The progress in understanding wafer-fused vertical-cavity lasers and improvements in fabrication techniques have led to the realization of the first room-temperature continuous-wave operating 1.54-/spl mu/m vertical-c...
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The progress in understanding wafer-fused vertical-cavity lasers and improvements in fabrication techniques have led to the realization of the first room-temperature continuous-wave operating 1.54-/spl mu/m vertical-cavity lasers. By demonstrating continuous-wave operation at room temperature using vertical-cavity lasers fabricated by two wafer fusion steps, we have shown that wafer fusion is a viable technique. The lasers comprise strain compensated InGaAsP quantum-well active layers sandwiched between two AlGaAs/GaAs quarter-wave mirrors. Characteristics discussed include cavity losses, the gain-current density relationship, and voltage-current characteristics.
Information technology deployment in its many forms is the dominant technology force in the nineties. So much of information technology explosion has occurred in a relatively short span of time that one would wonder a...
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Information technology deployment in its many forms is the dominant technology force in the nineties. So much of information technology explosion has occurred in a relatively short span of time that one would wonder about what type of paradigm shift to anticipate in the ways these technologies are utilized in the practice of biomedical discipline both in the short and long term future. Collaborative medicine, nationally and globally oriented Patient-Physician-Provider (PPP) electronic health care paradigms and collaborative biomedical research and education possibilities using distributed system capabilities over high speed networks and new multimedia video conferencing technologies, are all on the near-horizon. The creation of "collaboratories" seen as "Centers without Walls" today enables biomedical researchers to do their work without being bound by geographic location. In parallel to the emergence of information technology tools, a new era of dramatic surges in computer power is unveiled with capabilities to explore solutions to some of the most complex biomedical problems. These resources can be shared by national and international researchers and educators via high speed networks. This paper will discuss the latest developments in the emerging field of biomedical information technology and presents a critical evaluation of some of the major issues that need to be addressed prior to effective implementation of these technologies in both clinical and research environments.
The authors present here a complete three-dimensional molecular model structure of the ternary complex (Enzyme-DNA-dNTP) of human immunodeficiency virus-type 1 reverse transcriptase (HIV-1 RT) using high performance c...
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The authors present here a complete three-dimensional molecular model structure of the ternary complex (Enzyme-DNA-dNTP) of human immunodeficiency virus-type 1 reverse transcriptase (HIV-1 RT) using high performance computer simulation and molecular modeling techniques. The Ca coordinates of the crystal structure of HIV-1 RT-DNA binary complex as well as biochemical properties of a number of mutant enzymes were used as the basis to model build a prepolymerase ternary complex in which Mg/sup 2+/ ions are also accommodated. The side chains of amino acid residues interacting with the template and primer strands and those stabilizing the dNTP and Mg/sup 2+/ ions in the active site pocket are clearly elucidated in the model. The structural information provided by this model should be useful in understanding the polymerase reaction mechanisms and should permit structure based drug design against HIV-1 RT.
作者：
Zhuang, XPKoshiba, MTsuji, YFaculty of Engineering
Hokkaido University Sapporo Japan 060 Graduated from the Department of Communication Engineering
Guellin Electronic Institute China in 1986. She received her M.S. degree from Hokkaido University in 1991 and was admitted to the doctoral program. She has been engaged in research on the optimum design of magnetooptic waveguides for nonreciprocal optical devices. Graduated in 1971 from the Department of Electronic Engineering
Hokkaido University where he received his M.S. degree in 1973 and his Dr. of Eng. degree in 1976. In 1976 he became a Lecturer in the Department of Electronic Engineering Kitami Institute of Technology where he was promoted to Associate Professor in 1977. In 1979 he became an Associate Professor at Hokkaido University where he was promoted to Professor in 1987. He has been engaged in research on optical and wave electronics. In 1987 he received a Best Paper Award. He is the author ofFundamentals of Finite Element Method of Optics and Waves(Morigkata Publ.)Optical Waveguide Analysis(Asakura Publ.)Optical Waveguide Analysis(McGraw-Hill Book Co.) andOptical Waveguide Theory by the Finite Element Method(KTK Scientific Publishing/Kulwer Academic Publishers). He is also co-author of one book and has written chapters in six other books. He is a member of the Institute of Television Engineers of Japan the Institute of Electrical Engineers of Japan the Japan Society for Simulation Technology the Japan Society for Computational Methods in Engineering and the Japan Society of Applied Magnetics and Mechanics. He is also an IEEE Senior Member. Graduated in 1991 from me Department of Electronic Engineering
Hokkaido University where he received his M.S. degree in 1993. He is currently in the doctoral program. He has been engaged in research on quantum wave phenomena and computer-aided design of optical and quantum effect devices.
To evaluate nonreciprocal mode conversion characteristics in a magnetooptic channel waveguide, a finite element analysis based on the scalar wave approximation is formulated for the first time. A simple iterative calc...
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To evaluate nonreciprocal mode conversion characteristics in a magnetooptic channel waveguide, a finite element analysis based on the scalar wave approximation is formulated for the first time. A simple iterative calculation method is conceived for solution of the nonlinear eigenvalue equations finally obtained in which the two polarizations are coupled. Specifically, the maximum isolation ratio in the mode-conversion-type magnetooptic rib guide was evaluated and the validity of the method is confirmed by comparison with published experimental results.
作者：
Tsuji, YKoshiba, MTanabe, TFaculty of Engineering
Hokkaido University Sapporo Japan 060 Graduated in 1991 from the Department of Electronic Engineering
Hokkaido University and received his M.S. degree in 1993. He is currently working toward a doctoral degree. He has been engaged in research on the computer-aided design of optical and quantum-wave phenomena and quantum-effect devices. Graduated in 1971 from the Department of Electronic Engineering
Hokkaido University and received his M.S. and Dr. of Eng. degree in 1973 and 1976 respectively. In 1976 he became a Lecturer at Kitami Institute of Technology where he was promoted to an Associate Professor in 1977. In 1979 he became an Associate Professor in the Department of Electronic Engineering Hokkaido University where he was promoted to Professor in 1987. He has been engaged in research on opto- and wave-electronics. In 1987 he received a Best Paper Award. He is the author ofFoundations of Finite Element Method for Opto- and Wave-Electronics(Morikita Publ.)Optical Waveguide Analysis(Asakura Publ.)Optical Waveguide Analysis(McGraw-Hill Book Co.) andOptical Waveguide Theory by the Finite Element Method(KTK Scientific Publishers/Kluwer Academic Publishers). He has co-authored one book and written Graduated in 1995 from the Department of Electronic Engineering
Hokkaido University and is currently in the Master's program. He has been engaged in research on opto- and wave-electronics.
To the best of the knowledge of the authors, the formulation is carried out for the first time on the finite-element beam-propagation method for the analysis of the magnetooptic waveguide in which the structure varies...
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To the best of the knowledge of the authors, the formulation is carried out for the first time on the finite-element beam-propagation method for the analysis of the magnetooptic waveguide in which the structure varies along the propagation direction. The present method is applicable not only to the case in which refractive index difference is small but also to the case for the TE mode and the TM mode propagating in a waveguide with a large refractive index difference. To suppress the spurious reflection from the computational window edges, the transparent boundary condition is applied.
Preliminary radio frequency (RF) field experiments were conducted to evaluate the performance of smart antenna systems for code-division multiple access (CDMA) systems. Besides conventional multipath fading problems, ...
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Preliminary radio frequency (RF) field experiments were conducted to evaluate the performance of smart antenna systems for code-division multiple access (CDMA) systems. Besides conventional multipath fading problems, CDMA schemes are subject to near-far problems. The IS-95 CDMA system uses a 1/3 convolutional encoder and an interleaver to mitigate the fading problem and uses feedback power control schemes to equalize the powers of all the uplink co-channel signals. We evaluate the performance of the IS-95 standard implemented on a smart antenna system in a slow-fading environment. In particular, we evaluate the effects of imprecise power control, convolutional coding, and different beamforming techniques for a CDMA smart antenna system. Our results show that the smart antennas are not so sensitive to imperfect power control and that the optimal (Wiener) beamforming technique outperforms the simple beamforming approach. The most interesting result is that the effect of convolutional coding is not so significant for a smart antenna system than for an single antenna system. Based on our limited experimental results, we found that the 3 times bandwidth dedicated to the 1/3 convolutional encoding is better used to increase the spreading factor in a CDMA smart antenna system, leading to reduced cost and perhaps better performance.
This paper describes the implementation of transmission-line matrix (TLM) method algorithms on a massively parallel computer (DECmpp 12000), the technique of distributed computing in the UNIX environment, and the comb...
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This paper describes the implementation of transmission-line matrix (TLM) method algorithms on a massively parallel computer (DECmpp 12000), the technique of distributed computing in the UNIX environment, and the combination of TLM analysis with Prony's method as well as with autoregressive moving average (ARMA) digital signal processing for electromagnetic field modelling. By combining these advanced computation techniques, typical electromagnetic field modelling of microwave structures by TLM analysis can be accelerated by a few orders of magnitude.
The subband adaptive system, where the idea of the filter bank is applied to the adaptive filter, has a feature that a higher-order adaptation can be reduced to lower-order adaptations. The reduction of the order of t...
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The subband adaptive system, where the idea of the filter bank is applied to the adaptive filter, has a feature that a higher-order adaptation can be reduced to lower-order adaptations. The reduction of the order of the adaptive filter is related closely to the number of channels and the decimation ratio. The order of adaptive digital filter (ADF) is decreased greatly when the number of subbands is increased, and the decimation ratio is increased up to the maximum value. Then, however, the number of coefficient-updates per unit time is decreased, which results in the deterioration of the convergence Speed. From such a viewpoint, this paper discusses a method to improve the convergence speed, which is deteriorated in the subband adaptive system, due to the decimation. The idea of the proposed method is to utilize effectively the data which have been discarded in the decimation process and to improve the convergence speed. It is called the multirate repeating method. As the first step, the multirate repeating method is applied to the conventional subband adaptive system and the convergence speed is improved. Then a subband adaptive system is introduced in which the multirate repeating method can be utilized more effectively. As a result, a faster convergence is realized while retaining the ADF order-reduction effect, which is an advantage of the subband adaptive system.
Contents and implementation of a computer laboratory for undergraduate electromagnetics are described. The laboratory consists of four 3-hour sessions covering vector calculus, Maxwell's equations (integral and di...
Contents and implementation of a computer laboratory for undergraduate electromagnetics are described. The laboratory consists of four 3-hour sessions covering vector calculus, Maxwell's equations (integral and differential forms), wave propagation in materials, and wave behavior at planar interfaces. Each session contains theory (in the Help file), animations (where relevant) and a quiz. The program runs on IBM compatible 486-based PCs in a Windows environment and uses the Borland C ++ 4.0 compiler.
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