1,305 research outputs found

    Suppression of the thermal hysteresis in magnetocaloric MnAs thin film by highly charged ion bombardment

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    We present the investigation on the modifications of structural and magnetic properties of MnAs thin film epitaxially grown on GaAs induced by slow highly charged ions bombardment under well-controlled conditions. The ion-induced defects facilitate the nucleation of one phase with respect to the other in the first-order magneto-structural MnAs transition with a consequent suppression of thermal hysteresis without any significant perturbation on the other structural and magnetic properties. In particular, the irradiated film keeps the giant magnetocaloric effect at room temperature opening new perspective on magnetic refrigeration technology for everyday use

    Enhancing agroecological innovations with a multi-level approach to experimental research needs

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    Public policies clearly aim at an ecologisation of agriculture. However, few concrete goals or incentives have been established to mobilize the experimental research. Applied to 13-year results of four experimental stations of the South-East of France, the Direct-Indirect-System multi-level analysis grid showed a diversification of their experimental strategies. These three levels of analysis, combined with the identification of different types of agroecosystems, appears as promising for instigating assessment and determining agroecological innovation priorities for an experimental station, a territory or a food chain

    Moving walls accelerate mixing

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    Mixing in viscous fluids is challenging, but chaotic advection in principle allows efficient mixing. In the best possible scenario,the decay rate of the concentration profile of a passive scalar should be exponential in time. In practice, several authors have found that the no-slip boundary condition at the walls of a vessel can slow down mixing considerably, turning an exponential decay into a power law. This slowdown affects the whole mixing region, and not just the vicinity of the wall. The reason is that when the chaotic mixing region extends to the wall, a separatrix connects to it. The approach to the wall along that separatrix is polynomial in time and dominates the long-time decay. However, if the walls are moved or rotated, closed orbits appear, separated from the central mixing region by a hyperbolic fixed point with a homoclinic orbit. The long-time approach to the fixed point is exponential, so an overall exponential decay is recovered, albeit with a thin unmixed region near the wall.Comment: 17 pages, 13 figures. PDFLaTeX with RevTeX 4-1 styl

    A neutron diffraction study of the oxygen diffusion in molybdenum doped Ba2InO5

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    International audienceThe structures of molybdenum doped Ba2In2O5 were refined using X-ray and neutron diffraction data at room and high temperature with the aim to derive preferred oxygen diffusion pathways. At room temperature, refinement of composition Ba2In2-xMoxO5+3x/2 with x=0.1 revealed molybdenum atoms are preferentially located in the tetrahedral layers of the brownmillerite. At 700°C, the structure can be viewed as the stacking of alternating In and In/Mo octahedral layers. The conduction process occurs preferentially in the later which is highly oxygen deficient. Preferred oxygen diffusion pathways were deduced from Joint Probability Density Function (JPDF) and energy barriers were derived. It was in good agreement with the activation energy deduced from impedance spectroscopy for composition x=0.1 at 950°C. However, calculation of energy barrier assumes a dynamic disorder of oxide ions which is unlikely to occur at lower temperature and for sample containing a larger amount of molybdenum. Composition x=0.5 is cubic on the whole range of temperature. At room temperature, JPDF revealed a static disorder of the oxygen atoms, which is likely due to the solution of molybdenum into the barium indium perovskite. When temperature increases the disorder becomes more and more dynamic

    At the nexus of three kingdoms: the genome of the mycorrhizal fungus Gigaspora margarita provides insights into plant, endobacterial and fungal interactions.

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    As members of the plant microbiota, arbuscular mycorrhizal fungi (AMF, Glomeromycotina) symbiotically colonize plant roots. AMF also possess their own microbiota, hosting some uncultivable endobacteria. Ongoing research has revealed the genetics underlying plant responses to colonization by AMF, but the fungal side of the relationship remains in the dark. Here, we sequenced the genome of Gigaspora margarita, a member of the Gigasporaceae in an early diverging group of the Glomeromycotina. In contrast to other AMF, G. margarita may host distinct endobacterial populations and possesses the largest fungal genome so far annotated (773.104 Mbp), with more than 64% transposable elements. Other unique traits of the G. margarita genome include the expansion of genes for inorganic phosphate metabolism, the presence of genes for production of secondary metabolites and a considerable number of potential horizontal gene transfer events. The sequencing of G. margarita genome reveals the importance of its immune system, shedding light on the evolutionary pathways that allowed early diverging fungi to interact with both plants and bacteria

    Fungal ecological strategies reflected in gene transcription - a case study of two litter decomposers.

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    Microbial communities interplay with their environment through their functional traits that can be a response or an effect on the environment. Here, we explore how a functional trait-the decomposition of organic matter, can be addressed based on genetic markers and how the expression of these markers reflect ecological strategies of two fungal litter decomposer Gymnopus androsaceus and Chalara longipes. We sequenced the genomes of these two fungi, as well as their transcriptomes at different steps of Pinus sylvestris needles decomposition in microcosms. Our results highlighted that if the gene content of the two species could indicate similar potential decomposition abilities, the expression levels of specific gene families belonging to the glycoside hydrolase category reflected contrasting ecological strategies. Actually, C. longipes, the weaker decomposer in this experiment, turned out to have a high content of genes involved in cell wall polysaccharides decomposition but low expression levels, reflecting a versatile ecology compare to the more competitive G. androsaceus with high expression levels of keystone functional genes. Thus, we established that sequential expression of genes coding for different components of the decomposer machinery indicated adaptation to chemical changes in the substrate as decomposition progressed

    Plan de negocios para determinar la viabilidad de un negocio de producci?n y comercializaci?n de un dispositivo para prevenir las lesiones de los deportistas

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    El dispositivo en forma de parche para prevenir las lesiones de los futbolistas, los bailarines, y la gente que va al gimnasio denominado SmartPatch, se encuentra desarrollado para las personas modernas que viven en Lima. Este producto se relaciona con un aplicativo que permite almacenar la informaci?n recolectada durante el esfuerzo f?sico y que permite analizar los resultados. El aplicativo brindar? un servicio de consejos para los deportistas con el fin de mejorar sus h?bitos deportivos y su dieta. El principal beneficio es aliviar la ansiedad en cuanto a la ocurrencia de lesiones y mejorar los entrenamientos. Este producto se encontrar? en una p?gina web, en tiendas detallistas o en establecimientos deportivos de socios de negocio. SmartPatch plantear cambiar el mundo de los wearables poniendo tecnolog?a m?s espec?fica, sencilla y peque?a al servicio de la prevenci?n de lesiones de los deportistas. Por lo tanto, SmartPatch brinda una evaluaci?n de la sangre en tiempo real de tres elementos. En primer lugar, la hidrataci?n A trav?s de la medici?n de la cantidad de ox?geno. En segundo lugar, el ?cido l?ctico que se va produciendo a lo largo de la actividad f?sica. Por ?ltimo, un conjunto de seis nutrientes, a saber, el potasio, el sodio, el calcio, el hierro, el cobre, y el magnesio, que son mol?culas que no pueden ser producidas por el metabolismo humano

    Experimental Evidence of Fluctuation-Dissipation Theorem Violation in a Superspin Glass

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    We present the experimental observation of the fluctuation-dissipation theorem (FDT) violation in an assembly of interacting magnetic nanoparticles in the low temperature superspin glass phase. The magnetic noise is measured with a two-dimension electron gas Hall probe and compared to the out of phase ac susceptibility of the same ferrofluid. For "intermediate" aging times of the order of 1 h, the ratio of the effective temperature TeffT_{\rm eff} to the bath temperature T grows from 1 to 6.5 when T is lowered from TgT_g to 0.3 TgT_g, regardless of the noise frequency. These values are comparable to those measured in an atomic spin glass as well as those calculated for a Heisenberg spin glass

    Contourite porosity, grain size and reservoir characteristics

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    Acknowledgements Many people are to thank for the collection and release of the data used in this study. In particular, we thank the captain, officers and crew, and the scientific and technical shipboard parties of the different IODP expeditions utilised. We each thank our respective institutes for their ongoing support. Xiaohang Yu acknowledges financial support from the National Natural Science Foundation of China (No. 41976067).Peer reviewedPostprin
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