检索结果-内蒙古大学图书馆

Social insects and beyond: The physics of soft, dense invertebrate aggregations

学校读者我要写书评

暂无评论

Collective Intelligence 2022年第2期1卷

作者： Olga Shishkov Orit Peleg BioFrontiers Institute University of Colorado Boulder Boulder CO USA Department of Computer Science University of Colorado Boulder Boulder CO USA Department of Physics University of Colorado Boulder Boulder CO USA Department of Applied Math University of Colorado Boulder Boulder CO USA Department of Ecology and Evolutionary Biology University of Colorado Boulder Boulder CO USA Santa Fe Institute Santa Fe NM USA

Aggregation is a common behavior by which groups of organisms arrange into cohesive groups. Whether suspended in the air (like honey bee clusters), built on the ground (such as army ant bridges), or immersed in water (such as sludge worm blobs), these collectives serve a multitude of biological functions, from protection against predation to the ability to maintain a relatively desirable local environment despite a variable ambient environment. In this review, we survey dense aggregations of a variety of insects, other arthropods, and worms from a soft matter standpoint. An aggregation can be orders of magnitude larger than its individual organisms, consisting of tens to hundreds of thousands of individuals, and yet functions as a coherent entity. Understanding how aggregating organisms coordinate with one another to form a superorganism requires an interdisciplinary approach. We discuss how considering the physics of an aggregation can yield additional insights to those gained from ecological and physiological considerations, given that the aggregating individuals exchange information, energy, and matter continually with the environment and one another. While the connection between animal aggregations and the physics of non-living materials has been proposed since the early 1900s, the recent advent of physics of behavior studies provides new insights into social interactions governed by physical principles. Current efforts focus on eusocial insects; however, we show that these may just be the tip of an iceberg of superorganisms that take advantage of physical interactions and simple behavioral rules to adapt to changing environments. By bringing attention to a wide range of invertebrate aggregations, we wish to inspire a new generation of scientists to explore collective dynamics and bring a deeper understanding of the physics of dense living aggregations.

关键词： Collective behavior aggregation invertebrates soft matter survey

Optimization of checkpointing/recovery strategy in cloud computing with adaptive storage management

学校读者我要写书评

暂无评论

Optimization of checkpointing/recovery strategy in cloud com...

作者： Meroufel, Bakhta Belalem, Ghalem Department of Math and Computer Science Faculty of Exact Sciences and Computer Science University of Abdelhamid Ibn Badis of Mostaganem Mostaganem Algeria Department of Computer Science Faculty of Exact and Applied Sciences University of Oran1 Ahmed Ben Bella Oran Algeria

Cloud Computing is a type of distributed system that is usually based on the services offered to the user based on SLA contract. In this case, the implementation of a fault-tolerant system that ensures the reliability and the services continuity becomes a major requirement. In this paper, we propose a fault tolerance strategy based on checkpointing and replication. Our approach uses a smart checkpoint infrastructure for cloud computing tasks. The checkpoints are stored in alternative already paid VMs. This allows resuming a task execution faster and cheaper after a node crash. Since checkpoints are distributed and replicated, our approach increases also the system reliability. The experimental results show the effectiveness of the proposed strategy in term of energy consumption, SLA (System Level Aggregation) violation, and reliability. © 2018 John Wiley & Sons, Ltd.

关键词： Cloud computing

Crouzeix’s Conjecture and Related Problems

学校读者我要写书评

暂无评论

arXiv 2020年

作者： Bickel, Kelly Gorkin, Pamela Greenbaum, Anne Ransford, Thomas Schwenninger, Felix Wegert, Elias Department of Mathematics Bucknell University LewisburgPA17837 United States Department of Mathematics Bucknell University LewisburgPA17837 United States Department of Applied Mathematics University of Washington Département de mathématiques et de statistique Université Laval QuébecQCG1V 0A6 Canada Department of Mathematics Universität Hamburg Department of Applied Mathematics University of Twente Netherlands Department of Mathematics and Computer Science Technische Universität Bergakademie Freiberg Division of Mathematical Sciences National Science Foundation United States NSERC and the Canada Research Chairs program

In this paper, we establish several results related to Crouzeixs conjecture. We show that the conjecture holds for contractions with eigenvalues that are sufficiently well-separated. This separation is measured by the so-called separation constant, which is defined in terms of the pseudohyperbolic metric. Moreover, we study general properties of related extremal functions and associated vectors. Throughout, compressions of the shift serve as illustrating examples which also allow for refined *** Codes 47A25, 47A12, 15A60, 47A20, 30J10 Copyright © 2020, The Authors. All rights reserved.

关键词： Eigenvalues and eigenfunctions

Simultaneous dimensionality and complexity model selection for spectral graph clustering

学校读者我要写书评

暂无评论

arXiv 2019年

作者： Yang, Congyuan Priebe, Carey E. Park, Youngser Marchette, David J. Department of Electrical and Computer Engineering Johns Hopkins University Department of Applied Math and Statistics Johns Hopkins University Center for Imaging Science Johns Hopkins University Applied Mathematics and Data Analytics Group Naval Surface Warfare Center Dahlgren Division

Our problem of interest is to cluster vertices of a graph by identifying underlying community structure. Among various vertex clustering approaches, spectral clustering is one of the most popular methods because it is easy to implement while often outperforming more traditional clustering algorithms. However, there are two inherent model selection problems in spectral clustering, namely estimating both the embedding dimension and number of clusters. This paper attempts to address the issue by establishing a novel model selection framework specifically for vertex clustering on graphs under a stochastic block model. The first contribution is a probabilistic model which approximates the distribution of the extended spectral embedding of a graph. The model is constructed based on a theoretical result of asymptotic normality of the informative part of the embedding, and on a simulation result providing a conjecture for the limiting behavior of the redundant part of the embedding. The second contribution is a simultaneous model selection framework. In contrast with the traditional approaches, our model selection procedure estimates embedding dimension and number of clusters simultaneously. Based on our conjectured distributional model, a theorem on the consistency of the estimates of model parameters is stated and proven. The theorem provides statistical support for the validity of our method. Heuristic algorithms via the simultaneous model selection framework for vertex clustering are proposed, with good performance shown in the experiment on synthetic data and on the real application of connectome analysis. Copyright © 2019, The Authors. All rights reserved.

关键词： Embeddings

HIV and COVID-19 co-infection: A mathematical model and optimal control

学校读者我要写书评

暂无评论

Informatics in Medicine Unlocked 2022年 31卷 100978页

作者： Ringa, N. Diagne, M.L. Rwezaura, H. Omame, A. Tchoumi, S.Y. Tchuenche, J.M. Data and Analytic Services British Columbia Centre for Disease Control 655 W 12th Ave Vancouver BC V5Z 4R4 Canada School of Population and Public Health University of British Columbia 2329 West Mall Vancouver BC V6T 1Z4 Canada Département de Mathématiques UFR des Sciences et Technologies Université de Thiès Thiès BP 967 Senegal Mathematics Department University of Dar es Salaam P.O. Box 35062 Dar es Salaam Tanzania Department of Mathematics Federal University of Technology Owerri Nigeria Abdus Salam School of Mathematical Sciences Government College University Lahore Pakistan Department of Mathematics and Computer Sciences ENSAI University of Ngaoundéré P.O. Box 455 Ngaoundéré Cameroon School of Computer Science and Applied Mathematics University of the Witwatersrand Private Bag 3 Wits 2050 Johannesburg South Africa School of Computational and Communication Sciences and Engineering Nelson Mandela African Institution of Science and Technology P.O. Box 447 Arusha Tanzania

A new mathematical model for COVID-19 and HIV/AIDS is considered to assess the impact of COVID-19 on HIV dynamics and vice-versa. Investigating the epidemiologic synergy between COVID-19 and HIV is important. The dynamics of the full model is driven by that of its sub-models;therefore, basic analysis of the two sub-models;HIV-only and COVID-19 only is carried out. The basic reproduction number is computed and used to prove local and global asymptotic stability of the sub-models’ disease-free and endemic equilibria. Using the fmincon function in the Optimization Toolbox of MATLAB, the model is fitted to real COVID-19 data set from South Africa. The impact of intervention measures, namely, COVID-19 and HIV prevention interventions and COVID-19 treatment are incorporated into the model using time-dependent controls. It is observed that HIV prevention measures can significantly reduce the burden of co-infections with COVID-19, while effective treatment of COVID-19 could reduce co-infections with opportunistic infections such as HIV/AIDS. In particular, the COVID-19 only prevention strategy averted about 10,500 new co-infection cases, with similar number also averted by the HIV-only prevention control. © 2022 The Author(s)

关键词： Basic reproduction number Co-infection COVID-19 HIV Optimal control

Bresse-Timoshenko type systems with thermodiffusion effects: Well-possedness, stability and numerical results

学校读者我要写书评

暂无评论

arXiv 2020年

作者： Elhindi, Mohammad Zennir, Khaled Ouchenane, Djamel Choucha, Abdelbaki Arwadi, Toufic E.L. Department of Mathematics and Computer Science Faculty of Science Beirut Arab University Beirut Lebanon Department of Mathematics College of Sciences and Arts Qassim University Ar-Rass Saudi Arabia Laboratoire de Mathématiques Appliquées et de Modélisation Université 8 Mai 1945 Guelma. B.P. 401 Guelma24000 Algeria Laboratory of pure and applied mathematic Laghouat University Algeria Department of Mathematics Faculty of Exact Sciences University of El Oued B.P. 789 El Oued39000 Algeria

Bresse-Timoshenko beam model with thermal, mass diffusion and theormoelastic effects is studied. We state and prove the well-posedness of problem. The global existence and uniqueness of the solution is proved by using the classical Faedo-Galerkin approximations along with two a priori estimates. We prove an exponential stability estimate for problem under an unusual assumption, and by using a multiplier technique in two different cases, with frictional damping in the angular rotation and with frictional damping in the vertical displacement. In numerical parts, we first obtained a numerical scheme for problem by P1-finite element method for space discretization and implicit Euler scheme for time discretization. Then, we showed that the discrete energy decays, later a priori error estimates are established. Finally, some numerical simulations are presented. Copyright © 2020, The Authors. All rights reserved.

关键词： Damping

Learning models from data with measurement error: Tackling underreporting

学校读者我要写书评

暂无评论

arXiv 2019年

作者： Adams, Roy Ji, Yuelong Wang, Xiaobin Saria, Suchi Department of Computer Science Johns Hopkins University Center on the Life Origins of Disease Department of Population Family and Reporductive Health Johns Hopkins University Bloomberg School of Public Health Department of Applied Math and Statistics Johns Hopkins University Bayesian Health.

Measurement error in observational datasets can lead to systematic bias in inferences based on these datasets. As studies based on observational data are increasingly used to inform decisions with real-world impact, it is critical that we develop a robust set of techniques for analyzing and adjusting for these biases. In this paper we present a method for estimating the distribution of an outcome given a binary exposure that is subject to underreporting. Our method is based on a missing data view of the measurement error problem, where the true exposure is treated as a latent variable that is marginalized out of a joint model. We prove three different conditions under which the outcome distribution can still be identified from data containing only error-prone observations of the exposure. We demonstrate this method on synthetic data and analyze its sensitivity to near violations of the identifiability conditions. Finally, we use this method to estimate the effects of maternal smoking and opioid use during pregnancy on childhood obesity, two import problems from public health. Using the proposed method, we estimate these effects using only subject-reported drug use data and substantially refine the range of estimates generated by a sensitivity analysis-based approach. Further, the estimates produced by our method are consistent with existing literature on both the effects of maternal smoking and the rate at which subjects underreport smoking. Copyright © 2019, The Authors. All rights reserved.

关键词： Measurement errors

Knot mosaic tabulation

学校读者我要写书评

暂无评论

Involve 2018年第1期11卷 13-26页

作者： Lee, Hwa Jeong Ludwig, Lewis D. Paat, Joseph Peiffer, Amanda School of Undergraduate Studies College of Transdisciplinary Studies Daegu Gyeongbuk Institute of Science and Technology Daegu 42988 South Korea Department of Mathematics and Computer Science Denison University 100 West College Granville 43023 OH United States Department of Applied Mathematics and Statistics Johns Hopkins 211-E Whitehead Hall 3400 N. Charles St. Baltimore 21218-2682 MD United States Department of Math and Computer Science Denison University Granville 43020 OH United States

In 2008, Lomonaco and Kauffman introduced a knot mosaic system to define a quantum knot system. A quantum knot is used to describe a physical quantum system such as the topology or status of vortexing that occurs in liquid helium II for example. Kuriya and Shehab proved that knot mosaic type is a complete invariant of tame knots. In this article, we consider the mosaic number of a knot, which is a natural and fundamental knot invariant defined in the knot mosaic system. We determine the mosaic number for all eight-crossing or fewer prime knots. This work is written at an introductory level to encourage other undergraduates to understand and explore this topic. No prior knowledge of knot theory is assumed or required. © 2018, mathematical sciences Publishers. All rights reserved.

关键词： crossing number knot mosaic knots mosaic number

An empirical study on the knowledge management practice in software testing 21

学校读者我要写书评

暂无评论

An empirical study on the knowledge management practice in s...

21st Ibero-American Conference on Software Engineering, CIbSE 2018

作者： Maciel, Claudia P.C. De Souza, Erica Ferreira Vijaykumar, Nandamudi L. De Almeida Falbo, Ricardo Meinerz, Giovani Volnei Felizardo, Katia Romero Department of Computer Federal Technological University of Paraná/UTFPR Cornelio Procópio/PR Brazil Lab. of Comp and Applied Math. National Institute for Space Research INPE Sao José dos Campos/SP Brazil Department of Computer Science Federal University of Espirito Santo UFES Vitória/ES Brazil

ISBN: (纸本)9789584837547

Context: Software testing is a knowledge intensive process, and therefore can benefit from the use of experience gained from past projects. In this context, principles of Knowledge Management (KM) can be applied to promote knowledge capture and sharing as well as the emergence of new knowledge. In spite of this, there are only few studies that present practitioners' perspective about KM initiatives in software testing. Objective: The main goal of this study is to identify the perception of professionals in software testing on the use of KM initiatives in software engineering companies, such as KM adoption, potential benefits or hindrances. Method: A survey was conducted in software development companies. In addition, the survey results were compared with another survey conducted previously in the same context, however, with different objectives and target audience. 39 software companies participated in this research. Results: Testing planning activity and the test case reuse are the aspects that have received more attention by companies. A strategic planning and reuse of existing test cases have a potential to significantly reduce software development costs and time. Conclusion: Applying KM in software companies can bring several benefits in terms of quality of results, reduction costs, time and effort. However, it is still a challenge to be faced and tackled. © 2018 Conferencia Iberoamericana de Software Engineering - CIbSE. All Rights Reserved.

关键词： Software testing