Phase diagram and dynamic response functions of the Holstein-Hubbard model

We present the phase diagram and dynamical correlation functions for the Holstein-Hubbard model at half filling and at zero temperature. The calculations are based on the Dynamical Mean Field Theory. The effective impurity model is solved using Exact Diagonalization and the Numerical Renormalization Group. Excluding long-range order, we find three different paramagnetic phases, metallic, bipolaronic and Mott insulating, depending on the Hubbard interaction U and the electron-phonon coupling g. We present the behaviour of the one-electron spectral functions and phonon spectra close to the metal insulator transitions.Comment: contribution to the SCES04 conferenc

Outsourcing and Employment: A Decomposition Approach

In this paper we study the employment effects of changes in the levels and patterns of outsourcing in the Austrian economy over the periods 1995-2000 and 2000-2003. Based on an input-output framework we apply a hierarchical decomposition analysis to disentangle the employment effects of changes in labour productivity, technical input coefficients and final demand components. Outsourcing is modelled as changes in the shares of domestically produced intermediates. For this some further details can be derived by distinguishing between intermediate imports of energy, material and service products or according to educational intensities of the imported intermediate products. Following this approach first allows to study the direct and indirect effects of changes in the levels and structures of outsourcing.Second, the framework takes account of all 60 sectors (products) of the economy and thus also includes employment effects of service offshoring. Third, we also calculate the employment effects for three employment groups distinguished by educational attainment levels. This paper thus provides a comprehensive picture of employment effects of outsourcing in the Austrian economy.Foreign Direct Investment, outsourcing, offshoring, employment effects, hierarchical decomposition, input-output modelling

Single particle spectrum of the flux phase in the FM Kondo Model

We investigate the 2D ferromagnetic Kondo lattice model for manganites with classical corespins at Hund's rule coupling J_H=6, with antiferromagnetic superexchange 0.03 < J' < 0.05. We employ canonical and grand canonical unbiased Monte Carlo simulations and find paramagnetism, weak ferromagnetism and the Flux phase, depending on doping and on J'. The observed single particle spectrum in the flux phase differs from the idealized infinite lattice case, but agrees well with an idealized finite lattice case with thermal fluctuations.Comment: contribution to the SCES04 conferenc

Outsourcing in cattle ectoparasite control - a promising opportunity.

Records of the occurrence of resistant populations of cattle parasites are becoming increasingly frequent in different regions of the country. These reports refer in general to the horn fly, Haematobia irritans.Edição dos trabalhos do:7th International conference on urban pests. Updates on urban pest control. Ouro Preto, 2011

Automatic Classification of Text Databases through Query Probing

Many text databases on the web are "hidden" behind search interfaces, and their documents are only accessible through querying. Search engines typically ignore the contents of such search-only databases. Recently, Yahoo-like directories have started to manually organize these databases into categories that users can browse to find these valuable resources. We propose a novel strategy to automate the classification of search-only text databases. Our technique starts by training a rule-based document classifier, and then uses the classifier's rules to generate probing queries. The queries are sent to the text databases, which are then classified based on the number of matches that they produce for each query. We report some initial exploratory experiments that show that our approach is promising to automatically characterize the contents of text databases accessible on the web.Comment: 7 pages, 1 figur

Proposta de manejo de Memora peregrina - a Ciganinha.

A "ciganinha", cientificamente conhecida como Memora peregrina (Miers) Sandwith (Bignoniaceae), presente em diversas áreas de cerrado do Brasil Central, vem sendo um sério problema como invasora de pastagens cultivadas, em especial, quando estas já se encontram em adiantado estado de degradação. Nunes (1999) descreve-a como um arbusto, com ramos semilenhosos, entouceirado, ereto, que atinge a altura entre 100 e 150 centímetros. Apresenta inflorescências vistosas com flores amarelas semelhantes às do ipê-amarelo, o que contribuía para que, até recentemente, fosse catalogada apenas como planta ornamental (LORENZI; SOUZA, 1995). O principal período de florada ocorre na primavera e no verão, embora a presença de flores pode ser observada, praticamente, em qualquer época do ano. Sua reprodução se dá por sementes aladas, contidas em camadas sobrepostas no interior de uma cápsula com aspecto de uma longa vagem e, também, por processo vegetativo. Esse último ocorre pela ativação de gemas latentes presentes no caule, tanto em sua parte aérea quanto na subterrânea, em resposta ao seu eventual fracionamento ou quando este sofre lesões de qualquer natureza, especialmente por tratos mecânicos. Pouco se conhece sobre M. peregrina, porque mesmo em pastagens com gramíneas nativas e/ou naturalizadas, como Paspalum notatum (grama batatais ou mato-grosso), Melinis minutiflora (capimgordura) ou Hyparrhenia rufa (capim-jaraguá), manejadas há décadas com roçadeiras ou fogo, essa planta não é considerada problema. A ciganinha só assumiu o status de praga anos depois da implantação de pastagens cultivadas com uso de arados, grades de aração e subsoladores, sendo, em muitos casos, indicadora de pastagens degradadas ou em processo de degradação.bitstream/CNPGC-2009-09/12486/1/COT101.pd

Adult Female Spruce Bedworm, \u3ci\u3eChoristoneura Fumiferana\u3c/i\u3e (Lepidoptera: Tortricidae), Dry Weight in Relationship to Pupal Fresh Weight and Case Diameter

(excerpt) The weights of adult insects are often measured in production and population studies in order to estimate such variables as growth rates, food conversion efficiencies, fecundity, and others. For the eastern spruce budworm, Choristoneura fumiferana (Clemens), both pupal fresh weights and pupal case diameters have been measured as indicators of adult fecundity and adult dry weights (Miller 1957). However, there are no reports explicitly showing the relationship between these metric pupal variables and adult dry weights. This is the goal of this note

First- and Second Order Phase Transitions in the Holstein-Hubbard Model

We investigate metal-insulator transitions in the Holstein-Hubbard model as a function of the on-site electron-electron interaction U and the electron-phonon coupling g. We use several different numerical methods to calculate the phase diagram, the results of which are in excellent agreement. When the electron-electron interaction U is dominant the transition is to a Mott-insulator; when the electron-phonon interaction dominates, the transition is to a localised bipolaronic state. In the former case, the transition is always found to be second order. This is in contrast to the transition to the bipolaronic state, which is clearly first order for larger values of U. We also present results for the quasiparticle weight and the double-occupancy as function of U and g.Comment: 6 pages, 5 figure

Outsourcing and Employment: A Decomposition Approach

In this paper we study the employment effects of changes in the levels and patterns of outsourcing in the Austrian economy over the periods 1995-2000 and 2000-2003. Based on an input-output framework we apply a hierarchical decomposition analysis to disentangle the employment effects of changes in labour productivity, technical input coefficients and final demand components. Outsourcing is modelled as changes in the shares of domestically produced intermediates. For this some further details can be derived by distinguishing between intermediate imports of energy, material and service products or according to educational intensities of the imported intermediate products. Following this approach first allows to study the direct and indirect effects of changes in the levels and structures of outsourcing.Second, the framework takes account of all 60 sectors (products) of the economy and thus also includes employment effects of service offshoring. Third, we also calculate the employment effects for three employment groups distinguished by educational attainment levels. This paper thus provides a comprehensive picture of employment effects of outsourcing in the Austrian economy