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

作者： Thomas T. Lee Ofer Levi Jianhua Cang Megumi Kaneko Michael P. Stryker Stephen J Smith Krishna V. Shenoy James S. Harris Department of Electrical Engineering University of Stanford Stanford CA USA Departments of Electrical Engineering and Applied Physics University of Stanford Stanford CA USA Department of Physiology University of California San Francisco USA Department of Molecular and Cellular Physiology and the Neurosciences Program University of Stanford Stanford CA USA Department of Electrical Engineering and the NeurosciencesProgram University of Stanford Stanford CA USA Departments of Electrical Engineering Applied Physics and Materials Science and Engineering University of Stanford Stanford CA USA

Intrinsic optical signal (IOS) imaging is a widely accepted technique for imaging brain activity. We propose an integrated device consisting of interleaved arrays of gallium arsenide (GaAs) based semiconductor light sources and detectors operating at telecommunications wavelengths in the near-infrared. Such a device will allow for long-term, minimally invasive monitoring of neural activity in freely behaving subjects, and will enable the use of structured illumination patterns to improve system performance. In this work we describe the proposed system and show that near-infrared IOS imaging at wavelengths compatible with semiconductor devices can produce physiologically significant images in mice, even through skull

关键词： Optical sensors Optical imaging Gallium arsenide Brain Optical arrays Sensor arrays Light sources Minimally invasive surgery Monitoring Lighting

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Adaptive control for nonnegative dynamical systems with arbitrary time delay

Adaptive control for nonnegative dynamical systems with arbi...

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American Control Conference (ACC)

作者： V. Chellaboina W.M. Haddad J. Ramakrishnan T. Hayakawa Department of Mechanical Aerospace and Biomedical Engineering University of Tennessee Knoxville TN USA Georgia Institute of Technology School of Applied and Engineering Physics Atlanta GA USA Mechanical and Environmental Informatics Tokyo Institute of Technology Tokyo Japan

In this paper, we develop a direct adaptive control framework for uncertain linear nonnegative dynamical systems with unknown time delay. The specific focus of the paper is on compartmental pharmacokinetic models and their applications to drug delivery systems. In particular, we develop a Lyapunov-Krasovskii-based direct adaptive control framework for guaranteeing set-point regulation of the closed-loop system in the nonnegative orthant in the presence of unknown system time delay. The framework additionally guarantees nonnegativity of the control signal. Finally, we demonstrate the framework on a drug delivery model for general anesthesia involving system time delays

关键词： Adaptive control Delay effects Biological system modeling Drug delivery Anesthesia Biological materials Space technology Aerospace engineering programmable control Medical control systems

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Enhancement of light extraction in GaInN light-emitting diodes by conductive omni-directional reflectors

Enhancement of light extraction in GaInN light-emitting diod...

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Conference on Lasers and Electro-Optics (CLEO)

作者： Jong Kyu Kim J.-Q. Xi Hong Luo E. Fred Schubert Jaehee Cho Cheolsoo Sone Yongjo Park Electrical Computer and Systems Engineering Department Rensselaer Polytechnic Institute Troy NY USA Department of Physics Applied Physics and Astronomy Rensselaer Polytechnic Institute Troy NY USA Photonics Program Team Samsung Advanced Institute of Technology Suwon South Korea

Enhancement of light extraction in a GaInN light-emitting diode employing a conductive omnidirectional reflector consisting of GaN, an indium-tin oxide nanorod low-refractive-index layer, and an Ag layer is presented.

ISBN: (纸本)1557528136

关键词： Indium tin oxide Light emitting diodes Refractive index Gallium nitride Films Reflectivity Optical reflection

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Detection of Lung Cancer with Phase-Contrast X-ray Imaging Using Synchrotron Radiation

Detection of Lung Cancer with Phase-Contrast X-ray Imaging U...

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

作者： Ping Liu Jianqi Sun Yijing Guan Guilin Zhang Lisa Xuemin Xu School of Life Science and Technology Shanghai Jiaotong University Shanghai China Shanghai Institute of Applied Physics Chinese Academy and Sciences Shanghai China School of Mechanical Engineering and Department of Biomedical Engineering Purdue University Calumet West Lafayette IN USA

In the present study, the feasibility of applying synchrotron radiation for the detection of lung cancers was investigated. Lung cancer tissues grown in mice over different periods were observed with phase-contrast synchrotron X-ray chest imaging. Irregular and tortuous vessels appearing in early cancer angiogenesis were found in the periphery region of the implanted cancer. Structure difference was clearly shown between normal tissue and early stage solid cancer in micrometers. Results from this study indicate that synchrotron X-ray may open broad perspectives for imaging cancer development and progression noninvasively

关键词： Cancer detection Phase detection Radiation detectors X-ray detection X-ray detectors Lungs X-ray imaging Synchrotron radiation Optical imaging Mice

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Magnetic fibre and paper for information storage

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Paper Asia 2006年第3期22卷 31-33页

作者： Ong, B.H. Zakaria, S. Ahmad, S. Abdullah, M. Yusoff, M.N.M. Liang, M.S. Van De Ven, T.G.M. Faculty of Engineering Multimedia University Jalan Multimedia Selangor Darul Ehsan Malaysia Materials Science Program School of Applied Physics Universiti Kebangsaan Malaysia 43600 Bangi Selangor Malaysia Physics Program School of Applied Physics Universiti Kebangsaan Malaysia 43600 Bangi Selangor Malaysia Wood Chemistry Division Forest Research Institute Malaysia Kepong 52109 Kuala Lumpur Malaysia Department of Mechanical Engineering College of Engineering Universiti Tenaga Nasional Km 7 Jalan Kajang - Puchong 43009 Kajang Selangor Malaysia Department of Chemistry Pulp and Paper Research Centre McGill University Montreal H3A 2A7 Canada

Magnetic paper via lumen loading process was prepared from neverdried and dried kraft pulp. Polyethylenimine (PEI) was used as retention aid during the inter-stage treatment. The paper produced from the magnetic pulp showed an increase of magnetic properties as the loading increased. The physical properties of the paper such as tensile index, burst index, tear and folding endurance showed a reduction in the strength value as the loading capacity increased. The lumen-loaded paper shows better physical properties than conventionally loaded paper. The flocculation study shows that the magnetic colloid exists in multi particles aggregates form in water solution, which caused by magnetodipole interaction.

关键词： Papermaking

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Mechanism of enhanced broadening of the ionization level of Li outside transition metal surfaces

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Physical Review B 2006年第11期74卷 115109-115109页

作者： Keith Niedfeldt Peter Nordlander Emily A. Carter Department of Mechanical and Aerospace Engineering and Program in Applied and Computational Mathematics Princeton University Princeton New Jersey 08544-5263 USA Department of Physics and Astronomy M.S. 61 Rice University P.O. Box 1892 6100 South Main Street Houston Texas 77251-1892 USA

We show that the d-band of a transition metal surface induces intra-atomic hybridization of an atom in its vicinity. It is demonstrated that such hybridization can have a profound influence on the resonance width and hence lifetime of the atomic ionization level. The degree of Li s−p hybridization is found to be directly correlated to the overlap of the d-band density of states with the Li 2s and 2p levels, and is shown to be not due solely to long-range electrostatic image potential effects.

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Pinhole Trajectories for SPECT Imaging of the Breast, Axilla, and Upper Chest

Pinhole Trajectories for SPECT Imaging of the Breast, Axilla...

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： James E. Bowsher Justin R. Roper Joerg Peter Ronald J. Jaszczak Departments of Radiation Oncology and Radiology Duke University Medical Center Durham NC USA Medical Physics Graduate Program University Medical Center Durham NC USA German Cancer Research Center Heidelberg Germany Department of Biomedical Engineering Duke University Durham NC USA

Several methods have been proposed for dedicated SPECT imaging of the breast. Two key characteristics achieved by these methods are shortened distance and lessened attenuation between the SPECT collimator and the breast. However, many of these methods are unable to image the important regions of the axilla and upper chest. Partial-Circle pinhole trajectories can image into the axilla, but only over a narrow axial range. Here we propose X and X-Line trajectories that can effectively image a broad axial range of the breast, axilla, and upper chest. The X and X-Line trajectories provide a third dimension of pinhole displacement, which is key to expanding the range of sufficient sampling. In order to investigate spatial variations in the imaging characteristics of different pinhole trajectories, phantoms were constructed with hot lesions and Defrise slabs distributed throughout the breast and torso. Projection data were computer simulated, and images were reconstructed by OSEM. These studies indicate that all three trajectories can sample activity well into the axilla. However, the axial range of good sampling is narrow with the Partial-Circle trajectory. The X and X-Line trajectories provide good sampling well into the axilla and over a broad axial range. The convex hulls of the X and X-Line trajectories encompass the breast and much of the axilla and upper chest, thereby satisfying Tuy's condition for sufficient sampling of those regions, truncation issues aside. The spatial extent of the convex hull is tunable. At the same time, the X and X-Line trajectories achieve two other key characteristics of dedicated SPECT breast imaging: Shortened average distance and lessened average attenuation between the collimator, i.e. the pinhole, and the breast and other nearby tissue of interest.

关键词： Breast Axilla Image sampling Attenuation Collimators Imaging phantoms Lesions Slabs Torso Computational modeling

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Three-Dimensional Tomosynthesis Reconstruction from 1D and 2D X-ray Source Arrays

Three-Dimensional Tomosynthesis Reconstruction from 1D and 2...

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IEEE Symposium on Nuclear Science (NSS/MIC)

作者： David Lalush Ramya Rajaram Enzhuo Quan Jian Zhang Jianping Lu Otto Zhou Joint Department of Biomedical Engineering North Carolina State University Raleigh NC USA Curriculum in Applied and Meterials Sciences North Carolina State University Chapel Hill USA Department of Radiation Oncology North Carolina State University Chapel Hill NC USA Department of Physics and Astronomy North Carolina State University Chapel Hill NC USA

We study the effects of geometric design on the reconstruction of 3D images from an X-ray tomosynthesis system using microfabricated discrete X-ray sources. Carbon-nanotube-based field-emission X-ray sources can be fabricated in arrays; however, little is known about the effects of the geometry of such a system on reconstruction of tomosynthesis data. We produced simulated X-ray projection data for several source array geometries including a 1 times 11 array, and a 3 times 11 array. The phantom simulates a mammography task, with seven 400 mum spheres embedded in a uniformly-absorbing background. Data from both geometries was reconstructed using the ordered-subset convex (OSC) algorithm specially implemented for these array geometries. Reconstruction was performed on an 800 times 800 (lateral) times 20 (depth) array of noncubic voxels of size 200 mum times 200 mum (lateral) times 2.5 mm (depth). Contrast, resolution, and noise measurements on the reconstructed spheres were used to compare results from the different geometries. The reconstruction from the 2D array had higher contrast than that from the 1D array, but the 2D array image also suffered from higher levels of noise for the same total exposure. The contrast-to-noise ratio for the 2D array, was 5-17% higher than the 1D array. Other studies showed that staggering a 2D array is beneficial, and that increasing the density of sources is detrimental after a certain optimal density is reached We conclude that, in a tomosynthesis system such as that described here, a 2D source array will outperform a 1D array in terms of contrast-to-noise and resolution, while also increasing the usable field-of-view, and that further studies encompassing the effects of scatter will be needed to optimize such systems.

关键词： Image reconstruction X-ray imaging Geometry Carbon nanotubes Solid modeling Imaging phantoms Mammography Noise measurement Noise level X-ray scattering

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Collective coordinate control of density distributions

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Physical Review E 2006年第3期74卷 031104-031104页

作者： Obioma U. Uche Salvatore Torquato Frank H. Stillinger Department of Chemical Engineering Princeton University Princeton New Jersey 08544 USA Department of Chemistry Princeton University Princeton New Jersey 08544 USA Princeton Institute for the Science and Technology of Materials Princeton University Princeton New Jersey 08544 USA Program in Applied & Computational Mathematics Princeton University Princeton New Jersey 08544 USA Princeton Center for Theoretical Physics Princeton University Princeton New Jersey 08544 USA

Real collective density variables C(k) [cf. Eq. (1.3)] in many-particle systems arise from nonlinear transformations of particle positions, and determine the structure factor S(k), where k denotes the wave vector. Our objective is to prescribe C(k) and then to find many-particle configurations that correspond to such a target C(k) using a numerical optimization technique. Numerical results reported here extend earlier one- and two-dimensional studies to include three dimensions. In addition, they demonstrate the capacity to control S(k) in the neighborhood of ∣k∣=0. The optimization method employed generates multiparticle configurations for which S(k)∝∣k∣α, ∣k∣⩽K, and α=1, 2, 4, 6, 8, and 10. The case α=1 is relevant for the Harrison-Zeldovich model of the early universe, for superfluid He4, and for jammed amorphous sphere packings. The analysis also provides specific examples of interaction potentials whose classical ground states are configurationally degenerate and disordered.

关键词： STATISTICAL MECHANICS REALIZABILITY SYSTEM

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Experimental Measurement of Single-Wall Carbon Nanotube Torsional Properties

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Physical Review Letters 2006年第25期96卷 256102-256102页

作者： A. R. Hall L. An J. Liu L. Vicci M. R. Falvo R. Superfine S. Washburn Curriculum in Applied and Materials Sciences University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599 USA Department of Chemistry Duke University Durham North Carolina 27708 USA Department of Computer Science University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599 USA Department of Physics and Astronomy University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599 USA Department of Biomedical Engineering University of North Carolina at Chapel Hill Chapel Hill North Carolina 27599 USA

We report on the characterization of nanometer-scale torsional devices based on individual single-walled carbon nanotubes as the spring elements. The axial shear moduli of the nanotubes are obtained through modeling o... 详细信息

关键词： .torsional PRL week ending Carolina at Chapel Chapel Hill Chapel Hill North Carolina

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