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Selection of a cut-off for high-and low-methane producers using a spot-methane breath test:results from a large north American dataset of hydrogen,methane and carbon dioxide measurements in breath

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Gastroenterology Report 2017年第3期5卷 193-199,I0001,I0002页

作者： Klaus Gottlieb Chenxiong Le Vince Wacher Joe Sliman Christine Cruz Tyler Porter Stephen Carter Synthetic Biologics Inc. RockvilleMarylandUSA commonwealth laboratories llc SalemMassachusettsUSA

Background:Levels of breath methane,together with breath hydrogen,are determined by means of repeated collections of both,following ingestion of a carbohydrate substrate,at 15–20 minutes intervals,until 10 samples have been *** frequent sampling is required to capture a rise of hydrogen emissions,which typically occur later in the test:in contrast,methane levels are typically elevated at *** methane emissions represent the principal objective of the test,a spot methane test(i.e.a single-time-point sample taken after an overnight fast without administration of substrate)may be ***:We analysed 10-sample lactulose breath test data from 11674 consecutive unique subjects who submitted samples to commonwealth laboratories(Salem,MA,USA)from sites in all of the states of the USA over a one-year *** North American Consensus(NAC)guidelines criteria for breath testing served as a reference ***:The overall prevalence of methane-positive subjects(by NAC criteria)was 20.4%,based on corrected methane results,and 18.9% based on raw *** our USA dataset,the optimal cut-off level to maximize sensitivity and specificity was4ppm CH4,94.5%[confidence interval(CI):93.5–95.4%]and 95.0%(CI:94.6–95.5%),*** use of a correction factor(CF)(5%CO_(2) as numerator)led to reclassifications CH4-high to CH_(4)-low in 0.7% and CH_(4)-low to CH_(4)-high in 2.1%.Conclusions:A cut-off value for methane at baseline of either≥4 ppm,as in our USA dataset,or≥5 ppm,as described in a single institution study,are both highly accurate in identifying subjects at baseline that would be diagnosed as‘methanepositive’in a 10-sample lactulose breath test for small intestinal bacterial overgrowth.

关键词： breath tests spot-methane breath test diagnostic test small intestinal bacterial overgrowth

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Gastroenterology Report 2018年第3期6卷 242-242,I0003页

Gastroenterol Rep(Oxf).2017 doi:10.1093/gastro/*** authors wish to inform the reader that any references to‘confidential interval’throughout the paper have been corrected to‘confidence interval’.The paper has now ... 详细信息

关键词： methane dioxide corrected

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Analysis of Anisotropic Nonlocal Diffusion Models:Well-Posedness of Fractional Problems for Anomalous Transport

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Numerical Mathematics(Theory,Methods and Applications) 2022年第4期15卷 851-875页

作者： Marta D’Elia Mamikon Gulian Data Science and Computing Sandia National LaboratoriesCAUSA

We analyze the well-posedness of an anisotropic,nonlocal diffusion *** an equivalence between weighted and unweighted anisotropic nonlocal diffusion operators in the vein of unified nonlocal vector calculus,we apply our analysis to a class of fractional-order operators and present rigorous estimates for the solution of the corresponding anisotropic anomalous diffusion ***,we extend our analysis to the anisotropic diffusion-advection equation and prove well-posedness for fractional orders s∈[0.5,1).We also present an application of the advection-diffusion equation to anomalous transport of solutes.

关键词： Nonlocal models fractional models anomalous diffusion anisotropic diffusion solute transport

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Machine Learning Models of Plastic Flow Based on Representation Theory

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Computer Modeling in Engineering & Sciences 2018年第12期117卷 309-342页

作者： R.E.Jones J.A.Templeton C.M.Sanders J.T.Ostien Sandia National laboratories P.O.Box 969LivermoreCA 94551USA.

We use machine learning(ML)to infer stress and plastic flow rules using data from representative polycrystalline *** particular,we use so-called deep(multilayer)neural networks(NN)to represent the two response *** ML process does not choose appropriate inputs or outputs,rather it is trained on selected inputs and ***,its discrimination of features is crucially connected to the chosen inputoutput ***,we draw upon classical constitutive modeling to select inputs and enforce well-accepted symmetries and other *** the context of the results of numerous simulations,we discuss the design,stability and accuracy of constitutive NNs trained on typical experimental *** these developments,we enable rapid model building in real-time with experiments,and guide data collection and feature discovery.

关键词： Machine learning constitutive modeling plasticity invariance.

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Millimeter Wave and Terahertz Communications: Feasibility and Challenges

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ZTE Communications 2012年第4期10卷 3-12页

作者： Phil Pietraski David Britz Arnab Roy Ravi Pragada Gregg Charlton InterDigital Communications llc. MelvilleNY 11747 USA AT&T Labs Shannon laboratories Florham ParkNJ 07932 USA InterDigital Communications llc. King of PrussiaPA 19406 USA

In this paper, the challenges with and motivations for developing millimeter wave and terahertz communications are described. A high-bye candidate architecture is presented, and use cases highlighting the potential applicability of high-frequency links are discussed. Mobility challenges at these higher frequencies are also discussed. Difficulties that arise as a result of high carrier frequencies and higher path loss can be overcome by practical, higher-gain antennas that have the added benefit of reducing intercell interference. Simulation methodology and results are given. The results show that millimeter wave coverage is possible in large, outdoor spaces, and only a reasonable number of base stations are needed. Network throughput can exceed 25 Gbit/s, and cell-edge user throuqhput can reach aDoroximatelv 100 Mbit/s.

关键词： millimeter wave terahertz small cells propagation mesh backhaul

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Power Factor Estimation of Distributed Energy Resources Using Voltage Magnitude Measurements

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Journal of Modern Power Systems and Clean Energy 2021年第4期9卷 859-869页

作者： Samuel Talkington Santiago Grijalva Matthew J.Reno School of Electrical and Computer Engineering Georgia Institute of TechnologyAtlantaGA 30318USA Electric Power Systems Research Department Sandia National LaboratoriesAlbuquerqueNM 87123USA

This paper presents a new method for the estimation of the injection state and power factor of distributed energy resources (DERs) using voltage magnitude measurements only. A physics-based linear model is used to develop estimation heuristics for net injections of real and reactive power at a set of buses under study, allowing a distribution engineer to form a robust estimate for the operating state and the power factor of the DER at those buses. The method demonstrates and exploits a mathematical distinction between the voltage sensitivity signatures of real and reactive power injections for a fixed power system model. Case studies on various test feeders for a model of the distribution circuit and statistical analyses are presented to demonstrate the validity of the estimation method. The results of this paper can be used to improve the limited information about inverter parameters and operating state during renewable planning, which helps mitigate the uncertainty inherent in their integration.

关键词： Decentralized power system control detection and estimation power factor sparse approximation

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Learning two-phase microstructure evolution using neural operators and autoencoder architectures

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npj Computational Materials 2022年第1期8卷 1804-1816页

作者： Vivek Oommen Khemraj Shukla Somdatta Goswami Rémi Dingreville George Em Karniadakis School of Engineering Brown UniversityProvidenceRIUSA Division of Applied Mathematics Brown UniversityProvidenceRIUSA Center for Integrated Nanotechnologies Sandia National LaboratoriesAlbuquerqueNM87185USA

Phase-field modeling is an effective but computationally expensive method for capturing the mesoscale morphological and microstructure evolution in ***,fast and generalizable surrogate models are needed to alleviate the cost of computationally taxing processes such as in optimization and design of *** intrinsic discontinuous nature of the physical phenomena incurred by the presence of sharp phase boundaries makes the training of the surrogate model *** develop a framework that integrates a convolutional autoencoder architecture with a deep neural operator(DeepONet)to learn the dynamic evolution of a two-phase mixture and accelerate time-to-solution in predicting the microstructure *** utilize the convolutional autoencoder to provide a compact representation of the microstructure data in a low-dimensional latent *** DeepONet is trained in the latent space,it can be used to replace the high-fidelity phase-field numerical solver in interpolation tasks or to accelerate the numerical solver in extrapolation tasks.

关键词： materials phase operators

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Performant implementation of the atomic cluster expansion(PACE)and application to copper and silicon

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npj Computational Materials 2021年第1期7卷 878-889页

作者： Yury Lysogorskiy Cas van der Oord Anton Bochkarev Sarath Menon Matteo Rinaldi Thomas Hammerschmidt Matous Mrovec Aidan Thompson Gábor Csányi Christoph Ortner Ralf Drautz ICAMS Ruhr-Universität BochumBochumGermany Engineering Laboratory University of CambridgeCambridgeUK Center for Computing Research Sandia National LaboratoriesAlbuquerqueNMUSA Department of Mathematics University of British ColumbiaVancouverBCCanada

The atomic cluster expansion is a general polynomial expansion of the atomic energy in multi-atom basis *** we implement the atomic cluster expansion in the performant C++code PACE that is suitable for use in large-scale atomistic *** briefly review the atomic cluster expansion and give detailed expressions for energies and forces as well as efficient algorithms for their *** demonstrate that the atomic cluster expansion as implemented in PACE shifts a previously established Pareto front for machine learning interatomic potentials toward faster and more accurate ***,general purpose parameterizations are presented for copper and silicon and evaluated in *** show that the Cu and Si potentials significantly improve on the best available potentials for highly accurate large-scale atomistic simulations.

关键词： functions expansion cluster

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Stability of Efficient Deterministic Compressed Sensing for Images with Chirps and Reed-Muller Sequences

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Applied Mathematics 2013年第1期4卷 183-196页

作者： Somantika Datta Kangyu Ni Prasun Mahanti Svetlana Roudenko Department of Mathematics George Washington University Washington DC USA Department of Mathematics University of Idaho Moscow USA HRL laboratories LLC Malibu USA School of Electrical Computer and Energy Engineering Arizona State University Tempe USA

We explore the stability of image reconstruction algorithms under deterministic compressed sensing. Recently, we have proposed [1-3] deterministic compressed sensing algorithms for 2D images. These algorithms are suitable when Daubechies wavelets are used as the sparsifying basis. In the initial work, we have shown that the algorithms perform well for images with sparse wavelets coefficients. In this work, we address the question of robustness and stability of the algorithms, specifically, if the image is not sparse and/or if noise is present. We show that our algorithms perform very well in the presence of a certain degree of noise. This is especially important for MRI and other real world applications where some level of noise is always present.

关键词： Compressed Sensing Reed-Muller Sequences Chirps Image Reconstruction

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A tabletop X-ray tomography instrument for nanometer-scale imaging: reconstructions

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Microsystems & Nanoengineering 2023年第2期9卷 249-259页

作者： Zachary H.Levine Bradley K.Alpert Amber L Dagel Joseph W.Fowler Edward S.Jimenez Nathan Nakamura Daniel S.Swetz Paul Szypyt Kyle R.Thompson Joel N.Ulom National Institute of Standards and Technology GaithersburgMD 20899USA National Institute of Standards and Technology BoulderCO 80305USA Sandia National laboratories AlbuquerqueNM 87123USA Department of Physics University of ColoradoBoulderCO 80309USA

We show three-dimensional reconstructions of a region of an integrated circuit from a 130 nm copper *** reconstructions employ x-ray computed tomography,measured with a new and innovative high-magnification x-ray *** instrument uses a focused electron beam to generate x-rays in a 100 nm spot and energy-resolving x-ray detectors that minimize backgrounds and hold promise for the identification of materials within the *** x-ray generation target,a layer of platinum,is fabricated on the circuit wafer itself.A region of interest is imaged from a limited range of angles and without physically removing the region from the larger *** reconstruction is consistent with the circuit's design file.

关键词： process removing platinum

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