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Two-channel spectroscopic reflectometry for in situ monitoring of blanket and patterned structures during reactive ion etching

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Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures 2000年第6期18卷 2785-2793页

作者： Stutzman, Brooke S. Huang, Hsu-Ting Terry Jr., Fred L. Applied Physics Program University of Michigan Ann Arbor MI 48109 United States Dept. of Elec. Eng. and Comp. Sci. University of Michigan Ann Arbor MI 48109 United States Applied Physics Program Dept. of Elec. Eng. and Comp. Sci. University of Michigan Ann Arbor MI 48109 United States

A low cost, high speed, high accuracy in situ thin film measurement system for real time process monitoring and industrial process control has been developed. The system features a two channel spectroscopic reflectometer (2CSR), a hybrid of spectroscopic ellipsometry and spectroscopic reflectometry, used during reactive ion etching. The accuracy of the 2CSR, makes it a viable technique for patterned wafer analysis.

关键词： Plasma etching

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Signal Analysis of the Singing Voice: Low-Order Representations of Singer Identity 26

Signal Analysis of the Singing Voice: Low-Order Representati...

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26th International Computer Music Conference, ICMC 2000

作者： Mellody, Maureen Wakefield, Gregory H. Applied Physics Program University of Michigan United States Department of Electrical Engineering and Computer Science University of Michigan United States

Signals from 12 soprano and mezzo-soprano singers are analyzed with the modal distribution, a high-resolution time-frequency analysis method, to obtain measures of instantaneous amplitude and frequency of the signals’ partial components. These estimates are used to construct singer-specific transfer functions for each vowel and pitch analyzed. An AR approximation to a residual representation of these transfer functions is determined. This low-order residual approximation is used in a hierarchical clustering experiment. Using this representation, functions from each singer for a given vowel tend to cluster into a single class before classes collapse across singers. This result suggests that the low-order residual approximation captures singer-specific features in the sung signals. © 2000 ICMC. All Rights Reserved.

关键词： Transfer functions

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Equilibrium Distribution of Heavy Quarks in Fokker-Planck Dynamics

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Physical Review Letters 2000年第1期84卷 31-31页

作者： D. Brian Walton Johann Rafelski Program in Applied Mathematics University of Arizona Tucson Arizona 85721 Physics Department University of Arizona Tucson Arizona 85721

We obtain an explicit generalization, within Fokker-Planck dynamics, of Einstein's relation between drag, diffusion, and the equilibrium distribution for a spatially homogeneous system, considering both the transverse and longitudinal diffusion for dimension n>1. We provide a complete characterization of the equilibrium distribution in terms of the drag and diffusion transport coefficients. We apply this analysis to charm quark dynamics in a thermal quark-gluon plasma for the case of collisional equilibration.

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Twirling and Whirling: Viscous Dynamics of Rotating Elastic Filaments

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Physical Review Letters 2000年第7期84卷 1623-1623页

作者： Charles W. Wolgemuth Thomas R. Powers Raymond E. Goldstein Department of Physics University of Arizona Tucson Arizona 85721 Division of Engineering and Applied Sciences Harvard University Cambridge Massachusetts 02138 Program in Applied Mathematics University of Arizona Tucson Arizona 85721

Motivated by diverse phenomena in cellular biophysics, including bacterial flagellar motion and DNA transcription and replication, we study the overdamped nonlinear dynamics of a rotationally forced filament with twist and bend elasticity. Competition between twist injection, twist diffusion, and writhing instabilities is described by coupled PDEs for twist and bend evolution. Analytical and numerical methods elucidate the twist/bend coupling and reveal two regimes separated by a Hopf bifurcation: (i) diffusion-dominated axial rotation, or twirling, and (ii) steady-state crankshafting motion, or whirling. The consequences of these phenomena for self-propulsion are investigated, and experimental tests proposed.

关键词：细菌生理学 DNA/化学 DNA/超微结构扩散弹性鞭毛/化学鞭毛/生理学鞭毛/超微结构行走/生理学旋转黏度

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Bistable Helices

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Physical Review Letters 2000年第7期84卷 1631-1631页

作者： Raymond E. Goldstein Alain Goriely Greg Huber Charles W. Wolgemuth Department of Physics University of Arizona Tucson Arizona 85721 Program in Applied Mathematics University of Arizona Tucson Arizona 85721 Department of Mathematics University of Arizona Tucson Arizona 85721

We extend elasticity theory of filaments to encompass systems, such as bacterial flagella, that display competition between two helical structures of opposite chirality. A general, fully intrinsic formulation of the dynamics of bend and twist degrees of freedom is developed using the natural frame of space curves, spanning from the inviscid limit to the viscously overdamped regime applicable to cellular biology. Aspects of front propagation found in flagella are discussed.

关键词：芽孢杆菌枯草/细胞学弹性鞭毛/化学鞭毛/生理学鞭毛/超微结构模型生物学运动(Motion) 沙门菌属/细胞学热力学转矩黏度

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Chiral Self-Propulsion of Growing Bacterial Macrofibers on a Solid Surface

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Physical Review Letters 2000年第7期84卷 1627-1627页

作者： Neil H. Mendelson Joelle E. Sarlls Charles W. Wolgemuth Raymond E. Goldstein Department of Molecular and Cellular Biology University of Arizona Tucson Arizona 85721 Department of Physics University of Arizona Tucson Arizona 85721 Program in Applied Mathematics University of Arizona Tucson Arizona 85721

Supercoiling motions that accompany the growth of bacterial macrofibers (multicellular filamentous structures formed in B. subtilis by cell division without separation) are responsible for rolling, pivoting, and walking of fibers on a surface. Fibers possess a fulcrum about which they pivot and step in a chiral manner; forces and torques associated with cell growth, when blocked by friction, result in self-propulsion. The elastic engine that drives macrofiber motions generates torques estimated as μdyncm and femtowatts of power; optical trapping studies yield a first direct measurement of the Young's modulus of the bacterial cell wall, the engine's “working fluid,” of ca. 0.05GPa.

关键词：芽孢杆菌枯草/细胞学芽孢杆菌枯草/遗传学芽孢杆菌枯草/生长和发育芽孢杆菌枯草/生理学细胞分裂弹性摩擦行走/生理学模型生物学转矩黏度

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Improved in vivo abdominal image quality using real-time estimation and correction of wavefront arrival time errors

Improved in vivo abdominal image quality using real-time est...

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IEEE Symposium (IUS) Ultrasonics

作者： K.W. Rigby C.L. Chalek B.H. Haider R.S. Lewandowski M. O'Donnell L.S. Smith D.G. Wildes GE Corporate Research and Development Center Schenectady NY USA Department of Biomedical Engineering and Applied Physics Program University of Michigan Ann Arbor MI USA

ISBN: (纸本)0780363655

The speed of sound varies with tissue type, yet commercial ultrasound imagers assume it is constant. Sound speed variation in abdominal fat and muscle layers is widely believed to be largely responsible for poor image contrast and resolution in some patients. The simplest model of the abdominal wall assumes that it adds a spatially varying time delay to the ultrasound wavefront. We describe an adaptive imaging system consisting of a GE LOGIQ 700 imager connected to a multi-processor computer. Arrival time errors for each beamforming channel, estimated by correlating each channel signal with the beamsum signal, are used to correct the imager's transmit and receive beamforming time delays at the image frame rate. A multi-row transducer provides two dimensional sampling of wavefront arrival time errors. After beamforming time delay correction, we observe significant improvement in abdominal images of healthy male volunteers, including increased contrast of blood vessels, increased brightness of liver tissue, and improved definition of the renal capsule and splenic boundary.

关键词： In vivo Abdomen Image quality Ultrasonic imaging Delay effects Array signal processing Computer errors Muscles Spatial resolution Image resolution

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On the Perception of Transients: Applying Psychophysical Constraints to Improve Audio Analysis and Synthesis 26

On the Perception of Transients: Applying Psychophysical Con...

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26th International Computer Music Conference, ICMC 2000

作者： Wakefield, Gregory H. Heller, Laurie M. Carney, Laurel H. Mellody, Maureen Department of Electrical Engineering and Computer Science University of Michigan Ann ArborMI48109 United States Naval Submarine Medical Research Laboratory GrotonCT06359 United States Hearing Research Center Dept. of Biomedical Engineering Boston University BostonMA02215 United States Applied Physics Program University of Michigan United States

In a psychophysical experiment, a wideband, 4-ms noise is compared with spectrally smoothed versions of the noise. To isolate on the magnitude spectrum, the phase spectrum is controlled by assigning the same random phase spectrum to both the original and smoothed signals. Depending on the choice of phase spectrum, discrimination thresholds for spectral shape vary from a maximum spectral deviation of 2-3 dB to as much as 25 dB. The exact source of this effect remains an open question. However, it suggests that not all transients require the same signal fidelity. Given a proper characterization of the perceptual response, it may be possible to reduce the size of the codebook required to maintain acceptable perceptual results. © 2000 ICMC. All Rights Reserved.

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A room temperature unipolar quantum dot intersubband long wavelength (13.3 /spl mu/m) laser

A room temperature unipolar quantum dot intersubband long wa...

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IEEE Photonics Conference (IPC)

作者： S. Krishna P. Bhattacharya J. Singh J. Urayama T.B. Norris P.J. McCann K. Namjou Applied Physics Program Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI USA School of Electrical and Computer Engineering University of Oklahama Norman OK USA

Summary form only given. We report the room temperature operation of a novel unipolar self-organized quantum dot FIR laser (13.3 /spl mu/m) based on transitions between discrete bound electron states in self-organized... 详细信息

关键词： Quantum dot lasers US Department of Transportation Electrons Infrared detectors Stationary state Finite impulse response filter Land surface temperature Infrared spectra Spectroscopy Laser radar

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An ESR spectroscopic analysis of proton and photon irradiated bone

An ESR spectroscopic analysis of proton and photon irradiate...

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

作者： Sang-Yeob Lee J.F. Copeland G.E. Chabot F.T. Greenaway Radiological Sciences Program Department of Physics and Applied Physics University of Massachusetts Lowell Lowell MA USA Radiological Physics Section Department of Radiology Beth Israel Deaconess Medical Center Harvard Institutes of Medicine Boston MA USA Department of Chemistry Clark University Worcester MA USA

ISBN: (纸本)0780364651

Electron spin resonance (ESR) spectroscopy was used to analyze the persistent free radicals in irradiated bone. Human cortical bone samples were irradiated in vitro by a 160-MeV proton beam and a 6-MV photon beam, and were subsequently analyzed with an x-band ESR spectrometer. The samples' spectroscopic g-values and microwave power saturation responses were studied, as well as various combinations of ESR signal peak-to-peak widths (PPW) and heights (PPH). The samples were also measured using the vector saturation transfer (VST) method, where first- and second-derivative ESR spectra collected at various modulation phases, and calculated third-derivative "harmonics," are compared. The samples' spectroscopic g-values and microwave power saturation responses were similar for both types of radiation. The g-values varied depending on bone dose and "background" signal, but became fairly regular around 50 Gy. The PPW were similar for both protons and photons, and varied with dose. The various groupings of PPH were all a linear function of dose. The ratio of net proton/photon PPH(dose) was 0.81, which differs from previous results. No significant differences were observed In the resultant VST harmonic figures, In conclusion, with the exception of the ratio of the net proton/photon PPH(dose), there were no significant differences in the spectroscopic character of the persistent free radicals in the proton- or photon-irradiated bone samples.

关键词： Paramagnetic resonance Spectroscopy Protons Bones Magnetic field measurement Amplitude modulation Frequency modulation Magnetic modulators Humans Microwave frequencies

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