3,615 research outputs found

    Maintenance H2-antagonist is not necessary after eradication of Helicobacter pylori in bleeding peptic ulcers

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    An implicit boundary finite element method with extension to frictional sliding boundary conditions and elasto-plastic analyses

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    Implicit boundary methods, which enrich the interpolation structure with implicit weight functions, are straightforward methods for the enforcement of Dirichlet boundary conditions. In this article, we follow the implicit boundary method that uses approximate step functions (the step boundary method) developed by Kumar et al. and provide modifications that have several advantages. Roller boundary conditions have wide practical applications in engineering, however, the step boundary method for roller boundary conditions with inclinations has yet to be fully formulated through to the final linear system of equations. Thus we provide a complete derivation that leads to simplified stiā†µness matrices compared to the original approach, which can be implemented directly in fictitious domain finite element analysis. The approach is then extended, we believe for the first time, to the nonlinear cases of frictional boundary conditions and elasto-plastic material behaviour. The proposed formulation and procedures are validated on a number of example problems that test diā†µerent aspects of the method

    Performance modelling and analysis of software defined networking

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    Software Defined Networking (SDN) is an emerging architecture for the next-generation Internet, providing unprecedented network programmability to handle the explosive growth of Big Data driven by the popularisation of smart mobile devices and the pervasiveness of content-rich multimedia applications. In order to quantitatively investigate the performance characteristics of SDN networks, several research efforts from both simulation experiments and analytical modelling have been reported in the current literature. Among those studies, analytical modelling has demonstrated its superiority in terms of cost-effectiveness in the evaluation of large-scale networks. However, for analytical tractability and simplification, existing analytical models are derived based on the unrealistic assumptions that the network traffic follows the Poisson process which is suitable to model non-bursty text data and the data plane of SDN is modelled by one simplified Single Server Single Queue (SSSQ) system. Recent measurement studies have shown that, due to the features of heavy volume and high velocity, the multimedia big data generated by real-world multimedia applications reveals the bursty and correlated nature in the network transmission. With the aim of the capturing such features of realistic traffic patterns and obtaining a comprehensive and deeper understanding of the performance behaviour of SDN networks, this paper presents a new analytical model to investigate the performance of SDN in the presence of the bursty and correlated arrivals modelled by Markov Modulated Poisson Process (MMPP). The Quality-of-Service performance metrics in terms of the average latency and average network throughput of the SDN networks are derived based on the developed analytical model. To consider realistic multi-queue system of forwarding elements, a Priority-Queue (PQ) system is adopted to model SDN data plane. To address the challenging problem of obtaining the key performance metrics, e.g., queue length distribution of PQ system with a given service capacity, a versatile methodology extending the Empty Buffer Approximation (EBA) method is proposed to facilitate the decomposition of such a PQ system to two SSSQ systems. The validity of the proposed model is demonstrated through extensive simulation experiments. To illustrate its application, the developed model is then utilised to study the strategy of the network configuration and resource allocation in SDN networksThis work is supported by the EU FP7 ā€œQUICKā€ Project (Grant NO. PIRSES-GA-2013-612652) and the National Natural Science Foundation of China (Grant NO. 61303241)

    A simplified but equally accurate C-13 urea breath test for Helicobacter pylori

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    Tolerance of banana for fusarium wilt is associated with early H2O2 accumulation in the roots

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    Banana plants derived from a tissue culture process possess a high rate of random variations that were widely used as popular cultivars due to the new desired traits. In this study, two near-isogenic lines, one susceptible (parental Williams-8818) and the other resistant (somaclonal variation progeny Williams-8818-1 from Williams-8818) to Fusarium oxysporum f. sp. Cubense (Foc4), were inoculated with race 4 of F. oxysporum (Fox). Production of O2ā€¢āˆ’ , H2O2 and MDA, as well as changes in enzyme activities, and transcript levels of SOD and CAT in root extracts were monitored every 24 h over 4 days. The histochemical location of H2O2 was also detected. In the resistant iso-line, the accumulation of O2ā€¢āˆ’ and H2O2, and the activation of SOD occurred in the first 24 h, but activation of CAT reached its maximum only after 48 h. All changes were generally lower in the susceptible iso-line when compared to the resistant iso-line. SOD transcripts were further up-regulated until 72 h in the resistant iso-line, but not in the susceptible iso-line. CAT expression was not affected in any of the two iso-lines. This suggests that expressions of the two key genes in the antioxidant system are less suitable indicators for Foc resistance in banana. In contrast, the first ā€œoxidative burstā€ is a better indicator for different susceptibility of banana to Foc.Key words: Banana, Fusarium oxysporum, catalase, reactive oxygen species, somaclonal variation, disease resistance

    Differing coping mechanisms, stress level and anorectal physiology in patients with functional constipation

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    Aim: To investigate coping mechanisms, constipation symptoms and anorectal physiology in 80 constipated subjects and 18 controls. Methods: Constipation was diagnosed by Rome II criteria. Coping ability and anxiety/depression were assessed by validated questionnaires. Transit time and balloon distension test were performed. Results: 34.5% patients were classified as slow transit type of constipation. The total colonic transit time (56 h vs 10 h, P<0.0001) and rectal sensation including urge sensation (79 mL vs 63 mL, P = 0.019) and maximum tolerable volume (110 mL vs 95 mL, P = 0.03) differed in patients and controls. Constipated subjects had significantly higher anxiety and depression scores and lower SF-36 scores in all categories. They also demonstrated higher scores of 'monitoring' coping strategy (14Ā±6 vs 9Ā±3, P = 0.001), which correlated with the rectal distension sensation (P = 0.005), urge sensation (P=0.002), and maximum tolerable volume (P = 0.035). The less use of blunting strategy predicted slow transit constipation in both univariate (P = 0.01) and multivariate analysis (P = 0.03). Conclusion: Defective or ineffective use of coping strategies may be an important etiology in functional constipation and subsequently reflected in abnormal anorectal physiology. Ā© 2005 The WJG Press and Elsevier Inc. All rights reserved.published_or_final_versio

    An evaluation of PyloriTek test for the diagnosis of Helicobacter pylori infection in Chinese - before and after eradication therapy

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    A study on the effect of COX-2 inhibitors on gastric mucosal prostaglandin synthesis

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    Three-day lansoprazole quadruple therapy for Helicobacter pylori-positive duodenal ulcers: a randomized contolled study

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    General Hydrodynamics of He-3-a in Finite Magnetic-Fields

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