Wikipedia:Reference desk/Archives/Science/2011 March 19

= March 19 =

car
what brand car is in this vid http://www.youtube.com/watch?v=4vS4U1xXQwQ — Preceding unsigned comment added by Wdk789 (talk • contribs) 02:00, 19 March 2011 (UTC)


 * This is a video clip running for 3 minutes and 10 seconds. It shows a very un-funny prank in numerous fast-food driveways.  The car is entirely irrelevant to the prank.  You can't see enough of the car to determine its brand.  I suggest no-one even bothers to download the video or watch it.  Life is short enough as it is without wasting a few minutes on boring stuff like this.  Dolphin  ( t ) 04:25, 19 March 2011 (UTC)


 * It is pretty funny. At points it sounds like this. Bus stop (talk) 01:54, 20 March 2011 (UTC)

lights
how do they change the head lights in this http://img.ibtimes.com/www/data/images/full/2011/03/17/75371-dd.jpg — Preceding unsigned comment added by Wdk789 (talk • contribs) 04:26, 19 March 2011 (UTC)


 * This is just a link to a photograph of spent fuel rods at the bottom of a pool of water in a nuclear reactor. There is no car, or any other vehicle, visible in the photograph so there are no head lights.  Don't bother.  Instead, spend the time checking out the contributions from Wdk789.  Dolphin  ( t ) 04:31, 19 March 2011 (UTC)


 * Perhaps he meant to ask how they change the lights in the radioactive areas of a nuclear plant, and mistakenly called them "headlights" ? StuRat (talk) 17:22, 19 March 2011 (UTC)

yes — Preceding unsigned comment added by Wdk789 (talk • contribs) 22:06, 19 March 2011


 * The glow on that reactor, though, is Cherenkov Radiation and a natural effect in the air above energetic particles flying about. Whatever additional lights are used are probably fluorescent tubes energized also by the reactions themselves, thus not needing to be changed. Of course, the nature of such a reactor design is such that it's actually safe to walk around it with an open top. SamuelRiv (talk) 05:34, 20 March 2011 (UTC)


 * Assuming those are ordinary electric lights, I would change them by lowering the level of the water (they keep the water level higher than necessary as a safety margin). Then I would suspend someone in harness from a crane or hoist in the ceiling and have them change the light. Ariel. (talk) 00:38, 21 March 2011 (UTC)

Liver question
What is difference between compensatory hyperplasia and regenration of liver? —Preceding unsigned comment added by 210.2.181.244 (talk) 07:47, 19 March 2011 (UTC)

Does bicarb remove the acidity of acetic acid (apple cider vinegar)?
Can I just confirm that adding any amount of bicarbonate of soda would lower the acidity affects of vinegar (acetic acid)? The fact that bicarb is an 'amphoteric' (react as an acid as well as a base) doesn't clarify whether it would make vinegar more effective or less? 220.244.35.181 (talk) 09:43, 19 March 2011 (UTC)
 * It reduces the acidity of acids, because it acts like a base when in contact with acids. Grandiose (me, talk, contribs) 10:40, 19 March 2011 (UTC)


 * Thanks! you know what's also interesting and confusing, is that there is a formula for getting rid of mould/mildew in showers - and it instructs that you mix white vinegar with bicarb: the vinegar is to kill the mildew and the bicarb is to eliminate the odour of the vinegar - but how would that work if the two cancel eachother out???

220.244.35.181 (talk) 10:49, 19 March 2011 (UTC)


 * It confuses me too, when the ingredients are mixed, they no longer act as two substances with distinct properties. The new substance produced, is a solution of sodium acetate with completely different properties. Plasmic Physics (talk) 11:15, 19 March 2011 (UTC)


 * that's simplistic. vinegar + bicarbonate forms a buffer solution at some fixed pH (so long as there is not an overwhelming amount of either the vinegar or the bicarbonate.). This pH is still acidic enough to kill unprotected mildew. The free acid CH3COOH is what is smelling like vinegar (vinegar is volatile and evaporates). That's because it's at a considerably low pH (vinegar has around a pH of ~2.4) so there's a lot of free acid. A buffer solution of sodium acetate and acetic acid I believe, has a pH of around 4.76. That's still acidic enough to hinder growth, but not that acidic. Also, the acetate ions help sequester the free acid RCOOH molecules from evaporating. 199.111.169.216 (talk) 16:34, 19 March 2011 (UTC)

Just remember that mixing the two gives you a nice release of CO2, making it ooze bubbly foamy stuff. Fun thing to show your kids. SamuelRiv (talk) 05:36, 20 March 2011 (UTC)


 * OP here. Thanks for the help. Then it's confirmed, I won't be mixing any bicarb with the vinegar because we want a lower pH level. Thanks 220.244.35.181 (talk)


 * What does the atmospheric pressure of CO2 have to be for the dominant equilibrium to be: carbonic acid + acetate <-- -> acetic acid + bicarbonate? 199.111.185.182 (talk) 16:40, 20 March 2011 (UTC)

Identifying an actual triquetral bone
On File:RightHumanAnteriorDistalRadiusUlnaCarpals.jpg and File:RightHumanPosteriorDistalRadiusUlnaCarpals.jpg, which bone is the triquetral? I've left an image note on the anterior image for what I think is the triquetral, but I can't be sure, and I don't think it's visible in the posterior image. Nyttend (talk) 12:00, 19 March 2011 (UTC)
 * According to the article triquetral bone, it is the triangular bone marked C, not D. See the summary notes here.. Cuddlyable3 (talk) 13:50, 19 March 2011 (UTC)


 * According to Gray's Anatomy here the small bone marked 'D' is the pisiform and the other bone, 'C', is called the triangular or os triquetrum. Richard Avery (talk) 14:46, 19 March 2011 (UTC)
 * So I marked the bone labelled D? I know that it's C — my problem is that I can't easily figure out which bones in the diagram correspond to which bones in the photograph.  If I marked the wrong one, would you please remove the note and place it on the correct bone?  Nyttend (talk) 17:43, 19 March 2011 (UTC)
 * Oh, I just realised that I gave the wrong caption to the image here. Sorry — that was a typo, and I meant to say "C" on the caption.  Nyttend (talk) 17:55, 19 March 2011 (UTC)

Which is this?
Video. Is this a MiG-23 or a MiG-27? 1:16 in the video or so is probably the best image. These are very similar aircraft, so maybe we can't tell. SDY (talk) 13:53, 19 March 2011 (UTC)


 * Libyan air force says "On 19 March 2011, the rebels shot down one of their captured MiG-23BN over Benghazi", but only sites as a reference that same video, which doesn't explicitly make that identification. -- Finlay McWalter ☻ Talk 14:00, 19 March 2011 (UTC)


 * Agenzia Giornalistica Italia identifies it as a MiG-23 (but doesn't specify which type) here, but the Sydney Morning Herald says it was later identified as a Mirage here. -- Finlay McWalter ☻ Talk 14:20, 19 March 2011 (UTC)


 * Sky News also claims it's a MiG-23 here. -- Finlay McWalter ☻ Talk 14:25, 19 March 2011 (UTC)


 * It can't be a Mirage, the planform is completely wrong. SDY (talk) 14:37, 19 March 2011 (UTC)

Matter to energy
If matter is converted to energy, and the matter happens to be in a gravitational field, then what happens to the matter's gravitational potential energy? —Preceding unsigned comment added by 86.183.1.249 (talk) 14:36, 19 March 2011 (UTC)
 * See gravitational redshift. Icek (talk) 15:29, 19 March 2011 (UTC)
 * Matter is NOT converted to energy. Matter IS a form of energy. When matter is converted to a different form of energy its potential energy remains there because the new form of energy still possesses a relativistic mass given by the famous formula E=mc2 identical to the mass that the matter had before. Dauto (talk) 16:07, 19 March 2011 (UTC)
 * Is this connected to the fact that an object weighs more when it is heated? The gravitational potential of the heat energy is manifested as extra weight? 86.160.211.135 (talk) 18:47, 19 March 2011 (UTC)


 * Yes, that's it. Any form of energy has a mass given by E=mc2. Dauto (talk) 19:29, 19 March 2011 (UTC)
 * Thanks for your help. 86.160.211.135 (talk) 20:05, 19 March 2011 (UTC)

Aquatic minibeasts
Okay, this is a long shot. What minibeasts might I have seen in a sunny ditch in Oxfordshire? The ditch was calm and a sort of temporary (but recurring) pond in the middle of a field. It still had alive-looking grass at the bottom. There were a few minibeasts that looked like pale mites or ticks, gliding through the water, but the ones I'm most interested in were there in large numbers, and looked like small ants although I didn't see legs. They were reddish-brown and moved constantly in a jerking motion: their movement was made up of lots of little straight-line pushes, a bit like Brownian motion but with acceleration that looked like little repeated pushing glides. Perhaps they move by releasing something suddenly behind them?

I'm aware this may not be possible without a picture, but I appreciate any information. 212.183.128.107 (talk) 15:03, 19 March 2011 (UTC)


 * I'm not sure about jet-type propulsion, but at that size class*, a high density critter in an ephemeral pool is likely an aquatic insect larva. See a visual overview of shapes here . Did they look at all like mosquito larvae? Some sort of Dipteran larvae would be my guess with such limited info. *I assume 'small ant' size is ~1-2mm. SemanticMantis (talk) 16:50, 19 March 2011 (UTC)
 * Another guess which fits with "moved constantly in a jerking motion" is Daphnia which are very common even in quite small pools in the UK. Country folk call them "water fleas". Mosquito larvae tend to wriggle and it may be too early in the year for them. Another slightly smaller relative is the Cyclops. They both have a little pair of arms with which they do a sort of butterfly stroke - hence the jerking action. The best thing is to fish some out in a jam jar next time you're passing and have a look with an ordinary magnifying glass. This page is a simple key to pond invertibrates; click on the drawing for more details. This page is more comprehensive, but not so easy-peasy. Alansplodge (talk) 19:50, 19 March 2011 (UTC)
 * Me again. Looking at the naturegrid.org.uk page linked above, it says that "Daphnia contain haemoglobin - which is also found in human blood. This substance can hold and process a lot of oxygen. It turns red when it contains oxygen." That fits with the reddish-brown colour that you reported. Alansplodge (talk) 20:16, 19 March 2011 (UTC)

Thanks (I'm the OP), this is all really good. I agree that a jamjar and magnifying glass would make this a lot easier: I might be able to try that in a couple of days. I was pretty sure they weren't mosquito larvae, partly because it seems too early, but also because I first went to look closer because of the sparkles on the water: I wanted to see if it was air bubbles or little creatures like mosquito larvae. And these weren't doing the tube-to-the-surface thing that mosquito larvae do (unless they don't always do that: I shall look it up). I didn't think they were water flea or triops/cyclops shape, although maybe the angle they are in the water makes them look different. 86.164.66.59 (talk) 23:25, 19 March 2011 (UTC)
 * Daphnia are roughly disc-shaped, so viewed from above they would look different to the linked photos which all show the side view. However it may well be something else; I'm an amateur at pond-dipping. Good hunting! Alansplodge (talk) 01:51, 20 March 2011 (UTC)

Ocular dominance vs. amblyopia
If one cannot read (discern letters) with his left eye when the right eye is closed, is this an ocular dominance or rather amblyopia?--89.76.224.253 (talk) 16:01, 19 March 2011 (UTC)
 * It isn't either one of those things. Ocular dominance and amblyopia are both conditions in which one eye dominates the other when both are open -- neither says anything about what happens when one eye is closed.  See ocular dominance and amblyopia for more information. Looie496 (talk) 18:20, 19 March 2011 (UTC)
 * Um, let me correct that. Amblyopia is a condition in which one of the two eyes sees poorly in an absolute sense -- but there are many conditions other than amblyopia that can cause one of the two eyes to see poorly. Looie496 (talk) 20:08, 19 March 2011 (UTC)
 * I recently spent some time reading about various eye conditions. Lazy eye seems to present in a way that it can be observed by other people (check google for images). Eye dominance is natural preference of one eye over another (muck like beeing right or left handed). What you describe might as well be something else (say, a refraction error in left eye) Xil  (talk) 10:07, 20 March 2011 (UTC)

Identifying the contents of a 55-gallon drum by the torn remnants of its MSDS
During a recent binge of idiocy my friend decided 55-gallon drums would make awesome trash bins. Except he didn't want to buy them new, so he dumpster-dived a few. The several we already have work fine (as their MSDSes were intact and didn't show anything freaky)... but one of them is kind of worrying. This particular black plastic 55-gallon drum was discarded by a now-defunct steel and wire processing company and most of the attached MSDS was destroyed by the elements. From what we can read though it's kind of awful, so I really want to know what's on the rest of the MSDS. I know there are different categories of danger based on the wording of the sentence (i.e. "may be harmful if ingested" and "harmful if ingested" and "toxic if ingested" and "poisonous if ingested" denote totally different levels of toxicity). So can anyone get an idea of what this crap is (or give me tips as to doing the same) based on this meager information? (Words that have worn off replaced with #)

On the barrel itself was a stamped sequence of numbers "USA/R-1608/RL/03/10".

SKIN CONTACT Remove contaminated clothing. Wash affected #### with soap and water for at least 15 minutes #### medical attention of irritation persists. EYE CONTACT Remove contact lenses. Hold eyelids apart and flush with plenty of water for at least 15 minutes. Seek immediate medical attention if irritation persists. INHALATION Remove victim to fresh air. Restore breathing if necessary. Seek medical attention if irritation persists. INGESTION Seek prompt medical attention. Do NOT induce vomiting. Never give anything by mouth to an unconscious person. See MATERIAL SAFETY DATA SHEET for additional health-related information. OTHER PRECAUTIONS Use all personal protective equipment. Observe good personal hygiene practices, such as washing after handling and before eating, drinking and/or smoking. KEEP OUT OF REACH OF CHILDREN appl############## enter s########### has enter######### exte############## WASTE ############ Uncontaminated ### tim### Recyclin### disposal. Foll#### H################# Keep from freezing. Store###### area away from all ignition s## incompatibles. Keep containe### MSDS Rev No. 01 MSDS Date: 03/12/10
 * 1) be harmful if swallowed. May cause mild to severe eye irritation upon prolonged, repeated exposures. Prolonged or repeated exposure may cause skin ### defatting and irritation ranging from mild to severe. May cause mild to severe respiratory irritation with repeated, prolonged exposures.
 * 1) be harmful if swallowed. May cause mild to severe eye irritation upon prolonged, repeated exposures. Prolonged or repeated exposure may cause skin ### defatting and irritation ranging from mild to severe. May cause mild to severe respiratory irritation with repeated, prolonged exposures.
 * 1) be harmful if swallowed. May cause mild to severe eye irritation upon prolonged, repeated exposures. Prolonged or repeated exposure may cause skin ### defatting and irritation ranging from mild to severe. May cause mild to severe respiratory irritation with repeated, prolonged exposures.

I'm thinking of just googling the longest intact segments or running them through a MSDS search engine, but anything else that works better would be a hell of a great help. ZigSaw 20:41, 19 March 2011 (UTC)


 * One hopes R-1608 might be a product number (no guarantees). But isn't there a company name on the barrel (not the wire company that bought it, but the manufacturer)? Wnt (talk) 21:23, 19 March 2011 (UTC)
 * Let's just hope he doesn't find the number 311-555-8674 stenciled on it. ;) Wnt (talk) 21:26, 19 March 2011 (UTC)
 * You've forgotten to put the thing canvcelling the small type. 92.24.178.214 (talk) 23:23, 19 March 2011 (UTC)


 * R-1608 is one of the names for an herbicide more commonly known as EPTC or eptam. It appears to have toxicity data similar to that on the label. Looie496 (talk) 23:26, 19 March 2011 (UTC)


 * The points listed above are on just about every MSDS ever made. I would suggest looking for a different drum. Or at least rinse it out and line the drum with a couple garbage bags to keep a barrier between your nice new garbage and whatever was originally in it. 50.92.121.76 (talk) 22:39, 20 March 2011 (UTC)

Humans from Africa
When humans spread out from Africa, were there already some human-like creatures (such as Neandertals and others) in the land they expanded into? Thanks 92.24.178.214 (talk) 23:20, 19 March 2011 (UTC)


 * The answer is yes. Just be careful to define what you mean by human. Neanderthals may also be considered human depending on your definition. Dauto (talk) 23:39, 19 March 2011 (UTC)


 * The article Early human migrations will get you started on this question, and you may find further relevant details by following links from it. You will also find a useful table of the different known Human/Homo species in the Homo article, and further details towards the end of Timeline of human evolution.
 * Briefly, when the only (known) now-surviving human subspecies Homo sapiens sapiens first spread beyond Africa (though many stayed there), there were likely still some closely related sub-species in Africa such as Homo sapiens idaltu, perhaps also some of the last Homo antecessor and/or Homo heidelbergensis whose earlier emigrants to Europe had evolved into Neanderthals, and possibly some surviving Homo ergaster (aka "African erectus") from whom H sapiens had evolved (also via H antecessor and heidelbergensis), and Homo rhodesiensis.
 * (Remember, when one species evolves "from" another, it often does so in one particular locality because of special conditions there, leaving populations of the first species still continuing to live elsewhere, from whom further species may subsequently evolve - there is not necessarily a strict line of succession and immediate replacement.)
 * Beyond Africa there were already: the species/subspecies Homo neanderthalensis/Homo sapiens neanderthalensis in the Levant and Europe (with whom H sapiens sapiens then interbred); Homo denisovan (or H sapiens denisovan?) in parts of Eurasia, (with whom some H sapiens sapiens also interbred); Homo erectus (divided into several localised sub-species) throughout Eurasia, Indonesia and possibly parts of Australasia (with whom H s s probably did not interbreed - though see Homo erectus soloensis - and whom we replaced), and Homo floresiensis (perhaps a descendant from erectus, perhaps from an Australopithecus species, perhaps something else - the jury is still out) in Flores and perhaps elsewhere.
 * There may well have been other localised Homo species and subspecies that we have not yet discovered. Several of the above-mentioned varieties of humans are known only from very few fossils, so future finds may well extend their currently confirmed time spans nearer to the present day. {The poster formerly known as 87.81.230.195} 90.197.66.165 (talk) 01:24, 20 March 2011 (UTC)