Store Is Closed
Heat loss in an organism is proportional to the surface area, or the square of its linear dimensions; the larger the surface area, the greater the heat loss. If the tissues of all homeotherms were to generate heat uniformly, the overall generation of heat would be proportional to the mass of the organism, or the cube of its linear dimensions. In other words, the larger the organism, the more tissue to generate heat, and the more heat generated overall.
However, this is not the case. Smaller mammals must overcome the effects of a larger surface area by generating more heat per unit of mass. Consider the following passage in On Growth and Form:
The tissues of one mammal are much like those of another. We can hardly imagine the muscles of a small mammal to produce more heat (caeteris paribus) than those of a large ; and we begin to wonder whether it be not nervous excitation, rather than quality of muscular
May 21 2011 1:43:20 pm ESTTopics:
Unlike land animals, aquatic animals evolve under different constraints. The crushing weight of gravity is counterpoised by the buoyancy of the water. A neutrally buoyant organism is effected differently by increasing mass.
The available energy for an organism depends on its mass, or the cube of its linear dimensions, while the resistance to motion is opposed not by gravity, but by skin-friction against the water, which varies with the square of its linear dimensions.
However, the rate of supply of kinetic energy depends on the surface area of the lung. In other words, the rate of work tends to vary with the square of the linear dimensions.
Under these constraints, the muscles are able to exert a force proportional to the cube of the linear dimensions, while the supply of energy is proportional to the surface area of the lungs or the square of the linear dimensions.
Consider the following passage in On Growth and Form (30-33):
...As Galileo also saw,
May 19 2011 12:14:03 pm EST
I am in the May 19th edition of Spotlight News for My Travels with Eos.
If, ten years ago, I could look into the future, and only see the title of the article published about me in Spotlight News: ‘Living with Aliens,” I might have submitted myself to a mental institution…
However, if I was able to actually read the article, I would probably have been pretty happy, though I would probably consult a psychologist…
In any case, the article was well written and covered all the bases pretty well. Thank you Alyssa Jung and Spotlight News for featuring me.
Click image to view hi-rez jpeg of article:
May 19 2011 11:18:14 am ESTTopics:
It’s a cold an lonely world without a star to orbit, and recent observations indicate that there may be twice as many orphaned planets than there are stars in the galaxy.
From Scientific American: Two astronomical collaborations report in the May 19 Nature that they have located a population of 10 celestial objects, each with about the mass of Jupiter, with no detectable host star. By extrapolation, the study’s authors, from the Microlensing Observations in Astrophysics (MOA) collaboration and the Optical Gravitational Lensing Experiment (OGLE) collaboration, calculate that there should be almost twice as many such objects in the Milky Way as there are stars. Some of the newfound objects may simply orbit a star at a distance so great that their host star is not apparent, but the researchers estimate that most of them are indeed free-floating.
I just read an interesting article in Scientific American about the environmental impact of algae biofuel.
The article sites a recent study demonstrating that in the first life-cycle, algae production consumes more energy, has higher greenhouse gas emissions and uses more water than other biofuel sources, such as switchgrass, canola and corn.
Researchers from the University of Virginia’s Department of Civil and Environmental Engineering published their findings in the journal Environmental Science and Technology.
“From a life-cycle standpoint, algae are not nearly as desirable as you would think they are,” said Andres Clarens, a civil and environmental engineering professor at the University of Virginia and lead author of the paper.. “And that was surprising to us.”
The culprit, the researchers say, is fertilizer. All of the nutrients — nitrogen and phosphorus — needed
Is pond scum the new Texas tea?
With the price of oil and gasoline on the rise, algae may be poised to enter the market soon as an alternative to fossil fuels. One company, Sapphire Energy, plans to begin commercial production in 2012, and was featured in PBS’s Nightly Business Report.
According to Mike Mendez, V.P., technology, Sapphire Energy, the key is to think of algae as a commodity: “You can’t think like an industry where you’re making a high- end product. This is not a high-end product. This is a commodity. You have to start thinking like a farmer and I think that that’s the way that we needed to approach the problem. Think like a farmer.”
However, an algae farmer has a unique advantage: Algae can be grown in the desert with salt water.
Mendez notes Sapphire’s choice of land: “New Mexico has two of the things we need most. The amount of sunlight we get here is probably the best in the world, definitely within the United States. Under
May 18 2011 9:00:00 am ESTTopics:
Shape memory alloy is an alloy that “remembers” its original, cold-forged shape: returning the pre-deformed shape by heating. This material is a lightweight, solid-state alternative to conventional actuators such as hydraulic, pneumatic, and motor-based systems.
A shape memory spring, for example, can be pulled and twisted out of shape, and will almost instantly reform to its original shape when heated. The process can be repeated “over a million times,” According to Dr. Alan Taub, Vice President of GM’s Global Research & Development.
According to Dr. Taub, shape memory alloy will replace expensive motors, hydraulics, and pneumatic systems for simple processes, such as opening and closing louvers on a radiator or deploying a rear spoiler.
May 17 2011 5:00:00 pm ESTTopics:
I recently read an interesting article in The New York Times, analyzing the International Energy Agency’s (IEA) 2010 World Energy Outlook. According to the report, China’s economic development will be the single largest factor in pushing oil prices higher over the next quarter-century. At the same time, they may become the driving influence behind growth in renewable technology.
The IEA predicted that Chinese energy demand would soar 75 percent by 2035, accounting for more than a third of the growth in global consumption. While China today accounts for 17 percent of world demand for energy, it should account for 22 percent in 25 years.
Over the last decade, China’s energy demand has doubled. While China used only half as much energy as the United States in 2000, it surpassed the United States in 2009 as the world’s largest energy user. Despite their growth in consumption, the average Chinese consumer uses roughl
May 17 2011 11:37:05 am ESTTopics:
In a recent study, a single pluripotent stem cell from one planarian flatworm was inserted into another dying planarian flatworm. The single cell multiplied, differentiated, and ultimately replaced all the dying host’s tissues.
In the study, researchers led by Peter Reddien, Daniel Wagner and Irving Wang at MIT exposed flatworms to ionizing radiation, robbing their cells of their ability to divide and regenerate. Without the ability to grow new cells, the animal would slowly die. They spared cNeoblast cells, which are undifferentiated cells capable of dividing into specialized cells, and watched as those remaining cells divided to form large colonies of replac
Photo of the Day
May 16 2011 5:34:50 pm ESTTopics:
Flesh Fly. Compared with single-aperture eyes, compound eyes possess a very large view angle, and can detect fast movement and, in some cases, the polarization of light. To see with a resolution comparable to our single-aperture eyes, humans would require compound eyes which would each reach the size of their head.
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