1,720,967 research outputs found
ON THE LOCATION OF THE 1-PARTICLE BRANCH OF THE SPECTRUM OF THE DISORDERED STOCHASTIC ISING MODEL
Full text linkWe analyse the lower non trivial part of the spectrum of the generator of the Glauber dynamics for a d-dimensional nearest neighbour Ising model with a bounded random potential. We prove conjecture 1 in [1]: for sufficently large values of the temperature, the first band of the spectrum of the generator of the process coincides with a closed non random segment of the real line
On the "Matrix Approach" to Interacting Particle Systems
No full textDerrida et al. and Schütz and Stinchcombe gave algebraic formulas for the correlation functions of the partially asymmetric simple exclusion process. Here we give a fairly general recipe of how to get these formulas and extend them to the whole time evolution (starting from the generator of the process), for a certain class of interacting systems. We then analyze the algebraic relations obtained to show that the matrix approach does not work with some models such as the voter and the contact processes
Multitasking attractor networks with neuronal threshold noise
No full textWe consider the multitasking associative network in the low-storage limit and we study its phase diagram with respect to the noise level T and the degree d of dilution in pattern entries. We find that the system is characterized by a rich variety of stable states, including pure states, parallel retrieval states, hierarchically organized states and symmetric mixtures (remarkably, both even and odd), whose complexity increases as the number of patterns P grows. The analysis is performed both analytically and numerically: Exploiting techniques based on partial differential equations, we are able to get the self-consistencies for the order parameters. Such self-consistency equations are then solved and the solutions are further checked through stability theory to catalog their organizations into the phase diagram, which is outlined at the end. This is a further step towards the understanding of spontaneous parallel processing in associative networks. © 2013 Elsevier Ltd
The Brownian Web: Convergence and Characterisation
No full textThe Brownian web (BW) is the random network formally consisting of the paths of coalescing one-dimensional Brownian motions starting from every space-time point in ?×?. We extend the earlier work of Arratia and of Tóth and Werner by providing a new characterization which is then used to obtain convergence results for the BW distribution, including convergence of the system of all coalescing random walks to the BW under diffusive space-time scaling
Cell capacity of LMDS systems in typical traffic scenarios
Full text linkBroadband access and multimedia technologies are expected to be primary drivers for the telecommunications market of the next few years. The increasing bandwidth needs, together with the plethora of different services and heterogeneous traffic flows, requires accurate methodologies for resource dimensioning, especially in the field of wireless technologies where efficient bandwidth usage is crucial. New methodologies need to be based on up-to-date traffic source modeling and usage scenarios. Therefore, in this article we propose a survey of statistical characterization of single traffic sources, QoS requirements and different traffic demands. When possible, we consider the aggregate traffic resulting from a large number of heavy tailed ON/OFF sources, relying on the theory of long-range dependent flows. This method is particularly useful when time- and resource-consuming simulations are needed in order to dimension the system resources, which is always the case in the multimedia scenarios of future networks. We use such a traffic framework to estimate by simulations the capacity of an LMDS system
Recursive integral equations with positive kernel for lattice calculations
Full text linkWe derive a Kirkwood-Salzburg integral equation, with positive defined kernel, for the states of lattice models of statistical mechanics and quantum field theory. The equation is defined in the thermodynamic limit, and its iterative solution is convergent; moreover, positivity leads to an exact a priori bound on the iteration. The equation's relevance as a reliable algorithm for lattice calculations is therefore suggested, and it is illustrated with a simple application. It should provide a viable alternative to Monte Carlo methods for models of statistical mechanics and lattice gauge theories
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
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