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Geometrically unrestricted, topologically constrained control of liquid crystal defects using simultaneous holonomic magnetic and holographic optical manipulation

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Physical Review E 2014年第2期89卷 022505-022505页

作者： Michael C. M. Varney Nathan J. Jenness Ivan I. Smalyukh Department of Physics University of Colorado at Boulder Boulder Colorado 80309 USA Department of Mechanical Engineering University of Rochester Rochester New York 14627 USA Department of Electrical Computer and Energy Engineering Materials Science and Engineering Program Liquid Crystals Materials Research Center University of Colorado at Boulder Boulder Colorado 80309 USA Renewable and Sustainable Energy Institute National Renewable Energy Laboratory and University of Colorado at Boulder Boulder Colorado 80309 USA

Despite the recent progress in physical control and manipulation of various condensed matter, atomic, and particle systems, including individual atoms and photons, our ability to control topological defects remains limited. Recently, controlled generation, spatial translation, and stretching of topological point and line defects have been achieved using laser tweezers and liquid crystals as model defect-hosting systems. However, many modes of manipulation remain hindered by limitations inherent to optical trapping. To overcome some of these limitations, we integrate holographic optical tweezers with a magnetic manipulation system, which enables fully holonomic manipulation of defects by means of optically and magnetically controllable colloids used as “handles” to transfer forces and torques to various liquid crystal defects. These colloidal handles are magnetically rotated around determined axes and are optically translated along three-dimensional pathways while mechanically attached to defects, which, combined with inducing spatially localized nematic-isotropic phase transitions, allow for geometrically unrestricted control of defects, including previously unrealized modes of noncontact manipulation, such as the twisting of disclination clusters. These manipulation capabilities may allow for probing topological constraints and the nature of defects in unprecedented ways, providing the foundation for a tabletop laboratory to expand our understanding of the role defects play in fields ranging from subatomic particle physics to early-universe cosmology.

关键词： LIQUID crystals TOPOLOGY CRYSTAL defects HOLONOMIC constraints MAGNETIC materials HOLOGRAPHY CONDENSED matter

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Semantic Interpretation of Robust Imaging Features for Fuhrman Grading of Renal Carcinoma

Semantic Interpretation of Robust Imaging Features for Fuhrm...

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

作者： Andrew Champion Guolan Lu Marcus Walker Sonal Kothari Adeboye O. Osunkoya May D. Wang School of Computational Science and Engineering Georgia Institute of Technology Department of Biomedical Engineering Georgia Institute of Technology and Emory University School of Electrical and Computer Engineering Georgia Institute of Technology Department of Pathology Emory University School of Medicine Department of Biomedical Engineering Winship Cancer Institute Parker H. Petit Institute of Bioengineering and Biosciences Institute of People and Technology Georgia Institute of Technology and Emory University

ISBN: (纸本)9781424479276

Pattern recognition in tissue biopsy images can assist in clinical diagnosis and identify relevant image characteristics linked with various biological characteristics. Although previous work suggests several informative imaging features for pattern recognition, there exists a semantic gap between characteristics of these features and pathologists' interpretation of histopathological images. To address this challenge, we develop a clinical decision support system for automated Fuhrman grading of renal carcinoma biopsy images. We extract 1316 color, shape, texture and topology features and develop one vs. all models for four Fuhrman grades. Our models are highly accurate with 90.4% accuracy in a four-class prediction. Predictivity analysis suggests good generalization of the model development methodology through robustness to dataset sampling in cross-validation. We provide a semantic interpretation for the imaging features used in these models by linking features to pathologists' grading criteria. Our study identifies novel imaging features that are semantically linked to Fuhrman grading criteria.

关键词： Feature extraction Image color analysis Shape Predictive models Accuracy Cancer Imaging

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Nanostructure investigations of nonlinear differential conductance in NdNiO3 thin films

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Physical Review B 2014年第20期90卷 205117-205117页

作者： Will J. Hardy Heng Ji Evgeny Mikheev Susanne Stemmer Douglas Natelson Applied Physics Program Rice Quantum Institute Rice University Houston Texas 77005 USA Department of Physics and Astronomy Rice University Houston Texas 77005 USA Materials Department University of California Santa Barbara California USA Department of Electrical and Computer Engineering and Department of Materials Science and Nanoengineering Rice University Houston Texas 77005 USA

Transport measurements on thin films of NdNiO3 reveal a crossover to a regime of pronounced nonlinear conduction below the well-known metal-insulator transition temperature. The evolution of the transport properties at temperatures well below this transition appears consistent with a gradual formation of a gap in the holelike Fermi surface of this strongly correlated system. As T is decreased below the nominal transition temperature, transport becomes increasingly non-Ohmic, with a model of Landau-Zener breakdown becoming most suited for describing I(V) characteristics as the temperature approaches 2 K.

关键词： ELLIPSOMETRY THIN films NANOSTRUCTURED materials SOLID state electronics MAGNETRON sputtering

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Modeling low energy x-ray interactions with biological material at the CUEBIT

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Journal of Physics: Conference Series 2015年第1期583卷

作者： J Klingenberger M Schott T Kimmel D Medlin A Gall M Rusin D Dean E Takacs School of Computing Clemson University 100 McAdams Hall Clemson SC 29634 USA Department of Electrical Engineering and Computer Science Vanderbilt University 400 24th Ave S Jacobs Hall Nashville TN 37212 USA Department of Physics and Astronomy Clemson University 118 Kinard Laboratory Clemson SC 29634 USA Department of Bioengineering Clemson University 301 Rhodes Research Center Clemson SC 29634 USA

Recent developments at Clemson University have established the need to model the production of x-rays using a highly charged ion beam generated by the Clemson University Electron Beam Ion Trap (CUEBIT). A Geant4 modeling environment has been developed on Clemson University's Palmetto2 supercomputing cluster to simulate the interaction of these x- rays with biological material. Preliminary results of the model have been obtained after performing initial simulations on the computing cluster. Future experiments using the CUEBIT as well as refinements to the Geant4 model are discussed.

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Causal analysis of cortical networks involved in reaching to spatial targets

Causal analysis of cortical networks involved in reaching to...

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

作者： John R. Iversen Alejandro Ojeda Tim Mullen Markus Plank Joseph Snider Gert Cauwenberghs Howard Poizner Institute of Neural Computation and Swartz Center for Computational Neuroscience UC San Diego Department of Electrical and Computer Engineering UC San Diego Department of Cognitive Science and Institute of Neural Computation UC San Diego Brain Products Inc. Institute of Neural Computation UC San Diego Department of Bioengineering Jacobs School of Engineering and Institute of Neural Computation UC San Diego

ISBN: (纸本)9781424479276

The planning of goal-directed movement towards targets in different parts of space is an important function of the brain. Such visuo-motor planning and execution is known to involve multiple brain regions, including visual, parietal, and frontal cortices. To understand how these brain regions work together to both plan and execute goal-directed movement, it is essential to describe the dynamic causal interactions among them. Here we model causal interactions of distributed cortical source activity derived from non-invasively recorded EEG, using a combination of ICA, minimum-norm distributed source localization (cLORETA), and dynamical modeling within the Source Information Flow Toolbox (SIFT). We differentiate network causal connectivity of reach planning and execution, by comparing the causal network in a speeded reaching task with that for a control task not requiring goal-directed movement. Analysis of a pilot dataset (n=5) shows the utility of this technique and reveals increased connectivity between visual, motor and frontal brain regions during reach planning, together with decreased cross-hemisphere visual coupling during planning and execution, possibly related to task demands.

关键词： Planning Electroencephalography Brain modeling Visualization Biological system modeling Neuroscience Independent component analysis

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Optics and photonics of Taiwan international conference: Introduction by the feature editors

Optics and photonics of Taiwan international conference: Int...

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作者： Fuh, Andy Y.-G. Khoo, Iam Choon Lin, Tsung-Hsien Huang, Yi-Pai Chien, Liang-Chy Chigrinov, Vladimir G. Yang, Tsung-Hsun Department of Physics Advanced Optoelectronic Technology Center National Cheng Kung University Tainan701 Taiwan Department of Electrical Engineering Pennsylvania State University University ParkPA16802 United States Department of Photonics National Sun Yat-Sen University Kaohsiung804 Taiwan Department of Photonics and Display Institute National Chiao Tung University Hsin-Chu300 Taiwan Chemical Physics Interdisciplinary Program Liquid Crystal Institute Kent State University KentOH44242 United States Department of Electronic and Computer Engineering Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong Department of Optics and Photonics National Central University Chung-Li City320 Taiwan

This Applied Optics feature issue is dedicated to the Optics and Photonics of Taiwan International Conference (OPTIC 2013), held 5-7 December 2013 in Zhongli (Chung-Li), Taiwan. The conference takes place every year at different universities in Taiwan. This feature issue is particularly focused on a broad range of topics covered under subconference VII (Display Technology), and also includes topics pertaining to display technology under other subconferences. In addition, the feature issue is open to all other researchers in the related area. © 2014 Optical Society of America.

关键词： Photonics

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Role of bias conditions in the hot carrier degradation of AlGaN/GaN high electron mobility transistors

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Physica Status Solidi (C) Current Topics in Solid State Physics 2013年第5期10卷 794-798页

作者： Mukherjee, Shubhajit Puzyrev, Yevgeny Hinckley, John Schrimpf, Ronald D. Fleetwood, Daniel M. Singh, Jasprit Pantelides, Sokrates T. Interdisciplinary Program in Materials Science Vanderbilt University Nashville TN 37212 United States Department of Physics and Astronomy Vanderbilt University Nashville TN 37212 United States Department of Electrical Engineering and Computer Science University of Michigan Ann Arbor MI 48109 United States Department of Electrical Engineering and Computer Science Vanderbilt University Nashville TN 37212 United States

The impacts of gate bias and device temperature on carrier energy distributions are reported for AlGaN/GaN High Electron Mobility Transistors. The lateral electric field and the average carrier energy are the highest at the end of gate on the gate-drain access side. The number of high energy carriers is the greatest in the semi-ON operating condition, with maximum energies exceeding the activation energy of defects in the AlGaN. There is a significant decrease in the number of very high energy carriers (greater than 2 eV) as the device temperature increases whereas the number of moderately energetic carriers (between 1 to 2 eV) is higher at elevated temperatures. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

关键词： High electron mobility transistors

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Introduction to the issue on biophotonics

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IEEE Journal on Selected Topics in Quantum Electronics 2014年第2期20卷 4-7页

作者： Ilev, Ilko K. Boppart, Stephen A. Andersson-Engels, Stefan Kim, Beop-Min Perelman, Lev Tuchin, Valery Center for Devices and Radiological Health U.S. Food and Drug Administration Silver Spring MD 20993 United States Beckman Institute for Advanced Science and Technology Departments of Bioengineering Electrical and Computer Engineering and Medicine University of Illinois Urbana IL 61801 United States Division of Atomic Physics Lund University Lund SE-22100 Sweden Department of Biomedical Engineering Korea University Seoul 136-703 Korea Republic of Center for Advanced Biomedical Imaging and Photonics Beth Israel Deaconess Medical Center Harvard University Boston MA 02215 United States Division of Optics and Biophotonics Saratov State University Saratov 410012 Russia Institute of Precision Mechanics and Control Russian Academy of Sciences Saratov 410028 Russia Optoelectronics and Measurement Techniques Laboratory University of Oulu Oulu FI-90014 Finland

The objective of this JSTQE Issue on Biophotonics is to highlight recent progress and trends in innovative biophotonics technology development. The papers published in this issue cover a broad range of advanced biophotonics areas summarized in the following sections: 1) bioimaging: optical coherence tomography and microscopy, nonlinear optical imaging, and novel multimodality imaging approaches; 2) biosensing: multifunctional biosensing, and novel biosensing approaches; 3) biophotonic science: mechanisms of light-cell and lighttissue interactions, advanced modeling methods in biophotonics, and light induced biophotonics effects; 4) biophotonic technology: advanced technologies in biophotonic diagnostics and therapeutics, infrared technology in biophotonics, and novel laser, biomedical and fiber optics tools and devices in biophotonics. These key research topics are highlighted as comprehensive overviews of the current status and future trends, as well as original results and recent developments in the field of biophotonics. This issue contains 33 papers, including 18 invited and 15 contributed papers authored by well-established research groups and promising scientists from all over the world. The invited papers include extended reviews on recent biophotonic developments and clinical applications in the areas of highresolution multispectral bioimaging, combined multifunctional microscopy, nonlinear deep tissue imaging, single molecule imaging, optical coherence elastography, cellular and molecular mechanisms of photobiomodulation, tissue optical clearing, clinical ultrafast laser surgery, infrared laser nerve stimulation, and novel tapered diode lasers for biophotonics. The contributed papers cover a broad variety of key biophotonic research areas including recently obtained original results on multimodal bioimaging and sensing, high resolution phase-sensitive magnetomotive optical coherence microscopy and elastography, and laser-assisted typing of polymorphic human

关键词： Special issues and sections Biophotonics

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Effects of Mechanical Properties on Tumor Invasion: Insights from a Cellular Model

Effects of Mechanical Properties on Tumor Invasion: Insights...

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

作者： Yingzi Li Hammad Naveed Jie Liang Lisa X. Xu School of Biomedical Engineering and Med-X Research Institute Shanghai Jiao Tong University Shanghai China Department of Bioengineering University of Illinois at Chicago Chicago IL USA Computer Electrical and Mathematical Sciences and Engineering Division King Abdullah University of Science and Technology Thuwal Saudi Arabia Shanghai Center for Systems Biomedicine Shanghai Jiao Tong Univerisity Shanghai China

Understanding the regulating mechanism of tumor invasion is of crucial importance for both fundamental cancer research and clinical applications. Previous in vivo experiments have shown that invasive cancer cells dissociate from the primary tumor and invade into the stroma, forming an irregular invasive morphology. Although cell movements involved in tumor invasion are ultimately driven by mechanical forces of cell-cell interactions and tumor-host interactions, how these mechanical properties affect tumor invasion is still poorly understood. In this study, we use a recently developed two-dimensional cellular model to study the effects of mechanical properties on tumor invasion. We study the effects of cell-cell adhesions as well as the degree of degradation and stiffness of extracellular matrix (ECM). Our simulation results show that cell-cell adhesion relationship must be satisfied for tumor invasion. Increased adhesion to ECM and decreased adhesion among tumor cells result in invasive tumor behaviors. When this invasive behavior occurs, ECM plays an important role for both tumor morphology and the shape of invasive cancer cells. Increased stiffness and stronger degree of degradation of ECM promote tumor invasion, generating more aggressive tumor invasive morphologies. It can also generate irregular shape of invasive cancer cells, protruding towards ECM. The capability of our model suggests it a useful tool to study tumor invasion and might be used to propose optimal treatment in clinical applications.

关键词： Tumors Electronic countermeasures Cancer Adhesives Indexes Shape Morphology

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Two-dimensional skyrmions and other solitonic structures in confinement-frustrated chiral nematics

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Physical Review E 2014年第1期90卷 012505-012505页

作者： Paul J. Ackerman Rahul P. Trivedi Bohdan Senyuk Jao van de Lagemaat Ivan I. Smalyukh Department of Physics University of Colorado Boulder Colorado 80309 USA Department of Electrical Computer and Energy Engineering University of Colorado Boulder Colorado 80309 USA National Renewable Energy Laboratory Golden Colorado 80401 USA Renewable and Sustainable Energy Institute National Renewable Energy Laboratory and University of Colorado Boulder Colorado 80309 USA Liquid Crystal Materials Research Center and Materials Science and Engineering Program University of Colorado Boulder Colorado 80309 USA

We explore spatially localized solitonic configurations of a director field, generated using optical realignment and laser-induced heating, in frustrated chiral nematic liquid crystals confined between substrates with perpendicular surface anchoring. We demonstrate that, in addition to recently studied torons and Hopf-fibration solitonic structures (hopfions), one can generate a host of other axially symmetric stable and metastable director field configurations where local twist is matched to the surface boundary conditions through introduction of point defects and loops of singular and nonsingular disclinations. The experimentally demonstrated structures include the so-called “baby-skyrmions” in the form of double twist cylinders oriented perpendicular to the confining substrates where their double twist field configuration is matched to the perpendicular boundary conditions by loops of twist disclinations. We also generate complex textures with arbitrarily large skyrmion numbers. A simple back-of-the-envelope theoretical analysis based on free energy considerations and the nonpolar nature of chiral nematics provides insights into the long-term stability and diversity of these inter-related solitonic field configurations, including different types of torons, cholestric-finger loops, two-dimensional skyrmions, and more complex structures comprised of torons, hopfions, and various disclination loops that are experimentally observed in a confinement-frustrated chiral nematic system.

关键词： SKYRMIONS SOLITONS PARTICLES (Nuclear physics) -- Chirality BOUNDARY value problems SURFACE texture

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