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Direct observation of symmetry-specific precession in a ferrimagnet

Physical Review B 2015年第10期92卷 104402-104402页

作者： P. Warnicke E. Stavitski J.-S. Lee A. Yang Z. Chen X. Zuo S. Zohar W. E. Bailey V. G. Harris D. A. Arena Photon Sciences Directorate Brookhaven National Laboratory Upton New York 11973 USA Department of Electrical and Computer Engineering Northeastern University Boston Massachusetts 02115 USA Materials Science Program Department of Applied Physics Columbia University New York New York 10027 USA

Here we demonstrate an experimental observation of GHz-scale spin dynamics resolved to sublattice octahedral (Oh) tetrahedral (Td) sites in a spinel ferrimagnet, in this case a Mn-ferrite thin film. X-ray absorption spectroscopy (XAS) and x-ray magnetic circular dichroism (XMCD) are used, in combination with multiplet calculations, to uniquely identify the spectral signature from Mn2+ and Fe2+,3+ on Oh and Td lattice sites. With the sample under rf excitation, the spin alignment of the sublattices is tracked with time-resolved XMCD (TR-XMCD). The spin alignment of the sublattices is mostly antiferromagnetic. The phase difference between the Oh Fe2+ [Oh Fe3+] and Td Mn2+ sites is 181.2±3.8∘ [183.3∘±3.7∘] at 150 K and 186.6±2.2∘ [182.0∘±2.2∘] at 300 K. Such direct measurement of the dynamic coupling, exchange stiffness, and damping enabled by TR-XMCD across sublattices will be essential for optimizing the development of future-generation microwave devices.

关键词： OCTAHEDRAL molecules TETRAHEDRAL molecules FERRIMAGNETIC materials X-ray absorption SPECTRUM analysis MAGNETIC circular dichroism LATTICE dynamics MICROWAVE devices

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Toward Non-Hair-Bearing Brain-computer Interfaces for Neurocognitive Lapse Detection

Toward Non-Hair-Bearing Brain-Computer Interfaces for Neuroc...

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

作者： Chun-Shu Wei Yu-Te Wang Chin-Teng Lin Tzyy-Ping Jung the Swartz Center of Computational Neuroscience (SCCN) Center for Advanced Neurological Engineering (CANE) and Department of Bioengineering University of California San Diego (UCSD) La Jolla CA USA SCCN CANE and the Department of Computer Science and Engineering UCSD La Jolla CA USA the Brain Research Center and the Department of Electrical Engineering National Chiao Tung University Hsinchu Taiwan

ISBN: (纸本)9781424492695

Recent advances in mobile electroencephalogram (EEG) acquisition based on dry electrodes have started moving Brain-computer Interface (BCI) applications from well-controlled laboratory settings to real-world environments. However, the application mechanisms and high impedance of dry electrodes over the hair-covered areas remain challenging for everyday use of BCI. In addition, whole-scalp recordings are not always necessary or applicable due to various practical constrains. Therefore, alternative montages for EEG recordings to meet the everyday needs are in-demand. Inspired by our previous work on measuring non-hair-bearing steady state visual evoked potentials for BCI applications, this study explores the feasibility and efficacy of detecting cognitive lapses of participants based on EEG signals collected from the non-hair-bearing areas. Study results suggest that informative EEG features associated with lapses could be assessed from non-hair-bearing areas with comparable accuracy obtained from the whole-scalp EEG. The design principles, validation processes and promising findings reported in this study may enable and/or facilitate numerous BCI applications in real-world environments.

关键词： EEG BCI non-hair-bearing areas

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How to optimize global health education for undergraduates: the value of a living-learning community and practical training at the university of Maryland, college park

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Annals of Global Health 2016年第3期82卷 343-343页

作者： P. Jacob Bueno de Mesquita A. Bickford B. Brown A. Kurian E. Claure A. Silver E. Maring Maryland Institute for Applied Environmental Health School of Public Health University of Maryland College Park Global Public Health Scholars Program Office of Undergraduate Studies University of Maryland College Park Department of Behavioral and Community Health Public Health Science Program Fischell Department of Bioengineering A. James Clark School of Engineering University of Maryland College Park Department of Biology College of Computer Mathematical and Natural Sciences University of Maryland College Park

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Multi-layered covert QR codes for increased capacity and security

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International Journal of computers and Applications 2015年第1期37卷 17-27页

作者： Meruga, Jeevan M. Fountain, Carly Kellar, Jon Crawford, Grant Baride, Aravind May, P. Stanley Cross, William Hoover, Randy Materials Engineering and Science Program South Dakota School of Mines and Technology 515 E. St. Joseph St Rapid CitySD57701 United States Department of Mathematics and Computer Science South Dakota School of Mines and Technology University of South Dakota United States Department of Electrical and Computer Engineering South Dakota School of Mines and Technology University of South Dakota United States Department of Chemistry University of South Dakota United States

Quick Response (QR) codes, used in marketing, warehouse management, product tracking, and other applications, are usually only comprised of visible black and white modules. The goal of this research is the creation of covert, color QR codes for increased data capacity, and security. This goal was met by layering QR codes, each of a unique color, printing the covert versions of the color QR codes, upconverting the covert codes into visible codes and unlayering them to take advantage of the various color channels present. It was shown that color layering of the QR codes effectively increased the data capacity by three times that of a traditional QR code, while the covert nature of the code provides added security. Finally, it was also demonstrated that a layered QR code with six base colors (using color intensity variations) could further increase QR code data capacity. © 2015 Taylor and Francis.

关键词： Color

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Microfluidic Platform for Neurotransmitter Sensing Based on Cyclic Voltammetry and Dielectrophoresis for In Vitro Experiments

Microfluidic Platform for Neurotransmitter Sensing Based on ...

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

作者： Jessy Mathault Pauline Zamprogno Jesse Greener Amine Miled LABioTRON bioengineering research laboratory at electrical and computer engineering department at Laval University Faculty of Science and Engineering Adrien-Pouliot Build. 1065 Av. de la médecine Québec (Qc) Canada Dept. of Chemistry Laval University Québec (QC) Canada

ISBN: (纸本)9781424492695

This paper presents a new microfluidic platform that can simultaneously measure and locally modulate neurotransmitter concentration in a neuron network. This work focuses on the development of a first prototype including a potentiostat and electrode functionalization to detect several neurotransmitter's simultaneously. We tested dopamine as proof of concept to validate functionality. The system is based on 320 bidirectional electrode array for dielectrophoretic manipulation and cyclic voltammetry. Each electrode is connected to a mechanical multiplexer in order to reduce noise interference and fully isolate the electrode. The multiplexing rate is 476 kHz and each electrode can drive a signal with an amplitude of 60 Vpp for dielectrophoretic manipulation.

关键词： prototype including potentiostat dielectrophoretic manipulation Potentiostats Cyclic voltammetry Electrophoresis Neurotransmitters Electrodes Microfluidics Platform

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A New Integrated Fuzzifier Evaluation and Selection(NIFEs) Algorithm for Fuzzy Clustering

A New Integrated Fuzzifier Evaluation and Selection(NIFEs) A...

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2015 Workshop 7

作者： Chanpaul Jin Wang Hua Fang Sun Kim Ann Moormann Honggang Wang Division of Biostatistics and Health Services Research Department of Quantitative Health Science UMass Medical School Department of Electrical & Computer Engineering University of Massachusetts Dartmouth Department of Nursing College of Nursing and Health Sciences University of Massachusetts Program of Molecular Medicine UMass Medical School

Fuzzy C-means(FCM) is simple and widely used for complex data pattern recognition and image analyses. However, selecting an appropriate fuzzifier(m) is crucial in identifying an optimal number of patterns and achieving higher clustering accuracy, which few studies have investigated. Built upon two existing methods on selecting fuzzifier, we developed an integrated fuzzifier evaluation and selection algorithm and tested it using real datasets. Our findings indicate that the consistent optimal number of clusters can be learnt from testing different fuzzifiers for each dataset and the fuzzifier with the lowest value for this consistency should be selected for clustering. Our evaluation also shows that the fuzzifier impacts the clustering accuracy. For longitudinal data with missing values, m = 2 could be an empirical rule to start fuzzy clustering, and the best clustering accuracy was achieved for tested data, especially using our multiple-imputation based fuzzy clustering.

关键词： Fuzzifier Fuzzy C-Means Multiple Imputation-Based Fuzzy Clustering(MIFuzzy) Missing Data Longitudinal Data

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Single-cell morphological analysis for rapid antimicrobial susceptibility test

Single-cell morphological analysis for rapid antimicrobial s...

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International Conference on Solid State Sensors and Actuators (TRANSDUCERS)

作者： J. Choi J. Yoo M. Lee E.-G. Kim J. S. Lee S. Lee S. Joo S. H. Song E.-C. Kim J. C. Lee H. C. Kim Y.-G. Jung S. Kwon Department of Electrical Engineering and Computer Science Seoul National University Seoul Republic of Korea QuantaMatrix Inc. Republic of Korea Interdisciplinary Program of Bioengineering Seoul National University Graduate School Seoul Republic of Korea Department of Laboratory Medicine School of Medicine” Incheon Republic of Korea Department of Laboratory Medicine Seoul National-University Hospital Seoul Republic of Korea Institute of Medical and Biological Engineering Seoul National University Seoul Republic of Korea

A rapid antibiotic susceptibility test (AST) is desperately needed in clinical settings for fast and appropriate antibiotic administration. Traditional ASTs, which rely on cell culture, are not suitable for urgent cases of bacterial infection and antibiotic resistance owing to their relatively long test times. Here, we describe a novel AST called single-cell morphological analysis (SCMA) that can determine antimicrobial susceptibility by automatically analyzing and categorizing morphological changes in single bacterial cells under various antimicrobial conditions. The SCMA was tested with four Clinical and Laboratory Standards Institute standard bacterial strains and 189 clinical samples from hospitals. The results were compared with the gold standard broth microdilution test. The SCMA results were obtained in less than 4 hours with 91.5% categorical agreement and 6.51% minor, 2.56% major, and 1.49% very major discrepancies. Thus, SCMA provides rapid and accurate antimicrobial susceptibility data.

关键词： Microorganisms Antibiotics Strain Immune system Microfluidics Standards Imaging

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Stick-slip motion of surface point defects prompted by magnetically controlled colloidal-particle dynamics in nematic liquid crystals

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Physical Review E 2015年第5期91卷 052503-052503页

作者： Michael C. M. Varney Qiaoxuan Zhang Ivan I. Smalyukh Department of Physics University of Colorado at Boulder Boulder Colorado 80309 USA Materials Science and Engineering Program University of Colorado at Boulder Boulder Colorado 80309 USA Department of Electrical Computer and Energy Engineering and Soft Materials Research Center University of Colorado at Boulder Boulder Colorado 80309 USA Renewable and Sustainable Energy Institute National Renewable Energy Laboratory and University of Colorado at Boulder Boulder Colorado 80309 USA

We explore the dynamics of topological point defects on surfaces of magnetically responsive colloidal microspheres in a uniformly aligned nematic liquid crystal host. We show that pinning of the liquid crystal director to a particle surface with random nanostructured morphology results in unexpected translational dynamics of both particles and topological point defects on their surfaces when subjected to rotating magnetic fields. We characterize and quantify the “stick-slip” motion of defects as a function of field rotation rates as well as temperature, demonstrating the roles played by the competition of elastic forces, surface anchoring, and magnetic torques on the sphere as well as random-surface-mediated pinning of the easy axis of the nematic director on colloidal microspheres. We analyze our findings through their comparison to similar dynamic processes in other branches of science.

关键词： NEMATIC liquid crystals POINT defects PARTICLE dynamics analysis COLLOIDS STICK-slip response MAGNETIC fields

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A New Integrated Fuzzifier Evaluation and Selection (NIFEs) Algorithm for Fuzzy Clustering

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Journal of Applied Mathematics and Physics 2015年第7期3卷 802-807页

作者： Chanpaul Jin Wang Hua Fang Sun Kim Ann Moormann Honggang Wang Division of Biostatistics and Health Services Research Department of Quantitative Health Science UMass Medical School Worcester MA USA Department of Electrical & Computer Engineering University of Massachusetts Dartmouth Dartmouth MA USA Department of Nursing College of Nursing and Health Sciences University of Massachusetts Boston MA USA Program of Molecular Medicine UMass Medical School Worcester MA USA

Fuzzy C-means (FCM) is simple and widely used for complex data pattern recognition and image analyses. However, selecting an appropriate fuzzifier (m) is crucial in identifying an optimal number of patterns and achieving higher clustering accuracy, which few studies have investigated. Built upon two existing methods on selecting fuzzifier, we developed an integrated fuzzifier evaluation and selection algorithm and tested it using real datasets. Our findings indicate that the consistent optimal number of clusters can be learnt from testing different fuzzifiers for each dataset and the fuzzifier with the lowest value for this consistency should be selected for clustering. Our evaluation also shows that the fuzzifier impacts the clustering accuracy. For longitudinal data with missing values, m = 2 could be an empirical rule to start fuzzy clustering, and the best clustering accuracy was achieved for tested data, especially using our multiple-imputation based fuzzy clustering.

关键词： Fuzzifier Fuzzy C-Means Multiple Imputation-Based Fuzzy Clustering (MIFuzzy) Missing Data Longitudinal Data

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Plasmonic Nanostructures for Organic Photovoltaic Devices

Plasmonic Nanostructures for Organic Photovoltaic Devices

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Optical Nanostructures and Advanced Materials for Photovoltaics, PVLED 2014

作者： Park, Wounjhang Department of Electrical Computer and Energy Engineering Materials Science and Engineering Program University of Colorado BoulderCO80309-0425 United States

We report the latest progress on plasmonic nanostructures for organic photovoltaic devices. Specifically, three aspects will be discussed: plasmon-exciton interaction, combined optical and electrical modeling and plas... 详细信息

ISBN: (纸本)9781557527561

关键词： Plasmonics

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