Random-phase approximation and its applications in computational chemistry and materials science

The random-phase approximation (RPA) as an approach for computing the electronic correlation energy is reviewed. After a brief account of its basic concept and historical development, the paper is devoted to the theoretical formulations of RPA, and its applications to realistic systems. With several illustrating applications, we discuss the implications of RPA for computational chemistry and materials science. The computational cost of RPA is also addressed which is critical for its widespread use in future applications. In addition, current correction schemes going beyond RPA and directions of further development will be discussed.Comment: 25 pages, 11 figures, published online in J. Mater. Sci. (2012

Kinetics of the hydrogen abstraction ·C2H5 + alkane → C2H6 + alkyl reaction class: an application of the reaction class transition state theory

This paper presents an application of the reaction class transition state theory (RC-TST) to predict thermal rate constants for hydrogen abstraction reactions at alkane by the C2H5 radical on-the-fly. The linear energy relationship (LER), developed for acyclic alkanes, was also proven to hold for cyclic alkanes. We have derived all RCTST parameters from rate constants of 19 representative reactions, coupling with LER and the barrier height grouping (BHG) approach. Both the RC-TST/LER, where only reaction energy is needed, and the RC-TST/BHG, where no other information is needed, can predict rate constants for any reaction in this reaction class with satisfactory accuracy for combustion modeling. Our analysis indicates that less than 50% systematic errors on the average exist in the predicted rate constants using either the RC-TST/LER or RC-TST/BHG method, while in comparison with explicit rate calculations, the differences are within a factor of 2 on the average. The results also show that the RC-TST method is not sensitive to the choice of density functional theory used

Reliability of OMERACT ultrasound elementary lesions in gout: results from a multicenter exercise

El Comité editorial o Consejo Asesor (Editorial), es un equipo de expertos en el campo de la revista.El objetivo de este estudio fue evaluar la confiabilidad de las definiciones de las medidas de resultado en reumatología (OMERACT) para las lesiones elementales de ultrasonido (EE. UU.) En la gota a través de un ejercicio de lectura de imágenes. Se recogieron imágenes de pacientes con gota (imágenes estáticas y videos). Como paso inicial, realizamos un ejercicio de lectura de imágenes con los expertos del Grupo de Estudio de la Liga Panamericana de Asociaciones de Reumatología (PANLAR) de Estados Unidos (n = 16). El siguiente paso consistió en un ejercicio basado en la web con la participación de mayor número de ecografistas (n = 63) de diferentes centros. Las imágenes se calificaron evaluando la presencia / ausencia de cualquier lesión elemental de EE. UU. Las confiabilidades entre lectores e intralectores se analizaron mediante coeficientes kappa. Los participantes fueron estratificados según su nivel de experiencia. En el primer ejercicio , los valores de kappa entre lectores fueron 0,45 para agregados, 0,57 para tofos, 0,69 para erosiones y 0,90 para doble contorno (DC). Los valores de kappa intralector fueron 0,86, 0,76, 0,80 y 0,90, respectivamente. El ejercicio basado en la webmostraron valores de kappa entre lectores para agregados, tofos, erosiones y DC de 0,42, 0,49, 0,69 y 0,79, respectivamente. Los valores de kappa intralector fueron 0,62, 0,69, 0,77 y 0,85, respectivamente. La confiabilidad no fue influenciada por el nivel de experiencia del ecografista. La confiabilidad de las nuevas definiciones de OMERACT US para las lesiones elementales en la gota varió de moderada a excelente, según el tipo de lesión

Dating Violence Victimization among Adolescents in Europe: Baseline Results from the Lights4Violence Project

Dating violence (DV) among adolescents is a public health issue because of its negative health consequences. In this study, we aimed to analyse the prevalence and the psychosocial and socioeconomic risk and protective factors associated DV among male and female adolescents in Europe. It was performed a cross-sectional study based on a non-probabilistic sample of 1555 students aged 13–16 years (2018–2019). The global prevalence of DV victimization was significantly greater among girls than boys (girls: 34.1%, boys: 26.7%; p = 0.012). The prevalence of DV in both girls and boys was greater for those over age 15 (girls: 48.5% p < 0.001; boys: 35.9%; p = 0.019). There was an increased likelihood of DV victimization among girls whose fathers did not have paid employment (p = 0.024), who suffered abuse in childhood, and reported higher Benevolent Sexism [PR (CI 95%): 1.01 (1.00–1.03)] and machismo [1.02 (1.00–1.05)]. In the case of boys, the likelihood of DV increased with abuse in childhood (p = 0.018), lower parental support [0.97 (0.96–0.99)], high hostile sexism scores (p = 0.019), lower acceptance of violence (p = 0.009) and high machismo (p < 0.001). Abuse in childhood was shown to be the main factor associated with being a victim of DV in both population groups, as well as sexism and machismo attitudes. These results may contribute to future DV prevention school programs for both, teenagers and children of elementary school age

The evolution of reproductive isolation in a simultaneous hermaphrodite, the freshwater snail Physa

<p>Abstract</p> <p>Background</p> <p>The cosmopolitan freshwater snail <it>Physa acuta </it>has recently found widespread use as a model organism for the study of mating systems and reproductive allocation. Mitochondrial DNA phylogenies suggest that <it>Physa carolinae</it>, recently described from the American southeast, is a sister species of <it>P. acuta</it>. The divergence of the <it>acuta/carolinae </it>ancestor from the more widespread <it>P. pomilia </it>appears to be somewhat older, and the split between a hypothetical <it>acuta/carolinae/pomilia </it>ancestor and <it>P. gyrina </it>appears older still.</p> <p>Results</p> <p>Here we report the results of no-choice mating experiments yielding no evidence of hybridization between <it>gyrina </it>and any of four other populations (<it>pomilia, carolinae</it>, Philadelphia <it>acuta</it>, or Charleston <it>acuta</it>), nor between <it>pomilia </it>and <it>carolinae</it>. Crosses between <it>pomilia </it>and both <it>acuta </it>populations yielded sterile F1 progeny with reduced viability, while crosses between <it>carolinae </it>and both <it>acuta </it>populations yielded sterile F1 hybrids of normal viability. A set of mate-choice tests also revealed significant sexual isolation between <it>gyrina </it>and all four of our other <it>Physa </it>populations, between <it>pomilia </it>and <it>carolinae</it>, and between <it>pomilia </it>and Charleston <it>acuta</it>, but not between <it>pomilia </it>and the <it>acuta </it>population from Philadelphia, nor between <it>carolinae </it>and either <it>acuta </it>population. These observations are consistent with the origin of hybrid sterility prior to hybrid inviability, and a hypothesis that speciation between <it>pomilia </it>and <it>acuta </it>may have been reinforced by selection for prezygotic reproductive isolation in sympatry.</p> <p>Conclusions</p> <p>We propose a two-factor model for the evolution of postzygotic reproductive incompatibility in this set of five <it>Physa </it>populations consistent with the Dobzhansky-Muller model of speciation, and a second two-factor model for the evolution of sexual incompatibility. Under these models, species trees may be said to correspond with gene trees in American populations of the freshwater snail, <it>Physa</it>.</p

Unprecedented within-species chromosome number cline in the Wood White butterfly Leptidea sinapis and its significance for karyotype evolution and speciation

Background: Species generally have a fixed number of chromosomes in the cell nuclei while between-species differences are common and often pronounced. These differences could have evolved through multiple speciation events, each involving the fixation of a single chromosomal rearrangement. Alternatively, marked changes in the karyotype may be the consequence of within-species accumulation of multiple chromosomal fissions/fusions, resulting in highly polymorphic systems with the subsequent extinction of intermediate karyomorphs. Although this mechanism of chromosome number evolution is possible in theory, it has not been well documented. Results: We present the discovery of exceptional intraspecific variability in the karyotype of the widespread Eurasian butterfly Leptidea sinapis. We show that within this species the diploid chromosome number gradually decreases from 2n = 106 in Spain to 2n = 56 in eastern Kazakhstan, resulting in a 6000 km-wide cline that originated recently (8,500 to 31,000 years ago). Remarkably, intrapopulational chromosome number polymorphism exists, the chromosome number range overlaps between some populations separated by hundreds of kilometers, and chromosomal heterozygotes are abundant. We demonstrate that this karyotypic variability is intraspecific because in L. sinapis a broad geographical distribution is coupled with a homogenous morphological and genetic structure. Conclusions: The discovered system represents the first clearly documented case of explosive chromosome number evolution through intraspecific and intrapopulation accumulation of multiple chromosomal changes. Leptidea sinapis may be used as a model system for studying speciation by means of chromosomally-based suppressed recombination mechanisms, as well as clinal speciation, a process that is theoretically possible but difficult to document. The discovered cline seems to represent a narrow time-window of the very first steps of species formation linked to multiple chromosomal changes that have occurred explosively. This case offers a rare opportunity to study this process before drift, dispersal, selection, extinction and speciation erase the traces of microevolutionary events and just leave the final picture of a pronounced interspecific chromosomal difference