science

Moist Panties

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A compendium to Wet Panties. Originally titled “A New Dynamic Clothing Model. Part 2: Parameters Of The Underclothing Microclimate”

Based on a new modeling, described in the first part of this paper, which takes into account the pumping effect under garments, the various parameters characterising the confined air, and managing its dry and latent losses, are determined. The mean temperature, calculated from heat exchanges with skin (or underwear) and with the garment, progresses exponentially as a function of the trapped time, until a limit. The mean humidity amount, determined from the energy of total evaporation, from the air layer renewal rate and from the water vapour diffusion through the fabric, increases linearly. Using a movable thermal manikin, walking at various speeds, and with a combined effect with wind, the intrinsic air speed and convection coefficient are defined. The intrinsic air speed combines the effects of external air and body motions. The intrinsic convection coefficient is a linear function of the square root of the inner air speed.

Robins Can Literally See Magnetic Fields

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Some birds can literally see magnetic fields. The ability to visualize the Earth’s magnetic field is believed to be linked to the availability of light and it is thought that specialized molecules in the birds’ retinas allow them to literally see the magnetic fields, which appear as patterns of light and shade superimposed over the regular image from light. A new study shows that the internal compass also depends on the birds having clear vision in their right eyes.

Some birds can sense the Earth’s magnetic field and orientate themselves with the ease of a compass needle. This ability is a massive boon for migrating birds, keeping frequent flyers on the straight and narrow. But this incredible sense is closely tied to a more mundane one – vision. Thanks to special molecules in their retinas, birds like the European robins can literally see magnetic fields. The fields appear as patterns of light and shade, or even colour, superimposed onto what they normally see.

Below is what is suspected it would look like to be a robin flying over Frankfurt, Germany at a flight altitude of 200 m above the ground.
Magnetic Vision
Image via Theoretical and Computational Physics Group

Kissing Cooties

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Just in time for valentines day, I discovered this interesting study. According to the Journal of Infectious Diseases, vol. 150, no. 2, August 1984, pp. 189-94, it is very unlikely you can catch a common cold from kissing. According to the journal, “Casual social encounters or kisses between infected and susceptible individuals are probably unlikely to result in the transmission of rhinoviruses.” Below is the data from the experiment

Bonus quote from the study: “During kissing the lateral margins of donor and recipient noses may also touch. [Our observations, as well as previous data] suggests that transmission resulting from nose-to-nose contact during kissing is infrequent….”

The Physics Of Moving Ski Moguls

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As an avid skier I have always considered moguls to be large, immovable, obstacles. Solid piles of difficulty that haphazardly push my skis around with no regard for my intentions.

Three researchers in Colorado, David B. Bahr, W. Tad Pfeffer, and Raymond C. Browning, have discovered that moguls actually move! And not only that – they move up hill!

The math goes something like this:

A specific representation for the erosion–deposition wave W at position x created by a skier n may be given by the sinusoidal form Wn(x) = a sin(2πx/2rn + ϕn), with positive W corresponding to deposition.

The layman explanation goes something like this: as a skier turns on a mogul, snow is scraped from the bottom of one mogul to the top of the next one, having the overall effect of “moving” the moguls. And, although skiers invariably push snow down the mountain, the ski moguls move uphill.

Mogul Diagram

Below is a time-lapse photo of video showing the uphill migration of ski moguls on the Riflesight Notch ski run at Winter Park Ski Resort. The movie spans five months, starting in early December and ending in late April of the 2006/2007 ski season. Each frame of the movie represents one day.

Martian Skin And Tatoo

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Martian Surface

This incredible photo of the surface of Mars was taken by the Mars Reconnaissance Orbiter’s HiRISE camera. Our very own local astronomer/blogger, Phil Plait of Bad Astronomy, points out that:

The important thing to note here is that the sand in the craters of Mars is actually dark grey in color, since it’s made of basalt. The reason it looks red in pictures is because covering the sand is a thin layer of much finer dust, and the dust is what’s red. When a dust devil moves over the Martian surface, it can pick up the very light dust particles, but not the heavier sand grains. So those blue-grey swirls are tracks where the dust devil has vacuumed up the dust, revealing the darker sand underneath. If you look carefully in the tracks, you can see the sand dune ripples are undisturbed. Only the dust is gone.

I think it is also important to note that by clicking the photo above, you can view a much larger version that shows the martian sand dunes and dust devil tracks in detail.

Bell Pepper Teratoma

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The other night I was fixing up some fajitas for dinner. Yum. While cutting up a red bell pepper for my meal, what to my wondrous eyes did appear? A red pepper teratoma! A capsicum styled fetus in fetu, if you will. A pepper within a pepper. According to this (fairly well referenced) Wikipedia article explains what fetus in fetu is:

Fetus in fetu (or fœtus in fœtu) is a developmental abnormality: a mass of tissue inside the body that more or less resembles a fetus. There are two theories of origin concerning fetus in fetu. One theory is that the mass begins as a normal fetus but becomes enveloped inside its twin. The other theory is that the mass is a highly developed teratoma. Fetus in fetu is estimated to occur in 1 in 500,000 live births.

It’s not quite as exciting as the foot found in the boys brain down in Colorado Springs (warning: very graphic photo [photo credit to the Denver Post]. DO NOT click if you are at all squeamish). But I was still pretty thrilled with my little discovery. My mature, and fully ripened, red pepper was carrying it’s own underdeveloped green pepper twin inside it. Of course I took pictures.

Red Pepper Teratoma (Inside)

And here is a picture of the with the fetus extracted.

Red Pepper Teratoma (Extracted)

Alas, teratoma peppers are not all that uncommon.

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Wet Panties

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For further research: Impact Of Wet Underwear On Thermoregulatory Responses And Thermal Comfort In The Cold.

In the wet condition 175 g of water was distributed in the underwear prior to the experiment. The test was done on eight men (Ta = 10°C, RH = 85%, Va < 01 m/s), and comprised a 60min resting period. Skin temperature, rectal temperature, and weight loss were recorded during the test. Total changes in body and clothing weight were measured separately. Furthermore, subjective ratings on thermal comfort and sensation were collected. The tests demonstrated the significant cooling effect of wet underwear on thermoregulatory responses and thermal comfort. Further, the tests showed that textile construction of underwear in a two-layer clothing ensemble has an effect on the evaporation rate from clothing during rest in the cold resulting in a significant difference in mean skin temperature. The thickness of the underwear has more of an influence on the thermoregulatory responses and thermal comfort, than the types of fibres tested.

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