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November 1

do soundcards produce voltages below 0

if I make a sine wave in, say, Audacity, and play it, is the voltage on the soundcard's output, is it a sine line centered on the soundcrad's ground or does it lie completely above it (i.e. is there a DC component)? and if I wanted to amplify the signal using an opamp in the inverting config, what should the (+) terminal of the opamp go to to keep the signal from clipping, the ground or a voltage divider? can it go to ground if the signal is capacitor-coupled (which should remove the DC component anyway)? Thank you in advance and sorry if the questions are dumb Asmrulz (talk) 01:13, 1 November 2014 (UTC)

This is a very reasonable question!

The answer is complicated. Voltage is always measured relative to a reference. So the question you are implicitly asking is whether any sound-cards produce a negative voltage relative to some standard reference point - most probably, the main system's ground plane (or chassis, or case, or the grounded power supply safety ... or whatever). The answer is "almost certainly" yes: some system somewhere does so.

But, this is uncommon on personal-computer hardware. Most audio output amplifiers that are built into computers will produce a signal whose dc level is at or above the system ground. This kind of digital-to-analog output signal is easier to generate.

Some audio amplifiers have a floating ground. Those amplifiers are susceptible to popping, clicking, and other turn-on/turn-off transients.

If you're connecting your soundcard's audio output to a secondary amplifier, you need to look up your card's nominal output voltage and impedance. We can probably help track that kind of thing down if you know your audio card model.

For example: here's the data sheet for the Realtek ALC850, a "top of the line" AC97 audio DSP and analog output chip (this is the sort of thing that used to be soldered onto motherboards, in the era after soundcards were plug-in peripherals, but before they were built into the main logic board's chipset, i.e. before analog audio was commonly built into the silicon of the system's "south bridge" or its modern equivalent). As you can see, the analog input can be whatever you want (within reason); but the DAC output will be scaled between ground and V_DD. Unlike the amp you'd find in a really old dinosaur hi-fi system's audio system, there is definitely not a negative voltage rail.

Keep in mind that PC audio output is usually driving a headphone or a separately-powered speaker-amplifier. It only needs to generate a very low power, very low current, very low voltage signal. For such amplifiers, it is not necessary to force a zero dc-mean current or voltage; the circuit doesn't have to be balanced. If you look at big amps - like a hi-fi loudspeaker amp - there are more reasons to choose a balanced design with a positive and negative voltage supply - reasons that have to do with engineering practicalities, like line losses, parasitics, power supply noise, ground bounce, and so on.

Nimur (talk) 03:53, 1 November 2014 (UTC)

thanks! by ground I meant simply the terminal which is designated ground in the standard 3.5 mm jack (bottom ring.) I suspect it's the same as the chassis and all other ports (the D-shaped thing on the VGA connector, for example), but I just said "the soundcard's ground" in case it isn't Asmrulz (talk) 09:22, 1 November 2014 (UTC)

I just had this idea, what if the left channel was CLK and the right was data, could one transmit serial data using the soundcard (for example to drive a counter or a shift register with a 7-segment display, only to see if it works) but I need to amplify the signal to 0..5 V that TTL understands Asmrulz (talk) 09:29, 1 November 2014 (UTC)

I don't think the answer is the same for all computers. Some of them are AC coupled - meaning that the signal may vary as to where it's mid-point is over time, others are not. I've been following a Kickstarter project "The Peachy Printer" which is working on driving a crazily low-cost 3D printer from the headphone jack of a desktop or a laptop (and are now trying to get it to work with a cellphone, an MP3 player or even a radio)! They are deflecting a couple of mirrors to position a laser using the left channel of the audio for one mirror and the right channel for the other. They have run into all of the problems that you're going to hit, (and there are many) and have outlined solutions in their project updates. It would be well worth trawling through those documents - and perhaps even contacting the project owner, who seems an amenable kind of a guy. To solve some of these problems, they had to resort to using an amplitude modulation technique where they send a continuous carrier signal from the sound port in an effort to keep the voltages referenced to some kind of a standard level. SteveBaker (talk) 13:24, 1 November 2014 (UTC)

Interesting, thanks Asmrulz (talk) 18:37, 1 November 2014 (UTC)

The statement that "voltage is always measured against a reference" is incorrect or at best misleading. A simple volt meter is proof. It has two terminals and voltage is always a relative measurement between two terminals. There is no absolute voltage scale. Grounding became a practice precisely because of this. Namely, shorts to surfaces tended to place humans between dangerous potentials, whence grounding was created to make humans and other non-terminals at a known potential as well as a creating an interruptible fault before killing someone. The point of "ground" is that if another terminal shorts to it, the fault protection will kick in and the stray voltage eliminated. You can certainly find balanced audio amplifiers that are 3 terminal but ground isn't a signal terminal. You can also find audio transformers (1:1) that can isolate circuitry (Midcom used to make them a long time ago for telephones and other applications). The drawback of 1 terminal being grounded is that the impedance is different for each terminal and noise will couple differently. Matched impedance makes the noise common mode. --DHeyward (talk) 00:53, 2 November 2014 (UTC)

That's more a matter of linguistics. The voltmeter can be said to measure against a reference that's determined by placing the black probe onto that reference and the red probe against the thing you want to measure. The black probe is the way you tell the voltmeter what the reference is. If you put the black probe on the signal wire and the red probe onto the ground pin, you'll get some negative voltage - but what you're doing is using the signal as the "reference" and measuring the ground voltage relative to that reference. The point here is that it is utterly meaningless to say "This wire is at 5 volts" unless you say "5 volts relative to ground" or "5 volts relative to this other wire". In most circuits, the implied reference is "ground" - but if you have a laptop and you're looking at the audio output, the voltage is relative to the ground pin on the connector - which may be wildly different to the ground of the thing you're connecting it to...or (in principle) different from (say) the negative terminal of the laptop's battery. SteveBaker (talk) 14:42, 3 November 2014 (UTC)

I think the "reference potential" for a portable multimeter is (definitionally) "the black probe, or whatever the black probe is touching." My statement shouldn't be interpreted to mean that the reference-point is guaranteed to be a good choice - only that the voltage of some other position is only a meaningful number in comparison to a reference (any reference, where-ever it may be). I apologize if this was a confusing choice of terminology.

It's the same way that tape-measures are used to measure distance, relative to a reference datum. If you tried to measure the distance to a point, and you just left one end of the tape measure flopping around, ... you'd still measure a "distance," but it would be an irrelevant distance. You'd probably want to hold the first end of the tape measure against some meaningful reference-point. Nimur (talk) 16:26, 3 November 2014 (UTC)

It seems like the question is trying to send digital data through an audio port. The first problem is how you could actually send the data, you will probably need to encode the data in one Audio file format. There is a big difference between digital and analog signals. Digital signals switch between two values something like a square wave. Trying to send a square wave through a sound card would cause a lot of problem - there would be a lot of distortion, a steady state signal might not actually appear. You might be better using a Modulation technique, like the way modems switch the frequency of a sin wave down audio phone lines.--Salix alba (talk): 23:47, 2 November 2014 (UTC)

I thought sine waves plus schmitt triggers on the input. Asmrulz (talk) 09:12, 3 November 2014 (UTC)

Yes, obviously to do a GREAT job of sending digital data through an audio channel, you're essentially re-inventing a good old-fashioned 56 kbaud audio-frequency modem such as you can still find in Fax machines and such. And if you do that, you'll get a baud rate in the tens of kilohertz range. But to build that yourself requires an actual modem chip and probably some external discrete components...or maybe you can do it with a lot of fancy software. If you need just low speed communication (hertz, but not kilohertz) and minimal external hardware - then maybe using the sound port without modulation will work well enough. SteveBaker (talk) 21:23, 3 November 2014 (UTC)

I think there are much simpler methods than what dialup modems use(d) (Trellis, QAM etc), such as FSK. But yes, I'd like to try with no modulation first. As you and User:Salix alba rightly noted, the soundcard can't produce steady voltage, but it doesn't have to because I'm only sending short pulses Asmrulz (talk) 02:18, 4 November 2014 (UTC)

Langer VS Hamburger invention

How can it be that Hratog Hamburger invented the saline only in 1896 while Langer invented the Langer's solution in 1882? (both of the information are from Wiki). In addition, Is Hartog Hamburger considered the first who discover the levels of the salt in our bodies before Langer? "Normal saline was invented by Dutch physiologist Hartog Hamburger in 1896. Hamburger's solution was only intended for in vitro study of RBC lysis and was never intended for clinical use.". In the next source, it also appears in reverse chronological order - I don't know why. 213.57.114.161 (talk) 14:39, 1 November 2014 (UTC)

Ringer's solution (not "Langer's", incidentally), is a rather ad-hoc mixture of electrolytes, which is isotonic with human blood. What Hamburger did was to establish that a normal solution of sodium chloride only (with no other electrolytes) could also be used for medical purposes. It would be more accurate to say that Hamburger invented the medical use of normal saline, rather than that he invented the actual substance. Tevildo (talk) 02:28, 2 November 2014 (UTC)

Soviet spacecraft atmosphere

I was going over the Valentin Bondarenko article. His story, of course, bears some tragic similarities to the fates of Grissom, White, and Chaffee in Apollo 1—both were the result of fires that engulfed the (in the American case, 100%, and at least 50% in Bondarenko's case) oxygen atmosphere that was apparently not thought to be a terrible idea (launch weight was the primary concern, as I understand it). After Apollo 1, NASA realized that it actually was a terrible idea, and began using a nitrogen-oxygen mixture roughly similar to earth atmosphere. What I haven't been able to find any record of is when the Soviet space authorities did the same. Did Vostok 1 launch with a primarily oxygen atmosphere? If so, when did (or did) the Soviets switch to a less-likely-to-result-in-fire-and-death American-style atmospheric mixture? Evan  18:51, 1 November 2014 (UTC)

Did NASA switch to a nitrogen-oxygen mixture during flight for the later Apollo capsules? My understanding (and I've not been able to locate a reference yet) is that while they switched over to nitrogen-oxygen while on the ground (to avoiding the super-flammability induced by 100% oxygen at 1.15 bar), they ran 100% oxygen at low pressure during flight. I'll keep looking, but I'd appreciate it if anyone can point me to some references which discuss atmosphere content and pressure for various spacecraft (particularly the post Apollo-1 capsules), and what hardware and procedural changes were implemented to support this. For instance, did the crew pre-breathe pure oxygen via masks while on the pad to avoid decompression sickness when the cabin pressure dropped during ascent, what was done to keep any oxygen leaks around their mask from increasing the oxygen content in the capsule during the countdown, and what was done to purge the nitrogen in the cabin once the pressure dropped to flight level. -- 190.58.249.5 (talk) 01:50, 2 November 2014 (UTC)

Bondarenko's accident occurred on "the tenth day of a 15-day endurance experiment in a low pressure altitude chamber ... . The chamber's atmosphere was at least 50% oxygen." This means that the chamber could have been pressurized to only 0.4 bar and still be normoxic (0.2 bar partial pressure oxygen). Is it publicly know what the pressure was? -- 190.58.249.5 (talk) 01:59, 2 November 2014 (UTC)

Offhand: I don't know about the USSR spacecraft. My memory is that after the Apollo 1 fire, they used regular air at a slightly increased pressure - 15.something PSI instead of 14.7. And once they were in space they gradually switched over to pure oxygen at lower pressure, something 3-4 PSI. I'll try to look it up. Bubba73 02:30, 2 November 2014 (UTC)

It is an interesting story. After the Apollo fire, when it was on the ground they used 60% nitrogen and 40% oxygen, at 10% or so above normal pressure. They could not use low pressure on the ground because the spacecraft was not designed for that pressure from the outside. If was pressurized above normal pressure to check for leaks. As the rocket ascended, when the pressure outside dropped to 60% of sea-level pressure, they started bleeding off the nitrogen/oxygen mix, while maintaining 40% of seal-level pressure. By the time it reached orbit, the pressure was about 35% of sea-level pressure, and most of the nitrogen was gone. Then they maintained about 35% pressure of almost pure oxygen.

From How Apollo Flew to the Moon, pp. 170-72. Bubba73 02:51, 2 November 2014 (UTC)

When I've heard Apollo 1's story told, it has always been emphasized that the high pressure pure oxygen atmosphere was what caused the increased flammability, and it is usually implied (and occasionally stated outright) that at a lower pressure (as during flight) the 100% oxygen atmosphere would not have been a problem. I was therefore very surprised when I was reading NASA's Recommendations for Exploration Spacecraft Internal Atmospheres and ran across this:

By contrast with human respiration that depends primarily on oxygen partial pressure in the atmosphere, materials flammability depends strongly on oxygen concentration (volume percent) and to a lesser extent on total pressure. (pg 11)

So I asked about that here two weeks ago, and while Stephan Schulz provided a couple mechanisms as to how the addition of inert gases could reduce flammability in a atmosphere where the partial pressure of O₂ remained constant, no references were provided either for the mechanisms or giving any numbers or graphs showing the magnitude of the effect on flammability of pO₂ compared to %O₂. For instance, what percent O₂ in a 1.0 bar O₂/N₂ atmosphere yields the same flammability in various substances as a 100% O₂ 0.21 bar atmosphere? -- 190.58.249.5 (talk) 03:12, 2 November 2014 (UTC)

Well, one reason that it was thought that 100% oxygen in space would not be a fire hazard is because that it was thought that a fire in zero-G could not be sustained. On Earth, the CO₂ produced goes up and away. In zero-G it was thought that it would stay around the flame and deprive it of oxygen. In tests in the space shuttle, I think they found that this isn't exactly true. Bubba73 03:51, 2 November 2014 (UTC)

The NASA document isn't inconsistent, it just fixes a different knob than the one you are used to turning and comparing. If, say, you fix the number of oxygen molecules in the capsule so that it's the same number as a 30%, 1 Atmosphere, the resulting 100% oxygen, low pressure environment will be more flammable than the 1 Atm case. This is because the amount of vapor from the object that will burn will increase in both the lower pressure case and also heat will need to be added to keep the temperature constant. The key to understanding the statement is that the partial pressure of oxygen and cabin temps must be habitable. Over that range of pressures/temps, flammability will be determined by how much fuel vapor is available. It is much more sensitive to concentration than pressure because of the added heat and the lower overall pressure in the high percentage case. The higher the concentration of oxygen, the more vapor will be available since the cabin pressure will drop and heat will be added to maintain temperature. Think of a petrol can that is sealed at 1 Atmosphere. Start pumping out only nitrogen molecules. Add heat to keep the temperature constant. That's my take, anyway. --DHeyward (talk) 08:41, 2 November 2014 (UTC)

Well stated. Still, I'd like to see some data.

Regarding the OP's question about Soviet spacecraft, our Soyuz and Voskhod articles indicate that they both used O₂/N₂ at 1.0 bar, and the Voskhod first flew in 1964, three and a half years after Bondarenko's death. Our Vostok article does not give atmosphere information. (Has that information been published?) Vostok 1 with Gagarin flew only three weeks after Bondarenko's death, so there wouldn't have been time to redesign the capsule to take advantage of lessons learned. And back to Apollo, our Apollo–Soyuz Test Project article mentions the need for an airlock connecting the two capsules "as the Apollo was pressurized at 5.0 psi using pure oxygen, while the Soyuz used a nitrogen/oxygen atmosphere at sea level pressure". It goes on to mention that the Soyuz was modified to "operate, during the docking phase, at a reduced nitrogen/oxygen pressure of 10.2 psi, allowing easier transfers between the Apollo and Soyuz". -- 190.58.249.5 (talk) 12:33, 2 November 2014 (UTC)

Thanks for the replies, everybody. It is definitely interesting that the Soviets started using nitrogen-oxygen mixtures before NASA did, and it does raise the question as to how NASA engineers would have reacted had they known. With all the "disappearing cosmonaut" rumors that were floating about it is disappointing, if not quite surprising, that there wasn't enough flow of information across the Curtain to result in NASA catching on. Evan  18:34, 2 November 2014 (UTC)

Through Apollo, they used nitrogen/oxygen only on the ground. Before an Apollo was very high in the atmosphere, they started venting that and replacing is with oxygen at lower pressure (see above). Bubba73 23:02, 2 November 2014 (UTC)

I saw. The significance of pressure and partial pressure vis a vis flammability isn't quite what I expected. Evan  01:48, 3 November 2014 (UTC)

One thing I always wondered about was why they didn't fill the capsule with 100% oxygen at low pressure prior to launch, to reduce the weight. Some thoughts:

1) As noted above, while less flammable than 100% oxygen at 1 atm, it's still worse than normal air at 1 atm.

2) This would require an additional procedure to depressurize the capsule after the crew enters, and repressurize it if the mission is aborted, complicating the launch process.

3) The capsule is meant to withstand pressure differentials, but only with higher pressure inside the capsule than outside. Reversing that may not work. Engineering it to withstand differentials in both directions might very well add more weight than would be saved. StuRat (talk) 13:06, 5 November 2014 (UTC)

Why don't dogs and cats get sick from licking, tasting, and even eating everything?

Dogs and cats constantly lick, taste, and even eat or drink many things that are usually considered unhygienic to humans: their own anus and the anus of other animals, their own feces and the feces of other animals, mud, shoe soles, dirty water, dirty balls and other dirty toys, garbage, etc. Why don't they get sick when humans doing the same thing would? —SeekingAnswers (reply) 20:56, 1 November 2014 (UTC)

They do pass on some diseases that way, but they just live with them. Humans sometimes do too! Most of us in the developed world are over-fussy about hygiene. Dbfirs 21:05, 1 November 2014 (UTC)

Most carnivores don't take apart their prey with flint knives (or better). They tear into the guts of an animal with apparent pleasure. Usually a mighty "predator", such as a wolf, is in reality part predator, more scavenger, and spends a lot of time eating scats (feces) it encounters. One visible difference of humans from most other mammals is in the stomach, which is much simplified, reflecting the substitution of fussy primate behaviors. Humans also have dramatically reduced odor-sensing capabilities (many mutated odorant receptors) ... hmmm, I wonder if this makes it harder for us to tell "good" rotten meat from "bad" rotten meat than it is for dogs? The simplest bottom line though is that most species are very well adapted to survive doing what they do - humans, a species of recent origin and ever-changing behavior, being a most notable exception.

That said, also recall felching. There are more things in heaven and earth..... Wnt (talk) 22:07, 1 November 2014 (UTC)

Supposedly, antifreeze tastes good to dogs, who will eagerly lap it up and then die from it. Or for that matter, chocolate. So they're not immune to everything. ←Baseball Bugs carrots→ 22:12, 1 November 2014 (UTC)

According to Mogens Eliasen's book:"Raw Food For Dogs - the Ultimate Guide for Dog Owners" in order to digest the large chunks of raw food that they swallow without much chewing, a dog's stomach produces very acidic digestive juices with a pH between 1 and 2, compared to a pH of 5 in humans. This is why they can eat things we can't. However, dogs do often end up being operated on to remove things they've eaten, such as shoe soles and rubber balls that they can't digest. I'm not sure though if this lower pH also breaks down toxins from bacteria. I do have a question about the original post though - why do you think we need links to dogs, cats, lick, taste and the other fourteen common terms you've linked? Richerman (talk) 22:59, 1 November 2014 (UTC)

Our article on gastric acid suggests that the pH in a human's stomach ranges from 1.5 to 3.5, not 5. Matt Deres (talk) 00:47, 2 November 2014 (UTC)

Hmm... it says that here too. I don't know where Eliansen gets 5 from. Richerman (talk) 01:08, 2 November 2014 (UTC)

Bear Grylls has demonstrated that you can actually violate pretty much most of the hygiene rules we stick to when living in the Wild: "The show has featured stunts including Grylls climbing cliffs, parachuting from helicopters, balloons, and planes, paragliding, ice climbing, running through a forest fire, wading rapids, eating snakes, wrapping his urine-soaked t-shirt around his head to help stave off the desert heat, drinking urine saved in a rattlesnake skin, drinking fecal liquid from elephant dung, eating deer droppings, wrestling alligators, field dressing a camel carcass and drinking water from it, eating various "creepy crawlies" , utilising the corpse of a sheep as a sleeping bag and flotation device, free climbing waterfalls and using a bird guano/water enema for hydration. Grylls also regales the viewer with tales of adventurers stranded or killed in the wilderness." Count Iblis (talk) 03:36, 2 November 2014 (UTC)

a truly terrible example. He has been hospitalised after filming his shows.Greglocock (talk) 21:24, 3 November 2014 (UTC)

Well, you can't trust everything you see on TV. The article you linked mentions something with a pony... in all seriousness, which do you think would be more repugnant to a TV producer: faking eating elephant dung (bear dung, etc.), or actually eating it? Though I suppose in a sense it's irrelevant -- it's not that eating these things can't be done, just that bad things could happen (Giardiasis being an obvious one that Grylls might conceivably have built up an immunity to at some point?) So whether he fakes it or he simply tries it for the show and gets lucky, the take-home is the same: still not a good idea. Wnt (talk) 04:55, 2 November 2014 (UTC)

Human babys also put allot in their mouth that is everything but "hygienic" without getting sick. On the long run Hygiene gives the impression to "pay out" statistically because it is simply a reduction of possible danger tho medicine tells us today that an Immune system decays if it is not burdened and the rising medical problem of Allergy may often be caused by tomuch Hygiene. --Kharon (talk) 05:08, 2 November 2014 (UTC)

Be careful. Some children do indeed put things in their mouths that harm them. ←Baseball Bugs carrots→ 07:03, 2 November 2014 (UTC)

Unfortunately indeed children to often die from chocking but that probably really happes most with completely hygienic items. --Kharon (talk) 23:18, 2 November 2014 (UTC)

Intestinal flora varies throughout the world. Montezuma's revenge is not mythical but reflects the difference in flora between different countries food supply. This gastro affliction is rarely fatal and takes a few weeks for adjustment. The same is likely true for other species. Once adapted to the local microbes, there is little effect and adaptation is not fatal in most cases. Humans tend to avoid getting getting sick and measure success by not getting sick. We are not so kind to animals, though. Dogs and cats get sick all the time and have the runs or vomit regularly yet unless they are dying from it we don't pay much attention. They may very well be suffering from their lack of hygiene but we simply don't notice/don't care about "Montezuma's revenge" in a dog the same way we feel sorry for (and track it) in humans. --DHeyward (talk) 06:33, 2 November 2014 (UTC)

Dogs and cats barf all the time. I know two dogs that died from some sort of food poisoning (one seems to have been intentional, the other accidental), and one that had to be operated on after eating a turkey carcass out of the trash. Where is the citation that supports a claim that such animals don't get sick form food poisoning or related illnesses? μηδείς (talk) 20:28, 2 November 2014 (UTC)

I agree. Another thing is that dogs, in particular, are able to suffer large amounts of pain without showing any obvious signs that they are suffering. We humans communicate even the slightest stomach discomfort to anyone who'll listen. So we tend to be more sensitive to things that upset our digestive system than we are to that in our dogs...so we assume that they don't get digestive problems when eating food that we wouldn't touch. SteveBaker (talk) 14:33, 3 November 2014 (UTC)

I'm with Count Iblis on this one. A TV show isn't the best example, but many humans survived just fine without modern sanitary practices. Sure, hygiene can be important, and it has saved many lives, especially in hospitals. But for daily routines, humans (and human babies) can eat and lick all sorts of things without necessarily becoming ill. You might be interested in reading up on the hygiene hypothesis, which is what

Some points:

1) Intestinal parasites do seem to be more common in animals that are careless about what they eat.

2) Indigestion seems to be more common too. As noted, such animals regularly vomit.

3) Acid from a puking dog actually dissolved the pattern off my brother's linoleum floor, so it's pretty acidic all right.

4) During periods of starvation, it makes sense to take more risks with what you eat, as starving to death is more likely than dying from what you eat.

5) People in undeveloped nations often live in less clean environments, and do suffer from more infectious diseases and have a much lower life expectancy as a result (lack of medical care probably has some effect here, too). However, they still manage to survive long enough to reproduce. They may well have fewer allergies (although some of that might just be that people who are sick all the time don't much notice allergies), but I'd still take the longer life expectancy along with allergies any day. StuRat (talk) 12:55, 5 November 2014 (UTC)

November 2

D5W is considered as isotonic solution?

D5W is dextrose 5% in water, and I saw on this blog that the nurse called it "isotonic". is it right? (this solution is without any salt - electrolytes) 213.57.114.161 (talk) 01:07, 2 November 2014 (UTC)

I don't think Isotonic is defined well enough, in a medical sense, to judge. You can put dextrose in normal saline for intravenous fluids or in just water or you can put lactose in a potassium salt based solution. "Isotonic" is going to depend on renal, liver, and pancreatic function and I suspect any solution administered by IV that doesn't overload the system with either edema or dehydration is going to be considered "isotonic" in a medical sense. None of them match the diversity of salts found in blood so trying to equate sodium to potassium as a salt will be very dependent on the patient. What's neutral for one patient could be lethal for another. --DHeyward (talk) 06:49, 2 November 2014 (UTC)

DC choke

I need to make a 50mH choke to take 3A dc. Any chance I can do it using a gapped iron core? If so, where would I get a core suitable for gapping?--86.176.23.223 (talk) 13:23, 2 November 2014 (UTC)

See Inductor and magnetic core for our relevant articles. Farnell do one that's 50 mH at 2.3 A (here), and other suppliers have similar products. (You can, of course, use two 25 mH inductors in series instead). They all appear to use toroidal cores - if your inductor is for a DC application, saturation, the main reason for gapped cores in AC applications, shouldn't be an issue, as you're not worried about distortion and harmonics. This paper gives some practical information if you want to make your own toroidal inductor. Tevildo (talk) 18:14, 2 November 2014 (UTC)

Thanks but the Farnell choke is a common mode line choke--- it wont take anything like 3 A differentially. I know I need a gapped core but where to buy them?--86.176.23.223 (talk) 18:21, 2 November 2014 (UTC)

Ah, right. Farnell and RS will sell you ferrite cores, but I don't know of any hobbyist suppliers of iron cores. A Google search on "iron transformer core suppliers" will give you plenty of commercial suppliers - some of them might be happy to sell you a single core, but I can't recommend any particular firm. Tevildo (talk) 21:48, 2 November 2014 (UTC)

Used to buy a lot from these two companies. I don't know about today but back the they had very helpful technical department. If they could not supply me with what I was after, they could nearly always point me towards a company that could. So run your need past them. It may be that you can utilize an old wire coat hanger or some laminations from an old transformer. This solution would need access to a vice, hacksaw and some files but might be quicker in the long run. Of course, you will need some way of measuring Henries (or in your case -tiny weeny henries). If you don't have a LCR meter in your kitchen one can always try this: .--Aspro (talk) 01:51, 3 November 2014 (UTC)

Heat transfer

If you're trying to solve a heat transfer problem with a layer of conduction and 2 layers of convection, then can you simply add together the Q values after working out Q, the heat transfer, individually from each surface using the conduction and convection equations? Or is it more complicated than that? — Preceding unsigned comment added by 194.66.246.112 (talk) 14:23, 2 November 2014 (UTC)

You have to set the rate of heat transfer through each layer equal to each other, this yields equations for the temperatures at the boundary of each layer. Count Iblis (talk) 17:42, 2 November 2014 (UTC)

that would eliminate heat transfer from the equation though. That's what I want to find. — Preceding unsigned comment added by 194.66.246.26 (talk) 18:06, 2 November 2014 (UTC)

It actually allows you to solve for that, after you eliminate the intermediary temperatures. Count Iblis (talk) 20:16, 2 November 2014 (UTC)

how? I'll give an example below.

Layer 1 - convection Q=1000*0.103*80=8240

Layer 2 - conduction assuming time=1 and thickness=1 Q=35*0.0456*(80-20)=95.76

Layer 3 - convection q=10*0.103*20=20.6

How do I find net heat transfer from this? — Preceding unsigned comment added by 194.66.246.55 (talk) 10:48, 4 November 2014 (UTC)

If you bury a body, how long does it still generate heat?

Does it generate heat during decomposition? — Preceding unsigned comment added by Senteni (talk • contribs) 17:47, 2 November 2014 (UTC)

Strictly speaking, a living thing stops generating heat at the exact moment it stops being alive—more specifically, at the moment the last of its biological processes has ceased functioning. It will, however, continue to emit heat until it reaches thermodynamic equilibrium with the surrounding medium (in your case, dirt, or, if left unburied, the atmosphere surrounding it). The microbial action of decomposition will generate some heat. I have no idea how much, but I have to imagine it is negligible. Evan  18:28, 2 November 2014 (UTC)

Newton's law of cooling may be useful here. --Jayron32 18:34, 2 November 2014 (UTC)

If you bury the cadaver six foot down then it will be in an anaerobic environment. The only bacteria able to live will be the endothermic ones. They require heat and so will not produce any. So no. It will be colder that the surrounding soil. Err. May I ask why you ask?--Aspro (talk) 18:38, 2 November 2014 (UTC)

But then, can you spot a buried body with a infrared camera several days after it was buried? If the bacteria are decomposing it, it will have a different heat-fingerprint. --Senteni (talk) 18:50, 2 November 2014 (UTC)

One needs to be careful about interpreting CIS data. With shallow burials, oxygen might well assist the breakdown of leaking body fluids but the ground has also been disturbed and any organic mater in the soil will start to oxidize in on being exposed to atmospheric oxygen. So is thermal imaging really detecting body-heat or oxidation of freshly disturbed the soil? --Aspro (talk) 19:14, 2 November 2014 (UTC)

There are plenty of anaerobic exothermic reactions. Fermentation and methanogenesis are examples. As discussed at anaerobic digestion, an anaerobic digester can generate about 1000 kWh per ton of dry food waste and is seen as a source of renewable energy. I have no knowledge of what specifically happens to a body in a grave, but there is no reason to assume that an absence of oxygen would necessarily imply cooling. Most reactions useful as energy sources to bacteria are exothermic, and that's true whether the environment is aerobic or anaerobic. Some of the exothermic energy is captured to build large molecules (an endothermic process), but on balance, bacteria are almost always net generators of heat. Dragons flight (talk) 20:53, 2 November 2014 (UTC)

Don't think you actually read and understood the articles you quoted from!--Aspro (talk) 23:44, 2 November 2014 (UTC)

Shrug, if you want to continue being wrong, I can't help you. Aerobic composting is strongly exothermic (and easily gets hots). Anaerobic digesters are typically weakly exothermic, and because they are most efficient well above ambient temperatures (e.g. 30-60 C, depending on design) often require insulation and external heating to operate efficiently in cooler external conditions. Doesn't change the fact that many of the key processes involved are exothermic though. For example, methanogensis from glucose is:

C₆H₁₂O₆ -> 3 CH₄ + 3 CO₂ + 137 kJ / mole glucose

Or glucose fermentation:

C₆H₁₂O₆ -> 2 C₂H₅OH + 2 CO₂ + 74 kJ / mole glucose

Neither of these have reaction energies resembling that for aerobic respiration:

C₆H₁₂O₆ + 6 O₂ -> 6 CO₂ + 6 H₂O + 2546 kJ / mole glucose

However, all these processes are still exothermic. Dragons flight (talk) 00:32, 3 November 2014 (UTC)

• Are we suggesting that coffins are filled with helium? The corpse will generate heat as long as any bacteria are decomposing it, even if they are anaerobic. Laws of thermodynamics. μηδείς (talk) 20:24, 2 November 2014 (UTC)

See my comment above. The anaerobic's do obey the the laws the laws of Laws of thermodynamics because need to convert heat to help power their metabolism. Compost heaps (aerobic) are hot, sewage farm slug (anaerobic ) are cold! No amount of pseudo-scientific waffle is going to reverse that.--Aspro (talk) 23:44, 2 November 2014 (UTC)

• • The laws of thermodynamics do not make endothermic reactions impossible. I tried a general Google search on the exact phrase "endothermic bacteria", but did not find anything that looked like a reliable source. However, a search in Google Scholar for the same phrase produces one hit on a paper, with the excerpt "The existence of (anaerobic) endothermic bacteria, which consume heat rather than produce it, shows that quantification of metabolic rate in terms of heat production has already its limitations." (The paper is "Metabolic acceleration in animal ontogeny: An evolutionary perspective" by S.A.L.M. Kooijman, but as usual for these things, its content is only available for purchase.) Note the parentheses: Koojiman is not saying that all anaerobic consume heat. I know nothing about the ones actually involved in decomposition. --174.88.134.249 (talk) 20:48, 2 November 2014 (UTC)

• • • I am a little confused, User:Aspro. Are you saying that the buildup of lactic acid in muscles cools the body? Are you saying that in a closed system anaerobic bacteria convert heat to usable energy, and the system as a whole cools? I never did study bacteriology, but this seems to contradict everything else I did study in biology and the hard sciences. μηδείς (talk) 01:52, 3 November 2014 (UTC)

One thing that could be measured and converted into red ("thermal vision") or green ("night vision) is electrical resistivity and conductivity. It's something like fire, and changes according to how how fresh a body is (how much liquid is left). In neatly stratified soil, freshly turned graves (or innocent holes) also give off their own distinct pecularity. When looking for long-lost graveyards, this can pick up pooled water in a grave, long after the human liquid is gone. If the lost soul was buried in a metallic casket, piece of cake.

I don't think I have to tell you this, but never dispose of a body in a metal casket unless you're cool with people knowing about it. If you put that much planning and expense into it, you're better off chartering a helicopter in a fake name and dropping it off in a volcano. Then the pilot. Then the helicopter. Then, it's up (or down) to you. InedibleHulk (talk) 00:33, November 3, 2014 (UTC)

Gravehunting is still a science in progress, but they figure it, like all disciplines, has something to do with pigs and magnets. InedibleHulk (talk) 00:36, November 3, 2014 (UTC)

Thermographic cameras are really sensitive, a fraction of a degree difference is plenty to produce an image - and it may be that even when the body is not generating heat and has reached thermal equilibrium with the soil may be detectable.

Consider that there is:

• A difference in thermal properties between soil that's been dug up and replaced and soil that's been compacted for a long time.
• A change in thermal conductivity of a cavity a foot or so beneath the surface causing heat from the sun to be conducted down into the soil at different rates.
• That surface vegetation is growing differently due to changed moisture content from the water and other nutrients from the decomposing body.

You can easily come up with enough changes compared to the surrounding ground to produce a tenth of a degree change that a camera might pick up even a year or two after the body was buried.

I spent many years doing simulation of military FLIR (forward-looking infrared) cameras - and these are quite incredible devices. There is an anecdote about the blockade of oil shipments from Iraq during the first gulf war when the Iraqi's were painting over the Iraqi flags on the bows of their oil tankers in an effort to sneak them past the blockades...but the thermal cameras on Apache helicopters were sufficiently accurate that the difference in the thickness of the paint and the differing properties of the different colors of paint in the painted-over flag was sufficient to allow them to see it quite clearly in the infrared imagery.

When you consider that - you can understand how finding a body in a shallow grave - or the massive disturbance caused by the burial in a deep grave - would be quite visible in the infrared. We're not talking about a ten degree temperature difference, a tenth of a degree might easily be enough.

So even if someone went to a lot of trouble to screen the body, just the digging of the hole might be enough to find it. Burying the body deeply in a recently ploughed or soon-to-be-ploughed field might be the best bet...but even then, I'm kinda skeptical that you could hide it from a careful search.

SteveBaker (talk) 14:27, 3 November 2014 (UTC)

Don't know if Steve would agree with me here, soil is not very heat conductive. Heat from a body would not leave as large a thermal signature on the surface as would the petrochemicals in the soil oxidizing. Some soils have so much that they can spontaneously catch fire when exposed to atmospheric oxygen.. . Even the Romans (that loved Garum), left the vats of fish guts in the sun, because at low temperatures the enzymatic action came to a halt. So the intestines and stomach of the copse is not going to generate much heat either. CSI: Crime Scene Investigation is fiction! They don't let science get in the way of a good story. So don't get your inexactitudes from this trash.--Aspro (talk) 21:16, 3 November 2014 (UTC)

I can't say what secret military capabilities exist, but the case of Eric Frein illustrated that police-grade IR was not meeting expectations when it came to finding a live body. Being able to detect a tenth of a degree difference in soil is all well and good... if you're searching a landscape that doesn't have big differences of temperature naturally. But where would you find one of those?

The thing is that you're not just measuring the temperature at one spot - you have a camera with live video. So if an area 6' long by 4' wide is slightly warmer (or cooler) than the rest of the area, you'll still see a ghostly rectangle showing through the noise caused by small plants, rocks, etc. Sure, there is a lot of noise, but when a strong feature is present, even with variation far less than the noise, you can still see it. People who know how to use IR cameras for this kind of task will be continually fiddling with the gain and offset knobs (like contrast and black-level) to try to pull out the kind of detail they want from the image. If you know you're looking for something that's roughly the size and shape of a shallow grave, then it gets a lot easier. Of course the bad guy could always dismember the body and bury the parts in separate holes a hundred feet apart - and then it would probably be impossible to spot this way...but criminals are mostly idiots - so competence is not always to be assumed here. SteveBaker (talk) 16:57, 5 November 2014 (UTC)

Still, I admit a fondness of disposal schemes that involve toilets or septic tanks. Just as a way to show you really care. :) Wnt (talk) 21:53, 3 November 2014 (UTC)

Toilets deposal? Do you mean in the sense of Aunt Agnis, When she dumps her dead brother’s ashes down the privy and then sits down to pee on them, to show how much she cared for him.. Good film. If so, I'm glad I'm not one of your relatives ;-)--Aspro (talk) 18:46, 4 November 2014 (UTC)

I don't know how far into the IR the modern FLIR cameras go. At very long IR wavelengths, earth can be almost transparent. A a body is composed of mostly water and fatty acids etc. It thus, would have a higher specific heat capacity than dry soil. So a cadaver in a very sallow grave (as opposed to six foot under as I said ) could be warmed by sunlight, so would be cooler by day and warmer by night. At long IR wavelengths you can see a hot water pipes through a 9 inch think brick wall. As murder victims are probably often buried in sallow graves, this technique may well work in 'some' situations. Putrefaction though, is a reduction process, so won't generate heat.--Aspro (talk) 18:37, 4 November 2014 (UTC)

Note that coffins have a fair amount of air in them, in addition to the body, so bodies so buried may undergo aerobic decomposition for some time, giving off heat as a result. If they are embalmed, that should slow the decomposition time dramatically, but the same total amount of heat would still be generated, in a completely sealed system, when it does completely decompose, however long that takes. StuRat (talk) 12:40, 5 November 2014 (UTC)

November 3

Passage of time with altitude

There was a piece on NPR this morning about time and super-accurate clocks. It said that due to relativity, the passage of time for a clock on the floor of your house differs from the passage of time for a clock hanging on the wall by one part per million.

That seems, intuitively, like a really high number to me (one second every 12 days!) - can someone give me a simple equation relating altitude to rate of time passage (compared to sea level, for example). Did I mis-hear "million" for "billion" or something?

SteveBaker (talk) 14:10, 3 November 2014 (UTC)

Physical Review Letters, 1980, Test of Relativistic Gravitation using a Space-Borne MASER, simplifying equation (1) for non-moving objects:

${\displaystyle {\frac {\delta f}{f}}={\frac {\delta \phi }{c^{2}}}}$

where φ is gravitational potential, and f is clock frequency.

Nimur (talk) 15:04, 3 November 2014 (UTC)

Thanks! That's what I was looking for. SteveBaker (talk) 20:38, 3 November 2014 (UTC)

Perhaps you listened to this NPR piece http://www.npr.org/2014/11/03/361069820/what-time-is-it-it-depends-where-you-are-in-the-universe ? The difference in clock measurements between wall and floor is on the order of one part in 10^16 (not 10^6). --Modocc (talk) 15:36, 3 November 2014 (UTC).

(I corrected an important error in my earlier comment: gravitational potential is not identical to gravitational potential energy). In more verbose notation, the equation expands (for two locations at height h₁, h₂ near Earth's surface where we can assume gravity g is a constant:

${\displaystyle {ClockError(ppm)}={\frac {g(h_{2}-h_{1})}{1\times 10^{6}\times c^{2}}}}$

...which gives a few parts per 10, not a few parts per million - so I think I am in complete agreement with Modocc.

Nimur (talk) 16:08, 3 November 2014 (UTC)

That makes more sense....it didn't seem right that the difference should be so large. Thanks! SteveBaker (talk) 20:38, 3 November 2014 (UTC)

• So what is the difference in time (clock error) out at the edge of the Solar System where Voyager 1 is? — Preceding unsigned comment added by Richard-of-Earth (talk • contribs)

You can plug and chug using the more general form equation I listed first; and use an estimate for solar gravitational potential, ${\displaystyle \phi \approxeq -{\frac {GM_{\odot }}{r}}}$. Of course, Voyager 1 is non-stationary with respect to Sun or Earth... so you'd really want to use the full-form equation and account for velocity and acceleration, as described in the original paper. The velocity and acceleration of Gravity Probe A was non-negligible, so it stands to reason that the velocity and acceleration of Voyager are also non-negligible, given that an interplanetary, extrasolar-capable exploration spacecraft has a higher kinetic energy at launch than a sub-orbital probe. Nimur (talk) 20:55, 3 November 2014 (UTC)

Also note that it is not error. Both clocks have the same error which is not the same as clock differences in relative (relativistic) frames of reference. High accuracy clocks are needed to measure the difference. Another example is Muon decay half-life as they enter the earths atmosphere at high rates of speed. The half-life increases over the "at rest" particle. That's a real physical manifestation of different clocks (for the particle, the half-life appears as "at rest" in it's own frame but the distance is shorter through Lorentz contraction). --DHeyward (talk) 21:38, 3 November 2014 (UTC)

Fair point; although to belabor the point in my defense, the term "error" is used in a lot of technical contexts to mean "any deviation from a reference value." For example, in feedback control, the "error signal" is what drives the system to its correct value. I agree that both clocks are equally correct. I did not intend to imply that the measurement is erroneous. Nimur (talk) 04:10, 4 November 2014 (UTC)

• Thanks folks, you have convinced me. I shall go out tomorrow and buy a bed mattresses of solid lead (or better still depleted Uranium). Sleeping upon this mass, will I will be able to extend my life by a few picoseconds – err... or a bit less. Giving up wine, women and song might be more efficacious but each to their own peccadilloes --Aspro (talk) 21:58, 3 November 2014 (UTC)

I ought to know this, or look it up for myself, but as long as you're looking at it already... do the effects of time dilation by speed and by gravity match up when something is in an elliptical orbit? For example, do clocks on Earth run at different rates (relative to, say, distant pulsars) when the planet is at its closest and furthest distances from the Sun? Wnt (talk) 05:04, 4 November 2014 (UTC)

Faster speed and greater gravitational potential both act to create more slowing, so the closest approach in an elliptical orbit (pericenter) will have more time dilation than the furthest distance (apocenter). Dragons flight (talk) 10:22, 4 November 2014 (UTC)

You're right! I knew these things individually, but somehow managed to flip their signs relative one another in my head. Wnt (talk) 12:22, 4 November 2014 (UTC)

Come to think of it, I suppose this suggests a better version of the twin paradox. I've seen it argued that the difference between the twins is that one accelerates. However, if two twins pass by one another in two identical space stations orbiting a supermassive black hole, one of which is in a circular orbit and one in an elliptical orbit that goes close to the horizon, then even though the stations each remain "at rest" (though not in an "inertial reference frame" because of the presence of tidal forces) the full time, when they next pass close by one another - I think even if they have the same speed relative to the black hole or the same combined kinetic and potential energy at the point of close approach to one another - they will still have different readings on their clocks. Wnt (talk) 14:29, 4 November 2014 (UTC)

You want to obtain the answer you should generally calculate the path ${\displaystyle s=\int ds}$ in Schwarzschild metric. Ruslik_Zero 19:40, 4 November 2014 (UTC)

Lysozymes (Lysosomal enzymes) and Veganism

Before I start I want to say that I don't mean to start any ideological discussion here - I aspire to read mostly "Technical" comments dealing only with the subject:

Dr Jockers claims in this article that some animal foods (i.e Dairy milk or uncooked eggs) can contribute Lysozymes to our Mucous membranes (I guess it's mainly the Oral and Nasal ones).

A possible notion from this article is that there are no comfortable non-animal sources for these enzymes. What do you guys think? thanks Ben-Natan (talk) 22:14, 3 November 2014 (UTC)

When you eat e.g. fat or protein, that material is not directly incorporated into the body. It is digested, then you make your own fats, proteins, etc. from the smaller pieces. From your article " enzymes that are naturally produced by the body's secretory cells within the mucosal membranes of the body." - emphasis mine. I'm not an expert on this, but my understanding is that the human body can synthesize these enzymes without ever ingesting said enzyme. While it is true that ingesting the enzyme would ensure that the body has all the right ingredients to synthesize it, those smaller individual ingredients are most likely available in plant sources. SemanticMantis (talk) 22:29, 3 November 2014 (UTC)

The above is correct. Ingested proteins will be broken down in the digestive system and will certainly not make it through intact. But even without all of that, first thing you need to do is look at the source of the statement. It's obviously a crackpot website. That should tell you enough about the validity of the statements made on it. Fgf10 (talk) 22:31, 3 November 2014 (UTC)

Indeed, but what about the claim that the Enzymes joins similar enzymes already on the surrounding oral and nasal Mucous membrane? You think it contains no truth? Thx Ben-Natan (talk)

Not at all. As noted by both people above, enzymes you eat do not enter your blood stream as whole enzymes. Anyone who makes any claim that they do can be automatically dismissed as not knowing their ass from their elbow, and every word that leaves their mouth from that moment forward can be safely ignored. An enzyme is a protein, which is a type of polypeptide. When you digest proteins (that is, when you eat them and then they go through your digestive tract) the protein itself is denatured, that is it is broken down into smaller pieces. The process of protein digestion basically turns the protein into the individual amino acids that make it up. Proteins are VERY sensitive things; if you make only a few minor changes to the way they are put together, they stop doing their job. So eating any protein that does anything inside your body will not give you more of that protein inside your body. Your body treats all ingested proteins as indiscriminate sources of amino acids. Any proteins made by your body (including enzymes), must be built from first principles by stacking together individual amino acids, and then folding it all up into the correct shape. This is why diabetics have to inject insulin. Insulin, a hormone made of several different proteins, cannot enter the blood stream by eating it. You need to inject it directly so it isn't digested by your stomach. If you ate insulin, you'd just get it broken down into the individual amino acids, and then your body would still have to make it. Which, in diabetics, they can't do... So, the moral of the story is you cannot increase the amount of any enzyme in your body by eating it. At all. Ever. Anyone who makes such a claim doesn't know what they are talking about. --Jayron32 01:11, 4 November 2014 (UTC)

I feel bad nitpicking such an excellent and correct explanation, but I feel I must point out that denaturing is not the protein breaking down into smaller pieces. It's the loss of secondary/tertiary structure and resulting loss of function. Which is of course one of the first things that would happen to most proteins when hitting the stomach (excluding things like pepsin). Fgf10 (talk) 07:52, 4 November 2014 (UTC)

To nitpick the nitpick, protein denaturation can break proteins down into separate pieces. A protein, in large part for historical reasons, is defined more or less as a tight lump of something mostly peptide in nature with a function, but can consist of multiple protein subunits or polypeptides. Also a single proprotein may be cleaved into multiple chains after it is made and folded. It is (or at least was) quite common for SDS-PAGE to split a biochemically defined "protein" isolated in terms of its activity into several individual bands on the gel. (Nowadays reverse genetics has decreased the prominence of that approach quite substantially) Wnt (talk) 14:40, 4 November 2014 (UTC)

Conceivably, one minded to be charitable could try to argue that lysozymes might contain a perfect combination of whichever essential amino acids are needed to make lysozyme, or that the text indirectly refers to some antibacterial effect of the enzymes acting on bacteria in the food itself, but... no. These would be really strained attempts. The author simply doesn't seem to understand the biology. Even when proteins contain special amino acids (i.e. hydroxyproline in collagen) the proteins still have to be produced with plain vanilla amino acids and altered after the fact. (Except selenocysteine, which is very special; but I don't think there is any in lysozyme, though I didn't check) Wnt (talk) 04:28, 4 November 2014 (UTC)

• I don't know the answer to the OP's question, but I think I have to point out that none of the replies above actually address it. The claim, as I understand it, is that lysozymes from dairy products that you eat or drink can migrate directly from the mouth to the mucous membranes without ever going through the digestive system. It seems doubtful to me that such a process could have any functional importance, but I don't actually know. Looie496 (talk) 14:20, 4 November 2014 (UTC)

I just read the article a second time, and I don't think the linked article explicitly claims what you say it does. Anyway I think the OP basically has the answer: there may not be non-animal sources of this specific enzyme, but that has little to do with production of the enzyme in the human body. SemanticMantis (talk) 15:33, 4 November 2014 (UTC)

(EC) It's worth noting that the despite the questionable nature of the original source, it did link to the supposed sources. These seem to be only used by the early claims, but perhaps it's just internal citation. Anyway while one of these is questionable, the rest seem RS.

The first one appears to be (someone screwed up the link). It's discussing modifying a (I think hen egg white) lyzosyme and testing the effect on gram negative bacteria. They do mention the possibility of using the modified enzyme in formulated food (as well as in a drug delivery system), but I'm not sure the purpose is primarily to have an in vivo effect or more to help protect the food. Either way a fairly odd choice for "natural food" promoting website, particularly once which is telling you stuff should never come from "commercialized farms" etc.

The second source is . The next source which mentions lysozyme is somewhat resistant to proteolytic action including from trypsin, but not from pepsin. Anyway by catalysing the lyzosomes first with pepsin, then with trypsin, they were able to find some components demonstrating non catalytic/enzymatic antimicrobial activity. Although they used hen egg lyzosyme (and were sponsored by the Ontario Egg Producers), I'm not sure they're suggesting this necessarily means there's any significance of consuming the hen egg lyzosyme (although they do mention how hen egg lysozymes are extensively use for preservation and related purposes). They mention "native lysozyme a few times, I think this means naturally occuring undigested lysozyme in somewhere.

The third one is . They are looking at the possible effects in the human mouth. Although they do make a brief mention of hen egg lysozymes (and one of the other things they were looking at being in mouth washes), it's not clear that they think dietary contributions is much of a factor compared to the lysozymes naturally occuring in the saliva (although they don't seem to discuss origins much).

The next source is , it's not particularly relevant however it does mention:

Lysozyme is found in virtually all human body fluids (e.g. saliva, respiratory secretions and liquor*). Expression of lysozyme in the skin has been located in the cytoplasm of epidermal cells and throughout the pilosebaceous apparatus

(*)Possibly they mean Cerebrospinal fluid

Next source is . Again they're looking at salivary lysozymes. They mention

Lysozyme present in the oral cavity is derived from the major and minor salivary glands, the gingival tissue and gingival crevicular fluid

and although they actually used hen egg lysozymes for their experiments, this and other stuff they mention make it clear these are just for convience and they're thinking of naturally occuring lysozymes in the saliva, not some sort of dietary constribution.

Next we have , this is looking at lysozyme (and lactoferrin) deficiency in babies is associated with bronchopulmonary dysplasia. They mention early on

Lysozyme is another antimicrobial protein found in nasal secretions and in many other external secretions. Lysozyme is the major protein in upper respiratory tract secretions, often representing 15% to 35% of total protein. Lysozyme is secreted along with lactoferrin by the serous cell.

they also say

The source of lactoferrin and lysozyme in tracheal aspirates of newborn infants is not known for certain.

They then go on to discuss some possibilities, including lactoferrin (but not lysozyme) from milk. I'mn not sure why they didn't consider lysozyme, but I'm pretty sure a similar conclusion still bears out namely that as some of the babies with high levels of lyzosomes were not fed and many others weren't fed much, it can't have come from there (but I even for those fed a bit of breast milk, I don't think they noticed any correlation). Finally they say:

We believe that the most likely source of lactoferrin and lysozyme is airway submucous glands. Lactoferrin and lysozyme are secreted by serous cells of the submucous glands of the adult human bronchus and nasal mucosa. Glands of the lower respiratory tract of newborn infants are also the source of lactoferrin and lysozyme.

This is quite an old article so the info may be seriously out of date, but on the whole, it doesn't sound like even in this more extreme case the dietary lysozymes had much effect. Perhaps the sample size and feeding level was too small, but the author of the naturalnews doesn't seem to have provided anything useful to suggest it does. The final source is . They do suggest it's possible in infants lysozymes and other antimicrobial proteins in breast milk may reduce infections and also encourage a healthy gut microflora, and also as

Recent studies show that the addition of recombinant human lysozyme to chicken feed would serve as a natural antibiotic, possibly suggesting that it could replace currently used antibiotic drugs.

However I suspect this is mostly thinking of the proteins acting at the digestive system level and not anywhere else. It looks like our article has a bit more on this and one of the earlier sources also mentioned that breast milk lysozyme (similar to human egg but it wasn't that source) lysozyme has anti-microbial peptide sequences after digestion.

My conclusion would be that it's possible that dietary lysozyme may have a minor beneficial effect in the adult dietary system (including perhaps the mouth), but even if this is the case, it likely doesn't last very long. And there's no evidence dietary lysozymes generally end up anywhere else (and although I agree with Looie496, we probably can't rule it out, I don't think it's particularly likely unless you're regularly snorting your food or something). This probably explains why the naturalnews article didn't actually provide any direct citations for the later claims, I suspect newer sources will help with some stuff, but probably not support their theory. (Actually this all reminds me of Mānuka honey.)

Nil Einne (talk) 16:43, 4 November 2014 (UTC)

Hmmmm, it turns out that human antibodies actually are not absorbed to the blood from the neonatal intestine, unlike many other animals. I found a cute site that suggests lysozyme works the same way as the milk antibodies, in the gut rather than by being absorbed, which lists a few refs. Unlike antibodies which are essentially a learned response, there's no theoretical reason why babies can't make lysozyme that is fully effective in whatever amount that is needed, yet that site suggests that something in breast milk helps to optimize their production level. Wnt (talk) 13:59, 5 November 2014 (UTC)

If proteins were always broken down in the digestion process, why is mad cow disease spread by ingesting proteins from affecting cattle ? StuRat (talk) 12:33, 5 November 2014 (UTC)

We could say that about many viruses... clearly digestion and barrier function isn't 100%. Prions are known for being particularly resistant to just about anything you try to do to them. Apparently they have caused lymphoreticular infection in about 1/2000 Britons, being detectable in appendix that is removed for other reasons, with the level of progression to clinical vCJD still being a matter of interest. Wnt (talk) 14:13, 5 November 2014 (UTC)

(edit conflict) The answer is we're not sure. See Transmissible_spongiform_encephalopathy#Competing_hypotheses which notes several competing hypotheses for how prions could be transmitted and still survive the gut; several hypotheses rely on as-yet-undiscovered agents, such as viruses or other small nucleic-acid-based agents which survive ingestion, and then produce the prions in situ. The other possibility is that the prions have some mechanism to protect themselves from the digestive process. We know that prion diseases can be acquired by eating tainted brain tissue, because it happens, but we don't as yet have a good mechanism for explaining why or how it happens. Your very question is flummoxing scientists as we speak. --Jayron32 14:20, 5 November 2014 (UTC)

November 4

Why does Gamma cell miss in the pancreas?

I read about: alpha, beta, and dalta. so where or who is the gama cell there? 213.57.99.33 (talk) 01:27, 4 November 2014 (UTC)

When you google "gamma cell pancreas" and get 492,000 hits, are none of them useful? μηδείς (talk) 02:35, 4 November 2014 (UTC)

Why don't you read through them all and tell us if any are useful, rather than expecting the OP to do so ? StuRat (talk) 12:23, 5 November 2014 (UTC)

The OP found our article on the pancreas, apparently, and wanted to know why it did not mention "gama" cells. I told him where he could get information pretty much sorted by relevance on gamma cells. Are you suggesting we get paid to read those sources for the questioners? μηδείς (talk) 19:32, 5 November 2014 (UTC)

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