1,720,969 research outputs found
Intrinsic frame transport for a model of nematic liquid crystal
No full textWe present a computer simulation study of the dynamical properties of a nematic liquid crystal model. The diffusional motion of the nematic director is taken into account in our calculations in order to give a proper estimate of the transport coefficients, Differently from other groups we do not attempt to stabilize the director through rigid constraints or applied external fields. We instead define an intrinsic frame which moves along with the director at each step of the simulation, The transport coefficients computed in the intrinsic frame are then compared against the ones calculated in the fixed laboratory frame, to show the inadequacy of the latter for systems with less than 500 molecules, Using this general scheme on the Gay-Berne liquid crystal model, we evidence the natural motion of the director and attempt to quantify its intrinsic time scale and size dependence. Through extended simulations of systems of different size we calculate the diffusion and viscosity coefficients of this model and compare our results with values previously obtained with fixed director
Phase equilibria of a lattice model of associating binary mixtures.
No full textWe study a lattice model of an associating A-B binary mixture, which differs from the one originally proposed by Lin and Taylor (Phys. Rev. E, 1994, 49, 2058 and Phys. Rev. Lett., 1994, 73, 2863) because it allows interactions between all pairs of particles. This model can be mapped onto an Ising model with renormalized coupling parameters. The global phase diagram of the mixture is obtained as a function of the physical parameters. The appearance of closed loops of immiscibility is analysed in terms of the coupling parameters
Critical exponents in the Lin-Taylor model of asymmetrical associating binary mixtures
No full textThe critical behaviour of an associating fluid mixture, the so called Lin-Taylor model, has been studied, with focus on the critical exponents which characterize different points on the critical manifold. In general the critical behaviour of the mixture is found to be Ising-like, but there are some special situations: when two ordinary critical points merge into a double critical point or three critical points coalesce at a critical inflection point. A check has been made on the validity of the relations between critical exponents and predictions from the scaling laws
Exact Results for the Lower Critical Solution in the asymmetric Model for an Interacting Binary Mixture
No full textCommen
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
Complex fluid behavior of strongly asymmetric binary mixtures. Thermodynamic properties of a generalized Lin-Taylor model
No full textA detailed analysis is made of the lattice model of binary mixtures A± B, proposed a few years ago by Lin and Taylor. This model exhibits ̄ uid± ̄ uid immiscibility and a closed loop of immiscibility. Based on general arguments, the distinct possible behaviour is examined as a function of the coupling parameters, temperature and pressure in di erent lattices. The phase diagram is found to be richer than that reported previously, even in the square lattice case. The system, for attractive A± A interactions, shows the disappearance of one of the critical points for pressures lower than the A-pure system critical pressure. On the other hand, the mixture displays closed-loop behaviour without a low temperature immiscibility region for values of the interaction parameters e AA < 0 and e AB < e AA /
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
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