The role of the hyperpolarization-activated inward current If in arrhythmogenesis: a computer model study.

Atrial fibrillation is the most common cardiac arrhythmia. Structural cardiac defects such as fibrosis and gap junction remodeling lead to a reduced cellular electrical coupling and are known to promote atrial fibrillation. It has been observed that the expression of the hyperpolarization-activated current If is increased under pathological conditions. Recent experimental data indicate a possible contribution of If to arrhythmogenesis. In this paper, the role of If in action potential propagation in normal and in pathological tissue is investigated by means of computer simulations. The effect of diffuse fibrosis and gap junction remodeling is simulated by reducing cellular coupling nonuniformly. As expected, the conduction velocity decreases when cellular coupling is reduced. In the presence of If the conduction velocity increases both in normal and in pathological tissue. In our simulations, ectopic activity is present in regions with high expression of If and is facilitated by cellular uncoupling. We conclude that an increased If may facilitate propagation of the action potential. Hence, If may prevent conduction slowing and block. Overexpression of If may lead to ectopic activity, especially when cellular coupling is reduced under pathological conditions.     

试论计算机技术在电子商务中的作用

电子商务是市场发展、时代发展的必然趋势,它是一种新型的交易渠道,与人们的生活节奏相符.所谓电子商务,就是指在互联网技术、计算机技术的支持下,在全球范围内,利用网络手段完成等价交换、产品信息交换的一种贸易方式.随着计算机技术的飞速进步与发展,计算机网络技术在电子商务中发挥了重要作用,为人们网上支付、网上购物提供了有利条件.然而在电子商务的发展过程中,人们还需意识到其中潜在的安全隐患问题,及时发现安全隐患,并采取措施解决问题,有利于提高电子商务发展的安全性.     

The effect of nerve cuff geometry on interference reduction: a study by computer modeling

The effect of nonlinearity in the extrafascicular field in tripolar electrode cuffs on interference pick-up was investigated. It was concluded that the interference is sensitive to electrode separation, especially in short cuffs. This suggests that significant improvements can be obtained by placing the end electrodes a few mm from the cuff ends.     

计算机技术对人力资源管理模式的作用探究

随着社会科技的不断进步,信息技术也有了突破性的进展。目前,信息技术已经涉及社会的不同领域,广泛应用于各行各业。尤其是对人力资源管理模式的研究产生了重大的影响。本文就对信息技术和人力资源管理的涵义进行阐述,并且介绍了计算机技术对人力资源管理模式的作用,让人们通过计算机技术的应用,更加了解现代人力资源管理的模式。     

计算机技术对人力资源管理模式的作用探究

随着社会科技的不断进步,信息技术也有了突破性的进展。目前,信息技术已经涉及社会的不同领域,广泛应用于各行各业。尤其是对人力资源管理模式的研究产生了重大的影响。本文就对信息技术和人力资源管理的涵义进行阐述,并且介绍了计算机技术对人力资源管理模式的作用,让人们通过计算机技术的应用,更加了解现代人力资源管理的模式。     

Procedure of creating a reliability-functional model for a chosen computer system

This work conducts a reliability analysis of a complex computer system. Different kinds of inefficiencies in computer systems are described and a procedure of creating a reliability-functional model for these systems is proposed. The analysis has been made for a three-level hierarchic computer network.     

Analysis of firm-level computer investments: a comparative study ofthree Pacific-rim economies

The impact of information technology (IT) on firm level productivity has been a subject of considerable research. Although a number of empirical studies have been reported, results are far from conclusive. Almost all of these studies are based on secondary data collected in the United States, which makes it impossible to compare productivity impacts under different economic and demographic settings. It remains unclear whether empirical findings obtained from US firms are also applicable to firms residing in other parts of the world. To answer this question, an empirical study was conducted to assess the impact of IT investment in firms operating in three economies (Hong Kong, Singapore, and Malaysia) in the Pacific Rim from 1983 to 1991. Our results indicate that while still small as a percentage of total capital compared with the United States, computer capital stock increased substantially in all economies during the period. Our production function estimates suggest that there are positive and excess returns in one of the three economies. Results of the analysis provide the basis to address issues such as national IT policy and the effect of economic dynamics on IT adoption     

Telco 2.0: a new role and business model

Recent market saturation and fierce competition among telcos and other access providers, including cable and wireless operators, are threatening telco's growth potential. Many "traditional" telcos around the world are making all-out efforts to discover new growth momentum not only for the existing market but also for the future market. A new direction to overcome the difficulties is desperately needed. In this situation, what should telcos do in the next five to ten years? How should they change? This article introduces Telco 2.0, which is the telco's new role and business model in the IP world to create customer value. Telcos should first perform their environment analysis, and then based on the results they can implement Telco 2.0 to create new revenue sources and overcome the difficulties. Telcos need to transform themselves into more customer-centric and highly innovative companies, and restore their role as true market leaders. This paper also briefly describes how Telco 2.0 is being implemented in a company, KT     

NETMAN: The design of a collaborative wearable computer system

This paper presents a wearable groupware system designed to enhance the communication and cooperation of highly mobile network technicians. It provides technicians in the field with the capabilities for realtime audioconferencing, transmission of video images back to the office, and contextsensitive access to a shared notebook. An infrared locationtracking device allows for the automatic retrieval of notebook entries depending on the user's current location.     

The anatomy of a portable computer

The Radio Shack TRS-80 Model 100 Portable Computer combines easy-to-use software with an efficient hardware architecture to bring a high level of programming power to the microcomputer user. This paper discusses the product development decisions, the ROM-based application programs, the file manager software, and the hardware features of the Model 100 computer. A prediction of the functionality of a future portable computer is made.     

计算机视频电磁信息泄漏效应研究

基于计算机电磁辐射的实测结果，对计算机视频信号的电磁辐射机理进行建模，利用计算电磁学的方法计算了计算机视频信号的远场电磁辐射；提出了利用FDTD(时域有限差分)计算电磁辐射伴随的噪声衰落的方法，表述了随机噪声的时变和远场特性；最后针对具有20dB噪声的泄漏电磁波进行软件模拟处理，利用同步、滤波、锁相、识别和重构等技术获得了再现的文字图像，研究了电磁信息泄漏现象，讨论了有关的规律。     

On the social role of computer communications

Computer-communication systems appear essential to meeting many needs in our society resulting from greater interdependence and complexity of operation and from rising expectations. There are, in principle, different ways of utilizing them for the same purposes, with radically different social consequences. The choice, which amounts in effect to a social decision, is, in practice, severely restricted by the computer hardware and software and by the communication facilities that happen to be available at the time. The paper discusses some of the pressures that lead to more widespread use of computers in the operation of society and illustrates how specific characteristics of computer-communication systems may influence social trends and, in particular, individual freedom.     

一种新型的FBG压力传感器数值模拟研究

提出一种基于金属圆筒式膜盒感受联杆传递到悬臂梁的组合式FBG压力传感机构,对其压力传感特性进行理论研究.利用双FBG(FBG1、FBG2)产生双反射峰实现温度压力同时区分测量,并且用有限元软件ANSYS进行了二维数值模拟实验.     

Embedding impedance of a millimeter wave Schottky mixer: Scaled model measurements and computer simulations

Using scaled model measurements at 2.5–12 GHz the embedding network of a 3 mm Schottky diode mixer has been developed. The noise performance of a cryogenic millimeter wave receiver was simulated by computer applying the developed equivalent circuit and diode parameters. The effects of impedance match at the fundamental frequency as well as at harmonic frequencies were studied. Also the effect of diode I-V-curve steepness was studied. The calculated results were compared with the experimental noise performance.     

Looking to build a model world: automatic construction of staticobject models using computer vision

Interest in virtual reality and multimedia has provided a great impetus to the development of automatic techniques for building graphical CAD/CAM models of objects and environments by sensing reality itself. The learning of models in this way is essential, particularly in terms of production times and attaining the required high fidelity needed for many applications. Research has produced techniques for extracting full 3D shape models using a variety of sensors and a spectrum of techniques. These include the use of static video cameras, mobile video cameras (e.g. walk through video), multiple camera platforms and/or specialist active range sensors (typically based on laser striping or sonar). This paper introduces the principles and methodologies underlying several of these methods and presents algorithms and examples from systems representative of three major approaches: models from silhouettes, models from active range sensors and, finally, models from passive uncalibrated video sequences     

Low-cost microcomputing: The personal computer and single-board computer revolutions

Personal computing is one of the most revolutionary applications of microprocessors; single-board computing is another. The origins of both applications are traced and current products and services described in a tutorial fashion. Trends are forecasted and conclusions drawn about these two low-cost computing revolutions.     

用计算机细分干涉条纹技术的研究

本文提出了一种对于干涉条纹的变化进行记录和细分的计算机系统。由于采用了一种新的细分标准,使细分干涉条纹更加合理、简便、准确,在文章的最一以实验结果验证了本系统的可靠性。     

Effects of muscle fatigue on the ground reaction force and soft-tissue vibrations during running: a model study

A modeling approach is used in this paper to study the effects of fatigue on the ground reaction force (GRF) and the vibrations of the lower extremity soft tissues. A recently developed multiple degrees-of-freedom mass-spring-damper model of the human body during running is used for this purpose. The model is capable of taking the muscle activity into account by using a nonlinear controller that tunes the mechanical properties of the soft-tissue package based on two physiological hypotheses, namely, "constant force" and "constant vibration." In this study, muscle fatigue is implemented in the model as the gradual reduction of the ability of the controller to tune the mechanical properties of the lower body soft-tissue package. Simulations are carried out for various types of footwear in both pre- and postfatigue conditions. The simulation results show that the vibration amplitude of the lower body soft-tissue package may considerably increase (up to 20%) with muscle fatigue, while the effects of fatigue on the GRF are negligible. The results of this modeling study are in line with the experimental studies that found muscle fatigue does not significantly change the GRF peaks, but may increase the level of soft-tissue vibrations (particularly for hard shoes). A major contribution of the current study is the formulation of a hypothesis about how the central nervous system tunes the muscle properties after fatigue.