Wikipedia:Reference desk/Archives/Science/2008 July 8

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July 8[edit]

Saving electricity by unplugging apliances?[edit]

How much electricity would be saved by unplugging the following except when on (which is a total of 2-3 hours a month): 22-inch TV, about 10 years old; DVD player, 3-4 years old; 13 inch TV, 20 years old. There really aren't any displays that keep going on any of them. Just wondering if I'd save my electric bill any with that. (I don't quite want to give up cable yet, though it's tempting. I only have the basic, though, so it's not much, less than $15 a month.) I wouldn't really have to cut costs like that, but I'm just wondering, is it worth it? Do appliances that aren't on but still plugged in waste a lot? (talk) 02:03, 8 July 2008 (UTC)

The old TV's will definately lose a lot of electricity if left in standby.. If there's a proper power off switch on them (not standby) using that will also work. The DVD will probably use hardly any energy in standby. (talk) 02:08, 8 July 2008 (UTC)
This all depends on your appliances. Any information given would be purely anecdotal. For example, I have everything on power strips. When I leave a room, I turn off the power strip and completely cut electricity to all devices in the room. I noticed a savings immediately. My monthly electricity bill dropped around $30/month. Since you can get power strips VERY cheap, it wouldn't be much trouble to get a few, use them to turn off anything not in use, and see what the change in your electricity bill turns out to be. I've heard some people say that their bill didn't change at all. I've heard others claim to cut their bill down to practically nothing. As I said, it is all anecdotal. -- kainaw 02:17, 8 July 2008 (UTC)
As long as they are actually switched off, unplugging shouldn't make any difference. If they are just on standby, though, they could well be using a lot of electricity and switching them off completely, either with an off switch or by unplugging, could save you a noticeable amount on your bill. --Tango (talk) 02:20, 8 July 2008 (UTC)
There's a definition: Parasitic_load - but it's just a stub. I've seen parasitic load described as up to 5% of total power, add in there the cost to air-condition the extra heat. Appliances more than 15 years old or so probably don't have a standby mode, very new appliances are increasingly subject to stringent standby power standards. In Canada, I think the latest is 5 watts maximum per appliance.
One way to check is to put your hand on the device to see if it's warm at all. I remember a cable converter box I had that would be -hot- to the touch, a good indication that I was spending money for nothing at all (except in winter, when we would huddle around it). Franamax (talk) 02:33, 8 July 2008 (UTC)
Addendum: unplug your cellphone charger and any other power adapter that has a transformer in it, so any voltage converter or AC/DC converter. They will always have a parasitic load, whether or not they have the actual appliance plugged in. Also, almost every modern PC has a standby mode - the "On" switch at the front sends a boot command to the motherboard, which is sitting there using a small amount of power even when it's off. The switch at the back is the one that makes zero power load. Kainaw is right - put a physical switch in to be sure everything is really turned off, off, off. Franamax (talk) 02:41, 8 July 2008 (UTC)
I endorse the idea that using a power strip to turn off the power will save on the electric bill. The problem is that some TVs and VCRs want to re-scan all the available frequecies when power has been off, to determine which channels are active. A VCR may also require resetting the clock and calendar when poser is restored. All the little AC adapters/wall warts are power vampires which waste energy. Edison (talk) 03:06, 8 July 2008 (UTC)
Actually the electronic power supplies switched mode power supply aren't that bad.. If your power supply contains a transformer then it will have a parasitic load. You can usually tell the difference by the weight (transformers are heavy).. (Switch them off anyway) (talk) 06:16, 8 July 2008 (UTC)
As it depends very heavily on the design of the specific appliance, go to the hardware store and get yourself one of those plug-in electricity meters - go between an appliance and the wall socket, and measure how much electricity is passing through. Use this to find out how much your appliances use when on standby, and multiply that by the cost of electricity in your area. — QuantumEleven 14:06, 8 July 2008 (UTC)
Have you seen a wattmeter in hardware stores? All I have seen are multimeters, which let you see volts or amps but not watts. The power factor is unknown, so measuring the volts and then the amps really does not show the power consumed. The cheapest one I see online is the "Kill A Watt" meter [1] which shows volts, amps, Hz, watts, or kilowatt hours, for about US$33. It might take a while for the savings from shutting off parasitic loads to pay for the meter. It would be a good rental item or a loaner from a community green organization. An online site [2] gives some watt measurements via the Kill A Watt for various electronic products, but I do not see thorough coverage of the idling power use by TVs and power adapters. "Energy Star" rated appliances are still allowed to consume 15% of maximum power usage when in power saving mode[3]. The article Standby power covers this subject pretty well, as does the Howstuffworks article "Fight vampire power" [4]. Edison (talk) 17:08, 8 July 2008 (UTC)

Survival versus reproduction[edit]

To what extent can a high reproduction rate in a species compensate for a low survival rate? NeonMerlin 03:26, 8 July 2008 (UTC)

If the goal is "how many offspring survive" (i.e., maximize number that reach reproductive age in order to pass on genes), it doesn't matter whether how many offspring you have. You don't need to have many if you can be sure they will survive, but if they're likely not to survive, you'd better have a lot of them to make sure some survive. 2 at 50% mortality is the same result as 100 at 99% mortality. DMacks (talk) 04:20, 8 July 2008 (UTC)
Check out r/K selection theory. I think that page needs some work, tho' . . . Robinh (talk) 12:48, 8 July 2008 (UTC)

Space Time[edit]

This may be a dumb question but, Why do large masses like our sun bend space time? (talk) 06:09, 8 July 2008 (UTC)

It's not a dumb question at all. Have you checked out our article on gravitational time dilation? -- Captain Disdain (talk) 06:23, 8 July 2008 (UTC)
General Relativity is also a good place to look. Basically anything with mass, distorts space time to some degree, and this distortion is what we call gravity. Objects with greater mass, cause greater distortions in space time, and thus have greater gravity. ScienceApe (talk) 01:03, 12 July 2008 (UTC)

Thank you both for the references. (talk) 06:39, 13 July 2008 (UTC)


myopia —Preceding unsigned comment added by Sandeep123456 (talkcontribs) 12:25, 8 July 2008 (UTC)

Do you have a question? If it's not answered in our article myopia, feel free to come back and ask it. Algebraist 12:32, 8 July 2008 (UTC)
Perhaps the question is just too small to read. --Several Times (talk) 20:50, 9 July 2008 (UTC)
Or perhaps the question will follow, but we're just too short-sighted to wait for it ? StuRat (talk) 04:23, 10 July 2008 (UTC)


IBS-Irritable bowel syndrome-how is it reffered to in other languages?I have tried,unsuccessfully to find info on it in Slovenija and dont really know how to go about it. —Preceding unsigned comment added by (talk) 13:08, 8 July 2008 (UTC)

Unhelpful comments were removed from this section by others.Franamax (talk) 06:47, 13 July 2008 (UTC)
I can't read the language but I would say would be a good start for your search. Jdrewitt (talk) 17:02, 8 July 2008 (UTC)
One of the neat little features of wikipdia that alot of folks don't notice is great in making just this kind of translation. If you look on the bottom left of most articles, you'll see what other languages the article is offered in. Scroll over the language links (and look at the status bar) or click them to see the name of the article translated. Off the bat I can tell you (from the links in the IBS article):
  • German: Reizdarmsyndrom
  • Spanish: Síndrome irritable de intestinos
  • French: Côlon irritable
  • Hebrew: תסמונת_המעי_הרגיז
  • Netherlands: Prikkelbare-darmsyndroom
  • Japanese: 過敏性腸症候群
  • Polish: Zespół jelita drażliwego
  • Portuguese: Síndrome_do_cólon_irritável
  • Russian: Синдром раздражённого кишечника
  • Suomi: Ärtynyt suoli
  • Swedish: Irritabel_tarm
  • Thai: โรคลำไส้แปรปรวน
Neat trick, right? Also, for the record, there is a language reference desk where you can pose questions like this. --Shaggorama (talk) 03:34, 9 July 2008 (UTC)
Um, in general that's not necessarily a translation. It's the corresponding article in those wikis, or the article that some user or bot has decided is the corresponding one. This can be problematic as content is not always divided up the same way in the different language WPs, so which link is best to make is not always obvious. The interwiki bots can be very bullheaded in changing back to the wrong link, or at least they used to be; I haven't seen that so much in a while -- maybe someone improved the code. --Trovatore (talk) 07:47, 9 July 2008 (UTC)

Thank you v much,Jdrewitt,that was exatcly what I needed. (talk) 14:26, 9 July 2008 (UTC)

Brain communication and handedness[edit]

If you were born left handed, but brought up right handed, would that improve your brains intra communication and make you smarter or not? —Preceding unsigned comment added by (talk) 15:57, 8 July 2008 (UTC)

I don't think it'd make you smarter as such, perhaps more ambidextrous and it might improve your co-ordinational ability.. It's still not entirely known why you are born right or left handed, and some still think it's a matter of how you are raised. Others think, as the article states, it could be due to which hand was used more in the womb. — CycloneNimrod  Talk? 16:58, 8 July 2008 (UTC)
You haven't given a reason for your assumption that improving the brain's intracommunication makes a person smarter. Simply increasing signals doesn't equate to intelligence. During a seizure, there is a lot of communication going on - and it just messes everything up. So, why would intracommunication lead to being smarter? -- kainaw 17:57, 8 July 2008 (UTC)
I don't think the OP was suggesting more signals = more intelligence. More likely the assumption was, perhaps correctly, that more neurons and connections (at least more knowledge) — CycloneNimrod  Talk? 22:07, 8 July 2008 (UTC)

bond energy[edit]

a C=C bond energy is less than twice a C-C bond energy but a C=O bond energy is more than twice a C-O bond energy, just can't figure out why, please help--scoobydoo (talk) 17:37, 8 July 2008 (UTC)

See bond energy (especially the distance correlation). -- kainaw 17:53, 8 July 2008 (UTC)

holes in chest[edit]

A couple of my (male) friend have like holes in their chests, (I suppose some girls probably may too but I don't go into changing rooms with them, (as much as I might like to)). Anyway, as I was trying to say before I was interrupted, like where their ribs should be I suppose the ribs are there but they're not normally shaped. I suppose (not studied too closely). What is this? Anyone got any good weird pictures? (as abnomalities go I suppose it is fairly harmless, unless you want to become such salubrious occupations as male stripper/porn stud/actor).

PS not this [5], or this [6]

ooh, actually like this

I can't click your links, but I think I understand from your description. Medically, it is known as Pectus excavatum. I have heard it referred to as a Concave Chest. Plasticup T/C 20:04, 8 July 2008 (UTC)
If their sternum goes inwards (concave), then it is indeed pectus excavatum. I did some pretty extensive work to that article a few months ago. Pectus carinatum is where the sternum protrudes outwards. There are loads of images available on the net if you just search around a bit :) I'd disagree about it being fairly harmless though, there are several medical conditions which are more likely if you have PE (such as mitral valve prolapse and it can also put pressure on the respiratory system). Let's not even start with the psychological damage it could have on a teenager, for example. — CycloneNimrod  Talk? 22:11, 8 July 2008 (UTC)

How to determine the right direction of an insert in a plasmid?[edit]

Hey guys. I need an immediate help. I have this biology lab about plasmids that we are required to inset a cDNA into a plasmid. one of the fundemental question of the lab is how can we determine that we put the insert in the right orientation? they talk about the use of restriction enzymes and to see the results of agaron gel electrophorisis. can somebody explain this to me? or at least guide me to a website that i can find in it useful information. Thank you, —Preceding unsigned comment added by (talk) 20:47, 8 July 2008 (UTC

See restriction enzyme and sticky ends. --Mark PEA (talk) 21:37, 8 July 2008 (UTC)
Briefly, there are specific palindromic sequences in DNA (called restriction sites) that marks the site that restriction enzymes will cut. You find a site in your cDNA and another in your plasmid. You then calculate what theoretical fragment sizes you would expect depending on which orientation the cDNA is in your plasmid. You then cut the DNA at these sites and separate the fragments by agarose gel electrophoresis. You then compare the size of the bands on your gel with the theoretical sizes, and that will tell your the direction of the cDNA in the plasmind. As Mark notes above, if you use non-complementary sticky ends to clone your cDNA in the first place, then you don't have to worry about this. Directionally is only really a concern with blunt end cloning or by using complementary sticky ends. Rockpocket 05:34, 9 July 2008 (UTC)

Purity of CO2[edit]

Are there other gaseous byproducts besides carbon dioxide resulting from the Hall-Héroult process and if so or if not is the carbon dioxide pure enough to use to make soft drinks? Mimus polyglottos (talk) 21:34, 8 July 2008 (UTC)

You can expect some sulfur dioxide Perfluorocarbon and hydrogen fluoride and other fluorides to be produced. It is very unlikely to be suitable for human consumption in a concentrated form. The reason is that the carbon is not pure and there will be other contaminates in the electrolyte. Graeme Bartlett (talk) 00:25, 9 July 2008 (UTC)

Talk:Composition of the human body[edit]

Out of curiosity, the exact elemental composition of a male human who was perfectly healthy with a mass of 90,000 grams would be what exacty? As well, what would the mass of the chemicals, and what chemicals, be for the chemical composition? This question also is asked for the material and tissue composition. Earthan Philosopher (talk) 22:22, 8 July 2008 (UTC)

This question was asked on the talk page of the very article that has the answer... I guess the only thing lacking is how to convert the percentages given into masses: If 65% of a 90,000 gram body is oxygen, then there is 0.65x90000=58500 grams of oxygen, the others are calculated the same way, just replace the 0.65 with the appropriate number. --Tango (talk) 22:36, 8 July 2008 (UTC)

But if 3.8 grams is of iron is definite, then how can you have an exact percentage of elements by mass. Also it says that there are other elements as well. Plus there are two ammounts of percentages that state that the percentage is less than .05 or .01 percent, so how would you know the exact ammount of those elements. and these don't answer my questions of chemicals and material and tisuue compositions. Earthan Philosopher (talk) 23:00, 8 July 2008 (UTC)

The composition is always going to vary from person to person. All the figures are approximate. 3.8g in a typical person is a fraction of one percent, so it's not going to cause the other figures to be inaccurate. The components not given in the table are also in very small amounts, so don't cause any inaccuracies in the other figures. I don't know about the chemical distributions, other than that Water#Effects on life says humans are 60-70% water. --Tango (talk) 23:20, 8 July 2008 (UTC)

Personal question though, ( if you are religious, do not let this bias your answer please) if you were to get all the components and put them in the right structure, do you think it would be possible to create artificial human life? —Preceding unsigned comment added by Earthan Philosopher (talkcontribs) 01:05, 9 July 2008 (UTC)

If it were possible to put them all together in just the right way, then yes. It would be impossible to distinguish a "real" human from an artificial one, so if one is alive, they most both be. The real question is whether that is possible, and the answer there may well be "no". The uncertainty principle prevents a perfect reconstruction, so there is always going to be some level or error. Whether it's possible to get it close enough or not, I don't know. Certainly not with current technology or anything in the foreseeable future. There have been attempts at creating much simpler artificial life, though, see Synthetic life. --Tango (talk) 01:24, 9 July 2008 (UTC)