3,547 research outputs found

    cAMP Perturbs Inter-Sertoli Tight Junction Permeability Barrier in vitro via its Effects on Proteasome-sensitive Ubiquitination of Occludin

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    Homotopy Method for the Large, Sparse, Real Nonsymmetric Eigenvalue Problem

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    A homotopy method to compute the eigenpairs, i.e., the eigenvectors and eigenvalues, of a given real matrix A1 is presented. From the eigenpairs of some real matrix A0, the eigenpairs of A(t) ≡ (1 − t)A0 + tA1 are followed at successive "times" from t = 0 to t = 1 using continuation. At t = 1, the eigenpairs of the desired matrix A1 are found. The following phenomena are present when following the eigenpairs of a general nonsymmetric matrix: • bifurcation, • ill conditioning due to nonorthogonal eigenvectors, • jumping of eigenpaths. These can present considerable computational difficulties. Since each eigenpair can be followed independently, this algorithm is ideal for concurrent computers. The homotopy method has the potential to compete with other algorithms for computing a few eigenvalues of large, sparse matrices. It may be a useful tool for determining the stability of a solution of a PDE. Some numerical results will be presented

    The effects of public housing on internal mobility in Hong Kong

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    The rationing of public housing reduces the efficiency of the match between public housing units and their occupants, as competing users cannot effectively convey their preferences through a price mechanism. This study investigates the costs of public housing from the perspective of the misallocation of housing units to households and examines how this misallocation affects their lives. We show that public housing occupants are less mobile than private housing occupants, but conditional on moving, they are more likely to relocate farther away from their original place of residence. They are also less likely to work in the same place as they live. Š 2010 Elsevier Inc.postprin

    A kinetic study of tin dissolution.

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    Dissolution of tin in hydrochloric acid.

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    Non-line-of-sight Node Localization based on Semi-Definite Programming in Wireless Sensor Networks

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    An unknown-position sensor can be localized if there are three or more anchors making time-of-arrival (TOA) measurements of a signal from it. However, the location errors can be very large due to the fact that some of the measurements are from non-line-of-sight (NLOS) paths. In this paper, we propose a semi-definite programming (SDP) based node localization algorithm in NLOS environment for ultra-wideband (UWB) wireless sensor networks. The positions of sensors can be estimated using the distance estimates from location-aware anchors as well as other sensors. However, in the absence of LOS paths, e.g., in indoor networks, the NLOS range estimates can be significantly biased. As a result, the NLOS error can remarkably decrease the location accuracy. And it is not easy to efficiently distinguish LOS from NLOS measurements. In this paper, an algorithm is proposed that achieves high location accuracy without the need of identifying NLOS and LOS measurement.Comment: submitted to IEEE ICC'1

    Quiescent Prominence Dynamics Observed with the Hinode Solar Optical Telescope. II. Prominence Bubble Boundary Layer Characteristics and the Onset of a Coupled Kelvin–Helmholtz Rayleigh–Taylor Instability

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    This is the author accepted manuscript. The final version is available from American Astronomical Society via the DOI in this record.We analyze solar quiescent prominence bubble characteristics and instability dynamics using Hinode/Solar Optical Telescope (SOT) data. We measure bubble expansion rate, prominence downflows, and the profile of the boundary layer brightness and thickness as a function of time. The largest bubble analyzed rises into the prominence with a speed of about 1.3 km s−1 until it is destabilized by a localized shear flow on the boundary. Boundary layer thickness grows gradually as prominence downflows deposit plasma onto the bubble with characteristic speeds of 20 − 35 km s−1 . Lateral downflows initiate from the thickened boundary layer with characteristic speeds of 25 − 50 km s−1 , “draining” the layer of plasma. Strong shear flow across one bubble boundary leads to an apparent coupled Kelvin-Helmholtz Rayleigh-Taylor (KH-RT) instability. We measure shear flow speeds above the bubble of 10 km s−1 and infer interior bubble flow speeds on the order of 100 km s−1 . Comparing the measured growth rate of the instability to analytic expressions, we infer a magnetic flux density across the bubble boundary of ∼ 10−3 T (10 gauss) at an angle of ∼ 70◦ to the prominence plane. The results are consistent with the hypothesis that prominence bubbles are caused by magnetic flux that emerges below a prominence, setting up the conditions for RT, or combined KH-RT, instability flows that transport flux, helicity, and hot plasma upward into the overlying coronal magnetic flux ropeTEB was supported by NASA contracts NNM07AA01C (Solar-B FPP), NNG04EA00C (SDO/AIA) while at the Lockheed Martin Solar and Astrophysics Laboratory (LMSAL), and by The National Weather Service (NWS) Office of Science and Technology Integration (OSTI) while at the National Oceanic and Atmospheric Administration (NOAA). A.H. was supported by his STFC Ernest Rutherford Fellowship grant number ST/L00397X/2. W.L. was supported by NASA HGI grant NNX15AR15G and NASA contract NNG09FA40C (IRIS) at LMSAL
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