Observational constraints on interacting quintessence models

We determine the range of parameter space of Interacting Quintessence Models that best fits the recent WMAP measurements of Cosmic Microwave Background temperature anisotropies. We only consider cosmological models with zero spatial curvature. We show that if the quintessence scalar field decays into cold dark matter at a rate that brings the ratio of matter to dark energy constant at late times,the cosmological parameters required to fit the CMB data are: \Omega_x = 0.43 \pm 0.12, baryon fraction \Omega_b = 0.08 \pm 0.01, slope of the matter power spectrum at large scals n_s = 0.98 \pm 0.02 and Hubble constant H_0 = 56 \pm 4 km/s/Mpc. The data prefers a dark energy component with a dimensionless decay parameter c^2 =0.005 and non-interacting models are consistent with the data only at the 99% confidence level. Using the Bayesian Information Criteria we show that this exra parameter fits the data better than models with no interaction. The quintessence equation of state parameter is less constrained; i.e., the data set an upper limit w_x \leq -0.86 at the same level of significance. When the WMAP anisotropy data are combined with supernovae data, the density parameter of dark energy increases to \Omega_x \simeq 0.68 while c^2 augments to 6.3 \times 10^{-3}. Models with quintessence decaying into dark matter provide a clean explanation for the coincidence problem and are a viable cosmological model, compatible with observations of the CMB, with testable predictions. Accurate measurements of baryon fraction and/or of matter density independent of the CMB data, would support/disprove these models.Comment: 16 pages, Revtex4, 5 eps figures, to appear in Physical Review

Matter density perturbations in interacting quintessence models

Models with dark energy decaying into dark matter have been proposed to solve the coincidence problem in cosmology. We study the effect of such coupling in the matter power spectrum. Due to the interaction, the growth of matter density perturbations during the radiation dominated regime is slower compared to non-interacting models with the same ratio of dark matter to dark energy today. This effect introduces a damping on the power spectrum at small scales proportional to the strength of the interaction and similar to the effect generated by ultrarelativistic neutrinos. The interaction also shifts matter--radiation equality to larger scales. We compare the matter power spectrum of interacting quintessence models with the measurments of 2dFGRS. We particularize our study to models that during radiation domination have a constant dark matter to dark energy ratio.Comment: 11 pages, 4 figures, accepted for publication in Phys. Rev.

Analysis of educational leadership at rural early-childhood and primary schools: a case study in Teruel (Aragon, Spain)

Rural schools are a distinctive feature in the autonomous community of Aragon, as state-run rural schools are the main cultural institution in small towns. This research was conducted in four grouped rural schools (hereafter referred to by their Spanish acronym, CRAs) in the province of Teruel in 2017. Our objectives included analising the views of management team members and teachers on educational leadership with a special emphasis on the rural school’s differentiating elements. Four CRAs were chosen in the province of Teruel. Three teachers and six members of management teams participated and the study data were collected using a qualitative interview. The content analysis of the interview was conducted using the NVivo program and was organised into two fundamental areas: views of educational leadership and the skills this leadership includes. The general perception of management teams and teachers is positive; they value the effort put into performing the work and understand that both management and CRAs are complex. They also appreciate the management teams’ organisation of training and its contents. This analysis suggests a set of conditions that provides a qualitative insight into management possibilities and limitations in the CRA model

Full characterization of Gaussian bipartite entangled states by a single homodyne detector

We present the full experimental reconstruction of Gaussian entangled states generated by a type--II optical parametric oscillator (OPO) below threshold. Our scheme provides the entire covariance matrix using a single homodyne detector and allows for the complete characterization of bipartite Gaussian states, including the evaluation of purity, entanglement and nonclassical photon correlations, without a priori assumptions on the state under investigation. Our results show that single homodyne schemes are convenient and robust setups for the full characterization of OPO signals and represent a tool for quantum technology based on continuous variable entanglement.Comment: 4 pages, 3 figures, slightly longer version of published PR

Afterglow rebrightenings as a signature of a long-lasting central engine activity? The emblematic case of GRB 100814A

In the past few years the number of well-sampled optical to NIR light curves of long Gamma-Ray Bursts (GRBs) has greatly increased particularly due to simultaneous multi-band imagers such as GROND. Combining these densely sampled ground-based data sets with the Swift UVOT and XRT space observations unveils a much more complex afterglow evolution than what was predicted by the most commonly invoked theoretical models. GRB 100814A represents a remarkable example of these interesting well-sampled events, showing a prominent late-time rebrightening in the optical to NIR bands and a complex spectral evolution. This represents a unique laboratory to test the different afterglow emission models. Here we study the nature of the complex afterglow emission of GRB 100814A in the framework of different theoretical models. Moreover, we compare the late-time chromatic rebrightening with those observed in other well-sampled long GRBs. We analysed the optical and NIR observations obtained with the seven-channel Gamma-Ray burst Optical and Near-infrared Detector at the 2.2 m MPG/ESO telescope together with the X-ray and UV data detected by the instruments onboard the Swift observatory. The broad-band afterglow evolution, achieved by constructing multi-instrument light curves and spectral energy distributions, will be discussed in the framework of different theoretical models. We find that the standard models that describe the broad-band afterglow emission within the external shock scenario fail to describe the complex evolution of GRB 100814A, and therefore more complex scenarios must be invoked. [abridged]Comment: 11 pages, 7 figures, 2 tables; Astronomy & Astrophysics, in pres

Asthma diagnosis is not associated with obesity in a population of adults from Madrid

Background: Several studies have suggested a relationship between asthma and obesity; however, this relationship is unclear when obesity is compared with bronchial hyperresponsiveness to methacholine. Aim: To determine whether obesity is associated with a diagnosis of asthma. Methods: We conducted a cross-sectional study in a population of Spanish adults in the north of Madrid, Spain between 2003 and 2007. The patients included had experienced asthma symptoms during the previous year, but had a ratio of forced expiratory volume in the fi rst second of expiration (FEV1) to forced vital capacity (FVC) of >70%. Diagnosis was confi rmed by the presence of symptoms and demonstration of bronchial hyperresponsiveness to methacholine. Obesity was measured by body mass index (BMI). Adjusted odd ratios (OR) were obtained by logistic regression. Results: Of a total of 1424 patients included, 251 (17.6%) were diagnosed with asthma. These patients were younger (P<.001) and had lower BMI (P<.001) and lung function parameters (FEV1 and FEV1/FVC ratio) than individuals without asthma (P<.001). After adjusting the model for age, gender, baseline FEV1, and FEV1/FVC ratio, patients with overweight or obesity were not more frequently diagnosed with asthma than those with normal weight (OR, 0.848 [95% confi dence interval (CI), 0.59-1.20]; and OR, 0.616 [95% CI, 0.38-0.99], respectively). In addition, obese males were more frequently diagnosed with asthma than obese females (P<.041). Conclusions: In this study, obesity and overweight were not associated with a diagnosis of asthma based on the presence of consistent symptoms and demonstration of airway responsiveness to methacholineFundamento: Varios estudios sugieren que la obesidad es un factor de riesgo para padecer asma, lo que no siempre se confi rma cuando se compara la obesidad con la hiperreactividad bronquial (HRB) en pacientes con síntomas de asma. Objetivo: Determinar si la obesidad se asocia con el diagnóstico de asma, confi rmado por presencia de síntomas e HRB a metacolina. Pacientes y Métodos: Se realizó un estudio transversal en población adulta del Área Norte de Madrid entre 2003 y 2007. Se incluyeron sujetos que habían padecido síntomas de asma en el último año, con un FEV1/FVC>70% y que precisaban una prueba de metacolina para confi rmar el diagnóstico. La obesidad se defi nió según el índice de masa corporal (IMC). Se aplicó un modelo de regresión logística para calcular odd ratios (OR) ajustadas. Resultados: Se estudiaron 1.424 sujetos y se diagnosticaron de asma 251 sujetos (17,6%) que, comparados con los 1.173 no diagnosticados de asma, eran más jóvenes y presentaban un IMC y parámetros de función pulmonar (FEV1, FEV1/FVC) más bajos (p<0,001). Tras ajustar el modelo por edad, sexo, FEV1 basal y FEV1/FVC el diagnóstico de asma no fue más prevalente en los sujetos obesos o con sobrepeso que en los sujetos con peso normal (OR 0,848, IC95% 0,59-1,20 y OR 0,616, IC95% 0,38-0,99, respectivamente). El diagnóstico de asma fue más frecuente en hombres obesos que en mujeres obesas (p=0,041). Conclusiones: La obesidad y el sobrepeso no se asociaron con el diagnóstico de asma establecido por la presencia de síntomas e HRB a metacolinaThis research project was carried out with a grant from Fundación para la Investigación Biomédica del Hospital Universitario La Paz (FIBHULP

Multiwavelength analysis of three SNe associated with GRBs observed by GROND

After the discovery of the first connection between GRBs and SNe almost two decades ago, tens of SN-like rebrightenings have been discovered and about seven solid associations have been spectroscopically confirmed to date. Using GROND optical/NIR data and Swift X-ray/UV data, we estimate the intrinsic extinction, luminosity, and evolution of three SN rebrightenings in GRB afterglow light curves at z~0.5. The SNe 2008hw, 2009nz, and 2010ma exhibit 0.80, 1.15, and 1.78 times the optical (r band) luminosity of SN 1998bw, respectively. While SN 2009nz evolves similarly to SN 1998bw, SNe 2008hw and 2010ma show earlier peak times. The quasi-bolometric light curves were corrected for the contribution of the NIR bands using data available in the literature and blackbody fits. The large luminosity of SN 2010ma (1.4x10^43 erg/s) is confirmed, while SNe 2008hw and 2009nz reached a peak luminosity closer to SN 1998bw. Physical parameters of the SN explosions, such as synthesised nickel mass, ejecta mass, and kinetic energy, are estimated using Arnett's analytic approach, which resulted in nickel masses of around 0.4-0.5 Msun. By means of the a very comprehensive data set, we found that the luminosity and the nickel mass of SNe 2008hw, 2009nz, and 2010ma resembles those of other known GRB-associated SNe. This findings strengthens previous claims of GRB-SNe being brighter than type-Ic SNe unaccompanied by GRBs.Comment: 11 pages, 9 figures, accepted for publication in Astronomy & Astrophysics, abstract abridge

Errores de estudiantes de primer año medio en la resolución de problemas que involucran ecuaciones de primer grado

Este documento abordalas principales dificultades de los alumnos de Primer Año de Enseñanza Media cuando se ven enfrentados a la necesidad de resolver ecuaciones de primer grado. Para este propósito se aplicó un cuestionario que requería una definición del concepto de ecuación, y que pretendía que los alumnos descubrieran errores simples o encontraran un dato faltante, el que debía ser incluido y modelado mediante una ecuación. Las respuestas obtenidas en dicho cuestionario fueron analizadas detenidamente y se pudo observar algunos errores relacionados con la rigurosidad de la argumentación y la base matemática de las respuestas