生物传感器芯片拓展神经科学

德国Infineon技术公司和马克斯普朗克生化研究所(MPI)成功地把一种新研制的生物传感器芯片和活神经细胞连接起来,读取神经细胞产生的电信号。这个在最近在旧金山召开的国际固态电路会议上发布并命名为Neuro-Chip的芯片有望使神经生物和神经化学研究人员获得对人体神经细胞、神经组织和有机神经网络的生物功能的检测活性神经组织的电信号(b)Neuro-Chip新认识。此外,该芯片还可以实现用活神经细胞试验制药化合物,将有助于开发新药。Infineon负责半导体技术,MPI负责神经细胞和芯片的连接。第一批试验测量了蜗牛脑神经细胞发出的电信号。N…     

Some recent advances in fibre-optic sensors

Fibre-optic sensor technology provides a means of performing sensing functions in hostile environments, such as explosive or high electromagnetic-interference-prone areas, whilst also offering advantages in terms of convenience of application. For these reasons fibre-optic sensors are of great interest to large sections of the industrial and military community. The authors present a selection of the sensor systems from Plessey Research and which illustrate this wide interest. The fibre-optic gas sensor and the fibre-optic distributed temperature sensor are examples of sensors with general industrial interest. The analogue spectral-filtering sensor system and the fibre-optic gyroscope are of interest to the aerospace industry. The hydrophone has potential naval applications whilst fibre-optic evanescent field sensors have an attraction to medical and industrial users. For each of these sensor types the principle of operation and the demonstrated performance are described and the current state of development commented on     

Some recent work in artificial intelligence

This paper will review certain approaches to artifical intelligence research--mainly work done since 1960. An important area of research involves designing a machine that can adequately improve its own performance as well as solve other problems normally requiring human intelligence. Work in heuristic programming that seems most relevant to this goal will be discussed at length. Important subproblems are devising techniques for self-improvement, the general problem of deciding what task to best work on next in a network of tasks, and the general problem of how to mechanize learning or inductive inference. Some work in linguistics and pattern recognition is directly concerned with the induction problem. Another area of research that will be treated is simulation of organic evolution.     

瑞士微光学的研究焦点及最新进展

Micro-optics and diffractive optics have a long tradition in Switzerland, in particular at the Institute of Microtechnology, University of Neuchátel (IMT-Uni NE) and at CSEM's Photonics Division in Zurich (formerly PSI / RCA Laboratories, Zurich). Driven by the pioneering work of these institutesand strongly supported by the Swiss Priority Program OPTIQUE during 1993～1999, micro-optics has penetrated into Swiss industry and has resulted in a number of start-up companies. Today, microoptical elements and design services are available from a multitude of Swiss companies and facilities,including CSEM, Heptagon, Colibrys, Suss Micro-Optics Neuchátel, and Leister Technologies.     

Some recent advances in integrated crystal filters

Integrated crystal filters-monolithic, tandem monolithic, and hybrid monolithic (polylithic) quartz crystal filters-are widely used in HF, VHF, UHF, and satellite communications equipments, in both commercial and military, in telephone FDM equipment, and in a number of other applications including frequency synthesizers and airborne navigation aids. Frequencies range from 5 to 180 MHz and occasionally to 250 MHz. Maximum inductorless bandwidths are usually 0.25 to 0.35 percent of center frequency below about 30-35 MHz and less at higher frequencies where overtones must be used. In the past decade, piezoelectric resonator theory has been extended to model accurately the linear and nonlinear behavior of monolithic filter devices. While most integrated crystal filters are all-pole networks, techniques for the design of filters with real and complex frequency transmission zeros are finding increasing application. A number of examples of current production filters are presented.     

Weaknesses in some recent key agreement protocols

B. Arazi ( see ibid., vol. 29, no. 11, p. 966-7, 1993 ) recently proposed a way to integrate the DSS (digital signature standard) to the Diffie-Hellman key exchange system to obtain an authenticated key establishment mechanism for secret session keys. The authors point out the following weakness in the Arazi system: if one key is compromised then the others will be disclosed as well. A similar weakness appears also in another recently presented key distribution system     

Some recent developments in microstrip antenna design

The fundamental radiation mechanism occurring at an open-circuit discontinuity is discussed to reveal limitations on bandwidth, efficiency, and sidelobe level control inherent in microstrip antennas, based on resonator action. Extraneous radiation from feed transitions is also assessed and shown to be a problem in some cases. Novel two-dimensional arrays using resonant elements are described which illustrate these performance limitations. In contrast, a nonresonant circularly polarized spiral element has a very wide bandwidth at the expense of lower efficiency. Other designs are then noted to show how a particular parameter or aspect can be optimized for antenna applications demanding choice of polarization, frequency scanning, log periodic behavior, low angle radiation, and integration with circuitry on a common substrate.     

Some recent developments in RCS measurement techniques

Three distinct methods of making high-range resolution radar cross-section (RCS) measurements are discussed. Comparisons are drawn for nanosecond pulse, FM/CW, and frequency-stepping methods of measuring location and magnitude of discrete scattering sources. The effects of using wide bandwidth transmissions on RCS amplitude level and fine structure are quantitatively estimated, and analytical results are presented. The three techniques are effective and yield the desired information about the magnitude and location of discrete scattering sources. Minor differences in data format and convenience of operation are noted, and it is concluded that a need for additional investigation of wide-band scattering phenomena is necessary.     

Highlights in recent wireless power IC research

<正>Wireless power transfer (WPT) has been a popular topic in power integrated circuit (IC) designs in the past decade. As slogan "cutting the last wire" presented in ISSCC’15^[1], WPT is poised to take over many wired power deliveries applications today, just like what happened to wireless communication nowadays. Over the years,     

Some recent developments in the audion receiver

The action of the audion as a detector and simple amplifier is explained, with the method of verification of the theory by means of oscillograms. To reinforce the oscillations in the grid circuit two methods are employed: first, to couple the grid circuit to the wing circuit and arrange the latter to permit audio frequency currents to pass freely in it; and second, to use a large inductance in the wing circuit, thereby tuning it to the incoming frequency (in conjunction with the capacity between the filament and wing in the audion itself). Both methods may be used together. Various methods of coupling grid and wing circuits are shown. Methods of combined audio and radio-frequency amplification are described. The audion, being a generator of alternating current of any desired frequency, can be used as a beat receiver. A steady audion generator of regular groups of radio frequency oscillations is illustrated. Various methods of audio frequency tuning permitting high selectivity are possible. By the use of two audions in cascade, amplifications as high as 1000 are attainable. The cascade systems can be arranged so as to operate both audions either synchronously or nonsynchronously. As an alternative to beat reception of sustained wave signals, an arrangement is explained wherein the amplifying ratio of a repeating audion is varied periodically at an audio frequency. Coupled to this system is a simple audion detector. Musical signals of any desired pitch are thus obtained. It is found that static of large amplitude nearly always decreases the wing current, while signal (with beat reception) alternately increases and decreases it. A system of circuits is described whereby this fact is taken advantage of in balancing out static while retaining an additive response to signals, thus effecting an elimination of static to a considerable extent. Finally, instances of long distance stations received and interference overcome in practice are given.     

Design for good matching in multichannel low-noise amplifier for recording neuronal signals in modern neuroscience experiments

The paper reports on the design of a prototype 16-channel ASIC for readout of signals from live neuronal systems. Single channel comprises a low-noise amplifier and a low-frequency pass-band filter. The amplifier design optimised with respect to noise and power consumption is discussed. The design of a continuous-time high-pass filter with lower cut-off frequency as low as 20 Hz, which is suitable for realisation in a CMOS process, is presented. Special attention is paid to uniformity of analogue parameters in the multichannel IC. Channel matching is evaluated by Monte Carlo simulation. The design has been fabricated in a 0.7 μm CMOS process and measurements of basic parameters and characteristics have been performed for the prototypes. Good agreement between the simulation and measurements has been achieved for single channel parameters as well as for channel matching. The obtained results on channel matching are discussed with respect to design reliability and production yield.     

Testing for statistical significance in bispectra: a surrogate data approach and application to neuroscience

Interactions among neural signals in different frequency bands have become a focus of strong interest in neuroscience. Bispectral analysis, a type of higher order spectral analysis, provides us with the ability to investigate such nonlinear interactions. Based on the fact that the bispectrum of a linear Gaussian process is zero, a surrogate data method was proposed to test the null hypothesis that the original data were generated by a linear Gaussian process. The method was first tested on two simulation examples. It was then applied to local field potential recordings from a monkey performing a visuomotor task. The analysis reveals nonzero bispectra for beta and gamma band activities in the premotor cortex. The rigorous statistical framework proves essential in establishing these results.     

A dispersion formula satisfying recent requirements in microstripCAD

A dispersion formula ϵ^*_eff(f)=ϵ^* -{ϵ^*-ϵ^*_eff(0)}/{1+( f/f₅₀)^m}, for the effective relative permittivity ϵ^*_eff(f) of an open microstrip line is derived for computer-aided design (CAD) use. The 50% dispersion point (the frequency f₅₀ at which ϵ^*_eff(f₅₀)={ϵ ^*+ϵ^*_eff(0)}/2}) is used a normalizing frequency in the proposed formula, and an expression for f₅₀ is derived. To obtain the best fit of ϵ ^*_eff(f) to the theoretical numerical model, the power m of the normalized frequency in the proposed formula is expressed as a function of width-to-height ratio w/ h for w/h⩾0.7 and as a function of w /h, f₅₀, and f for w/h⩽0.7. The present formula has a high degree of accuracy, better than 0.6% in the range 0.1<w/h⩽10, 1<ϵ^*⩽128, and any height-to-wavelength ratio h/λ₀     

Topics in recent studies with high-voltage electron microscopes

In this article, topics in recent studies with high-voltage electron microscopes (HVEMs) are reviewed. High-voltage electron microscopy possesses a number of advantages that cannot be afforded by conventional electron microscopy, thus providing a unique microscopy technique in both materials science and biological science. One of these advantages is the capability of continuously observing phenomena using a variety of electron microscopy techniques simultaneously with the introduction of the displacement of atoms from lattice points. This has enabled in-depth studies on such fundamental subjects as the crystalline-to-amorphous-to-crystalline transition, the motion properties of point defects and the one-dimensional diffusion of dislocation loops. Electron tomography studies using HVEMs take advantage of the large observable thickness of a specimen. In addition, by combining different advantages, a number of advanced applications in materials science have been carried out, including analyses of the atomic structure of a reduction-induced reconstructed surface and the atomic mechanism behind the self-catalytic vapor-liquid-solid growth of an oxide nanowire. As long as excellent and invaluable studies that cannot be carried out without HVEMs appear in succession, it is necessary to make the utmost efforts to improve these microscopes.     

近年来印制板自动化设备发展趋势综述

文章通过综述近年来印制板企业引进自动化设备形势和使用案例,试图揭示其中的原因和自动化设备发展的趋势;同时,还指出了国产自动化设备普遍存在的主要问题。     

Quadratic solitons: recent developments

Multicolor optical solitons mediated by quadratic nonlinearities have been observed experimentally during the last few years in a variety of materials and geometries in a number of laboratories around the world. Today, many of the basic properties of the corresponding soliton families are theoretically well established. Nevertheless, experiments continuously reveal new surprises, and the topic is entering new theoretical and experimental territories. In this paper, we briefly outline the key features of the quadratic solitons and overview the latest developments.