1,354,245 research outputs found
Cyclotomic and abelian points in backward orbits of rational functions
No full textWe prove several results on backward orbits of rational functions over number
fields. First, we show that if is a number field, and
then the extension of generated by the abelian points in the
backward orbit of is ramified only at finitely many primes. This has
the immediate strong consequence that if all points in the backward orbit of
are abelian then is post-critically finite. We use this result
to prove two facts: on the one hand, if is a quadratic
rational function not conjugate over to a power or a
Chebyshev map and all preimages of are abelian, we show that is
-conjugate to one of two specific quadratic functions, in the spirit
of a recent conjecture of Andrews and Petsche. On the other hand we provide
conditions on a quadratic rational function in for the backward orbit of
a point to only contain finitely many cyclotomic preimages, extending
previous results of the second author. Finally, we give necessary and
sufficient conditions for a triple , where is a
Latt\`es map over a number field and for the whole backward
orbit of to only contain abelian points
On multiplicative dependence of values of rational functions and a generalization of the Northcott theorem
No full textIn this paper, we study multiplicative dependence of values of polynomials or rational functions over a number field. As an application, we obtain new results on multiplicative dependence in the orbits of a univariate polynomial dynamical system. We also obtain a generalization of the Northcott theorem replacing the finiteness of preperiodic points from a given number field by the finiteness of algebraic integers having two multiplicatively dependent elements in their orbits
On abelian multiplicatively dependent points on a curve in a torus
No full textWe show, under some natural conditions, that the set of abelian (and thus also cyclotomic) multiplicatively dependent points on an irreducible curve over a number field is a finite union of preimages of roots of unity by a certain finite set of primitive characters from Gmn to Gm restricted to the curve, and a finite set. We also introduce the notion of primitive multiplicative dependence and obtain a finiteness result for primitively multiplicatively dependent points defined over a so-called Bogomolov extension of a number field
Garden of curves with many automorphisms
No full textWe survey recent results and some open problems on the abstract structures and actions of automorphism groups of algebraic curves in positive characteristic. Several examples with very large automorphism group are also presente
Studiu privind dezvoltarea conceptuală a unui sistem pentru analiza mersului
Get PDFÎn contextul actual al tehnologiei medicale avansate, analiza mersului a devenit un instrument esențial în diagnosticarea și reabilitarea afecțiunilor locomotorii. Acest articol își propune dezvoltarea conceptuală a unui sistem pentru analiza mersului, care integrează tehnologii și algoritmi pentru procesarea datelor. Prin identificarea parametrilor critici ai mersului (lungimea pasului, ritmul de mers, unghiul de deviație, durata unui ciclu de mers) și aplicarea unor metode de analiză biomecanică (analiza cinematică și cinetică, distribuția presiunii plantare, evaluarea parametrilor temporali, înregistrări video ale ciclului de mers), sistemul propus oferă o evaluare detaliată și personalizată a mersului pacientului. Cercetarea se concentrează pe crearea unui model care să permită colectarea precisă a datelor, utilizând un modul care se poate monta pe glezna subiectului și un modul pe genunchiul acestuia (acestea pot fi utilizate împreună sau separat în funcție de necesitățile analizelor asupra subiecților), precum și interpretarea într-un mod semnificativ și util d.pd.v. clinic. Sistemul pentru analiza mersului poate fi utilizat în practica clinică pentru diagnosticare, monitorizare, personalizarea tratamentului, prevenție și cercetare. Metodologia adoptată implică utilizarea senzorilor goniometrici, a platformelor de forță și a unui modul de analiză a datelor pentru definirea dinamicii mersului. Concluziile studiului subliniază importanța integrării tehnologiei în practica clinică, deschizând calea către noi cercetări în domeniul biomecanicii mersului
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Electrochemical Oxidation of Glucose Using Mutant Glucose Oxidase from Directed Protein Evolution for Biosensor and Biofuel Cell Applications
No full textIn this study, electrochemical characterisation of glucose oxidation has been carried out in solution and using enzyme polymer electrodes prepared by mutant glucose oxidase (B11-GOx) obtained from directed protein evolution and wild-type enzymes. Higher glucose oxidation currents were obtained from B11-GOx both in solution and polymer electrodes compared to wt-GOx. This demonstrates an improved electrocatalytic activity towards electrochemical oxidation of glucose from the mutant enzyme. The enzyme electrode with B11-GOx also showed a faster electron transfer indicating a better electronic interaction with the polymer mediator. These encouraging results have shown a promising application of enzymes developed by directed evolution tailored for the applications of biosensors and biofuel cells.Supplementary material: [http://cherry.chem.bg.ac.rs/handle/123456789/3611
Strong asymptotic arbitrage in the large fractional binary market
Get PDFCordero F, Perez-Ostafe L. Strong asymptotic arbitrage in the large fractional binary market. MATHEMATICS AND FINANCIAL ECONOMICS. 2016;10(2):179-202.We study, from the perspective of large financial markets, the asymptotic arbitrage (AA) opportunities in a sequence of binary markets approximating the fractional Black-Scholes model. This approximating sequence was introduced by Sottinen and named fractional binary market. The large financial market under consideration does not satisfy the standard assumptions of the theory of AA. For this reason, we follow a constructive approach to show first that a strong AA (SAA) exists in the frictionless case. Indeed, with the help of an appropriate version of the law of large numbers and a stopping time procedure, we construct a sequence of self-financing trading strategies leading to the desired result. Next, we introduce, in each small market, proportional transaction costs, and we show that a slight modification of the previous trading strategies leads to a SAA when the transaction costs converge fast enough to 0
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