46,266 research outputs found

    Polarization Induced Switching Effect in Graphene Nanoribbon Edge-Defect Junction

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    With nonequilibrium Green's function approach combined with density functional theory, we perform an ab initio calculation to investigate transport properties of graphene nanoribbon junctions self-consistently. Tight-binding approximation is applied to model the zigzag graphene nanoribbon (ZGNR) electrodes, and its validity is confirmed by comparison with GAUSSIAN03 PBC calculation of the same system. The origin of abnormal jump points usually appearing in the transmission spectrum is explained with the detailed tight-binding ZGNR band structure. Transport property of an edge defect ZGNR junction is investigated, and the tunable tunneling current can be sensitively controlled by transverse electric fields.Comment: 18 pages, 8 figure

    Hepatitis C in Haematological Patients

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    There is no consensus guideline concerning the management of chronic hepatitis C patients during chemotherapy, and immunosuppression. However, there are some suggestions in literature that hepatitis C viral load increases during chemotherapy and there is a risk of rebound immunity against hepatitis C after discontinuation of immunosuppression with a consequent liver injury. A close monitoring of liver function of these patients is prudent during treatment of haematological malignancy. Antiviral treatment is deferred after the completion of chemotherapy and recovery of patients' immunity to minimize the toxicity of treatment. A combination of pegylated interferon and ribavirin is the standard therapy in hepatitis C infected haematological patients

    An Update in Management of Noncutaneous T-Cell Lymphomas

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    T-cell lymphoma is a heterogeneous group of diseases. Except for ALK positive anaplastic large cell lymphoma, T-cell lymphoma responds to conventional chemotherapy unfavourably, and most patients carry poor prognosis. In recent years, efforts have been made to improve the outcome of T-cell lymphoma patients. Novel agents, high-dose therapy, and allogeneic stem cell transplantation are studied, and various results are reported in literature. This paper looks into the prognostication and treatment approach of different entities of noncutaneous T-cell lymphoma and would focus on the latest updates in its management

    Automating Carotid Intima-Media Thickness Video Interpretation with Convolutional Neural Networks

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    Cardiovascular disease (CVD) is the leading cause of mortality yet largely preventable, but the key to prevention is to identify at-risk individuals before adverse events. For predicting individual CVD risk, carotid intima-media thickness (CIMT), a noninvasive ultrasound method, has proven to be valuable, offering several advantages over CT coronary artery calcium score. However, each CIMT examination includes several ultrasound videos, and interpreting each of these CIMT videos involves three operations: (1) select three end-diastolic ultrasound frames (EUF) in the video, (2) localize a region of interest (ROI) in each selected frame, and (3) trace the lumen-intima interface and the media-adventitia interface in each ROI to measure CIMT. These operations are tedious, laborious, and time consuming, a serious limitation that hinders the widespread utilization of CIMT in clinical practice. To overcome this limitation, this paper presents a new system to automate CIMT video interpretation. Our extensive experiments demonstrate that the suggested system significantly outperforms the state-of-the-art methods. The superior performance is attributable to our unified framework based on convolutional neural networks (CNNs) coupled with our informative image representation and effective post-processing of the CNN outputs, which are uniquely designed for each of the above three operations.Comment: J. Y. Shin, N. Tajbakhsh, R. T. Hurst, C. B. Kendall, and J. Liang. Automating carotid intima-media thickness video interpretation with convolutional neural networks. CVPR 2016, pp 2526-2535; N. Tajbakhsh, J. Y. Shin, R. T. Hurst, C. B. Kendall, and J. Liang. Automatic interpretation of CIMT videos using convolutional neural networks. Deep Learning for Medical Image Analysis, Academic Press, 201

    Strong Secrecy for Multiple Access Channels

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    We show strongly secret achievable rate regions for two different wiretap multiple-access channel coding problems. In the first problem, each encoder has a private message and both together have a common message to transmit. The encoders have entropy-limited access to common randomness. If no common randomness is available, then the achievable region derived here does not allow for the secret transmission of a common message. The second coding problem assumes that the encoders do not have a common message nor access to common randomness. However, they may have a conferencing link over which they may iteratively exchange rate-limited information. This can be used to form a common message and common randomness to reduce the second coding problem to the first one. We give the example of a channel where the achievable region equals zero without conferencing or common randomness and where conferencing establishes the possibility of secret message transmission. Both coding problems describe practically relevant networks which need to be secured against eavesdropping attacks.Comment: 55 page

    A comprehensive analysis of Swift/XRT data: I. Apparent spectral evolution of GRB X-ray tails

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    An early steep decay component following the prompt GRBs is commonly observed in {\em Swift} XRT light curves, which is regarded as the tail emission of the prompt gamma-rays. Prompted by the observed strong spectral evolution in the tails of GRBs 060218 and 060614, we present a systematic time-resolved spectral analysis for the {\em Swift} GRB tails detected between 2005 February and 2007 January. We select a sample of 44 tails that are bright enough to perform time-resolved spectral analyses. Among them 11 tails are smooth and without superimposing significant flares, and their spectra have no significant temporal evolution. We suggest that these tails are dominated by the curvature effect of the prompt gamma-rays due to delay of propagation of photons from large angles with respect to the line of sight . More interestingly, 33 tails show clear hard-to-soft spectral evolution, with 16 of them being smooth tails directly following the prompt GRBs,while the others being superimposed with large flares. We focus on the 16 clean, smooth tails and consider three toy models to interpret the spectral evolution. The curvature effect of a structured jet and a model invoking superposition of the curvature effect tail and a putative underlying soft emission component cannot explain all the data. The third model, which invokes an evolving exponential spectrum, seems to reproduce both the lightcurve and the spectral evolution of all the bursts, including GRBs 060218 and 060614. More detailed physical models are called for to understand the apparent evolution effect.Comment: 13 pages in emulateapj style,6 figures, 1 table, expanded version, matched to published version, ApJ, 2007, in press. This is the first paper of a series. Paper II see arXiv:0705.1373 (ApJ,2007, in press
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