2,963 research outputs found

    Rare histotype of sporadic Creutzfeldt-Jakob disease, clinically suspected as corticobasal degeneration

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    Sporadic Creutzfeldt-Jakob disease (sCJD) is a rare neurodegenerative disease that can mimic other neurological disorders. We present a case of sCJD in a 64-year-old man that presented with corticobasal syndrome and survived for 3 years. He presented initially with dementia, hemiparkinsonism and alien limb phenomenon and was diagnosed with corticobasal degeneration, ultimately progressing to immobility and akinetic mutism. With a normal MRI 1 year before onset, his neuroimaging 1 year later revealed abnormal DaTscan, cortical and hippocampal atrophy with ventricular dilatation on MRI, and diffusion-weighted cortical ribboning and thalamic hyperintensity. Postmortem, the patient’s brain was collected by the Parkinson’s UK Tissue Bank. Prion protein immunohistochemistry revealed widespread diffuse microvacuolar staining without kuru-type plaques. Hyperphosphorylated tau was only found in the entorhinal cortex and hippocampus. This case highlights the clinical heterogeneity of sCJD presentation and the important inclusion of CJD in the differential diagnosis of atypical presentations of neurodegenerative disease

    Evolution of an elliptical bubble in an accelerating extensional flow

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    Mathematical models that describe the dynamical behavior of a thin gas bubble embedded in a glass fiber during a fiber drawing process have been discussed and analyzed. The starting point for the mathematical modeling was the equations presented in [1] for a glass fiber with a hole undergoing extensional flow. These equations were reconsidered here with the additional reduction that the hole, i.e. the gas bubble, was thin as compared to the radius of the fiber and of finite extent. The primary model considered was one in which the mass of the gas inside the bubble was fixed. This fixed-mass model involved equations for the axial velocity and fiber radius, and equations for the radius of the bubble and the gas pressure inside the bubble. The model equations assumed that the temperature of the furnace of the drawing tower was known. The governing equations of the bubble are hyperbolic and predict that the bubble cannot extend beyond the limiting characteristics specified by the ends of the initial bubble shape. An analysis of pinch-off was performed, and it was found that pinch-off can occur, depending on the parameters of the model, due to surface tension when the bubble radius is small. In order to determine the evolution of a bubble, a numerical method of solution was presented. The method was used to study the evolution of two different initial bubble shapes, one convex and the other non-convex. Both initial bubble shapes had fore-aft symmetry, and it was found that the bubbles stretched and elongated severely during the drawing process. For the convex shape, fore-aft symmetry was lost in the middle of the drawing process, but the symmetry was re-gained by the end of the drawing tower. A small amount of pinch-off was observed at each end for this case, so that the final bubble length was slightly shorter than its theoretical maximum length. For the non-convex initial shape, pinch-off occurred in the middle of the bubble resulting in two bubbles by the end of the fiber draw. The two bubbles had different final pressures and did not have fore-aft symmetry. An extension of the fixed-mass model was considered in which the gas in the bubble was allowed to diffuse into the surrounding glass. The governing equations for this leaky-mass model were developed and manipulated into a form suitable for a numerical treatment

    Homogenization of the Equations Governing the Flow Between a Slider and a Rough Spinning Disk

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    We have analyzed the behavior of the flow between a slider bearing and a hard-drive magnetic disk under two types of surface roughness. For both cases the length scale of the roughness along the surface is small as compared to the scale of the slider, so that a homogenization of the governing equations was performed. For the case of longitudinal roughness, we derived a one-dimensional lubrication-type equation for the leading behavior of the pressure in the direction parallel to the velocity of the disk. The coefficients of the equation are determined by solving linear elliptic equations on a domain bounded by the gap height in the vertical direction and the period of the roughness in the span-wise direction. For the case of transverse roughness the unsteady lubrication equations were reduced, following a multiple scale homogenization analysis, to a steady equation for the leading behavior of the pressure in the gap. The reduced equation involves certain averages of the gap height, but retains the same form of the usual steady, compressible lubrication equations. Numerical calculations were performed for both cases, and the solution for the case of transverse roughness was shown be in excellent agreement with a corresponding numerical calculation of the original unsteady equations

    On the third critical field in Ginzburg-Landau theory

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    Using recent results by the authors on the spectral asymptotics of the Neumann Laplacian with magnetic field, we give precise estimates on the critical field, HC3H_{C_3}, describing the appearance of superconductivity in superconductors of type II. Furthermore, we prove that the local and global definitions of this field coincide. Near HC3H_{C_3} only a small part, near the boundary points where the curvature is maximal, of the sample carries superconductivity. We give precise estimates on the size of this zone and decay estimates in both the normal (to the boundary) and parallel variables

    Beta-decay properties of 25^{25}Si and 26^{26}P

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    The β\beta-decay properties of the neutron-deficient nuclei 25^{25}Si and 26^{26}P have been investigated at the GANIL/LISE3 facility by means of charged-particle and γ\gamma-ray spectroscopy. The decay schemes obtained and the Gamow-Teller strength distributions are compared to shell-model calculations based on the USD interaction. B(GT) values derived from the absolute measurement of the β\beta-decay branching ratios give rise to a quenching factor of the Gamow-Teller strength of 0.6. A precise half-life of 43.7 (6) ms was determined for 26^{26}P, the β\beta- (2)p decay mode of which is described

    Etravirine with 2 NRTIs: an effective switch option for ARV simplification and side effect management

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    Etravirine (ETV) has been approved for use in treatment-experienced patients based on results of the Duet clinical trials [1]. Less experience exists with ETV in earlier stages of treatment. ETV has a favorable genetic barrier, lipid profile, and little associated CNS toxicity. These characteristics make ETV attractive as a switch strategy for simplification and/or management of side effects. A retrospective chart review was conducted at a large urban HIV clinic in Toronto. All patients who were switched to ETV plus 2 nucleosides and whose viral load (VL) was <200 copies/ml at the time of switch were included. Maintenance of viral suppression, CD4 and lipid changes at 24 weeks and reason for switch to ETV are reported. Seventy-three patients (67 male) were identified. Mean age was 46±10 and mean duration of HIV infection was 11.7±7.4 years. Switches were from efavirenz=29, atazanavir=23, lopinavir=16, other=5. Duration of prior regimen was long; median 195 weeks. CNS and GI intolerance were the most common reasons for switches. At the time of analysis, 63 patients had reached week 24. Three patients had discontinued ETV prior to week 24, 3 LTF/U, 4 had <24 weeks follow-up. 92% (67/73) maintained VL suppression (ITT); failures were 6 patients who stopped/lost-to-follow-up prior to week 24. On treatment, CD4 increased and lipid decreased changes as seen below. All patients who switched due to CNS side effects had subjective improvement.Switch to ETV plus 2 nucleosides maintained viral suppression, improved lipid profiles and improved side effect profile in this selected group of patients. 48 week f/u will be presented

    Quantized Roentgen Effect in Bose-Einstein Condensates

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    A classical dielectric moving in a charged capacitor can create a magnetic field (Roentgen effect). A quantum dielectric, however, will not produce a magnetization, except at vortices. The magnetic field outside the quantum dielectric appears as the field of quantized monopoles

    Microscopic calculation of the spin-dependent neutron scattering lengths on 3He

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    We report on the spin.dependent neutron scattering length on 3He from a microscopic calculation of p-3H, n-3He, and d-2H scattering employing the Argonne v18 nucleon-nucleon potential with and without additional three-nucleon force. The results and that of a comprehensive R-matrix analysis are compared to a recent measurement. The overall agreement for the scattering lengths is quite good. The imaginary parts of the scattering lengths are very sensitive to the inclusion of three-nucleon forces, whereas the real parts are almost insensitive.Comment: 9 pages, 1 figur

    Spin picture of the one-dimensional Hubbard model: Two-fluid structure and phase dynamics

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    We propose a scheme for investigating the quantum dynamics of interacting electron models by means of time-dependent variational principle and spin coherent states of space lattice operators. We apply such a scheme to the one-dimensional hubbard model, and solve the resulting equations in different regimes. In particular, we find that at low densities the dynamics is mapped into two coupled nonlinear Schroedinger equations, whereas near half-filling the model is described by two coupled Josephson junction arrays. Focusing then to the case in which only the phases of the spin variables are dynamically active, we examine a number of different solutions corresponding to the excitations of few macroscopic modes. Based on fixed point equation of the simpler among them, we show that the standard one-band ground state phase space is found.Comment: 10 pages, 1 figure, to appear on Phys. Rev.
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