Tight-Binding study of the electronic and magnetic properties of an L1_0 ordered FeCu alloy

We have calculated the electronic structure of the tetragonal L1$_0$ ordered FeCu by solving self-consistently a tight-binding Hamiltonian for s, p and d electrons. We have found by total energy calculation that this structure is ferromagnetic. In addition, we have determined that the equilibrium ratio between the interlayer and the intralayer lattice parameters is 0.947.Comment: 7 pages latex, 4 postscript figures included. To appear in Phys. Lett.

Monitoring the spreading of industrial yeast populations in the winery environment

Resumo e poster da comunicação apresentada no "22nd International Specialized Symposium on Yeasts", em 2002, Kwa Maritane, África do Sul.Nowadays, about 50% of the European wine production is based on the use of active dried wine yeast. These strains were selected due to their good fermentation performance and to their capacity to produce a wine with desirable organoleptical characteristics. From an ecological point of view, they are non-indigenous, mostly S. cerevisiae strains that are annually introduced in the ecosystem surrounding the winery. The fate of those yeasts in the natural environment in different geographical localizations is totally unknown. The present study aims to evaluate the industrial starter yeasts’ ability to survive and spread in nature, and become part of the natural microflora of musts. A large-scale sampling plan was elaborated, including 6 different vineyards (3 in Portugal 3 in France), that use the same industrial yeast strain continuously in the last 5 years, being the winery located in close proximity to the vine. In each vineyard, 6 sampling sites were chosen depending on the predominating wind direction and the relative position to the winery. From each site, before and after the harvest, a sufficient amount of grapes was collected to perform small-scale fermentations (0,5 l). Must samples were plated when 30 g/l and 70g/l of CO2 were released, and in both cases, 30 randomly selected colonies were collected. The identification of the industrial yeast strains, Zymaflore VL1 from Laffort Oenologie and a labelled starter yeast, were performed by PCR-amplification of ∂-sequences [1, 2], pulse field electrophoresis and by the use of appropriate antibiotics containing media, respectively. The overall duration of those studies is 3 years, and preliminary results of the first year will be presented

A network of occipito‐temporal face‐sensitive areas besides the right middle fusiform gyrus is necessary for normal face processing

Neuroimaging studies have identified at least two bilateral areas of the visual extrastriate cortex that respond more to pictures of faces than objects in normal human subjects in the middle fusiform gyrus [the ‘fusiform face area' (FFA)] and, more posteriorly, in the inferior occipital cortex [‘occipital face area' (OFA)], with a right hemisphere dominance. However, it is not yet clear how these regions interact which each other and whether they are all necessary for normal face perception. It has been proposed that the right hemisphere FFA acts as an isolated (‘modular') processing system for faces or that this region receives its face‐sensitive inputs from the OFA in a feedforward hierarchical model of face processing. To test these proposals, we report a detailed neuropsychological investigation combined with a neuroimaging study of a patient presenting a deficit restricted to face perception, consecutive to bilateral occipito‐temporal lesions. Due to the asymmetry of the lesions, the left middle fusiform gyrus and the right inferior occipital cortex were damaged but the right middle fusiform gyrus was structurally intact. Using functional MRI, we disclosed a normal activation of the right FFA in response to faces in the patient despite the absence of any feedforward inputs from the right OFA, located in a damaged area of cortex. Together, these findings show that the integrity of the right OFA is necessary for normal face perception and suggest that the face‐sensitive responses observed at this level in normal subjects may arise from feedback connections from the right FFA. In agreement with the current literature on the anatomical basis of prosopagnosia, it is suggested that the FFA and OFA in the right hemisphere and their re‐entrant integration are necessary for normal face processin

Microfluidics-based automated genotyping of Saccharomyces Cerevisiae strain by interdelta sequence typing : an interlaboratory comparasion

High-throughput molecular characterization of microbial isolates requires the application of automated microfluidic electrophoresis. We herein evaluate the factors that affect interlaboratory reproducibility of interdelta sequence typing for Saccharomyces cerevisiae strain delimitation, using microfluidic electrophoresis (Caliper Lab Chip ® ). This approach is necessary for the constitution of bio-databanks, equitable sharing of genotypic data among laboratories, for biodiversity conservation and sustainable development of genetic resources. Delta sequences are 300 bp regions flanking retrotransposons Ty1 and Ty2 of S. cerevisiae, occurring also as separate elements dispersed throughout the genome. PCRbased interdelta sequence typing has a high discriminatory power [1], generating polymorphic banding patterns. Our approach included 12 genetically diverse S. cerevisiae strains, two different Taq polymerases (commercial and in-house cloned/prepared) and two different thermal cyclers. PCR amplifications were performed in two laboratories, resulting in a total of 384 electrophoretic banding patterns (32 replicates for each strain). From the combinations between strains, Taq polymerase, thermal cycler and laboratory, a total of 60 different groups was obtained. Data were analyzed in terms of the fragment sizes (bp), absolute and relative concentrations of each band. Due to the lack of normality (Kolmogorov-Smirnov and Shapiro-Wilk tests) and the homogeneity of variances (Levene's test), the ANOVA test was not applied. The nonparametric alternative, Kruskal-Wallis one-way analysis of variance was used to test the equality of the medians among the different groups. By rejecting the null hypotheses with a p-value < 0.001, we performed multiple pairwise comparisons using the method proposed by Conover and Iman [2], based on a t-Student distribution to search for the origins of the differences. The data obtained revealed that both the performance of experiments in two independent laboratories and the use of different Taq polymerases introduced significant variability between the respective replicates. The use of in-house cloned/prepared Taq polymerase was associated with highest variability, pointing to the need for careful experimental standardization of PCRbased interdelta sequence analysis.Portuguese Science and Technology Foundation (PTDC/AGR-ALI/103392/2008)European Community´s Seventh Framework Programme (FP7/2007-2013) - grant agreement nº 23245

Impacts of composition and beta irradiation on phase separation in multiphase amorphous calcium borosilicates

Borosilicate glasses for nuclear waste applications are limited in waste loading by the precipitation of water-soluble molybdates. In order to increase storage efficiency, new compositions are sought out that trap molybdenum in a water-durable CaMoO4 crystalline phase. Factors affecting CaMoO4 combination and glass-in-glass phase separation in calcium borosilicate systems as a function of changing [MoO3] and [B2O3] are examined in this study in order to understand how competition for charge balancers affects phase separation. It further examines the influence of radiation damage on structural modifications using 0.77 to 1.34 GGy of 2.5 MeV electron radiation that replicates inelastic collisions predicted to occur over long-term storage. The resulting microstructure of separated phases and the defect structure were analyzed using electron microscopy, XRD, Raman and EPR spectroscopy prior to and post irradiation. Synthesized calcium borosilicates are observed to form an unusual heterogeneous microstructure composed of three embedded amorphous phases with a solubility limit ~ 2.5 mol% MoO3. Increasing [B2O3] increased the areas of immiscibility and order of (MoO4)2 − anions, while increasing [MoO3] increased both the phase separation and crystallization temperature resulting in phases closer to metastable equilibrium, and initiated clustered crystallization for [MoO3] > 2.5 mol%. β-irradiation was found to have favorable properties in amorphous systems by creating structural disorder and defect assisted ion migration that thus prevented crystallization. It also increased reticulation in the borosilicate network through 6-membered boroxyl ring and Si ring cleavage to form smaller rings and isolated units. This occurred alongside an increased reduction of Mo6 + with dose that can be correlated to molybdenum solubility. In compositions with existing CaMoO4 crystallites, radiation caused a scattering effect, though the crystal content remained unchanged. Therefore β-irradiation can preferentially prevent crystallization in calcium borosilicates for [MoO3] < 2.5 mol%, but has a smaller impact on systems with existing CaMoO4 crystallites

Genotyping of Saccharomyces cerevisiae strains by interdelta sequence typing using automated microfluidics

Amplification of genomic sequences flanked by delta elements of retrotransposons TY1 and TY2 is a reliable method for characterization of Saccharomyces cerevisiae strains. The aim of this study is to evaluate the usefulness of microfluidic electrophoresis (Caliper LabChip®) to assess the factors that affect interlaboratory reproducibility of interdelta sequence typing for S. cerevisiae strain delimitation. We carried out experiments in two laboratories, using varying combinations of Taq DNA polymerases and thermal cyclers. The reproducibility of the technique is evaluated using non-parametric statistical tests and we show that the source of Taq DNA polymerase and technical differences between laboratories have the highest impact on reproducibility, whereas thermal cyclers have little impact. We also show that the comparative analysis of interdelta patterns is more reliable when fragment sizes are compared, than when absolute and relative DNA concentrations of each band are considered. Interdelta analysis based on a smaller fraction of bands with intermediate sizes between 100 and 1000 bp yield the highest reproducibility.Fundação para a Ciência e Tecnologi

Tests of achromatic phase shifters performed on the SYNAPSE test bench: a progress report

The achromatic phase shifter (APS) is a component of the Bracewell nulling interferometer studied in preparation for future space missions (viz. Darwin/TPF-I) focusing on spectroscopic study of Earth-like exo-planets. Several possible designs of such an optical subsystem exist. Four approaches were selected for further study. Thales Alenia Space developed a dielectric prism APS. A focus crossing APS prototype was developed by the OCA, Nice, France. A field reversal APS prototype was prepared by the MPIA in Heidelberg, Germany. Centre Spatial de Li\`ege develops a concept based on Fresnel's rhombs. This paper presents a progress report on the current work aiming at evaluating these prototypes on the SYNAPSE test bench at the Institut d'Astrophysique Spatiale in Orsay, France

Upper limit to magnetism in LaAlO3/SrTiO3 heterostructures

Using polarized neutron reflectometry (PNR) we measured the neutron spin dependent reflectivity from four LaAlO3/SrTiO3 superlattices. This experiment implies that the upper limit for the magnetization induced by an 11 T magnetic field at 1.7 K is 2 emu/cm3. SQUID magnetometry of the superlattices sporadically finds an enhanced moment, possibly due to experimental artifacts. These observations set important restrictions on theories which imply a strongly enhanced magnetism at the interface between LaAlO3 and SrTiO3