Extensive population synthesis of isolated neutron stars with field decay

We perform population synthesis studies of different types of neutron stars taking into account the magnetic field decay. For the first time, we confront our results with observations using {\it simultaneously} the Log N -- Log S distribution for nearby isolated neutron stars, the Log N -- Log L distribution for magnetars, and the distribution of radio pulsars in the $P$ -- $\dot P$ diagram. We find that our theoretical model is consistent with all sets of data if the initial magnetic field distribution function follows a log-normal law with $\sim 13.25$ and $\sigma_{\log B_0}\sim 0.6$. The typical scenario includes about 10% of neutron stars born as magnetars, significant magnetic field decay during the first million years of a NS life. Evolutionary links between different subclasses may exist, although robust conclusions are not yet possible. We apply the obtained field distribution and the model of decay to study long-term evolution of neuton stars till the stage of accretion from the interstellar medium. It is shown that though the subsonic propeller stage can be relatively long, initially highly magnetized neutron stars ($B_0 > \sim 10^{13}$ G) reach the accretion regime within the Galactic lifetime if their kick velocities are not too large. The fact that in previous studies made $>$10 years ago, such objects were not considered results in a slight increase of the Accretor fraction in comparison with earlier conclusions. Most of the neutron stars similar to the Magnificent seven are expected to become accreting from the interstellar medium after few billion years of their evolution. They are the main predecestors of accreting isolated neutron stars.Comment: 4 pages, conference "Astrophysics of Neutron Stars - 2010" in honor of M. Ali Alpar, Izmir, Turke

Energy versus information based estimations of dissipation using a pair of magnetic colloidal particles

Using the framework of stochastic thermodynamics, we present an experimental study of a doublet of magnetic colloidal particles which is manipulated by a time-dependent magnetic field. Due to hydrodynamic interactions, each bead experiences a state-dependent friction, which we characterize using a hydrodynamic model. In this work, we compare two estimates of the dissipation in this system: the first one is energy based since it relies on the measured interaction potential, while the second one is information based since it uses only the information content of the trajectories. While the latter only offers a lower bound of the former, we find it to be simple to implement and of general applicability to more complex systems.Comment: Main text: 5 pages, 4 figures. Supplementary material: 5 pages, 5 figure

Recombination dramatically speeds up evolution of finite populations

We study the role of recombination, as practiced by genetically-competent bacteria, in speeding up Darwinian evolution. This is done by adding a new process to a previously-studied Markov model of evolution on a smooth fitness landscape; this new process allows alleles to be exchanged with those in the surrounding medium. Our results, both numerical and analytic, indicate that for a wide range of intermediate population sizes, recombination dramatically speeds up the evolutionary advance

Fijación interna versus percutánea en fracturas diafisarias de metacarpianos: estudio de casos-controles

Objetivos: comparación de resultados clínicos de fijación interna versus fijación percutánea. Material y Métodos: estudio retrospectivo de casos y controles de 58 fracturas de metacarpianos (43 pacientes). Se incluyeron las fracturas diafisarias, sin afectación articular. Se excluyeron si había afectación del pulgar o de falanges, fracturas abiertas o más de 3 fracturas en la misma mano. Un total de 26 fracturas fueron tratadas con fijación interna y 32 con percutánea. Con un seguimiento medio de 2,5 años (rango, 1-4), se valoró la función mediante movilidad activa total (MAT), fuerza, DASH, EAV de dolor y resultado radiográfico. Resultados: con ambos tratamientos los resultados fueron satisfactorios. El tiempo de consolidación y alineación radiográfica fueron similares. Todas las valoraciones clínicas, objetivas y subjetivas, fueron mejores en el grupo de fijación interna, así como la tasa de retorno a las actividades previas. En el grupo de fijación interna hubo un caso de pseudoartrosis que fue reoperado y otro de déficit de movilidad. En el grupo percutáneo hubo 4 casos con déficit de movilidad. Discusión y conclusiones: ambas técnicas ofrecen resultados adecuados, pero con la fijación interna se obtuvieron mejores resultados respecto a movilidad, fuerza, mayor facilidad para realización de las actividades previas y retorno a las laborales y deportivas, a pesar de las complicaciones inherentes a la cirugía abiertaObjectives: comparison of outcomes with internal fixation versus percutaneous fixation. Material and Methods: retrospective case-control study of 58 metacarpal fractures (43 patients). Shaft fractures without joint involvement were included. Exclusion criteria were involvement of the thumb or phalange, open fracture, or more than 3 fractures in the same hand. There were 26 fractures treated with internal fixation and 32 with percutaneous fixation. With a mean follow-up of 2,5 years (range, 1-4), functional evaluation was performed by total active motion (TAM), strength grip, DASH, pain VAS, and radiographic results. Results: satisfactory outcomes were obtained with both treatments. Consolidation time and radiographic alignment were similar. All clinical objective and subjective assessments were better in the internal fixation group, as well as the rate of return to previous activities. In the internal fixation group, there was one case with nonunion, which was reoperated, and other with lack of motion. In the percutaneous group, there were 4 cases with mobility deficits. Discussion and conclusions: satisfactory results were offered by both methods, but better outcomes were obtained by internal fixation with regard to motion, strength, best facility for previous activities, and return to work and sport activities. All this was spite of the inherent complications of open surger

The influence of magnetic field geometry on magnetars X-ray spectra

Nowadays, the analysis of the X-ray spectra of magnetically powered neutron stars or magnetars is one of the most valuable tools to gain insight into the physical processes occurring in their interiors and magnetospheres. In particular, the magnetospheric plasma leaves a strong imprint on the observed X-ray spectrum by means of Compton up-scattering of the thermal radiation coming from the star surface. Motivated by the increased quality of the observational data, much theoretical work has been devoted to develop Monte Carlo (MC) codes that incorporate the effects of resonant Compton scattering in the modeling of radiative transfer of photons through the magnetosphere. The two key ingredients in this simulations are the kinetic plasma properties and the magnetic field (MF) configuration. The MF geometry is expected to be complex, but up to now only mathematically simple solutions (self-similar solutions) have been employed. In this work, we discuss the effects of new, more realistic, MF geometries on synthetic spectra. We use new force-free solutions in a previously developed MC code to assess the influence of MF geometry on the emerging spectra. Our main result is that the shape of the final spectrum is mostly sensitive to uncertain parameters of the magnetospheric plasma, but the MF geometry plays an important role on the angle-dependence of the spectra.Comment: 6 pages, 4 figures To appear in Proceedings of II Iberian Nuclear Astrophysics Meeting held in Salamanca, September 22-23, 201