Mitochondrial DNA genetic relationships at the ancient Neolithic site of Tell Halula

The extent of racemization of aspartic acid (Asp) -expressed as D/L ratio- has been used as a marker of biomolecular degradation in ancient remains. However, Asp racemization rate is highly variable, and depends on biochemical and geochemical factors. In this paper we aim to determine to which extent the fraction analyzed and the kind of sample used may influence the D/L Asp ratios. Other factors, such as burial site and sample preservation conditions, are also considered. D/L Asp ratios were obtained in 38 ancient human samples from 30 different individuals in which Real Time PCR quantification and amplification of short mtDNA fragments had been previously achieved. Four samples were taken from bones, 16 from whole teeth and 18 from dentine. In 7 cases whole tooth and dentine fractions from the same individual were analyzed. The samples belonged to 8 archaeological sites from Pre-pottery Neolithic B (PPNB), Cardial Neolithic and Chalcolithic time periods. Results show significant differences between the D/L Asp ratios obtained in dentine and whole tooth fractions from the same tooth and individual, as well as among dentine samples from the same archaeological site and among samples of the same age from different, though nearby, archaeological sites. Ancient DNA (aDNA) could be characterized in the majority of the samples, independently from their racemization values, which suggests that other factors, apart from the sample preservation stage, are more significantly affecting the racemization rate. A generalized use of the Asp racemization ratio as a threshold value for ancient DNA preservation needs to be questioned until further methodological standardization is considered

La mejora del rendimiento escolar y el clima social mediante un programa de intervención basado en el aprendizaje-servicio y mentoría entre iguales

ABSTRACT  The current data about academic failure and dropout in education are alarming, with scores above average the European average. In this sense, the universities are to react with proposals, reliable, valid and adapted, such as, the establishment of teaching alternative methodologies, to increase the acquisition of learning and skills, reduces risk behaviors, and it promotes an environment and suitable school climate. Considering that situation, the aim of this study is to determine the efficacy of the Huelva Educa Program, an experience based on service-learning and peer mentoring, in order to increase school performance and improve the social climate in compulsory education students. The sample was composed of 69 students of compulsory education and 14 educational tutors. Likewise, in this investigation a quasi-experimental pretest-posttest design with a single group was used, where the intervention, which consisted of different sessions of mentoring among university students, previously trained, and the pupils in compulsory education, in out of school hours during the scholastic year. The results show improvements in school performance of the pupils in compulsory education, and improvements in the quantity and quality of interactions in the classroom, both from the perspective of students and of the educational-tutors, contributing to the failure and early dropout prevention.RESUMEN Los datos actuales, sobre fracaso escolar en educación son alarmantes, con índices por encima de la media europea Por ello, las universidades han de reaccionar con propuestas de mejora, fiables, válidas y adaptadas, tales como, el establecimiento de metodologías alternativas docentes, que ayudan al incremento de la adquisición de aprendizajes y competencias, las cuales reducen conductas de riesgo, promocionando un entorno y clima escolar adecuado. Atendiendo a esta situación, el objetivo de este estudio fue determinar la eficacia del Programa Huelva Educa, experiencia basada en el aprendizaje-servicio y la mentoría entre iguales, para incrementar el rendimiento escolar y mejorar el clima social de alumnado de educación obligatoria. La muestra estuvo compuesta por 69 alumnos de educación obligatoria y 14 docentes-tutores. En esta investigación, se empleó un diseño cuasiexperimental pretest-postest con un solo grupo, donde la intervención consistió en una serie de sesiones de mentoría entre alumnado universitario, previamente entrenado, y el alumnado de educación obligatoria, en horario extraescolar durante el curso escolar. Los resultados arrojan mejoras en el rendimiento escolar del alumnado de educación obligatoria, y mejoras en la cantidad y calidad de las interacciones en el aula, tanto desde la perspectiva del alumnado como de sus docentes-tutores, contribuyendo a la prevención del fracaso y abandono temprano.ABSTRACT  The current data about academic failure and dropout in education are alarming, with scores above average the European average. In this sense, the universities are to react with proposals, reliable, valid and adapted, such as, the establishment of teaching alternative methodologies, to increase the acquisition of learning and skills, reduces risk behaviors, and it promotes an environment and suitable school climate. Considering that situation, the aim of this study is to determine the efficacy of the Huelva Educa Program, an experience based on service-learning and peer mentoring, in order to increase school performance and improve the social climate in compulsory education students. The sample was composed of 69 students of compulsory education and 14 educational tutors. Likewise, in this investigation a quasi-experimental pretest-posttest design with a single group was used, where the intervention, which consisted of different sessions of mentoring among university students, previously trained, and the pupils in compulsory education, in out of school hours during the scholastic year. The results show improvements in school performance of the pupils in compulsory education, and improvements in the quantity and quality of interactions in the classroom, both from the perspective of students and of the educational-tutors, contributing to the failure and early dropout prevention

The 1989 and 2015 outbursts of V404 Cygni: a global study of wind-related optical features

The black hole transient V404 Cygni exhibited a bright outburst in June 2015 that was intensively followed over a wide range of wavelengths. Our team obtained high time resolution optical spectroscopy (~90 s), which included a detailed coverage of the most active phase of the event. We present a database consisting of 651 optical spectra obtained during this event, that we combine with 58 spectra gathered during the fainter December 2015 sequel outburst, as well as with 57 spectra from the 1989 event. We previously reported the discovery of wind-related features (P-Cygni and broad-wing line profiles) during both 2015 outbursts. Here, we build diagnostic diagrams that enable us to study the evolution of typical emission line parameters, such as line fluxes and equivalent widths, and develop a technique to systematically detect outflow signatures. We find that these are present throughout the outburst, even at very low optical fluxes, and that both types of outflow features are observed simultaneously in some spectra, confirming the idea of a common origin. We also show that the nebular phases depict loop patterns in many diagnostic diagrams, while P-Cygni profiles are highly variable on time-scales of minutes. The comparison between the three outbursts reveals that the spectra obtained during June and December 2015 share many similarities, while those from 1989 exhibit narrower emission lines and lower wind terminal velocities. The diagnostic diagrams presented in this work have been produced using standard measurement techniques and thus may be applied to other active low-mass X-ray binaries.Comment: Accepted for publication in MNRAS. 23 pages paper, plus a 9 pages appendix with extra tables and figures. 18 figures are included in the paper and 8 in the appendi

BlackCAT: A catalogue of stellar-mass black holes in X-ray transients

During the last ~50 years, the population of black hole candidates in X-ray binaries has increased considerably with 59 Galactic objects detected in transient low-mass X-ray binaries, plus a few in persistent systems (including ~5 extragalactic binaries). We collect near-infrared, optical and X-ray information spread over hundreds of references in order to study the population of black holes in X-ray transients as a whole. We present the most updated catalogue of black hole transients, which contains X-ray, optical and near-infrared observations together with their astrometric and dynamical properties. It provides new useful information in both statistical and observational parameters providing a thorough and complete overview of the black hole population in the Milky Way. Analysing the distances and spatial distribution of the observed systems, we estimate a total population of ~1300 Galactic black hole transients. This means that we have already discovered less than ~5% of the total Galactic distribution. The complete version of this catalogue will be continuously updated online and in the Virtual Observatory, including finding charts and data in other wavelengths.Comment: http://www.astro.puc.cl/BlackCAT - Accepted for publication in Astronomy & Astrophysics. 20 pages, 8 figures, 5 Table

Global optical/infrared - X-ray correlations in X-ray binaries: quantifying disc and jet contributions

The optical/near-infrared (OIR) region of the spectra of low-mass X-ray binaries appears to lie at the intersection of a variety of different emission processes. In this paper we present quasi-simultaneous OIR - X-ray observations of 33 XBs in an attempt to estimate the contributions of various emission processes in these sources, as a function of X-ray state and luminosity. A global correlation is found between OIR and X-ray luminosity for low-mass black hole candidate XBs (BHXBs) in the hard X-ray state, of the form L_OIR is proportional to Lx^0.6. This correlation holds over 8 orders of magnitude in Lx and includes data from BHXBs in quiescence and at large distances (LMC and M31). A similar correlation is found in low-mass neutron star XBs (NSXBs) in the hard state. For BHXBs in the soft state, all the near-infrared (NIR) and some of the optical emission is suppressed below the correlation, a behaviour indicative of the jet switching off/on in transition to/from the soft state. We compare these relations to theoretical models of a number of emission processes. We find that X-ray reprocessing in the disc and emission from the jets both predict a slope close to 0.6 for BHXBs, and both contribute to the OIR in BHXBs in the hard state, the jets producing ~90 percent of the NIR emission at high luminosities. X-ray reprocessing dominates the OIR in NSXBs in the hard state, with possible contributions from the jets (only at high luminosity) and the viscously heated disc. We also show that the optically thick jet spectrum of BHXBs extends to near the K-band. (abridged)Comment: Accepted for publication in MNRAS; 19 pages, 7 figure

Accreting Millisecond X-Ray Pulsars

Accreting Millisecond X-Ray Pulsars (AMXPs) are astrophysical laboratories without parallel in the study of extreme physics. In this chapter we review the past fifteen years of discoveries in the field. We summarize the observations of the fifteen known AMXPs, with a particular emphasis on the multi-wavelength observations that have been carried out since the discovery of the first AMXP in 1998. We review accretion torque theory, the pulse formation process, and how AMXP observations have changed our view on the interaction of plasma and magnetic fields in strong gravity. We also explain how the AMXPs have deepened our understanding of the thermonuclear burst process, in particular the phenomenon of burst oscillations. We conclude with a discussion of the open problems that remain to be addressed in the future.Comment: Review to appear in "Timing neutron stars: pulsations, oscillations and explosions", T. Belloni, M. Mendez, C.M. Zhang Eds., ASSL, Springer; [revision with literature updated, several typos removed, 1 new AMXP added

Resistance to autosomal dominant Alzheimer's disease in an APOE3 Christchurch homozygote: a case report.

We identified a PSEN1 (presenilin 1) mutation carrier from the world's largest autosomal dominant Alzheimer's disease kindred, who did not develop mild cognitive impairment until her seventies, three decades after the expected age of clinical onset. The individual had two copies of the APOE3 Christchurch (R136S) mutation, unusually high brain amyloid levels and limited tau and neurodegenerative measurements. Our findings have implications for the role of APOE in the pathogenesis, treatment and prevention of Alzheimer's disease

The 2005 outburst of the halo black hole X-ray transient XTE J1118+480

We present optical and infrared monitoring of the 2005 outburst of the halo black hole X-ray transient XTE J1118+480. We measured a total outburst amplitude of ~5.7 ± 0.1 mag in the R band and ~5 mag in the infrared J, H, and Ks bands. The hardness ratio HR2 (5-12 keV : 3-5 keV) from the RXTE ASM data is 1.53 ± 0.02 at the peak of the outburst, indicating a hard spectrum. Both the shape of the light curve and the ratio LX(1-10 keV)/Lopt resemble the minioutbursts observed in GRO J0422+32 and XTE J1859+226. During early decline, we find a 0.02 mag amplitude variation consistent with a superhump modulation, like the one observed during the 2000 outburst. Similarly, XTE J1118+480 displayed a double-humped ellipsoidal modulation distorted by a superhump wave when settled into a near-quiescence level, suggesting that the disk expanded to the 3 : 1 resonance radius after outburst, where it remained until early quiescence. The system reached quiescence at R = 19.02 ± 0.03, about 3 months after the onset of the outburst. The optical rise preceded the X-ray rise by at most 4 days. The spectral energy distributions (SEDs) at the different epochs during outburst are all quasi-power laws with Fν να increasing toward the blue. At the peak of the outburst, we derived α = 0.49 ± 0.04 for the optical data alone and α = 0.1 ± 0.1 when fitting solely the infrared. This difference between the optical and the infrared SEDs suggests that the infrared is dominated by a different component (a jet?), whereas the optical is presumably showing the disk evolution