Entanglement in fermionic chains with finite range coupling and broken symmetries

We obtain a formula for the determinant of a block Toeplitz matrix associated with a quadratic fermionic chain with complex coupling. Such couplings break reflection symmetry and/or charge conjugation symmetry. We then apply this formula to compute the Renyi entropy of a partial observation to a subsystem consisting of $X$ contiguous sites in the limit of large $X$. The present work generalizes similar results due to Its, Jin, Korepin and Its, Mezzadri, Mo. A striking new feature of our formula for the entanglement entropy is the appearance of a term scaling with the logarithm of the size of $X$. This logarithmic behaviour originates from certain discontinuities in the symbol of the block Toeplitz matrix. Equipped with this formula we analyse the entanglement entropy of a Dzyaloshinski-Moriya spin chain and a Kitaev fermionic chain with long range pairing.Comment: 27 pages, 5 figure

On the M\"obius transformation in the entanglement entropy of fermionic chains

There is an intimate relation between entanglement entropy and Riemann surfaces. This fact is explicitly noticed for the case of quadratic fermionic Hamiltonians with finite range couplings. After recollecting this fact, we make a comprehensive analysis of the action of the M\"obius transformations on the Riemann surface. We are then able to uncover the origin of some symmetries and dualities of the entanglement entropy already noticed recently in the literature. These results give further support for the use of entanglement entropy to analyse phase transition.Comment: 29 pages, 5 figures. Final version published in JSTAT. Two new figures. Some comments and references added. Typos correcte

Connectivity-dependent properties of diluted sytems in a transfer-matrix description

We introduce a new approach to connectivity-dependent properties of diluted systems, which is based on the transfer-matrix formulation of the percolation problem. It simultaneously incorporates the connective properties reflected in non-zero matrix elements and allows one to use standard random-matrix multiplication techniques. Thus it is possible to investigate physical processes on the percolation structure with the high efficiency and precision characteristic of transfer-matrix methods, while avoiding disconnections. The method is illustrated for two-dimensional site percolation by calculating (i) the critical correlation length along the strip, and the finite-size longitudinal DC conductivity: (ii) at the percolation threshold, and (iii) very near the pure-system limit.Comment: 4 pages, no figures, RevTeX, Phys. Rev. E Rapid Communications (to be published

Smoothly-varying hopping rates in driven flow with exclusion

We consider the one-dimensional totally asymmetric simple exclusion process (TASEP) with position-dependent hopping rates. The problem is solved,in a mean field/adiabatic approximation, for a general (smooth) form of spatial rate variation. Numerical simulations of systems with hopping rates varying linearly against position (constant rate gradient), for both periodic and open boundary conditions, provide detailed confirmation of theoretical predictions, concerning steady-state average density profiles and currents, as well as open-system phase boundaries, to excellent numerical accuracy.Comment: RevTeX 4.1, 14 pages, 9 figures (published version

Estrutura e dinâmica em uma floresta de várzea do Rio Amazonas no Estado do Amapá.

O Rio Amazonas; O braço norte do Rio Amazonas; A várzea do estuário amazônico; A floresta de várzea do estuário amazônico; Uso dos recursos da floresta de várzea do estuário; A estrutura da floresta de várzea do estuário; Distribuição diamétrica; A dinâmica da floresta de várzea do estuário; Dinâmica e sucessão florestal; Ingresso e recrutamento; Crescimento; Mortalidade; Descrição da área de estudos; Clima; Solo; Áreas da parte externa da Foz do Rio Amazonas; Vila Progresso - Bailique; Igarapé República; Rio Aracu - Foz do Rio Macacoari; Áreas da parte interna da Foz do Rio Amazonas; Furo do Mazagão; Rio Mutuacá; Rio Maniva - Ilha do Pará; Análise da estrutura da floresta; Estrutura da floresta; Composição florística; Densidade, dominância, frequência e valor de importância; Distribuição espacial das espécies; Diversidadde de espécies; Quociente de mistura; Importância sócio-econômica da floresta em estudo; O manejo dos açaizais; O manejo das espécies arbóreas; O manejo das espécies oleaginosas.Tese (Doutorado em Ciências Florestais) - Universidade Federal do Paraná, Curitiba