7,698 research outputs found

    A Generalization of Abel Inversion to non axisymmetric density distribution

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    Abel Inversion is currently used in laser-plasma studies in order to estimate the electronic density nen_e from the phase-shift map ÎŽÏ•\delta \phi obtained via interferometry. The main limitation of the Abel method is due to the assumption of axial symmetry of the electronic density, which is often hardly fulfilled. In this paper we present an improvement to the Abel inversion technique in which the axial symmetry condition is relaxed by means of a truncated Legendre Polinomial expansion in the azimutal angle. With the help of simulated interferograms, we will show that the generalized Abel inversion generates accurate densities maps when applied to non axisymmetric density sources

    The volumetric rate of calcium-rich transients in the local universe

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    We present a measurement of the volumetric rate of `calcium-rich' optical transients in the local universe, using a sample of three events from the Palomar Transient Factory (PTF). This measurement builds on a detailed study of the PTF transient detection efficiencies, and uses a Monte Carlo simulation of the PTF survey. We measure the volumetric rate of calcium-rich transients to be higher than previous estimates: 1.21−0.39+1.13×10−51.21^{+1.13}_{-0.39}\times10^{-5} events yr−1^{-1} Mpc−3^{-3}. This is equivalent to 33-94% of the local volumetric type Ia supernova rate. This calcium-rich transient rate is sufficient to reproduce the observed calcium abundances in galaxy clusters, assuming an asymptotic calcium yield per calcium-rich event of ~0.05M⊙\mathrm{M}_{\odot}. We also study the PTF detection efficiency of these transients as a function of position within their candidate host galaxies. We confirm as a real physical effect previous results that suggest calcium-rich transients prefer large physical offsets from their host galaxies.Comment: Accepted for publication in ApJ. 9 pages, 5 figure

    MC generator TAUOLA: implementation of Resonance Chiral Theory for two and three meson modes. Comparison with experiment

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    We present a partial upgrade of the Monte Carlo event generator TAUOLA with the two and three hadron decay modes using the theoretical models based on Resonance Chiral Theory. These modes account for 88% of total hadronic width of the tau meson. First results of the model parameters have been obtained using BaBar data for three pion mode.Comment: 5 pages, 1 figure, contribution to the Proceedings of the QCD@Work12 Conferenc

    Therapeutic efficacy of platelet-rich plasma injections in treating high hamstring tendinopathy

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    Thesis (M.A.)--Boston UniversityHamstring muscle and tendon injuries are commonly seen in sports medicine clinics, especially in track and field athletes. However, a less common subset of these injuries has recently begun to gain more attention among researchers and clinicians and is referred to as high hamstring tendinopathy. Patients suffering from this condition typically report deep buttock pain brought on by running, or in severe cases even by prolonged sitting, such as in driving a car for long periods of time. Diagnosis of this condition requires a specific patient history, positive signs on physical exams, as well as positive findings on imaging studies, primarily MRI and ultrasound. Treatment for high hamstring tendinopathy typically starts with conservative measures for pain management including ice, electrical stimulation, and pulsed ultrasound. As soon as patients are able, a physical therapy protocol is prescribed involving stretching, along with strengthening, progressing to eccentric exercises. In cases where symptoms are persistent, more aggressive treatments can be followed, such as corticosteroid injections, extracorporeal shockwave therapy, and surgery in more severe cases. However, because these therapies are often ineffective, expensive, and potentially carry high risks, physicians have begun to turn to alternative forms of therapy. One such treatment gaining recent popularity is the use of platelet-rich plasma injections (PRP). The widely held belief is that PRP provides a higher than average concentration of growth factors than is normally contained in platelets and that these stimulate the wound healing cascade and help in tissue repair and regeneration. PRP is prepared using autologous whole blood from patients by two rounds of centrifugation, separating and concentrating the platelets from other components such as red blood cells and leukocytes. [TRUNCATED

    Theoretical inputs and errors in the new hadronic currents in TAUOLA

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    The new hadronic currents implemented in the TAUOLA library are obtained in the unified and consistent framework of Resonance Chiral Theory: a Lagrangian approach in which the resonances exchanged in the hadronic tau decays are active degrees of freedom included in a way that reproduces the low-energy results of Chiral Perturbation Theory. The short-distance QCD constraints on the imaginary part of the spin-one correlators yield relations among the couplings that render the theory predictive. In this communication, the obtaining of the two- and three-meson form factors is sketched. One of the criticisms to our framework is that the error may be as large as 1/3, since it is a realization of the large-N_C limit of QCD in a meson theory. A number of arguments are given which disfavor that claim pointing to smaller errors, which would explain the phenomenological success of our description in these decays. Finally, other minor sources of error and current improvements of the code are discussed.Comment: 5 pages, no figures, contribution to the Proceedings of the QCD@Work12 Conferenc

    Domains of invasion organelle proteins from apicomplexan parasites are homologous with the Apple domains of blood coagulation factor XI and plasma pre-kallikrein and are members of the PAN module superfamily

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    AbstractMicronemes are specialised organelles, found in all apicomplexan parasites, which secrete molecules that are essential for parasite attachment to and invasion of host cells. Regions of several microneme proteins have sequence similarity to the Apple domains (A-domains) of blood coagulation factor XI (FXI) and plasma pre-kallikrein (PK). We have used mass spectrometry on a recombinant-expressed, putative A-domain from the microneme protein EtMIC5 from Eimeria tenella, to demonstrate that three intramolecular disulphide bridges are formed. These bridges are analogous to those that stabilise A-domains in FXI and PK. The data confirm that the apicomplexan domains are structural homologues of A-domains and are therefore novel members of the PAN module superfamily, which also includes the N-terminal domains of members of the plasminogen/hepatocyte growth factor family. The role of A-domains/PAN modules in apicomplexan parasites is not known, but their presence in the microneme suggests that they may be important for mediating protein–protein or protein–carbohydrate interactions during parasite attachment and host cell invasion

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    Synthetic Spectra for Type Ia Supernovae at Early Epochs

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    We present the current status of our construction of synthetic spectra for type Ia supernovae. These properly take into account the effects of NLTE and an adequate representation of line blocking and blanketing. The models are based on a sophisticated atomic database. We show that the synthetic spectrum reproduces the observed spectrum of 'normal' SN-Ia near maximum light from the UV to the near-IR. However, further improvements are necessary before truly quantitative analyses of observed SN-Ia spectra can be performed. In particular, the inner boundary condition has to be fundamentally modified. This is due to the dominance of electron scattering over true absorption processes coupled with the flat density structure in these objectsComment: To appear in "Proceedings of the IAU Colloquium 192 - Supernovae (10 Years of SN1993J)", eds. J.M. Marcaide and K.W. Weile
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