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Extended Lorenz majorization and frequencies of distances in an undirected network

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Journal of Data and Information Science 2024年第1期9卷 1-10页

作者： leo Egghe Hasselt University Diepenbeek 3590Belgium

Purpose:To contribute to the study of networks and ***/methodology/approach:We apply standard mathematical ***:We show that the distance distribution in an undirected network Lorenz majorizes the one of a *** a consequence,the average and median distances in any such network are smaller than or equal to those of a *** limitations:We restricted our investigations to undirected,unweighted *** implications:We are convinced that these results are useful in the study of small worlds and the so-called six degrees of separation ***/value:To the best of our knowledge our research contains new network results,especially those related to frequencies of distances.

关键词： majorization Lorenz curves networks shortest path distance graphs

Covid-19 vaccination in pregnancy and placental pathology

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Asian pacific Journal of Reproduction 2024年第2期13卷 76-79页

作者： leo Simanjuntak Department of Obstetrics and Gynecology Faculty of MedicineUniversitas HKBP NommensenMedanIndonesia

Objective:To describe and determine the association between Covid-19 vaccination in pregnancy and placental ***:Conducted in a tertiary hospital in Medan,Indonesia,from April 30th 2022 to June 30th 2022,this single-center cross-sectional study involved Covid-19 vaccinated and unvaccinated women with singleton full-term pregnancies delivering live fetuses via cesarean *** characteristics,placental pathologies,and the placental index were documented at *** association between Covid-19 vaccination status and placental pathology was ***:The study enrolled 200 pregnant women,including 110 vaccinated women and 90 unvaccinated *** significant differences were observed in birthweight(P=0.48),placental index(P=0.48),and placental pathology findings[intervillous bleeding(P=0.20),increased syncytial knots(P=0.83),chorangiosis(P=0.13),villous stromal edema(P=0.13),vascular dilation and congestion(P=0.13),and vascular wall thrombus(P=0.71)]between the vaccinated and unvaccinated ***:This study revealed no statistically significant association between Covid-19 vaccination and placental *** findings support the safety of Covid-19 vaccination during pregnancy,in regards to changes of the placental pathology.

关键词： Covid-19 Vaccination Pregnancy Women Placenta

Enhanced Hoek-Brown(H-B)criterion for rocks exposed to chemical corrosion

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International Journal of Mining Science and Technology 2024年第5期34卷 609-630页

作者： Hao Li leo Pel Zhenjiang You David Smeulders Department of Mechanical Engineering Eindhoven University of TechnologyEindhoven 5600 MBthe Netherlands Department of Applied Physics Eindhoven University of TechnologyEindhoven 5600 MBthe Netherlands Center for Sustainable Energy and Resources School of EngineeringEdith Cowan UniversityJoondalupWA 6027Australia School of Chemical Engineering The University of QueenslandBrisbaneQLD 4072Australia Gas and Energy Transition Research Centre The University of QueenslandBrisbaneQLD 4072Australia

Underground constructions often encounter water environments,where water–rock interaction can increase porosity,thereby weakening engineering ***,the failure criterion for chemically corroded rocks becomes essential in the stability analysis and design of such *** study enhances the applicability of the Hoek-Brown(H-B)criterion for engineering structures operating in chemically corrosive conditions by introducing a kinetic porosity-dependent instantaneous mi(KPIM).A multiscale experimental investigation,including nuclear magnetic resonance(NMR),X-ray diffraction(XRD),scanning electron microscopy(SEM),pH and ion chromatography analysis,and triaxial compression tests,is employed to quantify pore structural changes and their linkage with the strength responses of limestone under coupled chemical-mechanical(C-M)*** employing ion chromatography and NMR analysis,along with incorporating the principles of free-face dissolution theory accounting for both congruent and incongruent dissolution,a kinetic chemical corrosion model is *** model aims to calculate the kinetic porosity alterations within rocks exposed to varying H+concentrations and ***,utilizing the generalized mixture rule(GMR),the kinetic porositydependent mi is *** of the KPIM-enhanced H-B criterion using compression test data from 5 types of rocks demonstrated a high level of consistency between the criterion and the experimental results,with a coefficient of determination greater than 0.96,a mean absolute percentage error less than 4.84%,and a root-mean-square deviation less than 5.95 ***,the physical significance of the porosity-dependent instantaneous mi is clarified:it serves as an indicator of a rock’s capacity to leverage the confining pressure effect.

关键词： Hoek-Brown(H-B)criterion Instantaneous mi Kinetic porosity-dependency Chemical corrosion Compressive strength

Removing Splitting/Modeling Error in Projection/Penalty Methods for Navier-Stokes Simulations with Continuous Data Assimilation

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Communications in Mathematical Research 2024年第1期40卷 1-29页

作者： Elizabeth Hawkins leo G.Rebholz Duygu Vargun Department of Mathematical Sciences Clemson UniversityClemsonSC 29634USA

We study continuous data assimilation(CDA)applied to projection and penalty methods for the Navier-Stokes(NS)*** and projection methods are more efficient than consistent Ns discretizations,however are less accurate due to modeling error(penalty)and splitting error(projection).We show analytically and numerically that with measurement data and properly chosen parameters,CDA can effectively remove these splitting and modeling errors and provide long time optimally accurate solutions.

关键词： Navier-Stokes equations projection method penalty method continuous data assimilation

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失而复得

作文 2024年第17期 2-2,1页

作者： leo

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Crystalline cyclic(alkyl)(amino)stannylene via transient stannyne

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Science China Chemistry 2024年

作者： Xinfeng Wang Chaopeng Hu Zhihao Lu Liu leo Liu Department of Chemistry and Research Center for Chemical Biology and Omics Analysis College of Science Southern University of Science and Technology

We demonstrate that a bulky cyclic amino ligand, specifically 1,1,3,3-tetraphenylisoindolinyl, can facilitate the formation of a transient stannyne, endowed with adjacent ambiphilic carbon and tin centers. This stannyne, manifesting carbene-like behavior,engages in an unprecedented sequence of reactions, including Buchner ring expansion, [1,3]sigmatropic, and [1,5]-sigmatropic shifts, culminating in the synthesis of a stable cyclic(alkyl)(amino)stannylene. This compound represents the first tin analogue of the well-known cyclic(alkyl)(amino)carbenes. Both the bonding configuration and the formation process of this stannylene are thoroughly analyzed through quantum chemical computations. Our findings pave the way for further synthesis of unusual main group species using bulky isoindolinyl substituents, emphasizing their potential as a versatile tool in synthetic chemistry.

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女性科研工作者的退出风险与学术成就学术界性别不平等之因

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科学大观园 2024年第6期 30-33页

作者： leo

学术界性别不平等的现象始终存在，也有不少研究对此表示关注，但由于各种原因没能够得出令人满意的结论。黄俊铭博士及其合作者，整合并运用前所未有的大规模数据库，进行了一项题为《不同国家和学科的科学职业中性别不平等的历史比较...

学术界性别不平等的现象始终存在，也有不少研究对此表示关注，但由于各种原因没能够得出令人满意的结论。黄俊铭博士及其合作者，整合并运用前所未有的大规模数据库，进行了一项题为《不同国家和学科的科学职业中性别不平等的历史比较》的研究。本文是对研究报告的详细解析，将从职业生涯、学术能力等不同角度透析学术界性别不平等之因。

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来源：博看期刊

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谁是歹人

作文 2024年第13期 2-2,1页

作者： leo

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机枪登机简史(上)

轻兵器 2024年第6期 50-53页

作者： leo 不详

在军事史上,机枪与飞机的结合彻底改写了战争规则。一战时,飞行员们冒险在云层中战斗,却没有得心应手的武器。随着机枪登上飞机,这两种武器的结合将战争带人全新的维度,并重新定义了空中优势,将人类带入一个全新的时代,战争不再局限于... 详细信息

在军事史上,机枪与飞机的结合彻底改写了战争规则。一战时,飞行员们冒险在云层中战斗,却没有得心应手的武器。随着机枪登上飞机,这两种武器的结合将战争带人全新的维度,并重新定义了空中优势,将人类带入一个全新的时代,战争不再局限于陆地与海洋,还向着天空延伸——。

关键词：机枪军事史空中优势飞行员战争重新定义飞机