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Improving resolution in microscopic holography by computationally fusing multiple, obliquely illuminated object waves in the Fourier domain

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APPLIED OPTICS 2007年第6期46卷 827-833页

作者： Price, Jeffery R. Bingham, Philip R. Thomas, C. E., Jr. Oak Ridge Natl Lab Image Sci & Machine Vis Grp Oak Ridge TN 37831 USA Third Dimens Technol LLC Knoxville TN 37920 USA

We present a computational method to increase the effective NA of a holographic microscopy system operating in air. Our optical system employs a reflection Mach-Zender architecture and computational reconstruction of the full complex (phase and amplitude) wavefront. Based on fundamental diffraction principles, different angles of incident illumination result in different diffracted orders of the object wave being imaged. We record, store, and computationally recombine these object waves to expand the spatial frequency response. Experimental results demonstrate an improvement in the effective NA of our system from 0.59 to 0.78.

关键词： computation methods Digital imaging Holographic interferometry Holographic microscopy Spatial frequency Spatial resolution

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Simplified laser-speckle-imaging analysis method and its application to retinal blood flow imaging

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OPTICS LETTERS 2007年第15期32卷 2188-2190页

作者： Cheng, Haiying Duong, Timothy Q. Emory Univ Yerkes Imaging Ctr Dept Neurol Atlanta GA 30329 USA

Laser speckle imaging (LSI) is widely used to study blood flow at high spatiotemporal resolution. Several papers recently pointed out that the commonly used LSI equation involves an approximation that could result in incorrect data analysis. We investigated the impact of such an approximation and introduced a simplified analysis method to improve computation time. Flow phantom studies were performed for validation. Moreover, we demonstrated a novel LSI application by imaging blood flow of rat retinas under normal and physiologic-challenge conditions. Because blood-flow abnormality is implicated in many retinal diseases, LSI could provide valuable physiologic, and potentially diagnostic, information. (C) 2007 Optical Society of America.

关键词： Analytical techniques computation methods Laser Doppler velocimetry Laser imaging Phantom studies Speckle patterns

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Channelized-ideal observer using Laguerre-Gauss channels in detection tasks involving non-Gaussian distributed lumpy backgrounds and a Gaussian signal

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JOURNAL OF THE OPTICAL SOCIETY OF AMERICA A-OPTICS IMAGE SCIENCE AND VISION 2007年第12期24卷 B136-B150页

作者： Park, Subok Barrett, Harrison H. Clarkson, Eric Kupinski, Matthew A. Myers, Kyle J. US FDA Natl Inst Biomed Imaging & Bioengn CDRH Lab Assessment Med Imaging SystDiv Imaging & App Silver Spring MD 20993 USA Univ Arizona Ctr Opt Sci Tucson AZ 85724 USA Univ Arizona Dept Radiol Tucson AZ 85724 USA

We investigate a channelized-ideal observer (CIO) with Laguerre-Gauss (LG) channels to approximate ideal-observer performance in detection tasks involving non-Gaussian distributed lumpy backgrounds and a Gaussian signal. A Markov-chain Monte Carlo approach is employed to determine the performance of both the ideal observer and the CIO using a large number of LG channels. Our results indicate that the CIO with LG channels can approximate ideal-observer performance within error bars, depending on the imaging system, object, and channel parameters. The CIO also outperforms a channelized-Hotelling observer using the same channels. In addition, an alternative approach for estimating the CIO is investigated. This approach makes use of the characteristic functions of channelized data and employs an approximation method to the area under the receiver operating characteristic curve. The alternative approach provides good estimates of the performance of the CIO with five LG channels. However, for large channel cases, more efficient computational methods need to be developed for the CIO to become useful in practice. (C) 2007 Optical Society of America.

关键词： computation methods Continuous variables Fast Fourier transforms Ideal observers Image quality Imaging systems

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A survey of population analysis methods and software for complex pharmacokinetic and pharmacodynamic models with examples

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AAPS JOURNAL 2007年第1期9卷 E60-E83页

作者： Bauer, Robert J. Guzy, Serge Ng, Chee XOMA US LLC Pharmacokinet Pharmacodynam & Bioinformat Berkeley CA 94710 USA Canc Therapy & Res Ctr S Texas Inst Drug Dev San Antonio TX 78229 USA

An overview is provided of the present population analysis methods and an assessment of which software packages are most appropriate for various PK/PD modeling problems. Four PK/PD example problems were solved using the programs NONMEM VI beta version, PDx-MCPEM, S-ADAPT, MONOLIX, and WinBUGS, informally assessed for reasonable accuracy and stability in analyzing these problems. Also, for each program we describe their general interface, ease of use, and abilities. We conclude with discussing which algorithms and software are most suitable for which types of PK/PD problems. NONMEM FO method is accurate and fast with 2-compartment models, if intra-individual and interindividual variances are small. The NONMEM FOCE method is slower than FO, but gives accurate population values regardless of size of intra- and interindividual errors. However, if data are very sparse, the NONMEM FOCE method can lead to inaccurate values, while the Laplace method can provide more accurate results. The exact EM methods (performed using S-ADAPT, PDx-MCPEM, and MONOLIX) have greater stability in analyzing complex PK/PD models, and can provide accurate results with sparse or rich data. MCPEM methods perform more slowly than NONMEM FOCE for simple models, but perform more quickly and stably than NONMEM FOCE for complex models. WinBUGS provides accurate assessments of the population parameters, standard errors and 95% confidence intervals for all examples. Like the MCPEM methods, WinBUGS's efficiency increases relative to NONMEM when solving the complex PK/PD models.

关键词： population pharmacokinetics pharmacodynamics clinical software computation methods

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Guest Editorial: 2007 Special Section on Modeling of Guided-Wave Photonic Devices

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Journal of Lightwave Technology 2007年第9期25卷 2284-2286页

关键词： computation methods Integrated optical devices Microwaves Nonlinear effects Photonic crystals Photonic devices

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Dynamic traffic grooming of subwavelength connections with known duration

Dynamic traffic grooming of subwavelength connections with k...

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Optical Fiber Communication - OFC 2007 Collocated National Fiber Optic Engineers Conference (OFC 2007), vol.3

作者： Massimo Tornatore Andrea Baruffaldi Hongyue Zhu Biswanath Mukherjee Achille Pattavina Department of Electronics and Information Politecnico di Milano Milan Italy Blade Network Technologies Santa Clara CA USA Department of Computer Science University of California Davis CA USA

For dynamic grooming of sub-wavelength connections in an optical mesh network, we investigate a new algorithm which exploits the holding time of connections to achieve significant reduction in blocking probability.

ISBN: (纸本)1557528306

关键词： computation methods Network topology Optical networks Ring networks Routing algorithms Wavelength division multiplexing Fiber optics and optical communications (060.0060) Networks (060.4250) Optical communications (060.4510)

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Backup Path Multiplexing over Survivable GMPLS Networks

Backup Path Multiplexing over Survivable GMPLS Networks

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Optical Fiber Communication - OFC 2007 Collocated National Fiber Optic Engineers Conference (OFC 2007), vol.3

作者： Yuanqiu Luo Si Yin Ting Wang Shinya Nakamura Nirwan Ansari NEC Laboratories America 4 Independence Way Princeton New Jersey 08540 USA NEC Corporation 1131 Hinode Abiko Chiba 270-1198 Japan Advanced Networking Lab. Electrical and Computer Engineering Dept. New Jersey Institute of Technology Newark New Jersey 07102 USA

ISBN: (纸本)1557528306

This paper proposes a backup path multiplexing scheme for survivable generalized multiprotocol label switching (GMPLS) networks. The shared risk link group (SRLG)-disjoint label switched paths (LSPs) share common backup resources as many as possible to achieve higher efficiency. Based on the problem formulation, the analysis on the expected recovery failure probability, the expected recovery time, and the expected signal loss reveals the upper bound of the backup path length. The simulation results demonstrate that the proposed scheme provides higher multiplexing gain.

关键词： computation methods Multiplexing Network survivability Network topology Wavelength division multiplexing Wavelength routing Fiber optics and optical communications (060.0060) Networks (060.4250) Optical communications (060.4510)

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Adaptive flat multiresolution multiplexed computational imaging architecture utilizing micromirror arrays to steer subimager fields of view

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APPLIED OPTICS 2006年第13期45卷 2884-2892页

作者： Christensen, MP Bhakta, V Rajan, D Mirani, T Douglas, SC Wood, SL Haney, MW So Methodist Univ Dept Elect Engn Dallas TX 75275 USA Santa Clara Univ Dept Elect Engn Santa Clara CA 95053 USA Univ Delaware Dept Comp Engn Newark DE 19716 USA

A thin, agile multiresolution, computational imaging sensor architecture, termed PANOPTES (processing arrays of Nyguist-limited observations to produce a thin electro-optic sensor), which utilizes arrays of microelectromechanical mirrors to adaptively redirect the fields of view of multiple low-resolution subimagers, is described. An information theory-based algorithm adapts the system and restores the image. The modulation transfer function (MTF) effects of utilizing micromirror arrays to steering imaging systems are analyzed, and computational methods for combining data collected from systems with differing MTFs are presented. (c) 2006 Optical Society of America.

关键词： computation methods computational imaging Image quality Image reconstruction Image sensors Imaging systems

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Global optimization and modeling techniques for planar multilayered dielectric structures

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APPLIED OPTICS 2006年第23期45卷 5910-5922页

作者： Oulton, R. F. Adjiman, C. S. Univ London Imperial Coll Sci Technol & Med Dept Chem Engn Ctr Proc Syst Engn London SW7 2BZ England

We present a multilevel global optimization strategy for synthesizing planar multilayered dielectric structures. A low discrepancy sequence of sample points with uniform variable space coverage allows a global-level search while systematic refinement using gradient-based techniques identifies optima at the local level. Since efficient local optimization is important for this method, a fast calculation approach based on mode matching is presented;this also facilitates the compact derivation of analytical gradients. The approach is compared with genetic and simulated annealing algorithms through an antireflection coating design. The method proves to be competitive in terms of its performance, nonadaptive algorithm, and ability to track local solutions. (C) 2006 Optical Society of America.

关键词： Antireflection coatings Bragg reflectors computation methods Genetic algorithms Optical design Semiconductor lasers

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Improving connection availability by means of backup sharing restrictions

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JOURNAL OF OPTICAL NETWORKING 2006年第5期5卷 383-397页

作者： Pándi, Z Gricser, A Budapest Univ Technol & Econ Dept Telecommun H-1117 Budapest Hungary

Online connection provisioning with availability guarantees has to meet the double challenge of assigning resources to connections sparingly and ensuring that connection availability remains above a certain threshold. After having selected an appropriate protection scheme, the first aim is achieved primarily by means of sharing backup resources, and the second aim calls for well conceived restrictions on backup resource sharing rules. We investigate the trade-offs that are behind the choice of protection schemes and sharing rule restrictions with respect to blocking probability and connection availability. Results of simulations carried out in European and Italian network topologies are used to draw conclusions. Sensitivity analysis of availability parameters is also carried out. (C) 2006 Optical Society of America.

关键词： computation methods Network topology Optical networks Plasma displays Wavelength conversion Wavelength division multiplexing

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