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Scalp potentials and magnetic fields of a fully and partially activated central sulcus

International Congress Series 2007年 1300卷 157-160页

作者： Ramon, Ceon Holmes, Mark D. Haueisen, Jens Schimpf, Paul H. Freeman, Walter J. Department of Electrical Engineering University of Washington Seattle WA United States Department of Neurology University of Washington Seattle WA United States Institute of Biomedical Engineering and Informatics Technical University Ilmenau Germany Department of Computer Science Eastern Washington University Cheney WA United States Department of Molecular and Cell Biology University of California Berkeley CA United States

Our objective was to examine how the scalp potentials and the magnetic fields of a sulcus change if the cortex in the walls is partially or fully active. The scalp potentials and magnetic fields of a part of the central sulcus were simulated with a finite element model of the head constructed from the segmented MRI images of an adult male subject. The electrical activity was modeled with current dipoles (0.1 mA meter) oriented perpendicular to the curved cortical surface. The fields of scalp EEG were computed using an adaptive finite element solver. The magnetic fields at a surface 1.0 cm above the scalp were computed using Biot-Savart law. Three distributions of activity were studied: the total sulcus;the superficial half and the deep half. Contour plots of EEG and MEG were constructed for each case. The spatial patterns of the scalp potential contours were significantly different for the partial vs. full activation. Each partial activation gave a uniquely different configuration of peak MEG and EEG locations that could have diagnostic utility. The spatial shifts in the peaks were more pronounced for the MEG compared with the EEG. These results indicate that scalp potentials and fields change significantly when the electrical and magnetic manifestations of activity are selective in the walls of a sulcus. © 2007 Elsevier B.V. All rights reserved.

关键词： Central sulcus models EEG Epilepsy Finite element MEG Realistic head model Stroke

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Hypergraph-based Dynamic Load Balancing for Adaptive Scientific Computations

Hypergraph-based Dynamic Load Balancing for Adaptive Scienti...

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International Symposium on Parallel and Distributed Processing (IPDPS)

作者： Umit V. Catalyurek Erik G. Boman Karen D. Devine Doruk Bozdag Robert Heaphy Lee Ann Riesen Department of Biomedical Informatics Department of Electrical & Computer Engineering Ohio State Uinversity Columbus OH USA Discrete Algorithms and Mathematics Department Sandia National Laboratories Albuquerque NM USA Department of Biomedical Informatics Department of Electrical & Computer Engineering Ohio State Uinversity Columbus OH USA

Adaptive scientific computations require that periodic repartitioning (load balancing) occur dynamically to maintain load balance. Hypergraph partitioning is a successful model for minimizing communication volume in scientific computations, and partitioning software for the static case is widely available. In this paper, we present a new hypergraph model for the dynamic case, where we minimize the sum of communication in the application plus the migration cost to move data, thereby reducing total execution time. The new model can be solved using hypergraph partitioning with faced vertices. We describe an implementation of a parallel multilevel repartitioning algorithm within the Zoltan load-balancing toolkit, which to our knowledge is the first code for dynamic load balancing based on hypergraph partitioning. Finally, we present experimental results that demonstrate the effectiveness of our approach on a Linux cluster with up to 64 processors. Our new algorithm compares favorably to the widely used ParMETIS partitioning software in terms of quality, and would have reduced total execution time in most of our test cases.

关键词： Load management Costs Biomedical computing Partitioning algorithms US department of Energy Laboratories Clustering algorithms Computational modeling Contracts Biomedical informatics

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Performance vs. accuracy trade-offs for large-scale image analysis applications

Performance vs. accuracy trade-offs for large-scale image an...

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IEEE International Conference on Cluster Computing

作者： Vijay S. Kumar Tahsin Kurc Jun Kong Umit Catalyurek Metin Gurcan Joel Saltz Department of Biomedical Informatics Ohio State University USA Department of Electrical and Computer Engineering Ohio State University Department of Biomedical Informatics The Ohio State University USA

In many data analysis applications, application-level parameters influence the execution time of the data analysis method or program. Some of these parameters also affect the accuracy of output of the analysis. In this work, we investigate execution strategies for adaptive data analysis applications where the user is willing to trade-off accuracy of output for performance gain and vice-versa. In order to meet the user defined quality of service requirements, the system must dynamically select values for the parameters during execution. We propose algorithms for adaptive processing of image tiles at different resolutions so that user defined requirements in terms of accuracy of the result and execution time constraints can be satisfied. We develop heuristics for estimation of accuracy vs performance characteristics of image tiles and for scheduling of the tiles for processing. We implement a demand-driven strategy for parallel execution of these heuristics on a parallel machine. We evaluate our approach for analysis of large images from digitized microscopy scanners.

关键词： Tiles Accuracy Image resolution Quality of service Classification algorithms Process control Heuristic algorithms

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Retina Layer Segmentation and Spatial Alignment of Antibody Expression Levels

Retina Layer Segmentation and Spatial Alignment of Antibody ...

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IEEE International Conference on Image Processing

作者： Nhat Vu Pratim Ghosh B. S. Manjunath Department of Electrical and Computer Engineering Center for Bio-image Informatics University of California Santa Barbara CA USA

The expression levels of rod opsin and glial fibrillary acidic protein (GFAP) capture important structural changes in the retina during injury and recovery. Quantitatively measuring these expression levels in confocal micrographs requires identifying the retinal layer boundaries and spatially corresponding the layers across different images. In this paper, a method to segment the retinal layers using a parametric active contour model is presented. Then spatially aligned expression levels across different images are determined by thresholding the solution to a Dirichlet boundary value problem. Our analysis provides quantitative metrics of retinal restructuring that are needed for improving retinal therapies after injury.

关键词： Retina Active contours Image segmentation Injuries Labeling Image converters informatics Protein engineering Boundary value problems Medical treatment

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Simulation control of a biped robot with Support Vector Regression

Simulation control of a biped robot with Support Vector Regr...

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IEEE International Symposium on Intelligent Signal Processing

作者： Joao P. Ferreira Manuel Crisostomo A. Paulo Coimbra Bernardete Ribeiro Institute of Systems and Robotics Department of Electrical and Computer Engineering University of Coimbra Portugal CISUC Department of Informatics Engineering University of Coimbra Coimbra Portugal

ISBN: (纸本)1424408296;97

This paper describes the control of an autonomous biped robot that uses the Support Vector Regression (SVR) method for its longitudinal balance. This SVR uses the Zero Moment Point (ZMP) position and its variation as input and the longitudinal correction of the robot's body is obtained as the output. The SVR was trained based on simulation data that was confirmed with the real robot. This method showed to be faster (with similar accuracy) than a recurrent network or a neuro-fuzzy control of the biped balance.

关键词： Control systems Stability Nonlinear control systems Computational modeling Robot control Mathematical model Humans Kinematics Torso computer simulation

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Using spectral analysis to determine the equivalent circuit of the output filter of DC-DC converters at their operating frequency

Using spectral analysis to determine the equivalent circuit ...

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International Aegean Conference on electrical Machines and Power Electronics, ACEMP

作者： Acacio M. R. Amaral A. J. Marques Cardoso Department of Electrical and Computer Engineering University of Coimbra Coimbra Portugal Department of Informatics and Systems Polytechnic Institute of Coimbra Coimbra Portugal

The aim of this paper is to present an on-line technique which can be used to determine the equivalent circuit of the storage elements of DC-DC converters at their operating frequency. This technique can be used not only for the determination of both inductor and capacitor equivalent circuits, but also as a fault diagnostic technique, in order to evaluate the state condition of these components. The proposed technique uses the spectral analysis in order to obtain the relation between inductor current and voltage, and between inductor current and output voltage ripple. From these relationships, it is possible to determine the equivalent circuit of the inductor and capacitors at the operating frequency of the converter. In this paper, several experimental and simulated results are presented in order to demonstrate the accuracy of the proposed method.

关键词： Spectral analysis Equivalent circuits Filters DC-DC power converters Frequency conversion Inductors Capacitors Voltage Circuit faults Circuit simulation

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Knowledge based system for reliable perimeter protection using sensor networks

Knowledge based system for reliable perimeter protection usi...

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WINSYS 2007 - 2nd International Conference on Wireless Information Networks and Systems

作者： Voloencu, Constantin Curiae, Daniel-Loan Banias, Ovidiu Doboli, Alex Dranga, Octavian Automatics and Applied Informatics Department Politehnica University of Timisoara Bd. V. Parvan nr. 2 300223 Timisoara Romania Electrical and Computer Engineering Department State University of New York NY 11794-2350 United States School of Engineering James Cook University Townsville QLD 4811 Australia

This paper provides a strategy for perimeter protection using sensor networks with hardware and analytical redundancy. The sensor network reliability is augmented using a knowledge-based system, which implicates the analysis of the trustworthiness of each sensor. For this, we used two stratagems: one that relies on hardware redundancy based on the Confidence Weighted Voting Algorithm and one that relies on analytical redundancy based on a neural perceptron predictor that uses past and present values obtained from neighbouring nodes. This solution can be also a way to discover the malfunctioning nodes that were subjects of an attack and it is localized at the base station level being suitable even for large-scale sensor networks.

关键词： Neural networks

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MPI-HMMER-boost: Distributed FPGA acceleration

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Journal of VLSI Signal Processing Systems for Signal, Image, and Video Technology 2007年第3期48卷 223-238页

作者： Walters, John Paul Meng, Xiandong Chaudhary, Vipin Oliver, Tim Yeow, Leow Yuan Nathan, Darran Schmidt, Bertil Landman, Joseph Institute for Scientific Computing Wayne State University Detroit MI 48202 United States Electrical and Computer Engineering Department Wayne State University Detroit MI 48202 United States Department of Computer Science and Engineering University at Buffalo State University of New York Buffalo NY 14260 United States Progeniq Pte Ltd. 8 Prince George's Park 118407 Singapore Singapore UNSW Asia 1 Kay Siang Road 248922 Queenstown Singapore Scalable Informatics LLC 2433 Woodmont Canton MI 48188 United States

HMMER, based on the profile Hidden Markov Model (HMM) is one of the most widely used sequence database searching tools, allowing researchers to compare HMMs to sequence databases or sequences to HMM databases. Such searches often take many hours and consume a great number of CPU cycles on modern computers. We present a cluster-enabled hardware/software-accelerated implementation of the HMMER search tool hmmsearch. Our results show that combining the parallel efficiency of a cluster with one or more high-speed hardware accelerators (FPGAs) can significantly improve performance for even the most time consuming searches, often reducing search times from several hours to minutes. © 2007 Springer Science + Business Media, LLC.

关键词： Data mining

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Using spectral analysis to determine the equivalent circuit of the output filter of DC-DC converters at their operating frequency

Using spectral analysis to determine the equivalent circuit ...

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International Aegean Conference on electrical Machines and Power Electronics and Electromotion ACEMP'07 and Electromotion'07 Joint Conference

作者： Amaral, Acácio M. R. Cardoso, A. J. Marques Polytechnic Institute of Coimbra ISEC Department of Informatics and Systems Rua Pedro Nunes - Quinta da Nora P - 3030-199 Coimbra Portugal University of Coimbra FCTUC / IT Department of Electrical and Computer Engineering Pólo II - Pinhal de Marrocos P - 3030-290 Coimbra Portugal

ISBN: (纸本)1424408911

关键词： Equivalent circuits

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A Pipelined Recurrent Fuzzy Neural Filter for the Separation of Lung Sounds

A Pipelined Recurrent Fuzzy Neural Filter for the Separation...

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IEEE International Conference on Fuzzy Systems (FUZZ-IEEE)

作者： Dimitris Stavrakoudis Paris Mastorocostas John Theocharis Department of Electrical and Computer Engineering Aristotle University of Thessaloniki Greece Department of Informatics and Communications Technological Educational Institute of Serres Serres Greece

This paper presents a recurrent fuzzy-neural filter that performs the task of separation of lung sounds, obtained from patients with pulmonary pathology. The filter is a pipelined Takagi-Sugeno-Kang recurrent fuzzy network, consisting of a number of modules interconnected in a cascaded form. The participating modules are implemented through recurrent fuzzy neural networks with internal dynamics. The structure of the modules is evolved sequentially from input-output data. Extensive experimental results, regarding the lung sound category of crackles, are given, and a performance comparison with a series of other fuzzy and neural filters is conducted, underlining the separation capabilities of the proposed filter.

关键词： Lungs Fuzzy systems Fuzzy neural networks Pathology Takagi-Sugeno-Kang model Inference algorithms Least squares methods Nonlinear filters Delay Neurons

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