Meditation Beats Dance for Harmonizing Body and Mind

Meditation Beats Dance for Harmonizing Body and Mind

  8:32:00 PM    Science Lover

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The body is a dancer's instrument, but is it attuned to the mind? A new study from the University of California, Berkeley, suggests that professional ballet and modern dancers are not as emotionally in sync with their bodies as are people who regularly practice meditation.

UC Berkeley researchers tracked how closely the emotions of seasoned meditators and professional dancers followed bodily changes such as breathing and heart rates.

They found that dancers who devote enormous time and effort to developing awareness of and precise control over their muscles -- a theme coincidentally raised in the new ballet movie "Black Swan" -- do not have a stronger mind-body connection than do most other people.

By contrast, veteran practitioners of Vipassana or mindfulness meditation -- a technique focused on observing breathing, heartbeat, thoughts and feelings without judgment -- showed the closest mind-body bond, according to the study recently published in the journal Emotion.


"We all talk about our emotions as if they are intimately connected to our bodies -- such as the 'heartache of sadness' and 'bursting a blood vessel' in anger," said Robert Levenson, a UC Berkeley psychology professor and senior author of the study. "We sought to precisely measure how close that connection was, and found it was stronger for meditators."

The results offer new clues in the mystery of the mind-body connection. Previous studies have linked the dissociation of mind and body to various medical and psychiatric diseases.

"Ever have the experience of getting home from work and realizing you have a blistering headache?" said Jocelyn Sze, a doctoral student in clinical science at UC Berkeley and the lead author of the study. "The headache probably built up throughout the day, but you might have been intentionally ignoring it and convincing yourself that you felt fine so that you could get through the demands of the day."

Increasingly, mindfulness meditation is being used to treat physical and psychological problems, researchers point out. "We believe that some of these health benefits derive from meditation's capacity to increase the association between mind and body in emotion," Levenson said.

For the experiment, the researchers recruited volunteers from meditation and dance centers around the San Francisco Bay Area and via Craigslist. The study sample consisted of 21 dancers with at least two years of training in modern dance or ballet and 21 seasoned meditators with at least two years of Vipassana practice. A third "control group" was made up of 21 moderately active adults with no training in dance, meditation, Pilates or professional sports.

Participants, who ranged in age from 18 to 40, were wired with electrodes to measure their bodily responses while they watched emotionally charged scenes from movies and used a rating dial to indicate how they were feeling.

Although all participants reported similar emotional reactions to the film clips, meditators showed stronger correlations between the emotions they reported feeling and the speed of their heartbeats. Surprisingly, the differences between dancers and the control group were minimal.

Researchers theorize that dancers learn to shift focus between time, music, space, and muscles and achieve heightened awareness of their muscle tone, body alignment and posture.

"These are all very helpful for becoming a better dancer, but they do not tighten the links between mind and body in emotion," Levenson said.

By contrast, meditators practice attending to "visceral" body sensations, which makes them more attuned to internal organs such as the heart. "These types of visceral sensations are a primary focus of Vipassana meditation, which is typically done sitting still and paying attention to internal sensations," Sze said.

The study was published in the December 2010 issue of Emotion. In addition to Sze and Levenson, coauthors are UC Berkeley psychologists Joyce W. Yuan and Anett Gyurak, who is currently a postdoctoral fellow at Stanford University.

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Trapping Sunlight With Silicon Nanowires

Trapping Sunlight With Silicon Nanowires

  4:38:00 PM    Science Lover

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Solar cells made from silicon are projected to be a prominent factor in future renewable green energy equations, but so far the promise has far exceeded the reality. While there are now silicon photovoltaics that can convert sunlight into electricity at impressive 20 percent efficiencies, the cost of this solar power is prohibitive for large-scale use. Researchers with the Lawrence Berkeley National Laboratory (Berkeley Lab), however, are developing a new approach that could substantially reduce these costs. The key to their success is a better way of trapping sunlight.

This photovoltaic cell is comprised of 36 individual arrays of silicon nanowires featuring radial p-n junctions. The color dispersion demonstrates the excellent periodicity over the entire substrate. (Credit: Photo from Peidong Yang)

"Through the fabrication of thin films from ordered arrays of vertical silicon nanowires we've been able to increase the light-trapping in our solar cells by a factor of 73," says chemist Peidong Yang, who led this research. "Since the fabrication technique behind this extraordinary light-trapping enhancement is a relatively simple and scalable aqueous chemistry process, we believe our approach represents an economically viable path toward high-efficiency, low-cost thin-film solar cells."

Yang holds joint appointments with Berkeley Lab's Materials Sciences Division, and the University of California Berkeley's Chemistry Department. He is a leading authority on semiconductor nanowires -- one-dimensional strips of materials whose width measures only one-thousandth that of a human hair but whose length may stretch several microns.

"Typical solar cells are made from very expensive ultrapure single crystal silicon wafers that require about 100 micrometers of thickness to absorb most of the solar light, whereas our radial geometry enables us to effectively trap light with nanowire arrays fabricated from silicon films that are only about eight micrometers thick," he says. "Furthermore, our approach should in principle allow us to use metallurgical grade or "dirty" silicon rather than the ultrapure silicon crystals now required, which should cut costs even further."

Yang has described this research in a paper published in the journal NANO Letters, which he co-authored with Erik Garnett, a chemist who was then a member of Yang's research group.

Generating Electricity from Sunlight

At the heart of all solar cells are two separate layers of material, one with an abundance of electrons that functions as a negative pole, and one with an abundance of electron holes (positively-charged energy spaces) that functions as a positive pole. When photons from the sun are absorbed, their energy is used to create electron-hole pairs, which are then separated at the interface between the two layers and collected as electricity.

Because of its superior photo-electronic properties, silicon remains the photovoltaic semiconductor of choice but rising demand has inflated the price of the raw material. Furthermore, because of the high-level of crystal purification required, even the fabrication of the simplest silicon-based solar cell is a complex, energy-intensive and costly process.

Yang and his group are able to reduce both the quantity and the quality requirements for silicon by using vertical arrays of nanostructured radial p-n junctions rather than conventional planar p-n junctions. In a radial p-n junction, a layer of n-type silicon forms a shell around a p-type silicon nanowire core. As a result, photo-excited electrons and holes travel much shorter distances to electrodes, eliminating a charge-carrier bottleneck that often arises in a typical silicon solar cell. The radial geometry array also, as photocurrent and optical transmission measurements by Yang and Garrett revealed, greatly improves light trapping.

"Since each individual nanowire in the array has a p-n junction, each acts as an individual solar cell," Yang says. "By adjusting the length of the nanowires in our arrays, we can increase their light-trapping path length."

While the conversion efficiency of these solar nanowires was only about five to six percent, Yang says this efficiency was achieved with little effort put into surface passivation, antireflection, and other efficiency-increasing modifications.

"With further improvements, most importantly in surface passivation, we think it is possible to push the efficiency to above 10 percent," Yang says.

Combining a 10 percent or better conversion efficiency with the greatly reduced quantities of starting silicon material and the ability to use metallurgical grade silicon, should make the use of silicon nanowires an attractive candidate for large-scale development.

As an added plus Yang says, "Our technique can be used in existing solar panel manufacturing processes."

This research was funded by the National Science Foundation's Center of Integrated Nanomechanical Systems.

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