Criação de peixes pode ser uma boa alternativa de negócio para o produtor rural brasileiro.

Há mais de 20 anos, a criação de peixes vem se apresentando como uma promissora oportunidade econômica para o empresário rural brasileiro. No início, estimulada pela expansão dos ?pesque-pagues?, a atividade mostrou-se muito lucrativa, permitindo à piscicultura experimentar um crescimento até então inédito no País. Os brasileiros começavam a perceber que os peixes poderiam ser produzidos em cativeiro, sob condições controladas e planejadas, diferentemente da tradicional pesca extrativista. A perspectiva de aumentar o consumo de um alimento nobre passou a fazer parte do dia a dia da população e o setor produtivo percebeu uma excelente alternativa de negócio.bitstream/item/123119/1/Criacao-de-peixes.pd

Variations of the Energy of Free Particles in the pp-Wave Spacetimes

We consider the action of exact plane gravitational waves, or pp-waves, on free particles. The analysis is carried out by investigating the variations of the geodesic trajectories of the particles, before and after the passage of the wave. The initial velocities of the particles are non-vanishing. We evaluate numerically the Kinetic energy per unit mass of the free particles, and obtain interesting, quasi-periodic behaviour of the variations of the Kinetic energy with respect to the width $\lambda$ of the gaussian that represents the wave. The variation of the energy of the free particle is expected to be exactly minus the variation of the energy of the gravitational field, and therefore provides an estimation of the local variation of the gravitational energy. The investigation is carried out in the context of short bursts of gravitational waves, and of waves described by normalised gaussians, that yield impulsive waves in a certain limit.Comment: 20 pages, 18 figures, further arguments supporting the localizability of the gravitational energy are presented, published in Univers

Qualidade da água na engorda de tambaqui em viveiros sem renovação da água.

bitstream/CPATC/19780/1/f_18_2007.pd

Non-singular inflation with vacuum decay

On the basis of a semi-classical analysis of vacuum energy in an expanding spacetime, we describe a non-singular cosmological model in which the vacuum density decays with time, with a concomitant production of matter. During an infinitely long period we have an empty, inflationary universe, with H \approx 1. This primordial era ends in a fast phase transition, during which H and \Lambda decrease to nearly zero in a few Planck times, with release of a huge amount of radiation. The late-time scenario is similar to the standard model, with the radiation phase followed by a long dust era, which tends asymptotically to a de Sitter universe, with vacuum dominating again. An analysis of the redshift-distance relation for supernovas Ia leads to cosmological parameters in agreement with other current estimations.Comment: Work presented at IRGAC 2006, Barcelona, July 11-15 2006. To appear in a special issue of Journal of Physics

Redução dos impactos ambientais da pecuária de corte no Acre.

A pecuária de corte é a atividade responsável por aproximadamente 75% dos 1.420.300 hectares de áreas desmatadas no Acre (9,3%). A partir da década de 70, a Embrapa Acre iniciou ações de pesquisa e desenvolvimento em propriedades do Estado, com o objetivo de desenvolver tecnologias que permitissem viabilizar sistemas de produção animal sustentáveis que contribuíssem para atender à demanda interna de carne, gerar excedentes exportáveis e, ao mesmo tempo, reduzir os impactos ambientais desta atividade.bitstream/item/135533/1/3673.pd

Sistemas sustentáveis de pecuária leiteira para a agricultura familiar no Acre.

A pecuária leiteira é uma atividade de crescente importância na agricultura familiar no Acre, tanto em áreas de colonização como em reservas extrativistas e áreas indígenas. Entretanto, esta atividade resulta em grandes impactos ambientais negativos., decorrentes dos desmatamentos, perda de biodiversidade e degradação dos solos. Além disso, a pecuária leiteira, desenvolvida por pequenos produtores, apresenta baixa rentabilidade decorrente dos baixos índices zootécnicos. Há duas décadas, a Embrapa Acre desenvolve tecnologias para responder ao desafio de viabilizar sistemas de produção sustentáveis para a pecuária leiteira, economicamente rentáveis e de reduzido impacto ambiental para a agricultura familiar no Acre.bitstream/item/135543/1/3674.pd

Endosperm genotyping as a strategy to differentiate the allele source in maize heterozygous progeny.

The objective of this work was to distinguish the parental source of alleles in heterozygous progeny using semiquantitative polymerase chain reaction (PCR) in maize endosperm. Endosperms derived from direct and reciprocal single-cross hybrids between maize inbred lines L3 and L1113-01 were genotyped by semiquantitative PCR methodology (SQ-PCR) using fluorescent microsatellite primers. The amplification products were evaluated by the ratios of fluorescence intensity (RFI), calculated between the peaks corresponding to the alleles derived from each parental line. Based on the statistically significant contrast between RFI mean values of direct and reciprocal single-cross hybrids, it was possible to distinguish the number of alleles received from each parental line and, ultimately, to determine the origin of the alleles of each cross. Thus, endosperm genotyping using SQ-PCR is a promising strategy to map QTL in maize outbred populations

Radiographic fetal osteometry: Approach on age estimation for the portuguese population

The estimation of gestational age (GA) on fetal remains can be an important forensic issue. Forensic specialists usually use reference tables and regression equations derived from reference collections, which are quite rare in what fetuses are concerned. Since these tools are mostly grounded on ultrasonographic measurements, which are known to differ from real bones measurements or are based on ancient literature, this study aimed the construction of tables and regression equations for the Portuguese population on the basis of diaphyseal bone length measurements (femur, tibia and humerus) of 100 fetuses of known GA, using post-mortem radiographs. There is a strong correlation between the longitudinal length of studied bones and GA; the femur exhibits the strongest correlation (r = 0.969; p = 0.000), followed by the tibia (r = 0.966; p = 0.000) and the humerus (r = 0.963; p = 0.000). Therefore it was possible to obtain regression equations and to build tables with reference values for each of the diaphysis analyzed