GTC OSIRIS transiting exoplanet atmospheric survey: detection of sodium in XO-2b from differential long-slit spectroscopy

We present two transits of the hot-Jupiter exoplanet XO-2b using the Gran Telescopio Canarias (GTC). The time series observations were performed using long-slit spectroscopy of XO-2 and a nearby reference star with the OSIRIS instrument, enabling differential specrophotometric transit lightcurves capable of measuring the exoplanet's transmission spectrum. Two optical low-resolution grisms were used to cover the optical wavelength range from 3800 to 9300{\AA}. We find that sub-mmag level slit losses between the target and reference star prevent full optical transmission spectra from being constructed, limiting our analysis to differential absorption depths over ~1000{\AA} regions. Wider long slits or multi-object grism spectroscopy with wide masks will likely prove effective in minimising the observed slit-loss trends. During both transits, we detect significant absorption in the planetary atmosphere of XO-2b using a 50{\AA} bandpass centred on the Na I doublet, with absorption depths of Delta(R_pl/R_star)^2=0.049+/-0.017 % using the R500R grism and 0.047+/-0.011 % using the R500B grism (combined 5.2-sigma significance from both transits). The sodium feature is unresolved in our low-resolution spectra, with detailed modelling also likely ruling out significant line-wing absorption over an ~800{\AA} region surrounding the doublet. Combined with narrowband photometric measurements, XO-2b is the first hot Jupiter with evidence for both sodium and potassium present in the planet's atmosphere.Comment: 9 pages, 10 figures, 1 table, accepted for publication in MNRA

Olfactory preference for ethanol following social interaction with an intoxicated peer in adolescent rats exposed to ethanol in-utero

Background: Prenatal exposure to ethanol and later socially mediated exposure predicts ethanol intake in human adolescents. Animal rat models indicate that brief interactions with an ethanol-intoxicated peer result in heightened preference for ethanol odor and ethanol intake. Methods: This study assessed preference for ethanol odor in adolescent male rats (observers) following social interaction with an ethanol intoxicated peer (demonstrators) as a function of prenatal ethanol exposure (gestational days 17-20, 1.0 g/kg, intragastric). Social behavior and locomotion during social interaction was also measured. Results: Social investigation was greater in observers that interacted with an intoxicated demonstrator in comparison to those that interacted with a sober peer. Social contact increased when the demonstrator was under the effects of ethanol, but only if the observer had experienced ethanol prenatally. Ethanol inhibited locomotion in the demonstrators. Finally, social interaction with an intoxicated peer during adolescence as well as prenatal ethanol experience increased preference for ethanol odor. Conclusions: Fetal exposure to ethanol mediated by maternal intoxication at late gestation or by interaction with an intoxicated peer at adolescence heightens preference for the chemosensory cues of the drug

Mechanical based rigid registration of 3D objects: application to multimodal medical images

The registration of 3-D objects is an important problem in computer vision and especially in medical imaging. It arises when data acquired by different sensors and/or at different times have to be fused. Under the basic assumption that the objects to be registered are rigid, the problem is to recover the six parameters of a rigid transformation. If landmarks or common characteristics are not available, the problem has to be solved by an iterative method . However such methods are inevitably attracted to local minima. This paper presents a novel iterative method designed for the rigid registration of 3-D objects . Its originality lies in its physical basis : instead of minimizing an energy function with respect to the parameters of the rigid transformation (the classical approach) the minimization is achieved by studying the motion of a rigid object in a potential field. In particular we consider the kinetic energy of the solid during the registration process, which allows it to "jump over" some local maxima of the potential energy and so avoid some local minima of that energy. We present extensive experimental results on real 3-D medical images. In that particular application, we perform the matching process with the whole segmented volumes .La mise en correspondance d'objets 3D est un problème important dans le domaine du traitement d'image. Il apparaît lorsque des données acquises par différents capteurs, à des moments ou/et des instants différents doivent être fusionnées. Si l'on suppose que les objets à mettre en correspondance sont rigides, nous avons a retrouver les paramètres d'une transformation rigide. Lorsque l'utilisatin d'amers ou de caractéristiques communes n'est pas possible pour résoudre cette tache, une méthode itérative peut êre utilisée avec profit. Cet article présente une méthode itérative générale pour la mise en correspondance d'objets 3D. Son originalité réside dans ses fondements mecaniques: plutôt que de minimiser une énergie potentielle par rapport aux paramètres de la transformation rigide, qui est l'approche classique, nous étudions le mouvement d'un objet rigide, c'est-à-dire un solide, dans un champ de potentiel. Cette approche particulière prend en compte l'énergie cinétique du solide, ce qui permet de «sauter» certains maxima locaux de l'énergie potentielle et donc d'en éviter certains minima locaux. Nous montrons que notre approche, si l'on considère l'énergie cinétique toujours nulle, est équivalente à une méthode de descente de gradient, l'introduction de la vitesse permet donc d'en accélérer la convergence. En outre, nous montrons que notre méthode se laisse moins facilement «piéger» par les minima locaux de l'énergie que les méthodes classiques de minimisation. L'article est illustré par l'application de la méthode au recalage d'images médicales réelles, ou nous utilisons la totalité du volume segment

Do personality traits affect productivity? Evidence from the lab

While survey data supports a strong relationship between personality and labor market outcomes, the exact mechanisms behind this association remain unexplored. In this paper, we take advantage of a controlled laboratory set-up to test whether this relationship operates through productivity, and isolate this mechanism from other channels such as bargaining ability or self-selection into jobs. Using a gender neutral real-effort task, we analyse the impact of the Big Five personality traits on performance. We find that more neurotic subjects perform worse, and that more conscientious individuals perform better. These findings are in line with previous survey studies and suggest that at least part of the effect of personality on labor market outcomes operates through productivity. In addition, we find evidence that gender and university major affect the impact of the Big Five personality traits on performance