Wikipedia:Reference desk/Archives/Science/2012 November 24

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November 24

Women nagging from a scientific or psychological point of view

I don't want this question to come out as sexist, since all I am asking are findings based on scientific studies, journals, and the like. Basically, from a scientific or psychological point of view, what are the reasons why women seem to nag so much? Is there anything in female psychology, something in their DNA, or other scientific factors that cause them to nag more than men? And is this trait common with other animals? I tried searching for scientific studies about the topic, but I couldn't find any. Narutolovehinata5 ^tccsdnew 00:53, 24 November 2012 (UTC)

It could be that women as a group is more about social interaction rather than about "things" for males. And in particular to change social behaviour by the means of repetition. Electron9 (talk) 03:21, 24 November 2012 (UTC)

Be careful. It is probably because males suck. 00:57, 24 November 2012 (UTC) p.s. On a more serious note: they talk more and some have periods.

Is the basis of your question, the claim that "women nag so much", supported by "scientific studies, journals, and the like"? Otherwise, the question certainly comes out as sexist. HiLo48 (talk) 01:02, 24 November 2012 (UTC)

I meant "seem to nag..." I'll add in those words right now. Narutolovehinata5 ^tccsdnew 01:04, 24 November 2012 (UTC)

I'm really not sure that helps. Presumably it's your opinion that "women seem to nag so much", but how much of the rest of the world feels that way? I don't. So that's 50/50 out of this tiny sample. Maybe the studies, if any, need to be on those that feel the same way as you. HiLo48 (talk) 01:10, 24 November 2012 (UTC)

See You Just Don't Understand: Women and Men in Conversation by Deborah Tannen.

—Wavelength (talk) 01:13, 24 November 2012 (UTC)

Deborah doesn't seem to be the brainy type:

“ I recall one discussion period following a lecture I gave to a group assembled in a bookstore. The group was composed mostly of women, but most of the discussion was being conducted by men in the audience. At one point, a man sitting in the middle was talking at such great length that several women in the front rows began shifting in their seats and rolling their eyes at me. Ironically, what he was going on about was how frustrated he feels when he has to listen to women going on and on about topics he finds boring and unimportant. ” — Deborah Tannen

The article about Deborah contains the phrase "however, feminist linguists argue against Tannen's claims."...

Trio The Punch (talk) 01:30, 24 November 2012 (UTC)

The article about Dr. Tannen mentions two book awards that she has won.

—Wavelength (talk) 02:48, 24 November 2012 (UTC)

This page about one of Dr. Tannen's books has the following statement.

• Women in managerial positions have embraced this book as an account and an explanation of their own experiences and a guide to making changes.

—Wavelength (talk) 02:54, 24 November 2012 (UTC)

I am not saying she is not successful, she is probably richer than I am, I said she doesn't seem to be the brainy type, a polite way of saying she is not very smart. I suspect feminists think her ideas are outdated and sexist. You forgot to mention the author of that quote... Is it Deborah herself? I googled "Women in managerial positions have embraced this book": 1 result, her own website. She either wrote it herself or the person who made her website did. Trio The Punch (talk) 03:00, 24 November 2012 (UTC)

This may or may not be helpful in answering the original questions. Dr. Tannen has videos on YouTube.

—Wavelength (talk) 04:12, 24 November 2012 (UTC)

Newton's Second Law

Ever since I have learned that Newton's second law is actually "force equals the change in momentum in time" instead of "F=ma" I have been curious about this but can't really find a good answer. I understand that in the second form, we assume that the mass is constant in time. The first form is more general because it allows mass to change in time such as a rocket being launched and its mass decreasing in time as fuel is being spent. My question is, is there any hint anywhere that Newton might have suspected relativistic changes in mass? Because the first form is general enough to allow increase in mass too as velocity increases. I realize that back in those days relativistic velocities were difficult to achieve and the relativistic effects were hard to measure with those instruments so no one had probably seen these effects in an experiment but you never know. Thanks! 184.96.226.214 (talk) 02:04, 24 November 2012 (UTC)

That's a later modification to Newton's second law. Newton's original text stated: "The alteration of motion is ever proportional to the motive force impressed; and is made in the direction of the straight line in which that force is impressed." 1729 English translation, for comparison here is Newton's latin original. It is quite clear he is talking about acceleration, "alteration of motion", as Newton's own explanatory notes after the statement of the law refer to acceleration rather unambiguously. Newton's original law makes no mention of mass at all; it is implied from context that he's refering to forces applied to the same object. --Jayron32 03:27, 24 November 2012 (UTC)

Mayans

Is it true the Mayans successfully predicted every solar and lunar eclipse up until current time and even when their own civilization would be overtaken by invading foreigners. This said they did http://voices.yahoo.com/will-world-really-end-2012-11075310.html --Wrk678 (talk) 08:04, 24 November 2012 (UTC)

Most of their writings were burned by the Spanish, as explained in Maya codices. Of the three surviving codices known to be authentic, the Dresden Codex has a table of times when eclipses could (but did not necessarily) occur.[1] It spans 11,959 days (405 lunar months or 32+ years), hardly "until current time". Plus, they weren't totally accurate ("The astronomers periodically corrected the eclipse tables, learning from their small mistakes and adjusting the calendars ..."[2]). As for the writer you cited, she also believes in "holistic healing" and makes an unexplained (and really hard to believe) claim that the Mayans knew "when their own civilization would be overtaken by invading foreigners". If they did, why didn't they prepare better? All in all, not exactly what we'd call a WP:reliable source, not by a long shot. Clarityfiend (talk) 11:13, 24 November 2012 (UTC)

We know very little about the Mayans. That hasn't stopped certain people from making a lot of money by exaggerating what we do know and adding some fiction. Extra-ordinary claims require extra-ordinary evidence. That Yahoo link was not written by an expert. The "voices" subdomain is the location of the Yahoo! Contributor Network, anyone can join by signing up here. If you want me to I can write a page about the fact that Justin Bieber is a shapeshifter and publish it on voices.yahoo.com. Would you believe me if I did? Trio The Punch (talk) 16:33, 24 November 2012 (UTC)

When there's little known, there's a tendency to want to fill in gaps, especially if one can make money from it. As the author of the book that debunked the Bermuda Triangle said, "Everybody loves a mystery." By contrast, there's not a lot written about how wonderful the Vikings were, because they were known all too well. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:24, 24 November 2012 (UTC)

Over time all historical people and groups of people turn into stereotypes. Many people use the same kind of stereotypes to describe modern people and groups of people, we use words like racism to describe that. People love these noble savages. BTW I hate Vikings and their repetitive singing. Trio The Punch (talk) 17:43, 24 November 2012 (UTC)

I think all intolerant people should be shot. -- Jack of Oz ^[Talk] 20:28, 24 November 2012 (UTC)

By shapeshifting Viking singers at long range with spam, spam, spam, spam, spam, spam, baked bean, spam, spam, spam and spam bullets. Clarityfiend (talk) 23:14, 24 November 2012 (UTC)

What is this formula depicting?

This tattoo on a person's foot looks like a really fancy chemistry thing. Could anyone enlighten me please? http://shechive.files.wordpress.com/2011/01/dork-nerd-10.jpg — Preceding unsigned comment added by 24.72.13.24 (talk) 08:11, 24 November 2012 (UTC)

Polypeptide 2HN-CO-Glycine-Leucine-Proline-Cystine-Asparagine-Glutamine-Isoleucine-Tyrosine-Cystine-NH2 with sulfur bridge between cystein and Cystine.--Stone (talk) 08:50, 24 November 2012 (UTC)

G-L-P-C-N-I-Y-C in short --Stone (talk) 08:53, 24 November 2012 (UTC)

Gly-Val-Pro-Cys-Asn-Gln-Ile-Tyr-Cys --Stone (talk)

It is Oxytocin, I think it is biochemists expression for love.

According to the article "it is sometimes referred to as the "love hormone"" (citation needed). Do biochemists give each other oxytocin chocolates?--Shantavira|^{feed me} 11:41, 24 November 2012 (UTC)

Such a tattoo could alternatively indicate a union booster, since oxytocin induces labor. Using such formulas as tattoos is about as sensible other things that one does not fully understand. -- Scray (talk) 16:45, 24 November 2012 (UTC)

"chocolate is packed full of glucose"

My textbook compares a chocolate bar to a baked potato; the baked potato releases energy slowly, the chocolate quickly, because one is starch and has to be broken down into glucose, and then quote: "whereas chocolate is packed full of glucose which is more readily absorbed..." My question is: have they taken a liberty here, by not clarifying that this is true of cheap milk chocolate bars? Or does this also extend to, say, an 85% Lindt chocolate bar? By saying just chocolate they are implying that cocoa itself is packed full of glucose. Would this be true? Howie.W.30 (talk) 09:22, 24 November 2012 (UTC)

All you need to do to answer this is look at the dietry information printed on the packet. It happens that I have a Cadbury "Old Gold" dark chocolate bar waiting for me to eat. This is not a cheap milk type. It says on the packet that the sugar content is 57.3 grammes per 100 g of chocolate. Delicous but perhaps not very good for you if not eaten in moderation. In World War 2 cholocate bars were issued to Australian soldiers to eat before battles, because it kept well in a convenient sealed packet, and when eaten would give you a fast energy boost - that's what sugars/glucose does. All that sugar won't come from the cocoa. Note that chocolate is made from milk without the water, and milk with its water is up to 8% glucose. I don't know if chocolate manufacturers add glucose/sugar but it seems likely. Googling glucose chocolate reveals that researchers have been trying to prove that cocoa reduces blood sugar level. Floda 124.178.154.224 (talk) 11:28, 24 November 2012 (UTC)

My bar of 70% Old Gold has 27.7g of sugars (which I take it to include lactose etc). I'm not saying this is low, simply that we have to be realistic, if a bar is 85% cocoa solids, it's not going to have 57.3 g of sugar. Nil Einne (talk) 11:55, 24 November 2012 (UTC)

I looked again. Yep, my (Australian made) bar of Old Gold says it has 57.3 g sugar per 100 g chocolate. The cocoa solids are listed as only 45%. I've tried other types with 85% cocoa solids - they are not to my taste. When I made my first post, I only thought to look at the detailed dietry info. If I had looked above that to the summary of ingredients, I would have seen that it says that sugar is added. Floda 124.178.154.224 (talk) 13:16, 24 November 2012 (UTC)

(EC) Well I question whether that's correct in general. Outside of countries where high fructose corn syrup is common, like the US, most chocolate bars even cheap ones will have sugar i.e. sucrose not glucose. (To be clear, I'm not saying that HFCS will have a worse effect on GI then sucrose, simply that something using HFCS will have a far amount of glucose as well of course as a lot of fructose.) E.g. I just confirmed this from a bar of Cadbury milk chocolate here in NZ. And the glycemic index of potatoes even baked ones is actually quite high whereas the glycemic index of even cheap milk chocolate AFAIK often isn't that high. E.g. [3] gives 49 for milk chocolate. It doesn't have baked potatoes but the lowest for potatoes is boiled at 56. Jacket potatoes which I presume were baked is given as 85. This source specifically mentions chocolate generally has a lower GI then potatoes [4]. This source [www.amsa.org/healingthehealer/GlycemicIndex.pdf] gives 85 for baked potatoes and 68 for chocolate bars (type not specified but I think it's resonable to assume we're talking about fairly normal cheap chocolate bars). This [5] gives 49 for chocolate bar, 68 for Mars Bar, no specific value for potatoes but it mentions it's normally fairly high. To perhaps further emphasise [6] gives 111 for a baked russet potato (82 for a boiled white potato), which may seem a little extreme but I'm sure this isn't the first time I've heard of a potato having a higher glycemic index (then glucose). Nil Einne (talk) 11:47, 24 November 2012 (UTC)

Besides the added sugar, chocolate contains both cocoa powder, which has some fat and a tiny bit of sugar (maybe 2-3%) [7] and cocoa butter, with all fat and no sugar [8]. My 85% cocoa Möser Roth bar has 8 grams of sugar per 50 gram serving, which would make it 16% sugar. Most chocolate bars add far more sugar. Why ? Because cocoa is quite bitter by itself.

You can buy baker's chocolate, without added sugar. You find it in the baking aisle, not with sweets, since the assumption is that it will be used in baking, along with added sugar, not consumed directly. Take a bite, if you dare, but be close to a place where you can spit it back out. StuRat (talk) 20:56, 24 November 2012 (UTC)

• Dark chocolate has a rather low glycemic load, and diabetics who may need emergency sugar are aadvised to carry candy but not chocolate for that purpose. This website is quite incredible a resource for all your nutrition information needs: http://nutritiondata.self.com/facts/sweets/10638/2. μηδείς (talk) 21:27, 24 November 2012 (UTC)

Just a few comments on the above... sucrose is half glucose, half fructose. And while there's some small debate over the point, high fructose corn syrup is usually about the same nutritionally as sucrose (depending on concentration, but most are around 50%). There's very little difference in structure, or effect, between just sugar and HFCS. I'm baffled that your textbook would use a baked potato as an example of a low glycemic index food. Fiber tends to level out blood glucose levels more than anything else. Shadowjams (talk) 03:40, 25 November 2012 (UTC)

Drive shaft feature identification

What is that square cut out at the end of the drive shaft called [9]? What is its purpose?Dncsky (talk) 13:45, 24 November 2012 (UTC)

It is intended to allow the user to couple a generic part to the drive shaft. I'm not aware of a more technical term than "couple" or "socket" that's used in this sort of scenario: but I would label it a mortise socket if I were drafting a sketch for manufacturing a part to fit it. Nimur (talk) 14:13, 24 November 2012 (UTC)

But isn't there already a rotor attached? I can't see what else could be fitted on there.Dncsky (talk) 14:21, 24 November 2012 (UTC)

You linked to a photo of a very small engine, correct? It's plausible that one manufacturer can use this engine to drive a model or toy aircraft propeller; another manufacturer can use the same engine, unmodified, to power a small model car, and so on. Do you know the engine make and model? The image is somewhat small and blurry. Nimur (talk) 18:04, 24 November 2012 (UTC)

You must be joking, Nimur. Looking at the fittings on it, and the complexity, it is not likely to be a toy or small model engine. And it is quite unlike the small engines used for gneral purposes. It's far more likely to be an engine for an ultralight aircraft. Keit 121.221.229.69 (talk) 00:04, 27 November 2012 (UTC)

Isn't an ultralight aircraft, for all regulatory purposes, a "toy"? (At least, that's how I interpret 14 CFR Part 103 after translation from government-ese to English). Even the 7ECA Citabria that I fly - which is about the smallest, scrawniest, slowest aircraft on our airfield, has a 120 horsepower Lycoming O-320, which as you can see looks a might more powerful, small though it may be, still quite a bit larger than the engine in the original question above... Now, I know there are some light sport aircraft on the market that fly with a smaller engine, and the infamous J-3 Cub originally took loft with less than forty horsepower ... but even those engines didn't look so small. I believe what we are observing, above, is a lawn-mower with a propeller bolted to the front. Nimur (talk) 00:55, 27 November 2012 (UTC)

A reverse image-search, provided by Google, indicates that this engine is actually a AR801 Wankel engine, distributed by UAV Engines Limited, intended for use on model aircraft. I stand by my earlier statements about the probable purpose of the shaft coupling socket. Because Wankel engines operate at peak efficiencies at very high-RPM (say, 6000 to 8000 RPM), it is common to attach the drive-shaft to a reduction gearbox. And, preemptively, the enthusiastic reader might want to reference our article before comparing the nominal bhp to hp). Nimur (talk) 01:43, 27 November 2012 (UTC)

And if Nimur had actually read the data on the AR801, he would have found it is NOT intended for model aircraft. It is a 40/60 BHP engine, quite within the range of ultralight applications, and way way too big for models, although it was developed for professional drone aircraft (ie remote controlled aircraft for police and military use). So I was not far wrong. There's no way it could have been a lawnmover engine - it does not comply with common mounting and shaft standards for such engines, and it looks far too compex/sophisticated. Keit 121.221.229.69 (talk) 02:13, 27 November 2012 (UTC)

The lawn-mower bit was of course intended for some light humor, Keit. Anyway, it is a fairly sophisticated engine; and a UAV may be a little bit more expensive or "professional" than the term "model airplane" usually connotes; but I still wouldn't trust a human's life to it. And neither would the FAA. So, from my point of view, it's a toy, even if it's an expensive toy bought by police or military clients. Nimur (talk) 02:29, 27 November 2012 (UTC)

Just curious, why do you think the Authorities would not approve it? It has two complete independent ignition systems, is available with a compliant fuel system, and meets vibration requirements. If the documentation requirements are met, it's fine. Keit 121.221.229.69 (talk)

As far as why I believe the FAA would not certificate this model: I don't speak for them, but above, I've linked the FARs and the advisory circulars on engine airworthiness. I suspect the engine is "unreliable," a claim which I can only support by citing its manufacturer's recommended ten-hour TBO and my own personal "gut instinct." In actual fact, I'm neither expert nor authority enough to really comment on whether this engine model is safe or legal for any particular purpose. I have included a variety of links, along with my opinions in some of my postings; and while I'm entitled to my opinion, I have probably already strayed too far from factual, referenced statements; so let me stop now before I get too carried away. Nimur (talk) 04:58, 27 November 2012 (UTC)

Assuming it is in fact machined into the crankshaft and not part of the propellor (I am very familiar with engines, but not engines of this type), its purpose may be for barring, and thus it could reasonably be called the barring socket or barring nut. Barring is the process of turning a piston engine over slowly and often to precise points such as top dead centre - something that mechanics must often do in the aseembly/maintenance/overhaul of engines. With the propellor fitted you would not need it - just grab the prop and turn. But the crankshaft may have a barring socket or nut anyway so you can work on the engine without the prop. The term comes from the history of engines - early piston engines were large and heavy, with big heavy cast iron flywheels. Holes were made around the periphery of the flywheel, into which you inserted a crowbar or just an iron bar of convenient length, to turn the engine over to check timing, adjust valve gear clearances etc. Modern large diesel engines such as types of 400 to 5000 horsepower have a geared mechanism that engages with the starting ring gear for this same purpose - to use it you attach a large wrench and push it in to engage with the flywheel and for every 100 turns or so of the nut you turn the crankshaft one turn. It is called the barring gear for the same historical reason. In very large engines of power staion and ship main propulsion size, an actual engine (non-mechanics and non-engineers sometimes incorrectly call it a donkey engine) is provided to turn the main engine over for maintenance/assembly/overhaul purposes - this is called a barring engine. (Not to be confused with a starter motor/starting engine, which is designed to turn the main engine over as fast as possible without any positional precision.) Keit 121.215.135.17 (talk) 15:40, 24 November 2012 (UTC)

It also could quite likely be just a retaining nut to affix the propellor, and not part of the shaft at all. Keit 121.215.135.17 (talk) 15:43, 24 November 2012 (UTC)

Why is the equator not a large desert?

Global Desertification Vulnerability Map

Hi, I thought about the main theory of climate, and I haven't understood why is the equator not a large desert, and why the Sahara is. Exx8 (talk) 17:05, 24 November 2012 (UTC)

Most of the equatorial regions get rain. ←Baseball Bugs ^{What's up, Doc?} carrots→ 17:21, 24 November 2012 (UTC)

Desertification is caused by a variety of factors such as climate change and human activities but being close to the equator is not one of them. Trio The Punch (talk) 17:25, 24 November 2012 (UTC)

I'm curious what the "main theory" of climate is. Some topics, like algebra or calculus, have a central theorem that embodies the critical idea of study. Climate, however, is a very complex scientific topic. We understand climate through the methods of physics, chemistry, biology, ecology, meteorology,... but none of these profer a "main theory of climate." Nimur (talk) 18:13, 24 November 2012 (UTC)

Am I reading it wrongly, or does that map show East Anglia as being at a high risk of desertification? A visit to that part of the world at this time of year might be instructive to whoever drew it. Tevildo (talk) 18:21, 24 November 2012 (UTC)

According to the main theory, the most major factor to climate is the longitude .

Another oddity is that there seems to be a magical climate change right on the US-Canada border, in the Western plains. StuRat (talk) 22:10, 24 November 2012 (UTC)

The 50 degrees temperature differential across the border probably has something to do with it.Dncsky (talk) 23:30, 24 November 2012 (UTC)

East Anglia contains the areas of the UK with the lowest annual rainfall, so I guess it's nearer to being at risk of becoming a desert than, say, Manchester or South Wales or Cornwall. --Demiurge1000 (talk) 01:11, 25 November 2012 (UTC)

As you can see on the picture, the angle of which the sunlight hits the ground changes the amount of energy that cm^2 gets. By doing so the amout of thermal energy changes in the place. That why the poles are cold, and the equator is hot and Arabia and 20 to 30 longitudes are usually deserts.. But I don't got why the equator is not a desert!!! Exx8 (talk) 18:41, 24 November 2012 (UTC)

Heat is not the definition of a desert. Precipitation is. Precipitation is more complicated than longitude alone, because it is more complicated than temperature alone. --Mr.98 (talk) 19:07, 24 November 2012 (UTC)

Arabia,North Africa, Australia, Namibia all are near or between 20 to 30 longitude (south or north) and have vast areas of desert.

Exx8 (talk) 20:09, 24 November 2012 (UTC)

Substitute "latitude" for "longitude" and this discussion will make a lot more sense. Edison (talk) 20:18, 25 November 2012 (UTC)

Lack of rainful defines a desert, hence the largest desert is Antarctica. The reason certain latitudes are deserts is because of atmopheric cells. At the Equator heat evaporates and as it rises it cools and falls as rain. At 30 degrees the air cool and cirulates round by this time there is no water left in the air so it is dry and hence a desert. Also mountains and being landlocked causes desertifcation.Dja1979 (talk) 20:52, 24 November 2012 (UTC)

Rainfall patterns are strongly tied to prevailing winds. Places which lie on the windward side of mountain ranges tend to get more rain than those on the leeward side. This is called the rain shadow effect, and many deserts can be explained because the desert lies in the rain shadow of a mountain range. Also, wind that blows over the land for long distances doesn't gather any moisture, while wind that blows over ocean water (especially warm ocean water) does. Additionally, there are bands of the earth's atmosphere where there is a permanent state of high pressure that leads to very little rainfall, these are called the horse latitudes and you'll find much of the world's desert lying underneath these. When you combine many of these factors (rain shadow, land upwind, horse latitudes) you get the world's driest deserts (Sahara, Arabian, Atacama, Kalahari, etc.) --Jayron32 01:13, 25 November 2012 (UTC)

(oop, wrote this before seeing Jayron's response, pardon the duplicate links) Dja1979 has it right. Atmospheric cells are the big picture reason. Some additional links: The large cells create prevailing winds. The northern and southern trade winds meet in the Intertropical Convergence Zone, near the equator, which tends to be rainy and wet. In contrast around the Tropic of Cancer and Tropic of Capricorn the large-scale atmospheric circulation creates dry zones of high pressure called the horse latitudes, which is where the temperate deserts are located, more or less. It is also why very dry deserts can exist right next to oceans, like the Atacama Desert. Mountains and rain shadow effects can intensify the aridity, or cause aridity beyond the horse latitudes. The High Desert of Oregon, for example, is far north of the horse latitudes, well into the zone of the Westerlies, which, blowing off the Pacific Ocean create temperate rain forest along the coast and on the west side of the Cascade Range. But by the time the westerlies get over the Cascades they have lost most of their moisture due to orographic lift. Thus the east side of the mountains are very dry. Pfly (talk) 02:31, 25 November 2012 (UTC)

why is the desert strips are created around 30 degrees and not around 50 degrees for example?Exx8 (talk) —Preceding undated comment added 18:07, 25 November 2012 (UTC)

Based on this explanation, why don't the Rocky Mountains turn the northern Great Plains into an enormous rain-shadow desert?

Also, why does the map show much of the Canadian prairie as desert? Whoop whoop pull up ^{Bitching Betty | Averted crashes} 18:35, 25 November 2012 (UTC)

the weather of the Great Plains is complex and diverse

Much of the Great Plains/Canadian Prairie is steppe, which can be "semi-arid" or pretty close to desert. True desert gets 250 ml or less of rain per year, a "semi-arid" or "semi-desert" climate gets between 250-500 ml of rain per year, and much of the Great Plains falls into this climate. The southeastern Great Plains gets considerable rainfall from warm, moist air flowing northward from the Gulf of Mexico; there's a feature called the "dry line" that roughly separates the drier great plains from the wetter great plains. The dry line defines tornado alley. Much of the Great Plains is at risk constantly from desertification; there are periods of extreme drought, whereby the plains are converted to desert land, see Dust Bowl for a time period when this happened in recent memory. Regarding the Rocky Mountains: there are lots of deserts in the rain shadow of the Rocky Mountains: Much of New Mexico, Colorado and West Texas lies within the High Plains, an area of desert or semi-desert conditions. Much of that area meets the literal definition of desert, or close to it. The really severe deserts in the U.S., however, lie between mountain ranges, where there is no inflow of moisture available from any direction. For example, the Mojave Desert lies between the Sierra Nevada and Rocky Mountains; it is part of the wider Basin and Range Province which is essentially all desert. --Jayron32 03:04, 26 November 2012 (UTC)

why is the desert strips are created around 30 degrees and not around 50 degrees for example? That's a good question I don't know the answer to. Our Hadley cell page simply says "Why it extends only to 30 degrees latitude and what determines its strength are questions addressed by modern dynamical meteorology." Not exactly an answer! The page Subtropical ridge hints at a bit more: "The divergence over the near-equatorial trough leads to air rising and moving away from the equator aloft. As it moves towards the Mid-Latitudes, the air cools and sinks, which leads to subsidence near the 30th parallel of both hemispheres." The impression I get from reading these, and other pages, is that the Hadley cells and the polar cells are the driving forces, while the in-between mid-latitude Ferrel cell exists mainly because the polar and Hadley cells have a gap between them. Why though, I don't know. Perhaps about 30-35 degrees is about as far from the equator that warmed air aloft can get before it cools too much and sinks? Pfly (talk) 05:58, 26 November 2012 (UTC)

From all the above discussion, I wonder how much the phenomenon of deserts tending to be around 30 degrees latitude is due to effects common to all spinning spheres with atmospheres, and how much of it is attributable to local topographic idiosyncracies. In this regard, do we know anything about the latitudinal patterns of rainfall or the equivalent on Venus, Jupiter, Saturn, or Titan? Duoduoduo (talk) 15:16, 26 November 2012 (UTC)

Good question. I am too lazy to google info about Venus, Jupiter and Titan, but the rainfall on Saturn is pretty interesting. Could you imagine if Earth's moon was the source of rainfall? Enceladus is the sixth-largest of the moons of Saturn. It has geysers at its south pole, actively spewing out quite a bit of water into space. About 3-5% of the water from Enceladus’s geysers falls on Saturn. Yes, I am crazy, but no, I am not lying. Here is the research (PDF). I think comparing rainfall patterns on Saturn to rainfall patterns on Earth won't help us understand desertification, but it is certainly interesting stuff. Trio The Punch (talk) 20:38, 26 November 2012 (UTC)

if you go deep enough from Sahara or Arab flat and Iran Kavir about 35 meter you will find a layer of soil shows growing of plant some millions of years ago there ,the fact that this zones became desert and burning of them is effect of equator ,same as reflection .the heat circulation from equator correctly lands on zones between 35-60 degrees band.--Akbarmohammadzade (talk) 16:22, 27 November 2012 (UTC)

Human humerus

what does a broken human humerus at the head look like.18:14, 24 November 2012 (UTC) — Preceding unsigned comment added by 50.142.225.56 (talk)

This. Many similar images are available with a Google search on "Proximal humerus fracture". Tevildo (talk) 18:19, 24 November 2012 (UTC)

Sensor Array http://en.wikipedia.org/wiki/Sensor_array

In the Section on "Spectral Based Beamforming", there is a math equation for the "spacial covariance matrix" in which the "array manifold vector" V and it has a raised index or exponent "H" , but there is no explanation for what "H" stands for - that is my question? SnakeCasey (talk) 21:52, 24 November 2012 (UTC)

This is the Hermitian transpose, rows are turned into columns and complex conjugate is taken. Graeme Bartlett (talk) 22:04, 24 November 2012 (UTC)

That's what I guessed as well, but to be honest I was a bit stumped at first. Should it be changed? I don't think I've seen it elsewhere on Wikipedia. -Anagogist (talk) 22:06, 24 November 2012 (UTC) Never mind, I'm an idiot. -Anagogist (talk) 22:08, 24 November 2012 (UTC)

micro wave shielding methods and materials

What particular materials are used to shield enclosed areas, like a small room? and where I might 0find them. — Preceding unsigned comment added by 75.6.143.24 (talk) 22:16, 24 November 2012 (UTC)

A metallic screen (much like a window screen). The actual spacing is critical, however, and depends on the frequencies you need to block. StuRat (talk) 22:21, 24 November 2012 (UTC)

See Faraday cage and Electromagnetic shielding for our articles on the subject. Tevildo (talk) 22:38, 24 November 2012 (UTC)

What is the current energy usage of the Internet

http://www.theregister.co.uk/2012/11/24/cudos_photonics_australian_institute_physics/ If we want to keep expanding the performance and the reach of the Internet, we need an inflection point: otherwise, its electricity consumption will become catastrophic.

Is it really that big a deal? Could we save a great deal of energy by turning the Internet off at night? Hcobb (talk) 23:23, 24 November 2012 (UTC)

Umm... what? It's not as easy as flipping a switch to "turn the Internet off," and even if it were I daresay people in other parts of the world will be rather cross with you for turning off their Internet at 9 in the morning. 24.92.74.238 (talk) 00:52, 25 November 2012 (UTC)

The Register is an amusing read, but it's important not to take anything it says too seriously. The word "catastrophic" is clearly an exaggeration here. The internet and internet industry and such, according to the article takes a few per cent of world energy demand; and as it continues to grow it will need more; so researchers are looking at ways to operate it more efficiently. That's about it. --Demiurge1000 (talk) 01:08, 25 November 2012 (UTC)

I've got a better idea. Just download the internet and print it off, then go through it one weekend, decide what to keep, and ditch the rest. I'm sure you'd save a massive amount of space. You can then use the scrap paper to mop up all that excess water in the Pacific Ocean.  :) -- Jack of Oz ^[Talk] 07:55, 25 November 2012 (UTC)

Internet service is mostly carried by phone or cable lines so is not a huge added cost over the baseline signal. Servers are a new draw on electricity, and I understand it costs a lot to keep them from overheating. Computers cost money to run, but not so much more than running an old TV would have, one presumes. I'd look into the cost of running the servers. Imagine how big google's footprint must be. Probably not as bad as the machines in Terminator, yet. Once we get to Matrix stage they'll be feeding off us. μηδείς (talk) 02:53, 25 November 2012 (UTC)

Servers are computers, and the consistent trend has been that each new generation of servers can do more work while consuming less power. Also, servers are not "a new draw"... internet servers (in the modern sense) have been around for well over thirty years, web servers for well over twenty years.

Google and Amazon and similar hosting companies do indeed draw lots of power, but they do it by providing hosting facilities that mean power does not need to be used by smaller companies elsewhere. Such centralisation provides considerable efficiency (i.e. saves power) by allowing them to design their very large datacentres for best performance (solar panels on the roof, clever ways of using airflow and ambient temp cooling and so on.) --Demiurge1000 (talk) 03:13, 25 November 2012 (UTC)

Using power that wasn't used before efficiently is still using power. But I think Demiurge's overall point is obviously true, the internet saves an effload of power given all the efficiencies it introduces economywide. μηδείς (talk) 04:03, 25 November 2012 (UTC)

I wasn't discussing whether using the internet consumes more power than not using the internet (or not having an internet). I was discussing whether the ideas mentioned by the OP, and amplified by yourself, namely that the internet will progressively use more and more power to a "catastrophic" degree, are realisic. Current technology trends are to use less power to do more things. --Demiurge1000 (talk) 05:47, 25 November 2012 (UTC)

But, of course, increasing energy efficiency doesn't automatically mean reduced energy consumption. In many cases, increased efficiency may permit us to do more things economically, thus increasing the total workload. Consider that during WW2, code-breaking machines used a huge amount of power to do simple things, yet our total computer electricity consumption now is far more than then, despite massive increases in efficiency. StuRat (talk) 06:19, 25 November 2012 (UTC)

Same tasks, less power. Computers are not now used mainly for code-breaking. --Demiurge1000 (talk) 06:25, 25 November 2012 (UTC)

Which is my point, precisely. The more efficient they become, the wider their usage. StuRat (talk) 06:30, 25 November 2012 (UTC)

I see nothing that suggests a direct correlation between increased power efficiency of computers and more widespread use of them. --Demiurge1000 (talk) 17:07, 25 November 2012 (UTC)

They have both consistently increased over time, so the correlation is obvious. Whether there is a causal link or not is not as easy to tell, but I would be very surprised if there weren't. It's simple supply and demand - when something can be supplied cheaper, the price comes down, demand for it will increase and total consumption will increase. --Tango (talk) 17:38, 25 November 2012 (UTC)

The purchase price of computer hardware, and the cost of electricity required to run it, are two completely different things. Very few people decide whether to buy a computer based on the exact amount of electricity required to use it. (An exception, to some extent, is computers that are used as servers - the increased interest in their power efficiency being my point here.) --Demiurge1000 (talk) 10:47, 26 November 2012 (UTC)

The reason people don't worry about the price of the electricity to run a computer is because it's so low. If they used kilowatts per hour, then it would be a concern, and fewer people would buy them, with many of those who did just getting on, checking their e-mail, and getting back off again. StuRat (talk) 06:47, 28 November 2012 (UTC)

If more of the economy is handled via the Internet, using more energy, then less of the economy is handled in old-fashioned ways, so that energy is conserved. For example, more teleconferencing means less driving and flying to meetings. More emails means fewer snail mails. More pics texted back and forth means less film needs to be developed and mailed. More movies viewed online means less driving to the video store to pick up movies or watching movies in theaters. It might all balance out, or even save energy overall. StuRat (talk) 05:25, 25 November 2012 (UTC)

Darn right. As a professional engineer with a career involving research and development, I used to spend a lot of time driving to university and national libraries and having them post photocopies to me. I still do that, but I get most of what I need these days sitting at my computer. Yep, my computer and the servers I'm accessing consume energy but not anywhere near what I used to use in the car. I largely work from home now, as I can access email, the web, and client systems just as well at home. Saves a fortune of time, money, and energy I used to comsume in commuting to work each day. On the other hand, my house aircon is nowhere as energy efficient as aircon in commercial premisses, but I'm working on that. Keit 120.145.149.167 (talk) 04:00, 26 November 2012 (UTC)

More teleconferencing usually means more teleconferencing that generate more travelling for physical meetings ;) Electron9 (talk) 11:44, 25 November 2012 (UTC)