6,324 research outputs found

    Boundary effects on the scaling of the superfluid density

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    We study numerically the influence of the substrate (boundary conditions) on the finite--size scaling properties of the superfluid density ρs\rho_s in superfluid films of thickness HH within the XY model employing the Monte Carlo method. Our results suggest that the jump ρsH/Tc\rho_s H/T_c at the Kosterlitz--Thouless transition temperature TcT_c depends on the boundary conditions.Comment: 2 pages, 1 Latex file, 1 postscript figure, 2 style file

    A patient preference study that evaluated fluticasone furoate and mometasone furoate nasal sprays for allergic rhinitis

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    Background: Corticosteroid nasal sprays are the mainstay of treatment for allergic rhinitis. These sprays have sensory attributes such as scent and/or odor, taste and aftertaste, and run down the throat and/or the nose, which, when unpleasant, can affect patient preference for, and compliance with, treatment. Objective: This study examined patient preference for fluticasone furoate nasal spray (FFNS) or mometasone furoate nasal spray (MFNS) based on their sensory attributes after administration in patients with allergic rhinitis. Methods: This was a multicenter, randomized, double-blind, cross-over study. Patient preferences were determined by using three questionnaires (Overall Preference, Immediate Attributes, and Delayed Attributes). Results: Overall, 56% of patients stated a preference for FFNS versus 32% for MFNS (p _ 0.001); the remaining 12% stated no preference. More patients stated a preference for FFNS versus MFNS for the attributes of “less drip down the throat” (p _ 0.001), “less run out of the nose” (p _ 0.05), “more soothing” (p _ 0.05), and “less irritating” (p _ 0.001). More patients responded in favor of FFNS versus MFNS for the immediate attributes, “run down the throat” (p _ 0.001), and “run out of the nose” (p _ 0.001), and, in the delayed attributes, “run down the throat” (p _ 0.001), “run out of the nose” (p _ 0.01), “presence of aftertaste” (p _ 0.01), and “no nasal irritation” (p _ 0.001). Conclusion: Patients with allergic rhinitis preferred FFNS versus MFNS overall and based on a number of individual attributes, including “less drip down the throat,” “less run out of the nose,” and “less irritating.” Greater preference may improve patient adherence and thereby improve symptom management of the patient’s allergic rhinitis

    The Ellipticity and Orientation of Clusters of Galaxies from N-Body Experiments

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    In this study we use simulations of 1283^3 particles to study the ellipticity and orientation of clusters of galaxies in N-body simulations of differing power-law initial spectra (P(k) \propto k^n ,n = +1, 0, -1, -2),anddensityparameters(), and density parameters (\Omega_0 = 0.2to1.0).Furthermore,unlikemosttheoreticalstudieswemimicmostobserversbyremovingallparticleswhichlieatdistancesgreaterthan21/hMpcfromtheclustercenterofmass.Wecomputedtheaxialratioandtheprincipalaxesusingtheinertiatensorofeachcluster.Themeanellipticityofclustersincreasesstronglywithincreasing to 1.0). Furthermore, unlike most theoretical studies we mimic most observers by removing all particles which lie at distances greater than 2 1/h Mpc from the cluster center of mass. We computed the axial ratio and the principal axes using the inertia tensor of each cluster. The mean ellipticity of clusters increases strongly with increasing n.Wealsofindthatclusterstendtobecomemoresphericalatsmallerradii.Wecomparedtheorientationofaclustertotheorientationofneighboringclustersasafunctionofdistance(correlation).Inaddition,weconsideredwhetheraclustersmajoraxistendstoliealongthelineconnectingittoaneighboringcluster,asafunctionofdistance(alignment).Bothalignmentsandcorrelationswerecomputedinthreedimensionsandinprojectiontomimicobservationalsurveys.Ourresultsshowthatsignificantalignmentsexistforallspectraatsmallseparations(. We also find that clusters tend to become more spherical at smaller radii. We compared the orientation of a cluster to the orientation of neighboring clusters as a function of distance (correlation). In addition, we considered whether a cluster's major axis tends to lie along the line connecting it to a neighboring cluster, as a function of distance (alignment). Both alignments and correlations were computed in three dimensions and in projection to mimic observational surveys. Our results show that significant alignments exist for all spectra at small separations (D < 15 h^{-1}Mpc)butdropsoffatlargerdistanceinastrongly Mpc) but drops off at larger distance in a strongly n-$dependent way.Comment: 22 pages, requires aaspp4.sty, flushrt.sty, and epsf.sty Revised manuscript, accepted for publication in Ap

    NaAlSi: a self-doped semimetallic superconductor with free electrons and covalent holes

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    The layered ternary sp conductor NaAlSi, possessing the iron-pnictide "111" crystal structure, superconducts at 7 K. Using density functional methods, we show that this compound is an intrinsic (self-doped) low-carrier-density semimetal with a number of unusual features. Covalent Al-Si valence bands provide the holes, and free-electron-like Al 3s bands, which propagate in the channel between the neighboring Si layers, dip just below the Fermi level to create the electron carriers. The Fermi level (and therefore the superconducting carriers) lies in a narrow and sharp peak within a pseudogap in the density of states. The small peak arises from valence bands which are nearly of pure Si, quasi-two-dimensional, flat, and coupled to Al conduction bands. Isostructural NaAlGe, which is not superconducting above 1.6 K, has almost exactly the same band structure except for one missing piece of small Fermi surface. Certain deformation potentials induced by Si and Na displacements along the c-axis are calculated and discussed. It seems likely that the mechanism of pairing is related to that of several other lightly doped two-dimensional nonmagnetic semiconductors (TiNCl, ZrNCl, HfNCl), which is not well understood but apparently not of phonon origin.Comment: 9 pages, 7 figures, 1 tabl

    AAV-mediated and pharmacological induction of Hsp70 expression stimulates survival of retinal ganglion cells following axonal injury.

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    We evaluated the effect of AAV2- and 17-AAG (17-N-allylamino-17-demethoxygeldanamycin)-mediated upregulation of Hsp70 expression on the survival of retinal ganglion cells (RGCs) injured by optic nerve crush (ONC). AAV2-Hsp70 expression in the retina was primarily observed in the ganglion cell layer. Approximately 75% of all transfected cells were RGCs. RGC survival in AAV2-Hsp70-injected animals was increased by an average of 110% 2 weeks after the axonal injury compared with the control. The increase in cell numbers was not even across the retinas with a maximum effect of approximately 306% observed in the inferior quadrant. 17-AAG-mediated induction of Hsp70 expression has been associated with cell protection in various models of neurodegenerative diseases. We show here that a single intravitreal injection of 17-AAG (0.2 ug ul(-1)) results in an increased survival of ONC-injured RGCs by approximately 49% compared with the vehicle-treated animals. Expression of Hsp70 in retinas of 17-AAG-treated animals was upregulated approximately by twofold compared with control animals. Our data support the idea that the upregulation of Hsp70 has a beneficial effect on the survival of injured RGCs, and the induction of this protein could be viewed as a potential neuroprotective strategy for optic neuropathies

    Time--Splitting Schemes and Measure Source Terms for a Quasilinear Relaxing System

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    Several singular limits are investigated in the context of a 2×22 \times 2 system arising for instance in the modeling of chromatographic processes. In particular, we focus on the case where the relaxation term and a L2L^2 projection operator are concentrated on a discrete lattice by means of Dirac measures. This formulation allows to study more easily some time-splitting numerical schemes
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