6,227 research outputs found

    A 3-form Gauge Potential in 5D in connection with a Possible Dark Sector of 4D-Electrodynamics

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    We here propose a 5-dimensional {\bf Abelian gauge} model based on the mixing between a U(1)U(1) potential and an Abelian 3-form field by means of a topological mass term. An extended covariant derivative is introduced to minimally couple a Dirac field to the U(1)U(1) potential, while this same covariant derivative non-minimally couples the 3-form field to the charged fermion. A number of properties are discussed in 5D; in particular, the appearance of a topological fermionic current. A 4-dimensional reduced version of the model is investigated and, { \bf in addition to the U(1)U(1) electric- and magnetic-sort of fields,} there emerges an extra set of electric- and magnetic-like fields which contribute a negative pressure and may be identified as a possible fraction of dark energy. The role of the topological fermionic current is also contemplated upon dimensional reduction from 5D to 4D. Other issues we present in 4 space-time dimensions are the emergence {\bf of a pseudo-scalar massive particle,} an extra massive neutral gauge boson,{\bf which we interpret as a kind of paraphoton}, and the calculation of spin- and velocity-dependent interparticle potentials associated to the exchange of the intermediate bosonic fields of the model.Comment: -- 30 pages -- L. P. R. Ospedal appears as a new co-author; modifications by inclusion of the gravitational sector and the attainment of a spin- and velocity-dependent potential as an application have been worked out in this Revised Versio

    Noncommutative Metafluid Dynamics

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    In this paper we define a noncommutative (NC) Metafluid Dynamics \cite{Marmanis}. We applied the Dirac's quantization to the Metafluid Dynamics on NC spaces. First class constraints were found which are the same obtained in \cite{BJP}. The gauge covariant quantization of the non-linear equations of fields on noncommutative spaces were studied. We have found the extended Hamiltonian which leads to equations of motion in the gauge covariant form. In addition, we show that a particular transformation \cite{Djemai} on the usual classical phase space (CPS) leads to the same results as of the \star-deformation with ν=0\nu=0. Besides, we will shown that an additional term is introduced into the dissipative force due the NC geometry. This is an interesting feature due to the NC nature induced into model.Comment: 11 page

    Nonlethal, Attenuated, Transfusion-Associated Graft-Versus-Host Disease in an Immunocompromised Child: Case Report and Review of the Literature

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    Transfusion-associated graft-versus-host disease (TA-GVHD) is a rare complication of transfusion of nonirradiated blood components. It usually affects children in high-risk groups, including those who have primary immunodeficiencies (PIDs). It usually presents with skin, hepatic, digestive, and hematologic involvement and is normally fatal

    Supersymmetrization of the Radiation Damping

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    We construct a supersymmetrized version of the model to the radiation damping \cite{03} introduced by the present authors \cite{ACWF}. We dicuss its symmetries and the corresponding conserved Noether charges. It is shown this supersymmetric version provides a supersymmetric generalization of the Galilei algebra obtained in \cite{ACWF}. We have shown that the supersymmetric action can be splited into dynamically independent external and internal sectors.Comment: 9 page

    Hamiltonian symplectic embedding of the massive noncommutative U(1) Theory

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    We show that the massive noncommutative U(1) theory is embedded in a gauge theory using an alternative systematic way, which is based on the symplectic framework. The embedded Hamiltonian density is obtained after a finite number of steps in the iterative symplectic process, oppositely to the result proposed using the BFFT formalism. This alternative formalism of embedding shows how to get a set of dynamically equivalent embedded Hamiltonian densities.Comment: 16 pages, no figures, revtex4, corrected version, references additione

    A germinação de alface romana é afetada por diferentes extratos de vermicomposto.

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    Diante da necessidade iminente de novos processos e tecnologias relacionadas a sementes para a agricultura organica, alternativas efecazes precisam ser estudadas. No presente trabalho avaliou-se os efeitos de dois diferentes extratos de vermicomposto e um tipo de lixiviado de vermicomposto sobre a germinação e crescimento inicial de alface romana

    Quantum pattern recognition with liquid-state nuclear magnetic resonance

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    A novel quantum pattern recognition scheme is presented, which combines the idea of a classic Hopfield neural network with adiabatic quantum computation. Both the input and the memorized patterns are represented by means of the problem Hamiltonian. In contrast to classic neural networks, the algorithm can return a quantum superposition of multiple recognized patterns. A proof of principle for the algorithm for two qubits is provided using a liquid state NMR quantum computer.Comment: updated version, Journal-ref adde

    Competição de capim-arroz (Echinochloa crusgalli) em arroz irrigado: épocas de controle e prejuízos à cultivar BRS Querência.

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    Extratos de vermicomposto na germinação e no crscimento inicial da alface romana.

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    No presente trabalho avaliou-se os efeitos de dois diferentes extratos de vermicomposto (TEA 50% e HUM 25%) e um tipo de lixiciado de vermicomposto (LV 25%) sobre a germinação e crescimento inicial de alface romana.Resumo expandido
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