Friday, February 19, 2010

Selected readings 2/19/10

Interesting reading and news items.

These items are also bookmarked at my Diigo account.

Searching ALL the Tevatron data for exotic physics
The majority of published particle physics papers involve looking for a very specific elementary particle process. They conclude by either showing that it exists or constraining limits on how often that process could possibly occur. But is there a way to take advantage of a collider’s whole data set and seeing if it is consistent with an expansive theoretical model, such as the Standard Model of particle physics? [Symmetry breaking, 2/13/10]

The Cosmological Constant and the Dark Sector
The dark sector refers to dark energy and dark matter, which are two distinct phenomena which seem to have no direct connection other than in name. In this post I am going to talk about the cosmological constant, dark energy, and look at some landmark literature on the subject. [The Astronomist, 2/7/10]

Physicists Solve Difficult Classical Problem with One Quantum Bit
Most research on quantum information systems has concentrated on models that use multiple quantum bits. In a new study, physicists have demonstrated how to solve a difficult classical problem that completely encapsulates a quantum model that requires only one quantum bit. The scientists, Gina Passante, et al., from the University of Waterloo in Ontario, Canada, have presented their experimental results for the quantum solution of the approximation of the Jones polynomial, which is a knot invariant. [, 1/8/10]

Quantum computer calculates exact energy of molecular hydrogen
In an important first for a promising new technology, scientists have used a quantum computer to calculate the precise energy of molecular hydrogen. This groundbreaking approach to molecular simulations could have profound implications not just for quantum chemistry, but also for a range of fields from cryptography to materials science. [, 1/10/10]

Warp-Speed Algebra: New Algorithm Does Algebra in a Snap
Quantum computers can do wondrous things: too bad they do not exist yet. That has not stopped physicists from devising new algorithms for the devices, which can calculate a lot faster than ordinary computers—in fact, exponentially faster, in quite a literal sense. Once quantum computers do become available, the algorithms could become a key part of applications that require number crunching, from engineering to video games. [Scientific American, 1/1/10]

Fermi telescope closes in on mystery of cosmic ray acceleration
The Large Area Telescope collaboration, led by KIPAC researchers Takaaki Tanaka, Uchiyama, and Hiroyasu Tajima, released the first image of a supernova remnant in the giga-electronvolt energy range (about 200 million times the energy of visible light). By revealing the spatial distribution of cosmic rays in the remnant, this result is a significant step toward definitively determining how cosmic rays are accelerated in supernova remnants. [Symmetry breaking, 1/7/10]

Do particle theorists have a blind spot?
Theorist Matthew Strassler from Rutgers University challenged particle theorists to not be too simple in their analyses. Most people would probably not claim that theoretical particle physics is too simple, but Strassler argued that nature is likely to be even more complicated than hpysicists expect. And if theorists only properly examine the simplest classes of models, where simple is a relative term, they might be led astray in interpreting future Large Hadron Collider data. [Symmetry breaking, 2/14/10]

How to Change A Skin Cell Into A Nerve Cell or Cellular Anarchy & The Great Leap Sideways
A team at Stanford's Institute for Stem Cell Biology & Regenerative Medicine, led by Marcus Wernig and graduate student Thomas Vierbuchen, recently announced that a combination of only three transcription factors that would change a skin cell into a nerve cell -- with no intermediate (undifferentiated) steps. [h+ Magazine, 2/7/10]

Imaging the Brain Better, Faster, Thinner
fMRI's a tool, an amazing one in a lot of ways, but like any tool it needs to be used well. Along with others, I've criticized various aspects of recent fMRI practice, but only because it's frustrating to see such a powerful tool not being used to its full potential. So I was very pleased by a recent paper by Sabatinelli et al, The Timing of Emotional Discrimination in Human Amygdala and Ventral Visual Cortex. The authors set out to test a hypothesis - that seeing an emotionally charged picture would activate the amygdala and the inferotemporal cortex (IT) before activating the extrastriate occipital cortex. [Neuroskeptic, 2/3/10]

Uncovering the Genetic Controls of Cellular Aging
A fascinating thing about DNA replication is that the actual process lacks the ability to replicate the very ends of chromosomes. That means chromosomes should get shorter with every round of cell division (DNA replication), but they remain more or less the same length, getting gradually shorter with aging. The natural shortening of chromosomes is refered to as cellular aging. So how do chromosomes maintain their ends if not by replication? [DNA Dude, 2/9/10]

God's will and beliefs are your own, not god's
According to these results believers project their own values and beliefs on their god (or gods) to a great extent, which could certainly help explain not only the great diversity and variability of religious belief and expression, but also the ambiguous nature of religious interpretation. [Ego sum Daniel, 1/27/10]

Hunting Fossil Viruses in Human DNA
The borna virus is at once obscure and grotesque. It can infect mammals and birds, but scientists know little about its effects on its victims. ... The virus now turns out to have an intimate bond with every person on Earth. In the latest issue of Nature, a team of Japanese and American scientists report that the human genome contains borna virus genes. The virus infected our monkey-like ancestors 40 million years ago, and its genes have been passed down ever since. [New York Times, 1/11/10]

The Origin of the Future: Death by Mutation?
The evolutionary biologist Michael Lynch has published a provocative paper (to mark his inauguration into the National Academy of Sciences) in which he makes another kind of forecast. Our future evolution, he warns, is going to lead to a devastating decline in our health. [The Loom, 1/7/10]

Spiral Galaxies Exist — But Why?
It's a minor miracle (and a topic of considerable debate) how all the spirals we see today managed to endure all that mayhem unscathed. "The formation of spirals is a problem," admits Christopher Conselice, a galaxy specialist at the University of Nottingham. "We don't know how they formed, or how they survive all those mergers." [Sky & Telescope, 2/16/10]

WMAP Refines "Precision Cosmology"
Without much public notice, the team running the Wilkinson Microwave Anisotropy Probe (WMAP) recently released results from the satellite's "seven-year data set," updating the five-year data released in 2008. ... The two more years of data have further beaten down the statistical uncertainties in the cosmic background map, allowing analysts to refine what it tells us about the cosmos as a whole. If the new, revised results didn't make much news, it's because they show modern cosmology to be steady on course. The better data only firm up confidence in what we already thought we knew. [Sky & Telescope, 2/14/10]

Cell phone radiation may fight Alzheimer's... in mice
The study examined the performance of mice that received a daily dose of radiation similar to that produced by cell phones, and found that, over a period of several months, their memory improved. When the same procedure was performed with mice engineered to be predisposed to Alzheimer's pathology, it was actually able to reverse some of the cognitive decline. [Nobel Intent, 1/6/10]

Zinc Fingers Could Be Key to Reviving Gene Therapy
The technique, which depends on natural agents called zinc fingers, may revive the lagging fortunes of gene therapy because it overcomes the inability to insert new genes at a chosen site. Other researchers plan to use the zinc finger technique to provide genetic treatments for diseases like bubble-boy disease, hemophilia and sickle-cell anemia. [New York Times, 12/28/09]

Climate change: No hiding place?
The fact that no record high happened in the 2000s does not mean that there was no warming over the decade—trends at scales coarser than the annual continued to point upwards, and other authorities suggest there have been record years during the period. Nor was the length of time without an annual record exceptional. Models simulating centuries of warming normally have the occasional decade in which no rise in surface temperatures is observed. [The Economist, 1/7/10]

Induced Pluripotent Stem Cells Fall Short of Potential Found in Embryonic Version
The act of reprogramming cells to make them as capable as ones from embryos apparently can result in aberrant cells that age and die abnormally, suggesting there is a long way to go to prove such cells are really like embryonic stem cells and can find use in therapies. [Scientific American, 2/11/10]

Pop Goes the Pulsar
One of the challenges of astrophysics is interpreting what we observe. Here on Earth we can set up experiments to test phenomena, but when it comes to the cosmos all we can do is sit back and watch. We've sent probes to the furthest regions of our solar system, but even that is just a tiny corner of the heavens. So how can we possibly know that there are galaxies light years away, or that the universe is billions of years old? The answer is that we take what we know about physics here and apply it to what we observe there. [Upon Reflection, 2/17/10]

Should Evolutionary Theory Evolve?
Some evolutionary biologists say that the body of knowledge concerning evolutionary processes has simply outgrown the confines of the Modern Synthesis, which was crafted before science had a strong grasp of genomics, molecular biology, developmental biology, and other, more recently derived disciplines, such as systems biology. [The Scientist, 1/1/10]

Violating Parity with Quarks and Gluons
Quarks and gluons interact in interesting ways, and in the many fluctuations that happen in these high-temperature collisions we can get “bubbles” that pick out a direction in space. In the presence of these bubbles, quarks treat left and right differently, even though they treat both directions exactly the same when they’re in empty space. [Cosmic Variance, 2/16/10]

RSS access:
Blog posts labeled "readings"
Items saved at Diigo


Links to this post:

Create a Link


Post a Comment

<< Home