1,720,959 research outputs found
Separation of variables and Backlund transformations for the symmetric Lagrange top
No full textWe construct the one- and two-point integrable maps (Backlund transformations) for the symmetric Lagrange top. We show that the Lagrange top has the same algebraic Poisson structure that belongs to the sl(2) Gaudin magnet. The two-point map leads to a real time discretization of the continuous flow. Therefore, it provides an integrable numerical scheme for integrating the physical flow. We illustrate the construction by a few pictures of the discrete flow calculated in MATLAB
Backlund transformations for the sl(2) Gaudin magnet
No full textElementary, one- and two-point, Backlund transformations are constructed for the generic case of the sl(2) Gaudin magnet. The spectrality property is used to construct these explicitly given, Poisson integrable maps which are time discretizations of the continuous flows with any Hamiltonian from the spectral curve of the 2 x 2 Lax matrix
ON THE QUANTUM INVERSE SCATTERING METHOD FOR THE DST DIMER
No full textThe quantum inverse scattering method is used to solve the spectral problem of the discrete self-trapping dimer, in the case of both a quadratic and a linear r-matrix algebra representation. The first case is solved by the algebraic Bethe ansatz, while in the case of the linear r-matrix algebra we use the method of separation of variables. In this last case it is shown that the wave functions of the quantum discrete self-trapping dimer are related to the solutions of a Heun's type equation and that the system is equivalent to the two-site hyperbolic Gaudin magnet separable in elliptic coordinates
Integrable time-discretisation of the Ruijsenaars-Schneider model
No full textAn exactly integrable symplectic correspondence is derived which in a continuum limit leads to the equations of motion of the relativistic generalization of the Calogero-Moser system, that was introduced for the first time by Ruijsenaars and Schneider. For the discrete-time model the equations of motion take the form of Bethe Ansatz equations for the inhomogeneous spin-1/2 XYZ Heisenberg magnet. We present a Lax pair, the symplectic structure and prove the involutivity of the invariants. Exact solutions are investigated in the rational and hyperbolic (trigonometric) limits of the system that is given in terms of elliptic functions. These solutions are connected with discrete soliton equations. The results obtained allow us to consider the Bethe Ansatz equations as ones giving an integrable symplectic correspondence mixing the parameters of the quantum integrable system and the parameters of the corresponding Bethe wavefunction
Dynamical r-matrix for the elliptic Ruijsenaars-Schneider system
No full textThe classical r-matrix structure for the generic elliptic Ruijsenaars-Schneider model is presented. It makes manifest the integrability of this model as well as of its discrete-time version that was constructed in a recent paper
Backlund transformations for many-body systems related to KdV
Full text linkWe present Backlund transformations (BTs) with parameter for certain classical integrable n-body systems, namely the many-body generalised Henon-Heiles, Garnier and Neumann systems. Our construction makes use of the fact that all these systems may be obtained as particular reductions (stationary or restricted flows) of the KdV hierarchy; alternatively they may be considered as examples of the reduced sl(2) Gaudin magnet. The BTs provide exact time-discretizations of the original (continuous) systems, preserving the Lax matrix and hence all integrals of motion, and satisfy the spectrality property with respect to the Backlund parameter
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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