Asteroseismology of ZZ Ceti stars with fully evolutionary white dwarf models: I. The impact of the uncertainties from prior evolution on the period spectrum

ZZ Ceti stars are pulsating white dwarfs with a carbon-oxygen core build up during the core helium burning and thermally pulsing Asymptotic Giant Branch phases. Through the interpretation of their pulsation periods by means of asteroseismology, details about their origin and evolution can be inferred. The whole pulsation spectrum exhibited by ZZ Ceti stars strongly depends on the inner chemical structure. At present, there are several processes affecting the chemical profiles that are still not accurately determined. We present a study of the impact of the current uncertainties of the white dwarf formation and evolution on the expected pulsation properties of ZZ Ceti stars. Our analysis is based on a set of carbon-oxygen core white dwarf models with masses $0.548$ and 0.837 M_{\sun} derived from full evolutionary computations from the ZAMS to the ZZ Ceti domain. We have considered models in which we varied the number of thermal pulses, the amount of overshooting, and the $^{12}$C$(\alpha,\gamma)^{16}$O reaction rate within their uncertainties. We explore the impact of these major uncertainties in prior evolution on the chemical structure and the expected pulsation spectrum. We find that these uncertainties yield significant changes in the $g$-mode pulsation periods. We conclude that the uncertainties in the white dwarf progenitor evolution should be be taken into account in detailed asterseismological analysis of these pulsating stars.Comment: 7 pages, 8 figures. To be published in Astronomy and Astrophysic

Classical communication cost of quantum steering

Quantum steering is observed when performing appropriate local measurements on an entangled state. Here we discuss the possibility of simulating classically this effect, using classical communication instead of entanglement. We show that infinite communication is necessary for exactly simulating steering for any pure entangled state, as well as for a class of mixed entangled states. Moreover, we discuss the communication cost of steering for general entangled states, as well as approximate simulation. Our findings reveal striking differences between Bell nonlocality and steering, and provide a natural way of measuring the strength of the latter.Comment: 7 pages, 1 figure. See also arXiv:1603.xxxxx for related work by S. Nagy and T. V\'ertes

Retos en la Identificación de los Alumnos Superdotados: Cuestiones relacionadas con la Evaluación Psicológica.

This paper discusses issues related to the assessment of children and youth for the identification of giftedness, and presents specific rec-ommendations for educational measures in order to attend to the particular characteristics and needs of these students. We outline the most common difficulties related to the psychological assessment of these children, in-cluding the lack of adequate instruments for the assessment of the multiple dimensions of giftedness, as well as the shortage of training for this identi-fication. Regarding these difficulties, we describe some assessment procedures that assure higher levels of objectivity and validity in data, reducing the possibil-ity of false positives and false negatives in the identification of these stu-dents. In addition to psychological tests, we present the advantages of us-ing multiple informants and the contribution of different professionals and parents for this assessment. On the other hand, as we present giftedness as a result of a developmental process, it is important to conduct students’ as-sessment in phases, including an initial screening phase, followed by the sound assessment of students and nurturing. Finally, we present some sug-gestions for the advancement in giftedness identification and assessment, as a means to support the development of research in this area.Este artículo analiza los temas relacionados con la identificación de los estudiantes superdotados y recoge algunas recomendaciones específicas sobre medidas educativas, con el fin de responder a la diversidad de estos estudiantes. Se plantean las dificultades más comunes relacionadas con la evaluación psicológica de estos estudiantes, entre ellas la falta de instrumentos adecuados para la evaluación de las múltiples dimensiones de la superdotación y el talento, así como, la falta de formación que tienen los profesionales para esta identificación. Con respecto a estas dificultades, se describen algunos procedimientos de evaluación con el fin de asegurar mayores niveles de objetividad y validez de los datos, lo que reduce la posibilidad de falsos positivos y falsos negativos en la identificación de estos estudiantes. Además de las pruebas psicológicas, se presentan las ventajas del uso de diferentes fuentes de información y la contribución de los distintos profesionales y padres para esta evaluación. Por otro lado, es importante llevar a cabo la evaluación de los estudiantes superdotados por fases, incluyendo una fase de evaluación inicial (screening), seguida de la fase de diagnóstico o identificación; y la fase final, orientada a atender a la diversidad de estos estudiantes. Por último, se presentan algunas sugerencias para el avance en la identificación y evaluación de la superdotación, como un medio para apoyar el desarrollo de la investigación en este área.This article has been produced with the financial support by Spanish Ministry of Science and Technology (EDU2014-53646-R)

Fully nonlocal quantum correlations

Quantum mechanics is a nonlocal theory, but not as nonlocal as the no-signalling principle allows. However, there exist quantum correlations that exhibit maximal nonlocality: they are as nonlocal as any non-signalling correlations and thus have a local content, quantified by the fraction $p_L$ of events admitting a local description, equal to zero. Exploiting the link between the Kochen-Specker and Bell's theorems, we derive, from every Kochen-Specker proof, Bell inequalities maximally violated by quantum correlations. We then show that these Bell inequalities lead to experimental bounds on the local content of quantum correlations which are significantly better than those based on other constructions. We perform the experimental demonstration of a Bell test originating from the Peres-Mermin Kochen-Specker proof, providing an upper bound on the local content $p_L\lesssim 0.22$.Comment: 9 pages, 5 figures and three tables. To appear in PR

Reacciones de ciclización reductiva para la síntesis de nuevas benzodiazepinonas y benzotiadiazepinas S,S-dióxido

En este trabajo se describe la síntesis y ciclización de N-(2-nitrobencil)-2-cloroacetamidas así como de N-(2-aminobencil)-1-bromometansulfonamidas. La anelación de las amidas se produjo por ciclización reductiva con Fe proporcionando 1,2,4,5-tetrahidro-1,4-benzodiazepin-3-onas con muy buenos rendimientos. Para el caso de las N-(2-aminobencil)-1-bromometansulfonamidas, éstas fueron sometidas a ciclización intramolecular en distintos solventes (DMF, sulfolano) a distintas temperaturas no pudiéndose obtener el producto ciclado (3,1,4-benzotiadiazepinas 3,3-dióxido). En su defecto se obtuvo el producto de la reducción del grupo bromometansulfonilo a metansulfonilo con rendimientos aceptables. Todos los productos formados fueron caracterizados por espectroscopia 1H-RMN y 13C-RMN mono y bidimensional

Seismology Of A Massive Pulsating Hydrogen Atmosphere White Dwarf

We report our observations of the new pulsating hydrogen atmosphere white dwarf SDSS J132350.28+010304.22. We discovered periodic photometric variations in frequency and amplitude that are commensurate with nonradial g-mode pulsations in ZZ Ceti stars. This, along with estimates for the star's temperature and gravity, establishes it as a massive ZZ Ceti star. We used time-series photometric observations with the 4.1 m SOAR Telescope, complemented by contemporary McDonald Observatory 2.1 m data, to discover the photometric variability. The light curve of SDSS J132350.28+010304.22 shows at least nine detectable frequencies. We used these frequencies to make an asteroseismic determination of the total mass and effective temperature of the star: M-star = 0.88 +/- 0.02 M-circle dot and T-eff = 12,100 +/- 140 K. These values are consistent with those derived from the the optical spectra and photometric colors.CNPqFAPERGS/PronexUS National Science Foundation AST-0909107Norman Hackerman Advanced Research Program 003658-0252-2009MICINN grant AYA08-1839/ESPESF EUROCORES Program EuroGENESIS (MICINN grant) EUI2009-04170Generalitat de Catalunya 2009SGR315EU-FEDER fundsAGENCIA through the Programa de Modernizacion Tecnologica BID 1728/OC-ARCONICET PIP 112-200801-00940Astronom

Description of a Eulerian–Lagrangian Approach for the Modeling of Cooling Water Droplets

The present paper describes a tool developed in-house for the modeling of free-falling water droplet cooling processes. A two-way coupling model is employed to account for the interactions between the droplets and the carrier fluid, following a Eulerian-Lagrangian approach. In addition, a stochastic separated flow technique is employed, involving random sampling of the fluctuating fluid velocity. In physical modeling, two empirical correlations are considered for determining the heat and mass transfer coefficients, with the possibility of accounting for vibrations. The numerical results indicate the preponderance of the interactions between droplet and carrier fluid at various humidity ratios.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

Characterization of a Two-way Coupling Approach for the Simulation of Fluid Flows under Cryogenic Conditions

Ice formation at lifting surfaces and engine intakes is a significant issue affecting regular aircraft operation. The icing on a wing’s leading edge perturbs the airflow around the wing, contributing to a decrease in lift and increasing drag. A step towards the understanding of droplet dynamics under cryogenics is made in the present work. An in-house developed tool is used to study the impact of droplet diameter and air humidity ratio in free-falling water droplets’ flow dynamics. The 3D Navier-Stokes equations are solved in a RANS-based two-way coupling model, which considers that the carrier fluid properties are modified by the presence of a dispersed phase, accounting for mass exchange momentum and energy between them. A Lagrangian/Eulerian formulation is employed to model each of the considered phases. The results obtained are compared with a one-way modeling approach and experimental data to infer the interacting phases’ effect in the overall process dynamics. In this way, it is possible to conclude that for high humidity content, this interaction is predominant and, consequently, needs to be taken into consideration. However, for low humidity ratios, the one-way coupling is a sufficient approximation to the experimental data.Fundação para a Ciência e a Tecnologiainfo:eu-repo/semantics/publishedVersio

Catalytic performance of bulk and colloidal Co/Al layered double hydroxide with Au nanoparticles in aerobic olefin oxidation

A Co/Al layered double hydroxide material was synthesized in both bulk and exfoliated (colloidal) forms. Anion exchange with methionine allowed immobilization of Au nanoparticles previously prepared by a biomimetic method using an anti-oxidant tea aqueous extract to reduce the Au salt solution. The catalytic performance of bulk and exfoliated clays Au-hybrid materials was assessed in aerobic olefin epoxidation. Both catalysts were very active towards the epoxide products and with very interesting substrate conversion levels after 80 h reaction time. The Au-exfoliated material, where the nanosheets work as large ligands, yielded higher product stereoselectivity in the case of limonene epoxidation. This arises from a confined environment around the Au nanoparticles wrapped by the clay nanosheets modulating access to the catalytic active centres by reagents. Mechanistic assessment was also accomplished for styrene oxidation by DFT methodspublishe

Protótipo de aplicativo para dispositivos móveis compatível com uma impresora 3D de alimentos.

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