1,720,983 research outputs found
The Cuntz algebra Q_N and C*-algebras of product systems
No full textWe consider a product system over the multiplicative group semigroup N^x of Hilbert bimodules which is implicit in work of S. Yamashita and of the second named author. We prove directly, using universal properties, that the associated Nica-Toeplitz algebra is an extension of the C*-algebra Q_N introduced recently by Cuntz
The Cuntz algebra Q_N and C*-algebras of product systems
No full textWe consider a product system over the multiplicative group semigroup N^x of Hilbert bimodules which is implicit in work of S. Yamashita and of the second named author. We prove directly, using universal properties, that the associated Nica-Toeplitz algebra is an extension of the C*-algebra Q_N introduced recently by Cuntz
THE MODULATION MAPPING FOR MAGNETIC SYMBOLS AND OPERATORS
Full text linkArtículo de publicación ISIWe extend the Bargmann transform to the magnetic pseudodifferential
calculus, using gauge-covariant families of coherent states. We also introduce
modulation mappings, a first step towards adapting modulation spaces
to the magnetic case.The first author is partially supported by N´ucleo Cientifico ICM P07-027-F “Mathematical
Theory of Quantum and Classical Magnetic Systems” and by the Chilean Science Foundation
Fondecyt under grant no. 1085162.The second author acknowledges partial support from contract no. 2-CEx 06-11-18/2006
Automorphisms of the Cuntz algebras
No full textWe survey recent results on endomorphisms and especially on automorphisms of the Cuntz algebras, with a special emphasis on the structure of the Weyl group. We discuss endomorphisms globally preserving the diagonal MASA and their corresponding actions. In particular, we investigate those endomorphisms of O_n which restrict to automorphisms of the diagonal. We review a combinatorial approach to the study of permutative endomorphisms. All the presented material is put in context with current research topics
Automorphisms of the Cuntz algebras
No full textWe survey recent results on endomorphisms and especially on automorphisms of the Cuntz algebras, with a special emphasis on the structure of the Weyl group. We discuss endomorphisms globally preserving the diagonal MASA and their corresponding actions. In particular, we investigate those endomorphisms of O_n which restrict to automorphisms of the diagonal. We review a combinatorial approach to the study of permutative endomorphisms. All the presented material is put in context with current research topics
Quantization of 2-plectic manifolds
No full textWe describe an extension of the axioms of quantization to the case of 2-plectic manifolds. We show how such quantum spaces can be obtained as stable classical solutions in a zero-dimensional 3-algebra reduced model obtained by dimensional reduction of the Bagger-Lambert-Gustavsson theory. We demonstrate that the groupoid approach to geometric quantization proposed by Hawkins and others can be useful for quantizing 2-plectic manifolds. We discuss our results in the context of recent developments in the quantum geometry of M-branes, and in the nonassociative deformation of spacetime induced by closed strings in the presence of a 2-plectic form
On the Fermi Golden Rule:Degenerate Eigenvalues
No full textWe review and further develop the framework in [9] of the stationary theory of resonances, arising by perturbation of either threshold, or embedded in the continuum, eigenvalues. While in [9] only non/degenerate eigenvalues were considered, here we add some results for the degenerate case.[9] A. Jensen and G. Nenciu, The Fermi Golden Rule and its form at thresholds in odd dimensions. Comm. Math. Phys 261 (2006), 693-727We review and further develop the framework in [9] of the stationary theory of resonances, arising by perturbation of either threshold, or embedded in the continuum, eigenvalues. While in [9] only non/degenerate eigenvalues were considered, here we add some results for the degenerate case.[9] A. Jensen and G. Nenciu, The Fermi Golden Rule and its form at thresholds in odd dimensions. Comm. Math. Phys 261 (2006), 693-727</p
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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