Wikipedia:Reference desk/Archives/Science/2006 July 7

Humanities Science Mathematics Computing/IT Language Miscellaneous Archives

The page you are currently viewing is an archive page. Whilst you can leave answers for any questions shown below, please ask new questions at one of the pages linked to above. This will insure that your question is answered more quickly.

< July 6 Science desk archive July 8 >

Recover Hard Drive Table Information From Previously "Mounted" Drive

I have three hard drives in my computer, connected to IDE1 Primary and Secondary, and IDE2 Primary.

The bootable drive (Seagate 200GB) is partitioned into 20GB (boot) and 160GB (data).

There are two drives I use for media, a Seagate 400GB and a WD 200GB.

I reinstalled Windows XP onto the 20GB boot partition and then SP1 so that I could accurately manage 137GB+ drives. Unfortunately, things didn't return (obviously) as they were before.

I previously had mounted the the WD 200GB (a drive for media) into a directory on the 400GB, effectively making it a "600 GB hdd". Now, however, the old 'mounted' WD 200GB drive isn't being properly recognized in Windows. It recognizes there is indeed a drive, but it appears as a blank, raw drive with no filesystem. All other drives (and partitions) are accurately displayed.

I used data recovery tools on the drive to see if my data had gone missing--it isn't, it's still intact. This leads me to believe (through my very ignorant knowledge of hard drives) that the tables which control filesystems are incorrect on the drive, possibly/probably due to it being 'mounted' in a hard drive directory previously. I've tried to Google for an answer here, but no luck, so I beg your assistance. I've tried the drive on multiple cables and IDE1/2 and master/slave, but no luck, Windows always fails to properly handle this one drive.

I refuse (unless that become my ONLY option) to let ChkDsk run its course on start up, as I've had it corrupt data on hard drives in the past when in similar situations. I think I need to force Windows to read this drive as the NTFS system it is.. but how? Or how to rebuild that table?

(I'm also aware that I could always buy a new HDD to copy the data to through a recovery program, but financially that isn't a good solution.)

If you need any other information, I will provide it ASAP. Thank you for your time!

--67.82.24.34 02:30, 7 July 2006 (UTC)MCS

I'd need some more information to be any help. Here are some basic questions to make sure I understand whats what:

• When you say you "mounted the the WD 200GB into a directory on the 400GB", how and what exactly did you do.
• What system were the drives working under, when they worked? XP? XP SP1? NT? 2000? ...?
• Basically, I need more understanding what's gone on. This is what I need, in summary:
  1. How were they set up when it worked, and what system were you running?
  2. How did they appear in Windows and under Disk management?
  3. What filing systems were you using (FAT32/NTFS) for each partition?
  4. What exactly did you do, or change?
  5. What works and what doesn't work now, after changing it?
  6. What have you tried to do, to fix or diagnose it, so far?

Answer those and I'll try to help you through it. Luck! FT2 ^{(Talk | email)} 20:48, 8 July 2006 (UTC)

PHP developing environment

I'm looking for a good (free) PHP developing environment. Any one got a suggestion? Oskar 03:48, 7 July 2006 (UTC)

I use the Eclipse IDE for Java work, but it is also compatible with PHP after a [free] plug-in is downloaded. I've found it nice, so that may be a good starting point. Titoxd^(?!?) 03:52, 7 July 2006 (UTC)

I use Notepad++ in windows and Kate in linux. Jon513 12:24, 7 July 2006 (UTC)

I also use Kate in KDE and Nano when I only have a shell. --Kainaw ^(talk) 16:34, 7 July 2006 (UTC)

I use TextWrangler on Mac OS X. It's awesome. --Fastfission 16:31, 7 July 2006 (UTC)

Try PSPad --83.161.99.21 17:22, 22 July 2006 (UTC)

Excel sheet to powerpoint

how to fit the excel sheet in power point slide?..i m getting lots of problems doing this.

You have already asked this question on the miscellaneous reference desk. Please do not double post. Your question has been answered over there. Iolakana|^T 10:45, 7 July 2006 (UTC)

Anti Gravity

Is it possible to achieve an anti gravitational effect on earth excluding the sensation aquired by allowing a plane to freefall. --74.136.8.13 05:36, 7 July 2006 (UTC)Anton

• monkey--152.163.100.74 05:50, 7 July 2006 (UTC)

I'm not certain what you mean by an "anti-gravitational effect", but we feel gravity when we're in contact with the ground or some solid object in contact with the ground. People in free fall (whether it be onboard an orbiting satellite, in a malfunctioning plane, or on an amusement park ride) will experience weightlessness. — Knowledge Seeker দ 05:56, 7 July 2006 (UTC)

You can achieve the effect of anti-gravity, but not anti-gravity itself. If you don't fancy the Vomit Comet, you could always ride a roller coaster, which is the same sensation but over a much shorter period of time, or sky diving. Scuba diving provides a similar sensation.--Shantavira 06:06, 7 July 2006 (UTC)

You could also sit yourself on some super powerful magnets, and make it appear as if you are defying gravity, but arguably that's no more anti-gravitational than sitting on the seat in your car.  freshofftheufoΓΛĿЌ  06:18, 7 July 2006 (UTC)

there's a company that used to make anti-gravity pads, but they went out of fashion about the same time red/blue 3-D theaters did. 82.131.188.167 06:20, 7 July 2006 (UTC).

[Edit conflict.. grrr] I suppose you mean weightlessness. As Knowledge Seeker mentioned, you feel the weight when there is gravity acting on you and when there is something obstructing your fall towards the object that is attracting you. When there is nothing to obstruct your fall, you actually move freely (fall) towards the object and also experience weightlessness. So in effect, whenever you fall towards earth, (in a plane, in a freefalling lift, jump from a height etc) you experience weightlessness. An exception to this could be Lagrange_points. I thought that these are the points in space where the gravities of two bodies cancel each other but the article seems to suggest some deeper meaning. I am not qualified enough to explain these Lagrange_points --Wikicheng 06:24, 7 July 2006 (UTC)

You've got the Lagrangian points basically right, though they're really not an exception. As you mention, you feel weight when there is gravity acting on you; at Lagrangian points, the net force of gravity is zero, so naturally an entity there would experience weightlessness. — Knowledge Seeker দ 07:33, 7 July 2006 (UTC)

Technically you are not weightless in freefall, weight is mass x gravity, you still have a mass, there is definately gravity, otherwise you wouldn't be falling. Philc _T^E_C^I 13:52, 7 July 2006 (UTC)

I expected one Lagrange point for a set of two bodies, somewhere in the middle where the gravitational pulls cancel each other. I was surprised to find 5 LPs and that too, not between the bodies!. I may need to read it properly to understand how --Wikicheng 08:19, 7 July 2006 (UTC)

Now I read it. I am wrong in saying that the gravitational pulls cancel each other at the LPs. But nevertheless, you do experience weightlessness at those points. --Wikicheng 08:53, 7 July 2006 (UTC)

Yes, I simplified it a bit too much; gravity does not necessarily cancel out at the Lagrangain points. I suppose the more accurate statement would be that an object at one of the Lagrangian points or at any other point in space would experience weightlessness, since as you point out there's nothing obstructing its path. It's just that the path at the Lagrangian points (or in orbit around Earth, etc.) is relatively stable an an object there won't soon arrive at a collision. — Knowledge Seeker দ 09:09, 7 July 2006 (UTC)

Oh ye of little faith. Who are we to say we will never achieve a device capable of "anti-gravity"? As per the reader's questions, which seems to pertain to current technology, the answer is yes - the buoyancy force provides an excellent anti-gravitational experience; just jump in the ocean with a scuba tank, and eventually you will descend to a depth at which you are the same density as the water. At that point, gravity will be cancelled out. If you're looking for something which actually "blocks" the gravitational field, the answer is, not yet. --Bmk 16:49, 7 July 2006 (UTC)

In the case of immersion, would there not still be the effect of gravity making a difference in fluid pressures and distribution inside the body? --Seejyb 19:31, 7 July 2006 (UTC)

You're right - it isn't exactly like the absence of gravity, but some of the effect of the gradient of gravity is eliminated because there is also a gradient of water density; i.e. gravitational potential decreases downward, but buoyancy increases. In any case, I agree with Seejyb - it won't be exactly like weightlessness, but similar. I know NASA sends astronauts into big pools in spacesuits to simulate zero-G working conditions. --Bmk 00:08, 8 July 2006 (UTC)

Sounds like what the question is asking is whether gravity is polar like a magnet which to the best of our current knowledge it is not. But who knows what the case might be with anti-matter. Instead of particles attracting maybe anti-matter particles push each other away. ...IMHO (Talk) 20:07, 7 July 2006 (UTC)

See gravitational interaction of antimatter. --cesarb 23:38, 7 July 2006 (UTC)

Forget about calculating Langrange points. Take up yogic flying, then you can help create world peace at the same time ;-) --Shantavira 09:08, 8 July 2006 (UTC)

i've heard that sleeping straight is good for health means on back...but sleeping opposite with your front facing downward is bad for health...how true is this????

sleeping

my question is "is there any rules exist for sleeping?"...means how to sleep?...wat are the ways to take most relaxing sleep?—Preceding unsigned comment added by 80.247.152.121 (talk • contribs)

I suggest you read our very comprehensive article about sleep, then come back here if you have further questions.--Shantavira 09:44, 7 July 2006 (UTC)

I think it will help to sleep better if one stop thinking about "rules" for sleeping when going to bed.--Vsion 22:49, 8 July 2006 (UTC)

Generally, at the time you're trying to sleep, I find there's little you can do if you can't sleep. It's something that your body just does, and it's hard to force. Overall, making sure you go to bed at the same time every night, are relaxed (warm baths and warm uncaffeinated drinks can help, as can relaxing music), the right temperature and in calm surroundings. Block as much light from entering your room as possible. Try to quieten your mind, keep it from racing. Chanting/repeating some calming phrase in your head and concentrating on it can help. (For example, some prayer or pattern of prayer from your religion, some relatively long poem or nursery rhyme that you are very familiar with). If you are having trouble sleeping, and this lasts a long time, you might want to visit a doctor and ask his advice. Skittle 18:35, 9 July 2006 (UTC)

As Skittle said, try making yourself as comfortable as possible. Don't worry if you can't fall asleep--if you worry, it'll be even harder to sleep. Also, strangely enough, I fall asleep quicker if there is an intense light being reflected onto my eyelids (for example, in a sunny afternoon when the Sun is not shining directly into my window). --Bowlhover 04:38, 10 July 2006 (UTC)

"Trying" to do anything at all will hinder the onset of sleep. Letting it happen is a much better approach. JackofOz 00:49, 12 July 2006 (UTC)

Electrolysis

Im sure that there is a simple answer to the question but not to ask is a greater ignorance than to not know. Would it be possible to create a divice that splits water (electrolysis)underwater and guides the bubbles into a tube to be used to breath underwater? Perhaps there is a problem with breathing pure oxygen.

Actually that's what submarines do - that's why they can stay underwater for years (problem is the food doesn't last that long) --mboverload@ 06:53, 7 July 2006 (UTC)

But it requires a lot of energy so don't count on using it in a diving suit. -Mgm|^(talk) 07:31, 7 July 2006 (UTC)

Indeed. Very large amounts --mboverload@

FROM THE SUBMARINE ARTICLE --mboverload@ 09:43, 7 July 2006 (UTC)

With nuclear power, submarines can remain submerged for months at a time. Diesel submarines must periodically resurface or snorkel to recharge their batteries. Most modern military submarines are able to generate oxygen for their crew by electrolysis of water. Atmosphere control equipment includes a CO₂ scrubber, which uses a catalyst to remove the gas from air and diffuse it into waste pumped overboard. A machine that uses a catalyst to convert carbon monoxide into carbon dioxide (removed by the CO₂ scrubber) and bonds hydrogen produced from the ship's storage battery with oxygen in the atmosphere to produce water, also found its use. An atmosphere monitoring system samples the air from different areas of the ship for nitrogen, oxygen, hydrogen, R12 and R114 refrigerant, carbon dioxide, carbon monoxide, and others. Poisonous gases are removed, and oxygen is replenished by use of an oxygen bank located in a main ballast tank. Some heavier submarines have two oxygen bleed stations (forward and aft). The oxygen in the air is sometimes kept a few percent less than atmospheric concentration to reduce fire danger.

There is a problem with breathing pure oxygen, but seeing as when you breathe you don't use up any of the other compunds, or molecules in the air, you can re-use them. So as long as you start with a bit, its ok. Philc _T^E_C^I

13:48, 7 July 2006 (UTC)

If I recall correctly, a person needs about 6 liters of oxygen per minute, and the electrolysis of water into hydrogen and oxygen takes a minimum of 1.7 volts. Are these numbers anywhere near correct?So what amperage wold be required (i.e, how much power) to liberate 6 liters per minute of oxygen at some reasonable temperature and pressure? Surely the contributors here can do better than "a lot of energy."Edison 20:36, 16 July 2006 (UTC)

don't forget rebreather article! 82.131.184.144 15:51, 7 July 2006 (UTC).

Sleeping in a dark room is very important, and the ideal temperature is 16°C. When I cannot sleep I read for a while, or go and edit Wikipedia. If you do this in a low light environment, then you will get sleepy quite quickly. -Wser 12:28, 14 July 2006 (UTC)

Two Wikipedia Pages

There are two pages on wikipedia I have found in the past and can't seem to find anymore.

• List of most edited wikipedia articles
• List of the longest wikipedia articles

Any help? --Russoc4 14:32, 7 July 2006 (UTC)

Try Special:Specialpages.
 SLUMGUM  yap  stalk  14:41, 7 July 2006 (UTC)

See also the offline reports at Wikipedia:Maintenance#Reports. --cesarb 15:37, 7 July 2006 (UTC)

Muchas gracias. --Russoc4 17:08, 7 July 2006 (UTC)

Many such pages can no longer exist due to software upgrades. //Ae:æ 03:21, 8 July 2006 (UTC)

As to the original question, the direct links would be Special:Mostrevisions and Special:Longpages. Titoxd^(?!?) 03:36, 8 July 2006 (UTC)

energy band

why energy levels are parabolide in shape in E-K diagrams?

Sorry, not sure what you mean. Please be much more specific and clear. Are you perhaps talking about the potential of a quantum harmonic oscillator? That's the only thing that rings a bell, but i'd rather not spend time answering without clarification. --Bmk 19:37, 7 July 2006 (UTC)

windows on ships

hi, in the UK we have this guy called stelios someone. anyway he runs a low cost airline (easy jet) in europe and last year launched a similar concept for cruises (called, easily enough, easy cruise). anyway, the cabins in this ship dont have windows -he claims this way he can reduce his costs. i cant actually believe this but neither can i see any other advantage in not having windows. is having windows (by which i mean the small circular port hole things, not vast great french windows looking out on to the horizon) expensive? if so, why? thanks 201.32.177.211 18:33, 7 July 2006 (UTC)

Offhand guess - his ships are cheap because they're converted freighters, and one of the ways to keep a conversion cheap would be to not add windows. But I really don't know. Shimgray | talk | 18:53, 7 July 2006 (UTC)

According to our article, The cabins offer a simple bed and bathroom: most do not have windows (although that is changing to make all the rooms have windows). I suspect he charges less because he can carry more passengers by having more cabins (since they don't all have to be along the sides of the ship). Perhaps the extra cabins are going to have windows onto the corridor rather than onto the sea? Henry^Flower 19:18, 7 July 2006 (UTC)

I don't understand why it is difficult to understand that not adding windows is cheaper than buying windows, cutting holes in the ship, mounting the new windows, and then sealing them. If you don't add windows, there's no cost. If you do add windows, there is the cost of supplies and labor. --Kainaw ^(talk) 19:34, 7 July 2006 (UTC)

I got three lettors for you: T, C, and O. Total Cost of Ownership. TCO. Just Google. 82.131.184.144 22:36, 7 July 2006 (UTC).

I know that windows in the hull of a ship are round because square ones tear at the corners. But maybe round ones also weaken the hull, making it necessary to make it heavier or something. But even local reinforcements will add to the cost and if you offer travel at dirt cheap prices you need to cut every corner.

By the way, imagine ships not having to pay taxes on fuel, like airplanes. Airlines would go out of business in a massive way. But that's a different issue. DirkvdM 19:40, 7 July 2006 (UTC)

This is rather offtopic, but I strongly doubt it. Commuting by ship had largely died by the 1960's; plane travel was much, much more expensive then than it is now. In any case, you can buy a New York-London return plane ticket for 500 USD; even using a 40 knot ship and assuming Plymouth as a departure point rather than London, it still takes 72 hours to do New York-Plymouth. Feeding somebody half-decent food for six days (return) costs at least 150 USD or so. If you assume 20 USD per night for the cabin, that's another 120 USD. So that's 270 USD, conservatively, before we've even moved the ship anywhere. So, at a maximum, we're going to save in the order of 200-250 USD by taking the ship, at the cost of six days on the ship against one day (total) on the plane. Most international travellers earn considerably more than 250 USD per week. --Robert Merkel 03:52, 8 July 2006 (UTC)

Two things. One, you're talking about Europe-US. Those are the cheapest airfares around, I believe. In stead, try the Caribbean. Two, after the 60's, a new phenomenon arose, the budget traveller. There's loads of (mostly young) people around these days who have a fair bit of money (compared to the 50's), though not too much (compared to holiday making families) and loads of time. On a half year trip a few days on a boat won't make that much of a difference. And you don't get jet lagged. And it's not cramped. And you get to meet other budget travellers. And ehm, on international waters, so ... tax free alcohol?

I've been a budget traveller for several years, so I know what I'm talking about. A 300 euro trip to the Caribbean? Yeah man, cool! In Indonesia they've got these island-hopping Pelni ships that are a real cool way to travel and meet people. I suppose the 'meeting people' thing is the most important. Along with the price. DirkvdM 08:49, 8 July 2006 (UTC)

Ah, I've checked their website [1] and after starting in Europe, their next destination is ... the Caribbean. I had thought of this myself years ago, but I lack both the money and the entrepreneurial instinct to set something like this up. However, I could try applying for a job with them. Doing this trip and getting paid for it! How cool is that? Of course, I'll have to work too. Bummer! :) DirkvdM 09:02, 8 July 2006 (UTC)

ANCIENT BEER

I HAVE BEEN TOLD THAT ANCIENT PEOPLE WHO MADE BEER DIED FROM ITS USE. IT HAS BEEN EXPLAINED TO ME THAT THE PROCESS THEY USED DID NOT FILTER OUT IMPURITIES THAT MAY HAVE MADE THE BEER TOXIC. IS THIS TRUE? —Preceding unsigned comment added by 164.156.127.28 (talk • contribs)

Please stop yelling (using all caps). There is no mention of death by impurities in history of beer, but it is rather silly to think that beer didn't have impurities or go bad long before refridgeration. --Kainaw ^(talk) 19:31, 7 July 2006 (UTC)

There is some truth behind that. Before the introduction of hops other bitter herbs were used to flavor and preserve beer, some of which were indeed toxic in large quantities. The keyword here is gruit. One must also remember that in former times people would consume large quantities of beer because it had been boiled and thus was safer than water. Dr Zak 20:07, 7 July 2006 (UTC)

On a related point, my understanding is during days of yore, because beer is fermented, weak beer/wine was actually used as the common drinking liquid instead of water, which would often harbor microorganisms that would cause illness. So while deaths may have come from beer impurities (and don't forget ethanol itself is toxic in large amounts, like everything), probably beer saved more lives (or at least delayed deaths) more than it took. 128.197.81.223 21:56, 7 July 2006 (UTC)

No pathogenic (disease-causing) microorganisms can survive in beer. Therefore, beer (filtered or not) is not toxic, except in the case of alcohol poisoning, unless toxic substances are added (a la Dr Zak's herbs). In fact, homebrewers regularly consume unfiltered beer, and some styles such as hefeweizen are sold commercially without filtration. --Ginkgo100 ^{talk · contribs} 03:49, 8 July 2006 (UTC)

Another point that I should mention -- beer brewers are very careful to keep all equipment and wort (unfermented beer) as sanitary and microorganism-free as possible. However, the consequences of bacterial contamination are not potentially toxic, just potentially ruinous to the flavor of beer. Brewers of lambic beer are an exception; they encourage the growth of wild bacteria and yeasts. --Ginkgo100 ^{talk · contribs} 03:52, 8 July 2006 (UTC)

A tv documentary years ago on the workers who built the pyramids said that archeology shows that the workers diet consisted of onions, garlic, bread and beer. You could do worse. Also I'v read the statement that it was considered healthier in general to drink beer than to drink water in many European countries pre-20th century because the boiling as part of the brewing killed pathogens found in river water and some well water.Edison 20:43, 16 July 2006 (UTC)

Agent Orange

What chemicals does 2,4,5,T break down to? 2,4,5,T is one half of Agent Orange.

Burkholderia cepacia can break down 2,4,5,T in the chain shown here [2]. This [3] abstract claims that 2,4,5,T was broken down by non-adapted sediment microorganisms first into 2,5-Dichlorohydroquinone (as in the previous link) but then into 3-chlorophenol and phenol (but notably without apparent 2,4,5-trichlorophenol as an intermediate, unlike as in the first link). It is thus likely that the intermediates and end products vary from organism to organism, but it appears some steps are common, at least in the information from the two links above. As to what it breaks down to on its own, I do not know. 128.197.81.223 22:07, 7 July 2006 (UTC)

According to this article about a selectively bred organism, Pseudomonas Cepacia, which readily breaks down 2,4,5-T, 2,4,5-T is very recalcitrant to spontaneous degradation, and are usually slowly broken down by natural soil bacteria. However, I did finally find an article here from "Inchem" that seems to deal significantly with the spontaneous (non-biological) breakdown of 2,4,5-T. To summarize, the article seems to say that when it travels through biological pathways, i.e. bacteria, the intermediates vary widely, but the end products are mostly carbon dioxide, inorganic chlorides, and water. However when 2,4,5-T is broken down through photolysis, i.e. sunlight, the end product is 2,4,5-trichlorophenol. This product will not be detected often because it is more easily metabolized than 2,4,5-T.

It may also be of interest that during the manufacture of 2,4,5-T, some amount of 2,3,7,8 tetrachlorodibenzo-p-dioxin (TCDD) is also produced. If the reaction is carefully temperature-controlled, TCDD levels can be minimized. TCDD is (according to our article and [http://www.pesticideinfo.org/Detail_Chemical.jsp?Rec_Id=PC35857#Toxicity this]) a serious human and environmental toxin, although it is not a breakdown product of 2,4,5-T, just a byproduct of synthesis. --Bmk 05:50, 8 July 2006 (UTC)