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April 19

What flowers are these?

the pink and white ones --78.148.106.196 (talk) 09:23, 19 April 2014 (UTC)

Could they be all white flowers which have been given red dye, at the stem ? StuRat (talk) 10:12, 19 April 2014 (UTC)

They are carnations, or Dianthus caryophyllus to give them their full name, and some of them look like that naturally. --TammyMoet (talk) 12:47, 19 April 2014 (UTC)

Yes, no dye used. They have been bred to look like this. (Red and white are natural colours for Dianthus, but this combination does not occur in the wild.) Dbfirs 06:40, 20 April 2014 (UTC)

Theme park rides

Are theme park rides designed by civil or mechanical engineers or both? Clover345 (talk) 09:50, 19 April 2014 (UTC)

That would be mostly mechanical engineering, but often some civil engineering (and several other disciplines) would be involved. If you read those articles they are fairly clear (though I was surprised to see a picture of the International Space Station in the lead of the civil engineering article).--Shantavira|^{feed me} 10:47, 19 April 2014 (UTC)

Really? I thought most of it would be structural and geotechnical engineering. I can understand the mechanical elements if it being mechanical engineering but what about the track structure, support structure, foundation, ride station etc. Clover345 (talk) 13:24, 19 April 2014 (UTC)

Why not perform a case-study? Let's take a look at a project orchestrated by Walt Disney Imagineering from two aspects: the portions of the project under the creative direction of the Disney group; and the portions of the project that are inevitably contracted to other companies.

Wikipedia has thorough articles on about every major theme park attraction: for example, the latest mouse ride.

You can also see what type of people Disney hires: the Disney Imagineering Professional Internships careers page has a lot of openings for (...you guessed it...) software, graphics design, business and marketing. There are some openings for the more hard-core engineering disciplines, but those are pretty rare. A recent humor-article on Cracked, 6 Things Nobody Tells You About Working at Disney World, focused on the in-park internships, and provides an interesting insight into the types of work a Disney corporate intern or employee can expect. Once in a while, you might even find something as technical as Animatronics Intern.

So, if Disney has decided to focus on the creative side, somebody else must be engineering and constructing the projects. Possibly the most famous cases are the Monorails at the Disney resorts. Famously, ALWEG engineered and built the first monorail in 1959; and in the 1960s they were replaced by MBB. Disney also operates a cruise line; but as the animation and film industry has little overlap with the operation of a large marine vessel, they subcontract the operation to BAE Systems. I specifically recall the Disney World Skyway at the Florida park; that item was built by Von Roll Holding, an industrial conglomerate that's mostly owned by Bombardier Inc.. Its construction and operational history is plagued by drama, and it has always inspired me to research the conglomerates who build my ski-lifts. (My favorite resort has a huge poster of the commando-looking engineers from Doppelmayr construction firm moving massive construction equipment over cliffs in the Sierra Nevada mountains - you can see some historic photos in their brochure series, Die Welt der Seilbahnen). The recurring theme you might see is that Disney subcontracts the heavy-lifting to major engineering and aerospace conglomerates - groups like BAE and Bechtel and Lockheed. In return, Disney Corporation helps out the defense industry reciprocally by camouflaging aerospace and defense factories so they look like theme parks from the air. But in all seriousness, if you're the sort of person who is attentive to detail, the next time you walk around a Disney-branded theme-park, you might start spotting the not-so-subtle corporate logos of a lot of other companies - particularly, the aerospace and defense supergiants - plastered on the sides of all the mechanical parts of the ride. Most kids are too busy paying attention to the cartoon characters to spot that stuff.

But the reality is, very few corporations have the expertise in the sorts of specialized engineering that a theme-park ride actually requires. Structurally, it requires moving around massive quantities of heavy material and equipment and setting up construction-facilities in remote swampland. This is the sort of thing that military logistics contractors and oil companies excel at: mobilizing the manpower and engineering to construct massive single-purpose projects; over-engineering complex-systems to provide simplicity, safety, and (best-effort)-idiot-proofing.

These corporations hire civil engineers, mechanical engineers, aerospace engineers, a wide variety of technicians and experts, and they directly hire (and subcontract) for a large volume of unskilled labor. If you want to work on such a project, you have a better chance applying to, say, Boeing or Schlumberger, than Disney; but you still have to be really talented and lucky and competitive to get assigned to a really cool theme-park project.

Meanwhile, Disney Corporation handles the branding and the marketing, and the "theming" of the park.

If you study major theme parks operated on behalf of other conglomerates, you will probably find the same trends.

Nimur (talk) 17:07, 19 April 2014 (UTC)

thanks for the detailed answer. Wouldn't most parks employ a small engineering team though, maybe within their project management group? Clover345 (talk) 17:41, 19 April 2014 (UTC)

I think most theme parks, even the ones owned by companies that do nothing but operate theme parks like Cedar Fair, don't design and build their own rides. Individual parks probably don't have enough new construction on a regular basis to justify a full-time engineering department to design them. But there are several companies that do specialize in theme park rides like Mondial, Bolliger & Mabillard, and Intamin.

As for the original question, I imagine it would depend on the type of ride. For something relatively simple like a conventional roller coaster or river rafting ride, I imagine it would probably be about equal between the mechanical and structural designs. But for more exotic rides like roller coasters launched with linear induction motors and things like this, the mechanical design is probably a little more involved. Mr.Z-man 17:42, 19 April 2014 (UTC)

I imagine that most modern theme park rides also involve a fair bit of electrical engineering and computer engineering for the power, automation, and safety features. shoy (reactions) 13:45, 21 April 2014 (UTC)

Innovationin engineering and design

Do you think all engineering disciplines have just as much scope for innovation as each other? Clover345 (talk) 16:35, 19 April 2014 (UTC)

I think it's reasonable to accept that as a starting position and instead put the onus on arguing that they don't. — Lomn 16:50, 19 April 2014 (UTC)

I don't think "innovation" is well-defined or easily-compared, either. It is nearly impossible to provide a total ordering amongst various innovations, so we can't say whether one accomplishment was more innovative than another.

In my experience, "innovative" people need to be generalists who have the ability to quickly become the best specialist on the team. That means you have to be able to become the best at every branch of engineering. Today's problem might be software; tomorrow, it might be glue that isn't sticky enough; and in two weeks, it might be a budget shortfall. Innovation is being able to come up with a new solution that is better than the existing solution, no matter what today's problem is. As my co-worker jokes - "we're software engineers, which is why we have so many oscilloscopes." Nimur (talk) 17:18, 19 April 2014 (UTC)

I would think that in some engineering fields, it's innovate or fail, like consumer electronics, while other engineering fields are far more conservative, like civil engineering, since a new bridge design which collapses because it wasn't completely understood will cause massive lawsuits. See Tacoma Narrows Bridge (1940).

Airplane design is a field where you might think innovation would be needed, but innovations in that field often cause crashes, due to unknown forces and processes, like supersonic flight (turbulence and sonic booms), rectangular windows (force concentration and metal fatigue), composite materials (delamination), and lithium batteries (flammability). Of course, some innovation is needed, but everything needs to be thoroughly tested before it goes into production there, so being conservative makes sense in aeronautics. An exception might be for unmanned vehicles, where accidents are less likely to cause deaths. StuRat (talk) 19:57, 19 April 2014 (UTC)

So would you say there's more innovation in engineering research than in engineering practice? And what about computer science? Is there innovation in that? Clover345 (talk) 16:26, 20 April 2014 (UTC)

Yes to both, although some areas, like consumer electronics, have a lot of innovation in practice, as well. Some areas of computer science are pretty well set, like database design, while others, like microchip design, are very innovative fields. StuRat (talk) 16:38, 20 April 2014 (UTC)

LED bulbs and inteference

Do LED lamps produce interference they way CFCs do? The article doesn't say anything about it, so I assume that they don't. Bubba73 ^{You talkin' to me?} 18:49, 19 April 2014 (UTC)

CFCs usually refer to an unrelated chemical. Are you sure you don't mean CFL, as in compact fluorescent lamp ? Nimur (talk) 19:20, 19 April 2014 (UTC)

Yes, I meant CFL. Bubba73 ^{You talkin' to me?} 20:02, 19 April 2014 (UTC)

So, who you got winning the Grey Cup this year? --Jayron32 22:28, 19 April 2014 (UTC)

Yes, LED bulbs can produce electromagnetic interference. The references I have found (here, here, and here, to start) suggest that this comes from the power circuits driving the LEDs, rather than from the LEDs themselves. There seems to be some wide variance in EMI produced by LED bulbs depending on the type and the manufacturer. - Eron^Talk 19:06, 19 April 2014 (UTC)

I'm getting terrible interference on my electric guitar. Most of the bulbs in our house are CFLs. Some are incandescent and some are LEDs. I'm replacing CFLs by LEDs as they go bad. Bubba73 ^{You talkin' to me?} 20:17, 19 April 2014 (UTC)

You may be getting that interference over the power line, not RF through the air. I experimented with a strat with single-coil pickups, walking around with it hooked up to an iPod via iRig (so there's no ground loop or other mains connection at all) and I can only get an audible buzz when the pickup is < 10cm from the CF bulb's base. With most light fittings, I can't get the pickups close enough to the source of noise for any buzz to be evident. Instead of the expensive business of changing out the bulbs, you might like to first look at eliminating ground loops and, if that's not enough, install a power conditioner in front of the amp. -- Finlay McWalterᚠTalk 10:41, 20 April 2014 (UTC)

I'd go with Finlay McWalte to look at ground loops first. But a word of warning. Some guitarists, having got rid of interference, have then dropped dead the moment they grab hold of the mic (which in my day had chromium plated metal grip and driven by a separate amplifier). Run your problem by a qualified electrician who will know about Z's (simplest way I can put it). If he likes your genre, it won't cost you nothing and may save your life. Also, some stages have power sockets from three different phases. An electrical fault in your equipment can result in lethal voltages between equipment which may be plunged in to different sockets. Modern regulations endeavour to prevent this, but for example: Australians can still plug a hair drier into a socket in their bathroom because the regulators don't believe that their citizens would be so daft as to dry their hair whilst sitting in the bath. Hum. Most Australians I've met are far from daft – but I did say 'most'. So, I think you would be better off genned up on ground loop so that you know how to inform and describe to an electrician your issue.--Aspro (talk) 20:43, 20 April 2014 (UTC)

But isn't Australia better off without those people who see no problem in bathing with their hair dryers ? :-) StuRat (talk) 04:36, 21 April 2014 (UTC)

Eliminating ground loops in house circuits is not a good idea. Most electricians won't know what it is and most residential codes do not allow isolated grounds. Hospital grade outlets and dedicated circuits are really the only foolproof way to eliminate ground loops in power lines. If you still have noise with an isolated circuit, the next step would be to see if the chassis ground can be isolated from circuitry ground. That prevents the neutral/earth ground loop. Do not ever float the chassis to eliminate the noise as it must be tied to earth ground. Noise from CFL's can be propagated on the power line and across transformers so air distance is not very important (X10 and other high freq data is propagated on power lines as well). --DHeyward (talk) 03:37, 22 April 2014 (UTC)

Power factor ?

CFL's seem to create some type of weird problem with the power factor or some such thing, which I've observed when I put them on the same circuit with a regular fluorescent light, all triggered by a motion detector. The lights wouldn't start until I added an incandescent bulb to the circuit, too. I wonder if LED lights also have this problem, or if they would work like an incandescent and smooth everything out ? StuRat (talk) 19:51, 19 April 2014 (UTC)

The motion detector is probably trying to bleed through a small current through the CFL to operate itself, so it may need a lower resistance item in the circuit to work. Graeme Bartlett (talk) 20:40, 19 April 2014 (UTC)

So do CFLs have high resistance, until they turn on, then drop to low resistance ? And would LEDs exhibit this behavior, too, or behave like incandescents ? StuRat (talk) 21:18, 19 April 2014 (UTC)

If I'm not mistaken, CFLs do have a high resistance at first because enough power has to be put into them to get the gas inside to fluoresce. Once the gas is fluorescing, then the resistance goes down. That is one of the problems (only one?) in getting CFLs to dim. LEDs can and do dim depending on the power that they are supplied, so I would expect them to allow a certain amount of power through without any observable light. Dismas|^(talk) 03:01, 20 April 2014 (UTC)

Interesting. So dimmable CFLs should work then, too ? StuRat (talk) 03:05, 20 April 2014 (UTC)

Good luck. Dimmable CFLs don't even work with all dimmers (I know, because I have one). As for LED's, It would seem to depend on the circuitry used for lighting but they can have ballasts, too, and that circuit combined with the motion sensor circuit would determine how "on" is achieved. --DHeyward (talk) 03:37, 22 April 2014 (UTC)

Yottabytes stored in all servers worldwide?

Does of you have any reliable information on how many bytes of data (ranging from text to movies) are stored in all the servers worldwide? One server alone in Utah is said to be able to store 1 yottabyte of data. 112.198.90.173 (talk) 21:20, 19 April 2014 (UTC)

Wired handwavily estimated that NSA's Utah Data Center could "handle yottabytes" (where "handle" does mean "store"), but Forbes estimated (with slightly less guessing, but still lots and lots) that it could store "3 and 12 exabytes", much less than a yottabyte. -- Finlay McWalterᚠTalk 21:44, 19 April 2014 (UTC)

"Handle" might mean "process". So, they might well process 1 yottabyte of data in a year, but only decide 3 and 12 exabytes of it is worth storing. StuRat (talk) 00:51, 20 April 2014 (UTC)

Grr, I meant to write "Handle" does not mean "store". -- Finlay McWalterᚠTalk 08:36, 20 April 2014 (UTC)

But are there any data how many bytes of data of humankind ranging from private data to govern databases are currently stored in the servers of the world, meaning the sum of all data produced by humankind since inception of data gathering? 112.198.90.161 (talk) 07:05, 20 April 2014 (UTC)

Our articles on Exabyte and Zettabyte have better information than Yottabyte. Dbfirs 07:17, 20 April 2014 (UTC)

No. Companies tend to keep that kind of thing secret. We can place some limits based on the number of hard drives sold. That suggests a few tens of Exabytes at most.©Geni (talk) 10:13, 20 April 2014 (UTC)

That's only data stored online, though (meaning "quickly retrievable", not "Internet accessible"). The amount of data archived on tape may be orders of magnitude higher. "The sum of all data produced by humankind" would be still larger, since a lot of it has been lost. For example, the Large Hadron Collider's detectors produce about one petabyte per second of raw data, which would fill the entire world's supply of online storage in a matter of hours. The vast majority of it is discarded without ever being written to disk (they try to keep the most interesting events). -- BenRG (talk) 00:46, 21 April 2014 (UTC)

Replacing harmful flora with innocuous flora as a cure

You have probably already heard of people with colitis being treated by cleansing their intestinal tract and then deliberately repopulating it with a collection of different organisms, usually obtained from a healthy individual. It made me wonder about other ailments that arise from a disturbance in flora. For instance there's a suggested relationship between certain species of Malassezia (a yeast) and dandruff and seborrhoeic dermatitis and related skin disorders. Would it not be a good idea to try to cleanse the skin and then supplant those yeasts with less problematic ones? The same with acne, too. When I was a spotty kid, I got some sort of infection in the corner of my mouth which was easily treated with an antibiotic cream and didn't come back. The cream also reduced my spots but they came back after discontinuation of that cream. Maybe if I'd replaced the bacteria with a type that didn't have any involvement in acne, I'd have been "cured". I'm reckoning there are other afflictions that could be handled similarly but can't think of any at the moment. Do my suggestions make sense or is there a flaw I'm not seeing? I guess obtaining the alternative flora in appropriate ratios might be difficult. I know those "good bacteria" yoghurts are a crock because they don't represent the variety of bacteria in a healthy intestinal tract. --129.215.47.59 (talk) 22:52, 19 April 2014 (UTC)

The difference is that you can control which organism enter your intestines more easily than the bacteria which contact your skin. But, in areas where the person can control what goes in and out, your suggestion does make sense. For example, vaginal yeast infections could be controlled by introducing "good" organisms. (Douching seems to be the cause of many yeast infections, because it removes those good organisms.) StuRat (talk) 23:18, 19 April 2014 (UTC)

• For reference, the OP seems to be hinting at gut flora and perhaps fecal transplants. Also probably the human microbiome. Last sentence seems a bit WP:SOAP, but we do have articles on yogurt and Fermentation_(food). That will be a good start with references, I'll think more and come back later :) SemanticMantis (talk) 23:28, 19 April 2014 (UTC)

The last sentence might be incorrect but was based in the fact that there are hundreds of species of bacteria in the healthy gut and there are less than 20 in probiotic yoghurt. Finding sources for how many different yoghurts contain is proving difficult. I've only found two sources so far. "It has three times the amount of probiotics that are in yogurt. This is because of the fact that in order to ferment a milk with kefir, 10 to 20 different types of probiotic bacteria and yeasts should be mixed" "A popular brand called Lifeway has 12 species or cultures." 129.215.47.59 (talk) 01:18, 20 April 2014 (UTC)

It's possible that only a few are often lost from the intestines, and in need or replenishment. StuRat (talk) 03:03, 20 April 2014 (UTC)

The reason your acne came back was because it's etiology is more complex than a simple bacterial infection (it is caused initially by hormonal changes) and the treatment didn't last long enough. It usually takes a number of months to clear it up. see [1]. Richerman (talk) 09:55, 20 April 2014 (UTC)

April 20

If it's called cardiac arrest when the heart suddenly stops...

...what's it called when the brain suddenly stops? Ac05number1 (talk) 02:37, 20 April 2014 (UTC)

Brain death. Dismas|^(talk) 02:54, 20 April 2014 (UTC)

Even in total brain death, parts of the brain, like the brain stem, may remain active. StuRat (talk) 02:59, 20 April 2014 (UTC)

That's not correct. See brain death#Medical criteria. Looie496 (talk) 13:26, 20 April 2014 (UTC)

I don't think it stops suddenly. The heart doesn't usually completely stop all at once either, just parts of it stop or pump out of sequence. StuRat (talk) 02:57, 20 April 2014 (UTC)

• In some contexts, where a "cardiac arrest" is called a "heart attack", a Stroke is sometimes called a "brain attack". --Jayron32 03:06, 20 April 2014 (UTC)

Why does the term "cerebral arrest" not exist? -- Jack of Oz ^{[pleasantries]} 07:34, 20 April 2014 (UTC)

There's no accounting for the quirks of English. But consider this: The term "arrest" means to stop.[2] It occurs to me that the term "arrest" in any context usually refers to a sudden or swift action - like it's either beating or it isn't. In the case of the heart, if it stops beating it's pretty obvious just from listening to the chest. The brain doesn't "beat" like the heart does. It requires medical equipment to detect its activity, or lack thereof. ←Baseball Bugs ^{What's up, Doc?} carrots→ 07:46, 20 April 2014 (UTC)

Cerebral arrests are the Thought Police's job. —Tamfang (talk) 08:44, 20 April 2014 (UTC)

Cool. I'm sometimes tempted to make a citizen's cerebral arrest. Of course, in my particular case, it would be a cerebral citizen's arrest.  :) -- Jack of Oz ^{[pleasantries]} 09:02, 20 April 2014 (UTC)

• "Cardiac arrest" means that the heart suddenly stops pumping blood, but in almost every case the individual muscle fibers continue to contract for a while. What happens is that they lose their global synchrony, resulting in fibrillation. The most directly analogous phenomenon in the brain is an epileptic seizure. Those are rarely fatal, though, because they eventually end and don't cause the heart to stop. Breathing may stop for a while, but it usually resumes after the seizure ends. Looie496 (talk) 13:21, 20 April 2014 (UTC)

Yes but the brain can also go into a loop vis avis BB.31.55.123.188 (talk) 00:47, 21 April 2014 (UTC)

The end of LADEE

From IB Times: "Before LADEE crashed into the lunar surface, the spacecraft reached speeds of 3,600 miles per hour, and it most likely broke apart before impact."

What could cause LADEE to break up before impact? Bubba73 ^{You talkin' to me?} 05:24, 20 April 2014 (UTC)

I can think of two reasons why a plunging satellite might break up, but neither seems strong enough on the Moon to have that effect:

1) Hitting the atmosphere. The Moon has a very thin atmosphere, so even at 3600 mph, this doesn't seem likely to cause it to break up, to me, even considering that the satellite isn't designed to withstand re-entry.

2) Tidal effects. Here the near side of the object is pulled more than the far side. This caused Comet Shoemaker–Levy 9 to break up before it hit Jupiter. But, the Moon's gravity is far less than Jupiter's, so this seems unlikely. StuRat (talk) 07:18, 20 April 2014 (UTC)

Yes, but it had been orbiting only about 1 mile above the surface for a while, without breaking up. Bubba73 ^{You talkin' to me?} 08:20, 20 April 2014 (UTC)

I think it's just an error by the IB Times. The NASA press release says it broke up "during impact". -- BenRG (talk) 08:05, 20 April 2014 (UTC)

Probably. Bubba73 ^{You talkin' to me?} 08:20, 20 April 2014 (UTC)

I don't think either knows for sure. I suspect it loses stability in flight and begins cartwheeling. The centrifugal force rips it apart. --DHeyward (talk) 15:39, 22 April 2014 (UTC)

What strain/breed of Columbia livia/Columbia livia domestica is the common white dove?

I have a problem with the so-called white doves (it's Easter day, after all... happy Easter to everyone!). This article says the most common strain of white doves is the Stielbacht, a breed or strain that does not apperar in this list. Should it be added or is it something different from a proper breed?--Carnby (talk) 10:04, 20 April 2014 (UTC)

It's not Columbia, but Columba, which is mentioned.

Resolved? - ¡Ouch! (^{hurt me} / _{more pain}) 06:03, 22 April 2014 (UTC)

Nodal loads on shear and moment diagrams

How do you represent nodal loads on shear and moment diagrams. As far as I know, these diagrams, always start and end at 0. So if for example, a simply supported beam has a uniform load on it but also a nodal load on 1 support. How do you factor this in? If I simply draw the uniform load on the diagrams and then put in the nodal load, the diagrams wouldn't end at 0 and hence the beam wouldn't be in equilibrium. Clover345 (talk) 14:35, 20 April 2014 (UTC)

Do I need to perform a HIV test?

For more than a year, I have been having my hair cut at a nearby barber shop (around 10+ times). The barber always cuts my chin when shaving, maybe because my beard is hard. He used his fingers cleaning the blood, and I did not notice it until recently. I have 2 flus, 1 at the time being, and 1 long ago I cannot remember. 3 months ago I had a muscle pain in my left leg which lasted for nearly 2 months. I felt extreme pain when I stretched my leg or performed a high kick. Currently it has not fully gone, but is negligible. I am 25, healthy. I don't care much about the flus, but the leg pain was really unusual.

Although I got cut many times, I know the risk is very small. The number of HIV infected people going to the same barber shop is small, the number of people getting cut is small, the chance between 2 bleeding people is small. But I am still worry about my unusual leg pain. Are there many causes for such pain? I do not really want to take a HIV test because of the discriminations. People here consider only those with social issues (drug, have sex with prostitutes, etc...) are vulnerable to the disease and need such kind of test. -- 222.252.79.24 (talk) 14:39, 20 April 2014 (UTC)

We cannot give you medical advice or diagnosis. See your doctor (and change your barber).--Shantavira|^{feed me} 14:49, 20 April 2014 (UTC)

For the benefit of other respondents, the IP geolocates to Vietnam (technically Hanoi, but I have doubts Vietnamese geolocation is that accurate). Nil Einne (talk) 16:25, 20 April 2014 (UTC)

222.252.79.24 - Be careful when looking for these kinds of things on the Internet; many people answer confidently without knowing what they're talking about and it's very easy to get bad information. Most doctors will not give definitive answers to these kinds of questions over the internet, nevermind us non-doctors, so as already stated we cannot give medical advice here. If you've not seen them already, there's an article on HIV/AIDS tagged as "good article" (high quality) as well as on Misconceptions about HIV/AIDS. The US government has a website for HIV/AIDS information that might be useful (aids.gov) and the AIDS Healthcare Foundation also operates in Vietnam, offering various services including testing. But it would be best to just call your local doctor who would be best able to point you in the right directions and answer questions you have. --— Rhododendrites ^talk |  17:55, 20 April 2014 (UTC)

Is the stigma or social discrimination attached to merely taking the HIV test, or to failing the test? ←Baseball Bugs ^{What's up, Doc?} carrots→ 03:39, 21 April 2014 (UTC)

It is apply to both those who apply the test, and those who are HIV-positive, although the latter being worse. The stigma even comes from your beloved relatives. I had a drugged cousin who died of this disease around 10 years ago. My uncle (his father) sent him to a drug treatment camp, only for him to be beaten badly by others. Other relatives, including my parents, did not give him any concerns. No treatment was given, and he died when he was at my age, 5 years after the infection. Sad story. I think I will have an anonymous test in the next few months anyway, although I highly doubt if I am really in trouble with this cursed disease. -- 222.252.79.24 (talk) 12:20, 21 April 2014 (UTC)

Acacia motteana and Acacia podalyriifolia

I have read that Acacia motteana and Acacia podalyriifolia are two names for the same species. Do you know if it's true?--Carnby (talk) 14:54, 20 April 2014 (UTC)

This page says so - assuming that "sin." means "synonym". I couldn't find the use of A. motteana on any English language website. Alansplodge (talk) 22:07, 20 April 2014 (UTC)

Revision strategy

How do you revise for physics exams? Past papers and example questions? Do you have to time yourself? I find it too hard to time unless I've done every type of question possible which isn't always feasible as there's too many possible types. 90.205.212.104 (talk) 16:20, 20 April 2014 (UTC)

Your tutor will be able to guide you better than we can. Every course has a syllabus, and you will be asked questions on what you have covered from the syllabus. Your tutor will tell you whether there will be multiple choice questions on the paper, and how to complete the paper if there is. He/she will also be able to provide you with past papers. You only need to revise what is on the syllabus. --TammyMoet (talk) 18:59, 20 April 2014 (UTC)

Yes, your teacher will be the best guide, because we don't know what exam or syllabus you are studying for, but past papers are an excellent way to revise , provided that they are on the same syllabus as your exam. Understanding is more important than timing, but it would be useful to try an occasional times paper just to check that you are not working too slowly. Have you not done a "mock" paper? Dbfirs 20:27, 20 April 2014 (UTC)

Read and re read your notes whilst subjecting yuorself to physical pain such as sitting on your leg. In this way, the knowledge will embed itself in your brain.31.55.123.188 (talk) 00:21, 21 April 2014 (UTC)

I made it a point to perform all my studying for the Private Pilot Knowledge Test using only my cockpit kneeboard as my writing surface, and occasionally studying in unusual attitudes... because if I could perform well in those conditions, I could ace the written test in normal desk conditions. Quoting an archived newsletter, "...Quality unusual attitude training creates a unique environment in which to learn how to override the potentially debilitating mental inertia that accompanies the normal shock of an unexpected loss of control." As physics written tests go, this exam was one of the easiest I've had to endure, but I also spent more time studying for it than any previous exam I had taken. Nimur (talk) 21:48, 21 April 2014 (UTC)

Is "revision" British English for studying ? StuRat (talk) 22:46, 21 April 2014 (UTC)

Yes. Think of re-vision as re-viewing. --50.100.193.30 (talk) 23:01, 21 April 2014 (UTC)

Seems potentially confusing, where "note revision" could either mean modifying your notes or studying them. StuRat (talk) 23:11, 21 April 2014 (UTC)

Yes, potentially confusing to American readers, but not in the UK where I used to re-write my notes (onto small cards that I carried round with me to look at in boring moments) as part of my revision (studying, reviewing) for exams. This British sense of the verb to revise is restricted to education, but has been in use since 1886 (first unambiguous usage with this sense in The Lancet). It's sense 3 in Wiktionary, marked as UK, Australia, New Zealand. Dbfirs 09:23, 22 April 2014 (UTC)

microscopy

compare the limit resolution of air and oil — Preceding unsigned comment added by 115.240.159.50 (talk) 17:07, 20 April 2014 (UTC)

Please do your own homework.

Welcome to the Wikipedia Reference Desk. 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. --Jayron32 19:43, 20 April 2014 (UTC)

We have articles on both Oil immersion and Water immersion objective. Personally speaking, my objectives seem to improve when I am immersed in a good Single malt whisky. Hope this helps.--Aspro (talk) 22:02, 20 April 2014 (UTC)

But even macroscopic details become blurry after a while. DMacks (talk) 02:59, 21 April 2014 (UTC)

Location of the big bang and size of the universe

The observable universe is centred on Earth and it's unknown how big the universe is with some saying that it's infinite. I have a couple of questions, though I imagine you guys will have to correct me on a lot.

I see in the news every so often that new and improved telescopes have revealed how the very early universe took shape after the big bang. Does that mean in the observable universe we can see or almost see the location of the big bang and the very first galaxies?

The universe was only 630 million years old when GRB 090423 exploded and it took 13 billion years for that light to reach us. Similar to the above question, since we know GRB's location and how long is ago it exploded (relevant because everything is moving away from the big bang), doesn't that give us some clue as to the size of the universe and the location of the big bang? And would the location of the big bang be the centre of the universe, roughly, as everything in the universes exploded outwards from that location? Thanks, 92.16.58.122 (talk) 18:15, 20 April 2014 (UTC)

I know that the universe was just a small ball then it got much larger when the big bang occurred, like a balloon, so my question of location is whether the small ball expanded uniformly and so our knowledge of the early galaxies mean we know where the centre is and the length of time it took for that light to reach us mean we can guess the size of the universe. 92.16.58.122 (talk) 18:35, 20 April 2014 (UTC)

The usual analogy used for the young is to imagine the universe as the surface of a balloon. Draw a load of galaxies on a deflated balloon, then inflate it. The galaxies move further apart, but none of them are the centre. There is no location where the big bang started. The galaxies are not expanding away from the centre, they are expanding away from each other. There is no centre. The big bang wasn't an explosion of matter into space: it is the beginning of time and space as we know it, and space expands like the surface of a balloon.

This is exactly the right question for you to ask, to find out more about the big bang. So, well done. 86.146.28.229 (talk) 19:12, 20 April 2014 (UTC)

I see, thanks. So does GRB 090423's (former) location give us some clue as to the size of the universe? I imagine at 630 million years, the universe was much closer together/smaller than it is now. 92.16.58.122 (talk) 20:10, 20 April 2014 (UTC)

Not necessarily. We have some sense for the size of the observable universe, which includes ALL parts of the universe we can get ANY information about. Since the universe is actually larger than what we can observe, and by definition what we cannot observe we have no information about, we can only speculate about the actual size of the entire universe. You may find good reading at Universe#Size, age, contents, structure, and laws and Shape of the universe. The first section starts with the sentence "The size of the Universe is unknown; it may be infinite." That's about all we can say. --Jayron32 20:18, 20 April 2014 (UTC)

Also, I read that because everything is moving further away there are some stars that we'll never see because the light can't reach us. With better telescopes would that change? 92.16.58.122 (talk) 20:13, 20 April 2014 (UTC)

Nope. Telescopes can only capture light that we get; if the light never gets here, no matter how good our telescopes, we'll never see it.--Jayron32 20:18, 20 April 2014 (UTC)

Future horizon explains this at little more.--Aspro (talk) 21:13, 20 April 2014 (UTC)

The crucial point is that the universe is (or seems to be) homogeneous. This implies that there's no place where the big bang happened, and relics of the big bang (such as the CMBR) fill the universe uniformly. The matter that emitted the CMBR that we see now is now a certain distance away, and in that sense we're seeing faraway objects when we see the CMBR, but if we were somewhere else in the universe we would see similar CMBR from a different set of objects at the appropriate distance from that location. -- BenRG (talk) 01:08, 21 April 2014 (UTC)

(EC) The closest thing to the Big Bang that it's possible to see is the last scattering surface, which existed around the time of the recombination, about 378,000 years after the Big Bang. It isn't possible to see anything that existed earlier than that time because before that time, the universe was so dense that it was opaque. The light from that last scattering surface is called the cosmic microwave background, which we can still detect. But the cosmic microwave background comes to us from all directions equally, instead of coming from one particular direction, due to the expansion of the universe being an expansion of space itself, not an expansion of the universe into previously empty space outside of the universe. I.e., there is no direction that points toward the Big Bang, except that if you count time as a "direction", then the direction that points toward the Big Bang is "backwards in time". That perspective of "backwards in time" being very much like a "direction" is a standard perspective in Einstein's theory of relativity. Red Act (talk) 01:30, 21 April 2014 (UTC)

Also, if you have the math for it (I don't, but someone might) Minkowski space would be a useful read. --Jayron32 02:15, 21 April 2014 (UTC)

"Dense" isn't quite the right word; as per the name "recombination", the universe was hot enough prior to that time that it was a plasma and thus (more) opaque to radiation. (Pressure ionization does occur, but not at densities 10^-20 that of water like at recombination.) --Tardis (talk) 02:37, 21 April 2014 (UTC)

Point taken. I have struck out the problematic phrase. Red Act (talk) 05:50, 21 April 2014 (UTC)

does anything not sink to the ocean floor?

does anything not sink to the ocean floor? — Preceding unsigned comment added by Wilburlou544 (talk • contribs) 22:18, 20 April 2014 (UTC)

Yes, any object with a lower average density than seawater (about 1.025 grams per milliliter) will float. The volume used in determining that "average density" includes any volume of air that's unable to be replaced by water; see Archimedes' principle and buoyancy. Red Act (talk) 23:18, 20 April 2014 (UTC)

See Great Pacific garbage patch for an awful example... OttawaAC (talk) 01:25, 21 April 2014 (UTC)

An interesting variation on the OPs question (and possibly what they meant to ask): is there anything that will sink in water but not ultimately come to rest on the seafloor? I.e., something that will stop falling at a certain point and just sort of float about 20,000 feet down (or whatever). The answer to that question is also yes, and buoyancy is again the reason. Evan ^{(talk|contribs)} 02:23, 21 April 2014 (UTC)

The density of seawater is only a few percent more at the floor of the ocean than at the surface, due to the low compressibility of water, so the large majority of objects will either sink to the ocean floor or float. But yes, there do exist objects that have a density within the necessary range to maintain an intermediate elevation. For objects in or around that density range, the compressibility of the object would be an important consideration, too, i.e., the density of the object is going to change some depending on how deep it is, too, due to the pressure of the surrounding water. Red Act (talk) 03:41, 21 April 2014 (UTC)

I interpreted this Q differently: "Is there any living sea creature, which, when dead, won't eventually sink to the ocean floor ?". In this case I'd say that the decomposition process will eventually reduce the organism to microscopic floating particles and a portion which sinks, such as bones. StuRat (talk) 22:50, 21 April 2014 (UTC)

Just because it's relevant and awesome, behold the recently discovered Osedax. Also relevant is marine snow. SemanticMantis (talk) 00:05, 22 April 2014 (UTC)

I think the giant isopods at those whale falls are even cooler. StuRat (talk) 01:38, 22 April 2014 (UTC)

My guess was that the question was about flight 370. Red Act (talk) 00:10, 22 April 2014 (UTC)

And perhaps more specifically some metallic material recently washed ashore that might have come from that flight (but "We're just guessing at the moment"). Mitch Ames (talk) 12:56, 23 April 2014 (UTC)

April 21

Bazhin Gap

In the Nanga Parbat there is a high altitude gap/saddle called "Bazhin Gap". What does "Bazhin" refer to? Local dialect? A name of a person? The expression seems to be mentioned for the first time in the 1930ies. Any lead is appreciated. GEEZER^{nil nisi bene} 10:18, 21 April 2014 (UTC)

Probably a person. Note that there is also a "Bazhin Glacier" nearby. Looie496 (talk) 14:06, 21 April 2014 (UTC)

don't put warm food in fridge?

I had some leftovers that I was going to save in the fridge, but my mom says don't do that since they are still warm. I'm supposed to leave them on the counter til they reach room temperature before refrigerating. She says the same thing when we buy warm stuff from the store. What's the issue here? Does the quicker temperature change mess up the food in some way? Does putting the warm stuff (just an unfinished meal, not anything large) in the fridge temporarily warm up the fridge interior enough to speed the spoilage of other food in the fridge? Or is the whole thing just silly? Thanks. 98.207.66.10 (talk) 19:33, 21 April 2014 (UTC)

"Make sure food has cooled down before you put it in the fridge," says Philippa Hudson, senior lecturer in food safety at Bournemouth University.

"If the food is still hot it will raise the temperature in the fridge, which isn't safe as it can promote bacterial growth." [3] 86.146.28.229 (talk) 20:09, 21 April 2014 (UTC)

See also Danger zone (food safety). If you place an overhot item in the fridge, you increase the chance of raising the temperature of all of the other food around it to temperatures that promote unhealthy bacterial growth. --Jayron32 20:12, 21 April 2014 (UTC)

The U.S. Department of Agriculture says "Hot food can be placed directly in the refrigerator or it can be rapidly chilled in an ice or cold water bath before refrigerating."[4] The U.S. Food and Drug Administration says "Leftovers … need to be refrigerated or frozen within two hours … . Despite what some people believe, putting hot food in the refrigerator doesn't harm the appliance."[5] The Washington State Department of Health labels the idea that you shouldn't put hot foods in the fridge a "myth", and says "Hot food can be placed in the refrigerator."[6] Red Act (talk) 20:24, 21 April 2014 (UTC)

I do wonder if there are climate and cultural differences. The stereotype is that Americans have larger, more powerful fridges than Britons: I know that I have watched the temperature in my fridge rise out of the safe zone, when I have overloaded it. And American food safety advice I have seen seems to assume a much warmer environment than British food safety advice: perhaps in line with the jokes about room temperature being laughably unrealistic in British labs. And every bit of American advice which claims it is a myth, that I have seen, also has a note about if you left the food to cool and forgot about it for hours, which perhaps shows the motive for the advice. This would explain why the official governmental advice from the NHS, supported by expert advice, is to allow food to cool before putting it in the fridge, whereas the official governmental advice in America is to not worry about that. 86.146.28.229 (talk) 20:31, 21 April 2014 (UTC)

I'd say it depends. If you have a powerful, almost empty fridge, containing food that doesn't really need refrigeration anyway (like fruit), and the food you want to put in isn't all that hot, but might tend to spoil quickly, then go for it. On the other hand, if it's very hot, doesn't need refrigeration all that much, and you will need to cram it in right next to some foods that really need to be properly refrigerated (like egg salad), and your fridge can barely keep up with what's already in it, then wait. StuRat (talk) 22:57, 21 April 2014 (UTC)

Thanks, I see. At least this identifies the issue, of warm food in the fridge transferring heat to other food. Of course letting the warm food sit outside the fridge probably attracts even more bacteria, but whatever. 98.207.66.10 (talk) 01:09, 22 April 2014 (UTC)

• This really depends on the food and circumstances. Soup in a pot with a lid that forms a seal can be brought to a boil and served, then left on the stove with the lid closed, be removed from heat, and let cool overnight. As long as the lid is not removed and the stock was boiling it is sterile. Leaving out uncovered eggs or dairy to cool is foolish. Bacterial growth is normally most rapid around body temperature. The worst thing to do is to let food sit warm. It's an easy way to get you restaurant shut down. Food should be under 40 or over 140F. If your fridge is from the 1940's a warm pot might be a problem, but letting a newer model run to cool the food is better than kidney failure. μηδείς (talk) 02:53, 22 April 2014 (UTC)

Hypoxia

I have read the article on hypoxia, but it did not answer my questions. What are the cumulative effects of marginal hypoxia? What would the main symptoms be? Thank you. — Preceding unsigned comment added by 62.56.71.197 (talk) 21:45, 21 April 2014 (UTC)

I'm not an expert on hypoxia, but I suppose drowsiness and fatigue would be two of the most likely symptoms/effects. FWiW 24.5.122.13 (talk) 05:48, 22 April 2014 (UTC)

Confusion and muddled/slow thinking. It kills pilots because they are awake but unaware of danger or that help is in their interest. --DHeyward (talk) 09:52, 23 April 2014 (UTC)

Rust treatment

Steel gasoline (UK: petrol) tanks of cars and motorcycles that have internal rust are difficult to clean, access is only via by small openings and most of the inner surface is out of sight. Vinegar which is mainly dilute Acetic acid is suggested in online videos as a rust remover so I experimented by letting the head of a rusty screw soak overnight in a teaspoonful of concentrated "Vinegar Essence 35%" which is cheap (and is probably safer than an industrial chemical such as phosphoric acid). The pictures show my results which are promising. The questions are:

1. Surface rust on the screw has blossomed into a powdery scale (center pic). This happens above the submerged part of the screw. I suppose capillary action and/or a reaction in air occur. Can anyone explain what chemical reaction is likely here?
2. The converted rust could be washed off with warm water (right pic). The bolt head is now almost rust free, and I can repeat the treatment. But in the case of a fuel tank I suspect the acid etched surface will be prone to rust again quickly. My question is what is a good way to finish the vinegar treatment? I am considering alternatives such as rinsing with Kerosene, Gasoline or with dilute caustic soda ? JustAnotherUploader (talk) 23:50, 21 April 2014 (UTC)

I'm wondering if it makes economic sense to try to remove rust from a gas tank, instead of replacing it. To remove the rust you will have to remove the gas tank (which is quite a job, in the case of a car), drain it, then use quite a bit of whatever rust removing agent you decide on, then rinse that, then coat it with a large quantity of some type of anti-rust treatment, then maybe let it cure for a while, then rinse again, dry all the water out, then re-install. The labor and other costs of all this sounds like it would exceed that of a new tank (or maybe a used one from a junkyard). Perhaps an exception might exist for old tanks for which no replacement can be found, or when you need to keep the original parts intact in a classic vehicle. StuRat (talk) 01:26, 22 April 2014 (UTC)

• I have to agree with Stu. Have a professional replace the tank. The last thing you need is rust particles flowing upstream into the engineworks. Pennywise, poundfoolish. μηδείς (talk) 02:40, 22 April 2014 (UTC)

April 22

Which covalent bonds are broken in DNA cleavage by nucleases?

When DNA is cleaved by restriction endonucleases, meganucleases, engineered zinc finger nucleases/TALENs or Cas9 which covalent bonds are broken? Are they different for each type and if so, does that affect the repair mechanisms? --78.148.106.196 (talk) 00:47, 22 April 2014 (UTC)

I suggest you read the first sentence in nuclease, and our article on DNA. There is only one bond to be cleaved in DNA. Fgf10 (talk) 07:08, 22 April 2014 (UTC)

I think I can see five potential bonds that could be cleaved. What makes you so sure that all enzymes cleave cleanly at that point? --78.148.106.196 (talk) 10:58, 22 April 2014 (UTC)

Only likely (from a chemical standpoint) possibilities, given we are talking about the phosphodiester bonds of the backbone linkage, are the two P–O (those O being the 3' and 5' on the adjacent deoxyribose parts of the two DNA residues). The two O–C are comparatively harder to break. And the C^5'–C^4' is not at all fragile. The question of "which P–O" is a reasonable one. Assuming the phosphate remains attached to one of the two DNA residues, does it stay with 3' (breaking off the next one's 5') or vice versa? DMacks (talk) 14:56, 22 April 2014 (UTC)

I think it's going to be a while before I can answer my own question. I know that some of the enzymes form covalent bonds with the DNA which are then broken. Also, since the restriction endonucleases, Cas9 and the business ends of ZFNs and TALENs all derive from an evolutionary need to protect bacteria from invading phage and plasmids, I think it stands to reason that the DNA might be cleaved in such a way that it couldn't easily be ligated back together. I don't know nearly as much as I'd like to about DNA repair. Some day... 78.148.106.196 (talk) 19:46, 22 April 2014 (UTC)

Rotary cannon and super capacitors

The M61 Vulcan compared to the Gryazev-Shipunov GSh-6-23 has a slower rate of fire and has a slower "spin up" time. The article says this is due to the GSh-6-23 using a gas operating system instead of an electrical system to cycle the weapon. I was wondering if a rotary cannon were powered by super capacitors, would they have more power, and therefore spin up faster and have a rate of fire comparable to the gas operating rotary cannon? Also on a related note, would super capacitors grant electric cars greater acceleration? ScienceApe (talk) 00:59, 22 April 2014 (UTC)

My guess is that you are not on the right track. The reason the electrical system would be "slower" I doubt is because of the power delivery, which is probably from the vehicle. It seem far more likely to me that it is a synchronization or motor speed issue, there’s also heat dissipation and many other factors to consider. These guns are designed with many specifications in mind, including weight, cost and serviceability, not just “rate of fire”. No doubt you COULD make a faster firing, electrically powered rotary cannon, could you do it with super capacitors? I don’t really see why you’d bother, there are perfectly serviceable high speed motors, I don’t think power delivery is the limiting factor there. As for cars, power delivery ‘’might’’ be a factor, but no doubt weight and cost are also, and I don’t think electric cars have a problem with acceleration, the major problem for electric cars is range, so weight plays a more important factor. Vespine (talk) 02:17, 22 April 2014 (UTC)

Have a read of the applications section of the Supercapacitor article, if you haven't already. You'll get a good idea of the kinds of situations supercapacitors are being used in, they generally supplement systems where batteries are already used or only small amounts of power are required. They might be used in electric cars, but it would be more to save the batteries from spikes in current drain which could reduce their (usually expensive) life, rather then to "supercharge" the acceleration or anything like that. Vespine (talk) 02:24, 22 April 2014 (UTC)

Right, as for electric cars, I would guess that the acceleration is actually limited by the computer to act more like a traditional gas-powered car. In a conventional internal combustion engine, torque increases with engine RPM and will eventually decrease at even higher RPMs (see Power band), hence the need for transmissions with multiple gear ratios. This isn't the case with electric motors. Electric motors can produce maximum torque instantly. So the actual acceleration is probably limited to keep people from doing a burnout every time they tap the accelerator. Though they certainly can if you want, the Tesla Model S has a 0-60 time of ~4 seconds, comparable to a Corvette. And then there's the EV-converted 1972 Datsun that can do it under 2 seconds, comparable to an F1 car.

Another benefit to using supercapacitors in vehicles though is their short charge time. They can be fully charged in minutes rather than hours. So for vehicles that stop a lot at predictable locations for short periods of time like buses, you can build electric vehicles that can run all day without needing continuous overhead wires like a trolleybus. Mr.Z-man 03:34, 22 April 2014 (UTC)

Why does the gas operated rotary canon fire faster/faster spin up time? Isn't it because the propellant produces more power? ScienceApe (talk) 01:49, 23 April 2014 (UTC)

To touch the gun part of the question, there are newer Vulcan cannon which have both an increased ROF and shorter spin-up interval; they achieve that through decreased spun mass rather than better motors (or a Tim Taylor-esque "more power" approach). Other guns (including the XM301, no image though) feature a truncated-conic (rather than cylindric) barrel array, where the muzzles are at the narrow end. This does not only (slightly) decrease spun mass, but it limits the energy taken to spin the array, because a lower linear velocity will translate to the same angular velocity. The fact that the muzzle velocity vector and the axis are no longer parallel is accounted for easily.

During live-fire exercises, many guns are used at a low speed setting (usually half or two thirds of battle speed), and fed training rounds, which are not only cheaper than fully combat-effective rounds, but also easier on the barrels. - ¡Ouch! (^{hurt me} / _{more pain}) 06:59, 22 April 2014 (UTC)

Most modern gatling guns operate using a DC motor to cycle the rounds (chambering, ejecting, etc.) A typical time frame for the gatling gun to reach full fire rate is about 0.4 seconds (see GAU-19). So the super capacitor idea is kind of a moot point. Justin15w (talk) 15:30, 22 April 2014 (UTC)

This page states about the Soviet GSh-6-30 that

The charging and spin-up of the barrel group before firing was achieved with the use of a pneumatic system which included, among other things, a pair of compressed air storage tanks and a "pneumostarter".

From the same author, we get spin-up times of about 0.4s for both the older M61 Vulcan and its bigger cousin the GAU-12, while the GSh times are merely given as "far less". The newer M61A2 is stated to have an improved spin-up of 0.25 seconds.

Currently, rotary cannon seem to come in roughly five sizes.

• 5.56mm, based on the 5.56mm NATO round, the 5.45mm Soviet, or the .22 Long Rifle. These are of very limited use due to their short range.
• 7.62mm (NATO or Soviet). These are heavy machineguns in terms of raw firepower but not WRT range. However, the sheer volume of fire does help achieve kills at ranges which wouldn't be called "effective" for single-barrel machineguns.
• 12.7mm MG (again, NATO or Soviet). These are the true heavy machineguns, usually found on the heavier vehicles, or as small guns on ships or attack helicopters.
• 20 to 23mm. Most of these cannon are mounted on fighter planes or air defense platforms. The CIWS role is notable, too. Spin-up is critical in the dogfighting role, and only there. In the CIWS role, the ROF is usually stepped down on purpose, because the full volume of shells would not outweigh the lower accuracy, except at very close range.
• 25mm and more. Old high-caliber guns are usually in the 30+ range, while most newer guns use 25mm shells with little to no loss of effectiveness. Roles are the same as the 20mm class, but better suited to overcome the low hit probabilities on maneuvering targets with a more damaging round. As noted above, the spin-up time is comparable to older 20mm weapons, but the GAUs are probably still behind the Soviet GShs. - ¡Ouch! (^{hurt me} / _{more pain}) 07:58, 23 April 2014 (UTC)

Mesopotamian units of measure

Dear refence desk

please supply the reference for two specific Sumerian units which are given with precision

first the cubit (kus) of 497 mm

second the mass of the pound (ma-na) of 497.7 grams

Thank you

Roland Boucher Irvine california — Preceding unsigned comment added by 2602:306:CE07:A6D0:21F:F3FF:FECE:3122 (talk) 03:14, 22 April 2014 (UTC)

You already asked here three months ago for support for the cubit being 497mm, which I'm aware that you need to be true in order to support your theory (that I won't link to) that the Sumerians basically invented the metric system 5000 years before the French proposed it. The information you were given last time, that in historical reality the cubit wasn't a precise consistent length but rather varied a bit depending on the precise time and location you're talking about, is still true. Red Act (talk) 05:43, 22 April 2014 (UTC)

It's also important to understand (and accept) that the levels of precision you're expecting did not exist in those days, even in places and timeframes where the units employed were consistent. AlexTiefling (talk) 12:27, 22 April 2014 (UTC)

Bah! This theory has bogus written all over it!

1. The meter was originally defined as 1/10,000,000th the distance from the pole to the equator - there is no way the Mesopotamians knew the size of the earth to any kind of precision - so it can only be coincidence that their definition of the cubit is remotely close to a half meter.
2. As we've already pointed out, there are countless different standards for the "cubit". Finding one specific place where it just happens to come out within a percent or two of a half meter isn't a great way to come up with a theory. What about all of the other places where it WASN'T close to a half meter?
3. If they had intentionally defined the pound in terms of the cubit in the same manner that the kilogram is defined in terms of the meter (1 kg = the mass of 1 liter of distilled water at 4 degC = 1/1000th of a cubic meter of water at 4 degC), they'd have had to choose a temperature at which to make that definition. The only way for your theory to make sense would be if they (like the French) chose the temperature of 4 degrees Centigrade to measure the density of water. Since Mesopotamia is a fairly hot region of the world, with very few mountains high enough to reach those low temperatures, it seems highly unlikely that they'd have happened to pick the exact same temperature as the French at which to define their system. It's stretching the bounds of plausibility to breaking point to imagine that they'd have done that.
4. If you'd picked a HALF meter as your standard unit of length, then the natural unit of mass would be 1/1000th of a cubic cubit of water. That 'natural' measure would be EIGHT times less than the kilogram - not half a kilogram as you claim they used for their pound. A cubic volume of water weighing 1 meospotamian pound would be some very odd size in mesopotamian cubits...actually, an irrational number.

For all of these reasons, your ideas are very, very busted. The relationships you think you've found are nothing more than a coincidence.

SteveBaker (talk) 02:12, 23 April 2014 (UTC)

Hunger hormones VS Appetite hormones

As I know, it is now clear for scientists that Hunger and Appetite are 2 different things - Hunger will always bring appetite but appetite won't necessarily bring hunger.

My question is: Are there any documented Neurochemicals that deals specifically with hunger and others that specifically with appetite? Thanks Ben-Natan (talk) 04:08, 22 April 2014 (UTC)

I don't think your distinction between Hunger and Appetite is standard in the literature, but if you are using "Appetite" to mean the act of eating, then yes, there are biological distinctions. It isn't true, though, that hunger always causes eating. Unfortunately we don't yet have a very deep understanding of either the neurochemistry of hunger or the mechanisms that drive eating. Our article on hunger (motivational state) gives a rather sketchy overview of what is currently known. The hormones leptin and ghrelin seem to be pretty directly related to the sensation of hunger. Looie496 (talk) 14:02, 22 April 2014 (UTC)

Buoancy

If no water is displaced when an object is put in it, then how do objects like leaves float when they do not displace water and thus the water does not have buoyancy force? — Preceding unsigned comment added by 122.150.66.107 (talk) 04:52, 22 April 2014 (UTC)

Anything that floats on water displaces water. See Archimedes principle. Leaves don't displace very much, because they don't weigh very much. --50.100.193.30 (talk) 05:43, 22 April 2014 (UTC)

Perhaps surface tension has something to do with it. Richard Avery (talk) 05:59, 22 April 2014 (UTC)

Yes, surface tension has two effects: firstly, for an unwetted leaf, it moves the displacement of water away from the leaf (but the same amount of water is still displaced, it's just not as obvious); secondly, at the boundary of the container, it allows displaced water to form a meniscus above the edge of the container, preventing overflow. Thus the displacement of a small mass of water is not clearly observable. The displacement will be more clearly visible if you use heavier leaves and add a surfactant (e.g. detergent) to the water next time you try the experiment. Dbfirs 09:07, 22 April 2014 (UTC)

Giant bumblebee

Here in Central California this spring, there seem to be quite a few GIGANTIC black bumblebees (I'd say at least 1.5-2 inches in length, and about the same in wingspan), which I hadn't noticed in previous years. Are these native to California, or are they an invasive species? Are they any more dangerous than ordinary bumblebees (more aggressive/more toxic/etc.)? Thanks in advance! 24.5.122.13 (talk) 05:54, 22 April 2014 (UTC)

Black bees tend to be Carpenter bees, and there are many species of them. Some can get quite large: see [7]. If I had to guess, you have seen some kind of carpenter bee, but more specific than that, it would be hard to say. --Jayron32 12:40, 22 April 2014 (UTC)

There's also the black-chinned hummingbird there. The ones in our article don't look all that black, but here's one that does: [8], which can be mistaken for a giant bee, as it makes a similar sound and also hovers as it goes from flower to flower. (While in motion, the wings are a blur, so you can't see the obvious difference between bird wings and insect wings.) StuRat (talk) 13:38, 22 April 2014 (UTC)

Without pics it's hard to ID conclusively, but Xylocopa_varipuncta is the largest bee native to California. Females are metallic black, males are gold and fluffy. They can reach over an inch long, and can easily seem to reach 2" while on the wing. In general, actual bumble bees (bombus) are not very aggressive. Carpenter bees can be aggressive, but mostly to other bees. This in part comes from different social structures. Most carpenter bees are solitary, and each male will defend an area from other males, while hoping to attract mates. People often think they are a threat, as they will aggregate around e.g. wooden picnic shelters that they have prepared nesting sites in. The bees will then fly at incoming animals to investigate. So, you might feel threatened if one of these comes flying at your head, it actually poses no threat, it just wants to make sure you're not a rival bee. Males can't sting, and you can swat them away with impunity. For fun, you can wad up a bit of paper or aluminum foil and chuck in the direction of such an aggregation. The bee will quickly track that object, and follow it away from you. Since they don't live together in a large colony, they do not cooperatively defend anything, so it is almost impossible to get a swarm of them chasing you (unlike certain wasps, africanized honeybees, etc.) Anyway, just wanted to give you the general info that carpenter bees are nothing to be afraid of. Yellow jackets, however, are horrible jerks, and will seriously ruin your day ;) SemanticMantis (talk) 15:46, 22 April 2014 (UTC)

Looks like Xylocopa californica to me, because it was not shiny, although the one I saw up close was at least 1.5 inches long. Anyway, from what I gather, they ARE native to California, and the best way to deal with them is to just leave them alone, right? 24.5.122.13 (talk) 22:16, 22 April 2014 (UTC)

Right! The only "problem" they cause if if a whole bunch of them decide to try to nest in the eaves of your house or garage. Even then, mostly just an annoyance, but enough small holes can structurally damage over time (see e.g. here [9]) If you are getting "buzzed" by them often, just ignore, swatting at them may trigger aggression. SemanticMantis (talk) 15:04, 23 April 2014 (UTC)

Do Jews have some African/Black DNA?

All the people that I know are Jewish ethnicity/race have some of the same ethnicity-specific features as Black people including a cloud of big curly hair that grows out like an afro, very full lips and according to a funny book about true stereotypes, a giant penis. Since Jews have some of the features that are unique to African people does that mean they have some African/Black DNA? — Preceding unsigned comment added by 68.8.106.52 (talk) 05:12, April 22, 2014

We all have African DNA. HiLo48 (talk) 09:44, 22 April 2014 (UTC)

More specifically "In paleoanthropology, the recent African origin of modern humans, frequently dubbed the "Out of Africa" theory, is the most widely accepted model describing the geographic origin and early migration of anatomically modern humans." --Jayron32 10:52, 22 April 2014 (UTC)

That's correct, but the "Out of Africa" event occurred over 50,000 years ago. Since then there has been limited genetic mixing between sub-Saharan populations and non-African populations, so the question actually does make some sense at that level. The bigger problem is that there is really no such thing as a "Jewish race", or anything like it, at a biological level. Modern-day Jews derive from a pretty diverse mixture of backgrounds. In any case, as a group, it's extremely unlikely that they have higher levels of sub-Saharan-derived DNA than other people from the same parts of Europe or Asia. (I think the question is probably trolling but I have answered it seriously anyway.) Looie496 (talk) 13:51, 22 April 2014 (UTC)

The question may be related to Ethiopian Jews in Israel. Ruslik_Zero 19:32, 22 April 2014 (UTC)

For the hair bit: obviously not all Africans have the same hair type, nor do all Jewish people. Afro#Similar_styles_internationally has some discussion and references. SemanticMantis (talk) 22:12, 22 April 2014 (UTC)

By African/Black I mean someone the same racial ethnicity as (and this probably sounds offensive but) Flavor Flav. I know about the "Out of Africa" event and that all people are descended from people from the entire continent of Africa. But there are a lot of different types of African-nationality individuals, from this to this to this. But the hair texture of 100% Black people is unique to people of specifically Negro ethnicity (which is maybe what I should have written instead of African). Take the afro or the flat-top for example. Those specific TEXTURES are examples of natural Black hair and no one else on Earth has hair that grows that way, not even if they want it to, unless they have some Negro ancestry I would think. So I would like to get this question answered if you'll give it another try. Looie469, are there any charts or graphs or studies that could prove your view or mine? And I've read before that there is a difference between people who are religiously Jewish and ethnically Jewish. I guess not? — Preceding unsigned comment added by 68.8.106.52 (talk) 23:30, 22 April 2014 (UTC)

That type of hair is known as Afro-textured hair, or sometimes as "nappy hair", and it actually isn't true that only Africans and their descendants have it. As Afro-textured hair#Evolution explains, there are several other populations who live in equatorial regions who have similar hair. Looie496 (talk) 03:42, 23 April 2014 (UTC)

Those articles were very interesting! Thanks for enlightening me. — Preceding unsigned comment added by 68.8.106.52 (talk) 06:11, 23 April 2014 (UTC)

I had never heard of Flavor Flav, so I just checked our article on him. In every photo he's wearing a hat, so I still don't know what his hair looks like, and the article says nothing about his ethnicity. HiLo48 (talk) 06:31, 23 April 2014 (UTC)

Here HiLo, you can see a bit of his hair in this photo: http://images.starpulse.com/pictures/2009/03/22/previews/Flavor%20Flav-PRN-035552.jpg This guy doesn't look Black to you? Well, we're all entitled to our own opinion. Haha. Thanks. — Preceding unsigned comment added by 68.8.106.52 (talk) 07:01, 23 April 2014 (UTC)

Baseline fitness

Other than age, what influences natural baseline fitness levels. Without any training, anyone's fitness regresses but what influences the speed of regression and also where the regression stops, other than age. Clover345 (talk) 10:13, 22 April 2014 (UTC)

Physical fitness is a nebulous concept, and not easily quantifiable. There are aspects of fitness (such as the ability to complete certain physical tasks, like run a certain distance, etc.) or things like Basal metabolic rate or Body Mass Index or other such measures which are sometimes used as proxies for fitness, but none of those singularly captures what it means to be "fit". --Jayron32 12:34, 22 April 2014 (UTC)

Hormone levels are important, in particular testosterone in males. Looie496 (talk) 14:47, 22 April 2014 (UTC)

Physical activity an important factor here. If you exercise regularly from a young age onward, you should not notice a significant decline in physical fitness until you start to hit old age. Only if you are an olympic class top sporter who exercises a few hours per day will this be different. A typical 60 year long distance runner who has run for most of his life can perform just as well as when he was 30; exercising regularly will have helped to preserve the physical fitness he had decades ago. Count Iblis (talk) 15:07, 22 April 2014 (UTC)

Urinalysis

Do chlamydia and gonnorhea urine tests involve the same test as a urinalysis looking for white cells, blood etc? If not, why don't they do it along with the std test since they have a sample of urine anyway sand it can't be that expensive to do both? Do these test literally only detect chlamdia and gonnorhea? 90.205.212.104 (talk) 14:14, 22 April 2014 (UTC)

According to http://std.about.com/od/gettingtested/qt/Urine-Testing-For-Gonorrhea-And-Chlamydia.htm, the standard method of testing is to test for the presence of bacterial DNA in the urine. That's quite different from the method of looking for blood cells. Looie496 (talk) 14:46, 22 April 2014 (UTC)

They could also test for LSD metabolites, gold particles, and Borg nanoprobes. The questions invovled are reasonable suspicion of risk, cost-benefit analysis, and informed consent. μηδείς (talk) 16:57, 22 April 2014 (UTC)

Would borg nano probes and gold particles come out in urine? 90.205.212.104 (talk) 18:27, 22 April 2014 (UTC)

Does (or did) any country's military or police use the Desert Eagle pistol?

Question as topic. I thought at one time that the Israeli military and US Special Forces used them, for two examples - but I've been told not. I have been told that most Desert Eagles will only ever be fired at targets, tin cans and water jugs by private owners, because they're not actually that useful, in terms of effectiveness to the military and police, despite being a .50 caliber pistol. Also that they're basically 'more form than function'. Thanks. — Preceding unsigned comment added by 87.112.139.143 (talk) 21:43, 22 April 2014 (UTC)

This impressively outsized handgun quickly attracted the attention of Hollywood. The Desert Eagle debuted in "The Year of the Dragon," a 1984 action flick staring Mickey Rourke. Since then, it's been featured in some 400 to 500 motion pictures and TV films, including Arnold Schwarzenegger's "Eraser" and "The Last Action Hero." Whenever a script calls for a wicked-looking, thoroughly intimidating handgun, the Desert Eagle still gets the nod - says "American Handgunner". I observed one in the holster of a petite policewoman rushed on duty at Venice Airport hours after transatlantic air transport was shut down following the WTC Attacks. Nella lettura di questa mia cara, mi scusi se glielo dico ciò che difficilmente la si può sollevare solo il look ridicolo. JustAnotherUploader (talk) 22:09, 22 April 2014 (UTC)

The absence of scales in the pictures in our article make it hard to judge its size. DuncanHill (talk) 22:15, 22 April 2014 (UTC)

Demi Moore for scale (?) here [10], from this thread discussing the gun [11]. (I did look around for actual scales or size comparison, but couldn't find anything else that made it look big). SemanticMantis (talk) 23:57, 22 April 2014 (UTC)

With a barrel length of 10-15 inches depending on model, it IS pretty big for a pistol. 24.5.122.13 (talk) 05:34, 23 April 2014 (UTC)

I fired one once, caliber .50 Action Express, and nearly knocked myself over, though I'm a good bit heavier than Demi Moore. In hindsight I wasn't properly braced, but in combat you can't count on that anyway. —Tamfang (talk) 09:23, 23 April 2014 (UTC)

Why are "double red cell" blood donations by females subject to a higher weight requirement?

While looking at the Red Cross blood donation elgibility rules for something else, I noticed here that double red cell donations by females are subject to a higher weight and height requirement than those by males. Why is this the case? I initially thought that this was a mistake, but after some more searching, this doesn't seem to be the case. To me it doesn't make much sense, since one would think that quite a sizeable number of females wouldn't be heavy or tall enough, and given that men are generally taller/heavier. (While perhaps there are many "average" Americans who might fit the requirements, it for instance seems clear to me that from personal experience, this might disqualify a lot of Asian American women.) Morningcrow (talk) — Preceding undated comment added 22:45, 22 April 2014 (UTC)

On average, women have a lower proportion of blood per unit of body weight (in part due to their higher average body fat content) than men. Roughly speaking, men have approximately 75 mL of blood per kilogram of body weight, whereas woman only have about 65 mL per kilogram. Women also average a lower hematocrit (volume fraction of red blood cells in whole blood) than men.

The purpose of the requirements isn't to ensure that equal numbers of men and women are able to donate, but rather to ensure that it is safe for donors to do so. TenOfAllTrades(talk) 22:57, 22 April 2014 (UTC)

I figured it wasn't because of an interest in having equal numbers (otherwise it definitely wouldn't have made sense), but had no idea. Thanks - this more or less explains everything. 23:06, 22 April 2014 (UTC) — Preceding unsigned comment added by Morningcrow (talk • contribs)

Direct current from stored torsion (e.g. wind-up battery/battery charger)

Hi, I'm interested in the general physics and engineering at play here, but I'll put the two specific questions up front:

1. Are there any devices on the market that let you turn a crank to store energy in a spring, and then release that energy slowly to power a small electronic device (or charge a battery)? I'm aware of crank-powered flashlights and and chargers, e.g. [12], but those don't store mechanical power; they seem to universally require high speed, low-resistance turning for long periods of time, even to power a small radio.

2. Assuming negative to the above, are there any physical problems with the idea, or is it more a matter of engineering/materials/market limitations?

Elaboration on the idea: wouldn't it be more convenient to turn a crank with much more resistance, over a shorter period of time, with less dependence on rotation speed? E.g. if I wanted to charge a flashlight with a one-hour charge while camping, I'd rather work to wind a very stiff spring for a minute or so, than spin those little cranks quickly for about 10 minutes, perhaps repeatedly.

I'd think that a torsion spring could be rigged up to drive a small dynamo, and the resulting current could either run a device directly, or charge its battery, or perhaps even both, depending on needs. But then I get a little lost through all the details. Surely there's a lot of linkages, gearing, and other mechanics to worry about. We have to consider current/voltage demands, the spring constants of the material, the size of lever arms and rotors, etc. In summary, is it foolish to think that a device could do this? If not, could something like this be cobbled together from mostly of-the-shelf components? Weight, size and conversion efficiency don't matter much for the last bit, but of course they would for a hypothetical product. Thanks for any suggestions, SemanticMantis (talk) 23:35, 22 April 2014 (UTC)

Compressed air is used to store energy. Count Iblis (talk) 00:38, 23 April 2014 (UTC)

See Human power#Windup radio for a practical example of something that does exactly this. AndyTheGrump (talk) 00:44, 23 April 2014 (UTC)

Ah, thanks! I hadn't heard/seen any specific mention of spring storage before! SemanticMantis (talk)

I have such a wind-up radio. The idea is that it's ready for emergency use, while a battery-powered radio always seems to have dead batteries whenever the emergency occurs, and even if you have spare batteries, acid may have leaked out of the old batteries and destroyed the radio.

I also recall that on the TV show M*A*S*H, Radar O'Reilly would wind up the army phone before using it. StuRat (talk) 11:59, 23 April 2014 (UTC)

I am not 100% certain, but I think the 'winder' was only to signal the other telephone or switchboard. See here, and here which says this type of phone was in use from ≈1937, WW2 through to Korea, and "into the 1980s".--220 of ^Borg 13:47, 23 April 2014 (UTC)

Yes. Search for images of the old Freeplay flashlight. I was given one a long time ago, perhaps in the early 1990s, which had a clear plastic case so you could see the mechanism. The handle wound a very wide, substantial spring from one spool to another, taking about 20-30 seconds. When switched on, the spring wound back over a period of about 3 minutes, either operating the light or charging a small NiCd battery. I don't have the bandwidth for any images, but the Freeplay site does have a small support page for their discontinued Freeplay 2020 flashlight, which includes the warning, "The spring is powerful and dangerous. Do not remove any covers unless you are an experienced engineer.", so that sounds like the mechanism I remember. If I ever make it back to my storage unit, I think I will dig it out and look into converting it to LED. -- ToE 12:49, 23 April 2014 (UTC)

I don't understand the advantages here. I understand that you'd like to apply more torque for a shorter period of time - but that's just a matter of gearing. The only real questions are:

1. Is there some efficiency difference between storing energy in a spring versus a battery?
2. Is there some cost benefit in one mechanism versus the other?

My gut feel is that the spring doesn't discharge energy at all uniformly. Very high quality mechanical clocks go to a lot of trouble to even out the energy produced by the spring over time. All of that extra 'stuff' seems unnecessary if you use a battery to store the energy instead. Assuming the thing you're driving needs a uniform energy input, I think batteries will do a better job. NiCd and NiMH's have a fairly uniform voltage over most of the discharge cycle.

Cost is harder to estimate - but in our modern age, moving parts are generally avoided in favor of solid state stuff - so eliminating the spring seems like it would save money.

SteveBaker (talk) 01:42, 23 April 2014 (UTC)

Steve, I agree with most of what you say. I don't think this would be objectively better, or more efficient than batteries. Moving parts do wear down, etc. I thought maybe with some clever circuitry it wouldn't matter if the spring output was uneven. Shouldn't a system of RLC circuitry be able to buffer the mechanical input, so that the electrical output is more even? E.g. a moving average. Don't conventional battery chargers already do a bunch of "smart" controlling of the charging process to deliver current and voltage at different rates? To clarify, my interest is for things like camping, hiking, biking, etc. As for storage, I guess a large capacitor with high-resistance gearing might make the spring a worthless complexity. So maybe I should think about how to get bigger capacitors and higher gearing onto one of those cell phone chargers I linked above? SemanticMantis (talk) 02:45, 23 April 2014 (UTC)

This reminds me ... it's been a few years since we discussed energy budgets for automatic watches: has anyone found a reliable source that quantitatively discusses comparative energy-budgets for digital and mechanical watches? Nimur (talk) 04:55, 23 April 2014 (UTC)

Well, how about this: There is an extremely comprehensive source for Seiko watches HERE, From a quick look at that document, the analog quartz watches mostly used between 0.8 and 2.0 microAmps for the movement and 0.3 to 0.8 microAmps for the "circuit block"...although there are lots of outliers in some of their models. So we're talking between one and three microAmps for a typical quartz/Analog watch. This delivers a battery life between one and five years. Surprisingly, the digital watches seem to use a lot more power - around 1.0 to 10 microAmps for the "movement" (presumably that's watchmakerspeak for "display") and between 0.8 and 3.0 microAmps for the "circuit block" - so maybe 2x to 5x more power consumption than analog watches. But with a similar battery life quoted for each...so probably there are more/bigger batteries in the digital models. A watch battery holds around 250 milliamp-hours of charge - and at 1.2 volts, that's 200 milliWatt hours or 720 Joules of energy.

I'm not sure that helps to illuminate this question though! As I explained above, our OP's problem lies mostly with the gearing on the crank rather than the technology used to store the energy...and perhaps we can use this example to illustrate the problem:

I recently bought a rather nice antique grandfather clock. It has chimes that go off every 15 minutes, a second hand and a moon-phase dial - and it runs for about a week using the gravitational potential energy of three (roughly 1kg) weights lifted through about a meter. This is a better way to store and retrieve energy than a spring because the force exerted by the falling weights is exactly constant over the entire week...but obviously it's a lot less convenient for portable devices!

Anyway, I can wind the three weights up to the top of the clock using the hand crank provided in about 5 seconds per weight. It takes quite a bit of force to turn the crank - but it's a reasonably comfortable rate to crank at - and a longer crank arm would probably allow you to crank at this rate for a considerable amount of time. Now, we know that for gravitational energy, E=mgh, so when I'm winding it up, I'm providing about 30 Joules of energy over 15 seconds of work - so I'm providing about 2 Joules/second or 2 Watts while I'm cranking it. When fully wound, my clock stores about 30 Joules of gravitational potential energy - about 24 times less than that 720 Joule watch battery! Which means that this gigantic clock could hypothetically run for 24 weeks - close to 6 months - on a battery that will power a quartz watch for two years. So this gigantic mechanical monster from the 1800's is only 4 times less efficient than a beautifully engineered modern watch - and it ticks loudly enough to be heard in the next room, chimes every quarter hour loud enough that I can hear it from anywhere in the house and keeps a gigantic pendulum swinging backwards and forwards against all of the friction generated by 100 year old bearings and gears!

I find that rather impressive - (or to put it another way, those fancy watches are surprisingly inefficient devices!).

SteveBaker (talk) 14:11, 23 April 2014 (UTC)

I'm not so sure that a watch battery can power a grandfather clock for 24 weeks. Assuming your math is all correct, you're just comparing energy, and ignoring all the details of how a battery would transmit mechanical power, at what efficiency/loss, etc! Which was kind of the information I was looking for here, but the other way around. Still, interesting comparison, thanks. SemanticMantis (talk) 15:10, 23 April 2014 (UTC)

April 23

Basteria in diabetes control

Can high blood glucose level be controlled or reduced by introducing some non pathogenic strain of bacteria that is biotechnologically modified to not reproduce that will absorb glucose and decompose it.Is this possible.I am not a doctor but this idea occured to me.Please highlight and discuss.Has there been any research in this line.Ichgab (talk) 07:00, 23 April 2014 (UTC)

What's "basteria" -- bastard bacteria?  ;-) Anyway, if you put bacteria (bastard or not, modified or not) into your bloodstream, you'll get some really nasty consequences. 24.5.122.13 (talk) 08:30, 23 April 2014 (UTC)

Sorry for the typing error but i mean that the bacteria if it is biotechnologically maodified with the presently available hitech processes or if that is developed in near future to avoid sepsis then cant it be good method to control blood glucose level.117.194.232.254 (talk) 11:22, 23 April 2014 (UTC)

Well, that doesn't sound any better than injecting insulin, to me, unless the bacteria could be programmed to only reduce blood sugar when it's over a certain level. I seem to recall that some animal, (was it the Komodo Dragon ?) has a form of insulin which does that, so genetically modifying bacteria or other organisms to create that would be a great thing for diabetics, as they would no longer have to worry about overdoses causing dangerous blood sugar drops. And, without that concern, they could take a lot more insulin, say with an insulin pump, and thus avoid blood sugar spikes, too. Another approach would be to modify the insulin pump, from the current stupid version that injects insulin at a constant rate, to a smart one that injects insulin as needed, by taking blood sugar readings continuously. Of course, such a device would have to work 100% of the time, as a malfunctioning one could easily kill the patient. StuRat (talk) 12:07, 23 April 2014 (UTC)

Thanks for your clarification.117.194.238.140 (talk) 13:04, 23 April 2014 (UTC)

You're welcome. I looked it up, and Exenatide is the generic name of meds created from lizards (they list the gila monster, but other lizards, like the Komodo dragon, also have it). I was off a bit on how it works, though. Rather than being an insulin itself, it's derived from lizard saliva, and stimulates production of the patient's own insulin, and the patient's pancreas then releases insulin based on blood sugar levels, unlike the current insulin pump. StuRat (talk) 13:37, 23 April 2014 (UTC)

Can (non-human) animals get sick because of their poo throwing habit?

Which animals besides chimps do that? Then they eat with those hands? Really? Sagittarian Milky Way (talk) 09:45, 23 April 2014 (UTC)

Yes, any animal can become sick when exposed to feces which carry a disease. However, they are less likely to become sick from their own feces, as presumably they have already been exposed to anything in them. There could be exceptions, though, by reintroducing an organism which otherwise would have been cleared from their system. So, you could think of feces throwing as a form of biological warfare, where they attack the target with the organisms in their feces.

In fact, the potential for transmission of disease is the whole reason we have evolved an instinct to avoid feces. Not all animals have such an instinct, though, such as dogs, which seem to eat other animal's feces. Presumably there is some corresponding benefit to them which surpasses the risk, such as if they can extract some nutrition from them and avoid starvation. StuRat (talk) 13:01, 23 April 2014 (UTC)

. --Jayron32 13:48, 23 April 2014 (UTC)

That would be [13].--Shantavira|^{feed me} 15:12, 23 April 2014 (UTC)

Obligate Parasites

What's an obligate parasite, and what makes it different from other parasites? The article says it "cannot complete it's life cycle without exploiting a suitable host". I thought this was the case with all parasites. I'm confused. --Yashowardhani (talk) 11:03, 23 April 2014 (UTC)

See facultative parasite for examples. I updated parasite#Types to list the two types, with links to the articles. StuRat (talk) 12:44, 23 April 2014 (UTC)

Help with plant identification

Resolved

Unknown shrub

This plant has mysteriously appeared in one of our garden beds, and we can't figure out what it is. This is in Harlingen, Texas -- the Rio Grande Valley, right at the southern tip of Texas. I haven't seen anything like it in local yards, gardens, or the countryside. In case the picture doesn't make it clear, it is a shrub currently about two feet high, with a straight central stem covered with small stiff hairs, and opposed leaves. Does anybody recognize it? Looie496 (talk) 14:19, 23 April 2014 (UTC)

looks like Ragweed maybe Ambrosia trifida --Digrpat (talk) 14:49, 23 April 2014 (UTC)

It looks a bit like sassafras to me. However, Harlingen, Texas is a bit out of range for that one. --Jayron32 15:00, 23 April 2014 (UTC)

Maybe a ficus (fig) of some sort. See [14]. --Jayron32 15:10, 23 April 2014 (UTC)

After looking at pictures on Google Images, I'm satisfied that Ragweed is the right answer -- and I've expeditiously obliterated the plant. Thanks everyone. Looie496 (talk) 15:19, 23 April 2014 (UTC)

(EC) Pretty sure not a sassafras or ficus. Ficus have sclerotinous (i.e. hard, waxy cuticle) leaves, OP doesn't. Sassafras is an understory shrub, not a sun lover. It also would have obvious bark at that point, not a hairy stem. Looie, why do you call it a shrub? Is there any sign of woodiness at the base? From context, it seems much more likely to be a ruderal species of some annual plant. Ragweed seems like a good guess, but there are a lot of different varieties. Suffice it to say, it's most likely a weed. SemanticMantis (talk) 15:23, 23 April 2014 (UTC)

I called it a shrub because my knowledge of plant terminology is near the moron level, basically. Looie496 (talk) 15:31, 23 April 2014 (UTC)

ethylhexyl palmitrate/ethylhexyl salicylatte

Is Ethylhexyl palmitrate and ethylhexyl salicylate the same or akin to each other? I have recently been allergic to octyl salicylate and trying to figure out which cosmetics I can use and wanted to know the relationship of these two chemicals. thank you. 173.187.108.228 (talk) 16:23, 23 April 2014 (UTC)