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Nonspherical laser-induced cavitation bubbles

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Physical Review E 2010年第1期81卷 016308-016308页

作者： Kang Yuan Lim Pedro A. Quinto-Su Evert Klaseboer Boo Cheong Khoo Vasan Venugopalan Claus-Dieter Ohl Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University 21 Nanyang Link Singapore 637371 Singapore Institute of High Performance Computing Fusionopolis 1 Fusionopolis Way #16-16 Connexis Singapore 138632 Singapore Department of Mechanical Engineering National University of Singapore 10 Kent Ridge Crescent Singapore 119260 Singapore Department of Chemical Engineering and Materials Science and Laser Microbeam and Medical Program Beckman Laser Institute University of California Irvine California 92697-2575 USA

The generation of arbitrarily shaped nonspherical laser-induced cavitation bubbles is demonstrated with a optical technique. The nonspherical bubbles are formed using laser intensity patterns shaped by a spatial light modulator using linear absorption inside a liquid gap with a thickness of 40 μm. In particular we demonstrate the dynamics of elliptic, toroidal, square, and V-shaped bubbles. The bubble dynamics is recorded with a high-speed camera at framing rates of up to 300 000 frames per second. The observed bubble evolution is compared to predictions from an axisymmetric boundary element simulation which provides good qualitative agreement. Interesting dynamic features that are observed in both the experiment and simulation include the inversion of the major and minor axis for elliptical bubbles, the rotation of the shape for square bubbles, and the formation of a unidirectional jet for V-shaped bubbles. Further we demonstrate that specific bubble shapes can either be formed directly through the intensity distribution of a single laser focus, or indirectly using secondary bubbles that either confine the central bubble or coalesce with the main bubble. The former approach provides the ability to generate in principle any complex bubble geometry.

关键词： High speed cameras

Advances in tangible interaction and ubiquitous virtual reality

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Advances in tangible interaction and ubiquitous virtual real...

作者： Hong, Dongpyo Höllerer, Tobias Haller, Michael Takemura, Haruo Cheok, Adrian David Kim, Gerard Jounghyun Billinghurst, Mark Woo, Woontack Hornecker, Eva Jacob, Robert J.K. Hummels, Caroline Ullmer, Brygg Schmidt, Albrecht Van Den Hoven, Elise Mazalek, Ali Gwangju Institute of Science and Technology Department of Computer Science University of California Santa Barbara Upper Austria University of Applied Sciences Department of Digital Media Infomedia Education Division Osaka University Cybermedia Center National University of Singapore Mixed Reality Lab. Keio University Department of Computer Science and Engineering Korea University Gwangju Institute of Science and Technology Open University Pervasive Interaction Lab. Department of Computer Science Tufts University Eindhoven University of Technology Department of Industrial Design Department of Computer Science Louisiana State University University of Duisburg Pervasive Computing and User Interface Engineering Group Essen Digital Media Program Georgia Institute of Technology

The first article reports on context-sensitive augmented-reality research presented at the 2007 International Symposium on Ubiquitous Virtual Reality. This student-organized event explored the use of contextual information, design principles, and effective user evaluation for developing AR applications for ubiquitous computing environments. The second article reports on The International Conference on Tangible and Embedded Interaction, the first conference series worldwide to focus on tangible and embedded interaction. The conference is interdisciplinary, covering the arts, hardware design, software toolkits for prototyping, and user studies and theory development. © 2006 IEEE.

关键词： Virtual reality

A computational information criterion for particle-tracking with sparse or noisy data

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arXiv 2021年

作者： Tran, Nhat Thanh Benson, David A. Schmidt, Michael J. Pankavich, Stephen D. Department of Mathematics University of California Irvine IrvineCA92697 United States Hydrologic Science and Engineering Program Department of Geology and Geological Engineering Colorado School of Mines GoldenCO80401 United States Center for Computing Research Sandia National Laboratories AlbuquerqueNM87185 United States Department of Applied Mathematics and Statistics Colorado School of Mines GoldenCO80401 United States

Traditional probabilistic methods for the simulation of advection-diffusion equations (ADEs) often overlook the entropic contribution of the discretization, e.g., the number of particles, within associated numerical methods. Many times, the gain in accuracy of a highly discretized numerical model is outweighed by its associated computational costs or the noise within the data. We address the question of how many particles are needed in a simulation to best approximate and estimate parameters in one-dimensional advective-diffusive transport. To do so, we use the well-known Akaike Information Criterion (AIC) and a recently-developed correction called the Computational Information Criterion (COMIC) to guide the model selection process. Random-walk and mass-transfer particle tracking methods are employed to solve the model equations at various levels of discretization. Numerical results demonstrate that the COMIC provides an optimal number of particles that can describe a more efficient model in terms of parameter estimation and model prediction compared to the model selected by the AIC even when the data is sparse or noisy, the sampling volume is not uniform throughout the physical domain, or the error distribution of the data is non-IID Gaussian. Keywords: Computational Information Criterion, Lagrangian Modeling, Particle Methods, Diffusion-reaction Equation, Non-Gaussian Error Distribution Copyright © 2021, The Authors. All rights reserved.

关键词： Advection

BLIS-Net: Classifying and Analyzing Signals on Graphs

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arXiv 2023年

作者： Xu, Charles Goldman, Laney Guo, Valentina Hollander-Bodie, Benjamin Trank-Greene, Maedee Adelstein, Ian De Brouwer, Edward Ying, Rex Krishnaswamy, Smita Perlmutter, Michael Department of Mathematics Yale University United States Department of Computer Science Yale University United States Department of Mathematics Harvey Mudd College United States Department of Genetics Yale School of Medicine United States Department of Applied Mathematics University of Colorado Boulder United States Department of Mathematics Boise State University United States Program in Computing Boise State University United States

Graph neural networks (GNNs) have emerged as a powerful tool for tasks such as node classification and graph classification. However, much less work has been done on signal classification, where the data consists of many functions (referred to as signals) defined on the vertices of a single graph. These tasks require networks designed differently from those designed for traditional GNN tasks. Indeed, traditional GNNs rely on localized low-pass filters, and signals of interest may have intricate multi-frequency behavior and exhibit long range interactions. This motivates us to introduce the BLIS-Net (Bi-Lipschitz Scattering Net), a novel GNN that builds on the previously introduced geometric scattering transform. Our network is able to capture both local and global signal structure and is able to capture both low-frequency and high-frequency information. We make several crucial changes to the original geometric scattering architecture which we prove increase the ability of our network to capture information about the input signal and show that BLIS-Net achieves superior performance on both synthetic and real-world data sets based on traffic flow and fMRI data. Copyright © 2023, The Authors. All rights reserved.

关键词： Graph neural networks

A multi-agent system for optimizing physiological collection based on adaptive strategies

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Smart Health 2021年 19卷

作者： Aranda, Jorge Arthur Schneider Bavaresco, Rodrigo Simon da Silva Machado, Roger de Carvalho, Juliano Varella Corrêa, Adenauer Yamin Barbosa, Jorge Luis Victória Applied Computing Graduate Program (PPGCA) of University of Vale do Rio dos Sinos (UNISINOS) Av. Unisinos 950 São Leopoldo 93.022-750 RS Brazil Creative and Technological Sciences Institute of Feevale University ERS 239 2755 Novo Hamburgo RS 93525-075 RS Brazil Computer Science Graduate Program of Federal University of Pelotas Gomes Carneiro 1 Pelotas 96010-610 RS Brazil

Wearable devices have emerged from the evolution of communication and information technology, along with the miniaturization of electronic components. These devices monitor the user's physiology on a periodic basis and generally have low battery autonomy. This article proposes the Odin system, a multi-agent system that performs real-time analysis of physiological data in order to adapt the collection according to the user's health condition. Two types of adaptation were proposed in terms of adapting the collection. The first, wait-time adaptation (WTA), consists of collecting physiological data through a sensor defined as the main sensor, where the frequency of the collection is based on the user's condition. Meanwhile, the second, paused sensors adaptation (PSA), manages the activation status of secondary sensors when the main sensor suggests a possible risk to the user's health. An evaluation was implemented through two steps. First, a simulation was performed with requests control to optimize the parameters of the data collection. These results showed an increase of 214% in battery life in the adaptive scenario compared to one with no adaptivity. Second, Odin's adaptivity was evaluated in terms of a real dataset, which allowed for the reduction of the number of requests. This reduction optimized the battery consumption, with a 66% improvement over data collection with no adaptivity. © 2020 Elsevier Inc.

关键词： Adaptive systems Embedded systems Healthcare Wearable Devices

Nonuniform 3D finite difference elastic wave simulation on staggered grids

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arXiv 2020年

作者： Gao, Longfei Ghattas, Omar Keyes, David Oden Institute for Computational Engineering and Sciences The University of Texas at Austin AustinTX78712 United States Oden Institute for Computational Engineering and Sciences Jackson School of Geosciences Department of Mechanical Engineering The University of Texas at Austin AustinTX78712 United States Applied Mathematics and Computational Science Program Extreme Computing Research Center King Abdullah University of Science and Technology Thuwal23955-6900 Saudi Arabia

We present an approach to simulate the 3D isotropic elastic wave propagation using nonuniform finite difference discretization on staggered grids. Specifically, we consider simulation domains composed of layers of uniform grids with different grid spacings, separated by nonconforming interfaces. We demonstrate that this layer-wise finite difference discretization has the potential to significantly reduce the simulation cost, compared to its fully uniform counterpart. Stability of such a discretization is achieved by using specially designed difference operators, which are variants of the standard difference operators with adaptations near boundaries or interfaces, and penalty terms, which are appended to the discretized wave system to weakly impose boundary or interface conditions. Combined with specially designed interpolation operators, the discretized wave system is shown to preserve the energy conserving property of the continuous elastic wave equation, and a fortiori ensure the stability of the simulation. Numerical examples are presented to demonstrate the efficacy of the proposed simulation approach. © 2020, CC BY.

关键词： Elastic waves

A Web-Based Tool for Semi-Automated Segmentation of Histopathological Images Using Nonlinear Color Classifiers

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A Web-Based Tool for Semi-Automated Segmentation of Histopat...

Annual IEEE Symposium on Computer-Based Medical Systems

作者： Marcelo Dornbusch Lopes Antonio C. Sobieranski Aldo Von Wangenheim Eros Comunello INCoD - National Brazilian Institute for Digital Convergence / LAPIX - Image Processing and Computer Graphics Lab - Federal University of Santa Catarina Brazil Postgraduate Program in Applied Computing University of Itajai Valley - UNIVALI INCoD (Nat. Brazilian Inst. for Digital Convergence) LAPIX (Image Process. & Comput. Graphics Lab.) Universidade Federal de Santa Catarina Florianopolis SC BR

ISBN: (纸本)9781467390378

Histopathological staining is a technique widely used to highlight biological states or pharmacological activities in uman tissue. A quantitative analysis of the resulting images can produce biomarkers for diseases or even other specific conditions, thus providing valuable information for diagnosis and prognosis. Since biomarkers require measurements to be made in an objective and consistent way, software systems are employed to provide this quantitative analysis. For measurements to be reproducible, the same methods must be available across different laboratories. In this paper, we present a tool that allows users to perform quantitative analyses over the web, thus providing an efficient environment not only for individual cases to be evaluated, but also for users to share a common ground when making measurements. The classification method used by the tool to segment stained pixels is performed by a similarity function based on the polynomial version of the Mahalanobis distance, which is nonlinear and provides very robust classification for m-dimensional feature spaces. Furthermore, the similarity function can be generalized in the tool, so that images can be classified by reusing parameters of previous cases. The results of our web-based approach were compared with established ground-truth data sets, producing sensitivity, specificity and fitness values of 97.09%, 98.70%, and 97.90%.

关键词： Image color analysis Image segmentation Biomarkers Sensitivity Inspection Servers Statistical analysis

Dynamic compressed sensing for real-Time tomographic reconstruction

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arXiv 2020年

作者： Schwartz, Jonathan Zheng, Huihuo Hanwell, Marcus Jiang, Yi Hovden, Robert Department of Material Science and Engineering Ann ArborUniversity of Michigan MichiganMI United States Argonne Leadership Computing Facility Argonne National Laboratory LemontIL United States Kitware Inc Clifton ParkNY United States Advanced Photon Source Facility Argonne National Laboratory LemontIL United States Applied Physics Program University of Michigan Ann ArborMI United States

Electron tomography has achieved higher resolution and quality at reduced doses with recent advances in compressed sensing. Compressed sensing (CS) theory exploits the inherent sparse signal structure to effciently reconstruct three-dimensional (3D) volumes at the nanoscale from un-dersampled measurements. However, the process bottlenecks 3D reconstruction with computation times that run from hours to days. Here we demonstrate a framework for dynamic compressed sens-ing that produces a 3D specimen structure that updates in real-Time as new specimen projections are collected. Researchers can begin interpreting 3D specimens as data is collected to facilitate high-throughput and interactive analysis. Using scanning transmission electron microscopy (STEM), we show that dynamic compressed sensing accelerates the convergence speed by 3-fold while also re-ducing its error by 27% for a Au/SrTiO3 nanoparticle specimen. Before a tomography experiment is completed, the 3D tomogram has interpretable structure within 33% of completion and fine details are visible as early as 66%. Upon completion of an experiment, a high-fidelity 3D visualization is produced without further delay. Additionally, reconstruction parameters that tune data delity can be manipulated throughout the computation without rerunning the entire process. Copyright © 2020, The Authors. All rights reserved.

关键词： Compressed sensing

Using causal loop diagrams to explore the maternal and child health system response to payment for performance in Zambia, and it’s generalisability across settings

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SSM - Health Systems

SSM - Health Systems 2025年 5卷

作者： Chitalu Miriam Chama-Chiliba Nkenda Sachingongu Rachel Cassidy Peter Binyaruka Collins Chansa Agnes Rwashana Semwanga Josephine Borghi Institute of Economic and Social Research University of Zambia P O Box 32379 Plot 2631 Munali Road Chudleigh Lusaka 10101 Zambia Department of Gender Studies University of Zambia P O Box 32379 Great East Road Campus Lusaka 10101 Zambia KPM Center for Public Management University of Bern Bern 3012 Switzerland Swiss Institute for Translational and Entrepreneurial Medicine Bern 3010 Switzerland Department of Global Health and Development London School of Hygiene and Tropical Medicine 15-17 Tavistock Place London WC1H 9SH UK Ifakara Health Institute P O Box 78373 Dar es Salaam Tanzania Health Nutrition and Population Global Practice World Bank Group Monrovia Liberia Heidelberg Institute of Global Health Heidelberg University Hospital and Medical Faculty Heidelberg Germany Information Systems Department College of Computing and Information Sciences Makerere University P O Box 7062 Kampala Uganda Social Cohesion Health and Wellbeing Research Group Population and Just Societies Program International Institute for Applied Systems Analysis Austria

This study investigates the generalisability of pathways depicted by causal loop diagrams (CLDs) in payment for performance (P4P) schemes by adapting and validating the Tanzanian CLDs to the Zambian context. Specifically, it explores whether the health system pathways represented by CLDs, are consistent across different settings and how variations in programme design and local context influence these pathways. Using a five-stage approach, the study adapted the Tanzanian CLDs to reflect the Zambian P4P programme context, validating them through stakeholder interviews, workshops, and secondary qualitative data. The findings show that while the overarching pathways influencing P4P outcomes are similar, differences in programme design and contextual factors shape their intensity and impact. Notably, Zambia’s higher facility autonomy and stronger trust in the health system contributed to greater health worker motivation and service delivery compared to Tanzania. programme design features such as safeguards for non-incentivised services and adequate funding for facility investment with provider autonomy influenced performance outcomes. Additionally, contextual factors such as trust in the system mitigated programme delays, while decentralised procurement systems enhanced P4P effectiveness. These findings highlight the need for context-specific adaptation when implementing P4P programmes. The study advances the application of CLDs for cross-country health system analysis, highlighting both their potential and limitations in comparing health interventions across diverse settings.

关键词： Health system Causal loop diagram Payment for performance Maternal and child health Zambia Tanzania