Wikipedia:Reference desk/Archives/Science/2009 October 5

Welcome to the Wikipedia Science Reference Desk Archives
The page you are currently viewing is an archive page. While you can leave answers for any questions shown below, please ask new questions on one of the current reference desk pages.

October 5

Symptoms of novel swine (H1N1) influenza

Hi. I'm wondering if it is possible for the H1N1 virus to produce brain-related symptoms, for example: insomnia, mild depression, psychomotor retardation, prolonged shallow or manual breathing, fast and variable heartrate (OK, that's not entirely brain-related, but still), headache, irritability, numbness, and lack of desire for certain things? I also wonder if it could produce other symptoms such as irregular temperature in the extremeties (ears, hands, knees, feet; some hot, others cold), itching in the face and hands/feet, nosebleeds, dehydrated/cracked lips, low levels of urine, asthma-like symptoms, arrythmia, pain in the abdominal organs (kidneys, spleen, pancreas, gallbladder, etc.), drowsiness, and partial paralysis while in a half-sleeping state. I do know however that it can cause nausea, vomitting, diarrhea, fatigue, dizziness, fainting spells, and even seizures. Also, would having both the seasonal flu and swine flu make the symptoms worse? Would an altered sleep schedule? I am in no way asking for medical advice or a diagnosis. I am not trying to diagnose any of my own symptoms, nor those of someone else I know, nor do I have an illness that would make me lie about this. Please do not provide any information that pertains or alludes to a diagnosis or medical advice. Please also do not interperet this as a medical advice question. Thanks. ~AH1^(TCU) 00:10, 5 October 2009 (UTC)

Diseases and people are sufficiently individual and variable that almost any symptoms or signs might, in some circumstances, be caused in someone by almost any disease; when considered in permutations the possibilities would be endless. Most of the things you list are, in my entirely untrained non-medical lay opinion based on very limited knowledge, not particularly characteristic of Swine flu, but both individually and even more so in some permutations might be possible signs/symptoms of many conditions as serious or more serious, ranging up to imminently lethal.

Were I myself to want an answer to the question with any urgency, I would be inclined to ask someone definitely knowlegeable about such matters face-to-face - a GP springs immediately to mind (I happen to know one socially). If I wanted to use such information to, say, work up ideas for a novel, I might hang around common rooms in a medical teaching establishment or otherwise get to know advanced medical students socially, and invite their brainstorming over drinks. A large Science Fiction Convention would be another good venue to pursue such ideas, as there are likely to be student and qualified medical and or biology-discipline personnel as well as laypersons with relevant knowledge among the attendees (again, I speak from personal knowledge).

(Given the OP's caveats, I thought answering worth a shot, but I'll understand if other regulars disagree and act accordingly.) 87.81.230.195 (talk) 02:13, 5 October 2009 (UTC)

Our article on influenza notes the common symptoms, and our article on the 2009 flu pandemic notes that symptoms are generally in keeping with standard seasonal flus. We note that neurological symptoms have been noted in some cases; you'll want to check those references for further details. — Lomn 02:24, 5 October 2009 (UTC)

Check also the article Fever since it is a common symptom of influenza and it is generally a sign of the body correctly coping with the infection. A question like "Would an altered sleep schedule...make the symptoms worse?" is asking for medical advice. Cuddlyable3 (talk) 13:07, 5 October 2009 (UTC)

Headache is common. Fatigue is common, but not drowsiness per se. Dehydration and subsequent low levels of urine could result from the nausea, or from simple irritability with poor feeding in children. The other symptoms you mention would be uncommon, but theoretically possible as the IP above describes. Sleep deprivation depresses the immune system, but merely an altered sleep schedule (such as working the graveyard shift) would not have any effect to my knowledge. - Draeco (talk) 18:47, 5 October 2009 (UTC)

how does........

how do ice flakes fall even during rain in TROPICAL RAINFORESTS? —Preceding unsigned comment added by Vgrewal0 (talk • contribs) 09:54, 5 October 2009 (UTC)

I assume you mean hail. Hail forms in high-altitude clouds, which can be cold regardless of surface temperature beneath them. Sufficiently large bits are able to reach the ground still frozen, even on hot days, because air is a poor thermal conductor. — Lomn 12:47, 5 October 2009 (UTC)

...and so is ice. SteveBaker (talk) 15:21, 5 October 2009 (UTC)

Ideal gas law. If you take an air parcel at sea level and lift it to say, 500 millibars, temperatures can drop sharply below freezing. John Riemann Soong (talk) 04:31, 7 October 2009 (UTC)

If I remember correctly, hail is falling in the Amazon rainforest more than usual due to more particulate matter being released from smoke from the increasing number of fires. ~AH1^(TCU) 01:10, 8 October 2009 (UTC)

Carbon Monoxide Levels Given Off By Older Vehicles

Let me begin by saying that this question is in no way a roundabout way of obtaining medical or legal advice. That said, the other day, I noticed that I was able to smell the exhaust of a car idling outside of myself, which made me wonder exactly how much co is in exhaust fumes, and how many ppm would be in the air as a function of time (odd thing to wonder about, I know?) Thus, lacking the means to figure this out myself, I wanted to see if anyone here had even a rough idea of how many ppm of co would be in the air after a vehicle was idling outside for t minutes(namely, t = 15 minutes, 30 minutes, 1 hour) For simplicity, assume we are talking a room of average size, that the vehicle is older and ill configured, and that the only major source of ventillation in the room is the window outside of which the vehicle is idling. [Again I want to stress that this not a roundabout way to obtain legal/medical advice, obviously the above data would in no way imply anything relating to either types] —Preceding unsigned comment added by 71.61.48.205 (talk) 12:52, 5 October 2009 (UTC)

You cannot smell Carbon monoxide which increases the danger of Carbon monoxide poisoning.Cuddlyable3 (talk) 12:58, 5 October 2009 (UTC)

Presumably the OP did not pass out from inhaling those fumes. The article does not quite come out and say, so I have to ask: Once CO is exposed to the open air, does it quickly join with O2 molecules and become pairs of CO2's? Or does it simply dissipate? Not that you want to be surrounded by CO2, either. →Baseball Bugs ^{What's up, Doc?} carrots 13:03, 5 October 2009 (UTC)

I'm aware that you can't smell co, nonetheless, it is present in exhaust fumes. Or rather, any car giving off extremely odorus exhaust fumes is likely improperly calibrated, and thus, also giving off carbon monoxide. Thank you though:) Given that most naturally occuring oxygen is O2, it is unlikely that it bonds with CO; though other reactions might take place [though they couldn't be overly significant, else co poisoning would be much more rare.] [this is op by the way] —Preceding unsigned comment added by 71.61.48.205 (talk) 13:07, 5 October 2009 (UTC)

There is far too little information to make a meaningful scientific estimate of "ppm emissions per unit of time". If the vehicle is outdoors, wind will be a major factor in controlling the local particle levels. A simpler starter-question would be - "Can you find or measure the net CO emissions from a vehicle in number-of-particles-per-minute?" The answer to this is of course "yes" - in fact, it is required in many states - California's mandatory measurements include Carbon Monoxide (and Carbon Dioxide, nitrous oxide, unburned hydrocarbon, and other contaminants). How this net flux of contaminants disperses is a very hard problem to define. If you were in a tiny enclosed room running the engine and assuming uniform dispersal, you could count the net particles released and divide by the volume of the room. (Note: it is very dangerous to run a car in a closed environment - you can suffocate and die before you ever smell the contaminants). But outdoors, all bets are off. Local and prevailing winds will disperse the particles pretty well - so even if you correctly know the net contaminant released (by mass), it's hard to know what your vehicle's contribution is to contaminant density. Nimur (talk) 15:26, 5 October 2009 (UTC)

The issue is not so much about how well set-up the car is (although that does have an impact) - but whether it has modern catalytic converters. These are required by law on vehicles less than 25 years old - but those older than that are exempt in most parts of the world - so the biggest risks are with cars older than 25 years. There are far too many unknowns to be able to calculate a direct answer to the OP's question though: How far was the car from the window? What was the wind speed and direction? What engine capacity does the car have? ...I'm sure there are others. But since any one of those things would affect the answer (possibly by a couple of orders of magnitude each) - our error bars are far too wide. SteveBaker (talk) 15:21, 5 October 2009 (UTC)

I figured that this was too broad of a question to realy get a specific answer. I guess my major curiosity is how large an impact sources of co outside a building can have on the co levels inside a building; I guess asking for an approx ppm value was a little absurd, I was still a little sleepy. In other words, can you ever get an appreciable co level from running a vehicle outside of a window, how long would it take, what kind of conditions would there need to be, etc? This would probably be more in line with what I was wondering; sorry for the confusion...71.61.48.205 (talk) 16:28, 5 October 2009 (UTC)

CO does not react with normal oxygen at room temperature. Oxygen is a diradical -- and this makes it only reactive at higher temperatures where other radicals are produced -- hence why combustion takes place at high temperatures. Diradicals tend to react only with other radicals since if a diradical reacted with most "normal" molecules (that have filled orbitals), a monoradical would be produced (which is higher in energy). You could probably quench it with a flood of reactive singlet oxygen, but you'll also destroy whatever organic material is with the CO (read: the tissues of most living things) in the process. John Riemann Soong (talk) 22:14, 5 October 2009 (UTC)

Singlet oxygen is not terribly reactive. --Pykk (talk) 14:29, 6 October 2009 (UTC)

OK, so the answer to my question would essentially be that it dissipates, i.e. it spreads out and the potential harm is significantly reduced - unlike as with a closed environment, such as a sealed house with a malfunctioning stove or furnace, or a sealed garage where someone is trying to snuff it by running their car. →Baseball Bugs ^{What's up, Doc?} carrots 23:55, 5 October 2009 (UTC)

Severe Weather

What is the sever weather chance for Fort Worth today/Accdude92 (talk) (sign) 13:30, 5 October 2009 (UTC)

According to the weather channel, there is a 30% chance of isolated thunderstorms. No severe weather warnings at this time. I would thus say there is a probability of less then 30% of severe weather in Fort Worth Texas today. Googlemeister (talk) 13:48, 5 October 2009 (UTC)

The National Weather Service is the authoritative government bureau for these kinds of questions. They are the original source for nearly all redistributed commercial forecasts (as seen on the Weather Channel or local news); and they collaborate very closely with military and civil aviation weather bureaus to establish uniform estimates of weather conditions. You can see their forecasts directly, as well as most of the raw data and RADAR imagery that is used to make these forecasts, at nws.noaa.gov. Fort Worth Weather Forecast Office is a regional center, so there is no shortage of accurate information for you. Nimur (talk) 14:36, 5 October 2009 (UTC)

TLC: detecting 0.5% yield?

Suppose by nature of your laboratory (a kitchen) and the nature of your reagents/catalysts (phosphoric and acetic acid), your desired experiment gives you like a yield of 0.5%, but you want to prove the yield exists. What's a practical way of showing a new ester has formed, besides the subjective means of smell and taste? Would 0.5% product show up against the starting material on TLC? John Riemann Soong (talk) 15:22, 5 October 2009 (UTC)

Depends on what you are detecting - for visual inspection using fluorescent backed tlc plates aromatics>>non-aromatics. For aromatics I think a 1:200 ratio is just detectable by eye (spot size ~1:30 ?). With a color based detection agent it might be easier.83.100.251.196 (talk) 19:26, 5 October 2009 (UTC)

Mostly a bunch of aliphatic esters, though I may decide to use various aromatic acids (or possibly their anhydrides) or something like that. Actually because of the nature of some of my reagents (they are food-based) I may get a spread of products (and food-wise this is desirable). John Riemann Soong (talk) 22:05, 5 October 2009 (UTC)

do protonated alkaloids still taste bitter?

Or is it in fact, the protonated molecule that tastes bitter? John Riemann Soong (talk) 15:26, 5 October 2009 (UTC)

Theobromine tastes bitter as the free base... It's clear that making the salt of an alkaloid increases it's solibility and hence tastability - see quinine tannate as an example of an insoluble quinine salt with little or no taste.83.100.251.196 (talk) 20:14, 5 October 2009 (UTC)

Seeking list of mercury content of fish species

I have not succeeded in my lengthy Google search for a list of the mercury content of a variety of fish species, including things like sardines and the different types of mackeral. I'm looking for the numeric quantitative amounts of mercury, preferably in metric, not just something categorised as low medium or high. Maybe someone could try a different approach to me and find the information please? 78.149.191.96 (talk) 17:37, 5 October 2009 (UTC)

Of course, mercury content will vary by geographic location, especially for freshwater species. Here's a quantitative analysis of a few different fish "types" (well, fish and crustaceans): [1] Franamax (talk) 18:20, 5 October 2009 (UTC)

Also, I nabbed a copy of "Survey of total mercury in some edible fish and shellfish species collected in Canada in 2002" which is the source Health Canada used. You would need to email me to get a copy for your personal use only. Franamax (talk) 18:38, 5 October 2009 (UTC)

And some quant stuff from the US FDA: [2] (eww, catfish ;) I'm just using the gsearch term "mercury content in fish". Also, note the distinction between total mercury and methylmercury when you read this stuff. Methylmercury is way the more dangerous form than inorganic variants. Franamax (talk) 18:49, 5 October 2009 (UTC)

[3] "Many researchers have reported geographic variability in Hg concentrations among commercially important fish and shellfish species. "

Mega table from same link [4]. there's more too. If you wanted data from another area...83.100.251.196 (talk) 19:09, 5 October 2009 (UTC)

For more try "mercury fish mg/kg marine freshwater etc" as a search term.83.100.251.196 (talk) 19:11, 5 October 2009 (UTC)

If I was born on Mars...

What would my astrological sign be? Do you take into account precession of the equinoxes, or no? --99.237.234.104 (talk) 21:40, 5 October 2009 (UTC)

Well they aren't taken into account on Earth... ~ Amory (u • t • c) 21:57, 5 October 2009 (UTC)

That would depend a lot on when you were born, I suppose. Mars can see the same constellations as we can, and Mars' axis is roughly parallel to our own. I imagine the signs would be the same, though the Sun Signs wouldn't line up with the same months as they do on Earth. (In fact, the martian year is a different length, earth months wouldn't line up with the zodiac at all!) APL (talk) 22:12, 5 October 2009 (UTC)

The axial tilt isn't what's important. You want the orbital inclination (which is only about 2 degrees different from Earth's) - that's what determines the path of the Sun against the background stars. Astrology is in no way scientific, though, so this is the wrong reference desk to discuss it on - try Miscellaneous. --Tango (talk) 22:27, 5 October 2009 (UTC)

(edit conflict) Actually, the axial tilt plays an important role in determining which constellations the Sun appears in front. If the Earth were 0˚ or 45˚, we'd see a different range of stars at a given latitude and date. The precession of the axis is not, as I said, taken into account - since the Astrological system was first "defined" the axis has rotated roughly one sign. And I think the question was placed appropriately given the answers have to come from a scientific reason, even if the topic isn't. ~ Amory (u • t • c) 22:41, 5 October 2009 (UTC)

Yes, you would see the stars in different places, but you also see the sun in a different place. It is the sun relative to the stars that determines a star sign, and that is dependant on the planet's orbit around the sun only. The ecliptic (the path the sun takes through Earth's sky) is the project of the Earth's orbit onto the celestial sphere. It depends solely on the orbit. --Tango (talk) 22:44, 5 October 2009 (UTC)

Which constellations the sun crosses your planet's celestial equator in is determined by the heliocentric ecliptic longitude of the point it's axis points to. This determines the origin (the closest point the planet's ecliptic approaches the north celestial pole is 0° mars ecliptic latitude, 90° mars ecliptic longitude) The 0, 0 point is the sun equator crossing that moves north. Whether the pole that's north is the one pointing closest to Earth's north ecliptic pole or the one pointing closest to Earth's North Celestial Pole or the one that rotates counterclockwise when viewed from above.. is ambiguous even in astronomy. So far this is astronomy. I don't know what they'd pick. For Mars this is unambiguous. But not for every planet in the solar system. Naah, they just count the same direction the sun moves, who wants the numbers to go down through the year? North is the one above you when prograde moves left.

They attach great and utter significance to ecliptic longitude twelfths measured prograde from this point, as if these gores eminated mystical powers, oooh. It is one of the three pillars (signs, aspects and houses, which is like signs but for the day instead of the year) So does this mean rotating an axis will render 2000 years of astrological development obsolete? (haha) They'll have to find out everything all over again: Being born 60 to 90 degrees after new equinox makes one grumpy, clinical research studies have increased predictive skill for trait [male libido] due to new finding of a sine distribution centered on 28°16 (+/-2)″ Aries Makemake sign with a peak of 0.0011813796363706844 correlation with secondary peak 0.0008/12°2(+/-3)″Gem/*all95%cnfdncelvl/blablabla superimposed

The axial tilt is least important to them becase it just determines the angle it crosses at. And they don't care about that (you know, changing it even 10% only what like starts ice ages or something?) Sagittarian Milky Way (talk) 04:49, 6 October 2009 (UTC)

The origin is just a coordinate thing, it doesn't affect which constellation the Sun is in, which is (nominally) what star signs are all about. --Tango (talk) 14:34, 6 October 2009 (UTC)

Yes, but the thing is they don't care about constellations, they care about ecliptic longitude twelvths, and you need at a minimum an ecliptic, and a starting point with a direction arrow for that, which is coordinates. Every ecliptic and equatorial coordinate system uses the vernal equinox "prime meridian" by convention. (although there is such a thing as astrology that tries to use the real constellations, it is rare) Sagittarian Milky Way (talk) 04:42, 7 October 2009 (UTC)

No, use of a sidereal zodiac isn't rare at all; it just seems like it to you because of the particular culture you live in. Indian astrology uses the same 12 zodiac signs that you're used to (that came from Hellenistic astrology), but is tied to a sidereal coordinate system instead of an ecliptic coordinate system. Given that there are more people in India than in all of Europe and all of North America combined, it's not immediately obvious to me as to whether a sidereal or an ecliptic coordinate system is used by more astrologers worldwide. Red Act (talk) 05:34, 7 October 2009 (UTC)

I stand corrected. Sagittarian Milky Way (talk) 08:46, 7 October 2009 (UTC)

This is really not a science question. Astrologers really don't give a damn about science - and they are just as likely to make up some kind of crazy answer as they do on any other day. The answer is whatever the nut-jobs say the answer is. Go ask an astrologer...no - better still - go ask three different astrologers and be impressed about how none of their answers will agree with any of the others! SteveBaker (talk) 22:37, 5 October 2009 (UTC)

To amplify Steve's comment here, The sun (from Earth) is very clearly in Virgo right now. Pretty much right in the middle of it. But for whatever reason, September 23 - October 22 is considered Libra's territory. It makes you wonder what planet astrologers are on.

So we can tell you what constellation the sun is in, as seen from Mars, on any particular day. (Right now it's in Taurus.) But there's no telling how that'll line up with whatever standards astrologers come up with.

Hope this helps. APL (talk) 03:09, 6 October 2009 (UTC)

Whoops, wrong direction. The Sun is in Ophiuchus on Mars right now. Sagittarian Milky Way (talk) 04:49, 6 October 2009 (UTC)

It's funny you should mention all that. And it's ironic the OP should ask about the procession of the equinoxes - because, as I understand it, that phenomenon is the reason that the constellations no longer physically align with the astrology charts. It's like refusing to accept the Gregorian calendar, only much worse in terms of the amount of error. So things don't even line up anymore, yet astrologers pretend that they do, which goes to show how bogus it all is. →Baseball Bugs ^{What's up, Doc?} carrots 03:15, 6 October 2009 (UTC)

Just to put Steve's comment into perspective here, I have two medical doctors in my immediate family and I have long amused myself by asking them the exact same medical question and comparing the answers. When I'm feeling especially evil, I ask them both while they're in the same room. It's not just the nut-jobs who often disagree. Franamax (talk) 05:12, 6 October 2009 (UTC)

For a hot second there, I thought you were going to say you ask them to interpret astrology charts. →Baseball Bugs ^{What's up, Doc?} carrots 05:21, 6 October 2009 (UTC)

The difference between the medical doctors and the astrologers, of course, is that we rationally believe that the doctors, while perhaps giving different answers, are trying to pinpoint some actual extant universal and discoverable truth ("these symptoms mean you are pregnant", "this lump is terminal cancer") that will have meaningful real-world outcomes ("in a few months you will give birth", "in a few months you will likely die") unless something intervenes ("unless you miscarry", "unless we begin chemotherapy") and on which both doctors would eventually completely agree given enough critical evidence ("Ah, so, you gave birth!", "Sorry to hear of your passing") whereas the answers given by the astrologers are really more just fun pretend-truths that sound Very Real to Me but Don't Mean Anything Really and are Never Verifiable. What's not okay is when the latter try to pretend that they are the former or are seeking the same kind of universal truths, which is what they do constantly. KDS4444^Talk 21:13, 21 June 2010 (UTC)

• Astrology is not science. --Pykk (talk) 22:47, 5 October 2009 (UTC)

Astrology, and in particular the western astrology you're asking about, is essentially a religion. As such, I think the humanities ref desk would be the correct place to ask this question, since that's the category that covers religion. However, I think SteveBaker's answer hits the nail on the head. What your sign would be depends on which person making stuff up you choose to listen to. There is no scientifically meaningful answer. Red Act (talk) 23:38, 5 October 2009 (UTC)

Given how cold Mars is, it could be the sign of Chillius Willius, the Penguin. →Baseball Bugs ^{What's up, Doc?} carrots 23:52, 5 October 2009 (UTC)

Or the sign of a frozen Snickers bar. Bus stop (talk) 02:24, 6 October 2009 (UTC)

Yep. The problem with the OP's question is that it's based on a flawed premise. Keep in mind, aside from the fact that astrology is hogwash, that it also dates to a time when people thought the earth was the center of the universe, and that everything else (including Mars) orbited around it. Trying to fit astrology to Mars "does not compute". →Baseball Bugs ^{What's up, Doc?} carrots 02:27, 6 October 2009 (UTC)

Utter and compounded nonsense. Edison (talk) 04:06, 6 October 2009 (UTC)

That about covers it. →Baseball Bugs ^{What's up, Doc?} carrots 04:11, 6 October 2009 (UTC)

Not quite ...

First off, axial tilt has nothing to do with what the OP is trying to find out; it is, indeed, the plane of Mars' orbit about the Sun that is the determining factor, just as it is the Plane of the Ecliptic (the plane of Earth's orbit about the Sun) that determines which constellations the Sun appears to be in front of at any particular time. As it turns out, the Ecliptic cuts through 13 constellations, the twelve of the standard Western zodiac plus a corner of Ophiuchus (which the vast majority of astrologers ignore, if, indeed, they've ever heard of it). As there is only a small angle between the orbital planes of Earth and Mars, the Martian zodiac would be very similar, if not identical, to Earth's. (I have not taken the trouble to either research the exact details or figured it out for myself.)

As mentioned by others already, astrologers ignore Precession, discovered by Hipparchus in the 2nd century BC. The dates of the "Sun Signs" that you see in your newspaper were correct in approximately 100 AD, and are now almost a month off. Astrologers also ignore the fact that the constellations are not all the same size and that the segments of the Ecliptic are of different lengths when crossing them. The Sun spends more time "in" some constellations than others. Astrologers ignore this and say that the Sun spends equal time in the various "Signs" or "Houses," and thus where the Sun is in relations the actual constellations doesn't matter. Of course, if one thinks about it, this constitutes an admission that astrology isn't based on the real motions of the heavenly bodies, which was supposed to be the point of it all. As most of us know, there is no scientific validity to Astrology, but by ignoring the actual location of the Sun, planets, and stars, its claims are seen to be empty even by its own standards.

Okay, now, if you still care, here's what to do. Mars' period (year) is almost exactly 687 Earth-days long. Whenever you decide to determine the answer to your question, find out where Mars is in its orbit (not as seen from Earth, but from the Sun). Based on its longitude see what "sign" the Sun is "in" now. Well then, 687 days before then, it was in the same place. You know your age - I don't. Calculate your age in days. Determine what that comes to modulo 687 (just keep subtracting 687s and deal with the remainder). Every 57 1/4 days in the remainder pushes your answer back one Sign.

It's depressing to realize how much effort has been wasted over the centuries on this sort of "utter and compounded nonsense." B00P (talk) 05:42, 6 October 2009 (UTC)

It can be seen as depressing, or it can be seen as funny, as well as giving you a natural feeling of superiority over others, which can be useful. The Martian day is roughly 24 hours, as ours is, but as you suggest, if you want to have a "month" that relates to the 12 signs, then each month is over 50 days long, which probably wreaks havoc with the astrology charts which would expect roughly a 30 day month. For example, Libra would then run from roughly September 42nd through October 40th. Yikes. And to top it off, life expectancy in Martian years would be about 37. Ironically, on Mars, Jack Benny wouldn't have made it much past 39. →Baseball Bugs ^{What's up, Doc?} carrots 06:08, 6 October 2009 (UTC)

It would also wreak havoc with The Fifth Dimension. "When Phobos is in the Seventh House and Jupiter aligns with Neptune..." That doesn't quite work. →Baseball Bugs ^{What's up, Doc?} carrots 06:10, 6 October 2009 (UTC)

That is just a prescription for When it's 2-4 hours after lunar "high noon" and a multiple of 12.8 years from/before ~2009-10 simultaneously". How bout that Fifth Element, that movie is somewhat related to this thread and was awesome. Sagittarian Milky Way (talk) 08:27, 6 October 2009 (UTC)

Some people above seem to be assuming that Martian astrologers will use the tropical zodiac that's currently the most widely used by Western astrologers. The topical zodiac is the version of the zodiac that's tied to the seasons, and hence has shifted from the Hellenistic zodiac due to axial precession. But the sidereal zodiac, which still matches up with the Hellenistic zodiac in terms of the sun's position relative to the constellations, is also in widespread current use, being used by all Jyotish astrologers, and also some Western astrologers. It seems likely that the sidereal zodiac will become relatively more popular on Mars than it is on Earth, as Martian astrologers will be more likely to view the Earth's axial precession as being less relevant to their lives.

Or maybe the increasingly popular 13-zodiac astrology used by Walter Berg will take over by the time there are colonies on Mars, or maybe some zodiac system will be developed by then that hasn't even been thought of yet. After all, Western astrology seems to be a relatively rapidly evolving set of beliefs. The whole modern sun sign astrology, in which only a person's sun sign is taken into account, was invented only 79 years ago (in 1930), for convenience in publishing horoscopes in newspapers. Westerners who aren't heavily into astrology tend to think of astrology as just being the simple new sun sign astrology that's printed in newspapers, but Western astrology is much more complicated than that to the people who are into it heavily. It seems like a good guess that the relative popularity of sun sign astrology will decrease in the future, as printed newspapers continue to decline, and astrology software makes it easy to get predictions that are based on full-fledged Western astrology, which cares about location of birth, and exact time of birth down to the minute.

One reason to guess that the most popular Martian zodiac might wind up being different from the tropical zodiac is because Martian astrology will have to mutate substantially from Earth-bound astrology, anyway. The position of Mars is important to Earth-bound astrologers, but will become irrelevant in Martian astrology. The position of the Earth, which is meaningless in Earth-bound astrology, will presumably take on some significance to Martian astrologers. The position of Earth's moon is very important in Earth-bound astrology, and indeed is the main thing that supposed causes the day-to-day changes in a person's horoscope in sun sign astrology. But the position of the Earth's moon presumably would be given little or perhaps no importance by Martian astrologers.

In short, it's difficult to try to predict the relative popularity of whatever various zodiac systems will be used by Martian astrologers.

And it still seems to me like this was really a question for the Humanities ref desk. Giving astrology any serious discussion here on the Science ref desk sort of feels similar to us doing an in-depth analysis of the aerodynamics of Superman's cape. Red Act (talk) 09:21, 6 October 2009 (UTC)

The irony of switching from sun-based astrology to planet-based is that it could be argued that there is actually a tiny grain of possible truth in the sun-based variety because your star sign correlates to the time of year you were born in. There is indeed some evidence of variation in humans dependent on the season they were born in ([5], for example). It's not hard to imagine that in primitive societies, the diet of the mother during pregnancy would be dramatically different for babies born in summer versus winter...that the amount of vitamin D the baby would produce in the early months of life would depend on the amount of sunlight available in summer versus winter...or that children are more likely to be born in one season than another if their parents are poor versus rich. So it's remotely possible that some vestige of these differences could remain with you throughout your life and perhaps have an impact on you that would be in some way predictable by your star sign. However, if this were truly what the astrologers were doing - their first question should be: "Were you born in the northern or southern hemisphere?"...and sadly, that does not figure into their patter.

However, the Astrologers are clearly not producing their results that way - so they don't get to take any credit for this - and worse still, the more serious amongst them generally prefer the more utterly ridiculous planetary-based version of the pseudo-science over the more plausible sun-based variety anyway.

SteveBaker (talk) 12:18, 6 October 2009 (UTC)

Read Mostly Harmless by Douglas Adams. 66.65.140.116 (talk) 02:34, 7 October 2009 (UTC)

Just to clarify, I don't believe in any of the astrology nonsense. I asked the question partially to mock astrology, partially because I was curious whether Martian astrologers would move one's real sun sign one constellation forward to compensate for the fact that on Earth, the astrological zodiac is behind the real zodiac by one constellation. --99.237.234.104 (talk) 04:52, 7 October 2009 (UTC)

Radiation levels near nuclear reactors

Generally speaking, at what distances is it safe to be near a nuclear reactor? In other words, are the radiation levels (rems/sV) 10 meters from a reactor under normal conditions dangerous? What is the typical distance that workers are from the reactor core itself? I ask because pictures like this make me curious (this one's even better since it's obviously taken by a person). According to this diagram there isn't much between the core and the containing pool. Shadowjams (talk) 23:15, 5 October 2009 (UTC)

I have visited the PULSTAR reactor at North Carolina State University (in the photo you linked) ; we never wore counters or radiation detectors, let alone PPE. It should be noted that it is a very small reactor (50 kW, I think). Surrounding the chamber was a wall made of paraffin brick - the idea being that hydrogen in the long hydrocarbon chains of paraffin would stop neutrons. I have also visited the operational reactor at MIT - again, no counters or protective equipment. In fact, one of the applications at MIT's nuclear reactor is a medical research program for tumor-ablation - they can open a window to the core and expose slow-neutron radiation on to a live human test-subject to irradiate harmful tumors. You can read about their NRL nuclear medicine program at their website (including radiation levels. (That one has a thermal-neutron source flux; you can find data for other types of nuclear radiation elsewhere on the site). Realistically, on a day-to-day basis, inside a nuclear plant there is more hazard from electrocution, steam explosion, or pump malfunction than from nuclear radiation. Even these risks are properly controlled via effective operational procedure, maintenance, and design. Nimur (talk) 23:58, 5 October 2009 (UTC)

There are significant neutrons produced in these research reactors. BUT, with enough water, most of the neutrons will scatter, lose energy, be reflected in, and not be a significant problem, for low-power reactors. This is, of course, assuming no meltdowns and etc. (which in the case of many research reactors is just physically not possible anyway). (Neutrons are scattered very easily by light nuclei—so regular water, light water, or paraffin, end up slowing down neutrons significantly.)

At the MIT Nuclear Research Reactor (which you can tour without any dosimeters, though you do have to be screened before you leave), they tell a story about how they used to use solid tools to change the core configuration once, and the neutrons used it as an easy pathway out (and set off all the radiation detectors). Now they use hollow tools that fill up with water. It sounds counterintuitive that water is a better neutron reflector than steel, but it has to do with the mechanism of the neutrons being scattered (it's not the same thing as radiation penetration, e.g. trying to go through lead).

It's of note that comparing research reactors to the PWR (a power reactor) is not necessarily useful... the sizes are quite different, and the cores are quite different in radiation output. I don't imagine you'd stand that close to a commercial reactor core. Size does matter! --Mr.98 (talk) 00:26, 6 October 2009 (UTC)

Speaking of nuclear power, as opposed to ittybitty reactors at colleges, during normal operation, I would expect high radiation levels near the actual reactor inside the containment building. Someone who works in the field could come up with actual radiation levels. But when it is shut down for maintenance, workers have to be able to go in and physically work on valves, switches, instruments, pipes, wiring, etc. They are very complex systems and require much maintenance during refueling or maintenance outages. When there is a malfunction, like Chernobyl or Three Mile Island, lethal levels of radiation are found inside the containment (like Three Mile Island) or in the surrounding countryside (as at Chernobyl, which had no containment building). In the plant, around the grounds, and near the plant the radiation levels are supposed to be quite low, since people work there. Edison (talk) 16:17, 6 October 2009 (UTC)