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991.
We solve the general problem of mixing of electromagnetic and scalar or pseudoscalar fields coupled by axion-type interactions
L
int = g
ϕ
ϕε
μναβ
F
μν
F
αβ
. The problem depends on several dimensionful scales, including the magnitude and direction of background magnetic field,
the pseudoscalar mass, plasma frequency, propagation frequency, wave number, and finally the pseudoscalar coupling. We apply
the results to the first consistent calculations of the mixing of light propagating in a background magnetic field of varying
directions, which show a great variety of fascinating resonant and polarization effects.
相似文献
992.
The potential role of ultrasound in differentiating solid and cystic swellings of the true vocal fold 总被引:3,自引:0,他引:3
John S. Rubin Stuart Lee John McGuinness Ian Hore David Hill Leslie Berger 《Journal of voice》2004,18(2):231-235
This study was designed to investigate the potential role of ultrasound in the diagnosis of cysts of the true vocal fold. Materials and Methods: Grayscale ultrasound of the larynx was carried out in 29 patients with a swelling of the true vocal fold and dysphonia. The findings were then compared with those at subsequent microlaryngoscopy, in the majority of cases. Results and Conclusions: Whereas preoperative laryngeal ultrasound correctly predicted the surgical findings of a cystic lesion in only 5 of 11 cases, it correctly identified that no cyst was present in 15 of 16 instances when this had been queried. This study suggests that ultrasound may have some role in investigation of unilateral vocal fold pathology, but that further fine-tuning of the technique may be necessary. 相似文献
993.
Culling JF Hawley ML Litovsky RY 《The Journal of the Acoustical Society of America》2004,116(2):1057-1065
Three experiments investigated the roles of interaural time differences (ITDs) and level differences (ILDs) in spatial unmasking in multi-source environments. In experiment 1, speech reception thresholds (SRTs) were measured in virtual-acoustic simulations of an anechoic environment with three interfering sound sources of either speech or noise. The target source lay directly ahead, while three interfering sources were (1) all at the target's location (0 degrees,0 degrees,0 degrees), (2) at locations distributed across both hemifields (-30 degrees,60 degrees,90 degrees), (3) at locations in the same hemifield (30 degrees,60 degrees,90 degrees), or (4) co-located in one hemifield (90 degrees,90 degrees,90 degrees). Sounds were convolved with head-related impulse responses (HRIRs) that were manipulated to remove individual binaural cues. Three conditions used HRIRs with (1) both ILDs and ITDs, (2) only ILDs, and (3) only ITDs. The ITD-only condition produced the same pattern of results across spatial configurations as the combined cues, but with smaller differences between spatial configurations. The ILD-only condition yielded similar SRTs for the (-30 degrees,60 degrees,90 degrees) and (0 degrees,0 degrees,0 degrees) configurations, as expected for best-ear listening. In experiment 2, pure-tone BMLDs were measured at third-octave frequencies against the ITD-only, speech-shaped noise interferers of experiment 1. These BMLDs were 4-8 dB at low frequencies for all spatial configurations. In experiment 3, SRTs were measured for speech in diotic, speech-shaped noise. Noises were filtered to reduce the spectrum level at each frequency according to the BMLDs measured in experiment 2. SRTs were as low or lower than those of the corresponding ITD-only conditions from experiment 1. Thus, an explanation of speech understanding in complex listening environments based on the combination of best-ear listening and binaural unmasking (without involving sound-localization) cannot be excluded. 相似文献
994.
John F. Gunion 《Pramana》2004,62(2):283-305
I summarize the basic theory and selected phenomenology for the Higgs boson(s) of the standard model, the minimal supersymmetric
model and some extensions thereof, including the next-to-minimal supersymmetric model. 相似文献
995.
Constantin LA Pitarke JM Dobson JF Garcia-Lekue A Perdew JP 《Physical review letters》2008,100(3):036401
We resolve the long-standing controversy over the metal surface energy: Density-functional methods that require uniform-electron-gas input agree with each other, but not with high-level correlated calculations such as Fermi hypernetted chain and diffusion Monte Carlo calculations that predict the uniform-gas correlation energy. Here we apply the inhomogeneous Singwi-Tosi-Land-Sj?lander method, and find that the density functionals are indeed reliable (because the surface energy is bulklike). Our work also vindicates the use of uniform-gas-based nonlocal kernels in time-dependent density-functional theory. 相似文献
996.
The Vlasov equation governs the evolution of the single-particle probability distribution function (PDF) for a system of particles interacting without dissipation. Its singular solutions correspond to the individual particle motions. The operation of taking the moments of the Vlasov equation is a Poisson map. The resulting Lie-Poisson Hamiltonian dynamics of the Vlasov moments is found to be integrable is several cases. For example, the dynamics for coasting beams in particle accelerators is associated by a hodograph transformation to the known integrable Benney shallow-water equation. After setting the context, the Letter focuses on geodesic Vlasov moment equations. Continuum closures of these equations at two different orders are found to be integrable systems whose singular solutions characterize the geodesic motion of the individual particles. 相似文献
997.
Anthony D. Appelhans John E. Olson David A. Dahl Michal B. Ward Troy A. Robinson James E. Delmore 《Journal of Radioanalytical and Nuclear Chemistry》2018,315(2):207-209
A new isotope separator has been designed, constructed, and put into routine operation for separation of 133Xe providing a major advancement and significant cost reduction in preparation of this radioactive isotope. The design features and advantages are discussed that expedite high purity separation of relatively small quantities of this isotope. These advantages could be easily used to expedite separation of other shorter-lived radioactive isotopes. 相似文献
998.
Despotopulos John D. Kmak Kelly N. Shaughnessy Dawn A. 《Journal of Radioanalytical and Nuclear Chemistry》2018,318(2):985-989
Journal of Radioanalytical and Nuclear Chemistry - A new procedure has been developed for isolating no-carrier-added 197m,gHg from 20 to 25&;nbsp;MeV α-particle irradiations of high purity... 相似文献
999.
1000.
Cytochrome P450 119 Compounds I Formed by Chemical Oxidation and Photooxidation Are the Same Species
Dr. Zhi Su Dr. John H. Horner Prof. Dr. Martin Newcomb 《Chemistry (Weinheim an der Bergstrasse, Germany)》2019,25(61):14015-14020
Compound I from cytochrome P450 119 prepared by the photooxidation method involving peroxynitrite oxidation of the resting enzyme to Compound II followed by photooxidation to Compound I was compared to Compound I generated by m-chloroperoxybenzoic acid (MCPBA) oxidation of the resting enzyme. The two methods gave the same UV/Visible spectra, the same products from oxidations of lauric acid and palmitic acid and their (ω-2,ω-2,ω-3,ω-3)-tetradeuterated analogues, and the same kinetics for oxidations of lauric acid and caprylic acid. The experimental identities between the transients produced by the two methods leave no doubt that the same Compound I species is formed by the two methods. 相似文献