Improvements on analytic modelling of stellar spots

In this work we present the solution of the stellar spot problem using the Kelvin-Stokes theorem. Our result is applicable for any given location and dimension of the spots on the stellar surface. We present explicitely the result up to the second degree in the limb darkening law. This technique can be used to calculate very efficiently mutual photometric effects produced by eclipsing bodies occulting stellar spots and to construct complex spot shapes.Comment: Resubmitted to MNRAS after accounting for minor comments of second review, 9 pages, 5 figures, software available at http://eduscisoft.com/KSINT

SOAP-T: A tool to study the light-curve and radial velocity of a system with a transiting planet and a rotating spotted star

We present an improved version of SOAP (Boisse et al. 2012) named "SOAP-T", which can generate the radial velocity variations and light-curves for systems consisting of a rotating spotted star with a transiting planet. This tool can be used to study the anomalies inside transit light-curves and the Rossiter-McLaughlin effect, to better constrain the orbital configuration and properties of planetary systems and active zones of their host stars. Tests of the code are presented to illustrate its performance and to validate its capability when compared with analytical models and real data. Finally, we apply SOAP-T to the active star, HAT-P-11, observed by the NASA Kepler space telescope and use this system to discuss the capability of this tool in analyzing light-curves for the cases where the transiting planet overlaps with the star's spots.Comment: 9 pages, 7 figures, accepted for publication in Astronomy and Astrophysic

Non universality of entanglement convertibility

Recently, it has been suggested that operational properties connected to quantum computation can be alternative indicators of quantum phase transitions. In this work we systematically study these operational properties in 1D systems that present phase transitions of different orders. For this purpose, we evaluate the local convertibility between bipartite ground states. Our results suggest that the operational properties, related to non-analyticities of the entanglement spectrum, are good detectors of explicit symmetries of the model, but not necessarily of phase transitions. We also show that thermodynamically equivalent phases, such as Luttinger liquids, may display different convertibility properties depending on the underlying microscopic model.Comment: 5 pages + references, 4 figures - improved versio

Transport Processes in Metal-Insulator Granular Layers

Tunnel transport processes are considered in a square lattice of metallic nanogranules embedded into insulating host to model tunnel conduction in real metal/insulator granular layers. Based on a simple model with three possible charging states ($\pm$, or 0) of a granule and three kinetic processes (creation or recombination of a $\pm$ pair, and charge transfer) between neighbor granules, the mean-field kinetic theory is developed. It describes the interplay between charging energy and temperature and between the applied electric field and the Coulomb fields by the non-compensated charge density. The resulting charge and current distributions are found to be essentially different in the free area (FA), between the metallic contacts, or in the contact areas (CA), beneath those contacts. Thus, the steady state dc transport is only compatible with zero charge density and ohmic resistivity in FA, but charge accumulation and non-ohmic behavior are \emph{necessary} for conduction over CA. The approximate analytic solutions are obtained for characteristic regimes (low or high charge density) of such conduction. The comparison is done with the measurement data on tunnel transport in related experimental systems.Comment: 10 pages, 11 figures, 1 reference corrected, acknowlegments adde

Herdabilidades e estimativas do número mínimo de genes para os caracteres comprimento da haste principal e dias para floração em três cruzamentos de feijão-caupi.

Neste trabalho são apresentadas as estiativas de herdabilidades e do número de genes para os caracteres comprimento da vagem e dias para floração nos cruzamentos IPA 206 x PI 293588, Epace 11 x PI 293588 e BR 17 Gurgueia x PI 293588, avaliados nas condições de Petrolina, PE.Suplemento. Edição dos resumos expandidos do 45 Congresso Brasileiro de Olericultura; 15 Congresso Brasileiro de Floricultura e Planta Ornamentais; 2 Congresso Brasileiro de Cultura de Tecidos de Plantas, Fortaleza, ago. 2005

Improved thermal isolation of silicon suspended platforms for an all-silicon thermoelectric microgenerator based on large scale integration of Si nanowires as thermoelectric material

Special suspended micro-platforms have been designed as a part of silicon compatible planar thermoelectric microgenerators. Bottom-up grown silicon nanowires are going to bridge in the future such platforms to the surrounding silicon bulk rim. They will act as thermoelectric material thus configuring an all-silicon thermoelectric device. In the new platform design other additional bridging elements (usually auxiliary support silicon beams) are substituted by low conductance thin film dielectric membranes in order to maximize the temperature difference developed between both areas. These membranes follow a sieve-like design that allows fabricating them with a short additional wet anisotropic etch step. © Published under licence by IOP Publishing Ltd.Peer ReviewedPostprint (published version

Chemical abundances of 1111 FGK stars from the HARPS GTO planet search program II: Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd and Eu

To understand the formation and evolution of the different stellar populations within our Galaxy it is essential to combine detailed kinematical and chemical information for large samples of stars. We derive chemical abundances of Cu, Zn, Sr, Y, Zr, Ba, Ce, Nd and Eu for a large sample of more than 1000 FGK dwarf stars with high-resolution ($R \sim$\,115000) and high-quality spectra from the HARPS-GTO program. The abundances are derived by a standard Local Thermodinamyc Equilibrium (LTE) analysis using measured Equivalent Widths (EWs) injected to the code MOOG and a grid of Kurucz ATLAS9 atmospheres. We find that thick disk stars are chemically disjunct for Zn and Eu and also show on average higher Zr but lower Ba and Y when compared to the thin disk stars. We also discovered that the previously identified high-$\alpha$ metal-rich population is also enhanced in Cu, Zn, Nd and Eu with respect to the thin disk but presents Ba and Y abundances lower on average, following the trend of thick disk stars towards higher metallities and further supporting the different chemical composition of this population. The ratio of heavy-s to light-s elements of thin disk stars presents the expected behaviour (increasing towards lower metallicities) and can be explained by a major contribution of low-mass AGB stars for s-process production at disk metallicities. However, the opposite trend found for thick disk stars suggests that intermediate-mass AGB stars played an important role in the enrichment of the gas from where these stars formed. Previous works in the literature also point to a possible primary production of light-s elements at low metallicities to explain this trend. Finally, we also find an enhancement of light-s elements in the thin disk at super solar metallicities which could be caused by the contribution of metal-rich AGB stars. (short version)Comment: 20 pages, 19 figures, accepted by A&

A new analysis of the WASP-3 system: no evidence for an additional companion

In this work we investigate the problem concerning the presence of additional bodies gravitationally bounded with the WASP-3 system. We present eight new transits of this planet and analyse all the photometric and radial velocity data published so far. We did not observe significant periodicities in the Fourier spectrum of the observed minus calculated (O-C) transit timing and radial velocity diagrams (the highest peak having false-alarm probabilities of 56 per cent and 31 per cent, respectively) or long-term trends. Combining all the available information, we conclude that the radial velocity and transit timing techniques exclude, at 99 per cent confidence limit, any perturber more massive than M \gtrsim 100 M_Earth with periods up to 10 times the period of the inner planet. We also investigate the possible presence of an exomoon on this system and determined that considering the scatter of the O-C transit timing residuals a coplanar exomoon would likely produce detectable transits. This hypothesis is however apparently ruled out by observations conducted by other researchers. In case the orbit of the moon is not coplanar the accuracy of our transit timing and transit duration measurements prevents any significant statement. Interestingly, on the basis of our reanalysis of SOPHIE data we noted that WASP-3 passed from a less active (log R'_hk=-4.95) to a more active (log R'_hk=-4.8) state during the 3 yr monitoring period spanned by the observations. Despite no clear spot crossing has been reported for this system, this analysis claims for a more intensive monitoring of the activity level of this star in order to understand its impact on photometric and radial velocity measurements.Comment: MNRAS accepted (14/08/2012

Diffraction and an infrared finite gluon propagator

We discuss some phenomenological applications of an infrared finite gluon propagator characterized by a dynamically generated gluon mass. In particular we compute the effect of the dynamical gluon mass on $pp$ and ${\bar{p}}p$ diffractive scattering. We also show how the data on $\gamma p$ photoproduction and hadronic $\gamma \gamma$ reactions can be derived from the $pp$ and $\bar{p}p$ forward scattering amplitudes by assuming vector meson dominance and the additive quark model.Comment: 4 pages, 7 figures, added references and figures, changed structure. Contribution to Proceedings of XVIIIth Reuniao de Trabalho sobre Interacoes Hadronicas, Sao Paulo, Brazil, 22-24 May, 200

Light elements in stars with exoplanets

It is well known that stars orbited by giant planets have higher abundances of heavy elements when compared with average field dwarfs. A number of studies have also addressed the possibility that light element abundances are different in these stars. In this paper we will review the present status of these studies. The most significant trends will be discussed.Comment: 10 pages, 6 figures. Submitted to the proceedings of IAU symposium 268: Light elements in the universe