450 research outputs found

    Increased dissolution rates of tranilast solid dispersions extruded with inorganic excipients

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    The purpose of this study was to evaluate the performance of Neusilin¼ (NEU) a synthetic magnesium aluminometasilicate as inorganic drug carrier co-processed with the hydrophilic surfactants Labrasol and Labrafil to develop Tranilast (TLT) based solid dispersions using continuous melt extrusion (HME) processing. Twin – screw extrusion was optimized to develop various TLT/excipient/surfactant formulations followed by continuous capsule filling in the absence of any downstream equipment. Physicochemical characterisation showed the existence of TLT in partially crystalline state in the porous network of inorganic NEU for all extruded formulations. Furthermore, the in line NIR studies revealed a possible intermolecular H–bonding formation between the drug and carrier resulting in the increase of dissolution of TLT. The capsules containing TLT extruded solid dispersions showed enhanced dissolution rates and compared with the marketed Rizaben¼ product

    Abundance and evolution of galaxy clusters in cosmological models with massive neutrino

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    The time evolution of the number density of galaxy clusters and their mass and temperature functions are used to constrain cosmological parameters in the spatially flat dark matter models containing a fraction of hot particles (massive neutrino) additional to cold and baryonic matter. We test the modified MDM models with cosmic gravitational waves and show that they neither pass the cluster evolution test nor reproduce the observed height of the first acoustic peak in ΔT/T\Delta T/T spectrum, and therefore should be ruled out. The models with a non-zero cosmological constant are in better agreement with observations. We estimate the free cosmological parameters in Λ\LambdaMDM with a negligible abundance of gravitational waves, and find that within the parameter ranges h∈(0.6,0.7)h\in (0.6, 0.7), n∈(0.9,1.1)n\in (0.9, 1.1), (i) the value of ΩΛ\Omega_\Lambda is strongly affected by a small fraction of hot dark matter, fÎœâ‰ĄÎ©Îœ/Ωm∈(0,0.2)f_\nu\equiv\Omega_\nu /\Omega_m\in (0, 0.2): 0.45<ΩΛ<0.70.45 <\Omega_\Lambda <0.7 (1σ1\sigma CL), and (ii) the redshift evolution of galaxy clusters alone reveals the following explicit correlation between ΩΛ\Omega_\Lambda and fÎœf_\nu: ΩΛ+0.5fÎœ=0.65±0.1\Omega_\Lambda +0.5f_\nu =0.65\pm 0.1. The present accuracy of observational data allows only to bound the fraction of hot matter, fΜ∈(0,0.2)f_\nu\in (0, 0.2) (the number of massive neutrino species remains undelimited, NÎœ=1,2,3N_\nu =1, 2, 3).Comment: 9 pages, 7 figures, submitted in A&

    On the fourth-order accurate compact ADI scheme for solving the unsteady Nonlinear Coupled Burgers' Equations

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    The two-dimensional unsteady coupled Burgers' equations with moderate to severe gradients, are solved numerically using higher-order accurate finite difference schemes; namely the fourth-order accurate compact ADI scheme, and the fourth-order accurate Du Fort Frankel scheme. The question of numerical stability and convergence are presented. Comparisons are made between the present schemes in terms of accuracy and computational efficiency for solving problems with severe internal and boundary gradients. The present study shows that the fourth-order compact ADI scheme is stable and efficient

    New Insights into White-Light Flare Emission from Radiative-Hydrodynamic Modeling of a Chromospheric Condensation

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    (abridged) The heating mechanism at high densities during M dwarf flares is poorly understood. Spectra of M dwarf flares in the optical and near-ultraviolet wavelength regimes have revealed three continuum components during the impulsive phase: 1) an energetically dominant blackbody component with a color temperature of T ∌\sim 10,000 K in the blue-optical, 2) a smaller amount of Balmer continuum emission in the near-ultraviolet at lambda << 3646 Angstroms and 3) an apparent pseudo-continuum of blended high-order Balmer lines. These properties are not reproduced by models that employ a typical "solar-type" flare heating level in nonthermal electrons, and therefore our understanding of these spectra is limited to a phenomenological interpretation. We present a new 1D radiative-hydrodynamic model of an M dwarf flare from precipitating nonthermal electrons with a large energy flux of 101310^{13} erg cm−2^{-2} s−1^{-1}. The simulation produces bright continuum emission from a dense, hot chromospheric condensation. For the first time, the observed color temperature and Balmer jump ratio are produced self-consistently in a radiative-hydrodynamic flare model. We find that a T ∌\sim 10,000 K blackbody-like continuum component and a small Balmer jump ratio result from optically thick Balmer and Paschen recombination radiation, and thus the properties of the flux spectrum are caused by blue light escaping over a larger physical depth range compared to red and near-ultraviolet light. To model the near-ultraviolet pseudo-continuum previously attributed to overlapping Balmer lines, we include the extra Balmer continuum opacity from Landau-Zener transitions that result from merged, high order energy levels of hydrogen in a dense, partially ionized atmosphere. This reveals a new diagnostic of ambient charge density in the densest regions of the atmosphere that are heated during dMe and solar flares.Comment: 50 pages, 2 tables, 13 figures. Accepted for publication in the Solar Physics Topical Issue, "Solar and Stellar Flares". Version 2 (June 22, 2015): updated to include comments by Guest Editor. The final publication is available at Springer via http://dx.doi.org/10.1007/s11207-015-0708-

    Ralph: A Visible/Infrared Imager for the New Horizons Pluto/Kuiper Belt Mission

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    The New Horizons instrument named Ralph is a visible/near infrared multi-spectral imager and a short wavelength infrared spectral imager. It is one of the core instruments on New Horizons, NASA's first mission to the Pluto/Charon system and the Kuiper Belt. Ralph combines panchromatic and color imaging capabilities with IR imaging spectroscopy. Its primary purpose is to map the surface geology and composition of these objects, but it will also be used for atmospheric studies and to map the surface temperature. It is a compact, low-mass (10.5 kg), power efficient (7.1 W peak), and robust instrument with good sensitivity and excellent imaging characteristics. Other than a door opened once in flight, it has no moving parts. These characteristics and its high degree of redundancy make Ralph ideally suited to this long-duration flyby reconnaissance mission.Comment: 18 pages, 15 figures, 4 tables; To appear in a special volume of Space Science Reviews on the New Horizons missio

    Complete measurement of three-body photodisintegration of 3He for photon energies between 0.35 and 1.55 GeV

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    The three-body photodisintegration of 3He has been measured with the CLAS detector at Jefferson Lab, using tagged photons of energies between 0.35 GeV and 1.55 GeV. The large acceptance of the spectrometer allowed us for the first time to cover a wide momentum and angular range for the two outgoing protons. Three kinematic regions dominated by either two- or three-body contributions have been distinguished and analyzed. The measured cross sections have been compared with results of a theoretical model, which, in certain kinematic ranges, have been found to be in reasonable agreement with the data.Comment: 22 pages, 25 eps figures, 2 tables, submitted to PRC. Modifications: removed 2 figures, improvements on others, a few minor modifications to the tex

    A Kinematically Complete Measurement of the Proton Structure Function F2 in the Resonance Region and Evaluation of Its Moments

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    We measured the inclusive electron-proton cross section in the nucleon resonance region (W < 2.5 GeV) at momentum transfers Q**2 below 4.5 (GeV/c)**2 with the CLAS detector. The large acceptance of CLAS allowed for the first time the measurement of the cross section in a large, contiguous two-dimensional range of Q**2 and x, making it possible to perform an integration of the data at fixed Q**2 over the whole significant x-interval. From these data we extracted the structure function F2 and, by including other world data, we studied the Q**2 evolution of its moments, Mn(Q**2), in order to estimate higher twist contributions. The small statistical and systematic uncertainties of the CLAS data allow a precise extraction of the higher twists and demand significant improvements in theoretical predictions for a meaningful comparison with new experimental results.Comment: revtex4 18 pp., 12 figure

    eta-prime photoproduction on the proton for photon energies from 1.527 to 2.227 GeV

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    Differential cross sections for the reaction gamma p -> eta-prime p have been measured with the CLAS spectrometer and a tagged photon beam with energies from 1.527 to 2.227 GeV. The results reported here possess much greater accuracy than previous measurements. Analyses of these data indicate for the first time the coupling of the etaprime N channel to both the S_11(1535) and P_11(1710) resonances, known to couple strongly to the eta N channel in photoproduction on the proton, and the importance of j=3/2 resonances in the process.Comment: 6 pages, 3 figure

    Measurement of the Deuteron Structure Function F2 in the Resonance Region and Evaluation of Its Moments

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    Inclusive electron scattering off the deuteron has been measured to extract the deuteron structure function F2 with the CEBAF Large Acceptance Spectrometer (CLAS) at the Thomas Jefferson National Accelerator Facility. The measurement covers the entire resonance region from the quasi-elastic peak up to the invariant mass of the final-state hadronic system W~2.7 GeV with four-momentum transfers Q2 from 0.4 to 6 (GeV/c)^2. These data are complementary to previous measurements of the proton structure function F2 and cover a similar two-dimensional region of Q2 and Bjorken variable x. Determination of the deuteron F2 over a large x interval including the quasi-elastic peak as a function of Q2, together with the other world data, permit a direct evaluation of the structure function moments for the first time. By fitting the Q2 evolution of these moments with an OPE-based twist expansion we have obtained a separation of the leading twist and higher twist terms. The observed Q2 behaviour of the higher twist contribution suggests a partial cancellation of different higher twists entering into the expansion with opposite signs. This cancellation, found also in the proton moments, is a manifestation of the "duality" phenomenon in the F2 structure function

    Measurement of the Polarized Structure Function σLTâ€Č\sigma_{LT^\prime} for p(e⃗,eâ€Čπ+)np(\vec{e},e'\pi^+)n in the Δ(1232)\Delta(1232) Resonance Region

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    The polarized longitudinal-transverse structure function σLTâ€Č\sigma_{LT^\prime} has been measured using the p(e⃗,eâ€Čπ+)np(\vec e,e'\pi^+)n reaction in the Δ(1232)\Delta(1232) resonance region at Q2=0.40Q^2=0.40 and 0.65 GeV2^2. No previous σLTâ€Č\sigma_{LT^\prime} data exist for this reaction channel. The kinematically complete experiment was performed at Jefferson Lab with the CEBAF Large Acceptance Spectrometer (CLAS) using longitudinally polarized electrons at an energy of 1.515 GeV. A partial wave analysis of the data shows generally better agreement with recent phenomenological models of pion electroproduction compared to the previously measured π0p\pi^0 p channel. A fit to both π0p\pi^0 p and π+n\pi^+ n channels using a unitary isobar model suggests the unitarized Born terms provide a consistent description of the non-resonant background. The tt-channel pion pole term is important in the π0p\pi^0 p channel through a rescattering correction, which could be model-dependent.Comment: 6 pages, LaTex, 5 eps figures: Submitted to PRC/Brief Reports v2: Updated referenc
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