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971.
Carlson JW 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2000,147(2):210-216
A continuous transformation of an RF waveform with a modified Korteweg-de Vries equation or generalization can be used to adjust the phase behavior of a selective excitation pulse while preserving the magnitude behavior of the spin response. This transformation has applications in removing or adding to the nonlinear phase properties of a selected region. 相似文献
972.
Woelk K Zwank BL Trautner P Lehnhof E Bargon J Klingler RJ Gerald RE Rathke JW 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2000,145(2):276-290
A finite-difference approach has been developed for precisely determining diffusion coefficient and T1 relaxation time in fluid samples analyzed by magnetization-grating rotating-frame imaging (MAGROFI) with either a surface coil or a toroid cavity detector (TCD). This approach avoids shortcomings of phenomenologically based approximations, such as neglect of sample geometries with singularities at the confines of the sample volume, and accounts for the diffusive edge enhancement observed in fluid imaging. Error limits are discussed. The new method has been applied to the determination of the self-diffusion coefficient for MAGROFI experiments using TCDs filled with acetone. 相似文献
973.
974.
为了既节省稀有昂贵的冰洲石晶体材料,又实现偏振光的大剪切差输出,采用冰洲石晶体与光学玻璃组合的方法,设计了一种新型平行分束偏光镜。该棱镜的前后半块分别为ZBaF3玻璃和冰洲石晶体,由大折射率液态胶合剂溴代萘胶合而成。实验测试表明:该棱镜透射的2束平行光的消光比,o光可达10-5;尽管受到光学玻璃的影响,e光的消光比仍优于10-3;透射比均与纯冰洲石晶体材料的棱镜基本相当。理论分析表明:该棱镜自身结构带来的性能影响在一定情况下完全可以忽略,因此具有较好的应用前景。 相似文献
975.
976.
C. Garcıa-Recio J. Nieves L. L. Salcedo 《The European Physical Journal A - Hadrons and Nuclei》2007,31(4):540-542
Starting from a consistent SU(6) extension of the Weinberg-Tomozawa (WT) meson-baryon chiral Lagrangian ( Phys. Rev. D 74, 034025 (2006)), we study the s-wave meson-baryon resonances in the strangeness S = - 3 and negative-parity sectors. Those resonances are generated by solving the Bethe-Salpeter equation with the WT interaction
used as kernel. The considered mesons are those of the 35-SU(6)-plet, which includes the pseudoscalar (PS) octet of pions and the vector (V) nonet of the rho-meson. For baryons we consider
the 56-SU(6)-plet, made of the 1/2+ octet of the nucleon and the 3/2+ decuplet of the Delta. Quantum numbers I(J
P) = 0(3/2-) are suggested for the experimental resonances Ω
*(2250)- and Ω
*(2380)-. Among other, resonances with I = 1 are found, which minimal quark content is sssˉl', being s the strange quark and l, l' any of the the light up or down quarks. A clear signal for such a pentaquark would be a baryonic resonance with strangeness -3 and electric charge -2 or
0, in proton charge units. We suggest looking for K
-
Ξ
- resonances with masses around 2100 and 2240MeV in the sector 1(1/2-), and for π
±
Ω
- and K
-
Ξ
*- resonances with masses around 2260MeV in the sector 1(3/2-). 相似文献
977.
A. Wilmer T. D. Frank P. J. Beek R. Friedrich 《The European Physical Journal B - Condensed Matter and Complex Systems》2007,60(2):203-215
In this work a method is developed for analyzing time series of
periodically driven stochastic systems involving time-delayed feedback.
The proposed data-analysis method yields
dynamical models in terms of stochastic delay differential equations. On
the basis of these dynamical models differential effects of driving
forces and time-delayed feedback forces can be identified. 相似文献
978.
D. Antonucci D. de Ceglia A. D’Orazio M. De Sario V. Marrocco V. Petruzzelli F. Prudenzano 《Optical and Quantum Electronics》2007,39(4-6):353-360
In this paper we discuss the conditions to obtain the enhancement of second harmonic generation in a two-dimensional circular
photonic crystal AlGaAs cavity. The photonic crystal circular cavity offers the possibility of having high-Q resonance modes
with respect to those obtained with other types of photonic crystal lattices. The crystallographic cut of the AlGaAs provides
a strong nonlinear coupling between a transverse-magnetic (TM) polarized resonant mode at the fundamental wavelength and a
transverse-electric (TE) polarized resonant mode at second harmonic wavelength. The double resonance condition leads to a
strong improvement of the second harmonic generation process. A preliminary linear analysis has been performed by using the
finite-difference time-domain method, which includes the dispersive response of the material, modeled using the well-known
one-pole pair Lorentzian function. 相似文献
979.
V. V. Varlamov 《International Journal of Theoretical Physics》2007,46(4):741-805
A construction of relativistic wave equations on the homogeneous spaces of the Poincaré group is given for arbitrary spin
chains. Parametrizations of the field functions and harmonic analysis on the homogeneous spaces are studied. It is shown that
a direct product of Minkowski space time and two-dimensional complex sphere is the most suitable homogeneous space for the
physical applications. The Lagrangian formalism and field equations on the Poincaré and Lorentz groups are considered. A boundary
value problem for the relativistically invariant system is defined. General solutions of this problem are expressed via an
expansion in hyperspherical functions defined on the complex two-sphere.
PACS numbers: 02.30.Gp, 02.60.Lj, 03.65.Pm, 12.20.-m 相似文献
980.
Alexander I. Nosich Elena I. Smotrova Svetlana V. Boriskina Trevor M. Benson Phillip Sewell 《Optical and Quantum Electronics》2007,39(15):1253-1272
Research into microdisk lasers demonstrates new achievements both in the technology and in the associated physical effects
and applications. Melting and rounding of the disk edge boosts the Q-factors due to improved surface smoothness. In-plane
cavity shape is widely used as a design instrument. Optimal shaping of pumped area lowers the threshold power. Photonic molecules
made of several microdisks as “photonic atoms” show lasing at several closely spaced frequencies. A microdisk with a single
quantum dot as an active region is considered as the most promising system for realisation of a single photon emitter necessary
for quantum computing. These new effects and devices can be simulated with accurate numerical techniques, developed recently
for “warm-cavity” linear modelling, that are able to bring a new vision of the physics of lasing. 相似文献