The Levi-Civita spacetime

We consider two exact solutions of Einstein's field equations corresponding to a cylinder of dust with net zero angular momentum. In one of the cases, the dust distribution is homogeneous, whereas in the other, the angular velocity of dust particles is constant [1]. For both solutions we studied the junction conditions to the exterior static vacuum Levi-Civita spacetime. From this study we find an upper limit for the energy density per unit length $\sigma$ of the source equal ${1\over 2}$ for the first case and ${1\over 4}$ for the second one. Thus the homogeneous cluster provides another example [2] where the range of $\sigma$ is extended beyond the limit value ${1\over 4}$ previously found in the literature [3,4]. Using the Cartan Scalars technics we show that the Levi-Civita spacetime gets an extra symmetry for $\sigma={1\over 2}$ or ${1\over 4}$. We also find that the cluster of homogeneous dust has a superior limit for its radius, depending on the constant volumetric energy density $\rho_0$

A mobile solution to help visually impaired people in public transports and in pedestrian walks

Promoting social inclusion is a field of active research and an emergent topic that relates to blind and visually impaired people. They face plenty of problems in their daily routines and solutions to increase their independence are important. Among the difficulties they face, we discuss two that aim to help them in the use of public transport and the carrying out of walking routes between strategic points such as the City Hall, Finances, Health Center, etc. While the first task can be easier to accomplish, the later relies on GPS and as there are places with week signal, there are some additional difficulties. In this paper, we present a case study, developed in the Historical Center of Viana do Castelo, a city on the north of Portugal, which had the collaboration of a Visually Impaired Association that helped us along the process of the mobile application development and field tests. We present the objectives, developed prototypes, performed tests and evaluation of the system. ? 2018 WIT Press.5311-8814-F0ED | Sara Maria da Cruz Maia de Oliveira PaivaN/

Identificação de polimorfimos de base única (SNPs) em genes relacionados à taxa de ovulação em ovinos.

Resumo 708

"Enfezamento pálido" e "enfezamento vermelho" na cultura do milho no Brasil Central.

Foi constatada alta incidencia de plantas com sintomas de "Enfezamento Palido" e de "Enfezamento vermelho" em lavouras de milho no Brasil Central. Na mesma area observou-se a presenca de cigarrinha Dalbulus maidis em alta densidade. A presenca de espiroplasma foi confirmada apenas em plantas com sintomas de "Enfezamento Palido", atraves de teste DAS-ELISA. Os resultados da analise por PCR indicaram a presenca de fitoplasma em algumas amostras de plantas com sintomas do "enfezamento Vermelho"

Evaluation of high quality protein maize (QPM) hybrids obtained by conversion of normal inbred lines.

Two experimental QPM hybrids obtained by lhe partial conversion of three elite inbred lines by modified backcrossing were evaluated and compared to the normal versions of the same hybrids. Thirteen agronomic and 12 grain quality traits were evaluated. The hybrids were also anaJyzed by SSR markers in order to evaluate the genetic relationship among them. Results demonstrated that the converted QPM hybrids presented a better protein quality and a similar agronomic performance for most of the evaluated traits, including grain yield, in comparison to their normal versions. However, some of the deficiencies generally ascribed to QPM hybrids, such as a higher lodgíng percentage, thicker cobs, and shorter kernels were maintained up to this stage of the conversion process. In comparison to more recent elite hybrids, the normal versions as well as the converted QPM hybrids presented the worst performances in relation to the grain yield, thus indicating a loss of competitiveness

A layering model for superconductivity in the borocarbides

We propose a superlattice model to describe superconductivity in layered materials, such as the borocarbide families with the chemical formul\ae\ $RT_2$B$_2$C and $RT$BC, with $R$ being (essentially) a rare earth, and $T$ a transition metal. We assume a single band in which electrons feel a local attractive interaction (negative Hubbard-$U$) on sites representing the $T$B layers, while U=0 on sites representing the $R$C layers; the multi-band structure is taken into account minimally through a band offset $\epsilon$. The one-dimensional model is studied numerically through the calculation of the charge gap, the Drude weight, and of the pairing correlation function. A comparison with the available information on the nature of the electronic ground state (metallic or superconducting) indicates that the model provides a systematic parametrization of the whole borocarbide family.Comment: 4 figure

Características químicas e físicas de um solo cascalhento e suas implicações para o manejo sustentável desse solo.

Nesse trabalho foi coletado e analisado um solo cascalhento sob campo cerrado de Sete Lagoas - MG, visando obter subsídios para sua classificação e seu manejo. O solo foi analisado pelos métodos de rotina para fertilidade, química e física. Os resultados indicam que o solo é dominado pelas frações grosseiras, que perfazem mais de 80% da massa dos horizontes. O solo também apresenta acidez trocável elevada e baixos teores de nutrientes, exceto no horizonte superficial. Os testes de infiltração indicam condutividade hidráulica alta. O solo apresenta relativa resistência à erosão, mas de difícil manejo em caso de intervenção. Palavras-chave: granulornetria, fração grosseira, infiltração não saturad

Epigenetic enhancement and drought stress tolerance in maize: selection to anthesis-silking interval.

Edição dos resumos do 46º Congresso Nacional de Genética, Águas de Lindóia, SP, 2000