Wikipedia:Reference desk/Archives/Science/2013 December 16

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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)

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)

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)

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)

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)

[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)

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)

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)

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)

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)

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)

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.[1] Alansplodge (talk) 14:14, 16 December 2013 (UTC)

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)

You might be interested in this article [2] 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)

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

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)

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)

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)

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)

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)

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)

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)

[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)

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)

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)

Astronauts' seats on their way back home

• http://history.nasa.gov/SP-4225/nasa1/photo/nasa1-photo-37.htm
• List of International Space Station expeditions

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)

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

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)

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)

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)

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)

Deadly overdose of SSRI's

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

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)

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)

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)

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)

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)

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)

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)

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)

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

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

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)

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)

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)

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

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)

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)

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)

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)

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)

Other good rules about diets are:

1. 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.
2. 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.
3. Any diet that talks about 'flushing toxins' or things like that is most likely to be nonsense.
4. 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.
5. 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.
6. 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
7. 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)

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)

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)

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)

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)

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

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