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September 23

Biology - Genus: Hepatocystis - conflict - Who described it?

Article Hepatocystis mentioned 'Miller 1908' was the first to describe the genus. According to Taxonomicon the genus Hepatozoon was described by Miller 1908, not Hepatocystis. Unfortunately I can't verify the information in Taxonomicon from a second source. Who could verify it and - if necessary - edit the article? -- from de.wikipedia.org Temdor (talk) 00:33, 23 September 2013 (UTC)[reply]

What does the letter V of ECG stand for?

In ECG there is 12 leads, every one of them called V. In example V1 and V2 and V3 and so on... so, what does the letter V stand for? Thank you 95.35.220.182 (talk) 08:43, 23 September 2013 (UTC)[reply]

I always assumed it was for "Voltage" as these are points at which electric potential difference (voltage) is measured. This is just an assumption though. -- Q Chris (talk) 08:57, 23 September 2013 (UTC)[reply]

The 6 "V" leads are the precordial or "chest leads" (the other leads go on the arms or legs), and they get numbered from 1 to 6 as they are placed across the chest from right to left. ~~I'm not certain why the chest leads are designated with "V", but perhaps it's from "ventrum", the Latin for chest.~~ Actually, the "V" does stand for voltage: The use of chest leads was first described in 1932: Wolferth CC, Wood FC. The electrocardiographic diagnosis of coronary occlusion by the use of chest leads. Am J Med Sci 1932;183:30-35, and the positions were standardized in 1938: Barnes AR, Pardee HEB, White PD. et al. Standardization of precordial leads. Am Heart J 1938;15:235-239. It's in this latter paper that we can find that the "V" stands for voltage. - Nunh-huh 09:45, 23 September 2013 (UTC)[reply]

Thank you a lot for the help! 95.35.220.182 (talk) 10:45, 23 September 2013 (UTC)[reply]

article of CC

I'm looking for the article for the question what does the letters CC of measurement stand for? I mean about 1CC of medicine for example. 95.35.220.182 (talk) 11:34, 23 September 2013 (UTC)[reply]

cubic centimeter. -- Staecker (talk) 11:37, 23 September 2013 (UTC)[reply]

Yes, and it is equivalent to 1 ml. 1 table spoon is roughly 14.8 cc. Dauto (talk) 13:52, 23 September 2013 (UTC)[reply]

In the metric system, a tablespoon as a measure is generally considered exactly 15 ml, by definition, just as a teaspoon is considered 5 ml. I assume the weird stuff where tablespoons and teaspoons are considered non-integer numbers of ml are due to some conversion from american units of measure? 86.164.30.45 (talk) 20:46, 23 September 2013 (UTC)[reply]

Ah, I see from our article that the US considers a tablespoon to be 1/2 fl oz, which is then converted to 14.8 ml. So a standard US tablespoon measure is very slightly smaller than a standard metric tablespoon measure. Still, if you're going to say 'roughly', why not give a round integer? 86.164.30.45 (talk) 20:50, 23 September 2013 (UTC)[reply]

I guess I'm not that rough? :-)

Garden Spider doing a spot of trawling?

So i'm in Britain and i've got some Zantedeschia aethiopica (Calla Lillies) sitting outside in a pot inside a washing up bowl. This washing up bowl has a few inches of water in and has many what i assume to be Mosquito larvae swimming round the water inside.

I have noticed that there is what i believe to be a rather large European Garden spider sitting on the water with its mouth submerged (and mouth-pincers(?) moving) and it seems to be slowly moving around the bowl.

What i'm wondering is, is it hunting and also is this usual behaviour? I've also noticed a small clump of soil attached to one of its rear legs and was wondering if it is possible for it to use its web to trawl like a fishing vessel?

I've considered the possibility that it is stuck but it seems to be rather happy on the water surface tension and looks large enough to pull itself out. (Cesdeva (talk) 12:04, 23 September 2013 (UTC))[reply]

Depends on the size of the spider, but Raft spiders are semi-aquatic and may exhibit such behaviour. (I don't want to look...) --TammyMoet (talk) 13:32, 23 September 2013 (UTC)[reply]

I think you're right. After re-observing, the Spider does look more like it resembles those species within Dolomedes. Now to find out which one... (Cesdeva (talk) 13:53, 23 September 2013 (UTC))[reply]

Dehumidifiers >100% efficient have a COP > 1 as heaters.

I read on a forum comment that dehumidifiers have a secondary effect of warming the room, and the amount of heat added to the air is more than 100% of the energy consumed (COP > 1). The reason given was that the latent energy from the water vapour is also emitted into the room. The system was likened to a giant heat pump where the dehumidifier takes the place of the compression side and the sun on the oceans as the evaporator?

Is this correct? If so what percentage extra heating would you get, is it significant or marginal? -- Q Chris (talk) 12:08, 23 September 2013 (UTC)[reply]

Note as our article mentions (Heat pump#Efficiency), the word 'efficiency' is generally avoided when talking about such things as efficiency is generally taken to a have a specific thermodynamic definition, instead the Coefficient of performance is normally discussed. Nil Einne (talk) 13:04, 23 September 2013 (UTC)[reply]

Noted, I have corrected the question -- Q Chris (talk) 13:31, 23 September 2013 (UTC)[reply]

It will generate more heat than the electricity it consumes (by a very tiny amount) only until the room is as dry as it can make it be. At that point, it'll be no more than 100% efficient. You might argue that you can put some water in the room to evaporate and replenish the humidity - but that evaporation would cool the room by exactly as much as the humidifier is more than 100% efficient...so the net benefit in terms of heating drops to zero. SteveBaker (talk) 14:15, 23 September 2013 (UTC)[reply]

At a practical level, the most common way of dehumidifying air is to use an air conditioner, which causes water vapor to condense on the chilling elements. Air conditioners obviously don't warm a room -- rather the dehumidifying effect shows up as a reduction in cooling efficacy. Looie496 (talk) 14:37, 23 September 2013 (UTC)[reply]
But they do heat the outside. If you kept the condenser of the AC unit inside the room with you, and then just drained the water outside, you'd have a dehumidifier that heated the room rather than cooled it. --Jayron32 14:47, 23 September 2013 (UTC)[reply]

To actually answer the question asked this (possibly unreliable bloggy) page [1] say they achieved a COP of 1.52, ie 52% increase. This [2] more scientific investigation achieved latent COPs up to about 0.38, ie a 38% improvement, depending on the exact setup. I extracted this data from the graphs at the end of the paper. Latent COP represents only the latent heat of condensation, 1.0 has to be added to this to get the total COP assuming all the power going into the dehumidifier unit ends up as heat in hte room. Spinning Spark 17:37, 23 September 2013 (UTC)[reply]

Microwave attacks?

When I was at grammar school in the '60', there was a girl in my class with a birth deformity, which impaired her walking. She was the daughter of diplomats who had been located in Moscow, prior to her birth. There was talk at the time that the Russians were bombarding diplomatic staff with microwaves. Was this ever proved, and have there been instances since of people being damaged by microwave or other forms of electromagnetic or focused radiation? — Preceding unsigned comment added by 31.25.4.14 (talk) 13:20, 23 September 2013 (UTC)[reply]

People have certainly been killed accidentally by microwaves, but it's unlikely that they would cause birth defects. Generally speaking it takes ionizing radiation to do that -- microwave photons don't have enough energy to break apart a DNA molecule. Looie496 (talk) 14:32, 23 September 2013 (UTC)[reply]

Articles such as this one suggest that the microwave bombardment of the embassy building was done from the late 1950's all the way into the early 1970's. The girl you knew must have been between 11 years old and 17 years (because she was "at grammar school") and you say it was "in the 1960's" - which means that she was conceived sometime between 1943 (17 years old in 1960) and 1958 (11 years old in 1969). We know (eg from this) that the radiation started around 1956 or 57. So if you knew her in your first year at grammar school and it was the late 1960's - then it's just about numerically possible that she was irradiated before birth. Mostly, that seems to have caused cancers in the embassy staff at some unreasonably high rates. The daughter of Franz Misch (who was born in 1968) seems to have suffered mental defects - which might be attributable to the microwave bombardment - and if it was indeed the cause of that - then other deformities are certainly possible.

It would help to know what year you were born (because this girl was in your class - and therefore, presumably, within a year or so of your age) - that would tell us whether she was conceived before all of the microwave business started - which would efficiently disprove your theory.

Obviously there is no possible way to prove it. Children are born with deformities all the time - and microwave bombardment isn't often the cause - so even if she was there during the worst of the attacks, the microwaves might still have had no effect on her.

SteveBaker (talk) 14:35, 23 September 2013 (UTC)[reply]

Hmmmm - further down this article, it says: "It turned out that the Soviets had been bombarding us with microwaves, beginning in about 1964 or 1965." - which would totally bust this theory since the girl would have had to be at least 5 years old when the attack started. However, the first reference I found said: "Two retired US Secret service agents who accompanied then Vice-President Richard Nixon to Moscow in 1959 said in 1976 that the embassy was bombarded with such heavy radiation that one radiation detection device was damaged". That report seems a bit suspect to me - I mean, what kind of radiation detector would be damaged in that way? Also, if they had detectors installed in 1959, then you'd presume that the bombardment must have gone on for a while before the attack was noticed and the detectors had to be installed. Then this says that "Washington had known what was going on since the 1960's" - which doesn't fit with a destroyed radiation detector in 1959. Then this says that "US officials noticed that the Soviets had begun directing microwaves at the embassy in 1962, perhaps starting as early as 1953"...so that also confirms that the radiation detector couldn't have been destroyed in 1959 - but throws this new curve ball in by saying it might have started MUCH earlier.

So I guess the start date is a bit "fuzzy". SteveBaker (talk) 15:00, 23 September 2013 (UTC)[reply]

And more...this suggests that the microwave bombardment was actually a kind of power source for their system of hidden microphones in the embassy...interesting! SteveBaker (talk) 15:22, 23 September 2013 (UTC)[reply]

Indeed sources say it was Steve. See Thing (listening device) (unless that's where you got your spybusters source?) -∇-220 of ^Borg 17:10, 23 September 2013 (UTC)[reply]

Who'da thunk the Soviets were such evil bastards? In any case, Looie496's got it right. Microwaves cause heating, not mutations. The Soviets might as well have been pricking voodoo dolls. μηδείς (talk) 15:36, 23 September 2013 (UTC)[reply]

In 1971 the Australian magazine Electronics Today published a full technical explanation, with diagrams and a photo, of the Soviet seal microwave eavsdropping system. Based on the operating principle (passive detection & re-radistion) and the distances involved, only around a few watts from the microwave source are required. Nobody would be hurt by that. 120.145.70.130 (talk) 15:43, 23 September 2013 (UTC)[reply]

Could that be in the public domain by now? Though the sources for the on-line explanations are probably the same as ETIs'. -√- 220 of ^Borg 17:10, 23 September 2013 (UTC)[reply]

See "Kvikk case" and "Radium Girls" and "SCOJ 2005 No.1977" and "Vatican Radio lawsuit".

—Wavelength (talk) 16:49, 23 September 2013 (UTC)[reply]

A more directly relevant article is the Great Seal bug. Spinning Spark 17:08, 23 September 2013 (UTC)[reply]

There are a large number of publications on PubMed about microwaves (and terahertz radiation, which was not considered a separate category until recently) and DNA. However, there has not been any finding of teratogenesis in experiments. [3] The caveat there, however, is that experiments with broad-band emissions may not cover the field, because there have been specific, frequency-specific interactions observed in terahertz, to the extent that they are under study for things like identifying pathogenic bacteria in environmental samples. The idea encounters considerable skepticism because these photons do not carry the energy to physically break chemical bonds in DNA - they would have to work by vibrating the strands somehow and shaking loose interacting proteins, etc. But I am not convinced such a thing does not occur. Wnt (talk) 18:33, 23 September 2013 (UTC)[reply]

Of course, it is also possible that her mother suffered mutation due to increased cosmic ray radiation during repeated air travel. Wnt (talk) 18:34, 23 September 2013 (UTC)[reply]

It might also be the father. The Kvikk case suggests that damage to the father's sperm can cause club-foot - which is exactly the kind of thing that our OP could have seen in this girl. SteveBaker (talk) 19:11, 23 September 2013 (UTC)[reply]

You're absolutely right -- sorry, "mother" was a stupid thing to say. Actually, fathers are if anything more prone to mutations in specific genes as the result of aging and background radiation, whereas mothers are a bit more prone to pick up large-scale chromosomal aberrations. Wnt (talk) 04:16, 24 September 2013 (UTC)[reply]

So if "The Thing" (aka "The Great Seal Bug") was being illuminated at 330MHz - that's only just barely into the microwave part of the spectrum (normally defined as 300Mhz to 300GHz)...it's going to behave more like low frequency radio wave. It's hard to imagine how that could hurt anyone. For sure, the one documented case of birth defects in embassy staff's children could have been a completely unrelated fluke. But what about the increased cases of cancer?

It would *REALLY* help if our OP could tell us his/her age so we can narrow down the likely range of dates over which this girl would have been exposed to this radiation in the womb. SteveBaker (talk) 19:02, 23 September 2013 (UTC)[reply]

Our article may be wrong about the frequency. The source Steve found earlier [4], which seems quite knowledgeable, disputes the assesment of the antenna as a quarter-wave and says it is more likely a half-wave monopole. They, and other sources, put the frequency of operation at 1.1 GHz. Quarter-wave monopoles do not work very well without a ground plane to create an image and this was absent here. It is significant in this respect that later American versions of this device used a quarter-wave dipole. Also, the cavity shown on the diagram (0.775" dia) seems much too small to resonate at 330 MHz. Spinning Spark 19:52, 23 September 2013 (UTC)[reply]

A retrospective cohort study of embassy personnel found no adverse health effects of the radiation. A 2012 review of this study (http://www.ehjournal.net/content/11/1/85) concludes: "The conclusions of the original report are supported. Contrary conclusions given in some other reports are due to misinterpretation of the results."

Seems that "an opinion piece, not an intended to be a balanced presentation of the literature" by John Goldsmith got more attention than the mentioned study. Ssscienccce (talk) 11:41, 24 September 2013 (UTC)[reply]

There are a couple things I want to contribute. In the 50s & 60s perhaps, the American Embassy in Moscow was driving a station wagon around Moscow streets. It was large and the body was made out of wood. It certainly stood out of other (Russian) cars. The KGB puzzled for a while until they figured out what was going on. The car had hidden microwave detectors inside. They were mapping the Soviet Defense Industry. Radiation of every kind was a hot topic those days.

Aside from microwave there might be another potential source of birth defects in Moscow. They still have so called Kurchatov's Institute where Igor Kurchatov and Alexander Sakharov made the atomic and hydrogen bombs. There was a malfunction there in the 50s resulting in radiation contamination of a large district in Moscow. I don't know how far Kurchatov's Institute is from the American Embassy but can find out.

- Alex174.52.14.15 (talk) 01:28, 25 September 2013 (UTC)[reply]

Your replies are engrossing. The girl would have been born between 1951-1953. And I think she had a club foot. So your replies are suggestive but not conclusive. Thanks.31.25.4.14 (talk) 09:24, 27 September 2013 (UTC)[reply]

...and that's the best you can possibly get. A "conclusive" determination is impossible because that condition happens "naturally" to about one in a thousand children. So even if you knew for 100% certain that she was exposed to some hypothetical kind of radiation that is known to cause club foot in 99% of those exposed, then there was still a chance that she was one of the lucky 1% who was not affected by the radiation - but on of the unlucky 0.1% who got the condition "naturally".

But I think the issue here is that microwaves are not known to cause this problem - and the rash of club-footed children in the Kvikk case is of uncertain cause. So while there is reasonable grounds to suspect that her condition could be blamed on the Russians, it's far from certain that this is anything other than a random birth defect.

Consider the theory that someone posted above. The father was on the embassy staff during one of the busiest times in history for a US diplomat - and therefore probably spent a lot of time flying back and forth across the Atlantic in high altitude airplanes. He'd be getting repeated doses of X-rays to the testicles. One transatlantic flight gets you a dose of 0.07 mSv. Compare that to 0.02 mSv (a chest X-ray on a modern machine) or 0.18 mSv (the maximum that a Nuclear power worker is allowed to incur in an entire year).

SteveBaker (talk) 15:10, 27 September 2013 (UTC)[reply]

Surgical treatments for Tibialis (Anterior) Tendinitis?

How could Surgery help to solve such a problem? interesting, Thanks. Ben-Natan (talk) 16:34, 23 September 2013 (UTC)[reply]

? Ben-Natan (talk) 19:17, 25 September 2013 (UTC)[reply]

Donate my personal data to science

I know I can donate my body to science when I die, but I'd also like to donate my personal data, from my DNA to my Gmail and Facebook archives, so that even my weaknesses and failures will ultimately contribute something to society. Is there a way to do this? I have Asperger Syndrome and other reasons to suspect I may be of interest as a case study. Neon Merlin 17:47, 23 September 2013 (UTC)[reply]

What scientists are currently doing that research? Is there a presumed religious freedom to have that information destroyed as a funerary right, many ancient religions believed belongings had to follow to the world of the dead. — Preceding unsigned comment added by CensoredScribe (talk • contribs) 19:15, 23 September 2013 (UTC)[reply]

And why do you need to wait until you die to do it? Data is easy enough to copy - and if some kind of research did need it, there would be much greater worth if they could come back and ask you questions about it. I guess the key question here is whether Asperger researchers are lacking data of this sort. I rather suspect that they aren't - or we aspies (yes, me too!) would be being asked for it...and I see no sign of that happening. Anyway - there is a list of Asperger research groups here - I suggest you try to contact them to see how you can help. SteveBaker (talk) 20:47, 23 September 2013 (UTC)[reply]

Your Gmail and Facebook archives are not your personal data. The people you corresponded with presumably assumed the conversation would be kept private, since they never gave you permission to disclose it. Donating the data to science would violate their right to privacy. --128.112.25.104 (talk) 20:42, 23 September 2013 (UTC)[reply]

In American law you own the copyright to letters you send, but not the letters you receive. For example, one can publish one's own collected letters, but can reproduce letters from others in that collection only with permission. μηδείς (talk) 21:02, 23 September 2013 (UTC)[reply]

No need to donate, it's already being used. Count Iblis (talk) 00:16, 24 September 2013 (UTC)[reply]

Omg! "Your Data: If You Have Nothing to Hide, You Have Nothing to Fear". Sounds familiar! :-/ -ʊ-220 of ^Borg

Count Iblis's website link is a joke/satire website. The correct link to the NSA's website is https://www.nsa.gov and their statement on the recent issue, available online, largely seeks to correct several mischaracterizations of their activity. Nimur (talk) 09:02, 24 September 2013 (UTC)[reply]

And what makes you think that the NSA is telling the truth, and the whole truth? I understand that their activities imply keeping things under wraps. (although I don't believe they go through most communications, and I worry more about private companies accessing my data than governmental agencies which could subpoena it anyway). OsmanRF34 (talk) 14:07, 24 September 2013 (UTC)[reply]

Because all activities conducted by the National Security Agency are directly accountable to its administrator, and to the Executive and to Congress; not to mention the United States Supreme Court; and after extensively reading about the involved issues - from other sources I trust, including the Senate committee and House committee, and statements provided directly from our Executive, I have decided for myself that I have high confidence that our form of government is able to adequately provide checks and balances, even in situations when confidential material cannot be disclosed to the entire public. I respect that other people may disagree with that position. I also believe that most other people have not chosen to inform themselves about these issues in great depth. Nimur (talk) 14:28, 24 September 2013 (UTC)[reply]

Yeah, that's what they want you to believe. I suppose any descent conspiracy theory will dismiss your evidence, but yes, it seems compelling to me. As said above, I worry more about private companies trying to get hold of my data (maybe to improve their credit ratings, or vet my employability?). And I wonder how could I have the same privacy through email that I have through letters (specially considering that the other side would also need some form of encryption, which many are unwilling or unable to implement).OsmanRF34 (talk) 14:49, 24 September 2013 (UTC)[reply]

But is NeonMerlin even in the US or US citizens? They didn't say so in their post and their user page is unclear to me although referring to themselves as a university student seems something less likely for someone from the US to say. The statement you linked to mostly talks about protetions for US citizens and those living in the US. It's great that you living in the US as a US citizen can trust the NSA to protect your rights given the checks and balances, but this may be cold comfort to someone who is not in the US nor a US citizen, who may still have legitimate questions over where this leaves them even if they are not particularly hostile to the US or engaged in any extreme activities, particularly considering there is strong evidence that being a close ally may not be enough to protect you (which isn't particularly surprising). Really the only thing going for NeonMerlin is that despite some ridiculious figures banded around, whatever they do, and with no disrespect, it's likely to be so insignificant that it will never get any specific attention (not so much because the US wants to protect their rights but because the cost would be astronomical). Nil Einne (talk) 15:56, 24 September 2013 (UTC)[reply]

Too bad this xkcd came out after this discussion "Privacy Opinions"--220 of ^Borg 09:13, 2 October 2013 (UTC)[reply]

Do cats despise potential energy?

Why do cats do things like this? I've known many cat owners and many have reported similar things. My own cats do this as well. A small item like a pen will be sitting on a table minding its own business when a cat will come along to knock it off the table for what seems like no reason. I've even seen one of my cats get up onto a shelf with what appeared to be the sole purpose of knocking each and every item off the shelf. Is there a scientific reason for this? Dismas|^(talk) 20:24, 23 September 2013 (UTC)[reply]

I don't think their goal is to knock the items down. Exploring an item involves batting it around, and if it's on a shelf, this results in it falling off the shelf. I'd expect similar behavior from a baby. Both also might put the item in question in their mouth to explore it. An adult human might pick the item up, turn it around, then put it back where it was, but cats and babies lack the coordination/fingers to do this.

In the case of the shelf, though, they might want the junk off the shelf so they can sleep there. I've found many cats like high spots, for the better view. They also know they won't be stepped on there. StuRat (talk) 20:47, 23 September 2013 (UTC)[reply]

I am fairly certain the appropriate concept here is not entropy, but evil. You don't find dogs doing this stuff. μηδείς (talk) 20:57, 23 September 2013 (UTC)[reply]

True, but dogs in turn tear things to pieces. At least for cats that knock things off high places, some things are salvageable. Plasmic Physics (talk) 21:44, 23 September 2013 (UTC)[reply]

Tearing things to pieces is a stage with some puppies, and not usual in most dogs. Don't all cats engage in the knocking things down behavior? μηδείς (talk) 02:20, 24 September 2013 (UTC)[reply]

Indeed. I have 5 dogs currently and only one of them finds quite a bit of enjoyment in chewing up rawhides. Three of them nibble on them occasionally. And the last has no interest, though it might have something to do with his advanced age. I have 7 cats as well and I have observed most of them knocking things off tables (mostly pens). Dismas|^(talk) 06:50, 24 September 2013 (UTC)[reply]

My cat has never done any knocking things off of anywhere, nor has it jumped onto any furniture that we didn't teach it to, ever. Plasmic Physics (talk) 10:01, 24 September 2013 (UTC)[reply]

"Ever." As far as you know. ←Baseball Bugs ^{What's up, Doc?} carrots→ 12:52, 24 September 2013 (UTC)[reply]

Do what, Dismas? Can you provide a link that doesn't require us to log in to imgur? Astronaut (talk) 15:26, 24 September 2013 (UTC)[reply]

Bah! Sorry, Astronaut. Thought I grabbed the universal link. I've changed the link to one that doesn't require login. Apologies, Dismas|^(talk) 16:23, 24 September 2013 (UTC)[reply]

I love the concept of cats despising potential energy. Dogs with big tails, in particular Labs, seem to have the same characteristic, though they try to pretend it's accidental. --jpgordon^{::==( o )} 16:42, 25 September 2013 (UTC)[reply]

Why does the USA use odd tenths of a Mhz for FM radio?

I noticed that while the United States has radio stations like 99.1, 104.3 and 107.7, in Indonesia and Greece, the same FM band uses stations like 102.6. When was it determined that the USA should use odd tenths and is there any particular reason why? (I flipped a coin in determining whether to post this here or the Entertainment refdesk)Naraht (talk) 23:48, 23 September 2013 (UTC)[reply]

It seems to have been an arbitrary choice, as explained here by the FCC. See also FM broadcasting in the United States, based on the lowest frequency a station could use and the bandwidth of each possible channel. Other countries just made a different arbitrary choice or had a different starting frequency With old radios having analog tuning there was no problem going from Europe to the US, but some modern digital radios don't work equally well with both frequency assignment systems. See [5]. Edison (talk) 00:22, 24 September 2013 (UTC)[reply]

Of course the FCC site says that the bottom end of the broadcast spectrum is 88.1 and Wikipedia says that there are two stations broadcasting on 87.9, sigh...Naraht (talk)

Years ago I heard that the FCC uses the odd decimals to make everyone have a "point something". So it would be 97.1 instead of 97. I don't know if that is correct. Bubba73 ^{You talkin' to me?} 02:34, 24 September 2013 (UTC)[reply]

The FM broadcast band in the US is 88 MHz to 108 MHz and the channel spacing is 200 kHz. As mentioned already, these are arbitrary choices, but given these numbers, it is a simple mathematical consequence that the centre frequencies are an odd decimal. Stations which have overlapping coverage areas, however, are separated by at least 400 kHz. In the UK the radio environment is quite different: there are a lot of stations in an overcrowded space and several nationwide stations broadcasting from multiple sites. Two transmitters with overlapping areas are sometimes spaced at 300 kHz, especially when they are carrying the same nationwide programme.[6] Obviously, one or the other of them must then be on an even decimal centre frequency. The situation in Greece (see List of radio stations in Greece) seems best to be described as anarchy with the regulation system having semi-broken down. I don't know anything about Indonesia but I would guess the reasons for the mix are similar either to UK or Greece or both. [7] says that the Indonesian FM band starts at 87.5 MHz which would naturally lead to even decimal centre frequencies at 200 kHz spacing. List of radio stations in Jakarta, for instance, shows a lot (but by no means all) of stations on even decimals. Spinning Spark 14:46, 24 September 2013 (UTC)[reply]

The job of allocating frequncies for broadcast stations is actually quite complicated - more so for AM, where the ground wave may travell 2000 km or more, and there is no "capture effect" (FM receivers have capture effect - a strong signal will render a weak signal on the same frequency inaudible. With AM, the weak station will be audible at low volume), but even for FM it is quite complicated. Here's the basics: 1) stations serving a given city should have widely spaced frequencies to make selection and tuning easy. But not too far apart, or the stations near the edges of the band will be upset as they won't capture listeners tuning between stations. We have some community stations near the top of the band - around 107 to 108 MHz. Hardly anyone knows they are there as all the big name commercial stations are around 94 to 96 MHz. 2) Due to how radios work, downconverting the signal to 10.7 MHz for amplification, two stations separated by 10.7 MHz will together interfere with all other stations in the area. This is due to what is known as cross-modulation in the input circuitry of recievers. 3) Stations that are a multiple of an analog TV channel vision frequency, TV sound frequency, or a multiple of the TV vision/sound separation are at a dissadvantage (in USA and other countries that used NTSC, multiples of 4.5 MHz, making FM channels 90.0, 94.5 MHz, 99.0 MHz, 103.5 MHz bad choices, in standard PAL countries, multiples of 5.5 MHz, ie FM channel 93.5 MHz, 99.0 MHz, 104.5 MHz bad choices, in Britain with unstandard PAL, multiples of 6.5 MHz, making FM channels 91.0 MHz, 97.5 MHz, 104.0 MHz bad choices.) In theory, these issues would not apply if everyone had well designed receivers. An the demise of analog TV has changed things. However, the allocation rules were determined years ago and allow for some people having very cheap poorly performing radios. — Preceding unsigned comment added by 1.122.206.159 (talk) 03:53, 25 September 2013 (UTC)[reply]

Actually the superheterodyne technique of an oscillator running at 10.7 MHz higher than the tuning station makes cheap high quality radios compared to AM. --DHeyward (talk) 04:06, 27 September 2013 (UTC)[reply]

Well, no, because the superheterodyne technique is used for AM radios as well, with the oscillator running 455 kHz (some radios differ slightly, American car radios made up to the 1950's used a 262 kHz oscillator offset, many radios prior to the 1930's used a 175 kHz offset.) The percieved high quality of FM comes from the wide bandwidth more easy to provide on VHF frequencies. However the same bandwidth and quality is possible with AM. The frequencies used for AM are more subject to interference though. 121.215.63.7 (talk) 10:34, 27 September 2013 (UTC)[reply]