http://hdl.handle.net/10016/5857 Wed, 22 May 2013 02:27:25 GMT 2013-05-22T02:27:25Z http://e-archivo.uc3m.es:80/retrieve/24357/logo_gama.bmp http://hdl.handle.net/10016/5857 http://hdl.handle.net/10016/7012 Title: Demixing behavior in two-dimensional mixtures of anisotropic hard bodies Author(s): Martínez-Ratón, Yuri; Velasco, Enrique; Mederos, Luis Abstract: Scaled particle theory for a binary mixture of hard discorectangles and for a binary mixture of hard rectangles is used to predict possible liquid-crystal demixing scenarios in two dimensions. Through a bifurcation analysis from the isotropic phase, it is shown that isotropic-nematic demixing is possible in two-dimensional liquid-crystal mixtures composed of hard convex bodies. This bifurcation analysis is tested against exact calculations of the phase diagrams in the framework of the restricted-orientation two-dimensional model (Zwanzig model). Phase diagrams of a binary mixture of hard discorectangles are calculated through the parametrization of the orientational distribution functions. The results show not only isotropic-nematic, but also nematic-nematic demixing ending in a critical point, as well as an isotropic-nematic-nematic triple point for a mixture of hard disks and hard discorectangles. Description: 11 pages, 9 figures.-- PACS nrs.: 64.70.Md, 64.75.+g, 61.20.Gy.-- ArXiv pre-print available at: http://arxiv.org/abs/cond-mat/0509213 Wed, 31 Aug 2005 22:00:00 GMT http://hdl.handle.net/10016/7012 2005-08-31T22:00:00Z http://hdl.handle.net/10016/6935 Title: Recent trends in orthogonal polynomials and their applications Author(s): Marcellán, Francisco; Arvesú, Jorge Abstract: In this contribution we summarize some new directions in the theory of orthogonal polynomials. In particular, we emphasize three kinds of orthogonality conditions which have attracted the interest of researchers from the last decade to the present time. The connection with operator theory, potential theory and numerical analysis will be shown. Description: 29 pages, 1 figure.-- MSC2000 codes: 42C05, 33C45.-- Contributed to: XVII CEDYA: Congress on differential equations and applications/VII CMA: Congress on applied mathematics (Salamanca, Spain, Sep 24-28, 2001).; MR#: MR1873645 (2002i:42031); Zbl#: Zbl 1026.42025 Sun, 31 Dec 2000 23:00:00 GMT http://hdl.handle.net/10016/6935 2000-12-31T23:00:00Z http://hdl.handle.net/10016/6853 Title: On free nets over Minkowski space Author(s): Baumgärtel, Hellmut; Jurke, Matthias; Lledó, Fernando Abstract: Using standard results on CAR- and CCR-theory and on representation theory of the Poincaré group a direct way to construct nets of local C*-algebras satisfying Haag-Kastler's axioms is given. No explicite use of any field operator or of any concrete representation of the algebra is made. The nets are associated to models of mass m ≥ 0 and arbitrary spin or helicity. Finally, Fock states satisfying the spectrality condition are specified. Description: 27 pages, no figures.-- MSC2000 codes: 46L60, 81T05.; MR#: MR1369988 (96m:81132); Zbl#: Zbl 0883.46040 Tue, 31 Jan 1995 23:00:00 GMT http://hdl.handle.net/10016/6853 1995-01-31T23:00:00Z http://hdl.handle.net/10016/6852 Title: Superselection structures for C*-algebras with nontrivial center Author(s): Baumgärtel, Hellmut; Lledó, Fernando Abstract: We present and prove some results within the framework of Hilbert C*-systems $\{{\cal F},{\cal G}\}$ with a compact group ${\cal G}$. We assume that the fixed point algebra ${\cal A}\subset{\cal F}$ of ${\cal G}$ has a nontrivial center ${\cal Z}$ and its relative commutant w.r.t. ${\cal F}$ coincides with ${\cal Z}$, i.e., we have ${\cal A}'\cap{\cal F}= {\cal Z}\supset\bbfC\text{\bf 1}$. In this context, we propose a generalization of the notion of an irreducible endomorphism and study the behaviour of such irreducibles w.r.t. ${\cal Z}$. Finally, we give several characterizations of the stabilizer of ${\cal A}$. Description: 35 pages, no figures.-- MSC2000 codes: 46L05, 46L60.; MR#: MR1475657 (99g:46097); Zbl#: Zbl 0893.46046 Tue, 31 Dec 1996 23:00:00 GMT http://hdl.handle.net/10016/6852 1996-12-31T23:00:00Z