Influence of the external pressure on the quantum correlations of molecular magnets

The study of quantum correlations in solid state systems is a large avenue for research and their detection and manipulation are an actual challenge to overcome. In this context, we show by using first-principles calculations on the prototype material KNaCuSi$_{4}$O$_{10}$ that the degree of quantum correlations in this spin cluster system can be managed by external hydrostatic pressure. Our results open the doors for research in detection and manipulation of quantum correlations in magnetic systems with promising applications in quantum information science

Food consumption of Rhammatocerus schistocercoides Rehn (Orthoptera: Acrididae) infected by the fungus Metarhizium flavoviride Gams & Rozsypal.

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On the Infrared Behavior of the Pressure in Thermal Field Theories

We study non-perturbatively, via the Schwinger-Dyson equations, the leading infrared behavior of the pressure in the ladder approximation. This problem is discussed firstly in the context of a thermal scalar field theory, and the analysis is then extended to the Yang-Mills theory at high temperatures. Using the Feynman gauge, we find a system of two coupled integral equations for the gluon and ghost self-energies, which is solved analytically. The solutions of these equations show that the contributions to the pressure, when calculated in the ladder approximation, are finite in the infrared domain.Comment: 20 pages plus 4 figures available by request, IFUSP/P-100

Semiclassical Evolution of Dissipative Markovian Systems

A semiclassical approximation for an evolving density operator, driven by a "closed" hamiltonian operator and "open" markovian Lindblad operators, is obtained. The theory is based on the chord function, i.e. the Fourier transform of the Wigner function. It reduces to an exact solution of the Lindblad master equation if the hamiltonian operator is a quadratic function and the Lindblad operators are linear functions of positions and momenta. Initially, the semiclassical formulae for the case of hermitian Lindblad operators are reinterpreted in terms of a (real) double phase space, generated by an appropriate classical double Hamiltonian. An extra "open" term is added to the double Hamiltonian by the non-hermitian part of the Lindblad operators in the general case of dissipative markovian evolution. The particular case of generic hamiltonian operators, but linear dissipative Lindblad operators, is studied in more detail. A Liouville-type equivariance still holds for the corresponding classical evolution in double phase, but the centre subspace, which supports the Wigner function, is compressed, along with expansion of its conjugate subspace, which supports the chord function. Decoherence narrows the relevant region of double phase space to the neighborhood of a caustic for both the Wigner function and the chord function. This difficulty is avoided by a propagator in a mixed representation, so that a further "small-chord" approximation leads to a simple generalization of the quadratic theory for evolving Wigner functions.Comment: 33 pages - accepted to J. Phys.

A importância do perfil socioeconômico de criadores de ovinos de corte na elaboração de políticas públicas.

Resumo: A agropecuária brasileira é caracterizada pela versatilidade e heterogeneidade. São diversos os modos de produção e diferentes os tipos de criadores. Quando se avalia aspectos relacionados a criadores, sobretudo aqueles considerados familiares, a maioria dos estudos os retrata a partir de características econômicas e produtivas, suprimindo aspectos sociais importantes que os identificam enquanto grupos marcados por sociabilidades distintas. Dessa forma, objetivou-se com esse trabalho demonstrar a importância do perfil socioeconômico dos criadores de ovinos de corte e sua importância na formulação de políticas públicas. Para isso, foram entrevistados 336 criadores do município de Tauá-CE. O município possui um dos maiores rebanhos de ovinos do país e concentra um tradicional mercado de carne ovina no qual a "manta de Tauá" se destaca como principal produto. Observou-se que a maioria dos entrevistados se constitui sob núcleos familiares pequenos, estáveis, chefiados por homens com baixo grau de instrução e detentores de propriedades rurais com boa infraestrutura para moradia, mas pouco produtivas. Foram apontados ainda aspectos relacionados à juventude rural e suas consequências na sucessão familiar. [The importance of socio-economic profile of meat sheep breeders in the development of public policy]. Abstract: Brazilian agriculture is characterized by versatility and variety. There are several modes of production and different types of farmers When evaluating aspects of the creators, especially those considered farm family , most studies portrays them from economic and production characteristics , suppressing important social aspects that identify them as distinct groups marked by sociability. Thus, the aim of this work was to demonstrate the importance of the socioeconomic profile of sheep cutting and its importance in the formulation of public policies. For this, we interviewed 336 farmers in the municipality of Taua - CE. The city has one of the largest herds of sheep in the country and focuses a traditional lamb market in which the "Manta de Taua" stands out as the main product. It was observed that the majority of respondents in households are small, stable, headed by men with low levels of education and rural property owners with good infrastructure for housing, but not very productive. The aspects related to rural youth and their consequences on succession familiar were appointed