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Acta Mathematica Sinica,English Series 2007年第12期23卷 2205-2212页

作者： Juan J.NIETO RosanaRODRGUEZ-LPEZ departamento de Análisis matemático Facultad de MatemáticasUniversidad de Santiago de Compostela

We prove some fixed point theorems in partially ordered sets, providing an extension of the Banach contractive mapping theorem. Having studied previously the nondecreasing case, we consider in this paper nonincreasing mappings as well as non monotone mappings. We also present some applications to first-order ordinary differential equations with periodic boundary conditions, proving the existence of a unique solution admitting the existence of a lower solution.

关键词： fixed point partially ordered set first-order differential equation lower and upper solutions

EXISTENCE OF SOLUTIONS OF nTH-ORdeR NONLINEAR DIFFERENCE EQUATIONS WITH GENERAL BOUNDARY CONDITIONS

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Acta Mathematica Scientia 2020年第1期40卷 226-236页

作者： Alberto CABADA Nikolay DIMITROV departamento de Estatística Análise Matemática e OptimizaciónInstituto de MatemáticasFacultade de MatemáticasUniversidade de Santiago de CompostelaSantiago de CompostelaGaliciaSpain depatment of Mathematics University of RuseRuse 7000Bulgaria

The aim of this paper is to prove the existence of one or multiple solutions of nonlinear difference equations coupled to a general set of boundary conditions.Before to do this,we construct a discrete operator whose fixed points coincide with the solutions of the problem we are looking for.Moreover,we introduce a strong positiveness condition on the related Green's function that allows us to construct suitable cones where to apply adequate fixed point theorems.Once we have the general existence result,we deduce,as a particular case,the existence of solutions of a second order difference equation with nonlocal perturbed Dirichlet conditions.

关键词： difference equation multiplicity of solutions Green's function positive solutions parameter dependence

Characterizations of VMO and CMO Spaces in the Bessel Setting

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Acta Mathematica Sinica,English Series 2023年

作者： Qing Dong GUO Jorge J.BETANCOR Dong Yong YANG School of Mathematical Sciences Xiamen University departamento de Anáisis matemáico Universidad de La Laguna Campus de Anchieta

Let λ > 0 and ?λ:=-d2d/dx2-2λ/xd/dx be the Bessel operator on R+:=(0, ∞). In this paper, the authors introduce and characterize the space VMO(R+, dmλ) in terms of the Hankel translation, the Hankel convolution and a John-Nirenberg inequality, and obtain a sufficient condition of Fefferman-Stein type for functions f ∈ VMO(R+, dmλ) using R?λ, the adjoint of the Riesz transform R?λ. Furthermore, we obtain the characterization of CMO(R+, dmλ) in terms of the John-Nirenberg inequality which is new even for the classical CMO(Rn) and a sufficient condition of Fefferman-Stein type for functions f ∈ CMO(R+, dmλ).

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Effects of fire history on animal communities:a systematic review

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Ecological Processes 2022年第1期11卷 248-258页

作者： Tania Marisol González Juan David González‑Trujillo Alberto Muñoz Dolors Armenteras Laboratorio de Ecología del Paisaje y Modelación de Ecosistemas ECOL‑MOD Departamento de BiologíaFacultad de CienciasUniversidad Nacional de ColombiaEdificio 421111321 BogotáColombia departamento de Biología Facultad de CienciasUniversidad Nacional de ColombiaEdificio 421111321 BogotáColombia departamento de Didáctica de Ciencias Experimentales Sociales y MatemáticasFacultad de EducaciónUniversidad Complutense de Madrid28040 MadridSpain CREAF 08193 Cerdanyola del VallèsCataloniaSpain

Fire is a natural agent with a paramount role in ecosystem functioning and biodiversity maintenance.Still,it can also act as a negative force against many ecosystems.despite some knowledge of the interactions of fire and vegetation,there is no clear understanding of how different components of fire regimes(i.e.,severity,history,or frequency)influence known patterns of animal communities.Therefore,we performed a systematic review on the global responses of arthropods,birds,mammals,reptiles,and amphibians to different fire regimes.Specifically,we focused on assessing how fire severity,history,and frequency modulate the effect of fire on the richness and abundance of faunal communities.We conducted a systematic review of 566 papers retrieved from the Scopus database.We also scrutinized all the documents included in the meta‑analysis of Pastro et al.(Pastro et al.Glob Ecol Biogeogr 23:1146–1156,2014).Our selection criteria excluded studies without data on species richness or abundance.We also excluded studies without adequate controls and those without information about the fire regime of the study zone.After careful examination,we used data from 162 studies to perform a quantitative meta‑analysis.From the 162 studies meeting our selection criteria,nearly 60%of the studies are from North America,25%from Australia,11%from Europe,and 4%from the tropics.According to the ecological role of fire,90%of the studies were carried out in fire‑dependent ecosystems(i.e.,conifer forests,natural savannas,pastures).Finally,40%of the studies analyzed birds,22%mammals,and 20%arthropods.The meta‑analysis of the available evidence indicates that fire history is an important modulator of animal richness and abundance.Whether negative or positive,animal responses depended on the time since the last fire event.Considering that short‑term studies may not capture such a long‑term effect on fauna,this translates to more challenges at implementing fire management strategies.Whether or not we can anticipate the impact of the fire will then dep

关键词： Amphibians Arthropods Birds Fire regime components Mammals Reptiles

Variation of Parameters Formula and Gronwall Inequality for Differential Equations with a General Piecewise Constant Argument

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Acta Mathematicae Applicatae Sinica 2011年第4期27卷 561-568页

作者： Kuo-Shou CHIU Manuel PINTO departamento de matemótica Facultad de Ciencias BósicasUniversidad Metropolitana de Ciencias de la EducacinJ.P.Alessandri 774SantiagoChile departamento de matemóticas Facultad de CienciasUniversidad de ChileCasilla 653SantiagoChile

A variation of parameters formula and Gronwall type integral inequality are proved for a differential equation involving general piecewise alternately advanced and retarded argument.

关键词： variation of parameters formula Gronwall integral inequality alternately advanced and retarded argument

A Note on Extreme Points in Dual Spaces

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Acta Mathematica Sinica,English Series 2013年第3期29卷 471-476页

作者： Juan Francisco MENA-JURADO Juan Carlos NAVARRO-PASCUAL departamento de Análisis matemático Facultad de Ciencias Universidad de Granada departamento de lgebra y Análisis matemático Universidad de Almería

Given a normed space X it can be easily proven that every extreme point in Bx＊, the unit ball of X＊, is the restriction of an extreme point in Bx Our purpose is to study when the restrictions of extreme points in B... 详细信息

关键词： Extreme point Ll-predual M-ideal

Sharp Interpolation Inequalities on the Sphere:New Methods and Consequences

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Chinese Annals of Mathematics,Series B 2013年第1期34卷 99-112页

作者： Jean DOLBEAULT Maria J. ESTEBAN Michal KOWALCZYK Michael LOSS Ceremade Université Paris DauphinePlace de Lattre de Tassigny departamento de Ingeniería matemática and Centro de Modelamiento matemático (UMI 2807 CNRS) Universidad de Chile Skiles Building Georgia Institute of Technology

This paper is devoted to various considerations on a family of sharp interpolation inequalities on the sphere, which in dimension greater than 1 interpolate between Poincaré, logarithmic Sobolev and critical Sobolev (Onofri in dimension two) inequalities. The connection between optimal constants and spectral properties of the Laplace-Beltrami operator on the sphere is emphasized. The authors address a series of related observations and give proofs based on symmetrization and the ultraspherical setting.

关键词：插值球体 Sobolev 不等式夏普光谱特性最佳常数庞加莱

Maximum mass of magnetic white dwarfs

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Research in Astronomy and Astrophysics 2015年第10期15卷 1735-1741页

作者： Daryel Manreza Paret Jorge Ernesto Horvath Aurora Pérez Martínez departamento de Fisica General Facultad de FísicaUniversidad de la Habana Instituto de Astronomia Geofisica e Ciencias Atmosfericas USP Instituto de Cibernética Matemática y Física(ICIMAF)

We revisit the problem of the maximum masses of magnetized white dwarfs （WDs）. The impact of a strong magnetic field on the structure equations is addressed. The pressures become anisotropic due to the presence of the magnetic field and split into parallel and perpendicular components. We first construct stable solutions of the Tolman-Oppenheimer-Volkoff equations for parallel pressures and find that physical solutions vanish for the perpendicular pressure whenB ≥ 10^13 G. This fact estab- lishes an upper bound for a magnetic field and the stability of the configurations in the （quasi） spherical approximation. Our findings also indicate that it is not possible to obtain stable magnetized WDs with super-Chandrasekhar masses because the val- ues of the magnetic field needed for them are higher than this bound. To proceed into the anisotropic regime, we can apply results for structure equations appropriate for a cylindrical metric with anisotropic pressures that were derived in our previous work. From the solutions of the structure equations in cylindrical symmetry we have con- firmed the same bound for B- 10^13 G, since beyond this value no physical solutions are possible. Our tentative conclusion is that massive WDs with masses well beyond the Chandrasekhar limit do not constitute stable solutions and should not exist.

关键词： magnetic fields -- white dwarfs -- equation of state

On Integrable Roots in Split Lie Triple Systems

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Acta Mathematica Sinica,English Series 2009年第11期25卷 1759-1774页

作者： A.J.CALdeRóN MARTíN departamento de matemáticas Universidad de Cádiz

We focus on the notion of an integrable root in the framework of split Lie triple systems T with a coherent 0-root space. As a main result, it is shown that if T has all its nonzero roots integrable, then its standard embedding is a split Lie algebra having all its nonzero roots integrable. As a consequence, a local finiteness theorem for split Lie triple systems, saying that whenever all nonzero roots of T are integrable then T is locally finite, is stated. Finally, a classification theorem for split simple Lie triple systems having all its nonzero roots integrable is given.

关键词： Lie triple system root split Lie algebra classification theory

A Remark about the Orlicz-Pettis Theorem and the Statistical Convergence

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Acta Mathematica Sinica,English Series 2010年第2期26卷 305-310页

作者： A.AIZPURU M.NICASIO-LLACH F.RAMBLA-BARRENO departamento de matemticas Universidad de Cdiz

In this paper we obtain a new version of the Orlicz-Pettis theorem by using statistical convergence. To obtain this result we prove a theorem of uniform convergence on matrices related to the statistical convergence.

关键词： statistical convergence summability Orlicz-Pettis theorem