16 hours ago • 3 notes • Reblog

Beard trend is ‘guided by evolution’

The more beards there are, the less attractive they become - giving clean-shaven men a competitive advantage, say scientists in Sydney, Australia.

When “peak beard” frequency is reached, the pendulum swings back toward lesser-bristled chins - a trend we may be witnessing now, the scientists say.

Their study has been published in the Royal Society journal Biology Letters.

In the experiment, women and men were asked to rate different faces with “four standard levels of beardedness”.

Both beards and clean-shaven faces became more appealing when they were rare.

The pattern mirrors an evolutionary phenomenon - “negative frequency-dependent sexual selection”, or to put it more simply “an advantage to rare traits”.

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16 hours ago • 4 notes • Reblog


(Source: capaldiblog)

1 day ago • 259 notes • Reblog

Nutrient-Rich Forests May Absorb More Carbon
Apr 14, 2014 01:49 PM EDT By Jaleesa Baulkman, UniversityHerald Reporter (j.baulkman@universityherald.com)

The ability of forests to absorb carbon from atmosphere depends on nutrients available in the forest soils, according to a recent study.

An international team of researchers found that forests growing in fertile soils with ample nutrients are able to sequester about 30 percent of the carbon that they take up during photosynthesis. In contrast, forests growing in nutrient-poor soils may retain only 6% of that carbon. The rest is returned to the atmosphere as respiration.

"In general, nutrient-poor forests spend a lot of energy — carbon — through mechanisms to acquire nutrients from the soil, whereas nutrient-rich forests can use that carbon to enhance biomass production," Marcos Fernandez-Martinez, first author of the paper and researcher at the Center for Ecological Research and Forestry Applications (CREAF) and the Spanish National Research Council (CSIC), said in a statement.

Researchers noted that until now, scientific models to predict forest carbon sequestration on a global scale had only considered the amount of nitrogen in the soil and did not take into account other constraints such as phosphorus or the pH of the soil, which is related to the availability of nutrients.

The new study includes both those factors as well as nitrogen availability, in an analysis synthesizing data from 92 forests in different climate zones on the planet. Tropical rainforests had the poorest nutrient availability, and the lowest efficiency for carbon sequestration, the researchers found.

Researcher said the difference in efficiency of carbon absorption could be due to several factors. For one thing, plants in nutrient-poor soils devote more energy to locating nutrients.

"When plants are in nutrient poor conditions, they send out more roots and produce chemicals that can help dissolve nutrients from the soil. This takes energy, though, and so the plants produce less biomass," Michael Obersteiner, program director of the Ecosystems Services and Management Program Director at the International Institute for Applied Systems Analysis, said in a statement.

Furthermore, the study showed that nutrient-rich ecosystems also generally have more stable ground organic material, which is not easily degraded, and thus retains more carbon.

source: University Herald

Smallest speed jump of pulsar caused by billions of superfluid vortices
This result is important to our understanding of the behavior of matter under extreme conditions.
By NOVA, Amsterdam  |  Published: Monday, April 14, 2014

A team of astronomers, including Danai Antonopoulou and Anna Watts from the University of Amsterdam (Uva), has discovered that sudden speed jumps in the rotational velocity of pulsars have a minimum size and that they are caused not by the unpinning and displacement of just one sub-surface superfluid vortex, but by billions. This result is important to our understanding of the behavior of matter under extreme conditions.

Pulsars are rotating neutron stars — remnants of massive stars that end their lives in supernova explosions. They act like cosmic lighthouses whose beams sweep through the universe. Their rotational velocity decreases in time, but can suddenly increase in rare events called glitches. These glitches are caused by the unpinning and displacement of vortices that connect the crust with the mixture of particles containing superfluid neutrons beneath the crust.

The team of astronomers discovered that the glitches of the Crab Pulsar always involve a decrease in the rotational period of at least 0.055 nanosecond. The Crab Pulsar was one of the first pulsars to be discovered and has been observed almost daily with the 42-foot telescope at the Jodrell Bank Observatory over the last 29 years. The huge amount of data makes this object the best choice to study glitches.

The smallest glitch is likely to be caused by the unpinning and movement of billions of vortices. “Surprisingly, no one tried to determine a lower limit to glitch size before,” said Antonopoulou. “Many assumed that the smallest glitch would be caused by a single vortex unpinning. The smallest glitch is clearly much larger than we expected.”

“Astronomers would of course like to know whether the smallest glitches of other pulsars are also caused by billions of vortices. The next step is to sift through the data of other pulsars and to continue observing,” said Cristobal Espinoza from the Institute of Astrophysics Pontificia Universidad Catolica in Chile.

“By comparing the observations with theoretical predictions, we learn about the behavior of matter in these exotic objects,” said Watts. “The precise cause of glitches is still a mystery to us, and this result offers a new challenge to theorists.”

source: Astronomy Magazine

2 days ago • 14 notes • Reblog

Scientists regenerate organ in mice in world-first breakthrough
Results on rebuilt thymus in very old mice potentially open way for helping humans to live longer

Scientists have regenerated a living organ for the first time, potentially opening the way for life-lengthening human therapies.

A team at Edinburgh University’s medical research centre for regenerative medicine managed to rebuild the thymus of very old mice, re-establishing the health of the organ seen in younger creatures.

Scientists reactivated a natural mechanism that shuts down with age to rejuvenate the thymus, an organ near the heart that produces important infection-fighting white blood cells, called T cells.

By targeting a protein called FOXN1, which helps control how genes are switched on, the function of the thymus was restored. Treated mice began to make more T cells.

The research, published in the journal Development, found the thymus grew to twice its previous size, and the recovery appeared sustainable. Scientists now will look into any unintended consequences of increasing FOXN1.

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5 days ago • 5 notes • Reblog