Spin-glass behaviour on random lattices

The ground-state phase diagram of an Ising spin-glass model on a random graph with an arbitrary fraction $w$ of ferromagnetic interactions is analysed in the presence of an external field. Using the replica method, and performing an analysis of stability of the replica-symmetric solution, it is shown that $w=1/2$, correponding to an unbiased spin glass, is a singular point in the phase diagram, separating a region with a spin-glass phase ($w<1/2$) from a region with spin-glass, ferromagnetic, mixed, and paramagnetic phases ($w>1/2$)

Environmental comfort indicators for school buildings in sustainability assessment tools

Decades ago, the only requirement to construct a building was to give men the right conditions for the execution of their work or leisure activities. With the development of knowledge about the internal and external environments of buildings, other requirements have been added such as the issue of user comfort. New construction techniques have been incorporated and new products have been created to improve internal environment comfort. This research addressed the importance of using indicators related to environmental comfort in sustainability assessment tools applied to school buildings. It also considered the importance of environmental issues for the good performance of human beings, and the harmonious coexistence of the comfort indicators indoor air quality, thermal comfort, visual comfort, acoustic comfort and ergonomic comfort based on data gathered in research carried out with users of high schools (only students). This research was carried out in two different cities of different countries, Guimarães (Portugal) and Juiz de Fora (Brazil), that have similar characteristics of teaching standards and climate conditions (temperature and air humidity). In this study, interviews were made through questionnaires and, later, the information collected was analyzed. This study demonstrates the need to include an ergonomic indicator for school buildings in sustainability assessment tools.The corresponding author wants to thank: the teacher and Administrative Director of Francisco de Holanda High School, Abílio Ferreira, for showing me the school and giving all the necessary information, always with great attention; Parque Escolar Company (EPE) for supplying the necessary material for the execution of the work; and Mrs. Catarina Araujo for helping me in the conception of this article. This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.info:eu-repo/semantics/publishedVersio

The inclusion of sustainability awareness indicator in assessment tools for high school buildings

The growing debate about global environmental problems is evident in several spheres of society. The concern for the future of the planet is used as a political slogan, inspiring the creation of new laws and encouraging academic research that serves this purpose, as well as increasing the number of government agencies concerned with this matter. The 21st century is considered the ?century of sustainable development?. Sustainability education in high schools has the potential to make the benefits of civil construction more visible to society and media by showing students, parents, and communities in general how sustainability in the built environment can improve their lives in economic, social, and environmental aspects. This study was applied in three high schools of Juiz de Fora (Brazil) and Guimarães (Portugal). These high schools have similar characteristics regarding teaching patterns and commitment to strengthening sustainability in their respective regions and reflect their socio-economic conditions, governmental strategies, everyday habits, and cultural attributes. The information was collected through questionnaires applied to high school students in 2017. This paper shows the need for including an indicator of sustainability awareness in sustainability assessment tools for high school buildings.Federal University of Juiz de Fora. (UFJF, Universidade Federal de Juiz de Fora, Brazil).info:eu-repo/semantics/publishedVersio

Diluted antiferromagnet in a ferromagnetic enviroment

The question of robustness of a network under random ``attacks'' is treated in the framework of critical phenomena. The persistence of spontaneous magnetization of a ferromagnetic system to the random inclusion of antiferromagnetic interactions is investigated. After examing the static properties of the quenched version (in respect to the random antiferromagnetic interactions) of the model, the persistence of the magnetization is analysed also in the annealed approximation, and the difference in the results are discussed

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.

Decoherence of Semiclassical Wigner Functions

The Lindblad equation governs general markovian evolution of the density operator in an open quantum system. An expression for the rate of change of the Wigner function as a sum of integrals is one of the forms of the Weyl representation for this equation. The semiclassical description of the Wigner function in terms of chords, each with its classically defined amplitude and phase, is thus inserted in the integrals, which leads to an explicit differential equation for the Wigner function. All the Lindblad operators are assumed to be represented by smooth phase space functions corresponding to classical variables. In the case that these are real, representing hermitian operators, the semiclassical Lindblad equation can be integrated. There results a simple extension of the unitary evolution of the semiclassical Wigner function, which does not affect the phase of each chord contribution, while dampening its amplitude. This decreases exponentially, as governed by the time integral of the square difference of the Lindblad functions along the classical trajectories of both tips of each chord. The decay of the amplitudes is shown to imply diffusion in energy for initial states that are nearly pure. Projecting the Wigner function onto an orthogonal position or momentum basis, the dampening of long chords emerges as the exponential decay of off-diagonal elements of the density matrix.Comment: 23 pg, 2 fi

Hidrólise de diacetato de fluoresceína como bioindicador da qualidade de solo de várzea subtropical.

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