806 research outputs found
Unexpected Magnetism of Small Silver Clusters
The ground-state electronic, structural, and magnetic properties of small
silver clusters, Ag (2n22), 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 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
Mesh selection of hake, blue whiting, horse-mackerel,megrim, sole and Nephrops in nylon codends on Galicia and Portugal shelf
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 LaCuO 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 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
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