Wikipedia:Reference desk/Archives/Science/2011 May 18

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May 18

Mouth Anatomy

Here is an image of a mouthguard, worn by some athletes to lessen the risk of injury in case of falls, catching a hockey puck in the teeth, etc.

http://www.acmetaekwondo.com/home/images/stories/news/mouth_guard_3.jpg

The device fits around the upper teeth; the indent at the top centre is to accommodate a line of soft tissue between the upper lip and the upper gum.

My question: what is the function of that soft tissue?

Thanks. Wanderer57 (talk) 00:17, 18 May 2011 (UTC)

According to [http://www.ispub.com/journal/the_internet_journal_of_dental_science/volume_7_number_2_20/article/clinical-assessment-of-diverse-frenum-morphology-in-permanent-dentition.html this] article, it is called the "superior labial frenum" and is "a membranous fold of mucous membrane which provides stability and support for the upper lip. It is also called as Maxillary frenum or frenulum labii superioris." Bielle (talk) 00:35, 18 May 2011 (UTC)

Of course it's worth remembering that the human body is far from perfect in evolutionary terms and many parts of the body have no perceivable funtion although wherever there is a feature someone will have a theory about why it is there. I'm thinking philtrum and vermiform appendix as two easy examples. The idea that this tiny flexible piece of tissue has any effect on the stability of the top lip stretches credulity. Likewise there is a similar membrane under the tongue which has on some individuals been severed for medical reasons (tongue tie) or accidental causes with no effect whatsoever on the funtion of the tongue. Interestingly the WP article for this membrane only offers a funtion during foetal development Richard Avery (talk) 07:29, 18 May 2011 (UTC)

I'm sure the philtrum arises as a consequence of the way the face develops in the womb, being the point where the various parts of the face meet during development, rather than being a facial feature with a particular function. It is problems with this development that leads to cleft lip Si1965 (talk) 09:59, 18 May 2011 (UTC)

EDIT: having just read the philtrum article, I see its says all that, and in a much better way than I just did. Si1965 (talk) 10:01, 18 May 2011 (UTC)

Our article on the appendix points out that the "vestigial organ" explanation is probably incorrect; the human appendix apparently serves the function of providing a "safe house" for gut flora to repopulate the intestines from. Matt Deres (talk) 13:50, 18 May 2011 (UTC)

We need an article on superior labial frenum or Frenulum of upper lip Graeme Bartlett (talk) 12:14, 18 May 2011 (UTC)

The OP was asking specifically "What is the function of that soft tissue?", which is quite separate from 'how was it formed'. My point was not everything in or on the human body has a function. Richard Avery (talk) 13:20, 18 May 2011 (UTC)

We sometimes cut the maxillary frenum if it's in the way, by doing a labial frenectomy. DRosenbach ^{(Talk | Contribs)} 16:45, 18 May 2011 (UTC)

Orion Molecular Cloud Complex

Knowing of my interest in Astronomy and PowerPoint a teacher friend of my ask if I might be able to put together some slideshows showing some of the beautiful object making up our universe. I could think of no better one to start off with than The Orion Molecular Cloud Complex. Wikipedia’s article on the complex (http://en.wikipedia.org/wiki/Orion_Molecular_Cloud_Complex) breaks it down into eight parts; I have found photos of all of them except two, the Orion Molecular Cloud 1 (OMC-1) and the Orion Molecular Cloud 2 (OMC-2). Can anyone direct me to a site where I can obtain good quality photos of these two objects? Any help provided would be greatly appreciated. 173.202.14.171 (talk) 03:11, 18 May 2011 (UTC)

In the Wikipedia article you linked, the first site in the External Links section is this, which has a picture of OMC-2 on that page, plus links in the text to two objects within OMC-1. Whether they qualify as "good" is another question, but my understanding is that the light that reaches us from them is largely at infra-red rather than visible wavelengths, in which they are somewhat obscured by dust, so there may be a limit to how "good" in the aesthetic sense they can be.

I do not address the question of whether they or other pictures not on Wikipedia may have copyright issues; some jurisdictions might hold that one-time use in a non-commercial academic context would be permissible, but it would be your responsibility (and also that of the teacher giving or supervising the slideshow, who should be professionally aware of such issues) to ensure that you do not contravene copyright. {The poster formerly known as 87.81.230.195} 90.197.66.156 (talk) 03:40, 18 May 2011 (UTC)

A Hubble Space Telescope image of OMC-1 can be found here. The right panel is a NICMOS image, so indeed (near-)infrared. --Wrongfilter (talk) 08:07, 18 May 2011 (UTC)

If you check out the Hubble site, you will find some amazing photos there, and also a link to their educational use policy. --TammyMoet (talk) 09:26, 18 May 2011 (UTC)

HAHO jumps and radar

I understand that HALO jumps are intended to get people safely to ground in a hostile environment ASAP. But HAHO is also supposed to be used in hostile environments where overflight is dangerous? Doesn't a parachute slowly cruising along for many kilometers show up on radar? The Masked Booby (talk) 03:33, 18 May 2011 (UTC)

Fabric is not a good reflector of radar. The material of the target is an important component of radar reflectance. Seaphoto^Talk 03:36, 18 May 2011 (UTC)

Does evaporative cooling cause air to become lighter or heavier?

I live in a climate with hot but fairly dry summers and I'm designing a dog house with simple evaporative cooling on the roof. It seems there are two opposing effects when cooling air by evaporation of water:

• Adding water vapor which is lighter than air at a certain temperature as mentioned by the article on relative humidity
• Cooling the air which makes it denser

For summer temperatures (25 to 40 degrees celsius) and low starting relative humidity (below 50%), when attempting to cool air down to wet bulb temperature, can one rely on a particular one of these effects always dominating? If so, which one? 196.215.115.184 (talk) 06:42, 18 May 2011 (UTC) Eon

I have evaporative cooling in my house. The cool air is driven into the house by a powerful fan so there is some turbulence and immediate mixing with the warmer air in the house. I would guess that the increased density of the cooler air is much more significant than any reduced density due to the presence of water vapor. This would seem to be confirmed at Microburst#Dry microbursts. Dolphin (t) 07:32, 18 May 2011 (UTC)

(edit conflict)Evaporative cooling makes air denser overall. The process is very important in the formation of downbursts in severe thunderstorms; extreme evaporative cooling can cause a pool of air to become extremely dense compared to its surroundings, and it will rush towards the ground with great force [1]. -RunningOnBrains^(talk) 07:37, 18 May 2011 (UTC)

Vision & Fear

How is fear reduced when one closes one's eyes (but not entirely) during a threatening situation or while watching a horror movie? What connection does vision have with fear/amygdala/emotions etc.,? - anandh, chennai —Preceding unsigned comment added by 199.224.149.10 (talk) 07:42, 18 May 2011 (UTC)

The Ostrich effect is the avoidance of apparently risky financial situations by pretending they do not exist. The name comes from the common (but false) legend that ostriches bury their heads in the sand to avoid danger. This myth likely began with Pliny the Elder (AD 23-79), who wrote that Ostriches "imagine, when they have thrust their head and neck into a bush, that the whole of their body is concealed." Cuddlyable3 (talk) 08:02, 18 May 2011 (UTC)

Thanks. Are blind people blind to fear? - anandh, chennai. —Preceding unsigned comment added by 199.224.149.10 (talk) 08:19, 18 May 2011 (UTC)

Vision isn't the only way to know that they are in a dangerous situation. I suppose, if a bunch of thugs carrying guns pass by, the blind person may not be afraid, if they don't know about the guns. But, if somebody told them, then they'd be just as scared. StuRat (talk) 08:32, 18 May 2011 (UTC)

While I assume there is no great overall difference in how the blind experience fear, it still might be interesting to see how fMRI images of amygdala activation would differ between the congenitally blind and the sighted. I scrounged around on the net a little and found this weird master's thesis claiming that congenitally blind people have some developmental traits similar to autism (perhaps simply due to lack of cues from facial expressions) but I'm afraid I didn't look it over very carefully.^[2] The truth is probably out there, I'm just not thinking of the right search terms. Wnt (talk) 10:12, 18 May 2011 (UTC)

Blindness is really more of a philosophical essay than a scientific guess. Also this inaccessible journal article might be of peripheral relevance. ~AH1 ^(discuss!) 00:52, 20 May 2011 (UTC)

Is the plane that separates the bonding and anti-bonding region in two H atoms a hyperboloid of two sheets

I can't find it but I saw a picture showing this plane and it looked so much like a hyperboloid of two sheets(and maybe the two nuclei are the focal points)If it's true could you show me a proof or something? thanks.--Irrational number (talk) 08:50, 18 May 2011 (UTC)

Antibonding in H₂ is unstable,[3] so the electrons bond when they are out of phase by releasing kinetic or low frequency (radio to infrared) electromagnetic energy. For regions in more complex molecules, the probability density functions involved rarely form perfect mathematical shapes, even for uniform charge boundaries. 99.39.5.103 (talk) 11:27, 18 May 2011 (UTC)

The bonding and corresponding antibonding are in the same general area, not really "separated from each other". But σ*, the antibonding orbital of a single bond, does look like you describe in the area between the two atoms. Is the image in that article close to what you are remembering? DMacks (talk) 21:13, 18 May 2011 (UTC)

What is a diathermic substance?

like.. a diathermic wall —Preceding unsigned comment added by Krishnashyam94 (talk • contribs) 10:30, 18 May 2011 (UTC)

It means it conducts heat relatively well. 99.39.5.103 (talk) 10:59, 18 May 2011 (UTC)

"-thermic" obviously refers to heat; -dia means through or across. ~AH1 ^(discuss!) 00:46, 20 May 2011 (UTC)

Do sound waves tell us anything about how the microscopic interactions between the surfaces are?

If the answer is yes, are there any examples? Imean the sound of metalls colliding each other is different from the sound of two pieces of plastic colliding each other. why?--Irrational number (talk) 10:44, 18 May 2011 (UTC)

The tone, timbre, other spectral characteristics, and envelope characteristics like ringing involve complex interactions between a substance's density, tensile strength, hardness, compressibility, elastic modulus, surface texture (especially if it's involved in a highly inelastic collision), acoustic and mechanical dampening characteristics, size, and shape, as well as the force and composition of the material striking it. Acoustics is very complicated, but not as complicated as turbulent flow. 99.39.5.103 (talk) 11:06, 18 May 2011 (UTC)

Vibration analysis (no article or link ?) is the method of determining the condition of machinery and structures based on the sounds they make, either on their own or in response to an input sound. One simple rule is that a solid object will transmit sound better than one full of cracks. StuRat (talk) 18:28, 18 May 2011 (UTC)

Hence the long-established railway-worker specialism of Wheeltapper. {The poster formerly known as 87.81.230.195} 90.197.66.34 (talk) 07:57, 19 May 2011 (UTC)

What you're looking for is the field of sound colour (ie. white noise, brown noise, red noise), and interactions given acoustic resonance. ~AH1 ^(discuss!) 00:42, 20 May 2011 (UTC)

East-Prinovozemelsky field and the ice pack

Could anybody tell me if the proposed East-Prinovozemelsky field that will be worked on by Rosneft would have any use of icebreakers and other icebreaking special vessels. I was just wondering if the joint venture between United Shipbuilding Corporation of Russia and the Finnish company Arctech Helsinki Shipyard Oy would be of any use to Rosneft's activities there. I'm not thinking of investing (wish i had the money) but I'm merely reading up on the business conflicts of the Russian hierachy and it's oligarchs. Deputy Prime Minister Igor Sechin is currently chairman of both Rosneft and United Shipbuilding Corporation but has proposed that Novolipetsk Steel chairman Vladimir Lisin takes over at United Shipbuilding Corporation a company that was all but in name set up by President Vladimir Putin. many thanks. Scraggy4 (talk) 17:02, 18 May 2011 (UTC)

Surely, although I don't think they've decided precisely where various equipment will go. At the very least they'll need smaller icebreakers to keep whatever harbours the service vessels use clear. One reason Rosneft wanted to team up with BP on this was BP's experience on the North Slope of Alaska, which gave them extensive experience of offshore and onshore extraction of hydrocarbons in the challenging arctic climate. Without BP they'll presumably have to team up with someone else to gain that expertise, and it'll be a political problem for anyone (I think Exxon, Conoco, and Statoil are probably the most experienced contenders). You're right to be concerned about the business environment in Russia: Transparency International gives Russia a dismal 2.1 out of 10 on its 2010 Corruptions Perceptions Index.(ref) -- Finlay McWalter ☻ Talk 21:33, 18 May 2011 (UTC)

Many Thanks Finlay I just wasn't sure how cold it got in the current proposed area. Scraggy4 (talk) 23:04, 18 May 2011 (UTC)

Most developed automatic driving car in the market

wkWhich car has the most automatic driving features? Does any one keep the car on track on the road, brake, accelerate, and read traffic signs? I know these features can be found on different cars, but I don't know if they can be found all at once. Quest09 (talk) 17:50, 18 May 2011 (UTC)

Top of the range Lexus? See Lexus_LS_(XF40)#Driver-assist_systems - it has Autoparking, Radar Controlled Cruise Control and Auto Lane Keeping. Exxolon (talk) 18:35, 18 May 2011 (UTC)

See Driverless car, if you really mean "automatic driving". Comet Tuttle (talk) 21:23, 18 May 2011 (UTC)

A Chauffeur can be added to most cars to perform all the mentioned functions. Cuddlyable3 (talk) 09:49, 19 May 2011 (UTC)

Of course we also have an article on cruise control. ~AH1 ^(discuss!) 00:39, 20 May 2011 (UTC)

It's not "on the market", but the OP may be interested in the DARPA Grand Challenge for some background on the development of driverless vehicle technology. --Jayron32 02:25, 20 May 2011 (UTC)

What can a man do against a Straight-Sunken scar on the chin?...

Hello. i would really like your help...

as for today - 2011, what does technology can offer for a man with such a scar?...

laser didn't help,

bless you all!. —Preceding unsigned comment added by 79.183.19.219 (talk) 22:28, 18 May 2011 (UTC)

Sorry, we're not really allowed to give you advice about medical topics. The best we can do is point you towards our article's section on scar treatments : Scar#Treatments. APL (talk) 22:45, 18 May 2011 (UTC)

Hello, i declare i don't look for a Professional medical advice. only for friendly advices.

thanks. 79.183.19.219 (talk) 23:01, 18 May 2011 (UTC)

Sorry, that's the rules. Besides, without examining you personally, I think even a real doctor wouldn't be able to do much better than just giving you a list of all possible scar treatments, like I did above. APL (talk) 23:29, 18 May 2011 (UTC)

(ec):We can't answer this as a request for medical advice. There are lots of good papers out there - it is an active field of research - but what works? What's the best in your case? You'd need a genuine professional to say. But We can begin to answer this (to a very limited degree in my case, as I'm not an expert) if it is a general request for new technologies that are under development, which you might want to watch and see if they become available. I do so in this sense only.

Generally speaking (PMID 21061757) there are many ways that can be used to deal with scars of various types (though not all will be appropriate for your case) - "topical applications (e.g., silicone, vitamin E, pressure dressing, herbal extracts), intralesional medication (e.g., steroids, antimitotics), soft-tissue augmentation (e.g., collagen, fat), laser applications (e.g., 585-nm flashlamp-pumped pulsed dye, CO2), cryotherapy and make-up camouflage." For atrophic scars, some methods I see are:

PMID 21120258 describes a hyaluronic acid based injection to raise the level of the skin.

PMID 20865835, same thing with Artefill.

Some publications mention a CROSS technique, using 100% trichloroacetic acid, for sunken scars. (PMID 21457391, PMID 21332915, PMID 21269351. I see it evaluated generally in terms of sunken acne scars, with about the same success as subcutaneous collagen.

PMID 20553364 - "subcision-suction method". I don't understand what they're doing here but it sounds interesting.

That's what seems most interesting from skimming the first five pages of "scar atrophic" searched at http://www.ncbi.nlm.nih.gov/pubmed going back more or less to 2009 - omitting laser articles since you seem less interested in that. You can try doing a few searches yourself, look into the web as to the risks and benefits of such treatments, maybe call around to local dermatologists and see who offers what or what they have to say against it. Everyone says "ask your doctor" but some doctors have newer equipment and training than others. Don't be discouraged; this is and remains a lucrative field for research. Wnt (talk) 23:34, 18 May 2011 (UTC)

How do Helix pomatia look when they are young?

How do Helix pomatia look when they are young? I see lots of this endangered species in my garden but all of those I see (and identify as such) are 2cm (4/5 inch) at least. Now I wonder if I have no smaler ones around, or if they look very different, or if they hide into places I don't look on my garden walks. 95.112.146.74 (talk) 22:37, 18 May 2011 (UTC)

Google images of baby snails will give you a good idea, i don't think there's anything particular about that species.. You probably don't find them because baby snails are probably better at hiding and aren't as adventurous as adult snails. I also don't see that the species is endangered, it's habitat is threatened in many regions of Europe but that's not the same thing as the species being endangered. Vespine (talk) 23:08, 18 May 2011 (UTC)

Also, forgive me if I'm wrong, but are you sure you aren't just seeing Common Garden Snail? They look very similar to me, I don't think I'd be able to tell the difference. Vespine (talk) 23:12, 18 May 2011 (UTC)

Um, well, it doesn't have a strived shell but as one is a protected species and the other is not, I'm quite thankful for your suggestion and ready and willing to believe it is Common Garden Snail. As for the numbers occuring, I was in doubt for the (de) reason of protection anyway . 95.112.146.162 (talk) 23:54, 18 May 2011 (UTC)