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1.
JOSEF MÁLEK JINDŘICH NEČAS K. R. RAJAGOPAL 《Archive for Rational Mechanics and Analysis》2002,165(3):243-269
To describe the flows of fluids over a wide range of pressures, it is necessary to take into account the fact that the viscosity
of the fluid depends on the pressure. That the viscosity depends on the pressure has been verified by numerous careful experiments.
While the existence of solutions local-in-time to the equations governing the flows of such fluids are available for small,
special data and rather unrealistic dependence of the viscosity on the pressure, no global existence results are in place.
Our interest here is to establish the existence of weak solutions for spatially periodic three-dimensional flows that are
global in time, for a large class of physically meaningful viscosity-pressure relationships.
(Accepted May 1, 2002) Published online November 15, 2002
Communicated by S. S. ANTMAN 相似文献
2.
A waveguide in integrated optics is defined by its refractiveindex. The guide is assumed to be invariant in the propagationdirection while in the transverse direction it is supposed tobe a compact perturbation of an unbounded stratified medium.We are interested in the modes guided by this device, whichare waves with a transverse energy confined in a neighbourhoodof the perturbation. Our goal is to analyse the existence of such guided modes. Underthe assumptions of weak guidance the problem reduces to a two-dimensionaleigenvalue problem for a scalar field. The associated operatoris unbounded, selfadjoint, and bounded from below. Its spectrumconsists of the discrete spectrum corresponding to the guidedmodes and of the essential spectrum corresponding to the radiationmodes. We present existence results of guided modes and an asymptoticstudy at high frequencies, which shows that contrarily to thecase of optical fibers, the number of guided modes can remainbounded. The major tools are the min-max principle and comparisonof results between different eigenvalue problems. The originalityof the present study lies in the stratified character of theunbounded reference medium. 相似文献
3.
Jay Jin Saranya Kittanakom Victoria Wong Beverly AS Reyes Elisabeth J Van Bockstaele Igor Stagljar Wade Berrettini Robert Levenson 《BMC neuroscience》2010,11(1):33
Background
Opioid agonist drugs produce analgesia. However, long-term exposure to opioid agonists may lead to opioid dependence. The analgesic and addictive properties of opioid agonist drugs are mediated primarily via the mu-opioid receptor (MOR). Opioid agonists appear to alter neuronal morphology in key brain regions implicated in the development of opioid dependence. However, the precise role of the MOR in the development of these neuronal alterations remains elusive. We hypothesize that identifying and characterizing novel MOR interacting proteins (MORIPs) may help to elucidate the underlying mechanisms involved in the development of opioid dependence. 相似文献4.
MF Miller IA Franchi AS Sexton CT Pillinger 《Rapid communications in mass spectrometry : RCM》1999,13(13):1211-1217
The use of infrared laser-assisted fluorination to release oxygen from milligram quantities of silicates or other oxide mineral grains is a well-established technique. However, relatively few studies have reported the optimisation of this procedure for oxygen-17 isotope measurements. We describe here details of an analytical system using infrared (10 μm) laser-assisted fluorination, in conjunction with a dual inlet mass spectrometer of high resolving power ( approximately 250) to provide (17)O and (18)O oxygen isotope measurements from 0.5-2 mg of silicates or other oxide mineral grains. Respective precisions (1) of typically 0.08 and 0.04 per thousand are obtained for the complete analytical procedure. Departures from the mass-dependent oxygen isotope fractionation line are quantified by Delta(17)O; our precision (1) of such measurements on individual samples is shown to be +/-0.024 per thousand. In turn, this permits the offset between parallel, mass-dependent fractionation lines to be characterised to substantially greater precision than has been possible hitherto. Application of this system to investigate the (17)O versus (18)O relationship for numerous terrestrial whole-rock and mineral samples, of diverse geological origins and age, indicates that the complete data set may be described by a single, mass-dependent fractionation line of slope 0.5244+/- 0.00038 (standard error). Copyright 1999 John Wiley & Sons, Ltd. 相似文献
5.
We examine a local realist bound in the case of a one-atom micromaser. It is shown that such a bound is violated using a simplified
treatment of the micromaser. We consider the effect of dissipation in a proposed experiment with the real micromaser. It is
seen that the magnitude of violation of a Bell-type inequality depends significantly on the cavity parameters. 相似文献
6.
The scope of the palladium-catalyzed silylation of aryl halides with triethoxysilane has been expanded to include aryl bromides. A more general Pd(0) catalyst/ligand system has been developed that activates bromides and iodides: palladium(0) dibenzylideneacetone (Pd(dba)(2)) is activated with 2-(di-tert-butylphosphino)biphenyl (Buchwald's ligand) (1:2 mol ratio of Pd/phosphine). Electron-rich para- and meta-substituted aryl halides (including unprotected aniline and phenol derivatives) undergo silylation to form the corresponding aryltriethoxysilane in fair to excellent yield; however, ortho-substituted aryl halides failed to be silylated. 相似文献
7.
Manoso AS Ahn C Soheili A Handy CJ Correia R Seganish WM Deshong P 《The Journal of organic chemistry》2004,69(24):8305-8314
General reaction conditions for the synthesis of aryl(trialkoxy)silanes from aryl Grignard and lithium reagents and tetraalkyl orthosilicates (Si(OR)(4)) have been developed. Ortho-, meta-, and para-substituted bromoarenes underwent efficient metalation and silylation at low temperature to provide aryl siloxanes. Mixed results were obtained with heteroaromatic substrates: 3-bromothiophene, 3-bromo-4-methoxypyridine, 5-bromoindole, and N-methyl-5-bromoindole underwent silylation in good yield, whereas a low yield of siloxane was obtained from 2-bromofuran, and 2-bromopyridine failed to give silylated product. The synthesis of siloxanes via organolithium and magnesium reagents was limited by the formation of di- and triarylated silanes (Ar(2)Si(OR)(2) and Ar(3)SiOR, respectively) and dehalogenated (Ar-H) byproducts. Silylation at low temperature gave predominantly monoaryl siloxanes, without requiring a large excess of the electrophile. Optimal reaction conditions for the synthesis of siloxanes from aryl Grignard reagents entailed addition of arylmagnesium reagents to 3 equiv of tetraethyl- or tetramethyl orthosilicate at -30 degrees C in THF. Aryllithium species were silylated using 1.5 equiv of tetraethyl- or tetramethyl orthosilicate at -78 degrees C in ether. 相似文献
8.
An analytical iterative procedure has been established to determine the amplitude of a laser beam propagating through an active
medium. The treatment is valid for both homogeneous and inhomogeneous broadening, and for arbitrary inhomogeneities of the
parameters characterizing the active medium, namely, the refractive index, the small-signal gain and the saturation intensity.
After a supplementary approximation, a thin-sheet gain approach is derived from the first iteration. The formalism enables
us to provide analytical criteria for evaluating both the accuracy of each iteration and the propagation distances for which
the thin-sheet solution can be used.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
9.
MARTI´NEZ C. Encinas-Sanz F. Serna J. MEJI´AS P. M. MARTI´NEZ-HERRERO R. 《Optical and Quantum Electronics》1997,29(9):923-931
A simple analytical model is proposed to describe the transversal spatial structure of a tridimensional rotationally symmetric
pulsed beam. The spatial behaviour of the pulse amplitude is shown to be linked to its (measurable) second- and higher-order
intensity moments, namely, beam width, quality parameter and kurtosis. As an illustrative experimental example, this model
has been applied to high-quality TEA CO2 laser pulses.
This revised version was published online in November 2006 with corrections to the Cover Date. 相似文献
10.