Wikipedia:Reference desk/Archives/Science/2017 December 17

= December 17 =

Evolution death
What is evolution death? One of the first medical descriptions of an ebolavirus patient's condition said:"The illness is characterized with a high temperature of about 39°C, hematemesis, diarrhea with blood, retrosternal abdominal pain, prostration with 'heavy' articulations, and rapid evolution death after a mean of three days."A Google search finds mostly results for Stanley Shostak's book The evolution of death, and even if I exclude results mentioning Shostak, I get things mostly related to biological evolution. Nyttend backup (talk) 02:37, 17 December 2017 (UTC)


 * That's either a typo or an idiosyncratic/headlinese jargony usage where progression toward would be the normal term. μηδείς (talk) 02:44, 17 December 2017 (UTC)
 * (EC) It looks to me like like a period or comma or perhaps a few words are missing. It's not saying there's an evolution death but rapid evolution of the disease resulting in death after a mean of three days. Although 'evolution' is a very weird word to use in this context, progression would be the norm. Maybe things were different then or perhaps more likely the doctor who wrote that didn't that much experience with English words used in the anglophone developed world to describe diseases. (I'm assuming of course that the transcription from the doctor's log is accurate.) Nil Einne (talk) 02:50, 17 December 2017 (UTC)
 * A real conundrum of digital historiography!
 * This thesis, Living under the threat of Ebola : a phenomenological study (2014, Univ. of South Africa) quotes the origin differently than the Scripps website.
 * "The first accurate clinical description of Ebola is attributed to Dr. Ngoy Mushola, who was part of the medical team during the 1976 outbreak in Yambuku hospital in DRC (Piot et al 1978:7). In the first patient's notes, Mushola describes the clinical presentation of this hitherto unknown disease as: "the illness is characterised by a high temperature of about 39°C, hematemesis, diarrhoea with blood, retrosternal and abdominal pain, prostration with articulations and rapid evolution to death after a mean of three (3) days"; pioneering descriptions true today as they were back then!"
 * I can't find Piot 1978, but I could find Piot's work from 1976 and 1977 in this online PDF-book format comprising the conference proceedings: Ebola Virus Haemorrhagic Fever, which quotes:
 * "the illness is characterized with a high temperature of about 39°C, hematemesis, diarrhea with blood, retrosternal abdominal pain, prostration with "heavy" articulations, and rapid evolution death after a mean of 3 days".
 * Now, that web-formatted book was scanned, some time after 1998, and converted to text:
 * "We acknowledge the superb scanning performance editing to a useful website document by Dr. Dirk De Bock..."
 * I would be willing to bet that the original was "evolution to death..."; and that the reason we find "evolution death" in so many places is because most researchers newer-than-1999 are using the free digital copy of the PDF, therefore, they are citing a copy-error verbatim!
 * Have we got anybody with access to a medical library that contains the actual paper proceedings of the 1978 colloquium - or even better, paper-copies of Ngoy (1976)?
 * Nimur (talk) 03:39, 17 December 2017 (UTC)
 * For the historically-inclined, here is a 1978 Bulletin of the WHO chronology of the events of 1976: Ebola haemorrhagic fever in Zaire, including attribution of the first possible cases to Ngoy. This PDF is a scanned image, but it unfortunately does not cite the exact questionable passage from Ngoy's notes.
 * Like always, digging into the history of Ebola only raises more questions than it answers. Like... why were the Belgians intentionally infecting guinea pigs with the virus?  What possible research benefit might there be to extracting the liver from an infected guinea pig and liquefying it in a blender?  Was this established medical practice in the 1970s, or ever?  (...apparently it is).  What were the Belgians really doing in the Congo in the first place, and why should we trust their version of events?  They don't exactly have a clean record when it comes to importing diseases and conducting medical research on the victims they created.
 * I'm glad the worst of history is behind us: and Belgians are no longer intentionally releasing diseased rats into hospitals in Africa to benefit humanity . ... At least the daily threat of thermonuclear devastation is a glimmer in the distant past.  The free world no longer abides, condones, or enables actual enslavement of real humans .  At least we still lead the world by prioritizing legitimate research over pseudoscience so our species can make it through another decade.  Well, darn it.
 * Nimur (talk) 03:52, 17 December 2017 (UTC)
 * You were dead on, at least up until that last strikeout paragraph when I kind of lost the point. But our article doesn't even cover all of it -- for example, HIV first showed up in the Belgian Congo during the worst of the atrocities.  The usual media explanation is bush meat with a connotation of sex with a monkey, but when desperate quota seekers were cutting up rubber vines and anything potentially edible and getting their hands cut off for failing to meet the quota with those same blades, a more direct route would seem more likely to me.  That curse was not lightly cast! Wnt (talk) 12:36, 18 December 2017 (UTC)


 * It just appears odd. Remove "rapid evolution" and it reads fine. Then simply compare "death" with "rapid evolution death" as a type of death, it makes more sense.  Keeping "rapid evolution" together is what's intended, not "evolution death." --DHeyward (talk) 04:37, 17 December 2017 (UTC)


 * I suspect the author did mean to write evolution to death, as this is idiomatic, if not usual. A situation can evolve quickly to the point of no return, for example.  Again, I think it's a combination of jargon with an accidental omission of to/toward. There's certainly no phenomenon here "evolution death" lurking in the literature, just this hapax legomenon. μηδείς (talk) 05:09, 17 December 2017 (UTC)


 * The Congolese doctor who first described the condition, as quoted above, would probably have done so in French - and "évolution rapide jusqu'à la mort" sounds much more felicitous than the above used English translation. "Evolution" is commonly used in French to describe the progressive development of a disease. Wymspen (talk) 12:48, 17 December 2017 (UTC)


 * Yes, and jusqu'à means "toward, up to" here. The problem with the English is the ungrammaticl "evolution death" standing for the proper prepositional "evolution/progession to/toward/until/up to death". μηδείς (talk) 03:54, 19 December 2017 (UTC)

Feynman Lectures. Exercises. Exercise 15-1 JPG
. .

I have solved the exercise: $$ \begin{align} x&=\frac{x'+ut'}{\sqrt{1-u^2/c^2}},\\ y&=y',\\[2ex] z&=z',\\ t&=\frac{t'+ux'/c^2}{\sqrt{1-u^2/c^2}}, \end{align} $$ According to the chapter 15-5 I understand that as Joe sees that Moe (moving with u = 0.866c) lays the 1 meter stick  down e.g. 8 times. Joe sees this stick with printed "1 meter" mark as 0.5m - stick. So Joe lays his 1 meter stick 4 times. Now a question is how many times does Moe lay his stick in his reference frame and how many does Joe in his system? Username160611000000 (talk) 10:08, 17 December 2017 (UTC)


 * The total number of times an observer lays his meter stick down is an invariant across reference frames. If one thinks of the observer doing something where a discrete number of separated "events" (e.g. laying down a meter stick) happen, then one could imagine a spacetime diagram where each "event" along that observer's world line is marked by a point. The number of events along a timelike observer's world line would be a constant -- they would also stay separated -- in whatever Lorentz frame is chosen.


 * However, there is some confusion evident in your post. Let's assume that Joe and Moe are both using a meter stick to measure the length of some object. If one of the observers is moving at .866c relative to the other, then the object is not at rest with respect to both of them. If it is stationary for one, then it is moving at .866c for the other and vice-versa; otherwise, it is not at rest relative to either.


 * But your post seems to be getting at something a little different from what Feynman was talking about -- he is talking about a meter stick in a more abstract sense, while you are talking about a stick you carry around and place down repeatedly to make a measurement. In this case, Moe were to use his 1 meter stick to measure the object to be 8 meters long, and put a mark on the object simultaneously (in his reference frame) each time he laid his meter stick as if to put "meter marks" on the object, then if Joe arrived at the object later, he would see the same number of marks on the object, but if his velocity relative to the object is different than that of Moe's, in general he would see the marks spaced at a different distance than one meter (this is always true if we restrict Joe and Moe to move along the same axis -- there are caveats when Joe and Moe are both moving at some "angle" relative to one another -- so let's just focus on the case of one-dimensional movement). So, if Joe's velocity relative to the object is less than that of Moe's, the meter marks will be spaced at less than one meter. If Joe's velocity relative to the object is greater than that of Moe's, the meter marks will be spaced at more than one meter. In any case, the number of times Joe lays down his meter stick while making his measurement doesn't depend on the Moe's prior measurement. 72.221.67.126 (talk) 04:24, 20 December 2017 (UTC)


 * However, there is some confusion evident in your post. Let's assume that Joe and Moe are both using a meter stick to measure the length of some object. If one of the observers is moving at .866c relative to the other, then the object is not at rest with respect to both of them. If it is stationary for one, then it is moving at .866c for the other and vice-versa; otherwise, it is not at rest relative to either.
 * This changes nothing. Suppose the point P on Fig. 15–1 has a speed = 0 in system (x,y,z,t) and has a speed = -u in system  (x',y',z',t'). Then the distance from origin of x'-coordinates to point P contracts 2 times. So if Joe lays down his 1m-stick 4 times, Moe sees this distance as 2 meters and lays down his stick 2 times. But Joe sees that Moe's stick is 50 cm long and x' > x or in other words that Moe lays down his stick more than 4 times. We again come to the paradox.Username160611000000 (talk) 14:49, 20 December 2017 (UTC)

Different causes of death
There are many different causes of death whether from illness or accidents etc but isn’t the cause of all deaths, ultimately cardiac arrest? Since the heart is required to stop before death happens. 90.192.100.85 (talk) 15:24, 17 December 2017 (UTC)


 * I'd say death = brain death. The heart could keep on pumping blood after it, but who would believe someone in this situation is alive?. --Hofhof (talk) 16:03, 17 December 2017 (UTC)


 * Death is a complicated issue and our opinions of what defines the onset of death have changed over time. For example, in defining when death legally occurs (legal death), the Uniform Determination of Death Act in the US recognizes that a person may die when either there is "irreversible cessation of circulatory and respiratory functions" (cardiopulmonary death) or "irreversible cessation of all functions of the entire brain" (brain death).  In most situations both occur at nearly the same time, though in the context of unusual injuries and aggressive medical interventions, it is possible to have only one or the other system fail (at least for a while).  Dragons flight (talk) 16:24, 17 December 2017 (UTC)


 * You are conflating a "cause" with "observable." Cardiac arrest is an observable condition that can be caused by a number of diseases.  The underlying disease that is behind cardiac arrest is the disease that causes death.  --DHeyward (talk) 22:27, 17 December 2017 (UTC)
 * The sequence leading to death commonly ends in cardiac arrest, but the underlying causes and contributory causes are different. There's an interesting discussion of this in the guidance to doctors on completing death certificates by the (UK) General Medical Council: see Section 5.1:Sequence leading to death, underlying cause and contributory causes . Klbrain (talk) 00:38, 18 December 2017 (UTC)
 * The confusion is between a mechanism of death (cardiac arrest) vs. a cause (e.g. myocardial infarction). All too often a mechanism appears on a death certificate where the cause of death should be; this is either through ignorance or laziness. - Nunh-huh 00:52, 18 December 2017 (UTC)

How does a cold environment affect human health
How does low-ish temperatures directly affect our health? Besides from behavioural based changes (like spending more time in a closed space with more people breathing the same air) can spending time in a room below our comfort zone (of maybe 26 C) affect our health? If the human gets enough calories to produce body heat, would it be a problem to live in a 20 C or 15 C room? — Preceding unsigned comment added by 31.4.156.1 (talk) 15:47, 17 December 2017 (UTC)


 * Our ancestors did it. I recall seeing scientific papers from the early 1900s, where several authors treated 15 C as room temperature for biological or chemical purposes. Wnt (talk) 16:11, 17 December 2017 (UTC)


 * Relevant articles: Room temperature and Thermal comfort. --Hofhof (talk) 16:14, 17 December 2017 (UTC)
 * We have lots of countries with cool climate in the top of the List of countries by life expectancy. Among them even Iceland at #6, with an average of −10 °C in the winter and 10–13 °C in the summer. To a healthy, fed human cold does no damage but freezing temperatures can. --Kharon (talk) 09:22, 18 December 2017 (UTC)
 * AFAIK, people in Iceland do not spend more time in a cold space than people in other countries. Why would they? They even have heated streets. For evidence about people being exposed chronically to cold temperatures I'd choose a poorer country, where people simply can't afford to heat their home around the clock. That would probably unfortunately be paired with not getting enough calories, which would contradict the OP's scenario. — Preceding unsigned comment added by Hofhof (talk • contribs) 12:38, 18 December 2017 (UTC)
 * No problem at all to live in such a room. I just had a look at the temperature and it is 16°C and I'm perfectly happy here sitting in my shirtsleeves. Dmcq (talk) 12:53, 18 December 2017 (UTC)


 * For a long time England was notorious for chilly and drafty houses, even among the wealthy. It probably has something to do with a climate that is often chilly and wet, but rarely below freezing. Looie496 (talk) 12:53, 18 December 2017 (UTC)


 * Mentioning "health" and temperature above makes me think that it may be of interest to know that the hospital I used to work at kept the temperature throughout the hospital at 60F/15C. The one I work in now keeps the temperature at 63F/17C. Lower temperatures and very low humidity help keep the hospital sanitary. I personally don't think that the lifespan of any bacteria is greatly affected by a chill in the air, but whomever sets the regulations certainly thinks so. 209.149.113.5 (talk) 13:27, 18 December 2017 (UTC)
 * Lower heating bills for the hospital. - Nunh-huh 07:14, 19 December 2017 (UTC)
 * Makes perfectly sense. Bacteria reproduce faster within a range of temperatures. 15 is probably too cold for some bacteria. --Hofhof (talk) 13:45, 19 December 2017 (UTC)


 * Yes, living at sub-optimal temperatures can negatively affect human health. We have some information at fuel poverty. You don't need to look at poorer countries: Fuel poverty in the United Kingdom is widely understood as a cause of death among old people ("The UK has an appalling record on cold-related deaths, with one older person dying every seven minutes from the winter cold. Colder countries like Sweden are better at protecting older people from the cold,” says Caroline Abrahams, charity director at Age UK. ) but it is increasingly seen as a factor in the deaths of certain poor people below retirement age ("Mum-of-four died alone in freezing home 'wrapped in coat and scarf after her benefits were stopped'. Elaine Morrall, who suffered from an eating disorder and mental health problems, was discovered dead at her home in Runcorn, Cheshire, earlier this month" ). NB we are talking about deaths at home, not of people caught outside in a snowstorm. The notoriously poor energy efficiency in British housing has a part to play, but a larger factor is the expense of the fuel compared to a household's income: in other words, poverty. Carbon Caryatid (talk) 15:26, 18 December 2017 (UTC)
 * PS Here's a pdf briefing from Public Health England:
 * Fuel poverty, cold homes and health inequalities: Cold homes are associated with a range of poor health outcomes. Cold can increase the risk of respiratory problems, such as asthma and bronchitis;9,10 circulatory problems, such as CVD and stroke;11,12 and exacerbate existing health conditions, including asthma, diabetes and recovery following hospital discharge.13,14 Home temperatures also have implications for mental health: cold is linked with increased risk of conditions such as depression and anxiety.15
 * Carbon Caryatid (talk) 15:36, 18 December 2017 (UTC)


 * These are some very good answers, better than I was thinking of. But I still do wonder if cold from poverty is different than cold from social expectation.  I'm thinking the early 1900s had a whole science of staying warm and comfortable in cold temperatures - galoshes, raincoats, scarves, many different kinds of hat, long underwear, dickies, sealskin, four-poster beds with canopies and I'm sure I'm just scratching the surface.  When most people can afford heat, the ones who can't are left without the old technologies to fall back on, or even knowledge that they exist let alone how to use them. Wnt (talk) 15:19, 19 December 2017 (UTC)
 * At least we have the Beanie to keep the head warm these days. Note: this is the universal name in several countries, including NZ. Akld guy (talk) 20:38, 19 December 2017 (UTC)


 * We are mammals, not cold blooded reptiles. We burn ten times more energy than we need to just survive given the available food resources. This allows us to thrive in cold conditions, we burn the required amount of energy to keep fat cells filled to a certain level given the food we eat. So, someone in energy equilibrium at 20 C would still be in energy equilibrium at 22 C or 18 C, simply because the body regulates its metabolic rate to match energy expenditure to energy intake. Count Iblis (talk) 20:51, 19 December 2017 (UTC)