Narrow Results

This paper studies the mechanisms of ionic channels in neurons of lamprey central pattern generator (CPG), such as the N-methyl-D-aspartate (NMDA) receptor channel and the calcium-dependent potassium channel etc. The CPG properties on oscillation attributed to the ionic mechanisms are exploited. The conditions for oscillation, divergence, convergence and the guidelines on selection of the parameters are established. The effects of key parameters on CPG frequency and duty cycle are investigated. Mathematical analysis and simulation study is performed to verify these results. This study will potentially enhance the effective application of biological CPG model into engineering practice such as robotics.

The buoyancy driven exchange flow through the large openings in horizontal partitions occurs in many practical situations such as in enclosed regions with a ceiling opening and a heat source such as fire. The density difference between two compartments arises partly due to difference in composition and partly from the difference in temperature. A heavier fluid located on the top of a lighter fluid and separated by a horizontal vent constitutes a gravitationally unstable system. Horizontal vents produce flow, which are unstable with irregular oscillatory behavior. However, when lower compartment is slightly pressurized the flow becomes stable and unidirectional. A numerical study has been performed to characterize the bi-directional flow and transition to unidirectional flow through a horizontal vent in an enclosure, due to differences in pressure and density across the vent. Fresh and salt water has been considered as working fluids to create density difference across the vent with a pressure field imposed in the lower compartment. The pressure in the lower region was increased to find the critical pressure corresponding to transition to unidirectional from bi-directional flow. Unsteady, 2D axisymmetric, incompressible Navier–Stokes equation along with species, turbulence and continuity equation have been solved with finite volume method using the in-house computational fluid dynamics (CFD) code. Several cases were examined to compute the critical pressure for various density differences for low opening aspect ratio. The code has been validated with reported experiments and used to simulate various other practical cases occurred during fire induced flow through such openings.

Many real-world networks are interconnected with each other. In this paper, we study the traffic dynamics in interconnected complex networks under an intentional attack. We find that with the shortest time delay routing strategy, the traffic dynamics can show the stable state, periodic, quasi-periodic and chaotic oscillations, when the capacity redundancy parameter changes. Moreover, compared with isolated complex networks, oscillations always take place in interconnected networks more easily. Thirdly, in interconnected networks, oscillations are affected strongly by the coupling probability and coupling preference.

An appropriately placed array of new generation neutrino detectors, in conjunction with the use of nuclear devices as a source of intense flux of neutrinos, can serve as a powerful precision probe of neutrino–oscillation parameters. If such detectors are made mobile by placing them on a criss-crossing grid of railway tracks, one may under certain hostile circumstances use them to locate nuclear powered vehicles like submarines, aircraft carriers and any other strong neutrino sources. Since neutrinos cannot be shielded, it may not be possible to escape detection.

Reporting about the formalism with the Dirac equation we describe the dynamics of chiral oscillations for a fermionic particle non-minimally coupling with an external magnetic field. For massive particles, the chirality and helicity quantum numbers represent different physical quantities of representative importance in the study of chiral interactions, in particular, in the context of neutrino physics. After solving the interacting Hamiltonian (Dirac) equation for the corresponding fermionic Dirac-type particle (neutrino) and quantifying chiral oscillations in the Dirac wave packet framework, we avail the possibility of determining realistic neutrino chirality conversion rates by means of (helicity) polarization measurements. We notice that it can become feasible for some particular magnetic field configurations with large values of B orthogonal to the direction of the propagating particle.

We discuss the current state of measurements taken by MiniBooNE and emphasize the uniqueness of neutrino oscillations as an important probe into the "Windows on the Universe."

T2K is the first of a new generation of long baseline neutrino oscillation experiments that will measure neutrino oscillations parameters. The experiment uses the J-PARC accelerator complex on the east cost of Japan to sent a neutrino beam to the Kamioka mine, located 295 km to the west. It consists of a dedicated beam-line, a near detector complex to characterize the beam and the well-known Super-Kamiokande detector to measure the oscillation signal. This paper describes the experimental setup, the results of the first measurement campaign as well as giving an outlook on the future potential of the experiment.

Existence of non-zero neutrino magnetic moment would mean new physics beyond the standard model. A search for the neutrino magnetic moment has been conducted using the high statistic solar neutrino data from Super-Kamiokande-I. This is done by looking for the distortion to the observed energy spectrum of recoil electrons. A non-zero neutrino magnetic moment would cause an increase of event rates at lower energies. The search found no clear signal of neutrino magnetic moment. A limit on the neutrino magnetic moment has been obtained at 3.6 × 10^-10μ_B at 90% C.L. by fitting to the Super-Kamiokande day-night spectra. The effects of neutrino oscillation have been included in the analysis. Including results from other neutrino experiments limiting the oscillation region, a limit of 1.1 × 10^-10μ_B at 90% C.L. was obtained.

A method of dispersing nanogranules in polymer utilizing the stretching, compression, and shearing effects induced by bubble inflation or oscillation in a polymer melt undergoing foaming is reported. It can be known from theoretical calculation that the bubble inflation is very fast (about μs). The other result of theoretical calculation is that the bubble can oscillate when appearing appropriate condition in polymer. The successful dispersion of nanogranules in a polymer melt by bubble inflation has been shown by experiment. Comparison of a theoretical analysis of the dispersion effect is given by the ISBS method with the results from experimental scanning electron microscope micrographs, given reasonable grounds for support of our hypotheses.

This paper demonstrates in theory that a bias-induced oscillatory current should occur in a tunneling junction made of the high-T_c cuprates in pseudogap state. This novel oscillatory effect can be utilized for the judging mechanism of pseudogap in the high-T_c cuprates and a series of non-superconducting materials. In application, this novel effect can be utilized for making electronic devices, using Cooper pairs and operating at room temperature.

Transmittance self-oscillation discovered in amorphous GeSe₂ films has attracted considerable interest, while its underlying mechanism remains controversial. We suggest that the oscillation is governed by at least two kinds of changes; one occurs in absorption for thin ($\sim 6\mu$m) films and the other in refractive-index for thick ($\sim 1$mm) plates. We also detail a model, which assumes recoverable micro-crystallization. An idea for increasing the oscillation frequency is proposed for possible applications.

In this work, the influence of two-dimensional state density on oscillations of transverse electrical conductivity in heterostructures with rectangular quantum wells is investigated. A new analytical expression is derived for calculating the temperature dependence of the transverse electrical conductivity oscillation and the magnetoresistance of a quantum well. For the first time, a mechanism has been developed for oscillating the transverse electrical conductivity and magnetoresistance of a quantum well from the first-order derivative of the magnetic field (differential) $\frac{\partial ({\rho }_{{}_{\perp }}^{2d}(E,B,T,d))}{\partial B}$ at low temperatures and weak magnetic fields. The oscillations of electrical conductivity and magnetoresistance of a narrow-band quantum well with a nonparabolic dispersion law are investigated. The proposed theory investigated the results of experiments of a narrow-band quantum well (In_xGa${}_{1-x}$Sb).

An aircraft model was tested at the 3-meter low speed wind tunnel as it was oscillated with large amplitude. The unsteady aerodynamic behavior was acquired during the oscillation in yawing, rolling and yawing-rolling. The lateral-directional dynamic derivative was obtained using the mathematic model of unsteady aerodynamics and the dynamic derivative simulation. According to the principle of linear superposition, the unsteady aerodynamic parameters of the model about yaw-roll coupled motion can be obtained by the quasi-steady aerodynamic model and the result was compared with the experimental test. It was found that for the quasi-steady aerodynamic model the unsteady aerodynamic characteristic was in agreement with the test at the middle and large angle of attack (for example α ≤ 45°), but was opposite at the extremely large angle of attack (α > 45°).

The oscillation of a cavitation bubble and the effect of gas content inside a cavity on the bubble motion are investigated by theory and experiment. Based on the cavitation model, the numerical study yields the gas content dependence of the amplitude and duration of the bubble oscillation in liquids. In experiment, the temporal oscillation of a single laser-induced cavitation bubble is obtained by means of a sensitive fiber-optic sensor based on optical beam deflection. The characteristic bubble parameters are determined, including the maximum (minimum) radii, oscillation duration and bubble energy, which all decrease with the oscillation. Besides, combining the cavitation theory with experimental data, the variation of gas content within the bubble during each oscillation is estimated, which increases with the oscillation cycle. Our results reveal the competitive interplay of the bubble energy and gas content during the bubble motion and the bubble energy in effect outweighs the latter.

We present the integration and accuracy and power improved hearing aid system that proposes the triple oscillation-based loops (TOL) technique. Compared with the conventional techniques, the technique replaces the interface capacitors, A/D and D/A convertors with the oscillation-based closed loop and the calibration/operation feedback paths, which are able to enhance the integration of the system and improve the system's accuracy and power performance. Specifically, the technique achieves the only once of the second-order delta-sigma modulation with an integrator and an oscillator. To realize the architecture, the current mode blocks with calibration and successive subtraction are presented on the circuit design. Simulated with a 0.13 μm standard CMOS process in Cadence, with the 16 ohm loudspeaker impedance under the 1 V supply voltage, the input referred DC offset voltage with interface capacitor free is achieved below 2.5 mV; and the signal-to-noise and distortion rate (SNDR) achieves 50 dB@400 mV_p-p output voltage. Moreover, the power consumption with no load is maintained within 350 μW.

Intracellular cardiac Ca²⁺ handling involves interactions of numerous distinct cellular and macromolecular structures. Such interactions coordinate the complicated behaviors of individual processes into spatial and temporal coherent patterns of Ca²⁺ sparks, oscillations and traveling waves. Understanding the dynamical behaviors and functional roles of intracellular Ca²⁺ handling requires not only detailed experimental information about subcellular structures and dynamics, but also useful tools to integrate and analyze this information. This requires interactions between experimental and simulation results within a virtual cell.

We present some sufficient conditions for the existence of isochronous sections of planar differential systems. We consider isochronous sections at a critical point, a cycle, the boundary of a central or attraction region.

The primary purpose of this paper is to show that simple dissipation can bring about oscillations in certain kinds of asymptotically stable nonlinear dynamical systems; namely when the system is locally active where the dissipation is introduced. Furthermore, if these nonlinear dynamical systems are coupled with appropriate choice of diffusion coefficients, then the coupled system can exhibit spatio-temporal oscillations. The secondary purpose of this paper is to show that spatio-temporal oscillations can occur in spatially discrete reaction diffusion equations operating on the edge of chaos, provided the array size is sufficiently large.

Coupled positive and negative feedback loops form an essential building block of cellular signaling pathways, but the dynamics of such a system remain to be fully explored. Here, we systematically analyze a two-component circuit with interlinked positive and negative feedback loops, focusing on feedback-induced dynamics and their mechanisms. We show that feedbacks can induce monostability, oscillation, and excitability as well as the coexistence of two attractors (including that of two different stable steady states (called Type-I bistability) and that of both a stable steady state and a stable limit cycle (called Type-II bistability)). In particular for Type-II bistability, we find that feedback-controlled molecular noise can induce stochastic switching between two different attractors, and that the first passage time between them exhibits a multi-peak distribution. These investigations provide insights for understanding the biological functions of coupled positive and negative feedback circuits from the viewpoint of dynamics.

In the three-body problem, it is known that there exists a special set of periodic orbits: spatial isosceles periodic orbits. In each period, one body moves up and down along a straight line, and the other two bodies rotate around this line. In this work, we revisit this set of orbits by applying variational method. Two unexpected phenomena are discovered. First, this set is not always spatial. It actually bifurcates from the circular Euler (central configuration) orbit to the Broucke (collision) orbit. Second, one of the orbits in this set encounters an oscillating behavior. By running its initial condition, the orbit stays periodic for only a few periods before it becomes irregular. However, it moves close to another periodic shape in a while. Shortly it falls apart again and starts running close to a third periodic shape after a moment. This oscillation continues as t increases. Actually, up to t = 1.2 × 10⁵, the orbit is bounded and keeps oscillating between periodic shapes and irregular motions.