224 research outputs found

    Magnetic dephasing in mesoscopic spin glasses

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    We have measured Universal Conductance Fluctuations in the metallic spin glass Ag:Mn as a function of temperature and magnetic field. From this measurement, we can access the phase coherence time of the electrons in the spin glass. We show that this phase coherence time increases with both the inverse of the temperature and the magnetic field. From this we deduce that decoherence mechanisms are still active even deep in the spin glass phase

    Topological surface states of strained Mercury-Telluride probed by ARPES

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    The topological surface states of strained HgTe have been measured using high-resolution ARPES measurements. The dispersion of surface states form a Dirac cone, which origin is close to the top of the \ghh band: the top half of the Dirac cone is inside the stress-gap while the bottom half lies within the heavy hole bands and keeps a linear dispersion all the way to the X-point. The circular dichroism of the photo-emitted electron intensity has also been measured for all the bands.Comment: with supplementary materia

    Cross-Over between universality classes in a magnetically disordered metallic wire

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    In this article we present numerical results of conduction in a disordered quasi-1D wire in the possible presence of magnetic impurities. Our analysis leads us to the study of universal properties in different conduction regimes such as the localized and metallic ones. In particular, we analyse the cross-over between universality classes occurring when the strength of magnetic disorder is increased. For this purpose, we use a numerical Landauer approach, and derive the scattering matrix of the wire from electron's Green's function.Comment: Final version, accepted for publication in New Journ. of Physics, 27 pages, 28 figures. Replaces the earlier shorter preprint arXiv:0910.427

    Animal welfare, a driving force to change pig production systems?

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    Animal welfare requirements are expected to affect the future development of pig production systems in France. Rules and regulations play a major role in this evolution. This could be in favour of larger farms, better able to sustain their economic burden. The development of alternative production systems should also be in favour of improved animal welfare. However, French consumer demand for this type of production remains very low due to higher prices. On the other hand, simultaneous improvement of animal performance and welfare provides an interesting approach, as the price increase due to the welfare-related cost may be at least partly offset by enhanced animal performance.La prise en compte du bien-être animal devrait jouer un rôle important dans l'évolution des systèmes de production porcine en France. La réglementation y contribue de manière prépondérante. Elle pourrait favoriser le développement de structures de plus grande taille, mieux armées pour faire face à ses conséquences économiques. Les élevages labellisés incluent dans leurs cahiers des charges le respect du bien-être des animaux. De ce fait leur développement contribue à celui du respect du bien-être animal. Cependant, la demande des consommateurs pour ce type de productions reste jusqu'à présent très limitée en raison de leurs prix plus élevés. L'amélioration conjointe du bien-être et des performances constitue une approche intéressante, dans la mesure où l'augmentation des coûts liés au bien-être peut être, tout au moins en partie, compensée par l'accroissement des performances zootechniques

    Remanence effects in the electrical resistivity of spin glasses

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    We have measured the low temperature electrical resistivity of Ag : Mn mesoscopic spin glasses prepared by ion implantation with a concentration of 700 ppm. As expected, we observe a clear maximum in the resistivity (T ) at a temperature in good agreement with theoretical predictions. Moreover, we observe remanence effects at very weak magnetic fields for the resistivity below the freezing temperature Tsg: upon Field Cooling (fc), we observe clear deviations of (T ) as compared with the Zero Field Cooling (zfc); such deviations appear even for very small magnetic fields, typically in the Gauss range. This onset of remanence for very weak magnetic fields is reminiscent of the typical signature on magnetic susceptibility measurements of the spin glass transition for this generic glassy system

    Prisutnost Candida sp. u svježem voćnom soku

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    Fruit juices are popular soft drinks with an important role in human nutrition. Fruit juices are often infested by yeast species that can survive different storage conditions. The aim of this study was to determine the degree of yeast contamination of freshly squeezed juices in three large supermarkets in Zagreb, Croatia. The analysis included 84 juice samples obtained from freshly squeezed orange, lemon, grapefruit, and apples. Their acidity varied between pH 2.1 and pH 4.9. Juice samples were plated directly on Sabouraud 4 % glucose Agar (Merck, 1.05438) and processed according to standardised methods (HRN ISO 7954:2002). Yeasts were isolated in all 84 samples and ranged between 0.005x103 and 23x103 colony forming units per mL (CFU mL-1). The most common yeasts identifi ed using the API 20C AUX yeast kit included Candida guillermondii, C. krusei, C. famata, C. spherica, C. colliculosa, C. albicans, Trichosporon mucoides, Kloeckera spp. and yeast-like fungus Cryptococcus neoformans. C. guillermondii prevailed in 55.95 % of all samples.Voćni su sokovi tekući ekstrakti voća dobiveni cijeđenjem zrelog voća te su vrlo važan čimbenik u svakodnevnoj prehrani ljudi. Najčešće zastupljeni mikroorganizmi u svježem voćnom soku su kvasci koji preživljavaju niske temperature skladištenja. Svrha ovog istraživanja bila je odrediti prisutnost i brojnost kvasaca u svježim voćnim sokovima uzorkovanim u supermarketima na području Republike Hrvatske, odnosno glavnom gradu Zagrebu. Ukupno su uzorkovana i pregledana 84 uzorka svježe iscijeđenih naranči, limuna, grejpfruta i jabuka. pH-vrijednost se kretala od 2.1 do 4.9. Uzorci su nacijepljivani direktno na Sabouraudov agar s 4 % glukoze (Merck, Njemačka) u skladu s propisanom normom HRN ISO 7954:2002. U sva 84 uzorka utvrđena je prisutnost kvasaca u broju od 0.005x103 do 23x103 CFU mL-1. Identifi kacija je provedena testom API 20 C AUX (bioMérieux, 20 210). Najčešće su izolirani sljedeći kvasci: Candida guillermondii, C. krusei, C. famata, C. spherica, C. colliculosa, C. albicans, Trichosporon mucoides, Kloeckera spp. i kvascu slična gljivica Cryptococcus neoformans. U svim uzorcima C. guillermondii bila je najčešće izolirani kvasac (55.95 %)

    Keratinocyte Secretion of Cyclophilin B via the Constitutive Pathway Is Regulated through Its Cyclosporin-Binding Site

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    Cyclophilin B (CypB) is an endoplasmic reticulum (ER)-resident member of the cyclophilin family of proteins that bind cyclosporin A (CsA). We report that as in other cell types, CypB trafficked from the ER and was secreted by keratinocytes into the media in response to CsA. Concentrations as low as 1 p of CsA induced secretion of CypB. Using brefeldin A, we showed that CypB is secreted from keratinocytes via the constitutive secretory pathway. We defined that substitution of tryptophan residue 128 in the CsA-binding site of CypB with alanine resulted in dissociation of CypBW128A-green fluorescent protein (GFP) from the ER. Photobleaching studies revealed a significant reduction in the diffusible mobility of CypBW128A-GFP compared with CypBWT-GFP, consistent with redistribution of CypBW128A-GFP into secretory vesicles disconnected from the ER/Golgi network. Furthermore, CsA significantly decreased the mobility of CypBWT-GFP but not CypBW128A-GFP. These studies demonstrate that therapeutically relevant concentrations of CsA regulate secretion of CypB by keratinocytes, and that a key residue within the CsA-binding site of CypB controls retention of CypB within the ER and regulates entry into the secretory pathway. As keratinocytes express CypB receptors (CD147) and CypB exhibits chemotactic properties, these data have implications for the therapeutic effects of CsA in inflammatory skin disease

    c-Met overexpression in inflammatory breast carcinomas: automated quantification on tissue microarrays

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    Inflammatory breast carcinoma (IBC) is a rare but aggressive tumour associated with poor outcome owing to early metastases. Increased expression of c-Met protein correlates with reduced survival and high metastatic risk in human cancers including breast carcinomas and is targetable by specific drugs, that could potentially improve the prognosis. In the present study, we compared c-Met expression in IBC (n=41) and non-IBC (n=480) immunohistochemically (Ventana Benchmark autostainer) in two tissue microarrays (TMA) along with PI3K and E-cadherin. The results were quantified through an automated image analysis device (SAMBA Technologies). We observed that (i) c-Met was significantly overexpressed in IBC as compared with non-IBC (P<0.001), (ii) PI3K was overexpressed (P<0.001) in IBC, suggesting that the overexpressed c-Met is functionally active at least through the PI3K signal transduction pathway; and (iii) E-cadherin was paradoxically also overexpressed in IBC. We concluded that overexpressed c-Met in IBC constitutes a potential target for specific therapy for the management of patients with poor-outcome tumours such as IBC. Automated image analysis of TMA proved to be a valuable tool for high-throughput immunohistochemical quantification of the expression of intratumorous protein markers
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