Monday, December 21, 2009

Selected readings 12/20/09

Interesting reading and news items.

These items are also bookmarked at my Diigo account.


Mammogram Math
The panel of scientists advised that routine screening for asymptomatic women in their 40s was not warranted and that mammograms for women 50 or over should be given biennially rather than annually. The response was furious. Fortunately, both the panel’s concerns and the public’s reaction to its recommendations may be better understood by delving into the murky area between mathematics and psychology. [New York Times, 12/10/09]

Introns: A mystery renewed
The sequences of nonsense DNA that interrupt genes could be far more important to the evolution of genomes than previously thought. ... Scientists say introns are inserted into the genome far more frequently than current models predict. The scientists also found what appear to be "hot spots" for intron insertion -- areas of the genome where repeated insertions are more likely to occur. And surprisingly, the vast majority of intron DNA sequences the scientists examined were of unknown origin. [Indiana University, 12/10/09]

Science at the petascale: Roadrunner supercomputer results unveiled
The world's fastest supercomputer, Roadrunner, at Los Alamos National Laboratory has completed its initial "shakedown" phase doing accelerated petascale computer modeling and simulations of a variety of unclassified, fundamental science projects. [Physorg.com, 10/26/09]

Scientists use world's fastest supercomputer to model origins of the unseen universe
Understanding dark energy is the number one issue in explaining the universe, according to Salman Habib, of the Laboratory's Nuclear and Particle Physics, Astrophysics and Cosmology group. ... The model is one of the largest simulations of the distribution of matter in the universe, and aims to look at galaxy-scale mass concentrations above and beyond quantities seen in state-of-the-art sky surveys. [Physorg.com, 10/26/09]

A Delicate Balance of Sexual Identity
The difference between male and female is smaller than one might think--at least on a cellular level. Researchers have found that they can change ovary cells into testicular cells in mice by turning off a single gene. The discovery provides new insights into the evolution of sex differences. [ScienceNOW, 12/10/09]

One gene keeps ovaries female
Knocking down a single gene in an adult mouse makes ovaries develop the characteristics of a male gonad and produce testosterone, according to a study published today (December 10th) in Cell. The study suggests that the signal is required to maintain the female phenotype throughout adulthood. [The Scientist, 12/10/09]

How a new muon experiment can advance physics
In recent years, particle physicists have increasingly turned their attention to finding physics beyond the Standard Model description of the building blocks of matter and how they interact. ... Many theories exist to explain the origins of suspected “new physics” and extensions to the Standard Model, the current theoretical framework.A new Fermilab-based experiment, the Muon-to-Electron Conversion experiment, or Mu2e, could shine light on those gray areas. [Symmetry Breaking, 12/9/09]

New evidence links sirtuins and life extension
Ever since he first discovered the lifespan-extending effects of proteins called sirtuins 15 years ago, MIT Professor Leonard Guarente has been accumulating evidence to demonstrate a link between sirtuins and the effects of calorie restriction on lifespan. [MIT News, 12/15/09]

Higgs in space: Orbiting telescope could beat the LHC
Evidence for the Higgs boson could be pouring down upon us from deep space. If so, an orbiting space telescope could upstage the Large Hadron Collider in the search for the elusive particle. [New Scientist, 12/14/09]

P vs. NP -- The most notorious problem in theoretical computer science remains open
In a 2002 poll, 61 mathematicians and computer scientists said that they thought P probably didn’t equal NP, to only nine who thought it did — and of those nine, several told the pollster that they took the position just to be contrary. But so far, no one’s been able to decisively answer the question one way or the other. Frequently called the most important outstanding question in theoretical computer science, the equivalency of P and NP is one of the seven problems that the Clay Mathematics Institute will give you a million dollars for proving — or disproving. [Physorg.com, 10/29/09]

Study: Earth's polar ice sheets vulnerable to even moderate global warming
A new analysis of the geological record of the Earth's sea level, carried out by scientists at Princeton and Harvard universities and published in the Dec. 16 issue of Nature, employs a novel statistical approach that reveals the planet's polar ice sheets are vulnerable to large-scale melting even under moderate global warming scenarios. Such melting would lead to a large and relatively rapid rise in global sea level. [Physorg.com, 12/16/09]

High testosterone linked to miserly behaviour
If you're looking to haggle, steer clear of big, beefy salesmen. The same hormone responsible for their brawn may also reduce their generosity, new research suggests. "Our broad conclusion is that testosterone causes men essentially to be stingy," says Karen Redwine, a neuro-economist at Whittier College in California. [New Scientist, 10/26/09]

A Molecule of Motivation, Dopamine Excels at Its Task
People talk of getting their “dopamine rush” from chocolate, music, the stock market, the BlackBerry buzz on the thigh — anything that imparts a small, pleasurable thrill. Familiar agents of vice like cocaine, methamphetamine, alcohol and nicotine are known to stimulate the brain’s dopamine circuits, as do increasingly popular stimulants like Adderall and Ritalin. [New York Times, 10/26/09]


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