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 reflectome...
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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.
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...
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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 transv...
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.
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 twis...
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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.
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 d...
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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.
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 walki...
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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.
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...
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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.
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 ph...
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...
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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 dots. A typical photoluminescence spectrum of InGaAs-GaAs self-organized quantum dots is shown.
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...
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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.
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