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941.
It is shown that the approach proposed by Lax et al. [Phys. Rev. A 11, 1365 (1975)] for studying the propagation of an electromagnetic beam beyond the paraxial approximation can be efficiently employed evenwhen the beam under consideration presents a very nonparaxial character. The method that we present consists of applying a nonlinear resummation scheme, the so-called delta transformation, to the divergent perturbative series arising from the Lax scheme. Numerical results pertinent to the evaluation of transverse and longitudinal components of the electric field are presented for the particular case of vectorial Gaussian beams, showing the effectiveness of the method. 相似文献
942.
943.
The effect of fluctuations in the classical control parameters on the Berry phase of a spin 1/2 interacting with an adiabatically cyclically varying magnetic field is analyzed. It is explicitly shown that in the adiabatic limit dephasing is due to fluctuations of the dynamical phase. 相似文献
944.
Discretization of phase space usually nullifies chaos in dynamical systems. We show that if randomness is associated with discretization dynamical chaos may survive and be indistinguishable from that of the original chaotic system, when an entropic, coarse-grained analysis is performed. Relevance of this phenomenon to the problem of quantum chaos is discussed. 相似文献
945.
946.
We consider the paraxial model for a nonlinear resonator with a saturable absorber beyond the mean-field limit. For accessible parametric domains we observe total radiation confinement and the formation of 3D localized bright structures. Different from freely propagating light bullets, here the self-organization proceeds from the resonator feedback, combined with diffraction and nonlinearity. Such "cavity" light bullets can be independently excited and erased by appropriate pulses, and once created, they endlessly travel the cavity round-trip. 相似文献
947.
Pica Ciamarra M Lara AH Lee AT Goldman DI Vishik I Swinney HL 《Physical review letters》2004,92(19):194301
Our experiments and molecular dynamics simulations on a projectile penetrating a two-dimensional granular medium reveal that the mean deceleration of the projectile is constant and proportional to the impact velocity. Thus, the time taken for a projectile to decelerate to a stop is independent of its impact velocity. The simulations show that the probability distribution function of forces on grains is time independent during a projectile's deceleration in the medium. At all times the force distribution function decreases exponentially for large forces. 相似文献
948.
A short field campaign was performed in the outskirts of Rome at four sites located pretty along the four rose wind directions to city centre. Both chlorinated (PCB and PCDD/F) and non-chlorinated (n-alkanes, PAH, nitrated-PAH, n-alkanoic acids) organic micropollutants were investigated for their contents in the atmosphere. Concentrations reached by these pollutants in the outskirts were compared to those found in downtown Rome, both inside and outside of its largest city garden. Although concentrations of organic pollutants found in the outskirts were quite low, however they seemed enough high to induce some health risk in humans. Rural sites were less affected than industrial and waste disposal/treatment areas. 相似文献
949.
Giurlani Walter Sergi Luca Crestini Eugenio Calisi Nicola Poli Federico Soavi Francesca Innocenti Massimo 《Journal of Solid State Electrochemistry》2022,26(1):85-95
Journal of Solid State Electrochemistry - The electrochemical behaviour of steel, copper, and titanium current collectors was studied in aqueous solutions of lithium... 相似文献
950.
Dr. Martina Lippi Andrea Murelli Prof. Patrizia Rossi Prof. Paola Paoli Prof. Dr. Massimo Cametti 《Chemistry (Weinheim an der Bergstrasse, Germany)》2022,28(26):e202200420
One-dimensional (1D) coordination polymers (CPs) featuring three different topologies, comprising zig-zag, ribbon-like and poly-[n]-catenane structures, were obtained by reaction of Hg(II) ions with a novel bispidine ligand L3 , and structurally characterized by SC- and P-XRD methods. The CPs obtained in the form of microcrystalline powders were tested for their ability to undergo solvent adsorption and exchange by P-XRD and 1H NMR spectroscopy. The extent of their dynamic behavior was then correlated to their structural features, highlighting the role of interchain interactions established among their constituting linear arrays. Zig-zag CPs proved to be resilient to external chemical stimuli, while they differently respond to thermal treatments, depending on the solvent originally included within the CP. In the case of polycatenated structures, we observed transformations where the original topology was maintained upon guest exchange, but also cases where it changed to zig-zag, even under solid/vapor conditions (i. e., no complete dissolution of the CP). Given the presence of linear interconnected 1D channels, 3 ⋅ ClBz-polycatenanePwd is also able to trap volatile guests such as n-hexane when exposed to its vapors. 相似文献