Wikipedia:Reference desk/Archives/Science/2014 August 11

= August 11 =

Locking pin
What is a locking pin? Is it the same thing as "Split pin" ? From the google images it looks like it is. If I translate from Romanian ro:Splint (which means "split pin") into English, then I get "Locking pin". If it's not the same thing, then can anyone start a stub about it or at least help me with some info so I can start such a stub? Thanks. —  Ark25  (talk) 00:15, 11 August 2014 (UTC)


 * In the US we call it a cotter pin, although that seems to mean something else in the UK. StuRat (talk) 00:19, 11 August 2014 (UTC)


 * I don't think there is much difference in usage, except that cotter is the connecting pin in the UK, with the word "cotter" (on its own) not normally used for the locking pin that keeps the cotter in place. The locking pin (cotter pin in the US and sometimes also in the UK) can be a split pin or a locking device of a different design (R-clip or split ring). The locking could also be achieved with a circlip (snap ring) invented by Coates & Carver of Manchester (England) around 1890.   D b f i r s   08:45, 11 August 2014 (UTC)


 * I've never heard of a cotter pin being referred to as a cotter in the UK, and I've never heard a split pin called a cotter pin. DuncanHill (talk) 09:39, 11 August 2014 (UTC)


 * I think there are regional variations in usage.   D b f i r s   12:31, 12 August 2014 (UTC)


 * A cotter pin in britenglish is quite different to a split pin. The most familiar example used to be the cylindrical bolt with a tapered flat wedge section used to tighten the crank of a bicycle to the front chain wheel's axle. Similar but more elaborate devices were used to hold steam engines together. A split pin is merely a D shaped cross section of wire wrapped around to form a cylindrical, but split, pin. I suggest the OP post a photo or find one online to show us, as there are many options. In engineering terminology I would be quite happy to call many wedge type fixtures cotters. Greglocock (talk) 09:47, 11 August 2014 (UTC)

(sorry for late answer) Well, I was just wandering if the term Locking pin really means something in English. Searching on Google, I get the photos with split pins or things like this. Maybe the term "Locking pin" is used by some to designate a spit pin and by others to name particular type of nail, like the one in the above image. —  Ark25  (talk) 21:28, 14 August 2014 (UTC)

Footprints in streambed
If someone leaves footprints on the bottom of a small stream (as was the case in Fenimore Cooper's The Last Mohican), how long would they typically last before they're washed away? (No need for high precision here -- a ballpark figure will suffice.) 24.5.122.13 (talk) 07:41, 11 August 2014 (UTC)


 * That would very enormously depending of the flow rate and material in the stream bed. For a fast flow over light silt, the prints might vanish within a second or two whereas for a gentle stream over a clay bed the footprints might remain for months.    D b f i r s   09:04, 11 August 2014 (UTC)
 * How might footprints (e.g. from dinosaurs) last so long as to end up petrified? ←Baseball Bugs What's up, Doc? carrots→ 09:09, 11 August 2014 (UTC)
 * See ichnite.--Shantavira|feed me 10:38, 11 August 2014 (UTC)
 * I see. Hardened enough that being silted over did little or no damage to the print, and resulting in preserving it and eventually becoming rock. Thank you! ←Baseball Bugs What's up, Doc? carrots→ 10:43, 11 August 2014 (UTC)

If Cooper had any real knowledge of Nature's ways of doing things, he had a most delicate art in concealing the fact. For instance: one of his acute Indian experts, Chingachgook (pronounced Chicago, I think), has lost the trail of a person he is tracking through the forest. Apparently that trail is hopelessly lost. Neither you nor I could ever have guessed out the way to find it. It was very different with Chicago. Chicago was not stumped for long. He turned a running stream out of its course, and there, in the slush in its old bed, were that person's moccasin-tracks. The current did not wash them away, as it would have done in all other like cases—no, even the eternal laws of Nature have to vacate when Cooper wants to put up a delicate job of woodcraft on the reader.
 * I wonder if this question has anything to do with Mark Twain's essay on Fenimore Cooper's Literary Offenses:
 * Looie496 (talk) 14:37, 11 August 2014 (UTC)


 * Your hunch is right on -- I've read the essay, and then reread the passage to which he alludes, and that posed the question. Because in The Last Mohican, this little scene takes place on D+5 after the women are kidnapped, and I'd like some input on whether the footprints can last that long on the streambed.  FYI, the stream in question is described as a muddy spring and the scene takes place near its source -- so the flow rate is probably fairly low (which would favor the footprints remaining), but the soil is unusually soft (which could cut either way -- softer soil makes for deeper footprints, but also for a higher rate of erosion). 24.5.122.13 (talk) 01:18, 12 August 2014 (UTC)


 * There are some 20,000 year old human footprints at Lake Mungo. HiLo48 (talk) 02:12, 12 August 2014 (UTC)


 * I was asking about how long can footprints last under FLOWING water. 24.5.122.13 (talk) 02:19, 12 August 2014 (UTC)
 * In any case, Dbfirs has more-or-less answered the question. And since Cooper's description of the stream is closer to Dbfirs's second limiting set of conditions (gentle stream over alluvium) and the elapsed time is no more than 5 days, my conclusion would be that in this case, Cooper was right and Twain was wrong -- the footprints would not have been washed away YET.  (Twain was right, though, about Cooper's overly elaborate dialogue.) 24.5.122.13 (talk) 02:26, 12 August 2014 (UTC)

White Kidney Bean extract - is it cooked?
I'm talking about the famous Phase2(tm) extract... It seems powderish for in my check, and I try to understand if it's actually cooked beans than dried and grinned, or just grinned beans (I ask this because I've heard that eating non-cooked beans can be toxic, and therefore it's not very likely that Phase2(tm) extract is made from uncooked beans). thanks for you elaboration, Ben. Ben-Natan (talk) 11:15, 11 August 2014 (UTC)
 * I've never heard of phase2, but a quick search finds which says it's a fractionated water extract from dried beans. While that's from the manufacturer, they appear to be nominally trying to operate within the law so the claim is probably true (even if the page in general is weasel wording and exagerating as much as they can). In any case although it doesn't mean dried beans or fractionated, it being a water extract seems to be confirmed by this published source . Their "science dossier"  also mentions it being a fractionated water extract. Notably:
 * "The Phase 2® product is a water extract of the white kidney bean (Phaseolus vulgar is) standardized to alpha-amylase (8;12;15;39) inhibiting units (Pharmachem Laboratories, Kearny, NJ). Phase 2 is produced from non-GMO whole white kidney beans, which are ground and then extracted for 4 hours. The liquid is filtered and concentrated under vacuum. The extract is filtered again, and then pasteurized before being spray dried. Phase 2 is odorless and tasteless. Each lot of Phase 2 has at least 3000 alpha amylase inhibiting units (AAIU) per g when tested at a pH 6.8 using potato starch as the substrate and pancreatin as the enzyme source. The Phase 2 extraction process was designed to make it more potent and stable than the white bean product tested by the Mayo clinic."


 * Of course, you should use the usual caveats with a science dossier published by the manufacturer, in particular recognising that a lot of the research, while perhaps peer reviewed, was probably paid for by them (i.e. there's an obvious COI) and that they may have also excluded research which doesn't put their product in a good light. However I think we can mostly trust them on how it's manufactured.
 * Notably none of this mentions the beans being cooked.
 * If you look at the info in the previous sources and others like, it sounds like the product is supposed to work due to the presence of alphaamayze inhibitors. The type of inhibitor isn't mentioned, but the specific presence in the beans would lead one to believe, and this seems to be confirmed by sources like and further  although referring to inhibitors in different plants, that we're probably referring to a proteinaceous inhibitor. Considering that, and seemingly confirmed by the last source (although it does mention one study which found inhibitors heat stable up to 90-100 degrees C), cooking the beans would probably denature the inhibitors, so seems unlikely.
 * In terms of safety risk with the appropriate caveats (not medical advice etc), AFAIK the biggest problem with raw beans tends to be Phytohaemagglutinin as mentioned in our article (although some may have cyanogenic glycosides or other nasties removed by cooking). The source says that white kidney beans naturally have much lower levels and that the process they use significantly reduces the levels (it doesn't say how, perhaps it's the fractionation). It also lowers trypsin inhibition levels which may be important to help prevent protect deficiency. In any case, various sources claims the phase2 extract is Generally recognised as safe.
 * Nil Einne (talk) 13:38, 11 August 2014 (UTC)


 * Awww hell, I had that quote sitting in my copy-paste buffer and somebody beat me to it. :) If you search PubMed you'll find that there are several publications on Phaseolus vulgaris (Common Bean) extract used for this purpose, e.g.  .  Essentially, some enterprising people have isolated the toot out of the bean and found it to be good for the health. :)  In other words, slowing digestion of starches.  What I find interesting is that this is an effect I would have some years ago been ready to attribute to "complex carbohydrates"; but in fact it is a specific biochemical activity in the plant, presumably for the adaptive purpose of making those eating it less hungry. Wnt (talk) 13:55, 11 August 2014 (UTC)

Kidney activity
Does the kidney as a whole or in part, function at a constant rate or in peaks and troughs? If the rate varies, what are the variables that influence the rate? — Preceding unsigned comment added by 60.226.104.246 (talk) 12:56, 11 August 2014 (UTC)
 * This page seems to indicate that normally functioning kidneys work continuously; that is they don't turn on and off. -- Jayron  32  14:43, 11 August 2014 (UTC)


 * The output of the kidney is not constant, circadian rhythm certainly has some effect on the activity of kidneys, [see here] and [here] hence that irritating full bladder in the morning that seems designed to get you up and hunting working and it is a widely known fact that increased intake of fluids when the kidney owner is not dehydrated will lead to increased outflow of urine. Similarly a decrease in fluid intake will lead to decreased activity of the kidneys and the production of small amounts of concentrated urine. Richard Avery (talk) 14:51, 11 August 2014 (UTC)


 * We should probably distinguish between removal of water and waste. The rate at which they remove water is obviously highly variable.  The rate at which they remove waste isn't as variable, but I'm not sure how constant it is.  A very full bladder might also slow down the kidneys, if the back pressure on the ureters is too high for the kidneys to continue to drain into them.  StuRat (talk) 16:08, 11 August 2014 (UTC)
 * There shouldn't be back-pressure from ureters. They are very muscular pumping tubes. I am certain incontinence will occur before back-pressure can. 104.128.96.117 (talk) 18:55, 11 August 2014 (UTC)
 * It is possible, as cited in hydronephrosis. I knew someone who lost both kidneys from hydronephrosis caused by chronic bladder obstruction. He survived for 40 years with dialysis. Richard Avery (talk) 09:40, 12 August 2014 (UTC)


 * Our countercurrent multiplication article links to these helpful animations. The kidneys are always continuously operating. If they stop, they will have serious issues resuming. 104.128.96.117 (talk) 18:55, 11 August 2014 (UTC)