Wikipedia:Reference desk/Archives/Science/2006 June 9

One server, multiple domain names
Let's say I sign up for a web hosting service, and create two websites in separate directories (say, /~myusername/public_html/greathats/ and /~myusername/public_html/shoes4sale/). Let's say I then register two domain names (greathats.com and shoes4sale.com). What do I need in order to make it so that greathats.com and shoes4sale.com associate themselves with those particular directories in a nonobvious way (that is, the site will not make it clear that there are any higher levels to it than those particular directories they are hosted in)? Put another way (I apologize for my inarticulateness with this -- if I knew what to call it, I'm sure I could figure it out myself!), I don't want it to be clear that either of the URLs are at all connected in the same server in any obvious fashion (someone could run a WHOIS of course and find out, but I don't care about that -- I just want them to superficially look like two different websites, but hosted on the same server).

What should I look for in a web host if I plan to have this sort of arrangement? I've seen some which say things like they offer "5 primary and secondary DNS" services, but I don't really know what that means (though I suspect it might be relevant) and "4 domain forwarding" and "virtual hosting" (but I don't want virtual hosting of the sort where you get subdomains, like bowlers.greathats.com; the two URLs will look nothing like each other). If I got a plan that had both of those, would it allow me to do what I wanted? I'm confused. :-( Can someone make this easy for me? Many thanks. --Fastfission 00:26, 9 June 2006 (UTC)


 * I am a Linux/Unix and Apache person. I don't do Windows.  In Apache, you just edit your config file (most likely httpd.conf) and tell it which directory each domain name goes to.  Then, point all the domain names to your server.  You can also point each domain to a different set of logs (and set different permissions for each domain).  As for what to look for, it depends on what you need.  If you are going to hosting a lot of sites and you want a highly dependable service, then spend the money and lease a server.  I spend $300/month on my network services - which makes some webhosting people cringe.  However, I bring in just over $2,000/month.  I could make a lot more, but I don't want the extra work. --Kainaw (talk) 00:53, 9 June 2006 (UTC)


 * (edit conflict) The service you are looking for is usually described as "Add-on domains" or "Host X domains in 1". It is accomplished at the webhost level and is becoming fairly common, but not universal.  I operate websites with two different webhosts (one is professional level, one is more basic).  The more basic host that I use is Bluehost and they offer the service you are looking for and are likely to meet your other needs unless your planned sites will be quite busy or need unusual features (such as direct control of mail services).  Dragons flight 00:56, 9 June 2006 (UTC)


 * That Bluehost is so cheap it is scary. How can they afford to give you all of the things they list at only $7/mo.? --Fastfission 02:43, 9 June 2006 (UTC)


 * The secret is that $7/mo is with a 2 year contract. It's $8/month for 1 year, and their pricing structure is such that it is basically noncompetitive to consider periods shorter than that.  See also my talk page reply. Dragons flight 03:27, 9 June 2006 (UTC)

Plumbbob
Not in terms of Operation Plumbbob, what is a plumbbob anyway?? —  The   Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 03:54, 9 June 2006 (UTC)
 * You mean this sort of a "plumbbob"? --inksT 04:10, 9 June 2006 (UTC)


 * Better question: According to the operation plumbbob article, there is an urban legend of a manhole cover being propelled upward by an underground blast and exceeding Escape Velocity thus leaving the earth's orbit and eventually the solar system.  This seems quite far-fetched... Anyone care to postulate if it's physically possible?
 * There is some discussion of it on Sublette's Plumbbob page and specifically this page. If you scroll down to the Pascal-B shot info, Sublette has a number of equations and other mumbo jumbo describing why it didn't happen, but doesn't say anything definitive about whether it could feasibly happen if you wanted it to. --Fastfission 17:16, 9 June 2006 (UTC)


 * This is discussed on a page that links out from Operation Plumbbob. The manhole cover probably would have been disassociated due to heat of ram pressure from flying through the atmosphere. — [[Image:Flag_of_the_United_States.svg|17px]]  The   Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 00:59, 10 June 2006 (UTC)

Possible damage from anal vibrator
I've had moderate pain in my lower abdomen after moving around some while using an anal vibrator for the first time. The pain seems to have continued for 12 hours or so. It feels a lot like a muscle pain, and seems to be in the front, but I was nervous, because I've heard stories about people suffering from internal bleeding and things. As long as I'm not in severe pain, and I don't have any blood in the stool, am I all right to wait and see what happens? -- LazerTruck666 04:23, 9 June 2006 (UTC)
 * We're not qualified to answer that. Your best option is to see a doctor. You don't want to find out you waited to long when it's already too late. - 131.211.210.10 07:43, 9 June 2006 (UTC)
 * Your muscles and walls of the rectum and/or sigmoid colon (you'll have to scroll down) may or may not be ripped/damaged. How long was your vibrator? Be gentle! — [[Image:Flag_of_the_United_States.svg|17px]]  The   Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 12:16, 9 June 2006 (UTC)


 * i regulary use anal vibrators and (less regularly) have anal sex and have never had a long lasting pain -is it possible thats its just a coincidence and in fact has been caused by somethine else? 195.93.21.8 13:24, 9 June 2006 (UTC)


 * Of course it's possible. And it's possible it's not. That's why he should see a doctor, because neither he nor we have the information or expertise to know which is actually the case. Black Carrot 23:02, 9 June 2006 (UTC)

Special relativity
I heard my teacher saying to another student that "...therefore empty space loses its meaning in special relativity" Why does empty space loses its meaning? Thanks!


 * Because special relativity basically boils down to "there is no absolute space or absolute time, only space and time relative to other frames of reference" and in empty space, all frames of reference are indistinguishable. Confusing Manifestation 12:48, 9 June 2006 (UTC)


 * ConMan's explanation for what your teacher may have meant is very plausible. I'd like to add that this statement is probably far too strong: just because there is no such thing as an absolute reference frame does not imply that there is no such thing as space or that it cannot be empty.  Indeed, there is such a thing as empty space in relativity. -lethe talk [ +] 15:03, 9 June 2006 (UTC)


 * ConMan is full of beans. There is spacetime objectively.  Certain properties are subjective, but you could talk about a region of empty space over a time interval objectively.  (Cj67 01:38, 11 June 2006 (UTC))


 * Special relativity plus quantum mechanics imples that "empty" space is actually teeming with virtual particles--see vacuum energy. No idea if that's what he meant or not, but it's true at least. -- SCZenz 10:45, 10 June 2006 (UTC)

gp120/41/160 stability
If HIV has no "proof-reading" mechanisms, hence the immense genetic variability and recombinant effects producing many subtypes, how come the genes for gp120, gp41, and gp 160 are so stable, hence no glycoprotein mutations? HIV doesn't have half a proof-reading mechanism, just for the envelope. What's going on? -- Eh-Steve 09:40, 9 June 2006 (UTC)
 * So Steve, read my reply to your questions on my talk page? — [[Image:Flag_of_the_United_States.svg|17px]]  The   Mac Davis ] ⌇☢ &#xE0D;&#x19B;. 12:09, 9 June 2006 (UTC)

This isn't the place, but yeah... --Eh-Steve 21:32, 9 June 2006 (UTC)


 * Usually where proteins show little change over time, it is because their functions are extremely sensitive to mutation. gp120 and gp41 are the proteins that allow HIV to recognize, bind, and insert itself into cells; mutations to these proteins are likely to produce a virus that cannot bind to T-cells and therefore cannot infect them and reproduce.
 * So there are probably lots of mutated variants of gp160 being cranked out&mdash;however, they are unable to infect T-cells and so they don't get reproduced. TenOfAllTrades(talk) 14:30, 9 June 2006 (UTC)

Microkinesitherapy
Hello -- I would like to find out more about microkinesitherapy - a therapeutic treatment used in France to unblock energy in one's body that was blocked by past trauma. Thank you.

Wikipedia doesn't seem to have an article on this, but try Microkinesitherapy. Conscious 13:24, 9 June 2006 (UTC)

sea gull poo
hi, yesterday, i was sitting in my garden with my (brand new) red linen trousers (h&m's finest) when a sea gull deficated on me. i washed them but they havent come out AT ALL - its as though i havent washed then at all. firstly, why is sea gull poo so tough? and secondly, does anyone know how to get it out? thanks! 195.93.21.8 13:27, 9 June 2006 (UTC)


 * She gulps sea gulls on the sea. Whore! --DLL 18:03, 9 June 2006 (UTC)

I suggest you immediately remove any such clothes, scrape off as much poo as possible, soak the area with stain remover, then wash it. It sounds like it might be too late for many of these steps, so you may not have much luck removing the stain. How about making them into a nice pair of summer cut-offs ? :-) StuRat 21:05, 9 June 2006 (UTC)


 * If all else fails, take them to a drycleaner. JackofOz 03:50, 10 June 2006 (UTC)
 * Better still, make the sea gull take them to the cleaners for you! freshofftheufo  ΓΛĿЌ  06:03, 12 June 2006 (UTC)

insect hair
where can you get more info about insect hair? (or spider hair). it must be a lot smaller than mammal hair. Is it made from the same protien? is there a wikipedia article about it? Jonathan talk 15:40, 9 June 2006 (UTC)
 * From Hair, it seems these are actually "insect bristles", which you will notice is a redlink. I found a rather technical Pubmed article on their development here. --Ginkgo100 talk · contribs 16:30, 9 June 2006 (UTC)
 * Yes, I see the hair article does not clearly state the fact: hair is found only on mammals, and all mammals have hair. The hairlike protruberances on other animals are different in structure --Seejyb 22:41, 9 June 2006 (UTC)
 * This is simply not true. Hair is found on other animals (such as insects) and not all mammals have hair (e.g. dolphins and whales are completely hairless). Hair is made of keratin, but I can't confirm how different it is on insects. (that pubmed article may help). —Pengo 15:16, 11 June 2006 (UTC)
 * Pengo, all mammals do have hair; it is one of their defining features. Dolphins and whales and elephants are only hairless in the sense that a bald human is hairless; they still have hair, just streamlined. Skittle 21:29, 11 June 2006 (UTC)
 * Mammal hair is, however, unique, growing as it does from specialized hair follicles. --Ginkgo100 talk · contribs 19:06, 11 June 2006 (UTC)


 * What the hell is streamlined whale hair?? If a mammal loses its hair it it still a mammal. It is not the hair that makes a mammal a mammal, but the linage it is decended from. Hair folicles may be a defining characteristic of the earliest mammals, but if this character is lost in a later mammal species (secondary loss) then it's still a mammal.—Pengo 14:18, 14 June 2006 (UTC)


 * Birds also have hair. Look closely at their eyes - they have eyelashes. --84.64.94.121 21:49, 11 June 2006 (UTC)

eyeglass while reading a computer
Is there any eyeglasses out there which could be used while viewing a computer screen? My doctor said I have no distant vision or near vision. He also said there are no eyeglasses such as to be used while reading a computer. Do you know any eyeglasses such? Please tell me.


 * You should be able to wear the same glasses to look at a computer screen as you use to look at a piece of paper the same distance away. It doesn't matter what you're looking at, only how far away it is. What does "no distant vision or near vision" mean? You're blind? You have astigmatism? —Keenan Pepper 17:44, 9 June 2006 (UTC)
 * Perhaps you mean nearsighted or farsighted? Regardless, as Keenan pointed out there is nothing special about a computer screen that eyeglasses can help.  What is special is that when you work at a computer for long periods, your eyes naturally 'trance' (not sure if there is a technical term for this) and the rate of blinking slows down greatly.  This leads to dry eyes, and irritation.  If you are suffering from eye fatigue and you have no other vision problems (and you're sitting far enough back from the screen), then that's probably it.
 * I think you should either trust what your doctor says or go to another doctor or optometrist. They should be able to give you better and more personal advice than us here.  If you can see the display perfectly at first but you have problems after watching it for a longer time (such as tired or irritated or dry eyes, blurry vision etc) there might be other fixes than glasses.  For example, you may need to take breaks every hour; fiddle with the brightness and contrast controls of the monitor; make it sure that no direct sunlight falls on the monitor but the computer is not in a very dark environment either; there are no annoying reflections on the monitor (the most common ones being sun rays reflected from an open window or the reflections of a lamp); make sure you're not watching the monitor from too close; or use approperiate eye drops.  &#x2013; b_jonas 11:21, 11 June 2006 (UTC)


 * I suggest you see an Optometrist and perhaps ask about progressive lenses. - Cybergoth 15:16, 12 June 2006 (UTC)

Speculative CSS and/or Javascript question
You know how if you click on the little "hand" tool in Adobe Reader, you can click-and-drag to scroll around the page image? Is there any way to easily implement a similar function on a webpage — so that if the user clicks and drags, the page will scroll within the browser window? It's not worth tearing one's hair out over, but for some little thing I am doing it would be a neat effect. It seemed like the sort of thing that wouldbe implemented with some sort of CSS tagging or Javascript using a "onmousedown" attribute or something like that. Is such a thing easily implementable? I suspect not, but thought I would ask. --Fastfission 16:38, 9 June 2006 (UTC)


 * Nevermind -- I was able to adapt this script to do what I wanted to. Pretty neat stuff! --Fastfission 17:04, 9 June 2006 (UTC)

the largest tram network
Which city has the largest tram network on Earth? I think Vienna is in top 5, but I am not quite sure... Thank you!

I have no idea, but i do know that the Amsterdam tram is quite extensive, with dozens of lines. SanderJK 20:28, 9 June 2006 (UTC)


 * The article on trams asserts Saint Petersburg's tramway network still is the largest in the world. You may want to do some googling to verify that. Weregerbil 20:49, 9 June 2006 (UTC)

Low TSH-levels and hyperthyroidism
The TSH article says this: "Higher than normal levels of TSH may indicate congenital hypothyroidism (cretinism), hypothyroidism or thyroid hormone resistance. Lower than normal (suppressed) levels of TSH may indicate hyperthyroidism." Is this true? I was thinking since hyperthyroidism is overactivity of the thyroid doesn't that mean TSH levels should be elevated? And vice versa. Jack Daw 20:35, 9 June 2006 (UTC)


 * It's counterintuitive. The high levels of TSH are because the thyroid won't respond to normal levels, so the anterior pituitary gland, sensing a lack of T3 and T4, keeps making TSH. When too much T3 and T4 are made, the pituitary gland is inhibited, so no more TSH is made, so levels are low. The malfunction is all due to the thyroid. Hope that helped. --Eh-Steve 21:31, 9 June 2006 (UTC)


 * Yes it did, thank you very much. Jack Daw 21:40, 9 June 2006 (UTC)


 * An easy way to remember this is to think of it as a negative feedback system. - Cybergoth 21:53, 9 June 2006 (UTC)


 * Shouldn't the article also be stating the obvious that low TSH can be due to hypopituitarism and high TSH to an excess production by a pituitary tumor (adenoma)? --Seejyb 22:59, 9 June 2006 (UTC)
 * Yes, you could add that if it isn't there already. - Cybergoth 14:08, 11 June 2006 (UTC)


 * There is a further detail that is even more counterintuitive than the above: in hypopituitary hypothyroidism ("central" or "secondary" hypothyroidism) the TSH is often borderline high (typically 6-8) because of a complex dual feedback system at the hypothalamic level.alteripse 02:35, 13 June 2006 (UTC)