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991.
Nathan L. Harshman 《International Journal of Theoretical Physics》2007,46(8):1929-1946
The notion that elementary systems correspond to irreducible representations of the Poincaré group is the starting point for
this paper, which then goes on to discuss how a semigroup for the time evolution of unstable states and resonances could emerge
from the underlying Poincaré symmetry. Important tools in this analysis are the Clebsch-Gordan coefficients for the Poincaré
group. 相似文献
992.
In this work we derive lower bounds for the Hausdorff and fractal dimensions of the global attractor of the Sabra shell model
of turbulence in different regimes of parameters. We show that for a particular choice of the forcing term and for sufficiently
small viscosity term ν, the Sabra shell model has a global attractor of large Hausdorff and fractal dimensions proportional
to log ν −1 for all values of the governing parameter ε, except for ε =1. The obtained lower bounds are sharp, matching the upper bounds
for the dimension of the global attractor obtained in our previous work. Moreover, the complexity of the dynamics of the shell
model increases as the viscosity ν tends to zero, and we describe a precise scenario of successive bifurcations for different
parameters regimes. In the “three-dimensional” regime of parameters this scenario changes when the parameter ε becomes sufficiently
close to 0 or to 1. We also show that in the “two-dimensional” regime of parameters, for a certain non-zero forcing term,
the long-term dynamics of the model becomes trivial for every value of the viscosity.
AMS Subject Classifications: 76F20, 76D05, 35Q30 相似文献
993.
Roderich Tumulka 《Foundations of Physics》2007,37(2):186-197
In a recent paper Conway and Kochen, Found. Phys. 36, 2006, claim to have established that theories of the Ghirardi-Rimini-Weber
(RW) type, i.e., of spontaneous wave function collapse, cannot be made relativistic. On the other hand, relativistic GRW-type
theories have already been presented, in my recent paper, J. Stat. Phys. 125, 2006, and by Dowker and Henson, J. Stat. Phys.
115, 2004. Here, I elucidate why these are not excluded by the arguments of Conway and Kochen.
相似文献
994.
A parallel plate interferometer with a reflecting mirror for measuring angular displacement is proposed. A deflection angle
of a beam caused by an angular displacement is amplified by use of a reflecting mirror to increase the optical path difference
(OPD) in the plane-parallel plate, which provides high sensitivity of the phase measurement. Detection of light transmitted
through the plane-parallel plate with a position sensitive detector (PSD) enables high accurate measurement of the initial
angle of incidence to the plane-parallel plate with insensitivity to stray light. The improved parallel plate interferometer
achieves a measurement repeatability of 10−8 rad. 相似文献
995.
Phospholipid lung surfactant and nanoparticle surface toxicity: Lessons from diesel soots and silicate dusts 总被引:3,自引:0,他引:3
William E. Wallace Michael J. Keane David K. Murray William P. Chisholm Andrew D. Maynard Tong-man Ong 《Journal of nanoparticle research》2007,9(1):23-38
Because of their small size, the specific surface areas of nanoparticulate materials (NP), described as particles having at
least one dimension smaller than 100 nm, can be large compared with micrometer-sized respirable particles. This high specific
surface area or nanostructural surface properties may affect NP toxicity in comparison with micrometer-sized respirable particles
of the same overall composition. Respirable particles depositing on the deep lung surfaces of the respiratory bronchioles
or alveoli will contact pulmonary surfactants in the surface hypophase. Diesel exhaust ultrafine particles and respirable
silicate micrometer-sized insoluble particles can adsorb components of that surfactant onto the particle surfaces, conditioning
the particles surfaces and affecting their in vitro expression of cytotoxicity or genotoxicity. Those effects can be particle surface composition-specific. Effects of particle
surface conditioning by a primary component of phospholipid pulmonary surfactant, diacyl phosphatidyl choline, are reviewed
for in vitro expression of genotoxicity by diesel exhaust particles and of cytotoxicity by respirable quartz and aluminosilicate kaolin
clay particles. Those effects suggest methods and cautions for assaying and interpreting NP properties and biological activities. 相似文献
996.
V. Katchkanov J.F.W. Mosselmans S. Dalmasso K.P. ODonnell S. Hernandez K. Wang R.W. Martin O. Briot N. Rousseau G. Halambalakis K. Lorenz E. Alves 《Superlattices and Microstructures》2004,36(4-6):729
The local structure of Tm3+ ions incorporated into GaN epilayers was studied by means of Extended X-ray Absorption Fine Structure. The samples were doped either in situ during growth by Molecular Beam Epitaxy or by ion implantation of layers grown by Metal Organic Chemical Vapour Deposition. The implantation was done at ion energy of 300 keV and different nominal fluences of 3×1015, 4×1015 cm−2 and 5×1015 cm−2. The concentration of Tm in the samples studied was measured by Wavelength Dispersive X-ray analysis. For the in situ doped sample with concentration of 0.5%, and for all of the implanted samples, Tm was found on the Ga site in GaN. The ion implanted sample and an in situ doped sample with a similar concentration of Tm showed the same local structure, which suggests that the lattice site occupied by Tm does not depend on the doping method. When the average Tm concentration for in situ doped samples is increased to 1.2% and 2.0%, Tm is found to occupy the Ga substitutional site and the presence of a substantial number of Tm ions in the second coordination sphere indicates dopant clustering in the films. The formation of pure TmN clusters was found in an in situ doped sample with a dopant concentration of 3.4%. 相似文献
997.
998.
999.
Myocardial infarction results from the rupture of an atherosclerotic plaque, which occurs in response to both mechanical stress
and inflammatory processes. In order experimentally observe flow into atherosclerotic coronary artery morphologies, a novel
technique for molding realistic compliant phantom featuring injection-molded inclusions and multiple layers has been developed.
This transparent phantom allows for particle image velocimetry (PIV) flow analysis and can supply experimental data to validate
computational fluid dynamics algorithms and hypothesis. 相似文献
1000.
A new optical technique based on real time holographic interferometry in true colors has been implemented around the transonic
wind tunnel of the ONERA-Lille center to analyze 2D unsteady wake flows. Tests realized in color interferometry, real time
and double exposure, use simultaneously three wavelengths of a continuous waves laser (argon and krypton mixed) and holograms
are recorded on silver-halide single-layer panchromatic Slavich PFG03c plates. The very principle of real-time true color
holographic interferometry uses three primary wavelengths (red, green and blue) to record, under no-flow conditions, the interference
among the three measurement beams and the three reference beams simultaneously on a single reference hologram. After the holographic
plate is developed, it is placed on the test setup again in the position it occupied during exposure and the hologram is illuminated
again by the three reference beams and three measurement beams. A flat, uniform color can then be observed behind the hologram.
So a horizontal, vertical, or even circular fringe pattern can be formed and the achromatic central fringe can be made out
very clearly. The single color is used to determine the path difference zero on the interferograms. The flow studied was the
unsteady flow downstream of a cylinder placed crosswise in the test section. A sequence of hundred interferograms was recorded
on the flow around the cylinder at Mach 0.37. The vortex formation and dissipation phases can be seen very clearly, along
with the fringe beat to either side of the cylinder. 相似文献