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Harnessing piecewise-linear systems to construct dynamic logic architecture

CHAOS 2008年第3期18卷 033101-033101页

作者： Peng, Haipeng Yang, Yixian Li, Lixiang Luo, Hong Beijing Univ Posts & Telecommun State Key Lab Networking & Switching Technol Informat Secur Ctr Beijing 100876 Peoples R China Beijing Univ Posts & Telecommun Beijing Key Lab Intelligent Telecommun Software & Beijing 100876 Peoples R China

This paper explores piecewise-linear systems to construct dynamic logic architecture. We present three schemes to obtain various basic logic gates, adders, and memory by using piecewise-linear systems. These schemes can switch easily among different operational roles by changing parameters. The proposed schemes are computationally efficient and easy to use. It is convenient for us to study and analyze them with the theory of linear systems. (C) 2008 American Institute of Physics.

关键词： computer Systems computer-Aided Design Computing Methodologies Equipment Design signal processing, computer-assisted/instrumentation

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BOLD correlates of EMG spectral density in cortical myoclonus: Description of method and case report

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NEUROIMAGE 2006年第2期32卷 558-565页

作者： Richardson, Mark P. Grosse, Pascal Allen, Philip J. Turner, Robert Brown, Peter UCL Inst Neurol Dept Clin & Expt Epilepsy London England UCL Inst Neurol Sobell Dept Neurophysiol London England UCL Inst Neurol Wellcome Dept Imaging Neurosci London England Natl Hosp Neurol & Neurosurg London WC1N 3BG England

The recording of electrophysiological data during BOLD fMRI is highly challenging but provides the opportunity to develop a more thorough account of brain function than either modality alone. To develop new techniques in this area has often required the study of pathological electrophysiological measures because such measures can be unusually strong (e.g., epileptic EEG spikes) and hence more easily detectable during fMRI than weaker normal phenomena. In this paper, we have studied pathologically strong EMG signals in a patient with cortical myoclonus. First, we studied the patient outside of scanning: The pathological corticospinal drive to muscle was concentrated over 6-30 Hz so that EMG components at higher frequency could be used to control for non-corticospinal contributions to the EMG during scanning. Additionally, there was very strong EMG-EMG and EMG-EEG coherence in this frequency band. Furthermore, analysis of spectral phase showed that this exaggerated coherence was produced by efferent drive from brain to muscle. Hence, the exaggerated peak in distal muscle EMG power spectrum reflected brain activity producing the efferent drive. Subsequently, we modified equipment and data analysis techniques previously developed for simultaneous EEG-fMRI to record polychannel EMG from distal upper limbs during simultaneous BOLD fMRI. After artefact reduction, the EMG recorded during fMRI retained the essential frequency and phase characteristics of EMG recorded outside of scanning. The BOLD signal was significantly correlated with time-varying 6- to 30-Hz power in a froutoparietal network compatible with the neurophysiological characteristics of our patient and compatible with prior hypotheses explaining the origin of cortical mynclonus. (c) 2006 Elsevier Inc. All rights reserved.

关键词： Adult Artifacts Brain Mapping Brain Mapping Cerebral Cortex/physiopathology Dominance, Cerebral/physiology Electroencephalography/instrumentation Electromyography/instrumentation Essential Tremor/diagnosis Essential Tremor/physiopathology Fourier Analysis Fourier Analysis Gyrus Cinguli/physiopathology Humans Image Enhancement/instrumentation Image processing, computer-assisted/instrumentation Magnetic Resonance Imaging/instrumentation Male Mathematical Computing Muscle, Skeletal/innervation Myoclonus/diagnosis Myoclonus/physiopathology Nerve Net/physiopathology Oxygen/blood signal processing, computer-assisted/instrumentation Software Statistics as Topic

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A force reproduction analysis of two recording sensors of a computerized occlusal analysis system

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CRANIO-THE JOURNAL OF CRANIOMANDIBULAR & SLEEP PRACTICE 2006年第1期24卷 15-24页

作者： Kerstein, RB Lowe, M Harty, M Radke, J 665 Beacon St 204 Boston MA 02215 USA

The purpose of this study was to measure the performance of a new design of occlusal sensor, the high definition (HD) sensor, and directly compare this sensor to the previous design. This new HD sensor design has increased active recording area by 33%, and decreased inactive recording area by 50% as compared to the previous design (G3). This was accomplished by determining the force reproduction variability for repeated occlusal closures on the same sensor for a sampling of sensors from both designs. Thirty (30) G3 and 30 HD sensors were consistently positioned and loaded 24 times between articulated epoxy casts by a Pneumatic Occlusal Force Simulator. Their force reproduction consistency was measured as an electronic voltage drop across six occlusal contacts that were consistently located on all sensors. The force variability of the two sensor designs was determined by comparing the consistency of the voltage drops across the six occlusal contacts. An analysis of variance was employed to determine the variability of force reproduction over multiple closures across six occlusal contact regions. For five of the six contacts, the G3 sensor mean variances, were significantly larger (p < 0.05) than those of the HID sensor. The within sensor variability of the HID sensor was significantly less than that of the G3 sensor. Within the limitations of this study, the HD sensor exhibited less variable force reproduction than the G3 sensor for at least 20 in-laboratory loading cycles.

关键词： Bite Force Dental Articulators Dental Models Electronics/instrumentation Epoxy Resins Equipment Design Humans Jaw Relation Record/instrumentation Reproducibility of Results signal processing, computer-assisted/instrumentation Transducers, Pressure

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Using reconfigurable hardware to accelerate multiple sequence alignment with ClustalW

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BIOINFORMATICS 2005年第16期21卷 3431-3432页

作者： Oliver, T Schmidt, B Nathan, D Clemens, R Maskell, D Nanyang Technol Univ Sch Comp Engn Singapore 2263 Singapore Ngee Ann Polytech Sch Engn Project Proteus Singapore Singapore

Aligning hundreds of sequences using progressive alignment tools such as ClustalW requires several hours on state-of-the-art workstations. We present a new approach to compute multiple sequence alignments in far shorter time using reconfigurable hardware. This results in an implementation of ClustalW with significant runtime savings on a standard off-the-shelf FPGA.

关键词： computers Databases, Protein Databases, Protein Equipment Design Equipment Failure Analysis Sequence Alignment/instrumentation Sequence Alignment/methods Sequence Analysis, Protein/instrumentation Sequence Analysis, Protein/methods signal processing, computer-assisted/instrumentation Software User-computer Interface

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Stop place coding: An acoustic study of CV, VC#, and C#V sequences

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PHONETICA 2004年第1期61卷 2-21页

作者： Modarresi, G Sussman, H Lindblom, B Burlingame, E Univ Texas Dept Linguist Austin TX 78712 USA Stockholm Univ Dept Phonet S-10691 Stockholm Sweden

This study investigated stop + vowel coarticulation as a coding mechanism for differentiation of stop place categories in an F2-defined stimulus space. Locus equations (LEs) were used to index the extent of coarticulation in three contexts: ( 1) onset stop + vowel utterances [.CV];(2) within-syllable vowel + coda stop utterances [VC#], and (3) across-syllable/word coda stop + vowel utterances [C#V]. Five speakers of American English and 2 speakers of Persian produced [***2] (English and Persian), [tV(1)C#V(2)t] (English) and [dV(1)C#V(2)t] (Persian) tokens with voiced labial, alveolar/dental, and velar stops surrounded by a variety of vowels. In the across-syllable/word boundary condition [C#V-2] the extent of anticipatory coarticulation was much reduced relative to traditionally measured onset [CV2] syllables. LE slopes derived across the syllable/word boundary, however, still differed between stop places in the same order as onset CVs. LE slopes derived from within-syllable [V1C#] sequences, however, did not differ between stop places. Copyright (C) 2004 S. Karger AG, Basel.

关键词： Acoustics Adult Fourier Analysis Fourier Analysis Humans Male Phonetics signal processing, computer-assisted/instrumentation Sound Spectrography Speech/physiology Speech Acoustics Speech Production Measurement Tape Recording/instrumentation

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Grading of age-related maculopathy for epidemiological studies - Is digital imaging as good as 35-mm film?

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OPHTHALMOLOGY 2003年第8期110卷 1540-1544页

作者： van Leeuwen, R Chakravarthy, U Vingerling, JR Brussee, C Hooghart, AJ Mulder, PG de Jong, PTVM Netherlands Ophthalm Res Inst KNAW NL-1105 BA Amsterdam Netherlands Erasmus Med Ctr EUREYE Grading Ctr Rotterdam Netherlands Erasmus Med Ctr Dept Epidemiol & Biostat Rotterdam Netherlands Queens Univ Belfast Dept Ophthalmol & Visual Sci Belfast Antrim North Ireland Erasmus MC Univ Ctr Med Dept Ophthalmol Rotterdam Netherlands Acad Med Ctr Dept Ophthalmol Amsterdam Netherlands

Purpose: To compare stereo digital images with stereo 35-mm color transparencies as to the quality and reliability of grading age-related maculopathy (ARM) in the context of a multicenter European epidemiologic study (the EUREYE Study). Design: Instrument validation study. Participants: Ninety-one subjects (137 eyes) with varying degrees of ARM, including no ARM. Methods: From both eyes of the participants, 35-mm film and digital stereoscopic fundus images were obtained with two identical eTopcon fundus cameras. Two experienced graders classified all signs of ARM according to the International Classification System. Agreement between eimaging techniques and between graders was calculated using the weighted K statistic. Main Outcome Measures: Signs of ARM (number, size, and morphologic characteristics of drusen;pigmentary changes;geographic atrophy;and neovascular macular degeneration) as well as an overall staging system of increasing ARM severity. Results: The weighted K value for between-technique agreement ranged from 0.41 for number of drusen <63 mum to 0.79 for drusen type and total area occupied by drusen. The K values for atrophic and neovascular end-stage ARM were 0.87 and 0.94, respectively. The between-technique agreement on stages of ARM was approximately 0.76. The agreement between graders was largely the same for both techniques of imaging. Conclusions: In the described setting, digital images were as good as 35-mm film for the grading of ARM. Considering the practical advantages of digital imaging, this technique may serve well in epidemiologic studies of ARM. (C) 2003 by the American Academy of Ophthalmology.

关键词： Aged Diagnostic Techniques, Ophthalmological Humans Macula Lutea/pathology Macular Degeneration/classification Macular Degeneration/epidemiology Observer Variation Photography/methods Reproducibility of Results signal processing, computer-assisted/instrumentation

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Portable video-oculography. A diagnostic tool in vertigo and for use in preparing expert opinions

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HNO 2003年第4期51卷 321-323页

作者： Kazak, I Helling, K Scherer, H Free Univ Berlin Klinikum Benjamin Franklin Abt Hals Nasen Ohrenheilkunde D-12200 Berlin Germany

Bisher wurden in der internationalen Literatur nur wenige mobile Systeme vorgestellt. Dabei findet sich bei 2 Geräten eine elektronystagmographische, bei 1 Gerät eine videookulographische Dokumentation. Während die Elektronystagmographie das grundsätzliche Problem unterschiedlicher Ableitbedingungen (Hautwiderstand,Elektrodenposition) und damit schlecht reproduzierbarer Ergebnisse bietet, ist das vorgestellte videookulographische System ein Eigenbau ohne Angabe von technischen Daten. So gestaltet sich die Nutzung durch Dritte *** wird im Folgenden ein portables videookulographisches System vorgestellt,welches preiswert aus im freien Handel erhältlichen Teilen zusammengestellt worden *** dem Patienten oder dem Untersucher die Möglichkeit zu geben Kommentare aufzuzeichnen, verfügt das Gerät zusätzlich über einen Mikrofoneingang.

关键词： Diagnosis, Differential Disability Evaluation Electronystagmography/instrumentation Equipment Design Expert Testimony/legislation & jurisprudence Humans Malingering/diagnosis Meniere Disease/diagnosis Microcomputers Point-of-Care Systems signal processing, computer-assisted/instrumentation Video Recording/instrumentation

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Noninvasive evaluation of arterial abnormalities in young patients with neurofibromatosis type 1

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ANGIOLOGY 2000年第9期51卷 733-741页

作者： Tedesco, MA Ratti, G Di Salvo, G Martiniello, AR Limongelli, G Grieco, M Calabrese, E Grassia, C Iacono, A Lama, G Univ Naples 2 Med Surg Inst Cardiol I-80136 Naples Italy Univ Naples 2 Dept Pediat I-80136 Naples Italy

Neurofibromatosis regroups at least two different autosomal dominant genetic disorders: neurofibromatosis type 1 (NF1) and neurofibromatosis type 2 (NF2). Vascular disease is an underestimated complication of NF1. Few studies are available on this, all based on case reports. Neurofibromin, NF1 protein product, has also been detected in aortic smooth muscle. The purpose of this study was to evaluate the physical properties of the vessels, by measuring the carotid-femoral pulse wave velocity (PWV). This parameter was assessed by the Complior(R), a new noninvasive, validated device, used to screen a large population. The authors studied 64 neurofibromatosis patients (34 boys and 30 girls) with a mean age of 12 years (range 5-25 years). To investigate the presence of vascular lesions, aortic stiffness was evaluated by carotid-femoral PWV by using an automatic processor (Complior(R)). They compared data from the PWV with a control group (30 healthy children, 17 boys and 13 girls, mean age 11 years, range 5-23 years). The calculated mean PWV in the control group was 6.5 +/- 1.15 m/s. The mean PWV of the 64 young patients with NF1 was 6.3 +/- 1.02 m/s. There was no difference between the two groups (p=0.39). Nevertheless, analysis of the linear regression has shown a linear relationship between systolic blood pressure (SBP) and PWV in the control group, while in NF1 patients this relationship is not present. The authors suggest that the coexistence of different factors, such as intimal proliferation, thinning media, fragmentation of the elastic tissue, irregularity, stenosis and tortuosity of the vessels, dysplasia of the small vessels, that counterbalance PWV, normalize the mean value. They emphasize the importance of a careful vascular evaluation, using noninvasive method, such as Complior(R). This device is well accepted by NF1 patients.

关键词： Adolescent Adult Blood Flow Velocity/genetics Blood Flow Velocity/physiology Blood Pressure/genetics Blood Pressure/physiology Child Child, Preschool Elasticity Female Gene Expression Regulation, Neoplastic/physiology Genetic Screening Humans Male Muscle, Smooth, Vascular/physiopathology Nerve Tissue Proteins/genetics Neurofibromatosis 1/diagnosis Neurofibromatosis 1/genetics Neurofibromatosis 1/physiopathology Neurofibromin 1 Pulsatile Flow/genetics Pulsatile Flow/physiology Reference Values signal processing, computer-assisted/instrumentation Tunica Intima/physiopathology Vascular Diseases/diagnosis Vascular Diseases/genetics Vascular Diseases/physiopathology

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High-speed digital microscopy

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METHODS-A COMPANION TO METHODS IN ENZYMOLOGY 2000年第4期21卷 325-334页

作者： Sanderson, MJ Univ Massachusetts Sch Med Dept Physiol Worcester MA 01655 USA

Highspeed imaging is an ideal technique to accurately resolve the temporal and spatial characteristics of rapid events at either the molecular or cellular level. In this article, the digital imaging techniques used to simultaneously acquire transillumination phase-contrast images, at 240 images s(-1) (high-speed), to characterize ciliary beat frequency, and fluorescence images, at 30 images s(-1) (fast), to measure intracellular calcium concentration ([Ca2+](i)), are described. With this technique, a precise correlation between the changes in ciliary beat frequency with changes in [Ca2+](i) can be made. Simultaneous imaging is achieved by using different wavelengths of light to form the phase-contrast and fluorescent images and selectively directing these light wavelengths to different cameras with dichroic mirrors and bandpass filters. High-speed images compatible with standard video recording equipment are obtained by prematurely resetting the raster scan of a CCD camera with additional vertical synchronization pulses. The fast [Ca2+](i) images are determined using the ratiometric dye fura-2 and a recording technique that monitors rapid changes in fluorescence at a single wavelength and uses intermittent reference images for calibration. (C) 2000 Academic Press.

关键词： Image processing, computer-assisted/methods Microscopy, Fluorescence/instrumentation Microscopy, Fluorescence/methods Microscopy, Phase-Contrast/instrumentation Microscopy, Phase-Contrast/methods Microscopy, Video/instrumentation Microscopy, Video/methods signal processing, computer-assisted/instrumentation

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Neuroimage of voluntary movement: Topography of the Bereitschaftspotential, a 64-channel DC current source density study

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NEUROIMAGE 1999年第1期9卷 124-134页

作者： Cui, RQ Huter, D Lang, W Deecke, L Univ Vienna Neurol Clin Vienna Austria Univ Vienna Ludwig Boltzmann Inst Funct Brain Topog Vienna Austria

The Bereitschaftspotential (BP) was recorded at 56 scalp positions when 17 healthy subjects performed brisk extensions of the right index finger. Aim of the study was to contribute to our understanding of the physiology underlying the BP and, in particular, to specify the situation at BP onset. For this purpose, the spatial pattern of the BP was analyzed in short time intervals (35 and/or 70 ms) starting 2.51 s before movement onset. For each time segment a spherical model of the BP was calculated by using spline interpolation. Then the spatial distribution of the electric potential at the scalp surface was transformed into a spatial distribution of current source densities (CSD map). Onset times of the BP and onset times of initial CSD-activity ranged between 2.23 and 1.81 s before movement onset. We selected a time window between 1.6 and 1.5 s before movement onset in order to analyze the spatial CSD pattern in each subject. In 10 subjects there was a significant current sink in the scalp area located over medial-wall motor areas (pre-SMA, SMA proper and anterior cingulate cortex: electrode positions C1, C2, FCz, Ct) in the absence of a significant current sink over the primary motor cortex (MI: electrode positions C3, CP3, and CP5). in three subjects significant current sinks were present at both sites and in another three subjects a current sink only over the lateral motor cortex was observed. In one subject no significant current sinks were measured. It is concluded that there is a large group of subjects (13/17) in whom BP at onset is associated with a current sink over medial-wall motor areas. At a later time interval (0.6 to 0.5 s before movement onset), significant current sinks were found in 13 subjects in medial and in 10 subjects in lateral recordings. These data were considered to be consistent with the hypothesis that, at least in a majority of subjects, medial-wall motor areas are activated earlier than lateral motor areas when organizing the initiati

关键词： Adult Brain Mapping/instrumentation Brain Mapping/instrumentation Cerebral Cortex/physiology Contingent Negative Variation/physiology Electroencephalography/instrumentation Female Gyrus Cinguli/physiology Humans Male Motor Cortex/physiology Reference Values signal processing, computer-assisted/instrumentation Synaptic Transmission/physiology

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