Thermodynamic and Tunneling Density of States of the Integer Quantum Hall Critical State

We examine the long wave length limit of the self-consistent Hartree-Fock approximation irreducible static density-density response function by evaluating the charge induced by an external charge. Our results are consistent with the compressibility sum rule and inconsistent with earlier work that did not account for consistency between the exchange-local-field and the disorder potential. We conclude that the thermodynamic density of states is finite, in spite of the vanishing tunneling density of states at the critical energy of the integer quantum Hall transition.Comment: 5 pages, 4 figures, minor revisions, published versio

Non-equilibrium phase transitions in biomolecular signal transduction

We study a mechanism for reliable switching in biomolecular signal-transduction cascades. Steady bistable states are created by system-size cooperative effects in populations of proteins, in spite of the fact that the phosphorylation-state transitions of any molecule, by means of which the switch is implemented, are highly stochastic. The emergence of switching is a nonequilibrium phase transition in an energetically driven, dissipative system described by a master equation. We use operator and functional integral methods from reaction-diffusion theory to solve for the phase structure, noise spectrum, and escape trajectories and first-passage times of a class of minimal models of switches, showing how all critical properties for switch behavior can be computed within a unified framework

Improved Orbital Parameters And Transit Monitoring For HD 156846b

HD 156846b is a Jovian planet in a highly eccentric orbit (e = 0.85) with a period of 359.55 days. The pericenter passage at a distance of 0.16 AU is nearly aligned to our line of sight, offering an enhanced transit probability of 5.4% and a potentially rich probe of the dynamics of a cool planetary atmosphere impulsively heated during close approach to a bright star (V = 6.5). We present new radial velocity (RV) and photometric measurements of this star as part of the Transit Ephemeris Refinement and Monitoring Survey. The RV measurements from the Keck-High Resolution Echelle Spectrometer reduce the predicted transit time uncertainty to 20 minutes, an order of magnitude improvement over the ephemeris from the discovery paper. We photometrically monitored a predicted transit window under relatively poor photometric conditions, from which our non-detection does not rule out a transiting geometry. We also present photometry that demonstrates stability at the millimagnitude level over its rotational timescale

Host Star Properties And Transit Exclusion For The HD 38529 Planetary System

The transit signature of exoplanets provides an avenue through which characterization of exoplanetary properties may be undertaken, such as studies of mean density, structure, and atmospheric composition. The Transit Ephemeris Refinement and Monitoring Survey is a program to expand the catalog of transiting planets around bright host stars by refining the orbits of known planets discovered with the radial velocity technique. Here we present results for the HD 38529 system. We determine fundamental properties of the host star through direct interferometric measurements of the radius and through spectroscopic analysis. We provide new radial velocity measurements that are used to improve the Keplerian solution for the two known planets, and we find no evidence for a previously postulated third planet. We also present 12 years of precision robotic photometry of HD 38529 that demonstrate the inner planet does not transit and the host star exhibits cyclic variations in seasonal mean brightness with a timescale of approximately six years

Regulatory Processes That Control Haploid Expression of Salmon Sperm mRNAs

Objective  Various stages of mRNA processing are necessary for functionally important genes required during late-stage sperm differentiation. Protein–RNA complexes form that edit, stabilize, store, deliver, localize and regulate translation of sperm mRNAs. These regulatory processes are often directed by recognition sequence elements and the particular composition of the proteins associated with the mRNAs. Previous work has shown that the cAMP response element modulator (CREM), estrogen receptor-alpha (ERα) and forkhead box L2A (FOXL2A) proteins are present in late-stage salmon sperm. Here we investigate whether these and other regulatory proteins might control processing of mRNAs not expressed until the haploid stage of development. We also examine regulatory processes that prepare and present mRNAs that generate unique products essential for differentiating sperm (i.e. for flagellar assembly and function). Results  We provide evidence for potential sperm-specific recognition elements in 5′-untranslated regions (utrs) that may bind CREM, ERα, FOXL2A, Y-box and other proteins. We show that changes within the 5′-utrs and open reading frames of some sperm genes lead to distinct protein termini that may provide specific interfaces necessary for localization and function within the paternal gamete

Parental environments and interactions with conspecifics alter salinity tolerance of offspring in the annual medicago truncatula

Summary: Based on expectations of the stress-gradient hypothesis for conspecific interactions, stress-sensitive genotypes may be able to persist in stressful environments when positive interactions between individuals occur under stressful environments. Additionally, we test how parental environmental effects alter responses to stress and outcomes of conspecific interactions in stress. While the stress-gradient hypothesis focuses on plant growth, earlier flowering may provide stress avoidance in short-lived organisms. We studied responses to soil salinity and conspecific neighbour using genotypes of Medicago truncatula (Fabaceae) originating from saline or non-saline environments, utilizing seeds from parental plants grown in saline or non-saline environments. During the early stages of reproduction, we quantified leaf number, as a measure of vegetative growth, and number of flowers, as a measure of early reproduction potential. Based on leaf counts, non-saline genotypes were better competitors than saline-origin genotypes and benefited from neighbouring plants in saline environments. This positive interaction was detected only when seeds were matured on parental plants grown in non-saline environments. Saline-origin genotypes displayed greater salinity tolerance in early flowering than non-saline genotypes. Plants with neighbours had greater early flowering, regardless of origin, consistent with facilitative interactions in stressful environments. Transgenerational plastic responses influenced neighbouring plant interactions on plant growth, and results suggest that facilitative interactions may be transient only persisting for one generation. However, earlier flowering of non-saline genotypes when grown with a neighbouring plant is consistent with facilitative interactions resulting in reproductive benefits in saline environments, if earlier flowering is favoured in saline environments. Synthesis. Adaptation to stressful environments allows tolerant genotypes to persist in these environments. Less appreciated is that stress-sensitive genotypes lacking such adaptations may persist in stressful environments via positive interactions with other individuals. Thus, positive interactions between individuals may explain the persistence of stress-sensitive genotypes within a population adapted to stressful environments. © 2013 British Ecological Society