Temporary hearing loss influences post-stimulus time histogram and single neuron action potential estimates from human compound action potentials

An analytic compound action potential (CAP) obtained by convolving functional representations of the post-stimulus time histogram summed across auditory nerve neurons [P(t)] and a single neuron action potential [U(t)] was fit to human CAPs. The analytic CAP fit to pre- and postnoise-induced temporary hearing threshold shift (TTS) estimated in vivo P(t) and U(t) and the number of neurons contributing to the CAPs (N). The width of P(t) decreased with increasing signal level and was wider at the lowest signal level following noise exposure. P(t) latency decreased with increasing signal level and was shorter at all signal levels following noise exposure. The damping and oscillatory frequency of U(t) increased with signal level. For subjects with large amounts of TTS, U(t) had greater damping than before noise exposure particularly at low signal levels. Additionally, U(t) oscillation was lower in frequency at all click intensities following noise exposure. N increased with signal level and was smaller after noise exposure at the lowest signal level. Collectively these findings indicate that neurons contributing to the CAP during TTS are fewer in number, shorter in latency, and poorer in synchrony than before noise exposure. Moreover, estimates of single neuron action potentials may decay more rapidly and have a lower oscillatory frequency during TTS.     

Cochlear action potential threshold and single unit thresholds.

There is a close correlation between the sound pressure of tone burst required to affect a primary auditory neuron at its characteristic frequency and that which will produce a detectable N1 response at the same frequency. Units with thresholds from 80--0 db SPL (recorded from damaged and undamaged cochleas) were 0--20 dB , respectively, more sensitive than the action potential response.     

Analytic treatment of the network synchronization problem with time delays

Motivated by novel results in the theory of network synchronization, we analyze the effects of nonzero time delays in stochastic synchronization problems with linear couplings in an arbitrary network. We determine analytically the fundamental limit of synchronization efficiency in a noisy environment with uniform time delays. We show that the optimal efficiency of the network is achieved for λτ = π(3/2)/(2√π + 4) ≈ 0.738, where λ is the coupling strength (relaxation coefficient) and τ is the characteristic time delay in the communication between pairs of nodes. Our analysis reveals the underlying mechanism responsible for the trade-off phenomena observed in recent numerical simulations of network synchronization problems.     

The effects of cochlear hypothermia on compound action potential tuning

The effects of lowered cochlear temperature on eighth-nerve tuning were assessed by using forward masking of whole nerve action potential (AP) responses to generate AP tuning curves (APTCs) at cochlear temperatures ranging from 38.5 degrees to 30 degrees C for probe frequencies from 8 to 36 kHz. The data indicate that subnormal cochlear temperatures result in: broadened APTCs for probe frequencies above 10 kHz which are interpreted as resulting from reduced hair-cell frequency selectivity, lowered or more sensitive APTC tips where tone-burst thresholds are unchanged, and raised or less sensitive tips where thresholds to tone bursts were elevated. Increased tip sensitivity is explained in terms of enhanced eighth-nerve adaptation which occurred during hypothermia. Experiments directly addressing adaptation were performed, in which the masker-probe interval (delta t) was systematically lengthened. The normalized AP decrement versus delta t functions indicate an enhancement of both the amount and duration of adaptation during hypothermia. Functions relating the growth of response to the masker (AP decrement versus masker intensity functions) were reduced at low temperatures.     

Analytic treatment of time fractional nonlinear operator equation with applications

In this paper, analytic treatment of time fractional nonlinear operator equation has been presented by using Adomian’s decomposition method (ADM). To illustrate the procedure, the nonlinear Schrodinger (NLS) equation of fractional order has been solved. The solution is expressed in terms of Mittag-Leffler function. The present method performs extremely well in terms of accuracy, efficiency and simplicity.     

急性缺氧条件下EP、CM、CAP以及耳蜗毛细胞的形态学变化

本实验用同一根玻璃微电极在豚鼠耳蜗中阶记录EP（Endocochlear Potential,耳蜗内电位）、CM（Cochlear Microphonics,耳蜗振电压）、CAP（Comnound Action Potential,复合动作电位）,观察在不同缺氧状态下,三者动态变化过程.发现在缺氧初始（1-2分钟）,CM和CAP随EP同步迅速下降;但缺氧3-6分钟时,CM下降缓慢,似一\     

The inverse problem of estimating the gravitational time dilation

Precise testing of the gravitational time dilation effect suggests comparing the clocks at points with different gravitational potentials. Such a configuration arises when radio frequency standards are installed at orbital and ground stations. The ground-based standard is accessible directly, while the spaceborne one is accessible only via the electromagnetic signal exchange. Reconstructing the current frequency of the spaceborne standard is an ill-posed inverse problem whose solution depends significantly on the characteristics of the stochastic electromagnetic background. The solution for Gaussian noise is known, but the nature of the standards themselves is associated with nonstationary fluctuations of a wide class of distributions. A solution is proposed for a background of flicker fluctuations with a spectrum (1/f)^γ, where 1 < γ < 3, and stationary increments. The results include formulas for the error in reconstructing the frequency of the spaceborne standard and numerical estimates for the accuracy of measuring the relativistic redshift effect.     

Analytic extension of the coherent potential approximation to clusters

We put forward the homomorphic cluster coherent potential approximation (HCPA) for substitutionally disordered systems as one possible way of avoiding the breakdown of analyticity in average Green's functions even when effects of clusters are properly taken into account. We assert that a cluster CPA yields an analytic physical solution if a one-particle total Hamiltonian is partitioned into the sum of homomorphic single-cluster Hamiltonians and the CPA condition is applied to one of these homomorphic sub-Hamiltonians.     

The role of single-channel cues in synchrony perception: the summed waveform

Human observers are able to discriminate between simultaneously presented bands of noise having envelopes that are identical (synchronous) rather than statistically independent (asynchronous). The possibility that the detection of envelope synchrony is based on cues available in a single critical band, rather than on a simultaneous comparison of envelopes extracted via independent critical bands, is examined. Two potential single-channel cues were examined, both relying on the assumption that information present in the envelope of the summed bands is available to the listener. One such single-channel cue is the rms of the envelope of the summed waveform; the envelope is more deeply modulated for the summed synchronous bands than for the summed asynchronous bands. The second cue examined was envelope regularity; the envelope of the summed synchronous bands has periodic envelope minima, while the summed asynchronous bands exhibit aperiodic envelope minima. Psychophysical results suggest that such within-channel cues may be both available to, and utilized by, the listener when the component bands are separated by less than one-third of an octave.     

Map-based model of the cardiac action potential

A simple computationally efficient model which is capable of replicating the basic features of cardiac cell action potential is proposed. The model is a four-dimensional map and demonstrates good correspondence with real cardiac cells. Various regimes of cardiac activity, which can be reproduced by the proposed model, are shown. Bifurcation mechanisms of these regimes transitions are explained using phase space analysis. The dynamics of 1D and 2D lattices of coupled maps which model the behavior of electrically connected cells is discussed in the context of synchronization theory.     

Analytic solutions of the double ring-shaped Coulomb potential in quantum mechanics

The exact solutions of the Schr6dinger equation with the double ring-shaped Coulomb potential are presented, including the bound states, continuous states on the ＂k/2π scale＂, and the calculation formula of the phase shifts. The polar angular wave functions are expressed by constructing the so-called super-universal associated Legendre polynomials. Some special cases are discussed in detail.     

Analytic solution of the Percus-Yevick equation for sticky hard sphere potential

It is shown that within the Percus-Yevick approximation the radial distribution function for sticky (i.e. with a surface adhesion) hard spheres satisfies a linear differential equation with retarded right-hand side. Using the theory of distributions and the Green's function technique the analytic solution of this equation is found and explicit formulas are given enabling one to evaluate the radial distribution function both for sticky and non-attractive hard spheres for any distance and any density.     

PS(X~2Π_r)基态势能函数与光谱常数研究

根据群论及原子分子反应静力学的有关原理,推导了PS基态分子电子态及其合理的离解极限.采用Gaussian 03软件中的密度泛函理论B3LYP和B3P86结合6-311++G(3df,3pd)、6-311++G、6-311G(3df,3pd)、cc-p VTZ和D95基组,对PS分子基态平衡结构和谐振频率进行了计算.通过比较计算结果,发现B3P86方法结合cc-p VTZ基组计算所得结果与实验值最接近.在该水平下对PS分子的基态进行了单点势能扫描计算,利用正规方程组拟合三参数的Murrell-Sorbie函数和修正的Murrell-Sorbie+C6函数,得到了基态PS分子完整的势能函数与相应的光谱常数ωe、ωexe、Be和αe的值.计算结果表明,利用三参数的Murrell-Sorbie函数计算所得的光谱常数与实验数据吻合得更好.     

Magnetoelectric response of the spin-Peierls compound CuGeO3

The effect of an electric field on the magnetic susceptibility in a pure CuGeO₃ single crystal at microwave frequencies is investigated. A quadratic effect of the electric field on the magnetic susceptibility, which increases with decreasing temperature, is observed in the spin-Peierls state at temperatures below 5 K. The observed effect is tentatively attributed to residual magnetism, due to distortions of the regular dimerized structure at domain walls with different values of the dimerization phase, and to the effect of the electric field on the interchain exchange interaction. Pis’ma Zh. éksp. Teor. Fiz. 64, No. 9, 646–651 (10 November 1996)     

Analytic approximations of statistical quantities and response of noisy oscillators

Nonlinear oscillators have been utilized in many contexts because they encompass a large class of phenomena. For a reduced phase oscillator model with weak noise forcing that is necessarily multiplicative, we provide analytic formulas for the stationary statistical quantities of the random period. This is an important quantity which we term ‘response’ (i.e., the spike times, instantaneous frequency in neuroscience, the cycle time in chemical reactions, etc.) that is often analytically intractable in noisy oscillator systems. The analytic formulas are accurate in the weak noise limit so that one does not have to numerically solve a time-varying Fokker-Planck equation. The steady-state and dynamic responses are also analyzed with deterministic forcing. A second order analytic formula is derived for the steady-state response, whereas the dynamic response with time-varying forcing is more complicated. We focus on the specific case where the forcing is sinusoidal and accurately capture the frequency response with an analytic approximation that is obtained with a rescaling of the equation. By utilizing various techniques in the weak noise regime, this work leads to a better understanding of how the random period of nonlinear oscillators are affected by multiplicative noise and external forcing. Comparisons of the asymptotic formulas with a full oscillator system confirm the qualitative accurateness of the theory.     

A method of estimating the noise level in a chaotic time series

An attempt is made in this study to estimate the noise level present in a chaotic time series. This is achieved by employing a linear least-squares method that is based on the correlation integral form obtained by Diks in 1999. The effectiveness of the method is demonstrated using five artificial chaotic time series, the Henon map, the Lorenz equation, the Duffing equation, the Rossler equation and the Chua's circuit whose dynamical characteristics are known a priori. Different levels of noise are added to the artificial chaotic time series and the estimated results indicate good performance of the proposed method. Finally, the proposed method is applied to estimate the noise level present in some real world data sets.     

Application of time transfer function to McVittie spacetime: gravitational time delay and secular increase in astronomical unit

We attempt to calculate the gravitational time delay in a time-dependent gravitational field, especially in McVittie spacetime, which can be considered as the spacetime around a gravitating body such as the Sun, embedded in the FLRW (Friedmann–Lemaître–Robertson–Walker) cosmological background metric. To this end, we adopt the time transfer function method proposed by Le Poncin-Lafitte et al. (Class Quantum Gravity 21:4463, 2004) and Teyssandier and Le Poncin-Lafitte (Class Quantum Gravity 25:145020, 2008), which is originally related to Synge’s world function Ω(x _A , x _B ) and enables to circumvent the integration of the null geodesic equation. We re-examine the global cosmological effect on light propagation in the solar system. The round-trip time of a light ray/signal is given by the functions of not only the spacial coordinates but also the emission time or reception time of light ray/signal, which characterize the time-dependency of solutions. We also apply the obtained results to the secular increase in the astronomical unit, reported by Krasinsky and Brumberg (Celest Mech Dyn Astron 90:267, 2004), and we show that the leading order terms of the time-dependent component due to cosmological expansion is 9 orders of magnitude smaller than the observed value of dAU/dt, i.e., 15 ± 4 (m/century). Therefore, it is not possible to explain the secular increase in the astronomical unit in terms of cosmological expansion.