1,721,102 research outputs found
Lack of BV bounds for approximate solutions to a two-phase transition model arising from vehicular traffic
No full textWe consider wave-front tracking approximate solutions (Formula presented.) to a two-phase transition model for vehicular traffic. We construct an explicit example showing that the total variation in space of (Formula presented.) may blow up in finite time for (Formula presented.) even for an initial datum with bounded total variation
Monte Carlo simulation of electron transport in (formula presented) superlattices: Vertical transport enhanced by a parallel field
No full textConsiderable effort is presently devoted to develop Si quantum structures for microelectronics and nanoelectronics. In particular, well-defined (formula presented) superlattices and quantum wells are under study. We investigate here the transport properties of a (formula presented) superlattice with a multiband one-particle Monte Carlo simulator. The band structure is obtained with an analytical model and the scattering mechanisms introduced in the simulator are confined optical phonons, both polar and nonpolar. Owing to the very flat shapes of the bands along the growth direction, very low drift velocities are obtained for vertical transport. However, the simulation shows that, for oblique fields, the transport properties along the vertical direction are strongly enhanced by the in-plane component of the electric field, consequently higher vertical drift velocities can be easily obtained. © 2002 The American Physical Society
Coherence and flow-maximization of a one-way valve
No full textWe consider a mathematical model for the gas flow through a one-way valve and focus on two issues. First, we propose a way to eliminate the chattering (the fast switch on and off of the valve) by slightly modifying the design of the valve. This mathematically amounts to the construction of a coupling Riemann solver with a suitable stability property, namely, coherence. We provide a numerical comparison of the behavior of the two valves. Second, we analyze, both analytically and numerically, for several significative situations, the maximization of the flow through the modified valve according to a control parameter of the valve and time
Lights and shadows of electrophile signaling: Focus on the Nrf2-Keap1 pathway
No full textTargeted covalent modification is assuming consolidated importance in drug discovery. In this context, the electrophilic tuning of redox-dependent cell signaling is attracting major interest, as it opens prospect for treating numerous pathologic conditions. Herein, we discuss the rationale and the issues of electrophile-based approaches, focusing on the transcriptional Nrf2-Keap1 pathway as a test case. We also highlight relevant medicinal chemistry strategies researchers have devised to meet the ambitious goal, dwelling on the investigational and therapeutic potential of modulating redox-signaling networks through regulatory cysteine switches
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
Indium surface diffusion on InAs (2×4) reconstructed wetting layers on GaAs(001)
No full textIn this paper we present a study of In surface diffusion on InAs wetting layers deposited on the (001) surface of GaAs. The α2 (2×4) and β2 (2×4) reconstructions stabilized by a high In concentration are considered. The low symmetry of the α2 (2×4) reconstruction allowed us to understand the effect of the wetting-layer symmetry on the adsorbate diffusion. We find that (i) the diffusion coefficient value is larger for In motion on the α2 reconstruction than on the β2 reconstruction. This is due to the presence on β2 of an additional As dimer that rises locally the potential energy surface and offer an additional site to which the In adatom can bind strongly. (ii) The In adsorption sites located within the As dimers have to be taken into account properly for these specific reconstructions, since they greatly affect the value of the diffusion coefficient. This is in contrast to what happens for the other reconstructions reported in the literature. (iii) The adsorbate diffusion is highly anisotropic with the [1̄ 10] direction favored over the [110] direction, due to the presence of low-potential channels along [1̄ 10]. (iv) The anisotropy is slightly smaller on the α2 reconstruction than on the β2 reconstruction because on the β2 there is an additional diffusion channel along the [1̄ 10] direction. © 2009 The American Physical Society
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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