246 research outputs found

    Laser assisted proton collision on light nuclei at moderate energies

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    We present analytic angular differential cross section model for laser assisted proton nucleon scattering on a Woods-Saxon optical potential where the nth-order photon absorption is taken into account simultaneously. As a physical example we calculate cross sections for proton - 12^{12}C collision at 49 MeV in the laboratory frame where the laser intensity is in the range of 107−1021 10^{7} - 10^{21} W/cm2^2 at optical frequencies. The upper intensity limit is slightly below the relativistic regime.Comment: 6 pages, 4 figures, will be submitted to Phys. Rev.

    Hermetic storage: A novel approach to the protection of cocoa beans

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    Hermetic storage has provided a successful storage method for protection of commodities without fumigants or need for refrigeration for insect control and quality preservation of stored products. Hermetic storage is achieved in specially constructed plastic structures for the preservation of cereal grains and other commodities. Plastic structures suitable for long-term storage systems, as well as intermediate storage of grain have been developed and applied. These storage systems based on the hermetic principle were designed for (1) storage at the farmercooperativeand small trader level with 10 - 1000 tonnes capacity for enclosing stacks termed Cocoonsℱ, (2) small scale storage suitable for small portable containers of 60 kg to 2 tonnes called SuperGrainbagsℱ and (3)quality preservation, insect control and prevention of condensation during shipment of commodities in shipping containers known as  ranSafelinersℱ. Hermetic storage is based on the principle of generation of an oxygendepleted, carbon dioxide-enriched interstitial atmosphere caused by the respiration of the living organisms in the ecological system of a sealed storage. A sufficiently low oxygen and elevated CO2, atmosphere is created through a natural metabolic process based on insect respiration and, in cases where the commodity has sufficiently high moisture, the respiration of the microorganisms within a sealed storage system. Applications for which hermetic technology has been most widely accepted are long-term storage of cereal grains, primarily rice, corn, barley,wheat and a variety of seeds to preserve germination potential and vigor and quality preservation of high-value commodities such as cocoa and coffee. Under field conditions in a cocoa bean storage facility in Makassar,Indonesia, a hermetically sealed flexible structure containing 6.7 tonnes of cocoa beans at an initial moisture content of 7.3% and relative humidity of 70% was monitored for oxygen concentration and quality parameters ofthe beans. The measurements showed a decrease in oxygen concentration to 0.3% after 5.5 days. No insects survived the oxygen depleted biogenerated atmosphere. Similar trials were carried out in Ghana by COCOBOD in which three stacks for hermetic storage and one stack each for conventional storage (without fumigation) and standard storage (with fumigation) were built for sampling and observation. At the sixth week of storage 100% mortality of insects was recorded in the CocoonTM. All the cocoa beans inside the CocoonTM maintained their quality category throughout the storage period and the grade remained the same after nine weeks of storage as it was at the beginning of the experiment

    Translating model simulators to analysis models

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    The final publication is available at Springer via http://dx.doi.org/10.1007/978-3-540-78743-3_6Proceedings of 11th International Conference, FASE 2008, Held as Part of the Joint European Conferences on Theory and Practice of Software, ETAPS 2008, Budapest, Hungary, March 29-April 6, 2008.We present a novel approach for the automatic generation of model-to-model transformations given a description of the operational semantics of the source language by means of graph transformation rules. The approach is geared to the generation of transformations from Domain-Specific Visual Languages (DSVLs) into semantic domains with an explicit notion of transition, like for example Petri nets. The generated transformation is expressed in the form of operational triple graph grammar rules that transform the static information (initial model) and the dynamics (source rules and their execution control structure). We illustrate these techniques with a DSVL in the domain of production systems, for which we generate a transformation into Petri nets.Work sponsored by the Spanish Ministry of Science and Education, project MOSAIC (TSI2005-08225-C07-06

    Cross-reactive memory T cells associate with protection against SARS-CoV-2 infection in COVID-19 contacts

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    Cross-reactive immune responses to SARS-CoV-2 have been observed in pre-pandemic cohorts and proposed to contribute to host protection. Here we assess 52 COVID-19 household contacts to capture immune responses at the earliest timepoints after SARS-CoV-2 exposure. Using a dual cytokine FLISpot assay on peripheral blood mononuclear cells, we enumerate the frequency of T cells specific for spike, nucleocapsid, membrane, envelope and ORF1 SARS-CoV-2 epitopes that cross-react with human endemic coronaviruses. We observe higher frequencies of cross-reactive (p=0.0139), and nucleocapsid-specific (p=0.0355) IL-2-secreting memory T cells in contacts who remained PCR-negative despite exposure (n=26), when compared with those who convert to PCR-positive (n=26); no significant difference in the frequency of responses to spike is observed, hinting at a limited protective function of spike-cross-reactive T cells. Our results are thus consistent with pre-existing non-spike cross-reactive memory T cells protecting SARS-CoV-2-naĂŻve contacts from infection, thereby supporting the inclusion of non-spike antigens in second-generation vaccines

    CD36 maintains the gastric mucosa and associates with gastric disease.

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    The gastric epithelium is often exposed to injurious elements and failure of appropriate healing predisposes to ulcers, hemorrhage, and ultimately cancer. We examined the gastric function of CD36, a protein linked to disease and homeostasis. We used the tamoxifen model of gastric injury in mice null for Cd36 (Cd36-/-), with Cd36 deletion in parietal cells (PC-Cd36-/-) or in endothelial cells (EC-Cd36-/-). CD36 expresses on corpus ECs, on PC basolateral membranes, and in gastrin and ghrelin cells. Stomachs of Cd36-/- mice have altered gland organization and secretion, more fibronectin, and inflammation. Tissue respiration and mitochondrial efficiency are reduced. Phospholipids increased and triglycerides decreased. Mucosal repair after injury is impaired in Cd36-/- and EC-Cd36-/-, not in PC-Cd36-/- mice, and is due to defect of progenitor differentiation to PCs, not of progenitor proliferation or mature PC dysfunction. Relevance to humans is explored in the Vanderbilt BioVu using PrediXcan that links genetically-determined gene expression to clinical phenotypes, which associates low CD36 mRNA with gastritis, gastric ulcer, and gastro-intestinal hemorrhage. A CD36 variant predicted to disrupt an enhancer site associates (p < 10-17) to death from gastro-intestinal hemorrhage in the UK Biobank. The findings support role of CD36 in gastric tissue repair, and its deletion associated with chronic diseases that can predispose to malignancy

    Tomographic Probability Representation for States of Charge moving in Varying Field

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    The coherent and Fock states of a charge moving in varying homogeneous magnetic field are studied in the tomographic probability representation of quantum mechanics. The states are expressed in terms of quantum tomograms. The coherent states tomograms are shown to be described by normal distributions with varying dispersions and means. The Fock state tomograms are given in the form of probability distributions described by multivariable Hermite polynomials with time-dependent arguments.Comment: 12 pages, submitted to "Optics and Spectroscopy
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