47,638 research outputs found

    Imaging slow failure in triaxially deformed Etna basalt using 3D acoustic-emission location and X-ray computed tomography

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    We have deformed basalt from Mount Etna (Italy) in triaxial compression tests under an effective confining pressure representative of conditions under a volcanic edifice (40 MPa), and at a constant strain rate of 5 similar to 10(-6) s(-1). Despite containing a high level of pre-existing microcrack damage, Etna basalt retains a high strength of 475 MPa. We have monitored the complete deformation cycle through contemporaneous measurements of axial strain, pore volume change, compressional wave velocity change and acoustic emission (AE) output. We have been able to follow the complete evolution of the throughgoing shear fault without recourse to any artificial means of slowing the deformation. Locations of AE events over time yields an estimate of the fault propagation velocity of between 2 and 4 mm. s(-1). We also find excellent agreement between AE locations and post-test images from X-ray microtomography scanning that delineates deformation zone architecture

    Possible Contribution to Electron and Positron Fluxes from Pulsars and their Nebulae

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    The AMS-02 experiment confirms the excess of positrons in cosmic rays (CRs) for energy above 10 GeV with respect to the secondary production of positrons in the interstellar medium. This is interpreted as evidence of the existence of a primary source of these particles. Possible candidates are dark matter or astrophysical sources. In this work we discuss the possible contribution due to pulsars and their nebulae. Our key assumption is that the primary spectrum of electrons and positrons at the source is the same of the well known photon spectrum observed from gamma-rays telescopes. Using a diffusion model in the Galaxy we propagate the source spectra up to the Solar System. We compare our results with the recent experiments and with the LIS modelComment: To appear in the Proceedings of the 14th ICATPP Conference, Villa Olmo 23-27 September 201

    Conforming finite element methods for the clamped plate problem

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    Finite element methods for solving biharmonic boundary value problems are considered. The particular problem discussed is that of a clamped thin plate. This problem is reformulated in a weak, form in the Sobolev space Techniques for setting up conforming trial Functions are utilized in a Galerkin technique to produce finite element solutions. The shortcomings of various trial function formulations are discussed, and a macro—element approach to local mesh refinement using rectangular elements is given

    FORMULATION AND EVALUATION OF VENLAFAXINE HYDROCHLORIDE SUSTAINED RELEASE MATRIX TABLET

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    Aim: The term modified-release drug product is used to describe products that alter the timing and/or the rate of release of the drug substance.Objective: The objective of the present study was to formulate and evaluate the sustained release matrix tablet of venlafaxine hydrochloride.Methods: Venlafaxine hydrochloride is a structurally novel antidepressant for oral administration. It is widely prescribed for the treatment of depression, generalized anxiety disorder, and social anxiety disorder. Venlafaxine hydrochloride is currently available as immediate release tablet and as an extended release capsules under the brand names of Effexor (WYETH AYERST) and Effexor XR (WYETH AYERST). The biological half-life of venlafaxine very short (5 h) and the dose is to be taken 2–3 times a day and the recommended maximum daily dose is 75–450 mg/day. Venlafaxine hydrochloride is an antidepressant and so it is to be taken for quite a long period. Hence, to reduce the dosing frequency, simple, lower cost sustained release tablets of venlafaxine were preferred for the development.Conclusion: The venlafaxine hydrochloride sustained release matrix tablets shown controlled release profile as per the release profile ofthe innovator is EffexorTm_XR. The sustained release of this matrix tablet reduces the dosing frequency and reduces the side effects, bywhich in a long-term therapy, it may be useful as a product with patient compliance for the treatment of major depression disorder

    HIV-associated multi-centric Castleman’s disease with multiple organ failure: cuccessful treatment with rituximab

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    Introduction: Multicentric Castleman's Disease (MCD), a lymphoproliferative disorder associated with Human Herpes Virus-8 (HHV-8) infection, is increasing in incidence amongst HIV patients. This condition is associated with lymphadenopathy, polyclonal gammopathy, hepato-splenomegaly and systemic symptoms. A number of small studies have demonstrated the efficacy of the anti-CD20 monoclonal antibody, rituximab, in treating this condition. Case presentation: We report the case of a 46 year old Zambian woman who presented with pyrexia, diarrhoea and vomiting, confusion, lymphadenopathy, and renal failure. She rapidly developed multiple organ failure following the initiation of treatment of MCD with rituximab. Following admission to intensive care (ICU), she received prompt multi-organ support. After 21 days on the ICU she returned to the haematology medical ward, and was discharged in remission from her disease after 149 days in hospital. Conclusion: Rituximab, the efficacy of which has thus far been examined predominantly in patients outside the ICU, in conjunction with extensive organ support was effective treatment for MCD with associated multiple organ failure. There is, to our knowledge, only one other published report of its successful use in an ICU setting, where it was combined with cyclophosphamide, adriamycin and prednisolone. Reports such as ours support the notion that critically unwell patients with HIV and haematological disease can benefit from intensive care

    Periodicity of dynamical signatures of chaos in quantum kicked top

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    A host of dynamical measures of quantum correlations -- out-of-time ordered correlators, Loschmidt echo, generalized entanglement and observational entropy -- are useful to infer about the underlying classical chaotic dynamics in quantum regime. In this work, these measures are employed to analyse quantum kicked top with kick strength kk. It is shown that, despite the differences in their definitions, these measures are periodic with kk, and the periodicity depends on the number of spins represented by the kicked top. The periodic behaviour arises from the structure of the kicked top Floquet operator and spans the regime in which the corresponding classical dynamics is predominantly chaotic. This result can guide experiments towards the right choice of kick strengths to avoid repetitive dynamics.Comment: 11 pages, 8 figure

    Pyrazolo-triazolo-pyrimidines as adenosine receptor antagonists: A complete structure–activity profile

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    In the last 5 years, many efforts have been conducted searching potent and selective human A3 adenosine antagonists. In this field several different classes of compounds, possessing very good affinity (nM range) and with a broad range of selectivity, have been proposed. Recently, our group synthesized a new series of pyrazolo-triazolo-pyrimidines bearing different substitutions at the N5 and N8 positions, which have been described as highly potent and selective human A3 adenosine receptor antagonists. The present review summarizes available data and provides an overview of the structure–activity relationships found for this class of human A3 adenosine receptor antagonists

    Parameter uncertainty in forecast recalibration

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    This is the author accepted manuscript. The final version is available from Wiley via the DOI in this record.Ensemble forecasts of weather and climate are subject to systematic biases in the ensemble mean and variance, leading to inaccurate estimates of the forecast mean and variance. To address these biases, ensemble forecasts are post-processed using statistical recalibration frameworks. These frameworks often specify parametric probability distributions for the verifying observations. A common choice is the Normal distribution with mean and variance specified by linear functions of the ensemble mean and variance. The parameters of the recalibration framework are estimated from historical archives of forecasts and verifying observations. Often there are relatively few forecasts and observations available for parameter estimation, and so the fitted parameters are also subject to uncertainty. This artefact is usually ignored. This study reviews analytic results that account for parameter uncertainty in the widely used Model Output Statistics recalibration framework. The predictive bootstrap is used to approximate the parameter uncertainty by resampling in more general frameworks such as Non-homogeneous Gaussian Regression. Forecasts on daily, seasonal and annual time scales are used to demonstrate that accounting for parameter uncertainty in the recalibrated predictive distributions leads to probability forecasts that are more skilful and reliable than those in which parameter uncertainty is ignored. The improvements are attributed to more reliable tail probabilities of the recalibrated forecast distributions.Stefan Siegert was supported by the European Union Programme FP7/2007–2013 under grant agreement 3038378 (SPECS). Philip Sansom was supported by a grant from the National Oceanic and Atmospheric Administration (NOAA) NA12OAR4310086
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