Sunday, June 13, 2010

Selected readings 6/13/10

Interesting reading and news items.

Please leave some comments that indicate which articles you find most interesting or that identify topics you would like to read about, and I will try to include more articles of a similar nature in the future

These items are also bookmarked at my Diigo account.

Anticipating the first steps beyond the Standard Model
Physicists’ knowledge of elementary particles is encapsulated in the Standard Model of particle physics, which currently describes almost everything we’ve seen. Yet there is compelling evidence that the Standard Model cannot be the complete description of nature. For example, despite all of its successes, the Standard Model describes only 20 percent of the mass of the Universe. Eighty percent of the mass is known as “dark matter,” which we have never directly observed and know next to nothing about. [Symmetry Breaking, 6/3/10]

Could DZero result point to multiple Higgses?
What caused the DZero result’s large deviation from Standard Model predictions is just as earth-shaking a mystery. The answer could point to the completion of the Standard Model, missing only the theorized Higgs boson particle, or the creation of a new story line for a host of new particles in the saga of how matter in the universe behaves. In their quest for a full explanation, scientists debate whether they are simply missing a chapter in the Standard Model or if they need a sequel that goes beyond the model, potentially including extra dimensions or a theory called supersymmetry that would double the number of known particles. [Symmetry Breaking, 6/4/10]

What is a "law of physics," anyway?
Why should nature be governed by laws? Why should those laws be expressible in terms of mathematics? Why should they be formulated within space and time? These were the questions posed at a fascinating workshop two weeks ago at the Perimeter Institute, the sequel to a workshop held at Arizona State University in December 2008. ... The bottom line is that the organizers had better start planning on more sequels, because the questions seem as intractable as ever. [Scientific American, 6/4/10]

What a shoddy piece of work is man
The human body is certainly no masterpiece of intelligent planning. The eye's retina, for instance, is wired back to front so that the wiring has to pass back through the screen of light receptors, imposing a blind spot. Now John Avise, an evolutionary geneticist at the University of California at Irvine, has catalogued the array of clumsy flaws and inefficiencies at the fundamental level of the genome. His paper ... throws down the gauntlet to advocates of Intelligent design, the pseudo-scientific face of religious creationism. What Intelligent Designer, Avise asks, would make such a botch? [Nature News, 5/3/10]

Illuminating the brain
Now though, advances in a five-year-old field called optogenetics are convincing these scientists to crack open molecular-biology textbooks. Using a hybrid of genetics, virology and optics, the techniques involved enable researchers to instantaneously activate or silence specific groups of neurons within circuits with a precision that electrophysiology and other standard methods do not allow. Systems neuroscientists have longed for such an advance, which allows them their first real opportunity to pick apart the labyrinthine jumble of cell types in a circuit and test what each one does. [Nature News, 5/5/10]

The code within the code
95% of the human genome is alternatively spliced, and that changes in this process accompany many diseases. But no one knew how to predict which form of a particular gene would be expressed in a given tissue. "The splicing code is a problem that we've been bashing our heads against for years," says Burge. "Now we finally have the technologies we need." [Nature News, 5/5/10]

European and Asian genomes have traces of Neanderthal
The genomes of most modern humans are 1–4% Neanderthal — a result of interbreeding with the close relatives that went extinct 30,000 years ago, according to work by an international group of researchers. [Nature News, 5/6/10]

Linux vs. Genome in Network Challenge
A comparison of the networks formed by genetic code and the Linux operating system has given insight into the fundamental differences between biological and computational programming. The shapes are very dissimilar, reflecting the evolutionary parameters of each process. Biology is driven by random mutations and natural selection. Software is an act of intelligent design. [Wired, 5/5/10]

Complex Life Traced to Ancient Gene Parasites
Mysterious gene structures called introns that help make complex organisms possible are descended from DNA parasites that infested bacteria billions of years ago, according to a new study. ... The findings fit the notion that group II introns flourished in the early Earth’s heat, and were ultimately co-opted into their hosts’ genomes. [Wired, 6/9/10]

The Magical Mystery Tour
Cassini, the first spacecraft to orbit Saturn, has revealed intricate details of the gas giant planet and its moons -- but many mysteries remain. Six years ago, the Cassini spacecraft began orbiting Saturn and taking detailed images of its ring and many moons. While the Cassini-Huygens mission has helped answer questions about this planetary system, it also has revealed new mysteries for scientists to puzzle over. [, 5/5/10]

Peptides may hold 'missing link' to life
Scientists have discovered that simple peptides can organize into bi-layer membranes. The finding suggests a "missing link" between the pre-biotic Earth's chemical inventory and the organizational scaffolding essential to life. [, 5/6/10]

Physicists study how moral behaviour evolved
A statistical-physics-based model may shed light on the age-old question "how can morality take root in a world where everyone is out for themselves?" Computer simulations by an international team of scientists suggest that the answer lies in how people interact with their closest neighbours rather than with the population as a whole. [, 5/5/10]

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