3,910 research outputs found

    Method of tracing contour patterns for use in making gradual contour resin matrix composites

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    The invention relates to methods for making alminate patterns for a resin matrix composite structural component. A sheet of paper is temporarily adhered to a model of the structrual component. A pen is positioned on the paper with a spindle touching the model surface opposite the pen. The pen and spindle are moved along the path that maintains the aforementioned contacts. The resulting line traced on paper is a model constant-thickness locus and provides a pattern for a single lamination of resin-impregnated fabric. The steps are repeated to make other patterns and each time the steps are repeated the distance between the tracer and the spindle is changed to correspond to the thickness of a lamination

    Molding procedure for casting a variety of alloys

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    General procedure and molding sand composition for preparing molds usable for casting variety of alloys are developed. Molds are prepared from mixture of sand, sodium silicate binder, and organic liquid ester. Castings of radiographic quality are produced from various alloys

    h→Zγh \rightarrow Z \gamma in the complex two Higgs doublet model

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    The latest LHC data confirmed the existence of a Higgs-like particle and made interesting measurements on its decays into γγ\gamma \gamma, ZZ∗Z Z^\ast, WW∗W W^\ast, τ+τ−\tau^+ \tau^-, and bbˉb \bar{b}. It is expected that a decay into ZγZ \gamma might be measured at the next LHC round, for which there already exists an upper bound. The Higgs-like particle could be a mixture of scalar with a relatively large component of pseudoscalar. We compute the decay of such a mixed state into ZγZ \gamma, and we study its properties in the context of the complex two Higgs doublet model, analysing the effect of the current measurements on the four versions of this model. We show that a measurement of the h→Zγh \rightarrow Z \gamma rate at a level consistent with the SM can be used to place interesting constraints on the pseudoscalar component. We also comment on the issue of a wrong sign Yukawa coupling for the bottom in Type II models.Comment: 31 pages, 15 figure

    A reappraisal of the wrong-sign hbb‾hb\overline{b} coupling and the study of h→Zγh \rightarrow Z \gamma

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    It has been pointed out recently that current experiments still allow for a two Higgs doublet model where the hbbˉh b \bar{b} coupling (kDmb/vk_D m_b/v) is negative; a sign opposite to that of the Standard Model. Due to the importance of delayed decoupling in the hH+H−h H^+ H^- coupling, h→γγh \rightarrow \gamma \gamma improved measurements will have a strong impact on this issue. For the same reason, measurements or even bounds on h→Zγh \rightarrow Z \gamma are potentially interesting. In this article, we revisit this problem, highlighting the crucial importance of h→VVh \rightarrow VV, which can be understood with simple arguments. We show that the impacts on kD<0k_D<0 models of both h→bbˉh \rightarrow b \bar{b} and h→τ+τ−h \rightarrow \tau^+ \tau^- are very sensitive to input values for the gluon fusion production mechanism; in contrast, h→γγh \rightarrow \gamma \gamma and h→Zγh \rightarrow Z \gamma are not. We also inquire if the search for h→Zγh \rightarrow Z \gamma and its interplay with h→γγh \rightarrow \gamma \gamma will impact the sign of the hbbˉh b \bar{b} coupling. Finally, we study these issues in the context of the Flipped two Higgs doublet model.Comment: 13 pages, pdf figure

    The K-process on a tree as a scaling limit of the GREM-like trap model

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    We introduce trap models on a finite volume kk-level tree as a class of Markov jump processes with state space the leaves of that tree. They serve to describe the GREM-like trap model of Sasaki and Nemoto. Under suitable conditions on the parameters of the trap model, we establish its infinite volume limit, given by what we call a KK-process in an infinite kk-level tree. From this we deduce that the KK-process also is the scaling limit of the GREM-like trap model on extreme time scales under a fine tuning assumption on the volumes.Comment: Published in at http://dx.doi.org/10.1214/13-AAP937 the Annals of Applied Probability (http://www.imstat.org/aap/) by the Institute of Mathematical Statistics (http://www.imstat.org

    Non-Equilibrium Modeling of the Fe XVII 3C/3D ratio for an Intense X-ray Free Electron Laser

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    We present a review of two methods used to model recent LCLS experimental results for the 3C/3D line intensity ratio of Fe XVII (Bernitt et al. 2012), the time-dependent collisional-radiative method and the density-matrix approach. These are described and applied to a two-level atomic system excited by an X-ray free electron laser. A range of pulse parameters is explored and the effects on the predicted Fe XVII 3C and 3D line intensity ratio are calculated. In order to investigate the behavior of the predicted line intensity ratio, a particular pair of A-values for the 3C and 3D transitions was chosen (2.22 ×\times 1013^{13} s−1^{-1} and 6.02 ×\times 1012^{12} s−1^{-1} for the 3C and 3D, respectively), but our conclusions are independent of the precise values. We also reaffirm the conclusions from Oreshkina et al.(2014, 2015): the non-linear effects in the density matrix are important and the reduction in the Fe XVII 3C/3D line intensity ratio is sensitive to the laser pulse parameters, namely pulse duration, pulse intensity, and laser bandwidth. It is also shown that for both models the lowering of the 3C/3D line intensity ratio below the expected time-independent oscillator strength ratio has a significant contribution due to the emission from the plasma after the laser pulse has left the plasma volume. Laser intensities above ∼1×1012\sim 1\times 10^{12} W/cm2^{2} are required for a reduction in the 3C/3D line intensity ratio below the expected time independent oscillator strength ratio

    A line-binned treatment of opacities for the spectra and light curves from neutron star mergers

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    The electromagnetic observations of GW170817 were able to dramatically increase our understanding of neutron star mergers beyond what we learned from gravitational waves alone. These observations provided insight on all aspects of the merger from the nature of the gamma-ray burst to the characteristics of the ejected material. The ejecta of neutron star mergers are expected to produce such electromagnetic transients, called kilonovae or macronovae. Characteristics of the ejecta include large velocity gradients, relative to supernovae, and the presence of heavy rr-process elements, which pose significant challenges to the accurate calculation of radiative opacities and radiation transport. For example, these opacities include a dense forest of bound-bound features arising from near-neutral lanthanide and actinide elements. Here we investigate the use of fine-structure, line-binned opacities that preserve the integral of the opacity over frequency. Advantages of this area-preserving approach over the traditional expansion-opacity formalism include the ability to pre-calculate opacity tables that are independent of the type of hydrodynamic expansion and that eliminate the computational expense of calculating opacities within radiation-transport simulations. Tabular opacities are generated for all 14 lanthanides as well as a representative actinide element, uranium. We demonstrate that spectral simulations produced with the line-binned opacities agree well with results produced with the more accurate continuous Monte Carlo Sobolev approach, as well as with the commonly used expansion-opacity formalism. Additional investigations illustrate the convergence of opacity with respect to the number of included lines, and elucidate sensitivities to different atomic physics approximations, such as fully and semi-relativistic approaches.Comment: 27 pages, 22 figures. arXiv admin note: text overlap with arXiv:1702.0299

    The current status of hepatic transplantation at the University of Pittsburgh.

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    Tacrolimus is a more potent and satisfactory immunosuppressant than CyA for combination therapy with prednisone. In randomized trials comparing the 2 drugs, the ability of tacrolimus to rescue intractably rejecting grafts on the competing CyA arm allowed equalization of patient and graft survival on both arms when the intent-to-treat analytic methodology was applied. The ability of tacrolimus to systematically rescue the treatment failures of CyA suggested, as a matter of common sense, that it is the preferred baseline drug for hepatic transplantation. This conclusion was supported by analysis of secondary end points, including the ability to prevent rejection. Hepatic-intestinal, multivisceral and isolated intestinal transplantation became feasible on a practical basis only after the advent of tacrolimus. Nevertheless, better management strategies must be devised before intestinal transplantation, alone or with other abdominal viscera, will meet its potential. One such strategy is based on the discovery of the presence of previously unsuspected, low-level donor leukocyte chimerism in long-surviving allograft recipients. We believe that this chimerism is the essential explanation for the feasibility of organ transplantation and a link to the acquired neonatal tolerance demonstrated by Billingham, Brent and Medawar (32). The hematolymphopoietic chimerism in organ recipients explains why weaning to a drug-free state in selected long-term survivors is frequently feasible and particularly if the allograft is a liver. Weaning should never be attempted without a stepwise protocol and careful monitoring of graft function. Recognition of the natural chimerism that develops after whole organ transplantation has led to efforts to augment it with perioperative donor BM infusion. This procedure has been shown to be free of significant complications (including GVHD) in all kinds of whole organ recipients, including those given intestine. The prospects of clinical xenotransplantation must be evaluated in the same context of chimerism as that delineated for allotransplantation with the discovery of spontaneous chimerism. Before addressing chimerism-related questions in xenotransplantation, the additional barrier of the complement activation syndromes that cause hyperacute rejection will have to be surmounted. Although measures to effectively transplant xenografts have so far eluded us, the availability of the more potent drug, tacrolimus, and recognition of the seminal basis of allograft (or xenograft) acceptance via chimerism has inserted an element of reality into the largely wishful thinking that has been evident in discussions about the future of xenotransplantation

    From eremitical to monastic settlements, from rural towards urban areas: the spatial evolution of the Portuguese eremitical congregation of São Paulo da Serra de Ossa

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    The Portuguese Eremitical Congregation of São Paulo da Serra de Ossa was founded in 1482, combining a large number of eremitical settlements that had been documented since 1366, mainly in the Alentejo region (southern Portugal), under a centralised government. In 1578, an autonomous congregation was set up and became affiliated with the Hungarian Order of Saint Paul the First Hermit. This paper aims to analyse the impact of the transition from eremitical to monastic settlements, in terms of both settlement location and architectural typology. The 17 case studies presented in this paper have been identi ed in the geographical region in question. A census of the existing physical structures – sometimes scant remains only – was carried out through literature reviews, archival research and on-site morphological and spatial analyses, allowing for a critical interpretation to be gained of the monastic landscapes. This article shall serve to discuss the implications of the transition from the eremitical movement to the institutionalisation of the settlements, both in terms of their geography and spatial adaptations made as a result of these changes.info:eu-repo/semantics/publishedVersio
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