2,854 research outputs found

    Utilizar as recomendações técnicas em lugar de formulações tradicionais de fertilizantes - uma decisão com implicações técnicas e econômicas.

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    bitstream/item/31606/1/comunicado82.pd

    Adubação e calagem - uma proposta de uso racional (Rio Grande do Sul).

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    bitstream/item/119467/1/FOL-04317.pdfTrabalho apresentado no I Seminário Multiprofissional do Setor Publico Agropecuário Estadual, Porto Alegre, 1988

    Estudo da influência de seqüências polipeptídicas e de códons na determinação da estrutura secundária de proteínas.

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    O propósito desse trabalho foi descrever e quantificar os casos de polipeptídicos idênticos em diferentes estruturas secundárias, encontrados em banco de dados de estrutura: Protein Data Bank (PDB).bitstream/CNPTIA/9901/1/comuntec42.pdfAcesso em: 30 maio 2008

    Microscopic Conductivity of Lattice Fermions at Equilibrium. Part II: Interacting Particles

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    We apply Lieb–Robinson bounds for multi-commutators we recently derived (Bru and de Siqueira Pedra, Lieb–Robinson bounds for multi-commutators and applications to response theory, 2015) to study the (possibly non-linear) response of interacting fermions at thermal equilibrium to perturbations of the external electromagnetic field. This analysis leads to an extension of the results for quasi-free fermions of (Bru et al. Commun Pure Appl Math 68(6):964–1013, 2015; Bru et al. J Math Phys 56:051901-1–051901-51, 2015) to fermion systems on the lattice with short-range interactions. More precisely, we investigate entropy production and charge transport properties of non-autonomous C*-dynamical systems associated with interacting lattice fermions within bounded static potentials and in presence of an electric field that is time and space dependent. We verify the 1st law of thermodynamics for the heat production of the system under consideration. In linear response theory, the latter is related with Ohm and Joule’s laws. These laws are proven here to hold at the microscopic scale, uniformly with respect to the size of the (microscopic) region where the electric field is applied. An important outcome is the extension of the notion of conductivity measures to interacting fermions

    Weak* Hypertopologies with Application to Genericity of Convex Sets

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    We propose a new class of hypertopologies, called here weak∗^{\ast } hypertopologies, on the dual space X∗\mathcal{X}^{\ast } of a real or complex topological vector space X\mathcal{X}. The most well-studied and well-known hypertopology is the one associated with the Hausdorff metric for closed sets in a complete metric space. Therefore, we study in detail its corresponding weak∗^{\ast } hypertopology, constructed from the Hausdorff distance on the field (i.e. R\mathbb{R} or C\mathbb{C}) of the vector space X\mathcal{X} and named here the weak∗^{\ast }-Hausdorff hypertopology. It has not been considered so far and we show that it can have very interesting mathematical connections with other mathematical fields, in particular with mathematical logics. We explicitly demonstrate that weak∗^{\ast } hypertopologies are very useful and natural structures\ by using again the weak∗^{\ast }-Hausdorff hypertopology in order to study generic convex weak∗^{\ast }-compact sets in great generality. We show that convex weak∗^{\ast }-compact sets have generically weak∗^{\ast }-dense set of extreme points in infinite dimensions. An extension of the well-known Straszewicz theorem to Gateaux-differentiability (non necessarily Banach) spaces is also proven in the scope of this application.FAPESP (2017/22340-9) CNPq (309723/2020-5) by the Basque Government through the grant IT641-13 MTM2017-82160-C2-2-P

    Universal Bounds for Large Determinants from Non–Commutative Ho ̈lder Inequalities in Fermionic Constructive Quantum Field Theory

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    Efficiently bounding large determinants is an essential step in non–relati- vistic fermionic constructive quantum field theory, because, together with the summability of the interaction and the covariance, it implies the abso- lute convergence of the perturbation expansion of all correlation functions in terms of powers of the strength u ∈ R of the interparticle interaction. We provide, for large determinants of fermionic convariances, sharp bounds which hold for all (bounded and unbounded, the latter not being limited to semibounded) one–particle Hamiltonians. We find the smallest universal determinant bound to be exactly 1. In particular, the convergence of pertur- bation series at u = 0 of any fermionic quantum field theory is ensured by the decay properties of the covariance and the interparticle interaction alone. Our proofs use Ho ̈lder inequalities for general non–commutative Lp–spaces derived by Araki and Masuda [AM]

    Lieb–Robinson Bounds for Multi–Commutators and Applications to Response Theory

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    We generalize to multi-commutators the usual Lieb–Robinson bounds for commutators. In the spirit of constructive QFT, this is done so as to allow the use of combinatorics of minimally connected graphs (tree expansions) in order to estimate time-dependent multi-commutators for interacting fermions. Lieb–Robinson bounds for multi-commutators are effective mathematical tools to handle analytic aspects of the dynamics of quantum particles with interactions which are non-vanishing in the whole space and possibly time-dependent. To illustrate this, we prove that the bounds for multi-commutators of order three yield existence of fundamental solutions for the corresponding non-autonomous initial value problems for observables of interacting fermions on lattices. We further show how bounds for multi-commutators of an order higher than two can be used to study linear and non-linear responses of interacting fermions to external perturbations. All results also apply to quantum spin systems, with obvious modifications. However, we only explain the fermionic case in detail, in view of applications to microscopic quantum theory of electrical conduction discussed here and because this case is technically more involved.FAPESP under Grant 2013/13215-5 Basque Government through the grant IT641-13 SEV-2013-0323 MTM2014-5385

    Macroscopic Dynamics of the Strong-Coupling BCS-Hubbard Model

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    The aim of the current paper is to illustrate, in a simple example, our recent, very general, rigorous results on the dynamical properties of fermions and quantum-spin systems with long-range, or mean-field, interactions, in infinite volume. We consider here the strong-coupling BCS-Hubbard model, because this example is very pedagogical and, at the same time, physically relevant for it highlights the impact of the (screened) Coulomb repulsion on (ss-wave) superconductivity.FAPESP (2017/22340-9); CNPq (309723/2020-5); by the Basque Government through the grant IT641-13; MTM2017-82160-C2-2-
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