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作者： Bajwa, Waheed U. Calderbank, Robert Jafarpour, Sina Department of Electrical Engineering Program in Applied and Computational Mathematics Princeton University Princeton NJ 08544 United States Department of Computer Science Princeton University Princeton NJ 08544 United States

The problem of model selection arises in a number of contexts, such as subset selection in linear regression, estimation of structures in graphical models, and signal denoising. This paper studies non-asymptotic model selection for the general case of arbitrary (random or deterministic) design matrices and arbitrary nonzero entries of the signal. In this regard, it generalizes the notion of incoherence in the existing literature on model selection and introduces two fundamental measures of coherence- termed as the worst-case coherence and the average coherence-among the columns of a design matrix. It utilizes these two measures of coherence to provide an in-depth analysis of a simple, model-order agnostic one-step thresholding (OST) algorithm for model selection and proves that OST is feasible for exact as well as partial model selection as long as the design matrix obeys an easily verifiable property, which is termed as the coherence property. One of the key insights offered by the ensuing analysis in this regard is that OST can successfully carry out model selection even when methods based on convex optimization such as the lasso fail due to the rank deficiency of the submatrices of the design matrix. In addition, the paper establishes that if the design matrix has reasonably small worst-case and average coherence then OST performs near-optimally when either (i) the energy of any nonzero entry of the signal is close to the average signal energy per nonzero entry or (ii) the signal-to-noise ratio in the measurement system is not too high. Finally, two other key contributions of the paper are that (i) it provides bounds on the average coherence of Gaussian matrices and Gabor frames, and (ii) it extends the results on model selection using OST to low-complexity, model-order agnostic recovery of sparse signals with arbitrary nonzero entries. In particular, this part of the analysis in the paper implies that an Alltop Gabor frame together with OST can successfully carr

关键词： Recovery

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Graphene: Growth of Single Crystal Graphene Arrays by Locally Controlling Nucleation on Polycrystalline Cu Using Chemical Vapor Deposition (Adv. Mater. 42/2011)

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Advanced Materials 2011年第42期23卷

作者： Wei Wu Luis A. Jauregui Zhihua Su Zhihong Liu Jiming Bao Yong P. Chen Qingkai Yu Center for Advanced Materials University of Houston Houston TX 77204 USA Department of Electrical and Computer Engineering University of Houston Houston TX 77204 USA Birck Nanotechnology Center School of Electrical and Computer Engineering Department of Physics Purdue University West Lafayette IN 47907 USA Ingram School of Engineering and Materials Science Engineering and Commercialization Program Texas State University San Marcos TX 78666 USA

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PDMS stretchable platforms for the studies of mechanical compression on neurogenesis

PDMS stretchable platforms for the studies of mechanical com...

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4th IEEE International Conference on Nano/Molecular Medicine and engineering, IEEE NANOMED 2010

作者： Esfandiari, Leyla Tang, William C. Biomedical Engineering Interdepartmental Program University of California Los Angeles CA United States Department of Biomedical Engineering University of California Irvine CA United States Department of Electrical Engineering and Computer Science University of California Irvine CA United States

ISBN: (纸本)9781612841533

The use of MEMS to study the effect of mechanical compression on neurogenesis has been demonstrated. Polydimethylsiloxane- (PDMS)-based stretchable platforms were used on neurosphere assay to investigate the role of mechanical forces on the formation of radial glial processes, neuronal generation and migration. To induce mechanical compression on neurospheres, The PDMS culturing substrate is patterned with micron-sized wells. Neurospheres are cultured on the prestretched device. After 48 hours, when neurospheres are grown to the size of the well's width, the stretched substrate is released. The experimental results showed that applied mechanical compression on neural stem cells cultured as neurospheres could be a factor accelerating the radial glial formation, which is associated to neurogenesis and neuronal migration. © 2010 IEEE.

关键词： Polydimethylsiloxane

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Level Set Diffusion for MRE Image Enhancement

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5th International Workshop on Medical Imaging and Augmented Reality

作者： Li, Bing Nan Chui, Chee Kong Ong, Sim Heng Chang, Stephen Kobayashi, Etsuko NUS Graduate School for Integrative Science and Engineering National University of Singapore Singapore Singapore Department of Mechanical Engineering National University of Singapore Singapore Singapore Department of Electrical and Computer Engineering National University of Singapore Singapore Singapore Division of Bioengineering National University of Singapore Singapore Singapore Department of Surgery National University Hospital Singapore Singapore Department of Precision Engineering University of Tokyo Tokyo Japan

ISBN: (纸本)9783642156984

Magnetic resonance elastography (MRE) is an emerging technique for noninvasive imaging of tissue elasticity. Proprietary algorithms are used to reconstruct tissue elasticity from the images of wave propagation within soft tissue. Elasticity reconstruction suffers from interfering noise and outliers. The interference causes biased elasticity and undesired artifacts in the reconstructed elasticity map. Anisotropic geometric diffusion is able to suppress image noise while enhance inherent features. Therefore we integrate anisotropic diffusion with level set methods for numerical enhancement of MRE wave images. Performance evaluation of the proposed level set diffusion (LSD) approach was conducted on both synthetic and real MRE datasets. Experimental results confirm the effectiveness of LSD for MRE image enhancement and direct inversion.

关键词： Anisotropic diffusion image enhancement level set methods magnetic resonance elastography (MRE) noise suppression

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In vivo measurement of the complex shear modulus of rat mammary tumors using shear wave imaging techniques

In vivo measurement of the complex shear modulus of rat mamm...

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作者： Wang, Yue Orescanin, Marko Insana, Michael F. Department of Bioengineering Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign Urbana IL 61801 United States Department of Electrical and Computer Engineering Beckman Institute for Advanced Science and Technology University of Illinois at Urbana-Champaign Urbana IL 61801 United States

ISBN: (纸本)9781424441235

This paper summarizes dynamic measurements of shear modulus constants acquired for spontaneously growing rat mammary tumors. Measurements are compared with histology to determine tumor types. We also report on 3D shear-wave velocity fields acquired from an inhomogeneous hydrogel phantom with known mechanical properties. Phantom measurements enable us to interpret the effects of tissue structure and geometry on viscoelastic parameter estimates, and demonstrate that reproducible measurements are possible in vivo. Viscoelastic properties describe the mechano-environment of cells undergoing malignant transformation and tumor growth. © 2010 IEEE.

关键词： Rats

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Probabilistic Multi-Task Feature Selection 10

Probabilistic Multi-Task Feature Selection

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Annual Conference on Neural Information Processing Systems

作者： Yu Zhang Dit-Yan Yeang Qian Xu Department of Computer Science and Engineering Hong Kong University of Science and Technology Bioengineering Program Hong Kong University of Science and Technology

ISBN: (纸本)9781617823800

Recently, some variants of the l_1 norm, particularly matrix norms such as the l_(1,2) and l_(1,∞) norms, have been widely used in multi-task learning, compressed sensing and other related areas to enforce sparsity via joint regularized on. In this paper, we unify the l_(1,2) and l_(1,∞) norms by considering a family of l_(1,q) norms for 1 < q < ∞ and study the problem of determining the most appropriate sparsity enforcing norm to use in the context of multi-task feature selection. Using the generalized normal distribution, we provide a probabilistic interpretation of the general multi-task feature selection problem using the l_(1,q) norm. Based on this probabilistic interpretation, we develop a probabilistic model using the noninfor-mative Jeffreys prior. We also extend the model to learn and exploit more general types of pairwise relationships between tasks. For both versions of the model, we devise expectation-maximization (EM) algorithms to learn all model parameters, including q, automatically. Experiments have been conducted on two cancer classification applications using microarray gene expression data.

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Experimental measurement of growth patterns on fossil corals:Secular variation in ancient Earth-Sun distances

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Chinese science Bulletin 2010年第35期55卷 4010-4017页

作者： ZHANG WeiJia1,3,4,LI ZhengBin2,3 & LEI Yang1 1 department of Physics,Peking University,Beijing 100871,China 2 department of electrical engineering and computer science,Peking University,Beijing 100871,China 3 State Key Laboratory of Advanced Optical Communication Systems & Networks,Peking University,Beijing 100871,China 4 Committee of Yuanpei Honors program,Peking University,Beijing 100871,China Department of Physics Peking University Beijing 100871 China State Key Laboratory of Advanced Optical Communication Systems & Networks Peking University Beijing 100871 China Committee of Yuanpei Honors Program Peking University Beijing 100871 China Department of Electrical Engineering and Computer Science Peking University Beijing 100871 China

In recent years,much attention has been given to the increase in the Earth-Sun distance,with the modern rate reported as 5-15 m/cy on the basis of astronomical ***,traditional methods cannot measure the ancient leaving rates,so a myriad of research attempting to provide explanations were met with unmatched *** this paper we consider that the growth patterns on fossils could reflect the ancient Earth-Sun *** mechanical analysis of both the Earth-Sun and Earth-Moon systems,these patterns confirmed an increase in the Earth-Sun *** a large number of well-preserved specimens and new technology available,both the modern and ancient leaving rates could be measured with high precision,and it was found that the Earth has been leaving the Sun over the past 0.53 billion *** Earth's semi-major axis was 146 million kilometers at the beginning of the Phanerozoic Eon,equating to 97.6% of its current *** modern leaving rates are 5-14 m/cy,whereas the ancient rates were much *** results indicate a special expansion with an average expansion coefficient of 0.57H0 and deceleration in the form of Hubble *** the basis of experimental results,the Earth's semi-major axis could be represented by a simple formula that matches fossil measurements.

关键词：地球太阳古代距离生长模式实验石珊瑚量化

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Experimental analysis of coordination strategies to support wireless sensor networks composed by static ground sensors and UAV-carried sensors

Experimental analysis of coordination strategies to support ...

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IEEE International Symposium on Parallel and Distributed Processing With Applications

作者： De Freitas, Edison Pignaton Heimfarth, Tales Pereira, Carlos Eduardo Ferreira, Armando Morado Wagner, Flávio Rech Larsson, Tony School of Information Science Computer and Electrical Engineering Halmstad University Halmstad Sweden Institute of Informatics Federal University of Rio Grande do Sul Porto Alegre Brazil Computer Science Department Federal University of Lavras Lavras Brazil Defense Engineering Graduate Program Military Institute of Engineering Rio de Janeiro Brazil

ISBN: (纸本)9780769541907

This paper presents a comparison among different strategies to coordinate the use of heterogeneous wireless sensors aimed for area surveillance. The heterogeneity among the sensor nodes is related to their sensing and mobility capabilities. The goal of the strategies is to provide coordination among the different nodes, in order to make the wireless sensor network perform its missions with higher efficiency. Strategies combine advantages of bio-inspired and utility-based approaches to coordination. Simulations of scenarios with different characteristics were performed and the results are compared and analyzed. © 2010 IEEE.

关键词： Sensor nodes

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Mammalian cell sorting using ∝FACS

Mammalian cell sorting using ∝FACS

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作者： Cho, Sung Hwan Chen, Chun Hao Tsai, Frank S. Godin, Jessica Lo, Yu-Hwa Materials Science and Engineering Program Jacobs School of Engineering University of California San Diego San Diego CA United States Department of Bioengineering Jacobs School of Engineering University of California San Diego San Diego CA United States Department of Electrical and Computer Engineering Jacobs School of Engineering University of California San Diego San Diego CA United States

K562 mammalian cells are sorted using a highly integrated microfabricated fluorescence-activated cell sorter (∝FACS). The sample cells are purified with an enrichment factor of 230 at a high throughput (> 1,000 ce... 详细信息

ISBN: (纸本)9781557528902

关键词： Cytology

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Mission-oriented design: A fully autonomous mobile urban robot

Mission-oriented design: A fully autonomous mobile urban rob...

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IEEE International Conference on Multisensor Fusion and Integration for Intelligent Systems

作者： Zhang, Qun Tao, Pey Yuen Abraham, Aswin Thomas Rebsamen, Brice Yang, Chenguang Ge, Shuzhi Sam National University of Singapore Singapore 117456 Singapore A Star Agency for Science Technology and Research Singapore 638075 Singapore Department of Electrical and Computer Engineering Singapore Temasek Laboratories National University of Singapore Singapore 117411 Singapore Department of Bioengineering Imperial College London London SW7 2AZ United Kingdom Department of Electrical and Computer Engineering National University of Singapore Singapore 117576 Singapore

ISBN: (纸本)9781424454266

This paper describes a fully autonomous mobile urban robot-X1, which can perform multiple tasks autonomously in an unknown urban environment without human guidance, including mobile reconnaissance, target searching, and object manipulation. The mission-oriented design, which allows reliability and extensibility of the robotic system, includes a high degree of modularity for both hardware and software architecture, and coordination between tasks. Our strategy specifically addresses fundamental issues such as autonomous navigation in unknown urban environments and vision-based object manipulation. All the functionalities have been proved effective in the real urban environments. The robot platform is being built to provide valuable experiences on autonomous robotics research. © 2010 IEEE.

关键词： Robots

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