Influence of the photon - neutrino processes on magnetar cooling

The photon-neutrino processes $\gamma e^{\pm} \to e^{\pm} \nu \bar \nu$, $\gamma \to \nu \bar \nu$ and $\gamma \gamma \to \nu \bar \nu$ are investigated in the presence of a strongly magnetized and dense electron-positron plasma. The amplitudes of the reactions $\gamma e^{\pm} \to e^{\pm} \nu \bar \nu$ and $\gamma \gamma \to \nu \bar \nu$ are obtained. In the case of a cold degenerate plasma contributions of the considering processes to neutrino emissivity are calculated. It is shown that contribution of the process $\gamma \gamma \to \nu \bar \nu$ to neutrino emissivity is supressed in comparision with the contributions of the processes $\gamma e^{\pm} \to e^{\pm} \nu \bar \nu$ and $\gamma \to \nu \bar \nu$. The constraint on the magnetic field strength in the magnetar outer crust is obtained.Comment: 8 pages, LaTeX, 2 PS figures, based on the talk presented by D.A. Rumyantsev at the XV International Seminar Quarks'2008, Sergiev Posad, Moscow Region, May 23-29, 2008, to appear in the Proceeding

Exciton-carrier coupling in a metal halide perovskite nanocrystal assembly probed by two-dimensional coherent spectroscopy

The surface chemistry and inter-connectivity within perovskite nanocrystals play a critical role in determining the electronic interactions. They manifest in the Coulomb screening of electron-hole correlations and the carrier relaxation dynamics, among other many-body processes. Here, we characterize the coupling between the exciton and free carrier states close to the band-edge in a ligand-free formamidinium lead bromide nanocrystal assembly via two-dimensional coherent spectroscopy. The optical signatures observed in this work show: (i) a nonlinear spectral lineshape reminiscent of Fano-like interference that evidences the coupling between discrete electronic states and a continuum, (ii) symmetric excited state absorption cross-peaks that suggest the existence of a coupled exciton-carrier excited state, and (iii) ultrafast carrier thermalization and exciton formation. Our results highlight the presence of coherent coupling between exciton and free carriers, particularly in the sub-100 femtosecond timescales

A New Force Field of Formamide and the Effect of the Dielectric Constant on Miscibility

Current force fields underestimate significantly the dielectric constant of formamide at standard conditions. We present a derivation of an accurate potential for formamide, with a functional form based on the OPLS/AA force field. Our procedure follows the approach introduced by Salas et al. (J. Chem. Theory Comput. 2015, 11, 683−693) that relies on <i>ab initio</i> calculations and molecular dynamics simulations. We consider several strategies to derive the atomic charges of formamide. We find that the inclusion of polarization effects in the quantum mechanical computations is essential to obtain reliable force fields. By varying the atomic charges and the Lennard-Jones parameters describing the dispersion interactions in the OPLS/AA force field, we derive an optimum set of parameters that provides accurate results for the dielectric constant, surface tension, and bulk density of liquid formamide in a wide range of thermodynamic states. We test the transferability of our parameters to investigate liquid/liquid mixtures. We have chosen as case study an equimolar mixture of formamide and hexan-2-one. This mixture involves two fluids with very different polar characteristics, namely, large differences in their dielectric constants and their performance as solvents. The new potential predicts a liquid/liquid phase separation, in good agreement with experimental data, and highlights the importance of the correct parametrization of the pure liquid phases to investigate liquid mixtures. Finally, we examine the microscopic origin of the observed inmiscibility between formamide and hexa-2-one

Classification of phase transitions of finite Bose-Einstein condensates in power law traps by Fisher zeros

We present a detailed description of a classification scheme for phase transitions in finite systems based on the distribution of Fisher zeros of the canonical partition function in the complex temperature plane. We apply this scheme to finite Bose-systems in power law traps within a semi-analytic approach with a continuous one-particle density of states $\Omega(E)\sim E^{d-1}$ for different values of $d$ and to a three dimensional harmonically confined ideal Bose-gas with discrete energy levels. Our results indicate that the order of the Bose-Einstein condensation phase transition sensitively depends on the confining potential.Comment: 7 pages, 9 eps-figures, For recent information on physics of small systems see "http://www.smallsystems.de

Comparación ultrasonográfica transvaginal y transrectal de la dinámica folicular en ondas sucesivas de llamas (Lama glama)

The ovarian follicular dynamics monitored by transrectal (TR) and transvaginal (TV) routes in successive waves was studied in 10 llamas older than 4 years, multiparous, without calves at foot, body condition of 3.0, during a period of 90 days in the reproductive season. The Sonostar SS8® ultrasound equipment was used with a linear transducer for transrectal examination and endocavitary microconvex transducer for transvaginal examination, both with a frequency of 6.5 MHz. The inter-wave interval was 20 ± 4.4 and 22.5 ± 5.3 via TR and VT, respectively; the number of follicles per cohort was 5.21 ± 0.92 and 6.38 ± 1.26 for TR and TV, respectively (p=0.0011); the maximum diameter of follicles was 12.49 ± 3.57 mm for TR and 13.56 ± 3.91 mm for TV; the growth rate was 0.70 ± 0.35 and 0.67 ± 0.32 mm/day for TR and TV, respectively. The regression equation for the ratio of the maximum follicular diameter and duration of follicular wave via TR was y=0.89766x+6.5554 (R²=0.423) and for the TV route y=0.8466x+10.184 (R²=0.479). The duration of the follicular phases was similar between both techniques except for the dominance phase (10.2±3.19 days for TR and 8.67±2.46 for TV, p=0.0418). The relationship between the follicular diameter and the number of follicles detected showed a low negative correlation (R²=-0.0827 for TV and R²=-0.0876 for TR). In conclusion, the transvaginal endocavitary transducer makes it possible to determine with greater precision the characteristics of llama follicular dynamics in their recruitment, dominance and regression phases with overlapping of follicular waves as an important characteristic.La dinámica folicular ovárica monitoreada por vía transrectal (TR) y transvaginal (TV) en ondas sucesivas en llamas fue estudiada en 10 llamas con más de 4 años, multíparas, sin cría, estado corporal de 3.0, durante un periodo de 90 días en la época reproductiva. Se utilizó el ecógrafo Sonostar SS8® con un transductor lineal para el examen transrectal y transductor microconvexo endocavitario para el examen transvaginal, ambos con frecuencia de 6.5 MHz. El intervalo inter-onda fue de 20±4.4 y 22.5±5.3 por vía TR y TV, respectivamente; el número de folículos por cohorte fue 5.21±0.92 y 6.38±1.26 para TR y TV, respectivamente (p=0.0011); el diámetro máximo de folículos fue 12.49±3.57 mm para TR y 13.56±3.91 mm para TV; la tasa de crecimiento fue de 0.70±0.35 y 0.67±0.32 mm/día para TR y TV, respectivamente. La ecuación de regresión para relación del diámetro máximo folicular y duración de onda folicular vía TR fue de y=0.89766x+6.5554 (R²=0.423) y para la vía TV de y=0.8466x+10.184 (R²=0.479). La duración de las fases foliculares fue similar entre ambas técnicas con excepción de la fase de dominancia (10.2±3.19 días para TR y 8.67±2.46 para TV, p=0.0418). La relación entre el diámetro folicular y número de folículos detectados presentó una correlación negativa baja (R²=-0.0827 para TV y R²=-0.0876 para TR). En conclusión, el transductor endocavitario transvaginal permite determinar con mayor precisión las características de dinámica folicular en llamas en sus fases de reclutamiento, dominancia y regresión con sobreposición de ondas foliculares como característica importante.The ovarian follicular dynamics monitored by transrectal (TR) and transvaginal (TV) routes in successive waves was studied in 10 llamas older than 4 years, multiparous, without calves at foot, body condition of 3.0, during a period of 90 days in the reproductive season. The Sonostar SS8® ultrasound equipment was used with a linear transducer for transrectal examination and endocavitary microconvex transducer for transvaginal examination, both with a frequency of 6.5 MHz. The inter-wave interval was 20 ± 4.4 and 22.5 ± 5.3 via TR and VT, respectively; the number of follicles per cohort was 5.21 ± 0.92 and 6.38 ± 1.26 for TR and TV, respectively (p=0.0011); the maximum diameter of follicles was 12.49 ± 3.57 mm for TR and 13.56 ± 3.91 mm for TV; the growth rate was 0.70 ± 0.35 and 0.67 ± 0.32 mm/day for TR and TV, respectively. The regression equation for the ratio of the maximum follicular diameter and duration of follicular wave via TR was y=0.89766x+6.5554 (R²=0.423) and for the TV route y=0.8466x+10.184 (R²=0.479). The duration of the follicular phases was similar between both techniques except for the dominance phase (10.2±3.19 days for TR and 8.67±2.46 for TV, p=0.0418). The relationship between the follicular diameter and the number of follicles detected showed a low negative correlation (R²=-0.0827 for TV and R²=-0.0876 for TR). In conclusion, the transvaginal endocavitary transducer makes it possible to determine with greater precision the characteristics of llama follicular dynamics in their recruitment, dominance and regression phases with overlapping of follicular waves as an important characteristic

Preliminary analysis of the genetic variability of two natural beds of the Scallop Euvola ziczac (Linnaeus, 1758) in Brazil

Euvola ziczac (formerly Pecten ziczac), a simultaneous hermaphroditic scallop was heavily fished in Brazil between 1972 and 1980. The production peaked in 1980 with 8,800 tons and was followed by the total collapse of the resource. In order to investigate the possible loss of genetic variability of the stock associated to overfishing and self-fertilization, the polymorphism of phosphoglucomutase (PGM) and glucose phosphate isomerase (GPI) was analyzed by electrophoresis of the adductor muscle of scallops from São Francisco (26° 20.583S; 48° 16.507W) and Bom Abrigo (25° 28.735S; 47° 37.621W) beds; the southern and northern extremes of the scallop fishing ground, respectively. Animals from São Francisco showed a strong deficiency of heterozygosity for GPI and PGM. In addition, PGM showed *exclusive alleles for each bed. Such results coupled with other information about the species suggested the following hypothesis: a) the stock was a metapopulation with at least two populations; b) some reproductive isolation might be occurring which might be influenced by conditions of larval transport and by the extremely low densities of scallops; c) presently, the stock seemed to be mostly maintained through self-fertilization; d) São Francisco could constitute a source-area, contributing with larvae and recruits to Bom Abrigo and other areas; e) both beds were suffering a genetic homogenization more evident in São Francisco. Such hypothesis needed to be investigated in order to furnish guidelines for future programs of recovery and management of the resource.info:eu-repo/semantics/publishedVersio