Dirac-Hestenes spinor fields in Riemann-Cartan spacetime

In this paper we study Dirac-Hestenes spinor fields (DHSF) on a four-dimensional Riemann-Cartan spacetime (RCST). We prove that these fields must be defined as certain equivalence classes of even sections of the Clifford bundle (over the RCST), thereby being certain particular sections of a new bundle named Spin-Clifford bundle (SCB). The conditions for the existence of the SCB are studied and are shown to be equivalent to the famous Geroch's theorem concerning to the existence of spinor structures in a Lorentzian spacetime. We introduce also the covariant and algebraic Dirac spinor fields and compare these with DHSF, showing that all the three kinds of spinor fields contain the same mathematical and physical information. We clarify also the notion of (Crumeyrolle's) amorphous spinors (Dirac-K\"ahler spinor fields are of this type), showing that they cannot be used to describe fermionic fields. We develop a rigorous theory for the covariant derivatives of Clifford fields (sections of the Clifford bundle (CB)) and of Dirac-Hestenes spinor fields. We show how to generalize the original Dirac-Hestenes equation in Minkowski spacetime for the case of a RCST. Our results are obtained from a variational principle formulated through the multiform derivative approach to Lagrangian field theory in the Clifford bundle.Comment: 45 pages, special macros kapproc.sty and makro822.te

Mercado da energia eléctrica: uma modelação MPCC-NLP

O problema apresentado está relacionado com o mercado de energia eléctrica, modelado como um jogo de Stackelberg, onde a empresa líder de mercado tem o poder de manipular os preços e a capacidade de produção, de forma a maximizar o seu lucro. Devido às suas características particulares, o problema foi formulado como um Problema de Optimização com Restrições de Complementaridade (MPCC) e, posteriormente reestruturado num Problema de Programação Não Linear (NLP), com o intuito de tirar partido das suas propriedades, utilizando software específico

A MPCC-NLP approach for an electric power market problem

The electric power market is changing - it has passed from a regulated market, where the government of each country had the control of prices, to a deregulated market economy. Each company competes in order to get more clients and maximize its profits. This market is represented by a Stackelberg game with two firms, leader and follower, and the leader anticipates the reaction of the follower. The problem is formulated as a Mathematical Program with Complementarity Constraints (MPCC). It is shown that the constraint qualifications usually assumed to prove convergence of standard algorithms fail to hold for MPCC. To circumvent this, a reformulation for a nonlinear problem (NLP) is proposed. Numerical tests using the NEOS server platform are presented

Arquitetura da informação dos sites da Agropedia brasilis.

Agropedia brasilis é mais um dos esforços empreendidos na empresa para compatibilizar suas necessidades com as possibilidades oferecidas pelas tecnologias de informação e comunicação. O que se buscou neste trabalho foram os elementos necessários para uma estrutura inicial que atendesse aos interesses mais imediatos dos usuários

Generalization of Dirac Non-Linear Electrodynamics, and Spinning Charged Particles

In this note we generalized the Dirac non-linear electrodynamics, by introducing two potentials (namely, the vector potential A and the pseudo-vector potential gamma^5 B of the electromagnetic theory with charges and magnetic monopoles) and by imposing the pseudoscalar part of the product omega.omega* to be zero, with omega = A + gamma^5 B. We show that the field equations of such a theory possess a soliton-like solution which can represent a priori a "charged particle", since it is endowed with a Coulomb field plus the field of a magnetic dipole. The rest energy of the soliton is finite, and the angular momentum stored in its electromagnetic field can be identified --for suitable choices of the parameters-- with the spin of the charged particle. Thus this approach seems to yield a classical model for the charged (spinning) particle, which does not meet the problems met by earlier attempts in the same direction.Comment: standard LaTeX file; 16 pages; it is a corrected version of a paper appeared in Found. Phys. (issue in honour of A.O.Barut) 23 (1993) 46

Candida albicans antimicrobial and antibiofilm activity of novel endodontic solvents

Background: Candida albicans is the most prevalent fungi isolated in endodontic infections. In this study, the ability of C. albicans biofilm to tolerate the novel solvent mixtures methyl ethyl ketone (MEK)/tetrachloroethylene (TCE) and MEK/orange oil (OOil) sequentially to the standard irrigation of sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic (EDTA) was evaluated. Methods: Biofilm cell cultures of C. albicans SC 5314 were treated sequentially with NaOCl and EDTA and exposed to MEK/TCE or MEK/OOil. The effect of the antimicrobial treatment was evaluated using the disk diffusion method for planktonic culture, and the enumeration of colony-forming units (CFUs) and scanning electron microscope (SEM) for biofilm cell culture. Results: C. albicans mature biofilm (24 h) was significantly reduced in biomass and cell viability after solvent mixtures exposure, compared with the previous NaOCl and EDTA treatments. MEK/OOil combination caused a total reduction of biofilm, while with MEK/TCE, there was a 3-log (CFU/cm2) reduction compared with the sequence NaOCl and EDTA, and a 4-log (CFU/cm2) reduction compared with the control. Conclusions: The additional exposure of a preformed 24 h C. albicans biofilm to novel solvent mixtures MEK/TCE and MEK/OOil caused a positive antibiofilm impact, overcoming the performance of the conventional endodontic irrigating protocol.This article was supported by National Funds through FCT-Fundação para a Ciência e a Tecnologia, I.P., within CINTESIS, R&D Unit (reference UIDB/4255/2020). This work was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UIDB/04469/2020 unit and grant ref 2020.05720.BD for Liliana Fernandes; BioTecNorte operation (NORTE-01-0145-FEDER-000004) funded by the European Regional Development Fund under the scope of Norte2020-Programa Operacional Regional do Norte.info:eu-repo/semantics/publishedVersio

NANOPTICS: in-depth analysis of NANomaterials for OPTICal localized surface plasmon resonance sensing

Thin films containing metal (gold, silver, etc.) nanoparticles are important platforms for molecularsensing based on the localized surface plasmon resonance (LSPR) phenomenon. To support their usein high-resolution LSPR spectroscopy systems, a software package, called NANOPTICS, was developed.It performs a statistical analysis of the LSPR band of the films, employing central moments of the normalized spectral distribution of optical transmittance. LSPR band parameters, signal-to-noise ratio and refractive index sensitivity are the outputs. It is shown that NANOPTICS can be a powerful tool to perform fast diagnostics of LSPR-based sensors’ sensitivity and to analyse their response to target analytes.This work was supported by the Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Funding UIDB/04650/2020; and by the projects NANOSENSING POCI-01-0145-FEDER-016902, with FCT reference PTDC/FIS-NAN/1154/2014; and project NANO4BIO POCI-01-0145-FEDER-032299, with FCT reference PTDC/FIS-MAC/32299/2017. Marco S. Rodrigues acknowledges FCT for his PhD Scholarship, SFRH/BD/118684/2016. Joel Borges acknowledges FCT for his Researcher Contract from project NANO4BIO

Anatomia endobrônquica: estudo prospectivo das variações anatómicas da árvore traqueobrônquica

ResumoO conhecimento detalhado do normal padrão de ramificações da árvore traqueobrônquica é um requisito essencial para qualquer pneumologista. Os sistemas de classificação funcional que guiam a prática clínica corrente têm um carácter eminentemente estático e raramente contemplam referências aos desvios possíveis dentro do espectro normal.Por forma a caracterizar as variações anatómicas da árvore traqueobrônquica, os autores desenvolveram um estudo prospectivo que decorreu entre Fevereiro e Julho de 2009, onde se incluíram todos os doentes referenciados para realização de broncofibroscopias diagnósticas e/ou terapêuticas.Um total de 181 indivíduos foram incluídos no estudo tendo-se observado variantes anatómicas em 79 (43% do total). Globalmente observamos 20 diferentes variantes anatómicas. Estas variantes foram mais frequentemente observadas no lobo superior direito (16,6%). O lobo médio e a língula não foram sede de variantes anatómicas. A variante mais frequentemente observada foi o padrão bifurcado do lobo superior direito (13,8%).O presente estudo revelou uma elevada frequência de formas alternativas ao clássico padrão de ramificação traqueobrônquica. O conhecimento da tipologia, morfologia e frequência de expressão dessas variantes revela-se de extrema importância para o broncologista no estabelecimento das fronteiras da anatomia normal e na planificação de técnicas endoscópicas ou de procedimentos cirúrgicos.AbstractA comprehensive knowledge of the normal pattern of endobronchial branching is essential to any pulmonologist. The classification systems available are predominantly static descriptions and only seldom do they refer to possible variations within the normal spectrum.To evaluate all possible anatomical variants of the tracheobronchial tree we conducted a prospective study in our endoscopy unit between February, 1st and July, 10th (2009).A total of 181 individuals were included in the study. Anatomical variants were found to be present in 79 individuals (43% of total). Overall we found 20 different anatomical variants. Variations were more frequently found within the right upper lobe (16.6% of individuals). Middle lobe and lingula presented no variations. The variant most frequently found was the presence of a bifurcate pattern of the right upper bronchus (13.8%).The present study revealed a relatively high frequency of anatomical alternatives to the normal endobronchial branching pattern. Recognition of these variants and the frequency of their expression are fundamental for the bronchologist in establishing the limits of normal anatomy and preparing endobronchial techniques or surgical procedures