Wikipedia:Reference desk/Archives/Science/2013 January 28

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January 28

Why don't the the sunrise and sunset times go the other way at the solstice?

While we're on the subject of the Earth's orbit... I always assumed that after the 21st of December, or thereabouts, the sunset got later each day. However, when I look up the sunrise and sunset times for about this time for, say, London, although the days begin to get longer overall after the solstice, the sunsets don't necessarily get later or the sunrises earlier - one or the other will happen but not both together. There seems to be a couple of weeks discrepancy either side of the solstice before everything coincides and we get both a later sunset and an earlier sunrise on the same day. What causes the discrepancy? Does it depend on where you are on the surface of the Earth and if so, is there somewhere where everything changes on the day of the solstice and the following day the sunrises start to get earlier and the sunsets later? Richerman (talk) 00:22, 28 January 2013 (UTC)

It would work that way if the earth's orbit was both flat and circular. However, it isn't. The earth's orbit is oblique (offset by an angle to the plane of the solar system) and the orbit is an ellipse. As a result, there is are the deviations you note from the expected "symmetry" at the equinoxes. See Equation of time for these corrections. --Jayron32 00:39, 28 January 2013 (UTC)

Ah, right - so am I right in thinking that the solstices and equinoxes only seem less variable because they are measured in days rather than minutes? Richerman (talk) 00:53, 28 January 2013 (UTC)

I'm not quite sure what your getting at, but one cause of variation of the time and date of the solstices and equinoxes is that our calendar is not exactly one tropical year long, so the times of these phenomena vary quite a bit depending on how long it has been since a leap day. Jc3s5h (talk) 01:15, 28 January 2013 (UTC)

Analemma. Wnt (talk) 01:30, 28 January 2013 (UTC)

Interesting answer Jayron. I see the point of the elliptical motion, but I don't get the relevance of the inclination of the Earth's orbit relative to the solar system. If the other planets weren't there, there would be no plane of the solar system other than the Earth. Or am I missing something? IBE (talk) 07:33, 28 January 2013 (UTC)

What you've got is a complex interaction of several planes, none of which line up. There's the ecliptic, which is the plane that the sun occupies in its apparent motion in the sky if you hold the earth still. Then there's the Celestial equator, which is a projection of the earth's equator out to infinity. These planes are offset from each other by an angle; that angle is called the "obliquity" of the Earth's orbit. The fact that these planes don't match has to be taken into account when calculating the difference between the "mean solar day" (i.e. an exact 24 hour period measured on the clock) and the "apparent solar day", which is the time between the reappearance of the sun in the same position on successive turns of the earth around its axis. Over the course of an entire year, this averages out to the exact 24 hour day, but on any given day of the year, the length of the actual day (from the sun appearing in the same location on successive turns of the earth) varies depending on exactly where the earth is in its orbit. Both the ellipsoidal nature of the orbit, and the angle of the rotation relative to the ecliptic (the obliquity defined above) will shorten or lengthen the actual length of the day. These differences account for the fact that, for example, the day doesn't lengthen uniformly as one moves away from the solstice: the shortest day is not the same as both the latest sunrise and the earliest sunset, which is what the OP was asking about. In New York City this past December (see [1]), for example, the Winter Solstice occurred on December 21, however the earliest sunset occurred on about December 8 (4:28 PM) and the latest sunrise didn't occur until sometime during the first week of January (7:20 AM). There's thus a discrepancy caused by the Equation of time: The shortest daylight (solstice) of the year is neither the day with the earliest sunset, nor the day with the latest sunrise. It would be if the earth had a perfectly circular orbit AND had a perfectly perpendicular one WRT its axis. The fact that the earth's orbit is neither circular nor perpendicular is why there is a discrepancy. --Jayron32 07:51, 28 January 2013 (UTC)

I was with you until nearly the end. If the Earth's orbit were perfectly circular, and its axis perpendicular to the plane of that orbit, there wouldn't be a 'shortest day' - all days would be alike. AlexTiefling (talk) 10:19, 28 January 2013 (UTC)

Oh. Yeah. Duh. Well, skip that part. --Jayron32 14:04, 28 January 2013 (UTC)

Jayron got at least one thing definitely wrong: obliquity is customarily measured from the ecliptic (Earth's orbital plane), not from the celestial equator. One might reasonably argue that it ought to be measured from the invariable plane (closer to Jupiter's orbital plane), but the difference is less than 2°. —Tamfang (talk) 05:31, 13 October 2013 (UTC)

Also, it's important to note that the length of a day is sinusoidal, with very little change near the peak (summer solstice) and trough (winter solstice), and rapid change at the vernal and autumnal equinoxes. This allows minor effects from the non-circular orbit, etc., to have a noticeable impact around the solstices, while those effects are swamped out at the equinoxes. StuRat (talk) 04:40, 28 January 2013 (UTC)

We are accustomed to thinking that the length of a day is 24 hours. Our clocks accurately measure 24 hours each day but the length of a day, measured by observing the position of the sun above the horizon, is only 24 hours when averaged over a whole year. It actually varies on a daily basis – sometimes a little longer than 24 hours and sometimes a little shorter. Relative to a clock, there is a discrepancy on all but a couple of days a year. This discrepancy aggregates and causes a difference between clock time and solar time. It is this difference that causes the day of earliest sunrise to occur a couple of weeks before the summer solstice, and the day of latest sunset to occur a couple of weeks after the summer solstice. Similarly, the day of latest sunrise occurs a couple of weeks after the winter solstice; and the day of earliest sunset occurs a couple of weeks before the winter solstice.

The reason for the slight variation in the length of a day, measured by observing the position of the sun above the horizon, is because the Earth’s orbit is elliptical rather than circular. When the Earth is closest to the sun it is moving at its fastest; and it is moving at its slowest when it is farthest from the sun – Keppler's Laws. Also the distance to the sun influences the angle through which the Earth must rotate before the sun appears above the horizon in the same position as the previous day. Dolphin (t) 11:41, 28 January 2013 (UTC)

Note that when I said "the length of a day is sinusoidal", I meant the dawn-to-sunset period, not the (approximately) 24-hour period. StuRat (talk) 22:00, 28 January 2013 (UTC)

The asymmetry of dawn and dusk puzzled me for about 40 years (at least on the occasions I thought about it) because it is world-wide and no geographical features can explain it. It was only when I properly understood the equation of time (explained above) that I realised I was looking for an explanation of something not real, but created artificially by clocks. Sunrise and sunset are always symmetrical about local noon (except for local geographic effects), but local noon drifts each side of clock noon, causing an apparent asymmetry with earliest sunset seeming to occur in early December, and latest sunrise being not until early January by the clock. The reason (put simply) is that local noon is changing rapidly with respect to clock time around the winter solstice. This will not always be so -- see Milankovitch cycles. Dbfirs 12:17, 28 January 2013 (UTC)

Dbfirs's comments about "December" and "January" are true for the northern hemisphere, but not for the southern hemisphere. The facts can be summarised in a way that is equally valid for both hemispheres: The day of earliest sunrise occurs earlier than the summer solstice, and the day of latest sunrise occurs later than the winter solstice. Similarly, the day of earliest sunset occurs earlier than the winter solstice and the day of latest sunset occurs later than the summer solstice. Dolphin (t) 23:35, 28 January 2013 (UTC)

Sorry, Dolphin, for accidentally forgetting Australia etc. We do this too often in the north! Thanks for your improvement on my statement. Dbfirs 21:06, 29 January 2013 (UTC)

My pleasure! (We had 42 deg Celsius a week ago!) Dolphin (t) 03:56, 30 January 2013 (UTC)

We've just had a fortnight with the temperature constantly below zero, but it is milder now (daytime max.7C) with floods yesterday afternoon. Couldn't we exchange a little bit of weather? Dbfirs 08:17, 30 January 2013 (UTC)

Oooh. I like that answer even better than mine. --Jayron32 14:05, 28 January 2013 (UTC)

Here is my question on Y/A. I also need help

http://answers.yahoo.com/question/index;_ylt=As0ZpbMolRquFSK_zBvOfgu9DH1G;_ylv=3?qid=20130128225553AA09QS1 Eclectic Eccentric Khattak No.1

ninhydrin

ninhydrin is said to test for the prescence of amino group so it can be used in factories manufacturing textiles from milk does it have any effect on food substrate that it can not be used in the later future — Preceding unsigned comment added by 212.49.86.44 (talk) 05:47, 28 January 2013 (UTC)

I've never heard of that particular usage of ninhydrin. It's main use is to turn purple in the presence of free amines; there are several specific uses in the Wikipedia article titled ninhydrin. If you have a link to the usage you are talking about, could you provide it here so we can look at it and help you out? --Jayron32 06:05, 28 January 2013 (UTC)

T90 and leclerc tanks autoloader

How the ammunition is transferred to the autolloader after it becomes empty ( from outside or inside the tank ?) do you think it is practical to have the ammo seperated ? does not that expose the crew to the threat of being attacked during reloading the autoloader? how much time does it take to reload the autoloader ? — Preceding unsigned comment added by Tank Designer (talk • contribs) 12:57, 28 January 2013 (UTC)

From the look of things here, the remaining 21 rounds stored outside the autoloader would have to be reloaded from the outside ("special packing cases in the hull" doesn't sound much like a glovebox to me). As for whether this is practical, etc, all design considerations are tradeoffs. Certainly every tanker would love to carry a few hundred rounds of ammo, all immediately and internally accessible, without otherwise impairing the performance of the tank, but that can't be done. Russia has a long history of reasonable tank design, and I strongly suspect that their tactical doctrine maps to having at most 20 rounds available per engagement, at which point the tank retires from direct combat to re-arm. Web fora discussing the T-72 put in-field reloading by the commander and gunner from carried ammo at 10-15 minutes under such conditions. — Lomn 14:52, 28 January 2013 (UTC)

Also note that tanks with huge ammo stores defeat the purpose of the ammo. The purpose of the ammo is to be used, and if you have huge ammo loads on few platforms, most of the ammo wouldn't be used. Up (or down) to a certain point, another tank is more important than another few shots in a long firefight - and each round that explodes when the carrying tank is destroyed is a wasted round.

And the gun can't keep firing at full speed either. It'll heat up and degrade towards the end of a 20-round bombardment - and going beyond that point invites disaster (cook-off). - ¡Ouch! (^{hurt me} / _{more pain}) 11:33, 30 January 2013 (UTC)

Great Lakes region before last glacial period

Hi. I'm looking for a map, or description, or, well, just about any kind of information on the Midwestern US before the last glacial period. As I understand it from reading the Great Lakes article, the present lakes were created as the Laurentide ice sheet retreated at the end of the Wisconsin glaciation, and they only assumed their current shape a few thousand years ago. But why shouldn't the same have happened after the previous glacial period?

Many thanks JaneStillman (talk) 16:08, 28 January 2013 (UTC)

There probably were lakes there in the past, but the scouring effects of the last glaciation would have altered the lake boundaries and removed many of the markers of the previous shoreline. Hence it would be very challenging to say what the lakes looked like in the past. I'm not aware of any sources that speculate on specific boundaries during prior interglacial periods. Dragons flight (talk) 18:16, 28 January 2013 (UTC)

Hm, okay. Thanks, Dragons flight :) JaneStillman (talk) 09:40, 30 January 2013 (UTC)

Chicken nutrition revisited

A few days back I asked a question about protein content in cooked chicken. In that post, User:Sagittarian Milky Way pointed out the protein content in cooked chicken is also dependent on its water content. More water out, protein content increases. So I think it is better to analyze protein content of raw chicken. I searched Google and found different sources are making different claims.

The following data are for 100g raw chicken:

• NutritionData: Ground Chicken - 17 g
• myfitnesspal: Chicken breast without skin - 23 g
• myfitnesspal: Chicken breast with skin - 21 g
• livestong: Chicken breast - 23 g
• calorie count: Ground chicken - 19.5 g

My questions are:

1. What is the exact amount of protein in 100 g raw chicken muscle?
2. What is the nutritional value of chicken skin? Is it mostly fat?
3. Is the nutritional value of regular chicken muscle different from that of ground chicken? --PlanetEditor (talk) 16:16, 28 January 2013 (UTC)

I browsed around the Nutrition.gov website and easily found the Nutrition Database, in which you can look up factual answers your questions for various types of generic- and brand-name food products, including raw chicken, and different cuts of chicken meat. Nimur (talk) 16:48, 28 January 2013 (UTC)

• Chicken, roasting, meat only, raw. What does "roasting" mean here? --PlanetEditor (talk) 16:54, 28 January 2013 (UTC)

I think it refers to the expected use of the meat, as an indication of the grade or quality of product that the data relate to. AlexTiefling (talk) 17:00, 28 January 2013 (UTC)

Roasters and broilers are age ranges which are best cooked with those methods, I think. Sagittarian Milky Way (talk) 19:07, 28 January 2013 (UTC)

I think the OP is looking for a more precise answer than actually exists. The exact ratios of fat to protein in chicken will vary from muscle to muscle (thigh meat will have different values than breast meat), and also to some extent from bird to bird. The numbers you get are probably going to have some degree of variability, and you're simply not going to get a single number which is scrupulously correct for all parts of every chicken in existence. --Jayron32 18:39, 28 January 2013 (UTC)

To some extent, that's why the top-level nutrition recommendations from the USDA use a much more coarse unit of measure than the gram: the "unit of protein." More recently, the USDA is using the terminology "ounce-equivalent of protein food." But still, the idea is that you've only really got about one significant figure of reliable data. There's just too much variation between one meal and the next to measure protein content to several decimal places. Nimur (talk) 22:34, 28 January 2013 (UTC)

Also take into account that a lot of chicken meat has been subject of plumping, thereby significally increasing the amount of water in the meat. --Saddhiyama (talk) 10:18, 29 January 2013 (UTC)

Resonant frequency of an inductor

What parameters affect the frequency of a particular inductor? Is it solely the number of turns of wire? How does the cross section and composition of the wire, width of core, and spacing between turns affect yhe frequency, if at all? One more thing, I once saw a simple inductor that consisted of like 50 turns of wire then 25 turns back over the first layer. What is the purpose of that? A self-transformer or some such?! 75.228.139.34 (talk) 17:12, 28 January 2013 (UTC)

The first equation in our article Inductor#Inductance_formulae says that the inductance is proportional to the square of the number of turns, to the cross-sectional area of the coil and inversely proportional to the length of the coil. The cross section of the wire and the composition don't affect the inductance. The spacing between turns does matter because a wider spacing increases the length of the coil (for some given number of turns). SteveBaker (talk) 17:35, 28 January 2013 (UTC)

By itself, an ideal inductor has a reactance that's proportional to the applied frequency, so it doesn't have a resonant frequency. You need a more complicated circuit, like an LC circuit, for an inductor to form part of a circuit that has a resonant frequency. The resonant frequency in hertz of an LC circuit is

$f_{0}={1 \over {2\pi {\sqrt {LC}}}},$

into which you can plug one of the various inductance formulas for $L$. Red Act (talk) 19:34, 28 January 2013 (UTC)

Though an ideal inductor does not have resonant frequencies, a real coil has many. Unless you are dealing with radio frequency signals however, the lowest resonance is likely to be above your maximum frequency of interest and so can be ignored. --catslash (talk) 23:55, 28 January 2013 (UTC)

The self-resonant frequency of a real inductor due to parasitic capacitance isn't all that straight-forward to model or calculate. For example, for a single-layered air-cored inductor, if the inductor has a moderately large number (>20) of turns, the self-capacitance is fairly purely a function of the size and shape of the coil, and is unrelated to the number of turns, but for a very small number of turns, the self-capacitance increases with the number of turns. As another example, the skin effect within the coil's conductor becomes increasingly important at higher frequencies, and unlike with isolated conductors, the skin depth becomes more complicated when the turns in a winding are close to each other, due to the proximity effect. And the winding pattern of a real inductor is also an important consideration, with basket winding often used to lessen the parasitic capacitance. Real inductors are often modeled with a 3-element RLC circuit, but that simple model isn't very accurate at frequencies greater than about a fifth or a tenth of the inductor's self-resonant frequency. Real inductors can be modeled more accurately at higher frequencies with a four-element or five-element circuit.[2] Red Act (talk) 17:48, 29 January 2013 (UTC)

Sci fi

How much of sci-fis like star trek could actually become reality. Clover345 (talk) 17:40, 28 January 2013 (UTC)

This is much too broad a subject for the Reference Desk. There are entire books on subjects like The Science of Star Trek dedicated to exploring questions like this for any given series. However, it's fair to say that some things appear to be entirely impossible - faster-than-light spaceships, matter transmission, instant subspace/ansible communications - and others merely beyond our current capabilities - laser weapons, human-level AI. And some SF (including Star Trek) includes mention of fantasy elements like psychic powers, which do not even pretend to represent developments of real science. AlexTiefling (talk) 17:45, 28 January 2013 (UTC)

We do have an article: Physics and Star Trek, which includes a list of 'Further reading' suggestions. ~E:74.60.29.141 (talk) 19:19, 28 January 2013 (UTC)

Almost none of it. No alien species that can be played by humans in facial prostheses and bad make-up, no accidental resemblance of all alien languages to English dialect or period accents, no time travel, no FTL travel, no artificial gravity plating, no interbreeding with life from other planets, no transporters. We do have primitive "phasers" of various sorts, and we already have "communicators that would boggle Jean-Luc Picard. Hope I am wrong about warp speed, but if I were wrong the aliens would already be here. μηδείς (talk) 20:26, 28 January 2013 (UTC)

That's hardly fair. If you look at older sci-fi, and ask how much of that came true - and quite a bit has. The original series StarTrek communicators, for example, are completely dwarfed in performance by modern mobile phones...remember the "Dick Tracy" wrist-TV communicator...again, easy! Everyone in StarTrek uses piles of hand-held tablets that look just like an iPad (god knows why they needed so many of them - perhaps multitasking operating systems didn't exist!) Computer AI isn't there yet - but take a look at "K9" (Dr Who's robot dog) and it's just laughably primitive compared to modern robotics. Even R2D2 is a fairly awful robot compared to what we can currently manage. "Data" on StarTrek has fancier AI and amazing motors and power supplies - but the current generation of Japanese humanoid robots have a physical appearance that's much more natural.

I vividly recall the first gen StarTrek medical teams having that thing that could squirt drugs right through your skin without needles...that technology is also here today. Several companies now make "tricorders" that you can actually buy.

In Hitchhikers' guide to the Galaxy, there is this little electronic book that has the complete repository of all knowledge contained within it. Welcome to Wikipedia on your tablet computer (you have to cross out the Apple logo and write "DON'T PANIC!" in large friendly letters on the back yourself though).

Much of SciFi's gadget predictions are things that we utterly wouldn't want - we could almost certainly clone humans right now - but we've decided that it's "A Bad Thing", so we don't. We can put jellyfish DNA into a poodle so it glows in the dark...we could certainly do similar tricks to make genetically distinct humans - but it's another "Bad Idea", so we don't.

The more recent the SciFi is, the tougher it is for us to meet what they show - but that's mostly because authors of SciFi have to continually push the envelope to make the future seem different from today. But if you go back a generation or two, look at 40 to 50 year old SciFi, it's quite impressive how many of those things we now have working. Obviously there will always be totally impractical things (Warp drive, transporters, etc) - but the vast number of small gadgets they have can easily be improved upon these days. SteveBaker (talk) 21:02, 28 January 2013 (UTC)

That's hardly fair, Steve, you obviously did not click on the link I provided before you complained of the unfairness of it all. μηδείς (talk) 22:56, 28 January 2013 (UTC)

I don't agree that "The original series StarTrek communicators, for example, are completely dwarfed in performance by modern mobile phones". Our cell phones require installing a vast network of cell towers around the planet, while the ones in ST work more like satellite phones. Being able communicate with each other and ships in orbit, seemingly without the need for a recharge, and without a visible antenna or massive battery pack, is impressive. StuRat (talk) 21:47, 28 January 2013 (UTC)

Without visible antenna? That copper mesh that flips open is the antenna. APL (talk) 08:04, 29 January 2013 (UTC)

Steve, I'll tell you why the TNG people have so many tablets! So you can get a big-picture understanding of your work by physically spreading documents over your whole desk. If I could replicate as many free tablets as I wanted, I'd have at least half a dozen on my desk alone! APL (talk) 08:04, 29 January 2013 (UTC)

I'd have one on me at all times, and a decent computer too. One with a real keyboard. Without touch feedback (e.g. on-screen keyboard), I'm as slow compared to a real keyboard as a human is compared to Data. The PADD would be just right for the things where a full-sized computer feels like "too much" (e.g. calculator app, browsing thru mails, etc). The most remarkable feat of ST communicators is that Fed manages to keep all the spam and the cold calls away.

*bleep* "Mr Picard, it has been ten months since you departed from Risa. Would you like to spend your next holidays with us in <insert stardate>, please order now for a 20% discount..."

"Listen up cretin, this is not the time, we're about to strike a Borg mothercube, to save your stupid little derriere from assimilation."

"OK sir, I'll call again in five minutes then..." *bloop*

• bleep* (Riker's comm this time) Riker doesn't answer the call.
• bleep* ... *bleep* Riker to Picard: "Risa's calling me too Sir..."

Troi: "Hey, we've been to Risa, too. We could use that discount, don't you think so???"

Data: "Too soon. It's been nine, not ten months for the two of you. No discount for you, but an upgrade to the Riker family." :P - ¡Ouch! (^{hurt me} / _{more pain}) 11:56, 30 January 2013 (UTC)

Jet injectors existed already when Star Trek debuted, so that wasn't a prediction. Capacitive touch screens also predate the show, and CCDs and TN LCD panels came just a few years later. It took decades for them to become cheap and reliable enough to show up in consumer devices, but it's not as though no one had thought of the idea before that. We obviously have nothing resembling a tricorder, though there may be novelty devices sold under that name. A mere visual similarity of current devices and classic TV show props is not all that interesting when you consider that the designers probably saw those TV shows.

I'm amused that you think present-day androids look more human than Brent Spiner. Obviously he was given makeup and contacts for dramatic purposes, and not because the writers believed that technology would get that close to perfectly simulating a human and yet be unable to get the skin or eye color right. Likewise, K9 was primitive because of budget limitations and not because the writers were making some sort of prediction that we've now surpassed.

The HHGTTG was a conventional encyclopedia, as far as I can remember, aside from the rather lax management and being served up over the sub-etha (which can't actually be done at a galactic scale). Douglas Adams also described humanity as a species so primitive that it still thought digital watches were a pretty neat idea. We've since decided they're not so neat, so you could count that as a successful prediction. We currently think 3D movies and cloud computing are neat, but neither one for the first time, and I'm sure those pendulums will swing back at some point. I hope the current fad of keyboardless computers will pass too. Sue Gardner‎ mentioned at a talk I attended that they have noticeably decreased the number of casual Wikipedia editors since they make it hard to do anything but passively browse.

The International Space Station (mentioned by APL below) is mostly a sad reminder of what we haven't achieved in that area. It's not a bustling hub for commercial flights to the moon and Mars. Every trip to it is enormously expensive, and the US no longer even has the capability to get there since it scrapped the shuttle program with nothing to replace it. The station struggles to find a scientific purpose to justify its existence, and to a large extent has relied on publicity stunts and experiments that are more hype than substance.

Basically, I agree with Medeis, and I'm frequently surprised at the faith in science fiction that I see in computer nerds. -- BenRG (talk) 22:43, 29 January 2013 (UTC)

I think you're nitpicking details.

If the question is will reality ever be exactly like Scifi, then the answer is obviously "no". APL (talk) 23:27, 29 January 2013 (UTC)

<- There's a tractor beam that could pull very tiny spaceships.[3] Sean.hoyland - talk 07:24, 29 January 2013 (UTC)

• There is a 1956 Asimov story called The Dying Night that revolved around the idea that in the future all scientists would carry portable pen-sized document scanners that used photographic film. Nowadays, digital pen-sized document scanners are available, but most people use the cameras on their phone as document scanners. Not just scientists, either. So there technology has surpassed SciFi.
• The 1909 short story The Machine Stops, by E.M. Forrester, revolved around the idea that in the future there would be "The Machine" that allowed us to transmit ideas and information instantly across the globe. It follows this to its logical conclusion and describes people called "lecturers" who are basically bloggers.
• Previous to 1969 there were a whole lot of stories, novels, and movies about sending men to the Moon. NASA managed to pull that off a few times.
• Space Stations once only existed in SciFi, now they shoot Sesame Street segments up there.

I'm sure we could all come up with many examples of SciFi technology that became real. APL (talk) 08:25, 29 January 2013 (UTC)

ON A more serious note, it looks like some devices (pads, clam-shell phones) are only so popular because their imaginary counterparts were in a popular -fi show. Do we have articles on that (Psychological effects of science fiction? List of electronic devices resembling science fiction props?) I found Cultural influence of Star Trek so far. And Sexuality in Star Trek, FWIW. - ¡Ouch! (^{hurt me} / _{more pain}) 11:56, 30 January 2013 (UTC)

I like touchscreens. So you need to look at the screen to type, their coolness is worth it. And haptic touchscreens are being developed. What's so bad about clamshell phones though? They're the kind that's hardest to open inadvertently/activate in your pocket and call 8271981743**24778734#. Half of all 911 (emergency) cell calls are made by butts. Sagittarian Milky Way (talk) 05:01, 31 January 2013 (UTC)

diabtes

my mother had diabetes, and when it was hereditary in her family, her parents also. I am one of 5 children. what are the chances that I will also inherit diabetes? --109.232.72.49 (talk) 21:13, 28 January 2013 (UTC)

This page answers your question in detail. It's pretty complex it seems, and it depends on the type of diabetes. Furthermore, external factors play a role in addition to your genes. - Lindert (talk) 21:25, 28 January 2013 (UTC)

Lindert is right that it depends on what type of diabetes and some characteristics of you. But the page link is simplified and only covers the two most common types of diabetes. Other types are more strongly inherited. If you can give us some more details of your mother's diabetes we might be able to do better. alteripse (talk) 22:15, 28 January 2013 (UTC)

There are signs of and very helpful treatments for pre-diabetes. See your physician as soon as possible. μηδείς (talk) 22:54, 28 January 2013 (UTC)

Please note that diagnosing someone's genetic susceptibility to diabetes is a sort of medical advice that the Refdesk can't give. Though obviously knowing your age and the type of diabetes your relatives had is a great first step in understanding, trying to collect more data about your case with the notion of giving you an individualized answer ... is still going to be laughable compared to any actual medical visit. However, I believe more than most here that we should give people helpful information in these cases, and so I approve of Lindert's response provided that you understand this is recommended reading, not a personal answer for you. It may also be helpful to read about prediabetes. You may also want to learn more about a blood glucose meter, a useful over-the-counter tool - in the end, biology accepts no substitute for hard data. Wnt (talk) 04:52, 29 January 2013 (UTC)

Medeis is half right. There are useful treatments. However, there are no signs and symptoms of prediabetes, just statistical risk factors. And giving a probability is less medical advice than "see your doctor"-- which IS medical advice. alteripse (talk) 12:15, 30 January 2013 (UTC)

Our article says there are no signs or symptoms, then, oddly enough, lists them. I suspect what they meant to say is that there are no distinct signs or symptoms, because they are the same as for type 2 diabetes, but to a lesser degree. This should really be clarified in the article. I will add the word "distinct". StuRat (talk) 18:57, 30 January 2013 (UTC)

More clearly, a prediabetic may not be aware of any symptoms, but there are diagnostic methods of detecting it. μηδείς (talk) 18:38, 30 January 2013 (UTC)

One symptom they didn't list, which I associate with pre-diabetes, is the glucose spike/glucose crash cycle. That is, while normal individuals can eat sweets and be OK, a pre-diabetic may have a dramatic sugar spike (and become hyper), followed by a sugar crash (where they become lethargic). Is this not a recognized symptom ? StuRat (talk) 19:07, 30 January 2013 (UTC)

No. There is no evidence that people who describe symptoms that they imagine are due to sugar "spike and crash" have a specifically higher diabetes risk than that of their demographics: typically american culture, more than high school education, less than endocrine fellowship education." Most of them have no demonstrable abnormality of glucose metabolism. Overall lifetime diabetes risk for that category of americans is higher however than the lifetime diabetes risk for uneducated Tuaregs. However, again we can play the "change the characteristics and change the odds game." Let's say your putative patient with sugar "spike and crash" symptoms actually meets both postprandial hyperglycemia and Whipple criteria-- has checked glucose after meals and confirmed it is high, and has checked glucose while shaky and confirmed it is low. Actually meeting both criteria at the same time would make him quite unusual but interesting. He might have glycogen synthase deficiency a very rare defect of glycogen metabolism, which does not carry a higher diabetes risk, or if black and female, might be an adolescent with type A insulin resistance, in which case her future diabetes risk is quite high. It all depends on details. alteripse (talk) 19:27, 30 January 2013 (UTC)

I agree entirely with the policy that we cannot diagnose and treat medical problems here. We can however answer general medical questions about general situations. For example: What is the chance that the son of a woman diagnosed with diabetes will get diabetes? For the general population, assuming the broadest possible defintion of "mother diagnosed with diabetes", the most probable answer is something in the ballpark of "about 20% of offspring of a woman diagnosed with diabetes will be diagnosed with diabetes during their lifetimes". However, as noted above, with more information about the type of diabetes and the age of the offspring, it might be possible to give a much more specific statistical probability without actually giving medical advice. For example, "If an American woman of european ancestry, normal body build, and no known relatives with type 2 diabetes was diagnosed in childhood with ordinary type 1 diabetes with positive antibodies and an insulin requirement from diagnosis, her offspring have a 3% likelihood of being diagnosed with type 1 diabetes in their lifetimes, an about 2.5% chance of being diagnosed with type 1 before age 20, and a 5% chance of being diagnosed with type 2 diabetes after age 40". But if any single characteristic in that description were changed, the probability would change as well. For example, "If an american woman of hispanic ancestry, overweight, hypertensive and hypercholesterolemic, and 3 relatives with type 2 diabetes, was diagnosed at age 40 with type 2 diabetes, her male offspring have about a 5% chance of being diagnosed with type 2 diabetes before age 20, a 20% chance by age 40, and a 60% lifetime chance; this is 10% higher if offspring is female, 50% higher if offspring is obese, and 70% if hypertensive and hypercholesteroleic". If parent has characteristics of monogenic diabetes, the odds may be 50%. So the probability is all over the place, ranging from as low as 1% in non-american populations with low obesity rates to >90% in americans of certain high risk ethnicity and other risk factors. Given that the original question does not seem to have been posed by a literate native english speaker, this may be the type of answer way beyond comprehension and usefulness. But it would still be a permissible statistical fact, and not a matter of "giving medical advice." alteripse (talk) 19:13, 30 January 2013 (UTC)

Perhaps I should have been a bit more blunt above. The poster can try to estimate his risks of diabetes in this way, but practically anyone has a serious chance of coming down with type II diabetes anyway. If someone has diabetic relatives, any genetic disadvantages could potentially be offset by the advantage that if he sees them, he can ask to borrow their meter and a test strip and a lancet, after not eating anything that morning, and ask them to show him how to get a fasting blood glucose reading. Checking this number once a year or more, watching for when it starts going above 100 into prediabetes, should reduce the odds of being caught by surprise, which means that the person can begin taking dietary precautions and drugs hopefully before serious kidney or eye damage gets started, and especially the damage to the pancreas itself from the high blood sugar that contributes to progression of the disease. Many diabetics are not diagnosed until white spots start turning up on their shoes from the sugar leaking out of their heavily damaged kidneys, which is way way way later than is good for them. Wnt (talk) 06:43, 31 January 2013 (UTC)

The poster's actual risk of becoming diabetic can be as low as 1% or as high as 99% depending on his/her age, sex, adiposity, ethnicity, place of residence, number of relatives with diabetes, time frame specified, and most importantly the characteristics of his/her mother's diabetes. You are verging on giving medical advice in suggesting he/she start testing him/herself-- would you think that warranted if his risk over the next 50 years is 5%? And the story about white spots on shoes is largely a medical urban legend. I have heard some fancier versions involving ants around trees or rotten leather. In the rare cases in which spots of sugar left from evaporated urine might be noticed, sugar in urine is simply a sign that blood sugar has been exceeding the renal threshold for reabsorption, not that the kidneys have been damaged. If we loaded you with sugar and drugs that inhibit insulin, we could probably get your sugar up to 300 and your urine full of sugar in about 24 hours without actually damaging your kidneys. alteripse (talk) 04:47, 1 February 2013 (UTC)

Leg cramps

• This question has been removed as it may be a request for medical advice. Wikipedia does not give medical advice because there is no guarantee that our advice would be accurate or relate to you and your symptoms. We simply cannot be an alternative to visiting the appropriate health professional, so we implore you to try them instead. If this is not a request for medical advice, please explain what you meant to ask, either here or at the talk page discussion (if a link was provided).

Do see your physician, there are various successfully treatable conditions that require medical diagnosis and assistance. μηδείς (talk) 22:52, 28 January 2013 (UTC)

The rank of gram positive bacteria

What is the taxonomic rank of Gram Positive Bacteria because I just can't seem to find the answer. — Preceding unsigned comment added by Lightylight (talk • contribs) 23:07, 28 January 2013 (UTC)

According to bacteria, gram positive bacteria are a phylum. --Jayron32 23:22, 28 January 2013 (UTC)

Gram positive bacteria were previously identified with one or more phyla (e.g. Firmicutes), but we now believe that such bacteria are not strictly a monophyletic group, and as such the most widely used system of bacterial classification does not use gram staining to define taxonomic nomenclature. The article on gram positive bacteria gives more information. Dragons flight (talk) 23:25, 28 January 2013 (UTC)