On the frequency dependence of p-mode frequency shifts induced by magnetic activity in Kepler solar-like stars

The variations of the frequencies of the low-degree acoustic oscillations in the Sun induced by magnetic activity show a dependence with radial order. The frequency shifts are observed to increase towards higher-order modes to reach a maximum of about 0.8 muHz over the 11-yr solar cycle. A comparable frequency dependence is also measured in two other main-sequence solar-like stars, the F-star HD49933, and the young 1-Gyr-old solar analog KIC10644253, although with different amplitudes of the shifts of about 2 muHz and 0.5 muHz respectively. Our objective here is to extend this analysis to stars with different masses, metallicities, and evolutionary stages. From an initial set of 87 Kepler solar-like oscillating stars with already known individual p-mode frequencies, we identify five stars showing frequency shifts that can be considered reliable using selection criteria based on Monte Carlo simulations and on the photospheric magnetic activity proxy Sph. The frequency dependence of the frequency shifts of four of these stars could be measured for the l=0 and l=1 modes individually. Given the quality of the data, the results could indicate that a different physical source of perturbation than in the Sun is dominating in this sample of solar-like stars.Comment: Accepted for publication in A&

Psychological well-being in dancers: a social cognitive analysis

Este estudio analizó el clima motivacional, la satisfacción de necesidades, la motivación autodeterminada y la satisfacción/interés como predictores del bienestar psicológico de 303 bailarines. Se utilizaron escalas traducidas al castellano y adaptadas a la danza: PMCSQ (Perception of Motivational Climate Sport Questionaire), SMS (Sport Motivation Scale), SSI (Sport Satisfaction and Interest Scale) y PGWB (Perceived General Well-Being Scale); y cinco ítems elaborados en el estudio para medir el clima autodeterminante. Se planteó un modelo de relaciones causales con la siguientes secuencia: clima rendimiento y maestría → clima autodeterminante → satisfacción necesidades → motivación → satisfacción/interés → bienestar psicológico. Adicionalmente el modelo contemplaba las relaciones: Clima rendimiento y clima maestría → motivación; y satisfacción de necesidades y motivación → bienestar psicológico. El modelo se analizó mediante SEM y mostró significación para las relaciones hipotetizadas e índices de ajuste aceptables, apoyando los postulados de la Teoría de las Metas de Logro y la Teoría de la AutodeterminaciónThis study analysed the following variables: motivational climate, need satisfaction, motivation and satisfaction/interest, as predictors of psychological well-being of 303 dancers. Four scales were translated to Spanish and adapted to dance: PMCSQ (Perception of Motivational Climate in Sport Questionnaire), SMS (Sport Motivation Scale), SSI (Sport Satisfaction and Interest Scale), (PGWB (Perceived General Well-Being Scale); and five items were specifically created to measure self-determinant climate. A structural model with the following sequence: performance and mastery climates → self-determinant climate → need satisfaction → motivation → satisfaction/interest → psychological well-being, was proposed. The model also studied the following relationships: performance and mastery climates → motivation; and need satisfaction and motivation → psychological well-being. Model was analysed with SEM (Structural Equation Modelling). Results verified the hypothesized relationships, and fit indexes of the model were acceptable. Theories of Achievement Motivation and Self-Determination were supporte

Quark-mass dependence of baryon resonances

We study the quark-mass dependence of J^P = \frac12^- s-wave and J^P = \frac32^- d-wave baryon resonances. Parameter-free results are obtained in terms of the leading order chiral Lagrangian. In the 'heavy' SU(3) limit with m_\pi =m_K \simeq 500 MeV the s-wave resonances turn into bound states forming two octets plus a singlet representations of the SU(3) group. Similarly the d-wave resonances turn into bound states forming an octet and a decuplet in this limit. A contrasted result is obtained in the 'light' SU(3) limit with m_\pi =m_K \simeq 140 MeV for which no resonances exist.Comment: 8 pages, three figures, talk presented at HYP200

The silicon stable isotope distribution along the GEOVIDE section (GEOTRACES GA-01) of the North Atlantic Ocean

The stable isotope composition of dissolved silicon in seawater (δ30SiDSi) was examined at 10 stations along the GEOVIDE section (GEOTRACES GA-01), spanning the North Atlantic Ocean (40–60∘ N) and Labrador Sea. Variations in δ30SiDSi below 500 m were closely tied to the distribution of water masses. Higher δ30SiDSi values are associated with intermediate and deep water masses of northern Atlantic or Arctic Ocean origin, whilst lower δ30SiDSi values are associated with DSi-rich waters sourced ultimately from the Southern Ocean. Correspondingly, the lowest δ30SiDSi values were observed in the deep and abyssal eastern North Atlantic, where dense southern-sourced waters dominate. The extent to which the spreading of water masses influences the δ30SiDSi distribution is marked clearly by Labrador Sea Water (LSW), whose high δ30SiDSi signature is visible not only within its region of formation within the Labrador and Irminger seas, but also throughout the mid-depth western and eastern North Atlantic Ocean. Both δ30SiDSi and hydrographic parameters document the circulation of LSW into the eastern North Atlantic, where it overlies southern-sourced Lower Deep Water. The GEOVIDE δ30SiDSi distribution thus provides a clear view of the direct interaction between subpolar/polar water masses of northern and southern origin, and allow examination of the extent to which these far-field signals influence the local δ30SiDSi distribution

Security of continuous-variable quantum key distribution against general attacks

We prove the security of Gaussian continuous-variable quantum key distribution against arbitrary attacks in the finite-size regime. The novelty of our proof is to consider symmetries of quantum key distribution in phase space in order to show that, to good approximation, the Hilbert space of interest can be considered to be finite-dimensional, thereby allowing for the use of the postselection technique introduced by Christandl, Koenig and Renner (Phys. Rev. Lett. 102, 020504 (2009)). Our result greatly improves on previous work based on the de Finetti theorem which could not provide security for realistic, finite-size, implementations.Comment: 5 pages, plus 11 page appendi