Wikipedia:Reference desk/Archives/Science/2006 July 17

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Is Gadolinium(III) Oxide magnetic?

When Gadolinium oxidizes is it still magnetic like Magnetite or does it lose that property?

gadolinium metal and magnetite are ferromagnetic. the gadolinium in Gd2O3 is in the [Xe]4f7 electronic state, so it is going to be paramagnetic, a different and weaker form of magnetism. but due to the lack of symmetry in the f-orbitals, the [Xe]4f7 state is extremely paramagnetic, the most of any known element. this fact is exploited to make contrast agents for MRI. Xcomradex 04:14, 17 July 2006 (UTC)

So if its extremely paramagnetic, does that mean it is more or less attracted to magnets?

That means it is repelled by magnets... (paramagnetism) — The Mac Davis] ⌇☢ ญƛ. 21:30, 17 July 2006 (UTC)

it means it is attracted to magnetic fields. diamagnetic objects are repelled by magnetic fields. but remember in each case, the effect is generally quite weak. for Gd₂O₃, the mass susceptibility is 668.5, but for Gd metal its a whopping 9488. so Gd metal is much more magnetic than Gd₂O₃. for a gentle walkthrough, http://www.sigmaaldrich.com/Area_of_Interest/Chemistry/Materials_Science/Energy_Source_Materials/Magnetic_Materials/Tutorial/Properties.html Xcomradex 22:35, 17 July 2006 (UTC)

Gallbladder

On average, how much does a gallbladder weigh?

• Depends on what kind (whale gallbladders are heavier than human gallbladders, I'm guessing), and whether you count the bile. Deltabeignet 08:42, 17 July 2006 (UTC)

For an experiment I did back in undergrad college, I needed the average weight of a human hand. It is a rather hard thing to figure out. My solution was to go to the biology office and look in the body parts catalog for human hands and look up the shipping weight of them. I found that I could order them in lots of 100. So, I called and got the shipping weight of 100, divided by 100 and rounded down a tad (to eliminate packaging). Then, turned in my report and forgot the weight - dumb class. Anyway, that may help. If you have access to a biology lab that can order body parts, I'm sure a gallbladder is something that can be ordered. --Kainaw ^(talk) 12:19, 17 July 2006 (UTC)

Couldn't you have just elevated the forearm and let the back of the hand fall on a scale? Or am I missing something?--Pharos 15:49, 20 July 2006 (UTC)

No matter what you do, the arm attached to the hand will affect the weight. Either it will support some of the weight by being too high or add to the weight by being too low. But, I tried that method many times and the average wasn't even close to the actual weight. --Kainaw ^(talk) 12:20, 24 July 2006 (UTC)

I would be refering to a human gallbladder...

GIS data

Does anyone know of any free software that can be used to look at GIS data. The data I have is in ArcInfo, ArcView or MapInfo format. --Peta 04:40, 17 July 2006 (UTC)

GRASS GIS might be overkill if you just want to view the data, but it should do the job. Here's some tips on importing data from ArcGIS. -- Avenue 10:43, 17 July 2006 (UTC)

what type of acid can conduct electricity better.

which one of the below?

citric acid,tartaric acid,malic acid,formic acid,hydrochloric acid,lactic acid,ethanoic acid,tannic acid and carbonic acid.

if one of them is the one that can conduct electricity better then why is that so? and the one that did not conduct electriccity wellthen why is that so.--

Homework? :) -Obli (Talk)^? 09:00, 17 July 2006 (UTC)

The homework acid is a bad conductor in the science reference desk. But read your textbook acid may help --Wikicheng 10:52, 17 July 2006 (UTC)

See the articles on strong acid and weak acid. --71.246.9.190 01:17, 18 July 2006 (UTC)

Supersonic Passenger Flights

Supersonic passenger flights were begun in the 1970"SBY France, England, and then Soviet Union. However, the two supersonic airplanes used, the Concorde and the 144, are now grounded and supersonic flights are no longer available. Comment on the technological debacle. What type of thinking was behind these grand technological ventures? (question rewritten ;)

Please dont shout by typing in all capitals. Have you tried looking at Concorde and Supersonic Flight? Please come back here if you have any more questions. Jayant,17 Years, India • contribs 11:24, 17 July 2006 (UTC)

And at least try to make a token effort to disguise your homework question... *sigh* (Tupolev Tu-144 may also be of interest to you). — QuantumEleven 11:37, 17 July 2006 (UTC)

Please do your own homework.

Welcome to Wikipedia. Your question appears to be a homework question. I apologize if this is a misinterpretation, but it is our aim here not to do people's homework for them, but to merely aid them in doing it themselves. Letting someone else do your homework does not help you learn nearly as much as doing it yourself. Please attempt to solve the problem or answer the question yourself first. If you need help with a specific part of your homework, feel free to tell us where you are stuck and ask for help. If you need help grasping the concept of a problem, by all means let us know. TenOfAllTrades(talk) 13:08, 17 July 2006 (UTC)

Best scanner for books/magazines?

Hello there,

I'm interested in finding the best scanner for digitizing whole books and magazines. Is there a brand and model that's preferred in terms of speed and quality? I've tried using a Minolta X60 camera with text setting, but so far the results after OCR have been disappointing. Does anyone have experience with Canon Canoscan, HP Scanjet, or another brand who can speak to this?

Mjklin 12:30, 17 July 2006 (UTC)

Gee, that sounds like a neat project... Try contacting Google, and ask them about their success in scanning books and such. --Zeizmic 13:05, 17 July 2006 (UTC)

A camera won't be of much use, but any modern scanner will do the job. Do you only want page images, or are you hoping to use OCR? OCR does not work well on magazines and older books. What is far more critical than the make of scanner is the software you use (see optical character recognition), the clarity of the original print, and the computer memory available, as you will want to run all the page images together. You should note that what you are trying to do may be illegal, depending on the age of the books and your purpose in copying them.--Shantavira 14:08, 17 July 2006 (UTC)

As someone who has spent considerable time digitizing books and magazines for his own research purposes, I can say that OCR doesn't actually do that bad with magazines and older books if the original text is relatively clean. It's not usually good enough to just copy-and-paste into a document but it is usually good enough to search for specific names and things like that. As for the legality, if the person is using it for their own personal research then it falls under fair use. If they are distributing them to others, that's a copyright issue (if the works are still copyrighted). --Fastfission 15:08, 17 July 2006 (UTC)

I have a Canon Canoscan LiDE. I bought it because it was cheap (around $50 at the time), light (uses LCDs so it weighs as much as a textbook), and small (can fit into my backpack), so I can take it with me to libraries or archives to scan things right then. The OCR function works well. It is not very fast, though — it can take upwards of 20-30 seconds to scan a page of text in, which is eons when you are trying to scan anything of any length. As an image scanner the quality isn't the best, but as something you can lug around it is great.

For digitizing a whole book, there is nothing better than a photocopier with a scanner attachment. Many modern photocopiers can scan, and there are some which are set up to do nothing but scanning (I think the kind I use is made by IKON, it is at a nearby library). The problem is that they cost many thousands of dollars. But if you can find a place that has them, then you are set—they scan as fast as a photocopier does, which means that you can scan a 300 page book in an hour or so if you are so intent on doing so. I suspect something like this is what Google uses—at 1-2 seconds per page it is the only thing worth messing with. --Fastfission 15:08, 17 July 2006 (UTC)

I'm so glad the people I need to talk to have found me! :) I'm using OmniPage Pro for OCR, which does pretty well with my digital camera images but will do even better (I believe) with pages that are not just held open with my fingers or a hard plastic plate. This is wholly for my personal use...just to cut down on the number of books in my room, which is considerable.

I found this contraption made out of Lego for automating the task of scanning books...it looks good but I wonder if it will work with every kind of book and magazine. And I can't really see lugging that into a library! BTW, what do librarians have to say about scanning books right there? Mjklin 16:03, 17 July 2006 (UTC)

I wouldn't trust something like that to work accurately. Honestly, if you have a fast scanner, it does not take that long — around an hour per book, which isn't that bad, and you usually end up with a pretty high quality product. As for librarians.. I usually go somewhere where there aren't any librarians (mostly because scanners are somewhat noisy), or I go to where the photocopy machines are (since those are noisy too). As for copyright issues, most librarians don't seem to care at all — they've got bigger fish to fry than worry about what I might or might not being doing with the copyrighted content of their books (and in any case they are more oriented around helping the patron rather than restricting him/her). The only thing they care about is whether or not you are man-handling the books, which is a legitimate concern — in order to get a good scan you often have to push the book down pretty flat on the scanner bed, which I imagine probably does do some damage to the spine. But I usually justify it to myself that in the end, digitizing a book means less net wear-and-tear in the long run.

BTW, I checked and the photocopier/scanner was made by Canon, with the scanning software made by IKON (Docsend). --Fastfission 16:08, 18 July 2006 (UTC)

Micrometer tolerance

What is an approxiamate value for the tolerance of a micrometer that is in the measuring range of 0-25mm. I found a result on one website of ±1μm. However I was told that this is too small and I should expect a value of about 10μm. Thank you --Me22ac 13:31, 17 July 2006 (UTC).

Those are both approximate values for tolerance. It depends on and varies hugely with what kind you are using, how old it is, etc. There's no way to tell except in the owner's manual of an individual instrument. Registrar

This one puzzled me for a sec. The tolerance of a micrometre expressed in micrometres? Turns out EE/AE spelling here determines whether it's a unit of measurement (micrometre) or a tool (micrometer). According to the Wikipedia articles, that is, but I suppose that just happened to be convenient considering the other unit spellings. In AE the unit will probably also be spelled as 'micrometer', which would be some cause for confusion. But then USians would be used to that, with a bathroom really being a toilet and the south of America not being the same as South America and that sort of thing. :) DirkvdM 19:36, 17 July 2006 (UTC)

When I worked in a testing lab, measurement was strictly in either decimal fractions of an inch (0.6251 inch, for example), or strictly in decimal fractions of a millimeter (3.0047 mm). There was never any confusion, since the term "micrometer" referred strictly to the instrument doing the measurement. --Serie 22:04, 17 July 2006 (UTC)

If you used inches, that must have been in the US, where units are seen as separate entities. Those who are used to the SI system, however, see them as part of a continuum. To only use mm for length would be silly. You wouldn't express the size of your house or an atom in mm. Unless everything you measure hapens to be in the mm range, which may have been the case in that lab. And expressing something in the inch range in mm wouldn't be too strange, so why did you complicate things by using two unrelated units for the same quantity? DirkvdM 06:44, 18 July 2006 (UTC)

The largest object ever to come through the lab was a steel bar about four feet long, and the smallest was sheet metal about a hundredth of an inch thick, so using only inches when we needed imperial units and only millimeters for metric worked pretty well: we just needed to check to see if the test equipment was in imperial mode or in metric mode. Sure, we could have used the full range of metric: meters, millimeters, and micrometers, but that would introduce an unneccessary failure mode of entering a measurement with the equipment set for the wrong metric units.

Of course, sometimes the person we were doing the work for wanted the results in oddball units, in which case we'd do the testing in imperial, then figure out the conversion -- for example, a customer asked for pressure measurements in kilograms per square inch once. --Serie 22:11, 18 July 2006 (UTC)

A mixup between units is more probable with mm and inch because they differ a factor 25. With the standard SI prefixes the units differ a factor 1000. Actually, they're not different units, it's all still the same unit, with a different way of say 'ten to the power something'. If customers specify what they want in inches, I suppose it makes some sense, but even then you could make the conversion 'at the gate' and work with just one unit internally to avoid mixups. DirkvdM 06:29, 19 July 2006 (UTC)

Starrett is a well known maker of micrometers. Their 1998 catalog has a list of their accuracy standards. A 25 mm micrometer has an accuracy of +- 0.002 mm. Gerry Ashton 19:04, 18 July 2006 (UTC)

isnt the accuacy of a measuring tool simply half the smallest measurment you can make using it? eg if the smallest divide represented 1mm then the accuacy is +- 0.5 mm--Colsmeghead 21:38, 18 July 2006 (UTC)

That's resolution - what magnitude of change can be measured with an instrument. Contrast with accuracy and precision: http://en.wikipedia.org/wiki/Accuracy_and_precision

Image Tiler

Is there a program that will take an image file, tile it, and save it to another file? I want to tile the image a lot. The max amount of tiling might be 1680x1050. The image is 3x3, so the output would be 5040x3150 pixels. --Shanedidona 14:34, 17 July 2006 (UTC)

Usually the easiest way to do this is to use a program that has a "pattern brush" or "pattern fill" or something like that. Photoshop can do this easily, and I have never tried it in GiMP but I find it hard to believe it doesn't have something like this, as it is a pretty common feature. --Fastfission 15:12, 17 July 2006 (UTC)

Yes, GIMP has it. It also has an option to make an image seamless so it will tile without seeing the hard edge where the tile begins and ends. --Kainaw ^(talk) 15:17, 17 July 2006 (UTC)

I suppose Shanedidona meant automation. Photoshop (the only reason to still use msWindows) has such functionality - do it once, record that and then do the same to any file with the push of a button. The result can then be saved to the same file or as a separate file (in a different directory) as you asked. And you can do batch processing too, doing the same thing to all files in a directory. But doing the same to the same file over and over again, I can't imagine how that could be done. DirkvdM 19:42, 17 July 2006 (UTC)

Top-selling PC manufacturers

This is more of a business question than a tech question, but:

Who are the top-selling (either in $ or in units sold) manufacturers and merchants of personal computers for the USA market? Ideally, I'd like a list of most sales in the past 12 months. I'm looking for the companies whose names go on the box, like Dell and Gateway, not stores like Circuit City or parts makers like Intel. If I can clarify my question, please ask; I'll be monitoring this page for the next couple days. Thanks in advance! --M@rēino 14:38, 17 July 2006 (UTC)

In 1999 or 2000, Dell became #1 and Compaq became #2. I don't know what's happened in the last 6 years. IDC is the company that tracks that stuff. --Kainaw ^(talk) 15:00, 17 July 2006 (UTC)

here is the 2004 data and here is some newer stuff. Just google "computer market share" and other varients of that. - Registrar

• Thanks. And it looks like I can contact the company that did those market share surveys if it turns out that I need the professional-grade depth of data.--M@rēino 12:41, 18 July 2006 (UTC)

What is anticipation.

I have read an article about Huntingtons disease. In the para of genetic causes it was mentioned that,

When the gene has more than 35 repeats, the replication process becomes unstable and the number of repeats can change in successive generations. If the gene is inherited from the mother the count is usually similar, but tends to increase if inherited from the father.[3] Because of the progressive increase in length of the repeats, the disease tends to increase in severity and present at an earlier age in successive generations. This is known as anticipation.

But still i am confused can you tell me what it means by progressive increase in leangths of the repeats. Can you please explain me the concept of anticipation. Mail me at-(e-mail address removed)

See Trinucleotide repeat disorders for a brief explanation. The Huntington's disease gene contains a 3 nucleotide DNA sequence (CAG) that is repeated (ie. CAGCAGCAG...). The normal allelle has 10-35 repeats of the CAG sequence, but because of errors in DNA replication, a gene with over 40 repeats is possible. With each generation of DNA replication, more CAG sequences are added to the gene. The longer the CAG repeats, the more severe the disease. With each generation, the disease is more severe and/or occurs earlier - hence the term "anticipation". I hope this helps. - Cybergoth 17:15, 17 July 2006 (UTC)

I should hope that this article knows more: Anticipation (genetics). --Jmeden2000 17:11, 17 July 2006 (UTC)

Citing a software program

I would like to expand some of Wikipedia's star stubs using information available in a freeware computer application I recently downloaded. The program is called "Celestia", its website is <http://www.shatters.net/celestia/>, and as I mentioned, it's freeware (but I don't believe it is open source). What is the proper format for citing a software program in an article?

Sadachbia 15:31, 17 July 2006 (UTC)Cheli Winkler-Groschen (Sadachbia)

I'm afraid it might not be possible to cite the results of a software simulation -- I think it would count as original research unless the information you're talking about could be found in the source code itself. --Allen 16:04, 17 July 2006 (UTC)

I looked on the website, and it states that the code is licensed under the GNU public licence (the GPL). I've been led to believe that the GPL is incompatible with the GDFL, but I'll leave the wrangling to someone who actually understands copyright. --Sam Pointon 16:14, 17 July 2006 (UTC)

Facts are not eligible for copyright, so the license makes no difference as long as we're not copying any creative content verbatim. After all, how else could we cite copyrighted books and journals? —Ilmari Karonen (talk) 16:37, 17 July 2006 (UTC)

Are you sure you don't actually want to cite the documentation? I'd say there's no problem treating a computer program as a primary source about itself, as long as you cite it in such a manner that anyone with access to the program can easily verify the information. For open source programs, I suppose you could cite the source code too. Of course, as with any primary sources, citing a program or its source code should be avoided if there are suitable secondary sources (documentation, tutorials, reviews, etc.) available.

Going off on a tangent, it occurs to me that there are also situations where a computer program could be a secondary source. For example, my local library has a copy of an interactive taxonomic database of Finnish polypore fungi on a CD; the program is closed source and the database itself is in some proprietary format, but the information is nonetheless quite easily accessible through the front end and could certainly be cited in an article. As it happens, is this case there are print sources that are much more comprehensive than the CD, so I don't think there's any need to cite it in practice. But in principle there could be. —Ilmari Karonen (talk) 16:33, 17 July 2006 (UTC)

Be WP:BOLD. Add the info anyway, saying you've used the program to get it. If someone who doesn't like it comes along they can change it to another source (I'm pretty sure info on stars can be found on a range of sources). If you're worrying about format just use something like:

<ref>[http://www.shatters.net/celestia/download.html Celestia v1.4.1]</ref>

- Dammit 18:58, 17 July 2006 (UTC)

You may want to see the wikipedia article on celestia first --Wikicheng 19:40, 17 July 2006 (UTC)

changing IP addresses to another country

--146.96.224.150 17:47, 17 July 2006 (UTC)Here's a question I've been looking into for a while...I live in the US, so I assume my IP address indicates this. There are some internet sites that restrict access to certain countries. For example, the BBC had live streams of World Cup matches, but I wasn't able to watch from work on my pc because my computer has, obviosly, an "American IP address" but I would have needed a "British IP address". I looked online for a few hours to try to figure a way, but in the end I just ended up taking long lunch breaks and watched the football matches at a bar.

I know that VPN clients essentially give you an IP address from where ever the host is located, but is there a nifty way to just change IP addresses to another country? Since I don't need to stream football from the BBC any longer, this is a moot question, but I'm interested to see if there is a way.

--146.96.224.150 17:47, 17 July 2006 (UTC)RC

• Yes there is, all you have to do is find a list of proxies somewhere, once you find one from inside the UK all you have to do is go into Control Panel, then Internet options, select the connections tab, click on Settings, then check off the box that says use a proxy server for this connection, then simply fill in the proxy of your choice--172.145.64.188 17:51, 17 July 2006 (UTC)

• The only thing is, these proxies don't last very long, so if you do find a list of open proxies somewhere, you may have to try several dozen before you find one that still works, also you need the port number, so While 255.255.255.255 is an IP, you'd need the prt number, given like this 255.255.255.255:8080 where the first part goes in the first box Address, and the 8080 goes in the second box Port, and the : you don't use at all--172.145.64.188 17:54, 17 July 2006 (UTC)

• Also, you can use WHOIS to find out which country a given IP comes from, and keep trying until you find one registered to the UK. There are some limitations though, certian types of ISPs already have their own proxy system, which will stop this from working correctly--172.145.64.188 17:56, 17 July 2006 (UTC)

• Also part II, since open proxies tend to be a source of vandalism, wikipedia has some very complete lists of blocked open proxies, if you're having a hard time finding a proxy list with active proxies, wikipedia itself would be just as effective, although good luck finding any port numbers here--172.145.64.188 17:57, 17 July 2006 (UTC)

You could use Tor, then switching circuits(get new identity) until you are routed over your desired country. helohe (talk) 00:13, 21 July 2006 (UTC)

Earth's freefall acceleration.

We all know the given 9.8 meter/second squared, but that's for the theoretical non-air resistance constant.

Then, we always assume we fall slower than that counting air resistance. So, what would be an approximate value counting air resistance? In reality, it would have to be less than 9.8 meters/second squared. And, let's just say, I'm at 42 degrees North latitude, or in Chicago. Elevation about 600 to 700 feet. Thanks.

If you fall far enough, you reach a terminal velocity due to air resitance. After that point your acceleration is zero as your speed stays constant. Parachutes, for example, do not accelerate as they approach the ground.

If you consider air resistance, then you can not arrive at an apparent value of g. That is because the air resistance depends on the shape of the falling object and also on the velocity. More the velocity, more the resistance and hence all falling objects reach the terminal velocity. Once an object reaches the terminal velocity, it falls at the same velocity till it reaches earth. See the article on terminal velocity --Wikicheng 19:47, 17 July 2006 (UTC)

Alright, so, let's assume the shape of the body is an upright human, that will land on 2 legs. Of course, I'm talking about approaching terminal velocity, not at free fall. I don't care so much at how long it will take to reach terminal velocity at a speed of 120 miles per hour (or 200 if standing upright), but I guess you're saying there's no approximate value. If the Earth had no air, then jumping of 32 feet per second squared implies in 1.0 second I fall 32 feet (which comes out to be around 22 miles per hour), but how much would it be approximately if there were air? NealIRC 17 July 2006

If there is no air resistance, the velocity of a falling human will will increase indefinitely, according to v=u+at, irrecspective of his position or orientation. But with air, his velocity will increase till it reaches the terminal velocity (120 mph if he is in normal skydiving position or 200 mph if he is in upright position) and then he will fall at the same velocity. Once the terminal velocity is reached, there is no acceleration -- Wikicheng 08:09, 18 July 2006 (UTC)

Unfortunately, air resistance (to a rough approximation at low speeds) is propotional to velocity squared. Gravity is not a velocity-dependent force (ignoring for the moment relativistic effects :) ). So, when you consider air resistance, you must solve an entirely different differential equation:

instead of

$m{\frac {d^{2}x}{dt^{2}}}=-mg$

we get

$m{\frac {d^{2}x}{dt^{2}}}=-mg+b\left({\frac {dx}{dt}}\right)^{2}$

(b is a constant related to the shape of the object and the atmospheric conditions) I have no clue what the functional solutions of this look like, but it doesn't have simple quadratic solutions, so there is no "modified" gravitational acceleration for air resistance.

In fact, this would be a good question for the math desk - if you're still interested, ask them for the first four terms of the taylor series approximation of the solution of this equation - one term should look like $kx^{2}$. The value $2*k$ should be a rough approximation of the "modified" acceleration of gravity. Honestly, though, it won't be much use - it isn't really a good approximation anyways. --Bmk 21:42, 17 July 2006 (UTC)

Gulls, magpies, moonpies

Someone was asking a series of questions about the above. I prepared the answer below but I now cannot find out where the questions are. I have looked through the different lists and some of the archives, but still cannot find them.

The one I remember was someone writing about approaching gulls, how they think, and how they dislike magpies.

I prepaired a reply but cannot now find the question. Perhaps someone who knows where the question is could add the below reply. Thanks. The reply:

It sounds as if you would be interested in reading King Solomon's Ring (nonfiction) by Konrad Lorenz, and in particular the 1953 book The Herring Gull's World by Nikolaas Tinbergen. They are both about Ethology.

I live in a town on the coast where there are plenty of seagulls. They do get tamer than you suggest. Recently a large one was in a crowd of people, and only when I got to within about a foot of as I walked past did it decide to take off. I had to jump back to avoid being hit by its flapping wings.

I once saw another gull following a pigeon, perhaps 'thinking' that the pigeon would find some food. I wonder if the gulls have learnt how to behave in crowds by imitating pigeons.

Did the pigeon have food it its beak? Gulls often like to give chase and steal from other birds. It's quite funny to watch them going after the magpies - nine times out of ten, the magpie will easily outpace the gull and cause it to sheepishly and awkwardly flutter around for a few seconds wondering what to do next when it gets bored of the chase.

As for the gull that nearly hit you, I very much doubt that it would have allowed its precious wings to come into contact with you, unless it was deliberately trying to attack you (which *is* a possibility, if you startled it by approaching within arm's reach when it wasn't looking). Gulls are amongst the most masterful fliers of all birds and they have *amazingly* quick reflexes. I've seen them allow cars within a couple of feet of them (they actually seem to be less scared of cars than people around here) before taking off, performing a funny little mid-air twist and flip and pulling their wings milimetres clear of the car roof below. The older, experienced gulls are better at it than the juveniles, which you do occasionally see splattered on the road. --Kurt Shaped Box 22:21, 17 July 2006 (UTC)

The pigeon did not have food in its beak.

I should explain - I assume you are from the US - I live in an urban area next to the sea in England. In the UK we call it a town, but I think it is more than large enough to be called a city in American English (AE). It has a long High Street that is pedestrianised. During opening hours it is crowded with people walking around doing their shopping. Children and some other people often drop crisps (chips AE) and other snacks on the ground. Pigeons and to a lesser extent seagulls walk around on the ground searching for them. I believe they are reluctant to fly because of the energy this needs. When people get near they walk away very fast rather than take off. With pigeons they are so tame that sometimes you have to be careful not to step on them. Gulls usually walk away when you get to about two or three feet. The gull that took off must have done so because it was in a crowd of people and there was nowhere it could walk to. It had to take off vertically also. It was probably a particularly tame one. The tameness presumembly varies from gull to gull - most of the gulls stay in the air and do not come so near people. I'm sure that gull was not trying to attack me, but was (anthropomorphising) just getting too nervous about being in a crowd of people.

I do not think it is so unusual that the gull was following the pigeon, as in my experience gulls are alerted to food on a birdtable by the behaviour of other birds.

Both the gulls were large - about the size of chickens - I believe there are several species of gull. I have never seen them near cars. I've never seen any gull-magpie interaction as I've never seen a magpie around here, and I expect that the bird having that name in the UK or US are actually different species.

I believe even non-monkey mammals or birds have their own culture that varies from place to place, so the birds behave differently here and where you are. An example would be Blue tits learning to steal cream from old-fashioned milk bottles.

It is a matter for debate if pigeons or gulls are the best flyers.

Is it possible to think without using words?

Animals do not have language, yet monkeys at least can do some kind of primitive thinking.

Is it possible to think and reason without using words? (Are there any humans who no longer or have never used words to think due to brain damage etc?)

If no words are used, then how is this thinking encoded into the brain?

And how are words encoded into the neurons of the brain?

And, for that matter, how is conciousness represented at the neuronal level?

I have pondered this myself. It raises the same question as "Well, how do deaf people think without using words". They would probably think using their equivilant to speech, i.e. sign language etc.

I assume you mean stone deaf, a total inability to hear anything, which is rare. Most "deaf" people, even those categorised as "profoundly deaf", can still hear sounds, although in extreme cases it might not be comprehensible as words. In any case, deaf does not mean having no capacity to understand words. Deaf does not mean blind. Deaf people can still read and write; many use sign language, which depends on linguistic comprehension; and they can all think. JackofOz 20:11, 17 July 2006 (UTC)

In Charles Dickens non-fiction book American Notes about a tour around the US, he describes going to a place were a mute-deaf-blind child was cared for and had been taught sign language, and he says he was told that she made signings while asleep and presumably dreaming.

As have I. Thought is such a subjective thing. I don't know if it's possible to answer this question without having first experienced someone/something else's thoughts at first hand, which mainstream science would claim is an impossability. It's kind of like looking at a sleeping animal and wondering what it dreams about... --Kurt Shaped Box 20:28, 17 July 2006 (UTC)

(Edit conflict) See thought. Although symbolic communication (language) is sometimes considered key to the ability to think, I think (heh) scientists and philosophers have yet to reach a consensus as to whether language is necessary for thought. As for how words are encoded into neurons, everything that happens in the brain exists as a pattern of connections between neurons -- not properties of neurons themselves. See also neuroscience and neuron. And as for how consciousness is represented in the brain -- if you figure out the answer, please publish it in a journal for the rest of us, because I don't believe anybody really knows the answer. --Ginkgo100 ^{talk · contribs · e@} 20:32, 17 July 2006 (UTC)

Unfortunately, the answer to several of your questions is "No one knows." Our knowledge of the exact ways in which the brain works is still fairly primitive. Browsing the relevant articles might help you.

As for thinking without words, sure it's possible. I think in images all the time, when thinking of paintings or more often when thinking about certain sorts of math - when I was learning about manifolds for instance. I don't know if everyone does it, though. --George 20:40, 17 July 2006 (UTC)

Authors such as Temple Grandin have written on thinking in images rather than words. Grandin is autistic and says she thinks only in images, never in words; she also suggests in her book Animals in Translation that animals probably think in images as well. As for me, I find it difficult to think in images just as some people find it easy. --Ginkgo100 ^{talk · contribs · e@} 04:02, 18 July 2006 (UTC)

The brain is a stubbornly complex beast and most of the concepts we use in day-to-day language do not translate directly and easily to the neuronal level. But to answer your question about words, to the best of my knowledge, we have to consider what you mean by words. Spoken words are a complex auditory pattern and so the sound of words would be represented in higher-level auditory cortex. Written words, likewise, would be represented in higher-level visual cortex. The act of speaking a word would be encoded in motor cortex and probably the basal ganglia. In [association cortex]] these various representations are likely sort of unified into a single representation of the word itself (though that representation at all levels would be distributed across the firing patterns and synapses of many neurons). The meaning of words gets a bit more complicated. Words whose meanings are grounded directly in sensation (the animal dog, a high pitched sound, the scent of a rose, the taste of saltiness, the feeling of roughness or coldness, etc) likely have the representation of the words associated with the corresponding neuronal-level representation of the sensory aspects they refer to. The meanings of many action verbs, on the other hand, are likely stored in higher-level motor cortex (to hammer, to bite, to wave), reflecting the memory of performing the action referred to by the verb. Cognition (thinking) is much trickier and less well understood, so if I may be a little more speculative: one neural network model I've created deals with backward planning (i.e. identifying a goal and determining the actions needed to take your present state to the goal state). In this model, representations of actions became associated over time with the effects that consistently followed taking those actions and when a particular effect was desired, it would activate the appropriate action (i.e. if you pick something up a number of times you'll learn that the effect of picking something up is that it ends up in your hand, so if you desire something to end up in your hand, you would select the actions that lead to picking it up). The moral of that is that some forms of "thinking" are basically goal-directed behavior operating on an internal model of an environment, instead of taking real actions on the actual environment. That would suggest that one can think without using words, as words are just certain sensory representations attached to other representations, but using words allows greater generalization and power, I expect. Hope that helps instead of confusing... Digfarenough 20:55, 17 July 2006 (UTC)

I don't understand the complexity you put into the answers/question. Of course you can think without words. If you put your hand over a stove you know to move it, because you can feel the heat. After you move your hand away you think "hot." If you smell cow manure, or mold as I just smelled about 3 seconds ago, you can think "bad smelling" without having to think the words "bad smelling." — The Mac Davis] ⌇☢ ญƛ. 21:25, 17 July 2006 (UTC)

I don't think those are examples of thought, they seem more like examples of sensation (possibly coupled with a reflex in the first example and valence associations in the second example). Digfarenough 21:54, 17 July 2006 (UTC)

People can think without using words. Not complexly, for example when you see a car rushing at you, you deduce, without use of words that you want to get out of the way, and when hungry, and food is presented to you, you eat it. Philc _T^E_C^I 23:07, 17 July 2006 (UTC)

I think this is a pretty simple question to answer, as other people have said, of course you can think without words, sometimes I think in images, other times mathamatical operators, it's the type of person who is attracted to an online reference desk--172.133.170.19 23:22, 17 July 2006 (UTC)

There have been some interesting experiments done with non-human apes to explore this question. There are certain behavioral tasks that chimps normally find very difficult to accomplish. However, if you allow a chimp to learn the basics of human language, some of those "difficult" behavioral tasks then become much easier. It is hard to know what thoughts take place in these chimps, but it is as if human language increases certain cognitive capacities and allows new, more complex patterns of thought. A book called, "Kanzi: The Ape at the Brink of the Human Mind" by Savage-Rumbaugh and Lewin provides a good introduction to this topic. --JWSchmidt 02:04, 18 July 2006 (UTC)

Some dreams might be examples of thinking using images only. Typically, you're not aware that you're dreaming, and it's as if whatever is going on is happening in "the real world". You're not making any decisions with your conscious mind, so you're not "thinking" in the usual sense, you're just in the scenario (or observing a scenario). Some dreams do involve spoken/written words, but these tend to be symbolic in nature. Remembered dream-state conversations tend to sound illogical in the waking state, but I guess they're still using words, aren't they. JackofOz 04:33, 18 July 2006 (UTC)

What is thinking and what is language? If you have two ill-defined terms a comparison gets very hard. You could define the two to mean the same thing. Thinking in math is thinking in language because math is a language. The same might be said of images.

Thinking isn't encoded in the brain. What the brain does is think. It's like asking how sound is encoded in music. I wouldn't dare try to say how language is encoded in the brain. Digfarenough has given a good indication, though. It's a very complex interaction between different parts of the brain. It's like the question where your grandma is encoded in the brain and if that part were to die, would you then forget about her. The memory of her is probably distributed throughout the brain.

And consciousness is the vaguest term of them all.

I think a central problem here is the notion that thought is some evolutionary step that sets us apart from the other animals. It isn't. There is just an increase in complexity. It's like asking at what age one is old. There is no defining line, and in as far as there is one, it shifts according to how old people get in a certain culture. To some future offsping of ours it might seem we weren't capable of thought. Well, some primitive precursor to it maybe. DirkvdM 07:14, 18 July 2006 (UTC)

• We don't really know what thought is, or what the language faculty is, or how they might be connected, but personally I would call language symbols related by grammatical structure, and I think it would be reasonable to think in symbols other than words, though I doubt if it could be done entirely without words. Peter Grey 20:48, 19 July 2006 (UTC)

• There is some speculation that language influences thought. See Sapir-Whorf hypothesis. --WhiteDragon 15:33, 28 July 2006 (UTC)

Ring flashes for Canon EOS DSLRs.

I'm looking into getting a ring flash for my Canon EOS Digital Rebel. I was looking at getting a Phoenix RL-59C (they have them on eBay and such for seventy or eighty bucks), since they're much cheaper than the name-brand Canon ringflashes, but are superior to getting some random used ringflash because they're supposedly designed for the EOS system (the five-pin hotshoe, and all.)

I want whatever flash I get to support quenching itself to avoid overexposure---that is, if the flash is too close to the subject, it should turn itself off when either the flash or the camera has absorbed the requisite amount of light. I've heard of this being done with an "auto thyristor" on the flash; is this what the E-TTL system performs? If so, does the Phoneix RL-59C support E-TTL? Does it have an auto thyristor? In short, will I be stuck manually guessing at the proper exposure through trial-and-error?

Reading about the Canon EOS flash system, I still don't quite know whether I'm entirely off-base or not; my knowledge of and experience with flash systems is very small. I haven't been able to find reviews of this item that aren't product pages containing the word "review", but only in the context of "no reviews yet---add one!". grendel|khan 20:12, 17 July 2006 (UTC)

The problem is that in theory every flash that supports TTL metering should work, but canon has implemented some kind of non standarts in its cameras so maybe only canon flashes will work. Except the flashes are built specially for canon compatibility like some Metz flashes.

But TTL metering is what I need, then? grendel|khan 14:04, 23 July 2006 (UTC)

Simple web-page that creates a URL

Hi,

I'd like to create a simple page which has a textbox input, and which then sends the user to a URL based on the text, without using PHP (which my host doesn't allow).

E.g., if the user entered "test", and clicked "GO", they could be taken to www.blahblah.com/blah/test.html.

I'm not a programmer, but I do understand the basics of javascript and the like.

Any help would be greatly appreciated! 199 (talk) 20:52, 17 July 2006 (UTC)

There is a script available on the web called the Gatekeeper script that will do this for you. Theresa Knott | Taste the Korn 21:02, 17 July 2006 (UTC)

Assuming that if you don't have PHP, you don't have ANY server-side scripting, you must use JavaScript. This can be done. Make the form as normal, but add onsubmit='javascript:page_forward();return false;' to it. Now, instead of submitting the form, it will call the javascript function "page_forward". Next, you need an ID on your text field. Add id='user_text' to the text field. Finally, in javascript, you can use document.src='http://mypage.com/somdir/'+document.getElementById('user_text').value; to set the source of the current document to the new URL. If you don't know enough HTML or JavaScript to do that, just ask. --Kainaw ^(talk) 21:13, 17 July 2006 (UTC)

Ok, thanks. I'll mess around, and ask again if I can't get it to work. Thanks! 199 (talk) 21:16, 17 July 2006 (UTC)

iontophoresis

how big a particle can be delivered with iontophoresis

Iontophoresis, by itself, isn't therapeutically useful with compounds larger than about 1000 Da; the tough outer layer of the skin (the stratum corneum) is a very effective barrier. Some improvement (up to about 10 kDa) can be achieved by using higher energy electrical pulses to open short-lived channels through the skin: electroporation. TenOfAllTrades(talk) 21:20, 17 July 2006 (UTC)

Andreas Effect, droplet behavior

As a student I was told that a water droplet, after running along a slope, could actually run back and upwards a bit on the underside of an edge, before falling. Some teacher (I think) told me that is was called the "Andreas effect". Althought I could imagine the physics behind the phenomenon, I have not found it to be called by that name. Is there such an expression? Would be very happy to hear your opinion folks. --Tls99lli 21:20, 17 July 2006 (UTC)

I assume the lack of responses is because no one has heard of any effect by that name - I haven't. If you'd like, surface tension is a nice article. Or, another effect in the same genre of physical phenomena with a funny name is the cheerios effect. --Bmk 17:30, 18 July 2006 (UTC)

Electronic beeps & hearing loss

A few years ago, I'd heard from a couple of people that the electronic noises generated by watches, microwaves, children's toys, etc. were damaging to one's hearing. Is there any truth to this, or is it simply a neo wives' tale?

--64.26.68.82

Depends on which neo-wife you're talking to. :--) JackofOz 23:03, 17 July 2006 (UTC)

Electronic noises? Not sure what you mean by that. Maybe high-pitched pure sine waves? A car alarm going off next to you could cause ear damage I imagine (there must have been a lawsuit in the US). But soft sounds like from a watch sounds very unlikely. DirkvdM 07:21, 18 July 2006 (UTC)

ct machines

What is the technical name for the donut shape in the machine? If your diagnosis was phnemonia would you do a cta? Do ct machines look at structure or function?

Do you mean pneumonia? JackofOz 23:02, 17 July 2006 (UTC)

Torus? Rangek 00:29, 18 July 2006 (UTC)

Does Computed tomography help?

Oven Cleaner on Rims?

Can I use the oven cleaner sprays that foam up on my car rims to clean them? The ones that you spray and leave on for a few minutes and then wash off. Will it damage them? Thanks

Depends. If the rims are enameled steel like an oven, or bare steel like the racks, it might work -- try putting a little bit of cleaner on a non-visible, non-structural spot and see what happens. If they're painted steel or contain plastic components, I wouldn't try it. --Serie 22:10, 17 July 2006 (UTC)

How does smoking pot affect bodybuilding?

How does smoking pot affect bodybuilding?

It makes it more fun. :-P Philc _T^E_C^I 23:05, 17 July 2006 (UTC)

Two things spring to mind: 1) Any type of smoking affects blood vessels, constricting them and lessening blood flow. Since body building is about building muscle mass, smoking would be an inhibitor, albeit a small one in the case of pot (unless you smoked a lot); and 2) Cannabis has a mellowing effect on mood, which may decrease drive. Neither is particularly serious, IMO, although personally if I were ever to indulge in cannabis (I never have and it's not in the plan), I'd probably choose to eat hash cookies rather than smoking weed.--Anchoress 23:08, 17 July 2006 (UTC)

Isn't the constricting of blood vessels caused by nicotine? Weed doesn't have that afaik. DirkvdM 07:23, 18 July 2006 (UTC)

Mmm, I didn't think so, but maybe.--Anchoress 22:24, 18 July 2006 (UTC)

Most spliffs are rolled with tobacco though. Philc _T^E_C^I 12:02, 18 July 2006 (UTC)

Um, I imagine that probably depends on local custom. (That's not common in any of the places I have seen pot smoked.) --Fastfission 15:56, 18 July 2006 (UTC)

Really? curious, I thought when taken 'neat' or whatever the appropriate word in this context, that it has similar effects to when you take spirits neat, a hard hitting effect, that wears off after not to long. Obviously when taken through the pipe its on its own, but I've never seen that as the preference in a spliff. Ohwell, were probably just in different cultures as far as that goes. Obviously I am reffering to leaf form, not the resin or whatever. Philc _T^E_C^I 19:52, 18 July 2006 (UTC)

I can't tell if the question is about the long-term effects of smoking pot and body building (but not at the same time), or whether or not you can body build while high on pot. If the latter, I would recommend against it — marijuana cuts down on coordination and often your good sense, two things which it is good to have while lifting heavy weights. --Fastfission 15:56, 18 July 2006 (UTC)

I also recommend against it. Bodybuilding makes you muscles look stupid. DirkvdM 19:19, 18 July 2006 (UTC)

Suicide

Why is it that only humans have the choice to kill them selves?

They don't. A bee can sting you, but if it's prickly thing gets stuck in your skin instead of his, it dies. And I'm sure there's a lot more examples. And while people technically have that choices, it's a bad idea in 99.999999 % of the cases. - Mgm|^(talk) 23:28, 17 July 2006 (UTC)

And technically illegal in lots of places. (Assuming you survive, that is. Funny, I can't think of any other crime where it's illegal to attempt and fail, but not illegal to succeed). JackofOz 23:44, 17 July 2006 (UTC)

Overthrowing the government? David Sneek 18:20, 18 July 2006 (UTC)

It's only illegal so they can take you into custody should you attempt it. Public suicides are very disruptive and expensive. I only support suicide in a private home with some mechanism to alert the authorities once you're dead. It really reduces the cost to the tax payers (body transportation, minimal investigation). --mboverload@ 23:48, 17 July 2006 (UTC)

I hope you at least have a few more criteria than that? Even if you believe suicide can be a reasonable choice for a person to make (for example because of terminal illness), the significance of that choice undoubtedly has more to do with the individual and those around them than it does with the tax payer burden it might create. Dragons flight 00:03, 18 July 2006 (UTC)

I once saw a documentary on TV about chickens. There was one scene where some kind of hawk was circling and all the chickens were running away in panic to hide. One mother hen hid in some bushes but then saw that her chicks were still milling around in the grass and the hawk was getting ready to attack. She ran out and beckoned her offspring beneath her, then sat down over them and allowed the hawk to carry her off. I dunno, does 'choosing to give up one's own life to save another' count as 'suicide'? --Kurt Shaped Box 23:42, 17 July 2006 (UTC)

I'm not sure how much of it is choice, and how much dementia, but whales certainly do kill themselves by beaching. Dragons flight 23:44, 17 July 2006 (UTC)

If you shielded your children from a bomb blast, knowing that in all probability they would still be injured but survive, but you would almost certainly die, I would not call that suicide. You weren't doing it in order to die, but in spite of the possibility of dying. Since there was higher purpose, I would never call that suicide. JackofOz 23:49, 17 July 2006 (UTC)

Yeah, fair point. Likewise, a soldier throwing himself on top of a grenade to save his comrades. --Kurt Shaped Box 23:53, 17 July 2006 (UTC)

Orcas commit suicide, in the true sense, not just giving their lives for their offspring. It's well-documented that Orcas who have experienced the loss of a loved one will sometimes beach themselves, and if the tide washes them out or they are rescued, they'll keep doing it over and over until they die.--Anchoress 00:02, 18 July 2006 (UTC)

Please find a refernce for that and add it to Suicide! Currently the article states that no animals commit suicide, citing The Straight Dope. Melchoir 00:56, 18 July 2006 (UTC)

Someone said on here a while ago that seagull hens will fight to the death to protect their babies. There was something in the paper a couple of weeks ago about a clutch of being chicks being raised by someone at home after their mother was mortally wounded in a fight with a buzzard (which she managed to kill before dying shortly after).

I don't see how that has anything to do with suicide. She died in a battle, that's not suicide. --mboverload@ 00:11, 18 July 2006 (UTC)

She could of just flown away, cut her losses and figured that she could always lay more eggs. But she didn't.

...So going to war is suicide? They could have just ran away, too. Would you run away if someone was going to stab your baby? You would try and defend it. It may have been suicidal to think she could win, but it wasn't suicide. --mboverload@ 00:28, 18 July 2006 (UTC)

(edit conflict) Her intention was to save her chicks, not to die, as JackofOz said, that is doing something in spite of dieing, not with the intention to die, the seagull would have probably prefereed if it if she had killed the buzzard and survived. Philc _T^E_C^I 00:29, 18 July 2006 (UTC)

That certainly contradicts what someone said the other week. It was claimed that animals do not take unnescessay risks in defending their young, as it would be counterproductive in terms of ensuring the survival of their bloodline to die in defense of them, when they could easily have some more at a later date... --Kurt Shaped Box 00:46, 18 July 2006 (UTC)

Lionesses certainly don't, if a new male takes over the pride, it kills all of the young, and the females dont do anything to prevent it. Philc _T^E_C^I 12:02, 18 July 2006 (UTC)

First off, the state of California has no law against committing or attempting to commit suicide (from taking law courses there). Also, let's refer back to the original question: Why is it that only humans have the choice to kill them selves? I think what the author was trying to ask is why are we the only species capable of it. And that has to do with our intelligence. The question could also be is there such thing as an animal capable of wanting to commit suicide and then doing it. If there were any animals capable of that, they would most likely have to be primates, such as apes and chimpanees. NealIRC 18 July 2006.

Have you ever considered that a significant proportion of all those deer that get run over by cars after being supposedly 'transfixed by the headlights' actually wanted to die? ;) --Kurt Shaped Box 01:47, 18 July 2006 (UTC)

The state of California is but one jurisdiction among many in the world. Attempted suicide is certainly illegal in some places. Aren't there some animals that, when they get sick, wander off from the herd and go where they can't get any food or water and just wait to die? Whereas if they stayed with the herd, they'd be able to go on for some time longer. This might be called hastening death due to disease, but under some definitions of suicide it might also be called suicide. I think it comes down to a question of intention, and it's very difficult to know what the intention of an animal is in circumstances like these. Humans sometimes suicide while in a state of severe depression or psychosis, or while experiencing strong feelings of pointlessness, worthlessness or futility, but I'm not aware that animals are known to have such feelings. JackofOz 02:55, 18 July 2006 (UTC)

I once heard that there are certain Birds (I cant remember theyr name) that once they are together with a partner and then the partner dies, the remaining bird will commit suicide. Also lemmings tend to commit suicide if I remember correctly. helohe (talk) 23:59, 20 July 2006 (UTC)

I know that some pet birds can pine to death if their owner/companion bird dies. --Kurt Shaped Box 00:17, 21 July 2006 (UTC)

I've heard that certain parrots pine for the fjords, but they're only the dead ones that are nailed to their perches.  :--) JackofOz 02:54, 25 July 2006 (UTC)

The lemmings thing is a myth according to lemmings. DMacks 01:13, 21 July 2006 (UTC)