Wikipedia:Reference desk/Archives/Science/2011 May 15

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May 15[edit]

the brain's Physical quantity of dwarfs and the fact they are smart just as any other human[edit]

thanks.

Please put this in question form. Plasmic Physics (talk) 02:56, 15 May 2011 (UTC)
There are over 200 distinct medical conditions which can cause dwarfism. Most people with dwarfism have normal intelligence, and in particular, achondroplasia, which accounts for about 70% of cases of dwarfism, is not associated with diminished intelligence. However, some of those 200+ medical conditions do result in mental impairment. See Dwarfism#Characteristics. Red Act (talk) 11:39, 15 May 2011 (UTC)
And I believe most dwarfs have brain (and head) sizes in the normal range, too. This makes the head disproportionately large. There are proportionate dwarfs, though, historically called midgets, where the brain would be smaller. I believe Gary Coleman from Diff'rent Strokes and Emmanuel Lewis from Webster (TV series) are examples (they are sometimes used on TV to play children, since they appear to "stay young" longer). StuRat (talk) 16:40, 15 May 2011 (UTC)

are there any scientifically proven FOODS there a long-term eating of them could improve\enhance the human vision\eye-sight system?...[edit]

thanks.

I don't know about improving your eyesight, but lutein and zeaxanthin, found in green leafy vegetables and other foods, are supposed to be good for protecting the eyes against macular degeneration and cataracts (see lutein#Role in human eyes and zeaxanthin#Relationship with diseases of the eye). At least, some studies show a connection, though the US Food and Drug Administration isn't totally convinced, according the the zeaxantin article. Clarityfiend (talk) 00:56, 15 May 2011 (UTC)

I've read that fish oils and Vitamin D can also prevent macular degeneration. Count Iblis (talk) 01:16, 15 May 2011 (UTC)
Likewise, Vitamin A and the related molecules known as the carotenes are vital to eye health. --Jayron32 01:25, 15 May 2011 (UTC)
During WW2 in order to conceal their invention of radar the British put out a myth[1] that they were feeding their pilots carrots to improve their night vision. This claim is still heard but don't believe it (unless you are German and WW2 is on). Cuddlyable3 (talk) 18:01, 15 May 2011 (UTC)

Ice age Australasian straits[edit]

Ice age Australasia

At the time when Australia was first peopled (~40,000 years ago or more), what modern strait would be/correspond to the widest sea gap faced by people coming from Southeast Asia (Sunda shelf) to New Guinea-Australia (then joined because of lower sea levels)? 98.194.39.132 (talk) 06:07, 15 May 2011 (UTC)

The Selat Lombok between Bali and Lombok would have been the first water encountered. But the widest part would have been the Timor Sea. Other possible routes may meet the Molucca Sea, Seram Sea or Halmahera Sea. You may also want to read Wallace Line which includes a map at the time you are interested. Graeme Bartlett (talk) 10:45, 15 May 2011 (UTC)
OK, thanks. I think the Timor Sea is what I'm looking for... 98.194.39.132 (talk) 16:33, 15 May 2011 (UTC)
As Graeme said, it's not that simple. There is really no way to understand the situation except by looking at a map -- I've appended the one from the Wallace Line article. Looie496 (talk) 17:07, 15 May 2011 (UTC)

UL or other agency approval or certification[edit]

In what situations a UL or other agency approval or certification is needed for electrified public structures? —Preceding unsigned comment added by Mustafa-900 (talkcontribs) 10:00, 15 May 2011 (UTC)

Public structures have to be approved by a Professional Engineer??[edit]

Is there a law, rule or a regulation that says:

"Public structures have to be approved by a Professional Engineer" or

"...drawings of public structures have to be evaluated and signed by a professional engineer" or

"no change to those drawings can be made without the approval of a professional engineer" —Preceding unsigned comment added by Mustafa-900 (talkcontribs) 10:04, 15 May 2011 (UTC)

It would be helpful if you said what jurisdiction you were worrying about? In general though, most jurisdictions in the developed world will require that some form of licensed and accredited individual (e.g. civil engineer, architect, building inspector) approve of any new construction that is intended for public use. Dragons flight (talk) 10:24, 15 May 2011 (UTC)
This is a question about law, not science. I believe the Humanites Refdesk is the correct place for it. Roger (talk) 10:34, 15 May 2011 (UTC)
I'm not so sure. Laws dealing with science could be handled here. StuRat (talk) 16:27, 15 May 2011 (UTC)

Minimum thread engagements[edit]

Is there a law, rule or a regulation about minimum thread engagements for load carrying bolts for public structures? —Preceding unsigned comment added by 24.229.140.47 (talk) 10:16, 15 May 2011 (UTC)

There are probably thousands of such laws: they are called building codes, and they delve into alarming levels of detail. The applicable laws and building codes will depend entirely on your country, state/province, and local jurisdiction. If you are in the United States, you could check with your local ASCE chapter for rough advice about applicable laws, as well as conventional industry-practice. If you are actually building a structure, you should have a Professional Engineer, an attorney (or several), and a building inspector involved in the process; one or all of those people will know where to get specific information on such details. Nimur (talk) 15:58, 15 May 2011 (UTC)
Does ISO 965 help? hydnjo (talk) 15:58, 15 May 2011 (UTC)

interference reason[edit]

I AM CONFUSED THAT IS PATH DIFFERENCE NECESSARY FOR INTERFERENCE ?CAN INTERFERENCE TAKE PLACE WITHOUT PATH DIFFERENCE? —Preceding unsigned comment added by Nikhil320 (talkcontribs) 11:48, 15 May 2011 (UTC)

According to Interference (wave propagation), a path difference is not necessary. If the paths are equal then you get 100% constructive interference (i.e. double the amplitude); if they differ by half a wavelength then you get 100% destructive interference (i.e. zero amplitude). For intermediate cases you get something in between. --Heron (talk) 12:13, 15 May 2011 (UTC)
A path difference doesn't always mean a phase shift. Two different paths can be of equal length or the difference can be an integer multiple of the wavelength, in which cases the phases will be the same at the receiver. StuRat (talk) 16:26, 15 May 2011 (UTC)
Also relevant: Optical path length is affected by index of refraction, so two optical paths may have different optical path lengths (for example, one may pass through a glass lens and the other passes through air), even if both distances are the same. Nimur (talk) 15:53, 15 May 2011 (UTC)

Sailing stones[edit]

what is the phenomena or reason behind the "SAILING STONES"? —Preceding unsigned comment added by 175.110.91.49 (talk) 18:24, 15 May 2011 (UTC)

We have an article Sailing stones which gives some ideas. The bottom line is that a desert is not always dry, and the winds in that area are quite strong. Wnt (talk) 18:31, 15 May 2011 (UTC)
It is still somewhat of a mystery though. No one knows for sure. --T H F S W (T · C · E) 21:29, 15 May 2011 (UTC)
I heard somewhere that this was fairly recently solved quite conclusively, trying to find a reference. Vespine (talk) 23:10, 15 May 2011 (UTC)
Sailing stones explains that ice, and ice floes, are also thought to play a part. Dolphin (t) 00:05, 16 May 2011 (UTC)
There are a few theories, but the three that have the most support are:
  1. Ice is forming around the rocks and raising them, allowing them to "float" on a near frictionless bed of ice, and be pushed by the wind,
  2. Rare but significant rains create a slick of water on the floor of Racetrack Playa, which wets the clay creating a very low-friction surface which the winds can then push the stones along, or
  3. Some combination of these two theories.
I recently read this scientific article (at least, that's what I call it if my boss sees it) which suggested that the mystery had been solved, but a review of recent literature shows there is still no hard consensus among geologists.-RunningOnBrains(talk) 01:49, 16 May 2011 (UTC)

──────────────────────────────────────────────────────────────────────────────────────────────────── I am wondering if daily cycles of thermal expansion and thermal contraction can play a role here. If the rock was initially moved a bit by strong gusts, then that movement would create a clean track under the rock and behind it. On the front side, the ground would be a bit rougher. Then, it seems to me that the rock expanding and contracting could move it further forward. When the rock expands, the front side, which is very close to the edge where the rough ground starts, can move over the rough side a bit, due to different thermal expansion coefficents of the ground and the rock. It can then experience much more friction there, so that in the contraction cycle, it doesn't move as far back as it moved forward. Count Iblis (talk) 02:48, 16 May 2011 (UTC)

An interesting theory, but it doesn't fit observations. The stones don't move millimeters at a time, they sit still for years at a time and then suddenly move hundred meters overnight. The actual motion itself has never been observed. -RunningOnBrains(talk) 04:58, 16 May 2011 (UTC)
Correction, until very recently the movement hasn't been observed. There's a video on youtube now showing just that. It was linked to from a recent article about scientific "mysteries" that actually have really obvious answers HominidMachinae (talk) 07:55, 16 May 2011 (UTC)
I believe this is the video you are referring to. While they do observe water flowing across the valley floor, they do not observe the stones themselves moving. Also, all joking aside, I don't consider Cracked to be the most reliable of sources :) (I actually linked to that article above). -RunningOnBrains(talk) 08:16, 16 May 2011 (UTC)
Cracked is oftentimes sourced by wikipedia so it's at least as reliable as we are in most cases. I've generally found their writing to be a bit sensationalist and a bit heavy on puerile humor but generally factually accurate. I just wish they would provide more of a bibliography for some of their pieces. HominidMachinae (talk) 03:20, 17 May 2011 (UTC)

graph in excel[edit]

(I posted this at the Computing desk, but it's probably more appropriate here)

I should be able to get my head around creating a graph in Excel 2007, but I can't. Please help me.

I want a line graph, and I want two lines on it, for, say, reaction with X and reaction without X. For each line there are five data points, I want v on the vertical axis and v/s on the horizontal axis (so ten figures to table for each line). It would be super simple to do this by hand but I need to do it in Excel, and I can't work out how to set up the table so that Excel has any clue what I'm after. How do I table this data so Excel's graphing function can make sense of it? Thanks a lot. Howie26 (talk) 19:00, 15 May 2011 (UTC)

Something like this?
v/s v (with X) v (without X)
1 4
3 6
5 8
6 9
8 11
2 1
7 3
8 5
9 6
10 8
RD-S sample graph.png
The graph is a "scatter" graph style. DMacks (talk) 20:32, 15 May 2011 (UTC)
OpenOffice.org graph
Just to use the opportunity to plug Openoffice.org, a free alternative to Microsoft (Actually the Go-oo version to be precise), I typed in your numbers, selected Insert -> Chart..., chose chart type Scatter, selected the appearance with lines, hit Finish, and dragged out the right side a little to make the perspective more like yours. The program is generally the equal of Excel, with the glaring exception that even the Go-oo version has a hard time handling more than about 20,000 of certain operations at a time, which IMHO is often the whole point of using a spreadsheet. Wnt (talk) 20:49, 15 May 2011 (UTC)

Precisely what I wanted!! Thank you both! Brilliant! Howie26 (talk) 21:40, 15 May 2011 (UTC)

DARAPRIM COMPOUND TAB. quinine dihydrochloride[edit]

This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis, prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page.
This question has been removed. Per the reference desk guidelines, the reference desk is not an appropriate place to request medical, legal or other professional advice, including any kind of medical diagnosis or prognosis, or treatment recommendations. For such advice, please see a qualified professional. If you don't believe this is such a request, please explain what you meant to ask, either here or on the Reference Desk's talk page. --~~~~

Tevildo (talk) 20:36, 15 May 2011 (UTC)

Tomatoes[edit]

If you swallowed a small tomato whole without chewing it, would it come out the same as it went in?

Nope. Assuming it made it down your throat without choking you, your gastric acid would dissolve it (or most of it), and I think your intestines would squeeze it up. However, there may be large bits identifiable as tomato in your feces. Of course, never try swallowing a tomato; the most likely thing that would happen is it would block your throat and you'd suffocate. It might also block an intestine, needing a medical operation to take it out. --T H F S W (T · C · E) 21:28, 15 May 2011 (UTC)
Based on your earlier attempt to ask the same question, I would say the reason is that the skin is not a perfect membrane - gastric acid can attack a tomato at the place where it was attached to the vine, aswell as through pores on the surface.
So, in the hypothetical stuation you tried to propose, the tomatoe flesh would be digested regardless whether it is whole or not, independent of the state of the skin. Plasmic Physics (talk) 01:51, 16 May 2011 (UTC)
I am unconvinced that small tomatoes would always dissolve in the stomach acid. Various animals eat berries and they are still reasonably intact in the feces. Tomatoes can be soaked in vinegar and are thus preserved for a year or longer, with no evident dissolution by the acid [2]. The two acids have similar pH [3]. Even if gastric juice has a lower pH than household vinegar. the lack of tomato pickles being dissolved at all in over a year casts doubt on their being dissolved in a few hours in the stomach. Small cherry tomatoes, still green, would be hard and resistant to crushing, but perhaps a choking hazard, so I recommend against making the attempt. Edison (talk) 19:04, 16 May 2011 (UTC)
Vinegar is definitely nothing like stomach juice, you can pickle just about anything in vinegar and it won't dissolve, boiled eggs, gherkins, onions, you aren't suggesting that all of those come out the other end in tact when you eat them? Vespine (talk) 01:49, 18 May 2011 (UTC)
I'm too bored to explain, but corrosivity is not all in the pH. Plasmic Physics (talk) 12:44, 17 May 2011 (UTC)
See pepsin, which relies on acid for function. The stomach acid is not actually necessary to digestion, since users of various antacids and other drugs to neutralize stomach pH still digest their food, more or less. (Though I've heard they have some surprises with food colors surviving to the far end) I bet it really helps if you make a habit of eating sharp chips of bone, though... Wnt (talk) 10:39, 18 May 2011 (UTC)

Skullology or Skull-Osteology or what? - how should i say "skullology" in scientific terminology?[edit]

Thanks? —Preceding unsigned comment added by 109.67.5.122 (talk) 22:02, 15 May 2011 (UTC)

Unless there is an actual need for a defined "field", there may not be a name for it, especially if there isn't anything particularly unique to the field. I think it's unlikely there are people who study "skulls" in general, there would certainly be various osteologists (and probably palaeontologists) who specialize in skulls, but that's different, it doesn't mean they necessarily need their own distinct name. There used to be Craniometry and Phrenology but they were pseudo scientific. Vespine (talk) 23:04, 15 May 2011 (UTC)
My local hospital had a Cranio-Facial department, which dealt with the bones of the skull and face. I always thought that was the proper name for the medical specialism. --TammyMoet (talk) 12:17, 16 May 2011 (UTC)

Thanks.

i would like to have a good site \ FA which is dedicated to the differences between Male skull and Female skull, now, in the evolution, and some info about the etiology of the Difference.

thanks. —Preceding unsigned comment added by 109.67.5.122 (talk) 02:35, 16 May 2011 (UTC)

Gray's Anatomy has a section on Sexual Differences in the Skull which is quite technical.. I'm not sure you'll find much more then that. I wouldn't think there's anything evolutionary or etiologically unique about the differences in the skull as opposed to the rest of the skeleton in general. Vespine (talk) 03:54, 16 May 2011 (UTC)
Craniology. DRosenbach (Talk | Contribs) 19:47, 25 May 2011 (UTC)