A 24-GHz 3.9-dB NF low-noise amplifier using 0.18 /spl mu/m CMOS technology

A 24-GHz low-noise amplifier (LNA) was designed and fabricated in a standard 0.18-/spl mu/m CMOS technology. The LNA chip achieves a peak gain of 13.1 dB at 24 GHz and a minimum noise figure of 3.9 dB at 24.3 GHz. The supply voltage and supply current are 1 V and 14 mA, respectively. To the author's knowledge, this LNA demonstrates the lowest noise figure among the reported LNAs in standard CMOS processes above 20 GHz.     

Tip-induced local anodic oxidation on p-GaAs surface with non-contact atomic force microscopy

Nano-sized oxide structures resulted from localized electrochemical oxidation induced by a negatively biased atomic force microscopy (AFM) tip operated with the non-contact mode were fabricated on p-GaAs(1 0 0) surface. The geometrical characteristics of the oxide patterns and their dependences on various fabrication parameters, e.g., the anodization time, the biased voltages, the tip scanning rates, as well as the formation mechanism and relevant growth kinetics are investigated. Results indicate that the height of the protruded oxide dots grow exponentially as a function of time in the initial stage of oxidation and soon reaches a maximum height depending linearly with the anodized voltages, in according with the behaviors predicted by space charge limited local oxidation mechanism. In addition, selective micro-Auger analysis of the anodized region reveals the formation of Ga(As)O_x, indicating the prominent role played by the field-induced nanometer-size water meniscus in producing the nanometer-scale oxide dots and bumps on p-GaAs(1 0 0) surface.     

建立基于模型设计文化的最佳策略

本文引入了基于模型设计的概念,突出了其中的一些优点,详细讨论了组织中采用基于模型设计文化的10个最佳策略。这些最佳策略从不同工业领域的公司中收集,包括向基于模型设计的成功或者不成功的过渡。     

A Generalized Markov Sampler

A recent development of the Markov chain Monte Carlo (MCMC) technique is the emergence of MCMC samplers that allow transitions between different models. Such samplers make possible a range of computational tasks involving models, including model selection, model evaluation, model averaging and hypothesis testing. An example of this type of sampler is the reversible jump MCMC sampler, which is a generalization of the Metropolis–Hastings algorithm. Here, we present a new MCMC sampler of this type. The new sampler is a generalization of the Gibbs sampler, but somewhat surprisingly, it also turns out to encompass as particular cases all of the well-known MCMC samplers, including those of Metropolis, Barker, and Hastings. Moreover, the new sampler generalizes the reversible jump MCMC. It therefore appears to be a very general framework for MCMC sampling. This paper describes the new sampler and illustrates its use in three applications in Computational Biology, specifically determination of consensus sequences, phylogenetic inference and delineation of isochores via multiple change-point analysis.     

Feasibility of adding a personal communications network to anexisting fixed-service microwave system

This paper examines the feasibility of adding a personal communication network (PCN) to a frequency band which is already allocated to fixed-service microwave systems. To achieve this goal, spread spectrum techniques are used to spread narrowband PCN signals into wideband. The forward and reverse link performance of PCN users under the influence of the microwave system and the influence of PCN users on the microwave system are both examined. It is proven that spectrum sharing between the PCN network and microwave systems is indeed feasible. Although our analysis is done based upon the consideration of only one microwave system, it can be easily extended to allow the appearance of two or more microwave systems     

News Media Use and Adolescents' Attitudes about Nuclear Issues: An American-Soviet Comparison

Both Soviet and American youth show a great concern about the possible effects of nuclear war, with heavy media users in both countries more optimistic, but the relation was stronger among Soviet students.     

Introduction to the proceedings of the thirteenth symposium on biotechnology for fuels and chemicals

Applied Biochemistry and Biotechnology -     

Multicluster,mobile, multimedia radio network

A multi-cluster, multi-hop packet radio network architecture for wireless adaptive mobile information systems is presented. The proposed network supports multimedia traffic and relies on both time division and code division access schemes. This radio network is not supported by a wired infrastructure as conventional cellular systems are. Thus, it can be instantly deployed in areas with no infrastructure at all. By using a distributed clustering algorithm, nodes are organized into clusters. The clusterheads act as local coordinators to resolve channel scheduling, perform power measurement/control, maintain time division frame synchronization, and enhance the spatial reuse of time slots and codes. Moreover, to guarantee bandwidth for real time traffic, the architecture supports virtual circuits and allocates bandwidth to circuits at call setup time. The network is scalable to large numbers of nodes, and can handle mobility. Simulation experiments evaluate the performance of the proposed scheme in static and mobile environments.This work was supported by the U.S. Department of Justice/Federal Bureau of Investigation, ARPA/CSTO under Contract J-FBI-93-112 Computer Aided Design of High Performance Wireless Networked Systems.     

The structure-activity relationship of inhibitors of serotonin uptake and receptor binding

Summary An analysis of five different datasets of inhibitors of serotonin uptake has yielded quantitative structure/ activity relationships (QSARs) which delineate the role of steric and hydrophobic properties essential for inhibition by phenylethylamine-type analogues.     

High-speed Modulation of InGaAs: Sb-GaAs-GaAsP quantum-well vertical-cavity surface-emitting lasers with 1.27-/spl mu/m emission wavelength

1.27-/spl mu/m InGaAs: Sb-GaAs-GaAsP vertical-cavity surface-emitting lasers (VCSELs) were grown by metal-organic chemical vapor deposition and exhibited excellent performance and temperature stability. The threshold current changes from 1.8 to 1.1 mA and the slope efficiency falls less than /spl sim/35% as the temperature raised from room temperature to 70/spl deg/C. With a bias current of only 5 mA, the 3-dB modulation frequency response was measured to be 8.36 GHz, which is appropriate for 10-Gb/s operation. The maximal bandwidth is measured to be 10.7 GHz with modulation current efficiency factor (MCEF) of /spl sim/5.25 GHz/(mA)/sup 1/2/. These VCSELs also demonstrate high-speed modulation up to 10 Gb/s from 25/spl deg/C to 70/spl deg/C.