Wikipedia:Reference desk/Archives/Science/2008 November 29

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November 29[edit]


can caffiene be smoked? —Preceding unsigned comment added by (talk) 02:23, 29 November 2008 (UTC)

In the world of shisha there are ads for blends of caffeinated tobacco. I don't know anything about the actual dosage or effect. ---Sluzzelin talk 06:10, 29 November 2008 (UTC)

I can think of at least three other alkaloids – nicotine, morphine (as opium), and cocaine – that are smokable, which suggests that it's possible, but I know of no instances where caffeine is subjected to the same process. I would strongly advise against attempting it, however. Seriously. Caffeine overdoses can be fatal. – ClockworkSoul 08:18, 29 November 2008 (UTC)

I agree, we should be looking for ways to make smoked drugs into something edible, like coffee, instead, as smoking anything causes lung cancer. Pass the special brownies and grow those tomacco plants, please. StuRat (talk) 14:33, 29 November 2008 (UTC)
It is not true that “smoking anything causes lung cancer”. --Mathew5000 (talk) 15:23, 29 November 2008 (UTC)
Well, whilst I don't agree with the certainty with which StuRat stated it, it's kind of true that smoking (not inhaling) anything can cause cancer. When you smoke, you burn something, almost always inefficiently. When you do this, you produce carcinogens. Carcinogens cause cancer. —Cyclonenim (talk · contribs · email) 16:25, 29 November 2008 (UTC)
(ec) It's a pretty good approximation to 'true', however. Burning just about any organic material at low temperatures generates a number of carcinogenic products of incomplete combustion; this includes nasty polycyclic aromatic hydrocarbons like benzo[a]pyrene. I suppose that for some smoked products the user does not typically inhale particularly deeply, providing a modest amount of protection to the lungs; in those cases carcinogens would be largely deposited in the nose, mouth, lips, and throat, leading to oral and nasopharyngeal cancers. TenOfAllTrades(talk) 16:40, 29 November 2008 (UTC)
You are arguing that smoking anything should cause cancer, theoretically. But empirical data refute the claim; a 2006 study found no statistical association between smoking marijuana and lung, head, or neck cancer.[1][2] --Mathew5000 (talk) 19:16, 29 November 2008 (UTC)
It's rather dangerous to rely on a single study to draw a conclusion. Your remark could just as easily have said – correctly – that "a 2006 study found a statistically-significant association between smoking marijuana and lung cancer": PMID 18238947. Looking at PubMed, the best I can say is there's not a good scientific consensus one way or another. I don't see any clear-cut results from the last couple of year's publications, and there's a review in Arch. Intern. Med. that summarizes the data up to 2006 pretty well: PMID 16832000. Essentially, there's good data to support the conclusion that heavy marijuana smoking is linked to a number of clinical and histopathological markers of premalignancy, but the step to a demonstrated increase in lung cancer (or not) isn't there yet. Most of the studies I've looked at today don't seem to be sufficiently large or well-controlled. My two cents. TenOfAllTrades(talk) 20:14, 29 November 2008 (UTC)
I think it's also fair to compare the level of exposure that a "heavy" marijuana smoker gets to the amount that a "heavy" cigarette smoker when considering carcinogenic effect. I've known plenty of people who smoke 40 cigarettes a day (2 packs), but I've never met anyone who smokes 40 joints per day. --Sean 20:42, 29 November 2008 (UTC)
Agreed. While I stick by my claim that all smoking causes cancer, most pot-heads may be lucky enough to be below the exposure level which would cause a statistically-significant effect that can be easily measured. StuRat (talk) 18:03, 30 November 2008 (UTC)
It's also possible that smoking tobacco exposes a person to more or more powerful carcinogens then smoking marijuana dosage being equal. This doesn't imply that all smoking causes cancer is wrong Nil Einne (talk) 11:43, 1 December 2008 (UTC)

Cannabis & lung cancer[edit]

This case-control study suggests a link between the two. There are many potential reasons why this link might be less obvious than the tobacco–cancer link:-

  • Cannabis smoke has less carcinogenic effect than tobacco smoke. This article indicates reasons for this. Interestingly, cannabis smoke contains anti-carcinogenic chemicals
  • Cannabis users smoke comparatively less cannabis than tobacco smokers smoke tobacco
  • Cannabis smoke inhalation is less deep than tobacco smoke inhalation, so carcinogen exposure is reduced
  • Cannabis smokers tend to be younger, at an age when the risk for tobacco smokers is also low
  • Many cannabis smokers also smoke tobacco. Thus the effect of cannabis is partially masked by that of tobacco
  • In many countries, smoking cannabis recreationally is illegal. As a result:-
    cannabis users may be more reluctant to volunteer for studies, hence smaller studies
    cannabis smokers may not be truthful about the quantity used
  • Systematic bias, including recall bias

Axl ¤ [Talk] 10:28, 2 December 2008 (UTC)

Cost of an additional degree of heating[edit]

Let's say the average temperature outside is 30 °F. Now, let's say that someone can tolerate an indoor temperature of 70 °F but feels better with, say, 71 °F, and would feel even more comfortable with 72 °F or 73 °F. For a single-room studio apartment, how much more will it cost to heat that additional one degree over a month? Just a little bit, or a lot? What about an additional, say, two degrees? Or three? Basically, I'm trying to figure out whether it's worth it to turn up the thermostat or just keep shivering or wearing uncomfortably bulky clothing to save on heating costs. —Lowellian (reply) 04:28, 29 November 2008 (UTC)

The monetary answer depends strongly on how well insulated the apartment is. In general, conductive heat loss is directly proportional to the temperature difference, so if you have a 40° F difference between inside and outside then increasing it by 1° F will make you lose heat 41/40 = 1.025 times as fast. Which means using ~1.025 times as much heating and increasing your bill ~2.5% from what it otherwise would be. Most other factors (such as convective heat losses if you have a draft, or secondary sources of heating) will tend to imply this a lower limit, and the actual cost increment could be higher. Dragons flight (talk) 05:49, 29 November 2008 (UTC)
Please ignore Dragons flight's answer. It's completely incorrect. Heat loss isn't "directly proportional to the temperature difference"...Heat loss increases as the SQUARE of the temperature difference (per Newton's law) - which is why turning your thermostat down by a small amount produces much bigger gains than you'd expect. So going from 40 to 41 is a 5% increase in cost - not 2.5%. Read what I wrote below. SteveBaker (talk) 14:36, 29 November 2008 (UTC)
Steve, are you sure it's the square and not, as User:Dragons flight says, "directly proportional"? According to Wikipedia's article on heat transfer, "Newton's law of cooling, states that the rate of heat loss of a body is proportional to the difference in temperatures between the body and its surroundings, or environment." —Lowellian (reply) 19:17, 29 November 2008 (UTC)
Not an answer but a tip: if you sit still for a longer period of time, instead of warming the whole apartment you could buy an electrical foot warmer. I use one and I find that with warm feet, my whole body stays warmer. Lova Falk (talk) 09:17, 29 November 2008 (UTC)
Counter-tip: wool socks aka "boot socks". I keep a pair laying by the couch, if I'm feeling cold I put them on. You're absolutely right that keeping the feet warm is a big part of the puzzle. Franamax (talk) 12:02, 29 November 2008 (UTC)
The thing is, once my feet are cold, no socks can make them warm again. It rather feels as if the socks insulate the icy skin of my feet. I've heard that alternating foot baths (that is, alternating hot and cold water) do wonders for cold feet, but it is way too much hassle. Lova Falk (talk) 15:56, 29 November 2008 (UTC)
Because we don't know how efficient your heater is - or how well your house is insulated - or how much electricity/gas costs where you live - we can't answer the question as a direct amount of money. What we can do is tell you how much your electricity/gas bill will increase as a percentage of whatever you're paying now. Newton's law of cooling says that the rate at which heat is lost increases as the square of the difference in temperature between the inside of your house and the outside air. That fact is true regardless of the amount of insulation you have - or how your heating system works. So when the temperature outside is (say) ten degrees below what it is inside - then you are losing ten-squared=100 "units" of heat - which your heater has to replace using 100 "units" power you have to pay for (I'm being deliberately vague about what a "unit" is because that depends on all of those things that we don't know). If you increase the thermostat setting by just one degree then the difference is 11 degrees and you'll lose eleven-squared=121 units of heat. So the cost of increasing by one degree in a 10 degree temperature difference is to add 21% to your heating bill! However, if the weather outside is just one degree below your thermostat setting (1x1=1 unit of heat loss) - and you increase the thermostat by 1 degree then your (very small) 1 unit heating bill will go up to 2x2=4 units! Your heating bill will quadruple in a 1 degree temperature difference. (But then it was such a small bill in the first place - you may never notice).
As the temperature difference between inside and outside get bigger (eg because the weather got colder) then the cost of adding one degree gets smaller. If you live in deepest Alaska and the outside temperature is zero degF and you keep your home at a toasty 70 degF then you are already using 70x70=4,900 'units' of heat...if you wind the thermostat up one degree in that situation then you'll be using 71x71=5041 'units' - which is only about a 3% increase in your heating bill.
Insulation and having an efficient heater are vitally important because they reduce the cost to you (and to the environment) of adding one 'unit' of heat to your house.
The same rules apply when airconditioning a house too.
SteveBaker (talk) 14:31, 29 November 2008 (UTC)
Newton's law of cooling is linear not quadratic. Please ignore Steve's answer. It's completely incorrect. Dragons flight (talk) 22:02, 29 November 2008 (UTC)
From Physical Calculations (J.J.Tuma, c.1983), Sec. 6(6) Overall Heat Transfer, (a) Wall Transfer: quantity of heat Q transferred in the interval t through three stages is Q = A(Ta - Tb)t divided by (rec(h1) + rec(k) + rec(h2)) where A = transfer area, Ta, Tb are internal and external temperature, h1 and h2 are convection coefficients (air space) and k is thermal conductivity of the wall. (Sorry I haven't figured out <math> yet, also rec(x)=1/x) This implies a linear relationship (Ta - Tb), but then we need to examine k. My impression was always that thermal conduction varied with e (-kT), so I'd be interested in a resolution here. Franamax (talk) 01:58, 30 November 2008 (UTC)
And I might be wrong on the minus, and it should be a delta-T that I'm completely wrong on - so you can understand my complete confusion on this. :) Franamax (talk) 02:10, 30 November 2008 (UTC)
The rate of cooling, dT/dt, is indeed proportional to the temperature difference:
dT/dt = -k(T-T0), where the negative sign indicates temperature is decreasing
e^(-kt) can easily be found by rearranging the equation and integrating to solve for T:
dT/(T-T0)=-k dt
ln (T-T0)=-kt + C
T = (Ta-T0)e^(-kt) + T0, where Ta is the initial temperature of the cooling object
It is the temperature of an object left to cool that obeys this equation, not the rate of heat exchange. Since this rate is what matters in the case of a room being maintained at a constant temperature, the power spent by the heating unit should be linear, not exponential. --Bowlhover (talk) 05:35, 30 November 2008 (UTC)

I've been away from the Reference Desk for awhile, and when I return, I'm disappointed to see it devolve into this. "...please ignore the previous answer"... "...complete and utter nonsense..."... Reference Desk regulars, let's keep in mind that this is the Science Desk. There is no reason to ignore anything - incorrect or inaccurate discussion can still be educational - if nothing else, it shows that smart people can disagree about precise factual claims; more precision leads to more squabbling over the details. Let's not forget that Newton's Law of Cooling, like all other laws of Science, are mathematical generalizations based on empircal data. Models are not always correct; and they are very often inapplicable. Before throwing the differential equations around, it would be more productive to consider this situation qualitatively. Raising the thermostat will cause the furnace to turn on more often. How much more often? It will depend on the rate of cooling, and it will also depend on the differential rate of efficiency of the furnace to re-heat the room. (I suspect that turning on the furnace entails "overhead" - so heating from 70 to 71 degrees may actually take negligibly less energy than heating from 65 to 71). The consequence of this result is that the range of the thermostat's dead-zone has a bigger impact to the heating budget than small variations on the temperature setting. The total on-time of the furnace (and hence, the bill) might not change much for a single-degree change on the thermostat dial. Nimur (talk) 02:53, 1 December 2008 (UTC)

Copied from Steve's talk page:-

It looks like I had a "bad memory" day! I think Dragon's flight is correct - my apologies.

— SteveBaker

Axl ¤ [Talk] 19:40, 2 December 2008 (UTC)

THC absorption (repost)[edit]

Reposting removed question (see Wikipedia talk:Reference desk#Removed medical advice (THC absorption)). Zain Ebrahim (talk) 11:43, 29 November 2008 (UTC)
Ages ago, I learned (from somewhere, heck if I can remember) that when smoking marijuana, it is more effective to "hold it in" for as long as possible after inhaling to maximize the amount of THC taken in. Now... is this tactic effective? Does holding it in increase the amount of THC intake versus a quick inhaling followed quickly exhaling (as in "regular" breathing)? I guess an effective way to test this would to smoke same amounts of the same strain of marijuana with the same method of delivery over an identical period of time in each test on different days... except, there are other variables involved (food in the system, surroundings and comfort, mood, etc) and it may prove difficult to properly record or quantify any results (it's a lot of work for a part-time stoner to try and process with any consistency while under the influence). --Abin Sur (talk) 17:32, 24 November 2008 (UTC)

From the literature circulated in my church group, something like 90% of cannabinoids are absorbed immediately in the inhalation process. Brief holding-in would increase the absorption to some degree. Holding your breath for any amount of time will tend to reduce your blood oxygen, which could enhance the effect - however holding in the smoke is mostly part of the ritual, since it proves you're not being greedy and over-toking. Anyway, that's what I've heard at my church group, I never touch the stuff myself :) Franamax (talk) 11:54, 29 November 2008 (UTC)
According to "Cannabis in medical practice" [3], holding your breath for up to ten seconds increases absorbed THC, but not any longer than that. Also, holding your breath for longer increases exposure to tar and carbon monoxide. Fribbler (talk) 15:07, 29 November 2008 (UTC)
You're right, Abin Sur, your query did not run afoul of any applicable guidelines; its removal was unwarranted. If I recall correctly what I've read, THC absorption drops off sharply after five seconds or so. There are some high-quality references in Volcano Vaporizer, some of which address this what you're curious about. —Scheinwerfermann T·C17:49, 29 November 2008 (UTC)

Hydrogen peroxide and yeast[edit]

When mixed together do they react or is the hydrogen peroxide a catalyst for the yeast? —Preceding unsigned comment added by (talk) 15:15, 29 November 2008 (UTC)

Oxygen is released because of the yeast's catalase enzyme. Catalase breaks the peroxide into hydrogen and oxygen. Fribbler (talk) 17:41, 29 November 2008 (UTC)
While true, there won't be a great deal of catalase in the yeast medium. Peroxides, including hydrogen peroxide, are actually somewhat toxic at the cellular level, and won't be very good for yeast cells. – ClockworkSoul 18:00, 29 November 2008 (UTC)

Food Safety[edit]

This question relates to a prior discussion, now archived. Wikipedia:Reference desk/Science#Why is refrigeration of tin a bad idea?

Are food cans sealed with solder that contains lead? I understand from our article that they once were. Are they still?

Thanks. CBHA (talk) 17:37, 29 November 2008 (UTC)

No, they aren't soldered at all any more. StuRat (talk) 18:39, 29 November 2008 (UTC)

Plant Propagation[edit]

What factors (physical, biological, genetic) affect the ability of a plant cutting placed in water to grow roots.

Soft-tissue plants such as Saintpaulia, Coleus root very readily. What are the issues with tougher plants, and can they be overcome?

Just for example, I'm trying to root Schefflera cuttings (not because I need another Schefflera, just to see if it can be done.) After about five months, they still look healthy but there is no sign of growth. Ficus cuttings, put in water at the same time, have small roots.

Thanks, CBHA (talk) 18:43, 29 November 2008 (UTC)

Have you used that hormonal rooting powder? SteveBaker (talk) 20:32, 29 November 2008 (UTC)
Yes, it was used on the Schefflera and the Ficus. CBHA (talk) 20:35, 29 November 2008 (UTC)

Thanks for your responses. I guess I did not make my question clear. What was revolutionary with the surgery she performed was not that she did it from a remote location or even the technology that made that possible. Instead, what was revolutionary was the innovative nature of a surgical technique she devised to conduct the surgery. It's a technique that she apparently perfected and which is not on record as having been performed before anywhere in the world.

PlatoSelfstarterone (talk) 19:40, 1 December 2008 (UTC)

Ground-breaking Cardiac Surgery Technique.....[edit]

A female doctor from Michigan devised a new heart repair surgical procedure. She remotely (from her home), led and directed a team of other surgeons at a San Diego hospital, to perform the surgery on a 26 year old male patient. The surgery was performed sometime in November 2007. It was even rumored that the new procedure might be named after her. Does anyone out there know the name of this doctor and the name and/or type of procedure she performed?

PlatoSelfstarterone (talk) 19:12, 29 November 2008 (UTC)

2007 seems a bit late for that to be terribly ground-breaking (unless the innovation was that she did it over dial-up :) ). See Remote surgery. --Sean 20:45, 29 November 2008 (UTC)
The technology used is shown here. It is revolutionary.  ;o) CBHA (talk) 20:59, 29 November 2008 (UTC)

Feeding the seagulls[edit]

I was throwing bits of stale bagguette to a seagull this afternoon. I suppose that they were too hard or rough for him to swallow because every time I threw him a chunk, he'd pick it up, take it over to a puddle, swish it around in the water a bit until it was all soggy and soft and then swallow it and come back for more.

Has anyone else seen seagulls do this, or is this something that this one seagull has figured out on his own, do you think? -- (talk) 19:32, 29 November 2008 (UTC)

I've seen ducks do the same thing. --Tango (talk) 19:34, 29 November 2008 (UTC)
I can't answer your question but I'm surprised by it. My experience is that if I feed one seagull, approximately 83 others appear. CBHA (talk) 19:38, 29 November 2008 (UTC)
This one was already pecking around in my garden for worms or something before I fed him. I don't think that the other gulls saw him eating the bread. -- (talk) 19:48, 29 November 2008 (UTC)


Is there an easy way to find out which universities offer a degree in Psychoneuroimmunology? Also when such degrees first became available?

Would such a degree be a Doctor of Medicine degree or a Doctor of Philosophy?

Thanks, CBHA (talk) 19:42, 29 November 2008 (UTC)

I believe such specialism is only possible after studying a medical degree such as an MD, MBBS etc. I don't think there is a specific degree in psychoneuroimmunology but rather you train to become a psychoneuroimmunologist, like an immunologist or neurologist. Therefore, you would be a Doctor of Medicine. The specialism has existed for around 40 years. —Cyclonenim (talk · contribs · email) 20:06, 29 November 2008 (UTC)
While there will be doctors specialising in it, there will probably also be researchers with PhD's working in the field too having done their first degrees in pharmacology, (bio)chemistry, psychology, etc. (and then specialising for their PhD and subsequent work). It's also not uncommon for people to have both an MD (or equivalent for their country) and a PhD if they are involved in medical research. --Tango (talk) 22:54, 29 November 2008 (UTC)

Please Be Patient And I Thank You For Your Time[edit]

Awhile back, I believe some people did not take this seriously, so I am hoping everyone will taking this 'question' seriously (this time around).

I also want to give notice to this because this was some new information that had not be included. I humbly thank you. (talk) 22:18, 29 November 2008 (UTC)

We attempted to give you a serious answer and you refused to accept it. Our answer isn't going to be any different this time - chest hair is perfectly normal and there is absolutely no reason to believe it is a recent phenomenon. --Tango (talk) 23:01, 29 November 2008 (UTC)
I see absolutely no reason to suspect that any hair on your chest is unique to you or unique to the last 100 years. -- (talk) 01:10, 30 November 2008 (UTC)
As before and before that... If you believe you have some sort of physical problem, this is a medical issue. See a doctor. If this is not important enough to you to see a doctor, you must not consider it truly unique or special - so why should we? -- kainaw 01:17, 30 November 2008 (UTC)
Yes, such hair is absolutely normal. When you get old, you can also look forward to hair growing out of your ears and eyebrows that never stops, too. It seems this hair was put there primarily for God's amusement. StuRat (talk) 02:37, 30 November 2008 (UTC)
Evidence that not all hair is entirely useful: [4]. Sometimes, hair just gets in the way. 03:42, 30 November 2008 (UTC)
. . .indeed it does [5]
I think I finally understand what the questioner is trying to ask, but has failed to do so properly. He appears to be under the impression that he has some special kind of pubic hairs on his chest. Also, he appears to be under the impression that chest hair in general is a recent step along the evolutionary ladder. So, since short chest hairs are recent and he now has big chest hairs, he must be one step past the rest of the world on the evolutionary ladder. In fact, he is no longer a simply homo sapien. He is a completely new species, perhaps a homo pubicium. -- kainaw 14:05, 1 December 2008 (UTC)
Pubic hairs do often follow shortly after walking erect. :-) StuRat (talk) 00:51, 2 December 2008 (UTC)
What about this guy Image:Chesthair.jpg. Is he homo pubicium? I was under the impression the OP thought his chest hair growth may be related to plastics. Wouldn't that make him the first mutant human like you see in all the shows? Nil Einne (talk) 19:46, 2 December 2008 (UTC)
To the OP, did you ever look at Chest hair? It mentions studies which have looked at chest hair patterns. While 4 appear to be common, the are a lot of other less common patterns. If you read the studies, you may find people with similar patterns to yours, and this is with studies with a relatively small sample size. You can bet your ass (or hair) there are a lot more patterns that are less common. Also I can't remember if anyone told you this before but you do realise humans desceded from an ape which was hairy as with most other non-human apes alive today right? While it's possible chest hair arose in humans, far more likely for whatever reason (e.g. sexual selection) we didn't lose all our hair and retained some on our chest (amongst other places). Also the article links to [6] which goes a bit into a putative mechanism of what causes chest hair to develop. In case it's not obvious, this sort of thing doesn't happen overnight Nil Einne (talk) 19:59, 2 December 2008 (UTC)

What does "higher mammal" mean?[edit]

Is it related to their ability to think or some other classification? Can you point out a sample list of these animals? Thank you =) Louis Waweru  Talk  22:59, 29 November 2008 (UTC)

I've never heard of a strict definition of the phrase, it's usually used quite loosely. I think it usually refers to intelligence, at least partially - humans and primates would almost certainly be included. Intelligence is very difficult to define, though, which makes such a classification pretty much useless for any serious work. --Tango (talk) 00:05, 30 November 2008 (UTC)
It could also mean placental mammals, as opposed to marsupials and monotremes. StuRat (talk) 02:32, 30 November 2008 (UTC)
It is usually used to refer to the most intelligent mammals: apes. Axl ¤ [Talk] 10:05, 2 December 2008 (UTC)
Heheh, okay. I get the idea[s]. Louis Waweru  Talk  18:28, 2 December 2008 (UTC)

Accession number needed for BLAST[edit]

I would like to compare the gene sequences of PCAF and GCN5 (Homo sapiens, both) using BLAST. BLAST requests accession numbers. Here is the page of the NCBI entry for PCAF: [7] - it gives the number 8850. When I use this number in NCBI BLAST, it using a different gene sequence (something unrelated to PCAF. Why is this? Where is the correct accession number? --Seans Potato Business 08:00, 30 November 2008 (UTC)

When I click on the link, I see a page for KAT2B, which I see is also known as PCAF. Is that not what you get?CalamusFortis 01:33, 30 November 2008 (UTC)
Also, here is the data for GCN5, also known as KAT2A. [8] CalamusFortis 01:38, 30 November 2008 (UTC)
Well thanks; that's fine and dandy, but I need accession numbers that I can put into NCBI BLAST. I don't see them on those pages. --Seans Potato Business 08:00, 30 November 2008 (UTC)
I think I may have found what you need. At the very bottom of the page for the genes, there is a number associated with the nucleotide sequence. For PCAF, it's AC099057. For GCN5, it's AC105024.8. Could that be what you need?CalamusFortis 15:30, 30 November 2008 (UTC)

Lipid and Phosphate Granules[edit]

On your diagram of a section through a yeast cell on the yeast article, within the cell are two granules, one lipid and one phosphate. What do these granules do and is there any significance to the phosphate granule being within the vacuole.

Thanks in advance (talk) 23:42, 29 November 2008 (UTC)

If nobody here rises to the occasion with an answer, you may want to post this Q on the yeast talk page, instead. StuRat (talk) 02:29, 30 November 2008 (UTC)
The lipid granule is a storage facility, and the phosphate granule is an artifact of preparation, see D A Orlovich and A E Ashford at . When the cell is sliced, calcium ions leak into the vacuole that contains pyrophosphate ions, precipitating insoluble substances. Graeme Bartlett (talk) 09:38, 3 December 2008 (UTC)