Wikipedia:Reference desk/Archives/Science/2007 November 23

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November 23

Apoptosis

If a man goes fishing, we can say "the man has started to fish", if a cell begins the process of apoptosis, what single word (of the same root) is used in the sentence "the cell is has started to ..."? --Seans Potato Business 00:10, 23 November 2007 (UTC)

In your fish sentence you are using the word as a verb. Apoptosis is a noun, so wouldn't be conjugated. The only sentence I can think of is the same as yours: "As the cell dies, it begins has begun the process of apoptosis." Jeffpw (talk) 00:17, 23 November 2007 (UTC)

Apoptosize is a verb form, so you could say "The cell has started to apoptosize." bibliomaniac15 01:04, 23 November 2007 (UTC)

Or Apoptosise... —Preceding unsigned comment added by Shniken1 (talk • contribs) 01:15, 23 November 2007 (UTC)

In the texts I've read, apoptosis is used as a verb, so we say "the cell has started to undergo apoptosis". Looking at root words, though, we also use the word ptosis, specifically in relation to things like eyelids, the liver, etcetera, and we commonly will make a comment during examination of a patient such as "he had a ptosed liver", to say the lower border of the liver is lower than expected in the abdomen (for a number of possible reasons) --- so, then the answer could also be "apoptose". To me, to "apoptosize", as suggested by Bibliomaniac15, or "apoptosise", for those of us who prefer the Queen's English, would be to cause another cell to undergo apoptosis, rather then a cell undergoing apoptosis itself. Mattopaedia (talk) 02:41, 23 November 2007 (UTC)

That sentence uses it as a noun. Using it as a verb would be "the cell has started to apoptosis". — Daniel 02:57, 23 November 2007 (UTC)

Fair enough. I'm a doctor, not a linguist. I was thinking it might have been a noun and a verb at the same time, but thought that was a bit odd, so left it like that. Mattopaedia (talk) 03:53, 23 November 2007 (UTC)

Linguistically, what you're looking for is the infinitive form of the verb: to run, to swim, to play, et cetera. "to undergo apoptosis" is not using apoptisis as a verb; "to undergo" is the verb and apoptosis is the direct object, which is (in this case) a noun. "Apoptosize" would be a verb (assuming it's a word). Kuronue | Talk 21:14, 23 November 2007 (UTC)

But that's the question, isn't it? "Apoptosize" is, at best, a nonce word: it is certainly not in common use, and would not be used in any even minimally formal document. "Apoptosis" is the noun; "apoptotic" is the adjective, and there is no accepted verb form. - Nunh-huh 21:32, 23 November 2007 (UTC)

Funny, I've always use "Apoptose" as the verb. I have no idea if this is at all correct though. Someguy1221 (talk) 21:54, 23 November 2007 (UTC)

To determine whether it is correct or not, consult a dictionary. I already have. - Nunh-huh 22:12, 23 November 2007 (UTC)

I do hear apoptose, although it's probably a word made by extension (e.g. endocytosis-endocytose). However, I'd probably go with constructing the sentence to use either the noun or adjective form. -- Flyguy649 ^talk 22:15, 23 November 2007 (UTC)

The OED doesn't acknowledge apoptosize or apoptose as words. Speaking from experience, I occasionally see apoptose in scientific presentations. It's a nonce word or neologism, and I'd tend to shy away from it in formal writing. (Apoptosize is definitely not used. Anywhere.) A PubMed search finds about a hundred uses of apoptose in paper titles or abstracts, so at least some authors have been able to sneak it past the blue pencils. TenOfAllTrades(talk) 23:42, 23 November 2007 (UTC)

The part of the OED that covers the letter A was last updated around 1970, except for selected important words in the online edition, so that's not a good reference for new words. But none of the online dictionaries indexed by www.onelook.com has "apoptose" or "apoptosise"/"apoptosize" either. I think "apoptose" is definitely the natural form, though. Several other medical nouns in -osis often form verbs in -ose, like "diagnose", "sclerose", and "thrombose". --Anonymous, 01:32 UTC, November 24, 2007.

For what it's worth, the online version of the OED includes references as recent as 2004 for apoptosis and 2002 for apoptotic; it's safe to say that they're making an honest effort to stay on top of these new words—but I would agree that they're not the be-all and end-all for new terms. TenOfAllTrades(talk) 18:26, 24 November 2007 (UTC)

As it happens, I was using "apoptose" when my spellchecker rejected it, the first event in a short series that lead to my original post. Since it clearly should be a verb, I move that we resolve to use it as we see fit, since after all, what makes a word (a word) is how many people use it and understand the meaning behind it. I have a dream, that some day, every process will have a verb form... --Seans Potato Business 19:07, 24 November 2007 (UTC)

Michael Faraday established that magnetism could affect rays of light?

Hi, Michael_Faraday established that magnetism could affect rays of light? What? I thought light is not affected by magnetism. Please explain.

Thanks --InverseSubstance (talk) 02:42, 23 November 2007 (UTC)

Good question! This is what our article on Faraday says - "In 1845, he discovered the phenomenon that he named diamagnetism, and what is now called the Faraday effect: The plane of polarization of linearly polarized light propagated through a material medium can be rotated by the application of an external magnetic field aligned in the propagation direction. He wrote in his notebook, "I have at last succeeded in illuminating a magnetic curve or line of force and in magnetising a ray of light". This established that magnetic force and light were related"

Read the linked articles (showing up in blue), hopefully they will explain better than I can. DuncanHill (talk) 02:49, 23 November 2007 (UTC)

Thanks! Thats amazing. This might be a good time to ask another question I've been curious about. Light waves are usually depicted as a series of - well - light waves. If a light wave is the product of a quantum jump from a higher electron orbital to a lower electron orbital, then how many cycles are there in a light wave train? User:InverseSubstance —Preceding comment was added at 03:24, 23 November 2007 (UTC)

Well, the difference in energy of states in the quantum leap determines the energy of the photon, or $E=h\nu$, where $\nu$ is the frequency of the photon in cycles/sec and h is Planck's constant. Just multiply the cycle frequency by the number of seconds you're generating the wave packet for and boom, you have the number of cycles. The result doesn't have much meaning, however, as quantum mechanics describes a wave packet that has an infinite number of cycles that decay to zero exponentially as it propagates away, so you can think of our calculation as more of the average total number of cycles in a series of wave packets generated with certain frequency over a length of time. SamuelRiv (talk) 03:40, 23 November 2007 (UTC)

Ok - that's interesting. So when an atom absorbs a Photon, the entire wave packet is absorbed, including the entire exponentially decaying amplitudes, right?

I'm also curious about how a light wave can interfere with itself in the Double_slit experiment. The probabilistic Wave_packet can describe it, but not explain it. And I imagine that string theory also does not explain self-interference; it only describes its probability, right? --InverseSubstance (talk) 04:12, 23 November 2007 (UTC)

Classical wave theories of light are sufficient to explain the interference pattern (but not the lack thereof) in the double slit experiment. Basically, two waves diffracting at two narrow slits will interfere in an alternating constructive and destructive way (there are many diagrams of this in double slit experiment.) Light interferes with itself as a wave, but there is also light-to-light scattering (Delbruck scattering) which occurs when a virtual particle is exchanged between photons, similar to how electrons scatter off each other by exchanging a virtual photon. This is a nonclassical effect, but it has nothing to do with the double-slit experiment. SamuelRiv (talk) 05:21, 23 November 2007 (UTC) Addendum: none of this has anything to do with string theory, and string theory explains nothing about light. The best theory we have for light is Quantum electrodynamics (QED). SamuelRiv (talk) 05:30, 23 November 2007 (UTC)

String theory does actually have an explanation for diffraction (not that I can remember it). String theory generally has an explanation for everything, and generally these explanations produce no predictions divergent from quantum, and thus they are indistinguishable from quantum. String theory is in general not worth thinking about, except as an exercise of silliness and ammusing thoughts. Someguy1221 (talk) 05:59, 23 November 2007 (UTC)

An electron in a higher orbital has got a certain lifetime, the average time it needs to fall back to a lower orbital. This lifetime also determines the "number of significant cycles" and hence the coherence length - and, as can be calculated with the Fourier transform, the width of the spectral line (the spectral line is narrower if the lifetime is longer). If the atom is not undisturbed during this lifetime of the electron in the higher orbital, e.g. if it collides with other atoms, then the lifetime gets shorter and the spectral line gets broader - see also spectral line. Icek (talk) 10:48, 23 November 2007 (UTC)

I have long been in awe of Faraday, a man who probably could not have passed freshman high school algebra, showing the relationship betwen electricity and magnetism by discovering induction and transformer action, then discovering the relationship between magnetism and light (magnetism can rotate the plane of polarization of light), and in the end attempting (unsuccessfully) to find a relationship between electricity or magnetism and gravity. He was as tireless an experimentor as Einstein was a theorist. Edison (talk) 05:27, 25 November 2007 (UTC)

Spacetime and FTL

Given that:

• space and time are only two different aspects of spacetime;
• FTL travel is not a possibility which can be ruled out;
• and all matter is essentially composed of photons and leptons;

Is it plausible that photons (which are light themselves) or leptons, do accelerate above the speed of light, but that we cannot detect this phenomenon because the surpassing of this "threshold" transforms them into time? This might be a fallacy, but it seems quite logical to think that there exists a "phase change" which works like this: time <=== photons/leptons ===> matter. Remember there are special quantum effects which allow for a violation of the law of conservation of energy, maybe accelerating above the speed of light would be such a singularity. Is this idea really a fallacy or is it plausible? —Preceding unsigned comment added by Danilot (talk • contribs) 12:04, 23 November 2007 (UTC)

Okay, let's start with your givens, all of which are wrong:

• space and time are fundamentally different in our theory of general relativity, which uses Minkowski space in which a "length" is defined as $s^{2}=c^{2}t^{2}-x^{2}-y^{2}-z^{2}$, which shows that our time t is a separate type of coordinate than our space x,y,z. We find velocity (the time derivative) is then $v\cdot r/t=c^{2}$ which sets a fundamental limit on velocity through space (remember $v=\Delta r/\Delta t$) of c, the speed of light.
• Therefore FTL travel is ruled out in space, but we can still acheive it with a warp drive which bends space itself, or a wormhole which topologically tunnels through space.
• Your link to all matter being composed of leptons and photons is only valid for the very early universe, does not describe matter (only leptons exist in matter, photons "do not", and leptons are not as significant in matter as baryons).

And then your conclusions are also mistaken. Massless particles by definition must travel at the speed of light, and massive particles (like leptons and baryons (matter)) must appear to us to travel slower than the speed of light in vacuum in accordance with quantum mechanics, namely the uncertainty principle. What you are describing is called a tachyon, which travels faster than light by definition (but appear to us to be travelling slower than light, since they are travelling backwards in time. There is a model of antimatter that describes them as tachyons, but I believe there is solid evidence against this description. Anyway, it is a fundamental principle that particles travelling faster than light can never reach light speed, so they can never slow down to become slower than light, and vice-versa, so it does not represent a possibility for FTL travel. Finally, the Law of Conservation of Energy may be locally violated, but not globally violated, so it is always true. SamuelRiv (talk) 13:53, 23 November 2007 (UTC)

I'd like to correct one of those statements:

• Therefore FTL travel is ruled out in space, but we can still acheive it with a warp drive which bends space itself, or a wormhole which topologically tunnels through space.

We can't achieve FTL travel with warp drives or wormholes - current science doesn't say that they are practically possible - we have no idea how we could even theoretically make space warp or tunnel without playing around with black holes and other things that we really have no way to do. At best we can say that perhaps they aren't ruled out as utterly impossible. But with everything we actually know FTL travel is ruled out. Tachyons are not science - we havn't observed them and none of our laws either require or predict their existance - they are purely hypothetical. Annoying though the universal speed limit is, it looks certain that we're stuck with it. SteveBaker (talk) 17:13, 23 November 2007 (UTC)

Here's where I add the usual things I like to say about this: First, if a particle could "move" faster than c it wouldn't really be like motion at all, because in one inertial reference frame it would exist at infinitely many points in space but only one point in time (the opposite of the case of motion). For other reference frames, it would be moving the opposite direction! Second, the limitation of relative speed doesn't actually limit your ability to reach faraway destinations. For example, if you had a rocket that could sustain a 1 g acceleration indefinitely, you could reach any point in the galaxy in a matter of years[1] (of your own proper time, of course), even though the points are hundreds of thousands of light-years apart. You can think of this as being due to length contraction, which causes your destination to appear closer to you as you move toward it, hence easier to reach. —Keenan Pepper 06:05, 24 November 2007 (UTC)

And better yet, by the time you get back all of your favorite shows will be out on DVD! ;-) Someguy1221 (talk) 06:34, 24 November 2007 (UTC)

No, by that time most of the videos that you remember will have been destroyed during the second coming of Jesus.

To respond to Steve, I am well aware that there is no currently existing way to build a "warp drive", but I'm sure you are aware of the hypothetical solutions to the hypothetical problems with these topological types of propulsion. There is no hard evidence for any of it, so it's pretty much assumed that it's all science fiction, at least for now. And as for the tachyon nature of antimatter, I'm not in particle research, so I can't comment on the current state of it, but in general quantum field theory certainly holds this tachyon formulation in high regard (see Feynman diagram). SamuelRiv (talk) 06:50, 24 November 2007 (UTC)

Shared blood system

Ok it is stretching it but for the sake of fiction: how realistic would it be (if possible at all) to artificially link two normally constituted persons so that they share the same cardiovascular (bi-cardiovascular?) or blood circulatory system (the blood would go through both persons to do a full circulation)? In the some order of ideas let's imagine a situation where someone is really messed up under the neck and the only way to save him/her would be to tap the head's blood system into the jugular veins of the healthy person. How would the heart cope with the extra strain and how much is the blood compatibility an issue? Is it completely irrealistic or merely highly implausible? Keria (talk) 15:48, 23 November 2007 (UTC) p.s. this question is dedicated to Zaphod Beeblebrox :p

Check out Conjoined_twins#Types_of_conjoined_twins, as thoracopagus twins have a high mortality rate. However, if one twin is parasitic, as an attached head would be, it shouldn't be too much extra strain. SamuelRiv (talk) 16:50, 23 November 2007 (UTC)

A fat person's heart and lungs can keep a large amount of extra tissue supplied with blood and oxygen for years, so supplying an attached head wouldn't be an issue that way. However, establishing the connection would obviously involve major surgery, and there'd be major stress on the artery and vein that were "tapped", as the load on it above and below the junction would be different. Still, in principle the surgical hazards and techniques shouldn't be much different than with an artery bypass.

A severed head might have blood-supply problems in the area of the cut, because some small areas were previously supplied by vessels branching from below the cut, so there could be a risk of gangrene. However, similar issues must arise with amputations generally, so I guess that also ought to be manageable.

The whole-body thing that's also asked about seems much more problematic. --Anonymous, 22:54 UTC, November 24, 2007.

Blood type would, of course, have to match. And even so, there would be problems with each (partial?) person's immune system attacking the other person. But given that organ transplantation exists with usually-adequate rejection control, I suppose it's a reasonable-enough idea for a work of fiction.

Atlant (talk) 15:55, 26 November 2007 (UTC)

definition of latitude

On the surface of an elliptical body, the line through the center of mass and the line of local gravity coincide only at the equator and the poles. So, which one defines latitude? —Tamfang (talk) 19:58, 23 November 2007 (UTC)

You may want to check out types of latitude. In short, you don't have just one measure of latitude. And, since real celestial objects don't have a perfectly elliptical shape, you may also consider gravitatorial deviations of the plumb line (the so called astronomical latitude). Pallida  Mors 20:09, 23 November 2007 (UTC)

To be a bit more specific, you have (at least):

• The geodetic or geographic latitude, (which you may consider the "main" latitude), given by the angle formed between the vertical line normal to the ellipse, and the equatorial plane. As far as I know, this accounts for the "local gravity" reference you gave.
• The geocentric latitude, which is given by the angle between the equatorial plane and a (straight) line joining the local point and the center of the ellipse (the line through the center of mass you metioned in your question.

You have other latitudes explained in the article. Most of them refer to projection topics. Pallida  Mors 20:48, 23 November 2007 (UTC)