Wikipedia:Reference desk/Archives/Science/2009 April 6

Science desk
< April 5	<< Mar | April | May >>	April 7 >

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.

April 6

Boredom

Is it possible, either biologically or psychologically, to be literally bored to the point of death? I don't mean brought to the point of suicide, but sort of losing the will to live without being taken by any specific other cause. —Akrabbim^talk 01:28, 6 April 2009 (UTC)

It seems unlikely. We know that there are people have been kept in solitary confinement for many years (Richard Wurmbrand, for example - suffered extremes of this horrible torture for 14 years) - they suffer mental symptoms - but they don't die (at least, not from boredom). SteveBaker (talk) 03:18, 6 April 2009 (UTC)

Lightweight! These guys did 36 years of solitary in lovely Angola Prison. --Sean 14:02, 6 April 2009 (UTC)

According to this book and other places, it is believed that babies in orphanages die when they are not given any tactile stimulation. However, I haven't been able to find anything more concrete. I vaguely recall reading somewhere about the investigation of two orphanages in Victorian England; the one that was better financed supposedly had a 100% death rate because the caregivers were trained in the latest Victorian theories (i.e. no touching), while in the other, the adults received little or no instruction and interacted more with the babies, so some of the kids survived. I have no idea if this is true or just a story. Clarityfiend (talk) 06:00, 6 April 2009 (UTC)

You might find Atul Gawande's recent article in the New Yorker about solitary confinement enlightening on this point. --98.217.14.211 (talk) 14:16, 6 April 2009 (UTC)

Interesting, thank you. The defining factor here seems to be interpersonal interaction, rather than mere lack of activity. —Akrabbim^talk 15:53, 6 April 2009 (UTC)

RNA polymerase

How does RNA polymerase selects the DNA strand for transcription? —Preceding unsigned comment added by Mmpdsetti (talk • contribs) 03:13, 6 April 2009 (UTC)

• You want to read Transcription_(genetics)#Initiation. Basically, the RNA polymerase recognizes a promotor that is bound on a specific part of the RNA. Perhaps the 5'and 3'ends of the RNA fooled you into thinking the RNA strands were palindromic? = Mgm|^(talk) 08:04, 6 April 2009 (UTC)

since shorelines are fractal, how are they really (IN FACT) calculated, when we read figures about x miles of shoreline?

We often hear that shorelines are "fractal" -- which makes sense, since what would make them straight? But how then are the data for x miles of shoreline in FACT calculated? Do you just go inland until you CAN get a straight line, and just cut off many many many factors of jutting edges or what? THank you. —Preceding unsigned comment added by 94.27.225.22 (talk) 08:26, 6 April 2009 (UTC)

One possible method (which I believe is used) is to approximate the shoreline by a polygonal curve with each side about the same length. Of course, the result you get from this depends strongly on the length you choose for the sides, which is why different authorities often give wildly different figures for the lengths of coastlines and other non-straight borders. Algebraist 08:50, 6 April 2009 (UTC)

(after ec): Dr_Dima hypothesis number n+1: People who understand what a fractal is, and people who assign "shoreline length" a definite numerical value, form two non-empty disjoint (non-intersecting) sets. Seriously now, this reference explains how shoreline length is "measured" in practice. As expected, the word "fractal" is never mentioned, and neither is the systematic increase of the result with map resolution. --Dr Dima (talk) 09:00, 6 April 2009 (UTC)

Shorelines aren't truly fractal anyway. People like to imagine "shore line" as a fractal that is coherent all the way down to individual grains of sand. But really, even if you're standing on a beach, you'd be hard-pressed to draw a line in the sand at the "Shoreline". Not because of the infinite precision needed to describe a fractal, but because the ocean and even the beach itself are constantly in motion. Beyond a certain point there isn't any more precision to measure.

I'd wager that nowadays, It's entirely possible to define the length of a coastline with enough precision that the "fractal nature" of the coast doesn't make any difference.

How often this is done, I don't know. APL (talk) 13:40, 6 April 2009 (UTC)

That could introduce new problems, as the length of the shoreline changes when the tides goes out, and also after every storm (if a sandbar is connected or disconnected from the shore, does that change the length of the shoreline ?). StuRat (talk) 17:07, 6 April 2009 (UTC)

Exactly, what you're dealing with is an average. It doesn't make sense to talk about the fractal nature of an average. APL (talk) 20:26, 6 April 2009 (UTC)

I think it does. There's one fractal when the tide is out and another when it's in, and we'd average those. StuRat (talk) 19:42, 7 April 2009 (UTC)

well you know what people OUGHT TO DO? Just DRIVE DOWN THE SHORE, there is ALWAYS an easy way to drive along the shoreline, and just measure the difference the odometer shows at the end! 94.27.194.165 (talk) 15:45, 6 April 2009 (UTC)

That wouldn't work for fjords. I blame Slartibartfast. Gandalf61 (talk) 15:50, 6 April 2009 (UTC)

See Coastline paradox. --Heron (talk) 18:25, 6 April 2009 (UTC)

Easily solved. You drive an infinitesimally small car. Confusing Manifestation(Say hi!) 23:15, 6 April 2009 (UTC)

But wouldn't it take you an infinite amount of time to drive it around the coast? All of those tedious detours around sand grains...I bet you'd cheat and take shortcuts. SteveBaker (talk) 01:58, 7 April 2009 (UTC)

How about using the shortest path between the low-tide and high-tide lines? —Tamfang (talk) 05:20, 7 April 2009 (UTC)

Comorbidity of pulmonary and liver diseases

Hello. I'm trying to help out a friend who's studying Medicine to solve a medical case. I'm not going to give all the details of the case that's been assigned to her (lest you believe I am looking for medical advice), only those I believe are the most important. The pacient has rales, coughs and other pulmonary symptoms. The pacient also has abnormal liver test results, such as high GGT and alkaline phosphatase levels.

As I said, I am not going to ask for a specific diagnosis, but I would greatly appreciate if someone can give us a little push in the right direction, since we have been unable to find any disease which would cause both pulmonary and liver symptoms. Thanks a lot. Leptictidium (mt) 09:41, 6 April 2009 (UTC)

Chronic liver disease can present with numerous respiratory symptoms, see hepatopulmonary syndrome, though I'm not sure if that's mentioned in your case. In addition, in can result in elevated GGT levels, but I'm not sue about alkaline phosphatase levels. I'm not saying this is your answer, I'm not a doctor, but this is a logical option to consider. Cyclonenim :  Chat  10:43, 6 April 2009 (UTC)

Have you considered alcoholism? I mean, for your test case; not personally. Perhaps an alcoholic cardiomyopathy resulting in cor pulmonale to produce the respiratory symptoms; and alcoholic liver disease to cause GTT elevation. ALD and heart disease can both cause elevated ALP, as can many other things. The heart disease can also cause hepatic venous congestion and contribute to the deranged LFTs, particulary GGT as its a sign of hepatobiliary pathology moreso than pure hepatic pathology. You don't mention whether or not there's any other biochemical abnormalities, for example hypoalbuminemia, elevation of transaminases, hyperbilirubinemia (conjugated or not) - these would be useful to know. Also consider anything else that causes congestive heart failure, as the same physiology applies. Mattopaedia ^{Have a yarn} 02:59, 8 April 2009 (UTC)

Royal Society of Canada

Does the FRS(Canada) enjoy the same prestige as Memberships of American Academy of Arts and Sciences,French Academy of Sciences,Royal Society Of London,Royal Swedish Academy of Sciences,National Academy of Sciences and Pontificial Academy of Sciences(Ramanathan) —Preceding unsigned comment added by 212.247.70.129 (talk) 11:13, 6 April 2009 (UTC)

I don't have an answer about the FRS(Canada), but wanted to point out that the American Academy of Arts and Sciences may not be as prestigious as you think it is. Perhaps you're thinking of the United States National Academy of Sciences? --Scray (talk) 02:03, 7 April 2009 (UTC)

I must say I am surprised!According to the site American Academy of Arts and Sciences has more than 160 Nobel Laureates and 70 Pulitzer Prize winners amongst its membership and looking at the membership anybody who is anybody in US is a member!Surely that makes it perhaps one of the most sought after learned societies in the world apart from being the oldest learned society in the US!I was not so sure about the Royal Society of Canada.(Ramanathan) —Preceding unsigned comment added by 212.247.70.129 (talk) 09:35, 8 April 2009 (UTC)

Reference material for doctors

What materials do doctors use/refer to for diagnostic/differential purposes. In other words, for psychology/psychiatry you use the DSM-IV--this gives you criteria you must meet for certain disorders, possible treatment plans, etc. My question is, is there something comparable for the medical field? Thanks in advance for your help! Dimblethum (talk) 12:27, 6 April 2009 (UTC)

I'm just a layman but the last time I went to my NHS doctor in the UK, she used her computer after examining me. I realised later that she was looking up the recommended course of treatment. This is available publically online somewhere as I had a look at it, but sorry I've forgotten what it is called. In Britain patient records have been computerised, and apparantly this involves a classification system of some kind. I understand there are different classification systems used in the US. 78.147.28.51 (talk) 12:43, 6 April 2009 (UTC)

The ICD-10 from the WHO is what's used for general medical classification (and also used outside the US for psychiatry, rather tan the DSM-IV).Fribbler (talk) 15:33, 6 April 2009 (UTC)

Also see PubMed for which you can use Medical Subject Headings. For prescription drugs there's a pharmacological tome. Had the title when I started posting and now can't find it again, sorry. 76.97.245.5 (talk) 15:57, 6 April 2009 (UTC)

Depending on the doctor - and I suspect, the nature of the disorder you're being treated for - some doctors use Google. No, this is not a joke. However, upon re-reading your question, I feel that this probably doesn't address exactly what you're after. <.< 90.193.232.106 (talk) 17:59, 6 April 2009 (UTC)

Doctors use a variety of books, medical journals and internet resources. The Oxford Textbook series is widely used for reference, and all hospital libraries (in the UK) will have a copy of the Oxford Textbook of Medicine. I prefer Harrison's Principles of Internal Medicine; it is a little easier to read, and not just for reference. Again, Harrison's Principles is available everywhere. More recently, Uptodate.com has become a widely used web-based resource. In the UK, the British National Formulary is the definitive manual for drug dosing. [Declaration of conflict of interest: I am a pulmonologist and internist. I don't often read outside my areas of specialism.] Axl ¤ [Talk] 18:59, 6 April 2009 (UTC)

I agree with Axl. A great deal of medical training is learning to look things up and evaluate evidence. The list of reference sources is legion, as evidenced by the huge market for reference books and (increasingly) electronic media. While it's true that physicians use Google, it's often an indirect search for a specific reliable source or fact. Skills vary, of course, but good clinicians are very good at information retrieval. --Scray (talk) 19:51, 6 April 2009 (UTC)

@78.147.28.51. In Canada, the drug tome to which you were referring is called the CPS. // BL \\ (talk) 01:37, 7 April 2009 (UTC)

And in NZ, New Ethicals (randomly enough). Gwinva (talk) 03:49, 8 April 2009 (UTC)

If Sulforaphane is good for you, is sulphur dioxide beneficial also?

Sulforaphane is found in broccoli, cabbage and so on. Suplhur dioxide is used to preserve dried fruit etc. I make my own muesli using dried fruit, and I have been wary of sulphur dioxide. How likely would it be that if sulphoraphane is good for you, then suphur dioxide may be also? Would the metabolic pathways or the reasons for the benefit of the first chemical be similar to those of the second? Can this inference be made? 78.147.28.51 (talk) 12:50, 6 April 2009 (UTC)

If you really want to get into the details of this, you'll need to consult a doctor or some other appropriate professional. However, our sulfur dioxide article says that "[s]ulfur dioxide is an allergen to which some consumers are sensitive" and includes an EPA reference which notes that "SO₂ is associated with increased respiratory symptoms and disease, difficulty in breathing, and premature death."[1] — Lomn 13:06, 6 April 2009 (UTC)

I had already read both the articles thanks. I'm hoping for an answer from someone with knowledge of metabolic chemistry or physiology. It is not a medical question. 78.147.28.51 (talk) 13:29, 6 April 2009 (UTC)

I don't think we need any specialist knowledge here. Sulforaphane (C₆H₁₁NOS₂) has a completely different chemical formula from sulfur dioxide (SO₂) and has a much more complex molecular structure. There is no reason to expect their metabolic effects be at all similar. Our sulfur dioxide article says "Sulfur dioxide has no role in mammalian biology". Gandalf61 (talk) 13:32, 6 April 2009 (UTC)

The common mistake here is thinking that molecules which contain the same element must be similar. This is not true, at all. The most basic example is table salt, sodium chloride, which is composed of a metal, sodium, which bursts into flame when it gets wet, and a poisonous gas, chlorine. Obviously salt isn't much like either of those. StuRat (talk) 17:01, 6 April 2009 (UTC)

Magnetic flux

I have a doubt regarding magnetic flux, and i would appreciate if someone bothers to explain me this concept.

Basically, there is no such thing as a magnetic monopole right, so the most basic thing we can analyze is a dipole. And the dipole has to be a point dipole, it can't be two monopoles separated by a distance, for that would mean monopoles exist. So the most basic entity, corresponding to a point electric charge, is a point magnetic dipole. And i can regard the dipole as two monopoles, very close to each other( the monopoles have to be very strong, or the dipole moment will be zero, so consider both the pole strength and the distance as limits , one tending to infinity and the other to zero). Magnetic flux is a count of the no. of field lines emanating through a surface. But whatever the surface i consider (even if it is open), i can say that the positive flux caused by the positive point pole will exactly cancel the negative flux of the negative pole, as they are very close to each other, so the net flux has to be zero! So the magnetic flux through any surface is zero!

I know i am making a mistake somewhere in the argument, and i would be happy if someone would point it out to me. Thanks in advance (going through this would have caused some effort). —Preceding unsigned comment added by Rkr1991 (talk • contribs) 13:26, 6 April 2009 (UTC)

I believe you are exactly correct, the net magnetic flux through any closed surface is indeed zero. See http://en.wikipedia.org/wiki/Gauss%27s_law_for_magnetism It states "The left-hand side of this equation is called the net flux of the magnetic field out of the surface, and Gauss's law for magnetism states that it is always zero." —Preceding unsigned comment added by 81.11.162.104 (talk) 13:50, 6 April 2009 (UTC)

Indeed! In a world without magnetic monopoles any closed surface you construct will have zero net flux. There are still surfaces with net magnetic flux through them: unclosed ones.

You can prove this from Maxwell's equations if you don't mind some vector calculus: you start with ${\vec {\nabla }}\cdot {\vec {B}}=0$ try integrating it over a general volume and then use the divergence theorem to see that the boundary surface has a zero flux.

But do we live in a world without magnetic monopoles? Maxwell's equations are pleasingly symmetric if we include them and Dirac showed that if magnetic monopoles exist electric charge is quantized. Pretty tantalizing... 163.1.176.253 (talk) 14:27, 6 April 2009 (UTC)

I just noticed that you had mentioned open surfaces and you're not correct in thinking they would lead to zero flux. It's not correct to think of our ideal dipole as two point magnetic charges separated by zero distance. If it were then the two fields, generated by each monopole, would cancel perfectly (and therefore there wouldn't be any field lines at all).

So, if you want to think about it in terms of two separated points we need to have two monopoles separated by some non-zero distance. This then leads to fluxes for open surfaces and zero-fluxes for closed ones. (Although, as magnetic monopoles don't exist we should probably not give too much importance to the microscopic structure of a dipole constructed with them. We should really be using either the dipole as the fundamental generator of magnetic field or current loops, which have a magnetic moment and the advantage of existing.) 163.1.176.253 (talk) 16:25, 6 April 2009 (UTC)

Pah! A "point dipole" is an oxymoron -- it is nothing. Two opposite moments at the same location give a net sum of zero. The principle that there is no magnetic monopole only means that any positive magnetic moment must be associated with an equal negative moment in the vicinity. Looie496 (talk) 01:54, 7 April 2009 (UTC)

Well let me put forth my question more directly. This is a question which was handled in my class. There is a cylinder of radius r and height 2L. A point dipole m is placed at its center. Find the magnetic flux through the top surface, the axis of the cylinder being vertical. My teacher did this using the formula of the field due to a point dipole... but i want to know what's wrong with my logic. Since it is a point dipole, i have to bring the 2 monopoles(imaginary) very close to each other, which means they should cancel out each other's field lines, so there should be no flux. What's wrong with my logic? —Preceding unsigned comment added by Rkr1991 (talk • contribs) 05:38, 7 April 2009 (UTC)

You can indeed get a magnetic dipole by taking 2 magnetic monopoles of opposite magnetic charge, and let the distance between the monopoles go to zero while you let their charge go to infinity. If the magnetic charges remained finite, the fields would cancel out, but the magnetic charges go to infinity. The field in the limit is not zero. It's like finding x*(1/x) in the limit for x goes to 0 : the limit is 1, even though you seem to multiply by 0.

The monopoles are very close to each other, but they are also very strong. Surely you derived the formula for the field due to a point dipole by calculating the limit for the field of 2 monopoles whose magnetic charge goes to infinity and whose separation goes to zero? If not, try to do so mathematically. You'll see the field does not become 0. —Preceding unsigned comment added by 81.11.162.104 (talk) 07:39, 7 April 2009 (UTC) Ok thanks--Rkr1991 (talk) 13:27, 7 April 2009 (UTC)

Earthquake radius

I guess I know the basic answer to this question, but I am wondering if I can get more detail.

The terrible earthquake that occurred in Italy seems to have an exceedingly small radius in which it was felt. Is there a reason for this? Is my perception incorrect?

The related larger question is, why is an earthquake in St Louis felt in Boston, while an earthquake in LA is felt perhaps as far as San Diego (if even that far), while an earthquake in Italy is felt for barely 40 miles? Apollo58 (talk) 15:25, 6 April 2009 (UTC)

Fault (geology), Earthquake are worth a look. For Boston particularly Earthquake#Earthquakes away from plate boundaries. 76.97.245.5 (talk) 15:37, 6 April 2009 (UTC)

It's also worth noting that the Richter scale is logarithmic. Italy's quake is being estimated between 5.8 and 6.3 (a factor of five, give or take, so there's a lot of uncertainty). The 1812 New Madrid earthquake, which originated near St. Louis and rang church bells in Boston, was an 8.0 or higher -- approximately 100 times more powerful. — Lomn 15:49, 6 April 2009 (UTC)

Also, this USGS source suggests that the Italy quake was perceptible at least 200 km from the epicenter, significantly more than the 40 miles you first note. — Lomn 16:15, 6 April 2009 (UTC)

There are two aspects to this Q:

1) How severe a quake is at it's epicenter. This has to do with the magnitude on the Richter scale, of course, but also the population in that location, the building codes, and the local geology.

2) How well it travels. This depends on the geology between the source and measurement location as well as the local geology at the measurement site. A deeper quake will also tend to be felt more evenly over a wider area, while a shallow quake will be much stronger in the local area. StuRat (talk) 16:53, 6 April 2009 (UTC)

Indeed. An interesting comparison puts this week's Italian earthquake magnitude 6.3 M_w, depth 10km against the 2007 Gisborne earthquake, of 6.8 M_L and depth of 35.6 km. The Gisborne earthquake was felt in Christchurch, well over 700km away, yet there was little damage in Gisborne itself, and only 1 related death. (Of course, the depth is not the only contributor to damage: a medieval city will sustain more damage than a modern town built to exacting earthquake building codes. Gwinva (talk) 04:11, 8 April 2009 (UTC)

However, if an earthquake is say, over 100 km deep, then it would be felt over a wider area, but almost no major damage is likely to occur, because deeper quakes generally do less damage for a given area than a shallow one. ~AH1^(TCU) 02:08, 10 April 2009 (UTC)

Article: Science and technology in the United States

The article I mentioned above has almost no references or sources. For the article's quality, that's a problem that should be addressed elsewhere, but I'm looking for a good place to find some reliable sources on that topic. Thanks! Randnotell (talk) 16:12, 6 April 2009 (UTC)

While that article itself doesn't have references it's peppered with internal links. See if the linked articles have relevant information and whether that is referenced there. If it is you could either copy that ref. or leave things be as it is. (Latter option will almost guarantee the next "improve quality" editor stumbling over that article will scream murder. :-) 76.97.245.5 (talk) 17:26, 6 April 2009 (UTC)

Internal links cannot by themselves be used as references unless the fact in question is pretty obvious. It is also worth noting that there are long, synthetic paragraphs with almost no internal linking—which smacks of OR. There are also some major misconceptions. German scientists didn't leave Germany because Einstein urged them to, they left because the Nazis passed the Law for the Restoration of the Professional Civil Service that made them lose all their jobs. (Einstein didn't even flee Germany in the wake of Hitler—he had already left for a temporary position in the US, and after Hitler took power he announced that he wouldn't be coming back. That's not the same thing as fleeing.) (It also manages to totally omit any discussion of biology but that's another question.) It is... problematic to say the least. --140.247.242.83 (talk) 19:26, 6 April 2009 (UTC)

You can try my reliable sources search engine: [2] A Quest For Knowledge (talk) 19:28, 6 April 2009 (UTC)

A hypermiling question

I recently listened to a podcast about hypermiling and various fuel economy-maximizing behaviors. I drive an automatic Toyota Celica and have been hypermiling it for one fill-up so far; however, I'm wondering if constantly shifting into neutral is bad for my transmission? Presumably there's some general wear-and-tear, but is doing more harm than good in the long-run? -- MacAddct1984 ^{(talk &#149; contribs)} 16:14, 6 April 2009 (UTC)

Yes, it will do more harm than good unless you happen to drive down some very long hills (miles long), where the gas savings will be more significant. StuRat (talk) 16:39, 6 April 2009 (UTC)

Well, this last fill-up I went from averaging about 27 MPG (based on 9 data points, varying between 26-28 MPG) to 32.5 MPG, a 20% increase. As this was my first attempt, I suspect there may be improvement next time. I shift into neutral whenever suspect I won't need to accelerate for maybe 15+ seconds. How about shifting into neutral when stopped for at a traffic light? I have a feeling that the engine is working about the same fighting the brake in drive and spinning around incessantly in neutral. -- MacAddct1984 ^{(talk &#149; contribs)} 17:21, 6 April 2009 (UTC)

I read a report on the BBC website earlier this year, that shifting into neutral does not help fuel consumption; rather, it makes the car use more fuel because the engine thinks it should be doing something and starts eating fuel. The economical way they recommended was to keep the car in gear but to take your foot off the accelerator and drive it as long as possible without touching the pedals. --TammyMoet (talk) 18:35, 6 April 2009 (UTC)

In my above response, I definitely noticed an increase in MPG, granted it's only one data point so far. I can say that with my car, in neutral, the revs stay at about 700-800 RPM, in drive with my foot off the gas, it's about 1300 RPM. The problem with coasting in drive is that the car slows down much faster than when it is in neutral. -- MacAddct1984 ^{(talk &#149; contribs)} 19:37, 6 April 2009 (UTC)

But your fuel consumption is not proportional to RPM. If you have a car like mine with an instantaneous MPG meter - you'll see that you can have the tachometer wrapped around the end-stop

It's also very dangerous to let your car roll in neutral down long hills - you can't use engine braking (in a hurry) if you need to - and if you slow the car using the brakes, they may overheat, boil the brake fluid and then you'll have no brakes! If you want to do hypermiling - you're going to need a stick-shift car. Moreover, your 20% increase is much more likely from being acutely aware of your driving style than it is to do with rolling in neutral.

I did a proper scientific test (actually, as the result of a bet) in my first MINI Cooper'S (back when those cars only got 25-ish mpg when you drove them moderately agressively, as I usually do). What I did was:

1. Turned off the A/C.
2. Kept the tires slightly over-pressurized.
3. (most important) Never let the RPM get over 3,000 or under 2,000 (no easy feat!).
4. Kept my top speed down to 55mph.
5. Planned a route with the fewest stop-signs and traffic lights - even though it was ~10% longer than my usual commute.

By taking only those measures, I was able to squeeze 40mpg out of my 25mpg car...woohooo!

I love driving...but it was the most boring two weeks of my life!

Then I did some math...by driving like this, it was taking me 10 minutes longer to get to work each day - and 10 minutes longer to get home again. (People say that agressive driving doesn't get you there any quicker - but the science says "Bullshit"). Over the 560 miles I drove (56 miles per day) I used 14 gallons of gas - rather than the 22 gallons I usually used over that time. So at the cost of 200 minutes (3.3 hours) of my life, I saved 8 gallons of gas. At the time, gas was at it's most expensive - $4 a gallon...so I saved a princely $32. So - I was 'earning' about $10 per hour. Unfortunately, I earn $50 per hour - and at the time I was being paid for overtime work - so this represented a net loss of $150. Since I happen to enjoy being at work rather than creeping along the highway at 55mph - feeling uncomfortable because of the lack of A/C...it was actually a lot worse than that. But now - with gas under $2 per gallon, I'd only be saving $5 per hour - which means that I'd be paying myself less than minimum wage. So all of this nonsense doesn't make economic sense. If you are doing it - you're doing it for the greenhouse gas savings.

So now, I have the newest MINI Cooper'S - which does close to 40mpg with the A/C turned on and with my usual style of driving. This means that if I tried the experiment again - even if I got the same percentage mpg improvement - I'd be down to about $3 per hour.

My proper scientific conclusion is - don't drive a gas guzzler - get something with a 6 second 0-60 time and 140mph top speed - floor it at every red light if the car next to you is a VW Bug turbo, any kind of Scion or anything that says "Hemi" on the back. See if you can take cloverleafs at 80mph by following a proper racing line (um...you probably shouldn't try that in a Celica). Drive happy. SteveBaker (talk) 19:39, 6 April 2009 (UTC)

Your analysis avoids such things as time lost to more frequent refueling, possibly more frequent maintenance, and the occasional traffic accident ;-). --Stephan Schulz (talk) 20:12, 6 April 2009 (UTC)

Thanks for the lengthy reply, as always, Steve. Yes, the fact that I changed a bunch of variables at the start wasn't very scientific, so it is very possible that the change in driving style had more to do with it. Maybe I'll stop doing the neutral bit and see how much that actually changes things. Why keep the RPM over 2,000?

My commute to work is only about 10 minutes; however, I do a decent amount of highway driving a month (~800 miles) for work, visiting clients. For the record, I think those who turn their engines off completely while driving are insane. -- MacAddct1984 ^{(talk &#149; contribs)} 20:27, 6 April 2009 (UTC)

Well, 2000 rpm is what's recommended for my car - yours may be different. But in general - if the rpm is too low (and presuming it's doing work) - then the engine will be 'lugging' - which is when the sides of the piston to slap against the walls of the cylinder...it is extremely damaging to the cylinder walls. The car can safely idle at those low revs - but as soon as it has work to do - it needs more revs. Hmmm - oddly, we don't have an article about that...just a one-liner in a disambiguation page. It's not generally a problem in automatic cars because the transmission keeps the revs in the efficient range - but when you start messing around shifting it yourself - you get the worst of the stick shift and automatic approaches. Note: The cost of replacing your engine will make any amount of marginal gas savings irrelevent - so be careful. SteveBaker (talk) 00:30, 7 April 2009 (UTC)

Just for the record you should NEVER turn your engine off in a modern car while it's in motion. The steering may lock and you'll lose power assistance for the brakes and steering - extremely dangerous. Exxolon (talk) 21:06, 6 April 2009 (UTC)

Driving habits make a huge difference, but I agree with those above- there's no plausible explanation on why shifting into neutral would improve your mileage. Turning the engine off entirely would plausibly improve mileage, but it's dangerous, as pointed out above. Friday (talk) 21:15, 6 April 2009 (UTC)

You're talking automatic transmissions only, right? I can get a substantial improvement in "coast time" by dropping my manual Camry out of gear, because I'm no longer in compression. At one point in my commute, I crest one bridge over a crossroad, shift into neutral (which drops the engine speed from 2100 to 900 rpm), and can coast 7/10 of a mile to my exit, still hitting the cloverleaf at about 40mph. There's no plausible explanation for that? --DaHorsesMouth (talk) 22:33, 6 April 2009 (UTC)

Check the engine braking article. Exxolon (talk) 22:49, 6 April 2009 (UTC)

Sure, maintaining speed so you have it later can improve your mileage. What I mean specifically was, you're not using more gas in engine braking than you are just idling. Friday (talk) 14:57, 7 April 2009 (UTC)

I strongly disagree with DaHorsesMouth - doesn't matter whether it's stick or automatic. The "Gas pedal" is called that for a reason...it (essentially) controls how much gasoline is going into the cylinders. If your foot is not on the gas pedal, then it doesn't matter a damn whether you're in neutral at 900 rpm or in 4th gear at 3000 rpm...you're not using significant amounts of gas in either situation. If you have a car (like my '09 MINI Cooper'S) that has an instantaneous MPG gauge, you can prove this for yourself. If you take your foot off the gas pedal, then the reading goes to 99mpg (it's a two digit display) and then about half a second later, flips to flashing '-- mpg' irrespective of the RPM because the amount of fuel that's being used is zero and your MPG is infinite (or at least off the charts). Sliding into neutral doesn't do much (if anything)...and it's potentially dangerous. SteveBaker (talk) 15:23, 7 April 2009 (UTC)

I think all he was saying is that he slows down more when in gear, not that coasting in gear uses more gas than coasting in neutral. If you slow down when you didn't want to, and then have to give it some gas later, that uses more gas than not accidentally slowing down in the first place. Is the gas consumption really zero? I assumed the engine was still getting the same amount of gas it would get when idling, but I suppose I have no particular reason for having assumed that. I suppose a sufficiently-smart engine wouldn't bother injecting any gas at all, if it's not needed. But I don't know whether engines are commonly that smart. Friday (talk) 17:28, 7 April 2009 (UTC)

I would expect most modern engines to completely stop injecting fuel when the throttle is closed and the engine speed is sufficiently high (above 1,000 rpm or so). My 1994 Honda Civic del Sol did, and so does my 2006 MINI Cooper S (as documented by their service manuals), so I think it's a pretty well-established engine management feature. -- Coneslayer (talk) 13:14, 10 April 2009 (UTC)

Leave the car in gear and coast. This is engine braking, all modern fuel injected cars will completely shut off the injectors when you are engine braking, using no fuel. Also driving habits make a big difference, the harder you press the gas, the worse the MPG will be. That's about it.Extide (talk) 20:51, 7 April 2009 (UTC)

Centre of gravity

Hi! Where is the centre of gravity of the bow (weapon)when it is in passive state? Thanks! —Preceding unsigned comment added by 84.52.162.94 (talk) 18:04, 6 April 2009 (UTC)

That would depend on the bow. They come in all sorts of shapes and designs. It would also depend on whether you mean strung or unstrung when you say 'passive'. Algebraist 18:08, 6 April 2009 (UTC)

If you call the grip the front of the bow, then the center of gravity for a strung bow is going to be behind the grip. The center will move further back once it is drawn because the ends of the bow are pulled further from the grip. I am ignoring the contributions of the arrow in this case. Sifaka ^talk 18:37, 6 April 2009 (UTC)

But your first claim does not necessarily hold for a recurve bow. --Stephan Schulz (talk) 19:01, 6 April 2009 (UTC)

Composite bows sometimes have a weight out the front so that when drawn the centre of gravity is pretty much at the grip. Polypipe Wrangler (talk) 22:21, 12 April 2009 (UTC)

Violet scent

Is there any simple chemical (ester, perhaps?), that makes the characteristic scent of violets? Thanks, --Dendre (talk) 18:48, 6 April 2009 (UTC)

Perhaps Ionone per this website (see entry for 1905). Our article claims that ionone is a rose smell though. Rmhermen (talk) 19:01, 6 April 2009 (UTC)

Actually, our article on Ionones claims that one variety of Ionone is responsible for the rose smell. It seems entriely reasonable that a different Ionone or mixture thereof could be responsible for the violet smell as well... --Jayron32.talk.contribs 19:43, 6 April 2009 (UTC)

Another probe to Uranus?

Will we eventually send another probe to Uranus and Neptune? If so when? 2020? 2030? So far on Voyager 2 have been there.--69.228.146.223 (talk) 19:02, 6 April 2009 (UTC)

According to exploration of Uranus and exploration of Neptune, there are no current planned missions. I should think someone will send something eventually, if civilization survives long enough. Algebraist 19:14, 6 April 2009 (UTC)

We don't provide medical advice here. ;-) Axl ¤ [Talk] 22:27, 6 April 2009 (UTC)

I really don't want to make the obvious joke here. It's killing me not to... URGH... Probing Uranus? Did he at least buy you a nice dinner first? Too late... --Jayron32.talk.contribs 00:04, 7 April 2009 (UTC)

If Uranus was named in 1781, when was the first off-color joke published about its name? (Perhaps something like "Gosh, with my new telescope, I believe I can see Uranus!"). Understandably, with the correct pronunciation there is no humorous effect in such observations as 1902 "one with good eyesight can easily see Uranus without artificial help" or from 1914 "A remarkable thing about Uranus is that it is enveloped in a dense atmosphere of enormous extent." Edison (talk) 21:40, 7 April 2009 (UTC)

Garrison Dam

If Garrison Dam on the Missouri river in North Dakota failed catastrophically, how long would it take for the flood to reach the next dam down? Is it likely that this would cause a failure of the second dam as well? 65.121.141.34 (talk) 19:03, 6 April 2009 (UTC)

There are simply too many unknown variables to answer that. Some things that would influence the outcome is whether most of the water ends up going downriver or whether it can spread out; how fast the dam fails, how much debris it will carry, whether the other dams have been softened by rains; ice flow; etc.. The engineers probably allowed for some margin of error, but thing can always go wrong. 76.97.245.5 (talk) 11:04, 7 April 2009 (UTC)

Just curious, are there any examples of this kind of sequential dam failure? Rmhermen (talk) 16:13, 7 April 2009 (UTC)

I do not know of any, which is why I am thinking of using something like this for a disaster type book. 65.121.141.34 (talk) 16:55, 7 April 2009 (UTC)

See Banqiao Dam. -Arch dude (talk) 17:46, 7 April 2009 (UTC)

Fear of Abandoment

First - should psychology be under the Science Reference Desk? Second - What are the treatments for Fear of Abandoment? Has one treatment been more successful than other? --Reticuli88 (talk) 19:27, 6 April 2009 (UTC)

If we recommended treatments to you for any medical condition, that could be construed as advice. It would be irresponsible to make any statement which would encourage you to take a course of action which could end up being wrong. The best advice we could give you is to seek the advice of a qualified medical professional. --Jayron32.talk.contribs 19:40, 6 April 2009 (UTC)

Not seeking treatment for myself nor anyone. Just an objective question. --Reticuli88 (talk) 19:44, 6 April 2009 (UTC)

Perhaps our articles on Obsessive Love, Delusion or Anxiety may have some sources to help you out. We are not qualified to give you any advice, as psycological illnesses are extremely complex and treatments of any sort may vary greatly. Livewireo (talk) 20:15, 6 April 2009 (UTC)

The main treatments would be tranquilizers, cognitive behavioral therapy, or psychoanalysis, probably. Looie496 (talk) 02:07, 7 April 2009 (UTC)

Hammer Striking a Nail

Quick/dumb question: Why is it when you strike a nail (or any metal) with a hammer really hard there are sparks? —Preceding unsigned comment added by 24.171.145.63 (talk) 21:29, 6 April 2009 (UTC)

As a result of the impact, small pieces of iron or steel are shaved off and frictionally heated; so much so that they ignite and burn in air. Surface to volume ratio increases as the particle size decreases, therefore these particles burn much more readily than any "macroscopic" iron or steel objects. --Dr Dima (talk) 21:46, 6 April 2009 (UTC)

It is interesting to note that sufficiently small, unoxidized iron particles ignite spontaneously in air. So, frictional heating may not even be required (although it certainly helps). See pyrophoricity. --Dr Dima (talk) 21:56, 6 April 2009 (UTC)

I wouldn't say it's friction at all. If small bits of metal stick up on the nail when it is first struck, there will be an enormous pressure applied to those bits, causing them to heat enough to glow or even melt and splatter out. They then rapidly cool and solidify in the air. StuRat (talk) 19:05, 7 April 2009 (UTC)

Thanks! —Preceding unsigned comment added by 24.171.145.63 (talk) 22:05, 6 April 2009 (UTC)

Sparking is mostly true for steel hammers, a brass hammer will spark far less, or not at all, which is why they are used in emergencies when flammable gasses are in the area. 65.121.141.34 (talk) 13:39, 7 April 2009 (UTC)

Self-induced synesthesia?

I've recently been reading a lot about synesthesia as well as self-hypnosis. I found a study (http://www.medindia.net/news/Hypnosis-can-Induce-Synesthesia-Study-43347-1.htm) in which researchers claim to have induced Grapheme-> color synesthesia in their test subjects and I was wondering if the same would be possible via self-hypnosis. Further, would it by possible to induce sound->color synesthesia, assuming one has perfect pitch? Thank you! 128.252.254.7 (talk) 22:02, 6 April 2009 (UTC)

There are certain non-prescription medications which have been shown to induce synesthesia, but use of these is against the law in most jurisdictions... --Jayron32.talk.contribs 00:02, 7 April 2009 (UTC)

Thank you for answering; however, I was wondering if it was possible to induce grapheme->color synesthesia via self-hypnosis. Thank you! —Preceding unsigned comment added by 128.252.254.7 (talk) 00:54, 7 April 2009 (UTC)

The paper in question, PMID 19175754, was only published last month, which isn't really enough time for people to have weighed it and evaluated its implications. Looie496 (talk) 02:14, 7 April 2009 (UTC)

I remember reading about that study. The popular reportings suggest that the study considered grapheme-colour synaesthetes to be unable to see a black grapheme printed on a background of the related colour. I found this baffling based on my own experience of and readings about synaesthesia. No doubt there is some group of people for which this is true, but I don't think it's representative of synaesthesia in general. Is the actual study more nuanced on this? 80.41.115.101 (talk) 19:33, 7 April 2009 (UTC)

Global warming

Rather than we're destroying the planet couldn't global warming just be the sun going through what a star does when it becomes middle aged, i.e. become warmer and expand and bring its heat closer to the earth. I know we dont help but the idea of the sun being closer to us seems so much more viable to me. —Preceding unsigned comment added by 92.232.184.222 (talk) 23:09, 6 April 2009 (UTC)

See Stellar evolution. The kind of aging of the sun you describe takes place on the magnitude of 1,000,000,000's of years. Global warming is taking place on the order of 10's of years. Demonstrably unrelated events. Now, the sun does show small fluctuations in energy output, both increases and decreases, and sometimes on short-time periods, but the current trend in global warming has not been correlated to any such changes. It has, however, been nicely correlated to an increase in carbon dioxide levels in the atmosphere, AND to increases in industrialization... --Jayron32.talk.contribs 23:28, 6 April 2009 (UTC)

Yeah - the timescale of the present change is vastly too quick to be a 'natural' thing. Also, if you plot a graph of temperature gain versus CO2 levels - they track each other very closely. The correlation is close to perfect. Correlation doesn't mean causation - but we have plenty of reasons to show causation too. There is really no doubt left - none whatever - not a shred. We're beyond the "Is this really happening?" and "Is it a natural event?" thing...now it's down to "Can we fix it?", "How bad will it be before we do fix it?", "How much will it cost?" and "How can we pursuade China and India to do their part?"...sadly, we still get a dozen questions of this kind for every one of the latter - and that's a sad, sad measure of the success of the evil corporations who are trying to bury the facts under a whelter of FUD. SteveBaker (talk) 00:07, 7 April 2009 (UTC)

Well, there are natural events which can cause climate change on the time scales we're seeing now, such as giant meteors and supervolcanoes. However, we haven't had either of those events recently, so we know that's not the issue. StuRat (talk) 15:44, 7 April 2009 (UTC)

Yes, it's possible that changes in the Sun are the primary cause of global warming. Mars is getting warmer [3], Jupiter is getting warmer [4], Triton (Neptune's largest moon) is getting warmer [5] and even Pluto is getting warmer [6]. Meteorologist John Coleman, founder of the Weather Channel, states that global warming is primarily the cause of the Sun getting hotter [7]. This topic was discussed on Penn and Teller's Bullshit! program [8]. Although they stopped short of claiming that the idea that mankind is responsible for global warming is bullshit, they did say that it smells like bullshit (watch all 3 parts of the episode and the extra's for Penn and Teller's complete take on this issue). A Quest For Knowledge (talk) 03:34, 7 April 2009 (UTC)

I'm pretty sure he meant the effect of the sun getting hotter, not the cause. Global warming couldn't possibly cause the sun to get hotter.--KageTora (talk) 18:49, 7 April 2009 (UTC)

Dear OP: The previous respondent prefers to take the word of two comedians and a TV weather show anchor over hundreds and hundreds of qualified climatologists and scientists of all kind who are essentially unanimous on this point. You may judge his/her ability to answer questions of this kind accordingly. Sadly, I'm not allowed to use the phrase "total idiot" at this point (oops!). (Actually - it's just one comedian - the other one doesn't say much.) 14:55, 7 April 2009 (UTC)

I watched that episode of BS!, and it should be noted that it was made some time ago, before all the evidence was in. What they essentially said on the show was that global warming may or may not be occurring due to human activities, and that all the evidence was not in (at that point). Now it is, and it is pretty much clear to every scientist not on the payroll of a major polluter that global warming is a real problem. StuRat (talk) 18:43, 7 April 2009 (UTC)

According to a column Penn wrote last year [9], his position is "I don't know". A Quest For Knowledge (talk) 20:24, 8 April 2009 (UTC)

There is also some theory I saw on some science channel about the temperature of the galaxy being warmer in the spiral arms than in between (obvious, warmer near stars and colder away from them) and how that affects the overall temperature of the solar system as it passes through denser and less dense areas of the galaxy. That would mean that it could be a warm spot in the galaxy, not necessarily the sun getting warmer. Since I really have no interest in this theory, I didn't reserve any brain cells to remember what program it was or who was stating the theory. I vaguely remember that they had rather nice graphics (which is why I watched it). -- kainaw™ 03:56, 7 April 2009 (UTC)

"Planetary warming" is a myth promulgated by certain so-called sceptics. Of course, on average about half of all bodies in the solar system will get warmer at any one time due to orbital dynamics (elliptical orbits will move them towards and away from the sun). We do not have reasonable climate estimates for any of the farther solar system bodies. We only know about Pluto for 1/3rd of a Plutonian orbital period ("year"). The "warming" on Pluto, for example, is an extremely indirect measurement of atmospheric density during two occlusion events of stars -the atmosphere was thicker the second time, which may mean that more of it had thawed from the frozen state, which may mean that Pluto was warmer (or not). But Pluto, at that time was (and still is) fairly close to the sun, so of course it's expected to warm. Mars is not significantly warming - does anyone ever look at the second page of that NatGeo article? Jupiter is not getting significantly warmer, it very likely goes through a periodic event of wind system reorganization that makes some parts of it much warmer (and others cooler). And you might want to read the Triton article for yourself - there is no hint about increased solar output, but the warming is driven by atmospheric and albedo changes as the the moon goes through an unusual orbital alignment. We cover most of this with sources in the global warming FAQ. --Stephan Schulz (talk) 06:26, 7 April 2009 (UTC)

As Stephan said, the "warming" of other planets are due to measurement errors, or factors unrelated to the sun. To warm Pluto by 1C as a result of the sun warming is to warm Earth past the boiling point, so that's pretty much out of the question, although the Sun is expected to make Earth too hot for life in about 500 million years. ~AH1^(TCU) 02:03, 10 April 2009 (UTC)