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31.
We present numerical simulation results of the quasi-static magnetohydrodynamic (MHD) flow in a toroidal duct of square cross-section with insulating Hartmann walls and conducting side walls. Both laminar and turbulent flows are considered. In the case of steady flows, we present a comprehensive analysis of the secondary flow. It consists of two counter-rotating vortex cells, with additional side wall vortices emerging at sufficiently high Hartmann number. Our results agree well with existing asymptotic analysis. In the turbulent regime, we make a comparison between hydrodynamic and MHD flows. We find that the curvature induces an asymmetry between the inner and outer side of the duct, with higher turbulence intensities occurring at the outer side wall. The magnetic field is seen to stabilize the flow so that only the outer side layer remains unstable. These features are illustrated both by a study of statistically averaged quantities and by a visualization of (instantaneous) coherent vortices.  相似文献   
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Background  

Our group previously demonstrated that a DNA plasmid encoding the mycobacterial 65-kDa heat shock protein (DNA-HSP65) displayed prophylactic and therapeutic effect in a mice model for tuberculosis. This protection was attributed to induction of a strong cellular immunity against HSP65. As specific immunity to HSP60 family has been detected in arthritis, multiple sclerosis and diabetes, the vaccination procedure with DNA-HSP65 could induce a cross-reactive immune response that could trigger or worsen these autoimmune diseases.  相似文献   
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Inelastic scattering induces dephasing in mesoscopic systems. An analysis of previous models to simulate inelastic scattering in such systems is presented and a relatively new model based on wave attenuation is introduced. The problem of Aharonov-Bohm (AB) oscillations in conductance of a mesoscopic ring is studied. We show that the conductance is symmetric under flux reversal and the visibility of AB oscillations decays to zero as a function of the incoherence parameter, signaling dephasing. Further the wave attenuation model is applied to a fundamental problem in quantum mechanics, that of the conditional (reflection/transmission) times spent in a given region of space by a quantum particle before scattering off from that region.  相似文献   
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Suppose that a consistent one-step numerical method of orderr is applied to a smooth system of ordinary differential equations.Given any integer m 1, the method may be shown to be of orderr + m as an approximation to a certain modified equation. Ifthe method and the system have a particular qualitative propertythen it is important to determine whether the modified equationsinherit this property. In this article, a technique is introducedfor proving that the modified equations inherit qualitativeproperties from the method and the underlying system. The techniqueuses a straightforward contradiction argument applicable toarbitrary one-step methods and does not rely on the detailedstructure of associated power series expansions. Hence the conclusionsapply, but are not restricted, to the case of Runge-Kutte methods.The new approach unifies and extends results of this type thathave been derived by other means: results are presented forintegral preservation, reversibility, inheritance of fixed points.Hamiltonian problems and volume preservation. The techniquealso applies when the system has an integral that the methodpreserves not exactly, but to order greater than r. Finally,a negative result is obtained by considering a gradient systemand gradient numerical method possessing a global property thatis not shared by the associated modified equations.  相似文献   
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We have previously shown that the rhodacyanine dye, Rhodac, exhibits a potent photocytotoxic activity in HeLa cells. In this study several aspects of the photobiological activity of Rhodac were further examined. Rhodac displayed no selective cytotoxicity toward several malignant cell lines after photosensitization (3.6 J/cm2), although HeLa cells were found to be the most sensitive. Interestingly, MCF-7/Adr cells, a multidrug-resistant subline, were less sensitive to the antiproliferative effect of photoactivated Rhodac. The subcellular localization, as revealed by confocal laser microscopy, demonstrated that the dye was mainly concentrated in the cytosolic membranes of the perinuclear region. The Rhodac-induced inhibition of HeLa cell proliferation after light exposure was found to be strictly oxygen dependent. In addition, photoactivated Rhodac induced poly(adenosine 5' diphosphate-ribose)polymerase cleavage, caspase-3 activation and apoptosis in HeLa cells. In the current work it was further demonstrated that Rhodac binds specifically to high-density lipoproteins and low-density lipoproteins, while no binding was observed to very low-density and heavy proteins. To sum up, our results show that Rhodac is an interesting and potent photosensitizer. Further in vivo experiments are required to elucidate whether the lipoprotein binding leads to a selective uptake of Rhodac in tumor cells and to address its efficacy in photodynamic therapy.  相似文献   
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Much is known about the connection between the growth and decayof subharmonic functions. The results indicate that there isa general principle: asubharmonic function cannot decay ‘toofast’ relative to its growth.Three theorems are provedwhich, together with work previously published elsewhere, givea fairly complete account of how this principle works out fora subharmonic function having extremal decay along a ray. 1991Mathematics Subject Classification: 30D20, 31A05.  相似文献   
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