10,748 research outputs found
The Modernization of EC Antitrust Policy. A Legal Cultural Revolution
regulation; competition policy; Treaty on European Union
Population genetics of translational robustness
Recent work has shown that expression level is the main predictor of a
gene’s evolutionary rate, and that more highly expressed genes evolve
slower. A possible explanation for this observation is selection for proteins
which fold properly despite mistranslation, in short selection for
translational robustness. Translational robustness leads to the somewhat
paradoxical prediction that highly expressed genes are extremely tolerant to
missense substitutions but nevertheless evolve very slowly. Here, we study a
simple theoretical model of translational robustness that allows us to gain
analytic insight into how this paradoxical behavior arises.Comment: 32 pages, 4 figures, Genetics in pres
Thermodynamics of Neutral Protein Evolution
Naturally evolving proteins gradually accumulate mutations while continuing
to fold to thermodynamically stable native structures. This process of neutral
protein evolution is an important mode of genetic change, and forms the basis
for the molecular clock. Here we present a mathematical theory that predicts
the number of accumulated mutations, the index of dispersion, and the
distribution of stabilities in an evolving protein population from knowledge of
the stability effects (ddG values) for single mutations. Our theory
quantitatively describes how neutral evolution leads to marginally stable
proteins, and provides formulae for calculating how fluctuations in stability
cause an overdispersion of the molecular clock. It also shows that the
structural influences on the rate of sequence evolution that have been observed
in earlier simulations can be calculated using only the single-mutation ddG
values. We consider both the case when the product of the population size and
mutation rate is small and the case when this product is large, and show that
in the latter case proteins evolve excess mutational robustness that is
manifested by extra stability and increases the rate of sequence evolution. Our
basic method is to treat protein evolution as a Markov process constrained by a
minimal requirement for stable folding, enabling an evolutionary description of
the proteins solely in terms of the experimentally measureable ddG values. All
of our theoretical predictions are confirmed by simulations with model lattice
proteins. Our work provides a mathematical foundation for understanding how
protein biophysics helps shape the process of evolution
Hawking radiation from decoherence
It is argued that the thermal nature of Hawking radiation arises solely due
to decoherence. Thereby any information-loss paradox is avoided because for
closed systems pure states remain pure. The discussion is performed for a
massless scalar field in the background of a Schwarzschild black hole, but the
arguments should hold in general. The result is also compared to and contrasted
with the situation in inflationary cosmology.Comment: 6 pages, to appear in Class. Quantum Gra
Dual Labour Markets and Menu Costs: Explaining the Cyclicality of Productivity and Wage Differentials
The conventional menu cost framework performs poorly with realistic labour supply elasticities; the menu costs required for price rigidity are very high and the welfare consequences of monetary disturbances are negligible. We show that the presence of dual labour markets greatly improves the performance of the framework both by reducing menu cost requirements and by boosting the welfare consequences. In addition, the introduction of dual labour markets provides an explanation of procyclical productivity and the shrinking of wage differentials during booms, in line with stylized facts on business cycles.
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