3C 286: a bright, compact, stable, and highly polarized calibrator for millimeter-wavelength observations

(Context.) A number of millimeter and submillimeter facilities with linear polarization observing capabilities have started operating during last years. These facilities, as well as other previous millimeter telescopes and interferometers, require bright and stable linear polarization calibrators to calibrate new instruments and to monitor their instrumental polarization. The current limited number of adequate calibrators implies difficulties in the acquisition of these calibration observations. (Aims.) Looking for additional linear polarization calibrators in the millimeter spectral range, in mid-2006 we started monitoring 3C 286, a standard and highly stable polarization calibrator for radio observations. (Methods.) Here we present the 3 and 1 mm monitoring observations obtained between September 2006 and January 2012 with the XPOL polarimeter on the IRAM 30 m Millimeter Telescope. (Results.) Our observations show that 3C 286 is a bright source of constant total flux with 3 mm flux density S_3mm = (0.91 \pm 0.02) Jy. The 3mm linear polarization degree (p_3mm =[13.5\pm0.3]%) and polarization angle (chi_3mm =[37.3\pm0.8]deg.,expressed in the equatorial coordinate system) are also constant during the time span of our observations. Although with poorer time sampling and signal-to-noise ratio, our 1 mm observations of 3C 286 are also reproduced by a constant source of 1 mm flux density (S_1mm = [0.30 \pm 0.03] Jy), polarization fraction (p_1mm = [14.4 \pm 1.8] %), and polarization angle (chi_1mm = [33.1 \pm 5.7]deg.). (Conclusions.) This, together with the previously known compact structure of 3C 286 -extended by ~3.5" in the sky- allow us to propose 3C 286 as a new calibrator for both single dish and interferometric polarization observations at 3 mm, and possibly at shorter wavelengths.Comment: Accepted for publication in A&A. 7 pages, 4 figures, 8 tables. Updated data sets with regard to previous version. New discussion about multi frequency properties of the source. Section 3.3, Figures 3 and 4, and Tables 7 and 8 are ne

An infrared study of galactic OH/IR stars. I. An optical/near-IR atlas of the Arecibo sample

In this paper we present optical and near-infrared finding charts, accurate astrometry (~1") and single-epoch near-infrared photometry for 371 IRAS sources, 96% of those included in the so-called Arecibo sample of OH/IR stars (Eder et al. 1988; Lewis et al. 1990a; Chengalur et al. 1993). The main photometric properties of the stars in the sample are presented and discussed as well as the problems found during the process of identification of the optical/near-infrared counterparts. In addition, we also identify suitable reference stars in each field to be used for differential photometry purposes in the future. We find that 39% of the sources (144 in number) have no optical counterpart, 8 of them being invisible even at near infrared wavelengths. The relative distribution of sources with and without optical counterpart in the IRAS two-colour diagram and their characteristic near infrared colours are interpreted as the consequence of the increasing thickness of their circumstellar shells. Among the objects not detected at near infrared wavelengths four non-variable sources are proposed to be heavily obscured post-AGB stars which have just very recently left the AGB. Eight additional objects with unusually bright and/or blue near-infrared colours are identified as candidate post-AGB stars and/or proto-planetary nebulae.Comment: 28 pages, 9 figures, for associated finding charts see: http://www.edpsciences.org/articles/aa/full/2005/08/aa1709/FINDING_CHARTS/are cibo_index.htm

Interaction effects and transport properties of Pt capped Co nanoparticles

We studied the magnetic and transport properties of Co nanoparticles (NPs) being capped with varying amounts of Pt. Beside field and temperature dependent magnetization measurements we performed delta-M measurements to study the magnetic interactions between the Co NPs. We observe a transition from demagnetizing towards magnetizing interactions between the particles for an increasing amount of Pt capping. Resistivity measurements show a crossover from giant magnetoresistance towards anisotropic magnetoresistance

El efecto del capital cultural sobre el rendimiento educativo diferencial por género

Uno de los aspectos menos tratados respecto a las funciones de producción educativa, en España, es el de la influencia de los estilos de vida, como medio para caracterizar la influencia del contexto familiar en lo que respecta al denominado “capital cultural”. Este capital favorece la adquisición en la familia de valores y normas necesarios para potenciar un alto rendimiento académico. Este trabajo evalúa si las variables de capital cultural afectan de forma diferencial al rendimiento de niñas y niños en educación primaria y secundaria en Andalucía, empleando datos del curso 2009/10. En particular se pretende determinar hasta qué punto se pueden diseñar intervenciones que permitan corregir las diferencias de género tanto en rendimiento como en elección de campo de estudio, por cuanto ambas cuestiones no solo afectan a la desigualdad actual sino a potenciales diferencias en las carreras educativo-formativas futuras de mujeres y hombres, y a sus oportunidades laborales. Cuando se analizan las variables relativas al "capital cultural" los resultados mostrados en la literatura previa se ven matizados de forma significativa y se observan impactos diferenciales por razón de género que merecen ser puestos en valor y que dan robustez complementaria a algunos de los argumentos esgrimidos por la economía feminista.One of the less discussed issues in the literature on educational production functions, in Spain, is the influence of lifestyles as a way of characterizing more precisely the impact of gender and family background on educational outcomes, regarding the so-called "cultural capital." This capital potentially favors the acquisition of family values and norms necessary to boost educational outcomes. We intend to check whether this is supported by empirical evidence based on Spanish microdata (for the academic year 2009/10) and, additionally, whether these measures of cultural capital have any relationship with pupil’s subsequent educational choices at the end of compulsory education (age 16), both in terms of formal education and labor market opportunities. Once we control for "cultural capital" related variables significant nuances arise regarding to previous results dealing with gender differences, giving empirical additional support to many theories coming from the feminist economics

Rapid TeV variability in Blazars as result of Jet-Star Interaction

We propose a new model for the description of ultra-short flares from TeV blazars by compact magnetized condensations (blobs), produced when red giant stars cross the jet close to the central black hole. Our study includes a simple dynamical model for the evolution of the envelope lost by the star in the jet, and its high energy nonthermal emission through different leptonic and hadronic radiation mechanisms. We show that the fragmented envelope of the star can be accelerated to Lorentz factors up to 100 and radiate effectively the available energy in gamma-rays predominantly through proton synchrotron radiation or external inverse Compton scattering of electrons. The model can readily explain the minute-scale TeV flares on top of longer (typical time-scales of days) gamma-ray variability as observed from the blazar PKS 2155-304. In the framework of the proposed scenario, the key parameters of the source are robustly constrained. In the case of proton synchrotron origin of the emission a mass of the central black hole of $M_{\rm BH}\approx 10^8 M_{\odot}$, a total jet power of $L_{\rm j} \approx 2\times 10^{47} \, \rm erg\,s^{-1}$ and a Doppler factor, of the gamma-ray emitting blobs, of $\delta\geq 40$ are required. Whilst for the external inverse Compton model, parameters of $M_{\rm BH}\approx 10^8 M_{\odot}$, $L_{\rm j} \approx 10^{46} \, \rm erg\,s^{-1}$ and the $\delta\geq 150$ are required.Comment: 25 pages, 11 figures, Submitted to Ap

Additional Physical Interventions to Conventional Physical Therapy in Parkinson’s Disease: A Systematic Review and Meta-Analysis of Randomized Clinical Trials

Parkinson's disease (PD) represents the second most common neurodegenerative disease. Currently, conventional physical therapy is complemented by additional physical interventions with recreational components, improving different motor conditions in people with PD. This review aims to evaluate the effectiveness of additional physical interventions to conventional physical therapy in Parkinson's disease. A systematic review and meta-analysis of randomized controlled trials were performed. The literature search was conducted in PubMed, Physiotherapy Evidence Database (PEDro), Scopus, SciELO and Web of Science. The PEDro scale was used to evaluate the methodological quality of the studies. A total of 11 randomized controlled trials were included in this review. Five of them contributed information to the meta-analysis. The statistical analysis showed favorable results for dance-based therapy in motor balance: (Timed Up and Go: standardized mean difference (SMD) = −1.16; 95% Confidence Interval (CI):(−2.30 to −0.03); Berg Balance Scale: SMD = 4.05; 95%CI:(1.34 to 6.75)). Aquatic interventions showed favorable results in balance confidence (Activities-Specific Balance Confidence: SMD=10.10; 95%CI:(2.27 to 17.93)). The results obtained in this review highlight the potential benefit of dance-based therapy in functional balance for people with Parkinson's disease, recommending its incorporation in clinical practice. Nonetheless, many aspects require clarification through further research and high-quality studies on this subject

The milliarcsecond-scale jet of PKS 0735+178 during quiescence

We present polarimetric 5 GHz to 43 GHz VLBI observations of the BL Lacertae object PKS 0735+178, spanning March 1996 to May 2000. Comparison with previous and later observations suggests that the overall kinematic and structural properties of the jet are greatly influenced by its activity. Time intervals of enhanced activity, as reported before 1993 and after 2000 by other studies, are followed by highly superluminal motion along a rectilinear jet. In contrast the less active state in which we performed our observations, shows subluminal or slow superluminal jet features propagating through a twisted jet with two sharp bends of about 90 deg. within the innermost three-milliarcsecond jet structure. Proper motion estimates from the data presented here allow us to constrain the jet viewing angle to values < 9 deg., and the bulk Lorentz factor to be between 2 and 4.Comment: 11 pages, 12 figures. Accepted for publication in A&

The role of catchment areas on school segregation by economic, social and cultural characteristics

This research analyses the socioeconomic and cultural segregation of students across school catchment areas using census data for the students in their second year of secondary education in Andalusia (the most populated region in Spain). The main methodology used is the Mutual Information Index, which satisfies all the desirable properties for measuring segregation. Concretely, we draw upon the additive decomposability property, which decomposes the segregation of students across schools into the different levels in which schools can be grouped, that is, catchment areas and, within catchment areas, by source of funding (public and semiprivate schools). We found that school segregation is greater than catchment areas’ segregation. Additionally, statistically significant correlations are found between the level of segregation within the catchment areas and factors such as size of the catchment area, parental level of education and size of the municipality where the school is located.The authors acknowledge the training received from the University of Malaga PhD Program in Economics and Business [Programa de Doctorado en Economía y Empresa de la Universidad de Malaga]. This work has been partly supported by FEDER funding (under Research Project UMA18FEDERJA024); Fundación Pública Andaluza Centro de Estudios Andaluces (under Research Project PRY085/19); the Andalusian Regional Government (SEJ-645) and Ministerio de Educación, Cultura y Deporte (scholarship FPU17/00432)