271 research outputs found

    Estimation of Poisson-Dirichlet Parameters with Monotone Missing Data

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    This article considers the estimation of the unknown numerical parameters and the density of the base measure in a Poisson-Dirichlet process prior with grouped monotone missing data. The numerical parameters are estimated by the method of maximum likelihood estimates and the density function is estimated by kernel method. A set of simulations was conducted, which shows that the estimates perform well

    Involvement of TIP60 acetyltransferase in intracellular Salmonella replication

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    <p>Abstract</p> <p>Background</p> <p><it>Salmonella </it>enterica is a facultative intracellular pathogen that replicates within a membrane-bound compartment termed <it>Salmonella </it>containing vacuole (SCV). The biogenesis of SCV requires <it>Salmonella </it>type III protein secretion/translocation system and their effector proteins which are translocated into host cells to exploit the vesicle trafficking pathways. SseF is one of these effectors required for SCV formation and Intracellular <it>Salmonella </it>replication through unknown mechanisms.</p> <p>Results</p> <p>In an attempt to identify host proteins that interact with SseF, we conduct a yeast two-hybrid screening of human cell cDNA library using SseF as the bait. We identified that TIP60, an acetyltransferase, interacts with SseF. We showed that the TIP60 acetylation activity was increased in the presence of SseF, and TIP60 was upregulated upon <it>Salmonella </it>infection. In addition, TIP60 is required for efficient intracellular <it>Salmonella </it>replication in macrophages.</p> <p>Conclusion</p> <p>Taken together, our data suggest that <it>Salmonella </it>may use SseF to exploit the host TIP60 acetyltransferase activity to promote efficient <it>Salmonella </it>replication inside host cells.</p

    A flexible dual-mode pressure sensor with ultra-high sensitivity based on BTO@MWCNTs core-shell nanofibers

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    Wearable flexible sensors have developed rapidly in recent years because of their improved capacity to detect human motion in wide-ranging situations. In order to meet the requirements of flexibility and low detection limits, a new pressure sensor was fabricated based on electrospun barium titanate/multi-wall carbon nanotubes (BTO@MWCNTs) core-shell nanofibers coated with styrene-ethylene-butene-styrene block copolymer (SEBS). The sensor material (BTO@MWCNTs/SEBS) had a SEBS to BTO/MWCNTs mass ratio of 20:1 and exhibited an excellent piezoelectricity over a wide range of workable pressures from 1 to 50 kPa, higher output current of 56.37 nA and a superior piezoresistivity over a broad working range of 20 to 110 kPa in compression. The sensor also exhibited good durability and repeatability under different pressures and under long-term cyclic loading. These properties make the composite ideal for applications requiring monitoring subtle pressure changes (exhalation, pulse rate) and finger movements. The pressure sensor developed based on BTO@MWCNTs core-shell nanofibers has demonstrated great potential to be assembled into intelligent wearable devices

    Numerical Simulation of Unsteady Conjugate Heat Transfer of Electrothermal Deicing Process

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    A novel 3-D unsteady model of in-flight electrothermal deicing process is presented in this paper to simulate the conjugate mass and heat transfer phenomena of water film runback, phase change, and solid heat conduction. Mathematical models of water film runback and phase change are established and solved by means of a loosely coupled method. At the current time step, solid heat conduction, water film runback, and phase change are iteratively solved until the heat boundary condition reaches convergence, then the temperature distribution and ice shape at the moment are obtained, and the calculation of the next time step begins subsequently. A deicing process is numerically simulated using the present model following an icing tunnel experiment, and the results match well with those in the literatures, which validate the present model. Then, an in-flight deicing process is numerically studied to analyze the effect of heating sequence
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