Catálogo de publicaciones - revistas

<jats:p>We investigate the entanglement dynamics of two distinguishable two-level systems (TLSs) characterized by energy difference <jats:italic>δ</jats:italic> located inside a rectangular hollow metallic waveguide of transverse dimensions <jats:italic>a</jats:italic> and <jats:italic>b</jats:italic>. The effects of energy difference <jats:italic>δ</jats:italic> and the inter-TLS distance on the time evolution of the concurrence of the TLSs are examined in the single excitation subspace when the energy separation of the TLS is far away from the cutoff frequencies of the transverse mode.</jats:p>

<jats:p>The quantum speed limit time for quantum system under squeezed environment is studied. We consider two typical models, the damped Jaynes–Cummings model and the dephasing model. For the damped Jaynes–Cummings model under squeezed environment, we find that the quantum speed limit time becomes larger with the squeezed parameter <jats:italic>r</jats:italic> increasing and indicates symmetry about the phase parameter value <jats:italic>θ</jats:italic> = <jats:italic>π</jats:italic>. Meanwhile, the quantum speed limit time can also be influenced by the coupling strength between the system and environment. However, the quantum speed limit time for the dephasing model is determined by the dephasing rate and the boundary of acceleration region that interacting with vacuum reservoir can be broken when the squeezed environment parameters are appropriately chosen.</jats:p>

<jats:p>To identify the unstable individuals of networks is of great importance for information mining and security management. Exploring a broad range of steady-state dynamical processes including biochemical dynamics, epidemic processes, birth–death processes and regulatory dynamics, we propose a new index from the microscopic perspective to measure the stability of network nodes based on the local correlation matrix. The proposed index describes the stability of each node based on the activity change of the node after its neighbor is disturbed. Simulation and comparison results show our index can identify the most unstable nodes in the network with various dynamical behaviors, which would actually create a richer way and a novel insight of exploring the problem of network controlling and optimization.</jats:p>

<jats:p>Impacts of microenvironments on cell migration have been reported in various interaction modes. A rapid tumor metastasis occurs along topological interfaces <jats:italic>in vivo</jats:italic>, such as the interface between the blood vessels and nerves. In this work, we culture MDA-MB231 cells at dish-liquid, dish-hydrogel, and hydrogel-liquid interfaces, respectively, to study how these different interfaces influence cell dynamics and morphology. Our results show that the migration mode of cells changes from an amoeboid motion to a mesenchymal motion but their speed do not change obviously if the interface changes from hydrogel-liquid to dish-liquid. In contrast, the migration mode of cells at a dish-hydrogel interface maintains as a mesenchymal motion, whereas their speed increases significantly.</jats:p>

<jats:p>High-voltage transmission line possesses a typical suspended cable structure that produces ice in harsh weather. Moreover, transversely galloping will be excited due to the irregular structure resulting from the alternation of lift force and drag force. In this paper, the nonlinear dynamics and internal resonance of an iced cable under wind excitation are investigated. Considering the excitation caused by pulsed wind and the movement of the support, the nonlinear governing equations of motion of the iced cable are established using a three-degree-of-freedom model based on Hamilton’s principle. By the Galerkin method, the partial differential equations are then discretized into ordinary differential equations. The method of multiple scales is then used to obtain the averaged equations of the iced cable, and the principal parametric resonance-1/2 subharmonic resonance and the 2:1 internal resonance are considered. The numerical simulations are performed to investigate the dynamic response of the iced cable. It is found that there exist periodic, multi-periodic, and chaotic motions of the iced cable subjected to wind excitation.</jats:p>

<jats:p>We investigate the nonequilibrium thermodynamics of a quenched <jats:italic>XY</jats:italic> spin chain with multi-spin interaction in a transverse field. The analytical expressions of both the average work and the relative entropy are obtained under different quenching parameters. The influences of the system parameters on the nonequilibrium thermodynamics are investigated. We find that at finite temperature the critical phenomenon induced by the multi-spin interaction and the external field can be revealed by the properties of the system nonequilibrium thermodynamics. In addition, our results indicate that the average work and the relative entropy can be used to detect both the existence and strength of the multi-spin interaction in the nonequlibrium system.</jats:p>

<jats:p>Cell migration in anisotropic microenvironment plays an important role in the development of normal tissues and organs as well as neoplasm progression, <jats:italic>e.g.</jats:italic>, osteogenic differentiation of embryonic stem cells was facilitated on stiffer substrates, indicating that the mechanical signals greatly affect both early and terminal differentiation of embryonic stem cells. However, the effect of anisotropy on cell migration dynamics, in particular, in terms of acceleration profiles which is important for recognizing dynamics modes of cell migration and analyzing the regulation mechanisms of microenvironment in mechanical signal transmission, has not been systematically investigated. In this work, we firstly rigorously investigate and quantify the differences between persistent random walk and anisotropic persistent random walk models based on the analysis of cell migration trajectories and velocity auto-covariance function, both qualitatively and quantitatively. Secondly, we introduce the concepts of positive and negative anisotropy based on the motility parameters to study the effect of anisotropy on acceleration profiles, especially the nonlinear decrease and non-monotonic behaviors. We particularly elaborate and discuss the mechanisms, and physical insights of non-monotonic behaviors in the case of positive anisotropy, focusing on the force exerted on migrating cells. Finally, we analyze two types of <jats:italic>in vitro</jats:italic> cell migration experiments and verify the universality of nonlinear decrease and the consistence of non-monotonic behaviors with numerical results. We conclude that the anisotropy of microenvironment is the cause of the non-monotonic and nonlinear dynamics, and the anisotropic persistent random walk can be as a suitable tool to analyze <jats:italic>in vitro</jats:italic> cell migration with different combinations of motility parameters. Our analysis provides new insights into the dynamics of cell migration in complex microenvironment, which also has implications in tissue engineering and cancer research.</jats:p>

<jats:p>We investigate the properties of a generalized Rabi model by replacing the two-level atom in Rabi model with a ferromagnetic Heisenberg spin chain. We find that the dynamical behavior of the system can be divided into four categories. The energy spectrum of the ground state and some low excited states are obtained. When the magnons and the photon are in resonance, the model is exactly solvable and the rigorous solution is obtained. Near the resonance point where the detuning is small, the system is studied with the help of perturbation theory. This model has a spontaneously breaking of parity symmetry, suggesting the existence of a quantum phase transition. The critical exponent from the normal phase is computed.</jats:p>

<jats:p>The idea of network splitting according to time delay and weight is introduced. Based on the cyber physical systems (CPS), a class of multi-weighted complex transportation networks with multiple delays is modeled. The finite-time synchronization of the proposed complex transportation networks model is studied systematically. On the basis of the theory of stability, the technique of adaptive control, aperiodically intermittent control and finite-time control, the aperiodically intermittent adaptive finite-time synchronization controller is designed. The controller designed in this paper is beneficial for understanding the synchronization in multi-weighted complex transportation networks with multiple delays. In addition, the conditions for the existence of finite time synchronization have been discussed in detail. And the specific value of the settling finite time for synchronization is obtained. Moreover, the outer coupling configuration matrices are not required to be irreducible or symmetric. Finally, simulation results of the finite-time synchronization problem are given to illustrate the correctness of the results obtained.</jats:p>

<jats:p>Directly resolving structural changes in material on the atomic scales of time and space is desired in studies of many disciplines. Ultrafast electron diffraction (UED), which combines the temporal resolution of femtosecond-pulse laser and the spatial sensitivity of electron diffraction, is an advancing methodology serving such a goal. Here we present the design of a UED apparatus with multiple operation modes for observation of collective atomic motions in solid material of various morphologies. This multi-mode UED employs a pulsed electron beam with propagation trajectory of parallel and convergent incidences, and diffraction configurations of transmission and reflection, as well utilities of preparation and characterization of cleaned surface and adsorbates. We recorded the process of electron–phonon coupling in single crystal molybdenum ditelluride following excitation of femtosecond laser pulses, and diffraction patterns of polycrystalline graphite thin film under different settings of electron optics, to demonstrate the temporal characteristics and tunable probe spot of the built UED apparatus, respectively.</jats:p>