Spin-1 Particles with Light-Front Approach

For the vector sector, i.e, mesons with spin-1, the electromagnetic form factors and anothers observables are calculated with the light-front approach. However, the light-front quantum field theory have some problems, for example, the rotational symmetry breaking. We solve that problem added the zero modes contribuition to the matrix elements of the electromagnetic current, besides the valence contribuition. We found that among the four independent matrix elements of the plus component in the light-front helicity basis only the $0\to 0$ one carries zero mode contributions.Comment: 5 pages. 3 Figures, use latex and EPJ styl

Distribuição das Diatomáceas Modernas nos Sedimentos da Baía de Guanabara e Áreas Oceânicas, Rio de Janeiro (Brasil)

One hundred and fifty three superficial sediments were collected in Guanabara Bay to physical-chemistry and diatom analyses in the ambit to Monitoring Project (CENPES/PETROBRAS). A total of 146 taxa of diatoms were identified where the most frequent taxa in Guanabara Bay were Amphora spp., Coscinodiscus spp. and Navicula yarrensis var. yarrensis. These species are potentially harmful that might harm fisheries and mariculture during blooms. The values of ecological indexes like richness and diversity followed the estuarine gradient were the higher values were found in the mouth and de low in the inner part. The multivariate analyzes permitted recognize seven diatom assemblages in the bay. The DCA analyze shows the most influence in the distribution of assemblages were the depth and pH. The diatom assemblages analyze proved to be an efficient tool in the environmental diagnosis of Guanabara Bay.Cento e ciquenta e três amostras de sedimento superficial da Baía de Guanabara foram coletadas durante o Projeto de Monitoramento Ambiental (CENPES/PETROBRAS). Foram identificados 146 táxons de diatomáceas onde as espécies mais abundantes foram Amphora spp., Coscinodiscus spp. e Navicula yarrensis var. yarrensis. Estas espécies identificadas são potencialmente tóxicas e podem prejudicar peixes e a maricultura durante períodos de florescência. Os índices ecológicos de riqueza e diversidade acompanharam o gradiente estuarino sendo maior na entrada da baía e baixos na região interna. As análises multivariadas permitiram reconhecer sete assembléias de diatomáceas na baía. As análises em DCA mostrou que os parâmetros ambientais mais influentes na distribuição das assembléias foram a profundidade e o pH. Os resultados obtidos mostraram que as assembléias de diatomáceas são uma importante ferramenta na caracterização ambiental da Baía de Guanabara

Sharp Hessian estimates for fully nonlinear elliptic equations under relaxed convexity assumptions, oblique boundary conditions and applications

In this work we derive global estimates for viscosity solutions to fully nonlinear elliptic equations under relaxed structural assumptions on the governing operator which are weaker than convexity and oblique boundary conditions and under suitable assumptions on the dat. Our approach makes use of geometric tangential methods, which consists of importing "fine regularity estimates" from a limiting profile, i.e., the Recession operator, associated with the original second order one via compactness and stability procedures. As a result, we devote a special attention to the borderline scenario. In such a setting, we prove that solutions enjoy BMO type estimates for their second derivatives. In the end, as another application of our findings, we obtain Hessian estimates to obstacle type problems under oblique boundary conditions and no convexity assumptions, which may have their own mathematical interest. A density result in a suitable class of viscosity solutions will be also addressed

Mitigation of numerical Cerenkov radiation and instability using a hybrid finite difference-FFT Maxwell solver and a local charge conserving current deposit

A hybrid Maxwell solver for fully relativistic and electromagnetic (EM) particle-in-cell (PIC) codes is described. In this solver, the EM fields are solved in $k$ space by performing an FFT in one direction, while using finite difference operators in the other direction(s). This solver eliminates the numerical Cerenkov radiation for particles moving in the preferred direction. Moreover, the numerical Cerenkov instability (NCI) induced by the relativistically drifting plasma and beam can be eliminated using this hybrid solver by applying strategies that are similar to those recently developed for pure FFT solvers. A current correction is applied for the charge conserving current deposit to correctly account for the EM calculation in hybrid Yee-FFT solver. A theoretical analysis of the dispersion properties in vacuum and in a drifting plasma for the hybrid solver is presented, and compared with PIC simulations with good agreement obtained. This hybrid solver is applied to both 2D and 3D Cartesian and quasi-3D (in which the fields and current are decomposed into azimuthal harmonics) geometries. Illustrative results for laser wakefield accelerator simulation in a Lorentz boosted frame using the hybrid solver in the 2D Cartesian geometry are presented, and compared against results from 2D UPIC-EMMA simulation which uses a pure spectral Maxwell solver, and from OSIRIS 2D lab frame simulation using the standard Yee solver. Very good agreement is obtained which demonstrates the feasibility of using the hybrid solver for high fidelity simulation of relativistically drifting plasma with no evidence of the numerical Cerenkov instability

Ensino-aprendizagem de Óptica Geométrica através de uma sequência didática vygotskyana

A presente pesquisa tem como objeto de estudo o ensino de óptica geométrica a partir de um kit contendo peças de acrílico (lentes e prismas), espelhos, laser, e outros materiais, cuja aplicação se orienta por princípios teóricos vygotskyanos, com objetivo de proporcionar a aprendizagem de estudantes do 2º ano do Ensino Médio, quando em contato com experimentos relacionados à luz. Os conteúdos abordados na aplicação do produto educacional são: reflexão e refração da luz, convergência e divergência, projeções com obstáculos, composição e decomposição da luz.  Para o desenvolvimento dessa pesquisa será utilizada como base teórica a Teoria Sócio-Interacionista de Lev Vygotsky, haja vista que se trata de manuseio de instrumentos (objetos do kit), oralidade (arguições, falas dos alunos e do professor), esclarecimentos mais aprofundados por parte do professor, para compreender certos fenômenos e conceitos, quais os alunos não conseguem entender a princípio ”“ utilizando-se dessa forma da Zona de Desenvolvimento Proximal ”“ ZDP (PAULA, 2009). Barone (2011) ao abordar sobre a Psicologia sócio-histórica de Vygotsky comenta que os conceitos científicos são generalizados a partir de conceitos preliminares. A experiência, portanto, leva o experimentador a assimilar o novo com algo já conhecido. Sobre essa ótica, o professor atua como mediador, promovendo o contato entre o aluno e o objeto de pesquisa

Arterial vascularization of the thoracic lobes of the thymus in stillborns of the lineage C40

As origens e distribuições das artérias que vascularizaram os lobos torácicos do timo foram estudadas em fetos de 30 suínos da linhagem C40, sendo 12 machos e 18 fêmeas. Os exemplares tiveram o sistema arterial preenchido com solução aquosa a 50% de Neoprene Látex corado e, em seguida, foram submetidos à fixação em solução aquosa a 10% de formaldeído. Os lobos torácicos do timo foram vascularizados por ramos diretos das artérias torácica interna direita (63,33%) e esquerda (53,33%), subclávia esquerda (3,33%), vertebral esquerda (3,33%), cervical superficial direita (3,33%) e esquerda (3,33%), carótida comum esquerda (3,33%), coronária direita (3,33%) e pelos troncos braquiocefálico (33,33%) e costocervical (3,33%). Observaram-se ainda os ramos indiretos das artérias torácica interna direita (70%) e esquerda (76,67%), subclávia esquerda (23,33%), cervical superficial esquerda (3,33%) e do arco aórtico (6,67%).The origins and distributions of the arteries that vascularization the thoracic lobes of the thymus, right and left, were studied in 30 swine of the lineage C40, fetus, being 12 males and 18 females. The animals had the arterial system filled with aqueous colored solution in a 50% of Neoprene Latex, and than were fixed in 10% aqueous solution formaldehyde. The thoracic lobes of thymus were vascularization by direct branches of the right (53.33%) and left (63.33%) internal thoracic arteries, left subclavian (3.33%), left vertebral (3.33%), right (3.33%) and left (3.33%) superficial cervical, left common carotid (3.33%), right coronary (3.33%) and brachiocephalic trunk (33.33%) and costocervical trunk (3.33%). The right internal thoracic arteries (70%) and left internal thoracic (76.67%), left subclavian (23.33%), left superficial cervical (3.33%) of the aortic arch (6.67%) provided indirect branches for the correspondent thoracic lobes of the thymus in each side