Science desk
< August 11	<< Jul \| August \| Sep >>	August 13 >

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

August 12

Column vs flash chromatography

What exactly is the difference between column chromatography and flash chromatography?

What is the purpose of sodium sulfate, silicagel, dichloromethane, and cyclohexane in flash chromatography?

Thanks. --Activism1234 02:19, 12 August 2012 (UTC)[reply]

Flash chromatography is a kind of column chromatography which uses fluid (usually gas) pressure instead of gravity. See Column chromatography#Mobile phase (eluent) and this external link from that article. They explain the use of silica gel but I have no idea what sodium sulfate is for. Huh. The other two chemicals are common chromatography solvents. 75.166.207.214 (talk) 02:47, 12 August 2012 (UTC)[reply]

Oh, sodium sulfate causes proteins to crystallize and has apparently been used in chromatography for that purpose since around 2000. I guess the point of crystallizing them is to produce different size protein crystal particles which will differentiate in column positions? No idea, really, but you should be able to google around on these keywords to find out. 75.166.207.214 (talk) 02:59, 12 August 2012 (UTC)[reply]

If it helps, here's a procedure I've seen in research:

Add glass wool, sand, silicagel, sodium sulfate, to column. Add cyclohexane and dichloromethane as well (numbers were specified). Blow pressurized air in until level of sodium sulfate. Insert extract (from a previous step) into column, blow prezzured air in. Insert cyclohexane, blow pressurized air in. Add dichloromethane, blow pressurized air in. Let the liqiud that was collected in a beaker beneath the column evaporate overnight. --Activism1234 03:22, 12 August 2012 (UTC)[reply]

Let the liqiud that was collected in a beaker beneath the column evaporate overnight. NO! Don't do that. Dispose of it properly, please. — Preceding unsigned comment added by 148.177.1.210 (talk) 20:37, 13 August 2012 (UTC)[reply]

Allow it to evaporate in a fumehood fitted with an appropriate scrubber system for organics. Generally, you can assume that people engaging in a little bit of biochemistry know about the correct safety protocols. 203.27.72.5 (talk) 21:45, 13 August 2012 (UTC)[reply]

Apollo 11 or Apollo XI?

What is the correct way of writing it, Apollo 11 or Apollo XI? What was the official way of writing it used by NASA? This is discussed at Talk:Hollywood_Walk_of_Fame#Apollo_XI_.28plaque.29_vs_Apollo_11 right now. Could anyone help sort this out? Taylor Strand (talk) 08:20, 12 August 2012 (UTC)[reply]

If you search at NASA's official site for Apollo XI, you come up completely empty, whereas Apollo 11 returns many, many hits. I've never, in all the years I've walked the Earth, heard or read it called XI (until now). Of course, what the Hollywood Walk of Fame does is its own business. Clarityfiend (talk) 10:32, 12 August 2012 (UTC)[reply]

As you can see at commons:Category:Logos_of_Apollo_missions, some Apollo missions did use Roman Numerals on their insignia but Apollo 11 didn't. I think the insignia is the most likely place you'll see Roman Numerals - if they aren't used there, they won't be used anywhere else. According to Apollo 11#Insignia, the crew felt "11" would be understandable by more of the world's people than "XI" and they wanted to represent the world. --Tango (talk) 10:52, 12 August 2012 (UTC)[reply]

Clarityfiend, please read extant discussion before leaping. There's no single "official" NASA archive. Further, as I already wrote, here's a Kennedy Space Center NASA archives page about the so-emblazoned Apollo XI mission, and here's a NASA page which does use "11", while declaring the mission as "Apollo XI" - it's over on the left side, there - see it? --Lexein (talk) 17:08, 12 August 2012 (UTC)[reply]

I did read it. XIs are few and far between, overwhelmed by the teeming hordes of 11s. Clarityfiend (talk) 22:27, 12 August 2012 (UTC)[reply]

It's WP:COMMONNAME for "Apollo 11". - The Bushranger _{One ping only} 22:47, 12 August 2012 (UTC)[reply]
Not when the object carries the formal name, the mission name. A very few Wikipedia editors insist that they know how to name things better than the original author, publisher, designer, artist, ... - silly on the face of it. There is no purpose except denigration in quoting and parenthesizing the actual text used, when it is not misused or in error, and is therefore WP:UNDUE. --Lexein (talk) 04:37, 13 August 2012 (UTC)[reply]

Vibro Compaction

What is vibro compaction? What are the different types of vibro compaction? Is it only sand that can be used in vibro compaction? — Preceding unsigned comment added by 115.188.219.192 (talk) 08:35, 12 August 2012 (UTC)[reply]

Vibration at the proper frequency causes the sand to "dance". When it does so, it tends to eventually find more efficient ways to pack together, say by having smaller grains fill in the gaps between larger grains. The same can happen with other objects, although the frequency and amplitude of the sound required will differ. As for different types, the only thing that comes to mind is that the sand could either be unconstrained or have pressure applied to it as well. I'm not actually sure which method would result in more compaction, however (the freedom to move more might allow for more optimal packing). StuRat (talk)

To add a bit of context to StuRat's accurate answer, see Soil_liquefaction#Liquefaction_mitigation_methods for the usefulness of vibro compaction and the other techniques. 112.215.36.181 (talk) 09:43, 12 August 2012 (UTC)[reply]

Acoustic lubrication is also relevant. StuRat (talk) 09:46, 12 August 2012 (UTC)[reply]

There are two main applications of vibro-compaction. One type is the sort mentioned by StuRat - compaction and stabilising sand and soil, ready for future loads such as buildings and roads, by means of a vibrating plate or roller - see http://en.wikipedia.org/wiki/Soil_compaction. The other main type is compaction of concrete before it sets - this is done by a vibrating probe submerged and moved about in the wet concrete - see http://www.nicholsonconstruction.com/groundImprovement/vibroConcreteColumns.aspx. There are two main reasons for vibro-compacting concrete: It's easier to mix with an excess of water, and vibro-compactings can give an improved mix and move excess water to the top. Pooring concrete into confined spaces such as foundations columns has problems with voids and weak areas due to clogging by agregate - vibration during placement aids insertion of a consistent mix of agregate.

Compacted sand is often used to make a stable bed for houses and small commercial buildings in naturally sandy areas, and in rocky areas, as sand disturbed (by for example clearing or levelling a site) has a lot of air space and will subside over time if not compacted. For the same reason, road beds are compacted before laying the surface layer (butumen or concrete). A development of macadamising is sometimes used in rural roads where the cost of a bitumen surface is not justified by the traffic density. Whereas a bitumen surface requires thorough & costly preparation of the road bed to some depth, a macadam surface can be made over soil that has been merely graded. Modern macadmamising comprises spreading small stones (natural or crushed) of several selected sizes, (1 to 15 mm) to a thickness of 25 mm or so and then running a heavy vibrating roller over it. The vibrating roller re-compacts the graded under-surface, flattens the top, and mixes the various stone sizes to "lock" it all together to make a reasonably traffic and rain-proof smooth surface.

Wickwack11:06, 12 August 2012 (UTC) — Preceding unsigned comment added by 58.167.232.3 (talk)

animal with a large habitat in one continent

Looking for an animal whose habitat is very large (size of a medium size country) ; It can be found only in one continent ( nine countries of that continent)183.83.244.183 (talk) 10:05, 12 August 2012 (UTC) murthy[reply]

Is this for homework or for a trivia game? Evanh2008 ^{(talk|contribs)} 10:18, 12 August 2012 (UTC)[reply]

There are probably hundreds of thousands of animals, probably more, whose distribution range is that of a medium-sized country or larger. What animal were you specifically looking for? And what do you mean by "nine countries of that continent"? That's a rather arbitrary requirement, even more so given that animals don't exactly obey borders. -- OBSIDIAN†SOUL 10:25, 12 August 2012 (UTC)[reply]

Well, the nine countries requirement rules out North America and Antarctica. Dismas|^(talk) 12:49, 12 August 2012 (UTC)[reply]

Maybe Antartica but not necessarily North America, it depends on the definition. See List of North American countries by population. CambridgeBayWeather (talk) 15:48, 12 August 2012 (UTC)[reply]

The nine countries certainly rules out Australia. HiLo48 (talk) 17:43, 12 August 2012 (UTC)[reply]

This IP has now asked eight Refdesk questions over several months, and none have any merit. I suggest we not waste our time on this one. Looie496 (talk) 17:46, 12 August 2012 (UTC)[reply]

The questions all look like requests for help with riddles of some kind. Card Zero (talk) 20:00, 14 August 2012 (UTC)[reply]

Giant armadillo Count Iblis (talk) 18:00, 12 August 2012 (UTC)[reply]

How did you find that one? Ssscienccce (talk) 00:01, 14 August 2012 (UTC)[reply]

It is one of wikipedia's 18 official mammals. μηδείς (talk) 01:37, 14 August 2012 (UTC)[reply]

Race and sport

Is there any biological explanation as to why white swimmers are overrepresented in the same way as black basketball players? OsmanRF34 (talk) 14:33, 12 August 2012 (UTC)[reply]

I think it's more cultural than biological. 109.99.71.97 (talk) 16:44, 12 August 2012 (UTC)[reply]

Wealthy people are over-represented in swimming. Very tall people are over-represented in basketball. HiLo48 (talk) 17:07, 12 August 2012 (UTC)[reply]

I think there's strong evidence people with big feet are over-represented in swimming. See also [1] [2]. Nil Einne (talk) 17:25, 12 August 2012 (UTC)[reply]

On average, African-Americans have smaller proportioned calves and larger thighs and buttocks than white people. There is apparently a different muscle arrangement in the legs. I have never found this interesting or controversial so do not have any sources but white man can't jump, black men can't swim is a pretty common trope. μηδείς (talk) 18:14, 12 August 2012 (UTC)[reply]

There's a lot of really random things that happen in sport that have no basis in reality. Malcolm Gladwell covers in Outliers the fact that the greatest correlation for success in many sports is one's birthday: because youth leagues have an arbitrary cut off date, people whose birthday is just before the cut-off date are a year older than people whose birthday is just after said date. That means that those kids with the right birthday get better places on better teams, get more training, and ultimately end up being very over-represented at the highest levels of their sport. If the difference of as little as a few days in a birthdate (a fact which has no biological significance at all) can have such a huge effect on success in professional sports, then it is hard to say that anything biological (as opposed to social) is going on in the representation of certain arbitrary classifications of people as playing in certain sports. That is, there is no saying that with the proper training African-American atheletes couldn't be as good of swimmers as white swimmers or that white runners couldn't be as good as black runners. That they aren't right now doesn't mean there is anything in the biology preventing them from it. --Jayron32 19:30, 12 August 2012 (UTC)[reply]

Well, I don't know about preventing, but I imagine different people even within the same population would have a harder or easier time based on their genetics.--2002:B2A7:9A94:0:0:0:B2A7:9A94 (talk) 23:38, 12 August 2012 (UTC)[reply]

People are prone to all sorts of just so stories regarding race and sport. It's worth noting that in the early 20th century Booker T. Washington lamented that African-Americans were awful at sports and in generally bad health in general — a really obvious indication of the way that these things are likely as linked to social conditions as they are anything innately biological. There are all sorts of complicated dynamics in the United States in particular for who ends up in any particular sport — notice that almost all female gymnasts are from relatively poor white families, for example, for reasons I don't know.

All that being said, there are averages across genetic populations that may favor certain body-types, muscle concentrations, and other innate physical possibilities. I wouldn't read too much into them in most cases, though — the Olympics, for example, are about taking the tiniest sliver of the best end of the bell curve. Averages matter a whole lot less when you're taking the best-of-the-best — individuals, not population averages, are all that really count. In a few extreme cases, the benefits or detriments of a given population's genetic pool is going to make it very unlikely that any individual is going to be an outlier of significance (there are no pygmy basketball players), but I think for the vast majority of sports it is pretty clear that other social factors (identifying talent, incentivizing sports, training them well, plus extra things like sports medicine) are going to matter a lot more. (And anytime you start to think that for some reason whites are genetically predisposed, remember that China is the #2 medal winning country at the current Olympics. Funding for the social factors I've mentioned clearly is what makes the overall differences.) --Mr.98 (talk) 23:41, 12 August 2012 (UTC)[reply]

Some wise comments there, but I must pick you up on one not terribly critical but interesting point. In recent years in Melbourne, Australia there has been a basketball team made up entirely of short statured people. (Look here for definitions.) They found themselves a quality coach in the form of legendary Australian national player and coach, Lindsay Gaze. Their games against 12 year old teams of normal height people are still very challenging. Why do they do it? Who knows, but this country IS Bold textobsessed with sport. HiLo48 (talk) 07:49, 13 August 2012 (UTC)[reply]

A fair point — there are many ways to skin a cat, there are presumably many ways to shoot hoops. Presumably they play basketball in a way that maximizes their strengths and minimizes their weaknesses (e.g. emphasizing control of the ball and shooting as opposed to blocking and dunking, I guess; I'm not very fluent in basketball). --Mr.98 (talk) 15:35, 13 August 2012 (UTC)[reply]

This article is about a study which showed that young black males were more likely to suffer from negative buoyancy than their white counterparts, and therefore be at a disadvantage in swimming. "This result is now regarded as controversial. It seems unlikely that he would have deliberately produced misleading results, but racial origin is unlikely to have been the only difference between the two groups of students that would have an influence on personal buoyancy." Cullen Jones is cited as a counter example. Alansplodge (talk) 17:52, 13 August 2012 (UTC)[reply]

Unexpectedly valid folk taxonomies

Folk taxonomies are classifications made by laymen with words for biological groupings like cats or bird or bugs or shellfish which may or may not correspond to valid monophyletic or paraphyletic biological groups. Studies in the 1990's found that for the most part, lay classifications are not invalidated by biological ones, except when functional definitions apply. For example, shellfish can be described as sea food items which can't usually be caught by fishing. A term like critter is common in many languages, meaning small coldblooded creatures with legs, such as lizards and insects.

One interesting case is the term fowl in English. When bird became the general word for avians, the older word fowl was not lost, but applied more specifically to the folk taxonomy of gamebirds, the ducks and their relatives, the anseriformes; and the chickens and their relatives, the galliformes. This was a functional, not a scientific classification based on their relation to our mode of life, not their evolutionary relationship. But it turned out recently, with no one expecting it, that these two groups are each other's closest relative, forming the clade Galloanserae. I am curious if there are other folk taxa which have unexpectedly turned out to be biological taxa. Unfortunately, our folk taxonomy article is not at all helpful or complete. μηδείς (talk) 18:08, 12 August 2012 (UTC)[reply]

I'm not entirely certain you are correct on the fowl/bird thing. I always thought that fowl was the anglicized version of the French "poule" or Spanish "pollo", or "chicken", that is it made the same linguistic translations that other p/f words did between germanic and romance languages (c.f. father/pere) aka Grimm's law, and that the difference in categorization came either from categorical broadening (i.e. an older word refering to just chicken in English was broadened to a wider variety of birds) or constricting (i.e. a word that applied to a wider variety of birds in French was restricted to just chickens). --Jayron32 18:32, 12 August 2012 (UTC)[reply]

That's quite plausible, but in this case turns out to be wrong. The English is from the Germanic flug-la flying thing, cognate with German Vogel, while pullet comes eventually from pullus meaning young animal. Gallus was the older Latin word for chicken. See http://www.etymonline.com/index.php?term=fowl μηδείς (talk) 18:47, 12 August 2012 (UTC)[reply]

I stand corrected. I think, then, the answer to your actual question is "Even a broken clock is correct twice a day". That is, just because people with no scientific knowledge created a taxonomic word that happened to closely match the actual scientific taxonomy doesn't mean jack shit. Sometimes, dumb luck means that people get things randomly correct without trying. --Jayron32 19:22, 12 August 2012 (UTC)[reply]

I understood the question as "what are other examples of this" rather than "why is it so". 203.27.72.5 (talk) 19:55, 12 August 2012 (UTC)[reply]

(ec)Well, give them credit. Folk taxonomies aren't really noticeable when they're right. Words like "bird" or "wombat" weren't invented by professional taxonomists. Even when wrong, folk taxonomies were the starting point for more careful investigation, and often such investigation has gone through many false starts before it finally hit upon the right schema (we hope). In principle, laymen do the same thing as taxonomists - look for common morphological characteristics and design a cladogram. The only difference is the breadth of observation, for example when an amateur decides that having a "shell" and being a "fish" (or at least underwater) is enough to define a clade. Wnt (talk) 19:56, 12 August 2012 (UTC)[reply]

The studies I remember from the 1990's make a point of saying that there are two usual crtieria for folk etymologies: phenetic similarity (which usually corresponds to cladistic relationship) or functional classification based on human priorities. The "critter" concept, which is common in New Guinea languages, seemed to be based on smalll, low quality food sources that are unappealing and possibly toxic. Those are human concerns that cut accross biological relatedness resulting in a radically polyphyletic classification. Another example that might parallel the fowl/galloanserae case could be typically "African mammals" which would include things like the aardvark, the elephant, the hyrax, and the elephant shrew, which, despite earlier classifications, it turns out are members of the very recently discovered and highly unexpected Afrotherian clade. I am interested in anything in any way similar to these cases, whether actually polyphyletic or ultimately "true", for possible expansion of the folk taxonomy article. Interpret my question as broadly as possible. I don't want "correct" answers: I want "relevant/interesting/fruitful" answers. μηδείς (talk) 20:49, 12 August 2012 (UTC)[reply]

The difficulty here is in the word "unexpected". Unexpected by whom? Most folk taxonomies are broadly valid, although they are always ambiguous at the margins. Take "snake" as an example. That's a valid classification -- but is it unexpected? Looie496 (talk) 23:58, 12 August 2012 (UTC)[reply]

Cladistic is a related article. The thing is, animals related to each other do actually share traits with their relatives, so it's not really a surprise that someone grouping animals by traits will also inadvertently group them by evolutionary relationship. One funny story about cladistics is that in the 17th century, the catholic church ruled that beaver were a type of fish. Vespine (talk) 01:19, 13 August 2012 (UTC)[reply]

Dietary laws and culinary classifications are not at all the same thing as biological clades, and are not supposed to be. The tomato is a fruit, and so is the cucumber, but in culinary terms they are vegetables instead. You don't mock the scientific illiteracy of a chef who excludes tomatoes from the list of fruits that may go in a fruit salad. 86.157.148.121 (talk) 07:26, 15 August 2012 (UTC)[reply]

Yes. It's the rule, rather than the exception. Morphology still remains one of the most common basis for modern taxonomy. Thus it's really not surprising to biologists if organisms called by the same common names turn out to be closely related to each other. Early taxonomists even relied on it solely, with the absence of genetics, even if it meant groupings that are distorted by convergent evolution. Have a look at Linnaeus' early system in Systema Naturae. Note particularly his phylum Vermes.

So of course, "fish" turns out to be mostly valid, even if people did classify cetaceans as fish once too because they share the same body form. Contrast and compare that with the Biblical mention of bees making honey in a lion's corpse observed by Samson. From which observation he subsequently comes to the conclusion that this happens all the time and that bees really do come from dead lions. This belief was repeated by Virgil and Shakespeare. The more likely thing however, is that what they saw were bee mimics, which look remarkably like bees but are really flies. The lion was just rotting and maggoty, not miraculously transmogrifying into bees. But since they looked the same, it was a bee as far as they were concerned.-- OBSIDIAN†SOUL 01:36, 13 August 2012 (UTC)[reply]

Also see wastebasket taxon, for remnants of this practice in early taxonomy and a headache to modern biologists; and incertae sedis for organisms whose taxonomic relationships remain unclear.-- OBSIDIAN†SOUL 01:56, 13 August 2012 (UTC)[reply]

Take "unexpected" as the least limiting term, since it was thought of at the end of my musing in order to tie the thread together with a title--the case of fowl came first. Among many interesting comments, the bee-mimic answer is most interesting; I had never heard it before. As for fish, ther are shellfish, starfish, and jeelyfish as well as whales. It is perhaps the least valid folk taxon taht has slowly been made a valid one, with all the griping about how they should be called sea stars and sea jellies. They aren't stars either, are they? Silly biologers. μηδείς (talk) 02:09, 13 August 2012 (UTC)[reply]

Can't remember a book title - psychology or social science or possibly human evolution

I was at the bookstore browsing a few weeks ago, and I saw a book in the science section about how people learn to define other people as non-human, allowing them to justify the various atrocities people commit against each other. I didn't write down the title, and now I find I'm kind of curious to read it after all. Can anyone guess what I might have been looking at? -FisherQueen (talk · contribs) 19:00, 12 August 2012 (UTC)[reply]

That's a very old theme, so we will likely need more clues to narrow it down to a specific book. StuRat (talk) 19:55, 12 August 2012 (UTC)[reply]

Specifically, this is called Dehumanization. Vespine (talk) 01:43, 13 August 2012 (UTC)[reply]

Perhaps On Killing? Although it goes into more than dehumanization.--31.200.156.216 (talk) 12:39, 13 August 2012 (UTC)[reply]

It sounds to me like you might be looking for Steven Pinker's The Better Angels of Our Nature. I actually have not read this one as yet, despite being very impressed with his previous works; I recommend How the Mind Works and The Blank Slate quite frequently to people who are looking for an easily accessible primer to modern cognitive science in general and evolutionary psychology in particular. However, even having not read the more recent book, I have seen a number of his talks that he gave while he was researching it and the subject matter your describe is consistent with the themes he touched upon. I wouldn't be surprised if that's it. Snow (talk) 01:38, 14 August 2012 (UTC)[reply]

Earthquake damage

Last Thursday there was an earthquake on Lombok that measured 5.6 on the Richter scale. According to the article and my Google maps skills, the epicentre was about 150kms from my house on Bali. I did not even feel it and neither did my wife. Meanwhile, about 100m down the road, the building in the picture collapsed. Is this normal for an Earthquake of that magnitude so far away to cause that sort of damage? And is it normal that experinces of an earthquake are so varied just 100m appart? 203.27.72.5 (talk) 19:50, 12 August 2012 (UTC)[reply]

That is more difference than usual, but it is common for there to be considerable differences in nearby areas, due to differences in the ground stability and construction methods. I suspect, if a quake you didn't even feel destroyed a building 100 meters away, then that building design or construction was thoroughly flawed. StuRat (talk) 19:54, 12 August 2012 (UTC)[reply]

That's sort of what I suspected at first, here is picture of the shoddy buildings that survived. 203.27.72.5 (talk) 20:03, 12 August 2012 (UTC)[reply]

The intensity of vibration felt at a distance from the centre of a quake often isn't just a simple function of the distance from the quake - often the energy manifest at the surface is greater at points along the fault system than orthogonal to it. For example, look at the intensity distribution in this map of the Loma Prieta quake - people in west Oakland (60 miles from the epicentre) experienced more shaking than did people only 10 miles east of the epicentre. In addition, more shaking energy doesn't necessarily mean more damage. In San Francisco's Marina district (the north shore of the city) damage was greater than might be expected because the ground was soft and prone to soil liquefaction (see 1989 Loma Prieta earthquake#Marina District) - many places much closer to the epicentre, which experienced more shaking, exhibited less damage because structures were built on more solid ground. A failure of the ground is often a cause of building collapse - where one side of the ground gives way, leaving the building supported on one side and not on the other, as if you'd cut two of the legs off your kitchen table. Lastly the resistance of a structure to seismic damage is quite different from the solidity of its construction in ordinary circumstances - it's common to see unreenforced masonry structures fail when wooden structures (which can be more flexible, and which are easier to earthquake-proof) deformed but still standing. -- Finlay McWalterჷTalk 20:11, 12 August 2012 (UTC)[reply]

Your final point about masonry vs wood is probably the explantion here. That builing that collapsed was probably the shoddiest building nearby with a conrete foundation. The far shoddier looking buildings that survived were all wooden as far as I saw. 203.27.72.5 (talk) 20:24, 12 August 2012 (UTC)[reply]