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Cofibrant generation of pure monomorphisms

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arXiv 2020年

作者： Lieberman, Michael Positselski, Leonid Rosický, Jiří Vasey, Sebastien Institute of Mathematics Faculty of Mechanical Engineering Brno University of Technology Brno Czech Republic Department of Mathematics and Statistics Faculty of Science Masaryk University Brno Czech Republic Institute of Mathematics of the Czech Academy of Sciences Žitná 25 Prague 1115 67 Czech Republic Laboratory of Algebra and Number Theory Institute for Information Transmission Problems Moscow127051 Russia Department of Mathematics Harvard University CambridgeMA United States

We show that pure monomorphisms are cofibrantly generated—generated from a set of morphisms by pushouts, transfinite composition, and retracts—in any locally finitely presentable additive category. In particular, this is true in any category of R-modules. On the other hand, the classes of all monomorphisms and regular monomorphisms in a locally finitely presentable additive category need not be well-behaved. Copyright © 2020, The Authors. All rights reserved.

关键词： Additives

Computational Methods for Single-Particle Cryo-EM

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arXiv 2020年

作者： Singer, Amit Sigworth, Fred J. Department of Mathematics and Program in Applied and Computational Mathematics Princeton University PrincetonNJ08544 United States Departments of Cellular and Molecular Physiology Biomedical Engineering and Molecular Biophysics and Biochemistry Yale University New HavenCT06520 United States

Single-particle electron cryomicroscopy (cryo-EM) is an increasingly popular technique for elucidating the three-dimensional structure of proteins and other biologically significant complexes at near-atomic resolution. It is an imaging method that does not require crystallization and can capture molecules in their native states. In single-particle cryo-EM, the three-dimensional molecular structure needs to be determined from many noisy two-dimensional tomographic projections of individual molecules, whose orientations and positions are unknown. The high level of noise and the unknown pose parameters are two key elements that make reconstruction a challenging computational problem. Even more challenging is the inference of structural variability and flexible motions when the individual molecules being imaged are in different conformational states. This review discusses computational methods for structure determination by single-particle cryo-EM and their guiding principles from statistical inference, machine learning, and signal processing that also play a significant role in many other data science applications. Copyright © 2020, The Authors. All rights reserved.

关键词： Molecules

Approximate Solution and Analysis of Smoking Epidemic Model with Caputo Fractional Derivatives

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International Journal of Applied and Computational mathematics 2018年第5期4卷 1-16页

作者： Abdullah, M. Ahmad, Aqeel Raza, Nauman Farman, M. Ahmad, M.O. Department of Mathematics University of Engineering and Technology Lahore Pakistan Department of Mathematics and Statistics The University of Lahore Lahore Pakistan Department of Mathematics University of the Punjab Lahore Pakistan

In this paper, an epidemic model is presented to describe the dynamics of drugs usage among the adults. The Caputo fractional derivative operator of order ϕ∈ (0 , 1] is employed to obtain the system of fractional differential equations. Smoking is the large problem in the entire world. Despite the overwhelming facts about smoking, it is still a bad habit which is widely spread and socially accepted. A non-linear mathematical model is established to study and assess the dynamics of smoking and its impact on public health in a community. The analysis of two different states, disease free and endemic which means the disease dies out or persist in a population has been made by presenting sensitivity analysis. The stability of the model is provided by threshold or reproductive number. The Laplace Adomian decomposition method has been employed to solve smoking model which has five compartments, potential smoker P, occasional smokers O, smokers S, temporarily quit smokers Q and permanently quit smokers L. Finally, some numerical results are presented which shows the effect of fractional parameter ϕ on our obtained solutions. © 2018, Springer Nature India Private Limited.

关键词： Endemic equilibrium Epidemic model Fractional order Qualitative analysis Stability analysis

Retraction notice to “Two-stage intelligent planning with improved artificial bee colony algorithm for a microgrid by considering uncertainty of renewable resources” [Energy Rep. 7 (2021) 8912–8928]

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Energy Reports 2024年 12卷 836-836页

作者： Muhammad Hammad Saeed Wang Fangzong Sultan Salem Yousaf Ali Khan Basheer Ahmad Kalwar Ashk Fars Research Centre for Microgrid of New Energy College of Electrical Engineering and New Energy China Three Gorges University 8 Daxue Road Xiling District Yichang Hubei 443002 PR China Department of Economics Birmingham Business School (BBS) University of Birmingham United Kingdom Department of Mathematics and Statistics Hazara University Mansehra 23010 Pakistan Electrical and Electronic Engineering Department Sunlife Company Baku Azerbaijan

At the end of cosmic noon: Short gas depletion times in unobscured quasars at z ∼ 1

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arXiv 2024年

作者： Castillo, M. Frias Rybak, M. Hodge, J. van der Werf, P. Abbo, L.J. Ballieux, F.J. Ward, S. Harrison, C. Rivera, G. Calistro McKean, J.P. Stacey, H.R. Leiden Observatory Leiden University Niels Bohrweg 2 Leiden2333 CA Netherlands THz Sensing Group Department of Microelectronics Faculty of Electrical Engineering Mathematics and Computer Science Mekelweg 4 Delft2628 CD Netherlands European Southern Observatory Karl-Schwarzschild-Straße 2 Garching bei MünchenD-85748 Germany Excellence Cluster ORIGINS Boltzmannstraße 2 Garching bei MünchenD-85748 Germany Ludwig-Maximilian-Universität Professor-Huber-Platz 2 MünchenD-80539 Germany School of Mathematics Statistics and Physics Newcastle University NE1 7RU United Kingdom ASTRON Netherlands Institute for Radio Astronomy Oude Hoogeveensedijk 4 DwingelooNL-7991 PD Netherlands Kapteyn Astronomical Institute University of Groningen P.O. Box 800 Groningen9700AV Netherlands P.O. Box 443 Krugersdorp1740 South Africa Department of Physics University of Pretoria Lynnwood Road Hatfield Pretoria0083 South Africa

Unobscured quasars (QSOs) are predicted to be the final stage in the evolutionary sequence from gas-rich mergers to gas-depleted, quenched galaxies. Studies of this population, however, find a high incidence of far-infrared-luminous sources-suggesting significant dust-obscured star formation-but direct observations of the cold molecular gas fuelling this star formation are still necessary. We present a NOEMA study of CO(2-1) emission, tracing the cold molecular gas, in ten lensed z =1-1.5 unobscured QSOs. We detected CO(2-1) in seven of our targets, four of which also show continuum emission (λrest = 1.3mm). After subtracting the foreground galaxy contribution to the photometry, spectral energy distribution fitting yielded stellar masses of 109−11 M☉, with star formation rates of 25-160 M☉ yr−1 for the host galaxies. These QSOs have lower LCO′ than star-forming galaxies with the same LIR, and show depletion times spanning a large range (50-900 Myr), but with a median of just 90(αCO/4) Myr. We find molecular gas masses in the range ≤2-40 × 109(αCO/4) M☉, which suggest gas fractions above ∼50% for most of the targets. Despite the presence of an unobscured QSO, the host galaxies are able to retain significant amounts of cold gas. However, with a median depletion time of ∼90 Myr, the intense burst of star formation taking place in these targets will quickly deplete their molecular gas reservoirs in the absence of gas replenishment, resulting in a quiescent host galaxy. The non-detected QSOs are three of the four radio-loud QSOs in the sample, and their properties indicate that they are likely already transitioning into quiescence. Recent cosmological simulations tend to overestimate the depletion times expected for these z ∼ 1 QSO-host galaxies, which is likely linked to their difficulty producing starbursts across the general high-redshift galaxy population. Copyright © 2024, The Authors. All rights reserved.

关键词： Gases

Thermo-Mechanical Properties of Digitally-Printed Elastomeric Polyurethane: Experimental Characterization and Constitutive Modelling Using a Nonlinear Temperature-Strain Coupled Scaling Strategy

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SSRN

SSRN 2022年

作者： Yang, Jie Liao, Zisheng Hossain, Mokarram Huang, Guanyu Zhou, Xin Liu, Fan Alzaidi, Ahmed Saad Yao, Xiaohu State Key Laboratory of Subtropical Building Science South China University of Technology Guangzhou510640 China Faculty of Science and Engineering Swansea University SwanseaSA1 8EN United Kingdom Department of Mathematics and Statistics College of Science Taif University P.O. Box 11099 Taif21944 Saudi Arabia South China Advanced Institute for Soft Matter Science and Technology South China University of Technology Guangzhou510640 China

Additive manufacturing (AM) technology has emerged as a novel paradigm that uses the method of gradual accumulation of materials to manufacture solid parts, which is a ``bottom-up'' approach compared to the traditional cutting technology. Among available techniques, Digital Light Synthesis (DLS) further facilitates the opportunity for continuous building instead of the layer-by-layer or the dot-by-dot printing approach, thus curtailing the time of production and encouraging the development of many new materials. In this contribution, temperature-dependent mechanical properties of a Digital Light Synthesis (DLS)-based 3D-printed elastomeric polyurethane (EPU) are investigated utilizing experimental characterization and constitutive modelling. Specifically, uniaxial tensile and relaxation tests under temperature fields ranging from -20$^\circ$C to 60$^\circ$C are performed, which reveal deformation-nonlinearity and temperature-sensitivity of the *** temperature range covers below and above the glass transition region of the polymer. Experimental results show that the temperature-dependence is correlated with temperature field and strain levels simultaneously. Motivated by the experimental results, a phenomenologically-motivated thermodynamically-consistent constitutive model is devised to characterise the finite deformation behaviours of EPU. In this case, for the first time, a single temperature-strain coupling function can capture the thermo-mechanical behaviour across the glass transition. Good accuracy of the prediction can be seen using the proposed constitutive model. This study contributes to the fundamental understanding of the mechanical properties of DLS-based digitally-printed EPU under a wide temperature field. The comprehensive thermo-mechanical experimental characterisation and subsequent constitutive modelling will facilitate the designing of other 3D-printed soft materials. © 2022, The Authors. All rights reserved.

关键词： 3D printers

Real-Time Prediction of Mortality, Cardiac Arrest, and Thromboembolic Complications in Hospitalized Patients With COVID-19

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JACC: Advances

JACC: Advances 2022年第2期1卷 100043-100043页

作者： Shade, Julie K. Doshi, Ashish N. Sung, Eric Popescu, Dan M. Minhas, Anum S. Gilotra, Nisha A. Aronis, Konstantinos N. Hays, Allison G. Trayanova, Natalia A. Department of Biomedical Engineering Johns Hopkins University Baltimore MD United States Alliance for Cardiovascular Diagnostic and Treatment Innovation Johns Hopkins University Baltimore MD United States Division of Pediatric Cardiology Department of Pediatrics Johns Hopkins University School of Medicine Baltimore MD United States Department of Applied Mathematics and Statistics Johns Hopkins University Baltimore MD United States Division of Cardiology Department of Medicine Johns Hopkins University School of Medicine Baltimore MD United States

Background: COVID-19 infection carries significant morbidity and mortality. Current risk prediction for complications in COVID-19 is limited, and existing approaches fail to account for the dynamic course of the disease. Objectives: The purpose of this study was to develop and validate the COVID-HEART predictor, a novel continuously updating risk-prediction technology to forecast adverse events in hospitalized patients with COVID-19. Methods: Retrospective registry data from patients with severe acute respiratory syndrome coronavirus 2 infection admitted to 5 hospitals were used to train COVID-HEART to predict all-cause mortality/cardiac arrest (AM/CA) and imaging-confirmed thromboembolic events (TEs) (n = 2,550 and n = 1,854, respectively). To assess COVID-HEART's performance in the face of rapidly changing clinical treatment guidelines, an additional 1,100 and 796 patients, admitted after the completion of development data collection, were used for testing. Leave-hospital-out validation was performed. Results: Over 20 iterations of temporally divided testing, the mean area under the receiver operating characteristic curve were 0.917 (95% confidence interval [CI]: 0.916-0.919) and 0.757 (95% CI: 0.751-0.763) for prediction of AM/CA and TE, respectively. The interquartile ranges of median early warning times were 14 to 21 hours for AM/CA and 12 to 60 hours for TE. The mean area under the receiver operating characteristic curve for the left-out hospitals were 0.956 (95% CI: 0.936-0.976) and 0.781 (95% CI: 0.642-0.919) for prediction of AM/CA and TE, respectively. Conclusions: The continuously updating, fully interpretable COVID-HEART predictor accurately predicts AM/CA and TE within multiple time windows in hospitalized COVID-19 patients. In its current implementation, the predictor can facilitate practical, meaningful changes in patient triage and resource allocation by providing real-time risk scores for these outcomes. The potential utility of the predictor extend

关键词： big data cardiac arrest machine learning SARS-CoV-2 thromboembolism

Classification of images containing sensitive and non-sensitive information using the convolutional neural network

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AIP Conference Proceedings 2023年第1期2865卷

作者： Yudhi Ardiyanto Kusworo Adi Kurnianingsih Kurnianingsih Adi Wibowo Budi Warsito Doctoral Program of Information System School of Postgraduate Studies Diponegoro University Semarang 50241 Indonesia Department of Electrical Engineering Faculty of Engineering Universitas Muhammadiyah Yogyakarta Bantul 55183 Indonesia Department of Physics Faculty of Science and Mathematics Diponegoro University Semarang 50275 Indonesia Department of Electrical Engineering Politeknik Negeri Semarang Semarang 50275 Indonesia

Currently, social media is used by almost all ages, from pre-teens to the elderly. They use social media to socialize and express their activities by uploading pictures; however, they sometimes do not realize that the images they upload contain sensitive information. They do not carefully analyze the images to be uploaded due to a lack of knowledge, irresponsible acts, or impaired vision. Therefore, we propose a method to classify images with sensitive or non-sensitive content using Convolutional Neural Network (CNN). This research was performed through several steps: image public dataset collection, data pre-processing, model architecture design, model training, and model validation. A randomly selected sample of 2,000 of 5,537 images from the VizWiz-Priv dataset was used to train the classification model. The CNN architecture was compiled using two max-pooling layers and four convolution layers. Finally, the model was trained and validated using images containing sensitive and non-sensitive information. The results revealed that the model accuracy during training and validation achieved 98.75% and 83.30%, respectively.

关键词：

The significance of user-defined identifiers in Java source code authorship identification

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arXiv 2021年

作者： Frantzeskou, Georgia MacDonell, Stephen G. Stamatatos, Efstathios Georgiou, Stelios Gritzalis, Stefanos Dept of Info. and Comm. Systems Engineering University of the Aegean Samos83200 Greece SERL School of Comp. and Math. Sciences Auckland University of Technology Private Bag 92006 Auckland1142 New Zealand Department of Statistics and Actuarial - Financial Mathematics University of the Aegean Samos83200 Greece

When writing source code, programmers have varying levels of freedom when it comes to the creation and use of identifiers. Do they habitually use the same identifiers, names that are different to those used by others? Is it then possible to tell who the author of a piece of code is by examining these identifiers? If so, can we use the presence or absence of identifiers to assist in correctly classifying programs to authors? Is it possible to hide the provenance of programs by identifier renaming? In this study, we assess the importance of three types of identifiers in source code author classification for two different Java program data sets. We do this through a sequence of experiments in which we disguise one type of identifier at a time. These experiments are performed using as a tool the Source Code Author Profiles (SCAP) method. The results show that, although identifiers when examined as a whole do not seem to reflect program authorship for these data sets, when examined separately there is evidence that class names do signal the author of the program. In contrast, simple variables and method names used in Java programs do not appear to reflect program authorship. On the contrary, our analysis suggests that such identifiers are so common as to mask authorship. We believe that these results have applicability in relation to the robustness of code plagiarism analysis and that the underlying methods could be valuable in cases of litigation arising from disputes over program authorship. Copyright © 2021, The Authors. All rights reserved.

关键词： Java programming language