Windmills in the Sky Generate More Power

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Windmills in the Sky Generate More Power

For many years people knew that wind can be used to generate energy, but no one was aware of the quantity of energy it could actually produce. In 2005 two scientists at Stanford University, Cristina Archer and Mark Jacobson, performed a detailed estimation based on already known models of air movement. However, they calculated the energy that could only be produced from winds blowing at an altitude of 80 meters. Their results showed that under perfect conditions the total energy would be around 72 trillion watts.

It is worth mentioning that last year the full electrical generating capacity of the U.S. was slightly above 1 trillion watts. Scientists came to a conclusion that this number is way below the potential. The speed of wind increases with the altitude. The power increases at the cube of wind speed, which means that the electrical generating capacity could reach at least 72 trillion watts. If a turbine blade was located a few miles up, it could produce up to 250 times the energy that the turbine generates on the ground.

Bryan Roberts, who works as an engineering professor at the University of Technology in Sydney, Australia, proposed an idea on generating energy from wind. His project is currently developed by Sky WindPower, an American company with headquarters in San-Diego. The project features kites with rotors that fly like a helicopter to altitudes of over a mile where winds are stronger. When the device arrives to the destination point in the sky, rotors switch to generating mode and transmit electricity down their tethers. In case the winds change their direction the flying electric generators (FEGs) follow them.

This project, which looks rather simple, is really not like anything that the energy infrastructure creates.

A team of scientists at Worcester Polytechnic Institute in Massachusetts worked on a similar project - inexpensive energy kites that fly on low altitudes. These kites are somewhat different from the FEGs because the do not carry generators into the sky and then send current down the string. Instead they move up and down several hundreds of feet in the air, producing pulses in the tether that provides power to the generator stored on the ground.

 

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Body Heat to Power Electronic Devices Soon

Using body heat instead of batteries to power various devices is no longer a dream. German scientists developed a circuit that can be used to produce electricity from body heat.


A new way of generating electricity from body heat was discovered by researchers at the Fraunhofer Institute for Integrated Circuits IIS in Germany together with scientists at the Fraunhofer Institute for Physical Measurement Techniques (IPM) and the Fraunhofer Institute for Manufacturing Engineering and Applied Materials Research IFAM.

Their method is based on the principle of thermoelectric generators (TEG)produced from semiconductor elements. The temperature difference between hot and cold environment contributes to generation of electricity with the help of TEGs.

Usually, the difference of several tens of degrees is necessary to generate electricity. But when comparing body temperature and environment temperature, the difference is just a few degrees which is enough to generate only low voltages. In order to produce electricity for electronic devices one or two volts are necessary, while TEG extract about 200 millivolts.

The scientists developed a completely new way of generating electricity, creating circuits that work on 200 millivolts. This discovery led to creation of electronic system that produces energy from body heat. Researchers are making further improvements for various applications.

Electricity would be possible to produce anywhere a temperature difference takes place.

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Scientists Find Cells Coordinate Gene Activity with FM Bursts

How a cell achieves the coordinated control of a number of genes at the same time, a process that's necessary for it to regulate its own behavior and development, has long puzzled scientists.

Michael Elowitz, an assistant professor of biology and applied physics at the California Institute of Technology (Caltech), along with Long Cai, a postdoctoral research scholar at Caltech, and graduate student Chiraj Dalal, have discovered a surprising answer. Just as human engineers control devices ranging from dimmer switches to retrorockets using pulsed--or frequency modulated (FM)--signals, cells tune the expression of groups of genes using discrete bursts of activation.

Elowitz, who is also a Bren Scholar and an investigator with the Howard Hughes Medical Institute, and his colleagues discovered this process by combining mathematical and computational modeling with experiments on individual living cells. The scientists looked specifically at the molecular changes within simple baker's yeast (Saccharomyces cerevisiae) cells after exposure to excess calcium, which increases in concentration in cells in response to stressful conditions such as high salt levels, alkaline pH, and cell wall damage.

The scientists tracked that response using a protein called Crz1 labeled with a green fluorescent tag. Crz1 is stimulated in response to high calcium levels and activates genes that help protect the cell. The glowing of the fluorescent marker allowed Elowitz and colleagues to visualize the movement of Crz1 as it travelled within the cell from the cytoplasm into the cell nucleus and out again into the cytoplasm. Using time-lapse microscopy, they created "movies" of that movement.

"This allowed us to discover that the localization of the Crz1 protein was randomly switching between nucleus and cytoplasm," says Elowitz. The researchers were able to see the Crz1 protein moving in a coherent fashion. "What's striking is that most of the Crz1 molecules jump in or out of the nucleus together. The typical length of time they stay in the nucleus is constant, but how often they all jump into the nucleus depends on the signal--in this case, calcium. Thus, you can say that calcium levels are 'encoded' in the frequency of these nuclear localization bursts."

Using mathematical modeling, the researchers were then able to determine that the burst-like movement most likely serves to coordinate gene expression. The process is similar to how a dimmer switch on household lights works. Such knobs control the fraction of time that current, which switches on and off rapidly, goes to the light fixture. Rotating the knob varies the relative amount of time that current is on or off, and the resulting intensity of the light is proportional to the fraction of time the switch is on. "The idea of controlling a system by flipping it between extreme 'on' and 'off' states at different rates, rather than fine-tuning it, is sometimes called 'bang bang' regulation," Elowitz says.

"Similarly, the amount of gene expression in the Crz1 system is proportional to the fraction of time that Crz1 is localized to the nucleus. Unlike the dimmer, it is the frequency--how often there are nuclear localization pulses--not the duration of these pulses, which the cell regulates. But in both cases, it is the fraction of time that the system is 'on' that is being controlled," Elowitz says.

One key point, he adds, "is that as the rate of these jumps changes, all genes are affected in the same way. One way of thinking about it is that each 'jump' activates all of the genes, albeit at different levels. Therefore, the expression of each gene is individually proportional to the number or frequency of these jumps, and they are all proportional to each other as well."

The behavior of Crz1 is believed to control roughly 100 target genes. However, Elowitz and his colleagues suspect that frequency-modulated movement may be a common strategy for gene regulation. "Because the problem of coregulation of genes is very general, we suspect frequency modulation may be widespread across many genes, organisms, and cell types. We're now trying to determine how general this phenomenon is by looking at what other genes and cell types use this type of system," he says.

The paper, "Frequency-modulated nuclear localization bursts coordinate gene regulation," was published in the September 25 issue of the journal Nature. The work was supported by grants from the National Institutes of Health and the Packard Foundation.

Provided by Caltech