Unexpected Magnetism of Small Silver Clusters

The ground-state electronic, structural, and magnetic properties of small silver clusters, Ag$_n$ (2$\le$n$\le$22), have been studied using a linear combination of atomic Gaussian-type orbitals within the density functional theory. The results show that the silver atoms, which are diamagnetic in bulk environment, can be magnetic when they are grouped together in clusters. The Ag$_{13}$ cluster with icosahedral symmetry has the highest magnetic moment per atom among the studied silver clusters. The cluster symmetry and the reduced coordination number specific of small clusters reveal as a fundamental factor for the onset of the magnetism.Comment: 4 pages, 4 figure

L'évolution du travail des femmes en Italie : les inegalités entre les sexes et les difficultés de conciliation

Cet article étudie les déterminants de l’emploi des femmes en Italie au cours des vingt dernières années. Le but de cet article est celui d’examiner les facteurs qui ont influencé l’occupation des femmes sur le marché du travail en Italie en utilisant les données des recensements de la population de 1991 et 2001 et les données de l’It -SILC 2011, faites par l’ISTAT. En analysant les micro-données pour les trois périodes considérées on note comment les profils des femmes employées se sont modifiés soit au cours dans le temps par rapport aux non-occupées surtout pour ce qui est de l’âge, l’éducation, le nombre d’enfants et leur situation géographique. La répartition géographique reste l’un des indicateurs les plus importants là où les femmes du Nord continuent à avoir une probabilité significativement plus élevée d’être employée que dans le Centre et le Sud. Les résultats montrent que les femmes du Sud, qui sont face à un marché du travail plus difficile et un système de service quasi inexistants pour les enfants, se trouvent plus en difficulté

Spin excitations in a single La2_2CuO4_4 layer

The dynamics of S=1/2 quantum spins on a 2D square lattice lie at the heart of the mystery of the cuprates \cite{Hayden2004,Vignolle2007,Li2010,LeTacon2011,Coldea2001,Headings2010,Braicovich2010}. In bulk cuprates such as \LCO{}, the presence of a weak interlayer coupling stabilizes 3D N\'{e}el order up to high temperatures. In a truly 2D system however, thermal spin fluctuations melt long range order at any finite temperature \cite{Mermin1966}. Further, quantum spin fluctuations transfer magnetic spectral weight out of a well-defined magnon excitation into a magnetic continuum, the nature of which remains controversial \cite{Sandvik2001,Ho2001,Christensen2007,Headings2010}. Here, we measure the spin response of \emph{isolated one-unit-cell thick layers} of \LCO{}. We show that coherent magnons persist even in a single layer of \LCO{} despite the loss of magnetic order, with no evidence for resonating valence bond (RVB)-like spin correlations \cite{Anderson1987,Hsu1990,Christensen2007}. Thus these excitations are well described by linear spin wave theory (LSWT). We also observe a high-energy magnetic continuum in the isotropic magnetic response. This high-energy continuum is not well described by 2 magnon LSWT, or indeed any existing theories.Comment: Revised version to appear in Nature Materials; 6 pages,4 figure

Primeros datos sobre la dinámica del «stock» de merluza europea (Merluccius merluccius L.) frente al litoral gallego

Durante la campaña «Merluza NW 74", realizada en aguas gallegas, se extrajeron los otolitos de 272 merluzas, que hicieron posible conseguir una primera aproximación a la clave talla-edad, y al relacionarlos con las capturas de merluza obtenidas durante la campaña, una estimación de la mortalidad total. Los resultados muestran que el parámetro K de la ecuación de V. Bertalanffy estaría comprendido entre 0,069 y 0,O83, Y L∞ entre 143 y 124 cm. La mortalidad de las clases 1+ a II+ sería 0,94, y de la clase III+ en adelante, de 0,6. La alta cifra de mortalidad entre las clases II+ y JII+, y el sesgo a la izquierda de la talla media de la clase II+, demostrarían una emigración hacia fuera de la costa de la merluza mayor de esta clase de edad y de clases posteriores.During "Merluza NW 74" survey, undertaken off Galicia shores in August 1974, otoliths of 272 hakes were collected, that made possible to obtain a first approach to the length-age key ; and, relating these data with hake catches during the survey, a first estímate of total mortality was obtained. Results show that the K value from V. Bertalanffy equation would be between 0,069 and 0,083, and L∞ between 143 and 124 cm. Total rnortality between age classes I+ and II+ would be 0,94, and for classes III+ and older, 0,6. The high mortality figure between I+ and III+ classes, and the skewness to the left in the mean length of this class, woulcl show an emigration offshore for the bigger hake of this age-class and older.Versión del editor

Human mesenchymal stem cells response to multi-doped silicon-strontium calcium phosphate coatings

The search for apatitic calcium phosphate coatings to improve implants osteointegration is, nowadays, preferentially focused in the obtaining of compositions closer to that of the inorganic phase of bone. Silicon and strontium are both present in trace concentrations in natural bone and have been demonstrated, by separate, to significantly improve osteoblastic response on calcium phosphate bioceramics. This work aims the controlled and simultaneous multidoping of carbonated calcium phosphate coatings with both elements, Si and Sr, by pulsed laser deposition technique and the biological response of human mesenchymal stem cells to them. A complete physicochemical characterization has been also performed to analyze the coatings and significant positive effect was obtained at the osteogenic differentiation of cells, confirming the enormous potential of this multi-doping coating approach.Technical staff of CACTI (University of Vigo) is gratefully acknowledged. This work was partially supported by the UE-POCTEP 0330IBEROMARE1P project, UE-INTERREG 2011-1/164MARMED and Ministerio de Ciencia e Innovacion (Project MAT2010-18281). M Lopez-Alvarez thanks funding support from FP7/REGPOT-2012-2013.1 (no 316265, BIOCAPS)

The Search for Higher TcT_c in Houston

It is a great pleasure to be invited to join the chorus on this auspicious occasion to celebrate Professor K. Alex Mueller's 90th birthday by Professors Annette Bussman-Holder, Hugo Keller, and Antonio Bianconi. As a student in high temperature superconductivity, I am forever grateful to Professor Alex Mueller and Dr. Georg Bednorz "for their important breakthrough in the discovery of superconductivity in the ceramic materials" in 1986 as described in the citation of their 1987 Nobel Prize in Physics. It is this breakthrough discovery that has ushered in the explosion of research activities in high temperature superconductivity (HTS) and has provided immense excitement in HTS science and technology in the ensuing decades till now. Alex has not been resting on his laurels and has continued to search for the origin of the unusual high temperature superconductivity in cuprates.Comment: Dedicated to Alex Mueller, whose "important breakthrough in the discovery of superconductivity in ceramic materials" in 1986 has changed the world of superconductivit