Wikipedia:Reference desk/Archives/Science/2011 April 26

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April 26

Application of brain lateralization to UI design?

The article Lateralization of brain function doesn't discuss the phenomenon's applications. This article claims that gamers should place UI elements that they respond to with the right hand on the right side of the screen, and those that they respond to with the left hand on the left side, to shorten reaction time. Do any ergonomic studies support this claim? Is it possible that a gamer might be able to process some elements of the game state faster in one lobe than the other? NeonMerlin 00:43, 26 April 2011 (UTC)

A lot of "left-brain" and "right-brain" theory was never founded on scientific experiment, and most of it has been pretty thoroughly discredited. What we're left with is a much more vague, but much more believable, theory of functional specialization (brain). It may take decades for "pop psychology" to let the numerous invalid ideas go to rest, though. There is very little actual evidence to suggest, for example, that the "left side" of the brain is more suited to (or more active during) quantitative or numeric cognitive activity. Nimur (talk) 00:50, 26 April 2011 (UTC)

That's all true, but there is some pretty solid evidence that simple visuomotor reactions are faster when they use the hand on the same side as the stimulus (for example PMID 7128169). It is much less clear what happens when the stimuli are more complex or require sophisticated decision-making. From an anatomical point of view, the brain is wired such that the visual input from the right side of the world goes to the hemisphere that controls the right hand, and the left side matches with the left hand, so the basis for such an effect is certainly there. Looie496 (talk) 01:28, 26 April 2011 (UTC)

How to save generic annotated DNA sequences?

There is a sequence here in a generic form with annotations. How do I save it so that I can open it in a capable program which will feature the described annotations? Thanks. --129.215.47.59 (talk) 14:24, 26 April 2011 (UTC)

Can you be more specific about what you want to ultimately be able to do with the sequence? The "capable program" you choose (and there are lots of options) is going to depend on your application, and each program probably has a different input format. If you already have a program you want to use, then there should be some kind of FAQ or user guide that describes the required input. If you haven't already selected a program, then the question you really want to ask is "what program should I use to accomplish X". --- Medical geneticist (talk) 15:01, 26 April 2011 (UTC)

Hi. Thanks for your response. The program is called SeqBuilder; it's a miserable excuse for a cloning tool which we use because our Institute cannot afford Vector NTI. However, the page that I link to presents the genetic and annotation information in a way which I have seen time and time again in my short scientific life and this leads me to believe that it is some sort of generic format, capable of being understood by a number of different programs. If I save it as an .sbd file, SeqBuilder will open the sequence but ignore the annotations. I hope that by appending the correct file extension, I'll achieve an annotated sequence. --129.215.47.59 (talk) 19:33, 26 April 2011 (UTC)

You say, "the page that I link to" - which page is that? If you have an example of the layout you desire it will be easier to guide you. The options are remarkably diverse. Examples of free programs: Artemis, CLC sequence viewer. Geneious is not free, but has great features & students can get a 1-month license for $39. If these aren't what you want, please be more specific. -- Scray (talk) 02:54, 27 April 2011 (UTC)

The file format you link appears to be a variant of the EMBL or Swiss-Prot file formats (see [1] and [2]). If it doesn't autodetect the format, you would have to see what extension your program expects files with such a format to have. (Besides looking in the manual, one way to do so would be to try *saving* as EMBL format, and see what extension the program give it.) -- 140.142.20.229 (talk) 00:40, 27 April 2011 (UTC)

Fermi Paradox and data encryption

Our article on the Fermi paradox says that compressed data streams would be almost indistinguishable from white noise. Would not the same apply if the data was encrypted? A Quest For Knowledge (talk) 17:06, 26 April 2011 (UTC)

If it's good encryption, then absolutely. See page 13 of this book. So you're hypothesizing that the galaxy is teeming with life that communicates by radio, but it's encrypted, so we have no idea? Comet Tuttle (talk) 17:13, 26 April 2011 (UTC)

Both for compressed and encrypted streams, this assumes the data is sent with no kind of framing. You can communicate over an unreliable medium with a self-synchronising code, but why would you bother (unless you were trying to conceal the transmission)? Note that the assertion about compressed streams in that article is unsourced. -- Finlay McWalter ☻ Talk 17:23, 26 April 2011 (UTC)

I think concealment must be the whole point; see Prime Directive. Comet Tuttle (talk) 22:41, 26 April 2011 (UTC)

I'm also not convinced, absent a decent reference, either that a) a compressed stream resembles white noise as opposed to another colour (particularly for schemes which periodically flush their dictionaries) or b) that the cosmic or galactic noise you'd typically see is white either. -- Finlay McWalter ☻ Talk 17:36, 26 April 2011 (UTC)

It also depends on what your definition of a "resemblance" is. A wide band signal will fill the fourier-domain spectrum, but not with random data. So, if you define a signal to "resemble" white noise, solely on the basis of whether it occupies a wide frequency band, then a lot of things "resemble" white noise. Ultimately, if you use a deterministic compression methodology, each compressed input stream will have a unique spectral signature; so the characteristics of the output stream will depend entirely on what data is being transmitted. If you use a lossy compression scheme, any particular source stream will map to one of a finite set of possible compressed stream spectral signatures. I'm not very happy about our "color of noise" article, which seems to blur the terminology. I like our noise shaping article much better; and will toss in that digital signal quantization has unique spectral properties that are easily detectable as "band limiting;" the modulation scheme for any particular signal will dictate whether the band limitation exists as a fourier frequency band, or as some other more abstract vector-space spectrum (such as phase-space, or generalized wavelet spectrum, etc). Nimur (talk) 18:13, 26 April 2011 (UTC)

Toasted bread

why does the toasted bread tastes sweeter than the normal bread? —Preceding unsigned comment added by 122.162.128.226 (talk) 17:29, 26 April 2011 (UTC)

See Maillard reaction. --Jayron32 17:38, 26 April 2011 (UTC)

The sugar components of starch (amylose, glucose, etc) are relatively tastless in starch form. But when subjected to dry heat it produces pyrodextrins through process called pydrodextrinization (strange as it may seem). More like the sugars we use for sweetening. Wiki article (starch)scroll to pyrodextrinization.Phalcor (talk) 18:48, 26 April 2011 (UTC)

Without reading the article, I will tell you that you can link to the 'starch' article on this wiki by typing [[starch]], which gives you a blue link like this: starch. If there is a header 'pyrodextrinization' in the article, you can link to it by typing [[starch#pyrodextrinization]] which produces starch#pyrodextrinization. 82.24.248.137 (talk) 20:43, 26 April 2011 (UTC)

Oh, and I see that you probably meant people to read the bit under Starch#Dextrinization. 82.24.248.137 (talk) 20:44, 26 April 2011 (UTC)

perennial

Resolved

The Taraxacum officinale article says that they are perennial, but I can't see any mention of exactly how long they usually live. I know perennial means more than 2 years, I would like to know more specifically how long they can live for. 82.43.89.63 (talk) 18:56, 26 April 2011 (UTC)

The thing is, 'death by old age' doesn't really apply here. Dandelions exhibit indeterminate growth. So, death of a mature plant will usually be due to Plant_pathogens, herbivory, roundup, etc. In this light, the average life-span of a dandelion in a given population will depend on how prevalent these sources of mortality are. In principle, I know of no reason why a well-cared for specimen couldn't live 100 years or more. SemanticMantis (talk) 19:23, 26 April 2011 (UTC)

Thanks! 82.43.89.63 (talk) 20:33, 26 April 2011 (UTC)

Higgs boson

How does the Higgs boson explain the difference between the massless photon, which mediates electromagnetism, and the massive W and Z bosons — Preceding unsigned comment added by Lufc88 (talk • contribs) 20:04, 26 April 2011 (UTC)

Assuming you understand the contents of these articles (I certainly don't), you may find your answer at Higgs mechanism or 1964 PRL symmetry breaking papers or Higgs_boson#Theoretical_overview. Presumably, the information therin could be summarized in a way that someone who isn't familiar with the mathematics involved can still understand, which I will leave to someone else to do. --Jayron32 20:14, 26 April 2011 (UTC)

Perhaps that editor could also write such a summary in the appropriate articles. Like, as line #1 of each article. Comet Tuttle (talk) 22:39, 26 April 2011 (UTC)

How about starting with an explanation of this...:

"In the standard model, at temperatures high enough so that electroweak symmetry is unbroken, all elementary particles are massless. At a critical temperature, the symmetry is spontaneously broken, and the W and Z bosons acquire masses.

Fermions, such as the leptons and quarks in the Standard Model, can also acquire mass as a result of their interaction with the Higgs field, but not in the same way as the gauge bosons."

Now to be clear - at some very high temperature, does this mean that electron, quark, W, and Z (and photon?) all zip around at the speed of light, as massless particles, and can't go any slower than the speed of light? Are they all actually the same at that point, or just have the same apparent properties?

And at some point, they gain masses by interacting with the non-zero vacuum expectation Higgs field. Is there anything about the massless particle that says ahead of time whether it will become an electron, quark, W, or Z when it interacts with the Higgs?

If you cool down a photon enough, so that it has a really really really tiny energy and a huge wavelength, could it interact with a Higgs and become some new particle we don't yet know about? Wnt (talk) 00:41, 27 April 2011 (UTC)

The short version is that the symmetry breaking mechanism leaves some symmetry behind, and names like "photon" and "electron" are assigned after the fact in accordance with the remaining symmetry. Start with a featureless sphere. There are three independent continuous symmetries of the sphere: rotation around any three mutually perpendicular axes. Now break the symmetry by drawing a dot somewhere on the sphere. Probably, rotation around any of your original axes will move the dot. But there was never any reason to choose those particular axes, so throw them away and choose a new axis through the dot and two other axes perpendicular to that one. Now you have one rotational direction that preserves the remaining symmetry of the sphere-with dot, and two that don't. This is not the greatest of analogies, but it sort of resembles the origin of the photon and the W^± bosons. Keeping in mind that the choice of axes depends on the location of the dot, and the dot can be anywhere, do those axes "exist" before the dot is drawn? In one sense yes, in another sense no. -- BenRG (talk) 10:51, 27 April 2011 (UTC)

I think thye sphere with a dot is a good analogy. Dauto (talk) 13:46, 27 April 2011 (UTC)