This paper presents our study of time-resolved propagation of polarized light in scattering media. Monte Carlo simulated time-resolved Stokes vectors of transmitted light were compared with the experimental results. A...
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Two approaches were used to gain an understanding of the spatial variations in membrane potential resulting from exposure of cultured adrenal medullary chromaffin cells to a 20 V/cm DC electric field of different orie...
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Two approaches were used to gain an understanding of the spatial variations in membrane potential resulting from exposure of cultured adrenal medullary chromaffin cells to a 20 V/cm DC electric field of different orientations. The finite element method was used to solve Poisson's equation for the potential in a Petri dish containing isolated spherical chromaffin cells or chromaffin cell aggregates of various configurations and the results of the computations were compared to the results obtained experimentally. The latter used fluorescence imaging of chromaffin cell membranes stained with the fluorescent voltage-sensitive dye di-8-ANEPPS to monitor variations in membrane potential. For single cells, the numerical results for membrane potential variation were in good agreement with the experimental results. For realistic chains of two or three cells, the results from both methods were in agreement only when the long axis of the chain was perpendicular to the electric field. For three cells forming a realistic, irregularly shaped aggregate, variations in membrane potential determined experimentally were more complex than those predicted by the numerical computations for regions of cell contact. The results provide a foundation for understanding how excitable cells respond to DC electric fields and identify parameters that influence these responses.
Polarization-gated imaging techniques based on time-resolved Stokes vectors for filament tissues were discussed. The time-resolved Stokes vectors of signals transmitting chicken breast tissue, mouse cardiac muscle tis...
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ISBN:
(纸本)1557527067
Polarization-gated imaging techniques based on time-resolved Stokes vectors for filament tissues were discussed. The time-resolved Stokes vectors of signals transmitting chicken breast tissue, mouse cardiac muscle tissue, and polystyrene micro-sphere solution were compared. Results showed that with 45 degrees linear polarization and circular polarization output monitoring, better quality images will be obtained.
Multiple configurations of planar, conformally-mapped multielectrode arrays (cMEAs) are used to enable stimulation and recording of hippocampal acute slice activities. The configurations of the multielectrode arrays a...
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Multiple configurations of planar, conformally-mapped multielectrode arrays (cMEAs) are used to enable stimulation and recording of hippocampal acute slice activities. The configurations of the multielectrode arrays are conformal in that the designs incorporate the specific geometrical mapping of various sub-regions of the rat hippocampus (CA1-to-CA3, dentate gyrus-to-CA3, or individual regions). The high-density feature of the arrays also provides a high spatial resolution for current-source density (CSD) analysis, with 50 /spl mu/m or 60 /spl mu/m center-to-center distances. Fabrication of gold and ITO (indium tin oxide) based multielectrode arrays with up to sixty-four recording/stimulating elements has been achieved. Impedance measurements are taken for the multielectrode arrays, and a simple equivalent circuit has been employed to model the electrode-electrolyte interface; cyclic voltammetry and potential monitoring experiments are performed to set guidelines and to identify limitations of stimulation protocols, thus avoiding undesirable irreversible faradaic reactions due to excess stimulation. Evoked in-vitro electrophysiological experiments with acute slices of rat hippocampus have successfully been performed using the cMEAs.
A novel photolithography process was utilized to precisely align and pattern environmentally sensitive hydrogels onto silicon microcantilevers, after microcantilevers were fabricated and released. By patterning enviro...
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A novel photolithography process was utilized to precisely align and pattern environmentally sensitive hydrogels onto silicon microcantilevers, after microcantilevers were fabricated and released. By patterning environmentally sensitive hydrogels onto silicon microcantilevers, an ultrasensitive pH microsensor was prepared for MEMS and bioMEMS applications. Specifically, a crosslinked poly(methacrylic acid) network containing significant amounts of poly(ethylene glycol) dimethacrylate was studied. This hydrogel exhibits a swelling dependence on pH. Hydrogels were patterned onto the silicon microcantilevers utilizing a mask aligner to allow for precise positioning. Via modification of the silicon surface with /spl gamma/-methacryloxypropyl trimethoxysilane, covalent adhesion was gained between the polymer and the silicon surface. The micropatterned hydrogels were analyzed using optical microscopy and profilometry. The bending response of patterned cantilevers with a change in environmental pH was observed, providing proof-of-concept for a MEMS/bioMEMS sensor based on microcantilevers patterned with environmentally sensitive hydrogels.
作者：
Vieira, Luis CarlosPrograma de Pós-Graduação em Engenharia Elétrica e Informática Industrial
Departamento de Eletrônica e Telecomunicações (Graduate Program in Electrical Engineering and Industrial Computer Science Department of Electronics and Telecommunications) Centro Federal de Educação Tecnológica do Paraná (Federal Center of Technological Education of Paraná) Curitiba Brazil
This paper addresses the problem of robust /spl Hscr//sub /spl infin// filtering for linear discrete-time systems subject to parameter uncertainties in the system state-space model and with multiple time delays in the...
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This paper addresses the problem of robust /spl Hscr//sub /spl infin// filtering for linear discrete-time systems subject to parameter uncertainties in the system state-space model and with multiple time delays in the state variables. The uncertain parameters are supposed to belong to a given convex bounded polyhedral domain. A methodology is developed to design a stable linear filter that assures asymptotic stability and a prescribed /spl Hscr//sub /spl infin// performance for the filtering error, irrespective of the uncertainty and the time delays. The proposed design is given in terms of linear matrix inequalities, which has the advantage in that it can be implemented numerically very efficiently.
We report an observation of essentially full spatial coherence in a high average power soft-x-ray laser. Rapid coherence buildup due to strong refractive antiguiding in a long plasma column is experimentally demonstra...
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We report an observation of essentially full spatial coherence in a high average power soft-x-ray laser. Rapid coherence buildup due to strong refractive antiguiding in a long plasma column is experimentally demonstrated. This allows the generation of fully coherent, milliwatt-level average power soft-x-ray radiation by a tabletop device. The peak brightness of this laser reaches 2×1025photonss−1mm−2mrad−2 within 0.01% spectral bandwidth, making it one of the brightest soft-x-ray sources available.
The problem of robust H/spl infin/ filtering for continuous-time uncertain linear systems with multiple time-varying delays in the state variables is investigated. The uncertain parameters are supposed to belong to a ...
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The problem of robust H/spl infin/ filtering for continuous-time uncertain linear systems with multiple time-varying delays in the state variables is investigated. The uncertain parameters are supposed to belong to a given convex bounded polyhedral domain. The aim is to design a stable linear filter assuring asymptotic stability and a prescribed H/spl infin/ performance level for the filtering error system, irrespective of the uncertainties and the time delays. Sufficient conditions for the existence of such a filter are established in terms of linear matrix inequalities, which can be efficiently solved by means of powerful convex programming tools with global convergence assured. An example illustrates the proposed methodology.
The problem of robust H∞ state-feedback control design for a class of continuous-time linear systems with Markovian jumping parameters and multiple time-varying delays at the states, and subject to uncertain paramete...
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