Three-body structure of low-lying 12Be states

We investigate to what extent a description of 12Be as a three-body system made of an inert 10Be-core and two neutrons is able to reproduce the experimental 12Be data. Three-body wave functions are obtained with the hyperspherical adiabatic expansion method. We study the discrete spectrum of 12Be, the structure of the different states, the predominant transition strengths, and the continuum energy spectrum after high energy fragmentation on a light target. Two 0+, one 2+, one 1- and one 0- bound states are found where the first four are known experimentally whereas the 0- is predicted as an isomeric state. An effective neutron charge, reproducing the measured B(E1) transition and the charge rms radius in 11Be, leads to a computed B(E1) transition strength for 12Be in agreement with the experimental value. For the E0 and E2 transitions the contributions from core excitations could be more significant. The experimental 10Be-neutron continuum energy spectrum is also well reproduced except in the energy region corresponding to the 3/2- resonance in 11Be where core excitations contribute.Comment: 16 pages, 9 figures. Accepted for publication in Physical Review

Cosmological constraints on thermal relic axions and axion-like particles

Cosmological precision data can be used to set very strict constraints on Axions and Axion-like particles (ALPs) produced thermally in the big bang. We briefly review the known bounds and propose two new constraints for Axions and ALPs decaying in the early universe, based upon the concomitant dilution of baryon and neutrino densities, using WMAP7 and other cosmological data.Comment: 4 pages, 4 figures. To appear in the proceedings of 7th Patras Workshop on Axions, WIMPs and WISPs, Mykonos, Greece, 26 June - 1 July 2011 and of TAUP 2011, Munich, Germany, 5 - 9 September 201

Large eddy simulation and laboratory experiments on the decay of grid wakes in strongly stratified flows

A detailed analysis of the flow structure resulting from the combination of turbulence and internal waves is carried out and visualized by means of the Schlieren method on waves in a strongly stratified fluid at the Laboratory of the IPM in Moscow. The joint appearance of the more regular internal wave oscillations and the small-scale turbulence that is confined vertically to the Ozmidov length scale favours the use of a simple geometrical analysis to investigate their time-space span and evolution. This provides useful information on the collapse of internal wave breaking processes in the ocean and the atmosphere. The measurements were performed under a variety of linear stratifications and different grid forcing scales, combining the grid wake and velocity shear. A numerical simulation using LES on the passage of a single bar in a linearly stratified fluid medium has been compared with the experiments identifying the different influences of the environmental agents on the actual effective vertical diffusion of the wakes. The equation of state, which connects the density and salinity, is assumed to be linear, with the coefficient of the salt contraction being included into the definition of salinity or heat. The characteristic internal waves as well as the entire beam width are related to the diameter of the bar, the Richardson number and the peak-to-peak value of oscillations. The ultimate frequency of the infinitesimal periodic internal waves is limited by the maximum buoyancy frequency relating the decrease in the vertical scale with the anisotropy of the velocity turbulent r.m.s. velocity.Peer ReviewedPreprin

Axion cosmology, lattice QCD and the dilute instanton gas

Axions are one of the most attractive dark matter candidates. The evolution of their number density in the early universe can be determined by calculating the topological susceptibility $\chi(T)$ of QCD as a function of the temperature. Lattice QCD provides an ab initio technique to carry out such a calculation. A full result needs two ingredients: physical quark masses and a controlled continuum extrapolation from non-vanishing to zero lattice spacings. We determine $\chi(T)$ in the quenched framework (infinitely large quark masses) and extrapolate its values to the continuum limit. The results are compared with the prediction of the dilute instanton gas approximation (DIGA). A nice agreement is found for the temperature dependence, whereas the overall normalization of the DIGA result still differs from the non-perturbative continuum extrapolated lattice results by a factor of order ten. We discuss the consequences of our findings for the prediction of the amount of axion dark matter.Comment: 9 pages, 7 figure

Inequality and academic achievement in Chile

Includes bibliographyThis work uses a set of panel data to contribute new evidence on the impacts of socioeconomic determinants on academic achievement in Chile. Socioeconomic determinants are found to have a statistically significant effect, which rises over time, on academic achievement. The evidence shows that two individuals of different socioeconomic levels (SEL) who achieve the same score in Chile's Educational Quality Measurement System (simce) in eighth grade, are separated by a gap of over 70 points on average four years later, when they sit the University Selection Test (PSU). It is concluded that in a context of great income inequality and high returns on tertiary education, academic achievement indexes throw up barriers to access to tertiary education, principally for the population of low socioeconomic level, thereby perpetuating poor income distribution

First evidence of early socialization in the Great Spotted Cuckoo (Clamator glandarius)

Peer reviewe

Effect on hatchability of length of time for turning eggs during the incubation in Red-legged partridge (Alectoris rufa)

El volteo de los huevos en la incubación artificial es clave para lograr buenas tasas de eclosión y pollos viables. En la producción de perdiz roja (Alectoris rufa) la duración recomendada para el periodo durante el que los huevos deben ser volteados en la incubación no se ha comprobado experimentalmente. Para contribuir al conocimiento de la duración óptima del periodo de volteo, se incubaron 74 huevos divididos en tres grupos: huevos volteados hasta el día 18 ó 19, volteados hasta el día 20 ó 21 y volteados hasta el día 22 de incubación. La tasa de eclosión fue mayor en los huevos volteados durante 20 días o másTurning of the eggs during the artificial incubation is critical in order to obtain a good hatchability and viable one-day-old chicks. In Red-legged partridge (Alectoris rufa) farming, the recommended length of time during which the eggs should be turned along the incubation process has not been experimentally tested. With the aim of improving knowledge on the optimum length of time for the eggs to be turned during the incubation, seventy four eggs were incubated, divided into three groups: eggs that were turned until day 18 or 19, eggs that were turned until day 20 or 21, and eggs that were turned until day 22 of incubation. The hatchability of the eggs was higher for the eggs that were turned during the incubation over at least 20 days

Probing the mechanical unzipping of DNA

A study of the micromechanical unzipping of DNA in the framework of the Peyrard-Bishop-Dauxois model is presented. We introduce a Monte Carlo technique that allows accurate determination of the dependence of the unzipping forces on unzipping speed and temperature. Our findings agree quantitatively with experimental results for homogeneous DNA, and for $\lambda$-phage DNA we reproduce the recently obtained experimental force-temperature phase diagram. Finally, we argue that there may be fundamental differences between {\em in vivo} and {\em in vitro} DNA unzipping

Mioma Parasita: Forma Rara de Apresentação de uma Entidade Comum

Parasitic myomas are a rare form of uterine leiomyomas. Distinction from other abdominal masses may be difficult, due to parasitic leiomyomas' variable anatomic locations and clinical manifestations. We describe the case of a 45 years-old woman, presenting with abdominal pain and a large pelvic mass that turned out to be a parasitic myoma at surgical assessment. Histological analysis confirmed the intraoperative suspicion. We intend to bring awareness to the inclusion of this condition in the differential diagnosis of pelvic masses, especially in women with risk factors for parasitic myomas, such as previous surgery for uterine fibromyomatosis or concomitant uterine myomas.info:eu-repo/semantics/publishedVersio

Self Interacting Dark Matter in the Solar System

Weakly coupled, almost massless, spin 0 particles have been predicted by many extensions of the standard model of particle physics. Recently, the PVLAS group observed a rotation of polarization of electromagnetic waves in vacuum in the presence of transverse magnetic field. This phenomenon is best explained by the existence of a weakly coupled light pseudoscalar particle. However, the coupling required by this experiment is much larger than the conventional astrophysical limits. Here we consider a hypothetical self-interacting pseudoscalar particle which couples weakly with visible matter. Assuming that these pseudoscalars pervade the galaxy, we show that the solar limits on the pseudoscalar-photon coupling can be evaded.Comment: 17 pages, 2 figure