We demonstrate that the dynamic information and the spatial structure of a Rydberg wave packet formed by two neighboring Rydberg states can be simultaneously probed by harmonic spectra in a few-cycle laser pulse, wher...
详细信息
We demonstrate that the dynamic information and the spatial structure of a Rydberg wave packet formed by two neighboring Rydberg states can be simultaneously probed by harmonic spectra in a few-cycle laser pulse, where the Rydberg wave packet is produced by a pump laser field. By controlling the time delay of the pump-probe laser pulses, the harmonic spectra present a periodic variation, which directly illustrates the electron oscillation between the two neighboring Rydberg states. Specifically, by taking advantage of the periodic variation of the harmonic efficiency and the dip structure in the spectrum, one can detect the spatial characteristics and the dynamic information of the initial Rydberg wave packet.
In this paper, we consider the three-dimensional isentropic compressible fluid models of Korteweg type, called the compressible Navier-Stokes-Korteweg system. We mainly present the vanishing capillarity limit of the s...
详细信息
We derive an effective potential for binary black hole (BBH) spin precession at second post-Newtonian order. This effective potential allows us to solve the orbit-averaged spin-precession equations analytically for ar...
详细信息
We derive an effective potential for binary black hole (BBH) spin precession at second post-Newtonian order. This effective potential allows us to solve the orbit-averaged spin-precession equations analytically for arbitrary mass ratios and spins. These solutions are quasiperiodic functions of time: after a fixed period, the BBH spins return to their initial relative orientations and jointly precess about the total angular momentum by a fixed angle. Using these solutions, we classify BBH spin precession into three distinct morphologies between which BBHs can transition during their inspiral. We also derive a precession-averaged evolution equation for the total angular momentum that can be integrated on the radiation-reaction time and identify a new class of spin-orbit resonances that can tilt the direction of the total angular momentum during the inspiral. Our new results will help efforts to model and interpret gravitational waves from generic BBH mergers and predict the distributions of final spins and gravitational recoils.
We conduct a study on heat conduction through coupled Fermi-Pasta-Ulam (FPU) chains by using classical molecular dynamics simulations. Our attention is dedicated to showing how the phonon transport is affected by the ...
详细信息
We conduct a study on heat conduction through coupled Fermi-Pasta-Ulam (FPU) chains by using classical molecular dynamics simulations. Our attention is dedicated to showing how the phonon transport is affected by the interchain coupling. It has been well accepted that the heat conduction could be impeded by the interchain interaction due to the interface phonon scattering. However, recent theoretical and experimental studies suggest that the thermal conductivity of nanoscale materials can be counterintuitively enhanced by the interaction with the substrate. In the present paper, by consecutively varying the interchain coupling intensity, we observed both enhancement and suppression of thermal transport through the coupled FPU chains. For weak interchain couplings, it is found that the heat flux increases with the coupling intensity, whereas in the case of strong interchain couplings, the energy transport is found to be suppressed by the interchain interaction. Based on the phonon spectral energy density method, we attribute the enhancement of the energy transport to the excited phonon modes (in addition to the intrinsic phonon modes), while the upward shift of the high-frequency phonon branch and the interface phonon-phonon scattering account for the suppressed heat conduction.
Controlling segregation is both a practical and a theoretical challenge. Using a novel drum design comprising concave and convex geometry, we explore, through the application of both discrete particle simulations and ...
详细信息
Controlling segregation is both a practical and a theoretical challenge. Using a novel drum design comprising concave and convex geometry, we explore, through the application of both discrete particle simulations and positron emission particle tracking, a means by which radial size segregation may be used to drive axial segregation, resulting in an order of magnitude increase in the rate of separation. The inhomogeneous drum geometry explored also allows the direction of axial segregation within a binary granular bed to be controlled, with a stable, two-band segregation pattern being reliably and reproducibly imposed on the bed for a variety of differing system parameters. This strong banding is observed to persist even in systems that are highly constrained in the axial direction, where such segregation would not normally occur. These findings, and the explanations provided of their underlying mechanisms, could lead to radical new designs for a broad range of particle processing applications but also may potentially prove useful for medical and microflow applications.
We analyze the magnetic form factor of Cu2+ in low-dimensional quantum magnets by taking the metal-ligand hybridization into account explicitly. In this analysis, we use the form of magnetic Wannier orbitals, derived ...
We analyze the magnetic form factor of Cu2+ in low-dimensional quantum magnets by taking the metal-ligand hybridization into account explicitly. In this analysis, we use the form of magnetic Wannier orbitals, derived from first-principles calculations, and identify contributions of different atomic sites. We demonstrate that covalency of metal-ligand interactions has a strong effect on the magnetic form factor and must be taken into account in the evaluation of magnetic neutron scattering. The use of covalent form factors facilitates quantitative description of inelastic neutron-scattering data for BaCuSi2O6 that would not be possible when ionic form factors are used. We also propose easy-to-use approximations of the partial orbital contributions to the magnetic form factor in order to give microscopic explanation for the results obtained in previous first-principles studies.
We present extreme ultraviolet and visible spectra of promethiumlike tungsten and gold obtained with an electron beam ion trap. Although the contributions from a few charge states are involved in the spectra, the char...
详细信息
We present extreme ultraviolet and visible spectra of promethiumlike tungsten and gold obtained with an electron beam ion trap. Although the contributions from a few charge states are involved in the spectra, the charge state of the ion assigned to the observed lines is definitely identified by the time-of-flight (TOF) analysis of the ions performed at the same time with the spectroscopic measurements. Experimental results are compared with collisional-radiative model calculations as well as previous experimental and theoretical studies. Some ambiguous identifications in the previous observations have been clarified owing to the definite identification by the TOF analysis.
Due to unique physiochemical properties of carbon nanotubes (CNTs), they are utilized in biomedicine applications including biomedical engineering, tissue engineering, drug delivery, gene therapy and biosensor enginee...
详细信息
Due to unique physiochemical properties of carbon nanotubes (CNTs), they are utilized in biomedicine applications including biomedical engineering, tissue engineering, drug delivery, gene therapy and biosensor engineering. Studies have been shown that carbon nanotube have a large propensity to interact with biomembranes; therefore, the toxicity of these nanomaterials and understanding the way CNTs interact with cell become more important. Recently, enormous efforts have been made to understand the molecular mechanism of CNTs and lipid bilayer interaction. Because of the relative large scale of lipid bilayer, quantum ab-initio methods are not common for such systems; consequently, both all atom and coarse grained molecular dynamic simulation (MD) are widely performed. For simulation of such system it is important to apply the correct physical and structural properties of carbon nanotube in the simulation, for instance with density functional theory (DFT) modeling it has been clear that, for open-ended CNTs not only is there unsaturated bonds at the end of tube, but also has a significant dipole moment which should not neglected and their quantity correspond to nanotube chirality and diameter. The aim of this work is to discuss the partial charges distribution along the carbon nanotubes and describe how they affect in CNTs -lipid bilayer interaction by free energy calculation. Our Simulation consist of two stage, first partial charges for pristine and functional carbon nanotube were determined by DFT calculation then results were applied to molecular dynamic force field. The DFT simulation computes partial charges quantity at the ends of nanotube and its results indicate that partial charges for functional nanotubes are higher than pristine nanotubes. The MD simulation determines that nanotubes interaction energy with biomembrane is highly strong, about 120 kcal/mol.
It is shown that the filamentation instability of relativistically intense laser pulses in plasmas can be mitigated in the case where the laser beam has an elliptically distributed beam profile. A high-power elliptica...
详细信息
It is shown that the filamentation instability of relativistically intense laser pulses in plasmas can be mitigated in the case where the laser beam has an elliptically distributed beam profile. A high-power elliptical Gaussian laser beam would break up into a regular filamentation pattern—in contrast to the randomly distributed filaments of a circularly distributed laser beam—and much more laser power would be concentrated in the central region. A highly elliptically distributed laser beam experiences anisotropic self-focusing and diffraction processes in the plasma channel ensuring that the unstable diffractive rings of the circular case cannot be produced. The azimuthal modulational instability is thereby suppressed. These findings are verified by three-dimensional particle-in-cell simulations.
暂无评论