1,138 research outputs found

    Modelling and Simulation of Handover in Light Fidelity (Li-Fi) Network

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    © 2018 IEEE. The demand of a faster and more secure wireless communication system leads to the development of a new and innovated network in future. Light Fidelity (Li-Fi) is being researched to provide a better wireless network communication. In this communication technology, light from Light Emitting Diodes (LEDs) has been used for data transmission. The purpose of this research work is to investigate the performance of handover algorithms in a Li-Fi network. Two handover algorithms are Closest Access Point (AP) (CAP) and Maximum Channel Gain (MCG). MATLAB simulation results are presented to evaluate those two types of handover algorithms and to show the impacts of UE's rotation and movement on handover performance

    A single residue substitution in the receptor-binding domain of H5N1 hemagglutinin is critical for packaging into pseudotyped lentiviral particles

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    © 2012 Tang et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Background: Serological studies for influenza infection and vaccine response often involve microneutralization and hemagglutination inhibition assays to evaluate neutralizing antibodies against human and avian influenza viruses, including H5N1. We have previously characterized lentiviral particles pseudotyped with H5-HA (H5pp) and validated an H5pp-based assay as a safe alternative for high-throughput serological studies in BSL-2 facilities. Here we show that H5-HAs from different clades do not always give rise to efficient production of H5pp and the underlying mechanisms are addressed. Methodology/Findings: We have carried out mutational analysis to delineate the molecular determinants responsible for efficient packaging of HA from A/Cambodia/40808/2005 (H5Cam) and A/Anhui/1/2005 (H5Anh) into H5pp. Our results demonstrate that a single A134V mutation in the 130-loop of the receptor binding domain is sufficient to render H5Anh the ability to generate H5Anh-pp efficiently, whereas the reverse V134A mutation greatly hampers production of H5Cam-pp. Although protein expression in total cell lysates is similar for H5Anh and H5Cam, cell surface expression of H5Cam is detected at a significantly higher level than that of H5Anh. We further demonstrate by several independent lines of evidence that the behaviour of H5Anh can be explained by a stronger binding to sialic acid receptors implicating residue 134. Conclusions: We have identified a single A134V mutation as the molecular determinant in H5-HA for efficient incorporation into H5pp envelope and delineated the underlying mechanism. The reduced binding to sialic acid receptors as a result of the A134V mutation not only exerts a critical influence in pseudotyping efficiency of H5-HA, but has also an impact at the whole virus level. Because A134V substitution has been reported as a naturally occurring mutation in human host, our results may have implications for the understanding of human host adaptation of avian influenza H5N1 virusesThis work was supported by grants from the Research Fund for the Control of Infectious Diseases of Hong Kong (RFCID#08070972), the Area of Excellence Scheme of the University Grants Committee (grant AoE/M-12/-06 of the Hong Kong Special Administrative Region, China), the French Ministry of Health, and the RESPARI project of the Institut Pasteur International Network

    Branch retinal vein occlusion associated with quetiapine fumarate

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    <p>Abstract</p> <p>Background</p> <p>To report a case of branch retinal vein occlusion in a young adult with bipolar mood disorder treated with quetiapine fumarate.</p> <p>Case Presentation</p> <p>A 29 years old gentleman who was taking quetiapine fumarate for 3 years for bipolar mood disorder, presented with sudden vision loss. He was found to have a superior temporal branch retinal vein occlusion associated with hypercholesterolemia.</p> <p>Conclusion</p> <p>Atypical antipsychotic drugs have metabolic side effects which require regular monitoring and prompt treatment.</p

    Isolated Splenic Metastasis from Renal Cell Carcinoma: Case Report and Review

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    This report presents the case of a 70-year-old woman with a previous history of a left nephrectomy for renal cell carcinoma (RCC), who developed general malaise and fatigue. Abdominal computed tomography demonstrated an enhancing 6 × 7 cm necrotic lesion in the lower pole of the spleen suggestive of a metastasis. Given the highly suspicious nature of the lesion we proceeded to splenectomy. The tumour did not breach the splenic capsule, and there was no local diaphragmatic involvement. The mass was concluded to be a true metastasis of the original RCC rather than local recurrence of the disease. The causes of isolated solid splenic lesions are wide and varied, however a past or present history of malignancy should lead to a high index of suspicion for a splenic metastasis. We report an extremely unusual case of spread from a RCC

    Serviceability performance of steel-concrete composite beams

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    YesFor composite beams with low degrees of shear connection, additional deflections occur due to slip in the shear connectors, which can be significant for beams with low degrees of shear connection. A design formula is presented for the effective stiffness of composite beams taking account of the stiffness of the shear connectors, which is compared to measured deflections of 6 symmetric beams and an 11m span composite beam of asymmetric profile. It is shown that the comparison is good when using a shear connector stiffness of 70 kN/mm for single shear connectors and 100 kN/mm for pairs of shear connectors per deck rib. Results of push tests on a range of deck profiles confirm these initial elastic stiffnesses. To ensure that the slip at the serviceability limit state does not lead to permanent deformations of the beam, it is proposed that the minimum degree of shear connection should not fall below 30% for un-propped beams and 40% for propped beams of symmetric cross-section.European Commissio

    Modelling the Effect of Temperature on Respiration Rate of Fresh Cut Papaya (Carica papaya L.) Fruits.

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    A respiration rate (RR) model based on Peleg’s equation was developed for predicting RRs of fresh cut papaya. Respiration data for fresh cut papaya at 3/4 maturity were generated at temperatures 5, 10, 15, 20, 25 and 30°C using a closed system. RRs was found to be significantly influenced by storage temperature and increased from 0.021 to 0.289 mL[O2]/kg·h and 0.063 to 0.393 mL[CO2]/kg·h as a function of O2 and CO2 gas concentrations, respectively. Peleg’s constant K 1 and K 2 were obtained from linear regression analysis using GraphPad Prism 5.0 software and regression coefficients have good fit with values close to unity. The model was verified to assess the capability of its predictability of the RRs over the temperatures. There was good agreement with the experimentally estimated RRs. Information derived from the model can contribute in the design of successful modified atmospheric systems for storage of fresh cut papaya

    Boolean Dynamics with Random Couplings

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    This paper reviews a class of generic dissipative dynamical systems called N-K models. In these models, the dynamics of N elements, defined as Boolean variables, develop step by step, clocked by a discrete time variable. Each of the N Boolean elements at a given time is given a value which depends upon K elements in the previous time step. We review the work of many authors on the behavior of the models, looking particularly at the structure and lengths of their cycles, the sizes of their basins of attraction, and the flow of information through the systems. In the limit of infinite N, there is a phase transition between a chaotic and an ordered phase, with a critical phase in between. We argue that the behavior of this system depends significantly on the topology of the network connections. If the elements are placed upon a lattice with dimension d, the system shows correlations related to the standard percolation or directed percolation phase transition on such a lattice. On the other hand, a very different behavior is seen in the Kauffman net in which all spins are equally likely to be coupled to a given spin. In this situation, coupling loops are mostly suppressed, and the behavior of the system is much more like that of a mean field theory. We also describe possible applications of the models to, for example, genetic networks, cell differentiation, evolution, democracy in social systems and neural networks.Comment: 69 pages, 16 figures, Submitted to Springer Applied Mathematical Sciences Serie
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