Wikipedia:Reference desk/Archives/Science/2017 April 5

= April 5 =

Weight loss and mass loss
I understand how one gains body mass: when you eat more calories than are needed by your metabolism, the mass of glucose (and substances that get converted into glucose) also increase, and the body converts some of that glucose mass into fatty cells. But what about when you lose weight, i.e. how does reduced energy consumption cause your mass to decrease? Of course I understand that the body uses the energy in its stored fat cells, but the body isn't converting mass to energy directly. Do the fat-storing cells, now empty of their energy, simply get lost in defecation? Weight loss covers dieting, medical reasons for unintentional weight loss, etc., but it doesn't address this particular issue. Nyttend (talk) 00:08, 5 April 2017 (UTC)


 * Generally, Cn1Hn2On3 plus oxygen yields water plus carbon dioxide. You lose the mass as you respire, perspire, and urinate. Fatty acid metabolism talks about the chemistry of it a bit. When you lose weight, generally the fat cells do not change in number, only size . Someguy1221 (talk) 00:28, 5 April 2017 (UTC)
 * Someguy1221, thank you for those links! Could you expand Weight loss (ironic...) with some sources from the fatty acid metabolism article?  My chemistry knowledge is good enough that I can understand the basic idea, but it's poor enough that I can't understand most of it, and I'm liable to misinterpret the sources if I try to write by myself.  Nyttend (talk) 00:54, 5 April 2017 (UTC)


 * See also here. Count Iblis (talk) 07:30, 5 April 2017 (UTC)
 * Here's a video from SciShow addressing this question. --47.138.161.183 (talk) 10:22, 5 April 2017 (UTC)

Lead used to fix a connecting bar
The caption to this picture says, "Punched lead cast in a Venice bridge wall, fixing the hard-metal connecting bar."

Why would the lead be punched?

Aside from its corrosion resistance, is it fair to presume lead is being used here since it is fairly malleable and hence could better accommodate any structural movements? Sandbh (talk) 06:49, 5 April 2017 (UTC)


 * The holes would have the effect of increasing flexibility at the cost of strength. So, if lack of flexibility was a problem, this might be the solution. StuRat (talk) 07:05, 5 April 2017 (UTC)


 * This looks like earthquake strengthening to me. Venice is somewhat prone to earthquakes. The bars keep the blocks aligned and in an earthquake, the lead compresses so that the entire structure doesn't shatter. Akld guy (talk) 07:17, 5 April 2017 (UTC)


 * The pieces of lead will have been hammered into the holes (the angle would make pouring molten lead too dangerous). That would not give a perfect fit against the stonework. However, punching those holes in the lead would then force the lead plugs to expand and press more firmly against the stonework. As the main purpose of the lead will be to stop water getting in between the stones, and corroding the connecting bar, the close fit is needed. The punched holes will then also allow that little bit of flexibility if the bridge moves. Wymspen (talk) 10:03, 5 April 2017 (UTC)


 * These answers are exceptionally plausible, thank you very much. Is this kind of thing mentioned in the literature anywhere? Dr Google has so far not yielded anything. The closest I haven gotten is to lead wool used for caulking which seems to a related concept, capitalising on the corrosion resistance and malleability of lead.


 * I found Solid as a Rock: Poured Lead Joints in Medieval Masonry, but it doesn't mention punched lead. Alansplodge (talk) 23:09, 7 April 2017 (UTC)

Epistemology and ontology of medical sociology (sociology of illness and health) and health psychology.
Hello,

I am looking at the two subdisciplines of health psychology and medical sociology. I note that they are subdisciplines of their parent disciplines that both study illness and health and have some overlap (methods etc). I have read the relevant wiki articles and note that m.s. seems to take a macro approach, situating the person within their social and cultural context while health psychology seems to look more at a persons thoughts and beliefs (in general). After having read the wiki articles I have gone on to read some research on the topic but have been unable to find clear definitions for both disciplines' epistemology and ontology. Could anybody help me out or direct me to articles I can read about these? I would like to see the (different) ways in which these disciplines understand the world.

Any help or direction towards relevant studies and articles would be greatly appreciated. BW, --129.215.178.207 (talk) 13:37, 5 April 2017 (UTC)


 * I think you have hit on the basic difference: health psychology studies medicine and health using the tools and ideas from the field of psychology. Medical sociology studies studies medicine and health using the tools and ideas from the field of sociology. The differences between these two stem from the differences between the fields of psychology and sociology. Understanding the different viewpoints of these general fields will inform the differences of the specializations. Sociology and psychology do have very different epistemologies. Medical anthropology, a specialization of anthropology, is the third member in this cluster of disciplines. --Mark viking (talk) 05:53, 6 April 2017 (UTC)

How fast could an 18-wheeler cab do 0-60 with an aerodynamic shell attached?
The higher power-to-weight ratio ones without that little cabin in the back for sleeping. How fast could it accelerate if it had an aerodynamic shell attached and was geared for 0-60 instead of pulling trailers? And why does a Mack truck cab have up to 2,060 foot-pounds of torque which can pull 300,000 pounds (including itself and what's in it, with an overweight permit) but a Ford F-450 has 925 foot-pounds of torque and can't pull anything close to 300,000/2,060*925 pounds? Sagittarian Milky Way (talk) 19:26, 5 April 2017 (UTC)


 * Think you could look at Truck Dragsters and truck racing. Also trucks have double gearboxes so one can change up (just like in a car) to 60 or more – very quickly.--Aspro (talk) 22:24, 5 April 2017 (UTC)

What does the defibrilator do to the heart when it febrilates?
How does it stop the chaos which happens in the heart cells (myocardiocytes) in the micro level? I've checked the article here and it's not clear to me. — Preceding unsigned comment added by 95.133.184.142 (talk) 16:25, 5 April 2017 (UTC)
 * Defibrillation literally stops the heart. The intent is the equivalent of a computer reboot: to stop undesired behaviour, it halts all activity and resets itself. I can't tell you what happens on the micro level.  Even out article states that he exact mechanism of defibrillation is not well understood.Mingmingla (talk) 19:12, 5 April 2017 (UTC)
 * Remember how The Fonz could walk up to a jukebox, rap it with his knuckles, and it would start playing? I think it's kinda like that.  Only half joking. --Trovatore (talk) 19:23, 5 April 2017 (UTC)
 * Moved from the Language Refdesk Roger (Dodger67) (talk) 19:27, 5 April 2017 (UTC)

Vaccines
If someone had a high risk of getting exposed to water contaminated by fecal matter, would any vaccine, combination of vaccines, or prophylactic medicine help keep healthy? --Hofhof (talk) 21:27, 5 April 2017 (UTC)


 * Yes, this was clearly demonstrated in a documentary a shown on NGC a few years ago. The presenter took a dive in the severely polluted Ganges river in India and became ill due to all sorts of pathogens in that river. A course of antibiotics cured the disease, the reason why the locals don;t get ill is because of acquired immunity due to being exposed to the polluted river. So, gradual exposure will help to build enough immunity to keep healthy. Count Iblis (talk) 21:40, 5 April 2017 (UTC)
 * Filter sizes between 0.1 and 0.4 microns will remove bacteria from water but will not remove viruses, though new “hollow fiber” technology can remove viruses as well. Water that has been boiled for 1 minute is safe to drink after it has cooled. The CDC recommends these and other measures to travellers. Blooteuth (talk) 21:53, 5 April 2017 (UTC)
 * It's clear that not drinking contaminated water to start with is the best solution. But I had in mind a scenario where this is not possible. For example, in the case of development workers, troops, and foreign correspondents. Hofhof (talk) 22:08, 5 April 2017 (UTC)
 * There are vaccines against some of the most common waterborne illnesses, including cholera, hepatitis A, polio (you probably got that one) and typhoid. Vaccines are not 100% effective, but it will at least reduce your chances of infection if exposure is inevitable. Many serious waterborne illnesses have no approved vaccine, however, such as shigella. Someguy1221 (talk) 22:17, 5 April 2017 (UTC)
 * I haven't got polio. Why would I? Hofhof (talk) 22:31, 5 April 2017 (UTC)
 * "you probably got that [vaccine]" Someguy1221 (talk) 22:34, 5 April 2017 (UTC)
 * In the case of troops, they are issued water purification tablets as part of their kit. 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 06:38, 6 April 2017 (UTC)
 * And anyone who's been backcountry hiking should know of the need to purify drinking water, though I guess that doesn't exactly fall under "prophylactic medicine". And it's definitely necessary; my dad got giardiasis on a backpacking trip through Yosemite National Park, presumably by accidentally ingesting some contaminated water. As noted previously, many waterborne diseases have no vaccine or prophylactic medications. --47.138.161.183 (talk) 07:17, 6 April 2017 (UTC)
 * I have no doubt there are perfectly fine portable means of purifying water. But the question was what if you had to drink contaminated water. Hofhof (talk) 11:28, 6 April 2017 (UTC)
 * Why would you HAVE to, when you can always put chlorine tablets in it or just boil it? 2601:646:8E01:7E0B:F88D:DE34:7772:8E5B (talk) 01:14, 7 April 2017 (UTC)
 * People in many third world countries have no choice but to drink contaminated water. Richerman    (talk) 15:39, 7 April 2017 (UTC)