Rodrigues M.E.,Federal University of Pará |
Junior E.L.B.,Federal University of Pará |
Marques G.T.,University of Amazon |
Zanchin V.T.,Federal University of ABC
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2016
We obtain a class of regular black hole solutions in four-dimensional f(R) gravity, R being the curvature scalar, coupled to a nonlinear electromagnetic source. The metric formalism is used and static spherically symmetric spacetimes are assumed. The resulting f(R) and nonlinear electrodynamics functions are characterized by a one-parameter family of solutions which are generalizations of known regular black holes in general relativity coupled to nonlinear electrodynamics. The related regular black holes of general relativity are recovered when the free parameter vanishes, in which case one has f(R) R. We analyze the regularity of the solutions and also show that there are particular solutions that violate only the strong energy condition. © 2016 American Physical Society.
Agency: GTR | Branch: BBSRC | Program: | Phase: Research Grant | Award Amount: 43.39K | Year: 2012
Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.
Stone A.I.,Eastern Michigan University |
Stone A.I.,University of Amazon
International Journal of Primatology | Year: 2014
Sexually dimorphic traits can evolve through male-male competition or female choice. Squirrel monkeys (genus Saimiri) live in large multimale, multifemale groups and are seasonal breeders with concealed ovulation. In several species of the genus, females are dominant to males. Males show weight gain preceding and during the mating season, which produces a "fattened" appearance in the upper arms, shoulders, and torso. Although much is known about the physiology of fattening, the evolutionary function(s) of this sexually dimorphic trait, including possible benefits and costs, remain(s) unknown. This unusual reproductive physiology of males is suggestive of sexual selection. Here I present data on wild Saimiri sciureus studied in Brazil to describe male reproductive investment in the species and to examine the hypothesis that male fattening is a product of sexual selection. I observed at least nine adult males via focal animal sampling and ad libitum observations during four mating seasons and during an additional 10 nonbreeding season months for comparison. Compared to less robust males, fatter males spent significantly more time near females and less time alone. These males also spent more time engaged in sociosexual activities and less time feeding/foraging, suggesting a trade-off between maintenance and reproductive behaviors. The 2-mo mating season accounted for 62% of all male-male agonism observed over one 12-mo period. These results are suggestive of male-male competition for females. However, males did not coerce females to mate and females often rejected males; this pattern suggests female choice. It is possible that male fattening in Saimiri is a product of both intra- and intersexual selection. Males experience intense reproductive costs related to agonism with other males, and related to time and energy invested in the pursuit of females. Although fattening may mitigate some of these costs by aiding in male-male competition and in female preference, this phenomenon is likely not without physiological costs to adult males. © 2014 Springer Science+Business Media New York.
Vasconcelos S.S.,University of Florida |
Zarin D.J.,University of Florida |
Araujo M.M.,Federal University of Santa Maria |
Miranda I.D.S.,University of Amazon
Forest Ecology and Management | Year: 2012
Aboveground net primary productivity (ANPP) represents an important integrated measure of resource effects on forest ecosystem functions. Rates of ANPP, as well as resource availability controls over ANPP, are poorly understood for tropical forest regrowth following agricultural abandonment, although such regrowth accounts for a large and growing proportion of tropical landscapes. Here, we report on the response of ANPP to inter-annual variability in dry-season precipitation and to four years of dry-season irrigation in a forest regrowth stand in eastern Amazonia. ANPP was most strongly correlated with previous-year annual and dry-season precipitation inputs, suggesting a lag effect of the influence of precipitation on ANPP. The dry-season irrigation experiment provides some confirmation of this lag effect: ANPP response to treatment was significant for 2002 and 2003, following strong previous-year dry seasons, but not during the first treatment year (2001) or 2004, following the weak 2003 dry season. ANPP response to both inter-annual precipitation variability and to dry-season was largely due to a response in aboveground biomass increment rather than litterfall. Drought constraints on aboveground biomass increment suggest that the potential of forest regrowth to sequester atmospheric carbon will decrease with projected reductions in regional rainfall. © 2012 Elsevier B.V.
Do Nascimento Borges B.,University of Amazon |
Burbano R.M.R.,Federal University of Pará |
Harada M.L.,Federal University of Pará
Tumor Biology | Year: 2013
Gastric cancer is a major public health problem in Pará state, where studies suggest complex genetic and epigenetic profiles of the population, indicating the need for the identification of molecular markers for this tumor type. In the present study, the methylation patterns of three genes [p16 INK4A, p15 INK4B, and adenomatous polyposis coli (APC)] were assessed in patients with gastric adenocarcinoma from Pará state in order to identify possible molecular markers of gastric carcinogenesis. DNA samples from tumoral and non-tumoral gastric tissues were modified with sodium bisulfite. A fragment of the promoter region of each gene was amplified and sequenced, and samples with more than 20 % of methylated CpG sites were considered hypermethylated. The correlation between the methylation pattern of the selected genes and the MTHFR C677T polymorphism, as well as the relationship between APC and CDH1 methylation, were evaluated. The results suggest that APC hypermethylation is an age-specific marker of gastric carcinogenesis, and the concordance of this event with CDH1 hypermethylation suggests that the Wnt pathway has an important role in gastric carcinogenesis. While the hypermethylation pattern of p15 INK4B seems to be an earlier event in this type of tumor, the hypomethylated status of this gene seems to be correlated to the C677T MTHFR TT genotype. On the other hand, the observed pattern of p16 INK4A hypermethylation suggests that this event is a good marker for the gastric cancer pathway in the Pará state population. © 2013 International Society of Oncology and BioMarkers (ISOBM).
Arruda-Filho E.J.M.,University of Amazon |
Lennon M.M.,Frostburg State University
International Journal of Information Management | Year: 2011
Using netnographic evidence on iPhone usage, this study suggests that devoted and innovative consumers adopt and use new technology for hedonic experiences and social positioning, which generates experiential outcomes. This article presents an interpretive analysis of consumption behavior of iPhone users after their experience with iPhone v1 and its successive iterations, prior to the release of Apple's latest model the iPhone 4. The day the iPhone v1 was released was dubbed iDay1 by Apple brand aficionados, and the anticipated release date of the iPhone 4 iDay2. While the original iPhone v1 was seen as very cutting edge, successive releases (the iPhone 3G and iPhone 3GS), were far less innovative. Each successive iPhone release has not had as devout a following as the original. This raises the question: will innovation seeking consumers abandon the iPhone for a newer, more technologically innovative device? This study suggests that innovators prefer really new products instead of upgraded ones, because they cannot see the advantage of using an upgraded version of a product which has already been widely adopted. © 2011 Elsevier Ltd. All rights reserved.
Bernardes T.F.,Federal University of Lavras |
Do Rego A.C.,University of Amazon
Journal of Dairy Science | Year: 2014
Dairy farmers across Brazil were invited to participate in a study on silage production and utilization practices. Two hundred sixty farmers filled out a questionnaire, which was made available on a website. The questionnaire consisted of 14 questions, including information about the characteristics of the herd (n. = 3), the crop(s) used in the ensiling process, the use of additives, the harvest (n. = 3), the type of silo (n. = 1), aspects related to sealing (n. = 2), and management practices applied during feed-out (n. = 3). Farmers were also asked a final question about the main barriers they faced when producing and using silage. The main dairy-producing regions of Brazil had a strong influence on the number of participants. The profiles of farmers were heterogeneous and divided into 5 groups, which was considered a positive attribute of the study, allowing better analysis and assessment of current circumstances. Corn was the most widely grown crop for silage. Sorghum, tropical grasses, and sugarcane were the other species most cited. Additives were used by a small number of farmers (27.7%). Approximately 40% of farmers still depended on loaned equipment or outsourced services. The pull-type forage harvester was the main piece of equipment used on dairy farms (90.4%). Only 54.6% of respondents answered that they sharpen their harvester knives daily. Horizontal silos (bunker and stack) were the structures most commonly used to store silage. Most farmers sealed silos with double-sided plastic film (black-on-white) and with soil. However, almost one-fifth of all farmers still use black plastic. Manual removal of silage from the silos was practiced at most farms (i.e., the lack of equipment was also reflected in the stage of silage utilization). Disposal of spoiled silage before inclusion in the livestock feed was not a common practice on the farms. The main barriers encountered on the farms were lack of equipment, lack of manpower, and climatic variations. The results of this research may guide researchers, industries, extension workers, and governments to seek efficiency in milk production on farms using silage in the diet of livestock throughout the year or during part of the year in Brazil. © 2014 American Dairy Science Association.
Lima T.T.S.,University of Amazon |
Miranda I.S.,University of Amazon |
Vasconcelos S.S.,EMBRAPA - Empresa Brasileira de Pesquisa Agropecuária
New Phytologist | Year: 2010
Fine root dynamics is widely recognized as an important biogeochemical process, but there are few data on fine root growth and its response to soil resource availability, especially for tropical forests. We evaluated the response of fine root dynamics to altered availability of soil water and nutrients in a 20-yr-old forest regrowth in eastern Amazonia. In one experiment the dry season reduction in soil moisture was alleviated by irrigation. In the other experiment, nutrient supply was reduced by litter removal. We used the ingrowth core technique to measure fine root mass growth, length growth, mortality and specific root length. Dry-season irrigation had no significant effect on mass and length of live and dead roots, whereas litter removal reduced mass and length of live roots. For both irrigation and litter removal experiments, root growth was significantly greater in the dry season than in the wet season. Increased root growth was associated with decreased soil water availability. However, root growth did not increase in response to nutrient reduction in litter removal plots. Overall, our results suggest that belowground allocation may differ according to the type of soil resource limitation. © The Authors (2010). Journal compilation © New Phytologist Trust (2010).
Yague B.,University of Amazon
Revista Colombiana de Antropologia | Year: 2014
This paper addresses how urban indigenous people in Leticia develop strategies in order to access the traditional foods they cannot produce in the city. Through the establishment of food exchange networks they obtain food from the forest and also extend their alliances and build other social and gender relationships in a constantly changing urban environment. The study of these networks enables an understanding of how indigenous people interact and adapt to the city, and also how they transform it and make it "edible".
Monteiro K.F.G.,University of Amazon
Oecologia Australis | Year: 2011
To produce palm in tropical countries, rural enterprises have made progress in the areas of natural forests, causing serious impacts on their local and regional biodiversity. This context of disorderly use of land and forest resources appears after the year 2005, with the expansion of agribusiness activity for natural territories in countries located mostly in the humid tropics. This has shown that the ratio of expansion of the vegetable oil industry, biofuel industry and the use of plant biodiversity, with the current production model, has been impressive and unsustainable over time. This study aims to analyze through literature the experience of environmental management of productive activities of firms palm oil (extraction + biodiesel industry) in areas belonging to the Guyanese shield, Colombian and Brazilian Amazon between 2005 and 2009, using as a methodological tool the Life Cycle Assessment - LCA). The adoption of LCA is an important tool for better monitoring the production and identification of alternative interaction between processes and possible impacts on the environment. Results listed according to the degree of interference / importance in the production chain was first demonstrated by the emission of pollutants into the atmosphere, being established in phases and agricultural production of biodiesel, for the experience of Colombian companies had lower launch in two phases, in relation to the experience of the Brazilian Amazon. The second stage observed was the environmental impact of product processing industries of palm oil at this stage we observed a greater release of waste and waste generation in large quantities without final disposition appropriate for the activity. The environmental management system analyzed the experiences of biodiesel production from palm oil in the Amazon and Pará and Colombia, demonstrated that both need to be adapted to the requirements of quality standards demanded by the international market for biofuels.