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1.
We derive an expression for the harmonic signal from nonadiabatically aligned molecules that accounts for both electronic and rotational motions. We identify a single approximation, which converts the expression into a physically transparent and computationally convenient form. Our analytical result gives explicitly the time dependence of the harmonic spectra, thus explaining the observations of a class of recent experiments. Moreover, it points to new opportunities for generating insights into the structure and dynamics of molecular systems through harmonic generation experiments from aligned molecules. This includes information regarding the rotational and electronic dynamics of isolated systems, as well as regarding the decoherence and relaxation in molecules subject to a dissipative environment. 相似文献
2.
Modulation instability can be used to convert a continuous light wave into a train of pulses on a constant background. It is a longstanding discussion whether these pulses can be converted into solitons. We clarify the situation by using a more general mathematical context, invoking the Akhmediev breather, Peregrine soliton and Kuznetsov-Ma soliton solutions of the wave equation, and suggest the use of a Mach–Zehnder interferometer to remove the background. Expressions for the pulse widths and peak powers thus obtained are presented, and their soliton content is determined. It turns out that more than 95 % of each pulse’s energy can be converted to a soliton. 相似文献
3.
Travel and tourism: Into a complex network 总被引:4,自引:0,他引:4
It is discussed how the worldwide tourist arrivals, about 10% of the world’s domestic product, form a largely heterogeneous and directed complex network. Remarkably the random network of connectivity is converted into a scale-free network of intensities. The importance of weights on network connections is brought into discussion. It is also shown how strategic positioning particularly benefits from market diversity and that interactions among countries prevail on a technological and economic pattern, questioning the backbone of driving forces in traveling. 相似文献
4.
《Physica A》2007
We develop a simple statistical method to find affinity relations in a large opinion network which is represented by a very sparse matrix. These relations allow us to predict missing matrix elements. We test our method on the Eachmovie data of thousands of movies and viewers. We found that significant prediction precision can be achieved and it is rather stable. There is an intrinsic limit to further improve the prediction precision by collecting more data, implying perfect prediction can never obtain via statistical means. 相似文献
5.
社交网络和微博是重要的Web2.0应用模式, 其观点传播模式与其他网络媒体以及传统媒体相比有很大差异. 本文提出一种基于在线社交网络的观点传播模型, 研究社交网络中舆论观点扩散的形式与特征. 仿真结果表明: 模型中信息传播的速度与六度分割理论的结论十分符合; 一个带强烈倾向性的观点在固有观点均匀分布的网络中传播的情况下, 稳定时网络中不会出现相反的观点; 稳定时的观点分布与源节点的度和回溯深度有关, 并不受信任界限的限制, 这与Deffuant模型和Hegselmann-Krause模型不同. 同时, 本文还分析了传播意愿、观点变更率和信任界限对弛豫时间的影响. 相似文献
6.
基于BA无标度网络,构建了舆论和网络结构相互影响的自适应舆论演化模型.舆论的演化不仅受制于网络拓扑结构,而且也导致拓扑结构的变化.研究表明,演化达到稳态后,网络结构不再是初始的无标度网络而呈现泊松分布,而且随着时间的推移,系统中的舆论演化表现出很强的趋同效应,原来初始状态的几十个舆论,在长时间的演化后,大部分舆论灭亡,只有少数的舆论存留,且发展壮大.这种趋向与社会上的舆论、意见、信仰的演化大体上是符合的. 相似文献
7.
We unveil collective effects induced by imitation and social pressure by
analyzing data from three different sources:
birth rates, sales of cell phones and the drop of applause in concert halls. We interpret
our results within the framework of the
Random Field Ising Model, which is a threshold model for collective
decisions
accounting both for agent heterogeneity and social imitation. Changes of
opinion can occur either abruptly or
continuously, depending on the importance of herding effects. The main
prediction
of the model is a scaling relation between the height h of the speed
of variation peak and its width w of the form
h ∼w-κ, with κ= 2/3 for well connected
populations. Our three sets of data are compatible
with such a prediction, with κ≈0.62 for birth rates,
κ≈0.71 for cell phones
and κ≈0.64 for clapping. In this last case, we in fact
observe that some clapping
samples end discontinuously (w=0), as predicted by the model for
strong enough imitation. 相似文献
8.
We study the interaction of vector mesons with the octet of stable baryons in the framework of the local hidden gauge formalism using a coupled-channels unitary approach. We examine the scattering amplitudes and their poles, which can be associated to known J P = 1/2-, 3/2- baryon resonances, in some cases, or give predictions in other ones. The formalism employed produces doublets of degenerate J P = 1/2-, 3/2- states, a pattern which is observed experimentally in several cases. The findings of this work should also be useful to guide present experimental programs searching for new resonances, in particular in the strange sector where the current information is very poor. 相似文献
9.
Femtosecond pulses were generated from a Cr4+: Cunyite laser using a combination of a broadband semiconductor saturable absorber mirror (SESAM), chirped mirrors, and passive mode locking. The astigmatically compensated asymmetric X-cavity with a 4.5-mm-long Cr4+:Ca2GeO4 sample was operated with a 2.5% output coupler. Dispersion compensation was achieved using chirped mirrors. During self-starting mode-locked operation, pulses as short as 365 fs were generated at a pulse repetition rate of 100 MHz with output power of 70 mW and a spectral bandwidth of 5.2 nm at the center wavelength of 1432 nm. 相似文献
10.
Sourav Sarkar Bao-Xi Sun E. Oset M. J. Vicente Vacas 《The European Physical Journal A - Hadrons and Nuclei》2010,44(3):431-443
We study the interaction of the octet of vector mesons with the decuplet of baryons using Lagrangians of the hidden gauge theory for vector interactions. The unitary amplitudes in coupled channels develop poles that can be associated with some known baryonic resonances, while there are predictions for new ones at the energy frontier of the experimental research. The work offers guidelines on how to search for these resonances. 相似文献
11.
The Hunga-Tonga-Hunga-Ha'apai volcano in Tonga erupted violently on January 15, 2022. After 8 hours and 39 minutes, an infrasound array in Kunming at a distance of 10151 km away from the volcano recorded a sequence of strong infrasonic waves. The average period of the first four infrasonic waves is 443 s with propagation speed of 321 m/s. The azimuth angle of this event has been estimated by applying the progressive multi-channel correlation(PMCC) method to process the received signals. During continuous monitoring, the infrasonic waves propagating along and opposite to the direction towards the Kunming array around the earth are recorded respectively. 相似文献
12.
The Hunga-Tonga-Hunga-Ha’apai volcano in Tonga erupted violently on January 15, 2022. After 8 hours and 39 minutes, an infrasound array in Kunming at a distance of 10151 km away from the volcano recorded a sequence of strong infrasonic waves. The average period of the first four infrasonic waves is 443 s with propagation speed of 321 m/s. The azimuth angle of this event has been estimated by applying the progressive multi-channel correlation(PMCC) method to process the received signals. During c... 相似文献
13.
14.
15.
In this Letter, a hyperchaotic Lorenz system is constructed via state feedback control. Abundant dynamics of the hyperchaotic system is studied using the Lyapunov exponents, Poincaré section and bifurcation diagram. Furthermore, effective linear feedback controllers are designed for stabilizing hyperchaos to unstable equilibrium, periodic orbits and quasi-periodic orbit. Numerical simulations are given to illustrate and verify the results. 相似文献
16.
Quantum light sources are the core resources for photonics-based quantum information processing. We investigate the spectral engineering of photon triplets generated by third-order spontaneous parametric down-conversion in micro/nanofiber. The phase mismatching at one–third pump frequency gives rise to non-degenerate photon triplets, the joint spectral intensity of which has an elliptical locus with a fixed eccentricity of ■. Therefore, we propose a frequencydivision scheme to separate non-degen... 相似文献
17.
D. Stauffer P.M.C. de Oliveira 《The European Physical Journal B - Condensed Matter and Complex Systems》2002,30(4):587-592
The density of never changed opinions during the Sznajd consensus-finding process decays with time t as 1/t
θ. We find θ ≃ 3/8 for a chain, compatible with the exact Ising result of Derrida et al. In higher dimensions, however, the exponent differs from the Ising θ. With simultaneous updating of sublattices instead of
the usual random sequential updating, the number of persistent opinions decays roughly exponentially. Some of the simulations
used multi-spin coding.
Received 22 August 2002 / Received in final form 12 November 2002 Published online 31 December 2002 相似文献
18.
Mid-infrared pulses generated from the mixing output of an amplified, dual-wavelength Ti:sapphire system 总被引:2,自引:0,他引:2
We demonstrate the generation of femtosecond mid-infrared pulses by direct difference-frequency mixing in a AgGaS(2) crystal of two intense pulses from a dual-wavelength oscillator that have been simultaneously amplified in a single regenerative amplifier. A pulse energy of as much as 1.6 muJ was achieved at wavelengths of 9-11 mum. 相似文献
19.
Owen R Brink J Chen Y Kaplan JD Lovelace G Matthews KD Nichols DA Scheel MA Zhang F Zimmerman A Thorne KS 《Physical review letters》2011,106(15):151101
When one splits spacetime into space plus time, the spacetime curvature (Weyl tensor) gets split into an "electric" part E(jk) that describes tidal gravity and a "magnetic" part B(jk) that describes differential dragging of inertial frames. We introduce tools for visualizing B(jk) (frame-drag vortex lines, their vorticity, and vortexes) and E(jk) (tidal tendex lines, their tendicity, and tendexes) and also visualizations of a black-hole horizon's (scalar) vorticity and tendicity. We use these tools to elucidate the nonlinear dynamics of curved spacetime in merging black-hole binaries. 相似文献
20.
S. V. Ketov 《General Relativity and Gravitation》1990,22(2):193-202
We discuss the calculation of the three-loop-function for the twodimensional non-linear-model with torsion. It satisfies an integrability condition which leads to the ()1,2-corrections (to Einstein gravity) generated from the theory of closed bosonic strings at the tree level. Some applications of these results are briefly discussed. 相似文献