3,362 research outputs found

    A prototype of fine granularity lead-scintillating fiber calorimeter with imaging read out

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    The construction and tests performed on a smal prototype of lead-scintillating fiber calorimeter instrumented with multianode photomultipliers are reported. The prototype is 15 cm wide, 15 radiation lenghts deep and is made of 200 layers of 50 cm long fibers. One side of the calorimeter has been instrumented with an array of 3 × 5 multianode R8900-M16 Hamamatsu photomultipliers, each segmented with a matrix of 4 × 4 anodes. The read-out granularity is 240 pixels 11 × 11 mm 2 reading about 64 fibers each. They are interfaced to the 6 × 6 mm 2 pixelled photocade with truncated pyramid light guides made of BC-800 plastic, UV transparent. Moreover each photomultiplier provides also the OR information of the last 12 dynodes. This information can be useful for trigger purposes. The response of the individual anodes, their relative gain and cross-talk has been measured with a 404 nm picosecond laser illuminating only a few fibers on the opposite side of the read-out. We also present first results of the calorimeter response to cosmic rays and electron beam data collected at BTF facility in Frascati

    Tuning Local Hydration Enables a Deeper Understanding of Protein-Ligand Binding: The PP1-Src Kinase Case

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    Water plays a key role in biomolecular recognition and binding. Despite the development of several computational and experimental approaches, it is still challenging to comprehensively characterize water-mediated effects on the binding process. Here, we investigate how water affects the binding of Src kinase to one of its inhibitors, PP1. Src kinase is a target for treating several diseases, including cancer. We use biased molecular dynamics simulations, where the hydration of predetermined regions is tuned at will. This computational technique efficiently accelerates the SRC-PP1 binding simulation and allows us to identify several key and yet unexplored aspects of the solvent's role. This study provides a further perspective on the binding phenomenon, which may advance the current drug design approaches for the development of new kinase inhibitors

    Molecular and clinical conditions associated with venous thromboembolism in oncological patients

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    The association between cancer and thrombophilia has been known since 1865 since Trousseau described it. However in the last three decades an increased interest has been raised on this issue related to several molecular and condition that are involved in the daily management of oncological patients. This brief review has been focused on molecular conditions underlying cancer acquired thrombophilia then to further clinical aspects inducing thrombophilia in oncological patients such as surgery, chemotherapy, concomitant medical illness and inherited thrombophilia.Связь между опухолевым процессом и гематогенной тромбофилией известна с 1865 г., когда Trousseau впервые дал ее описание. В последнее время отмечают возрастающий интерес к этой проблеме и связанным с ней молекулярным и клиническим параметрам, которые учитываются при постоянном наблюдении за больными онкологического профиля. Данный короткий обзор литературы посвящен характеристике молекулярных факторов, лежащих в основе тромбофилии, возникающей в процессе развития новообразований, а также другим особенностям клинического течения, индуцирующим тромбофилию у больных онкологического профиля, таким как хирургическое вмешательство, химиотерапия, сопутствующие осложнения и наследственная тромбофили

    Plakilactones G and H from a marine sponge. Stereochemical determination of highly flexible systems by quantitative NMR-derived interproton distances combined with quantum mechanical calculations of C-13 chemical shifts

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    In this paper the stereostructural investigation of two new oxygenated polyketides, plakilactones G and H, isolated from the marine sponge Plakinastrella mamillaris collected at Fiji Islands, is reported. The stereostructural studies began on plakilactone H by applying an integrated approach of the NOE-based protocol and quantum mechanical calculations of (13)C chemical shifts. In particular, plakilactone H was used as a template to extend the application of NMR-derived interproton distances to a highly flexible molecular system with simultaneous assignment of four non-contiguous stereocenters. Chemical derivatization and quantum mechanical calculations of (13)C on plakilactone G along with a plausible biogenetic interconversion between plakilactone G and plakilactone H allowed us to determine the absolute configuration in this two new oxygenated polyketides

    Influence of Bed Roughness on Flow and Turbulence Structure Around a Partially-Buried, Isolated Freshwater Mussel

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    The present study uses eddy-resolving numerical simulations to investigate how bed roughness affects flow and turbulence structure around an isolated, partially-buried mussel (Unio elongatulus) aligned with the incoming flow. The rough-bed simulations resolve the flow past the exposed part of a gravel bed, whose surface is obtained from a laboratory experiment that also provides some additional data for validation of the numerical model. Results are also discussed for the limiting case of a horizontal smooth bed. Additionally, the effects of varying the level of burial of the mussel inside the substrate and the discharge through the two mussel siphons are investigated via a set of simulations in which the ratio between the median diameter of the (gravel) particles forming the rough bed, d50, and the height of the exposed part of the mussel, h, varies between 0.10 and 0.22. The increase of the bed roughness is associated with a strong amplification of the turbulence kinetic energy in the near-wake region. Increasing the bed roughness and/or reducing h intensifies the interactions of the eddies generated by the bed particles with the base and tip vortices induced by the active filtering and by the mussel shell, respectively, which, in turn, induces a more rapid dissipation of these vortices. Increasing the bed roughness also reduces the strength of the main downwelling flow region forming in the wake. The strong downwelling near the symmetry plane is the main reason why the symmetric wake shedding mode dominates in the smooth bed simulations with negligible active filtering. By contrast, the anti-symmetric wake shedding mode dominates in the simulations conduced with a high value of the bed roughness. The mean streamwise drag force coefficient for the emerged part of the shell and the dilution of the excurrent siphon jet increase with increasing bed roughness

    A global fit to determine the pseudoscalar mixing angle and the gluonium content of the eta' meson

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    We update the values of the eta-eta' mixing angle and of the eta' gluonium content by fitting our measurement R_phi = BR(phi to eta' gamma)/ BR(phi to eta gamma) together with several vector meson radiative decays to pseudoscalars (V to P gamma), pseudoscalar mesons radiative decays to vectors (P to V gamma) and the eta' to gamma gamma, pi^0 to gamma gamma widths. From the fit we extract a gluonium fraction of Z^2_G = 0.12 +- 0.04, the pseudoscalar mixing angle psi_P = (40.4 +- 0.6) degree and the phi-omega mixing angle psi_V = (3.32 +- 0.09) degree. Z^2_G and psi_P are fairly consistent with those previously published. We also evaluate the impact on the eta' gluonium content determination of future experimental improvements of the eta' branching ratios and decay width.Comment: 13 pages, 7 figures to submit to JHE

    Determination of the total width of the eta' meson

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    Taking advantage of both the low-emittance proton-beam of the Cooler Synchrotron COSY and the high momentum precision of the COSY-11 detector system, the mass distribution of the eta' meson was measured with a resolution of 0.33 MeV/c^2 (FWHM), improving the experimental mass resolution by almost an order of magnitude with respect to previous results. Based on the sample of more than 2300 reconstructed pp --> pp eta' events the total width of the eta' meson was determined to be 0.226 +- 0.017(stat.) +- 0.014(syst.) MeV/c^2.Comment: 4 pages, 4 figure

    Measurement of neutron detection efficiency between 22 and 174 MeV using two different kinds of Pb-scintillating fiber sampling calorimeters

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    We exposed a prototype of the lead-scintillating fiber KLOE calorimeter to neutron beam of 21, 46 and 174 MeV at The Svedberg Laboratory, Uppsala, to study its neutron detection efficiency. This has been found larger than what expected considering the scintillator thickness of the prototype. %To check our method, we measured also the neutron %detection efficiency of a 5 cm thick NE110 scintillator. We show preliminary measurement carried out with a different prototype with a larger lead/fiber ratio, which proves the relevance of passive material to neutron detection efficiency in this kind of calorimeters
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