Wikipedia:Reference desk/Archives/Science/2015 February 21

= February 21 =

Technical term for the rejection of Cholecystokinin (CCK) stimulation by gallbladder?
You know how diabetics either have an auto-immune disorder in which the person's own immune cells attack the insulin-producing cells in the pancreas (Type I diabetes) or insulin-resistance (Type II) diabetes? I am wondering if there is a same concept for the gallbladder. I don't think it's so far-fetched to think that the gallbladder can actually refuse to recognize the CCK, sent from the intestinal cells. Is there a known disorder that has to do with the inability of the gallbladder to recognize CCK? How would that affect the liver's ability to channel the bile to the small intestine or its communication with the gallbladder? SSS (talk) 04:05, 21 February 2015 (UTC)


 * Wikipedia has a putative article titled Gallbladder disease, but it's pretty dreadfull. It is nothing even approaching a complete article on the subject.  The article titled Gallbladder is more complete, but makes no mention of the disorder you note.  -- Jayron 32 03:39, 21 February 2015 (UTC)


 * Wow. That was fast. Another question: I signed my name with four tildes, and a bot treated me as if I didn't sign my name at all. Could it be the nickname/name thing? SSS (talk) 04:05, 21 February 2015 (UTC)


 * It looks like you set up your signature preferences incorrectly. When you set up your own formatted signature (which it looks like you did) rather than the default signature, be sure your user talk page is linked from your sig.  When you sign a post, the SineBot looks to see that your post contains a link to your User Talk page; if it doesn't it assumes you didn't sign.  This page has some guidance for you in how to properly customize your signature.  -- Jayron 32 03:49, 21 February 2015 (UTC)


 * A quick check of PubMed turned up, which says that cholecystokinin autoantibodies can be a result of autoimmune polyglandular syndrome type I. But the fault seems to be more at the autoimmunity level, with multiple hormones becoming neutralized.  Still, it results in a decrease in the number of CCK-producing cells in the intestine.  I'd expect some differences between this and diabetes since CCK is secreted to the lumen of the gut rather than remaining in circulation.  There's also a reference  that hints at but in no way provides evidence for an autoimmune role in the decrease of CCK production in bulimia nervosa. Wnt (talk) 16:10, 21 February 2015 (UTC)


 * Oh, cool. Thanks. It may be interesting to wonder about whether other aspects of bulimia nervosa causes the decrease of CCK production or that the decrease of CCK production contributes to bulimia nervosa. SSS (talk) 16:42, 21 February 2015 (UTC)

Is the computer a logical robot?
Is the computer being a logical robot and what did the computer doing the logical robot?--83.237.202.23 (talk) 05:24, 21 February 2015 (UTC)
 * I'm not sure I understand the nature of your question. Understanding the epistemology and ontology of computers is a complex issue.  The person best associated with these questions is perhaps Alan Turing, who not only looked at the nature of what a computer was, but also how computers and humans interact and what the nature of humanity was in relation to what computers can (and cannot) do.  For example, a Turing machine and the concept of Turing completeness are commonly used to define a machine as a "computer", as distinct from devices which may perform calculations or do other tasks for us, but which are not defined as computers (such as, say, an abacus).  A Turing machine is a hypothetical device designed to perform "thought experiments" about the nature of computers.  Turing is also famous for his insights into artificial intelligence, devising the Turing test which is commonly used as another thought experiment to determine if some machine is truly "intelligent".  If you're trying to understand the nature and philosophy of computers, Turing is your guy.-- Jayron 32 05:36, 21 February 2015 (UTC)
 * Another person who thought along these lines is the polymath John von Neumann, who like Turing also made important contributions to the early philosophy of "thinking machines" and "computing". He was working on a book titled The Computer and the Brain when he died; von Neumann's work in this area may also be useful for your research.  -- Jayron 32 05:42, 21 February 2015 (UTC)
 * Much thanks! I understood so, that the calculator not be a logical robot, because the calculator being none logical, but the computer did being a logical robot, so in what was being the main sign of logical, if the main sign of logic was being intellect?--83.237.215.8 (talk) 08:23, 21 February 2015 (UTC)
 * Maybe a sequence of actions (of computing) was being the main sign of logical?--83.237.212.20 (talk) 10:07, 21 February 2015 (UTC)
 * So, whether being the sequence of (applied) linguistics is logical?--83.237.212.20 (talk) 10:24, 21 February 2015 (UTC)
 * Maybe a phonetics is being determines the logical of sequence of linguistics?--83.237.196.132 (talk) 11:59, 21 February 2015 (UTC)
 * I’m thinking that a (logical) phonetically sequence was being forming a linguistics.--85.141.236.114 (talk) 16:40, 21 February 2015 (UTC)


 * Computers are logical in that they run computer programs using logical operators like "and" ""if" "not" then". Whether it is a robot depends on definition.  Obviously a laptop cannot build a car in a factory, and if you ask someone to draw a robot, you'll probably see a metallic man like C3PO or the Tin Woodsman.  But your laptop can play discs for you, and can be directed to direct the running of compatible household appliances, like lights and alarms and the lawn sprinkler. μηδείς (talk) 17:37, 21 February 2015 (UTC)


 * Robots are (at least, technically) just computers that are connected to motors and sensors so that they can make something 'physical' happen rather than just display stuff on screens or store things on disk drives. The term is getting gradually messed up by people who get confused about whether some radio controlled vehicles are "robots" (eg in "Robot Wars" where computers are rarely involved)...and in cases like drone aircraft where what happens is some kind of fusion between a robotic pilot handling the small details of the motion while some human "pilot" gives it higher level commands.


 * What distinguishes a "computer" from a calculator or some other piece of electronics is that computers are "programmable", you give them a list of commands and they go off and obey them all. Most people draw the line between computers and other electronic systems using the principle of equivalence to a "Turing Machine".   A turing machine is an abstract description of a very, very basic computer - and it can be shown (according to the Church-Turing thesis) that all computers that are equivalent to a turing machine are basically the same thing (although the details of how they operate and the amount of speed and memory they have will obviously differ).


 * Things start to blur when you look at something like a cellphone - which has multiple computers inside of it (the main "CPU", many little graphics processors, probably others in the networking hardware and so forth). It has a bunch of sensors (radios, touch screen, battery voltage and temperature, tilt, acceleration, cameras...I'm sure there are others) - it's more than just a computer, but not quite yet what we'd describe as a robot.


 * Other devices, like an inkjet printer are (arguably) robots because they contain motors and can move things around in the real world. Some people would argue that since a printer can't drive around the room - it's not a robot - but that kind of definition gets difficult when you think about industrial robots that are bolted firmly to the floor too.


 * All of these terms have varied over time, and will doubtless continue to do so. The term "computer" originally meant "a human being who is paid to perform arithmetical calculations"...and our modern computers were originally "automatic computers" to distinguish them from people.


 * But these days, a computer is a part of a robot - like the motors, sensors and batteries. Just like a brain isn't a human being and a human being isn't a brain.
 * SteveBaker (talk) 23:55, 21 February 2015 (UTC)
 * Thank you! I believe that all programming languages are always been the same linguistics, as usual linguistics.--83.237.203.228 (talk) 11:35, 23 February 2015 (UTC)
 * We could been assume that the phonetic sounds (phonetics) are always combining (consolidating) all linguistic groups of languages into a single linguistically phonetically family.--83.237.203.228 (talk) 11:52, 23 February 2015 (UTC)
 * It remains to be seen, had be the robotization of the speech(-ing) apparatus of human, or at soon be of a primate?--83.237.244.173 (talk) 13:05, 23 February 2015 (UTC)
 * Perhaps in ancient times, the first humans phonetically was been imitated animals, because the first humans speech(-ing) apparatus was been undeveloped (primitive), so that’s humanity had been invented(-ing) a phonetic alphabet. That’s why, did been the robotization of the speech(-ing) apparatus of human, or at soon be of a primate?--85.141.236.167 (talk) 15:46, 23 February 2015 (UTC)

distance to Venus and Mars at the present time
Can someone easily tell me the approximate distance from the Earth to Venus and the Earth to Mars, in AUs, as of today? (Mars must be close to 2.5AU, I think.) Bubba73 You talkin' to me? 05:56, 21 February 2015 (UTC)


 * Venus: 1.422 AU, Mars: 2.201 AU. You can find out by typing "distance to venus" into Wolfram Alpha.  --Bowlhover (talk) 06:26, 21 February 2015 (UTC)

Thank you for both answering the question and telling me how I can find out such things. Bubba73 You talkin' to me? 06:30, 21 February 2015 (UTC)
 * As a slight aside, Wolfram|Alpha's Astronomical and History databases are very good. For example, it can tell you the distance between Mars and Venus when Issac Newton was born. -- LongHairedFop (talk) 10:28, 21 February 2015 (UTC)

Technical reports
I am currently writing a technical report for an investigation I am carrying out in 2 parts. I have written an introduction and procedure but my advisor told me that I shouldn't start writing the analysis until I have results from parts 1 and 2. I think I can still write an analysis for part 1 only so why would my advisor say this? Do any experienced scientists have any advice? 90.194.63.41 (talk) 11:51, 21 February 2015 (UTC)
 * Your advisor is correct unless you have external funding. Nimur (talk) 16:27, 21 February 2015 (UTC)
 * In terms of the wider point, I don't think people will be able to provide more detailed help without more explaination. For example, if these 2 parts are highly linked, and it is expected that results between them would be related and you're likely to write about this in your analysis, then there may be good reason why you advisor is recommending this. Even more so if what you write about could be strongly influenced by the result of than the other. Or even if this isn't the case, if for example the second part is more uncertain or speculative and may not have results that are particularly interesting or useful, it may be you will need more followups on the first part, or at least to write more, if you don't have much to say about the second part. (Or conversely it may if you do get good results for the second part, the first part suddenly gets a lot less important or interesting, and you'd only want to write a small bit about it.) There are bound to be other reasons why your advisor, may feel it's better to only write the analysis later, beyond providing more information here, have you considered asking your advisor for more information on why they recommend to do it that way? If it's not an environment where it will be acceptable to challenge the suggestion, if they are an "advisor" I would hope they would at least be willing to offer some more explaination, since it's clear you're not satisfied with what you[ve been told so far. Even if the explaination is still unsatisfactory, perhaps it will help you in providing information when seeking advice from others. 17:16, 21 February 2015 (UTC)
 * That makes sense. They are linked, yes. The first part of the investigation is verified by the second part and so from the results of the first part, we can predict what the second part should be. If the second set of results aren't as expected, an explanation would need to be hypothesised.  What about the results?  Do you think I should wait until I have results for both parts until I start writing that as well? 90.194.63.41 (talk) 17:22, 21 February 2015 (UTC)

The Sound of Meteors
What conditions would be necessary in order to hear a meteor falling? I mean in general. I know I'm not going to be able to get exact figures. Dismas |(talk) 12:03, 21 February 2015 (UTC)


 * At what point in its descent? Most of them burn in the upper atmosphere, so they probably don't produce much noise. In contrast, there's the incident over Russia two or three years ago, and it produced an explosion. I don't recall reports of it making sound while flying through the air (except maybe the explosion). Maybe if you're close enough to hear it, you're toast anyway. ←Baseball Bugs What's up, Doc? carrots→ 13:17, 21 February 2015 (UTC)


 * Larger meteors will make more sound, and the closer you are the more likely you are to hear it.  Huge meteors which explode, like the Tunguska event, can be heard over the long distances.  Then there's the boom from those that survive to hit the ground or sea, making even more noise. StuRat (talk) 14:43, 21 February 2015 (UTC)


 * Don't forget also, meteors can create electrophonics. Anything near by the observer that acts like an half-wave dipole antenna may get stimulated by the low frequency radio waves generated by the plasmic trail and so produce an audio sound which can be  quite evident to those on the ground – long before the sonic sound from the meteor reaches them.--Aspro (talk) 17:38, 21 February 2015 (UTC)
 * This phenomena was noticed before the the sands of of recorded history started to run but only recently been understood. First in Britain and a few decades later in the US. Just found this: .--Aspro (talk) 22:29, 21 February 2015 (UTC)


 * You seem to have developed a stutter. :-) StuRat (talk) 23:16, 21 February 2015 (UTC)

Thanks for the link! And all the answers. Dismas |(talk) 14:24, 25 February 2015 (UTC)

Freezer energy use as a function of mass and insulation
I need to know how much energy it takes to keep 5 kg and 30 kg of water frozen and cooled to -2 ± 1 °C in a 300 liter (50 cm x 50 cm x 120 cm) freezer in a 22 °C room as a function of the freezer's insulation in terms of its thermal conductivity. Assume the freezer's door is never opened, everything but the temperature differential is in a steady state, and the compressor starts at -1.0 °C and stops at -3.0 °C. I need a formula for this, or a reference with tables derived empirically.

There are literally dozens of otherwise reputable web sites which suggest storing more food in a freezer takes less energy than storing less. This is utterly false, but in order to prove this, I need the thermodynamics formula. I am not interested in anecdotes of any kind, especially of the "heat capacity of food" of which there are several utterly incorrect examples in the WP:RDS archives. I am only interested in a formula or reference which describes the energy input for maintaining the thermodynamics of the temperature differential across the freezer's insulation. 184.96.139.187 (talk) 22:31, 21 February 2015 (UTC)


 * Why does the OP 'need' to know this? Is this a homework question?--Aspro (talk) 22:40, 21 February 2015 (UTC)


 * Because so many people have gotten it completely wrong, here and everywhere else on the internet, and I feel a very strong moral obligation to explain to them exactly why in incontrovertible mathematical terms. It is not homework, but if it were up to me it would be homework for every thermodynamics student until most people start getting it right. 184.96.139.187 (talk) 22:53, 21 February 2015 (UTC)


 * I've never heard anyone say that it costs less energy to run a full freezer than an empty one, but I have heard a full freezer will maintain it's temperature longer when the power goes out. StuRat (talk) 23:22, 21 February 2015 (UTC)


 * The reason for the difference in cost is that when you open an empty freezer a lot more cooled air is lost, which the freezer need to recoolen. If the freezer is full, much less air is lost. μηδείς (talk) 23:52, 21 February 2015 (UTC)


 * How many times would you have to open the door and completely replace ~300 liters of cold air with room temperature air to match the amount of heat that leaks across the insulation in a single hour? Frankly, you are completely wrong. 184.96.139.187 (talk) 01:29, 22 February 2015 (UTC)


 * ?!! The OP states “Assume the freezer's door is never opened” Water has a Specific Heat of about 2 at -10°C  (kcal/kg°C). And it is H20. Therefore, it will be absorbing long wave infra- red radiation (which just passes through the foam polyurethane insulation like it isn't there) far more readily than pure “air”. Thus a freezer full of 'ice' without the door being open will use more energy. It is basic physics.--Aspro (talk) 00:24, 22 February 2015 (UTC)


 * Why do you say that foam isn't opaque to infrared radiation? That seems absurd to me. 184.96.139.187 (talk) 01:29, 22 February 2015 (UTC)


 * Said the opposite. Read it again.--Aspro (talk) 17:57, 22 February 2015 (UTC)


 * I read "long wave infra-red radiation (which just passes through the foam polyurethane insulation like it isn't there)" to mean insulation is ineffective against long wave IR. This was surprising to me, too.  Is that what you meant to say ? StuRat (talk) 18:01, 22 February 2015 (UTC)


 * `Yes, that is what I meant. Had a quick google but could not find any long wave images in the public domain. Very long wave scanners are (as far as I know) are not even available to the military  yet (they are a hassle and need cooling and a tech to keep them working) but a house become transparent at those wavelengths. One can see through the walls,  central heating pipes, radiators, fridges and everything etc. That thermal radiation (which appear white, yellow, and red  on the screens) is absorbed by food stuffs – more readily  than bricks and mortar. Blue electromagnetic radiation has a lot more energy than red – but the red is continuous – night and day. The ground (terraferma )   even gives it off. It may only be a watt and a half  per square  meter per second but over 24 hours it all adds up. That is why cold stores to day  are so large. Just doubling the surface area increases the volume 8 fold. Look in your modern fridge and is has expanded polyurethane foam. It main insulating property is poor convection and conductivity but longer (not short) infra red just passes through like it isn't there--Aspro (talk) 19:52, 22 February 2015 (UTC)


 * I think you meant doubling the linear dimension increases the volume by a factor of 8. Doubling the area increases volume by a factor of the square root of eight.     D b f i r s   21:18, 22 February 2015 (UTC)


 * Yes, he made a grave mistake. :-) StuRat (talk) 00:05, 24 February 2015 (UTC)


 * Relevant is blackbody radiation. Every object which is not at absolute zero is always losing energy radiatively.  The second law of thermodynamics is a mean bitch.  -- Jayron 32 01:39, 22 February 2015 (UTC)


 * I agree with Medeis that a full freezer spills out less cold air than an empty one - which certainly suggests that the full freezer is more efficient. That's probably a marginal difference in the case of a 'chest' freezer where the higher density of the cold air causes it to tend to remain inside the chest rather than spilling out as it undoubtedly does with an upright freezer.  Our freezer is a pull-out tray at the bottom of our refrigerator - and that's probably somewhere between the two in terms of partially-loaded efficiency.  And of course, everything depends on how often you open the door, and for how long.


 * It's also true that when you initially fill the freezer, it's going to take more energy to cool down a full freezer than a largely empty one - the heat capacity of food is certainly going to be higher than air. So there are more unknowns there too.


 * But if you want a simplistic, quick answer, then I think the air-spilling-out-when-door-is-opened argument wins...and that's why it's so often quoted. But in the idealised world of spherical-cow physics, when the freezer is in steady-state and the door is never opened - it shouldn't matter how full it is.


 * The problem here is that our OP is asking for information about an idealized freezer (door never opened) in order to debunk all of the advice out there which is clearly discussing realistic freezers where the door gets opened a few times a day. These are NOT comparable situations.


 * SteveBaker (talk) 01:43, 22 February 2015 (UTC)


 * “when the freezer is in steady-state and the door is never opened - it shouldn't matter how full it is.”
 * The ability to absorb heat does matter. Dry cold air in a fridge does not absorb anything like that same amount of long wave infra red thermal radiation that food stuffs do That is why a cold store (with cold store workers going in and out all day long) full  of (say) Dates require less energy to maintain that storage temperature  than (say) candy. See:.  Cold dry air even less so, as it is mostly nitrogen and 21% oxygen. So on this point the OP is correct, in so much that what we are being told is nonsense. This, I think, is the point he is trying to get across. We are on the Ref Desk and so should be able to disassociate ourselves from repeating the 'full fridge' mantra and as the OP suggests we (and every thermodynamics student) should be able to get this  right! This is why I thought is was a homework question. It takes energy to keep mass cool. More the mass the greater the need of cooling. As I said above... It is basic physics!--Aspro (talk) 18:32, 22 February 2015 (UTC)


 * As far as I can tell no one claims that a never-opened freezer is more efficient when full, so there's no point debunking that. What people do claim is that a frequently-opened freezer is more efficient when full. For example this .ca.gov page says "If your refrigerator is nearly empty, store water-filled containers inside. The mass of cold items will enable the refrigerator to recover more quickly after the door has been opened." -- BenRG (talk) 05:56, 23 February 2015 (UTC)
 * That is a perfect example of the total bullshit that pervades the internet discussions of the topic. You are trying to keep a mass colder than the ambient temperature. Unless the insulation is perfect, the larger the mass means that you have to spend more energy maintaining the temperature difference. 184.96.139.187 (talk) 01:13, 24 February 2015 (UTC)


 * For a closed freezer, the energy leakage via thermal conduction may be modeled by: $$E = k {A \over l} \Delta T$$ where k is the effective thermal conductivity of the freezer walls, A is the area of the walls, l is the thickness of those walls and ΔT is the temperature difference between the outside and the inside. At steady state, the energy loss is independent of the contents of the freezer.  So as long as the freezer remains closed and there are no other mechanisms for energy transfer, the contents of the freezer don't matter.  Achieving a constant internal temperature simply requires balancing the losses due to thermal conductivity.  A full freezer has a much larger heat capacity than an empty freezer, so you will expend much more energy reaching that steady state, but the incremental effort to keep it there is the same regardless of the freezer contents.  Of course if you are going to consider opening and closing the door, that is a whole different issue.  Dragons flight (talk) 06:49, 24 February 2015 (UTC)


 * No! This I think is what the OP is trying to point out. Substances with low specific heat absorb less of the long wave thermal radiation than some other substances. So a completely empty freezer whose doors don't open requires less energy than a fridge that is full with anything – other than perhaps exotic stuff that is also  as transparent as air . And I bet  you wont find many fridges in your neighbourhood with those substances being stored.  The manufactures repeating this mantra are - I think-  attempting to say that be having a bit of cold mass already present enables them to claim that their fridge meets regulations (re: cooling capacity per 24 hours). That is nothing to do with energy consumption. Reminds me of that report on the radio some years back where a housewife  had her house raided by the police. On  hearing the mantra  that one should not have a empty fridge, she  placed  large plastic bags of her lawn clippings into her chest freezer (in early summer, her lawn clipping where readily available in bulk). It was not the lest a bit funny to find out that a jobs-worth had  overheard her telling a friend about this. So she got raided on a his tip-off  as  she was hiding a load  of grass in her freezer. It was explained to her that this excuse was silly and she ought to plead guilty – (be amazed... this persisted until the  lab report came in – on lawn clippings can you belive!) .  So this full fridge mantra (as the OP is indicating) is total utter nonsense.--Aspro (talk) 19:01, 24 February 2015 (UTC)


 * Where are you getting the long-wave thermal? If it is internal to the freezer, then it makes no difference at all in the steady state condition (where the premise is you already have a uniform internal temperature).  If you are talking about thermal radiation penetrating the closed freezer from outside, then I don't see that as being likely to be more than negligible.  I don't see how long-wave thermal makes a difference to a closed, steady-state freezer.  Dragons flight (talk) 19:56, 24 February 2015 (UTC)