Magnetic nanoparticles as efficient bulk pinning centers in type-II superconductors

Enhancement of flux pinning by magnetic nanoparticles embedded into the bulk of type-2 superconductor is studied both theoretically and experimentally. Magnetic part of the pinning force associated with the interaction between a spherical magnetic inclusion and an Abrikosov vortex was calculated in the London approximation. Calculations are supported by the experimental results obtained on sonochemically modified MgB2 superconductor with embedded magnetic Fe2O3 nanoparticles and compared to MgB2 with nonmagnetic Mo2O5 pinning centers of similar concentration and particle size distribution. It is shown that ferromagnetic nanoparticles result in a considerable enhancement of vortex pinning in large-kappa type-2 superconductors.Comment: PDF, 14 page

Economic evaluation of three systems of alimentation used in finishing lambs

Eighteen castrated male lambs of the Texel breed were randomly diestribut3ed among the following treatments: T1 = confinement; T2 = pasture with supplementation; T3 = pasture without supplementation. At 144 days of age the lambs were slaughtered after a 12hr fast. Live weight at slaughter and warm carcass weight were lower (P≤0.05) for T3 lambs compared with those confined or supplemented at pasture, which resulted in lower gross income. Profitability in relation to liveweight was higher (P≤0.05) for the lambs on pasture without supplementation relative to T1, whereas the profitability in relation to carcass weight numerically was higher for both T1 and T2 than for T3. The availability of herbage dry matter at the end of the experiment was 326% higher for the supplementation treatment than without supplementation (T2 vs. T3). (Portuguese

Superfluid fraction in an interacting spatially modulated Bose-Einstein condensate

At zero temperature, a Galilean-invariant Bose fluid is expected to be fully superfluid. Here we investigate theoretically and experimentally the quenching of the superfluid density of a dilute Bose-Einstein condensate due to the breaking of translational (and thus Galilean) invariance by an external 1D periodic potential. Both Leggett's bound fixed by the knowledge of the total density and the anisotropy of the sound velocity provide a consistent determination of the superfluid fraction. The use of a large-period lattice emphasizes the important role of two-body interactions on superfluidity

Distribution des larves de sardine et d'anchois le long du filament du Cap Ghir (région nord-ouest africaine)

L'une des caractéristiques des systèmes d'upwellings côtiers est la présence la présence de structures méso-échelles que la littérature appelle des "filaments d'upwelling", des extensions vers le large de masses d'eaux issues de l'upwelling. Ces filaments impactent la structure des communautés planctoniques, dont les larves de petits poissons pélagiques, considérées comme traceurs biologiques des filaments d’upwelling. Sur la côte Atlantique marocaine, le plus important de ces filaments est celui du Cap Ghir. Le présent travail présente une étude des caractéristiques hydrologiques et du plancton entreprise dans la région du Cap Ghir (31°N) à travers cinq campagnes océanographiques réalisées durant la période 2008-2009. L'analyse des mesures de température, salinité et de concentration de chlorophylle a montre une variabilité spatio-temporelle de la direction de la dérive des eaux d'upwelling vers le large, qui amène ces eaux alternativement au nord ou au sud du 31ème parallèle nord. Cette variabilité observée in situ, est confirmée par l'analyse des images satellites relatives aussi bien à la SST qu'à la couleur d'eau de mer. Sur le plan biologique, l'impact des filaments d'upwelling est étudié à travers la distribution des larves de sardines et d'anchois collectées dans la zone du Cap Ghir. Ainsi, la répartition des tailles moyennes pondérées de ces larves montre un transport vers le large selon un schéma de circulation vers le nord et le sud de la zone côtière d'upwelling

Peri-urban Farn ing Systems and Food Processing in the Congo

Abstract AGRICONGO (Institut de recherche et d'appui pour le développement agricole en Zones tropicales) developed a project entitled new farming systems (NSF). This project is intended to implement peri-urban agriculture for city dwellers who want to go into small farm businesses. Because the Congo is importing a large part of its food, the project's first goal was to identify products for development. A basic project assumption was that the best way to reduce these imports was to modernize traditional foods. There was also a need to develop appropriate technologies in agronomy and food science. Work was done to design both a 1.5 ha NFS farm and an integrated food processing facility. Farming techniques were tested at the research station level and the study included socioeconomic issues and farmer-level implementation of product marketing and commercialization. This report presents preliminary findings from 20 pilot NFS farms that were tested near Brazzaville. Food processing lines and their management are also described. Processed products made available to urban markets through the project were chikwangue (cassava bread) and cassava-based mixed flour for infant food

Insight from PREFACE & AWA on Tropical Atlantic Tuna ecology and effects on western African fisheries economies

International audienc

Quantum character varieties and braided module categories

We compute quantum character varieties of arbitrary closed surfaces with boundaries and marked points. These are categorical invariants $\int_S\mathcal A$ of a surface $S$, determined by the choice of a braided tensor category $\mathcal A$, and computed via factorization homology. We identify the algebraic data governing marked points and boundary components with the notion of a {\em braided module category} for $\mathcal A$, and we describe braided module categories with a generator in terms of certain explicit algebra homomorphisms called {\em quantum moment maps}. We then show that the quantum character variety of a decorated surface is obtained from that of the corresponding punctured surface as a quantum Hamiltonian reduction. Characters of braided $\mathcal A$-modules are objects of the torus category $\int_{T^2}\mathcal A$. We initiate a theory of character sheaves for quantum groups by identifying the torus integral of $\mathcal A=\operatorname{Rep_q} G$ with the category $\mathcal D_q(G/G)-\operatorname{mod}$ of equivariant quantum $\mathcal D$-modules. When $G=GL_n$, we relate the mirabolic version of this category to the representations of the spherical double affine Hecke algebra (DAHA) $\mathbb{SH}_{q,t}$.Comment: 33 pages, 5 figures. Final version, to appear in Sel. Math. New Se