Astrometric and photometric monitoring of GQ Lup and its sub-stellar companion

Neuhaeuser et al. (2005) presented direct imaging evidence for a sub-stellar companion to the young T Tauri star GQ Lup. Common proper motion was highly significant, but no orbital motion was detected. Faint luminosity, low gravity, and a late-M/early-L spectral type indicated that the companion is either a planet or a brown dwarf. We have monitored GQ Lup and its companion in order to detect orbital and parallactic motion and variability in its brightness. We also search for closer and fainter companions. We have taken six more images with the VLT Adaptive Optics instrument NACO from May 2005 to Feb 2007, always with the same calibration binary from Hipparcos for both astrometric and photometric calibration. By adding up all the images taken so far, we search for additional companions. The position of GQ Lup A and its companion compared to a nearby non-moving background object varies as expected for parallactic motion by about one pixel (2 \pi with parallax \pi). We could not find evidence for variability of the GQ Lup companion in the K-band (standard deviation being \pm 0.08 mag), which may be due to large error bars. No additional companions are found with deep imaging. There is now exceedingly high significance for common proper motion of GQ Lup A and its companion. In addition, we see for the first time an indication for orbital motion (about 2 to 3 mas/yr decrease in separation, but no significant change in the position angle), consistent with a near edge-on or highly eccentric orbit. We measured the parallax for GQ Lup A to be \pi = 6.4 \pm 1.9 mas (i.e. 156 \pm 50 pc) and for the GQ Lup companion to be 7.2 \pm 2.1 mas (i.e. 139 \pm 45 pc), both consistent with being in the Lupus I cloud and bound to each other.Comment: A&A in pres

Evaluación sistématica de la degradación de materiales sometidos al intemperismo

La necesidad de actividades de restauración y conservación del patrimonio deriva de la acción agresiva que ejercen los agentes ambientales sobre los materiales de construcción. En la actualidad, existen numerosos proyectos destinados a evaluar el comportamiento de estos materiales en ambientes de elevada agresividad, tales como las atmósferas marinas e industriales. Sin embargo, no se conocen iniciativas similares que estén orientadas al estudio de los deterioros que se producen en climas menos severos, y que en nuestro país representan las condiciones de una extensa región. Por otra parte, para diseñar las medidas de reparación y conservación de las construcciones resulta indispensable contar con herramientas que permitan evaluar en forma sistemática el comportamiento de los materiales y la evolución de los deterioros que ellos sufren, a fin de determinar las causas de degradación. Posteriormente, estas mismas herramientas deben permitir monitorear la efectividad de los métodos de reparación aplicados. Los profesionales que desean conocer con certeza el comportamiento de los materiales ante el paso del tiempo y su respuesta ante las distintas condiciones de exposición deben recurrir a datos suministrados por el fabricante o antecedentes existentes en la bibliografía específica y provenientes de investigaciones realizadas al respecto. Muchas de estas fuentes se encuentran desactualizadas, no corresponden a las condiciones de exposición específicas o bien carecen de valor técnico. El CECOVI, dentro de las actividades de investigación y desarrollo de materiales de construcción y sistemas constructivos que lleva adelante, está desarrollando un proyecto que tiene por objetivo principal el abordaje sistemático de la problemática de la durabilidad de los materiales de construcción sometidos a la acción de la intemperie y su aptitud en servicio. Este proyecto se circunscribe, actualmente, al estudio de la durabilidad de hormigones convencionales y elaborados con agregados livianos, hormigones celulares, madera, suelocemento y materiales plásticos, mientras que el tipo de exposición se limita a las condiciones de intemperismo habituales en un clima templado húmedo, de acuerdo a la clasificación establecida por el Sistema Internacional de Koeppen. Paralelamente, se realizan contrastes con materiales mantenidos en condiciones de laboratorio que actúan como patrones de comparación. Los ejes fundamentales planteados están constituidos por el análisis teórico, el seguimiento sistemático del comportamiento de materiales ante condiciones reales de exposición y en condiciones de envejecimiento acelerado, tendientes al establecimiento de una metodología de evaluación de aplicabilidad general, correlaciones entre el deterioro de los materiales y variables ambientales típicas de la región y el desarrollo de técnicas que permitan predecir su vida útil

Modeling the variability of shapes of a human placenta

While it is well-understood what a normal human placenta should look like, a deviation from the norm can take many possible shapes. In this paper we propose a mechanism for this variability based on the change in the structure of the vascular tree

The field high-amplitude SX Phe variable BL Cam: results from a multisite photometric campaign. II. Evidence of a binary - possibly triple - system

Short-period high-amplitude pulsating stars of Population I ($\delta$ Sct stars) and II (SX Phe variables) exist in the lower part of the classical (Cepheid) instability strip. Most of them have very simple pulsational behaviours, only one or two radial modes being excited. Nevertheless, BL Cam is a unique object among them, being an extreme metal-deficient field high-amplitude SX Phe variable with a large number of frequencies. Based on a frequency analysis, a pulsational interpretation was previously given. aims heading (mandatory) We attempt to interpret the long-term behaviour of the residuals that were not taken into account in the previous Observed-Calculated (O-C) short-term analyses. methods heading (mandatory) An investigation of the O-C times has been carried out, using a data set based on the previous published times of light maxima, largely enriched by those obtained during an intensive multisite photometric campaign of BL Cam lasting several months. results heading (mandatory) In addition to a positive (161 $\pm$ 3) x 10$^{-9}$ yr$^{-1}$ secular relative increase in the main pulsation period of BL Cam, we detected in the O-C data short- (144.2 d) and long-term ($\sim$ 3400 d) variations, both incompatible with a scenario of stellar evolution. conclusions heading (mandatory) Interpreted as a light travel-time effect, the short-term O-C variation is indicative of a massive stellar component (0.46 to 1 M_{\sun}) with a short period orbit (144.2 d), within a distance of 0.7 AU from the primary. More observations are needed to confirm the long-term O-C variations: if they were also to be caused by a light travel-time effect, they could be interpreted in terms of a third component, in this case probably a brown dwarf star ($\geq$ 0.03 \ M_{\sun}), orbiting in $\sim$ 3400 d at a distance of 4.5 AU from the primary.Comment: 7 pages, 5 figures, accepted for publication in A&

Spin Hamiltonian with large fourth order terms: Triple well potentials and Bloch sphere visualization

We present a study of a general spin Hamiltonian with terms up to fourth order. With the coherent states the semiclassical potential is obtained and with catastrophe theory its parameter space is constructed. When the fourth order parameters are large enough the parameter space has regions where the semiclassical potential has three wells. By applying an oscillating magnetic field a trajectory in parameter space crosses the Maxwell set multiple times resulting in many ground state quantum phase transitions. Using the coherent states we are able to visualize the localization of the ground state on the Bloch sphere as the magnetic field is varied.Comment: 18 pages, 6 figure

Overconfidence, incentives and digit ratio

This paper contributes to a better understanding of the biological underpinnings of overconfidence by analyzing performance predictions in the Cognitive Reflection Test with and without monetary incentives. In line with the existing literature we find that the participants are too optimistic about their performance on average; incentives lead to higher performance; and males score higher than females on this particular task. The novelty of this paper is an analysis of the relation between participants’ performance prediction accuracy and their second to fourth digit ratio. It has been reported that the digit ratio is a negatively correlated bio-marker of prenatal testosterone exposure. In the un-incentivized treatment, we find that males with low digit ratios, on average, are significantly more overconfident about their performance. In the incentivized treatment, however, we observe that males with low digit ratios, on average, are less overconfident about their performance. These effects are not observed in females. We discuss how these findings fit into the literature on testosterone and decision making and how they might help to explain seemingly opposing evidence

Full Scale Dynamic Response of a RC Building under Weak Seismic Motions Using Earthquake Recordings, Ambient Vibrations and Modelling

In countries with a moderate seismic hazard, the classical methods developed for strong motion prone countries to estimate the seismic behaviour and subsequent vulnerability of existing buildings are often inadequate and not financially realistic. The main goals of this paper are to show how the modal analysis can contribute to the understanding of the seismic building response and the good relevancy of a modal model based on ambient vibrations for estimating the structural deformation under moderate earthquakes. We describe the application of an enhanced modal analysis technique (Frequency Domain Decomposition) to process ambient vibration recordings taken at the Grenoble City Hall building (France). The frequencies of ambient vibrations are compared with those of weak earthquakes recorded by the French permanent accelerometric network (RAP) that was installed to monitor the building. The frequency variations of the building under moderate earthquakes are shown to be slight (~2%) and therefore ambient vibration frequencies are relevant over the elastic domain of the building. The modal parameters extracted from ambient vibrations are then used to determine the 1D lumped-mass model in order to reproduce the inter-storey drift under weak earthquakes and to fix a 3D numerical model that could be used for strong earthquakes. The correlation coefficients between data and synthetic motion are close to 80% and 90% in horizontal directions, for the 1D and 3D modelling, respectively

Extensive population genetic structure in the giraffe

<p>Abstract</p> <p>Background</p> <p>A central question in the evolutionary diversification of large, widespread, mobile mammals is how substantial differentiation can arise, particularly in the absence of topographic or habitat barriers to dispersal. All extant giraffes (<it>Giraffa camelopardalis</it>) are currently considered to represent a single species classified into multiple subspecies. However, geographic variation in traits such as pelage pattern is clearly evident across the range in sub-Saharan Africa and abrupt transition zones between different pelage types are typically not associated with extrinsic barriers to gene flow, suggesting reproductive isolation.</p> <p>Results</p> <p>By analyzing mitochondrial DNA sequences and nuclear microsatellite loci, we show that there are at least six genealogically distinct lineages of giraffe in Africa, with little evidence of interbreeding between them. Some of these lineages appear to be maintained in the absence of contemporary barriers to gene flow, possibly by differences in reproductive timing or pelage-based assortative mating, suggesting that populations usually recognized as subspecies have a long history of reproductive isolation. Further, five of the six putative lineages also contain genetically discrete populations, yielding at least 11 genetically distinct populations.</p> <p>Conclusion</p> <p>Such extreme genetic subdivision within a large vertebrate with high dispersal capabilities is unprecedented and exceeds that of any other large African mammal. Our results have significant implications for giraffe conservation, and imply separate <it>in situ </it>and <it>ex situ </it>management, not only of pelage morphs, but also of local populations.</p

Geographic variation in breeding system and environment predicts melanin-based plumage ornamentation of male and female Kentish plovers

Sexual selection determines the elaboration of morphological and behavioural traits and thus drives the evolution of phenotypes. Sexual selection on males and females can differ between populations, especially when populations exhibit different breeding systems. A substantial body of literature describes how breeding systems shape ornamentation across species, with a strong emphasis on male ornamentation and female preference. However, whether breeding system predicts ornamentation within species and whether similar mechanisms as in males also shape the phenotype of females remains unclear. Here, we investigate how different breeding systems are associated with male and female ornamentation in five geographically distinct populations of Kentish plovers Charadrius alexandrinus. We predicted that polygamous populations would exhibit more elaborate ornaments and stronger sexual dimorphism than monogamous populations. By estimating the size and intensity of male (n = 162) and female (n = 174) melanin-based plumage ornaments, i.e. breast bands and ear coverts, we show that plumage ornamentation is predicted by breeding system in both sexes. A difference in especially male ornamentation between polygamous (darker and smaller ornaments) and monogamous (lighter and larger) populations causes the greatest sexual dimorphism to be associated with polygamy. The non-social environment, however, may also influence the degree of ornamentation, for instance through availability of food. We found that, in addition to breeding system, a key environmental parameter, rainfall, predicted a seasonal change of ornamentation in a sex-specific manner. Our results emphasise that to understand the phenotype of animals, it is important to consider both natural and sexual selection acting on both males and females

Virtualización de la formación en la Universidad de Ciencias de la Cultura Física y el Deporte

The virtualization of the educational process in institutions is today a technological trend due to the boom of online courses, which are gaining space, time and dedication due to the diversity of learning possibilities they offer to students. In this sense, the objective of the research presented in the article is to socialize the strategy conceived for the implementation of the virtualization model of the training process of the Manuel Fajardo University of Physical Culture and Sports Sciences in its technological, organizational and pedagogical dimensions. Structured in five stages, and these in phases related to the roles and functions of the actors in the process under study, it reveals coherence with the identified shortcomings and potentialities. The study used a predominantly descriptive and qualitative approach, based on the dialectical method. As a result, the system of actions oriented to educational virtualization is presented, approved on the basis of the experts' criteria, and a subsequent evaluation stage of its applicability is projected.La virtualización del proceso educativo en las instituciones es hoy una tendencia tecnológica por el auge que han tenido los cursos en línea, los cuales van ganando espacio, tiempo y dedicación por la diversidad de posibilidades de aprendizaje que ofrecen a los estudiantes. En ese sentido, el objetivo de la investigación que se presenta en el artículo es socializar la estrategia concebida para la implementación del modelo de virtualización del proceso de formación de la Universidad de Ciencias de la Cultura Física y el Deporte Manuel Fajardo en sus dimensiones tecnológica, organizativa y pedagógica. Estructurada en cinco etapas, y estas en fases relacionadas con los roles y las funciones de los actores en el proceso objeto de estudio, revela coherencia con las carencias y potencialidades identificadas. En el estudio, se utilizó un enfoque predominantemente descriptivo y cualitativo, sustentado en el método dialéctico. Como resultado se presenta el sistema de acciones orientado a la virtualización educativa, aprobado a partir del criterio de expertos, y se proyecta una etapa de valoración posterior de su aplicabilidad