423 research outputs found

    Antiferromagnetic O(N) models in four dimensions

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    We study the antiferromagnetic O(N) model in the F_4 lattice. Monte Carlo simulations are applied for investigating the behavior of the transition for N=2,3. The numerical results show a first order nature but with a large correlation length. The N→∞N \to \infty limit is also considered with analytical methods.Comment: 14 pages, 3 postscript figure

    Surface magnetism in ZnO/Co3O4 mixtures

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    We recently reported the observation of room temperature ferromagnetism in mixtures of ZnO and Co3O4 despite the diamagnetic and antiferromagnetic character of these oxides respectively. Here we present a detailed study on the electronic structure of this material in order to account for this unexpected ferromagnetism. Electrostatic interactions between both oxides lead to a dispersion of Co3O4 particles over the surface of ZnO larger ones. As a consequence, the reduction of Co+3 to Co2+ at the particle surface takes place as evidenced by XAS measurements and optical spectrocopy. This reduction allows to xplain the observed ferromagnetic signal within the well established theories of magnetism.Comment: Accepted in Journal of Applied Physic

    The barley a-thionin promotor is rich in negative regulatory motifs and directs tissue-specific expression of a reporter gene in tobacco.

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    The promoter of the barley α-thionin gene (1.6 kb) fused to the β-glucuronidase (GUS) gene directs temporally-controled, tissue-specific expression in the endosperm of transgenic tobacco. The nucleotide sequence of this promoter shows negative regulatory motifs which have been functionally analyzed in other gene

    Expression of the alpha-thionin gene from barley in tobacco confers enhanced resistance to bacterial pathogens

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    Thionins are cysteine-rich, 5 kDa polypeptides which are toxic to plant pathogens in vitro. Expression of the gene encoding alpha-thionin from barley endosperm, under the 35S promoter from cauliflower mosaic virus, conferred to transgenic tobacco enhanced resistance to the bacterial plant pathogens Pseudomonas syringae pv. tabaci 153 and P. syringae pv. syringae. The barley alpha-thionin gene, which has two introns, was correctly spliced in tobacco. The alpha-thionin in transgenic plants had the expected mobility in the gradient, when separated by high- performance liquid chromatography, reacted with monospecific antibodies and showed the expected antibiotic properties in vitr

    Reliability and reproductibility of skin temperature of overweight subjects by an infrared thermograpy software designed for human beings

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    The technical improvement and new applications of Infrared Thermography (IRT) with healthy subjects should be accompanied by results about the reproducibility of IRT measurements in different popula-tion groups. In addition, there is a remarkable necessity of a larger supply on software to analyze IRT images of human beings. Therefore, the objectives of this study were: firstly, to investigate the reproducibility of skin temperature (Tsk) on overweight and obese subjects using IRT in different Regions of Interest (ROI), moments and side-to-side differences (?T); and secondly, to check the reliability of a new software called Termotracker®, specialized on the analysis of IRT images of human beings. Methods: 22 overweight and obese males (11) and females (11) (age: 41,51±7,76 years; height: 1,65±0,09 m; weight: 82,41±11,81 Kg; BMI: 30,17±2,58 kg/m²) were assessed in two consecutive thermograms (5 seconds in-between) by the same observer, using an infrared camera (FLIR T335, Sweden) to get 4 IRT images from the whole body. 11 ROI were selected using Termotracker® to analyze its reproducibility and reliability through Intra-class Correlation Coefficient (ICC) and Coefficient of Variation (CV) values. Results: The reproducibility of the side-to-side differences (?T) between two consecutive thermograms was very high in all ROIs (Mean ICC = 0,989), and excellent between two computers (Mean ICC = 0,998). The re-liability of the software was very high in all the ROIs (Mean ICC = 0,999). Intraexaminer reliability analysing the same subjects in two consecutive thermograms was also very high (Mean ICC = 0,997). CV values of the different ROIs were around 2%. Conclusions: Skin temperature on overweight subjects had an excellent reproducibility for consecutive ther-mograms. The reproducibility of thermal asymmetries (?T) was also good but it had the influence of several factors that should be further investigated. Termotracker® reached excellent reliability results and it is a relia-ble and objective software to analyse IRT images of humans beings

    Characterization and analysis of thionin genes

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    The general designation of thionins has been proposed for a family of homologous proteins that have been isolated from different tissues in a wide range of plant taxa and have been variously named purothionins, viscotoxins, crambins, etc. (see Garcia-Olmedo et al., 1989). The possible involvement of thionins in plant defense was first suggested, on the basis of their in vitro toxicity to plant pathogens, by Fernandez de Caleya et al., (1972). Those observations had been prompted by earlier reports concerning the antimicrobial properties of these polypeptides (Stuart and Harris, 1942; Balls and Harris, 1944). Work on the thionins, which has been actively pursued over the past half-century, has been recently reviewed in detail (Garcia-Olmedo et al., 1989). For this reason, earlier work will only be partially summarized in the present chapter, which will focus on recent developments concerning thionin genes and their potential role in plant defense mechanisms

    Towards Safer Robot Motion: Using a Qualitative Motion Model to Classify Human-Robot Spatial Interaction

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    For adoption of Autonomous Mobile Robots (AMR) across a breadth of industries, they must navigate around humans in a way which is safe and which humans perceive as safe, but without greatly compromising efficiency. This work aims to classify the Human-Robot Spatial Interaction (HRSI) situation of an interacting human and robot, to be applied in Human-Aware Navigation (HAN) to account for situational context. We develop qualitative probabilistic models of relative human and robot movements in various HRSI situations to classify situations, and explain our plan to develop per-situation probabilistic models of socially legible HRSI to predict human and robot movement. In future work we aim to use these predictions to generate qualitative constraints in the form of metric cost-maps for local robot motion planners, enforcing more efficient and socially legible trajectories which are both physically safe and perceived as safe

    The thionins: a protein family that includes purothionins, viscotoxins and crambins

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    Almost half a century ago, a crystalline protein material was obtained from lipid extracts of wheat endosperm and designated "purothionin" (Trvpwo, wheat; 9 e i w v , sulphur) on account of its high sulphur content (Balls et al., 1942a,b). This material, which was thought to be the oxidized form of a powerful oxidation-reduction system, was found to have baetericidal and fungicidal properties (Stuart and Harris, 1942), to inhibit fermentation of wheat mashes (Balls and Harris, 1944), and to be toxic to laboratory animáis (Coulson et al., 1942)

    Trypsin/α-amylase inhibitors and thionins: possible defence proteins from barley

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    This chapter reviews recent work on the trypsin/α-amylase inhibitor and thionin protein families. The genomic distribution of protein genes in barley and related species, gene expression and in vitro activities are considered. Some of the evidence of a possible defence role against stored products pests for inhibitors and thionins is briefly discusse
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