Finite temperature effective action, AdS_5 black holes, and 1/N expansion

We propose a phenomenological matrix model to study string theory in AdS_5 \times S_5 in the canonical ensemble. The model reproduces all the known qualitative features of the theory. In particular, it gives a simple effective potential description of Euclidean black hole nucleation and the tunnelling between thermal AdS and the big black hole. It also has some interesting predictions. We find that there exists a critical temperature at which the Euclidean small black hole undergoes a Gross-Witten phase transition. We identify the phase transition with the Horowitz-Polchinski point where the black hole horizon size becomes comparable to the string scale. The appearance of the Hagedorn divergence of thermal AdS is due to the merger of saddle points corresponding to the Euclidean small black hole and thermal AdS. The merger can be described in terms of a cusp (A_3) catastrophe and divergences at the perturbative string level are smoothed out at finite string coupling using standard techniques of catastrophe theory.Comment: 41 pages, 3 eps figures, uses harvma

The ArcB Leucine Zipper Domain Is Required for Proper ArcB Signaling

The Arc two-component system modulates the expression of numerous genes in response to respiratory growth conditions. This system comprises ArcA as the response regulator and ArcB as the sensor kinase. ArcB is a tripartite histidine kinase whose activity is regulated by the oxidation of two cytosol-located redox-active cysteine residues that participate in intermolecular disulfide bond formation. Here, we report that the ArcB protein segment covering residues 70–121, fulfills the molecular characteristics of a leucine zipper containing coiled coil structure. Also, mutational analyses of this segment reveal three different phenotypical effects to be distributed along the coiled coil structure of ArcB, demonstrating that this motif is essential for proper ArcB signaling

A study of nuclear effect in F3F_3 structure function in the deep inelastic ν(νˉ)\nu(\bar\nu) reactions in nuclei

We study nuclear effect in the $F^A_3(x)$ structure function in the deep inelastic neutrino reactions on iron by taking into account Fermi motion, binding, target mass correction, shadowing and anti-shadowing corrections. Calculations have been done in a local density approximation using relativistic nuclear spectral functions which include nucleon correlations for nuclear matter. Results for $F^A_3(x)$ have been compared with the results reported at NuTeV and also with some of the older experiments reported in the literature.Comment: 4Pages, 4 Figures To appear in the AIP Proceedings of the Sixth International Workshop on Neutrino-Nucleus Interactions in the Few-GeV Region, May 18th - 22nd, 2009 held at Sitges, Barcelona (Spain

Efecto del gen BMP15 sobre la distribución del tipo de parto en ovejas Rasa Aragonesa

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Relationship between the effects of the BMP15 gene and the polygenic effects on prolificacy in the rasa Aragonesa sheep breed

Los efectos del gen BMP15, localizado en el cromosoma X, sobre la media y la variabilidad de la prolificidad fueron estimados en la población Rasa Aragonesa, donde se analizaron 918.956 partos de ovejas de distintos genotipos (heterocigotas para el alelo FecXR o ROA®; y no portadoras). En primer lugar, se utilizaron modelos umbral que incluían o no el efecto del gen para estimar el efecto del genotipo BMP15 y su contribución a la variabilidad genética de la prolificidad en esta población. También se utilizaron otros dos modelos para estimar las interacciones entre el genotipo y los poligenes, así como el efecto del genotipo sobre la variabilidad de la prolificidad. Todos los análisis se hicieron con el programa ASReml. El efecto del genotipo sobre la media fue de 0,32 corderos adicionales por parto cuando el alelo ROA® se encontraba presente. Debido a que durante muchos años la selección por prolificidad en esta población se ha llevado a cabo desconociendo la presencia de esta mutación, los animales selectos portadores tienen un valor genético poligénico residual más bajo que los no portadores. No se encontró interacción significativa entre el genotipo y los efectos poligénicos sobre el valor genético. Aunque la interacción entre el genotipo y el conjunto de umbrales fue significativa, la diferencia entre ambos genotipos en la varianza de la prolificidad sobre la escala observada a una prolificidad media dada es escasa y muy poco relevanteThe effects of the BMP15 gene, located on the X chromosome, on mean prolificacy and its variability, were estimated in the Rasa Aragonesa sheep population through the analysis of 918,956 lambing records from ewes of different genotypes (FecXR or ROA® heterozygous ewes; and non-carrier ewes). Threshold models including or not the gene effect were first run to determine the effect of the BMP15 genotype and its importance in the total genetic variability of prolificacy. Two other models were also run to estimate the interaction between the BMP15 genotype and the polygenic background, as well as the effect of the genotype on the variability prolificacy. All the models were run using the ASReml software. The effect of the presence of the ROA® allele of the BMP15 gene on the mean prolificacy was 0.32 extra lambs per lambing. Due to the selection on prolificacy performed during many years in this population ignoring the presence of this major gene, animals carrying the mutation were found to have lower remaining polygenic estimated breeding values than non-carrier animals, and there was no interaction between the BMP15 genotype and the polygenic background. Although the interaction between the genotype and the set of thresholds was significant, the resulting between-genotypes difference of variance of prolificacy on the observed scale, at a similar mean litter size, was very low and not relevantPublishe

Triple-Decker Pentalene Complex of Iron and Cobalt

In [1(1,2,3,3a,6a-ƞ)-1,4-dihydropentalenyl][µ-1](1,2,3,3a,-6a-ƞ):2(3a,4,5,6,6a-ƞ)-pentalene][2(ƞ5)-pentamethylcyclopentadienyl]cobaltiron, [CoFe(C8H7)Cp*(C8H6)] (Cp*=C10H15), the Cp*-Co and (C8H7)-Fe moieties reside on opposite sides of the fused bridging pentalene ring system

Evidence for a Mixed Mass Composition at the ‘ankle’ in the Cosmic-ray Spectrum

We report a first measurement for ultrahigh energy cosmic rays of the correlation between the depth of shower maximum and the signal in the water Cherenkov stations of air-showers registered simultaneously by the fluorescence and the surface detectors of the Pierre Auger Observatory. Such a correlation measurement is a unique feature of a hybrid air-shower observatory with sensitivity to both the electromagnetic and muonic components. It allows an accurate determination of the spread of primary masses in the cosmic-ray flux. Up till now, constraints on the spread of primary masses have been dominated by systematic uncertainties. The present correlation measurement is not affected by systematics in the measurement of the depth of shower maximum or the signal in the water Cherenkov stations. The analysis relies on general characteristics of air showers and is thus robust also with respect to uncertainties in hadronic event generators. The observed correlation in the energy range around the ‘ankle’ at lg(E/eV) = 18.5–19.0 differs significantly from expectations for pure primary cosmic-ray compositions. A light composition made up of proton and helium only is equally inconsistent with observations. The data are explained well by a mixed composition including nuclei with mass A \u3e 4. Scenarios such as the proton dip model, with almost pure compositions, are thus disfavoredas the sole explanation of the ultrahigh-energy cosmic-ray flux at Earth

The MIDAS experiment: A prototype for the microwave emission of Ultra-High Energy Cosmic Rays

Recent measurements suggest that extensive air showers initiated by ultra-high energy cosmic rays (UHECR) emit signals in the microwave band of the electromagnetic spectrum caused by the collisions of the free-electrons with the atmospheric neutral molecules in the plasma produced by the passage of the shower. Such emission is isotropic and could allow the detection of air showers with 100% duty cycle and a calorimetric-like energy measurement, a significant improvement over current detection techniques. We have built MIDAS (MIcrowave Detection of Air Showers), a prototype of microwave detector, which consists of a 4.5 m diameter antenna with a cluster of 53 feed-horns in the 4 GHz range. The details of the prototype and first results will be presented.Comment: To appear in the proceedings of 12th Topical Seminar on Innovative Particle and Radiation Detectors (IPRD10), Siena, Italy, 7 - 10 June 201