The Number of Different Binary Functions Generated by NK-Kauffman Networks and the Emergence of Genetic Robustness

We determine the average number $\vartheta (N, K)$, of \textit{NK}-Kauffman networks that give rise to the same binary function. We show that, for $N \gg 1$, there exists a connectivity critical value $K_c$ such that $\vartheta(N,K) \approx e^{\phi N}$ ($\phi > 0$) for $K < K_c$ and $\vartheta(N,K) \approx 1$ for $K > K_c$. We find that $K_c$ is not a constant, but scales very slowly with $N$, as $K_c \approx \log_2 \log_2 (2N / \ln 2)$. The problem of genetic robustness emerges as a statistical property of the ensemble of \textit{NK}-Kauffman networks and impose tight constraints in the average number of epistatic interactions that the genotype-phenotype map can have.Comment: 4 figures 18 page

Theoretical characterization of a model of aragonite crystal orientation in red abalone nacre

Nacre, commonly known as mother-of-pearl, is a remarkable biomineral that in red abalone consists of layers of 400-nm thick aragonite crystalline tablets confined by organic matrix sheets, with the $(001)$ crystal axes of the aragonite tablets oriented to within $\pm$ 12 degrees from the normal to the layer planes. Recent experiments demonstrate that this orientational order develops over a distance of tens of layers from the prismatic boundary at which nacre formation begins. Our previous simulations of a model in which the order develops because of differential tablet growth rates (oriented tablets growing faster than misoriented ones) yield patterns of tablets that agree qualitatively and quantitatively with the experimental measurements. This paper presents an analytical treatment of this model, focusing on how the dynamical development and eventual degree of order depend on model parameters. Dynamical equations for the probability distributions governing tablet orientations are introduced whose form can be determined from symmetry considerations and for which substantial analytic progress can be made. Numerical simulations are performed to relate the parameters used in the analytic theory to those in the microscopic growth model. The analytic theory demonstrates that the dynamical mechanism is able to achieve a much higher degree of order than naive estimates would indicate.Comment: 20 pages, 3 figure

Higgs-photon associated production at eeˉe\bar{e} colliders

We present complete analytical expressions for the amplitudes of the process $e\bar{e}\rightarrow H\gamma$. The calculation is performed using nonlinear gauges, which significantly simplifies both the actual analytical calculation and the check of its gauge invariance. After comparing our results with a previous numerical calculation, we extend the range of Higgs masses and center of mass energies to those appropriate to LEP 200 and a future linear collider.Comment: To appear in PRD. 18 pages latex, uses REVTEX; 5 postscript figure

Cloning, expression, and localization of a novel γ-adaptin-like molecule

AbstractWe describe the cloning, expression, and localization of γ2-adaptin, a novel isoform of γ-adaptin. The predicted human and mouse γ2-adaptin proteins are ∼90 kDa and 64.4% and 61.7% identical to γ-adaptin, respectively. γ2-Adaptin was localized to the Golgi, its localization distinct from γ-adaptin. The membrane association of γ- and γ2-adaptin could further be distinguished by differential sensitivity to the fungal metabolite brefeldin A, γ2-adaptin binding being insensitive to drug treatment. Together, these results suggest that γ2-adaptin plays a role in membrane transport distinct from that played by γ-adaptin

Chandra Observations of the Faintest Low-Mass X-ray Binaries

There exists a group of persistently faint galactic X-ray sources that, based on their location in the galaxy, high L_x/L_opt, association with X-ray bursts, and absence of low frequency X-ray pulsations, are thought to be low-mass X-ray binaries (LMXBs). We present results from Chandra observations for eight of these systems: 4U 1708-408, 2S 1711-339, KS 1739-304, SLX 1735-269, GRS 1736-297, SLX 1746-331, 1E 1746.7-3224, and 4U 1812-12. Locations for all sources, excluding GRS 1736-297, SLX 1746-331, and KS 1739-304 (which were not detected) were improved to 0.6" error circles (90% confidence). Our observations support earlier findings of transient behavior of GRS 1736-297, KS 1739-304, SLX 1746-331, and 2S 1711-339 (which we detect in one of two observations). Energy spectra for 4U 1708-408, 2S 1711-339, SLX 1735-269, 1E 1746.7-3224, and 4U 1812-12 are hard, with power law indices typically 1.4-2.1, which are consistent with typical faint LMXB spectra.Comment: 15 pages, 3 figures. Accepted by Ap

Hard X-ray Bursts Recorded by the IBIS Telescope of the INTEGRAL Observatory in 2003-2009

To find X-ray bursts from sources within the field of view of the IBIS/INTEGRAL telescope, we have analysed all the archival data of the telescope available at the time of writing the paper (the observations from January 2003 to April 2009). We have detected 834 hard (15-25 keV) X-ray bursts, 239 of which were simultaneously recorded by the JEM-X/INTEGRAL telescope in the standard X-ray energy range. More than 70% of all bursts (587 events) have been recorded from the well-known X-ray burster GX 354-0. We have found upper limits on the distances to their sources by assuming that the Eddington luminosity limit was reached at the brightness maximum of the brightest bursts.Comment: 18 pages, 2 figures, 2 table

A comparison of the illness beliefs of people with angina and their peers: a questionnaire study

BACKGROUND: What people believe about their illness may affect how they cope with it. It has been suggested that such beliefs stem from those commonly held within society . This study compared the beliefs held by people with angina, regarding causation and coping in angina, with the beliefs of their friends who do not suffer from angina. METHODS: Postal survey using the York Angina Beliefs Questionnaire (version 1), which elicits stress attributions and misconceived beliefs about causation and coping. This was administered to 164 people with angina and their non-cohabiting friends matched for age and sex. 132 people with angina and 94 friends completed the questionnaire. RESULTS: Peers are more likely than people with angina to believe that angina is caused by a worn out heart (p <0.01), angina is a small heart attack (p = 0.02), and that it causes permanent damage to the heart (p <0.001). Peers were also more likely to believe that people with angina should take life easy (p <0.01) and avoid exercise (p = 0.04) and excitement (p <0.01). CONCLUSIONS: The beliefs of the peer group about causation and coping in angina run counter to professional advice. Over time this may contribute to a reduction in patient concordance with risk factor reduction, and may help to create cardiac invalids

Twisted k-graph algebras associated to Bratteli diagrams

Given a system of coverings of k-graphs, we show that the cohomology of the resulting (k+1)-graph is isomorphic to that of any one of the k-graphs in the system. We then consider Bratteli diagrams of 2-graphs whose twisted C*-algebras are matrix algebras over noncommutative tori. For such systems we calculate the ordered K-theory and the gauge-invariant semifinite traces of the resulting 3-graph C*-algebras. We deduce that every simple C*-algebra of this form is Morita equivalent to the C*-algebra of a rank-2 Bratteli diagram in the sense of Pask-Raeburn-R{\o}rdam-Sims.Comment: 28 pages, pictures prepared using tik

Non-perturbative orientifold transitions at the conifold

After orientifold projection, the conifold singularity in hypermultiplet moduli space of Calabi-Yau compactifications cannot be avoided by geometric deformations. We study the non-perturbative fate of this singularity in a local model involving O6-planes and D6-branes wrapping the deformed conifold in Type IIA string theory. We classify possible A-type orientifolds of the deformed conifold and find that they cannot all be continued to the small resolution. When passing through the singularity on the deformed side, the O-plane charge generally jumps by the class of the vanishing cycle. To decide which classical configurations are dynamically connected, we construct the quantum moduli space by lifting the orientifold to M-theory as well as by looking at the superpotential. We find a rich pattern of smooth and phase transitions depending on the total sixbrane charge. Non-BPS states from branes wrapped on non-supersymmetric bolts are responsible for a phase transition. We also clarify the nature of a Z_2 valued D0-brane charge in the 6-brane background. Along the way, we obtain a new metric of G_2 holonomy corresponding to an O6-plane on the three sphere of the deformed conifold.Comment: 76 pages, references adde