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Enhanced glucose sensor linearity using poly(vinyl alcohol) hydrogels

Journal of Diabetes Science and Technology 2009年第4期3卷 863-874页

作者： Vaddiraju, SanthiSagar Singh, Hardeep Burgess, Diane J. Jain, Faquir C. Papadimitrakopoulos, Fotios Polymer Program Institute of Material Science University of Connecticut Storrs CT 06269 United States Department of Pharmaceutical Sciences University of Connecticut Storrs CT United States Nanomaterials Optoelectronics Laboratory Electrical and Computer Engineering University of Connecticut Storrs CT United States Department of Chemistry University of Connecticut Storrs CT United States

Background: High linearities, sensitivities, and low oxygen dependence constitute prime requisites for electrochemical glucose sensors. However, for implantable sensors the need to control tissue inflammation requires the use of outer membranes that permit inward analyte diffusion while continuously releasing anti-inflammatory drugs and other tissue response-modifying (TRM) agents. We have shown previously that while outer membranes based on layer-by-layer (LBL) assembly enhance linearity, poly(vinyl alcohol)(PVA) hydrogels loaded with TRM-containing microspheres enable a significant reduction in tissue inflammation. This article discusses the amperometric performance of glucose sensors coated with stacked LBL/PVA hydrogel outer membranes. Methods: Sensors were fabricated by immobilizing glucose oxidase enzyme on a 50-μm platinum wire followed by deposition of stacked LBL/PVA hydrogel outer membranes. The sensor response to various glucose concentrations was determined by applying 0.7 V vs an Ag/AgCl reference electrode in phosphate-buffered saline (37°C). Michaelis-Menten analysis was performed to quantify sensor performance in terms of linearity (Km,gluapp) and oxygen dependence (Km,O2app/[Glucose]). Results: When overlaid onto LBL-assembled outer membranes, PVA hydrogels improved sensor linearity by 60% from 10 to 16 m M of glucose and resulted in a twofold decrease in oxygen dependence. Conclusions: Enhancement in the performance of a PVA-coated sensor is attributed to the oxygen-storing capability of PVA hydrogel due to the formation of hydrophobic domains during its freezing and thawing employed to physical cross-link the PVA. Such membranes with the capability to release TRMs continuously while storing oxygen constitute a major improvement over current outer membrane technologies. © Diabetes Technology Society.

关键词： Apparent Michaelis-Menten constants Biosensor Freeze-thaw cycle Layer-by-layer assembly Linearity Outer membranes Oxygen content Oxygen dependence of biosensors PVA hydrogels

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Quantum Systems Connected by a Time-Dependent Canonical Transformation

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Communications in Theoretical Physics 2009年第9期52卷 416-420页

作者： Kyu Hwang Yeon Jeong Ryeol Choi ZHANG Shou BK21 Physics Program and Department of Physics College of Natural Science Chungbuk National University Cheongju Chungbuk 361-763 Korea School of Electrical Engineering and Computer Science Kyungpook National University 1370 Sankyuk-dong Buk-gu Daegu 702-701 Korea Center for the Condensed-Matter Science and Technology Harbin Institute of Technology Harbin 150001 China Department of Physics College of Science Yanbinn University Yanji 133002 China

We study both classical and quantum relation between two Hamiltonian systems which are mutually connected by time-dependent canonical transformation. One is ordinary conservative system and the other is timedependent Hamiltonian system. The quantum unitary operator relevant to classical canonical transformation between the two systems are obtained through rigorous evaluation. With the aid of the unitary operator, we have derived quantum states of the time-dependent Hamiltonian system through transforming the quantum states of the conservative system. The invariant operators of the two systems are presented and the relation between them are addressed. We showed that there exist numerous Hamiltonians, which gives the same classical equation of motion. Though it is impossible to distinguish the systems described by these Hamiltonians within the realm of classical mechanics, they can be distinguishable quantum mechanically.

关键词： canonical transformation innumerable kind of Hamiltonians canonical quantization invariant operator unitary transformation

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A neuromorphic head direction cell system

A neuromorphic head direction cell system

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IEEE International Symposium on Circuits and Systems (ISCAS)

作者： Tarek M. Massoud Timothy K. Horiuchi Electrical and Computer Engineering Department Institute of Systems Research Neuroscience and Cognitive Science Program University of Maryland College Park MD USA

ISBN: (纸本)9781424438273

The head direction (HD) cell system in the brain of mammals is thought to be part of the neural circuitry supporting their spatial navigation capabilities. In this paper we present a neuromorphic VLSI system that mimics the operation of the HD system. Relying on spiking neurons and attractor dynamics, this system can be used to represent and retain the current estimate of head orientation in the environment and integrate angular velocity to update this estimate. The presented system is a first step towards more general odometry systems that could be used for modeling biological navigation systems.

关键词： Neuromorphics Neurons High definition video Navigation Very large scale integration Biological system modeling Brain Neuroscience Cognitive science Educational institutions

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Comparison of threshold selection methods for microarray gene co-expression matrices

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BMC Research Notes 2009年第1期2卷 1-6页

作者： Borate, Bhavesh Chesler, Elissa Langston, Michael Saxton, Arnold Voy, Brynn Genome Science and Technology Program University of Tennessee Knoxville TN United States Department of Electrical Engineering and Computer Science University of Tennessee Knoxville TN United States Oak Ridge National Laboratory Systems Genetics Group Biosciences Division Oak Ridge TN United States Department of Animal Science University of Tennessee Knoxville TN United States

Background. Network and clustering analyses of microarray co-expression correlation data often require application of a threshold to discard small correlations, thus reducing computational demands and decreasing the number of uninformative correlations. This study investigated threshold selection in the context of combinatorial network analysis of transcriptome data. Findings. Six conceptually diverse methods - based on number of maximal cliques, correlation of control spots with expressed genes, top 1% of correlations, spectral graph clustering, Bonferroni correction of p-values, and statistical power - were used to estimate a correlation threshold for three time-series microarray datasets. The validity of thresholds was tested by comparison to thresholds derived from Gene Ontology information. Stability and reliability of the best methods were evaluated with block bootstrapping. Two threshold methods, number of maximal cliques and spectral graph, used information in the correlation matrix structure and performed well in terms of stability. Comparison to Gene Ontology found thresholds from number of maximal cliques extracted from a co-expression matrix were the most biologically valid. Approaches to improve both methods were suggested. Conclusion. Threshold selection approaches based on network structure of gene relationships gave thresholds with greater relevance to curated biological relationships than approaches based on statistical pair-wise relationships. © 2009 Saxton et al;licensee BioMed Central Ltd.

关键词： Spectral Cluster Maximal Clique Threshold Estimate Biological Relationship Spectral Graph

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Use of a step-response approximation for thermal transient modeling in power MOSFETs

Use of a step-response approximation for thermal transient m...

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ARFTG Conference

作者： Charles Baylis Joseph Perry Matthew Moldovan Robert J. Marks Lawrence Dunleavy Wireless and Microwave Circuits and Systems Program Department of Electrical and Computer Engineering Baylor University Waco Waco TX USA Center of Wireless and Microwave Information Systems Department of Electrical Engineering University of South Florida Tampa FL USA

In a previous ARFTG paper, we presented the measurement of the thermally-induced transient drain voltage response of a power Si MOSFET to a step excitation in gate voltage. The data was fit by assuming the drain voltage takes an exponential shape. This relies on the assumption that the drain current is a step function, which is actually only approximate due to the dependence of the drain current on temperature. In this work, we show that the exponential approximation actually possesses the same asymptotic behavior of a more accurate, model-based solution we have obtained that incorporates thermal feedback. We show that the more theoretically accurate solution and exponential approximation of the solution both provide excellent fits to measured data for the Si MOSFET.

关键词： MOSFETs Temperature Time measurement Electrothermal effects Thermal resistance electrical resistance measurement Power measurement Voltage measurement Thermal engineering Power system modeling

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LFP beta power predicts cursor stationarity in BMI task

LFP beta power predicts cursor stationarity in BMI task

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2009 4th International IEEE/EMBS Conference on Neural engineering, NER '09

作者： Ranade, Gireeja V. Ganguly, Karunesh Carmena, Jose Department of Electrical Engineering and Computer Sciences University of California Berkeley CA United States Helen Wills Neruoscience Institute University of California Berkeley CA United States Program in Cognitive Science University of California Berkeley CA United States Department of Neurology University of California San Francisco CA United States

ISBN: (纸本)9781424420735

Beta band oscillations in the local field potential (LFP) have been previously related to behavior in motor tasks. We investigated the correlations between beta oscillations and movement state for brain-machine interfaces. Two macaque monkeys were trained to perform a center-out motor task on a computer under normal movement control and under a 'brain control' paradigm, where neural firing directly controls the cursor. In both cases, LFP beta power decreased after movement onset. High beta power was predominantly observed with low movement velocity and vice versa. This observation was used to predict the stationarity of a computer cursor during brain control. ©2009 IEEE.

关键词： Interface states

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On detection with partial information in the Gaussian setup

On detection with partial information in the Gaussian setup

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Annual Allerton Conference on Communication, Control, and Computing

作者： Onur Özyeşil M. Kivanç Mihçak Yğcel Altug PACM (the Program in Applied and Computational Mathematics) Princeton University Princeton NJ USA Electrical and Electronics Engineering Department Boğaziçi University Istanbul Turkey School of Electrical and Computer Engineering Cornell University Ithaca NY USA

We introduce the problem of communication with partial information, where there is an asymmetry between the transmitter and the receiver codebooks. Practical applications of the proposed setup include the robust signal hashing problem within the context of multimedia security and asymmetric communications with resource-lacking receivers. We study this setup in a binary detection theoretic context for the additive colored Gaussian noise channel. In our proposed setup, the partial information available at the detector consists of dimensionality-reduced versions of the transmitter codewords, where the dimensionality reduction is achieved via a linear transform. We first derive the corresponding MAP-optimal detection rule and the corresponding conditional probability of error (conditioned on the partial information the detector possesses). Then, we constructively quantify an optimal class of linear transforms, where the cost function is the expected Chernoff bound on the conditional probability of error of the MAP-optimal detector.

关键词： Transmitters Protection Context Detectors Noise robustness Information security engineering profession Signal processing Privacy Bidirectional control

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Probabilistic structure from sound

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Advanced Robotics 2009年第12-13期23卷 1687-1702页

作者： Wang, Chieh-Chih Lin, Chi-Hao Hu, Jwu-Sheng Department of Computer Science and Information Engineering Graduate Institute of Networking and Multimedia National Taiwan University Taipei 10617 Taiwan Intelligent Robotics Program of Industrial Technology Research Institute Department of Electrical and Control Engineering National Chiao Tung University HsinChu 310 Taiwan

Auditory perception is one of the most important functions for robotics applications. Microphone arrays are widely used for auditory perception in which the spatial structure of microphones is usually known. In practice, microphone array calibration can be tedious and other devices or means are required. The structure from sound (SFS) approach addresses the problem of simultaneously localizing a set of microphones and a set of acoustic events that provides a great flexibility to calibrate different setups of microphone arrays. However, the existing method does not take measurement uncertainty into account and does not provide uncertainty estimates of the SFS results. In this paper, we propose a probabilistic structure from sound (PSFS) approach using the unscented transform in which the uncertainties of the PSFS results are also available. In addition, a probabilistic sound source localization approach using the PSFS results is provided to improve sound source localization accuracy. The ample results of simulation and experiments using low-cost, off-the-shelf microphones demonstrate the feasibility and performance of the proposed PSFS approach. © 2009 VSP.

关键词： Microphone array

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Center for resources in general education (CIVIS): Towards student success in general and STEM education

Center for resources in general education (CIVIS): Towards s...

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39th Annual Frontiers in Education Conference: Imagining and engineering Future CSET Education, FIE 2009

作者： O'Neill-Carrillo, Efraín Collins, Dana L. Garriga, Juan López MacChiavelli, Raúl Cruz, José A. University of Puerto Rico-Mayagüez Puerto Rico Electrical and Computer Engineering Department Puerto Rico CIVIS: Center for Resources in General Education UPRM United States Department of Humanities United States Department of Chemistry Puerto Rico Science on Wheels Program UPRM Puerto Rico College of Agricultural UPRM Puerto Rico College of Business Administration UPRM Puerto Rico

ISBN: (纸本)9781424447152

Researchers at the University of Puerto Rico-Mayaguez (UPRM) have conducted an analysis of student needs and have identified strategies to respond to the General and STEM education challenges at UPRM. A Center for Resources in General Education (CIVIS) has been established to deal with these challenges by providing students and professors a new, integrated perspective (focused on General and STEM skills) of the curriculum, and by enabling student academic success through various learning opportunities. CIVIS brings together faculty from Agricultural Sciences, Arts and Sciences, Business Administration and engineering in order to develop activities that provide interdisciplinary and global perspectives to UPRM's General Education. The Center focuses on two main activities: 1) Paths to Student Success, and 2) Sustainable Context with the use of student learning modules tying the activities together. AU initiatives of the Center are supported by a recent grant from the U.S. department of Education, and are based on the success of initiatives that have been previously tested at a smaller scale at UPRM. CIVIS provides resources to expand the reach of those initiatives and will ensure sustainability by the institutionalization of those initiatives. ©2009 IEEE.

关键词： Students

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Instantaneous rate estimation of neuronal point processes from a compressed representation of their nonbinary spike trains

Instantaneous rate estimation of neuronal point processes fr...

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International Conference on Acoustics, Speech, and Signal Processing (ICASSP)

作者： Mehdi Aghagolzadeh Karim Oweiss Electrical & Computer Engineering Department Michigan State University East Lansing MI USA Neuroscience Program Michigan State University East Lansing MI USA

Estimating rate functions underlying neural point processes is essential for characterizing the firing patterns of cortical neurons involved in sensory and motor processing. This paper introduces a new method for directly estimating neuronal firing rates from a compressed representation of their extracellular recordings. The approach is based on extending a near-optimal sparse representation of the extracellular recordings to time scales matching those of the underlying rate functions, thereby performing the same role as a kernel-density estimator but at a much lower computational cost. Experimental results demonstrate that this method achieves comparable performance to the conventional Gaussian kernel estimation methods at a fraction of the computational cost. This makes it suitable to brain machine interface applications where real time decoding of neural activity for neuro-motor prosthetic control using firing rate estimates is strongly desired.

关键词： Neurons Decoding Sorting Yield estimation Kernel State estimation Neuroscience Extracellular Computational efficiency Neural prosthesis

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