Wikipedia:Reference desk/Archives/Science/2012 November 25

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November 25

A question in biology of Retroviruses (physiology and ecology)

A cat scratch's a man and allegedly almost not even wounding him (the cat may have a also micronic level of blood on his nail). let's assume that this blood on the nail is infected with a retrovirus (like HIV). considering the fact that this virus could be destroyed with oxygen (which can be found on the air), if the blood on his nail will interact with air, how much time will it take that the air will destroy the virus which allegedly localized on his nail (when outside\inside is fur) ? Thanks !!! — Preceding unsigned comment added by 79.179.170.159 (talk) 00:20, 25 November 2012 (UTC)

Reactions on a molecular level such as oxygen destroying the envelope of a virus happen extremely fast when they do happen (miniscule fractions of a second) but there is no way for us to speculate on specific conditions like how tolerant any random virus is of air exposure, how much liquid the virus might be protected by, and how long it would take to for the liquid to evaporate or oxygen to dissolve into it. μηδείς (talk) 02:46, 25 November 2012 (UTC)

(edit conflict) If your question is primarily about HIV survival outside of a host, then this page has very good answers. Other than that, it would be speculation to give you any sort of time frame, as survival rates depend largely on exactly what kind of virus it is and exactly what kind of conditions it has been exposed to. Merely being lodged underneath nails can still expose it to a variety of conditions that can change its survival rate significantly.

It is important to remember that viruses are closer to self-replicating chemicals, von Neumann machines, rather than to other forms of life. They are incapable of initiating metabolic reactions on their own, and can survive indefinitely in any state that doesn't change their biochemical makeup. They can be frozen, crystallized, and even disassembled and put back together, and they can still be viable. That said, anything that changes their biochemical makeup can denature them (again like any other chemical). Factors that can influence virus survival rates include UV (including from sunlight), extreme temperatures, desiccation, acidity, the absence of host cells, the loss or absence of capsids and envelopes, etc. All these can affect the infected blood under cat's nails. See virus processing.

Lastly, as far as I know, the claim that "viruses are destroyed by oxygen" is pseudoscientific quackery associated with dubious use of oxygen therapy that can be outright dangerous in some cases. Dioxygen (O₂), the oxygen we breathe, is a relatively stable allotrope. That doesn't mean it does not have an effect (e.g. this study shows it can decrease or increase virus replication rates), but it's certainly not as simple as "oxygen kills viruses". Ozone (O₃), however, is quite effective in destroying bacteria, viruses, and other microorganisms and is used widely in industrial sterilization. It is, however, toxic to all living cells (like other reactive oxygen species), as its high reactivity makes it capable of literally tearing most organic molecules apart. It is also only present in significant quantities in the stratosphere. In order for it to kill the viruses under the cat's nails, the cat would probably have to be exposed to enough ozone to kill the cat itself.-- OBSIDIAN†SOUL 02:50, 25 November 2012 (UTC)

Obsidian, what you said in the last paragraph contradics all i have heard till now, i can't analouge it for what your said in the paragraphs before. if i understand right. — Preceding unsigned comment added by 79.179.170.159 (talk) 03:24, 25 November 2012 (UTC)

It might help if you provide a link to where you heard that oxygen (and I assume you mean oxygen in the air we breathe) destroys viruses. I'm betting it's one of those "miracle hyperoxygenated water" companies or a religious/New Age therapy site. Ozone does, as well as reactive oxygen species like hydrogen peroxide, but they also kill most of anything anyway. AFAIK, stable dioxygen does not. -- OBSIDIAN†SOUL 03:42, 25 November 2012 (UTC)

It's from no link. 2 doctors of medicine told this to me. — Preceding unsigned comment added by 79.179.170.159 (talk) 03:45, 25 November 2012 (UTC)

Then I'm sorry but I can not help. Perhaps someone else who knows their microbiology better can. As far as I can see though, there are no indications in sources I can find that dioxygen destroys viruses. There is a lot of research on ozone for the last couple of decades, but ozone is not the normal state of oxygen we find in the air we breathe. Perhaps your doctors merely meant it in a general way? As in by saying "exposure to air" they really mean exposure to environments outside of a host?-- OBSIDIAN†SOUL 03:58, 25 November 2012 (UTC)

A search for "virus destroyed by exposure to oxygen" at Google and Google Scholar seems to result in almost pure quackery or nothing. Yet I have heard the claim made in semi-respectable popular sources as well. I suspect exposure to ozone or O^- must be the culprit if there is an effect. Perhaps that or simple drying? μηδείς (talk) 04:00, 25 November 2012 (UTC)

Probably. Innocent confusion or deliberate synthesis.-- OBSIDIAN†SOUL 04:16, 25 November 2012 (UTC)

Radical species derived from oxygen cause protein to denature and damages nucleic acids. Virus are basically nucleic acids wrapped in protein. 203.27.72.5 (talk) 04:25, 25 November 2012 (UTC)

Reactive oxygen species have already been mentioned. -- OBSIDIAN†SOUL 04:34, 25 November 2012 (UTC)

Obsedian, they have talked on it's appearance without an host, i believe. i am but a layman, i can't really mediate, not more than listening. — Preceding unsigned comment added by 79.179.170.159 (talk) 04:41, 25 November 2012 (UTC)

Plant identification in opening credits of Downton Abbey

What species are the two very large, spread-limbed, evergreen trees in the first three seconds of the Downton Abbey opening credits, as Lord Grantham (presumably) walks toward the manor house with his dog? See http://www.youtube.com/watch?v=v00bHK2C6kc. Thanks. μηδείς (talk) 07:32, 25 November 2012 (UTC)

They are apparently 18th century Lebanon cedars, according to this image from commons, and our Highclere castle article. Mikenorton (talk) 08:05, 25 November 2012 (UTC)

(edit conflict) There's more on the history of its origin in our article on Highclere Castle.-- OBSIDIAN†SOUL 08:10, 25 November 2012 (UTC)

Thanks. you can see why they'd put such a tree on a national flag. μηδείς (talk) 18:33, 25 November 2012 (UTC)

The first cedars were brought to England in the 1680s from Mount Lebanon where a small grove of trees tended by monks was said to have been planted by King Solomon. These were thought then to be the only cedars of Lebanon still in existence, so posession of one of their offspring was considered a prized asset. This was hightened by the number of times the cedar of Lebanon is mentioned in the Bible (in 48 seperate verses; Noah's Ark was made of it and it lined the Holy of Holies of the Temple in Jerusalem). They were wildly fashionable for large country houses throughout the 18th and 19th centuries, usually planted as a single specemin tree in a prominent place. It's difficult to think of an English stately home that doesn't have one. A lengthy diatribe on the subject is here. Alansplodge (talk) 19:21, 25 November 2012 (UTC)

Not Noah's ark, sorry. [Lebanon] Cedar is erez, the Noah's ark was gofer, traditionally translated as "cypress". I think you're thinking of the Ark of the Covenant. הסרפד (Hasirpad) [formerly Ratz...bo] 15:54, 27 November 2012 (UTC)

Wasn't the Ark of the Covenant made from shittim-wood? Trio The Punch (talk) 22:25, 27 November 2012 (UTC)

Yes, you're right. (The traditional cheder translation for both erez and shittim is tenenboym (tannenbaum), so I confused the two.) הסרפד (Hasirpad) [formerly Ratz...bo] 13:25, 28 November 2012 (UTC)

I stand corrected - neither Ark was made of cedar. I should have checked. Alansplodge (talk) 17:26, 29 November 2012 (UTC)

Question about subwoofers

There is any obligatory relation (or a “most” range) or proportion in the diameter of the magnets of a drive and the diameter of the drive itself?

I’m don’t saying that have to be an exact same relation but… for example, there is a way of knowing (by simply seeing the size of the magnet and drive) that the magnet is not the original, and instead, that the original one was bigger?

Iskánder Vigoa Pérez (talk) 14:56, 25 November 2012 (UTC)

There are essentially two common types of speaker magnetic configuration: a) types with a cylinder-shaped magnet inside and the "return" magnetic circuit on the outside, and b) types with a ring-shaped magnet on the outside and the return magnetic circuit on the inside. For the first type, the magnet is always made to fit just inside the voice coil, allowing a small clearance distance to avoid fouling. For the second type, the overall diameter of the magnet is unimportant, so long as the magnet is big enough to supply enough flux to saturate the pole pieces. With ferrite magnets, the strength is not high, but they are cheap, so it is common for ferrite ring magnets to significantly overhang the rest of the magnetic structure.

What is more important in contributing a low distortion output is the ratio of the voice coil diameter to the cone diameter. Here, the short story is that the larger the voice coil diameter the better, but for any given realistic voice coil to cone ratio, a different set of harmonics are excited. In theory, the simplest issues with harmonic distortion occurs when the cone area inside the voice coil diameter is equal to the area outside, but no manufacturer makes voice coils that big, because of the cost. Lots of other factors influence frequency response and distortion. The whole story is too complex to explain here, especially without diagrams.

For an excellent series of easy to read articles discussing the design factors of loudspeaker driver design, see the US magazine AudioXpress for the last 6 months or so. If you can handle the math (senior high school standard), the classic and very comprehensive textbook on loudpeakers & microphones written by Olson in the late 1930's and reprinted up to the late 1950's is still the best. It was a standard work in its day - every State or university library of any merit should have a copy.

It would be very very unusual for a speaker magnet to be replaced. It cannot fail in service, and assembly of speaker magnet structures is a somewhat specialised job. What does get replaced or repaired is the cone and voice coil - these often fail if overdriven and a tech can learn how to do it in about half an hour. — Preceding unsigned comment added by 121.215.71.120 (talk) 15:47, 25 November 2012 (UTC)

Keit 121.215.71.120 (talk) 15:34, 25 November 2012 (UTC)

Wow… Thank you very much… that clarify all my doubts Iskánder Vigoa Pérez (talk) 16:14, 25 November 2012 (UTC)

Background photon emissions

So, I was reading this paper "[www.scirp.org/journal/PaperInformation.aspx?paperID=21204 Marked Increases in Background Photon Emissions in Sudbury Ontario More than One Week before the Magnitude > 8.0 Earthquakes in Japan and Chile]", and it occurred to me that I don't really know what ground level background photon emissions that can be measured with a photomultiplier in a black wooden box covered with dark cloth in a windowless dark basement room are, despite knowing what all of those words mean. Although there is a bit more information in this earlier paper, I didn't have much luck via google. Do we have an article about this phenomenon ? I couldn't find one. Sean.hoyland - talk 15:23, 25 November 2012 (UTC)

As a scientist, I would be very reluctant to embrace the conclusions of any paper published in a SCIRP journal. Our article touches on some of that publisher's history, including instances where their peer review process seemed...less than rigorous: [1], [2]. (Speaking from personal experience, I know a number of graduate students who have been spammed with multiple invitations to join the editorial boards of various SCIRP journals—which doesn't inspire confidence.)

Meanwhile, Michael Persinger (the lead author of the two papers you found) has a history of publishing...interesting papers on fringe topics, and other groups have apparently had some difficulty reproducing some of his findings. Taken together, I see an awful lot of red flags. TenOfAllTrades(talk) 18:29, 25 November 2012 (UTC)

Agreed, I'm a geoscientist, but my only concern is that I really have no idea what background photon emissions are. Never heard of it. I'm assuming it's just one of those things I've missed i.e. everyone else has heard of it and knows what they are apart from me. Wouldn't be the first time. Sean.hoyland - talk 20:30, 25 November 2012 (UTC)

Even the most energetic gamma photons will not travel through more than a few metres of the ground. So any photons these fellows detected didn't radiate from Japan through the earth. Beyond that the only things coming up at these guys' basement photomultiplier are infrared, which is only an indication of how warm their basement floor is, and gammas from spontaneous nuclear decays in the few metres below them - again that's information only about the detector's environment, not about the whole earth or distant parts of it. Yes, there are background photons (coming down) from cosmic, galactic, and solar sources - but these won't make it into the basement (unless they left the basement door open). The only exception to that is radio frequency photons, which come from both astronomical and artificial sources - these can get in by diffraction and reflection (in the way that you might get a poor radio signal or bad cell phone coverage down in the basement). But you detect radio frequency photons with an antenna, not with an optical photomultiplier. So the claims in the paper are just aphysical - they're claiming they put an optical detector in a dark room, and that by some process it detected light; they then correlate that detection with some event (not exactly much data there) and then slyly imply a causation. So it's nonsense, at best. 87.112.97.202 (talk) 21:13, 25 November 2012 (UTC)

Well, here I go talking about something I know nothing about, but having read the earlier paper I provided a link for above in a futile attempt to learn what background photon emissions are supposed to be, I didn't get the impression that it was obviously aphysical or necessarily just visible light. The author says

• "There is classic theoretical and empirical evidence that photon emissions can originate from the types of silicates contained within crustal structures."....okay, I guess this is supposed to be about mechanoluminescence
• "Presumably the source of such emissions would be subtle mechanical pressures or electromagnetic stimuli."...so, I assume he's thinking about local sources, maybe including IR photons, I have no idea about his equipment, caused by local stress field variations coupled to global variations.....that somehow get into his black box....confused...but confused mostly about whether there actually is such a thing as ground level background photon emissions. Sean.hoyland - talk 22:12, 25 November 2012 (UTC)

It's pretty apparent from the references used in his paper that he (Persinger) is the first person (and probably the only person) who has claimed to detect these things. What he's calling 'ground level background photon emissions' are probably just the dark current from his photomultiplier tube. TenOfAllTrades(talk) 22:33, 25 November 2012 (UTC)

If you wanted to detect mechanical movement or stress in the local environment (which really means the cement floor of this guy's basement) then you'd use an ordinary stress sensor. Using a photo sensor is like using a thermometer to determine if your neighbour's TV is on. Ground movements strong enough to cause mechanoluminescence on the other side of the world would obviously show up on seismographs. 87.112.97.202 (talk) 22:52, 25 November 2012 (UTC)

Did the aborigines use dingoes as hunting dogs?

Does anyone know what benefit dogs brought humans in pre-invasion times? --Anthonyhcole (talk) 15:28, 25 November 2012 (UTC)

Our article (Dingoes#Present_day_distribution) says "possibly were used as food or eventually guard dogs" (without a source it seems) which sounds plausible but I assume no one really knows. There's this article. Sean.hoyland - talk 15:43, 25 November 2012 (UTC)

Another use, still today for bush aboriginals, is to keep warm at night - a sort of living heat providing blanket. A common expression in Australia for describing a cold night is to say someting like "Last night was a two dog night", or "Tonight will be a three dog night" due to its origins in using dogs to cuddle up to. Wickwack 120.145.26.49 (talk) 15:51, 25 November 2012 (UTC)

Wow, I never knew that. I always wondered why Three Dog Night called themselves that. Thanks. -- Jack of Oz ^[Talk] 06:13, 26 November 2012 (UTC)

Dingoes almost certainly didn't "come over" to Australia but were already on the continent Sahul before Australia was cut off from it by rising water and became an island within the last 10,000 years. The Australian aborigines may or may not have been directly related to the humans who brought the dogs to Sahul. New Guinea mainlanders have had the bow and arrow for a long time and had yam cultivation. Australian aborigines have neither, but have cultures better adapted to Australian conditions, as well as their own unique innovations. They may have lost technologies known to the New Gunieans, or they may have been the much older inhabitants of Sahul without these technologies when more recent waves of immigration brought them into New Guinea. It's entirely possible the common ancestors of the Australian Aborigines were an isolated southern people who'd arrived there perhaps tens of thousands of years before wild dingoes could have wandered down from the north on their own. Then the waters rose and the dingoes could have been stranded on Australia with Aborigines whose ancestors had never known them, with no cultural transmission of any sort of domestication behavior whatsoever. That's a logical possibility from the evidence and the timelines. μηδείς (talk) 05:20, 26 November 2012 (UTC)

I'm not sure how helpful that is. Australia and New Guinea were connected to each other 10,000 years ago, but neither has been connected to the Asian mainland for millions of years -- see our article on the Wallace Line. Looie496 (talk) 19:56, 26 November 2012 (UTC)

If you had posed that as a question, Looie, I could have mentioned how New Guineans use boats (ones primitive compared to Melanesians) and Australian Aborigines have lost that ability. I am not ignorant on the subjects discussed here at all. I can provide refrences for all my statements, But I wouldn't want to be unhelpful. μηδείς (talk) 23:01, 26 November 2012 (UTC)

What I was trying to say -- sorry for being unclear -- is that the important question is how and when dogs got to New Guinea. Getting from there to Australia is the easy part, since there was a massive land bridge. Looie496 (talk) 03:22, 27 November 2012 (UTC)

Yes, my point was really nothing to do with how they got to Australia, which I agree was by land bridge from New Guinea, but the point that the earlier Aborigines (since the OP specifically mentions them) may be unrelated to the human populations that brought dingoes to Sahul in the first place, hence no cultural transmission of practices such as cooperative hunting. This would be somewhat like the adoption of horse riding by American Indian tribes who took advantage of the animal introduced by Europeans. In that case there was cultural transmission by contact, but imperfect and indirect. Plains Indians were riding horses (contact transmission) bareback (failure of transmission of the saddle) before they encountered any serious direct contact with European settlers. In Australia, wild dingoes with a potential to be tamed may have approached Aborigines on their own and/or been retamed by them without any contact from New Guineans. Interestingly, it is known that the Amerinds had dogs. But I have read that (yet cannot confirm) all the original dogs died after European contact (presumably because of disease) and that all dogs kept by indigenous peoples now are descended from introduced European dogs. It's curious whether that applies to the chihuahua. μηδείς (talk) 18:00, 28 November 2012 (UTC)

Jared Diamond in Guns, Germs, and Steel says no: "Native Australians kept captive dingos as companions, watchdogs, and even as living blankets....But they did not use dingos/dogs for food, as did Polynesians, or for cooperative hunting of wild animals, as did New Guineans." Zoonoses (talk) 06:25, 26 November 2012 (UTC)

Thanks, Zoonoses. I had it in my mind that was the case but didn't know where I got the idea. Must have been that excellent book which I read not long after it came out. --Anthonyhcole (talk) 16:20, 26 November 2012 (UTC)

Dogs are useful for hygiene. They clean up the campsite by eating food scraps, and even faeces. Any modern owner of one of the "greedy" breeds such as beagles or labradors will know what I mean. HiLo48 (talk) 18:10, 28 November 2012 (UTC)

Final angular velocity after combining two disks

According the problem, two disks of equal masses are strung on the same rod. They are spinning with angular velocity $\omega _{0}$ but in opposite directions. The radius of one is $2r$ and the radius of the second is $r$. My first answer was $1.5\omega _{0}mr^{2}$ which was obtained by adding the momentum of the larger disk ($0.5\omega _{0}m(2r)^{2}=2\omega _{0}mr^{2}$) and the momentum of the smaller disk ($0.5(-\omega _{0})mr^{2}=-0.5\omega _{0}mr^{2}$), and then dividing the result ($1.5\omega _{0}mr^{2}$) by $mr^{2}$. Since this was wrong, I divided by $2mr^{2}$ instead. it was wrong again. Where am I making my mistake? --Melab±1 ☎ 19:15, 25 November 2012 (UTC)

You need to divide by the combined moment of inertia, which is not $mr^{2}$ nor $1.5mr^{2}$ nor $2mr^{2}$ . (Keep going ...) In rotational dynamics, moment of inertia plays the same role that simple mass plays in linear calculations. Our article on Moment of inertia might help. Dbfirs 21:07, 25 November 2012 (UTC)

I was able to find the solution. I have to divide ${\frac {1}{2}}\omega _{0}m(2r)^{2}-{\frac {1}{2}}\omega _{0}mr^{2}$ by ${\frac {1}{2}}m(2r)^{2}+{\frac {1}{2}}mr^{2}$. But, seeing that either disk can be chosen to have the positive angular velocity, the solution could then be $\omega _{f}={\frac {{\frac {1}{2}}\omega _{0}mr^{2}-{\frac {1}{2}}\omega _{0}m(2r)^{2}}{{\frac {1}{2}}m(2r)^{2}+{\frac {1}{2}}mr^{2}}}=-{\frac {3}{5}}\omega _{0}$ and that doesn't seem right. I also have to calculate the change in kinetic energy. --Melab±1 ☎ 22:31, 25 November 2012 (UTC)

I believe you are supposed to assume an inelastic collision, so you can forget about energy conservation and only assume conservation of angular momentum. No idea what you mean by "seeing that either disk can be chosen to have the positive angular velocity" bamse (talk) 09:27, 26 November 2012 (UTC)

The sign of your result just indicates the direction of the final rotation (the same as that of the larger disk). Energy is not conserved (elastic collision of gear wheels is very rare in real life!) The change in kinetic energy is just the total kinetic energy before meshing minus the total kinetic energy afterwards. This energy will be lost mainly as heat as the forces reverse the rotation of the small disk. Kinetic energy is $={\frac {1}{2}}I\omega ^{2}$ of course. See Rotational energy. Dbfirs 11:24, 26 November 2012 (UTC)

Gas bubbles on side of plastic container filled by chlorinated water

Regarding Chlorinated Water ...

I pour water in a plastic water jug and let the water sit for a couple hours. Small semi-spherical bubbles appear sticking to the inside plastic side. Question: What gas is in these bubbles? Is it chlorine evaporating out of the water?

--InverseSubstance (talk) 19:51, 25 November 2012 (UTC)

Probably air - assuming that the water was significantly colder than the temperature of the room initially, small amounts of nitrogen and oxygen come out of solution as the water temperature rises, forming bubbles that nucleate at imperfections on the surface of the jug [3]. Mikenorton (talk) 20:59, 25 November 2012 (UTC)

According to the World Health Organisation, "chlorine is present in most disinfected drinking-water at concentrations of 0.2–1 mg/litre" [www.who.int/water_sanitation_health/dwq/chlorine.pdf]. With an atomic mass of 35.5g/mol, that's 0.000028mol of Cl or a maximum of 0.000014mol of Cl₂. Assuming chlorine is an ideal gas, that would have a volume of 0.315mL. At standard temperature, far more than that would stay dissolved in water. But let's say you could force it all out of solution. 0.315mL of gas could be contained within 100 bubbles 0.9mm in radius. The bubbles would be greeny-yellow. 203.27.72.5 (talk) 01:41, 26 November 2012 (UTC)

Would you be able to see the color in that small of a quantity ? StuRat (talk) 05:49, 26 November 2012 (UTC)

• Does the single-purpose OP mean fluoridated tap water or chlorinated sewage or swimming pool water? Cool decanted water let sit usually shows bubbles which may be either air mixed in during decanting or carbon dioxide coming out of solution as the temperature rises. Chlorine sufficient to bubble out will certainly be detectable by smell. This is yet another underspecified and unanswerable ref desk question by a red link user with a strange knowledge of how to ask questions but a reluctance to contribute to the project. Regardless of the sockpuppetry, we need to know the source of the water, its treatment by the user, the original and final temperaure, how long it sat, and a host of other variables. And our answer would likely amount to medical advice. μηδείς (talk) 22:51, 26 November 2012 (UTC)

Is being HIV positive comparable to have diabetes?

Provided it's been treated. Comploose (talk) 23:52, 25 November 2012 (UTC)

Only in the almost irrelevant sense that both require lifelong treatment and monitoring, and both can kill you. As someone who spends so much time asking questions at the Ref Desk, Comploose, you surely know that your first stop for information should be the relevant Wikipedia articles. Do you have a question about the treatment and monitoring regimes associated with either condition that isn't addressed by Wikipedia? TenOfAllTrades(talk) 00:05, 26 November 2012 (UTC)

How can lifelong treatment and monitoring, and been killed be at the same time "almost irrelevant"? Comploose (talk) 00:29, 26 November 2012 (UTC)

Who said "almost irrelevant"? Trades is giving you good advice, and you respond with sarcasm and made up quotes? We don't do debate here, if you don't have a reference question this can be hatted. μηδείς (talk) 01:11, 26 November 2012 (UTC)

TenOfAllTrades said it. 4th and 5th words. 203.27.72.5 (talk) 01:16, 26 November 2012 (UTC)

Yes, my bad, I was looking for the irrelevant wikipedia article. He's right that the fact they are not curable is a rather minor similarity. μηδείς (talk) 01:22, 26 November 2012 (UTC)

I think the idea of the question was, "Is it true that HIV infection, controlled by medication, is not really that bad? Say, about as bad as diabetes?" If that's the question, then Ten did sort of miss the point.

I don't really know the answer to the question under modern treatment regimens, but I think the answer is still, "no, HIV is still worse, because you have to take lots more drugs with lots worse side effects, and also you can give it to someone else, which you can't do with diabetes". But more informed commentary would be welcome. --Trovatore (talk) 05:35, 26 November 2012 (UTC)

Well, diabetes will eventually kill many people who have it, even with the best medical care. Is that true of HIV these days ? StuRat (talk) 05:47, 26 November 2012 (UTC)

I have to take issue with that statement, Stu. An endocrinologist told me that diabetes, provided it is well controlled, is something you can die with but not of these days. I'll have a look round for some references that explain further. --TammyMoet (talk) 10:12, 26 November 2012 (UTC) This WHO factsheet tells us that diabetes causes fatal conditions such as cardiovascular disease and kidney failure, as well as other nuisances such as diabetic neuropathy and diabetic retinopathy. On a death certificate, the causes of death may be recorded as cerebro-vascular accident (for example) with a supplementary cause of diabetes. --TammyMoet (talk) 10:19, 26 November 2012 (UTC)

Yes. In my Dad's case, the order was diabetes -> kidney failure -> dialysis -> vascular degeneration -> heart disease -> open heart surgery -> post-op infection -> death . This all took 20 years, but diabetes was the start of the downward spiral. There was no mention of anything besides heart disease on the death certificate. They really only put the most obvious trigger for death, not the underlying causes. StuRat (talk) 04:05, 27 November 2012 (UTC)

On the current Deaths in 2012 page, diabetes is listed as at least part of the cause of death of 6 of the people listed. -- Jack of Oz ^[Talk] 19:31, 26 November 2012 (UTC)

• If we are just doing a junior-high style "compare and contrast", HIV is communicable, largely treated with pills, and can still progress to full-blown AIDS regardless of the best treatment. Diabetes is not contagious, requires daily bloodtesting and injections, and can be well controlled and lived with to a ripe old age with vigilance, other things being equal. All this can be gleaned from our articles. μηδείς (talk) 17:46, 26 November 2012 (UTC)