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Optical generation, templating, and polymerization of three-dimensional arrays of liquid-crystal defects decorated by plasmonic nanoparticles

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Physical Review E 2013年第3期87卷 032503-032503页

作者： Julian S. Evans Paul J. Ackerman Dirk J. Broer Jao van de Lagemaat Ivan I. Smalyukh Department of Physics and Materials Science and Engineering Program University of Colorado at Boulder Boulder Colorado 80309 USA Department of Electrical Computer and Energy Engineering and Liquid Crystals Materials Research Center University of Colorado at Boulder Boulder Colorado 80309 USA National Renewable Energy Laboratory Golden Colorado 80401 USA Functional Organic Materials and Devices Eindhoven University of Technology Box 513 5600 MB Eindhoven The Netherlands Renewable and Sustainable Energy Institute National Renewable Energy Laboratory and University of Colorado at Boulder Boulder Colorado 80309 USA

Defects in liquid crystals are used to model topological entities ranging from Skyrmions in high-energy physics to early-universe cosmic strings, as well as find practical applications in self-assembly of diffraction gratings and in scaffolding of plasmonic nanoparticles, but they are hard to control and organize into three-dimensional lattices. We laterally scan focused laser beams to produce periodic arrays of twist-stabilized defects forming either linear (fingers) or axially symmetric (torons) configurations in partially polymerizable liquid crystal films. Polymerization allows for stabilization of these structures and the formation of three-dimensional arrays of defects by stacking of the thin cholesteric films on top of each other. In the process of fabrication of such arrays, we polymerize the liquid crystal film with an array of torons or fingers and then sequentially produce and photopolymerize new liquid crystal layers on top of it, thus obtaining a three-dimensional structure of twist-stabilized defects in a layer-by-layer fashion. Templating by the polymerized layer spontaneously yields ordered organization of fingers and torons in the new cholesteric layer, thus enabling a three-dimensional ordered structure of defects. Nondestructive three-dimensional imaging of director fields by use of three-photon excitation fluorescence polarizing microscopy reveals the nature of topological singularities and physical underpinnings behind the observed templating effect. Three-dimensional patterning of defects templates the self-assembly of plasmonic nanoparticles into individual singularities and their arrays, laying the groundwork for potential applications in nanophotonics, plasmonics, metamaterial fabrication, and nanoscale energy conversion.

关键词： LIQUID crystals CRYSTAL defects POLYMERIZATION DIMENSIONAL analysis PLASMONS (Physics) NANOPARTICLES

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Multi-server MMO middleware: Unlocked

Multi-server MMO middleware: Unlocked

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2012 7th International Conference on P2P, Parallel, Grid, Cloud and Internet Computing, 3PGCIC 2012

作者： McKnight, Christopher Stubens, Carl Coady, Yvonne Li, Kin Fun Software Engineering Program University of Victoria Victoria BC Canada Department of Computer Science University of Victoria Victoria BC Canada Department of Electrical and Computer Engineering University of Victoria Victoria BC Canada

ISBN: (纸本)9781467329910

Massively multiplayer online (MMO) games consist of huge worlds populated by thousands of clients, far beyond the ability of a single server to maintain. This naturally leads to the division of the game world into many partitions, each controlled by a single server. To provide players with the illusion of a single large world, some MMO systems divide their game world across servers and synchronize all nearby activity between them. To accomplish and synchronize player movement and interaction between servers, a system of inter-server locks are employed. These locks introduce considerable software complexity and network traffic overhead. We discuss the practical problems of such locking systems, and present an alternate approach. A lockless middleware design is described which implements sequential consistency using inter-server remote writes. This approach provides consistency across all clients and servers, allowing for seamless movement of clients within an arbitrarily large game world. We compare the lockless architecture to the traditional locking design, and analyze its performance. © 2012 IEEE.

关键词： Middleware

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Label-free multimodal nonlinear optical microscopy for in vivo diagnosis of precancerous squamous epithelia

Label-free multimodal nonlinear optical microscopy for in vi...

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Biomedical Optics, BIOMED 2012

作者： Teh, Seng Khoon Zheng, Wei Li, Shuxia Li, Dong Zeng, Yan Yang, Yanqi Qu, Jianan Y. Biomedical Engineering Program Division of Bioengineering HKG China Biomedical Engineering Program Department of Electronic and Computer Engineering Hong Kong University of Science and Technology Hong Kong Hong Kong Faculty of Dentistry University of Hong Kong Hong Kong

We explore in vivo diagnostic utility of an in-house developed multimodal nonlinear optical microscopy for detection of squamous epithelia precancer. Our results reveal all epithelial sublayers and stroma provide sign... 详细信息

ISBN: (纸本)9781557529428

关键词： Nonlinear optics

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Smart environmental architecture for node localization in a wireless sensor network

Smart environmental architecture for node localization in a ...

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8th International Conference on Intelligent Environments, IE 2012

作者： Jauregui-Ortiz, Salvador Siller, Mario Ramos, Felix Scalabrin, Edson Electrical Engineering and Computer Science Department Center of Research and Advanced Studies Guadalajara Jalisco Mexico Graduate Program in Computer Science Pontifical Catholic University Parana Brazil Curitiba Parana Brazil

ISBN: (纸本)9780769547411

As far as we know, there is not a Node Localization Algorithm (NLA) that presents the same accuracy for all possible scenarios. We believe that a NLA should be able to interpret the dynamic information of the environment. In this sense, simple NLAs are rather focused and might perform well for specific scenarios and applications. Therefore, information fusion and context awareness seems to be an appropriate approach to address this issue. We propose the Smart Environmental Architecture for Node Localization (SEA-NL), which is composed by two main elements: (i) the Smart Beacon Nodes (SBNs) and (ii) the Logical Position of Nodes (LPN). In (i) the obstruction level indicator is estimated and can improve the estimation of distances among nodes. In (ii) environment information and a one to one relation between a node and an object are used and can also improve location estimation. Via simulation, our architecture was tested indoors and outdoors considering three localization algorithms: the Weighed Centroid Localization (WCL), the Centroid Localization, and the Triangular Centroid Localization. Finally, we present an accuracy comparison among NLAs used in isolated way, and by using the SBNs, the LPN, and the SEA-NL, where our architecture improves WCL up to ~30.88%. © 2012 IEEE.

关键词： Information fusion

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Femtosecond plasmonic optical tweezers using gold bowtie nanoantenna arrays

Femtosecond plasmonic optical tweezers using gold bowtie nan...

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Frontiers in Optics, FIO 2012

作者： Roxworthy, Brian J. Toussaint, Kimani C. Department of Electrical and Computer Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 United States Department of Mechanical Science and Engineering University of Illinois at Urbana-Champaign Urbana IL 61801 United States Affiliate in the Department of Electrical and Computer Engineering and Bioengineering University of Illinois at Urbana-Champaign Urbana IL 61801 United States

We demonstrate plasmonic optical trapping based on a femtosecond-pulsed input source and gold bowtie nanoantenna arrays. The femtosecond plasmonic tweezers allow for simultaneous manipulation and two-photon fluorescen... 详细信息

ISBN: (纸本)9781557529565

关键词： Plasmonics

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Ethics education & resources: A summary of issues facing the field and resources to address them

Ethics education & resources: A summary of issues facing the...

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119th ASEE Annual Conference and Exposition

作者： Bates, Rebecca A. Broome Jr., Taft H. Burge Jr., Legand L. Hollander, Rachelle Loui, Michael C. Computer Science Department Integrated Engineering Program Minnesota State University Mankato United States Department of Civil Engineering Howard University United States College of Engineering Department of Electrical Engineering Tuskegee University United States United States Department of Electrical and Computer Engineering University of Illinois Urbana-Champaign United States

ISBN: (纸本)9780878232413

The issues addressed in this paper and in the panel discussion are important for improving how the profession of engineering addresses ethical questions that arise in our field. We are called to provide our students with skills that will let them navigate not only the technical problems they will encounter but also the societal and ethical problems and nuances that often accompany the grand challenges as well as the everyday challenges engineers face. Participating in the online spaces and face-to-face conversations when possible will help form the resources into areas that are truly useful for practitioners. © 2012 American Society for engineering Education.

关键词： Students

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Hybrid clutter canceler with feedback guided predicative filtering on a heterogeneous parallel processing system

Hybrid clutter canceler with feedback guided predicative fil...

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International Waveform Diversity and Design Conference, WDD 2012

作者： Brinkhus, Jeffrey M. Jezak, Joseph A. Berdanier, Charles Levitan, Steven P. Chiarulli, Donald M. Electical and Computer Engineering University of Pittsburgh United States Computer Engineering Graduate Program University of Pittsburgh United States Electrical Engineering Wright State University United States Computer Science Department University of Pittsburgh United States

ISBN: (纸本)9781509005987

In this paper we describe a novel clutter cancellation platform based on a two stage approach that combines a feedback guided predictive front-end hybrid clutter canceller with high performance back-end filtering and target detection. The front-end architecture is based on an FPGA implementation of a Kalman filter that predicts target locations in real time and removes the target signals from the incoming data prior to hybrid cancellation. The back-end is user configurable and exploits high performance GPU and multi-core parallel hardware to simultaneously compute multiple clutter suppression and target detection algorithms coupled to an intelligent selection strategy for selecting the most accurate result. These target locations are fed back to the FPGA Kalman filter periodically to update the target predictions. © 2012 IEEE.

关键词： Kalman filters

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Accelerated DSP functions on the CBE for the X-Midas Toolkit

Accelerated DSP functions on the CBE for the X-Midas Toolkit

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International Waveform Diversity and Design Conference, WDD 2012

作者： Jezak, Joseph A. Berdanier, Charles Levitan, Steven P. Chiarulli, Donald M. Computer Engineering Graduate Program University of Pittsburgh United States USAF AFRL/RYMDA Wright Patterson Air Force Base United States Department of Electrical and Computer Engineering University of Pittsburgh United States Department of Computer Science University of Pittsburgh United States

ISBN: (纸本)9781509005987

We characterize the impact of the Cell Broadband Engine architecture, on commonly used radar DSP algorithms. We use the capabilities of the CBE to accelerate several key computational kernels including Matrix Multiplication, Matrix Inversion, and the Finite Impulse Response (FIR) filter. These algorithms are implemented and benchmarked as library routines within the X-Midas Toolkit. We observe speedups as large as 1200x for complex matrix multiplication, but speedups of 40x to 60x are more typical. We find that system I/O overhead within the X-Midas toolkit severely limited the performance of the applications. © 2012 IEEE.

关键词： FIR filters

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Shear wave elastography for characterizing muscle tissue in myofascial pain syndrome

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Proceedings of Meetings on Acoustics 2013年第1期19卷

作者： Diego Turo Paul Otto Tadesse Gebreab Katherine Armstrong Lynn H. Gerber Siddhartha Sikdar Department of Bioengineering George Mason University Fairfax VA 22030 Department of Electrical and Computer Engineering George Mason University Fairfax VA 22030 Department of Rehabilitation Science George Mason University Fairfax VA 22030 Department of Bioengineering George Mason University Fairfax VA

Myofascial pain syndrome (MPS) affects 85% of chronic pain sufferers in a specialty pain center. Neck and low-back are commonly affected by MPS. Myofascial trigger points (MTrPs) are characteristic findings of MPS and are palpable tender nodules in the muscles of symptomatic subjects. Mechanical characterization of MTrPs and surrounding tissue can offer important insight about the pathophysiology of the MPS. In this study, we propose an inexpensive technique, based on ultrasound shear wave elastography, to objectively measure mechanical properties of MTrPs and surrounding tissue in the upper trapezius. In an ongoing clinical study, we recruited 34 subjects: 12 healthy controls, 5 with latent (not spontaneously painful) MTrPs and 17 with symptomatic chronic neck pain and active (spontaneously painful) MTrPs. Shear wave elastography was performed on the upper trapezius of all subjects using the Ultrasonix RP system and an external vibrator. Voigt's model was used to estimate shear modulus G and viscosity μ of the interrogated tissue. Preliminary analysis demonstrates that symptomatic muscle tissue in subjects with neck pain is stiffer (G=10.45±11.36 kPa, mean±standard deviation) compared to muscle in control subjects (G=2.08±1.28 kPa) and that muscle tissue with latent MTrPs (μ=14.39±6.41 Pa*s) is more viscous than normal tissue (μ=9.02±3.92 Pa*s) (p<0.05).

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Forces of Orthodontic Closed Coil Springs Measured using Fiber Bragg Gratings

Forces of Orthodontic Closed Coil Springs Measured using Fib...

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Latin America Optics and Photonics Conference, LAOP 2012

作者： Milczewski, Maura Scandelari Dinisio, Felipe Gonçalves Martelli, Cicero Borges, Paulo César Kalinowski, Hypolito José da Cunha, José Carlos Munhoz Federal University of Technology - Paraná Curitiba80230-901 Brazil Graduate Program on Electrical Engineering and Applied Computer Science Canada Department of Mechanical Engineering Brazilian Dentistry Association Paraná Brazil

The aim of this study is to compare forces generated by three different orthodontic closed coil springs supplied by three companies, optical fiber Bragg gratins are used to evaluate the force of closing of springs. &#... 详细信息

ISBN: (纸本)9781557529589

关键词： Fiber Bragg gratings

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