Wikipedia:Reference desk/Archives/Science/2016 February 26

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February 26

On the definition of repolarization

I've read in the book of ECG (Mariot): "Electrical systole continues until the positively charged ions are pumped out of the cell, causing its repolarization.". If I would say that the repolarization is defined as entering of negative ions into the cell, I was right? and in addition, is the word "polarization" literal means to positive charge only or to both- negative or positive charge? ThePupil17 (talk) 01:17, 26 February 2016 (UTC)

Polarization means "a separation of charge". See Dielectric polarization. --Jayron32 01:51, 26 February 2016 (UTC)

Yeah, but in neuroscience, "depolarization" means positive deviation of the membrane potential from the resting potential, with the ability to induce action potentials, and hyperpolarization means negative deviation. But you're right, the definition of polarization in the cell biology context is very sign convention-dependent. The membrane potential is defined as the intracellular potential minus the extracellular potential. Yanping Nora Soong (talk) 02:05, 26 February 2016 (UTC)

• Unfortunately even the authors of books often don't understand electrophysiology very well -- neither the statement in the book nor your statement is correct. Changes in membrane potential, including depolarization and repolarization, are primarily caused by changes in membrane conductivity, not by movement of ions. Pumps are essential over the long term but they play no important role on the short term. Our membrane potential article covers these things in some detail, but it isn't easy reading -- this is a topic that many people find difficult to grasp regardless of how clearly it is explained. To fully understand it, it is necessary to make a close study of the Nernst equation and Goldman equation. Looie496 (talk) 15:43, 26 February 2016 (UTC)

high fever (104F) from an influenza infection triggering "drunkenness" (delirium), psychosis and suicidal thoughts

Request for medical and legal advice Tevildo (talk) 08:39, 26 February 2016 (UTC)
The following discussion has been closed. Please do not modify it.
To reframe the question so as to be answered without the provision of medical advice, how often does high fever (such as due to an acute influenza A infection) lead to neuropsychiatric complications (ranging from impaired judgment/delirium to impulsivity to suicidal ideation) in the general population, and is this risk substantially higher in at-risk populations like those suffering from PTSD, schizophrenia or bipolar disorder? Yanping Nora Soong (talk) 02:08, 26 February 2016 (UTC) As often as your doctor tells you when you ask him or her. --Jayron32 02:26, 26 February 2016 (UTC) Something's wrong here. The OP claims on their user page to be a biochemist and "a mental health activist, especially with regards to child abuse, bipolar disorder and PTSD". That being the case, I would think they would know how to research this type of question using professional journals, versus posting questions we can't answer here. General Ization Talk 02:31, 26 February 2016 (UTC) I'm getting results for the side effects of antidepressants (serotonin syndrome) and not for the intersection I want. I don't get literature access until I recover from the flu and get back to work. Also I'm asking about the general population versus mental health population. Why would asking a treatment provider be relevant here, especially as they are not academic researchers? Yanping Nora Soong (talk) 04:32, 26 February 2016 (UTC) Reframe Let me ask this question a different way, the question I actually really wanted to ask: if a patient presents with psychiatric symptoms (including SI) but also with high fever, would it be grounds for medical malpractice if a treatment provider in the ER sent that patient to the psych ward without first ruling out the high fever as a cause of the psychiatric symptoms? That is, wouldn't it be reasonable to suspect high fever as a possible cause of psychiatric symptoms (especially sudden onset), or do these complications happen infrequently enough such that would most doctors not make this connection? Yanping Nora Soong (talk) 04:43, 26 February 2016 (UTC) I'm not sure turning this from a medical advice issue to a medical and legal advice issue really helps. Nil Einne (talk) 07:50, 26 February 2016 (UTC) No one is going to be sued. At worst, a call-out post on social media will be made. Why is this still being classified as a request for medical advice? I am asking what the professional responsibilities of doctors are in this situation in recognizing psychiatric complications of organic illness. Yanping Nora Soong (talk) 08:08, 26 February 2016 (UTC) No one here is qualified to judge whether something would be grounds for a malpractice suit. You need to consult a lawyer. ←Baseball Bugs What's up, Doc? carrots→ 08:10, 26 February 2016 (UTC) @Yanping Nora Soong: Regarding the general issue only of whether flu-like symptoms could be linked with psychiatric symptoms, I think it's worth pointing out that interferon alpha, a natural response to many RNA viruses, can have these effects in some people, such as when it is given to patients to treat hepatitis C. (That much is on PubMed here, and PubMed is available anywhere) The association with influenza itself is not extreme - this abstract says influenza patients have 2.18 times the risk of neuropsychiatric symptoms. But flu-like symptoms can be triggered by a huge range of different things, some of which (like West Nile virus, HIV, and rabies) can affect the nervous system directly. I don't know how long the differential diagnosis takes to rule these out (or indeed, based on those news reports about the Ebola case in Texas, whether they get ruled out at all). I'm thinking a short-term decision to send someone to a psych ward, especially where suicidal ideation is concerned, might be motivated more by a desire to evaluate and control potential complications of the symptoms than to get at the root cause, at least right away. A person in that situation is probably confronted with an abundance of medical advice, and I would not want to contradict any of it, given the many unknowns of the situation. Wnt (talk) 14:20, 26 February 2016 (UTC) @Yanping Nora Soong: I don't know about this issue but I do know about scientific literature and the odd hodgepodge of access control schemes. Most research in the USA funded by the NIH has to be made freely available, but lots of good research is still locked behind paywalls. You might not know of WP:REX, where you can ask for copies of articles. I also often volunteer personal assistance in these matters, and I am happy to fulfill requests for specific articles on my talk page. In general, here [1] [2] are a directory and search engine that can be used to easily find only open-access articles. SemanticMantis (talk) 15:06, 26 February 2016 (UTC)

Launch windows for Mars landers

I am puzzled by a passage in Scott Hubbard’s memoir Exploring Mars. Referring to a decision being made in July 2000, about a mission to be launched in 2003, Hubbard writes:

“Finally, for 2003 the orbital mechanics were very favorable for a lander and this would not be true again for almost fifteen years. The orbital mechanics were not favorable for a solar-powered science lander in 2005, and this decision would give us more time to develop the alternative, a radioisotope power supply for 2007 or beyond.”

I understand that some launch windows (e.g. the one in 2003) are “better” in the sense that you can send more mass to Mars with the same amount of fuel, but what difference does it make whether the lander is powered by solar or by RTG? I would have thought that since the RTG supplies more power it would be used for heavier rovers (like Curiosity) which would ideally be launched in a more favourable launch window. Mathew5000 (talk) 05:27, 26 February 2016 (UTC)

Mars was the closest to Earth since ~50,000 BC in 2003 (and not even similarly close until 2018). It was also very close to the Sun at the same time. The average time between launch windows to Mars is 780 days and it's even longer near "good launch windows" like 2003. The Martian year is only 687 days. Therefore if they went in 2005 it would have to wait most of a Martian year after landing for Mars to get close to the Sun again and the rover couldn't be counted on to live that long (some vital part might fail in the winter (-200°F and twice as long) or a duststorm could cover the solar panels and turn off its electricity) Sagittarian Milky Way (talk) 05:51, 26 February 2016 (UTC)

The way I read this: 2005 was a bad year for a lander - any type of lander - because of the relative orbital positions of Earth and Mars. But - if we wanted to send one anyway - the only technology that was ready to fly was a solar-powered option.

By adding a few extra years, it would be possible to develop and mature an RTG-powered option. Even though RTGs have existed for a long time, every spacecraft design is unique; and it sounds like a spacecraft/lander based around an RTG simply wasn't ready at the time, and couldn't be ready for a ~2005 mission schedule.

To flight qualify a spacecraft design takes a long time, even if it is based on proven, extant technology. This is even more true for a planetary lander, because such missions are so rare, risky, and expensive.

Nimur (talk) 06:16, 26 February 2016 (UTC)

You read it a bit wrong. 2005 is a better than usual launch window for an RTG probe as can be seen here:

It takes about eight years after a perfect opposition for the oppositions to get as bad as possible, not two. The time between "good oppositions of Mars" about 16 years. (They said 15 because the time between oppositions is very close to 2 years plus 7 weeks when averaged over 15-17 years. Oppositions 16 or even 15.5 years apart are therefore impossible because of 1st grade math)

The reason they said 2005 wasn't favorable is because it's very bad for maximizing solar radiation unless the rover survives really, really long. Put the time of arrival of the 2005 launch window in here and it's almost at aphelion. The Sun's distance at arrival would be even worse than I thought as I didn't realize that the 2005 launch window's so late (why? I don't know) Sagittarian Milky Way (talk) 02:10, 27 February 2016 (UTC)

I wonder if they've considered a dual power system, where the (smaller) solar would work when the sunlight was present, and it would run off the (smaller) RTG only when dark, charging the batteries when there is an excess of power coming in. StuRat (talk) 19:16, 26 February 2016 (UTC)

Everything has been considered, including hybrid energy sources. Here's a paper on the MMRTG that's the current state-of-the-art. Here are some archives from the AIAA Joint conferences on Propulsion. Here's a fun paper, Human Missions to Phobos and Deimos Using Combined Chemical and Solar Electric Propulsion.

By virtue of the very long time scales and very massive budgets that are associated with spacecrafts, there is always adequate time to completely investigate lots of possible engineered solutions.

Spacecraft that can afford an RTG rarely need a solar panel, because (as this NASA brief explains), Radioisotope power systems do not require any sunlight to operate. By the time you've got the mass, money, and political clout to build an RTG spacecraft, you'd be laming your mission if you had to work within the energy- and operational restrictions that solar power imposes.

As the NASA Nuclear Power Assessment Study (2015) makes clear, NASA needs nuclear power. (Solar power just doesn't work for the missions that are planned). The more interesting question, rather than "solar vs. RTG", is at what point do we just place a fission reactor (FPS) on the spacecraft?

Nimur (talk) 20:09, 26 February 2016 (UTC)

The risk of a crash shortly after launch spreading radioactive material about might be countered if we could mine and refine the radioactive material on the Moon and launch from there. Something for long-term planning, obviously. StuRat (talk) 04:14, 28 February 2016 (UTC)

It's rather amazing how thoroughly the awareness of various nuclear accidents, such as inadvertently nuking Spain and Greenland, has been kept out of the public eye. When we think about science, it's inconceivable that any nuclear material could be released; but when it comes to military efforts, well, folks in Cuevas del Almanzora just have to learn to misstate where their farm products come from in order to get a good price. Wnt (talk) 04:04, 29 February 2016 (UTC)

Thank you everyone for these responses! @Sagittarian Milky Way: (1) That is a really cool diagram, thank you for linking, but I don't totally understand it. Is it showing the distance of Mars from a "fixed" Earth every three days? It looks from the diagram that when Curiosity (rover) landed in 2012, that was the least efficient trajectory of any launch opportunity? (2) I take your point, that Mars would be at aphelion in June 2006 [3] so it's not ideal to depend on solar power at that time. But Phoenix (spacecraft), which was solar-powered, landed on Mars around the May 2008 aphelion. And that was in the polar region! I know that a rover would require more energy than a stationary lander, but if you can operate a stationary lander at aphelion at 68°N, wouldn't the sunlight be sufficient at that time for a rover near the equator? After all, Mars is only about 9% further from the Sun at aphelion than its average (249 million km compared to 228 million km). (Also, the solar-powered Spirit and Opportunity rovers landed in January 2004, and were able to operate just fine through the aphelion in August 2004 and. obviously, well beyond that date.) Mathew5000 (talk) 22:01, 29 February 2016 (UTC)

Does "action potential" is the elctrical systole?

I've read in the book of Mariott that "This movement of ions initiates electrical systole, which is characterized by an action potential.". I don't understand this wording. Does he mean that the action potential is the electrical systole by itself? ThePupil17 (talk) 18:50, 26 February 2016 (UTC)

Term sought

If a person believes in the unbelievable, in something(s) that doesn't exist (things that are not real/realistically proven but the person believes it/in it no matter what others say), what kind of mental disability do they have? What is the correct term to identify this syndrome? -- Apostle (talk) 19:25, 26 February 2016 (UTC)

Faith (the "belief not based on proof" meaning). StuRat (talk) 19:30, 26 February 2016 (UTC)

Faith is what it takes to believe something that isn't true. Bubba73 ^{You talkin' to me?} 19:53, 26 February 2016 (UTC)

I'm searching for a medical term(s)... -- Apostle (talk) 19:45, 26 February 2016 (UTC)

This seems rather in bad faith yes, I giggled at use of "faith here" ... there's no "mental disability" or "syndrome" like this. People have worldviews based on ontologies and some people refuse to alter that worldview regardless of any information given. Everybody believes in things that are not falsifiably or provable (which is why ontology is philosophical). I know of no DSM diagnosis relating to such behavior. EvergreenFir (talk) Please {{re}} 20:07, 26 February 2016 (UTC)

Say for example: When family, relatives, friends, a doctor doesn't believe you, and they say, "How can you be right when everyone else in the world is saying that you are wrong, even the doctor said you are wrong and need medical help." What are they thinking? What's the correct term? - I was thinking of the word abnormal but it does not suffice. -- Apostle (talk) 20:09, 26 February 2016 (UTC)

Closest is psychosis; break with reality and delusional beliefs. Perhaps extreme case of cognitive dissonance. EvergreenFir (talk) Please {{re}} 20:11, 26 February 2016 (UTC)

Right, we do have an article on delusion, and that is something that can be diagnosed. As for good faith, OP here is better known to me than you are, and I know him to be earnest, curious, and ESL. He may not always express himself clearly but I'm pretty sure he's not out to smear religion, even if some of our readers may draw their own conclusions about delusion and faith in the supernatural ;) SemanticMantis (talk) 20:14, 26 February 2016 (UTC)

Sorry given all the troll socks on the ref desks, I'm perhaps not assuming the best of faith. I'm new to the ref desks and added then to my watchlist because of the socks. Thanks for the minor trouting and sorry to Apostle. EvergreenFir (talk) Please {{re}} 20:22, 26 February 2016 (UTC)

Hallucination may also be relevant. Not all people believe their hallucinations to be true or real, but some do. SemanticMantis (talk) 20:20, 26 February 2016 (UTC)

Confabulation is another possibility, which is remembering things that haven't happened. Tevildo (talk) 21:22, 26 February 2016 (UTC)

Are you including religion? If your nation is largely of a particular religion, a follower of that religion is not likely to be called anything except a "good [Christian, Jew, Muslim, Hindu, Buddhist, or whatever]". If they believe something that "sounds crazy" or outside the norm of the community's religion, they might be labeled as such. Hence the ridicule of Linus for believing in an alternate god-like being called "The Great Pumpkin". ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:42, 27 February 2016 (UTC)

Yes (whatever/whichever Wikipedia article(s) states really).

Its not like as you guys are thinking, so no worries... It's a great disappointment...everything is off of Wikipedia, with a bogus little story...

Religion, politics and science are not my topic – I’m rubbish at all three. I would’ve used them for my “fictional” character, (but as Jayron helped me understanding), but I’ve cancelled them including my personal philosophy because I’m meddling with religious and mythological stuff; in a manner. I do want people to be manipulated, basically take all the Zecharia Sitchin's fans; of course others if possible too...

The good and the bad ones who turn[ed] good, will understand because, they are the “good” and the “bad" ones who turned "good”… And the bad and or the evil ones? Not my brain and not my free will...

I do have mental disability(s), but I do not wish to receive a certificate from a doctor… If somehow this plan also gets cancelled than, I’m just hoping that I can manipulate people to pay me for my illness – if Kayne West and Syrians (who have smart phones and ipads but not me ) can, than – so that I can live my life; and or work (if possible, not guaranteed with the mental illness, plus "the world and its creatures are not my problem" anyway ",~7.2 Billion exist..." - if you know what I mean. )…

Thank you all for the information for analysis; I’ll read through…

Love you Wiki-Ladies!

Apostle (talk) 00:05, 28 February 2016 (UTC)