266 research outputs found

    Scattering and self-adjoint extensions of the Aharonov-Bohm hamiltonian

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    We consider the hamiltonian operator associated with planar sec- tions of infinitely long cylindrical solenoids and with a homogeneous magnetic field in their interior. First, in the Sobolev space H2\mathcal H^2, we characterize all generalized boundary conditions on the solenoid bor- der compatible with quantum mechanics, i.e., the boundary conditions so that the corresponding hamiltonian operators are self-adjoint. Then we study and compare the scattering of the most usual boundary con- ditions, that is, Dirichlet, Neumann and Robin.Comment: 40 pages, 5 figure

    Biological properties of natural dyes

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    El propósito del presente trabajo es evaluar el aumento en el uso de colorantes naturales en la industria alimentaria y la posibilidad de desarrollar nuevos medicamentos gracias a sus diversas propiedades biológicas. La presente revisión aborda las principales actividades biológicas observadas en los carotenoides y las antocianinas y pone énfasis en el amplio uso del extracto de achiote o bija (Bixa orellana L.) y de la curcumina (Curcuma longa) en estas actividades.The aim of the present work is to evaluate the increase uses of natural colorants in the nourishing industry and in the promising of new medicines due its several biological properties. In this review the main biological activities observed in the carotenóids and the anthocyianins are boarded, with emphasis in the wide use of the urucum‘s extract from Bixa orellana L.) and of curcumin from Curcuma longa in these activities

    Biological properties of natural dyes

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    El propósito del presente trabajo es evaluar el aumento en el uso de colorantes naturales en la industria alimentariay la posibilidad de desarrollar nuevos medicamentos gracias a sus diversas propiedades biológicas. La presenterevisión aborda las principales actividades biológicas observadas en los carotenoides y las antocianinas y poneénfasis en el amplio uso del extracto de achiote o bija (Bixa orellana L.) y de la curcumina (Curcuma longa) en estasactividadesThe aim of the present work is to evaluate the increase uses of natural colorants in the nourishing industry and in thepromising of new medicines due its several biological properties. In this review the main biological activities observedin the carotenóids and the anthocyianins are boarded, with emphasis in the wide use of the urucum‘s extract from Bixaorellana L.) and of curcumin from Curcuma longa in these activities

    Produção de polibenzoxazina a partir da lignina do bagaço da cana-de-açúcar.

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    Este Comunicado Técnico visa apresentar um processo para produção de uma resina benzoxazina, em escala de laboratório, a partir da lignina extraída do bagaço da cana-de-açúcar.bitstream/item/206830/1/CT-261.pd

    Characteristcs chemical and soil salinization in the Irrigated District of California, SE, Brazil

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    O manejo inadequado da irrigação pode resultar no acúmulo de sais no solo, cuja intensidade depende da qualidade da água utilizada na irrigação, da fração de lixiviação adotada e da demanda evapotranspirativa da região. O presente trabalho teve como objetivo avaliar os atributos físicos e químicos dos solos do perímetro irrigado Califórnia, localizado no extremo noroeste do Estado de Sergipe. Para tal, foram realizadas amostragens em 42 lotes, correspondendo a 16,4% dos lotes deste perímetro. As maiores concentrações de sais e de sódio ocorreram na camada superficial (0–0,2m) do solo, o que evidenciou a falta de um manejo da irrigação adequado visando ao controle da salinidade. O aumento do pH do solo foi correlacionado significativamente com a porcentagem de sódio trocável, atingindo valores acima de 9,5. Correlações positivas significativas foram observadas entre a condutividade elétrica e os teores de Ca e Mg, indicando que sais desses íons podem estar se acumulando no solo pela ascensão do lençol freático, associado à ausência de lixiviação e drenagem. _________________________________________________________________________________________ ABSTRACT: The improper irrigation management may result in the accumulation of salts in the soil profile, which intensity depends on the irrigation water quality, the leaching fraction adopted and on the evapotranspiration demand of the region. The objective of the present study was to study the physical and chemical characteristics of the soils in the irrigated district of California, located in the northwest of the State of Sergipe. Thus, soil sampling were made in 54 lots, corresponding to 16.4% of the lots of this district. The highest salt and sodium concentrations occurred in the shallowest soil layer (0–0.2m), evidencing the lack of an appropriate irrigation management in order to control the salinity build up. The increasing of the soil pH was significantly correlated to the exchangeable sodium percentage, reaching values over 9.5. Significant positive correlations were observed between the electrical conductivity and the Ca and Mg content, indicating that salts of both ions could be accumulating in soil by the capillary rise of the water table, associated to the lack of leaching and drainage

    Long-Baseline Neutrino Facility (LBNF) and Deep Underground Neutrino Experiment (DUNE) Conceptual Design Report Volume 2: The Physics Program for DUNE at LBNF

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    The Physics Program for the Deep Underground Neutrino Experiment (DUNE) at the Fermilab Long-Baseline Neutrino Facility (LBNF) is described

    On the running coupling constant in QCD

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    We try to review the main current ideas and points of view on the running coupling constant in QCD. We begin by recalling briefly the classic analysis based on the Renormalization Group with some emphasis on the exact solutions of the RG equation for a given number of loops, in comparison with the usual approximate expressions. We give particular attention to the problem of eliminating the unphysical Landau singularities, and of defining a coupling that remains significant at the infrared scales. We consider various proposals of couplings directly related to the quark-antiquark potential or to other physical quantities (effective charges) and discuss optimization in the choice of the scale parameter and of the RS. Our main focus is, however, on dispersive methods, their application, their relation with non-perturbative effects. We try also to summarize the main results obtained by Lattice simulations in various MOM schemes. We conclude briefly recalling the traditional comparison with the experimental data.Comment: 75 pages, 8 figures. Corrected typos, added references, replaced 1 figure. Accepted for publication in Progress in Particle and Nuclear Physic

    The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

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    The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure
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