1,721,020 research outputs found
Symmetry properties of a system of Euler-type equations for magnetized plasmas
No full textWe provide all Lie point symmetries of a system of partial differential equations, of great interest to plasma physics; we deduce the corresponding invariant solutions and discuss their physical interpretation. We also consider some of its conditional and partial symmetries and obtain other interesting solutions. Finally, we point out that, although the system can be cast in divergence form and admits conserved currents, it does not admit potential symmetries
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Charge state of a spherical plasma in vacuum.}, Phys. Rev. E, vol.71, pp. 056407.1-056407.5 (2005)
No full textExpansion of planar and spherical plasma bunches
No full textAbstract
The expansion dynamics of a finite-size plasma is examined from an analytical
perspective. Results regarding the charge distribution as well as the electrostatic
potential are presented. The acceleration of the ions and the associated cooling
of the electrons that takes place during the plasma expansion is described. An
extensive analysis of the transition between the semi-infinite and the finitesize
plasma behaviour is carried out. Finally, a test of the analytical results,
performed through numerical simulations, is presented
Two-dimensional Harris-Liouville plasma kinetic equilibria
No full textIsothermal stationary solutions of the self-consistent Vlasov equation can be constructed for arbitrary two-dimensional sheared magnetic field configurations by exploiting a complex function representation of the solutions of the nonlinear Liouville equation. All these solutions are shown to be locally equivalent to the well known Harris sheet pinch configuration. Solutions corresponding to different magnetic configurations are presented, including a double Y-point configuration reminiscent of a reconnection current layer. Lie point symmetries are used to elucidate the relationship between the different configurations and to investigate the structure of the linearized perturbations in the "quasistatic" approximation. (c) 2005 American Institute of Physics
Variations on the Author
Get PDF“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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