it may be a bit misleading to comment about the category as a whole rather than each specific compound. Wnt (talk) 20:30, 16 December 2013 (UTC)[reply]

It says that deaths have occurred in massive overdoses (only in massive ones, right?), so that means it is almost impossible to die from an overdose, if you don't take a massive one (ie. it is almost impossible to die from SSRI overdose, unless you take a massive one), right? And on da.wikipedia.org it says it is almost impossible to die from SSRI overdose, so is that true?--78.156.109.166 (talk) 20:41, 16 December 2013 (UTC)[reply]

It will also depend on what is meant by dying from an overdose, whether what is meant is direct poisoning of the liver or kidneys, central nervous system overload, or a side effect like a stroke or heart attack caused by overstimulus or high blood pressure. See also serotonin syndrome. μηδείς (talk) 21:09, 16 December 2013 (UTC)[reply]

Read, for example, the side effects of Zoloft, which can include anaphylaxis, heart attack, and liver failure. Presumably an overdose will exaerbate some of these side effects. No LD50 is listed for this drug, but other ssri's may have one listed. μηδείς (talk) 00:35, 17 December 2013 (UTC)[reply]

Basically agreeing with others -- yes, it is certainly possible. The most common mechanism of death, as I understand it, is overheating produced by loss of the ability of the body to temperature-regulate. High doses of serotonergic agents followed by exposure to intense heat is particularly dangerous. That's why diet drugs such as Phen-fen -- which acts mainly on serotonin -- have been banned. Looie496 (talk) 01:02, 17 December 2013 (UTC)[reply]

Phen-fen was banned because of the cardiac fibrosis it was producing, which is via its direct agonism at cardiac 5-HT2B receptors. Serotonergic drugs are still being developed for appetite suppression, see lorcaserin. Markr4 (talk) 14:06, 17 December 2013 (UTC)[reply]

How do you know what to eat these days?

How do you know what to eat these days? A few days ago I saw a program on TV that said to cut out seven foods. Three of them were eggs, dairy, and peanuts. Immediately after that, there was a program on about brain health, and it said DO eat eggs and dairy. And then there was an item on NPR that said that it is good to eat nuts every day, and the specifically included peanuts. What is a person to do? Bubba73 ^{You talkin' to me?} 22:17, 16 December 2013 (UTC)[reply]

Study science, especially but not exclusively nutrition. Make up your own mind. My general rule is "a little of everything I like, all in moderation". HiLo48 (talk) 22:44, 16 December 2013 (UTC)[reply]

Don't believe everything they say on TV. 86.128.183.4 (talk) 22:51, 16 December 2013 (UTC)[reply]

...especially advertisements or programs sponsored by food companies. HiLo48 (talk) 22:57, 16 December 2013 (UTC)[reply]

Cut out everything you really enjoy eating. You may not live any longer but it will certainly seem a lot longer. Richerman (talk) 22:59, 16 December 2013 (UTC)[reply]

In Sleeper (1973 film) Woody Allen wakes up in the future and is told to smoke and draw the smoke deep into his lungs as it is one of the healthiest things for his body! I don't think that is going to happen but yes I sympathize with your frustration about food advice. The food companies don't exactly see it as their job to help either. Dmcq (talk) 23:04, 16 December 2013 (UTC)[reply]

There are three issues here:

1) Psuedoscience. That is, any crazy nut job with a diet book can make diet claims. These should be completely ignored.

2) Paid advocacy. If a study on eggs is funded by the egg council, I'd ignore it. Only read unbiased studies with no conflict of interest.

3) Lack of scientific consensus. You will hear some studies say food X is good while others say it is bad. Well, all foods have good and bad to them, but some have far more good and some have far more bad.

Now let me address the 3 you mentioned:

A) Eggs have lots of good stuff and also lots of bad stuff, like cholesterol. If you just eat egg whites, you don't get much of the good or the bad. So, I'd say eat them in moderation. However, if you're a vegetarian for whom eggs are acceptable, you might want to eat more of them to get your protein and other nutrients most people get from meat.

B) Dairy can cause problems for those who are lactose intolerant. That's a substantial portion of the population, but not everyone. So, if that's not you, then dairy is OK. It's not great, since the calcium in milk isn't all that easy to absorb (adding vitamin D helps) and milk-based drinks are among the few with fat in them. But, it does have lots of nutrients. So, again, I'd say to consume dairy in moderation, and avoid dairy with lots of added sugar, like chocolate milk.

C) Peanuts. Some people have severe peanut allergies. If you don't, then peanuts are a decent food, so long as you get them without salt or sugar added to them. Compared to many other sources of protein in the Western diet, like red meat, they are a distinct improvement. They can also have a laxative effect. So, go ahead and eat peanuts. And peanut butter is popular with kids, but get the natural kind, without partially hydrogenated vegetable oils (trans fats).

And before anybody bitches at me, nutritional advice is not considered to be medical advice. StuRat (talk) 23:09, 16 December 2013 (UTC)[reply]

Yes, it goes without saying that if it's edible, someone will be allergic to it. --Auric talk 23:15, 16 December 2013 (UTC)[reply]

I think it's important to point out that "paid advocacy" is not solely limited to the "pro" camp. Yes, pro-egg results paid for by the egg board might be dodgy. But likewise are anti-egg results paid for by an animal rights group. (Regardless of your agreement with them on ethical issues, PETA is not an unbiased source for nutritional advice.) Even "independent" experts can have a financial stake. Some celebrity doctor is promoting a nutrition book? Even if he is thoroughly postnomialed and holds a position with a university or hospital, he may be playing up controversial advice to get people to purchase his book. (I am perpetually bemused by people who don't trust "the commercial food industry" because of their profit motive, but fail to realize that "natural/alternative foods" and associated advice are a multi-billion dollar industry in-and-of themselves.) - To the more general question, there's no easy answers in the diet/nutrition field. Anyone promoting a "simple" or "easy" answer probably doesn't know what they're talking about, and may be trying to hoodwink you. The media is really good at focusing on the results of single studies, rather than the state of research taken as a whole, which readily leads itself to strong recommendations which change from article to article. Ask someone without an agenda to push about the state of research taken as a whole, and you'll likely get an answer similar to "It's complex and probably depends on your situation. We don't really know for certain. Here's a ton of research, each with semi-contradictory conclusions. We're still trying to figure out how everything ties together. It may take a while." Someone who recognizes that this stuff is complex is way more trustworthy than someone who writes simple "These X foods may be killing you!" or "Eat these Y foods for better health!" articles, which often aren't worth the electricity they're written on. -- 160.129.138.186 (talk) 16:54, 17 December 2013 (UTC)[reply]

I'm not really asking for any specific nutritional or medical advice. I was wondering what to do about all the conflicting reports. Bubba73 ^{You talkin' to me?} 01:23, 17 December 2013 (UTC)[reply]

The answers above still exist if you find them useful. Other answers to your clarified question can be added. Be aware wickwack is fooling with this thread and will be reverted if he edits it again. μηδείς (talk) 02:42, 17 December 2013 (UTC)[reply]

In trying to answer this question I've rewritten my response three times, so I think I need to take a broader view. Studies will be done by different people for different reassons, often not maliciously. A report that says "don't eat eggs" may actually be saying "eggs are high in substance x, which we already have too much of in our diet". Now, if your diet isn't high in substance x, you have nothing to worry about, but the idea behind the report was that if we warn enough people away from substance x, then substance x overconsumption in the general populace will go down.

So it's like misinformation, only well-meaning. People do things like this by accident all the time. Same goes the other way. "eat more eggs because the general populace doesn't get enough of substance y!" They're trying to compensate for underconsumption of substance y by getting everyone to eat more of it.

And this is only one reason for why reports don't state the facts bluntly and directly. Blunt, direct facts are boring and unengaging for nearly everyone, and will achieve nothing. So you've got to place it in a context. and if you want viewers, you'd better be saying something other than "eggs are okay; do nothing differently", because no-one will watch that.

Honestly, you could type for hours on the subject of why reports aren't accurate. There's a process for how to think about reports to get the most real information out of them: Critical thinking. — Preceding unsigned comment added by 86.141.185.121 (talk) 10:11, 17 December 2013 (UTC)[reply]

Searching for "eggs, dairy and peanuts", the first results I get are for the "Virgin diet", one of which has the title "The Virgin Diet: Drop 7 Foods, Lose 7 Pounds, Just 7 Days". So the program that advised you to cut out seven foods may well have been advocating that diet. Losing weight fast has nothing to do with eating healthy, the recommendations differ because they try to achieve different goals. Ssscienccce (talk) 15:19, 17 December 2013 (UTC)[reply]

Other good rules about diets are:

Just about any diet can help you lose 7lb in 7 days. The problem is that most of this is easy "water loss" that always happens when you start dieting and makes it seem like you lost weight amazingly well - but comes right back on again the moment you stop dieting. The question isn't how much you lose in the first 7 days - it's how much you'll lose in the 10th week - and whether you can tolerate the diet well enough to stay on it indefinitely to keep your body at whatever new low weight you are happy with.
You can't safely and sustainably lose much more than 1lb per week. If you try to lose weight faster than that, your body may switch into "starvation mode" and you'll find it yet harder to lose weight. So any miracle or non-miracle diet that tells you anything other than that is suspicious in the extreme. If you need to drop 50lb - plan on it taking you an entire year. Systems like stomach bands and liquid-only diets that force you to eat dramatically less will help you to shed weight much faster - but they are also dangerous. For this reason, you can safely dismiss *ANY* fad diet without even bothering to read it.
Any diet that talks about 'flushing toxins' or things like that is most likely to be nonsense.
Your weight bounces up and down by several pounds each day - and most bathroom scales are only accurate to maybe +-2 or 3 lbs. So, again, claims that you'll lose 7lb in one week can be fulfilled by nothing more than wishful thinking and picking the difference between the highest number you saw one week and the lowest number you see over that week. This allows people to convince themselves that the chocolate and whipped cream diet is working - when it's really not.
As someone said in answer to another question below: All carbohydrate have around 4 calories/gram, all protein has 5.7 calories/gram and all fats have 9.3 calories. So, for example, it doesn't matter whether you eat the most sugary breakfast cereal or super-healthy cardboard-flavored stuff...it's all 99% carbohydrate - so all that matters is how much it weighs.
Sticking to a diet is about managing hunger pangs, and foods that are slower to digest are better because you fill fuller, longer. Nuts have the same calories per gram as 100% sugar candies - but nuts stay in your gut for a long time, where candy goes straight into your blood stream and is gone within minutes. So if you stick with less-easily-digested food, you'll feel more satisfied. The trendy word for this is "glycemic index". That doesn't affect how much of a food you can eat to stay on track with your diet - only that if you pick the right foods, you should be less hungry
One point of body fat is 3,700 calories. If over a week, you eat 3,700 calories than your body needs - then you'll put on a pound and if you eat 3,700 calories less, you'll lose a pound. It really is that simple.

So, putting this together and crunching the numbers. to lose weight sustainably - shoot for 1lb per week so you have to cut 530 calories out of your daily intake. Which means 130 grams of carbohydrate or 90 grams of protein or 60 grams of fat - or some combination of those things.

Obviously there are other aspects to a good diet than weight loss - so once you're at a good weight, you can start considering things like vitamins, sodium content and cholestorol. From a health perspective, getting your weight right is usually the highest priority thing...but the other things matter too.

SteveBaker (talk) 18:57, 17 December 2013 (UTC)[reply]

I disagree with #7. First, here's what I think you were trying to say, with the typos fixed: "One ~~point~~ pound of body fat is 3,700 calories. If over a week, you eat 3,700 more calories than your body needs - then you'll put on a pound and if you eat 3,700 calories less, you'll lose a pound. It really is that simple."

It's not that simple. This assume 100% efficiency in the digestion process. Digestion is never 100% efficient, and the efficiency varies wildly. For example, eating a lot at once tends to cause digestion to be more inefficient, as in a hot dog eating contest. Certain combos of food and food preparation methods can increase digestive efficiency. Then there are fat blockers, etc., specifically designed to interfere with digestion. StuRat (talk) 08:20, 18 December 2013 (UTC)[reply]

See Salt Sugar Fat: How the Food Giants Hooked Us: Michael Moss: 9781400069804: Amazon.com: Books and ISBN 9781400069804.

—Wavelength (talk) 20:02, 17 December 2013 (UTC)[reply]

Make sure your body puts what you eat to good use by getting enough exercise. Half an hour of running per day is the absolute minimum to maintain a top level fitness. If you eat a meal containing a lot of saturated fats and then do a blood test, you can actually see the fat floating in your blood in the tube. But if you exercise some time before such a meal, you'll have far less fat in your blood. Count Iblis (talk) 21:01, 17 December 2013 (UTC)[reply]

Eat food. Not to much. Mostly plants. I personally take tips from the Mediterranean diet. And I completely endorse the replies above advocating critical thinking. Vespine (talk) 00:45, 18 December 2013 (UTC)[reply]

See "In Defense of Food", by Michael Pollan.

—Wavelength (talk) 01:07, 18 December 2013 (UTC)[reply]

December 17

How are walnuts and Brazil nuts shelled in bulk?

It being Christmas, I've bought nuts to eat (quite why we British eat nuts at Christmas but not at other times is another question). Among them are Walnuts and Brazil nuts. For years I've wondered how these are produced shelled; the Brazil nut article even has a picture of shelled Brazil nuts. You struggle with the nutcrackers and maybe get a whole half walnut and 3 bits of the other half, your Brazil nut, after much work, might be 85% whole with 15% shards, yet you can buy bags of shelled walnuts (and pecans; same question and another "shelled" picture). In my experience the only nuts that can be shelled easily, giving a whole nut, are hazelnuts and (if you have a decent nutcracker) almonds. So how are shelled nuts produced? My private theory about tame worms that eat nutshells but not nuts is probably not the answer. Tonywalton ^Talk 00:14, 17 December 2013 (UTC)[reply]

Once again, youtube is your friend. μηδείς (talk) 00:23, 17 December 2013 (UTC)[reply]

Mmm. "A great big machine does it" seems to be the major theme there, unless I've missed some details. "Walnuts in, shells out at one place and walnuts out elsewhere". I'd kind of worked that out, but what happens in the middle? Thanks anyway. Tonywalton ^Talk 00:32, 17 December 2013 (UTC)[reply]

Well, it turns out that inside those machines there are these rather clever tamed worms that eat the shells... Actually, they will almost certainly use rollers to do the cracking. I assumed that some of these videos would show detail, but I am too busy to watch them myself. μηδείς (talk) 00:40, 17 December 2013 (UTC)[reply]

Speaking of worms, what's worse than biting into an apple and finding a worm? (And if you don't know the answer, you may have been in your shell too long.) ←Baseball Bugs ^{What's up, Doc?} carrots→ 9:19 pm, Today (UTC−5)

Two worms of course! 8.17.117.40 (talk) 14:32, 17 December 2013 (UTC)[reply]

Surely finding the two worms is far better than finding only one of them? Anyway the answer is half a worm. ;-) Dmcq (talk) 14:49, 17 December 2013 (UTC)[reply]

Sounds to me, as if the OP is using the cheap working-class [hazel/walnut cracker pliers ] meant for hazel, walnut and other tradition round nuts. There is no way to apply controlled force. Brazil, amound, etc, nuts are not round. They also need, controlled axial force to crack the nut with out crushing the kernel. I have just gone through all my kitchen draws to find my own, that cracks brazil's etc, perfectly, to photograph and upload -but it gone. I don't know if it got mislaid during our last house-move or if one of the wife's relatives took a fancy to it (they tend to treat my home, garage and garden shed as their local hardware and ironmongers shop) ( instead of installing a new cocktail bar, I should have set up a point-of-sales-counter ... hiss). Harrods of London is bound to stock such an item. This is the industrial, bench mounted and hand operated type. [6] Wrestling with all ones might, armed only with a pair of pliers that crushes the kernel as soon the the shell gives, is using the wrong tool for the job.--Aspro (talk) 17:26, 17 December 2013 (UTC)[reply]

Draws? That's the second time you've used that. Is it dialectal? I wasn't able to find a dictionary entry with that meaning. μηδείς (talk) 18:18, 17 December 2013 (UTC)[reply]

Common misspelling of the word "drawers", resulting from some people's pronunciation of that word with the "er" syllable softened to the point of oblivion. SteveBaker (talk) 14:03, 18 December 2013 (UTC)[reply]

This is getting silly. A drawer can be a sliding container, or someone that draws stuff out or drawers can refer to a women’s certain undergarment. I simply stated that I went through my draws that I normally draw stuff out off. Some of the containers don't 'draw' or slide out – it is stuffed into boxes (many boxes in my case). So: When I said I when through my kitchen draws... I meant what I said: I went through my kitchen draws. It may be a bit like Americans saying, they fill up at the 'gas' station, when the fuel they are buying is actually in the liquid phase. They presume everyone has the sense to fill in the missing 'oleine'. This grammatical, syntactical transgression which is going off on a tangent doesn't add any benefit to the OP's question.So don't be so pedantically irritating ;-) --Aspro (talk) 16:02, 18 December 2013 (UTC)[reply]

I asked out of curiosity. Your defensiveness is unwarranted. Is this typical where you live? μηδείς (talk) 17:27, 18 December 2013 (UTC)[reply]

Approximately how much would the increased muscle on each arm weigh if:

a person who weighed 215 lbs became able to do five regular pull-ups when formerly he could only do five "150 lbs" pull-ups on a balance assist machine? Is it about half a pound per arm or what? Assume he remains close to 215 lbs. Thanks174.52.9.38 (talk) 04:40, 17 December 2013 (UTC)[reply]

In other words, how many pounds of muscle and supporting blood vessels does it take to do a 65 lb pull-up? μηδείς (talk) 04:51, 17 December 2013 (UTC)[reply]

I don't think it's as simple as that. First, the increased muscle mass is likely offset by a decrease in fat. Second, existing muscle can also be made stronger without increasing it's mass much. You might wonder why this extra strong muscle isn't the default state. I believe "out of tone" muscles use less energy, and evolution seems to have programmed our bodies to behave as if starvation is always just around the corner. StuRat (talk) 09:10, 17 December 2013 (UTC)[reply]

Then you should calculate a range. The upper of jus adding muscle without fat loss, and the lower with concomitant fat loss. μηδείς (talk) 12:29, 17 December 2013 (UTC)[reply]

I know that the force that a muscle can produce is proportional to it's cross-sectional area. The mass of the muscle is proportional to it's volume. The length of the muscle is determined by the length of the bones - so it won't change significantly as a person trains to lift bigger weights. So I'd expect the weight of the muscle to increase as the square of the amount of force it can exert. You're asking for a roughly 30% increase in force - so I'd expect to need to add about 70% (1.3x1.3=1.69) to the mass of the muscles involved. However, we don't know the mass of the muscles to start with - we don't know how well "toned" they are to start with - and (as others have pointed out), when you work harder, you tend to lose fat - which may somewhat compensate for the muscle increase. If I had to put a number on the weight of a muscle...it's about the same density as water, and an untrained upper arm muscle looks to me to have about a 50 cm² cross-section and a length of around 20cm - so if we approximate it as a cylinder, we have about 1 liter of volume - which is 1kg or so. So the maximum weight gain is probably 700g for each arm...3lbs maybe. I'd say that a 3lb increase is the most you'll see - the least could easily be zero. SteveBaker (talk) 15:58, 17 December 2013 (UTC)[reply]

I realize that your 1.5 lbs per arm is meant as an upper limit, but couldn't the upper limit be refined downward? Because that's like a quart and a half of buff per arm which sounds like a real strong guy. Thanks again.174.52.9.38 (talk) 20:17, 17 December 2013 (UTC)[reply]

Oops, it would be a pint and a half, not a quart and a half--probably a reasonable upper limit.174.52.9.38 (talk) 20:20, 17 December 2013 (UTC)[reply]

SteveBaker, how do you arrive at M ~ F²? If A ~ F and M ~ A⋅L with L constant, shouldn't M ~ F? -- ToE 21:25, 17 December 2013 (UTC)[reply]

I doubt this was intended as a trick question, but it would make a good one. The fact is that the arm mass need not increase at all. A pull-up depends partly on the biceps (which are in the arm), but much more (the exact proportions depend on the type of pull-up) on the latissimus dorsi muscles (known as "lats", which are in the back. Looie496 (talk) 17:30, 17 December 2013 (UTC)[reply]

I took the question as the OP asking, given I can now do these pull-ups, how much muscle weight can I claim to have added? That would apply even if it were to other parts of the body. μηδείς (talk) 18:14, 17 December 2013 (UTC)[reply]

I think it's a lot more complicated than strength. I do a lot of pull-ups. I can do loads of sets of 6-8 reps; I usually stop when I get to 80-100 through boredom. I'm 82kg. There are lots of body builders at the gym who are way stronger than me but struggle with pull-ups and chin-ups. These guys weigh around 100kgs. Personally, I find pull-ups a lot easier than chin-ups, but then I tend to only do pull-ups. For me, a lot of the pull-up comes from holding the torso firm. When I've used those balance assist machines, I tend to collapse more, I guess because I'm kneeling on the platform and I find it much more difficult to hold the "tonic". --TrogWoolley (talk) 23:30, 17 December 2013 (UTC)[reply]

Conservation of energy in protein decomposition

The formation of proteins from amino acid requires energy. Then, according to the theory of conservation of energy, the decomposition of proteins into amino acid should produce energy. If so then why decomposition of protein in stomach by enzyme doesn't liberate much amount of energy (heat)?

You are right. Since the protein breakdown (also called Proteolysis) is a catabolic process, it should release energy. In fact, the breakdown of proteins in our stomach release energy, but the amount of energy released is not enough to cause any discomfort (or pain) in the stomach. Proteins in the diet serve primarily to build and maintain cells, but their chemical breakdown also provides energy, yielding close to the same 4 calories per gram as do carbohydrates. Carbohydrates have an average value of 4.1 calories per gram, proteins have 5.7 calories per gram, and fats have an average of 9.3 calories per gram. Scientist456 (talk) 15:07, 17 December 2013 (UTC)[reply]

According to the peptide bond article, breaking the bond releases 2–4 kcal/mol of energy. The molar mass of amino acids varies, glycine is only 75 g/mol, tryptophan 204 g/mol. Based on those figures, I'm guessing the breakdown of 100 g of proteins into amino acids would release between 1 and 6 kcal (depending on the specific amino acids). This is an insignificant amount compared to the more than 2000 kcal per day that an average person consumes (and which is ultimately released as heat). (the kcal I use is the same unit as the calorie Scientist456 uses btw: the energy needed to raise the temperature of 1 kg of water by 1 degree °C) Ssscienccce (talk) 22:48, 17 December 2013 (UTC)[reply]

Oh! Thank you for correcting me. Scientist456 (talk) 01:28, 18 December 2013 (UTC)[reply]

Correcting you? I wasn't aware I did that? If you refer to the calorie vs kcal issue, your use of calorie was correct, there are two units called calorie, differing by a factor 1000. They differ in their abbreviation, for the large (or dietary) calorie it's "Cal", for the small it's "cal", so 1 Cal = 1 kcal.

If you refer to the energy from breaking down proteins, your figure of about 4 calorie per gram is correct afaik, that's the energy from breaking down the amino acids, my figure only concerned the breaking of the peptide bonds. I'm just not sure where the 5.7 comes from, a different source? Ssscienccce (talk) 12:31, 18 December 2013 (UTC)[reply]

THIS ARTICLE may be useful for OP. Scientist456 (talk) 16:40, 18 December 2013 (UTC)[reply]

One more source: This paper assumes free energy of opening of a single peptide bond in the denatured state (ΔGop,D) equal to −2.7 kcal/mole. It also mentions that ΔG_op,N values cover the range from 0.2 to 10.0 kcal/mole for twelve specific peptide bonds... Ssscienccce (talk) 05:29, 19 December 2013 (UTC)[reply]

Formation and decomposition of protein

The formation of proteins from amino acid require energy. Then does the decomposition of protein into amino acid by digestive enzymes(trypsin,pepsin etc.) in alimentary canal release energy? If so what is its amount?Singh.ssm (talk) 9:00 pm, Yesterday (UTC−5)

See the multiple responses from where you asked this same/similar question a few days ago (#Conservation of energy in protein decomposition). DMacks (talk) 9:04 pm, Yesterday (UTC−5)

Please do not ask duplicate questions. μηδείς (talk) 05:12, 19 December 2013 (UTC)[reply]

Ink and dye

What physical or chemical properties distinguish ink from dye? Is it correct to say that ink is inorganic, whereas dye is organic? Scientist456 (talk) 15:34, 17 December 2013 (UTC)[reply]

No, and the answer will probably be context-specific. I used to hang around with a yarn engineer, and they distinguished between ink and dye based solely on when it got applied to the textile. Nimur (talk) 15:44, 17 December 2013 (UTC)[reply]

Well, ink usually washes out pretty easily. A useful dye needs to have some level of permanence -- possibly after some sort of treatment (such as heat). Looie496 (talk) 17:20, 17 December 2013 (UTC)[reply]

That article makes a lot of sense, actually. An ink in that context is localized dyeing - in other words, what makes an ink an ink is that you write (or in this case print) with it. So an ink has a requirement not only to be in one place, but not to be in some other. Wnt (talk) 17:24, 17 December 2013 (UTC)[reply]

Well, one could say that dye is is nothing more than ink unless a Mordant is employed.--Aspro (talk) 17:31, 17 December 2013 (UTC)[reply]

Permanent blue ink doesn't wash out easily. According to the dictionary definition ink is a solution used to write or print something whereas a dye is used to change the colour of something completely e.g. hair dye or fabric dye. As Nimur said I think it's mostly to do with what it's used for. Richerman (talk) 17:49, 17 December 2013 (UTC)[reply]

The wikipedia article on permanent markers show that it contains the mordant as a pyrrolidone. It is not what its used 'for' or upon but the chemical properties that makes for the diffidence between and ink and a dye.--Aspro (talk) 20:24, 17 December 2013 (UTC)[reply]

The difference between dye and pigment is more clear-cut: a pigment is a solid, insoluble in the liquid "vehicle", a dye is either a liquid itself or is dissolved in a liquid. Inks can be dye based or pigment based, but that would once again depend on the context. Ssscienccce (talk) 23:17, 17 December 2013 (UTC)[reply]

Yeah I don't know if permanence is that relevant as plenty of inks are fairly permanent. And inks can be dye based or pigment based, in fact some inkjet printers are known for using both with dye based ones often held to give better mixing and so used for CMYK and pigment ones to be more permanent and giving a sharper look so used for a special K intended primarily for text and stuff. I don't think there's generally much dispute that the stuff used in inkjet printers are inks.

As has been said, it's fairly context specific but I think whether something is called an ink or a dye depends at least somewhat on whether it's intended to diffuse or spread as part of the process of printing or application.

If we consider inkjet printers, where the coloured stuff is called ink (although as said it could be a dye or a pigment ink as well) or the many other uses such as pens etc the inks spreading may be a feature but generally not really intended (except that to ensure the ink application stays and is visible).

On the flip side we have Dye-sublimation printers which our article says should probably be called dye diffusion printers but doesn't dispute the dye bit (although does call the dyes, inks). In that case the dye diffusing in to the paper is part of the process of printing. (Although I imagine there be some artists applications where diffusion of inks is an important part of the process.) Noting of course that in a dye diffusion printer, you only want the dye to diffuse from your ribbon in to the paper and the areas where you want it to be applied, you don't want much further diffusion thoroughout the paper (you may want a small amount to give a more natural look, but then again, I wonder if inkjet printers also rely on this to some extent for photos although to a much finer level).

Of course we also can't ignore the history and marketing that like gives arise to such terms, for example Solid ink which uses a solid waxy coloured substances which needs to be melted before application has something that they call ink. Laser printing uses a powder which is baked on and although our article calls it ink a few times, it's generally called toner.

Nil Einne (talk) 06:47, 18 December 2013 (UTC)[reply]

Once again, etymology saves the day. Ink comes from the Greek enkauston,[7]‎ meaning burnt in, and used in relation to signatures. Dye comes from an Old English word, deah, for hue or coloring.[8] Etymology Online is your friend. μηδείς (talk) 23:21, 18 December 2013 (UTC)[reply]

So that answers the question "What is the etymological difference between ink and dye?" But how does that resolve the OP's question about chemical and physical properties of ink and dye. Methinks the day is not yet saved. Richard Avery (talk) 07:46, 19 December 2013 (UTC)[reply]

December 18

I am a FAT rocket man! Rocket man!!!

I asked about an astronaut's contour seat cushion a couple of days ago.

Now, if an astronaut gained or lost several pounds while he/she was in space, how does he/she manage to reuse the seat cushion on the way home? In fact, people may experience minor edema in space. -- Toytoy (talk) 10:15, 18 December 2013 (UTC)[reply]

I'm sure the exact shape is not that critical; they have way more important things to worry about at that stage.--Shantavira|^{feed me} 15:22, 18 December 2013 (UTC)[reply]

Come on! This is NASA! They not only have paperwork for this (Crew Flight Health Stabilization Program); they have an entire ground facility dedicated to monitoring flight crew health: Space and Clinical Medicine facility at Johnson Space Center. I know our OP is fooling around here, but the the take-away message - the thing to know about manned spaceflight - is that every single detail is accounted for. Nimur (talk) 15:58, 18 December 2013 (UTC)[reply]

Usually anyway. Clarityfiend (talk) 18:18, 18 December 2013 (UTC)[reply]

December 19

Equivalents in Chemistry (in the Winkler Determination specifically)

Greetings Wikipedia Science Reference Desk...

I am studying some material about water treatment when I came across a chapter on the concept of equivalency. I have a BS in chemistry, but I am not used to this concept, to be honest...the concept of equivalents/normal concentrations was not a thing I used often, or really at all past general chemistry. In any case, we have the following reaction:

2I₂ + 4Na₂S₂O₃ ---> 4NaI + 2Na₂S₄O₆

the material I'm reading says that "one mole of thiosulfate is equivalent to one mole of elemental iodine." I am unsure how this is true...2 moles of elemental iodine react with 4 moles of sodium thiosulfate, but here we have "is equivalent to," and the nuance is making the difference. I tried writing the reaction as a redox pair (1 mole iodine plus 2 moles "electron" yields 2 moles iodide, and then 2 moles thiosulfate yields one mole tetrathionate and 2 moles "electron") but with the quantities used here, I divide the molar quantities here by 4 (what the book has been calling "the equivalent number," i.e. the number of "electrons transferred") but I still get that one equivalent of sodium thiosulfate equals only one-half equivalent of elemental iodine. What am I missing? Thanks so much for the help.
PS I can't find too much helpful material for studying this concept online past incredibly facile problems involving mono-, di-, and triprotic acids. An good resources out there? Aquaman590 (talk) 06:30, 19 December 2013 (UTC)[reply]

I believe here you need to work from "reaction moles" and not moles of the individual reactants here. The iodine half reaction is:

I₂ + 2 e^- --> 2 I^-

And the thiosulfate half reaction is:

2 S₂O₃^-2 --> S₄O₆^-2 + 2 e^-

Since the two half reactions involve the same number of electrons, they are equivalent to each other. Even in chemistry, language can be imprecise, and from my best guess, that's what they are using the word "equivalent" here to mean. The term Equivalent (chemistry) is really an electrochemical term that refers to how much the charge of a moiety changes in a chemical reaction. Since both half reactions involve the same change of charge (2) then both half reactions are equivalent. --Jayron32 08:23, 19 December 2013 (UTC)[reply]

How much pseudoephedrine is sold every year?

I'm reading a story about how the big drug companies are trying to keep pseudoephedrine an over-the-counter drug and not require a prescription. So I'm wondering how much of the stuff is being used as a cold rememdy, and how much is getting diverted to methamphetamine production. — Preceding unsigned comment added by 50.43.12.61 (talk) 06:38, 19 December 2013 (UTC)[reply]

No space travel conspiracy

I don't know if this is exactly the right place to put this, but a couple of weeks ago I had an argument with someone who was claiming we've never been into space, satellites are fast moving planes, and that all international communication that would require satellite communication actually use over the horizon radio. I've been trying to find what this conspiracy theory would be called, because I want to read some more of their arguments for curisoties sake. I don't believe what they say of course, I just want to know more. Does anyone know what this conspiracy theory is called, and do we have an article on it? 81.138.15.171 (talk) 13:50, 19 December 2013 (UTC)[reply]