1,721,047 research outputs found
Prescribed mass ground states for a doubly nonlinear Schrödinger equation in dimension one
Full text linkWe investigate the problem of existence and uniqueness of ground states at fixed mass for two families of focusing nonlinear Schrödinger equations on the line.
The first family consists of NLS with power nonlinearities concentrated at a point. For such model, we prove existence and uniqueness of ground states at every mass when the nonlinearity power is subcritical and at a threshold value of the mass in the critical regime.
The second family is obtained by adding a standard power nonlinearity to the previous setting. In this case, we prove existence and uniqueness at every mass in the doubly subcritical case, namely when both the powers related to the pointwise and the standard nonlinearity are subcritical. If only one power is critical, then existence and uniqueness hold only at masses lower than the critical mass associated to the critical nonlinearity. Finally, in the doubly critical case ground states exist only at critical mass, whose value results from a non--trivial interplay between the two nonlinearities.17 page
Dalla multicultura all’intercultura. Spazi e strumenti geografici ( Seconda Edizione)
No full textL'evoluzione attuale della società e le trasformazioni economiche recenti
mettono in discussione il concetto tradizionale di cittadinanza ed obbligano
ad ampliare gli orizzonti per prestare attenzione alla difficile integrazione culturale
e giuridica tra comunità umane differenti. Sono necessarie nuove competenze
di cittadinanza mondiale per sviluppare una coscienza sociale e civica
in grado di affrontare le sfide del presente. Il processo interculturale si pone
come base fondativa a sostegno del cambiamento in atto.
Il volume, dopo aver ripreso il concetto e il significato di cultura ripartendo
dalla lettura di Paul Claval (2002) e Adalberto Vallega (2003), sintetizza alcuni
concetti chiave come diversità culturale, metacultura, transcultura, multicultura
per giungere infine a quello di intercultura tenendo ben presenti le
definizioni elaborate nel 2008 dal Consiglio d’Europa
Dalla multicultura all'intercultura. Spazi e strumenti geografici,
No full textMulticultura ed intercultura sono concetti talmente utilizzati, meglio ancora “abusati” in ogni contesto in cui si manifesta una generica volontà di apertura, da essere divenuti banali. Queste categorie concettuali sono in realtà state svuotate dei loro contenuti. Si mostrano solo quali nudi contenitori – indifferentemente in forma di sostantivo o di aggettivo – atti a mascherare fenomeni, geografici o meno, difficili da cogliere perché mutevoli. In tale contesto il volume analizza sotto diverse prospettive, in particolare quella geografica, queste tematiche e/o problematiche attraverso una serie di casi di studio ed esempi concreti. Il volume si rivolge in primis a studenti universitari, ma anche a tutti coloro che per la prima volta si avvicinano a queste tematiche
GEOGRAFIA INTERCULTURALE
No full textIl volume intende illustrare in quadro interdisciplinare le potenzialità della geografia interculturale nel proporre un modello educativo per formare i "cittadini del mondo
Normalized NLS ground states on a double-plane hybrid
Full text linkWe investigate the existence and the properties of normalized ground states of a nonlinear Schroedinger equation on a quantum hybrid formed by two planes connected at a point. The nonlinearities are of power type and L2-subcritical, while the matching condition between the two planes generates two point interactions of different strengths on each plane, together with a coupling condition between the two planes. We prove that ground states exist for every value of the mass and two different qualitative situations are possible depending on the matching condition: either ground states concentrate on one of the plane only, or ground states distribute on both the planes and are positive, radially symmetric, decreasing and present a logarithmic singularity at the origin of each plane. Moreover, we discuss how the mass distributes on the two planes and compare the strengths of the logarithmic singularities on the two planes when the parameters of the matching condition and the powers of the nonlinear terms vary
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
Normalized ground states for Schrödinger equations on metric graphs with nonlinear point defects
Full text linkWe investigate the existence of normalized ground states for Schrödinger equations on noncompact metric graphs in presence of nonlinear point defects, described by nonlinear δ-interactions at some of the vertices of the graph. For graphs with finitely many vertices, we show that ground states exist for every mass and every L^2-subcritical power. For graphs with infinitely many vertices, we focus on periodic graphs and, in particular, on Z-periodic graphs and on a prototypical Z^2-periodic graph, the two–dimensional square grid. We provide a set of results unravelling nontrivial threshold phenomena both on the mass and on the nonlinearity power, showing the strong dependence of the ground state problem on the interplay between the degree of periodicity of the graph, the total number of point defects and their dislocation in the graph
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
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