Wikipedia:Reference desk/Archives/Science/2013 July 23

= July 23 =

Help identifying a plant.
All I have is this picture http://i.imgur.com/nJouLXy.jpg and I was hoping to get the common name for the plant so I can find other pictures of it.

The picture was taken in Tennessee USA and it was taken July 22, 2013

Thank you! — Preceding unsigned comment added by 50.95.51.218 (talk) 03:04, 23 July 2013 (UTC)


 * I'm guessing some kind of gooseberry, but I'd be hard put to say which species. Looie496 (talk) 05:21, 23 July 2013 (UTC)


 * It's called the Canna lily. Dominus Vobisdu (talk) 06:32, 23 July 2013 (UTC)

Why doesn't aluminium spark?
Why doesn't aluminium spark when ground? Aluminium is flammable, so shouldn't it spark? Or is the temperature reached during grinding just not hot enough to ignite it? Ariel. (talk) 08:02, 23 July 2013 (UTC)
 * At the link you provided it adds that aluminium is difficult to ignite accidentally. The reason explained in the article Aluminium is a thin surface layer of aluminium oxide that forms when the metal is exposed to air, effectively preventing further oxidation. Under the right conditions created in Thermite, powdered aluminium can give you sparky Fireworks. DreadRed (talk) 09:20, 23 July 2013 (UTC)
 * But that layer is abraded when put in a grinder. Ariel. (talk) 11:15, 23 July 2013 (UTC)


 * This symposium on dust explosions says that steel friction sparks are a higher temperature than steel grinding sparks. They explain that this is due to the higher starting temperature of the steel when friction generated.  This leads me to think that thermal conductivity has a lot to do with this - in aluminium it is orders of magnitude higher than in steel.  Spinning  Spark  12:39, 23 July 2013 (UTC)
 * Yep, this book confirms it.  Spinning Spark  12:48, 23 July 2013 (UTC)

Is each transmitter restricted to a specific frequency?
Is it possible for the transmitter in a phone intended for use on 900 Mhz and 1800 Mhz networks to transmit at 446.00625 Mhz and therefore be used as a walkie-talkie (e.g. outside the range of cell towers) or is the frequency a function of some physical property of the transmitter? --78.150.16.133 (talk) 12:54, 23 July 2013 (UTC)
 * What ever makes you think that it would? That frequency is not even between the two phone bands.  Even if it were, the radio front end of the phone will not cover the whole 900-1800 MHz band.  Essentially, you would have to gut the phone and rebuild it to get this to work.  Even then, you probably could not get the electronics to fit into the space, a one-off prototype is never going to have the advantages of the integrated electronics of a mass-produced item.  Spinning  Spark  13:13, 23 July 2013 (UTC)


 * Not only would the electronics not be able to send and receive at 446.00625 MHz, the modulation for a cell phone to communicate with a cell tower is entirely different from the modulation alternatives for the Private Mobile Radio service in Europe (see our article PMR446). Jc3s5h (talk) 14:45, 23 July 2013 (UTC)
 * The easiest way to do this would be to take the signal from the antenna of your mobile and shift that in frequency (by amplifying it with a carrier wave at frequency f, you shift the frequency up and down by f). Count Iblis (talk) 14:33, 23 July 2013 (UTC)
 * That is neither easy, nor an answer to the question. Furthermore, it is completely wrong.  A digital phone signal frequency shifted on to an analogue FM walkie-talkie would sound like garbage rather than intelligible human speech.  Spinning  Spark  14:47, 23 July 2013 (UTC)


 * Not to mention all of the layers of software protocol, frequency-hopping, tower-reassignment and who-knows-what else that would have to be somehow handled. There are phones out there that are designed to be used as walkie-talkies - but converting a regular cellphone to do that entails a LOT more than just changing the transmitter frequency.  Because cellphones now also have bluetooth, WiFi and such like - there are also other ways to do short range communication without using the cell towers.  For example, some phones can be made to operate as WiFi hubs with the installation of a simple app.  It wouldn't be hard to provide voice communication over local WiFi connections that would function like a walkietalkie - but with more security, digital audio quality and so forth...providing you don't need to talk over more than a hundred feet or so. SteveBaker (talk) 15:11, 23 July 2013 (UTC)


 * PMR446 walkie-talkies are so cheap nowadays that the solution is always going to be "buy a walkie-talkie" unless you have a very special application and government funding.  Spinning Spark  16:28, 23 July 2013 (UTC)

The TETRA mobile radio standard provides for handsets that can communicate through the network of base stations when in range  and  in direct transceiver mode when outside the network. It is being widely implemented for emergency services. Modifying a handset made for a commercial standard such as GSM to work on TETRA is not practical because the changes involved go far beyond retuning a frequency. The only way to make a pair of GSM 900/1800MHz handsets seem to work as transceivers disjoint from the national network would be to set up one's own base station. That action would invite the legal consequences of unauthorised radio pollution so the joy might be intense, brief and end in tears. DreadRed (talk) 19:18, 23 July 2013 (UTC)


 * A fully Software-defined radio should in theory be able to send and receive any signal under its Nyquist–Shannon sampling theorem limit, given sufficient processing power and antenna attenuation. Hcobb (talk) 03:33, 24 July 2013 (UTC)
 * Yes, but a mobile phone aint one of those, and even if it were, paying someone to completely rewrite the DSP would be so far from cost-effective as to be a joke. Not sure what you mean be "sufficient antenna attenuation".  I would state it as using the device well outside the design wavelength would result in abysmal performance, and at some frequencies, no performance at all.  Spinning  Spark  12:02, 24 July 2013 (UTC)

Side effects
WHY do drugs (medicines) have side effects? What decides whether you GET a side effect, e.g. akathisia? I ask because you don't always get the side effects, like akathisia. The question applies to the whole world. Why can't we make drugs WITHOUT side effects? Pubserv (talk) 19:37, 23 July 2013 (UTC)


 * There fundamentally is no such thing as "side" effect. Drugs have various effects, it's only our distinction between good and bad that gets any labelled "side". The strength of these effects is dependent on particular body chemistry, diet, dosage, temperature, and other factors. Sometimes a person will get every bad effect and none of the good, or vice versa. Thankfully, most of us are closer to the middle (though you only ever need one "sudden death" effect to cancel out the rest). InedibleHulk (talk) 20:16, 23 July 2013 (UTC)


 * "Sometimes a person will get every bad effect and none of the good," That's what's happening to me. It's ruining my life (sorry, off-topic). Pubserv (talk) 18:37, 24 July 2013 (UTC)


 * Some "side effects" are actually beneficial, leading to off-label usages, or perhaps even replacing the original usage. Thalidomide, for example, is not a very good choice to help pregnant women with nausea symptoms, but not a bad choice for fighting cancer tumors in those who aren't pregnant. StuRat (talk) 22:01, 23 July 2013 (UTC)


 * Quite possibly the most popular (and lucrative) side effect is the one caused by a particular angina medication often sold in the form of little blue pills. Matt Deres (talk) 02:25, 24 July 2013 (UTC)


 * I'm guessing the researcher misheard his neighbor when he said he needed something to make his wife's angina feel better. :-) StuRat (talk) 02:30, 24 July 2013 (UTC)


 * (ec) See side effect. Basically, medicine doesn't know where to go, so if you swallow a pill, the contents end up everywhere. IBE (talk) 20:18, 23 July 2013 (UTC)


 * Yes, and more localized meds, like topically applied acne meds, are often the better choice, for this reason. Or, even better, fix the problem with diet and exercise, wherever possible. StuRat (talk) 22:04, 23 July 2013 (UTC)


 * Part of the reason for the rise of surprising effects is the general rise of new medicine. Clinical testing on small samples of people can only determine so much. Wider testing in a real environment is necessary before we can be sure which drugs tend to do what to most people. I believe it's ten years of testing after release before a drug can be officially deemed "safe" or "unsafe" in the US ( I'll look for a source Not sure if the "officially deemed" part is true, but it's longer than ten years. In a way, Phase IV trials never end). Think of all the new pills they've pushed out in the last decade, and of all the different kinds of people you know. That's enough chance on it's own, but when you consider that many people are on several iffy medicines at once, combinations can cause even more unforeseen effects.


 * It's really hard to know just what will happen, even if you take as directed. InedibleHulk (talk) 20:28, 23 July 2013 (UTC)


 * This is comedically toned and may contain offensive language, but worth a read. If you learn something and enjoy it, you might try this and this, too. InedibleHulk (talk) 20:38, 23 July 2013 (UTC)


 * 25 years ago I could easily buy pseudoephedrine to relieve the symptoms of a cold. As a middle distance fun runner I found it had the quite beneficial side effect of allowing me to run faster than normal, even though I was sick. Soon afterwards, the sports drug people banned it. Now it's banned because it's a precursor drug to methamphetamine. What a sad history it's had. HiLo48 (talk) 22:54, 23 July 2013 (UTC)


 * Our article only mentions Columbia and Mexico as places where it is illegal. Are there others? Rmhermen (talk) 00:18, 24 July 2013 (UTC)


 * It has become incredibly hard to get in Australia. Used to be something I could pick off the shelf at the pharmacy (drug store) and just take to the cash register, but now one has to present a case to the pharmacist, which may be rejected, and when you're crook with a cold you're not always good at such things anyway. Some pharmacies don't stock it at all because of the record keeping hassles, and the increased chance of being robbed. Then you have to show ID to prove who you are. All a big hassle. It's also illegal to privately import it. HiLo48 (talk) 01:07, 24 July 2013 (UTC)


 * I was hospitalized regularly as a child for allergy related complications, had tubes put in my ears for drainage (one of my oldest memories), probably sneezed once every 15 minutes while awake for 10 years as a child, until I was prescribed bromfed, which I could take once a day (some times five times a week, max), twice-a-day during allergy season, and be symptom free. It was a miracle, I swore by it.  They took it off the market about two years ago from fear it would be used to cook meth.  Now I can take benadryl 25mg, but have had to take as many as 24 a day (with doctor approval, believe it or not), and prefer hydroxyzine, a first-generation antihistamine that causes drowsiness and is now mostly prescribed off-use as a sedative (!), but I need take no more than 4 a day of it.  Bromfed is still legal in a liquid cough formulation, but is not for long term use. μηδείς (talk) 00:38, 24 July 2013 (UTC)


 * You might want to look at lock and key theory. Chemicals have shapes and local charges and how they interact depends on how these match up.  If chemical (molecule) A fits with chemical (molcule) B and solves a problem it may very well fit with Chemical (molecule) C enough to cause another problem. μηδείς (talk) 23:58, 23 July 2013 (UTC)

Why can't we make drugs WITHOUT side effects? Pubserv (talk) 18:15, 29 July 2013 (UTC)