CdTe semiconductor nanowires and NiFe ferro-magnetic metal nanowires electrodeposited into cylindrical nano-pores on the surface of anodized aluminum

Cylindrical nano-pores of an anodized aluminum oxide layer on the surface of bulk aluminum were used as templates for the electrochemical growth of semiconductor and magnetic nanowires. The electrodeposition of CdTe and NiFe was investigated to determine the optimum conditions for each nanowire growth over a wide range of cathode potentials. The desired composition of Cd50Te50 and Ni80Fe20 was achieved by controlling the cathode potential during electrodeposition. Temperature dependences of resistance for CdTe nanowires confirmed the semiconductor character with amorphous behavior at low temperature, while those of NiFe nanowires showed metallic character. The anisotropic magnetoresistance (AMR) of NiFe nanowires reached 1.9% at 300

Covering codes in Sierpinski graphs

Graphs and AlgorithmsInternational audienceFor a graph G and integers a and b, an (a, b)-code of G is a set C of vertices such that any vertex from C has exactly a neighbors in C and any vertex not in C has exactly b neighbors in C. In this paper we classify integers a and b for which there exist (a, b)-codes in Sierpinski graphs

Evidence of high dissipation in magnetization reversal processes of five Co/Cu bilayers

Heat and charge transport perpendicular to the plan in five Co/Cu stacks are studied using AC temperature gradients in the presence of a DC current. Large peaks in AC voltage response versus applied field are observed. This effect, measured only in reversible magnetization reversal modes and at sharp values of magnetic fields, suggests that an extra dissipation process is produced at well-defined magnetic configurations

Audio source separation with one sensor for robust speech recognition

International audienceIn this paper, we address the problem of noise compensation in speech signals for robust speech recognition. Several classical denoising methods in the field of speech and signal processing are compared on speech corrupted by music, which correspond to a frequent situation in broadcast news transcription tasks. We also present two new source separation techniques, namely adaptive Wiener filtering and adaptive shrinkage. These techniques rely on the use of a dictionary of spectral shapes to deal with the non stationarity of the signals. The algorithms are first compared on the source separation task and assessed in terms of average distortion. Their effect on the entire transcription system is eventually compared in terms of word error rate. Results show that the proposed adaptive Wiener filter approach yields a significant improvement of the transcription accuracy at signal/noise ratios greater than 15 dB

Covering codes in Sierpinski graphs

Graphs and Algorithm

Enhanced magnetic field sensitivity of spin-dependent transport in cluster-assembled metallic nanostructures

The emerging field of spintronics explores the many possibilities offered by the prospect of using the spin of the electrons for fast, nanosized electronic devices. The effect of magnetization acting on a current is the essence of giant or tunnel magnetoresistance. Although such spintronics effects already find technological applications, much of the underlying physics remains to be explored. The aim of this article is to demonstrate the importance of spin mixing in metallic nanostructures. Here we show that magnetic clusters embedded in a metallic matrix exhibit a giant magnetic response of more than 500% at low temperature, using a recently developed thermoelectric measurement. This method eliminates the dominating resistivity component of the magnetic response and thus reveals an intrinsic spin-dependent process: the conduction-electron spin precession about the exchange field as the electron crosses the clusters, giving rise to a spin-mixing mechanism with strong field dependence. This effect appears sensibly only in the smallest clusters, that is, at the level of less than 100 atoms per cluster

EMA - A R package for Easy Microarray data analysis

<p>Abstract</p> <p>Background</p> <p>The increasing number of methodologies and tools currently available to analyse gene expression microarray data can be confusing for non specialist users.</p> <p>Findings</p> <p>Based on the experience of biostatisticians of Institut Curie, we propose both a clear analysis strategy and a selection of tools to investigate microarray gene expression data. The most usual and relevant existing R functions were discussed, validated and gathered in an easy-to-use R package (EMA) devoted to gene expression microarray analysis. These functions were improved for ease of use, enhanced visualisation and better interpretation of results.</p> <p>Conclusions</p> <p>Strategy and tools proposed in the EMA R package could provide a useful starting point for many microarrays users. EMA is part of Comprehensive R Archive Network and is freely available at <url>http://bioinfo.curie.fr/projects/ema/</url>.</p

Autour de problèmes de plongements de graphes

Cette thèse s'articule autour de la notion de plongement de graphe. Un plongement de graphe consiste à envoyer les sommets d'un graphe dans une autre structure par une application qui conserve certaines propriétés à déterminer. Nous pouvons distinguer deux grandes familles de plongements. D'une part les plongements purement combinatoires qui envoient les éléments d'un graphe G dans un autre graphe H. La propriété la plus naturelle à conserver est la notion d'adjacence entre les sommets. Nous nous intéressons à la conservation d'une propriété supplémentaire : la distance entre les sommets. Nous caractérisons plusieurs familles de graphes se plongeant de cette façon dans les hypercubes ou les graphes de Hamming. Les plongements topologiques visent à représenter un graphe G sur une surface quelconque. Les sommets sont envoyés vers des points d'une surface et les arêtes vers des courbes continues entre ces points. Comment représenter un graphe afin de minimiser le nombre de croisements d'arêtes ? Nous nous posons ces questions à travers l'étude de la planarité et des nombres de croisements de certains graphes.This Ph.D. manuscript is built around the notion of graph embedding. An embedding of a graph G is an application mapping the vertices of G to elements of another structure, and preserving some properties of G. There are two types of embeddings. The combinatorial embeddings map the vertices of a graph G to the vertices of a graph H. The usual property that is preserved is the adjacency between vertices. In this thesis, we consider the isometric embeddings, preserving in addition the distances between vertices. We give some structural characterizations for families of graphs isometrically embeddable in hypercubes or Hamming graphs. The topological embeddings aim at drawing a graph G on some surface. Vertices are mapped to distinct points of the surface and the edges are represented by continuous curves linking these points. Is it possible to draw a graph G so that the edges do not cross eachother ? If not, what is the minimum number of crossings of a drawing of G ? We deal with these questions on different surfaces, or in relation with some graph operations as direct product or zip product.GRENOBLE1-BU Sciences (384212103) / SudocSudocFranceF