Wikipedia:Reference desk/Archives/Science/2013 August 16

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August 16

Identification of bug

I found this bug on the wall next to my front door this afternoon. Any idea what it is? NealCruco (talk) 00:29, 16 August 2013 (UTC)

That's a nice katydid, note the long antennae. Generally a harmless and interesting insect. Getting any more specific than that will might require some location information, and perhaps a sample specimen and Identification key. SemanticMantis (talk) 01:20, 16 August 2013 (UTC)

Maybe a common true katydid: Pterophylla camellifolia? Vespine (talk) 02:11, 16 August 2013 (UTC)

Well, I live in the CST time zone of the US. Is that specific enough? NealCruco (talk) 20:02, 16 August 2013 (UTC)

Your latitude is probably at least as important as your longitude. Nyttend (talk) 02:06, 18 August 2013 (UTC)

Vacuum pump

Do foot operated manual vacuum pumps exist, which are able to attain partial pressures involved in Büchner filtration? Plasmic Physics (talk) 01:54, 16 August 2013 (UTC)

Could you state the level of vacuum needed, in case someone is more familiar with pumps than with the particular process? Lots of gas chemistry was done in the 19th century with manually operated equipment. Hard vacuums were achieved with mercury operated pumps rather than mechanical pumps. Edison (talk) 14:23, 16 August 2013 (UTC)

The article on the process says an aspirator will work.I would call it a "suction" rather than a vacuum process, so comments about high vacuum do not apply. Foot operated aspirators are available, though the supplier I found is a wholesaler. See Medical foot operated manual vacuum aspirator where the FOB price is stated as $30-$180, so shop around. If you are handy, it might be possible to alter a typical foot operated inflator pump so that it acts as a suction pump. Here is a different design of foot operated aspirator which produces 300 mm of suction. There are also venturi suction devices which use the flow of tap water through a device to create suction, and cost about $7. Edison (talk) 14:44, 16 August 2013 (UTC)

Water-tap aspirators are pretty commonly used for this application. I've had problems with these sorts of filtrations when the vacuum source is pulsed rather than a more constant pull, but it depends on the nature of the liquid, solid, and filter-medium being used.. DMacks (talk) 15:28, 16 August 2013 (UTC)

The idea is to save on utilities, I don't want to be running up my parents' bills. I'm visualizing something like a spinning wheel - a pump which converts reciprocal motion to rotational motion.

Meaning, I'm not going to waste perfectly good water. Plasmic Physics (talk) 05:01, 17 August 2013 (UTC)

The spinning wheel is supposed to function as a fly wheel, preventing a pulsed vacuum. Plasmic Physics (talk) 08:12, 17 August 2013 (UTC)

'Suction'/vacuum', 'tomato'/'potato'. Thanks, I'll have a look at those. Plasmic Physics (talk) 01:09, 17 August 2013 (UTC)

Gingko biloba cutting

I took a 12 in. cutting from a tree a few weeks ago and have kept the proximal end in water ever since. For about 2 weeks it was doing fine and all the leaves remained moist and green and everything nice. But then, without warning, it shriveled and now I had to throw it out. Anything I should have done differently? My plan was for it to sprout rootlings and then I could plant it in soil and get a tree eventually by transferring it into a backyard. DRosenbach ^{(Talk | Contribs)} 03:48, 16 August 2013 (UTC)

Maybe should have used Indole-3-butyric acid? See cutting (plant). Wnt (talk) 04:03, 16 August 2013 (UTC)

Using water alone to propagate woody plants is always going to be problematic. The time taken for roots to appear is almost always longer than the time that mould or fungus takes to infect the cutting. This page suggests (1/3 way down) 15 centimetre cuttings of semi-ripe wood in summer in a cutting compost, this is a standard procedure for woody subject. My intuition tells me that gingko biloba are not that easy to root but I can't point you at a citation. Good luck, they are very interesting trees. Richard Avery (talk) 06:27, 16 August 2013 (UTC)

I'm about to stick a few cuttings in the ground. Spring soon where I am. I shall let you know in three months time. HiLo48 (talk) 07:07, 16 August 2013 (UTC)

As per above, I'd use some rooting hormone, and a little fungicide (neither of which has to be noxious). Rooting woody plants in water-only is often a bad idea, but they also must not be allowed to dry out in the first several weeks. Finally, a fun trick: Salix spp. root very well in pure water, and that water can then be used to root other plants, since it will have dissolved hormones from the willow! SemanticMantis (talk) 13:26, 16 August 2013 (UTC)

Ginko is a very primitive type of plant and is very different from other more advanced broadleaved trees. Our article Ginkgo biloba says; "most intentionally planted ginkgos are male cultivars grafted onto plants propagated from seed, because the male trees will not produce the malodorous seeds." The fact that cultivated root-stocks are grown from seed suggests that it's probably not easy to propagate it from a cutting. Alansplodge (talk) 13:36, 16 August 2013 (UTC)

But apparently it can be done: "The Ginkgo can also be propagated by cuttings (best way to be sure of the sex). Take young or half-ripe wood about 15 cm long during May-July. Put these in a frame and keep moist. They usually start growing best in their second year. You may also take cuttings of mature wood of the current year's growth. Shoots about 15-30 cm long are taken in December and placed in a frame. They should root in the spring."[1] Alansplodge (talk) 13:39, 16 August 2013 (UTC)

Fireflies completely gone from Indianapolis suburbs! Why?

Thirty years ago the suburban Indianapolis farm where my uncle has lived for nearly a century was teaming with fireflies at at least three or four per square foot on August nights. Today there are NONE. I stood outside wandering around the three acre plot for four hours and did not see a single firefly. I do not believe the explanations in http://www.firefly.org/why-are-fireflies-disappearing.html because there is no light pollution here: the same lights are in the same place and the road traffic is the same volume as it was 30 years ago. What do the reliable peer reviewed sources say about this tragedy? 98.220.133.91 (talk) 05:09, 16 August 2013 (UTC)

Indy got hit hard by the 2012–13 North American drought--Digrpat (talk) 09:42, 16 August 2013 (UTC)

True, but we also did here in central IL, and we had a fine firefly season this year. Actually, it peaked almost a month ago, and there are very few left. So perhaps the OP might have found a few round last month? SemanticMantis (talk) 13:27, 16 August 2013 (UTC)

Our article does say that they prefer "marshes or in wet, wooded areas"...so I could imagine a drought hitting them hard. SteveBaker (talk) 15:44, 16 August 2013 (UTC)

If it is a working farm I would ask about recent pesticide usage. Wnt (talk) 19:16, 17 August 2013 (UTC)

Indianapolis isn't the only firefly-free part of Indiana. There are very few fireflies around my house (whether in the woods or in the fields), and I'm in a rural area near Lake Monroe, south of Bloomington. We've been hit at least as hard as Indianapolis has by the drought (although not as badly as the areas west of Evansville); friends of mine in town have a stream in front of their house, but both last summer and this summer have seen it completely dry when it's normally a foot or two deep. Nyttend (talk) 01:56, 18 August 2013 (UTC)

Update — immediately after leaving this note, I stepped outside to watch for fireflies; my house is in the woods. In approximately four minutes, I saw exactly six of them: that's fewer than I'd see in one minute as a child in rural western Ohio. If you've been down toward the Hoosier National Forest, you'll know that we have few marshes down here, so they have to depend on the existence of wet, wooded areas. Nyttend (talk) 02:02, 18 August 2013 (UTC)

identify a plant

Can anyone identify this plant, please? I found it growing in the gap between two concrete slabs in my walkway, in St. Louis, Missouri.—msh210℠ 07:07, 16 August 2013 (UTC)

Pokeweed Phytolacca americana --Digrpat (talk) 09:23, 16 August 2013 (UTC)

Many thanks.—msh210℠ 18:23, 16 August 2013 (UTC)

Bom

How powerful would a bomb have to be for a tremor to be felt at the top of mount everest if it detonated at the deepest part of the ocean? 163.202.48.125 (talk) 12:09, 16 August 2013 (UTC)

Using this program, modeling the effects of an explosion as similar as one due to an impact (except for the air blast):

Input: Distance from Impact: 5000.00 km ( = 3110.00 miles ) Projectile diameter: 15.00 km ( = 9.32 miles ) Projectile Density: 8000 kg/m3 Impact Velocity: 30.00 km per second ( = 18.60 miles per second ) Impact Angle: 50 degrees Target Density: 1000 kg/m3 Target Type: Liquid water of depth 10.0 km ( = 6.2 miles ), over crystalline rock.

Energy:

Energy before atmospheric entry: 6.36 x 10^24 Joules = 1.52 x 10^9 MegaTons TNT

Seismic effects:

The major seismic shaking will arrive approximately 16.7 minutes after impact. Richter Scale Magnitude: 10.7 (This is greater than any earthquake in recorded history) Mercalli Scale Intensity at a distance of 5000 km:

IV. Felt indoors by many, outdoors by few during the day. At night, some awakened. Dishes, windows, doors disturbed; walls make cracking sound. Sensation like heavy truck striking building. Standing motor cars rocked noticeably.

V. Felt by nearly everyone; many awakened. Some dishes, windows broken. Unstable objects overturned. Pendulum clocks may stop.

Tsunami:

The impact-generated tsunami wave arrives approximately 4.5 hours after impact.

Tsunami wave amplitude is between: 255.0 meters ( = 837.0 feet) and 510.0 meters ( = 1670.0 feet).

Count Iblis (talk) 13:31, 16 August 2013 (UTC)

Bom 2

How powerful would a bomb have to be for a tremor to be felt at the deepest part of the ocean if it detonated at the top of mount everset? 163.202.48.125 (talk) 12:09, 16 August 2013 (UTC)

About as big as Bom 1 Caesar's Daddy (talk) 13:06, 16 August 2013 (UTC)

Much bigger, because you only get a big air blast; the seismic effects are then much less for the same explosion yield. Count Iblis (talk) 13:37, 16 August 2013 (UTC)

One problem is that Everest is a long way from the nearest ocean...and just about the opposite side of the planet from the Marianas trench (which is the deepest part of the ocean). That's a much bigger issue than whether you're at the top of a mountain or not. Another problem here is that you say "...for a tremor to be felt..." - you mean felt by a person? I guess their feet can't be touching the ground at the bottom of the deepest part of the ocean...so it's a bit hard to know how much seismic motion there needs to be under those circumstances. Is the person in a submarine? Either way, it's a heck of a lot more than if you were standing on the ground.

This document (which is talking about long distance seismic waves) says that "...larger power sources tend to produce lower frequencies." Unfortunately, humans are less good at detecting low frequency waves through our feet - a wave that moves the surface through (say) a millimeter over a time period of several minutes is detectable by instruments pretty easily - but not by humans. So we wouldn't "feel" the highest power sources. A very high frequency vibration of a tiny fraction of a millimeter is easy to feel...but that's not what you'll get here.

Underwater, you might feel a resulting tsunami - but not that far from land - and certainly not so deep.

The 1883 eruption of Krakatoa caused an explosion was estimated to be about 200 Megatons - four times larger than Tsar Bomba - the largest nuclear weapon ever made. Krakatoa is by far the largest explosion to have happened on earth in recorded history. It makes a great example of what could perhaps be achieved here.

That explosion was heard up to 3,000 miles away(!) - nowhere near far enough for your thought-experiment - so a guy sitting in a rowboat above the Marianas trench wouldn't hear it. Seismic instruments everywhere in the world measured the seismic waves - which looped around the world at least seven times before they faded too much to be measured. But those instruments are vastly more sensitive than people can feel themselves. Air pressure sensors also measured the change all around the world - but those effects wouldn't be noticable at the bottom of the ocean.

Smaller water waves were detected in fairly crude tidal gauges in the English channel - which is about as far from Krakatoa as you can get - so our guy in his rowboat might be able to detect it - but again, you wouldn't feel those at the bottom of the ocean - only in the surface layers of the water.

There don't seem to be any reports of people FEELING the explosion at ranges out at 3,000 miles where they could only just barely HEAR it...so people didn't feel the explosion on the other side of the world. It's pretty clear that 200 Megatons is nowhere near enough to do what you're looking for.

So the nearest I can get to a conclusion is that you need much MUCH more than 200 Megatons - which is already four times that of the biggest nuclear weapon ever manufactured.

The Valdivia Earthquake in Chile in 1960 (the largest earthquake in recorded history) produced seismic waves with 12 times more energy than Krakatoa - with an energy of around 2.7 gigatons - and even that was not felt by humans around the world - although it wasn't technically an explosion, so perhaps it doesn't count.

I doubt it can be done with any reasonable technology.

SteveBaker (talk) 15:31, 16 August 2013 (UTC)

One nitpicky detail: Everest is not really all that far from the Mariana Trench. Antipodes shows that the opposite side of the world from Everest is some distance off the west coast of Chile. The Trench is south of Japan and east of the Phillipines, and its antipode is somewhere around the coast of Brazil. As to setting off a bomb atop Everest, I would think Everest itself would absorb (and possibly be damage by) such a blast. Supposedly the crust under mountain ranges is much thicker than in the flatter areas of the continents, so the bomb would have to have the energy of a major earthquake - and that would take a huge amount of TNT. What humans can do pales by comparison with what Mother Nature can do. ←Baseball Bugs ^{What's up, Doc?} carrots→ 10:35, 17 August 2013 (UTC)

As a point of comparison, the Tunguska event in Siberia in 1908 knocked down an estimated 80 million trees over an area covering 2,150 square kilometres (830 sq mi), and it was only about 40% the power of Tsar Bomba. Krakatoa was 10 times as powerful as Tunguska, and Valdivia was 12 times as powerful as Krakatoa (or 120 times as powerful as Tunguska - roughly equivalent to the destruction of 10 billion trees). -- Jack of Oz ^{[pleasantries]} 20:09, 18 August 2013 (UTC)

Neutron gamma gamma

The article Neutron gamma gamma was created on August 14, 2013 and says things like"When two gamma photons are in contact, and unlike charge state (+ -), [3], are engaged by the ultra-high electric hook." "The two photons gamma (gamma pair) move at the speed of light, but the ultra-electric hook bend their trajectories rotating them on a imaginary center mass " and "Stability of gamma pair becomes unbalanced at about 10.3 minutes (statistical), but not broken. [26]" Is it the gibberish it sounds like? Are there little "gamma gammas" spinning around which resemble the Yin Yang images?Individually there are a number of verifiable facts in the article, but is it overall an accurate depiction of a notable topic in physics, or is it original research? Edison (talk) 15:26, 16 August 2013 (UTC)

The article obviously needs either deleting or serious and ruthless editing, but I'm not sure which. We need a particle physicist. There is a process called Neutron-gamma (η,γ) otherwise known as Neutron capture, but we already have an article on this. Is User:MARCOS BUIRA PARDO trying to explain this, or some other process? Dbfirs 16:30, 16 August 2013 (UTC)

The phrase "neutron gamma gamma" - which I have never heard before - is never explained, or even used - and does not appear in any of the "references" listed at the bottom; so at the very least, we can say the article is improperly titled. The references themselves are mostly reasonable and reputable websites, but they do not validate the material in the article or mention the title. In other words, Template:Irrelevant_citation and Template:Failed_verification applies.

After trying to read two or three paragraphs, I am inclined to declare the page "patent nonsense," and at the risk of escalating accusations about my grouchiness, I recommend deleting the article. It satisfies several criteria for deletion, and I do not believe even generous editorial help can save the article. Nimur (talk) 17:23, 16 August 2013 (UTC)

It looks like nonsense, but not quite patent. I'd take it to AfD rather than {{db-nonsense}}. --Trovatore (talk) 21:12, 16 August 2013 (UTC)

So nominated per WP:DUCK. Clarityfiend (talk) 00:53, 17 August 2013 (UTC)

I expect little subatomic particles, however small would spin madly about their "imaginary center of mass," even if they were somehow oppositely charged but massless, and the article may contain numerous true and referenced statements and facts, but may not have a subject that satisfies WP:V and WP:N. The article creator's lack of fluency in English might be part of the problem. Edison (talk) 04:42, 17 August 2013 (UTC)

When a neutron star explodes (by nuclear reaction), what expelling? quarks or gamma photons. MARCOS BUIRA PARDO (talk) 14:07, 17 August 2013 (UTC)

Marcos, could you tell us what you read to get the information for this article? Are you describing Neutron capture? Dbfirs 07:33, 17 August 2013 (UTC)

Sorry for the confusion, I'm Spanish, I'm using Google translator. Neutron gamma gamma, is a neutron model not based on 3 quarks. But it has a precise mathematical support for size,energy and mass. Thank you very much.MARCOS BUIRA PARDO (talk) 14:07, 17 August 2013 (UTC)

Google translate is not really suitable for writing Wikipedia articles (though it is useful for translating articles into your own language). Perhaps you should write the article in Spanish and try it on the Spanish Wikipedia, but you will need to provide references. I wonder if the best place for alternative theories on neutron structure might be the article on Neutron. Dbfirs 16:22, 17 August 2013 (UTC)

... later ... I don't read Spanish, but I'm told that the article doesn't make much sense in Spanish either. What references are you using? If this is just your own theory, then Wikipedia is definitely not the place to publish it because we don't allow original research. Dbfirs 07:26, 18 August 2013 (UTC)

How to compute the RGB values from the raw data of the camera?

As I understand it, a digital camera only has 3 sensors for each pixel with different spectral sensitivities. These don't correspond to the spectral sensitivities of the cells in our eyes, a linear transformation (the color matrix) is used to compute the RGB values and then some nonlinear transforms are used. However, I don't see how you could ever get the RGB values right if you only have 3 independent measurements that do not correspond to RGB.

So, the problem is that the "color space" of each pixel is infinite dimensional, because you have specify the amplitude of each frequency. Then what we perceive is always is the projection onto a 3 dimensional subspace, that subspace being defined by the spectral sensitivities of the cells that can detect red, green and blue light. But the camera has 3 different sensors, it project each pixel in a different 3 dimensional subspace. Count Iblis (talk) 18:07, 16 August 2013 (UTC)

SCIEN recently had an excellent presentation on this topic: essentially, a digital camera's electronics and computer is numerically inverting for several optical and physical processes, not least of which is the color filter array. Count Iblis correctly notes that the problem is underconstrained (in the pure mathematical sense of that word); this means that each implementer has to use a lot of heuristic tricks, leaving much room for error. I will see if the presentation video or slides are available to the public. Nimur (talk) 18:22, 16 August 2013 (UTC)

Thanks, it would be interesting to read more about this. I had not read into this issue before. It was only after I bought my Sony camera and the software for processing the raw files didn't work on my computer that I started to read about this. Alternative software is available but my camera isn't supported so I needed to find out about the way the colors are computed from the camera sensors. Count Iblis (talk) 19:22, 16 August 2013 (UTC)

Unfortunately the presentation I linked is available but non-free. In the interrim, we have a modest article on the generic color image pipeline; you can implement such a processing flow in software. The naive implementations for each stage are generally self-evident; the hard part is making algorithmic improvements that work without loss of generality. But if you're only processing a few images, this need not be an urgent concern. I'm not aware of any good free software implementations, but if you're willing to do a lot of manual work to tune up the results, dcraw can be used in GIMP; or if you prefer commercial software, you can download a Sony raw data plugin for Adobe Photoshop. Aperture (software) also works with Sony cameras, out of the box. Nimur (talk) 17:53, 17 August 2013 (UTC)

You may be overlooking that any three independent linear combinations of the cone response curves are as good as the actual cone response curves—they span the same (co-)subspace. Also, real-world spectra are pretty simple, otherwise a small change in illumination or a slightly tinted filter would totally change the apparent color of everything. Camera sensor response curves that aren't quite right won't distort the colors of real scenes too badly. -- BenRG (talk) 12:27, 20 August 2013 (UTC)

About running--------

If a person having weight 50 K.g.is running everyday in the morning about an hour with walking of 4 kilometers.He consumes less food than he want to eat.So what should be the effective change in the body? — Preceding unsigned comment added by Titunsam (talk • contribs) 18:17, 16 August 2013 (UTC)

There are many online sites showing how many calories you consume with exercise ([2] for example).

Basically, the calories from running for an hour will vary between about 470 to over 1000 depending on how fast you run. To get much over 600, you'll have to be running faster than most people can sustain for an hour - so 500 calories is probably a good number to go with. Walking 4km (2.5 miles) at a normal pace (around 2.5 mph) means that you're doing an hour of general walking - which consumes maybe another 180 calories. So you're consuming 680 from exercise. If you'd sat and watched TV for those two hours, you'd only have consumed around 220 calories - so you'd about 460 ahead of the game - which is about as much as one slice of pizza. (This is why exercise doesn't really excite me! I'd rather not bother with the exercise and eat one less slice of Pizza...but that's just me!)

It takes 3700 calories to make one pound of body fat - so you have to eat 3700 calories less than you burn in order to lose one pound.

So if you're only eating the barest minimum to keep your weight stable without exercise - then your exercise program should help you lose nearly a pound every week...which is a pretty good, sensible weight loss rate.

However, one extra slice of pizza per day - or a bag of potato chips every two days - completely wipes out the weight loss effect of all that exercise.

The problem is with "He consumes less food than he wants to eat". That's not a useful measure of what's good for you. If I eat whatever I want to - I'll go 500 calories over my ideal calorie intake every day. It only takes half a bag of chips to do that! And then I'll pack on a pound a week - and within a year I'll be seriously overweight.

To do this properly, you need to count and weigh EVERYTHING that passes your lips. Do this for a week - and by then you'll have a pretty good idea of what you're really consuming - in terms of calories.

For "numbers geeks" like me - I strongly recommend "The Hacker's Diet" - it's a great book that explains all of this clearly. Follow what it says to the letter and you'll lose a pound a week. Don't try to lose any faster than that though or you risk putting your metabolism into "starvation mode" - at which point losing weight becomes a major problem.

SteveBaker (talk) 19:04, 16 August 2013 (UTC)

That's what works for you, Steve. This is very individual. Some people eat less when they exercise, because exercise fills the void that they used to fill with the potato chips. (Or, in my case, there was I time I was controlling my weight by swimming, and I think part of the effect was that it made me just a tiny bit sick to my stomach and I didn't want as much lunch afterwards.) There was a period of a good number of years where I was able to control my weight with exercise alone, eating pretty much whatever I wanted. That's not true anymore, but it got me through at least five years consecutively, which is not to be dismissed lightly. --Trovatore (talk) 19:14, 16 August 2013 (UTC)

Yes, I agree. The hackers diet book does go into the science of this in some detail - and there is more to this than meets the eye. Personally, I find that exercise makes me incredibly hungry - so afterwards I'll want two more slices of pizza - and that doesn't just reverse the effects of exercise - it makes matters worse. Buy yeah - everyone is an individual. The best answers we can give are broad-brush. SteveBaker (talk) 19:30, 16 August 2013 (UTC)

Yes, and my own experience would point to the calory intake not being relevant for your weight (within a reasonable bandwidth) provided you exercise vigorougly almost every day. It doesn't make sense to me that an animal that has to survive in the wild would starve to death if due to changes in the environment it had to spend a bit more energy to get its food and if the amount it would find were a bit less. Obviously, it would just adjust its metabolic rate to keep its weight constant, warm blooded animals must have such a mechanism to avoid starving to death for such trivial reasons (note that 100 Kcal/day deficit = 46 kg weight loss in ten year time, but I'm sure I won't starve to death in ten years if I were to eat a sandwich a day less and increase the time I exercise a bit).

I measure everything I eat, I know that I eat close to 4000 Kcal per day now. I have increased my calory intake a lot it used to be just over 3000 Kcal/day a few years ago, and yet I have lost some weight, I used to weigh about 61 kg and I'm now at 58 kg. This is consistent with my idea that the body is designed to regulate itself, and eating until you are full is part of a normal healthy routine but then so is running for at least 30 minutes per day (I run for 50 minutes, 5 times per week). Why on earth would the signal for feeling hungry be wrong so that listening to it would undermine your health? To me that doesn't make sense at all. And if this is actually the case for some people, then these people have some health problem to begin with, which in most cases I believe is that they are couch potatoes. Count Iblis (talk) 19:44, 16 August 2013 (UTC)

Thermic effect of food

I read over here that digesting food requires calories. I was wondering if there's any food that requires more calories to digest than they contain. ScienceApe (talk) 21:08, 16 August 2013 (UTC)

See our Negative calorie food article. DMacks (talk) 21:13, 16 August 2013 (UTC)