Elastic Wave Scattering and Dynamic Stress Concentrations in Stretching Thick Plates with Two Cutouts by Using the Refined Dynamic Theory

Based on the refined dynamic equation of stretching plates, the elastic tension–compression wave scattering and dynamic stress concentrations in the thick plate with two cutouts are studied. In view of the problem that the shear stress is automatically satisfied under the free boundary condition, the generalized stress of the first-order vanishing moment of shear stress is considered. The numerical results indicate that, as the cutout is thick, the maximum value of the dynamic stress factor obtained using the refined dynamic theory is 19% higher than that from the solution of plane stress problems of elastic dynamics

Document distribution algorithm for load balancing on an extensible Web server architecture

Access latency and load balancing are the two main issues in the design of clustered Web server architecture for achieving high performance. We propose a novel document distribution algorithm for load balancing on a cluster of distributed Web servers. We group Web pages that are likely to be accessed during a request session into a migrating unit, which is used as the basic unit of document placement. A modified binning algorithm is developed to distribute the migrating units among the Web servers to fulfil the load balancing. We also present a redirection mechanism, which makes use of a migrating unit's property, to reduce the cost of request redirections. The distribution of Web documents would be recomputed periodically to adapt to the changes in client request patterns and system configuration. Simulation results show that our solution can reduce the amount of request redirection and document migration, and it can distribute workload properly among Web servers.published_or_final_versio

A unified concurrency control algorithm for distributed database systems

We present a unified concurrency-control algorithm for distributed database systems in which each transaction may choose its own concurrency control protocol. Specifically, they integrate two-phase locking, timestamp ordering, and precedence agreement into one unified concurrency-control scheme. They show the correctness of the scheme and study the problem of selecting the best protocol for each transaction to optimize system performance.published_or_final_versio

Isolation of 10 cyclosporine metabolites from human bile

Ten metabolites of cyclosporine were isolated from the ethyl ether extract of bile from four liver transplant patients receiving cyclosporine. Two of the metabolites were unique and previously unidentified. Liquid-liquid partitioning into diethyl ether with subsequent defatting with n-hexane was used for the initial extraction form bile. Separation of the individual metabolites (A-J) was performed using a Sephadex LH-20 column and a gradient high performance liquid chromatographic method. The molecular weights of the isolated metabolites were determined by fast atom bombardment/mass spectrometry. Gas chromatography with mass spectrometic amino acid analysis was also used to identify the amino acid composition and the hydroxylation position of metabolites A, B, C, D, and G. Proton nuclear magnetic resonance spectra were utilized to disinguish the chemical shifts of N-CH3 singlets and NH doublets of metabolites A, B, C, and D. Metabolites A, E, F, H, I, and J were reported previously in human urine and animal bile. Metabolites C and D are dihydroxylated compounds which cannot be clearly described as previously isolated compounds. Metabolites B and G are novel metabolites with a mass fragment which corresponded to a loss of 131 Da from the protonated molecular ion (MH+) in the fast atom bombardment/mass spectrometry, suggesting that the double bond in amino acid 1 has been modified. Metabolites B and G were primarily isolated from the bile of one of the liver transplant patients which contained abnormally high concentrations of these two metabolites. The method described is an efficient procedure for isolating milligram quantities of the major metabolites with greater than 95% purity

Assessment of diastolic dysfunction by tissue Doppler echocardiography in patients with heart failure

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The leading-edge vortex of swift wing-shaped delta wings

Recent investigations on the aerodynamics of natural fliers have illuminated the significance of the leading-edge vortex (LEV) for lift generation in a variety of flight conditions. A well-documented example of an LEV is that generated by aircraft with highly swept, delta-shaped wings. While the wing aerodynamics of a manoeuvring aircraft, a bird gliding and a bird in flapping flight vary significantly, it is believed that this existing knowledge can serve to add understanding to the complex aerodynamics of natural fliers. In this investigation, a model non-slender delta-shaped wing with a sharp leading edge is tested at low Reynolds number, along with a delta wing of the same design, but with a modified trailing edge inspired by the wing of a common swift Apus apus. The effect of the tapering swift wing on LEV development and stability is compared with the flow structure over the unmodified delta wing model through particle image velocimetry. For the first time, a leading-edge vortex system consisting of a dual or triple LEV is recorded on a swift wing-shaped delta wing, where such a system is found across all tested conditions. It is shown that the spanwise location of LEV breakdown is governed by the local chord rather than Reynolds number or angle of attack. These findings suggest that the trailing-edge geometry of the swift wing alone does not prevent the common swift from generating an LEV system comparable with that of a delta-shaped wing

Sensitivity of activated human lymphocytes to cyclosporine and its metabolites

Alloreactive T cells generated as clones from mixed lymphocyte cultures, or propagated from heart or liver transplant biopsies, were tested for secondary proliferation measured in the primed lymphocyte test in the presence of Cyclosporine A and metabolites fractionated from human bile. Significant differences were observed in Cyclosporine A sensitivity between various cell cultures ranging as high as 100-fold. The liver is the primary site of Cyclosporine A metabolism, which yields a number of hydroxylated and N-dimethylated derivatives that are eventually secreted into the bile. Bile was collected from adult liver transplant patients on Cyclosporine A therapy and following extraction with diethyl ether, separated by high pressure liquid chromatography. Thirteen fractions were tested for their effect on lymphocyte proliferation in concanavalin A activation, mixed lymphocyte cultures and primed lymphocyte test assays. The strongest immunosuppressive effect was found with fraction 8, which contained metabolite M17, which has a single hydroxylation in position 1. Only three other fractions 9, 10, and 13, which contained metabolites M1, M18, and M21, respectively, exhibited immunosuppressive activity, albeit much lower than that of Cyclosporine A. Differences in Cyclosporine A sensitivity among alloreactive T cells followed similar patterns with Cyclosporius A metabolites. Thus, the assessment of the Cyclosporine A effect must consider differences in drug sensitivity of lymphocytes involved in transplant immunity and the generation of metabolites with immunosuppressive activity. © 1988

Holonomic quantum computation using rf superconducting quantum interference devices coupled through a microwave cavity

We propose a different scheme to realize holonomic quantum computation with rf superconducting quantum interference device (SQUID) qubits in a microwave cavity. In this scheme associated with the non-Abelian holonomies, the single-qubit gates and a two-qubit controlled-PHASE gate as well as a controlled-NOT gate can be easily constructed by tuning adiabatically the Rabi frequencies of classical microwave pulses coupled to the SQUIDs. The fidelity of these gates is estimated to be possibly higher than 90% with the current technology. © 2005 The American Physical Society.published_or_final_versio

Impact of Secondhand Smoke Exposure on Smoking Cessation in Cardiac Patients

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Plasma adrenomedullin level in patients with heart failure is related to systolic but not diastolic dysfunction

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