1,720,967 research outputs found
Dimension estimates for badly approximable affine forms
No full textFor given & varepsilon;>0 and b is an element of R-m, we say that a real mxn matrix A is & varepsilon;-badly approximable for the target b if lim inf(q is an element of Zn,& Vert;q & Vert;->infinity)& Vert;q & Vert;(n)< Aq-b >(m)>=& varepsilon;, where <& sdot;> denotes the distance from the nearest integral vector. In this article, we obtain upper bounds for the Hausdorff dimensions of the set of & varepsilon;-badly approximable matrices for fixed target b and the set of & varepsilon;-badly approximable targets for fixed matrix A. Moreover, we give a Diophantine condition of A equivalent to the full Hausdorff dimension of the set of & varepsilon;-badly approximable targets for fixed A. The upper bounds are established by effectivizing entropy rigidity in homogeneous dynamics, which is of independent interest. For the A-fixed case, our method also works for the weighted setting where the supremum norms are replaced by certain weighted quasinorms.Y
Asymptotic distribution of values of isotropic quadratic forms at S-integral points
No full textWe prove an analogue of a theorem of Eskin-Margulis-Mozes [10]. Suppose we are given a finite set of places S over Q containing the Archimedean place and excluding the prime 2, an irrational isotropic form q of rank n≥4 on QS, a product of p-adic intervals Ip, and a product ω of star-shaped sets. We show that unless n ≥ 4 and q is split in at least one place, the number of S-integral vectors v ∈ TΩ satisfying simultaneously q(v) ∈ Ip for p ∈ S is asymptotically given by λ(q,ω)|I|·||T||n-2 as T goes to infinity, where |I| is the product of Haar measures of the p-adic intervals Ip. The proof uses dynamics of unipotent flows on S-arithmetic homogeneous spaces; in particular, it relies on an equidistribution result for certain translates of orbits applied to test functions with a controlled growth at infinity, specified by an S-arithmetic variant of the α-function introduced in [10], and an S-arithemtic version of a theorem of Dani-Margulis [7]. © 2017 AIMSCIENCES.Y
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Comptage de réseaux et rigidité entropique pour les actions de groupes sur des arbres et des immeubles
No full textIn my thesis, we consider two types of questions: counting overlattices, and the entropy rigidity in the group of automorphisms of trees and buildings. For the first questions, we obtain a universal upper bound for the number u(n) of lattices which contain a fixed lattice Γ of index n, in the automorphism group of a tree or a building. We also obtain a lower bound of u(n) for certain types of uniform lattices in the automorphism group of a tree or a hyperbolic building. The second problem is related to the dynamics of the geodesic flow on trees and buildings. Among all the normalized metrics on a graph, we show the existence and the uniqueness of a metric minimizing the entropy, and we obtain explicit formulae for this metric as well as for the minimal entropy.Dans cette thèse, nous considérons principalement deux types de questions: le comptage des réseaux, et la rigidité entropique dans des groupes d'automorphismes d'arbres et d'immeubles. Pour le premier problème, nous obtenons une majoration universelle pour le nombre u(n) de réseaux qui contiennent un réseau Γ fixé d'indice n, dans le groupe des automorphismes d'un arbre ou d'un immeuble. Nous obtenons aussi une minoration de u(n) pour certains types de réseaux uniformes dans le groupe des automorphismes d'un arbre et de certains immeubles hyperboliques. Le second problème est relié à la dynamique du flot géodésique sur les arbres et les immeubles. Parmi toutes les métriques normalisées sur un graphe, nous montrons l'existence et l'unicité d'une métrique minimisant l'entropie, et nous obtenons des formules explicites pour cette métrique ainsi que pour l'entropie minimale
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