检索结果-内蒙古大学图书馆

Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： T. Janjic S. Thomsen J.A. Pearce Biomedical Engineering Program University of Texas Austin Austin TX USA M D Anderson Cancer Center Laser Biology Laboratory University of Technology Houston TX USA

Most anatomical structures, especially vessels, are complex combinations of tissues with differing properties. In an electric field sense, tissues and their constituents are approximately linear but certainly are neither homogeneous nor isotropic. The authors have measured the anisotropic electrical conductivity of cardiac muscle, arteries and veins and of the vessel constituents collagen and elastin over the range of electrosurgical frequencies: 10 kHz to 10 MHz.

关键词： Anisotropic magnetoresistance Radio frequency Anatomical structure Linear approximation Conductivity measurement Frequency measurement Electric variables measurement Muscles Arteries Veins

来源：评论

学校读者我要写书评

暂无评论

A study on the nonlinear dynamics of PR interval variability using surrogate data

A study on the nonlinear dynamics of PR interval variability...

引用

Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Jongmin Lee Kwangsuk Park Insun Shin Interdisciplinary Program in Medical and Biological Engineering Major Seoul National University in Korea South Korea Department of Biomedical Engineering Seoul National University Seoul South Korea Department of Mathematics Education Korea National University of Education South Korea

PR interval variability (PRV) has been proposed as a noninvasive tool for investigating the autonomic nervous system (ANS) as well as heart rate variability (HRV). The goal of this study is to determine whether PRV has nonlinear dynamics or not. The authors developed an automatic PR interval measurement algorithm, and tested it using MIT ECG databases. 24-hour Holter ECGs were acquired from 30 healthy adults. Surrogate data was generated from a simpler linear model to have similar statistical characteristics with the original data. To detect nonlinear dynamics of the time series, correlation dimension, Lyapunov exponent, and phase space reconstruction were evaluated in both data. The results showed that PRV was significantly different from the surrogate data in the tests. It was concluded that PR interval variability shows nonlinear behavior.

关键词： Heart rate variability Electrocardiography Nonlinear dynamical systems biomedical engineering Educational programs Systems engineering education Autonomic nervous system Databases Character generation Phase detection

来源：评论

学校读者我要写书评

暂无评论

Surface Laplacian with spline and nearest neighbour interpolations for topographic brain mapping

Surface Laplacian with spline and nearest neighbour interpol...

引用

Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： C.J. Tierra D.M. Simpson A.F.C. Infantosi Biomedical Engineering Program Federal University of Rio de Janeiro (COPPE-EE) Rio de Janeiro Brazil Universidade Federal do Rio de Janeiro Rio de Janeiro RJ BR

In the construction of topographic maps from the EEG, the Laplacian (or Source Derivation) operation improves the localisation of sources, by reducing the smearing effect in conducting layers of the head. Due to the use of a limited number of electrodes, interpolation techniques are employed either before or after applying the Laplacian. In the present work, two such approaches, Spline interpolation followed by Laplacian and Laplacian followed by four nearest neighbour interpolation, are applied to scalp potential distributions derived from simulated dipole sources. The results prove both approaches to be similarly effective in demonstrating the presence of multiple dipoles.

关键词： Surface topography Laplace equations Spline Interpolation Brain mapping Scalp Electroencephalography Electrodes Head Brain modeling

来源：评论

学校读者我要写书评

暂无评论

A new method of measuring ciliary beat frequency using image processing

A new method of measuring ciliary beat frequency using image...

引用

Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： Wonjin Yi Kwangsuk Park Yanggi Min Meonghun Sung Interdisciplinary Program in Medical and Biological Engineering Major Seoul National University South Korea Department of Biomedical Engineering College of Medicine Seoul National University South Korea Department of Otolaryngology Head and Neck Surgery College of Med Seoul National University South Korea

Mucociliary clearance of the respiratory tract is one of the important defensive functions of the airway mucous. In this study, the authors developed a new method of measuring ciliary beat frequency (CBF) with high spatial resolution based on the image processing method. Microscopic ciliary images were digitized through an image grabbing board inside a PC, and data necessary for the power spectrum (FFT) analyses were extracted from these gray images by an image subtraction method. By means of FFT analyses, the maximum peak frequencies were found in each divided block of a whole acquired image. Finally using these frequencies, the authors composed frequency maps of various sizes showing the spatial distribution of CBF's in user specified resolution. The smaller the authors made the size of divided blocks included in analysis, the more detailed regional ciliary beat distributions they could evaluate.

关键词： Frequency measurement Image processing Image analysis Spatial resolution Pixel biomedical measurements Data mining biomedical imaging Optical sensors Optical microscopy

来源：评论

学校读者我要写书评

暂无评论

biomedical information technology: Internet and beyond

Biomedical information technology: Internet and beyond

引用

Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： S. Laxminarayan P. Yadav GES Internet John von Neuman Computer Network Biomedical Engineering Program New Jersey Institute of Technology Princeton NJ USA Department of Molecular Genetics Robert Wood Johnson Medical School-UMDNJ USA

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.

关键词： Information technology Internet High-speed networks Explosions Collaboration Medical services Collaborative work Multimedia systems Videoconference Educational technology

来源：评论

学校读者我要写书评

暂无评论

Electrical stimulation induced spasticity reductions in stroke as evidenced by changes in elbow torque responses

Electrical stimulation induced spasticity reductions in stro...

引用

Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： J.D. Given B.D. Schmit W.Z. Rymer J.P.A. Dewald Sensory Motor Performance Program PM&R Northwestern University Chicago IL USA Sensory Motor Performance Program PM&R Rehab. Institute of Chicago and Departments of Biomedical Engineering Northwestern University Chicago IL USA Sensory Motor Performance Program PM&R Physics Ther. Northwestern University Chicago IL USA

We studied the effects of electrical stimulation of the skin on upper extremity spasticity in 9 hemiparetic stroke subjects. The effects were quantified by comparing reflex torque responses during ramp and hold angular perturbations of the elbow. Electrical stimulation was applied to skin over the biceps muscle of all nine subjects for a period of ten minutes at a 20 Hz frequency, pulse duration 0.1 ms, with an intensity level between sensory and motor thresholds. In a subset of subjects (n=2), the protocol was repeated using frequencies of 1 and 100 Hz. In seven subjects, peak torque responses were reduced for at least 30 minutes. Significant increases in mean threshold onset angle of the reflex torque without changes in reflex stiffness were measured. These long-term changes may reflect synaptic plasticity of spinal circuitry outside the stretch reflex loop. Comparable reductions in spasticity were observed when repeating the same protocol with different stimulation frequencies.

关键词： Electrical stimulation Elbow Frequency Protocols Muscles Torque measurement Skin Electromyography biomedical measurements Position measurement

来源：评论

学校读者我要写书评

暂无评论

Molecular modeling studies of AChE inhibition by sarin

Molecular modeling studies of AChE inhibition by sarin

引用

Annual Northeast Bioengineering Conference

作者： C.E. Linaras A. Ritter D. Kristol Department of chemical Engineering New Jersey Medical School University of Medicine and Dentistry of New Jersey Newark NJ USA Department of Physiology New Jersey Institute of Technology Newark NJ USA Biomedical Engineering Program New Jersey Medical School University of Medicine and Dentistry of New Jersey Newark NJ USA

In the present study molecular modeling and molecular mechanics methods using the crystal structure coordinates for acetylcholinesterase (AChE) from Torpedo Californica were employed to demonstrate the behavior of key residues of the enzyme upon inhibition by both the P/sub R/ and P/sub S/ diastereomers of isopropylmethylphosphonofluoridate (sarin). Comparative studies between both the adducts of AChE with P/sub S/ and P/sub R/ sarin and with the native enzyme indicate the important role of the aromatic residues in the vicinity of the active site as well as that of His-440 which catalyzes both the C-O bond breaking in the dealkylation reaction and the reaction of bond breaking to the Ser /spl gamma/-O in reactivation. In contrast to previous studies, the role of Glu-199 in stabilizing the developing positive charge on the incipient carbonium ion in the dealkylation reaction was not verified in this study.

关键词： Biochemistry Bonding Integrated circuit modeling Aging Electrostatics Chemical engineering biomedical engineering Chemical technology Crystallography Proteins

来源：评论

学校读者我要写书评

暂无评论

Three dimensional molecular modeling studies in AIDS research using high performance computing facilities: a ternary complex of HV-1 RT

Three dimensional molecular modeling studies in AIDS researc...

引用

Annual International Conference of the IEEE engineering in Medicine and Biology Society (EMBC)

作者： N.S. Yadav S. Laxminarayan J.S. Yadav V.N. Pandey S. Singh M.J. Modak Dept. of Biochem. Acad. Comput. Center Piscataway NJ USA Biomedical Engineering Program New Jersey Institute of Technology and John von Neuman Computer Network Princeton USA Department of Biochemistry and Molecular Biology and Academic Computing Center University of Medicine and Dentistry of New Jersey Piscataway NJ USA

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.

关键词： Acquired immune deficiency syndrome High performance computing Biochemistry Spine Biological system modeling Biology computing DNA Computer networks Amino acids Polymers

来源：评论

学校读者我要写书评

暂无评论

STATISTICALLY TAILORED NEURAL-NETWORK APPROACH TO TOMOGRAPHIC IMAGE-RECONSTRUCTION

引用

MEDICAL PHYSICS 1995年第5期22卷 601-610页

作者： KERR, JP BARTLETT, EB Biomedical Engineering Program Iowa State University Ames Iowa 50011

In previous work it has been shown that a standard backpropagation neural network can be trained to reconstruct sections of single photon emission computed tomography (SPECT) images based on the planar image projections as inputs. In this study, it is demonstrated that an artificial neural network (ANN) trained on a series of simulated SPECT images or trained on a set of rudimentary geometric images can learn the planar data-to-tomographic image relationship for 64×64 tomograms. As a result, a properly trained ANN can produce accurate, novel image reconstructions but without the high computational cost inherent in some traditional reconstruction techniques. We also present a method of deriving activation functions for a backpropagation ANN that make it readily trainable for cardiac SPECT image reconstruction. The activation functions are derived from the estimated probability density functions (p.d.f.s) of the ANN training set data. The performance of the statistically tailored ANNs are compared with the performance of standard sigmoidal backpropagation ANNs, both in terms of their trainability and generalization ability. The results presented demonstrate that statistically tailored ANNs are significantly better than standard sigmoidal ANNs at reconstructing novel tomographic images based on a simulated SPECT image training set or a rudimentary geometric image training set. Neural network based image reconstruction has two potential advantages over conventional reconstruction methods. The first advantage is that ANNs can rapidly reconstruction tomograms. Secondly, the quality of the reconstructions produced are directly correlated to the quality of the images used to train the ANN.

关键词： ARTIFICIAL NEURAL NETWORK BACKPROPAGATION PROBABILITY DENSITY FUNCTION SINGLE PHOTON EMISSION COMPUTED TOMOGRAPHY (SPECT) STATISTICALLY TAILORED NEURAL NETWORK

来源：评论

学校读者我要写书评

暂无评论

A THEORY TO CORRECT THE SYSTEMATIC-ERROR CAUSED BY THE IMPERFECTLY MATCHED BEAM WIDTH TO VESSEL DIAMETER RATIO ON VOLUMETRIC FLOW MEASUREMENTS USING ULTRASOUND TECHNIQUES

引用

ULTRASOUND IN MEDICINE AND BIOLOGY 1995年第8期21卷 1047-1057页

作者： FEI, DY Biomedical Engineering Program Virginia Commonwealth University Richmond VA USA

When a multigate procedure is used to measure volumetric flow in vessels, in addition to the flow rate result obtained from the conventional velocity profile method, a second result from an ''average velocity profile method'' can be obtained simultaneously, The latter method obtains the flow rate from the product of the average velocity across the profile and the cross-sectional area of the vessel, A theoretical model has been used to study the effect of the beam width to vessel diameter ratio (BWR) on these two results, as well as a third flow rate result obtained from the uniform insonation method, A theory has been established to correct the systematic error caused by the imperfectly matched BWR associated with each method, It uses a correction factor and the difference between the results from the average velocity profile method and the velocity profile method to compensate for the systematic error, The relationship between an optimal correction factor and the BWR under different flow conditions has been studied, The results using the correction theory in this model show that if the estimated BWR is within +/-0.1 from the actual BWR value, the theoretical error in volumetric how estimation tan be limited to within 6.5% for the entire range of BWR.

关键词： ULTRASOUND VOLUMETRIC FLOW CORRECTION THEORY BEAM WIDTH TO VESSEL DIAMETER RATIO

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：