1,720,987 research outputs found
Convergence to self-similarity for the Boltzmann equation for strongly inelastic Maxwell molecules.
No full textWe prove propagation of regularity, uniformly in time, for the scaled solutions of the inelastic Maxwell model for any value of
the coefficient of restitution. The result follows from the uniform in time control of the tails of the Fourier transform of the solution,
normalized in order to have constant energy. By standard arguments this implies the convergence of the scaled solution towards the
stationary state in Sobolev and L1 norms in the case of regular initial data as well as the convergence of the original solution to the
corresponding self-similar cooling state. In the case of weak inelasticity, similar results have been established by Carlen, Carrillo
and Carvalho (2009) in [11] via a precise control of the growth of the Fisher information
Fokker-Planck equations in the modeling of socio-economic phenomena
No full textWe present and discuss various one-dimensional linear Fokker-Planck-Type equations that have been recently considered in connection with the study of interacting multi-Agent systems. In general, these Fokker-Planck equations describe the evolution in time of some probability density of the population of agents, typically the distribution of the personal wealth or of the personal opinion, and are mostly obtained by linear or bilinear kinetic models of Boltzmann type via some limit procedure. The main feature of these equations is the presence of variable diffusion, drift coefficients and boundaries, which introduce new challenging mathematical problems in the study of their long-Time behavior
Blow-up and global solutions for subcritical and critical parabolic equations in
No full textWe study the local well-posedness in the framework of the Sobolev space (Formula presented), for a semilinear parabolic equation with asymptotically polynomial nonlinearity up to the critical Sobolev growth. Then we establish the dichotomy between blow-up and global existence for solutions with small energy by means of variational methods and the so-called potential well argument
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
A Potential Well Argument for a Semilinear Parabolic Equation with Exponential Nonlinearity
No full text"We consider the Cauchy problem for a two space dimensional parabolic equation with square exponential nonlinearity. More precisely,
{∂tu=Δu−u+λf(u)u(0,x)=u0(x)in (0,T)×R2,in R2,
where λ>0, and f(u):=2α0ueα0u2, for some α0>0. We take into account initial data in the energy space H1(R2), i.e. u0∈H1(R2), and in view of the Trudinger-Moser inequality, the nonlinearity f (which has square exponential growth at infinity) is in the energy critical regime.
"We look for sufficient conditions in order to predict from the initial data whether the solution blows up in finite time or the solution exists globally in time. Our main tools are energy methods, and the so-called potential well argument. If 0<12α0, we prove that for energies below the ground state level, the dichotomy between blow-up and global existence is determined by the sign of a suitable functional.'
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
- …
