The best answers address the question directly, and back up facts with wikilinks and links to sources. Do not edit others' comments and do not give any medical or legal advice.
Is there the same amount of space inside a mans pelvic cavity as in a womans? What is the capacity of spare space in liters (assuming empty bowel) —Preceding unsigned comment added by 79.76.218.43 (talk) 01:06, 22 January 2010 (UTC)[reply]
It might be more straightforward to compare the openings rather than the volume, which would have to have the top and bottom specified, as well as the outer contours. Women need a large opening for childbirth, but a large volume is not so clearly needed for that purpose. In Iowa, "citizen soldiers" apparently need both a large pelvic volume and a large pelvic opening. The state seal specifies an image of a citizen soldier "with a plow in his rear." Edison (talk) 16:08, 22 January 2010 (UTC)[reply]
If you try to freeze a deep body of salt water what you get is a layer of fresh water ice above a slightly salter body of water. That process of separating into fresh water ice and saltier brine is preferred until the brine gets substantially saltier than sea water. If you could isolate that brine, then you could eventually freeze it, but different ions freeze at different temperatures. It would take till around -35 C before the remnant solution of calcium and sulfate ions finally freezes and you are left with a true solid (though actually sulfate can push past -55 C if there aren't enough of the right kinds of cations present). Dragons flight (talk) 04:23, 22 January 2010 (UTC)[reply]
Whats the simliarites and differences between two.
Basically, would like to know since my current prescription to generic prilosec is about to run out. At the same time I was told I had to see my doctor in order to get more of it. Which I totally not worth it in the long run since I have tried Prevacid in the past as well. The reason why I'm on Prilosec at the moment because insurance stopped covering Prevacid and had to switched to Prilosec at that time. Also, my parents are on Prilosec as well. One of them is in the same situation as me and has decided to take OTC Prilosec as the another one takes as well.
Hi Jessica, we really can't answer this question because it almost certainly will constitute medical advice - even if those drugs may be over-the-counter medicine. You should definitely talk to your doctor - it is his or her job to explain these sorts of things to you. If you don't understand their explanation, keep asking them until you understand it. We can link you to the Prilosec and Prevacid articles, but you should not rely on Wikipedia for anything more than a very basic overview of these drugs - especially since we can't guarantee the accuracy of those articles. Nimur (talk) 02:25, 22 January 2010 (UTC)[reply]
You might want to observe if you gulp some air while coughing, thus increasing the pressure. If so, you might want to tell your doctor just in case he forgets to ask about it. 95.115.144.18 (talk) 20:29, 22 January 2010 (UTC)[reply]
Genetic mutations, human electromagnetic fields and electronics
Some people say that electronic devices seem to malfunction more often or fail sooner when they're nearby. Is it theoretically possible that a person with the "right" genetic mutations could emit an electromagnetic field strong enough to damage devices or disrupt their functioning? NeonMerlin02:46, 22 January 2010 (UTC)[reply]
Yes, I expect so. Electric eels are capable of producing large electric fields, so it is certainly possible. It is ridiculously unlikely that that is the case, though. It would require a very large number of mutations, too many to occur in one person at any realistic probability, so it would take many generations to happen. Far more likely is that they are suffering from confirmation bias. --Tango (talk) 03:28, 22 January 2010 (UTC)[reply]
No! Hell no! We'd be easily able to measure a field that strong - and we can't. Electric eels can do that - but they have these enormous, easily spotted organs in their bodies for doing that. They evolved those organs for a reason - why would humans evolve the ability to zap electronics? No - this is just another one of those ridiculous claims people make when they are sad little people with nothing remarkable to say about themselves who wish to feel important and special. If this were true, we'd know all about it by now. I'm sure the James Randi foundation would be happy to pay out a million dollars to anyone who could demonstrate this ability in a proper scientific test. Please tell this to people who claim to have this mysterious ability - and watch as their claims shrink to "well, sometimes it happens" - which is a clear case observer bias. SteveBaker (talk) 04:23, 22 January 2010 (UTC)[reply]
There is a difference between a theoretical impossibility and something that is merely highly improbable. There is no law of physics that forbids humans that emit large EM fields, so the answer to the OP's question is "yes, it is theoretically possible". --Tango (talk) 04:54, 22 January 2010 (UTC)[reply]
Well - theoretically in the sense that it's theoretically possible for someone to be born with blue and green striped skin and six heads. An electric eel has to use a dedicated organ that occupies 80% of it's body volume to produce the pulse it generates! Even that 500 volts at 1 amp wouldn't be anywhere close to enough to leap several feet through the air to zap a piece of electronics. Remember - electric eels live in salty, highly conductive water...but the trick that we're talking about here has to work through air which is a damned good insulator. You can put your phone in front of the 5,000 volts produced in a TV set and you're not taking ANY risk of damaging it! Even if some random human mutation were somehow to produce an organ able to do that - the odds of it happening are so spectacularly astronomically unlikely that we can be very confident that it won't happen over the life of the universe. Electric eels gained this ability through slow piece-by-piece evolution over millions of years - not in one might flook. We can also be sure that the person afflicted with this mutation wouldn't survive the self-induced shock after they first activated this organ. We can also be sure that this thing would occupy several cubic feet of body space - so it would be REALLY noticable. Someone with this ability would be a freak-show mutation - not just some ordinary looking person. Please - we get enough of this crap in the world - let's not extend any hope to the bozo's who claim this kind of crap. No, it can't happen - period. SteveBaker (talk) 05:32, 22 January 2010 (UTC)[reply]
Scientific method comprises formulation of hypotheses, such as the OP reported, followed by rational enquiry into what needs to be, and what can by experiment be, validated. Characterising an unproven hypothesis as crap claimed by bozo's who are "sad little people with nothing remarkable to say about themselves who wish to feel important and special" is not scientific. See the articles Theremin about an electronic device that can be affected by a person at a (short) distance and Radar about electronic devices that can be affected by secondary radiation from a person at a great distance. Light is electromagnetic radiation that when reflected from a person can in particular circumstances upset the function of a low-light camera. Cuddlyable3 (talk) 14:27, 22 January 2010 (UTC)[reply]
So theramins and radar are driven by (to quote our OP) "a person with the "right" genetic mutations could emit an electromagnetic field"? No - theramins work by the change in capacitance of the air caused by the person and radar works by the person reflecting electromagnetic waves - not emitting them. Reflection of light is not emitting light - and you don't need genetic mutations to operate a theramin, or to be visible to radar. Nothing in your previous response has any bearing whatever on the OP's question. SteveBaker (talk) 17:58, 22 January 2010 (UTC)[reply]
If you restrict the meaning of "to emit"[2] to mean not just "to send forth" but additionally "to generate independantly" then reflecting is as you say not a process of emitting. However energy is never emitted without some conversion of incident energy. I described the emission from a radar target as secondary radiation because it is not necessarily simple reflection; rather resonance, phasing and absorption are all factors that determine Radar cross-section. A THEREMIN (spelling) operator by capacitive coupling becomes part of a r.f. resonating circuit. Since the OP asks about any theoretical possibility of a human mutation disrupting an electronic device, we can conceive of some mutation of a person's shape and/or tissue such that his/her quantitative influence on a sensitive device is changed enough to disrupt its function. An example might be a clock oscillator for a high-precision timing device: the oscillator is shielded well enough to hold its frequency within specification when the device is held in an ordinary hand but Mr Mutant is blessed with an extraordinarily large and conductive hand. When he picks up the timing device its function is disrupted out of specification. Of course that is a subtler effect than an electric arc that zaps electronics several feet away and is generated somehow like in an eel'selectrocytes but if that fishy fantasy was ever relevant to the OP's question then you have laid it to rest. BTW the second sentence of my post "Characterising an unproven...." has indeed no bearing on answering the OP's question because it is entirely about your post, from which I quoted.Cuddlyable3 (talk) 18:29, 23 January 2010 (UTC)[reply]
I read an account of a particular woman who could cause data processing equipment to malfunction. It was found to be due to electrostatic discharge due to the clothes/shoes she wore allowing a charge to build up. Plastic shoe soles would insulate more than leather soles. Walking across some carpets can build up several thousand volts of charge on a person, sufficient to make a large and painful spark when he touches something grounded. Such a discharge could damage many electronic devices. But a trash can dragged across the rug could also build up a static charge. Nothing special about it being a human. In an electronics lab I have visited, workers wear grounding electrodes to make sure their shoe soles do not insulate them from the floor, but which have some fuse capability so they would not carry a large current to electrocute the worker. There is nothing special about a human in relation to a Theremin. I expect a cabbage or a piece of aluminum foil or a bag of dirt moving near it could also affect the capacitance and cause an audible effect from a Theremin. My grandfather could never wear a wristwatch, because they stopped working, so he carried a pocket watch. I believe this was due to the amount or nature of his sweat rather than any electric effect. Edison (talk) 15:57, 22 January 2010 (UTC)[reply]
Indeed, it's very possible to zap an electronic device with a static charge - but the OP says (a) "when they are nearby" - not necessarily touching or holding the device - which rules out anything but a really severe spark jumping an unlikely distance - and (b) that this is a "genetic mutation" that causes an electric field to be "emitted" - which doesn't cover merely accumulating static by wearing the wrong kinds of clothes and shoes because our genes don't control that. But even then, a piece of personal electronics like a cellphone or something isn't going to be zapped like that while it's in its case with all of the wires hooked up to the battery. Certainly humans can damage electronics - throwing them violently at the nearest brick wall will do that with a fair degree of reliability! That's not what we're being asked here. Can someone with a genetic mutation emit an electromagnetic field strong enough to destroy nearby electronics? To which the answer is a very definite "No!". Saying otherwise and throwing in random references to theramins (which are specifically DESIGNED to pick up the presence of a nearby human) does a disservice to our questioner by merely muddying the waters. SteveBaker (talk) 17:58, 22 January 2010 (UTC)[reply]
The original poster was not specific about what "electronic devices" are malfunctioning, but another possibility is that the original complainant was talking about a radio or a baby monitor, and as you walk around the radio you certainly will block the signal in some places, possibly causing a lot of static, depending on the character and strength of the inbound signal. Alternatively, if the complainant is carrying a cellular phone, there's the "gallop" interference that is often heard on nearby speakers (including my computer speakers) every 5 or 10 minutes as the cell phone checks in with the local tower; maybe that's the "malfunctioning" that is being complained about. Not related to genetic mutation, except, I guess, for all the genetic mutations in the past that have led our bodies to be physically large enough to interfere with radio signals. Comet Tuttle (talk) 18:24, 22 January 2010 (UTC)[reply]
Let me just point out that eels live in water, which is highly conductive. An electric eel out of the water is unlikely to have any noticeable effect on electronic equipment nearby. It would be like an AC outlet with nothing plugged into it. Looie496 (talk) 18:28, 22 January 2010 (UTC)[reply]
And significantly, electric eels only live in salt water which is much more conductive than fresh water. The very few 'electric' fish that live in fresh water are only able to deliver relatively puny belts compared to electric eels. (See Electric skate, for example). SteveBaker (talk) 18:39, 22 January 2010 (UTC)[reply]
Electronic devices can be quite sensitive, and humans can gather quite a lot of static electricity. When my mobile rings next to my computer mouse the later sends a couple of mouse-wheel-events. On times I don't need to actually touch the touch-pad of my notebook to move the mouse, it is sufficient to move my finger some distance above without contact. When we had to build circuits at university from TTL chips we always could test them previous to switching the real power on. I simply touched the plus and minus wires with the fingers of my left and right hand respectively (or the other way round, didn't make a difference). It was only a few mV but enough to reliably check the logic of the circuit. I don't know how it worked, but it worked reproducibly every time I tried. And no, I'm not joking. 95.115.144.18 (talk) 20:11, 22 January 2010 (UTC)[reply]
I think it less likely that millivolts from your fingers energised your TTL circuits (which would need at least some 2-3 volts to start current in base-emitter junctions) than that the binary high "1" external input(s) you used to test the logic raised the positive supply via the on-chip input protection diode(s). When working with TTL circuits I too noticed that devices could work with their +ve supply pin disconnected. Cuddlyable3 (talk) 18:50, 23 January 2010 (UTC)[reply]
Once, I took an alarm clock with an LCD display and barely any battery power left, and it appeared to become clearer when I placed it near me. I think I also posted this as a question on the RefDesk, and it's perhaps possible that the small variations in EMF fields had a small effect on the almost as small remaining battery energy. ~AH1(TCU)02:21, 23 January 2010 (UTC)[reply]
Nope - because your body is basically a big bag of salty water, radio waves are affected by passing through you. When the battery is low, it takes a bigger radio signal to make your clock produce sound - and strategically placing your body in the right place can concentrate the radio waves enough to make a difference - of course putting it in some other position will block the waves. But it's nothing to do with magical power emanating from your body. SteveBaker (talk) 05:03, 23 January 2010 (UTC)[reply]
The bit about testing logic circuits is good science because the human body can act as a cell, producing a few mV. This is easily shown on a galvanometer or a sensitive multimeter. Years ago, people used to claim that I could make faulty electrical and electronic devices work just by coming near them. A colleague was reputed to have the opposite effect. It was all Confirmation bias, of course, I was just good at guessing what was wrong, and the colleague was good at making inappropriate adjustments. Dbfirs07:35, 23 January 2010 (UTC)[reply]
immunity and cancer
cancer is caused by our own cells , so immunity of body does not effect it. is that so? or immunity of body effect the spreadin' of cancer. in todays date is there any cure of cancer except the lasers? are lasers efficient enough to kill cancer cells from root?
I M NOT ASKING A MEDICAL ADVICE, its just zeal
Cancer arises from our own cells, not caused by our own cells.
Immunity and other body responses is important in regulation of most types of cell growth and tumors including cancer suppression.
There are many treatments that can cure cancer. Surgery can cure many cancers. Chemotherapy can cure some cancers. Radiation can cure some cancers. Most treatments of most serious diseases have some risk and some cost. The ratios of likelihood of cure to likelihood of harm vary enormously for different cancers, different people, different treatments. alteripse (talk) 23:00, 22 January 2010 (UTC)[reply]
Thousands of substances have "cancer-fighting capabilities" in some cancer model or system. It's a long way from that to calling it a cure. alteripse (talk) 15:22, 24 January 2010 (UTC)[reply]
Our article on red dwarf stars doesn't mention this, but there is a reference in Stellar classification#Class M. It gives a fraction of 76% (for main sequence stars in the solar neighbourhood). That tally only includes stars of absolute magnitude 16 or brighter; the proportion of Class M stars would rise further if dimmer stars were included. TenOfAllTrades(talk) 05:06, 22 January 2010 (UTC)[reply]
Thank you -- I saw that figure, but thought perhaps the solar neighborhood (being not necessarily typical of all regions) might not be representative of the universe, which is the context of my question. Also, the article doesn't state what percentage of class M stars are red dwarfs, so there were two uncertainties. So: can anyone answer this regarding only red dwarfs, and in the context of the universe (instead of class M stars in the solar neighborhood)? —Preceding unsigned comment added by 63.17.40.163 (talk) 05:34, 22 January 2010 (UTC)[reply]
Class M stars are red, and by numbers they would be almost all dwarfs, with just a few giants. If you count in the solar neighbourhood, you can make sure that you can see them. Are you interested in brown dwarfs?Graeme Bartlett (talk) 08:17, 22 January 2010 (UTC)[reply]
So I guess the question is: Is the solar neighborhood representative of the universe in regard to the proportion of class M stars? If so, then approximately 75% ("almost all" of 76%) of all the stars in the universe are red dwarfs. If not, then what is the answer? —Preceding unsigned comment added by 63.17.45.118 (talk) 10:04, 22 January 2010 (UTC)[reply]
Oh -- and the figure of 75% would have to be adjusted higher (a little? a lot?) because of this: "That tally only includes stars of absolute magnitude 16 or brighter; the proportion of Class M stars would rise further if dimmer stars were included." Incidentally, I'm asking this because the consensus is that red dwarfs would not have planets capable of nurturing intelligent life, so the fact that they are (apparently) at least 75% of all stars is relevant to the discussion of life in the universe. —Preceding unsigned comment added by 63.17.45.118 (talk) 10:17, 22 January 2010 (UTC)[reply]
That used to be the consensus, but I've seen it challenged quite a lot in recent years. The habitable zone for a red dwarf is much closer in and much narrow, but it does exist. --Tango (talk) 12:31, 22 January 2010 (UTC)[reply]
...and of course that "habitable zone" is for "life as we know it" and not "life as we don't know it but could imagine" or "life as we don't know it and couldn't even imagine". Anywhere where there is a reasonable quantity of energy and matter, there could be some kind of life. SteveBaker (talk) 18:22, 22 January 2010 (UTC)[reply]
Oh, of course. There is no point discussing life as we don't know it since we don't know anything about it. We can hypothesise about certain types of life (silicon instead of carbon, ammonia instead of water, etc.) but there's no reason to believe live as we don't know it would fall into the "could imagine" category. --Tango (talk) 19:42, 23 January 2010 (UTC)[reply]
PS. Another reason to concentrate in life as we know it is that we are very unlikely to be able to make any kind of contact with any intelligent life unless it uses radios in the same way we do, and it stands to reason that life like us is more likely to have technology like ours. --Tango (talk) 19:44, 23 January 2010 (UTC)[reply]
It's relevant to the discussion of life, but proportion of habitable stars is only one parameter of the Drake equation. Given that there are at least four more parameters at which we can only guess the values (life, intelligent, signaling, duration), this one discussion shouldn't be enough to make or break any theories about extrasolar life. — Lomn13:56, 22 January 2010 (UTC)[reply]
Well, three of those four unknowns are not strictly relevent - the probability of there being extrasolar life is not the same thing as the probability of extrasolar intelligent life that is able and willing to talk to us right now! So if all you care about is whether there is extrasolar life at all then there are far fewer unknowns. We have a pretty solid idea of how many extrasolar planets there are. We'll soon be able to analyse the atmospheres of extrasolar planets and calculate what percentage are good for "life as we know it" and "life as we don't know it - but could imagine" - and at that point there is pretty much only one serious unknown - which is the probability of an abiogenesis event occurring (or the probability of a panspermia kind of event). Sadly, since we currently have no idea what our abiogenesis event was or whether panspermia is even a reasonable hypothesis, there is a big enough error bar on that number to make the result of the Drake equation come out to zero or infinity or anything between! Good news for science fiction authors - not so good news for the SETI folks! SteveBaker (talk) 18:22, 22 January 2010 (UTC)[reply]
I'm the OP -- I referred specifically to "intelligent life." I believe bacteria could be found just about anywhere, but it's a long way from bacteria to evolved intelligence, which could not evolve -- much less be nurtured (let's be serious) -- on a red dwarf's planet no matter what the planet was like. See Habitability_of_red_dwarf_systems (which, incidentally, gives an uncited range of 70%-90% "of all stars"). —Preceding unsigned comment added by 63.17.87.54 (talk) 05:20, 23 January 2010 (UTC)[reply]
I wouldn't be so sure. We only have a sample size of 1 to draw all our conclusions about where intelligent life can arise, so those conclusions are very unreliable. --Tango (talk) 19:42, 23 January 2010 (UTC)[reply]
It's impossible to say without knowing the properties and dimensions of the material out of which the spring is made, not to mention the load itself.--Shantavira|feed me12:09, 22 January 2010 (UTC)[reply]
I came across a sum in my textbook, which asks the reader to calculate the pressure at the bottom of a sealed cylindrical container fully filed with water which has been laid down on its side. The answer at the back is given as: 1/2ρgh+Ρ where P is air pressure at sea level. Can anyone explain why it's 1/2ρgh instead of simply ρgh? 117.194.224.21 (talk) 09:12, 22 January 2010 (UTC)[reply]
Do you mean the average pressure on the circular end? Is the printed answer just an average? The pressure will be P at the top of the circular end, and P + ρgd at the bottom. Have I misunderstood the question? Dbfirs09:20, 22 January 2010 (UTC)[reply]
If I understand what you mean by "laid down on its side", then the depth of water is the diameter of the cylindrical. The given answer would then make sense only if the cylinder was twice as tall as it was wide (before being laid down), that is, h=4r. 124.157.247.221 (talk) 12:45, 22 January 2010 (UTC)[reply]
Golden syrup versus sugar
Which is the healthiest option as a sweetener in porridge: golden syrup, white sugar or brown sugar? Why?
There's also (a recent invention), low GI sugar, at least where I live. [3]. However low in this case is 50, which isn't really that much less then the 65 for ordinary white sugar [4] and similar to what 220 said it's unlikely to really make that much of a difference. See also [5]. In particular, presuming you aren't using that much in you porridge it probably doesn't make that much an overall difference to the GI of the breakfast although at least you're consuming porridge rather then something like cornflakesorcocoa pops which likely have a high GI themselves. You may want to consider something like a banana or some other fruit instead of any normal sweetener Nil Einne (talk) 10:15, 22 January 2010 (UTC) That's Coco Pops (no 'a') on Wikipedia 'Cuz'. ;)) --220.101.28.25 (talk) 11:00, 22 January 2010 (UTC)[reply]
It's mostly sugar - and pound for pound it must have almost identical calories to sugar - but what makes it seem worse is that a level teaspoonful of sugar has an awful lot of air in it because of the large crystals - but a level teaspoonful of honey is all honey. SteveBaker (talk) 17:40, 22 January 2010 (UTC)[reply]
Except for the part that's water... It would be interesting to see the calories per unit volume for a scoop of standard-sized sugar crystals (where the non-sugar bits are air) and honey (where the non-sugar bits are water). --Jayron3204:21, 23 January 2010 (UTC)[reply]
Simple WP:OR. I have a cookbook which tells me 1 cup of white sugar is 200 g. 1 cup is 250 ml in NZ as in a number of other Commonwealth countries. So 800g/L. It also gives 2 tablespoons being 30g. We don't use the funny Australiantablespoons (which I admit are neater since they are 4 teaspoons and so can divide into 2 tea for 1/2 and 1 tea for 1/4 albeit makes 1/3 trickier). That means 30ml/30g or 1g/L. Clearly quite a big difference although I'm guessing it's for simplicity as much as anything.
Now nothing for honey but since it's a liquid, finding the density is hopefully quite easy and sure enough honey says "Honey has a density of about 1.36 kilograms per liter (36% denser than water)". Honey of course is easier to measure but is likely a much more variable product. My bag of white sugar says it has 1700kJ/100g (sugar says 1,619 kJ). My jar of honey say 1210kJ/100g while honey says 1,272 kJ. Close enough but I'll use the second one first since our density figure is evidentally for US honey and the figure for energy density is from the USDA. (My cookbook is Edmonds Cookery Book so measures NZ ingredients.) 17000kJ/kg * 0.8 kg/L = 13,600 kJ/L. 12720kJ/kg * 1.36 kg/L = 17,299 kJ/L. The sugar wins as SB expected, by about 1.27 times.
Ideally we need a better range for density, particularly for sugar (I know density isn't a good word but let's not worry about that) and you can probably find something on the internet but I'm lazy so I'll just fudge it and use what I have. You can do your own experiments of course particularly if you have an accurate e.g. digital scale.
Anyway if we take the energy density range 16190kJ/kg * 0.8 kg/L = 12,952 kJ/L and 12100kJ/kg * 1.36 kg/L = 16,456 kJ/L. Throwing in the tablespoon figures we get 16190kJ/L and 17000kJ/L obviously. Although personally I wonder if the range is a little higher, presuming 200g/250mL is resonably accurate perhaps say 175g/250mL-225g/250ml is a better range presuming you measure accurately and your sugar isn't highly packed (which doesn't tend to be too much of a problem for white sugar).
Note, if measuring smaller quantities it's likely to be more variable in any case. Oh and if you want funny old units like calories, you'll have to do the calculations yourself I'm a funny old unit free zone (the general simplicity and ease of calculation I've somewhat demonstrated here). (Admitedly the calorie is metric so isn't quite a bad unit as some stuff like Fahrenheit and does make some sense.)
Definitely, as little as one is enough in many cases. I know a guy who was intelligent, successful, etc who did the "I'll just try it once to see what it's like" thing - ten years later, he's still a total mess. That stuff is evil. SteveBaker (talk) 17:37, 22 January 2010 (UTC)[reply]
Isn't it even possibly deadly on the first injection, for example if one has a low tolerance for drugs in general? The sad case of your friend sounds like something Garrison Keillor said once, about people "who make a bad decision and then stick with it." ←Baseball BugsWhat's up, Doc?carrots→ 18:06, 22 January 2010 (UTC)[reply]
It isn't possible to become physiologically addicted to heroin after a single exposure, it takes dozens at least. Psychological addiction is a different matter, but that's very difficult to quantify. The data show that physiological addiction is quite a bit more rapid for fast-acting psychostimulants such as crack cocaine than for heroin -- the flip side is that the withdrawal symptoms produced by heroin addiction are probably the most unpleasant of any type of drug. Looie496 (talk) 18:19, 22 January 2010 (UTC)[reply]
(ec) Interesting...but of course what starts out as 'merely' a psychological addiction will pretty soon become a physiological one if not handled immediately. Having seen it happen, it's hard to believe that what made him go back for another fix was purely psychological...but if that's what it takes then I've gotta say that even intelligent, well-grounded, happy people can get psychologically addicted after the first shot. What the underlying cause of taking the second shot is - I have no clue. SteveBaker (talk) 18:34, 22 January 2010 (UTC)[reply]
The trouble with psychoactive compounds is that the distinction between physical dependence and psychological dependence is moot blurry - physiological effects manifest as perturbations of neurochemistry (among other physical dependence effects). The extent to which neurochemical dependence is separate from psychological dependence is hard to clearly define. There's no shortage of research on this, and it isn't clear to me that a scientific consensus exists. Nimur (talk) 18:44, 22 January 2010 (UTC)[reply]
The physiological addiction Looie mentioned is related to a change in opioid receptor regulation, which is possible to measure quantitatively. Psychological addiction is much harder to measure quantitatively. --Mark PEA (talk) 12:30, 23 January 2010 (UTC)[reply]
I don't know who posted that image from the Nutt et al paper, but it should be noted that the diagram is slightly flawed since the addictivity of cocaine doesn't take crack cocaine into consideration, which is possibly more psychologically addictive than heroin. Also, the methodology of that study isn't as scientific as one would assume for a Lancet paper. --Mark PEA (talk) 20:16, 22 January 2010 (UTC)[reply]
I have seen a bbc documentary created from the results of that study, and they claimed a difference in effect between crack and powder cocaine could not be established. —Preceding unsigned comment added by 80.226.1.7 (talk) 03:14, 23 January 2010 (UTC)[reply]
From the study's own discussion: "Crack cocaine is generally deemed to be more dangerous than powdered cocaine, but they were not considered separately in this study". What this means is that the participants who were asked to rate the drug harms were told to consider "cocaine" to mean "cocaine (in powder and freebase form)". I guess the narrator/producer of that programme misread that and thought that it meant they didn't consider there to be a difference, but there most certainly is. --Mark PEA (talk) 12:30, 23 January 2010 (UTC)[reply]
Why is tobacco to the left of alcohol in the Lancet graphic above? Don't lung cancer deaths due to nicotine addiction far outnumber deaths due to alcohol? 99.25.112.22 (talk) 05:53, 23 January 2010 (UTC)[reply]
Alcoholism is far more common than lung cancer. According to alcoholism, "In the United States and western Europe 10 to 20% of men and 5 to 10% of women at some point in their lives will meet criteria for alcoholism". I personally have never known anybody with lung cancer, but I've known at least a couple of dozen people whose lives were impaired by alcohol. Looie496 (talk) 16:13, 23 January 2010 (UTC)[reply]
The plural of anecdote is not data. "Each year, a staggering 440,000 people die in the US from tobacco use. Nearly 1 of every 5 deaths is related to smoking. Cigarettes kill more Americans than alcohol, car accidents, suicide, AIDS, homicide, and illegal drugs combined."[6] (emphasis added) 99.38.150.198 (talk) 18:53, 23 January 2010 (UTC)[reply]
It appears that while tobacco has greater chronic (long term) effects, the authors felt that alcohol's short term danger (drowning in your own vomit) makes alcohol the more "dangerous" drug. Really though, it's a bit like comparing apples to oranges. Do you want to slowly kill yourself by smoking for 40 years, or do you want to go binge drinking on the weekends and run the (small, but not insignificant) risk every week of not waking up on Monday? I don't think we should be reading too much into the small difference in the "harmfulness" numbers of the two without looking at other aspects of the drug. The chart makes it clear that both can be quite harmful. Buddy431 (talk) 21:16, 23 January 2010 (UTC)[reply]
Unless the individual user also pays taxes, is part of a health insurance pool, or is susceptible to the secondary comorbidities of nicotine addiction such as tuberculosis? 76.254.71.123 (talk) 00:54, 26 January 2010 (UTC)[reply]
What? No. To an individual, smoking one cigarette is far less harmful than injecting 10mg of heroin. The only exception would be an extremely unlikely scenario such as the person has overdosed on an opioid antagonist. --Mark PEA (talk) 18:39, 26 January 2010 (UTC)[reply]
It's just below the speed of light ("c"). As mentioned in the Upper Limit on Speeds section, it would take an infinite amount of energy to accelerate an object with mass to the speed of light. Since you don't have an infinite amount of energy available, you can get closer and closer by continuing to accelerate, but you'll always be just a little slower than c. Comet Tuttle (talk) 19:33, 22 January 2010 (UTC)[reply]
It's not only below the speed of light. You can actually reach the speed of light. You only need to find an adequate amount of anti matter and transform yourself to light.95.115.144.18 (talk) 19:47, 22 January 2010 (UTC)[reply]
This doesn't sound at all like a homework question to me. Thanks for the mention of the Speed article; I just corrected the intro where it had been claiming that matter can reach c. Comet Tuttle (talk) 19:43, 22 January 2010 (UTC)[reply]
This all sounds kind of familiar, but I'll ask anyway: photons travel at the speed of light, in part because they are "nearly" 0 mass. I might argue that they are not exactly 0 mass, just very small. So, is the speed of light really the upper limit for speed, or is it some other number that's just slightly more than the speed of light? Or is it more like limit formulas, such as 1/n, whose limit is 0 as n approaches infinity, but never actually reaches 0? Ya follow? ←Baseball BugsWhat's up, Doc?carrots→ 20:06, 22 January 2010 (UTC)[reply]
Bugs, photons are presently understood to have exactly zero rest mass (that is, what we conventionally consider "mass"). There's no "nearly" about it (in absence of some verifiable and reproducible experimental result that suddenly upsets a lot of physics). c is the upper bound, which can be reached in the idealized "light in a vacuum" state, though this is never fully found in nature. Note, though, that "speed of light" becomes confusing terminology here -- if photons were found to have mass, and thus traveled at less than c, the photon's speed would be the "speed of light". In particular, the upper bound of c is borne out in quantum entanglement, which though resulting in changes that appear to propagate at speeds greater than c (perhaps immediately), does not transmit information. For transfer of information to work with quantum entanglement (quantum teleportation is one such application), a classical (i.e. c-limited) communication is also required. On the other hand, the notion of the tachyon as an FTL particle is still floated about, though it's presently considered highly unlikely to exist in a causality-breaking form. — Lomn20:31, 22 January 2010 (UTC)[reply]
I'm not so sure that they literally have 0 mass, but it doesn't really matter, because as far as we know, the speed photons travel (in reference to whatever medium they are in) is the fastest known velocity of any object within that medium (be it water, vacuum, or whatever). So if the upper bound is slightly higher than c, it doesn't really matter as it's unattainable. ←Baseball BugsWhat's up, Doc?carrots→
Bugs: PLEASE stop guessing - we all make mistakes - but we really do work hard not to guess. Before you answer, either be very sure you know the answer - or look it up. Look up the Lorentz transform in this handy dandy encyclopedia we have on the interweb and you'll see: . That nice Mr Lorentz said that at some speed 'v', the mass of the object is it's rest mass multiplied by gamma...things get heavier as they are accellerated towards the speed of light. So if you know the rest mass and the speed - you can figure out the relativistic mass. Now, if v is exactly equal to c (ie, if the object is moving at exactly the speed of light) then v2/c2isexactly 1.0 - so gamma is one divided by the square root of zero...one over zero is either undefined (if you're a mathematician) or infinity (if you are a physicist) - so at exactly the speed of light, an object would become literally infinitely heavier than it was at rest. That means that it's mass would be literally bigger than the mass of the entire universe. That's not going to happen. However, we know that the photon does move at exactly the speed of light - and it doesn't have an infinite mass - it has a small but perfectly measurable relativistic mass while it's moving at the speed of light. So we can calculate the rest mass of the photon by dividing its relativistic mass by Lorentz's gamma factor. But if it's moving at the speed of light - then gamma is infinity and its rest mass is it's fairly small relativistic mass divided by infinity. Any number divided by infinity is...zero. So the rest mass of the photon MUST be precisely zero...not a teeny tiny bit above zero...it has to be EXACTLY zero. Now, when you say "it doesn't matter if it's a tiny bit above c" - you have to consider what you just said. If v is even the tiniest bit bigger than c then v2/c2 is just a hair bigger than 1.0 - but the number inside the square root of the lorentz transform is 1-v2/c2 - so that would be a negative number. The gamma factor would be one divided by the square root of a negative number...which is a complex number - and complex number never, EVER show up as real world quantities. Hence, speeds of even the most microscopic amount above c are proven to be clearly impossible by very basic arithmetic. It's not even something to discuss. SteveBaker (talk) 03:13, 23 January 2010 (UTC)[reply]
According to that article, there is a type of electromagnetic radiation that travels faster than "light" in that particular medium. However, "light" is a form of electromagnetic radiation. Unless they're restricting "light" to mean visible light, which is merely a subset of all the possibilities for electromagnetic radiation. Right? ←Baseball BugsWhat's up, Doc?carrots→ 02:52, 23 January 2010 (UTC)[reply]
That article does not say that. It doesn't even say anything like that. I don't know where you're getting your ideas from now. Algebraist03:23, 23 January 2010 (UTC)[reply]
When a body moves at a speed say .8c and another body at .5c (In opposite directions) Then the relative speed between them exceeds C while the maximum speed attainable is C .Doesn't this contradict the above statement PS this Isn't a homework 123.237.193.11
Don't forget time dilation! Once who was traveling around at a close enough speed of light can have time run 1,000x slower for him, so that he perceives himself traveling at 1000c (even though only going at 0.99999c) Googlemeister (talk) 20:19, 22 January 2010 (UTC)[reply]
Yes, that was a fundamental to one of Einstein's theories. Although in an absolute sense those two objects are speeding away from each other (or let's say from their common point of origin) at a net of 1.3c, from their own viewpoint they are not. Basically, nature corrects for this apparent paradox. ←Baseball BugsWhat's up, Doc?carrots→ 20:31, 22 January 2010 (UTC)[reply]
Yes on time dilation, no on perceiving 1000c (or anything greater than c). Every frame of reference is consistent with c being the maximum speed. Various tricks might be shown as to how a traveler might conclude that he's gone 1000c but they break down when shifts in frames of reference are taken into account. For example, consider the spaceship that travels from Earth to a star 1000 light years away, experiencing 1 year on its local clock. This is the sort of thing you might say equates to "1000c", right? But consider: the radio pulse broadcast from Earth simultaneous to the departure of the ship won't arrive 999 years later; it's already come and gone by the time the ship gets there. — Lomn20:44, 22 January 2010 (UTC)[reply]
(after edit conflict) @Googlemeister: Time is perceived to run at "normal rate" whatever the speed of travel, so no traveller can perceive himself to be travelling at 1000c. What he perceives is length contraction of objects not travelling at the same speed. (I suppose in some circumstances, that might amount to the same thing.)
@BaseballBugs: A wrong calculation by a "stationary" observer would add 0.8c to 0.5c and wrongly conclude that the relative velocity was 1.3c. This faulty calculation would not be supported by the observations of either of the travellers. Dbfirs20:48, 22 January 2010 (UTC)[reply]
Precisely. That observer might be standing on the point of origin. He would see them pulling away at their respective speeds and conclude they were receding from each other at faster than light speed. But the ones receding wouldn't see it that way. ←Baseball BugsWhat's up, Doc?carrots→ 20:54, 22 January 2010 (UTC)[reply]
Yes, perhaps I misunderstood what you intended by "absolute sense". It is the faulty assumption about how to add speeds that creates the paradox. I suppose it is true to say that, in the frame of reference of the stationary observer, the rate of increase of separation of the travellers is 1.3c, but this cannot be interpreted as a relative speed observable by either of the travellers. Dbfirs21:23, 22 January 2010 (UTC)[reply]
Quantum mechanics and probability
Hello again, and thank you in advance. As I always say when I ask these stupid questions, I am here as an amateur philosopher and only have a relatively superficial understanding of physics, and a slightly better but still probably inadequate understanding of maths, so you'll probably have to talk down to me a fair bit lol. But I'm curious anyway, and would appreciate it very much if you could aid my understanding.
My question is about the nature of probabilities in quantum mechanics. When there is something uncertain (like beta decay or wave function collapse or some other thing I kind of know about but don't really understand), is the probability of this uncertain thing occurring something that is known for sure? Like we might not know when a nucleus will emit an electron, but do we know at all times the probability that it will emit an electron?
That's a specific example but I'm asking the question generally. In quantum mechanics, are probabilities always certain quantities?
I'm not sure I understand, I think maybe I didn't ask the question right. I wasn't asking about whether there was disagreement on the actual values or mechanisms of these probabilities, I was wondering whether science sees them as even having actual values. I'm talking specifically in terms of the Copenhagen interpretation I think. Dan Hartas (talk) 20:40, 22 January 2010 (UTC)[reply]
If I understand the question correctly... (and assuming I understand this aspect of QM correctly)... let's take an example of something that is considered fundamentally probabilistic according to QM, like the decay of a nucleus of something radioactive. For any individual atom, when it will decay is fundamentally unknowable. I am not even sure if it can be expressed in a sense of "in every second, there is a 1/million chance that this could decay," but maybe someone can clarify that. However, taken as a group, the probabilities average in directly predictable ways according to the stability of the substance—thus we have half-lives, which are pretty iron-clad expressions of the rate of decay over a relatively large number of atoms. The half-life is not an expression of the likelihood of any given sample to decay in that period, but an observed expression of what that rate of decay will be, if that distinction makes sense. (The half-life article discusses this better terms than I am, I recognize.) --Mr.98 (talk) 00:39, 23 January 2010 (UTC)[reply]
And as something else possibly relevant... if you are interested in how weird probabilities can get in QM, I find Bell's theorem and its experiments to be pretty interesting food for thought. It basically rules out the possibility of hidden variables—e.g., the idea that the uncertain aspects of QM are not being secretly carried around by the particles, invisible to the observer but "known" to the particles themselves (or known in a "God's eye view"), but are, in fact, ontologically uncertain. (There are other interpretations of Bell's theorem, to be sure, but that it rules out local hidden variables seems to be the consensus, as I understand it. I am not a physicist, however!) --Mr.98 (talk) 00:43, 23 January 2010 (UTC)[reply]
Bell's theorem doesn't rule out global hidden variable theories—but then, I think those come with just about the same conceptual baggage as any other interpretation of QM. To the OP, you may find this explanation of Bell's theorem, and some of the debate around that time interesting. —Preceding unsigned comment added by Zazou (talk • contribs) 13:01, 23 January 2010 (UTC)[reply]
A quantum mechanical system is always in a definite state, described by a state vector. When time passes that state evolves (in the original nonrelativistic quantum mechanics) according to the hamiltonian of that system as described by the Schrödinger equation. The hamiltonian can be deduced from the laws of physics. The initial state must be measured or set up; it is usually impossible to know entirely. If however both are known, the future state vectors of the system are entirely determined by this.
The Copenhagen interpretation now says, that whenever a property of the system is measured, the state vector of the system is projected (collapsed) onto one of the base states corresponding to the possible measurement results. The square of the length of the projection is proportional to the probability for that measurement result. So if the initial state, the hamiltonian, the amount of time passed and the base vectors of the measurement are known, the probabilities for each measurement can be deduced from this.
Other interpretations give different answers. Hidden variables theories will claim that the probability for one measurement result is one and zero for all others and the full initial state vector cannot be known. Everett claims that the probabilities are all one; the state vector never collapses, it only couples with the measurement device to form a single quantum mechanical state which contains amplitudes for all measurement results. Mr. Coleman explains this way better than I ever could: http://media.physics.harvard.edu/video/index.php?id=SidneyColeman_QMIYF.flv—Preceding unsigned comment added by 80.226.1.7 (talk) 03:05, 23 January 2010 (UTC)[reply]
About human evolution
Starting from the article History of the Americas and found somewhere the theory that humans could have migrated to the Americas 40k years earlier than they did because siberia was infested by spotted hyena. This set my mind wondering and left me with two questions:
How long would human populations need to evolve without contact with each other to 1) not being able to genetically intermix any more, and, 2) not being susceptible to the other ones endemic diseases?
Well, I know, it depends, but are there any theories or estimates out there? 95.115.144.18 (talk) 19:39, 22 January 2010 (UTC)[reply]
I saw a TV show recently that said that homo sapiens and the neanderthals probably came from common ancestors in Africa. It's possible they could still have interbred. But if you can find an estimate on how long ago those branches split, that will give you a rough minimum figure - which I would guess is at least in the hundreds-of-thousands of years. Evolution among larger creatures is slow. But nature has had all kinds of time. ←Baseball BugsWhat's up, Doc?carrots→ 20:02, 22 January 2010 (UTC)[reply]
Why does the size of the creatures matter? Surely it is the length of a generation (that is, the average age of reproduction) that matters. There does seem to be a correlation between size and lifespan, but not a particularly strong one. --Tango (talk) 20:12, 22 January 2010 (UTC)[reply]
Not being at all susceptible to the other's diseases would take a very long time - we can catch diseases from birds (see Bird flu) and we separated from them hundreds of millions of years ago. --Tango (talk) 20:12, 22 January 2010 (UTC)[reply]
Doesn't the virus responsible for spreading bird flu need to be a mutated version in order to infect humans though? Otherwise there would have been a much much higher number of people who catch bird flu. Googlemeister (talk) 20:17, 22 January 2010 (UTC)[reply]
Chimps are a somewhat better analog, because there are some diseases that we still have the same receptors for, despite 6 million years of evolutionary distance. We are too distant to reproduce with them (probably), but not too distant to share some of the same diseases. --Mr.98 (talk) 23:33, 22 January 2010 (UTC)[reply]
You guys/gals do realise Mr. 98 already linked to that right? Anyway more seriously since the issue did come up even if not seriously, Origin of AIDS says as I had expect, bushmeat is usually considered the culprit, from when hunting or butchering the animal. And before anyone makes the joke, yes okay if you really did get AIDS from fucking a monkey (although I'm not sure if we could even get SIV from monkeys) you'd probably say you got it from bushmeat. Sorry didn't read Simian immunodeficiency virus properly, it appears HIV-2 did come from monkeys and [7] also suggests they're a high risk. Given their size [8], if you did try doing a Sooty Mangabey I doubt the monkey would survive and it's likely to be rather bloody, i.e. a rather high risk activity. Nil Einne (talk) 05:16, 23 January 2010 (UTC)[reply]
longjack
is longjack and Tongkat Ali the same thing? and does longjack contain all this: Eurycoma Longifolia Jack / Tongkat Ali / Malaysian Ginseng / Pasak Bumi? —Preceding unsigned comment added by 67.246.254.35 (talk) 19:59, 22 January 2010 (UTC)[reply]
Thinking about getting updated one because the current one that I have is Worst Pills, Best Pills. It is good, but it doesn't have everything that I'm looking for. At the same time it last update was 5 years ago and that's the one that I have. —Preceding unsigned comment added by Jessicaabruno (talk • contribs) 20:08, 22 January 2010 (UTC)[reply]
Personally I like The Pill Book. I like the type of information it provides and the way it presents it. It seems to be updated regularly too. I'm not a pharmacist; I'm just sharing my opinion as a consumer. Generally, you can find out what readers have to say about a book at websites that feature book reviews, such as Amazon's. --173.49.12.84 (talk) 15:14, 23 January 2010 (UTC)[reply]
life on other planets
I was reading a question that involved red dwarf stars and the drake equation and a thought occurred to me. Given that all life as we know it is carbon based, and seemingly dependent upon either O2 or CO2 for life, is it possible to determine what the odds are that life in other forms exists within our solar system, say floating around 100 miles into Jupiter, or bacteria sized organisms oozing around on Venus, considering that we have not explored these areas which would have had a completely different evolutionary path? It does not seem like we have a feasible way to determine that life does not exist in those locations considering that any life we can experiment on would be adapted to live on our planet, not in those other areas. Googlemeister (talk) 20:15, 22 January 2010 (UTC)[reply]
I have a hunch there's an article that would explore that topic. You could start with Life. Also, for that matter, it's possible we ourselves have introduced our own microbes to those areas where we have sent our various satellites and rovers - which might be able to adapt - and might even consume existing life forms there - or merge with them. ←Baseball BugsWhat's up, Doc?carrots→ 20:20, 22 January 2010 (UTC)[reply]
We have an article on SETI. Scientists do not rule out the possibilities of life - even life which is biochemically similar to earth life - within our own solar system. The probability of it existing is low, and the probability we might find it, even it if it does exist, is even lower - but it is part of the motivation for the study of planets and moons within our own solar system. One class of targets in recent years have been the moons of Saturn and Jupiter. You might like to read Extraterrestrial life#Direct search, Extraterrestrial life#Extraterrestrial life in the Solar_System, and the proposed Terrestrial Planet Finder for extrasolar planets. Nimur (talk) 21:24, 22 January 2010 (UTC)[reply]
Carbon is uniquely capable of producing a wide variety of complicated compounds with properties that are really conducive to constructing living things - there are good chemical reasons for supposing that life elsewhere would have to be carbon-based. That in turn puts limits on the temperature range over which life is reasonable - and it's a small step from that to requiring there to be liquid water. But I have to STRONGLY disagree with Baseball Bugs that our microbes "might even consume existing life forms there - or merge with them". That would be like making a Mac program run on a Windows computer. The odds of these other life-forms having compatible DNA is very, very tiny indeed. The only chance that there might be compatibility would be if our life came from their planet or their life from ours (See panspermia) - which means that they aren't really "alien" life at all - just a distant offshoot of our evolutionary tree.
But that doesn't mean that there can't be some really freakishly weird aliens out there. What if a species of fairly conventional aliens - similar to humans, perhaps - learned how to do really serious nanotechnology - or to produce artificially intelligent self-reproducing robots. Suppose then that over eons, the original species went extinct. That would allow either a race of intelligent robots - or an entire ecology of nano-mechanical "bacteria" to appear and colonize their planet. They might eventually learn to evolve and forget who made them. They might well not depend on carbon, water and reasonable temperatures. We would see them as exceedingly alien creatures!
I'm sure that even stranger things are possible - and as I said in a previous thread, there is life as we know it, life as we don't know it (but could imagine) and life as we can't even imagine. (Who said that? I can't find it in Wikiquotes.) By definition we can't guess at what might be in the third category. SteveBaker (talk) 02:26, 23 January 2010 (UTC)[reply]
J. B. S. Haldane said: Now, my suspicion is that the universe is not only queerer than we suppose, but queerer than we can suppose ... I suspect there are more things in heaven and earth than are dreamed of, in any philosophy. (Source for this version of the quote is Advanced Banter). -- Jack of Oz ... speak! ... 20:30, 23 January 2010 (UTC)[reply]
You don't necessarily need compatible DNA to merge (and you certainly don't for eating, you just need vaguely similar biochemistry with matching chirality - that last point is an interesting one, though, some molecules essential for human life have highly toxic mirror images, yet there is no reason for life on a different planet to match our chirality unless we have a common origin). Consider eukaryotes and mitochondria. While they do have compatible DNA (and have exchanged DNA over the years), I know of no reason why they couldn't maintain they symbiosis with vastly different genome storage mechanisms. --Tango (talk) 02:48, 24 January 2010 (UTC)[reply]
Preventing deterioration of rubber-made articles
Rubber tires (and generally things made of rubber) will deteriorate over time, even when they are not used. Are there ways to prevent rubber from deteriorating while in storage? --173.49.12.84 (talk) 21:17, 22 January 2010 (UTC)[reply]
Typically, avoid contact with direct strong light, extreme temperatures, and harsh chemicals, fumes, or abrasives. If you're seeking to preserve the rubber for very long periods of time, you could immerse it in some kind of nonreactive oil bath. To some extent, over long time scales, the rubber will self-react, breaking down its polymer chemical structure, resulting in a more brittle, less elastic material. Nimur (talk) 21:27, 22 January 2010 (UTC)[reply]
I'd go with a nitrogen (or argon) atmosphere, rather than an oil bath. IIRC, some of the components in rubber are oil-soluable. --Carnildo (talk) 01:16, 23 January 2010 (UTC)[reply]
Fellow antique car restorers often recommend Johnson's baby oil. It helps to keep rubber supple by preventing it from drying out - and can even go some way to restoring moderately dried out rubber parts as it's absorbed by the rubber and makes it swell, restoring flexibility. I didn't believe this - but I tried it on some of the rubber and plastic parts of my 1963 Mini - and it works! The stuff can dissolve rubber though - so use a small amount and test it on a bit that doesn't matter too much. Care is needed. SteveBaker (talk)
Surface temperature of planets and moons
Surface temperature can be measured by the infra-red coming off things. What are the surface temperatures of the various planets (solar and extra-solar) and moons. Are they all the same? 84.13.39.208 (talk) 23:54, 22 January 2010 (UTC)[reply]
Bugs, in the name of all that is holy, would you please make an effort to provide a reference each time you post on the Reference Desk? If you had troubled to link to Climate of Mars in this case, for example, you'd see that the estimated high temperature on Mars is 27 degrees Celsius, which is well above freezing, and you would not have posted your inaccurate offhand opinion. Comet Tuttle (talk) 01:40, 23 January 2010 (UTC)[reply]
Specifically, the Mars page (reachable from List of Solar System objects - so there it is a third time) says the MAX is 268 Kelvin or minus 5 Celsius. By definition, that's below freezing. Now, if the the climate page you linked to doesn't agree, maybe you would want to look into reconciling those pages, or at least making the facts clearer. ←Baseball BugsWhat's up, Doc?carrots→ 02:17, 23 January 2010 (UTC)[reply]
That astronomycafe link suggests a max temperature well above freezing. I wonder if there are some issues centering on just how "surface temperature" is defined? However, part of the OP's question was "Do all planets have the same surface temp?" and the answer is emphatically NO. To answer his more specific query - whether he can trust the details of the matter, as presented on wikipedia, is open to question. ←Baseball BugsWhat's up, Doc?carrots→ 03:30, 23 January 2010 (UTC)[reply]
Could someone tell me what time of year are avalanches likely to happen in the Rocky Mountains in Alberta (in the vicinity of Jasper / Dawson Creek)? Also what months are the worst in terms of avalanche severity? Thanks in advance! 24.23.197.43 (talk) 03:30, 23 January 2010 (UTC)[reply]
I'm not familiar with the areas, but I'd recommend asking people who are before venturing into those areas if you have any doubts. Falconusptc05:05, 23 January 2010 (UTC)[reply]
Well, late winter/early spring would be the worst, since avalanches are most likely when the snow and ice starts to melt and the weight goes out of balance on the slopes. At that point, there is so much snow, the slightest trigger would let the mountains come tumbling down. That being said, there is always a risk of avalanches so long as there is snow.
That said, there is no risk of avalanche in Dawson Creek (which is in BC, not Alberta) because Dawson Creek is flat and about 7 hours away from Jasper. Aaronite (talk) 06:45, 23 January 2010 (UTC)[reply]
Thanks for the info, you really helped me out on this. Now, what's the latest in the springtime that avalanches are likely to occur in the Jasper area? I'm writing a series of action-adventure novels about rescue pilots, and I need to know how late in the spring I can set the second one, or whether I should move up the first one by a few weeks. Clear skies to you! 24.23.197.43 (talk) 07:42, 23 January 2010 (UTC)[reply]
What months is the northern part of Hudson Bay (around Baffin and Southampton Islands) frozen over? Also, how thick does the ice get in that part of the bay? Thanks in advance! 24.23.197.43 (talk) 03:34, 23 January 2010 (UTC)[reply]
Just took a look at the article, it says that the bay can stay frozen as late as mid-June but the ice breaks up in the northern part first and then in the south. Thanks, and clear skies to you! 24.23.197.43 (talk) 06:20, 23 January 2010 (UTC)[reply]
These things usually differs from year to year. Some years, it's colder than usual and thus more ice, other years may be warmer than usual and with less ice. Depending on what month is coldest a particular winter, the answer can differ. E.G. (talk) 01:08, 24 January 2010 (UTC)[reply]
I wasn't sure to post this in Science or Computing. But since I wanted more of an EE sciencey explanation, I'm posting here. I'm having a little trouble with the concept of bandwidth concerning video and/or computer cables. For example, why a Cat5 cable cannot carry 10 gigabit signals, or why an audio cable with BNC connectors can't transmit Serial Digital Interface signals. Physically, cat5 looks the same as Cat6, and a BNC audio cable looks exactly like an SDI cable. And it's just pulses of electricity right? Help me out. --68.103.143.23 (talk) 05:27, 23 January 2010 (UTC)[reply]
Um, did you read the articles you linked to? E.g. Although it is sometimes made with 23 AWG wire, the increase in performance with Cat-6 comes mainly from better insulation; 22 to 24 AWG copper is allowed so long as the ANSI/TIA-568-B.2-1 performance specifications are met" Interference including crosstalk and alien crosstalk are of course big issues with ethernet cables and the reason balanced lines are used (again as mentioned in our articles). Ethernet physical layer, Ethernet over twisted pair & 10 Gigabit Ethernet may also be of interest. Note that cat 5e (but not cat 5) can carry 10GE albeit the range being limited to 45m Nil Einne (talk) 05:31, 23 January 2010 (UTC)[reply]
As the articles at Wikipedia note, Bandwidth (computing) is more closer related to Throughput which is the term for amount of data one can cram down a wire. The concept seems quite different from Bandwidth (signal processing), which refers to the part of the radio spectrum ('band') occupied by a particular wireless signal, i.e. literally the "width" of the "band" occupied by the wireless data signal. Using the term for wired communication seems a bit "weird" until one reads the articles, and realize that the throughput of a digital system is related to the freqency of the analog signal carrying it, via Hartley's law. Thus, digital throughput is related to analog bandwidth, and they really are connected concepts. I'm by no means an expert on this stuff, but it is explained in the articles. --Jayron3205:50, 23 January 2010 (UTC)[reply]
Bandwidth in computing is directly related to bandwidth in analog signal processing. Insofar as an analog physical layerisalways present, even in digital communication, the channel capacity is limited by the frequency bandwidth that the cable connection can sustain. That band depends on, among other things, the circuit design of the amplifiers and signal conditioners at each end of the wire; and the inherent physical and electrical properties of the wire. (See distributed element modelortransmission line for some elementary physics overview). A digital signal does occupy a width of a frequency band - usually in the radio frequency range of the electromagnetic spectrum - even if the signal is contained within a wire. This is because the data is digitally modulated on to a carrier (which may or may not be baseband, depending on the technology in use). Jayron's links are the best place to get started with these concepts. In actuality, there's nothing weird about transmitting radio by copper wire - it's a better medium than air, in a lot of respects for communication purposes. Nimur (talk) 07:08, 23 January 2010 (UTC)[reply]
Well, yes, its just that in computing "Bandwidth" is often used to mean "How many bits of data can I cram down this wire", which sounds more like "throughput", and at first glance sounds like it is unrelated to the radio wave frequency bands. I provided the above links to show the physical connection between the two concepts. --Jayron3216:02, 23 January 2010 (UTC)[reply]
This sounds interesting, but unfortunately I can't access either article cause I'm not subscribed to the journal. Could you tell me in your own words what's being compared to what? Clear skies 24.23.197.43 (talk) 06:25, 23 January 2010 (UTC)[reply]
Neither paper makes a concluding remark about the most economic long-term storage solution. The first paper is a literature review on research into various materials that have been used for latent heat storage (e.g. just heating up a material). Its conclusions are that all prior research is near-impossible to compare, because of a lack of standardized measurements. They identify phase-changes of various waxes and other materials as a possible energy storage scheme, but make no clear, concise remarks on feasibility or economy of such a method. The second paper is a review of thermochemical sorption as an additional way of storing heat (sort of a chemical analog to a physical phase change, allowing some control of reaction energetics). The author summarizes the conclusions of prior studies: that chemical heat pumps are consistently the only feasible option for short term storage (because well-suited chemical storage materials don't exist).
It's my opinion, independent of my reading of these papers, that long-term thermal energy storage is uneconomical for the simple reason that heat radiates. I would suggest that alternative storage methods, like electric or chemical batteries, are the most economic storage scheme - until we find a way to economically synthesize long-chain hydrocarbons using electricity and CO2. Unfortunately, none of these solutions are actually very economic - even if ideal processes actually existed, the cost of producing new energy is presently too low to make storing "old" energy worthwhile. If you're willing to consider the reservoir behind a hydroelectric dam as a long-term energy storage mechanism, then that probably qualifies as the single best economic region-scale method of storing energy. (My back-of-envelope calculations estimate that 1 cm of rain stores 11,500 gigajoules of extractable energy in Lake Mead). Try storing that with thermal latent heat systems! Unfortunately, it's not very feasible to store this in hydrological gravitational potential energy - unless you already have a reservoir somewhere, and a source of lower water you could pump to fill it. Finally, I'd just say that energy storage is unnecessary if you switch to energy generation methods that can easily scale according to demand curves - such as nuclear-electric and hydroelectric plants. Nuclear power plants can use control rods to ramp up and down the amount of energy in the reactor. Hydro plants can control the flow of water with flow gates, ranging from zero to full-blast, to ramp production. In combination, these schemes would render energy storage moot - you could build infrastructure to meet your maximal demand, and when that is unneeded, no energy would be wasted. Coal plants, as a counter-example, cannot easily "throttle back," because they have a very narrow regime of operation (coal has to be shoveled in at roughly the same rate, while nuclear rods can be highly throttled). Solar, wind, and other energy production schemes are totally uncontrollable - you get as much power as the sun is willing to shine and the wind is willing to blow. Nimur (talk) 07:22, 23 January 2010 (UTC)[reply]
I agree 100% with Nimur, but would add that tidal hydroelectric generation could be combined with super-efficient storage by pumping water up when excess energy is available at high tide and using the extra height gain to obtain more energy back at low tide. (The process actually gives back more energy than is stored, even though the pumps and generators are less than 100% efficient, because extra energy comes from the rotation of the earth-moon system.) The varying lag in time of high tide round the coast of the UK could give continuous generation, though less energy would be available during the week of neap tides at first and third moon quarters. Dbfirs12:40, 23 January 2010 (UTC)[reply]
Energy production is not a zero-sum game. If you build excess wind capacity, you can achieve any level of reliability you need. It increases costs, but less than flood insurance would otherwise increase them as long as you're displacing carbon. 99.38.150.198 (talk) 14:16, 23 January 2010 (UTC)[reply]
The best long term energy storage is achieved by tapping into naturally-available wells of it, like petroleum, or solar energy. If you are thinking of sitting down in a bunker waiting for the Apocalypse to come, you may be waiting a rather long time. Vranak (talk) 13:04, 23 January 2010 (UTC)[reply]
Unfortunately, your belief is counter to expert opinion. For a succinct summary, take a look at Forecasts and Analysis of Energy Data from the United States Department of Energy. Even a very optimistic outlook and rapid growth of wind sector puts it at a miniscule (I would even go so far as to call it trivial and negligible) fraction of the total energy production. I think you will be hard-pressed to find any well-thought-out energy solution which uses wind energy without a baseline production scheme. Nimur (talk) 19:01, 23 January 2010 (UTC)[reply]
By "miniscule" I mean that even if wind energy grows extremely fast, meeting optimistic, exponential growth curves, the Department of Energy speculates that it will be less than 5% of total electricity production capacity and supply less than 2% of total energy consumed in the United States by 2030. Data from the Energy Information Agency, supplementing the 2010 Energy Outlook report. Nimur (talk) 06:55, 24 January 2010 (UTC)[reply]
That halted growth projection might be a cynical outlook on prospects for continued federal support for renewable energy. But more seriously, this 1995 report explains that most wind projects have been integrated into the grid not because they are cost-effective, but because of government programs: "In many cases, the planned projects were not selected because of their economic competitiveness, but were initiated because State governments or Public Utility Commissions provided additional incentives..." As the weak economy dries up these government incentive programs, a realistic outlook is that the more expensive alternative energy sectors will become more and more marginalized. Let me again point out the fallacy of scalability - if everybody adopted a more expensive energy solution, no macro-market would exist to subsidize it. Wind power would thus need to stand its own ground on economic merits - which it cannot do, given realistic projected energy prices over the next few decades. Here's another good resource - Wind statistics. That ever-elusive geographic intersection between land that is good for wind electric production and land that is near a place with high electric demand and finally, most importantly, land which is legally owned by somebody (state or Federal government) who can use it for power production is rapidly saturating. This overview map, map 2, and these data tables, indicate that the best sites have already been developed. What's left - we can build wind power production facilities in places where they aren't needed, but that's very uneconomic. I suspect that a combination of these factors is responsible for the 2013-ish tail-off in wind electric growth. Nimur (talk) 01:56, 25 January 2010 (UTC)[reply]
Do you really think that the Department of Energy includes political considerations in staff projections? Honestly, that could explain it, because the other explanations are all implausible. The 1995 EIA report is very much at odds with the actual experience of, e.g., Colorado, where officials call 30% renewables by 2020 possible "with or without legislation."[11] Moreover, your colleagues at Stanford and U.C. Davis have widely published a plan to reach 100% renewables world-wide by 2030 using only a subsidy scheme paid for by reduced flood costs.[12] Is there any evidence from the past five years that wind has reached anything approaching saturation? 76.254.71.123 (talk) 22:31, 25 January 2010 (UTC)[reply]
I'll tell you the same thing I tell my colleagues at Stanford and U.C. Davis. If wind energy is the wave of the future, and is so economically viable, why don't you start investing heavily in it? The usual response is a series of dumb looks - experts in wind energy don't drink their own kool-aid and don't believe blogs that claim wind will power the entire country in two decades. They also commute to work in petroleum-powered automobiles when it's inconvenient to bike. But I fear we may be far off topic by now. Maybe we can continue this discussion elsewhere. Nimur (talk) 13:51, 26 January 2010 (UTC)[reply]
After reviewing your link, which should be www.ice-energy.com, I have to do some bubble-bursting. This is not an energy-storage solution. It's not even energy-efficient! What these devices are, are commercial/industrial size air conditioners that they are selling to residential customers. The plan, if I may boil it down, is to be less energy efficient by over-cooling the AC unit during the night (when electricity is cheaper). This means that lots of refrigerant is sitting around in the unit, cold, doing nothing (and slowly warming back up). Then, although this is wasteful, they trickle the coolant into the unit for the duration of the day, when the users want to turn the AC on. They are actually using more energy for the same amount of cooling, because of inefficiency in the thermal storage (by thermal radiation, as I mentioned above). However, this scheme will ironically actually cost less, because energy is cheaper at nighttime in some markets. The plan, as it stands, is to increase demand for electricity at night - not to decrease total demand for energy.
The enthusiastic respondant will reply, "but if everyone switched to these systems, the energy demand during the daytime would be lower!" But, this is nonsense. If everybody switched to these systems, energy demand would be high at nighttime, and it would no longer be economic to charge a different rate per kilowatt hour at night. And since the inherent thermodynamics are not in favor of energy storage, more total energy would be consumed. These schemes only work as an economic way to save costs if a very few people use them. Essentially, they are playing off the market price curves of the aggregate economic system by participating as "non-ideal" consumers - they are a niche market. If that market grew to large scale, it would be subject to the same commodity pricing as we have now.
I am baffled how many of these plans I see as proposed solutions to the energy challenges our society faces. They're only one notch above the ill-conceived perpetual motion machine - and they also indicate that our schools do a bad job teaching thermodynamics. Storing energy results in losses. This is a fundamental result of thermodynamics. Therefore, any energy storage mechanism will actually increase total energy demand, compared to an equivalent system which only draws as much power as it needs currently, i.e., if the power plant can scale its production. If the plan is to transform our entire society to use an energy storage system, whether it is city-wide or locally distributed on rooftops, then we will consequently increase our total societal energy consumption, because there is waste in every energy storage scheme.Nimur (talk) 19:17, 23 January 2010 (UTC)[reply]
Tidal pumping is the one exception to any energy storage mechanism will actually increase total energy demand, but I agree that there are problems with growth of marine organisms in such systems. Perhaps the only long-term, eco-friendly, complete solution to energy needs is nuclear fusion, but this is far in the future unless a vast amount of money gets thrown at the development. Meanwhile nuclear fission will probably have to be used much more extensively to reduce global warming, with safe disposal of waste products of course. Dbfirs20:49, 23 January 2010 (UTC)[reply]
Nimur, I'm pretty sure the anonymous poster understood all that. The idea is not to convert everybody, but to convert enough people that nighttime and daytime energy demands are roughly equal; then you can reduce your peak capacity, which might yield savings that exceed the storage losses. Or it might not; I couldn't tell you. But it's not an inherently illogical idea. -- BenRG (talk) 00:48, 27 January 2010 (UTC)[reply]
I haven't read the link, but it seems to me converting everone is not necessarily going to result in there being a lot higher night time usage then day time. It depends on various factors particularly how much of the energy usage is due to AC. From Nimur's description, you will only be moving the AC usage to be increased during the night time (and hopefully decreased during the day time), there are still clearly plenty of other things which will be used during both times and some of them may be higher at day time. For example many shops, offices and factories operate primarily during the day time and while AC will be part of what contributes to their energy usage it's not the only thing. Also given the OPs comment, perhaps one of the ideas is for a more dynamic smart usage system where the AC is turned on and off depending on the availability of energy and stores it when it's high, to be used when it's need. I'm not saying I think it's a good idea or will work. Actually from Nimur's description it sounds silly. Nil Einne (talk) 12:33, 27 January 2010 (UTC)[reply]
oxygen's diradical nature ... what about the halogens?
Oxygen's diradical nature supposedly stops its radical nature from oxidising all organic compounds at room temperature, except for the trace singlet oxygen that occasionally forms. Yet, chlorine and fluorine, etc. are not diradicals, yet they are dangerous oxidants at room temperature. Aren't a great deal of their oxidative properties non-radical in nature? Or is it because *O- (radical anion) makes a bad leaving group, as opposed to Cl-? (But F- isn't a great leaving group either...) John Riemann Soong (talk) 09:47, 23 January 2010 (UTC)[reply]
I think you are crossing wires on two sometimes slightly related concepts. Radicals can be good oxidants, but a) not all radicals are always good oxidants (consider the dozens of odd-electron metals) and b) there are lots of good oxidants which have no radical nature (say, permanganate. What makes something a good oxidant or not is much more closely related to the electron affinity of the species, rather than the odd/even nature of its electrons. Even though dioxygen has two "unpaired electrons", as predicted by molecular orbital theory, that actually gives those two electrons the opportunity to spin couple; which is actually somewhat slightly MORE stable than opposite-spin pairing. This is what gives stability to the electron configuration displayed in chromium, the s1d5 configuration rather than the s2d4 configuration. --Jayron3215:57, 23 January 2010 (UTC)[reply]
Over-watering my Philodendron
I've got a Philodendron that much to my chagrin I seem to have over-watered: the leaves are yellowed, soft, and wilting. I understand the concept of over-watering in general - the roots begin to rot, not enough oxygen, etc. But this very plant began as a collection of cuttings sitting in a glass pitcher filled solely with water not 6 months ago. The roots developed and then I transferred it to a soil pot where it was growing fine enough until just recently. This is fascinating. Could someone please explain to me how a plant that grows perfectly well in 100% water can receive too much water when it's in soil (and quantitatively receiving less)..? 61.189.63.173 (talk) 10:06, 23 January 2010 (UTC)[reply]
When there are a few roots in water there is enough oxygen, but with many roots and organic matter and bacteria in soil there are heaps of things using oxygen, and it is all used up. Graeme Bartlett (talk) 21:49, 23 January 2010 (UTC)[reply]
I and other people find it a problem to decide when a pot plant needs watering. Purpose-made probes that suppossedly measure the soil dampness do not work. I've concluded that the way to do it is by weight - when the pot+earth feels light, water it. Pot plants seem to do better by fluctuating in the moisture of the soil rather than trying to keep them moist all the time - reflecting what happens in nature I suppose. 92.29.81.16 (talk) 11:23, 24 January 2010 (UTC)[reply]
Different plants have different preferences though. If you use the same pattern or watering with a variety of plants, you will find which ones will survive by artificial selection. Philodendron did not survive with my watering practice - once a week, but may have been to do with environment too. Light, temperature and humidity can be important too. Graeme Bartlett (talk) 00:19, 26 January 2010 (UTC)[reply]
Circulation in Whitefish
Most of my life (decades!) I have wanted to know how the flesh of whitefish remains white, even though their blood is red. How does the red blood supply the white muscle without the capillaries making that flesh look some shade of red or pink?
I have tried the following Google searches: "whitefish muscle" and "whitefish circulation".
Meat (of fish or fowl or other animal) is white or red based on the content of myoglobin, a muscle protein, not on the basis of the color of the animal's blood. See [13] and [14] for further detail. - Nunh-huh12:35, 23 January 2010 (UTC)[reply]
Relative levels of myoglobin are what define "white meat" and "dark meat." As indicated to some extent in White_meat#Poultry and Muscle#Types, type I muscle is slow twitch and capable of sustained activity. It is often termed red and in chickens, for example, which do not do a lot of flying, this type exists in the legs, which perform the bulk of the bird's activities. Breast meat in chickens is white because it's primarily type II muscle, which is fast twitch and incapable of sustained activity. In ducks, which are built for a lot more upper body activity, there is really no white meat, and both uppers and lowers are red. DRosenbach(Talk | Contribs)13:51, 26 January 2010 (UTC)[reply]
hot water storage
electric hot water tank
There is no "handyman" ref desk, so I'm going to pester the scientific folk with my inanity. I have a question regarding the pipe (and associated valve) on the bottom of my hot water tank (see visual aid). When I first moved in to the flat (at Christmas), the valve was in the "off position" and a friend (perhaps as dim as me) remarked that it may be a waste pipe and should be "open", and twisted it (seemingly forever) to the right left. I suspect that it's "cold water in", actually. All the way to the right left, it leaks water out of the top of the valve, though not very much. Too much pressure? Even about halfway to off there seems to be some slight discharge. How far away from off should the valve be? How much water is the ideal amount to let in (if it is the cold water in as I suspect) and how do I know when I've achieved this? Is there any danger or unwanted side effect to leaving it completely open with the slight leak? I find that I run out of hot water very quickly (not enough for a shower and the washing up in the same day), is there any chance it's because of this valve (or is it just because the tank is super tiny for my extortionately long showers)? Advice, guidance, knowledge, sneering, and sympathy all welcome. Thank you! Maedin\talk13:12, 23 January 2010 (UTC)[reply]
If you have a look at the diagram (as IP 93 suggests) on the heateritsays that the pipe with the valve is the cold in!.:-) If there is a waste or overflow pipe I hazard a guess it may be behind the heater, possibly leading outside or connected to a drain pipe. This is installed under a kitchen counter or similar apparently? The label at the bottom says 125 L (Litres I expect). Does not seem very large, I suggest shorter(!) or cooler(!!) showers; or showering and 'washing up' (clothes?) on seperate days(!!!). I can't say too much for certain about how far the valve should be opened, if your local water pressure is 'high' then it is theoretically possible it could stress the pipes/connections. Perhaps turn it off to 3/4 and if there is no problem turn it down a bit more? Too far and your heater may shut off entirely.(or burn out if not enought water to cover the elements.) You say 'flat', if this is a rental then the landlord may be able to help? 220.101.28.25 (talk) 13:50, 23 January 2010 (UTC)[reply]
(e/c with Dbfirs below) I did say sneering is welcome, so I'll just say that yes, of course I noticed the blue label, and no, it doesn't really answer my questions, does it? You'll notice that I didn't actually ask, "is this the cold water in?" If I hadn't read the blue label, then I probably would have believed the person who claimed it was a waste pipe. I am (as you may have noticed^^) female and either don't believe labels that come on hot water tanks or assume that I am misunderstanding them, and the friend who made the initial guess was male (and I was reluctant to admit that a guy might not know what he was talking about regarding these things). "Washing up" is the British term for "doing the dishes", btw. Yes, I'm renting the flat, but landlords are notoriously tardy at responding to non-urgent queries and mine has been no different. Thanks for your help so far, :-) Maedin\talk14:08, 23 January 2010 (UTC)[reply]
Just open it sufficiently for your shower to operate at a reasonable flow. Closing this valve more will reduce the flow and increase your warm shower time. I was puzzled when you said turning to the right to open because most people would think you meant clockwise looking from above, and that would close the valve. Dbfirs14:03, 23 January 2010 (UTC)[reply]
It's not really about "too much pressure". As you turn the spindle to open the valve, you'll notice that the amount of spindle (The spindle is the round shaft that is attached to the handle, and disappears into the body of the valve) you can see sticking out the top of the valve increases (this is because there is a screwthread cut into it further down inside the valve and, as you open the valve, this unscrews - it's what actually makes the valve work).
The next thing you need to know is that there is a seal (called the gland) around the spindle. It is just underneath that odd-looking nut (sometimes called a gland follower) that fits round the spindle where it goes into the valve body.
What is probably happening is that as you open the valve fully, the bit of the spindle in contact with the gland changes (as the spindle moves out, you try to seal on a bit that's lower down) and you've probably hit a patch that's a bit rough or dirty.
To start with, try tightening the gland follower a little bit. One or two flats is usually sufficient (a flat is one sixth of a turn - as soon as you look at it, you'll appreciate why) - but your aim is to get a decent seal without making the valve too stiff to turn. If that doesn't work, you may need to repair the gland. That needs a bit more care as, if you get it wrong, you could cause a significant flood.
In terms of how far to open the valve, standard practice is to open it fully (assuming you have eliminated your gland leak), and then close it a quarter turn (to stop the threads binding).
Zeusfaber (talk) 18:18, 23 January 2010 (UTC)[reply]
As a rule of thumb - a shower uses 2 US gallons of water per minute. If you read the label right and the tank contains 125 liters then that's 33 US gallons - and should be enough for a 16 minute shower. Of course if the water is really hot - you're probably mixing it about 50/50 with cold water - so I'd guess that you could sit in the shower for half an hour without running out! You should probably be aware of the amount of hot water that other activities uses: Taking a bath can use 50 gallons - and if more than half of that is hot water from the tank - then you could easily run out. If your clothes washer uses hot water, then it'll take 10 gallons (but with modern detergents, you can save a ton of money by doing cold water washes) - and if your dishwasher is plumbed into the hot water lines then it can take 20 gallons. SteveBaker (talk) 18:51, 23 January 2010 (UTC)[reply]
Doesn't the tank begin refilling itself before it hits rock bottom empty? If it's re-filling itself with cold water you won't get the full 32 minutes of hot shower. APL (talk) 03:31, 24 January 2010 (UTC)[reply]
Yes, the tank starts filling with cold water as soon as the shower is turned on. It relies on the layering effect (hot water being less dense than cold) and lack of turbulence. By the time half the hot water has been used, a temperature drop will be noticeable, but the top half will still be much hotter than the cold water in the bottom half. Dbfirs08:11, 24 January 2010 (UTC)[reply]
[Unindent]. Let's start by describing your tank. There are 3 copper pipes connected to it, which are all water connections. The one at the bottom is the cold water in. The next one up is the hot water out. The one slightly higher than that (with the black plastic valve on) is a pressure relief. The first 2 do what you'd expect - let cold water in and hot water out to your shower, etc. The other one takes care of the chance that your cold water pressure might just possibly be high enough to damage the tank. If it is, the black valve will release to let water out and to safeguard the tank. In all normal circumstances it will not operate ever. The pipe at the bottom has the valve that you're worrying about on it - this is a stop cock and is essentially just used to turn the cold water on and off - it's not really designed to be left partly open or closed. I would advise turning it anti-clockwise (from the top) until it won't turn any more. Taps of these sort do have a tendency to leak when not fully open or closed, so this may well help your problem with the leak.
The cyclinder has 2 electrical heater ("immersion heaters") to warm the water up - these are the white things sticking out on the right. There are 2 since this is designed to work with Economy 7 - the lower one can be used at night to heat a load of water on a cheap tariff and the upper one is used at day to top the water up on a more expensive tariff. If you don't have Economy 7, you would just connect both to the electrical supply (this would have to be done by an electrician. Both of these have thermostats to set the temperature to which they heat the water. They should both be set to 60-65°C. I would guess that if you've not got enough hot water, it may simply be that the lower one is not connected, or set at too low a temperature.
By the way - the tank doesn't heat the water as you use it (much) - it pre-heats the water, which you then draw off. It looks like it's not insulated, so (a) you could almost certainly see how much hot water is in it by feeling the tank with your hand and (b) you are wasting money by letting the tank cool too quickly. You should ask your landlord to insulate it.
You guys are great, thank you so much. I just have a few more questions, mostly in response to Phil.
I am not certain if I'm on Economy 7 or not, but I'm guessing so. I've got two boxes for mains switches; one box is labelled water heater and storage heater (yes, I heat this place with bricks, if you can call that heating^^) and the other is for . . . everything else. I assume I'm right in thinking that they wouldn't be separated if they weren't on different tariffs. This would explain why a shower in the morning means I have no hot water in the evening: it's not heating up any water except at night. How does that information change your advice? It seems to me that I need something topping up the temperature on a more expensive tariff; does that mean I need an electrician to connect the top immersion heater? Is this something I should be asking my landlord to take care of, or the sort of thing I should arrange myself? (If that seems like a stupid question, I've never been a tenant before, I owned before this (with a male of the species, hence my profound ignorance of water heating).)
The other thing is that the tank isn't warm. Not even a bit. So it must be insulated inside? A friend has helpfully suggested that I could take the cover off the tank and find out, but I'm not sure I have enough testosterone for such a crazy idea.
As suggested, I've now opened the valve fully and quarter-turned it back so the threads don't bind (whatever that means). The leak is really slight and I don't have the right tool for adjusting the gland follower, so I'll leave it.
Yes it does sound like Economy 7 tariff. The tank is probably a modern one that is actually much smaller inside but has insulation built in. If there are two separate immersion heaters then the second one can be wired up to a switch so that you can boost the hot water whenever you wish (at the higher rate, of course). Has this not been done already? If not then you do need an electrician. Strictly, you also need your landlord's permission (and your landlord ought to pay for the work to be done!) If you are not able to ask your landlord, then a friendly electrician might be able make a temporary connection to a 13A plug, but this would be frowned on by Health & Safety experts because the tank is not a portable appliance. If you need lots of hot water for very long showers, it is actually possible to wire both immersion heaters to switches so that you can almost heat the water as you use it (5Kw is not quite enough for an instant shower unless the water is already warmish). A good electrician could wire this so that you still retain the benefit of Economy 7 rate overnight, but it is not standard wiring, so you would need someone who really knows what they are doing. Dbfirs16:17, 25 January 2010 (UTC)[reply]
The real test of whether you have Economy 7 is the electricity meter - if there are 2 sets of dials on it then it's highly likely - have a look at the photo in the article I linked to and you'll see what I mean - one is labelled "Normal" (daytime tariff) and the other "Low" (night-time tariff). You could also see what it says on your bill. There must be a time switch (or more likely, two time switches) somewhere that control the immersion heaters turning on and off. If you can find them and can work out how to over-ride them (i.e. nothing worse than turn them on when they're already off owing to the time) then you could consider turning the lower heater on about an hour before you need a shower. But don't blame me when your electricity bill doubles! And I think I was wrong about insulation - another look at the manual and it dos look if there is some insulation built in to the tank. More is always better, though. --Phil Holmes (talk) 17:05, 25 January 2010 (UTC)[reply]
Hi, I am pretty sure that your upper heating element has burnt out. They often do if they are set to run too hot. It is only a small task so it should be easy to (get the landlord to) replace it. It is only four screws, one on the cover and three cables - live neutral and earth. Good luck. :-) Chienlit (talk) 19:31, 25 January 2010 (UTC)[reply]
Actually, they normally use an immersion heater spanner to screw them in and out, and that can take considerable force. It would also have been sensible to suggest draining the tank before trying this, to avoid flooding the place as all the cold water rushes out of the hole previously occupied by the heater. --Phil Holmes (talk) 12:16, 27 January 2010 (UTC)[reply]
why no hair in biodegradable waste?
The Dutch version of the article Biodegradable waste says that, in general, dog or cat hair is not considered biodegradable waste ("GFT") and should be treated as "regular" waste. Why is this? Is hair not biodegradable or compostable?
It depends on what they're going to do with the waste stream. If they're going to feed it to pigs, clearly you don't want pigs eating (too much) hair. If it's going to compost, it is biodegradable, but much more slowly (and I think in wetter conditions) than other wastes - so it'd still be hair when the rest of the stuff was ready to be used. If they're going to dry it use it to power an incinerator then hair is fine. -- Finlay McWalter • Talk16:32, 23 January 2010 (UTC)[reply]
Hair is basically 'dead', and from the fact that it can still be found (ie on Egyptian Mummys) long after soft tissues are gone, suggest that it is not biodegradeable in any meaningful way. --220.101.28.25 (talk) 17:12, 23 January 2010 (UTC)[reply]
That's totally untrue. Mummies are preserved and dried and kept underground in a sealed container in a nearly lifeless environment. In normal conditions hair is decomposed by moths, fungi, and bacteria (ref (warning: a bit grisly)). If hair wasn't biodegradable then the world would be covered in a layer of meters of compressed hair. Being "basically dead" does not grant immunity from decay. -- Finlay McWalter • Talk18:01, 23 January 2010 (UTC)[reply]
This says that at least one species of cockroach will eat hair and even fingernail clippings...so yes - it's definitely biodegradable. However, it may well not be compostable or recyclable in any useful manner - which would explain the comment in the article. SteveBaker (talk) 18:39, 23 January 2010 (UTC)[reply]
I am currently taking an A-Level physics course, and I am very quickly falling behind my classmates, largely because I fail to understand a fundamental part of the syllabus, which is energy. What exactly is energy? Can we see energy? Does energy have a mass? What does energy look like? Any help would be greatly appreciated. --T.M.M. Dowd (talk) 21:36, 23 January 2010 (UTC)[reply]
Energy is that physical quantity which can do work - meaning it can exert a force through some distance. It can take many forms - most of them are not directly visible. When some object with mass has velocity, the object also has kinetic energy. When an object with mass is placed high above the ground, it has gravitational potential energy. So, you don't actually see the energy, though you can observe details about the situation from which you can deduce that there is energy present. At the level of basic physics you are working at, do not worry about energy-mass equivalence. For your purposes, energy has no mass - it is a different and unrelated physical quantity. (When you progress to a more advanced and more generalized treatment of physics, especially considering very large amounts of energy, it can be shown that in fact energy and mass are related - but in classical, every-day physics, they are separate quantities). Have you read our article on energy?Nimur (talk) 22:05, 23 January 2010 (UTC)[reply]
Understanding the concept of "energy" alone is relatively meaningless for the most part...If you could give us an example of how exactly you don't understand it, we'd be far better set to give you more useful information. If you provided us with an example question, we wouldn't answer it, but we might be able to explain the concepts you'd need to know to do it yourself. For me, light was my biggest problem in A-level Physics...well, that and practical work...) Vimescarrot (talk) 00:22, 24 January 2010 (UTC)[reply]
Sadly, you don't get a scientific answer - because there isn't one. So you get a touchy-feely philosophical one:
Little kids like to play the insanely annoying "why?" game. "Why can't I have chocolate? Because you've had enough already. Why is that enough? Because it's not good for you to eat only chocolate. Why isn't it? Because your body needs all sorts of different foods to work properly. Why does it need that?" ...and so on. There is no answer you can give that will make them not say "Why?" in response.
Well, I guess "energy" is the ultimate answer...it's end of the chain of reasoning and logic. Energy is that least, most minimal end of the line explanation for pretty much anything. You can't see it, feel it, taste it, smell it or hear it (although you can see, feel, taste, smell and hear the consequences of it). We can indirectly measure it - but not directly. We can predict how it changes from one form to another, we can even weigh it (thanks to E=mc2)...but we do not, cannot, directly deal with it.
For A-level physics, it's a letter in an equation. It's a convenient variable in the equation that explains how a pendulum swings - gravitational potential energy turns into kinetic energy which turns back into gravitational potential energy at the other end of the swing. You don't have to understand what the energy is - only how it changes form and is the intermediary between height and speed. Energy cannot be created or destroyed - it changes from one invisible, intangiable form to another. Set off a stick of dynamite and chemical energy changes to kinetic and acoustic energy and both eventually turn into heat. Turn the ignition key on your car and chemical energy in the battery becomes electrical energy in the wires, spins the starter, creating kinetic energy - the engine turns, the pressure in the cylinders produces heat with more electrical energy in the spark, you release chemical energy in the fuel and then more heat, causing expansion of the gasses, more kinetic energy, more heat - sound energy.
Everything that happens in the world is driven by energy changing from one form to another - but the energy itself is completely intangiable. It's a number in an equation...but it's the number that makes the universe tick over.
It's important at this stage to keep the curiosity about that intangiable at bay. Follow where the energy goes - do the math to follow it's passage through these various forms. Learn, do good work, pass exams, go to college, do more math, follow that energy, pass more exams. Get a job as theoretical physicist, get tenure, think about energy. Come back and tell me what the heck it is!
Yep. Feynman is my personal hero. His frustration was mostly with school physics textbooks though. The result of which that he produced a series of lectures that resulted in perhaps the finest set of physics textbooks in the world. After all of that - he really had no better insight into what energy actually is than use mere mortals. SteveBaker (talk) 01:52, 24 January 2010 (UTC)[reply]
Right. At this point, the important thing to do is to understand that this abstract concept has been shown, by experiment, to follow some quantitative rules that relate to kinematics and dynamics (i.e., position and velocity). The simple manifestations are easily defined with straightforward equations that relate energy to an object's velocity, its height above a surface, and so on. Nimur (talk) 01:50, 24 January 2010 (UTC)[reply]
True. Our OP also asks some very specific questions:
What exactly is energy? - As we've said. We don't have a deeper answer. Energy is the end of the line for explanation.
Can we see energy? - Not directly. We can use energy to light a light bulb and produce photons that carry the energy to cells in the back of our eyes which turn the photons into chemical, then electrical energy which flows into our brain and by a series of other electrical and chemical energy transitions causes us to "see" the energy...but can we actually see the energy? That's a philosophical question. Energy changed form...that's what it does.
Does energy have a mass? - Yes...yes-ish. E=mc2...or if you prefer, the far less memorable but equally true: m = E/c2 to find the 'mass' of the energy, divide the amount of energy by the square of the speed of light. But gosh - isn't light kinda fast? Well, yeah - and fast-squared is a freaking huge number. So you take if you weigh your AA battery when it's new and again when it's run down - the difference in mass due to the loss of the energy is so unbelievably tiny that we have no way to measure it. On the other hand - if you set off a nuclear bomb, the tiny amount of mass that gets turned into energy gets multiplied by the speed of light squared and you get are really big kaboom!
What does energy look like? - Since we can't see it...(see answer 2), this is a non-question. What does something that you can't see look like? If a tree falls in the forest and there is no-one there to hear - does it make a sound? Dunno - ask one of those weird philosopher guys?
I see that you're having problems with something that's very fundamental. Instead of giving you an answer that's technically correct but may or may not be helpful to you, I'll try to explain the concept using an analogy. Think of energy as currency in the world of physics. It is what enables you to do "work". Energy can exist in many interconvertible forms, just like (monetary) currencies. In the real world, if you want something "done", you need to spend money. In a similar way, if you want "work" done, say moving something a certain distance while opposing a force, you need to expend energy. If you pay someone money, you don't have the money anymore, but the recipient has it. In a similar way, when you expend energy, you don't have it anymore, it goes somewhere else, but is not destroyed. (Actually it's not strictly true, because of mass-energy equivalence, but until you're comfortable with the basics, it's better just to think of energy as something that's conserved, i.e. something that cannot be created or destroyed.) Can we see energy? Well, that depends on what exactly qualifies as "seeing" something. The fact is, some forms of energy (photons of visible light wavelengths) can stimulate our eyes and whereby be perceived. Does energy have mass? No. (Not exactly, but for your purpose right now, it's better to think of energy as something that's distinct and unrelated to mass.) --173.49.9.141 (talk) 03:30, 24 January 2010 (UTC)[reply]
@173.49.9.141 : As far as we know the conservation of energy is strictly true. Mass energy equivalece doesn't make it any less true. Dauto (talk) 06:27, 24 January 2010 (UTC)[reply]
Well, if you want the real McCoy about energy rather than the simplified lie-to-children version that is taught in pre-University physics, then here it is. Energy is conserved in classical physics because the laws of classical physics are are independent of translations in time (see Noether's theorem). More precisely, symmetries are associated with conserved or invariant quantities, and the conserved quantity associated with time translation symmetry is what we call "energy". Situations in which energy is dissipated into an irrecoverable form (which we call "heat") are always associated with an increase in entropy and hence a breaking of the time translation symmetry at a macroscopic level - the resulting asymmetry in time is called the arrow of time. Note that this is all within the context of classical physics (which includes special and general relativity). In quantum physics things are somewhat more complicated because conservation and symmetry laws are replaced by uncertainty relations between conjugate variables. For a more detailed explanation read Chapters 3 and 4 of Feynman's The Character of Physical Law. Gandalf61 (talk) 11:06, 24 January 2010 (UTC)[reply]
January 24
Maps of Australia
G'day! I'm looking forward to a drive across the Outback later this year. I will have a GPS and a road atlas, but as far as I can make out, Australia has no national grid reference system like I have in the UK. Are the reference grids on their maps just arbitrary or are they consistent from one publisher to another? Do the road atlases give any indication of latitude and longitude?--Shantavira|feed me10:49, 24 January 2010 (UTC)[reply]
Possibly. Quoting from page 3 of the 2008 "StreetSmart" Perth Street Directory (bold is added by me for emphasis) - which is Perth metro area, not the outback!
“
The black coordinates located at the corners of each map refer to the Australian Map Grid (AGD84). The pink coordinates ... refer to the Map Grid of Australia, Geocentric Datum of Australia (GDA94). The coordinates on the Regional Centres maps refer to the Map Grid of Australia (MGA94). For more information about GDA94 please refer to: http://www.landgate.wa.gov.au/corporate.nsf/web/Geodetic+Data.
Thanks, that's interesting. Looks like we need an article on that system. My GPS supports UTM, but I guess that is different. Does anyone know if I might be able to download the Aussie system to my Garmin GPS? Their website is not very informative. Maybe I should just buy a new GPS in Oz?--Shantavira|feed me12:34, 24 January 2010 (UTC)[reply]
Don't know about downloading, but a spare GPS, if you are going to rely on them a great deal, would be a very good idea. Are you for example planning to go off paved/marked roads? Our A$ is high at them moment so buying it here will be more expensive, though I have seen them for less than ≈$A150. 220.101.28.25 (talk) 13:41, 24 January 2010 (UTC)[reply]
Nah, probably only on paved roads, so the GPS is only for location rather than navigation. Your dollar is really low at the moment compared to the GBP [15]. I was amazed to discover that Google Street View now includes a lot of the Outback, including some dirt roads.--Shantavira|feed me14:43, 24 January 2010 (UTC)[reply]
You're reading the chart backwards, that graph shows GBP is low against AUD. The pound is only buying AUD $1.70, one year ago it was much stronger buying AUD$2.20. Vespine (talk) 22:14, 24 January 2010 (UTC)[reply]
You have to watch those exchange rates! Petrol/fuel/gas isn't cheap here either, probably(?) cheaper then the UK. (In the Outback I imagine it will be VERY expensive, compared to city prices). Possibly add several Jerry cans to your list of necessities? --220.101.28.25 (talk) 18:33, 25 January 2010 (UTC)[reply]
If hypochondriacs have a tendency to self-diagnose themselves with many diseases, why do they fail to self-diagnose themselves with hypochondria, and thus realise that they actually probably don't have those diseases? Also, is this related to the Dunning-Kruger effect? --Mark PEA (talk) 14:52, 24 January 2010 (UTC)[reply]
Hypochondria is a tendency to channel anxiety into worries about one's own body health. Perceived evidence of disease is given more weight than evidence of health or reassurance from other sources of health information. I do not consider hypochondria very closely related to the Dunning-Kruger effect. alteripse (talk) 15:16, 24 January 2010 (UTC)[reply]
Hypochondria isn't deadly or debilitating. Hypochondriacs have more to worry about than hypochondria. Even if they do diagnose themselves with it, it's not important enough to bother a doctor about when they've got so many other things that could be far more harmful. Vimescarrot (talk) 15:46, 24 January 2010 (UTC)[reply]
nb: livejasmine.com is an adult webcam site that pops up (I guess from ad links or partnership links) when browsing many porn sites. I guess the original-poster wants to be able to block these popups. I don't know how to do that, but running Firefox's "flashblock" extension means that the popup window doesn't have a live webcam feed. Googling for "livejasmine popup block" finds lots of threads about how to block the popup itself. 87.114.29.120 (talk) 16:57, 24 January 2010 (UTC)[reply]
Presuming the popups need to access livejasmine.com and don't use an IP or have different domains that they continually vary, a simple (and common) solution that will work in most OSes (albeit you'll need to find out how to do it in each) would be to put livejasmine.com in the hosts file and point it to 127.0.0.1 or something similar. This will not block the popups windows from opening, it will simple mean you'll get an webserver doesn't respond message (unless you actually have a webserver locally or wherever you point it to) and as I've said will not help if the websites start using popups from an IP or they cycle between domains. And it's obviously not an effective way of stopping all software from accessing the domain, they could query a hardcoded domain name server or query the defined DNS themselves bypassing the OS DNS subsystem (if the DNS is a router you control you may be able to do something similar on the router) but it should work for browsers. Nil Einne (talk) 04:27, 25 January 2010 (UTC)[reply]
Expression of ratios
The title makes this sound like a mathematics question. I have never been able to understand an answer - or, to be fair, most of the questions- on the mathematics desk, however, so I am hoping someone with a science background will have the same information. (I sometimes understand science answers.)
I had always understood that ratios are expressed using a ":" in the form "A:B", and represent a mathematical relatipnship between A and B. In the article Vaccination controversy is the following sentence:
In the U.S. during the year 2001, routine childhood immunizations against seven diseases were estimated to save over $40 billion per birth-year cohort in overall social costs including $10 billion in direct health costs, and the societal benefit-cost ratio for these vaccinations was estimated to be 16.5.
(The emphasis is mine.) Thinking this was merely a typo for "16:5", I went to the footnoted source which contains the following sentence:
Direct and societal benefit-cost ratios for routine childhood vaccination were 5.3 and 16.5, respectively.
Thus the "ratio" presented in the WP article is correctly transcribed, but I still don't know how a ratio can be a single number. Is anyone willing to explain? Bielle (talk) 18:37, 24 January 2010 (UTC)[reply]
It's 16.5:1. The one's implied in a ratio when they only show one number like that. For every dollar spent on vaccinating kids, $16.50 is saved in health care costs down the road. You can also check out Benefit-cost ratio for information about this specific type of ratio, and cost-benefit analysis for more general information on the subject. Buddy431 (talk) 18:53, 24 January 2010 (UTC)[reply]
When the ':' and the second number is missing, it's generally accepted that ':1' is intended. So 5.3 and 16.5 really mean 5.3:1 and 16.5:1 respectively. In other words, the benefit is 5.3 times the cost or 16.5 times the cost. SteveBaker (talk) 18:54, 24 January 2010 (UTC)[reply]
Really, this is just a matter of different ways of thinking about the same thing. The ratio 14:4 is equivalent to the ratio 7:2, just as the fraction 14/4 is equivalent to the fraction 7/2. The value of the fraction as a number is 3.5 and the fraction can also be written as 3.5/1, just as the ratio can also be written as 3.5:1. But if you had the fraction 3.5/1, you would normally simplify it to just 3.5 (well, you might write 7/2 if you considered that simpler). Well, in the same way, the ratio 3.5:1 can be written as just 3.5. A ratio (of two nonzero terms) and a fraction -- or for that matter a quotient, like 7÷2 -- are really pretty much equivalent, and it's common to see a ratio expressed as a single number.
Incidentally, 7:2 is actually the way they write 7÷2 in many countries; they don't use what we call a division sign at all. --Anonymous, 19:01 UTC, January 24, 2010.
Your division sign ÷ is an Obelus. It is commonly seen today representing minus in Norway, for example in advertisements proclaiming『Opptil 30% på salgsvare』(= Up to 30% reduction on goods in sale). Pity the plight of little Norwegians who must use pocket calculators with buttons + - x ÷ while their math teacher teaches them to write + - . : for the same functions. With luck the little ones may grow up to be programmers who use + - * / respectively. Cuddlyable3 (talk) 22:20, 24 January 2010 (UTC)[reply]
Unfortunately the ratio article doesn't discuss this normalised format for expressing ratio; if this usage is as common as the above implies, then it clearly should. I did try to find a reliable source to back up this usage, but searching for "normalised ratio" and the like only finds specific ratios, rather than this general style of expressing as a ratio:1 and then omitting the :1 -- Finlay McWalter • Talk19:10, 24 January 2010 (UTC)[reply]
Yes, any number can be a ratio. Ratios don't, as you say in your original question, denote any kind of relationship between the two numbers. "The ratio of X to Y is A:B" means "For every A of X you have B of Y". It's a relationship between X and Y, not between A and B. --Tango (talk) 19:37, 24 January 2010 (UTC)[reply]
I suppose it is, but the fact that a particular (ordered) pair of numbers happens to be the ratio of something isn't very interesting. For any pair of numbers you will be able to find infinitely many things that it is the ratio of. The fact that the ratio of a particular thing is some pair of numbers is far more interesting. --Tango (talk) 20:01, 24 January 2010 (UTC)[reply]
I have a feeling you are on a topic far removed from this page and this question, and from which you already bid farewell. There's no sense confusing the OP here because of something unrelated. --Neptunerover (talk) 21:12, 24 January 2010 (UTC)[reply]
Thank you all. I understand the protocol that has emitted the ":1" when something is called a "ratio" but is expressed as a single number. I am sure, after another read or two, I will also understand the point about A of X and B of Y. Bielle (talk) 19:44, 24 January 2010 (UTC)[reply]
It would probably be clearer if I didn't state it so generally and instead gave an example. "The ratio of boys to girls in the class is 3:2" means "For every 3 boys there are 2 girls". --Tango (talk) 20:01, 24 January 2010 (UTC)[reply]
I expect to see two numbers in a ratio, even if the divisor is one. There should be an antecedent and a consequent. A number, by itself, is not a ratio. Saying "The ratio is 5.3" is unnecessarily confusing. How hard is it to say "The ratio is 5.3:1?" As a college teacher, or as a journal editor, I would have questioned such a usage. Edison (talk) 04:35, 25 January 2010 (UTC)[reply]
Well, what one expects and what actually happens are often two very different things! It is very common to drop the ":1", whether we like it or not. --Tango (talk) 06:08, 25 January 2010 (UTC)[reply]
When ":1" is omitted, we are using a factor (as in multiple), not a ratio, but the usage seems to be widely abused. Do scientific journals really say "cost-benefit ratio" when they mean "cost-benefit factor", or is it just second-hand reporting that makes the error? Dbfirs15:38, 25 January 2010 (UTC)[reply]
I've never heard anyone say "cost-benefit factor". I think we just have to accept that this is a meaning of the word "ratio". The English language is defined entirely by how it is used. --Tango (talk) 20:44, 25 January 2010 (UTC)[reply]
Yes, I agree I've only ever heard "ratio", but then I would expect, like Edison, to see a ratio. I suppose we have to accept that the "to one" is just understood in the context. I've made a few minor edits to our article on Ratio, but it really needs a major re-write. Dbfirs14:17, 26 January 2010 (UTC)[reply]
Is there any indication of use of Enoxaparin sodium in aortic dissection? Maybe it prevents the formation of thrombi in the false lumen (thrombi could migrate and induce arteries occlusion in brain, coronaries ...) or what else? Or Enoxaparin sodium just aggravates dissection by inhibiting coagulation? Thansk so much for replies. --62.98.29.51 (talk) 21:40, 24 January 2010 (UTC)[reply]
I've just checked the article on enoxaparin sodium -- it says that this stuff is indicated for prevention of blood clots during dialysis and abdominal and orthopedic surgery and for treatment of deep vein thrombosis and some kinds of heart attack. Nothing at all about aortic dissection or any other kind of open-heart surgical procedure. I'm not an expert on surgery, but my guess is that it would be contraindicated for open-heart surgery because it could aggravate bleeding and possibly cause a dangerous hemorrhage. Clear skies to you 24.23.197.43 (talk) 03:37, 25 January 2010 (UTC)[reply]
Speaking of which, I should retract part of my answer — according to the article, surgery is not always the treatment for aortic dissection. It depends on the details. Not that I think anyone's going to say: Doc, I have to have surgery! Some guy on the refdesk said so! But you never know. --Trovatore (talk) 08:05, 25 January 2010 (UTC)[reply]
Sorry, I really thought aortic dissection was a procedure where they open up the aorta to take out some kind of blockage and then sew it shut again. (Well, I told y'all that I'm not a medical expert!) Anyway, now that we all know what aortic dissection really is, I can say with certainty that enoxaparin sodium would ABSOLUTELY, DEFINITELY be contraindicated in that case cause all it would do is to make you bleed out faster. See, my answer was right after all, even though it was for all the wrong reasons! 146.74.230.82 (talk) 01:09, 26 January 2010 (UTC)[reply]
Of course, my reference to 'Colorado' seagulls may be irrelevant, as who knows when the species may have last seen an ocean. Where I saw them just happened to be at the dump as well. I suppose inland seagulls have lakes instead of oceans, where they might very well stay, if it weren't for the local dump. --Neptunerover (talk) 05:44, 25 January 2010 (UTC)[reply]
I can testify to them congregating around lakes, and not just seas. Here in Vermont we have quite a few near Lake Champlain and at least a good 10 or so miles in the parking lot at my workplace. Dismas|(talk)11:56, 25 January 2010 (UTC)[reply]
As far as I know (and to echo Dismas), gulls will hang around/breed near lakes, inland seas and areas of marshland too, without human encouragement. If I'm remembering correctly, there are huge colonies to be found inland in Central Asia in these habitats. Gulls, being the tough, adaptable little generalists that they are, don't strictly *need* to be around accumulations of water in order to eke out a living - but they seem to be 'drawn' to it. --Kurt Shaped Box (talk) 19:57, 25 January 2010 (UTC)[reply]
I was thinking about this on my morning commute and I think that Life After People mentions what would (will?) become of gulls. Yep, just checked the article and it says that there is a large die-off but that populations come back once fish populations start to rebound. Dismas|(talk)20:15, 25 January 2010 (UTC)[reply]
January 25
why is THF called THF?
It seems to me that you're adding TWO equivalents of hydrogen across the furan ring... not four. Shouldn't it be called dihydrofuran? Shouldn't the current (2,3) dihydrofuran be called (mono)hydrofuran? I mean, I don't think you can add more than one H2 molecule across a double bond... John Riemann Soong (talk) 06:17, 25 January 2010 (UTC)[reply]
Two equivalents of dihydrogen (H2) are added. The "hydro" means "a hydrogen atom", not "the molecular form of that element". Like hydrohalogenation, hydroformylation, etc., each add "one hydrogen atom, one other thing". But the real whyisbecause, just like the answer to any "why is some standard used". Something had to be agreed, and even if it is completely nonsystematic and makes no sense to anyone, it is how it is, and asking "why" doesn't lead anywhere useful (though in this case it sort-of does). [16]DMacks (talk) 06:47, 25 January 2010 (UTC)[reply]
name of those fenced-in forests of powerlines and insulators etc?
Do you know the places I mean? What are they called?
As an aside, there are some studies out there saying that women are not "born with all the eggs they will ever use", but continue to produce eggs after they are born. I'm not sure if that has been conclusively proved or not, though. Clear skies 146.74.230.82 (talk) 01:20, 26 January 2010 (UTC)[reply]
Circadian rhythm studies
Hi,
I was told that many early studies into human circadian rhythms had not been careful enough about letting outisde light in, and this screwed up their results. Does anyone know any examples and can lead me to a paper or 2?
I'm not really familiar with that objection. In the 1930s Nathaniel Kleitman was already conducting isolation experiments in caves in Kentucky, which would seem to give pretty good control. He had also conducted other isolation experiments as far back as the 1920s that might not have been as convincing, but I don't know much about them. He published a book called Sleep and Wakefulness in 1939 that summarized his findings, but I haven't read it. Looie496 (talk) 19:15, 25 January 2010 (UTC)[reply]
wind turbine generator manufactures
I have patented a "Electric Power Train" this is for generating electricity from one of the forces (pressure)generated from automotive/railway traffic on road and rail.What I am looking for is someone who could give me the specks on the genrator/alternator being used on wind turbines at present.To name a few speck's I am looking for are how much force is needed to turn the shaft without the blades,what RPM is required to get the best results,I know you will be asking me what size generator or how much electrisity do I want to generate.I cannot say at this stage,but I do want a medium to large,For example one of wind turbine being used on the wind farm's,that will give me a good start and something to work from.If I could get contact details of a manufacture that would be good.I am based in the UK so one as neer as possible would be great. Thanks Pierre —Preceding unsigned comment added by 86.163.87.199 (talk) 15:23, 25 January 2010 (UTC)[reply]
If your plan is to mount the wind turbine on the car or train, you will be wasting more energy than you are creating by adding drag and decreasing fuel efficiency. You would do better to simply tap off the engine power directly with an alternator. This is already commonplace. If your plan is to mount the generator near the roadway or railway to collect wind from passing trains or cars, I think you will find that the amount of extractable energy is not cost effective (it will probably be darn near zero watts). In specific answer to your questions, there is no way we can answer details about force, torque, and RPM, unless you tell us your desired specifications. Perhaps you might take a look at wind power, which gives an encyclopedic overview of present technologies. If you're unfamiliar with engineering design in general, it may be worth reading up on that before you start a major venture and contracting manufacturers. Nimur (talk) 17:08, 25 January 2010 (UTC)[reply]
How did you get your patent without specifications? Perhaps I don't understand how you propose to generate your power. What pressure force are you planning to use? Here [17] is a manufacturer of small turbines who might be able to help you. Dbfirs17:36, 25 January 2010 (UTC)[reply]
What country have you patented your invention in, and what is the patent number? Or did you mean simply "invented" or "thought up an idea?" Edison (talk) 21:26, 25 January 2010 (UTC)[reply]
That would produce even less energy! Really, though, the OP specifically said that he/she wanted to use a wind turbine, so we can safely assume that he/she is planning to harness the boundary layer created by passing cars/trains. (Oops, sorry, I just looked, the OP is definitely a he, based on his name.) Not that it would be any more cost efficient. And another objection to the OP's proposal: if he wants to use a wind turbine of a comparable size to the ones used on a wind farm, then (1) there won't be enough roadside/trackside space where to put it, (2) if the turbine is to be mounted low enough to catch the slipstream, then the blades will strike the ground, and (3) even if the turbine was somehow mounted low enough, only the very tips of the turbine blades will ever be exposed to the slipstream -- the rest of the blade will remain idle! This is clearly an impossible and even borderline ludicrous proposal, and I'm very astonished that the UK patent office has issued a patent for this contraption. Clear skies 146.74.230.82 (talk) 01:37, 26 January 2010 (UTC)[reply]
To be fair to Pierre, during the last year or so I have read in New Scientist magazine of schemes to recover energy from the pressure of foot or vehicular traffic on walkways and roadways, as Cuddlyable3 surmises, and I believe a couple of experimental setups are or have been trialled, though I can't find anything from hasty googling. One criticism of such schemes is that most of the energy they would recover would be extra energy that the person or vehicle would have to expend to negotiate such a surface, which otherwise would not be required: thus, they would in effect be using the vehicle's engine or the person's muscles as the generators and recovering the extra energy rather inefficiently.
It may be that Pierre only wants the specifications ("specs", not "specks," Pierre!) for wind turbine generators in order to crunch some comparative numbers - I can't see how such machinery could be repurposed for surface energy recovery if that's the idea, though the specification in his Patent application should make everything clear - could we have the Patent Office and Application number please, Pierre? 87.81.230.195 (talk) 03:02, 26 January 2010 (UTC)[reply]
For the second part of your question: Nobody has made any kind of holographic television yet... and even if you had one, it's not like all of your 2D television would suddenly be 3D. The signal just does not carry that information most of the time.
That being said, see 3D television. There are apparently a number of stereoscopic TVs (you wear funny glasses like in the movies) expected to hit the market this year, and ESPN is apparently starting the first full-time 3D channel, or something along those lines. These are not holographic—they are 3D in the same sense as a 3D movie. You can't look around at every angle, they just provide a little parallax.
He probably said it last time Mr Loughlin asked about them.
Ithink what Loughlin is describing is a type of Lenticular display, Where each hemisphere/pixel shows a different color depending on the angle it's viewed. Certainly this idea has been thought of. (Everyone working on 3d displays thinks of this idea.) But it's just not practical. (Consider the number of pixels needed, multiplied against the number of angles each pixel could be viewed!) All that said, the technology is just now within grasp. Barely. I saw one at SIGGRAPH 09. It looked very primitive, but it was actually using a tremendous amount of computing power, and very expensive display elements to maintain the illusion. (If I recall correctly, it also had a serious overheating problem.)
To get a hologram you are going to have to control the phase of waves between the pixels, and to get a wide angle view, your pixels will have to half a wavelength or less. This will be of order of a megapixel per square millimeter, or about a terapixel for a square meter display. The information required is more because you need phase as well as brightness for each pixel, to get an uncompressed TV picture you will need around a petabyte per second of data. Graeme Bartlett (talk) 00:10, 26 January 2010 (UTC)[reply]
We have to be very careful to define what we mean by a 3D display. They come in roughly four kinds:
Single viewer (you have to be sitting in the right place) - hence a very limited view direction - but no special glasses needed. Lenticular displays are like this.
Multiple viewers - but all of whom get the same view - with special glasses (that's what you get in a 3D movie or using red/cyan glasses or a head-mounted display).
Multiple viewers in multiple locations - all getting the correct view for where they are standing without glasses or anything. Holograms are pretty much it.
Multiple viewers in multiple locations - all getting the correct view for where they are standing...but with one horrible drawback (the kind of thing our OP is describing, bubble tanks, spinning grids of LED's, vibrating mirror displays, etc, ad nauseum).
The problem with the OP's idea is that you can't control transparency. You can't stop light from the back of the object from shining through to the front - or from the left through to the right - and vice-versa. So everything looks ghostly. You can't ever display a realistic picture - period.
So - we're back with holograms - which are still ruinously expensive to generate in realtime. But we're getting there. Graeme is technically correct about needing a petabyte per second to broadcast raw volumetric data at hologram densities - but that's not the plan. You can send (for example) octree-encoded data about the shape of the objects and use on-the-fly wavefront reconstruction to generate the hologram. That blows away the bandwidth issues (well, relative to a petabyte per second at least!) - and shifts it into doing crazy high numbers of calculations. But that's actually more do-able. So I think it's possible that we'll see animated, interactive true holographic 3D displays in our lifetimes - but it's not certain.
Bottom line then: We're stuck with glasses until we get crazy amounts of CPU time...and sadly, the OP's idea isn't gonna cut it. Vibrating or spinning mirror displays can do the same job better, cheaper and much more easily. SteveBaker (talk) 01:50, 26 January 2010 (UTC)[reply]
I would dispute the transparency claim, the hemisphere has an opaque flat side with a pinhole, it would be like looking through a tiny hole in a fence from all angles, except there could be a lot of them, too small to see. I think opacity would occur, but the other practical problems including data rates are grim. —Preceding unsigned comment added by Trevor Loughlin (talk • contribs) 03:50, 26 January 2010 (UTC)[reply]
I really think you're describing something similar to the gCubik device I mentioned above. It worked on little hemispheres. It looked like a toy, and had serious problems, but it pushed the limit of modern technology.
Incidentally, I think you would have really enjoyed the "Emerging technologies" section of the SIGGRAPH 09 show. Besides the gCubic, there was this, which is very similar to what you described last time you asked. However, there's still nothing even close to the quality that you described the first time you asked.
I had a question about the voltage divider article, specifically the derivation of the formula V_out=V_in*R_2/(R_1+R_2). I see that V_in should be I(R_1+R_2), and that therefore the potential after the first resistor is IR_2. But when a path for the output voltage is provided, why should the current running through the first and second resistors be the same? —Preceding unsigned comment added by 173.179.59.66 (talk) 19:18, 25 January 2010 (UTC)[reply]
By definition if R1 and R2 are in series, the same current flows through them. The formula is for ideal conditions, and does not assume any of the current through R1 flows through a physical voltmeter instead of R2. In practice a modern digital voltmeter has an input resistance of perhaps 6 megohms. Older cheap analog voltmeters could load down very high resistance circuits and affect the measured voltage appreciably. Whatever the input resistance of the voltmeter, it could be modelled as a parallel resistor across R2. If R2 has less than 1/100 of the resistance of the voltmeter, then the voltage would be off by less than 1%. A Potentiometer (measuring instrument) (in the older sense, rather than a variable resistor in the modern usage of the term) can be used to measure voltage without extracting any current once the adjustment is complete, by having a very sensitive galvanometer between the measures point and a known voltage, with the known voltage adjusted until no current flows through the galvanometer. Edison (talk) 20:46, 25 January 2010 (UTC)[reply]
Our theories tell us the minimum mass of a brown dwarf and the observations of Upsilon Andromedae give estimates of the masses of the planets, and they are well below the brown dwarf threshold. Our article only gives lower bounds for the masses of the planets for some reason, but upper bounds will also be known. --Tango (talk) 22:11, 25 January 2010 (UTC)[reply]
Not necessarily, observations of gravitationally induced wiggling generally constrain the product M*sin i, where M is the mass and i is the inclination of the orbit. So you get a lower bound if the orbit is perfectly aligned for our viewing and sin i = 1, but it is unbounded in the upper limit since the planetary orbit might be directly skew to what we hope to observe. And there is no direct way to constrain i from wiggling alone (usually). You'd need to follow up gravitational detection with some other method to find an upper bound and that hasn't yet been done in many cases. Dragons flight (talk) 22:50, 25 January 2010 (UTC)[reply]
If there is just the one planet, then that's true. In this case, it's a whole system of planets and the interactions between them put constraints on the inclinations. The article mentions this. --Tango (talk) 23:40, 25 January 2010 (UTC)[reply]
Try it with something like lego blocks. The first law says that nothing is created or destroyed, it only changes form. Any legos you use can't be used to build something else. If all of your legos are part of a house, and you want to build a car, you need to take some legos from the house. Legos are thus, conserved. The second law says that things just become messier unless you do something to clean it up. Hence, the legos don't pick themselves up! The room would just get messier and messier unless you spend some time to pick up the legos and put them away. However, time spent putting legos away means you can't do something else during that time. So you can't get something for nothing. Either the room gets to messy to play in, so you can't play with anything because its a complete mess, OR you spend time cleaning it up, and then you don't have any more time to play. Either way you can't play all that you want. Entropy is a mean bitch that way. The third law is a bit tougher, but basically it's the cabinet where you put your toys away. The third law simply tells you where all the toys go when you pick up the room. Or, as someone eloquently put it to me:
The first law says you can't win or lose, you can only tie.
The second law says that you can't even tie, you can only lose.
I like the idea of a Lego analogy - but I think we could do better (and list all four laws):
0) If I have six lego bricks and you have six lego bricks and your best friend has the same number of bricks as you - then she also has the same number of bricks as me.
1) You only have just so many bricks. No matter what you build or how you put them together, there are always exactly the same number of bricks. Even if you lose bricks down the back of the sofa or your dog eats some - the bricks still exist...somewhere!
2) If you make a nice tidy pile of lego bricks - carefully arranged by size and color - then if someone shakes them up - they never get any tidier. It takes a lot of work to make a tidy pile of lego bricks - but hardly any effort for your little sister to mess them up again.
4)3) If you had a small box that was only just big enough to fit all of the lego bricks inside - they'd have to be really, really tidy to fit inside! If you jumble them all up - they wouldn't fit properly.
I don't see the point in teaching such abstract concepts. Small children should be encouraged to be inquisitive of knowledge, appreciative of nature, and skeptical of any claims. 66.65.139.33 (talk) 02:24, 26 January 2010 (UTC)[reply]
Probably not. Remember that if it worked that way, someone before you would have thought of it. Plus, intestinal flora (of which E. Coli is but one part) produce prodigious amounts of CO2 during the ethanol producing process. So, anything which could produce enough ethanol in your gut to make you drunk would probably also produce enough gas to make you painfully crampy and bloated to the point that being drunk wouldn't be worth it. If you REALLY want to make booze and don't care much about the enjoyment of drinking itself, then it's just best to let the fermentation go on outside of your body. See pruno for a simple recipe. --Jayron3221:23, 25 January 2010 (UTC)[reply]
Wouldn't that just mean I would fart a lot? For why it's not been thought of yet (or why it's not popular), people usually don't eat pure fiber. And other sugars would be digested before it could get processed into ethanol.
In theory, I suppose an alcohol enema would work. But the alcohol would hit the bloodstream fairly directly, I reckon, and you wouldn't have the safety of gradual absorption or vomiting to prevent acute alcohol poisoning. Much safer and more pleasant to just drink it. Brammers (talk) 21:40, 25 January 2010 (UTC)[reply]
The kind of E.coli that you got inside your azz do not digest cellulose, as far as I know. That said, there are some mutant / genetically engineered strains of E.coli that do convert cellulose to ethanol -- I've studied those firsthand for the oil company's cellulosic ethanol project that never got past the lab studies stage. You really wouldn't want to drink the product, though, because of the high concentration of fusel oil -- not unless you wanna get really drunk really quick and don't give a dam about the horrible taste or any tummyaches you might get later. You can burn the stuff in a car engine, though, but it won't be cost-effective in the current energy market. Clear skies 146.74.230.82 (talk) 01:49, 26 January 2010 (UTC)[reply]
If there were bacteria capable of efficiently digesting cellulose, why wouldn't they very quickly reduce all trees, woods, grasses into a bubbly slime? 95.115.188.228 (talk) 07:59, 26 January 2010 (UTC)[reply]
IsIndonesia part of Eurasian plate or Australian plate. Since Scotese map concludes indonesia will collide with Australia, but the map we have Eurasia in green shows indonesia is not in that county but in orange this shows Indonesia is part of Australian plate. how can Indonesia collide with Australia when the sense is like "taking a train to school" and "what you ate for lunch". This is strange when something inside a plate collides with something inside a plate. --209.129.85.4 (talk) 20:54, 25 January 2010 (UTC)[reply]
In fact there are some smaller plates involved (at least in some versions), most of Indonesia lies on the Sunda Plate, a tiny part near Aceh is on the Burma Plate while the eastern part is part of a complex mess of microplates. None of Indonesia is on the Australian Plate. However, the Sunda Plate is actively colliding with the Australian Plate at its eastern end. Mikenorton (talk) 21:48, 25 January 2010 (UTC)[reply]
how do I get rid of awful vibration artifact in my speaker setup?
Just to be clear that this isn't some "audiophile" mumbo-jumbo, I'm not speaking of some subtle effect that's bothering me on a subconscious level, I'm talking about a really clear, awful sound that's really as clear as day. The sound I'm talking about is this awful vibration sound that you usually get when you record something and for example yell into the microphone much louder than it can support. Problem is, I'm not playing anything that has that sound in it, and further, I am NOWHERE NEAR the limit of the speaker set up -- it could be way, way louder (WAY louder). So my question is: how do I get rid of that awful noise? Like, am I supposed to turn the line out (playing from a music device/my computer) down, or up, or almost completely up, etc. The setup is:
computer -> remote (with volume control) -> speaker system (with separate sound volume on the back, independent of the volume knob). Is there some way to set these to get the desired effect? THanks! —Preceding unsigned comment added by 84.153.202.229 (talk) 23:31, 25 January 2010 (UTC)[reply]
Your speakers are farting. Possible cause 1: you are over-driving them. From your description, this seems unlikely. Possible cause 2: one or more cones is physically damaged. The general cure for that is reconing them or replacing them entirely. To assist in the diagnosis, are you able to detach the speakers from the current setup & drive them from some other set-up (to see whether the problem stays with the speakers, or is associated with the PC/Remote setup?. And in any event, think yourself lucky. I've spent half an evening under my desk trying to get my PCs headphone socket working, with no joy :( --Tagishsimon(talk)23:38, 25 January 2010 (UTC)[reply]
The artifact you report might be clipping due to overdriving the system with too high an input. If you have a friend with an audio oscillator(signal generator) and an oscilloscope, it might be possible to input sine waves (pure tones) at varying frequencies and amplitudes and determine when the objectionable sound comes out of the speaker. If the recorded and played back sounds are free of clipping, then maybe the fault is somewhere between sound source, amp, and speaker. Perhaps the speakers are damaged, as mentioned above. Try borrowing and listening to good speakers, while keeping the volume below a level which would damage them. The square waves resulting from clipping can damage speakers. Edison (talk) 02:29, 26 January 2010 (UTC)[reply]
I've noticed I can get clipping (audio) on my headphones, plugged directly into the computer, if I have the computer's volume turned way down low and the volume on the media player turned up high... or was it the other way round? Anyway, worth considering that sort of internal clipping, whatever it is. 81.131.17.2 (talk) 11:16, 26 January 2010 (UTC)[reply]
January 26
Cloning question
Have we yet devised a theoretical method by which the memories and personality from the original might be restored/awakened in a clone? I know that there was some idea a while back of actual memories being encoded in genetic material but I don't know if that's been discredited now. —Preceding unsigned comment added by 95.148.105.150 (talk) 00:20, 26 January 2010 (UTC)[reply]
It sounds pretty fishy to me. Considering we don't really have a great understanding of the neurological basis of memory anyway, but the formation of memories is clearly somatic and not genetic, the idea that you could code memories in genes seems rather... unlikely. We'd need a far better understanding of how memory itself worked in the brain to begin with, much less a light-years superior understanding of the human genome. --Mr.98 (talk) 00:37, 26 January 2010 (UTC)[reply]
Aside from any other consideration - there is nowhere near enough 'space' in a DNA molecule to store that much memory. At best - each 'letter' of the DNA is one of C,T,G,A - two bits of information per base-pair. Human DNA has about 3x109 'letters' so it can store at best 6,000,000,000 bits - less than 1Gbyte. That's just pathetic! You can easily store more than that on a regular CD-ROM. My PC has five times that much main memory! And bear in mind that this DNA also has to contain enough information to construct our clone's entire body, to run it's biochemistry, to repair and regrow bits of the body that fail, etc. There is simply not enough space to store the memories of even a few days let alone a lifetime. So - a clone is no different than an identical twin - it would be born just like any other baby - grow, learn, experience the world and end up a very different person. Memories in the brain are retained over the long term as physical connections between neurons which change over time. The clone would have to have an exact duplicate of all of those neural connections - but that can't be because a clone has to be grown from a baby - and the baby clone's brain doesn't have enough space - enough cells to store an adult brains' worth of memories. So this is a complete and utter bust. There is no way to do this. SteveBaker (talk) 02:14, 26 January 2010 (UTC)[reply]
Though when you consider that ~30 billion memory-associated neurons in the cortices and hippocampus have 6,000,000,000 bits each, the capacity is not quite so pathetic. Each cell is terminally differentiated, so it doesn't actually need to contain enough information to construct our clone's entire body, just enough to code for the transcriptome of that particular neuron. How much genome variation (coding capacity) there is between neurons is currently unknown, but there are some suggestions that they could be quite significant and play a role in brain development and maintenance. The idea of genetic memory is a bust, of course, but not necessarily because of limited coding space. Rockpocket06:32, 26 January 2010 (UTC)[reply]
Oh, sure, memory could be stored using DNA (although there is no evidence to suggest it is and plenty to suggest otherwise), but that wouldn't help a clone. When you clone someone you only get to use one set of DNA, not one for each cell. --Tango (talk) 10:30, 26 January 2010 (UTC)[reply]
Yep - and that's why Rockpocket's answer is not relevant to this question. If our memories were routinely stored in DNA, consider how long it would take to retrieve one. Somehow, the brain would have to locate the right cell that contained the DNA where the answer was stored - then somehow duplicate the right section of that DNA and use that to provide the answer. How would the indexing mechanism work? How would we find the right molecule? No - the brain is a computing machine and the connectivity of the neural net is what stores information AND allows it to be retrieved so quickly. SteveBaker (talk) 13:54, 26 January 2010 (UTC)[reply]
You would need to use some kind of nano-tech duplication technology (which no-one has invented yet) and actually copy the body, including the brain. If you use a normal cloning technique it is, as Steve says, just like having an identical twin. --Tango (talk) 02:19, 26 January 2010 (UTC)[reply]
This is another form of Lamarckism, and has long been discredited save for some fringe scientists who keep trying to bring it back. It is futile. 66.65.139.33 (talk) 02:20, 26 January 2010 (UTC)[reply]
Such memory transfer is of course a popular device in Science Fiction, where it may be used to raise philosophical questions about the nature and continuity of identity and selfhood in addition to being a useful plot device. A recent example of the many novels, etc, exploiting the idea is John Scalzi's Old Man's War.87.81.230.195 (talk) 02:31, 26 January 2010 (UTC)[reply]
If by 'restored' you mean, copy the mind of the original into the clone? As Mr.98 says, our understanding of the brains memory (or even its 'programming') is not good enough. It seems an unlikely possibility. But, then so was flying etc. I would think ESP is more likely than Genetic memory. Not deriding your question, but the general concept (with a different mechanism) is also nicely addressed in the novel "To Your Scattered Bodies Go" by Philip Jose Farmer. Note I wrote this(slowly) while others were posting so it doesn't take into account all the erudite responses before me. --220.101.28.25 (talk) 02:44, 26 January 2010 (UTC)[reply]
Is there a pattern/schedule of the moon setting and rising like the sun? One night at around 7:00 PM, I happened to see the moon in a short distance from the horizon. On another night at around 7:00 pm, it was already at the "noon" position. --121.54.2.188 (talk) 00:55, 26 January 2010 (UTC)[reply]
Basically, it rises ~49 minutes later each time, because it is in orbit around the earth and the earth has to turn a bit farther than one day's worth to catch up. --Tardis (talk) 01:09, 26 January 2010 (UTC)[reply]
Not sure what you mean by "change faces". It only ever shows the same face to Earth, but not all parts of it are illuminated all the time. Re the "schedule", did you ever notice that a full moon always rises shortly after sunset? That's when its Earth face is getting maximum illumination from the Sun; but non-full moons rise at other times, when the Earth face is at some angle to the Sun. -- Jack of Oz ... speak! ... 02:54, 26 January 2010 (UTC)[reply]
If you are trying to understand what Jack is saying and struggling to work out why it works, try drawing a diagram, it can be very helpful. --Tango (talk) 03:18, 26 January 2010 (UTC)[reply]
A short answer is, when the moon is full it rises when the sun sets. Each day after that the moon rises later and later, and wanes, until it rises when the sun rises--the new moon. After that it appears as a crescent in the morning, setting soon after sunrise. Every day it rises later and later, and the waxes larger, until when full it once again rises when the sun sets. The article linked above will explain all this in more detail. Pfly (talk) 09:43, 26 January 2010 (UTC)[reply]
Small correction. A waxing crescent moon rises soon after the sun rises and sets soon after the sun sets. It is in the sky for most of the day, but not easily visible in daylight; it is most visible around dusk. A waning crescent moon rises shortly before sunrise and sets shortly before sunset. It is also in the sky for most of the day, but most easily visible around dawn. Gandalf61 (talk) 13:43, 26 January 2010 (UTC)[reply]
One of the commentators said that at least the pipe won't rust since the red bull can is made of aluminum. But would it only hasten the deterioration of the exhaust pipe by acting like a Sacrificial anode or something.
Looks like it's well away from the outlet manifold so heat (melting/softening) shouldn't be an issue. Looks like a good job actually, for temporary use. If the 'aluminum' acts as the anode it will corrode, not the steel pipe. If the pipe is mild steel the Sacrificial anode article under examples says "protection of voids in the glass lining of mild steel water heater tanks via use of magnesium or aluminum alloy anodes". Not 100% sure of this. Depends on exactly which dissimilar metals are involved 220.101.28.25 (talk) 11:08, 26 January 2010 (UTC)[reply]
Yeah, that's right. Aluminum has a much higher reduction potential than steel. So what will happen is the Aluminum will corode, and the iron will stop rusting. I have lost several good aluminum pots and pans when I made the mistake of keeping them in the same drawer as steel ones; when the steel ones started to rust, even a little bit, it caused the Aluminum pans to develop a nasty black film (aluminum oxide) which rubbed off on everything, and resisted washing off. I eventually ditched the pots, and learned to keep those materials in seperate locations. --Jayron3213:32, 26 January 2010 (UTC)[reply]
I've seen worse "fixes". My concern with this "fix" is that the connection between the can and the pipe doesn't look gas-tight - so in all likelyhood it's leaking nasty carbon monoxide into places where it can get sucked into the cabin. The vibration that's transmitted between the bucking/shaking engine and the fixed-to-the-frame tailpipe will find the weakest point. In a very short amount of time, the can will be bent enough it won't be a tight fit and then the occupants of the car will start losing brain cells to CO poisoning (although evidence suggests that this had already happened when they were considering the fix!) Also, there is scope for the can to melt - although it's hard to predict that without knowing a lot more about the vehicle. Exhaust pipes are made from heavy gauge steel - not thin aluminium. Car manufacturers would certainly use thin aluminium if they possibly could. The fact that they don't speaks volumes about the suitability for the job! This is the kind of botch that I'd certainly consider as a "get me to the nearest garage on a dark and stormy night" fix...but no more than that.
It's the 'invisible' fixes that are most worrying. When I bought my 1963 Mini, the previous owner had started to restore it - and had not understood that the pitch of the threads on the 'whitworth' bolts that British cars used back then is not the same as the thread pitch on US cars. Hence, when he replaced a nut or a bolt, he would - with 100% reliability - strip the threads. Of the 16 lug nuts holding the wheels onto the car, 8 were stripped in this way. One wheel had three out of four stripped - not one wheel had four good lug nuts! All of the bolts on all of the shock absorbers were stripped. His efforts to add seatbelts to a car that was manufactured without them (and without hard attachment points to which to add them) were...um...creative and exciting. SteveBaker (talk) 13:48, 26 January 2010 (UTC)[reply]
is this a valid question here?
Is this desk the proper place to ask a physics question? Is there perhaps a better place where physics discussions take place, such as the argument pages there are concerning mathematics? --Neptunerover (talk) 08:46, 26 January 2010 (UTC)[reply]
General Physics goes here, but Mathematical Physics (which looks just like Maths) goes on the Maths Desk, I would say. Dbfirs09:58, 26 January 2010 (UTC)[reply]
Okay then, my next question concerns the form of the question I want to ask, since I want to make sure I am not asking what would be an inappropriate question, no matter on which desk I ask it. I'm wishing to make a short statement that I consider valid, after which I'm hoping to be offered suggestions concerning my perceived validity of the statement, since I'm wondering if perhaps there might be things I am not taking into consideration. --Neptunerover (talk) 10:31, 26 January 2010 (UTC)[reply]
The intention of the Wikipedia Reference Desks is to respond to factual questions that can be answered by reference to Wikipedia articles, reliable sources outside of Wikipedia, or, occassionally, through the previous experience of individual editors. The reference desks are not intended to be a chatroom, a soapbox for promoting individual opinions, or a forum for debating controversial topics - see Wikipedia:Reference desk/Guidelines. Whether your question will meet these criteria or not depends upon the contents and context of your "short statement". Gandalf61 (talk) 11:16, 26 January 2010 (UTC)[reply]
If you want to know if your understanding of existing physics is correct, then ask away. If you want to ask if your own theory that you have come up with might be correct, then you'll need to go somewhere else. --Tango (talk) 12:57, 26 January 2010 (UTC)[reply]
Is this desk the proper place to ask a physics question? - Yes. Physics is science and this is the science reference desk and our job here is to answer questions.
Is there perhaps a better place where physics discussions take place, - Yes there are better places to hold discussions. Discussions (as in: general chit-chat) are not encouraged here - we're here to provide answers to specific questions. Sometimes we do get derailed into discussions but that's not really supposed to happen. So there is undoubtedly a better place (outside of Wikipedia) to hold discussions (as opposed to questions).
Refrigeration not supported at low ambient temperature
I've read the article on refrigerators which seems to confirm my understanding of how household fridges work. I've also searched the archive but couldn't find an answer to my query. I have a Smeg fridge (http://www.smegtech.com/site/smeg/pdf_libretti/914773907-GB.pdf) which is currently in an unheated garage. I wanted to use it for extra capacity around Xmas but, although it clearly had power (the interior light worked) there was no sign of the compressor(?) starting up. On checking the manual, I found that it is only designed to work if the ambient temperature is at least 16c. At the time it was probably about 2c.
Firstly, why is that? I'd have thought that it would assist the fridge in dissipating heat if the ambient temperature is cold. Would the refrigeration cycle not work properly or could some harm come to the device? Is it likely that the device has a cut-off so that it won't 'start-up' if the temperature is too cold? --Frumpo (talk) 11:02, 26 January 2010 (UTC)[reply]
That's a normal problem. The refrigerator requires outside warm air to evaporate the liquid that's flowing through it (when it evaporates, it cools), which will return to the refrigerator, be compressed by the pump, and absorb more heat (it's a cyclical thing). If the outside air temperature gets too low, it won't efficiently evaporate the gas, which effectively halts the cycle. See Vapor-compression refrigeration. If your refrigerator cuts out at 16c outside air temperature (which will quickly become inside air temperature), you will want to be very careful about what you eat from it - there are many foods that should not be stored at such a high temperature. Falconusptc12:44, 26 January 2010 (UTC)[reply]
If you garage is consistently around 2C over the xmas period, then you don't need a fridge - just put stuff in the garage as it is. If the garage spends a significant amount of time at temperatures between about 5C and 16C, then you have a problem - it's too warm to do without a fridge and too cold for the fridge to work. A lot of people keep extra fridges or chest freezers in their garages without problems, though, so I guess there are ones out there that can handle the low temperatures. Maybe you just need to get a different fridge. --Tango (talk) 12:55, 26 January 2010 (UTC)[reply]
Hall effect EEG?
Supposing a conventional EEG was taken using head electrodes. Would a powerful magnetic field around the subjects head, oscillating in a three dimensional raster pattern, alter the "focus" of all the electrodes in such a way as to vastly increase the spacial resolution down to the level of individual brain cells?Trevor Loughlin (talk) 13:58, 26 January 2010 (UTC)[reply]
Psychological reason for former students talking about how strict/tough teachers were
I was under the impression, and the article on memory seems to agree, that we remember mostly the good things. Obviously, people remember some negatives. Still, on a few alumni Facebook pages for American Junior High Schools, I notice former students, now in their 30s and 40s, talking more than usual (maybe 30-35% of posts) about teachers' discipline and how strict they were in 6-9th grade. My question is, why? Why are they choosing to discuss this when reminiscing?
I'm theorizing maybe it's how bad the students were; maybe not all the posters, but perhaps they're remembering some really rough kids but can't recall specifics on that - but they can recall teachers and how they handled it. While the ones I'm reading are from a city of 100,000 - not exactly a crime-riddled urban area - I'm sure the neighborhood plays a part.
It just seems strange that so much time is focused on negative thing, instead of different assignments, social activities, and so on; which are mentioned, but not as much. It especially seems strange because of the notion that "what's too painful to remember, we simpy choose to forget." (Okay, the line is fromt he song "The Way We Were," but you know what I mean.)209.244.187.155 (talk) 14:40, 26 January 2010 (UTC)[reply]
. That nice Mr Lorentz said that at some speed 'v', the mass of the object is it's rest mass multiplied by gamma...things get heavier as they are accellerated towards the speed of light. So if you know the rest mass and the speed - you can figure out the relativistic mass. Now, if v is exactly equal to c (ie, if the object is moving at exactly the speed of light) then v2/c2isexactly 1.0 - so gamma is one divided by the square root of zero...one over zero is either undefined (if you're a mathematician) or infinity (if you are a physicist) - so at exactly the speed of light, an object would become literally infinitely heavier than it was at rest. That means that it's mass would be literally bigger than the mass of the entire universe. That's not going to happen. However, we know that the photon does move at exactly the speed of light - and it doesn't have an infinite mass - it has a small but perfectly measurable relativistic mass while it's moving at the speed of light. So we can calculate the rest mass of the photon by dividing its relativistic mass by Lorentz's gamma factor. But if it's moving at the speed of light - then gamma is infinity and its rest mass is it's fairly small relativistic mass divided by infinity. Any number divided by infinity is...zero. So the rest mass of the photon MUST be precisely zero...not a teeny tiny bit above zero...it has to be EXACTLY zero. Now, when you say "it doesn't matter if it's a tiny bit above c" - you have to consider what you just said. If v is even the tiniest bit bigger than c then v2/c2 is just a hair bigger than 1.0 - but the number inside the square root of the lorentz transform is 1-v2/c2 - so that would be a negative number. The gamma factor would be one divided by the square root of a negative number...which is a complex number - and complex number never, EVER show up as real world quantities. Hence, speeds of even the most microscopic amount above c are proven to be clearly impossible by very basic arithmetic. It's not even something to discuss. SteveBaker (talk) 03:13, 23 January 2010 (UTC)[reply]
