DIRAC CONFINEMENT BY A VARIATIONAL APPROACH

An analytical approximate method for the Dirac equation with confining power law scalar plus vector potentials, applicable to the problem of the relativistic quark confinement, is presented. The method consists in an improved version of a saddle-point variational approach and it is applied to the fundamental state of massless single quarks for some especial cases of physical interest. Our treatment emphasizes aspects such as the quantum-mechanical relativistic Virial theorem, the saddle-point character of the critical point of the expectation value of the total energy, as well as the Klein paradox and the behaviour of the saddle-point variational energies and wave functions.

Fluctuating dimension in a discrete model for quantum gravity based on the spectral principle

The spectral principle of Connes and Chamseddine is used as a starting point to define a discrete model for Euclidean quantum gravity. Instead of summing over ordinary geometries, we consider the sum over generalized geometries where topology, metric, and dimension can fluctuate. The model describes the geometry of spaces with a countable number n of points, and is related to the Gaussian unitary ensemble of Hermitian matrices. We show that this simple model has two phases. The expectation value , the average number of points in the Universe, is finite in one phase and diverges in the other. We compute the critical point as well as the critical exponent of . Moreover, the space-time dimension delta is a dynamical observable in our model, and plays the role of an order parameter. The computation of is discussed and an upper bound is found, < 2.

A refinement of the gauss-lucas theorem

The classical Gauss-Lucas Theorem states that all the critical points (zeros of the derivative) of a nonconstant polynomial p lie in the convex hull H of the zeros of p. It is proved that, actually, a subdomain of H contains the critical points of p. ©1998 American Mathematical Society.

Caracterização anatômica da folha de Cymbopogon citratus (DC.) Stapf (Poaceae) e perfil químico do óleo essencial

The objective of the work was to accomplish an anatomical and ultrastructural study of mature leaf of Cymbopogon citratus (Poaceae) and analyze the essential oil through Gas Chromatography (GC). For the anatomical study, the material was fixed in FAA, followed bytheethyl dehydration and infiltration of the material in synthetic resin. For the ultrastructural study, the material was fixed and Kamovsky, dehydrated in acetone, dried to the critical point and metallized. For the analysis in GC, the essential oil it was obtained by steam distillation of leaves and analyzed by Gas Chromatography. Through the anatomical study it was observed that the faces of mesophyll are distinctly, the bulliform cells occupy the adaxial surface of the leaf and in the medium region are situated the biggest vascular bundles involved by sclerenchymatous hem with extensions reaching both epidermis. Between the biggest vascular bundles are observed three to five small vascular bundles, linkage only in the abaxial epidermis. Shortly, pointed and unicellular structures, called prickle-hair, had been observed inserted above the veins and micro-hair, that they consist of a long basal cell and an oval distal cell, that are located between the regions of vascular bundles. The chromatogram sample shows that the analyzed essential oil presented three majority components, responsible for 87% of the relative composition of the oil. These components are monoterpenos, justifying the strong smell of the essential oil.

Economic Survey of Latin America and the Caribbean 2008-2009: Policies for creating quality jobs

Includes bibliography

Ferromagnetism and superconductivity in CeFeAs 1-xP xO (0≤x≤40)

We report on superconductivity in CeFeAs 1-xP xO and the possible coexistence with Ce ferromagnetism (FM) in a small homogeneity range around x=30% with ordering temperatures of T SC≅T C≅4 K. The antiferromagnetic (AFM) ordering temperature of Fe at this critical concentration is suppressed to TNFe≈40 K and does not shift to lower temperatures with a further increase of the P concentration. Therefore, a quantum-critical-point scenario with TNFe→0 K which is widely discussed for the iron based superconductors can be excluded for this alloy series. Surprisingly, thermal expansion and x-ray powder diffraction indicate the absence of an orthorhombic distortion despite clear evidence for short-range AFM Fe ordering from muon-spin-rotation measurements. Furthermore, we discovered the formation of a sharp electron spin resonance signal unambiguously connected with the emergence of FM ordering. © 2012 American Physical Society.

Qualidade do leite: Utopia sem um programa sério de monitoramento da ocorrência de mastite bovina

Bovine mastitis is still a costly issue in dairy farms, besides public health aspects considering the pathogen transmission to humans. Its multiple etiology with a high number of pathogens involved, demands a rigorous control program for monitoring and milk quality control, based on diagnostic actions and epidemiological vigilance regarding parameters which indirectly are associated with the occurrence of mastitis in dairy herds, as the California Mastitis Test (CMT) and Somatic Cell Count (SCC/mL of milk), of individual milk samples obtained from each cow, and from bulk tank which also allows the Total Bacteria Count (TBC), usually related to the incidence of mastitis, especially in subclinical cases. It is important to reinforce the microbiological milk exam, also to stress the importance of the milking process as a critical point, and to determine risk factors for mastitis. Based on these aspects, this review is presented with the aim to obtain high quality milk products, compromising the personal enrolled in milk production to be conscious that milk quality depends on all, inclusive the consumers which are the final element in the milk production chain.

Problemas de valor de contorno não clássicos: uma abordagem usando funções de Green

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Perspectivas para uma teoria geral dos novos direitos: uma leitura crítica sobre a biodiversidade e os conhecimentos tradicionais associados

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo vocabular de petições jurídicas: ornamentação e rebuscamento

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

As imagens da Espanha em A jangada de pedra (1986), de José Saramago

Pós-graduação em Letras - FCLAS

Ocorrência de Salmonella spp. em carcaças e vísceras de rãs (Rana catesbeiana - Rã de Touro): avaliação do processo de abate

Pós-graduação em Medicina Veterinária - FMVZ

Ser docente: a experiência em uma Faculdade de Serviço Social privada

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Tutela penal e teoria crítica de direitos humanos: uma intersecção crítico-dialética marginal

Pós-graduação em Direito - FCHS

Discursos de professores e de livros didáticos de física do nível médio em abordagens sobre o ensino da física moderna e contemporânea: algumas implicações educacionais

Pós-graduação em Educação para a Ciência - FC