A new model for gravitational potential perturbations in disks of spiral galaxies. An application to our Galaxy

We propose a new, more realistic, description of the perturbed gravitational potential of spiral galaxies, with spiral arms having Gaussian-shaped groove profiles. We investigate the stable stellar orbits in galactic disks, using the new perturbed potential. The influence of the bulge mass on the stellar orbits in the inner regions of a disk is also investigated. The new description offers the advantage of easy control of the parameters of the Gaussian profile of its potential. We find a range of values for the perturbation amplitude from 400 to 800 km^2 s^{-2} kpc^{-1} which implies a maximum ratio of the tangential force to the axisymmetric force between 3% and 6%, approximately. Good self-consistency of arm shapes is obtained between the Inner Lindblad resonance (ILR) and the 4:1 resonance. Near the 4:1 resonance the response density starts to deviate from the imposed logarithmic spiral form. This creates bifurcations that appear as short arms. Therefore the deviation from a perfect logarithmic spiral in galaxies can be understood as a natural effect of the 4:1 resonance. Beyond the 4:1 resonance we find closed orbits which have similarities with the arms observed in our Galaxy. In regions near the center, in the presence of a massive bulge, elongated stellar orbits appear naturally, without imposing any bar-shaped potential, but only extending the spiral perturbation a little inward of the ILR. This suggests that a bar is formed with a half-size around 3 kpc by a mechanism similar to that of the spiral arms. The potential energy perturbation that we adopted represents an important step in the direction of self-consistency, compared to previous sine function descriptions of the potential. Our model produces a realistic description of the spiral structure, able to explain several details that were not yet understood.Comment: 12 pag., 11 fig. Accepted for publication in A&A, 2012 December 1

Equivalence between the Lovelock-Cartan action and a constrained gauge theory

We show that the four-dimensional Lovelock-Cartan action can be derived from a massless gauge theory for the $SO(1,3)$ group with an additional BRST trivial part. The model is originally composed by a topological sector and a BRST exact piece and has no explicit dependence on the metric, the vierbein or a mass parameter. The vierbein is introduced together with a mass parameter through some BRST trivial constraints. The effect of the constraints is to identify the vierbein with some of the additional fields, transforming the original action into the Lovelock-Cartan one. In this scenario, the mass parameter is identified with Newton's constant while the gauge field is identified with the spin-connection. The symmetries of the model are also explored. Moreover, the extension of the model to a quantum version is qualitatively discussed.Comment: 17 pages. No figures. Final version accepted for publication at the EPJ

Horner's Syndrome as a Complication of Ultrasound-Guided Central Cannulation: A Case Report

Cannulation of the internal jugular vein is often necessary for the management of critically ill patients. Despite being a very common procedure and performed more and more safely, several complications still occur. Horner's Syndrome (HS) is one of those complications described before the use of ultrasound as a method of guidance. HS is caused by functional interruption of sympathetic nerve supply to the eye, leading to a classic triad of ipsilateral ptosis, miosis, and anhidrosis. We present the case of a patient, in need of emergent surgery to control the hemorrhagic focus after delivery, with a transient HS secondary to internal jugular vein cannulation under real-time ultrasound guidance.info:eu-repo/semantics/publishedVersio

Number of carpels in the pollination efficiency of sour passion fruit.

RESUMO: As flores do maracujazeiro-azedo normalmente apresentam três carpelos, porém há indivíduos com maior quantidade de carpelos em suas estruturas reprodutivas e pouco se sabe da influência dessa característica na cultura. Plantas de maracujazeiro-azedo (Passiflora edulis Sims, cultivar BRS Sol do Cerrado), que apresentam flores com três, quatro e cinco carpelos, foram avaliadas quanto: à eficiência de polinização manual e natural; à frequência dos diferentes tipos de flores no pomar; à inclinação dos estiletes. As frequências de flores com três, quatro e cinco carpelos também foram avaliadas nos genitores da referida cultivar. Não foram observadas diferenças estatísticas significativas na eficiência de polinização entre os diferentes tipos de flores, as quais apresentaram médias acima de 90%, destacando-se a média de 100% das flores com cinco carpelos. As flores com três carpelos são predominantes na cultivar estudada, representando 88,93%, porém flores com quatro e cinco carpelos não apresentaram estiletes sem inclinação, enquanto flores com três carpelos apresentaram taxa de 11,83%. Apenas o genitor masculino da cultivar destaca-se quanto à taxa de flores com quatro e cinco carpelos, sendo de 37,33% e 7,33%, respectivamente. Assim, flores com quatro e cinco carpelos representam importantes características para o melhoramento genético do maracujazeiro. ABSTRACT: Passion fruit flowers usually have three carpels, but there are individuals with greater amount of carpels in their reproductive structures and little is known about the influence of this characteristic on this crop. Sour passion fruit (Passiflora edulis Sims, ?BRS Sol do Cerrado? cultivar) plants presenting flowers with three, four and five carpels were evaluated regarding the following characteristics: manual and natural pollination efficiency; frequency of different types of flowers in the orchard; and inclination of styles. Frequencies of flowers with three, four and five carpels were also evaluated in ?BRS Sol do Cerrado? genitors. There were no statistically significant differences in pollination efficiency among the different types of flowers, which presented averages above 90%, especially flowers with five carpels, with 100% efficiency. Flowers with three carpels are predominant in ?BRS Sol do Cerrado? cultivar, representing 88.93%, but flowers with four and five carpels did not show styles without inclination, whereas flowers with three carpels presented rate of 11.83%. Only the male genitor stands out for the rate of flowers with four and five carpels, being 37.33% and 7.33%, respectively. Thus, flowers with four and five carpels represent important characteristics for passion fruit breeding programs

Tecnologia de mudas enxertadas de maracujazeiro azedo para controle de doenças causadas por fusarium spp. no Mato Grosso - a experiência da Coopernova.

Entre as doenças mais sérias do maracujazeiro no Mato Grosso, merecem destaque a murcha e a podridão-do-pé causadas por Fusarium oxysporum f. sp. passiflorae e Fusarium solani, respectivamente. Até o momento não existem cultivares resistentes nem controle químico satisfatório para estas doenças. Por esse motivo, não se recomenda o cultivo do maracujazeiro em áreas com alta incidência destas doenças. A ocorrência destas doenças faz com que muitos produtores sintam-se desestimulados com a cultura do maracujazeiro, considerando que as plantas morrem no início do seu período produtivo

Macauba production estimated by regression models.

Made available in DSpace on 2020-06-19T04:13:00Z (GMT). No. of bitstreams: 1 Juaci-macauba-production-estimated.pdf: 197211 bytes, checksum: 228bc89a9d3020d455af6c36622e9e2d (MD5) Previous issue date: 2019bitstream/item/214065/1/Juaci-macauba-production-estimated.pd

Bayesian multi-trait analysis reveals a useful tool to increase oil concentration and to decrease toxicity in Jatropha curcas L.

DOI: 10.1371/journal.pone.01503