2,558 research outputs found

    Neutron capture cross sections from surrogate reaction data and theory: connecting the pieces with a Markov-Chain Monte Carlo approach

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    The neutron capture cross section for 90Zr(n,γ)^{90}Zr(n, \gamma) has recently been determined using surrogate 92Zr(p,dγ)^{92}Zr(p, d\gamma) data and nuclear reaction theory. That work employed an approximate fitting method based on Bayesian Monte Carlo sampling to determine parameters needed for calculating the 90Zr(n,γ)^{90}Zr(n, \gamma) cross section. Here, we improve the approach by introducing a more sophisticated Markov Chain Monte Carlo sampling method. We present preliminary results.Comment: Accepted into the proceedings of the 6th International Workshop on Compound-Nuclear Reactions and Related Topics, Berkeley, California, September 24-28, 2018. 4 pages, 1 figur

    The agrin gene codes for a family of basal lamina proteins that differ in function and distribution

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    We isolated two cDNAs that encode isoforms of agrin, the basal lamina protein that mediates the motor neuron-induced aggregation of acetylcholine receptors on muscle fibers at the neuromuscular junction. Both proteins are the result of alternative splicing of the product of the agrin gene, but, unlike agrin, they are inactive in standard acetylcholine receptor aggregation assays. They lack one (agrin-related protein 1) or two (agrin-related protein 2) regions in agrin that are required for its activity. Expression studies provide evidence that both proteins are present in the nervous system and muscle and that, in muscle, myofibers and Schwann cells synthesize the agrin-related proteins while the axon terminals of motor neurons are the sole source of agrin

    The Cellular Structure of Selected Apple Varieties

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    Apple cultivars (Sauergrauech, Klarapfel, James Grieve, Granny Smith, Mcintosh, Robinette) which had different textures based on sensory and instrumental analysis (particularly in firmness and mealiness) were examined by conventional scanning electron microscopy (SEM), cold-stage SEM (cryoSEM) and confocal scanning laser microscopy (CSLM) using various preparative procedures. Advantages, lim itations and artifacts of each technique are discussed. SEM with glutaraldehyde-fixation and criticalpoint- drying produced minimal tissue distortion and the fracture pattern and appearance of mealy versus non mealy tissue was different. Freeze-drying unfixed tissue caused cell collapse and firm versus soft varieties could not be differentiated. Freeze-fracturing and cryoSEM of apple ti ssue with varying textures revealed the degree of cell adhesion between frozen hydrated cells. CSLM provided more information on the three-dimensional internal structure of intact fresh apple tissue and cell cohesiveness . Details of structural elements were enhanced by staining with acridine orange
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