2,470 research outputs found

    A Full-Scale Evaluation of Lightweight Personal Protective Ensembles for Demining in Providing Protection Against Blast-Type Anti-Personnel Mines

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    A wide range of equipment, in the form of helmets, vests, aprons and trousers, is currently in use around the world to protect deminers against the effects of AP mines. Significant variations exist in terms of the level of protection afforded, operational usefulness, quality of manufacturing and cost of each of these components. To date, there have been limited studies undertaken to systematically and quantitatively assess the effectiveness of the different protective components applied to both the civilian and military demining theaters. This study summarizes the efforts of numerous full-scale test series carried out in 1999, with particular emphasis on quantifying the protective performance against blast AP mines of selected concepts of humanitarian demining ensembles. It was also possible to assess aspects of the blast and related fragmentation resistance of individual components

    Resonance Raman Characterization of the Peroxo and Hydroperoxo Intermediates in Cytochrome P450

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    Resonance Raman (RR) studies of intermediates generated by cryoreduction of the oxyferrous complex of the D251N mutant of cytochrome P450cam (CYP101) are reported. Owing to the fact that proton delivery to the active site is hindered in this mutant, the unprotonated peroxo-ferric intermediate is observed as the primary species after radiolytic reduction of the oxy-complex in frozen solutions at 77 K. In as much as previous EPR and ENDOR studies have shown that annealing of this species to ∼180 K results in protonation of the distal oxygen atom to form the hydroperoxo intermediate, this system has been exploited to permit direct RR interrogation of the changes in the Fe−O and O−O bonds caused by the reduction and subsequent protonation. Our results show that the ν(O−O) mode decreases from a superoxo-like frequency near ∼1130 cm−1 to 792 cm−1 upon reduction. The latter frequency, as well as its lack of sensitivity to H/D exchange, is consistent with heme-bound peroxide formulation. This species also exhibits a ν(Fe−O) mode, the 553 cm−1 frequency of which is higher than that observed for the nonreduced oxy P450 precursor (537 cm−1), implying a strengthened Fe−O linkage upon reduction. Upon subsequent protonation, the resulting Fe−O−OH fragment exhibits a lowered ν(O−O) mode at 774 cm−1, whereas the ν(Fe−O) increases to 564 cm−1. Both modes exhibit a downshift upon H/D exchange, as expected for a hydroperoxo-ferric formulation. These experimental RR data are compared with those previously acquired for the wild-type protein, and the shifts observed upon reduction and subsequent protonation are discussed with reference to theoretical predictions

    The Effectiveness of Different Personal Protective Ensembles in Preventing Injury to the Thorax from Blast-Type Anti-Personnel Mines

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    It is well established from numerous documented cases of bomb blasts that, under certain conditions (determined by the amount and proximity of explosive), the transmitted shock wave and associated overpressure generated by the detonation of an explosive device can cause critical and fatal injuries to the thorax, e.g., “blast lung.” As such injuries tend to be internal and thus difficult to detect, there has been considerable debate in recent years on the significance of the blast overpressure injury in the context of demining/mine clearance compared to more visible injuries, such as, amputation of extremities, fragmentation wounds and blindness. A wide range of personal protective ensembles are currently deployed in the field, incorporating disparate stackings of materials over the thoracic region

    Joint thrust and TMD resummation in electron-positron and electron-proton collisions

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    We present the framework for obtaining precise predictions for the transverse momentum of hadrons with respect to the thrust axis in e+ee^+e^- collisions. This will enable a precise extraction of transverse momentum dependent (TMD) fragmentation functions from a recent measurement by the Belle Collaboration. Our analysis takes into account, for the first time, the nontrivial interplay between the hadron transverse momentum and the cut on the thrust event shape. To this end, we identify three different kinematic regions, derive the corresponding factorization theorems within Soft Collinear Effective Theory, and present all ingredients needed for the joint resummation of the transverse momentum and thrust spectrum at NNLL accuracy. One kinematic region can give rise to non-global logarithms (NGLs), and we describe how to include the leading NGLs. We also discuss alternative measurements in e+ee^+e^- collisions that can be used to access the TMD fragmentation function. Finally, by using crossing symmetry, we obtain a new way to constrain TMD parton distributions, by measuring the displacement of the thrust axis in epep collisions.Comment: 25 pages, 5 figure

    PPE: Effective Protection for Deminers

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    This article briefly explains the work that Med-Eng Systems, Inc., has done on personal protective equipment (PPE) over the past few years
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