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In-situ TEM Study of Bismuth Nanostructures

MRS Online Proceedings Library 2008年第1期1044卷 1-7页

作者： Xiaoting Jia Vincent Berube Shuo Chen Bed Poudel Son Hyungbin Jing Kong Yang Shao-Horn Ren Zhifeng Gang Chen Mildred S. Dresselhaus Material Sciences and Engineering MIT Cambridge USA Physics MIT Cambridge USA Mechanical Engineering MIT Cambridge USA Physics Boston College Chestnut Hill USA Electrical Engineering and Computer Science MIT Cambridge USA

Nanostructured thermoelectric materials have attracted lots of interest in recent years, due to their enhanced performance determined by their thermoelectric dimensionless figure of merit. However, because of equipment limitations, not much work has been done on combining simultaneous transport measurements and structural characterization on individual nanostructured thermoelectric materials. With an integrated TEM-STM system, we studied the structural behavior and electrical properties of bismuth (Bi) nanobelts and nanoparticles. Results showed that clean Bi nanostructures free of oxides can be produced by in-situ high temperature electro-migration and Joule annealing processes occurring within the electron microscope. Preliminary electrical measurements indicate a conductivity of two orders of magnitude lower for Bi nanoparticles than that for bulk Bi. Such in-situ studies are highly advantageous for studying the semimetal-semiconductor transition and how this transition could enhance thermoelectric properties.

关键词： nanostructure Bi transmission electron microscopy (TEM)

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Subthreshold Characteristics of High-performance Inversion-type Enhancement-mode InGaAs NMOSFETs with ALD A12O3 as Gate Dielectric

Subthreshold Characteristics of High-performance Inversion-t...

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Device Research Conference

作者： P.D. Ye Y. Xuan Y. Q. Wu T. Shen H. Pal D. Varghese M. A. Alam M. S. Lundstrom W.K. Wang J.C.M. Hwang D.A. Antoniadis School of Electrical and Computer Engineering Purdue University West Lafayette IN USA Department of Electrical Engineering Lehigh University Bethlehem PA USA Department of Electrical Engineering and Computer Science MIT Cambridge MA USA

In this paper, high-performance inversion-type E-mode In 0.53 Ga 0.47 As and In 0.65 Ga 0.35 As MOSFETs with ALD Al 2 O 3 as gate dielectric is demonstrated and systematically studied their subthreshold or weak inversion characteristics. Much more works are needed to make this novel device structure a competitive technology for ultimate CMOS at 22 nm node or beyond. The work is supported by National science Foundation and SRC FCRP MSD Center.

关键词： Indium gallium arsenide MOSFETs Dielectrics Threshold voltage CMOS technology Electrons computer science III-V semiconductor materials Logic devices Application software

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Predicting occurrences of acute hypoglycemia during insulin therapy in the intensive care unit

Predicting occurrences of acute hypoglycemia during insulin ...

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

作者： Ying Zhang Division of Health Sciences and Technology and MIT Department of Electrical Engineering and Computer Science Harvard Medical School-MIT Cambridge MA USA

As intensive care units (ICUs) implement more intense insulin therapy to achieve tighter glycemic control, the risk for ICU patients to experience acute hypoglycemia increases. This study aims to develop a new method for predicting the occurrences of acute hypoglycemia during intravenous (IV) insulin infusion before the actual hypoglycemic events take place. Data from 3116 adult ICU patients have been retrospectively analyzed to elucidate glycemic dynamics and to devise a methodology for proactive prediction of acute hypoglycemic events in the ICU. Mutual information, embedded selection by classification trees, and odds ratios of categorized clinical time-series and occurrences of acute hypoglycemia were used to compare features of patients' glycemic dynamics. Classification tree learning was then applied to key features to generate predictive models of acute hypoglycemia. Results show that the two most recent blood glucose measurements and the slope of recent changes in blood glucose concentration with respect to the change in insulin infusion are the most informative features. Classification tree models built upon the key features accurately predicted 82.12% of acute hypoglycemic events (specificity: 89.87%; positive predictive value: 88.72%; accuracy: 86.00%) and 76.99% of severe acute hypoglycemic events (80.53%, 74.31%, and 78.76% respectively). The mechanistic approach developed in this study could be useful to discovering and understanding trends in clinical data leading up to acute hypoglycemia.

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Frontiers of Electronic Voting - Dagstuhl Seminar 07311

Frontiers of Electronic Voting - Dagstuhl Seminar 07311

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Frontiers of Electronic Voting 2007

作者： Chaum, David Kutylowski, Miroslaw Rivest, Ronald Ryan, Peter Y.A. Wroclaw University of Technology Institute of Mathematics and Computer Science Wybrzeze Wyspiańskiego Wroclaw50-370 Poland MIT Department of Electrical Engineering and Computer Science 77 Massachusetts Avenue CambridgeMA02139-4307 United States University of Newcastle upon Tyne School of Computing Science Newcastle upon TyneNE1 7RU United Kingdom

This is a short report on Dagstuhl Seminar 07311 - Frontiers of Electronic Voting, 29.07.07 - 03.08.07, organized in The International Conference and Research Center for computer science (IBFI, Schloss Dagstuhl). ... 详细信息

关键词： Voting machines

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Competitive analysis of opportunistic spectrum access strategies

Competitive analysis of opportunistic spectrum access strate...

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INFOCOM 2008: 27th IEEE Communications Society Conference on computer Communications

作者： Chang, Nicholas B. Liu, Mingyan Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109-2122 United States University of Michigan Advanced Sensor Techniques Group MIT Lincoln Laboratory 244 Wood Street Lexington MA 02420-9108 United States

ISBN: (纸本)9781424420261

We consider opportunistic spectrum access (OSA) strategies for a transmitter in a multichannel wireless system, where a channel may or may not be available and the transmitter must sense/probe the channel to find out before transmission. Applications for this work include joint probing and transmission for a secondary user in a cognitive radio network. Limited by resources, e.g., energy and time, the transmitter must decide on a subset of a potentially very large number of channels to probe and can only use for transmission those that have been found to be available. In contrast to previous works, we do not assume the user has a priori knowledge regarding the statistics of channel states. The main goal of this work is to design strategies that decide, based only on knowledge of the channel bandwidths/data rates, which channels to probe. We derive optimal strategies that maximize the total expected bandwidth/data rate in the worst-case, via a performance measure in the form of a competitive regret (ratio) between the average performance of a strategy and a genie (or omniscient observer). We examine the performance of these optimal strategies under a wide range of system parameters and practical channel models via numerical studies. © 2008 IEEE.

关键词： Transmitters

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IEEE Transactions on Haptics: Editorial

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IEEE Transactions on Haptics 2008年第1期1卷 2-8页

作者： Edward Colgate, J. Lederman, Susan Prattichizzo, Domenico Barbagli, Federico Basdogan, Cagatay Buss, Martin Ernst, Marc Frisoli, Antonio Gillespie, Brent Grant, Danny Harders, Matthias Hayward, Vincent Jones, Lynette Kajimoto, Hiroyuki Kappers, Astrid Kheddar, Abderrahmane Lin, Ming C. MacLean, Karon Miller, Brian Noma, Haruo Okamura, Allison M. O'Malley, Mareia Ryu, Jeha Tan, Hong Z. Yokokohji, Yasuyoshi Department of Psychology School of Computing Queen's University Canada IEEE Robotics and Automation Society Tübingen Germany Stanford University's Computer Science Department Tübingen Germany Institute of Automatic Control Engineering Technische Universität München Germany Independent Research Group Multisensory Perception and Action Max Planck Institute for Biological Cybernetics Tübingen Germany Department of Applied Mechanics SSSA Japan Research Division Virtual Reality and Telerobotic Systems PERCRO Laboratory Japan Department of Mechanical Engineering Japan Department of Robotics McGill University Canada Computer Vision Lab ETH Zurich Japan Virtual Reality in Medicine Group Japan IEEE CS/RAS Technical Committee on Haptics Japan Department of Electrical and Computer Engineering McGill University Canada Department of Mechanical Engineering MIT Japan University of Electro-Communications Japan Department of Physics and Astronomy Utrecht University Netherlands University of Evry France Chapel Hill United States Department of Computer Science University of British Columbia Canada ATR Knowledge Science Lab United Kingdom Department of Mechanical Engineering Denmark Johns Hopkins University United States Laboratory for Computational Sensing and Robotics United Kingdom Engineering Research Center for Computer-Integrated Surgical Systems and Technology United States Mechanical Engineering and Materials Science Department Rice University United States Korea Republic of Department of Electrical and Computer Engineering Mechanical Engineering and Psychological Sciences Purdue University United States Department of Mechanical Engineering and Science Graduate School of Engineering Kyoto University Japan

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Harnessing chemical energy for hydrogen purification in microreactors

Harnessing chemical energy for hydrogen purification in micr...

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2008 AIChE Annual Meeting, AIChE 100

作者： Deshpande, Kishori Adamo, Andrea Schmidt, Martin A. Jensen, Klavs F. Engineering and Process Sciences Dow Chemical Company 2301 N. Brazosport Boulevard Freeport TX 77541 United States Chemical Engineering Massachusetts Institute of Technology 25 Ames Street Cambridge MA 02142 United States Electrical Engineering and Computer Science Massachusetts Institute of Technology 77 Massachusetts Avenue Cambridge MA 02139 United States Chemical Engineering and Materials Science and Engineering MIT 77 Massachusetts Ave. Cambridge MA 02139 United States

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Design of electrical stimulation bioreactors for cardiac tissue engineering

Design of electrical stimulation bioreactors for cardiac tis...

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

作者： N. Tandon A. Marsano C. Cannizzaro J. Voldman G. Vunjak-Novakovic Department of Biomedical Engineering Columbia University New York NY USA Tufts University Medford MA USA Department of Electrical Engineering and Computer Science MIT Cambridge MA USA

electrical stimulation has been shown to improve functional assembly of cardiomyocytes in vitro for cardiac tissue engineering. Carbon electrodes were found in past studies to have the best current injection characteristics. The goal of this study was to develop rational experimental design principles for the electrodes and stimulation regime, in particular electrode configuration, electrode ageing, and stimulation amplitude. Carbon rod electrodes were compared via electrochemical impedance spectroscopy (EIS) and we identified a safety range of 0 to 8 V/cm by comparing excitation thresholds and maximum capture rates for neonatal rat cardiomyocytes cultured with electrical stimulation. We conclude with recommendations for studies involving carbon electrodes for cardiac tissue engineering.

关键词： Electrodes electrical stimulation Voltage measurement Immune system Length measurement Bioreactors Carbon

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Correlation between optical coherence tomography (OCT) and optical intrinsic signal imaging (OISI) during functional brain activation

Correlation between optical coherence tomography (OCT) and o...

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Biomedical Optics, BIOMED 2008

作者： Chen, Y. Aguirre, A.D. Ruvinskaya, L. Devor, A. Boas, D.A. Fujimoto, J.G. Department of Electrical Engineering Computer Science and Research Laboratory of Electronics Massachusetts Institute of Technology Cambridge MA 02139 United States Harvard-MIT Division of Health Sciences and Technology Cambridge MA United States Martinos Center for Biomedical Imaging Department of Radiology Massachusetts General Hospital Harvard Medical School Charlestown MA 02129 United States

Simultaneous OCT and OISI were performed on rat somatosensory cortex during forepaw stimulation. The depth-integrated OCT signal correlates well with OISI signal, while OCT resolves layer-specific dynamics in function... 详细信息

关键词： Optical tomography

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A combined top-down and bottom-up approach for precise placement of metal nanoparticles on silicon (vol 4, pg 330, 2008)

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SMALL 2008年第4期4卷 393-393页

作者： Choi, W. K. Liew, T. H. Chew, H. G. Zheng, F. Thompson, C. V. Wang, Y. Hong, M. H. Wang, X. D. Li, L. Yun, J. Microelectronics Laboratory Department of Electrical and Computer Engineering National University of Singapore 117576 Singapore Singapore Fax: (+65) 677-911-03 Department of Materials Science and Engineering Massachusetts Institute of Technology Cambridge MA 02139 USA ECE-DSI Laser Microprocessing Laboratory Department of Electrical and Computer Engineering National University of Singapore 117576 Singapore Singapore Advanced Materials for Micro- and Nano-Systems Singapore-MIT Alliance 117576 Singapore Singapore

A combined top-down and bottom-up approach was used for precise placement of metal nanoparticles on silicon substrates. The study used laser interference lithography (LIL) technique, to open windows on a silicon wafer with a silicon oxide mask. Inverted pyramids were obtained at the window region, by etching the silicon wafer in KOH under the top-down approach. The bottom-up approach involved the evaporation of a gold (Au) layer on the whole silicon wafer and annealing at elevated temperature. The Au inside the inverted pyramids was coarsened and formed Au dots inside them. The results show that the diameter of the metal nanoparticles can be tuned more effectively, by changing the Au layer thickness, along with the annealing temperature.

关键词： gold nanolithography nanomanipulation nanoparticles silicon surfaces

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