1,720,979 research outputs found
Scale invariant correlations in a driven dissipative gas
No full textWe investigate the steady state properties of a randomly driven dissipative gas. As the number of particles is increased power-law spatial correlations in the density and velocity are seen to develop, and the exponents are found to be independent of the model details. We show how the critical properties of this system can be understood in terms of a one particle model which is amenable to exact analysis
Spin-flip Avalanches and Dynamics of 1st-order Phase-transitions
No full textA Comment on the Letter by J. P. Sethna et al., Phys. Rev. Lett. 70, 3347 (1993)
Scaling properties of suboptimal interfaces
No full textWe define a class of interfaces in random exchange Ising ferromagnets that are associated with nonequilibrium states of the system. We find that the interfaces are fractal and have a fractal dimension of about 1.6. The scaling properties are reburst and characteristic of a new universality class. Our results suggest the possibility that the fractal structures observed in nature need not be related to the true equilibrium of the system
Zero-point Surface Phonons - Effect On Wetting
No full textThe recently observed behavior of helium films adsorbed on alkali metal surfaces has confirmed earlier ideas about wetting and prewetting transitions. However, a quantitative discrepancy between the predicted and observed wetting temperature suggests that a reexamination of the energetics of adsorbed helium films is required. We show how the zero point phonon energy of an alkali-vapor interface can dramatically change the wetting properties of these substrates, in accord with experiment. We investigate the dependence on the exposed facet of the crystal surface. For Rb and Cs, the (110) face is predicted to be wet at zero temperature while the (100) face is not. An isotope effect is also predicted
Phase-diagrams of Random-field Ising Systems
No full textWe show that the random-field Ising model may be tuned to obtain two distinct scenarios of phase diagram topology. Explicit evidence for this is presented in a numerically exact analysis in three dimensions and on a Bethe lattice, which allows us to investigate the effects of temperature, coordination number, and asymmetry in the field distribution
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
Ordering and Phase-transitions In Random-field Ising Systems
No full textAn exact analysis of the Ising model with infinite-range interactions in a random field and a local mean-field theory in three dimensions is carried out leading to a phase diagram with several coexistence surfaces and lines of critical points. Our results show that the phase diagram depends crucially on whether the distribution of random fields is symmetric or not. Thus, Ising-like phase transitions in a porous medium (the asymmetric case) are in a different universality class from the conventional random-field model (symmetric case)
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