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arXiv 2020年

作者： Flores, Ramón Kahrobaei, Delaram Koberda, Thomas Department of Geometry and Topology University of Seville Spain Department of Computer Science University of York United Kingdom New York University Tandon School of Engineering PhD Program in Computer Science CUNY Graduate Center Department of Mathematics University of Virginia CharlottesvilleVA22904 United States

The purpose of this article is to give a characterization of families of expander graphs via right-angled Artin groups. We prove that a sequence of simplicial graphs {Γi}i∈ forms a family of expander graphs if and only if a certain natural mini-max invariant arising from the cup product in the cohomology rings of the groups {A(Γi)}i∈ agrees with the Cheeger constant of the sequence of graphs, thus allowing us to characterize expander graphs via cohomology. This result is proved in the more general framework of vector space expanders, a novel structure consisting of sequences of vector spaces equipped with vector-space-valued bilinear pairings which satisfy a certain mini-max condition. These objects can be considered to be analogues of expander graphs in the realm of linear algebra, with a dictionary being given by the cup product in cohomology, and in this context represent a different approach to expanders that those developed by Lubotzky-Zelmanov and Bourgain-Yehudayoff. Copyright © 2020, The Authors. All rights reserved.

关键词： Vector spaces

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Performance comparison of InGaN-based 40–80 μm micro-LEDs fabricated with and without plasma etching

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Materials Today Advances 2024年 22卷

作者： Lo, Yu-Yun Chen, Yi-Ho Hsu, Yun-Cheng Lee, Tzu-Yi Hung, Yu-Ying Kao, Yu-Cheng Zan, Hsiao-Wen Wuu, Dong- Sing Kuo, Hao-Chung Samukawa, Seiji Horng, Ray-Hua Institute of Electronics National Yang Ming Chiao Tung University 1001 University Road Hsinchu30010 Taiwan Department of Photonics College of Electrical and Computer Engineering National Yang Ming Chiao Tung University Hsinchu30010 Taiwan Graduate Degree Program of College of Electrical and Computer Engineering National Yang Ming Chiao Tung University Hsinchu30010 Taiwan Department of Materials Science and Engineering National Chung Hsing University Taichung40227 Taiwan Department of Applied Materials and Optoelectronic Engineering National Chi Nan University Nantou54561 Taiwan Semiconductor Research Center Hon Hai Research Institute Taipei11492 Taiwan Institute of Communications Engineering National Yang Ming Chiao Tung University Hsinchu30010 Taiwan

The fabrication of InGaN-based blue 4✕4 array micro-LEDs (μLEDs) with 40 μm ✕40 μm chip size and 2✕2 array μLEDs with 80 μm ✕80 μm chip size etching by the inductive coupled plasma reactive ion etching (ICPRIE) and defect-free neutral beam etching (NBE) processes was studied in this work. In μLEDs of this size, the influence of defects formation in the sidewalls on EQE was evaluated. There was almost no difference in EQE between μLEDs array etched by the NBE process no matter 40 μm ✕40 μm and 80 μm ✕80 μm, but the dependence was observed in the ICPRIE. Even with this size, it was found that the size effect of EQE is smaller than that in case of using ICPRIE for defect-free neutral beam etching. This impact is substantial since μLED predominantly operated at low current density, around 1–5 A/cm2. Consequently, the reduction of defect density, encompassing both internal and sidewall defects, becomes imperative even in 40–80 μm InGaN-based μLEDs. This not only improves the overall efficiency of μLEDs but also fortifies the brightness stability of μLED displays if process etching by NBE. It was also found that the etching shape had an influence on EQE. It could be attributed to fact that the etching profile angle of NBE was more vertical than that of ICPRIE. Because the different angles of the mesa resulted in different light intensity. The μLEDs emitting with a wavelength of 450 nm, the light extraction efficiency and intensity at a mesa angle 58° of NBE etching μLEDs was about 8% lower than those of an angle (38°) of ICPRIE etching μLEDs by simulation. © The Authors

关键词： Light emitting diodes

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Faster Gröbner bases for Lie derivatives of ODE systems via monomial orderings

arXiv

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arXiv 2022年

作者： Bessonov, Mariya Ilmer, Ilia Konstantinova, Tatiana Ovchinnikov, Alexey Pogudin, Gleb Soto, Pedro Department of Mathematics CUNY NYC College of Technology New YorkNY United States Ph.D. Program in Computer Science CUNY Graduate Center New YorkNY United States Department of Mathematics CUNY Queens College New YorkNY United States LIX CNRS École Polytechnique Institute Polytechnique de Paris Paris France

Symbolic computation for systems of differential equations is often computationally expensive. Many practical differential models have a form of polynomial or rational ODE system with specified outputs. A basic symbolic approach to analyze these models is to compute and then symbolically process the polynomial system obtained by sufficiently many Lie derivatives of the output functions with respect to the vector field given by the ODE system. In this paper, we present a method for speeding up Gröbner basis computation for such a class of polynomial systems by using specific monomial ordering, including weights for the variables, coming from the structure of the ODE model. We provide empirical results that show improvement across different symbolic computing frameworks and apply the method to speed up structural identifiability analysis of ODE models. © 2022, CC BY-NC-SA.

关键词： Polynomials

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Dual-Targeting EGCG/NO-Supplying protein assembled nanoparticles with Multi-Synergistic effects against atherosclerosis

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Chemical Engineering Journal 2024年 493卷

作者： Lin, Chi Cheng, Tsai-Mu Liu, Yun-Chun Hsu, Fang-Yu Shih, Chun-Ming Tsai, Min-Lang Shih, Chun-Che Mi, Fwu-Long Graduate Institute of Medical Sciences College of Medicine Taipei Medical University Taipei11031 Taiwan The PhD Program for Translational Medicine College of Medical Science and Technology Taipei Medical University Taipei11031 Taiwan Taipei Heart Institute Taipei Medical University Taipei11031 Taiwan Department of Food Science National Taiwan Ocean University Keelung20224 Taiwan Department of Biochemistry and Molecular Cell Biology School of Medicine College of Medicine Taipei Medical University Taipei11031 Taiwan Division of Cardiology and Cardiovascular Research Center Taipei Medical University Hospital Taipei11031 Taiwan Division of Cardiovascular Surgery Department of Surgery Wan Fang Hospital Taipei Medical University Taipei11031 Taiwan Institute of Clinical Medicine School of Medicine National Yang-Ming Chiao Tung University Taipei Taiwan Department of Surgery School of Medicine College of Medicine Taipei Medical University Taipei11031 Taiwan Graduate Institute of Nanomedicine and Medical Engineering College of Biomedical Engineering Taipei Medical University Taipei11031 Taiwan International Ph.D. Program for Cell Therapy and Regeneration Medicine College of Medicine Taipei Medical University Taipei Taiwan

Limited therapeutic options are available to effectively preventing atherosclerosis. Inflammatory endothelial cells, foamy macrophages, and high protease levels contribute to atherosclerotic plaque formation. Studies have shown that catechins effectively scavenge reactive oxygen species (ROS), inhibit monocyte adhesion and reduce cholesterol levels, while nitric oxide (NO) enhances endothelial function. However, due to the poor stability and bioavailability of catechins and the toxicity from the burst release of current synthetic small molecules NO donor, effective delivery of these bioactive compounds to treat atherosclerosis is still a challenge. Herein, a catechin/protein-based NO donor co-delivery nanosystem was designed for combinatorial anti-atherosclerotic therapy. We engineered a (−)-epigallocatechin-3-gallate (EGCG)/NO-releasing protein co-assembled nanocomplex based on specific catechin-protein interactions. Furthermore, the nanocomplex was surface modified with fucoidan (Fu), a sulfated polysaccharide with anti-inflammatory activity. This nanocomplex exhibits sensitivity to ROS, pH, and enzymes. The Fu-functionalized nanoparticles specifically accumulates in atherosclerotic plaques mediated by P-selectin on inflamed endothelial cells and scavenger receptor A (SR-A) on foamy macrophages. Under environmental stimuli that simulate the condition of plaque, the nanoparticles are readily activated to release EGCG and NO in response to excess ROS and high protease levels, exerting the multi-synergistic anti-atherosclerosic effects on reducing monocyte adhesion, promoting NO production to proliferate endothelial cells, lowering ROS levels, and decreasing the foam cell formation in vitro, and reducing lipid accumulation, plaque size, and inflammatory cytokines release in high-fat diet-induced atherosclerosis model in ApoE−/− mice. The integration of plaques targeting ability and multiple therapeutic functions can provide an advanced therapeutic strategy for athero

关键词： Nitric oxide

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Improved MVDR beamforming using LSTM speech models to clean spatial clustering masks

arXiv

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arXiv 2020年

作者： Ni, Zhaoheng Grezes, Felix Trinh, Viet Anh Mandel, Michael I. Computer Science Program Graduate Center City University of New York United States Computer and Information Science Brooklyn College City University of New York United States

Spatial clustering techniques can achieve significant multichannel noise reduction across relatively arbitrary microphone configurations, but have difficulty incorporating a detailed speech/noise model. In contrast, LSTM neural networks have successfully been trained to recognize speech from noise on single-channel inputs, but have difficulty taking full advantage of the information in multi-channel recordings. This paper integrates these two approaches, training LSTM speech models to clean the masks generated by the Model-based EM Source Separation and Localization (MESSL) spatial clustering method. By doing so, it attains both the spatial separation performance and generality of multi-channel spatial clustering and the signal modeling performance of multiple parallel single-channel LSTM speech enhancers. Our experiments show that when our system is applied to the CHiME-3 dataset of noisy tablet recordings, it increases speech quality as measured by the Perceptual Evaluation of Speech Quality (PESQ) algorithm and reduces the word error rate of the baseline CHiME-3 speech recognizer, as compared to the default BeamformIt beamformer. © 2020, CC BY.

关键词： Cluster analysis

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Homogenization and design of acoustic Willis metasurfaces

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Physical Review B 2021年第5期103卷 054306-054306页

作者： Hussein Esfahlani Yarden Mazor Andrea Alù Photonics Initiative Advanced Science Research Center City University of New York New York New York 10031 USA Kymeta Corporation Redmond Washington 98052 USA Department of Electrical and Computer Engineering The University of Texas at Austin Austin Texas 78712 USA Physics Program Graduate Center of the City University of New York New York New York 10016 USA

Metasurfaces are ultrathin planar arrays of carefully tailored subwavelength particles that enable agile and flexible manipulation of the impinging waves. Originally introduced in optics, their application to acoustic waves has recently opened exciting opportunities for exotic sound control. In conventional acoustic inclusions, the interactions with the impinging pressure and velocity are decoupled, limiting the functionalities that arrays of them can achieve. While the coupling between these two quantities in symmetry-breaking inclusions, known as Willis coupling, has been discussed for several years, only recently has it been realized that these phenomena can become nonperturbative in suitably tailored resonant scatterers. Here, we explore the opportunities that these Willis meta-atoms open in the context of acoustic metasurfaces, offering additional knobs to manipulate and tailor sound. The general response of Willis metasurface is analytically derived, yielding fundamental bounds and optimal surface responses enabling full control of the impinging acoustic wave front.

关键词： Acoustic metamaterials Acoustic wave phenomena Polarizability

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Turing Tumble Is P(SPACE)-Complete 11th

Turing Tumble Is P(SPACE)-Complete

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11th International Conference on Algorithms and Complexity, CIAC 2019

作者： Johnson, Matthew P. Department of Computer Science Lehman College Ph.D. Program in Computer Science The Graduate Center City University of New York New YorkNY United States

ISBN: (纸本)9783030174019

Turing Tumble is a toy gravity-fed mechanical computer (similar to the classic, but including additional types of pieces such as gears), in which marbles roll down a board, along paths determined by the locations of ramps, toggles and gears, which are placed by the "programmer," and by their current states, which are altered by the passing marbles. Aaronson proved that a decision problem (viz., will any marbles reach the sink?) is -Complete, i.e., equivalent to evaluating comparator circuits, and posed the question of what additional functionality would raise the machine’s computational power beyond, speculating that a capability for toggles to affect one another’s states (which gears happen to provide) might suffice. This turns out to be so: we show, though a simple reduction from a variant of the circuit value problem (), that the decision problem is -Complete. The two models also differ in complexity when exponentially (or unboundedly) many marbles are permitted: while remains in, becomes -Complete. © 2019, Springer Nature Switzerland AG.

关键词： Marble

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Monitoring the contribution of development teams in the evolution of technical debt items in software projects 25

Monitoring the contribution of development teams in the evol...

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25th Americas Conference on Information Systems, AMCIS 2019

作者： dos Santos, Sandro L.A.C. Rios, Nicolli Mendonça, Manoel Spínola, Rodrigo O. Graduate Program in Systems and Computer Salvador University Salvador Brazil Department of Computer Science Federal University of Bahia Salvador Brazil Department of Computer Science Federal University of Bahia Fraunhofer Project Center Salvador Brazil Graduate Program in Systems and Computer Salvador University State University of Bahia Salvador Brazil

The adequate monitoring of technical debt (TD) is necessary to increase the chances of success of software projects, which also depend on the effective monitoring of the practitioners involved in their development. Several strategies have been proposed to support TD management. However, the relationship between TD and how much developers contribute to its existence has not yet been investigated. This paper presents a strategy to monitor the contribution of development teams to the TD accumulation in software projects. The proposed strategy was evaluated using the Technology Acceptance Model. The results indicated that the strategy is useful for supporting TD monitoring activities, with 97% of participants indicating that they would use it. In addition, about 76% of respondents agreed that the strategy is user-friendly and allows greater productivity and agility in monitoring the relationship between TD and members of the development team. © 2019 Association for Information Systems. All rights reserved.

关键词： Human resource management

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Improving attention mechanism in graph neural networks via cardinality preservation 29

Improving attention mechanism in graph neural networks via c...

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29th International Joint Conference on Artificial Intelligence, IJCAI 2020

作者： Zhang, Shuo Xie, Lei Ph.D. Program in Computer Science Graduate Center City University of New York United States Department of Computer Science Hunter College City University of New York United States Helen and Robert Appel Alzheimer's Disease Research Institute Feil Family Brain and Mind Research Institute Weill Cornell Medicine Cornell University United States

ISBN: (纸本)9780999241165

Graph Neural Networks (GNNs) are powerful for the representation learning of graph-structured data. Most of the GNNs use a message-passing scheme, where the embedding of a node is iteratively updated by aggregating the information from its neighbors. To achieve a better expressive capability of node influences, attention mechanism has grown to be popular to assign trainable weights to the nodes in aggregation. Though the attention-based GNNs have achieved remarkable results in various tasks, a clear understanding of their discriminative capacities is missing. In this work, we present a theoretical analysis of the representational properties of the GNN that adopts the attention mechanism as an aggregator. Our analysis determines all cases when those attention-based GNNs can always fail to distinguish certain distinct structures. Those cases appear due to the ignorance of cardinality information in attention-based aggregation. To improve the performance of attention-based GNNs, we propose cardinality preserved attention (CPA) models that can be applied to any kind of attention mechanisms. Our experiments on node and graph classification confirm our theoretical analysis and show the competitive performance of our CPA models. The code is available online: https://***/zetayue/CPA. © 2020 Inst. Sci. inf., Univ. Defence in Belgrade. All rights reserved.

关键词： Graph neural networks

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Novel diamond shuttle to deliver flexible neural probe with reduced tissue compression

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Microsystems & Nanoengineering 2020年第1期6卷 903-915页

作者： Kyounghwan Na Zachariah J.Sperry Jiaao Lu Mihaly Voroslakos Saman S.Parizi Tim M.Bruns Euisik Yoon John P.Seymour Electrical Engineering&Computer Science Department University of MichiganAnn ArborMI 48105USA Biomedical Engineering Department University of MichiganAnn ArborMI 48105USA Biointerfaces Institute University of MichiganAnn ArborMI 48105USA The Neuroscience Institute New York UniversityNew YorkNY 10016USA Center for Nanomedicine Institute for Basic Science(IBS)Seoul 03722Korea Graduate Program of Nano Biomedical Engineering(Nano BME) Yonsei-IBS InstituteYonsei UniversitySeoul 03722Korea Vivian L Smith Department of Neurosurgery University of Texas Health Science CenterHoustonTX 77030USA Department of Electrical and Computer Engineering Rice UniversityHoustonTX 77005USA

The ability to deliver flexible biosensors through the toughest membranes of the central and peripheral nervous system is an important challenge in neuroscience and neural *** devices implanted through dura mater and thick epineurium would ideally create minimal compression and acute damage as they reach the neurons of *** demonstrate that a three-dimensional diamond shuttle can be easily made with a vertical support to deliver ultra-compliant polymer microelectrodes(4.5-µm thick)through dura mater and thick *** diamond shuttle has 54%less cross-sectional area than an equivalently stiff silicon shuttle,which we simulated will result in a 37%reduction in blood vessel *** also discovered that higher frequency oscillation of the shuttle(200Hz)significantly reduced tissue compression regardless of the insertion speed,while slow speeds also independently reduced tissue *** and recording performance are demonstrated in rat and feline models,but the large design space of these tools are suitable for research in a variety of animal models and nervous system targets.

关键词： sectional neural thick

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