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Search Results: 1 - 10 of 608380 matches for " M. J. Pereira "
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Reversion to juvenility: the use of epicormics in the micropropagation of mature wild shrubs of Vaccinium cylindraceum Smith (Ericacaeae)
Arquipélago : Life and Marine Sciences , 2009,
Abstract: An efficient in vitro method was developed to propagate the shoots of mature wild shrubs of Vaccinium cylindraceum Sm. by axillary bud proliferation on epicormic stems. In the initial culture, 46.9% of the epicormic buds produced new shoots with juvenile morphological features. The number of nodes per shoot and the shoot length for explants which originated from epicormic buds was significantly higher when compared to that of winter dormant buds but similar when compared to that of seedling buds. The three most distal buds of epicormic twigs produced the best rates of shoot initiation: 87.5% (position 1) to 62.5% (position 3).
Human leptospirosis in a slum area in the city of Rio de Janeiro, Brazil: a serological and epidemiological study
Pereira, M. M.;Andrade, J.;
Memórias do Instituto Oswaldo Cruz , 1990, DOI: 10.1590/S0074-02761990000100007
Abstract: a serologic survey was carried out on slum dwellers in the city of rio de janeiro. a total of 259 serum samples from male and female individuals of different age groups were tested for the presence of antileptospire antibodies by microagglutination. prevalence data were analyzed in relation to the major risk factors present at the site, mainly represented by the presence of carrier animals and the occurence of frequent floods. of the samples tested, 25% reacted with antigens of different serogroups at titres ranging from 1:100 to 1:6400, with a predominance of titres <= 1:400; 35% of positive sera reacted with leptospirae of the icterohaemorrhagiae serogroup. reactions with djasiman, panama, javanica, canicola, pyrogenes, australis, ballum, sejroe, bataviae, grippotyphosa, autumnalis and cynopteri were also detected, though at lower frequencies. there was no statistically significant difference between sexes, but higher prevalence rates were found to be associated with increasing age. a focus of infection was characterized, in which social and economic factors contribute to the persistance of leptospirae by favoring the proliferation of the main reservoir.
Angular Momentum and Energy-Momentum Densities as Gauge Currents
M. Calcada,J. G. Pereira
Physics , 2002, DOI: 10.1103/PhysRevD.66.044001
Abstract: If we replace the general spacetime group of diffeomorphisms by transformations taking place in the tangent space, general relativity can be interpreted as a gauge theory, and in particular as a gauge theory for the Lorentz group. In this context, it is shown that the angular momentum and the energy-momentum tensors of a general matter field can be obtained from the invariance of the corresponding action integral under transformations taking place, not in spacetime, but in the tangent space, in which case they can be considered as gauge currents.
Gravitation and the Local Symmetry Group of Spacetime
M. Calcada,J. G. Pereira
Physics , 2002,
Abstract: According to general relativity, the interaction of a matter field with gravitation requires the simultaneous introduction of a tetrad field, which is a field related to translations, and a spin connection, which is a field assuming values in the Lie algebra of the Lorentz group. These two fields, however, are not independent. By analyzing the constraint between them, it is concluded that the relevant local symmetry group behind general relativity is provided by the Lorentz group. Furthermore, it is shown that the minimal coupling prescription obtained from the Lorentz covariant derivative coincides exactly with the usual coupling prescription of general relativity. Instead of the tetrad, therefore, the spin connection is to be considered as the fundamental field representing gravitation.
Energy Efficiency and Renewable Energy Technologies Using Smart Grids: Study Case on NIPE Building at UNICAMP Campus  [PDF]
M. D. Berni, P. C. Manduca, S. V. Bajay, J. T. V. Pereira, J. T. Fantinelli
Smart Grid and Renewable Energy (SGRE) , 2014, DOI: 10.4236/sgre.2014.58018
Abstract: In its broadest interpretation, the smart grid vision sees the future of power industry transformed by the introduction of intelligent two-way communications, ubiquitous metering and measurement. This enables much finer control of energy flows and the integration and efficient use of renewable forms of energy, energy efficiency methodologies and technologies, as well as many other advanced technologies, techniques and processes that wouldn’t have been practicable until present. The smart grid vision also enables the creation of more reliable, more robust and more secure power supply infrastructure, and helps optimize the enormous investments required to build and operate the physical infrastructure required. The smart grid promises to revolutionize the electric power business that has been in place for the past 75 years. This work discusses the efficiency, targeted at the consumer units of electricity, with a view to sustainability and potential for technological innovation. The issue is addressed from two perspectives: the systems for generation and power distribution, and the design of a building “smart energy”. Because of the novelty of the subject in our country, the concepts presented and treated throughout this work come from material obtained at events and specialized sites on electric power system in Brazil and worldwide, being accompanied by information and data from NIPE’s building at University of Campinas’s campus case study in which it exemplifies the applicability of the techniques and recommended technologies.
Landau levels of single layer and bilayer phosphorene
J. M. Pereira Jr.,M. I. Katsnelson
Physics , 2015, DOI: 10.1103/PhysRevB.92.075437
Abstract: In this work we introduce a low-energy Hamiltonian for single layer and bilayer black phosphorus that describes the electronic states at the vicinity of the gamma point. The model is based on a recently proposed tight-binding description for electron and hole bands close to the Fermi level. We calculate expressions for the Landau level spectrum as function of magnetic field and in the case of bilayer black phosphorus we investigate the effect of an external bias on the electronic band gap. The results showcase the highly anisotropic character of black phosphorus and in particular for bilayer BP, the presence of bias allows for a field-induced semiconductor-metal transition.
Obesity: Nutrition and Genetics—A Short Narrative Review  [PDF]
José M. Tallon, Janine Narciso, Ana Barros, Ana Pereira, Aldo M. Costa, António J. Silva
Health (Health) , 2018, DOI: 10.4236/health.2018.1012134
Abstract: Obesity has become a major global health challenge and it is a risk factor for the development of several comorbid conditions. Additionally, obesity has considerable economic consequences. Obesity is a multifactorial condition that arises from independent influences of genetic and social-environmental factors on food intake and physical activity. It has been difficult to establish clear associations between weight status and the intake of single foods or food groups. In most people, the predisposition to obesity has a polygenic basis, which means that obesity will develop if an individual has several polygenic variants that increase body weight. The FTO gene was the first GWAS-identified obesity-susceptibility gene and since then other polygenic variants that are associated with BMI and dietary intake have also been identified. However, this is still an active area of research as more polygenetic variants await discovery.
Self-Assembled Dextrin Nanogel as Curcumin Delivery System  [PDF]
Catarina Gon?alves, Paula Pereira, Peter Schellenberg, Paulo J. Coutinho, Francisco M. Gama
Journal of Biomaterials and Nanobiotechnology (JBNB) , 2012, DOI: 10.4236/jbnb.2012.32024
Abstract: Curcumin is a natural polyphenol with anti-oxidative, anti-inflammatory and anti-cancer properties. Its therapeutic potential is substantially hindered by the rather low water solubility and bioavailability, hence the need for suitable carriers. In this study, we show that self-assembled nanogels obtained from hydrophobically modified dextrin are effective curcumin nanocarriers. The stability and loading efficiency of curcumin-loaded nanogel depends on the nanogel/curcumin ratio. Higher stability of the formulation is achieved in water than in PBS buffer, as evaluated by dynamic light scattering and fluorescence measurements. The in vitro release profile, using sink conditions, indicates that dextrin nanogel may perform as a suitable carrier for the controlled release of curcumin. Biological activity of curcumin-loaded nanogel in HeLa cell cultures was assessed using the MTS assay.
Hymenoptera marking technique
Pereira, A. M.;Chaud-Netto, J.;
Journal of Venomous Animals and Toxins including Tropical Diseases , 2008, DOI: 10.1590/S1678-91992008000100014
Abstract: in true social hymenopterans, such as many species of bees, wasps and all species of ants, the main characteristics are the overlapping of generations, the care with the offspring and the division of labor among the members of the colony. the first biological feature means that in a same moment there are groups of individuals, with variable ages, that execute different activities in the colony. in order to study the division of labor among the members of the colony, or to estimate the life span of these insects, or even to analyze any kind of behavior in non-social insects, it is necessary to know the exact age of each individual. for this reason, the insects must be identified soon after emergence. the identification of insects with numbers is an important technological improvement in behavioral studies, mainly in honeybee colonies. the aim of this scientific note is to describe an easy and cheaper technique for marking hymenopterans.
Questionário de Avalia??o da Qualidade de Vida para adolescentes com Diabetes Tipo 1: Estudo de valida??o do DQOL
Almeida,J. Paulo; Pereira,M. Gra?a;
Análise Psicológica , 2008,
Abstract: diabetes type 1 is a complex chronic disease that is difficult to control specially during adolescence. this is due in part to the developmental transition of adolescence from dependency on parents to a more autonomous lifestyle. adolescence is also marked by a change in psychosocial characteristics that have an impact on adherence to treatment, metabolic control and quality of life in diabetics. the purpose of this study is to adapt a questionnaire of quality of life for adolescents with diabetes type 1. the research included 256 adolescents, aged 10 to 18 years from the pediatric department of hospital s. jo?o - porto. diabetes was diagnosed at least a year prior to data collection. the portuguese version of dqol has a smaller number of items than the original version gathered in 3 factors that assess impact of diabetes in the adolescent day to day life (13 itens), satisfaction with treatment and life (17 itens) and worry towards the future (6 itens). the scale shows an excellente internal consistency. the intercorrelation between the subscales is also good. the scale is able to descriminate between gender and age according to three phases of adolescence in two of the subscales. it also shows an excellent convergent validity being highly correlated with a questionnaire of anxiety towards diabetes.
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