Analyse minérale de tissus végétaux à faible teneur en silice : proposition d'une technique de minéralisation simplifiée et d'un plan d'organisation de la méthode d'analyse multiélémentaire

On propose une technique de minéralisation simplifiée d'échantillons de tissus végétaux, évitant l'usage de matériel en platine et l'application du traitement par l'acide fluorhydrique. Cette expérience prenant comme référence la méthode avec élimination de la silice par volatilisation, étudie les erreurs négatives qui peuvent apparaître lors de la détermination de la teneur en K, Ca, Mg et Na de diverses plantes. Cette technique est applicable aux végétaux dont la teneur en silice est inférieure à 2% car les erreurs contrôlées dans ce cas ne dépassent pas l'écart-type des méthodes d'analyse. Certaines espèces végétales, malgré leur teneur élevée en silice, ont un comportement particulier et ne révèlent que de faibles erreurs. Enfin, on présente un plan d'organisation coordonnée pour mener à bien l'analyse multiélémentaire (P, Ca, Mg, K, Na, B, Cu, Fe, Mn, et Zn

Optical lattices as a tool to study defect-induced superfluidity

We study the superfluid response, the energetic and structural properties of a one-dimensional ultracold Bose gas in an optical lattice of arbitrary strength. We use the Bose-Fermi mapping in the limit of infinitely large repulsive interaction and the diffusion Monte Carlo method in the case of finite interaction. For slightly incommensurate fillings we find a superfluid behavior which is discussed in terms of vacancies and interstitials. It is shown that both the excitation spectrum and static structure factor are different for the cases of microscopic and macroscopic fractions of defects. This system provides a extremely well-controlled model for studying defect-induced superfluidity.Comment: 14 pages, 13 figures, published versio

Including fringe fields from a nearby ferromagnet in a percolation theory of organic magnetoresistance

Random hyperfine fields are essential to mechanisms of low-field magnetoresistance in organic semiconductors. Recent experiments have shown that another type of random field --- fringe fields due to a nearby ferromagnet --- can also dramatically affect the magnetoresistance. A theoretical analysis of the effect of these fringe fields is challenging, as the fringe field magnitudes and their correlation lengths are orders of magnitude larger than that of the hyperfine couplings. We extend a recent theory of organic magnetoresistance to calculate the magnetoresistance with both hyperfine and fringe fields present. This theory describes several key features of the experimental fringe-field magnetoresistance, including the applied fields where the magnetoresistance reaches extrema, the applied field range of large magnetoresistance effects from the fringe fields, and the sign of the effect.Comment: 5 pages, 4 figures. Accepted by Phys. Rev. B Rapid Communication

Evolucion reciente de los estudios de geomorfologia glaciar y periglaciar en España (1980-2000): balance y perspectivas

Se revisan las principales obras españolas que durante las últimas dos décadas (1980-2000) se han ocupado del estudio de la morfología glaciar y periglaciar. De su análisis y valoración crítica se obtienen datos referidos al avance del conocimiento en este dominio científico y a la evolución de sus técnicas y métodos de trabajo

Improving Spatial Codification in Semantic Segmentation

This paper explores novel approaches for improving the spatial codification for the pooling of local descriptors to solve the semantic segmentation problem. We propose to partition the image into three regions for each object to be described: Figure, Border and Ground. This partition aims at minimizing the influence of the image context on the object description and vice versa by introducing an intermediate zone around the object contour. Furthermore, we also propose a richer visual descriptor of the object by applying a Spatial Pyramid over the Figure region. Two novel Spatial Pyramid configurations are explored: Cartesian-based and crown-based Spatial Pyramids. We test these approaches with state-of-the-art techniques and show that they improve the Figure-Ground based pooling in the Pascal VOC 2011 and 2012 semantic segmentation challenges.Comment: Paper accepted at the IEEE International Conference on Image Processing, ICIP 2015. Quebec City, 27-30 September. Project page: https://imatge.upc.edu/web/publications/improving-spatial-codification-semantic-segmentatio

Williams Syndrome: The extent of agreement between parent and self report of psychological

Background and Objectives: People with Williams syndrome (WS) have been reported by their carers to have problems with attention, anxiety and social relationships. People with WS have been shown to report their anxieties. This study extends our knowledge of how people with WS see themselves in terms of behaviour and social relationships. Methods: A survey using self and parent report forms of the Strengths and Difficulties Questionnaire. Results: Both parents and individuals with WS (N = 31) reported difficulties in emotional disorder and hyperactivity symptoms and strengths in prosocial behaviours such as altruism and empathy. They disagreed about peer problems. Conclusions: People with WS understand some but not all of their difficulties. In particular they fail to recognize their social difficulties which may lead them to be vulnerable to exploitation.</p

Thickness dependence of dynamic and static magnetic properties of pulsed laser deposited La0.7_{0.7}Sr0.3_{0.3}MnO3_3 films on SrTiO3_3(001)

We present a comprehensive study of the thickness dependence of static and magneto-dynamic magnetic properties of La$_{0.7}$Sr$_{0.3}$MnO$_3$. Epitaxial pulsed laser deposited La$_{0.7}$Sr$_{0.3}$MnO$_3$ / SrTiO$_3$(001) thin films in the range from 3 unit cells (uc) to 40 uc (1.2 - 16 nm) have been investigated through ferromagnetic resonance spectroscopy (FMR) and SQUID magnetometry at variable temperature. Magnetodynamically, three different thickness, $d$, regimes are identified: 20 uc $\lesssim d$ uc where the system is bulk like, a transition region 8 uc $\le d \lesssim 20$ uc where the FMR line width and position depend on thickness and $d=6$ uc which displays significantly altered magnetodynamic properties, while still displaying bulk magnetization. Magnetization and FMR measurements are consistent with a nonmagnetic volume corresponding to $\sim$ 4 uc. We observe a reduction of Curie temperature ($T_C$) with decreasing thickness, which is coherent with a mean field model description. The reduced ordering temperature also accounts for the thickness dependence of the magnetic anisotropy constants and resonance fields. The damping of the system is strongly thickness dependent, and is for thin films dominated by thickness dependent anisotropies, yielding both a strong 2-magnon scattering close to $T_c$ and a low temperature broadening. For the bulk like samples a large part of the broadening can be linked to spread in magnetic anisotropies attributed to crystal imperfections/domain boundaries of the bulk like film