Estimating Phase Amplitude Coupling between Neural Oscillations Based on Permutation and Entropy

Cross-frequency phase–amplitude coupling (PAC) plays an important role in neuronal oscillations network, reflecting the interaction between the phase of low-frequency oscillation (LFO) and amplitude of the high-frequency oscillations (HFO). Thus, we applied four methods based on permutation analysis to measure PAC, including multiscale permutation mutual information (MPMI), permutation conditional mutual information (PCMI), symbolic joint entropy (SJE), and weighted-permutation mutual information (WPMI). To verify the ability of these four algorithms, a performance test including the effects of coupling strength, signal-to-noise ratios (SNRs), and data length was evaluated by using simulation data. It was shown that the performance of SJE was similar to that of other approaches when measuring PAC strength, but the computational efficiency of SJE was the highest among all these four methods. Moreover, SJE can also accurately identify the PAC frequency range under the interference of spike noise. All in all, the results demonstrate that SJE is better for evaluating PAC between neural oscillations.     

Optimal control in NMR spectroscopy: Numerical implementation in SIMPSON

We present the implementation of optimal control into the open source simulation package SIMPSON for development and optimization of nuclear magnetic resonance experiments for a wide range of applications, including liquid- and solid-state NMR, magnetic resonance imaging, quantum computation, and combinations between NMR and other spectroscopies. Optimal control enables efficient optimization of NMR experiments in terms of amplitudes, phases, offsets etc. for hundreds-to-thousands of pulses to fully exploit the experimentally available high degree of freedom in pulse sequences to combat variations/limitations in experimental or spin system parameters or design experiments with specific properties typically not covered as easily by standard design procedures. This facilitates straightforward optimization of experiments under consideration of rf and static field inhomogeneities, limitations in available or desired rf field strengths (e.g., for reduction of sample heating), spread in resonance offsets or coupling parameters, variations in spin systems etc. to meet the actual experimental conditions as close as possible. The paper provides a brief account on the relevant theory and in particular the computational interface relevant for optimization of state-to-state transfer (on the density operator level) and the effective Hamiltonian on the level of propagators along with several representative examples within liquid- and solid-state NMR spectroscopy.     

Crystalline silicon solar cells with high resistivity emitter

The paper presents a part of research targeted at the modification of crystalline silicon solar cell production using screen-printing technology. The proposed process is based on diffusion from POCl₃ resulting in emitter with a sheet resistance on the level of 70 Ω/□ and then, shaped by high temperature passivation treatment. The study was focused on a shallow emitter of high resistivity and on its influence on output electrical parameters of a solar cell. Secondary ion mass spectrometry (SIMS) has been employed for appropriate distinguishing the total donor doped profile. The solar cell parameters were characterized by current-voltage characteristics and spectral response (SR) methods. Some aspects playing a role in suitable manufacturing process were discussed. The situation in a photovoltaic industry with emphasis on silicon supply and current prices of solar cells, modules and photovoltaic (PV) systems are described. The economic and quantitative estimation of the PV world market is shortly discussed.     

Localization and delocalization of energy in a Peyrard-Bishop chain

This paper studies energy localization conditions in lattices of the type proposed by Peyrard and Bishop. Homogeneous and inhomogeneous lattices are analyzed and the role of interfaces in the latter is emphasized. Simulations allowed us to identify critical energy values for the existence of localization. After a certain energy value, it is possible to observe the loss of energy localization along the chain.     

Nonextensivity at the edge of chaos of a new universality class of one-dimensional unimodal dissipative maps

We introduce a new universality class of one-dimensional unimodal dissipative maps. The new family, from now on referred to as the (z₁, z₂)-logarithmic map, corresponds to a generalization of the z-logistic map. The Feigenbaum-like constants of these maps are determined. It has been recently shown that the probability density of sums of iterates at the edge of chaos of the z-logistic map is numerically consistent with a q-Gaussian, the distribution which, under appropriate constraints, optimizes the nonadditive entropy S_q. We focus here on the presently generalized maps to check whether they constitute a new universality class with regard to q-Gaussian attractor distributions. We also study the generalized q-entropy production per unit time on the new unimodal dissipative maps, both for strong and weak chaotic cases. The q-sensitivity indices are obtained as well. Our results are, like those for the z-logistic maps, numerically compatible with the q-generalization of a Pesin-like identity for ensemble averages.     

Entanglement generation in a two-mode single-atom laser

We present a method of generating two-mode single atom laser based on the nonresonant interaction of a three-level Λ type atom in a two-mode cavity with three strong classical driving fields. An analytical solution for this effective dynamics under the presence of the cavity losses is obtained, which allow us to analyze the entanglement properties and the photon statistics of the two cavity modes exactly. It is also shown that the possible generation of the two-mode entangled coherent states in the transient regime after the atomic measurement.     

多光束激光外差高精度测量玻璃厚度的方法

利用基于激光外差测量技术和激光多普勒技术的非接触式多光束激光外差测量方法,得到了光电探测器输出电流的谐波表达式.讨论了该测量方法用于玻璃厚度超精密测量的可行性及理论依据,并利用Matlab软件对不同情况进行了仿真实验.结果表明：该方法在不同入射角时测量平板玻璃厚度最大的误差为0.3%,明显比其他测量方法精度高. 关键词： 外差探测 多光束激光外差 激光多普勒技术 非接触式测量     

基于布拉格反射镜的X射线多色单能成像谱仪

报道了一种基于布拉格反射镜的多色单能成像谱仪研制工作,谱仪由针孔阵列、布拉格反射镜和CCD相机组成.大约有300个微孔的针孔阵列板置于布拉格镜前用于空间成像,通过布拉格反射镜的单色化,投射到CCD上的数百个小孔成像沿色散方向获得了能量分辨.经过图像处理,可以还原得到目标的多色单能二维成像.根据采用的布拉格分光元件和图像还原方法,谱仪的能量分辨达到了50—200（λ/Δλ）;针孔成像的空间分辨优于10 μm.同时还为该谱仪开发了专门的单能图像重建软件及图像数据后处理软件,可以在任意选择的窄能带内还原准单能图像.并重点介绍了该谱仪的优化设计、获得的技术指标以及专门研制的超短周期（2.5 nm）X射线W/B₄C多层镜. 关键词： X射线光学 诊断技术 布拉格反射镜 X射线多层镜     

基于白光LED照明光源的室内VLC系统

LED照明与可见光通信技术相结合,构建出基于LED可见光无线通信系统。对室内VLC(Visible Light Communication)系统的白光LED光源特性和系统信道模型分析,提出照明光源布局设计与接收光功率分布的关系;对强度调制直接检测方式的室内VLC系统中信噪比和多径效应引起的码间串扰分析,提出采用光分集接收技术克服码间串扰和提高信噪比,并给出光检测器阵列布局的模型。建立VLC系统仿真模型,给出OOK-NRZ (On-Off Keying & Non-Return Zero)和OOK-RZ(On-Off Keying & Return Zero)调制方式的误码率和均方根时延扩展之间的关系曲线。仿真结果表明,接收光功率相同时,均方根时延扩展时间大于1.0 ns时,OOK-RZ特性优于OOK-NRZ。     

低反轰多腔热阴极微波电子枪物理设计

 为了开展基于自由电子激光的紧凑型太赫兹源技术研究,获得高品质（强流、低能散、低发射度）电子束,提出了一个低反轰双路微波馈入多腔热阴极微波电子枪的设计方案。用两路独立微波馈入激励微波电子枪,一路由首腔馈入激励首腔和实现阴极表面建场引出电子,另一路由后续腔馈入并通过腔间耦合激励各腔。两路微波互不耦合,通过移相器实现首腔和第2腔之间的相移连续可调。理论模拟结果表明:在一个射频周期内,热阴极微波电子枪的电子反轰功率约8 kW,平均反轰功率仅为1.2 W（重复频率25 Hz和脉宽6 μs）。