偏置模式波前传感器光强信息提取及输出信号对比分析

 在小像差近似下,对偏置模式波前传感器进行了理论分析,明确了该传感器的适用条件,对比分析了3种信息提取方式和3种传感器信号输出方式的优劣。针对Zernike像差模式,数值模拟研究了传感器对单阶和多阶模式的响应特性。结果表明,畸变波前中与偏置模式相同或相关的模式之间有响应,但传感器对各阶Zernike模式的响应灵敏度不同,而且不相关模式的存在对传感器输出信号和灵敏度均有影响。     

偏置模式波前传感器光强信息提取及输出信号对比分析

在小像差近似下,对偏置模式波前传感器进行了理论分析,明确了该传感器的适用条件,对比分析了3种信息提取方式和3种传感器信号输出方式的优劣。针对Zernike像差模式,数值模拟研究了传感器对单阶和多阶模式的响应特性。结果表明,畸变波前中与偏置模式相同或相关的模式之间有响应,但传感器对各阶Zernike模式的响应灵敏度不同,而且不相关模式的存在对传感器输出信号和灵敏度均有影响。     

Response of the cat eardrum to static pressures: mobile versus immobile malleus

A phase-shift shadow moiré interferometer was used to measure the shape of the cat eardrum with a normal mobile malleus and with an immobile malleus as it was cyclically loaded with static middle-ear pressures up to +/-2.2 kPa. The shape was monitored throughout the loading and unloading phases, and three complete cycles were observed. The mobile-manubrium measurements were made in five ears. In three ears, the malleus was then immobilized with a drop of glue placed on the head of the malleus. Eardrum displacements were calculated by subtracting shape images pixel by pixel. The measurements are presented in the form of gray-level full-field shape and displacement images, of displacement profiles, and of pressure-displacement curves for selected points. Displacement patterns with a mobile malleus show that pars-tensa displacements are larger than manubrial displacements, with the maximum pars-tensa displacement occurring in the posterior region in all cats except one. Displacements vary from cycle to cycle and display hysteresis. For both the mobile-malleus and immobile-malleus cases, the eardrum response is nonlinear. The response is asymmetric, with lateral displacements being larger than medial displacements. With a mobile malleus, manubrial displacements exhibit more pronounced asymmetry than do pars-tensa displacements.     

Seeing pitch: visual information for lexical tones of Mandarin-Chinese

Mandarin perceivers were tested in visual lexical-tone identification before and after learning. Baseline performance was only slightly above chance, although there appeared to be some visual information in the speakers' neck and head movements. When participants were taught to use this visible information in two experiments, visual tone identification improved significantly. There appears to be a relationship between the production of lexical tones and the visible movements of the neck, head, and mouth, and this information can be effectively used after a short training session.     

A mobile one-sided NMR sensor with a homogeneous magnetic field: the NMR-MOLE

A new portable NMR sensor with a novel one-sided access magnet design, termed NMR-MOLE (MObile Lateral Explorer), has been characterised in terms of sensitivity and depth penetration. The magnet has been designed to be portable and create a volume with a relatively homogeneous magnetic field, 15,000 ppm over a region from 4 to 16 mm away from the probe, with maximum sensitivity at a depth of 10 mm. The proton NMR frequency is 3.3 MHz. We have demonstrated that with this approach a highly sensitive, portable, unilateral NMR sensor can be built. Such a design is especially suited for the characterisation of liquids in situations where unilateral or portable access is required.     

一种移动式遥测天然气泄漏检测仪

天然气管道泄漏检测对人员安全、环境保护以及国家财产安全等具有重要的意义,但是,由于管线跨越地域广阔,操作工况以及环境情况复杂,致使管线的泄漏检测存在困难。文章介绍了一种基于波长扫描差分吸收光谱技术的移动式遥测天然气泄漏检测仪。针对遥测回波吸收光谱特性,提出了基于小波变换的改进型软阈值小波去噪方法,实验分析能够提高系统信噪比3倍多,同时在遥测光强为530nA时,可达到的最小遥测灵敏度为80ppm.m,系统采用波长扫描差分吸收光谱技术成功实现天然气泄漏的定量遥测与准确定位,具有快速、准确、智能及安全等特点。     

Imprinting modulates processing of visual information in the visual wulst of chicks

Background

Results of the Women's Health Initiative Memory Study (WHIMS) raised concerns regarding the timing and formulation of hormone interventions. Conjugated equine estrogens (CEE), used as the estrogen therapy in the WHIMS trial, is a complex formulation containing multiple estrogens, including several not secreted by human ovaries, as well as other biologically active steroids. Although the full spectrum of estrogenic components present in CEE has not yet been resolved, 10 estrogens have been identified. In the present study, we sought to determine which estrogenic components, at concentrations commensurate with their plasma levels achieved following a single oral dose of 0.625 mg CEE (the dose used in the WHIMS trial) in women, are neuroprotective and whether combinations of those neuroprotective estrogens provide added benefit. Further, we sought, through computer-aided modeling analyses, to investigate the potential correlation of the molecular mechanisms that conferred estrogen neuroprotection with estrogen interactions with the estrogen receptor (ER).

Results

Cultured basal forebrain neurons were exposed to either β-amyloid_25–35 or excitotoxic glutamate with or without pretreatment with estrogens followed by neuroprotection analyses. Three indicators of neuroprotection that rely on different aspects of neuronal damage and viability, LDH release, intracellular ATP level and MTT formazan formation, were used to assess neuroprotective efficacy. Results of these analyses indicate that the estrogens, 17α-estradiol, 17β-estradiol, equilin, 17α-dihydroequilin, equilinen, 17α-dihydroequilenin, 17β-dihydroequilenin, and Δ^8,9-dehydroestrone were each significantly neuroprotective in reducing neuronal plasma membrane damage induced by glutamate excitotoxicity. Of these estrogens, 17β-estradiol and Δ^8,9-dehydroestrone were effective in protecting neurons against β-amyloid_25–35-induced intracellular ATP decline. Coadministration of two out of three neuroprotective estrogens, 17β-estradiol, equilin and Δ^8,9-dehydroestrone, exerted greater neuroprotective efficacy than individual estrogens. Computer-aided analyses to determine structure/function relationships between the estrogenic structures and their neuroprotective activity revealed that the predicted intermolecular interactions of estrogen analogues with ER correlate to their overall neuroprotective efficacy.

Conclusion

The present study provides the first documentation of the neuroprotective profile of individual estrogens contained within the complex formulation of CEE at concentrations commensurate with their plasma levels achieved after an oral administration of 0.625 mg CEE in women. Our analyses demonstrate that select estrogens within the complex formulation of CEE contribute to its neuroprotective efficacy. Moreover, our data predict that the magnitude of neuroprotection induced by individual estrogens at relatively low concentrations may be clinically undetectable and ineffective, whereas, a combination of select neuroprotective estrogens could provide an increased and clinically meaningful efficacy. More importantly, these data suggest a strategy for determining neurological efficacy and rational design and development of a composition of estrogen therapy to alleviate climacteric symptoms, promote neurological health, and prevent age-related neurodegeneration, such as AD, in postmenopausal women.     

Imprinting modulates processing of visual information in the visual wulst of chicks

Background  

Imprinting behavior is one form of learning and memory in precocial birds. With the aim of elucidating of the neural basis for visual imprinting, we focused on visual information processing.     

The DIVAM sequence: selective excitation of signals from both rigid and mobile domains in a fluoropolymer

Simulations have been carried out on z-magnetizations produced by (and hence of the resulting spectra from) the dipolar filter (DF) and the recently suggested "Discrimination Induced by Variable-Amplitude Minipulses" (DIVAM) pulse sequences [S. Ando et al., Polymer 42 (2001) 8137; Magn. Reson. Chem. 40 (2002) 97]. The strengths of dipolar interactions have been modelled by introducing different values for transverse relaxation times. The DF case has been extended by allowing the pulse angles to be smaller than 90 degrees. The pulse intervals have also been used as variables. For the DIVAM case, the variables are similarly the minipulse nutation angles and minipulse intervals. The computations show that DIVAM is superior to DF in terms of selectivity for spectra of heterogeneous materials such as semi-crystalline polymers. The effects of the pulse sequences on 19F spectra of poly(vinylidene fluoride) (PVDF) and of a copolymer of vinylidene fluoride and trifluoroethylene (p(VDF/TrFE)) are presented, together with fits of the experimental results by the simulations.     

温度对霍尔位移传感器静态特性的影响

在不同环境温度下,对霍尔位移传感器的静态特性进行了测试.结果表明,随着环境温度的变化,霍尔传感器的静态特性差异明显,从理论上分析了产生差异的原因.并对其应用实例进行了说明.     

Technique for obtaining and processing spectral information with static fourier spectrometer

We propose a technique and algorithm for processing interferograms obtained with a static Fourier spectrometer. Spectra of secondary radiation from certain compounds are obtained in the visible and near-UV spectral ranges upon excitation by different radiation sources. We present and discuss results of experimental data processing.     

Securing information display by use of visual cryptography

We propose a secure display technique based on visual cryptography. The proposed technique ensures the security of visual information. The display employs a decoding mask based on visual cryptography. Without the decoding mask, the displayed information cannot be viewed. The viewing zone is limited by the decoding mask so that only one person can view the information. We have developed a set of encryption codes to maintain the designed viewing zone and have demonstrated a display that provides a limited viewing zone.     

Estimation of spatially distributed processes using mobile sensor networks with missing measurements

This paper investigates the estimation problem for a spatially distributed process described by a partial differential equation with missing measurements.The randomly missing measurements are introduced in order to better reflect the reality in the sensor network.To improve the estimation performance for the spatially distributed process,a network of sensors which are allowed to move within the spatial domain is used.We aim to design an estimator which is used to approximate the distributed process and the mobile trajectories for sensors such that,for all possible missing measurements,the estimation error system is globally asymptotically stable in the mean square sense.By constructing Lyapunov functionals and using inequality analysis,the guidance scheme of every sensor and the convergence of the estimation error system are obtained.Finally,a numerical example is given to verify the effectiveness of the proposed estimator utilizing the proposed guidance scheme for sensors.     

Robustness analysis of static routing on networks

Robustness is one of the crucial properties that needs to be considered in the design of routing strategies on networks. We study the robustness of three typical routing strategies, which are the SP (shortest path), EP (efficient path), and OP (optimal path) strategies, by simulating several different kinds of attacks including random attacks, target attacks and cascading failures on scale-free networks. Results of the average path length, betweenness centrality, network capacity, etc., demonstrate that the EP strategy is more robust than the other two, and the OP strategy is more reliable than the SP strategy in general. However, on the power-grid network, the OP strategy is more resistant against cascading failures than the EP and SP strategies.     

Frequency structure in an electronically tuned Ti:sapphire laser: periodic appearance of static fringes in both homodyne and heterodyne Michelson interferometers

Static interference fringes were observed repeatedly with changes of path difference in both homodyne and heterodyne Michelson interferometers. This unique coherence property of an electronically tuned Ti:sapphire laser with an intracavity acousto-optic tunable filter (AOTF) has revealed the frequency structure and dynamics of the laser field. The fact that static interference occurred in a heterodyne interferometer with unequal path lengths indicates backscattering of the intracavity laser field, suggesting that Brillouin-enhanced four-wave mixing occurs in the intracavity AOTF.     

光纤温度传感器实验的改进与分析

本文利用价格低廉的1310 nm商用光纤分束器、铝箔导热等对光纤温度传感器实验装置进行了改进,并测量了改进后传感器的温度系数,发现改进后的温度系数更加稳定,导热条件对温度系数的测量影响较大.最后对此实验的教学提出了建议.     

Radar sensor network for target detection using Chernoff information and relative entropy

In this paper, we propose to apply information theory to Ultra wide band (UWB) radar sensor network (RSN) to detect target in foliage environment. Information theoretic algorithms such as Maximum entropy method (MEM) and mutual information are proven methods, that can be applied to data collected by various sensors. However, the complexity of the environment poses uncertainty in fusion center. Chernoff information provides the best error exponent of detection in Bayesian environment. In this paper, we consider the target detection as binary hypothesis testing and use Chernoff information as sensor selection criterion, which significantly reduces the processing load. Another strong information theoretic algorithm, method of types, is applicable to our MEM based target detection algorithm as entropy is dependent on the empirical distribution only. Method of types analyzes the probability of a sequence based on empirical distribution. Based on this, we can find the bound on probability of detection. We also propose to use Relative entropy based processing in the fusion center based on method of types and Chernoff Stein Lemma. We study the required quantization level and number of nodes in gaining the best error exponent. The performance of the algorithms were evaluated, based on real world data.     

ITER磁体重力支撑系统的应力强度分析

用ANSYS有限元软件,分析了ITER重力支撑系统的静力情况。采用实体单元建立有限元模型,分析了磁体重量、热载荷、地震和电磁力多种工况下的应力分布及位移变形,获得的最大应力强度和最大位移均在许用应力及允许位移范围内。为进一步优化ITER重力支撑系统提供了重要的参考数据。