31,120 research outputs found
Functional Bias and Spatial Organization of Genes in Mutational Hot and Cold Regions in the Human Genome
The neutral mutation rate is known to vary widely along human chromosomes,
leading to mutational hot and cold regions. We provide evidence that categories
of functionally-related genes reside preferentially in mutationally hot or cold
regions, the size of which we have measured. Genes in hot regions are biased
toward extra-cellular communication (surface receptors, cell adhesion, immune
response, etc.) while those in cold regions are biased toward essential
cellular processes (gene regulation, RNA processing, protein modification,
etc.). From a selective perspective, this organization of genes could minimize
the mutational load on genes that need to be conserved and allow fast evolution
for genes that must frequently adapt. We also analyze the effect of gene
duplication and chromosomal recombination, which contribute significantly to
these biases for certain categories of hot genes. Overall, our results show
that genes are located non-randomly with respect to hot and cold regions,
offering the possibility that selection acts at the level of gene location in
the human genome.Comment: 17 pages, 6 figures, 2 tables. accepted to PLOS Biology, Feb. 2004
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Photoproduction of Pentaquark and Chiral Symmetry Restoration in Hot and Dense Medium
The photoproduction rate of pentaquark is calculated in a hot and
dense medium. At high temperature and density, due to the restoration of chiral
symmetry, photoproduction energy threshold is increased. Above the thresold the
production cross section is strongly enhanced.Comment: 5 pages, 3 figure
A 2 TeV , Supersymmetry, and the Higgs Mass
A recent ATLAS search for diboson resonances and a CMS search for
resonances which both show excesses with significance around 3 sigma have
generated interest in gauge extensions of the Standard Model with a
mass around 2 TeV. We investigate the possibility that an gauge
extension of the MSSM compatible with an explanation of the diboson anomaly
might give rise to a significant enhancement of the Higgs mass above the MSSM
tree level bound due to non-decoupling
D-terms. This model contains a vector-like charge -1/3 singlet quark
for each generation which mixes significantly with the doublet
quarks, affecting the phenomenology. We find that it is possible to
achieve , and this requires that the
mass is close to 3 TeV.Comment: 18 pages + appendices, 6 figure
Dyonic (A)dS Black Holes in Einstein-Born-Infeld Theory in Diverse Dimensions
We study Einstein-Born-Infeld gravity and construct the dyonic (A)dS planar
black holes in general even dimensions, that carry both the electric charge and
magnetic fluxes along the planar space. In four dimensions, the solution can be
constructed with also spherical and hyperbolic topologies. We study the black
hole thermodynamics and obtain the first law. We also classify the singularity
structure.Comment: Latex, 21 pages, typos corrected and references adde
Doping dependent charge injection and band alignment in organic field-effect transistors
We have studied metal/organic semiconductor charge injection in
poly(3-hexylthiophene) (P3HT) field-effect transistors with Pt and Au
electrodes as a function of annealing in vacuum. At low impurity dopant
densities, Au/P3HT contact resistances increase and become nonohmic. In
contrast, Pt/P3HT contacts remain ohmic even at far lower doping. Ultraviolet
photoemission spectroscopy (UPS) reveals that metal/P3HT band alignment shifts
dramatically as samples are dedoped, leading to an increased injection barrier
for holes, with a greater shift for Au/P3HT. These results demonstrate that
doping can drastically alter band alignment and the charge injection process at
metal/organic interfaces.Comment: 5 pages, 4 figure
USING THE SPATIAL STATISTICS APPROACH TO ANALYZE YIELD RISK POOLING IN THE US
Risk theory tells us if an insurer can effectively pool a large number of individuals to reduce the total risk, he then can provide the insurance by charging a premium close to the actuarially fair rate. There is, however, a common belief that the risk can be effectively pooled only when the random loss is independent, so that crop insurance markets cannot survive without government subsidy because crop yields are not independent among growers. In this paper, we take a a spatial statistics approach to examine the effectiveness of risk pooling for crop insurance under correlation. We develop a method for evaluating the effectiveness of risk pooling under correlation and apply the method to three major crops in the US: wheat, soybeans and corn. The empirical study shows that yields for the three crops present zero or negative correlation when two counties are far apart, which complies with a weaker condition than independence, finite-range positive dependency. The results show that effective risk pooling is possible and reveal a high possibility of a private crop insurance market in the US.Risk and Uncertainty,
A potential approach to solutions for set games
Concerning the solution theory for set games, the paper introduces a new solution by allocating, to any player, the items (taken from an universe) that are attainable for the player, but can not be blocked (by any coalition not containing the player). The resulting value turns out to be an utmost important concept for set games to characterize the family of set game solutions that possess a so-called potential representation (similar to the potential approaches applied in both physics and cooperative game theory). An axiomatization of the new value, called Driessen--Sun value, is given by three properties, namely one type of an efficiency property, the substitution property and one type of a monotonocity property
Knowledge Transformations between Frame Systems and RDB Systems
For decades, researchers in knowledge representation (KR) have argued for and against various choices in KR formalisms, such as Rules, Frames, Semantic nets, and Formal logic. In this paper, we present a set of transformations that can be used to move knowledge across two fundamentally different KR formalisms: Frame-based systems and Relational database systems (RDBs). We also describe partial implementations of these transformations for a specific pair of such systems: Protégé and the Postgres RDB system
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