Sunday, August 02, 2009

Honesty - Will or Grace?

Patterns of neural activity associated with honest and dishonest moral decisions
What makes people behave honestly when confronted with opportunities for dishonest gain? Research on the interplay between controlled and automatic processes in decision making suggests 2 hypotheses: According to the “Will” hypothesis, honesty results from the active resistance of temptation, comparable to the controlled cognitive processes that enable the delay of reward. According to the “Grace” hypothesis, honesty results from the absence of temptation, consistent with research emphasizing the determination of behavior by the presence or absence of automatic processes. To test these hypotheses, we examined neural activity in individuals confronted with opportunities for dishonest gain. Subjects undergoing functional magnetic resonance imaging (fMRI) gained money by accurately predicting the outcomes of computerized coin-flips. In some trials, subjects recorded their predictions in advance. In other trials, subjects were rewarded based on self-reported accuracy, allowing them to gain money dishonestly by lying about the accuracy of their predictions. Many subjects behaved dishonestly, as indicated by improbable levels of “accuracy.” Our findings support the Grace hypothesis. Individuals who behaved honestly exhibited no additional control-related activity (or other kind of activity) when choosing to behave honestly, as compared with a control condition in which there was no opportunity for dishonest gain. In contrast, individuals who behaved dishonestly exhibited increased activity in control-related regions of prefrontal cortex, both when choosing to behave dishonestly and on occasions when they refrained from dishonesty. Levels of activity in these regions correlated with the frequency of dishonesty in individuals.

Some people were always honest and they showed no special brain activity, other people were sometimes dishonest and they did display increased brain activity. This doesn't really seem surprising. Which isn't to say that this experiment is trivial, far from it - it's fascinating. It would be interesting to see if there are unusual people who can perform dishonestly without registering any special brain activity. Presumably these people would be naturally good spys, poker players, etc.
See the web page of the Moral Cognition Lab at Harvard.
There's a discussion of the paper at this blog post: Angels and Demons.

Statistics - Levy Laws and 1/f noise

A unified and universal explanation for Lévy laws and 1/f noises
Lévy laws and 1/f noises are shown to emerge uniquely and universally from a general model of systems which superimpose the transmissions of many independent stochastic signals. The signals are considered to follow, statistically, a common—yet arbitrary—generic signal pattern which may be either stationary or dissipative. Each signal is considered to have its own random transmission amplitude and frequency. We characterize the amplitude-frequency randomizations which render the system output's stationary law and power-spectrum universal—i.e., independent of the underlying generic signal pattern. The classes of universal stationary laws and power spectra are shown to coincide, respectively, with the classes of Lévy laws and 1/f noises—thus providing a unified and universal explanation for the ubiquity of these classes of “anomalous statistics” in various fields of science and engineering.

Cosmic Impact at the Younger Dryas Boundary

Shock-synthesized hexagonal diamonds in Younger Dryas boundary sediments
The long-standing controversy regarding the late Pleistocene megafaunal extinctions in North America has been invigorated by a hypothesis implicating a cosmic impact at the Ållerød-Younger Dryas boundary or YDB (≈12,900 ± 100 cal BP or 10,900 ± 100 14C years). Abrupt ecosystem disruption caused by this event may have triggered the megafaunal extinctions, along with reductions in other animal populations, including humans. The hypothesis remains controversial due to absence of shocked minerals, tektites, and impact craters. Here, we report the presence of shock-synthesized hexagonal nanodiamonds (lonsdaleite) in YDB sediments dating to ≈12,950 ± 50 cal BP at Arlington Canyon, Santa Rosa Island, California. Lonsdaleite is known on Earth only in meteorites and impact craters, and its presence strongly supports a cosmic impact event ...


Structure-based discovery and description of plant and animal Helitrons
Helitrons are recently discovered eukaryotic transposons that are predicted to amplify by a rolling-circle mechanism. They are present in most plant and animal species investigated, but were previously overlooked partly because they lack terminal repeats and do not create target site duplications.

Plant genomes: Massive changes of the maize genome are caused by Helitrons
Helitrons are eukaryotic transposable elements recognized only recently by computer analysis of repetitive DNA sequences of Arabidopsis, rice and Caenorhabditis elegans (Kapitonov and Jurka, 2001). Helitrons are quite large (>10 kbp) but unlike virtually all other classes of transposable elements, Helitrons lack terminal repeats and do not duplicate host sequences during the insertion process. They insert within the host dinucleotide, AT.

Living Fossils?

Nine exceptional radiations plus high turnover explain species diversity in jawed vertebrates
The other main deviations from our constant-rate model are the prototypical ‘‘living fossil’’ lineages, old lineages with few extant species (17, 18). In our study, 3 living fossil lineages are notable for both their low rate of speciation and extremely low rates of extinction. These groups stand out in stark contrast to the rest of the vertebrate tree, which is characterized by high rates of both speciation and extinction (Fig. 2). This highlights one of the key challenges presented by living fossils to molecular based studies of extant diversity: although young species-rich groups can be explained by a transient increase in net diversification rates for a relatively short period, older species-poor groups require negligible rates of both speciation and extinction over tremendously long periods of time to explain their persistence. We note that all 3 slowly evolving lineages were historically more diverse than they are today.

Why are these groups called "living fossils"? They diverged a long time ago and they have few surviving species. Why does that lead anyone to believe that the modern organisms are similiar to ancient ones?

Sirtuins - enzymes which regulate lifespan?

Recent progress in the biology and physiology of sirtuins
The sirtuins are a highly conserved family of NAD+-dependent enzymes that regulate lifespan in lower organisms. Recently, the mammalian sirtuins have been connected to an ever widening circle of activities that encompass cellular stress resistance, genomic stability, tumorigenesis and energy metabolism. Here we review the recent progress in sirtuin biology, the role these proteins have in various age-related diseases and the tantalizing notion that the activity of this family of enzymes somehow regulates how long we live.

Electricity from Kites

Wind power: High hopes in Nature.
A vast supply of energy is racing around the planet far above the surface. Erik Vance meets the engineers trying to bring the power of high-altitude wind down to earth.

Helical Dirac fermions

A tunable topological insulator in the spin helical Dirac transport regime
Helical Dirac fermions—charge carriers that behave as massless relativistic particles with an intrinsic angular momentum (spin) locked to its translational momentum—are proposed to be the key to realizing fundamentally new phenomena in condensed matter physics

First observation of spin-helical Dirac fermions and topological phases in undoped and doped Bi2Te3 demonstrated by spin-ARPES spectroscopy
Electron systems that possess light-like dispersion relations or the conical Dirac spectrum, such as graphene and bismuth, have recently been shown to harbor unusual collective states in high magnetic fields. Such states are possible because their light-like electrons come in spin pairs that are chiral,which means that their direction of propagation is tied to a quantity called pseudospin that describes their location in the crystal lattice. An emerging direction in quantum materials research is the manipulation of atomic spin-orbit coupling to simulate the effect of a spin dependent magnetic field,in attempt to realize novel spin phases of matter. This effect has been proposed to realize systems consisting of unpaired Dirac cones that are helical, meaning their direction of propagation is tied to the electron spin itself, which are forbidden to exist in graphene or bismuth.

X Rays from Nanotubes

Nanotubes sharpen X-ray vision
Mini X-ray tubes could revolutionize radiotherapy — and airport baggage scanners.

Is the Toucan's Bill primarily a Heat Exchanger?

Heat Exchange from the Toucan Bill Reveals a Controllable Vascular Thermal Radiator
The toco toucan (Ramphastos toco), the largest member of the toucan family, possesses the largest beak relative to body size of all birds. This exaggerated feature has received various interpretations, from serving as a sexual ornament to being a refined adaptation for feeding. However, it is also a significant surface area for heat exchange. Here we show the remarkable capacity of the toco toucan to regulate heat distribution by modifying blood flow, using the bill as a transient thermal radiator. Our results indicate that the toucan's bill is, relative to its size, one of the largest thermal windows in the animal kingdom, rivaling elephants’ ears in its ability to radiate body heat.

Polarized Signalling in Animals

Many animals create striking visual effects not with pigments but with intricately structured materials. See how some scarab beetles produce their colorful appearence in Evolutionary Photonics with a Twist.

Pathological Science

Pathological Science is when investigators trick themselves into believing false results. There was a classic talk PATHOLOGICAL SCIENCE given by Irving Langmuir in 1953.

Did the Immune System Originate with a Virus?

The immune system has the incredible ability to create a vast number of very specific antibodies. In Immune System: Success Owed to a Virus? the author conjectures that the recombination process which generates so much variety may have originated with a virus.

Rare Venomous Mammal

The Solenodon is a very rare and strange little mammal, it is the only mammal that injects venom through its teeth like snakes. See Saving a Venomous Ghost in Science. The are kind of cute too, see Venomous mammal caught on camera.