Wikipedia:Reference desk/Archives/Science/2011 April 9

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 9

What is this called?

One day, my classmate was clutching her stomach and jolting her head forward, as if she was vomiting, but she didn't vomit, and she started feeling really hot, and the nurse came and wheeled her away in one of those chairs on wheels, so I knew it was very severe. What happened to her, and what is it called? MickWithoutGlasses (talk) 00:28, 9 April 2011 (UTC)

It could be many things, some of them serious, some of them not. Looie496 (talk) 00:53, 9 April 2011 (UTC)

What are the things? MickWithoutGlasses (talk) 00:54, 9 April 2011 (UTC)

By the way, "one of those chairs on wheels" is usually called a wheelchair here in the States and likely many other places as well. Dismas|^(talk) 00:58, 9 April 2011 (UTC)

And a dry heave is making the vomiting motion but not actually vomiting.. StuRat (talk) 02:27, 9 April 2011 (UTC)

The posh word for it is retching. --TammyMoet (talk) 08:24, 9 April 2011 (UTC)

I don't know what it was, but I sure hope you washed your hands... Wnt (talk) 03:56, 9 April 2011 (UTC)

She could have PMS, flu, food poisoning, a migraine, there are too many possibilities. Probably hundreds of things could cause dry heaves and feeling flushed. Presumably they took her to someone who can examine her for other symptoms. Ariel. (talk) 01:13, 10 April 2011 (UTC)

characteristics of neutron star nebula

it was in 23 February 1987 that Canadian astronomer Ian Chilton in chilly hunted special event in Magellan cloud in mont wilson abservatory , it was a new supernova ,the brightness of one star in distance 170000light year came to 100million times further than sun , the nebula remained from 1987A supernova has beautiful shape and seems to human eye . two outer rings with common central core ,shape of this nebula defers from others such as crab nebula ,what does case this difference?

--78.38.28.3 (talk) SEE ALSO 05:24, 9 April 2011 (UTC)http://en.wiki.x.io/wiki/Supernova_remnant

The axis of explosion for one thing: as I understand it, if the pole of the explosion is aimed straight at you, then you will see something like the Crab Nebula or the Cassiopeia A remnant. If it's side on you will see something like SN1987A. Then there's the material which has been previously discharged from the progenitor star, how far it lies from the star and when the blast from the explosion catches up from the material. --TammyMoet (talk) 08:23, 9 April 2011 (UTC)

the distance of pre genitor star is about 20 light year .

In fact I want to know either the remnant nebula is dust as is said or it has gathered pieces or continues rings , the matter is escaping together and it shows the dust type with vacuum density might be incorrect, are they so

?akbarmohammadzade--78.38.28.3 (talk) 09:42, 9 April 2011 (UTC)

Identify this fruit

A fruit I saw and ate in India, but I can't remember what it was called. Anyone recognize it? SDY (talk) 06:52, 9 April 2011 (UTC)

It's a sugar-apple. Richard Avery (talk) 06:59, 9 April 2011 (UTC)

The name of this fruit is Custard Apple. For further details please kindly refer to the following link:

http://en.wiki.x.io/wiki/Custard-apple

In INDIA this fruit is known as Sitafal. aniketnik 09:50, 9 April 2011 (UTC) — Preceding unsigned comment added by Aniketnik (talk • contribs)

Well, whatever, but if you check the images in the two articles the difference may help you decide. Richard Avery (talk) 13:20, 9 April 2011 (UTC)

It could also be Annona cherimola or Cherimoya. Why are there two separate articles about the exact same thing? Roger (talk) 14:59, 9 April 2011 (UTC)

Its neither of those, though they look close. Its a custard apple (sitaphal). Cherimoya isn't bumpy enough, and plus I haven't heard of them in India. Anyways, why not propose a merger for those two articles? See WP:MERGE ManishEarth^{Talk • Stalk} 15:28, 9 April 2011 (UTC)

Ventrolateral side

Rostral-to-caudal axis for the human head

The term ventrolateral is a combination of two words "ventral" and "lateral". What does the term "ventrolateral" exactly mean? How is the term "ventrolateral" related to brain? aniketnik 09:53, 9 April 2011 (UTC) — Preceding unsigned comment added by Aniketnik (talk • contribs)

On the ventral (front, abdomen...) surface, but away from the midline of the body. --jjron (talk) 11:29, 9 April 2011 (UTC)

I don't know much about this but I thought for the brain "ventral" meant the underside. So, pointing towards your feet in standard anatomical position. Like this: [1] 129.234.53.36 (talk) 13:44, 9 April 2011 (UTC)

Questions like this are surprisingly difficult to get straight, and have been known to cause neuroscience students to tear their hair out. Our article on anatomical terms of location deals with it, but unfortunately not all that well. For most animals, three axes are used to denote locations on the body: rostral to caudal, meaning nose to tail; dorsal to ventral, meaning back to belly; medial to lateral, meaning midline to points away from the midline. Unfortunately the upright posture of humans means that the relationship between head and body is different for us than for most animals, and this creates difficulties in dealing with the human brain. The neuraxis, which runs straight in the nose-to-tail direction for most animals, turns at a 90 degree angle in the middle of the human brain. For this reason, anatomists often use a special set of axes for dealing with the heads and brains of humans and other primates: anterior-to-posterior, meaning from nose to back of head; and superior-to-inferior, meaning from top of head to neck. What this means is that for the human brain, the term "ventral" actually applies with respect to a curved axis, as shown in the picture I am adding. Is all that confusing enough for you? Looie496 (talk) 01:34, 10 April 2011 (UTC)

The picture along with the text (User:Looie496) give the right direction and make things simpler and easy to follow and to understand. Thanks a lot. aniketnik 07:31, 10 April 2011 (UTC) — Preceding unsigned comment added by Aniketnik (talk • contribs)

Butterfly effect

Is it safe to say that the time travel is practically (not theoretically) impossible just because of butterfly effect? If so, could it serve as an evidence of intelligent design, which did so to keep the past safe from external intervention? —Preceding unsigned comment added by 89.76.224.253 (talk) 12:53, 9 April 2011 (UTC)

Time travel is impossible because of the Entropy (arrow of time) and causality and other issues. These are practical descriptions of physical laws, as we understand them. As to assigning purpose to physical laws, that's between you and your God. You work out purpose for yourself, but there is zero "evidence" that you will derive from the physical laws which can "prove" intelligent design. That doesn't mean that God does not exist, or that he's not to be an important part of your life. Its just that, you're not going to be able to "prove" him or his existance via sceintific means. You won't "disprove" him either. --Jayron32 12:58, 9 April 2011 (UTC)

Also the problem of simple conservation of mass; the universe is chugging away one day and all of a sudden 200 odd lbs of protoplasm are created out of nothing, with an IOU from the future that promises they will disappear again in order to balance the books.... ?

Note that these problems go away with the concept of a time machine which works more like an elevator; i.e. you can go into the machine at any time during when it exists and leave at any time during which it exists, but not before it was put into operation or after it was shut down. How this affects intelligent design hypothesis, i can't guess.Gzuckier (talk) 04:30, 10 April 2011 (UTC)

No, everything was created last Thursday or 5 minutes ago, depending on whom you talk to. Imagine Reason (talk) 16:13, 12 April 2011 (UTC)

Where were those isotopes referenced?

Today when I was looking on Isotopes of meitnerium, I checked out several links on "References" section below, but still several isotopes' data were non-experimental and weren't cited any sources, like ²⁷⁰Mt, ²⁷¹Mt, ²⁷²Mt, ²⁷³Mt and some more. Should these data be considered valid?

I also found such information in the Nuclear Physics A source:

In case no experimental data is available, trends in the systematics of neighboring nuclides have been used, whenever possible, to derive estimated values (labeled in the database as non-experimental).

— From this source

I would like to know what is the "trend" and where is its source?--Inspector (talk) 13:10, 9 April 2011 (UTC)

cocoon

Our cocoon -Painted Lady Butterfly -was one day from opening when it fell from vertical position to horizontal position in the cage. Will it still open? Thanks. Christine —Preceding unsigned comment added by 76.209.134.249 (talk) 14:58, 9 April 2011 (UTC)

I don't see why not. The cocoons are fairly robust. However opening times are not as predictable as you seem to think. It might take a few more days yet.--Shantavira|^{feed me} 15:32, 9 April 2011 (UTC)

Not all pupae/chrysalises successfully emerge, sometimes for unobvious reasons, but this minor change of position should have little effect ♦. However, you might want to ensure the pupa is somewhat anchored, perhaps by putting a spot of glue on the cremaster (the hook at the end of its abdomen that it was hanging from) to re-fix it, so that when the adult does emerge it can gain sufficient purchase to free itself from the remains of the pupal case. If you do not re-hang the chrysalis, ensure that there is a rough vertical surface near it so that the emerged adult can cling to it in the natural position while it expands and dries its wings - if it has to do so while horizontal, wing deformities could be caused.

♦ In my schooldays, I raised many dozens of the related Small Tortoiseshell from eggs and caterpillars, and used to remove the hanging chrysalises from their feeding box and lay them out on the bottom of a (dry) aquarium in rows under lights to aid hatching and to enable our biology classes to watch the process. Only a small proportion failed to emerge successfully. {The poster formerly known as 87.81.230.195} 90.197.66.111 (talk) 18:25, 9 April 2011 (UTC)

Could you please check my math?

Hello. Electricity in my country costs about €0.11 per kW/h. I've calculated that, if I buy a 10-watt solar panel that costs €160, it will have paid off after 44 hours of operation. However, this figure seems suspiciously low. Could someone please check my math? Thanks. Leptictidium (mt) 16:58, 9 April 2011 (UTC)

Hard to check your math when you don't show it, but your result is way off. Even running on full power, it would take the panel 100 hours to produce a single kWh (not kW/h) and save 11 cents. Break-even will occur after about 17 years of continuous 24/7 sunshine. Note: not adjusted for inflation and capital costs. –Henning Makholm (talk) 17:07, 9 April 2011 (UTC)

(ec) It will take 100 hours at 10 W/h to generate 1 kW/h. That will save you €0.11. So, at that rate it will take you 100(160/0.11), or 145,454 hours. That would be 16.6 years straight. Of course, this is assuming maximum output. You probably get less output when the Sun is at an angle, when clouds are out, when a shadow falls on the solar panel, when it gets dirty, or when it gets old. You also get no output at night. There can also be a problem with excess electricity being produced which you then must store, sell back to the power company, or lose, but I assume this isn't a factor in your case. So, considering all those factors, it might be closer to 50 years, but they aren't likely to last that long (and maybe you aren't either). So, they will never pay for themselves. StuRat (talk) 17:16, 9 April 2011 (UTC)

How much energy does it cost to produce a 10 watt solar panel from the basic chemical elements we can mine? If this is less than the total amount of energy the solar panel produces then you can, in principle, design a process that will produce solar panels at an exponentially increasing rate. Count Iblis (talk) 17:38, 9 April 2011 (UTC)

Only to a point. We would soon have increased costs for the raw materials, due to shortages, and increased production costs, due to shortages of manpower, and we would have filled all the best spots for solar panels and end up putting them in less optimal positions, etc. Also note that the same thing would have applied to other forms of energy. And, indeed, petroleum use did increase at a dramatic rate early on, but is now leveling off, since the price went up, due to scarcity. StuRat (talk) 17:49, 9 April 2011 (UTC)

Yes, it would be just like when trees and plants first colonized the Earth. But if you have a self sustained process like the growth of plants, you will get a huge amount of solar power almost free of charge. Count Iblis (talk) 17:55, 9 April 2011 (UTC)

I wouldn't say it's "almost free", since plants do require resources other than light, such as land and water. So, unless those things are free, plant energy (like food and wood to burn) isn't free, either. StuRat (talk) 17:59, 9 April 2011 (UTC)

Also, 10 W sounds rather small for 160 EUR. Right now, [2] shows a 95 W panel going for USD 160, and at [3], USD 130 will buy you 110 W. Perhaps a digit has been dropped somewhere, or the 10 W model is a special one designed for small physical dimensions or long life? –Henning Makholm (talk) 19:43, 9 April 2011 (UTC)

Where do you get electricity for €0.11 per kWh? I have to pay about double the price. 93.132.156.45 (talk) 19:46, 9 April 2011 (UTC)

Unless solar energy is subsidized (i.e. you get payed more than €0.11 per kWh for the energy that your solar panel produces) by your country (e.g. in Germany) or you live in a really sunny place, solar panels are generally not cost effective yet. You might also like to read about Grid parity. bamse (talk) 22:41, 9 April 2011 (UTC)

Another way (The German Way) is to invent new taxes and otherwise put new costs on other grid electricity sources and to put up increasingly prohibitive obstacles for them (as for nuclear or coal powered plants). This way solar energy will get even cheaper than electricity from other sources. I only doubt heavily about the EROEI of such manoeuvres. 77.3.170.46 (talk) 16:29, 10 April 2011 (UTC)

Such high taxes can be justified as making producers pay the entire cost, rather than passing on to future generations the costs of minding nuclear waste and dealing with global warming. StuRat (talk) 17:21, 10 April 2011 (UTC)

And would there be less global warming or nuclear waste if we use a technology where the EROIE is negative, that is to say which eats up more nuclear or coal power for the manufacturing process than it delivers back? And what about the costs to get rid of solar panels made of toxic cadmium? 77.3.170.46 (talk) 18:25, 10 April 2011 (UTC)

Mythical terminal disease ?

A common plot device is an incurable terminal disease, but with no symptoms. One example is in the 1960's TV series Run for Your Life. My questions:

A) Are there really any such diseases (let's say that are terminal within 5 years) ?

B) Would they be detected, if they have virtually no symptoms ? StuRat (talk) 17:46, 9 April 2011 (UTC)

Lung cancer? You don't have any symptoms in the early stages when it can be cured. When you do get symptoms, it is usually too late. Count Iblis (talk) 17:52, 9 April 2011 (UTC)

That doesn't seem to qualify, as it doesn't result in a seemingly healthy person walking around who actually knows he has a terminal disease. StuRat (talk) 22:10, 9 April 2011 (UTC)

Cerebral aneurysm. These may or may not be symptomatic, depending on what structures in the brain they compress; in some locations, they are inoperable. While it is not usual to screen for asymptomatic aneurysms, they can be an incidental finding by CT or MR angiography. (When you say "no symptoms", do you really mean no symptoms, or do you just mean "no debilitating or outwardly conspicuous symptoms"? Persistent unexplained headaches, for example, could eventually lead to detection and diagnosis of an aneurysm, but wouldn't otherwise interfere with our hypothetical patient's normal life.) TenOfAllTrades(talk) 18:12, 9 April 2011 (UTC)

I suppose "no debilitating or outwardly conspicuous symptoms" would qualify, but does someone with a cerebral aneurysm always die with 5 years ? StuRat (talk) 22:12, 9 April 2011 (UTC)

Many cancers have no real symptoms until it is way too late and you have weeks to live, such as ovarian cancer. --TammyMoet (talk) 18:36, 9 April 2011 (UTC)

That doesn't seem to qualify, as it doesn't result in a seemingly healthy person walking around who actually knows he has a terminal disease. StuRat (talk) 22:10, 9 April 2011 (UTC)

Mate, I work in a day centre of a local hospice, and honestly you wouldn't know many of our cancer patients actually had cancer. Often the ones who look the illest (OK I know it's not a word but it'll do), the ones you'd expect to die soon, don't: it's the ones who look in better health than the nursing staff! One of our patients had cancer for 30 years! Often people only look ill with cancer in the last week or so of their lives. --TammyMoet (talk) 08:39, 10 April 2011 (UTC)

Many types in cancer while they are in a temporary remission after initial chemo/radiation. A man who eventually died of recurring leukemia seemed healthy before the final fatal reoccurrence. Edison (talk) 20:22, 9 April 2011 (UTC)

That might qualify. I suppose the hair loss would be less conspicuous in a man, who could just be thought of as bald or with a military hair cut. StuRat (talk) 22:16, 9 April 2011 (UTC)

Simply being alive would also qualify because, eventually, your body will age and die; the body lacks the mechanism for fully repairing itself. Count Iblis (talk) 20:34, 9 April 2011 (UTC)

Hence the 5 year limit I imposed. StuRat (talk) 22:09, 9 April 2011 (UTC)

There are some types of Congenital heart defect which have no symptoms until they kill you, nearly instantly. John Ritter, Hank Gathers and Reggie Lewis all died of one; in Gathers and Lewis the specific defect was Hypertrophic cardiomyopathy, which is asymptomatic and undetectable in most people, right up until it kills them. --Jayron32 21:41, 9 April 2011 (UTC)

Yes, but are these necessarily fatal within 5 years ? StuRat (talk) 22:09, 9 April 2011 (UTC)

Does it have to be a naturally occurring desease? Or would an artficially engineered one do? Nanobots with an expiration date? —Preceding unsigned comment added by 190.56.107.80 (talk) 22:37, 9 April 2011 (UTC)

I'm looking for something that currently exists. StuRat (talk) 02:27, 10 April 2011 (UTC)

What about this: You know for sure that you have ingested one microgram of polonium-210 by accident a few hours ago. While you don't have any symptons yet, you know that you are doomed. Count Iblis (talk) 02:13, 10 April 2011 (UTC)

I suppose some type of poison, including a radioactive one, might qualify, but I was looking for something that would leave them healthy for longer, at least a few months. StuRat (talk) 02:27, 10 April 2011 (UTC)

Bear in mind that sign and symptom do not mean the same thing. Richard Avery (talk) 06:45, 10 April 2011 (UTC)

My father and most of my uncles died of heart attacks around age 60. So if I were 55 already... 93.95.251.162 (talk) 14:03, 13 April 2011 (UTC) Martin.