305,720 research outputs found
Bifurcation of Poincaré-Andronov-Hopf to diffeomorphism in the plane
No full textO objetivo principal deste trabalho é apresentar uma exposição detalhada do Teorema de Poincaré-Andronov-Hopf para uma família de transformações do plano. Apresentaremos também uma aplicação a um sistema dinâmico que modela a evolução do preço e excesso de demanda em um mercado constituído por uma única mercadoria.The main purpose of this work is to present a detailed exposition of the Poincaré-Andronov-Hopf Theorem for a family of transformations in the plane. We also present an application to a dynamical system modelling the evolution of the price and the excess demand in a single asset market
Евгений Дмитриевич Поливанов: Абхазский Аналитический Алфавит. Издание текста с переводом на английский язык
No full textThe present paper features the publication of an unedited manuscript by the Soviet linguist E.D. Polivanov, submitted in November 1927 by its author not for publication but just as a contribu- tion to the discussion around the so-called Abkhaz Analytical Alphabet. is graphic system was devised by the academician Nikolay Yakovlevich Marr on the basis of the Latin alphabet for the representation of all Japhetic (Caucasian) languages. In the rst section of the introduction, the main characteristics of Marr’s Analytical Alphabet are presented; the second section addresses the linguistic discussion that followed its introduction in Abkhazia as the o cial alphabet in 1926 and its replacement two years later by a Latin-based alphabet. e third section gives comment on some questions of Abkhaz phonetics and transcription; the fourth is devoted to textual and editorial is- sues. e edition of the Russian text is accompanied by an English translation, prepared by Grazia Giannetta (Macerata)
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The smallest bimolecular mass-action system with a vertical Andronov–Hopf bifurcation
No full textWe present a three-dimensional differential equation, which robustly displays a degenerate Andronov–Hopf bifurcation of infinite codimension, leading to a center, i.e., an invariant two-dimensional surface that is filled with periodic orbits surrounding an equilibrium. The system arises from a three-species bimolecular chemical reaction network consisting of four reactions. In fact, it is, up to a natural equivalence, the only such mass-action system that admits a center via an Andronov–Hopf bifurcation
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
The smallest bimolecular mass-action system with a vertical Andronov-Hopf bifurcation
No full textWe present a three-dimensional differential equation, which robustly displays
a degenerate Andronov-Hopf bifurcation of infinite codimension, leading to a
center, i.e., an invariant two-dimensional surface that is filled with periodic
orbits surrounding an equilibrium. The system arises from a three-species
bimolecular chemical reaction network consisting of four reactions. In fact, it
is the only such mass-action system that admits a center via an Andronov-Hopf
bifurcation
Untersuchungen der bakteriellen Diversität mittels Oligonukleotid-Microarrays
No full textSharypova LA, Andronov E, Krol EE, Saal B, Wegener C, Becker A. Untersuchungen der bakteriellen Diversität mittels Oligonukleotid-Microarrays. BIOspektrum. 2006;(1):106-107
Author, publisher and bookseller : a tripartite synergy in Nigerian book industry
No full textThis work is about the roles of Author, Publisher and Bookseller in Book development in
Nigeria. The paper started by delving into the history of Book Publishing in Nigeria after
which it proceeded by defining who an author, a publisher, and a bookseller is and
expatiated on the indispensable roles of these key actors in Nigerian Book Industry and in
the emerging Information Society. Furthermore, the various constraints to book
development were identified while the paper advised on how the Book Industry can be
further promoted in Nigeria. However, the paper concluded and made recommendations
on how the Book sector can help in enhancing scholarship in the country
Bifurcação de Andronov-Hopf em um modelo de Liénard para as pregas vocais
No full textDissertação (mestrado)—Universidade de Brasília, Instituto de Ciências Exatas, Departamento de Matemática, Brasília, 2006.Texto parcialmente liberado pelo autor.Os fenômenos oscilatórios da natureza podem ser estudados por modelos matemáticos. Neste trabalho estudamos a dinâmica de um oscilador do tipo Liénard, que modela o comportamento das pregas vocais durante a fonação utilizando a teoria qualitativa das equações diferenciais. Estudamos o número de Lyapunov e a bifurcação de Andronov-Hopf para o caso bidimensional sobre a geração de um ciclo limite quando variamos uma parâmetro do sistema. Verificamos que a oscilação é produzida com valores fisiológicos realistas para os parâmetros. Ela é gerada através de uma bifurcação de Andronov-Hopf, a qual pode assumir as formas supercrítica e subcrítica. Ilustramos os resultados encontrados fazendo uma análise numérica com retratos de fase e diagramas de bifurcação. __________________________________________________________________________________________ ABSTRACTOscillatory phenomena in nature may be studied by mathematical models. In this work, we explore the dynamics of an oscillator of the Lienard type, which models the behavior of the vocal folds at phonation, using the qualitative theory of differential equations. We study the Lyapunov number and the Andronov-Hopf bifurcation for the bidimensional case, about the generation of a limit cycle when a systems parameter is varied. We verify that the oscillation is produced with realistic physiological values for the parameters. It is generated through an Andronov-Hopf bifurcation, which can assume supercritical and subcritical forms. We illustrate the results by a numerical analysis with phase portraits and bifurcation diagrams.Instituto de Ciências Exatas (IE)Departamento de Matemática (IE MAT)Programa de Pós-Graduação em Matemátic
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