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September 5

CTE

Have any studies been done on people other than sports participants or veterans to determine if they have had head trauma that it is CTE? — Preceding unsigned comment added by S0berpete (talk • contribs) 00:02, 5 September 2013 (UTC)[reply]

Chronic_traumatic_encephalopathy#Epidemiology also describes that people with a history of chronic seizures and domestic abuse victims are at a heightened risk of developing CTE. The reason that CTE research is so focused on combat veterans and athletes is that they are far far more likely to develop CTE - the first patient diagnosed was a boxer, for instance. This is a case study of five patients with CTE (back when it was called dementia pugilistica, or Boxer's Dementia). The patients included three athletes, a mentally disabled man with a history of banging his head against things, and an epilepsy patient with a history of smacking his head while falling during a seizure. Someguy1221 (talk) 00:53, 5 September 2013 (UTC)[reply]

Telescopes on the Moon

The Chang'e-3 is scheduled to launch in late 2013 and allegedly will carry a telescope for astral observations from the Moon. Will the Chinese be the first to attempt this or has another nation already done it? How does observation quality from the surface of the Moon compare to orbital platforms? Are there downsides? I couldn't find an article regarding telescopes on the Moon... DrewHeath (talk) 02:01, 5 September 2013 (UTC)[reply]

The Times of India thinks the first telescope on the Moon will be a private venture in 2016.[1] The MIT Technology Review has an article about using lunar dust to build a mirror.[2] There's also a proposal for a liquid mirror telescope.[3] Clarityfiend (talk) 02:48, 5 September 2013 (UTC)[reply]

Gastrobiology of obesity

Last month i believe there came a paper which suggests that Gut Flora play a role in the development of Obesity. Could you guys please elaborate In the simple and summerized way possible, why would Such a connection exists, and it's core principles in short?

Many many thanks for you kind help and illumination. 95.35.51.159 (talk) 02:28, 5 September 2013 (UTC)[reply]

This is a concept some have called Infectobesity. In summary, the idea is such: The bacteria in your gut play a huge role in the digestion and absorption of food that you have eaten. The obese have different gut flora than the thin. In particular, the gut flora often found in the obese allows their bodies to absorb a greater proportion of the energy from their meals than thin bodies are able to. The gut-flora differences do not apply to everyone: There are likely thin people with obesity-associated flora, and obese people with thinness-associated flora. It is unknown how broad this finding applies (i.e. does it vary with age, race geographic location, medical conditions, etc.). It is unknown whether having these gut flora makes you fat, or being fat causes your body to retain such flora. A paper came out earlier this year showing that you could cause mice to lose weight by altering their gut flora: [4]. Someguy1221 (talk) 03:06, 5 September 2013 (UTC)[reply]

Difference between char and charcoal?

Is there a difference between char and charcoal? The articles aren't clear, but they seem to define them in the same way. The biochar article seems to regard biochar as a specific type or application of charcoal.

So... they seem the same (so a merge might be needed) but I haven't found a definite answer from a reliable source.

(I see I'm not the first to ask.) --Chriswaterguy talk 02:44, 5 September 2013 (UTC)[reply]

One source about biochar and charcoal:

Christoph Steiner, a research scientist at the University of Georgia, says the difference between charcoal and biochar lies primarily in the end use. “Charcoal is a fuel, and biochar has a nonfuel use that makes carbon sequestration feasible,” he explains. “Otherwise there is no difference between charcoal carbon and biochar carbon.”

--Chriswaterguy talk 02:57, 5 September 2013 (UTC)[reply]

Wouldn't char contain a higher proportion of impurities such as phosphate and other minerals? Plasmic Physics (talk) 02:59, 6 September 2013 (UTC)[reply]

Why do you say that? --Chriswaterguy talk 16:13, 7 September 2013 (UTC)[reply]

Why when the plane fly above the earth, are not affected by the movement of the Earth's rotation on its axis in other words, why not lengthen or shorten the distance between one country and another when it fly?

Why when the plane fly above the earth, are not affected by the movement of the Earth's rotation on its axis in other words, why not lengthen or shorten the distance between one country and another when it fly? why it's not affected it? — Preceding unsigned comment added by 37.238.50.113 (talk) 07:37, 5 September 2013 (UTC)[reply]

Because it's flying in air, and the air moves with the Earth. — kwami (talk) 08:31, 5 September 2013 (UTC)[reply]

In a sense, we do. Airflow ("wind" ;-) over the Earth is affected by Coriolis force, and modern air routes are very much designed to take prevailing wind patterns into account. Indeed, if you check North Atlantic Tracks, you will see that the optimal route configuration is determined every day, based on current meteorological information. --Stephan Schulz (talk) 09:44, 5 September 2013 (UTC)[reply]

But the direct answer to the question is that the plane is affected. However, what is affected is the steering, not how far it must travel. As Kwami said, the atmosphere moves with the Earth, and the distance the plane must fly is relative to the atmosphere. But as for steering, the airplane feels a force perpendicular to the Earth's axis — that is, partly horizontal and partly vertical. The horizontal component is called the Coriolis effect or Coriolis force, and the vertical component is called the Eötvös effect. But the Earth rotates very slowly — it takes a whole day to rotate a single turn — and the result is that the Coriolis and Eötvös effects are very small. A plane must be constantly steered in flight to overcome the effects of any crosswinds and up and down drafts; the Coriolis and Eötvös effects can easily be overcome the same way. And since they are not only small but almost constant during the flight, the pilot would not even notice them. --50.100.188.72 (talk) 10:11, 5 September 2013 (UTC)[reply]

Earth's rotation is however a significant factor in space launches. Escape velocity says: "as the Earth's rotational velocity is 465 m/s at the equator, a rocket launched tangentially from the Earth's equator to the east requires an initial velocity of about 10.735 km/s relative to Earth to escape whereas a rocket launched tangentially from the Earth's equator to the west requires an initial velocity of about 11.665 km/s relative to Earth". This has strongly influenced the chosen sites (to the south on the Northern Hemisphere) and direction (east) for most space launches. PrimeHunter (talk) 10:36, 5 September 2013 (UTC)[reply]

Yes, even if planes could fly above the rotating atmosphere, they would still take of with a speed (relative to an inertial frame fixed at the centre of the earth but not rotating with the earth) of the take-off ground-speed plus the instantaneous tangential speed of the airstrip. In the absence of air, and some (currently impossible) mechanism to counteract just gravity, the plane would continue at constant speed on a tangent to the curvature of the Earth. If you jump in the air, you tend to land again on the same spot, because the Earth has rotated under you , but you have (almost exactly) retained the tangential velocity of the spot you jumped from. In practice, it is usually simpler (for jumping, balloons, planes etc, but not for space launches) to ignore the rotation of the Earth and just to take into account winds and Coriolis forces. Dbfirs 13:03, 5 September 2013 (UTC)[reply]

Three leaves in a dicot plant. Is this a mutation?

Comparison of a monocot and dicot sprouting. Note that the visible part of the monocot plant (left) is actually the first true leaf produced from the meristem; the cotyledon itself remains within the seed. (Image is from our cotyledon article.)

I observed a plant of leguminase family that has three first leavs. I could see the two cotyldons, but the first leavs appared are in numbr three. I planted five seeds. All other four seeds produced two leaves each but this one seems very odd with 3 leaves. --G.Kiruthikan (talk) 10:53, 5 September 2013 (UTC)[reply]

Do you have a photo? Sfan00 IMG (talk) 13:45, 5 September 2013 (UTC)[reply]

It seems like a developmental anomaly, but probably not a mutation, although it could be. Identical twins in humans are also a developmental anomaly but not a result of a mutation. Looie496 (talk) 14:14, 5 September 2013 (UTC)[reply]

Do you mean conjoined twins ? StuRat (talk) 01:09, 6 September 2013 (UTC)[reply]

Without a photo there is no way to opine on this topic. We don't know what is meant by the leaves come in threes. Cannabis has leaves with an odd number of leaves--that doesn't disqualify it as a dicot. We need an image. μηδείς (talk) 01:31, 6 September 2013 (UTC)[reply]

The question makes perfect sense, but you have to know some basic plant biology to understand it. The great majority of flowering plants are either monocots or dicots. The defining feature of the two groups is that in monocots, when the seed sprouts, the stalk that comes up gives rise to a single tiny leaf; in dicots it splits into two tiny leaves. This is the defining feature, but there are many others that go along with it -- basically monocots are grasses and grasslike things, dicots are almost all the remaining flowering plants. The OP is saying that he saw a plant in the dicot group where the sprout produced three tiny leaves instead of the usual two. Looie496 (talk) 01:52, 6 September 2013 (UTC)[reply]

No tricots? Hmm Sfan00 IMG (talk) 18:05, 6 September 2013 (UTC)[reply]

The OP's "I could see the two cotyldons, but the first leavs appared are in numbr three" seems to imply that he is talking about the first proper leaves, not the dicotyledons, Looie. μηδείς (talk) 00:51, 7 September 2013 (UTC)[reply]

This is the phot takaen by phone and retaken by webcam

— Preceding unsigned comment added by G.Kiruthikan (talk • contribs) 12:54, 8 September 2013 (UTC)[reply]

See this photo and decide whether it is a mutation or any other thing please. — Preceding unsigned comment added by G.Kiruthikan (talk • contribs) 13:09, 8 September 2013 (UTC)[reply]

Eating shellfish during a red tide

Dinoflagellates of the genus Gonyaulax produce a toxin called "saxitoxin", which is concentrated in clams, mussels, and other shellfish that feed on these marine protozoa. During a red tide, they bloom, and eating shellfish during these times can be fatal due to unusually high concentration of the toxin. Now, is the fact that eating shellfish during a red tide is deadly ever related to the fact that Jews can't eat shellfish? Is there an anthropological basis for this dietary restriction? 164.107.102.52 (talk) 15:25, 5 September 2013 (UTC)[reply]

It's hard to know what's behind a two-thousand-year-old arbitrary religious rule - however, I'd guess that living in a hot climate, far from the ocean, in an era before refrigeration, would make not eating shellfish be an excellent rule...religious or not! SteveBaker (talk) 16:08, 5 September 2013 (UTC)[reply]

SteveBaker, you do realize that the restriction is written out in Deuteronomy, right? According to this source, some people think that Deuteronomy is written in approximately 600 BC. Under this dating, that would place it six hundred years more or less before Christ. From today, that's 2600 years. 164.107.102.52 (talk) 16:22, 5 September 2013 (UTC)[reply]

The way I always heard it, bottom feeders are considered "unclean", which is why not just shellfish, but also hogs and catfish are on the list. ←Baseball Bugs ^{What's up, Doc?} carrots→ 16:49, 5 September 2013 (UTC)[reply]

There's a rough hypothesis to be made that the ancient Israelites, living as a community in Egypt (which many historians will claim never happened) were in some way able to understand that a dangerous red tide was underway and created the first Passover as a way of ensuring everyone ate something other than shellfish. It's purely speculation. There might be something in this to that effect but only Google's secret index knows (I could drag out my crummy command line pdf2djvu and eventually get searchability but I can't be bothered right now) Wnt (talk) 18:12, 5 September 2013 (UTC)[reply]

Far as I know, Egyptian hieroglyphs make it reasonably clear that the Hebrews were there, except their spin on it was that they drove the Hebrews out. ←Baseball Bugs ^{What's up, Doc?} carrots→ 21:45, 5 September 2013 (UTC)[reply]

I took this one on in Wikipedia:Reference_desk/Archives/Humanities/2013_June_23#Where_did_Jews_come_from_before_the_Exodus.3F, left less than satisfied. Wnt (talk) 08:02, 6 September 2013 (UTC)[reply]

Makeshift electromagnet advice

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.

Sorry guys, but this is way over the line of what constitutes medical advice—whether the original poster insists that he won't hold us liable or not, encouraging him to build powerful magnets for use as a medical device will end badly for all involved. TenOfAllTrades(talk) 13:09, 6 September 2013 (UTC)[reply]

Deleted means deleted Tevildo (talk) 22:31, 6 September 2013 (UTC)[reply]
The following discussion has been closed. Please do not modify it.
Bullshit. My friend removed a splinter with a magnet from inside a hard drive. You jobsworths make me sick. --129.215.47.59 (talk) 14:45, 6 September 2013 (UTC)[reply]

What is the meaning of A1C?

I don't ask about the hemoglobin A1C (because I read about in our article on Wiki) but only about the meaning of the sign "A1C".what's the meaning? probably it's initials of something95.35.210.39 (talk) 19:30, 5 September 2013 (UTC)[reply]

According to our disambiguation page A1C, this probably refers to Glycated hemoglobin...but that page doesn't say what it means either. SteveBaker (talk) 19:55, 5 September 2013 (UTC)[reply]

If you look down the page, at some point it's written HbA_1c. So I suspect the answer is that it's a form of hemoglobin A, probably further subdivided into subtype 1 and sub-sub-type c. --Trovatore (talk) 19:59, 5 September 2013 (UTC)[reply]

There is an article on: Hemoglobin, alpha 1 (Hemoglobin A1). so, now we looking for the meaning of letter C. 95.35.210.39 (talk) 20:54, 5 September 2013 (UTC)[reply]

Why do you think there's a "meaning"? Is there any reason to think it's not just the next one classified after HbA_1a and HbA_1b? --Trovatore (talk) 20:56, 5 September 2013 (UTC)[reply]

I have not knew about HbA_1a and HbA_1b. It's not written on our article of hemoglobin, but the other are written there. I thought maybe it's a shortening of a any word. 95.35.210.39 (talk) 21:09, 5 September 2013 (UTC)[reply]

I don't know of them either; whether there's any such thing as HbA_1a or HbA_1b I couldn't tell you. It could be short for a word (HbF seems to be fetal hemoglobin; I don't know whether the F stands for "fetal" or whether it's just a coincidence). I just don't see any immediate reason to think it's likely that it stands for anything. But who knows; maybe someone will pop up and tell us. --Trovatore (talk) 21:13, 5 September 2013 (UTC)[reply]

It's possible that it once had an actual meaning - but has since become "what it's called". There are lots of things like that out there. Everyone knows what a "laser" is - nearly everyone has forgotten that it was once written "L.A.S.E.R: and stood for " Light Amplification by Stimulated Emission of Radiation" - even though that's no longer how all lasers work. In the end, it may not matter what A1C stands for - so long as everyone in the business of dealing with it agrees on what it is. SteveBaker (talk) 21:56, 5 September 2013 (UTC)[reply]

Wait, what? There are lasers that don't work by stimulated emission? Which ones, and how do they work then? --Trovatore (talk) 23:20, 5 September 2013 (UTC)[reply]

This is trackable, but if you want the answer it may take some work. For some idiotic reason I cannot begin to comprehend, even now NCBI's journal abstract indexes go back little further than they did 20 years ago. As far as I'm concerned they ought to be back to Hippocrates by now. The reference given in the article is one of the very earliest you get when you search hemoglobin a1c there and sort by date. You can follow authors on the study further - for example, to one amazingly quixotic but truly valiant attempt in 1950 to determine the point mutation in sickle cell hemoglobin, before the idea was understood, which alas came up with four amino acids possibly altered, but actually found less valine in what we now know is a E->V point mutation [5] hmmm but I digress. Anyway, it appears sometime between 1950 and 1964 the term was invented. If you want to find it for sure, I'd guess you should hoof down to the library and either (a) pull out those big nasty tomes of Biological Abstracts or (b) read some of the publications of WA Schroeder that NCBI indexes (but without abstracts) from the early 1960s. One of these available online [6] says HbA was named because it was "alkali labile". Some others such as [7] [8] might review it. Oh, anyway, my guess is that it is a variant seen with electrophoresis or perhaps column chromatography. Wnt (talk) 22:41, 5 September 2013 (UTC)[reply]

As Wnt correctly guessed, the terminology derives from ion-exchange chromatography. Kunkel and Wellenius, studying normal adult hemoglobin (hemoglobin A) in 1955, noted that there were "minor components" present that varied from the parent hemoglobin. Further study (Allen et al.) distinguished between five subfractions (hemoglobin A1a, hemoglobin A1b, hemoglobin A1c, hemoglobin A1d, and hemoglobin A1e), named in order of elution (all of these preceded hemoglobin A0, the main form of hemoglobin). They therefore called A1a, A1b, A1c, A1d, and A1e the "fast hemoglobins". Rahbar et al. demonstrated in 1969 that hemoglobin A1c was elevated in the RBCs of diabetics. In 1971, Trivelli et al. suggested that there was a relationship between hemoglobin A1c levels and long term complications in diabetics. More recently, the Committee on Nomenclature, Properties, and Units of the IFCC proposed a new term for HbA1c, namely Haemoglobin beta chain(Blood-N-(1-deoxyfructos-1-yl)haemoglobin beta chain; substance fraction), but as this is impractical in clinical use, "permits" the continuing use of the trivial name "HbA_1c".

(Kunkel HG, Wallenius G. New hemoglobins in normal adult blood. Science. 1955;122(3163):288)

(Allen DW, Schroeder WA, Balog J. Observations on the chromatographic heterogeneity of normal adult and fetal hemogloba study of the effects of crystallization and chromatography in the heterogeneity and isoleucine content. J Am Chem Soc. 1958;80(7):1628–1634.)

(Rahbar S, Blumenfeld O, Ranney HM. Studies of an unusual hemoglobin in patients with diabetes mellitus. Biochem Biophys Res Commun. 1969;36(5):838–843.)

(Trivelli LA, Ranney HM, Lai HT. Hemoglobin components in patients with diabetes mellitus. N Eng J Med. 1971;284(7):353–357.) - Nunh-huh 09:36, 6 September 2013 (UTC)[reply]

what is the meaning of "beta" on hormones

I saw some hormones with prefix "beta". now I remember only one "beta hcg", but I know that there are more. anyway, what is the meaning of this word ("beta") when it comes as prefix before an hormone name? 95.35.210.39 (talk) 19:36, 5 September 2013 (UTC)[reply]

See Protein subunit. Tevildo (talk) 19:59, 5 September 2013 (UTC)[reply]

In the case of Human Chorionic Gonadotropin, Tevildo's link explains the general concept, but you might also like to read the article about the hormone, which is a heterodimer composed of an alpha chain and a beta chain. The beta chain can also circulate as a monomer or a homodimer (see PMID 15192308). In other cases that come to mind (which are cytokines, but the boundary between cytokines and hormones is a bit fuzzy), a name was given to a chemical mediator thought to be a single substance, which later turned out to be a class of substances. Greek letters were added to differentiate between the different substances. See interferon. In the case of the interferons, the greek letter is sometimes written first ("gamma interferon"), but more often last ("interferon gamma"). In other cases (Transforming growth factor, Tumor necrosis factor, TNF), the Greek letter last-convention predominates. Interestingly, according to our article, TFNα has been renamed simply to TNF, and TNFβ to lymphotoxin alpha. Lymphotoxin alpha exists as a homotrimer, but may also form heterotrimers with yet another membrane-bound protein called lymphotoxin beta. So in this case, the greek letter does double duty, it differentiaties between completely different molecules, TNFα and TFNβ, and between different chains of the same molecule (lymphotoxin alpha and lymphotoxin beta when the protein is a hereotrimer).

A third and completely unrelated usage of greek letters preceding proteins, indicates the "band" a protein will migrate to in a serum protein electrophoresis. Examples: α1-antitrypsin, α2-macroglobulin. --NorwegianBlue^talk 22:19, 5 September 2013 (UTC)[reply]

September 6

relation between speed and pressure of the fluid

I could not understand the concept of "relation between speed and pressure of the fluid". I read that where the speed is high, pressure will be low. I could not understand this statement. please elaborate and explain in simple language so that I may have a better understanding to this concept. thanks--39.55.149.184 (talk) 07:13, 6 September 2013 (UTC)[reply]

The intro to our Bernoulli's principle article is a pretty nice mix of technical details and lay-language summary if you know a few key ideas. That article defines the principle as "an increase in the speed of the fluid occurs simultaneously with a decrease in pressure". To quote the relevant parts from a few paragraphs later: "Bernoulli's principle can be derived from the principle of conservation of energy. This states that, in a steady flow, the sum of all forms of mechanical energy in a fluid along a streamline is the same at all points on that streamline. This requires that the sum of kinetic energy and potential energy remain constant. Thus an increase in the speed of the fluid occurs proportionately with an increase in both its dynamic pressure and kinetic energy, and a decrease in its static pressure and potential energy." Conservation of energy is a pretty basic idea in science: the total amount of energy must remain constant. The total amount of energy is composed of two parts: Kinetic energy is the energy of motion and potential energy is the energy that is stored (capacity to become/cause motion). Dynamic pressure is the pressure in the direction of motion (like the force of a water jet directed at your hand), and is related to the idea of kinetic energy. Static pressure is the general force pushing outward (causes a garden hose to swell), which is related to potential energy (because the liquid is just pushing not actually moving). So if the flow increases, the kinetic energy increases (more motion), which means the potential energy decreases (to keep same total energy) and therefore less static pressure. DMacks (talk) 08:11, 6 September 2013 (UTC)[reply]

Another way to see that is that if the air is moving from the high pressure to the low pressure, the net pressure force will point along the direction of the motion and the air will accelerate aquiring larger speed at the low pressure location. Dauto (talk) 11:54, 6 September 2013 (UTC)[reply]

Laminated beams

Can someone explain to me please, whether a beam made of 4 strips of 1/4 inch by 1 inch mild steel bolted and clamped together (flat sides together, thus forming a 1 inch square laminated beam), would be any stronger (more resistant to bending) than a solid 1 inch square bar of the same material? If it is stronger, where does it get this extra strength from? I can't find any information on this by googling. Thanks in advance 122.108.189.192 (talk) 08:27, 6 September 2013 (UTC)[reply]

Our Engineered wood article has quite a bit of information and relevant links. I gather that part of the gain in stiffness is due to cross-orienting the stiff axis of alternate layers; bonding of layers also prevents sliding as one mechanism for flexing. -- Scray (talk) 12:24, 6 September 2013 (UTC)[reply]

It's been a long time since I took engineering, but I will take a stab at it. The failure actually occurs because compressive forces make the top of the beam want to spread sideways. The bolts and clamps add to the strength by preventing this sideways deformation. Presumably, if you put the exact same bolts and clamps on the solid piece, it would be just as strong. Take this with a grain of salt, because I am using very old neurons. Tdjewell (talk) 12:25, 6 September 2013 (UTC)[reply]

Yes - but wood isn't a homogeneous material - our OP wants to know about mild steel. Certainly plywood is much stronger than a solid piece of wood of the same thickness...but that's because of the way the grain of the wood flexes and breaks. Also, I don't think we're being asked about failure modes - only about resistance to bending. I'm not sure what the answer is - but I don't think using wood as an analogy delivers the correct answer. SteveBaker (talk) 12:46, 6 September 2013 (UTC)[reply]

It is certainly dubious looking at what happens with wood. For mild steel, first, we need to make a couple of assumptions: We'll assume the volume of steel in the bolts is very small compared to the volume in the mild steel strips. On the limitted information the OP has supplied, this may not necessaily be a good assumption. We'll also assume the bolts are perfect clamps that allow no slip but do not compress the strips anywhere near their their elastic limit. We'll also note that the OP has defined "strength" as resistance to bending. There are of course other forms of strength, eg resistance to breakage or permanent deformation. With all these assumptions, there are two cases.

First case, the bending load is small: Since the elastic strength of steel is the same in both compression and tension (unlike say concrete), a light bending load causes equal stretching on the top of the curve as compression on the inside of the curve. In this case we can see that it makes no difference whether we have clamped strips or just one thick bar - the strength is the same.

Second case, the bending load is high: In this case, the strip(s) on the inside of the curve can buckle inwards, away from the outer strips. Buckling converts the stress in the buckled strips from pure compression into a mix of local compresion and tension. This allows the whole multistrip assembly to bend more. For large loads, the strength of the strip sassemble is thus lower than the single thick bar. Note that the amount of bucking may be imperceptable to the eye but still significantly lower the resistance to bending. In theory, if each strip is made very very thin, in the limit a multistrip assembly will have no resistance to bending at all. However, if the spacing betwene bolts is reduced, the strength is progressively brought back to that of a solid bar. Visualise bending a 100-page A4 book (say 9 mm thick) with your hands. Easy isn't it? Now visualise bending a piece of cardboard the thickness of 100 pages - can you do it? Only if you are a gorilla.

As you increase bending load on a multistrip steel strip assembly from zero, the bending increases linearly up to the point of buckling, the same as for a single thick bar, then it suddenly "lets go" to a certain extent.

Now we can look at bending loads beyond the elastic limit. As the strips on the inside of the bending curve can buckle, the point at which the assembly goes beyond its elastic limit fails is delayed. While a multistrip assembly is easier to bend, it can take higher loads before actually failing. As the strips are increased in number and made thinner, the assembly becomes more and more indestructable.

In a practical assembly, some slippage may occur between strips at each bolt. This obviously lowers the assembly elastic limit, but increases the load at which it will fail.

In a practical case, the bolts will elastically compress the strips - "pre-loading" them. The elastic limit to bending stress is thus reduced, and the assembly will fail at a lower bending load. However this effect should be quite small with properly selected and installed bolting or clamping, and can be neglected.

The non-linear response to bending loads combined with a higher resistance to failure is one reason why leaf springs were used for car suspension until the development of variable rate coil strings and hydraulic shock absorbers (which are actually vibration dampers), and are still used on heavy trucks. In such cases clamps where used instead of bolts to allow slippage and thus make the response even more non linear, and to introduce frictional damping, so that large shock absorbers are not needed.

120.145.46.27 (talk) 15:38, 6 September 2013 (UTC)[reply]

It would be weaker in bending, and substantially so. The bolted laminate beam would experience substantial shear forces at the boundaries between the layers, which would be concentrated around the bolts. The solid beam would have similar overall forces, but they would be distributed (relatively) uniformly throughout the beam. --Carnildo (talk) 23:51, 6 September 2013 (UTC)[reply]

(OP)Thank you all for your comments, I hadn't thought about the idea that the laminated beam would allow more deformation before actually "letting go". the laminated beam that prompted my question is actually stainless steel and used on a powerboat supporting the base of the rudder, so is subject to a lot of vibration. Maybe it was tried as an experiment to allow slightly more flexing without causing "work hardening" (something stainless steel is notorious for). 122.108.189.192 (talk) 07:44, 7 September 2013 (UTC)[reply]

Right - when you WANT more bending - use a laminated beam (hence [[leaf spring]s in some vehicles). When you want stiffness (at least with a homogeneous material like steel) - then a solid beam will be better. If you want resistance to fracturing, then a tube or a cylinder may be better - if you want tolerance to breaking to be a feature - then laminates have advantages. "Strength" is a complicated and rather vague term when it comes to material sciences. SteveBaker (talk) 14:26, 7 September 2013 (UTC)[reply]

Is there a list of human organs weight?

I'm looking for a list of human organs weight from the heavy to light, or vise verse. In example what is the heavy organ in the body? (skin & liver) and what is the light organ of the body? (I don't the answer). In sum up, I would like to get proportion about the body organs (weight & size). 95.35.210.39 (talk) 08:54, 6 September 2013 (UTC)[reply]

for a partial list, see [9]. Most such lists of normal weights cover only the organs weighed at autopsy, and so exclude the skin. -Nunh-huh 09:39, 6 September 2013 (UTC)[reply]

Why did not remain nothing nothing?

Why did not remain nothing nothing — Preceding unsigned comment added by 37.238.108.105 (talk) 11:55, 6 September 2013 (UTC)[reply]

Because something happened. --Jayron32 12:06, 6 September 2013 (UTC)[reply]

(ec) I'm assuming you're talking about the beginning of the universe, or "before" the big bang. Why would you expect nothing to remain nothing? What rules would have prevented it from becoming something? You also probably shouldn't assume that there was ever nothing. I don't have a name (talk) 12:11, 6 September 2013 (UTC)[reply]

Sometimes, there are questions that science can't yet answer - and this is definitely one of them.

The short answer is "we don't know" - or possibly "we don't know yet" - or possibly even "we can never know". Personally, I believe the last option is the most likely. To the best of our present day knowledge, the universe started with a "singularity" - a dot of zero size and possibly infinite mass - in which time was literally stopped and space itself was distorted to a point of zero size. No information can come from "before" that because without time flowing, there cannot be a "before". So in that view, there never was a time when there was nothing. The whole concept of "before" is meaningless when relativity says that infinite mass in zero space stops time. I recognize that this is not the only view of how the big bang started - but it's an answer that works and doesn't violate principles that we broadly understand.

There are many other possibilities, that the universe ends with a "big crunch" when all of time, space, matter and energy is sucked into a gigantic black hole - which then explodes in a big bang to recreate the universe. With that scenario, there could have been an infinite number of bang/crunch cycles, each starting and ending with a singularity that prevents any knowledge of the previous universe from leaking into ours. It's even possible that time loops around so that the universe repeats itself over and over forever, exact in every detail.

But all of those kinds of hypothesis require that the universe started in a singularity - then no information from "before" can possibly pass through the singularity into the present universe - so it seems likely that we can never know what there was before. Without that knowledge, your question doesn't have an answer.

You might find the "Weak Anthropic principle" (WAP) useful in thinking about this. It basically says that in any universe where the conditions would not be enough for intelligent life to eventually form, nobody would have been around to comment on it. It follows that the universe had to have the right characteristics for us to be here.

There are any number of other ideas - things like the Simulation hypothesis that says that the universe is just a software program running in a gigantic computer in "the real world"...I work in computer games and simulation - and when I look at the universe as we know it, there are many aspects of the laws of physics that seem like they were perfectly tailored to being a part of a simulation.

But the bottom line is that (for sure) we don't yet know...and (perhaps) we'll never be able to know, not even in theory.

SteveBaker (talk) 12:40, 6 September 2013 (UTC)[reply]

This problem may be an artifact of making the assumption that something exists at all. Similar to assuming that God exists who created the universe and then asking who created God. An obvious possibility to explore here is that God may not exist in the first place, but this is not so obvious to people who are indoctrinated with religion. Similarly, we all assume without any shred of evidence that there exist such a thing as "physical existence" which is supposed to be fundamentally different from merely "mathematical existence". An obvious possibility is to start exploring if in fact "physical existence" = "mathematical existence" as e.g. Max Tegmark has proposed. This hypothesis has yet to be falsified. Count Iblis (talk) 14:23, 6 September 2013 (UTC)[reply]

Does it matter? Suppose we dig down deep into string theory (or whatever) and find that at the root of all things, it truly is all just math - does that change anything at all? We'd still want to know more about these "physics" that emerge from the abstract mathematical substrate underlying all things. There are plenty of other ideas of that nature out there: That all of time already exists and we only feel the way we do because the nature of our organic memories is that they only contain representations of things to the left of wherever they are in time and not to the right...or that only this precise instant exists or has ever existed and that all of this memory is just a frozen artifact of the way things are. Or that we merely represent a point in Configuration space (Neil Stephenson's fiction "Anathem" is a great way to 'grok' this concept), or that the universe that we know is just a computer game being played by some uber-geek kid on an uber-computer in his bedroom out there in the uber-universe...and that his universe is also just a simulation...and that we are just now beginning to make our own tiny universes inside our own computers.

Sure, there are a million unfalsifiable prospects out there (including a god or gods, the simulation hypothesis and string theory) - but how do you choose between unfalsifiable hypotheses? The only approach we have is to resort to things like Occam's razor and Russel's teapot that fail us when common-sense and appeals to "simplicity" cannot help. SteveBaker (talk) 14:46, 6 September 2013 (UTC)[reply]

That applies only when the opposite of the hypothesis is falsifiable. Saying that there is no god or the universe is not a simulation is only falsifiable assuming specific definitions of god and simulation which allow for deliberate and chaotic intrusion into the normal workings of physics; but the most dignified presentation of either idea allows no chance of such falsification. With an interesting middle ground where people suppose that maybe just and so it can be falsified, which is just the point at which you have to either put up or shut up based on evidence obtained in such a manner. Wnt (talk) 19:51, 6 September 2013 (UTC)[reply]

"Why did not remain nothing nothing?" Because there was nothing to prevent it from turning into something. Dauto (talk) 21:02, 6 September 2013 (UTC)[reply]

You should provide references, Dauto: because there was nothing to prevent it. μηδείς (talk) 00:43, 7 September 2013 (UTC)[reply]

Read the first few lines of the book of Genesis, and that's the best information we have at present. ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:49, 7 September 2013 (UTC)[reply]

Hmmm...let's see:

"In the beginning when God created the heavens and the earth, the earth was a formless void and darkness covered the face of the deep, while a wind from God swept over the face of the waters. Then God said, "Let there be light"; and there was light. And God saw that the light was good; and God separated the light from the darkness."

That doesn't really work - it says that the Earth existed before light, which is clearly false - we know that the sun was producing light from nuclear fusion while the earth was still forming. It also says that there was water on the surface of the earth before the sun existed. As for the Earth being "a formless void" yet having water on it how does that work? Formless voids don't have enough gravity to hold water in place...and as for "separating the light from the darkness" - what the heck is that supposed to mean? God is also supposed to be an omniscient being - why didn't he figure out that light was "good" before he went to all the trouble of creating it?SteveBaker (talk) 00:31, 8 September 2013 (UTC)[reply]

I'm kinda starting to believe that there may be a few plot holes in this book! SteveBaker (talk) 00:31, 8 September 2013 (UTC)[reply]

Only if you take it literally. ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:08, 8 September 2013 (UTC)[reply]

"Blessed are the cheesemakers"

--220 of ^Borg 05:56, 8 September 2013 (UTC)[reply]

"...for they shall be called the Children of Gouda." ←Baseball Bugs ^{What's up, Doc?} carrots→ 06:37, 8 September 2013 (UTC)[reply]

Religion evolved to keep our intellect from being used too productively, it prevents us from being able to give a proper answer to the OP's question. Had our brains evolved to be more immune to religion, then that would have led to our civilization developing faster. We would have reached the point where machines would replace us a lot sooner, in a lot less generations. The probability to exist in such a more rational civilization is thus a lot less than the probability to exist in a more backward religious civilization. So, while we cannot explain yet why we exist, we can explain why God "exists". Count Iblis (talk) 01:53, 8 September 2013 (UTC)[reply]

Religion evolved because we wanted it to. It has value in society - a fact that vexes atheists no end (atheism being its own religion). As to God creating heaven and earth - well, that's just stating the obvious. God in that case equates to the creative force that triggered the Big Bang. Created from what, if anything, we can't know until or if we can find some evidence. ←Baseball Bugs ^{What's up, Doc?} carrots→ 02:17, 8 September 2013 (UTC)[reply]

Atheism is a religion like "not collecting stamps" is a hobby. A global 2012 poll reports that 59% of the world's population is religious, and 36% are not religious, including 13% who are atheists. Religion is an organized collection of beliefs, cultural systems, and world views that relate humanity to the supernatural, and to spirituality . Religion and atheism are mutually exclusive. The only people who ever claim atheism is a religion are religious people trying to demean atheism. Vespine (talk) 00:23, 9 September 2013 (UTC)[reply]

Back to the OP's question: there is a recent, well-reviewed, book by Jim Holt that surveys philosophers' and physicists' views on the subject: Why Does the World Exist?: An Existential Detective Story. Physicist Lawrence M. Krauss published his ideas on the question in A Universe from Nothing: Why There is Something Rather than Nothing last year, which sparked a lot of critical discussion among fellow scientists and science writers (links here). Both these works are written for a general audience, so should be readable by the OP and others. Abecedare (talk) 07:00, 8 September 2013 (UTC)[reply]

can anyone help with references?

The ref desks are for asking questions, not for proposing theories. SteveBaker (talk) 12:19, 6 September 2013 (UTC)[reply]

Has anyone seen things that might support the idea that because microbes live in hydrocarbon reserves and seepage, the reserves might be ecologically important???

I can't find direct references to the idea, although I can find information bits that seem to be relevant to the topic.

I post/pasted my argument yesterday, but didn't ask for references, which is my search goal. The concept is currently apparently undecided.

I'll post my argument again, and at the end are some links. these links show how microbes are responsible for all the functions that would mean they are important, and they are capable because seepage and reserves allow them to be in that place.

it's a little long, but not bad....

argument:: we are wrong about certain important aspects of ecology, both historically and presently. we are not crediting fossil fuels with their worth while underground. currently we state that it is un-important to the bio-sphere if we harvest fossil fuels, although pollution is damaging. I argue that indeed it is important to life both on the surface and underground that fossil fuels remain in place.

claim: the recent discovery of microbial populations in deep hydrocarbon reserves should support the claim that there were microbial populations in shallow reserves.

claim: The density and quality of hydrocarbons within a reserve affects the type and volume of microbial activity (although it is something I've considered that after getting what we can from a reserve, there might be a short term bloom given the newly found relaxed environment. hydrocarbons of high complexity can be broken again and again for energy)

claim: Harvesting fossil fuels dramatically alters the subterranean environment, and therefore the biologic activity.

claim: This affect in turn affects the surface. Hydrocarbon seepage is reduced with reduced reserve pressure.

discussion: WE farmed and deforested nearly everything. We did a lot of replanting. the vegetation as it is today in nearly every location has changed 100% . Lots of things died on their own or were replaced by invasive species. actually, we can't ever know about invasive species of the time. If it's going on now, I would think it's ok to assume it happened already.

discussion: Due to the nature of oil science (get money), it is likely that the kind of data one would use to support these claims isn't available. Not until biological sciences really started producing wild food genetics and such would we have had available data. some independent environmentalist data collector from long ago (or even a bunch of them) would not have been able to collect data that anyone would have found useful. Data collection is huge.

discussion: There are so many things happening to the surface due to human activities, many of the effects that may have been from changes in hydrocarbon seepage were likely attributed to something else, such as pollution or infrastructure development.

Link list:

Link list:

http://www.cartage.org.lb/en/themes/sciences/earthscience/geology/oilandgas/HydrocarbonMigration/Hydrocarbon/Hydrocarbon.html http://link.springer.com/chapter/10.1007%2F978-3-642-05297-2_61#page-1 http://ipec.utulsa.edu/28.d/28_Abs.html http://microbiology.okstate.edu/faculty/mostafa/publications/PetMicrorev.pdf http://www.livescience.com/23126-bacteria-sucked-up-200-000-tons-of-oil-after-bp-spill.html http://microbiology.okstate.edu/faculty/mostafa/publications/PetMicrorev.pdf http://levin.ucsd.edu/publications/Levin%20OMBAR%2005.pdf

— Preceding unsigned comment added by 67.155.62.160 (talk) 12:01, 6 September 2013 (UTC)[reply]

Uhh. the encyclopedia is for finding information. you read the topic, and give information as a reference person. in order to ask the question, I have to tell you what I'm finding info about.

Please take this to the Talk page. SteveBaker (talk) 12:41, 6 September 2013 (UTC)[reply]

the talk page looks different. I don't want to talk to an individual I want to walk away with references to relevant information to support of refute my argument.

HOwever, whatever. I can post again. I can paste for days. what I'm looking for doesn't really get clearer because I say "does it" before everything. to all: click the show button on the green field to gander at answering. — Preceding unsigned comment added by 69.24.176.113 (talk) 13:08, 6 September 2013 (UTC)[reply]

Somehow your links literally have three dots in them and can't be followed. You have an interesting idea which is indeed interpretable as a question (what is the ecological role of biota in oil reservoirs?) Apparently it helps greatly to have both oil and water for microbe growth [10] and the natural microbes can assist in oil extraction [11]. According to this book microbes over many millions of years convert debris to petroleum, mobilize the petroleum, and also assist in its recovery. Since many oilfields have turned naturally into oil seeps, liberating carbon and methane to the carbon cycle, I imagine the effect of these microbes on the environment has been substantial. --WHOOOPS!! I fixed the links. Hilarious! .. I want to make a comment on the liberated carbon. a hydrocarbon is an energy source for organisms, they need not get energy from other sources. metabolism is combustion. cool!! (I've heard the theory that deep life might contribute to earths heat, meaning life can increase the cooling time for earth by storing solar power in photosynthesis and then combusting it in subterranean biomes. off topic.) So these organisms in seepage can add to the surface life without taking away. Wnt (talk) 17:25, 6 September 2013 (UTC)[reply]

Feeding live mice to a cat

Edit: I should probably say that some of you might find this video upsetting.

Something I just saw in a YouTube vid here. I know what carnivory and predation entails and that animals eat other animals all the time, but is it really healthier for the cat to feed it the mice whole - and still alive? I'm just wondering if this is really considered nescessary or not - or is it yet another person doing something stupid with animals on YouTube? --46.208.75.245 (talk) 14:37, 6 September 2013 (UTC)[reply]

This is a serval, a wild cat, and I assume it has similar things in the wild. Domesticated dogs have specifically evolved to eat more starches [12] - I would suppose the same is true of other domesticated animals, including cats and humans. But mammalian carnivores double as scavengers - I know snake owners feed live mice for a reason, but even lions will eat dead meat. Interesting to compare Luka Magnotta, who put the shoe on the other foot and was vilified and hounded until he snapped; many believe animals are equal to humans but not apparently not so many find them equal to one another. Wnt (talk) 17:15, 6 September 2013 (UTC)[reply]

Sorry, I thought that "serval" was a (large) breed of domestic cat. I think that it's generally advised that you don't feed your snake live food, because a mouse/rat/rabbit/etc. can do a lot of damage with teeth to a snake while it's being subdued. They will definitely eat pre-killed stuff. As far as I know, it's snappers that will only eat live prey. --46.208.75.245 (talk) 18:44, 6 September 2013 (UTC)[reply]

I stand corrected! The moment I typed the "know" I should have realized I was swallowing something I'd heard once, rather than thinking about it. Wnt (talk) 19:34, 6 September 2013 (UTC)[reply]

Talk about vagina dentata. μηδείς (talk) 01:37, 8 September 2013 (UTC)[reply]

ATOMIC MASS AND MOLECULAR MASS

i need 5 differences between molecular mass and atomic mass ... can anyone help me ... i want a proper difference ... plz rep me soon .. hope u will be able to give my answer ... (139.190.134.121 (talk) 15:17, 6 September 2013 (UTC))[reply]

See molecular mass and atomic mass - we aren't going to do your homework for you. AndyTheGrump (talk) 15:29, 6 September 2013 (UTC)[reply]

Please do your own homework.

Welcome to the Wikipedia Reference Desk. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. SteveBaker (talk) 14:20, 7 September 2013 (UTC)[reply]

You asked a few days ago and were already given as much information as we have. DMacks (talk) 18:09, 7 September 2013 (UTC)[reply]

clonning

what is clonning ??? (139.190.134.121 (talk) 15:21, 6 September 2013 (UTC))[reply]

I've no idea what 'clonning' is. We do however have an article on cloning. AndyTheGrump (talk) 15:26, 6 September 2013 (UTC)[reply]

Having a clone is like having a twin. If a copy of the genetic code of a life form is used to create a new life form, that new life form is a clone of the first. Dauto (talk) 18:55, 6 September 2013 (UTC)[reply]

(Specifically: An identical twin - but different in age, obviously!) SteveBaker (talk) 14:13, 7 September 2013 (UTC)[reply]

Why aren't galaxies really bright?

If you take a star and move it farther away from the Earth, our eyes will detect a smaller rate of photons from the star. But its angular area will decrease by the same factor, so the star's angular intensity will remain constant. It seems to follow from this that the stars of distant galaxies should be as bright as the stars closer to home. So why can't the naked eye see them? 65.92.4.247 (talk) 19:22, 6 September 2013 (UTC)[reply]

You have a finite number of rods and cones in your retina, and to get one to fire takes a certain number of photons (I think under some conditions a rod can fire because of a single photon, but in any case it takes at least one). So a constant brightness in terms of flux per steradian doesn't help much if you have, I don't know, a quadrillionth of a steradian or something. You just don't get enough photons for your visual system to say "ahah, there's a star". --Trovatore (talk) 19:29, 6 September 2013 (UTC)[reply]

Also the total integrated apparent brightness of the nearby galaxies isn't that big anyway. E.g. the Andromeda galaxy has an apparent magnitude +3.44, but it is quite a bit harder to spot than a star of apparent magnitude +3.44 because of what Trovatore says above. See also this account of how hard it is to spot M81with the naked eye which has apparent magnitude of +6.94 compared to stars that have larger apparent magnitudes. Count Iblis (talk) 19:53, 6 September 2013 (UTC)[reply]

Agree with Trovotore. In theory, the Andromeda galaxy is far brighter in spots because it has bright blue stars in it. But in practice, seeing full brightness requires an entire receptor to be covered, which is just at the lower limit of the distance at which multiple receptors can be covered, i.e. the region in space where a visible disc can be discerned. Apart from a few of the biggest, nearest stars like Betelgeuse these discs aren't actually seen. Wnt (talk) 19:57, 6 September 2013 (UTC)[reply]

Also, the human eye has limited resolution because of spherical aberration which smears the image of distant stars into smudges of very little surface brightness Dauto (talk) 20:42, 6 September 2013 (UTC)[reply]

An interesting read relevant to the question is Olbers' paradox. Dauto (talk) 20:48, 6 September 2013 (UTC)[reply]

Homemade space suit.

Let's say I discovered a portal in my basement that led to the surface of the moon.

I can't get out and explore unless I have a space suit. I know that space suits are very complex pieces of technology, but how difficult would it be to make one from scratch with hardware store and household materials?

Please hurry. I'm really itching to do my first lunar EVA. ;)

209.182.120.18 (talk) 21:49, 6 September 2013 (UTC)[reply]

Hypothetically, if you have such a portal, what's keeping the air in your house once you expose that portal? ←Baseball Bugs ^{What's up, Doc?} carrots→ 22:03, 6 September 2013 (UTC)[reply]

An air-lock... --89.241.237.164 (talk) 19:18, 9 September 2013 (UTC)[reply]

Space suit is (naturally) our relevant article. There are two major issues that need to be addressed - air and heat. I'm sure it wouldn't be too tricky to adapt a standard diving suit to work in a vacuum rather than underwater, although I'm not sure that would count as a "hardware store" item. However, cooling the suit would be a bit more difficult. See Liquid Cooling and Ventilation Garment for some details of what you'd have to construct. The main problem would be making the sublimator to transfer the heat from the suit to the lunar vacuum, unless you could run a hose back to your basement and cool the water there. Tevildo (talk) 22:21, 6 September 2013 (UTC)[reply]

Another big problem is flexibility. A diving suit would blow up like a balloon and the arm and leg tubes would be too stiff to allow you to bend them. A huge question here is how long you expect to be out of the basement. For a short trip, you could dispense with heating and cooling. SteveBaker (talk) 03:09, 7 September 2013 (UTC)[reply]

To begin with, what you're looking for is probably a space activity suit. For purposes of fiction it would be tempting to postulate making one from one of those ridiculous latex suits you see on the internet, plus custom padding, but whatever used would need to be exceptionally strong, I think. Given a good helmet seal I suppose a person could probably survive some trial and error for purposes of fiction, but I don't think I'd want to try it! Wnt (talk) 06:30, 7 September 2013 (UTC)[reply]

Why not buy on old russian one on ebay? 20000$ might buy you one.--Stone (talk) 21:05, 8 September 2013 (UTC)[reply]

Copenhagen Suborbitals are working on a DIY spacesuit, however that's meant to be an IVA suit. An EVA suit would be a magnitude more difficult to build, and much more expensive. WegianWarrior (talk) 08:56, 7 September 2013 (UTC)[reply]

Dear OP.

I have a better plan for you.

Invest $10 to buy a cheap but sturdy garden rake with a nice long handle.
Push one end out of the portal while firmly holding onto the other.
You'll probably be able to reach about 10 kg of lunar material and rake it back into your basement.
If not, buy one of these - it'll probably work for a while on the moon.
Sell your moon rock for $500,000,000 (Current price estimates for moon rock is around $50,000 per gram).
(Do it quickly to avoid flooding the market and driving the prices down!)
Give $1,000,000 to a really good private detective to quietly track down as many ex-NASA Apollo-era space suit designers and constructors as possible.
Bring them into your basement, show them the portal and say "I'll give you guys 250 million dollars to make me a space suit - and when you're done, another 249 million to keep quiet about my portal!" (That's quite a bit more than the moon suits originally cost to develop and build - and they've done it before - so it should be easier this time around).
(Don't forget to tell them whether you want the red commander stripe or not - and how to spell your name for stitching onto the pocket. Ask one of them nicely if they'd please come back and help you to put it on - it's not easy to do by yourself and without training.)
Wait impatiently for your shiney new spacesuit to arrive via FedEx.
EVA party!
SteveBaker (talk) 14:10, 7 September 2013 (UTC)[reply]

Spectacular plan! Regarding the red "publicity" stripes fashion statement: your first missions should forgo stripes, and you should add them later. Nimur (talk) 22:40, 7 September 2013 (UTC)[reply]

protein loosing - sperm

How much protein we loose when we take out a sperm (semen)? and what is the important matter (like minerals etc.) we loose when we do that. thank you. 95.35.210.39 (talk) 22:14, 6 September 2013 (UTC)[reply]

See Semen#Composition of human semen. To answer your specific question, on average, 171 mg of protein per orgasm. Tevildo (talk) 22:23, 6 September 2013 (UTC)[reply]

"To ejaculate" is the proper verb. Sperm is relatively very high in phosphorus, found in the energy providing chemical ATP and its relatives. This is why police can detect its glow with a black light. μηδείς (talk) 00:37, 7 September 2013 (UTC)[reply]

Why am I suddenly reminded of General Jack Ripper? ←Baseball Bugs ^{What's up, Doc?} carrots→ 01:31, 7 September 2013 (UTC)[reply]

Another proper verb: "lose" not "loose". (Though I suppose one could be said to 'loose' semen.) AndrewWTaylor (talk) 11:31, 7 September 2013 (UTC)[reply]

Picture a very small, very fast German sub commander (in fathers, he wears the Iron Cross): torpedo 23,597,151 - Los! Wnt (talk) 17:27, 7 September 2013 (UTC)[reply]

September 7

Largest volcano on earth discovered?

Re: Tamu Massif, as mentioned on the main page - how exactly could scientists not have known for decades that something of that size was down there? I mean, finding a 260,000 square kilometre volcano... it's not like finding a set of car keys, is it? Did they just miss it? I'm confused. --46.208.75.245 (talk) 00:26, 7 September 2013 (UTC)[reply]

It doesn't have an obvious caldera, and it's over a mile down, and 145 million years old. They determined it is just one volcano by studying the lava flows, which all originate from one center. That's not an easy feat given the physical and time depth and erosion and deformation over that period. μηδείς (talk) 00:31, 7 September 2013 (UTC)[reply]

For decades they had assumed that Tamu Massif was formed from several volcanoes that had grown together. Think of the Hawaiian islands for comparison. Each island is a separate eruption center, and hence those islands were formed from a group of related volcanoes. The surprise with Tamu Massif is that the entire feature now appears to have been created by a single volcano. Dragons flight (talk) 01:24, 7 September 2013 (UTC)[reply]

Light emitting black hole

As we know black hole emit a Hawking radiation and the smaller the black hole, the more powerful the radiation. Is it possible that there is a sweet spot for a black hole size so its emitted radiation is in the visible light spectrum not just in usual gamma ray? 140.0.229.26 (talk) 01:07, 7 September 2013 (UTC)[reply]

As explained in the article, the temperature of black hole Hawking radiation is inversely proportional to mass. To get a sun-like spectrum (e.g. 5000 K), you'd need a mass of about 2×10¹⁹ kg (about twice the mass of Ceres), which implies a event horizon radius of about 30 nanometers. Dragons flight (talk) 01:34, 7 September 2013 (UTC)[reply]

Note the evaporation rate according to the article is 3.562 x 10³² W / M² (with M in kg); for the mass given above it should be 8.9 x 10^-7 W. I think that if magnified under a microscope about 4000x it should seem like an incandescent bulb in brightness, but with an arc just (under the scope, appearing to be) 0.12 mm in size the filament would seem a little thin and bright by comparison. Wnt (talk) 06:17, 7 September 2013 (UTC)[reply]

Yellow–brown stains on marble

Is this true? Thanks, 84.109.248.221 (talk) 17:08, 7 September 2013 (UTC)[reply]

It certainly looks like it. You can see similar stains on the arms - but not on other protruding parts. This source says that oils leave a dark brown stain on marble - and that's what we're seeing here. It's hard to imagine any other source of oil being selectively deposited there. The image at right here shows similar staining on places where people's hands are most likely have reached. SteveBaker (talk) 20:06, 7 September 2013 (UTC)[reply]

Also, this blog shows a photograph of a bronze sculpture where the breasts were worn shiney bright while the rest was a more typical tarnish. SteveBaker (talk) 20:16, 7 September 2013 (UTC)[reply]

This photo of the same statue from a different angle shows the same staining - so it wasn't photoshopped on there for a joke. SteveBaker (talk) 13:51, 9 September 2013 (UTC)[reply]

I'm not saying it's not true, but there is in fact at least one imaginable other source of oil being selectively deposited there: A combination of linseed oil and beeswax that used to be "applied as a polish, permeating the structure and, over time, forming an oxalate skin which invariably discolours the crystalline structure. Oxalate skins are complex and almost impossible to remove." ("Cleaning Marble", Victoria and Albert Museum). ---Sluzzelin talk 20:28, 7 September 2013 (UTC)[reply]

OK - but why would someone use the wrong kind of polish for cleaning marble...and do it selectively only on that specific part of the statue - and not at all on the male statue standing right next to it? I have presented evidence that other statues have their boobs groped on a regular and selective basis - how could that not be the case here? SteveBaker (talk) 00:15, 8 September 2013 (UTC)[reply]

See also this photo of the bronze boar outside the Deutsches Jagd- und Fischereimuseum in Munich. Note which parts are highly polished... Tevildo (talk) 00:14, 8 September 2013 (UTC)[reply]

Kidney transplant location

My grandmother had a kidney transplant (in the UK) around 1990. Mum says that her functional kidney is positioned over her stomach, at the front. Could this be correct or mum full of crap, as usual? --89.241.237.164 (talk) 18:09, 7 September 2013 (UTC)[reply]

See Kidney transplantation. According to the article, the new kidney is usually positioned in the iliac fossa (just above the top of your leg). It wouldn't be near the actual _stomach_ (which is much further up your abdominal cavity), but using "stomach" as a general term for "abdomen", your mum is approximately right. Mothers tend to be. Tevildo (talk) 19:22, 7 September 2013 (UTC)[reply]

A quick Google confirms that this is the case, although it may possibly have been different in 1990 (?). Alansplodge (talk) 14:28, 8 September 2013 (UTC)[reply]

My mother was frequently wrong before 1990... MChesterMC (talk) 08:31, 9 September 2013 (UTC)[reply]

Legality of spectrum analyzer use?

Is there any legal challenges to the use of a spectrum analyzer in the US ..? Electron9 (talk) 20:53, 7 September 2013 (UTC)[reply]

Are you sure you don't mean a radio scanner ? -- Jheald (talk) 21:15, 7 September 2013 (UTC)[reply]

A simple spectrum analyzer should be OK. There was a ban on scanners that could receive the analogue mobile phone system after some politician's phone call was publicized. If your spectrum analyzer can decode a signal into audio it may be subject to the same ban, and therefore have frequencies blocked. Usually equipment is made for an international market, so there will be a simple way to make it into a device suitable for a different country. Graeme Bartlett (talk) 21:48, 7 September 2013 (UTC)[reply]

Among the relevant places to check are the website of the Federal Communications Commission - http://FCC.gov - and Title 47 of the Code of Federal Regulations, e.g. 47 C.F.R. §18, regulating equipment for industrial and scientific use. I am not aware of any spectrum analyzer that requires operator licensing or regulation, (e.g., you do not need a HAM license to operate a radio receiver with spectrum analyzer attached), because most of them do not transmit any meaningful quantity of signal or interference. On perusal of http://justice.gov, I found numerous court case dockets with the search term "spectrum analyzer," but almost all of these referred to allegations of intellectual property infringement; a few legal battles involved import and sale of spectrum analyzers and other equipment in violation of tax and import regulations. Nimur (talk) 21:55, 7 September 2013 (UTC)[reply]

I saw this comment at slashdot:

strong cryptography on mobile phones (Score:1)

by fustakrakich (1673220) writes:

Shit, the FBI and NSA, et al put the kibosh on that before the damn things hit the streets. Instead they made a law that prohibits the sale of full spectrum scanners to the public, like was supposed to make them secure...

*

Re: (Score:1)

by Anonymous Coward writes:

Instead they made a law that prohibits the sale of full spectrum scanners to the public

Is that to outlaw bug sweepers and counterintelligence in general?

This in combination with TI:s sub 1 GHz spectrum analyzer MSP430 that covers 300-348, 383-464, 779-928 MHz made me wonder if there's something hiding in the open of the spectrum somehow. Electron9 (talk) 00:09, 8 September 2013 (UTC)[reply]

Some electronics test equipment is ITAR-restricted. That doesn't mean it's illegal; it just means that it's restricted. Chances are very high that if you knew what to do with such equipment, you'd already be on your way to being well-paid and securely employed by a company or organization with access to that type of equipment. Nimur (talk) 00:49, 8 September 2013 (UTC)[reply]

You'd have gotten a better answer at Humanities - off the top of my head, the problem was ECPA, which at the time stood out to me as the first case of banning a radio receiver in certain frequencies like in the Soviet Union. My impression is that the de facto outcome is that people import these products from other countries (I think it was Britain) instead of making them here. In theory I think they might be subject to be stopped at Customs, or perhaps damaged by a meteorite impact during shipping... Wnt (talk) 05:26, 8 September 2013 (UTC)[reply]

September 8

Monoethanolamine membranes?

Hello, I've been reading about CO2 scrubbing systems and I'm curious as to whether there is a way to pipe gas through monoethanolamine without percolating it through. I thought there might be some membrane which is permeable to CO2, but not to monoethanolamine. Does any such material exist? If so, what is it called? Thank you. 71.41.39.2 (talk) 04:00, 8 September 2013 (UTC)[reply]

Understanding calculus in non-geometric terms

I was studying thermodynamics recently and I noticed that I understand calculus, but only in geometric terms, and I couldn't justify (intuitively, but rigorously) the correctness of equations unless I thought about surfaces or lines (or color/density coded 3D space). So I was wondering is there a way to understand calculus in a more general way that doesn't need geometry, so that when I try to understand what happens in say, a gas in a tube, I think of a gas in a tube, not surfaces. And I know that the representation is essentially equivalent mathematically, but it still bugs me. A while ago I had (and still do have) the same kind of problem with integrals. I understand why the area under a curve is calculated by the anti-derivative of that curve, but I don't understand why the more general notion of integrals, especially multi-varibale ones (which roughly speaking is a form of "summation")is related to derivatives. I can understand limits in a general, non-geometric view, but not the things I just mentioned. So is there any book, or article or anything in which these subjects are discussed in more general ways than a geometric view?--Irrational number (talk) 08:30, 8 September 2013 (UTC)[reply]

It sounds like all you need is just practice/experience. When I was in 1st and 2nd year at university doing electrical engineering, we had subjects taught by the School of Engineering where we studied fundamental electrical components, whose behavior can be explained, sort of, with physical models (eg the rubber tube analogy for inductance) but can be clearly and precisely understood with calculus. With just those subjects it doesn't really settle in. But from the Math Department we studied calculus using a textbook that had copious examples from all branches of science and engineering. Once you had worked your way through that book, you were alright, and understanding electrical stuff was real easy. 1.122.160.213 (talk) 10:58, 8 September 2013 (UTC)[reply]

Try reducing it to qualitative visualisations. A derivative describes how a dependent variable changes with respect to the independent variable. That means that whenever the derivative is positive for a certain range of the independent variable, the dependent variable will be increasing as you transition through that range, the converse is also true, and it is true for both points and ranges.

An example, if you have a parabola (y=x²), then its derivative is dy/dx=2x. The derivative is negative for any value of x<0, and positive for any value of x>0. This means that y decreases for any value of x<0, and increases for any value of x>0. Keep in mind that this is only true if you transition in the positive direction for x.

When you take the integral of z(x,y) with respect to x, and then y, you'll get a function which will yield a 3D graph also called a surface. Plasmic Physics (talk) 13:39, 8 September 2013 (UTC)[reply]

Understanding things in only geometric terms is actually not such a limiting thing I have found - since almost everything (at least that I have encountered) can be mapped in some way to a visual concept, and humans are such visually oriented creatures. In fact I struggle to think of anything that I don't think about visually. To give some examples: statistics (venn diagrams, distributions and decision trees), logic (flow chart-like things) and foreign languages (vocabulary in categorised and subdivided spaces/bins, sentences constructed by slotting together parts of speech like jigsaw puzzle pieces). You may find that if you are a visual thinker like me it may be easier to work on your confidence in robustly mapping any situation back to the geometric case so you can always say "I can show this is true for the geometric case, and I can show that the geometric case is equivalent to my case, therefore this must also be true in my case". Maybe I'm misunderstanding you, but it appears to be the second step that is tripping you up (i.e. it might not bug you so much if you could demonstrate that a geometric representation is exactly equivalent, rather than simply "know it is essentially equivalent"). Learning to think about it non-geometrically is also a sensible approach, but personally I wouldn't even know where to begin thinking about anything at all without a visual metaphor. Equisetum (talk | contributions) 14:08, 8 September 2013 (UTC)[reply]

Why does salt amplify flavors in food?

When you add anything else to food it just makes the dish taste more like whatever you added yet salt makes other things taste more strongly, why is that?Bastardsoap (talk) 12:50, 8 September 2013 (UTC)[reply]

I'm not entirely sure that it does. However one suggestion I've seen in a few cook books is that salt pulls liquids from inside of cells to the surface by osmosis and that this brings more flavor to the surface where it's more easily tasted.

Of course it's not just salt, Monosodium glutamate (MSG) has a reputation for enhancing whatever flavor the food already has - but that too is a somewhat dubious claim because MSG has an innate umami flavor of its own. SteveBaker (talk) 13:10, 8 September 2013 (UTC)[reply]

Wouldn't sugar have an equal osmotic effect in equal concentrations?Bastardsoap (talk) 13:17, 8 September 2013 (UTC)[reply]

Perhaps it does? We add it to foods in similar ways. SteveBaker (talk) 13:42, 9 September 2013 (UTC)[reply]

I found National Center for Biotechnology Information - Taste and Flavor Roles of Sodium in Foods: A Unique Challenge to Reducing Sodium Intake which says; "Added salt improves the sensory properties of virtually every food that humans consume, and it is cheap. There are many reasons for adding salt to foods. The main reason is that, in many cases, added salt enhances the positive sensory attributes of foods, even some otherwise unpalatable foods; it makes them “taste” better. For people who are accustomed to high levels of salt in their food, its abrupt absence can make foods “taste” bad." It continues; "One understood mechanism by which sodium-containing compounds may improve overall flavor is by the suppression of bitter tastes.". Alansplodge (talk) 13:39, 8 September 2013 (UTC)[reply]

Suppression of bitter tastes is not a mechanism, doesn't tell you anything about how it does thisBastardsoap (talk) 15:51, 8 September 2013 (UTC)[reply]

I'm almost certain that McGee will have something to say on this subject in On Food and Cooking (how much detail he will go into I cannot say - it's a big book, but the guy has a lot of ground to cover). I will have a look in my copy when I get home in about 8 hours. If I don't post back here within 12 hours feel free to bug me on my talk page because that will mean I've forgotten. Equisetum (talk | contributions) 14:17, 9 September 2013 (UTC)[reply]

Sugar, salt and fat are the essence of tasty cooking. We have a particular reaction to sweetness that is so distinct the word for pleasure and sweet are often the same--compare the word hedonism the root of which is cognate to the English sweet. Note that fat is very different from sugar, in that it has a mouth feel more than a separate taste. Sugar on the tip of your tongue is sweet; fat on the tip of your tongue is inert. Salt seems to enhance the taste of fatty foods. Slat by itself, say on a cracker or pretzel, has a distinct taste. And while salt can be extremely unpleasant; for instance, if you unknowingly find salt, instead of sugar, in the sugar bowl; you can also use it as an abrasive to brush your teeth with with little objection. In cooking salt seems to enhance flavors, especially fat. Steak without salt is almost flavorless. Salt brings out the flavor immensely without really tasting salty at all in the way a salted cracker does. The next time you have a really bad, dry tasteless steak, try spreading a tiny bit of butter or a fatty spread with just a little salt and the taste will improve immensely.

The science of taste is hugely interesting, but it doesn't yet seem mature. One source I found on the internet said there are seven tastes: sweet, sour, bitter, salty, umami, hot, and metallic. I saw a science of cooking show that adds fat, called "richness", as another flavor. The question is not just chemical, but also psychological.

Coriander

Which aldehyde is responsible for the foul flavour of coriander, variously likened the smell of gym-socks, stink bugs, or dishwashing water, only perceptible by a fraction of the populace? Plasmic Physics (talk) 13:00, 8 September 2013 (UTC)[reply]

This paper gives details of the genetic component. It cites this paper, which states "The most important odorants in C. sativum were found to be Z-2-decenal, a co-eluting odour-cluster (E-2-dodecenal, E-2-dodecen-1-ol, and 1-dodecanol), beta-ionone, eugenol, and E-2-decenal." Tevildo (talk) 15:02, 8 September 2013 (UTC)[reply]

Thanks. Plasmic Physics (talk) 23:20, 8 September 2013 (UTC)[reply]

If evolution doesn't exist ...

Moved to the Wikipedia:Reference_desk/Humanities

An Indisputable, Cheap DNA/Genetic Test For Jewish Ancestry/Descent

For the record, this question is not meant to be offensive to anyone. Anyway, is there any indisputable, cheap DNA/genetic test which can test someone's DNA/genes for indisputable Jewish ancestry/descent? The reason that I am asking is that my family members (my mom, my uncle, et cetera) are suspecting that my maternal grandfather might have had some Jewish ancestry, but the thing is that my maternal grandfather has already died in January 2005. I was not even a teenager when he died, and thus I was unable to ask him these types of questions myself. What is really annoying is that my maternal grandfather (who, only in my opinion, did look Jewish to some extent/degree) was an only child, and finding cousins from him from both of his parents is much harder or maybe even (almost) impossible for my case, considering that he died in and his family members live in the former U.S.S.R., while I and my family live in the United States. In addition, my family has not kept in touch with any of my maternal grandfather's cousins for decades by this point in time, so there is no guarantee of us being to find them right now. Thus, I was thinking, if possible, to convince my mom to take a cheap DNA/genetic test to see if she has any indisputable Jewish ancestry if such a test is currently available here in Orange County, California, where I and my family currently live. (For the record, in case anyone is wondering, there is zero dispute that my dad has Jewish ancestry--we know for sure that my paternal grandfather was Jewish; it's my maternal grandfather's ancestry which I and my family are not completely sure about). Thank you very much. Futurist110 (talk) 19:43, 8 September 2013 (UTC)[reply]

No such 'indisputable' test can possibly exist. There are no alleles unique to individuals of Jewish descent. AndyTheGrump (talk) 20:09, 8 September 2013 (UTC)[reply]

On the other hand, given the tendency of people to mingle their genes, a simple card that says "Yes" will be 99.9999% correct, or better. --Stephan Schulz (talk) 20:16, 8 September 2013 (UTC)[reply]

Is there such a cheap test with/to 99.99% accuracy? This kind/type of test would be fine with/by me. And for the record, my maternal grandmother was not Jewish (I know this for a fact, unless there is something about her which I do not currently know; and for the record, she has already passed away as well in September 2009, so I cannot ask her about her and her husband's ancestry/descent as well anymore), so any Jewish ancestry which my mother would have would almost certainly come from my maternal grandfather's side of the family. Futurist110 (talk) 20:21, 8 September 2013 (UTC)[reply]

Also, in regards to a "simple card," if you mean a document/record which states this, then as far as we know, no such document exists. My maternal grandfather's documents/records (or at least the ones of them which we have and which state his ethnicity/nationality) state that he is a "Russian." Of course, keep in mind that in the Soviet Union, children of mixed Jewish-Russian ethnicity could have Russian written on their documents/records (for example, my dad and his sister both have "Russian" written on their documents/records from the U.S.S.R./Russia, but my dad also has documentation/records for his father which explicitly state that his father was "Jewish"), so having his documents state that he is a "Russian" doesn't necessarily mean that he didn't have any Jewish ancestry. Also, there is the matter of the Nazis occupying the city of Oryol, where my maternal grandfather lived with his family back then, during World War II. It is possible that if my maternal grandfather and one or both of his parents (likely one of his parents, though) had some Jewish ancestry, then they would have destroyed such documentation during World War II so that the Nazis could not see and find it. As for my maternal grandfather's parents' documentation/records (the ones which survived and/or which were re-made after World War II, I mean), neither I, nor my mother, nor my uncle (mother's brother) has seen these documents/records, so we do not know if they state that either of his parents had Jewish ancestry or not. Futurist110 (talk) 21:43, 8 September 2013 (UTC)[reply]

As Stephan Schulz suggests, such a test would probably be unnecessary given the low degree of probability that your maternal grandfather had no Jewish ancestry. Anyway, the answer is still no - for the reason I have already explained. AndyTheGrump (talk) 20:40, 8 September 2013 (UTC)[reply]

If Stephan Schulz is talking about a "simple card" which states this, then my family does not have and has never seen anything of that sort which either explicitly confirms or necessarily denies Jewish ancestry for my maternal grandfather and/or for either of his parents. If we had (found/seen) something like this by now, then I would not be asking this question here right now. Futurist110 (talk) 21:43, 8 September 2013 (UTC)[reply]

Futurist110 my interpretation is that if you sent my your DNA and I didn't bother analysing it, but just replied yes, I would be right 99.9% of the time.--Gilderien Chat|What I've done 21:51, 8 September 2013 (UTC)[reply]

Do you genuinely work for some company that does this, or are you simply joking/messing with me here? I honestly can't tell. Also, for the record, my mom's DNA would need to be the one to be analyzed, since my DNA would obviously hint at Jewish ancestry through my dad and through his side of the family regardless of whether or not my mom has any Jewish ancestry. Futurist110 (talk) 22:42, 8 September 2013 (UTC)[reply]

Well, I was half joking, half making a point. Chances are extremely high that you, and your grand parents, have at least one Jewish ancestor. Starting with the Jewish diaspora, there are about 80 generations of gene mixing. Assuming perfect non-incest, you would have about 2^80 ancestors back then, and (2^80)-1 conception events (about 1.2 million million million million). If one of them involved a Jew, you'd have Jewish ancestry. Of course in reality there is plenty of inbreeding (obvious because the population of the world was only around 300 million 2000 years ago), but chances that you (or I, or anyone alive who has roots in areas influenced by the Mediterranean classical cultures) have no Jewish ancestors are pretty close to zero. Note below that 23andme claims they can reliably identify Ashkenazi ancestry if one grandparent was Jewish. That's 4 candidates. Going only 200 years back, you have around 250 candidates. --Stephan Schulz (talk) 05:30, 9 September 2013 (UTC)[reply]

Jewish descent is reckoned through the mother's line. So, no. μηδείς (talk) 22:08, 8 September 2013 (UTC)[reply]

DNA does not obey Halachic law. Futurist110 is clearly asking about 'descent' in the biological sense. AndyTheGrump (talk) 22:17, 8 September 2013 (UTC)[reply]

Exactly. Andy is correct here. I was asking about descent in the biological sense, not according to Jewish religious law. I know that according to Jewish law, I am not Jewish, since neither of my grandmothers were Jewish, and since I did not convert. I also eat things which are not kosher, so yeah. (As a side note, I do have Israeli citizenship, in large part due to the fact that my paternal grandfather was indeed Jewish and had documents/records to prove his ancestry/ethnicity). Futurist110 (talk) 22:42, 8 September 2013 (UTC)[reply]

If you want to look at it that way, Jews were estimated to comprise up to 20% of the Persian Empire and 20% of the Roman Empire's population, and not just limited to the Levant. Presumably there are Saami peoples without Jewish extraction, but no guarantee. μηδείς (talk) 23:21, 8 September 2013 (UTC)[reply]

23andme.com testing can identify Ashnkenazi Jewish ancestry by finding sections of your DNA which match people self-identifying as Ashkenazi. Despite statements above about 99.99% of the people having Jewish ancestry, if that is what is semi-humorously being claimed, many people show no such Ashkenazi gene sequences. See a blog at 23andme which says that the Ashkenazi are "genetically unique and distinct from the European population at large" . A research paper in Genome Biology, a refereed journal stated that 'even subjects with a single Jewish grandparent can be statistically distinguished from those without Jewish ancestry." See also "Finding a family's Jewish ancestry."The cost of 23andme testing was $99 (US) the last time I looked. That seems "cheap" by my standards, but nothing is "indisputable," as seen when a "nonpaternity event" is shown by such genetic testing and the individual's parents say the test must be mistaken, or when a "pureblooded" southern US caucasian turns out to have 1% Subsaharan African ancestry and can't accept it. Edison (talk) 01:42, 9 September 2013 (UTC)[reply]

Zero ohm resistor

Zero ohm resistors apparently do exist in special applications. But in the form shown in Electronic color code, added sans sources by anon, is that real or a joke? Colour me citation needed. 88.112.41.6 (talk) 20:24, 8 September 2013 (UTC)[reply]

We have an article on the so-called Zero-ohm link. At least the latter two of the sources cited seem to check out. AndyTheGrump (talk) 20:47, 8 September 2013 (UTC)[reply]

They sell them! [13] --Stone (talk) 20:48, 8 September 2013 (UTC)[reply]

It's certainly not a joke.

There are certainly places where a zero ohm resistor makes sense. For example, my laser cutter has stepper motors that are driven by a controller module. That module has a current limiter (so it cuts out if the motor stalls or something) - and you "program" that limit with a resistor. The value of the resistor determines the current limit - and there is an equation that they provide to calculate what value of resistor you need for what stepper motor. Well, for a 1.5 amp limit, the equation says that you need zero ohms. If you buy your stepper motors from LinEngineering, you need 1.5 amps (and zero ohms) - if you buy from NanoTech, you need 2.5 amps - and a 220 ohm resistor.

The circuit board has two pads for you to solder the appropriate resistor into - so if you want a 1.5 amp limit, you solder in a piece of wire - otherwise you solder a resistor between those two pads. Now, you might think that you don't need actual zero ohm resistors when a simple piece of wire will do. But consider some automatic manufacturing system - it might look at whether the customer ordered a system with 1.5 amps or one with 2.5 amps - and insert a resistor of either zero or 220 ohms. In those circumstances, there would be enormous benefit to having the physical properties of the "zero ohm resistor" be identical to a 220 ohm resistor so that the machine can easily bend the leads, insert the resistor and solder it in place without human intervention. In those circumstances, being able to buy a bandolier of zero ohm resistors would be tremendously useful. Since normal resistors only cost pennies each - the extra cost of buying a zero ohm resistor instead of using a piece of wire might well be completely negligable compared to the convenience.

SteveBaker (talk) 22:09, 8 September 2013 (UTC)[reply]

September 9

6d transition metals

Has anyone ever published predictions on the melting and boiling points of the 6d transition metals? Double sharp (talk) 03:50, 9 September 2013 (UTC)[reply]

From some simple searching of each article, Rutherfordium has both a predicted melting point and a predicted boiling point although I haven't checked the sources. If you include it, Lawrencium also has a predicted melting point although I don't know where the figure came from as there's no citation in our article, may be you can work out from the history. Nil Einne (talk) 17:02, 9 September 2013 (UTC)[reply]

Stability of Technetium

Just a quick question: exactly why is Technetium radioactive despite its low atomic number? Based on a search I did in the Reference desk, our article on it used to have a section which explained why, but for some reason no longer does so. Could someone explain or link to an article/page which explains why Technetium is radioactive? Narutolovehinata5 ^tccsdnew 11:33, 9 September 2013 (UTC)[reply]

Isotopes of technetium#Stability of technetium isotopes, Mattauch isobar rule. Double sharp (talk) 12:09, 9 September 2013 (UTC)[reply]

But ⁹⁷Tc⁴³⁺ (fully ionized) should be stable as ⁹⁷Tc can only decay via electron capture. Double sharp (talk) 12:12, 9 September 2013 (UTC)[reply]

For a more detailed look at it, see this. Double sharp (talk) 12:35, 9 September 2013 (UTC)[reply]

Medication and the angle of the head

I've noticed that some people (no idea if it's common or not) when taking medication pop the pill in their mouth, take a sip of liquid and then tilt their head backwards. I assume that this is a belief that the pill will be easier to swallow. Is there any reason why tilting the head backwards would assist in taking pills? CambridgeBayWeather (talk) 12:47, 9 September 2013 (UTC)[reply]

Logic suggests that it provides a steeper slope off the tongue, and hence the pill would go down more easily 217.158.236.14 (talk) 12:51, 9 September 2013 (UTC)[reply]

This is entirely original research (well, not quite - I was given this tip by a friend when I had to take some large tablets), but I think the idea is that you want the medication to be swallowed with the liquid, not after the liquid. Tipping the head back makes a tablet sink to the back of the mouth, where it is swallowed at the same time as the bulk of the liquid. Conversely, for capsules, tipping the head forwards means they float to the back of the mouth with a similar effect. Since my friend gave me the tip I've always done it this way (tablets back, capsules forward) and found it significantly easier. I have observed that far fewer people use the head forwards trick with capsules than the head back trick with tablets - perhaps because it is slightly counterintuitive. Equisetum (talk | contributions) 14:06, 9 September 2013 (UTC)[reply]

More ObPersonal, based on experimenting with my cup of coffee and lunchtime baguette immediately on reading this question.

I, and I assume many if not most people, find it somewhat easier to swallow when my head is tilted back rather than in a normal sitting posture or looking downwards (e.g. in a keyboard-wards direction); this seems to be related to relative compression of the tongue and throat in these postures.

Pills/capsules are generally harder and sometimes larger and more angular than typical (masticated) food boluses (boli?) or particles that are swallowed, and combined with one's heightened consciousness in swallowing pills (as opposed to the semi-unconscious actions of normal feeding) are in any case harder than normal to swallow: tilting the head back therefore helps to counteract this added difficulty. {The poster formerly known as 87.81.230.195} 212.95.237.92 (talk) 14:49, 9 September 2013 (UTC)[reply]

wasp 2

What time of the year do queen wasps hibernate in the UK? I had one in my house today flying around and now and it seems to have gone somewhere and hidden. Would this be the right time of year for such behavior? I had one last year as well which emerged in May after sleeping the winter in a cupboard, could it be the same one? Waspgirl03 (talk) 15:03, 9 September 2013 (UTC)[reply]

Three-masted merchantman tonnage discrepancy

According to this painting by Samuel Walters, the Thames, of 454 tons, was built in London in 1829 for the West India trade. Originally owned by Hibberts of London, she later passed into the ownership of Thompson of London and was in service for over thirty years.

Section 1 in this information about the convict ship Thames gives the tonnage as 366.

I suspect both links are about the same ship. Are they? If they are about the same ship, what, if anything, is the difference between the term tons and tonnage? Why is the apparently same ship given a different value (454 and 366 respectively) for something I suspect should be the same?

--Senra (talk) 16:24, 9 September 2013 (UTC)[reply]

See Ship measurements. The tonnage of a ship is a measure of the _volume_ (not weight) of cargo it can carry. Describing a ship as "450 tons" might be expressing its maximum cargo volume using a different metric, or it might be expressing its maximum cargo weight, _or_ it might be expressing the displacement of the ship. The numbers you give (without any more precise definition) aren't inconsistent, and probably do refer to the same ship. Tevildo (talk) 17:33, 9 September 2013 (UTC)[reply]

It's possible that the ship was refitted for these different kinds of service - that could easily affect the tonnage. Of course there are many measures of tonnage too. Read Displacement (ship) for a few possibilities. SteveBaker (talk) 17:34, 9 September 2013 (UTC)[reply]

Thank you both. Useful input. Yes indeed. She could have been refitted between the two dates. The first link suggests the painting was completed in 1839, ten years after she was built. The second link indicates a voyage (the maiden voyage?) occurred between London and Van Diemen's Land (now Tasmania) between 31 July 1829 and 21 November 1829. --Senra (talk) 18:52, 9 September 2013 (UTC)[reply]