da Silva N.A.P.,Centro Universitario Of Brasilia |
Frizzas M.R.,University of Brasilia |
de Oliveira C.M.,Embrapa Cerrados
Revista Brasileira de Entomologia | Year: 2011
Seasonality in insect abundance in the "Cerrado" of Goiás State, Brazil. Many studies have provided evidence that tropical insects undergo seasonal changes in abundance and that this is partly due to alternation between the dry and rainy seasons. In the Brazilian "Cerrado" (savannah), this season alternation is particularly evident. The purpose of this work was to study the seasonal abundance of insects in a "Cerrado" area in the municipality of Pirenópolis, Goiás State, Brazil. The insects were captured fortnightly using a light trap between September 2005 and August 2006. The insects collected were separated at the order level and counted. Faunistic analysis was performed to select the predominant insect orders, a multiple linear regression to examine the relation between climatic variables (temperature and precipitation) with the abundance of insects and a circular distribution analysis to evaluate the existence of seasonality in the abundance of insect orders. A total of 34,741 insect specimens were captured, belonging to 19 orders. The orders with the greatest number of specimens were Hymenoptera (8,022), Coleoptera (6,680), Diptera (6,394), Lepidoptera (6,223), Isoptera (2,272), Hemiptera (2,240) and Trichoptera (1,967), which represent 97.3% of all the specimens collected. All the orders, except for Diptera, Isoptera and Trichoptera, showed a relationship with the climate variables (temperature), and all the orders, except for Diptera, presented a grouped distribution, with greater abundance in the transition from the end of the dry season (September) to the start of the rainy one (October/November). A discussion about seasonality on the abundance of the insects is presented.
Dias R.I.,University of Brasilia |
Dias R.I.,Centro Universitario Of Brasilia |
Lima M.R.,University of Brasilia |
Lima M.R.,State University Londrina
Wilson Journal of Ornithology | Year: 2015
Different ecological parameters are associated with the selection of nests and breeding sites in birds. Understanding nest-site selection and the subsequent consequences for reproductive success are critical to a full understanding of how natural selection shapes birds' nesting behavior. Between 2007 and 2008, we evaluated nest-site characteristics and nesting success of Tropical Screech-Owls (Megascops choliba) in an area of Cerrado interspersed with cultivated areas in central Brazil. We compared the characteristics of cavities used for nesting by owls and unused nesting cavities and modeled nest survival in MARK. Models were assessed using Akaike's Information Criterion for small sample sizes (AICc) and model averaging was used to infer model parameters. Tropical Screech-Owls nested in tree and termite-mound cavities. Nest success was 44.4%, with predation being the main cause of nest failure. We found that Tropical Screech-Owls nested in cavities with different orientations, and closer to the ground than unused cavities. Although the top-ranked models included nest height and nest concealment, multimodel inference showed that these variables had no clear effect on nest survival. Despite the lack of effect of these variables on nest survival, nest-site characteristics commonly associated with a cavity's microclimate (i.e., orientation of cavity entrance) may still have a stronger influence on nest-site selection. © 2015 The Wilson Ornithological Society.
Lima F.M.S.,University of Brasilia |
Venceslau G.M.,University of Brasilia |
Brasil G.T.,Centro Universitario Of Brasilia
Revista Brasileira de Ensino de Fisica | Year: 2014
In hydrostatics, the Archimedes principle predicts an upward force whenever a body is submerged in a liquid. In contrast to common sense, this physical law is not free of exceptions, as for example when the body touches the container. This is more evident when a rectangular block less dense than the liquid rests on the bottom, with no liquid underneath it, a case in which a downward force is expected, according to a recent work by the first author. In the present work, we describe a simple, low-cost experiment which allows the detection of such force. This counterintuitive result shows the inadequacy of Archimedes' principle for treating "contact" cases. © Sociedade Brasileira de Física.
Ramirez P.E.,Central American Business University |
Mariano A.M.,Centro Universitario Of Brasilia
Informacion Tecnologica | Year: 2014
This study analyzes the scientific production in the field of business studies in Chile and Brazil. The methodology is based on scientometric tools, using as sources 7955 papers published in Scopus indexed journals between 2004 and 2013. In summary, the results indicate that although in both countries the scientific production has significantly increased, a reduction of the impact of these articles is detected. In addition, there are differences between Chile and Brazil associated to cooperation with other countries, the variety of journals where studies are published, and the structure of the ranking of the institutions that publish. The main conclusions indicate that research in this area is carried out in universities, cooperation between countries is significant in this scientific production, and dissemination is carried out mainly through regional journals. © 2014, Centro de Informacion Tecnologica. All rights reserved.
Jose S.C.B.R.,Embrapa Recursos Geneticos e Biotecnologia |
Salomao A.N.,Embrapa Recursos Geneticos e Biotecnologia |
Costa T.S.A.,Embrapa Recursos Geneticos e Biotecnologia |
da Silva J.T.T.T.,Centro Universitario Of Brasilia |
Curi C.C.S.,Embrapa Recursos Geneticos e Biotecnologia
Revista Brasileira de Sementes | Year: 2010
The significant progress in Brazilian agricultural production has been due its capacity to incorporate and use genetic resources. Embrapa Genetic Resources and Biotechnology is the institution responsible for the long-term conservation of the seed germplasm of many crops, stored at -20 °C. Appropriate storage is necessary for correct germplasm management, to ensure the quality of the material stored and minimize the deterioration process. The objectives of this study were to evaluate the effect of seed water content on the tolerance to storage at sub-zero temperatures of -20 °C and -196 °C, to associate the tolerance level with physiological and biochemical aspects and to verify the effect of the pre-humidification of seeds on physiological quality after storage. Seed quality was evaluated by tests of electrical conductivity, first and final count of germination and determination of the peroxide index. Sunflower seeds can be dried to 3.2% of water content in silica gel or in a drying chamber and stored at -20 °C or -196 °C without loss of germination and vigor. Seed deterioration, evaluated by the peroxide index, was lower in seeds stored in NL. The humidification treatment was important for the evaluation of seedlings in the first count of germination test and the electrical conductivity test.