Federal University of Tocantins

Palmas, Brazil

The Universidade Federal do Tocantins is a public federal university located in the state of Tocantins, Brazil. This university has campuses located in Araguaína, Arraias, Gurupi, Miracema, Palmas, and Porto Nacional e Tocantinópolis. Wikipedia.

Time filter

Source Type

Pompeu P.S.,Federal University of Lavras | Agostinho A.A.,State University of Maringá | Pelicice F.M.,Federal University of Tocantins
River Research and Applications | Year: 2012

Most of the large rivers of South America are impounded mainly for hydropower production. The construction of fish passes has been one of the strategies adopted by Brazilian authorities and the energy sector to diminish the effects of these barriers on migratory fish communities. Despite the high investments and efforts involved, most facilities have been considered ineffective for conservation purposes. Decades of poor monitoring and the lack of specific studies have limited our knowledge on the real role of fish passes. Efficiency has been frequently defined as the proportion of fish that ascend a fish passage facility, compared to the shoal size that reaches the dam. Inspired by the notion that fishes accumulated below the dam need to migrate upstream, the quantity of fish passed upstream historically indicated successful management, as generally inferred by the fish abundance inside the fish pass. We propose a new concept for estimating fish pass efficiency for South American rivers, based on the capability of the fish pass to maintain viable populations. This broader approach is necessary because knowledge of fish habitats below and above the pass, plus the feasibility of downstream movements of eggs, larvae and adults through the reservoir and past the dam, is needed for assessing whether a fish pass is working as a conservation tool. © 2011 John Wiley & Sons, Ltd.

Pelicice F.M.,Federal University of Tocantins | Pompeu P.S.,Federal University of Lavras | Agostinho A.A.,State University of Maringá
Fish and Fisheries | Year: 2015

Most large rivers in South America are fragmented by large dams, and a common management strategy to mitigate impacts has been construction of fish passes. Recent studies, however, indicate that downstream passage of adults and young fish is nil or minimal. Better understanding of this phenomenon is needed if fishways are to provide any tangible conservation value in South America. We propose, in this article, that large reservoirs impose a different kind of barrier to migrating fish: impoundments create a diffuse gradient of hydraulic/limnological conditions that affects fish behaviour and functions as an extensive environmental filter that discourages downstream movements. To develop this idea, we characterize the barriers created by dams and reservoirs by describing their distinct nature, the effects on fish migration and potential solutions. We show, for example, that dams generally prevent upstream movements, whereas reservoirs impede mainly downstream movements. In this context, we explain how fish passes, in some instances, can partially mitigate fragmentation caused by dams, but there is no technical solution to solve the barrier effect of reservoirs. In addition, we present a body of empirical evidence that supports the theory that large reservoirs are important barriers to fish migration in South America, we offer an overview of the size of reservoirs to show that impoundments typically have large dimensions, and we discuss the significance of this theory for other regions. Based on current and proposed river regulation scenarios, we conclude that conservation of Neotropical migratory fish will be much more complicated than previously believed. © 2015 John Wiley & Sons Ltd.

Pelicice F.M.,Federal University of Tocantins | Vitule J.R.S.,Federal University of Paraná | Lima Junior D.P.,Federal University of Mato Grosso | Orsi M.L.,State University Londrina | Agostinho A.A.,State University of Maringa
Conservation Letters | Year: 2014

As Brazil undergoes rapid economic growth, short-sighted political decisions can threaten biological diversity and ecosystem services. Recently, the Brazilian Congress proposed a law to allow the rearing of nonnative fish in aquaculture cages in any hydroelectric reservoir of the country. This initiative may "naturalize by decree" some of the worst invasive species in the world (e.g., carps and tilapias) as a means of developing inland aquaculture and economy. The spread of aquaculture facilities will create opportunities for fish invasions to occur throughout the country, with the risk of damaging native biodiversity, ecosystem services, and environmental quality on a continental scale. The proposal ignores ecological theory, historical and/or empirical data concerning fish invasion, including dispersal, establishment, propagule pressure, invasiveness and invasibility, and all the negative consequences that may follow the invasion and establishment of nonnative organisms. This situation inspires reflection about the future of tropical biodiversity worldwide, particularly because Brazil, like many other developing countries, possesses a remarkable diversity of fish and other freshwater organisms yet has taken some political measures that are in conflict with important conservation issues. © 2013 Wiley Periodicals, Inc.

Dibble E.D.,Mississippi State University | Pelicice F.M.,Federal University of Tocantins
Ecology of Freshwater Fish | Year: 2010

This study investigated the effects of plant-specific habitat on the distribution of young and small adult fishes in lagoons of the Upper Paraná River floodplain, Brazil. We compared fish catch per unit effort (CPUE) and species richness and used an indirect gradient analysis to investigate fish-plant relationships within three aquatic macrophytes beds (Cabomba furcata, Eichhornia azurea, Nymphaea amazonum), and explored microhabitat influence (indexed by eight variables related to physical structure and water quality) on the structure of fish assemblages. Rarefaction analysis was used to compare fish species richness among the vegetated habitats. We captured a total of 1599 fish constituting 23 species, 7 families and 3 orders. Fish CPUE and species richness increased relative to microhabitat structure innate to the macrophytes; higher CPUE and richness were observed in C. furcata beds, a submerged aquatic macrophyte with finely dissected leaves. On the contrary, N. amazonum, a species that provides low microhabitat complexity, harbored fewer individual fish and number of species. Reproduction dynamics, hydrology and the amount of available plant-generated habitat structure (surface effect) contributed to the disproportionally high number of individuals captured during the dry season. Our data suggest that the microhabitat physical structure (e.g., edge distance, stem density and patch size) provided by macrophyte beds in the lagoons of the Upper Paraná River may play a more important role than physicochemistry (e.g., oxygen, temperature and pH) at mediating distribution patterns of small-sized fishes. © 2010 John Wiley & Sons A/S.

The genus Acanthicus is diagnosed from remaining Loricariidae genera by several characters, including the absence of adipose fin, pectoral-fin spine enlarged and the presence of small plates in abdomen region. Acanthicus currently comprises two valid species: A. hystrix and A. adonis. Acanthicus hystrix is distinguished from A. adonis, mostly by having body and fins dark brown to almost completely black background colored, without clear spots or dots (vs. dark brown color background with white spots covering body and fins) and presence of ochre to grey stripes in caudal fin (vs. stripes absent on caudal fin). The holotype of A. hystrix was destroyed during a bombing raid in the Second World War, no neotype was designed and the species is recognized by the illustration present in the original description, whose text is short, and uninformative. In the present contribution, specimens from several institutions were examined, revealing that the species is widespread in the Amazon, Tocantins-Araguaia and Orinoco basins, while A. adonis is restricted to the lower rio Tocantins. Herein, a redescription of Acanthicus hystrix is provided, with a comprehensive diagnosis of the genus and its species, along with a distribution map of the genus, a key to species identification, and brief comments on the systematics and distribution of the genus. Copyright © 2016 Magnolia Press.

Franco E.T.,Federal University of Tocantins
Physical Review D - Particles, Fields, Gravitation and Cosmology | Year: 2015

A seesaw mechanism is presented in the neutrino sector and a new phase of CP violation (α) emerges in the interplay between the type-I and type-III seesaw schemes. This phase is inside the mixing term, and thus it cannot be rotated away in the Yukawa Lagrangian and, therefore, the heavy symmetry states cannot be in a diagonal weak basis in the broken phase. Some particular descriptions are analyzed suggesting that if the usual Yukawa couplings are suppressed, leptogenesis still occurs due to a new interacting vertex with fermion triplet T, fermion singlets N, and scalar triple, Σ, which now is included to mediate the interactions. The evaluated CP violation is enough to generate the observed matter-antimatter asymmetry even in the minimal 1N+1T case (independently of α) or in the 2N+1T approach (controlled by α). The latter introduces more CP contributions to leptogenesis due to new diagrams which are now possible even with the suppressed imaginary part of the standard Yukawa couplings and can induce the observed baryon-to-photon ratio. © 2015 American Physical Society.

de Mello C.R.,Federal University of Lavras | Viola M.R.,Federal University of Tocantins
Revista Brasileira de Ciencia do Solo | Year: 2013

Studies of heavy rainfall are of practical interest for the conservation management of natural resources such as watersheds and soil and water. The spatial distribution of these natural rainfall events allows conclusions about regions where the occurrence of heavy rain is more frequent and to estimate their magnitude for locations without rainfall data sets. Thus, the purpose of this study was to map heavy rainfall data from 177 meteorological stations, using a geostatistical approach, for Minas Gerais, identifying the most vulnerable regions in terms of the occurrence of heavy rain. The highest values were estimated for the East and Northwest regions of the state, which can be explained by the influence of the South Atlantic Converge Zone (SACZ), aside from convective rainfall events. In addition, the lowest and intermediate values were found and mapped, respectively, for the North/Northeast and Mid/ South regions of the state. For the rainfall events with longest duration, intensities were high in the Southern region, which can be explained by the more frequent cold weather fronts that induce long-lasting rains.

The aims of the present study were to describe cancer causes and risk perception, and to associate behaviors adopted for the prevention of tumors and cancer family history in individuals with suspect of hereditary cancer syndromes. A convenience sample of 51 individuals was selected from an oncogenetic counseling outpatient clinic in a university hospital in the countryside of the state of São Paulo. An instrument adapted to Brazilian culture was used. The respondents considered their own risk as being the same as the population's risk, and family history was not statistically associated with the performing of preventive exams. These findings highlight the need for intervention by health professionals, especially nurses, who may conduct health education activities for this population, which is an essential component of nursing care in oncogenetics.

Cavalin P.R.,Federal University of Tocantins | Sabourin R.,École de Technologie Supérieure of Montreal | Suen C.Y.,Concordia University at Montréal
Neural Computing and Applications | Year: 2013

In this paper we propose a new approach for dynamic selection of ensembles of classifiers. Based on the concept named multistage organizations, the main objective of which is to define a multi-layer fusion function adapted to each recognition problem, we propose dynamic multistage organization (DMO), which defines the best multistage structure for each test sample. By extending Dos Santos et al.'s approach, we propose two implementations for DMO, namely DSAm and DSAc. While the former considers a set of dynamic selection functions to generalize a DMO structure, the latter considers contextual information, represented by the output profiles computed from the validation dataset, to conduct this task. The experimental evaluation, considering both small and large datasets, demonstrated that DSAc dominated DSAm on most problems, showing that the use of contextual information can reach better performance than other existing methods. In addition, the performance of DSAc can also be enhanced in incremental learning. However, the most important observation, supported by additional experiments, is that dynamic selection is generally preferred over static approaches when the recognition problem presents a high level of uncertainty. © 2011 Springer-Verlag London Limited.

De Carvalho R.L.,Federal University of Tocantins | Rosa P.F.F.,Brazilian Military Institute of Engineering
IEEE International Symposium on Industrial Electronics | Year: 2010

This work proposes an identification system for smart buildings using footstep information. Basically, the system has three modules: pre-processing, feature extraction and selection, and classification of the information. Gait frequency, spectral envelope, cepstral and mel-cepstral analysis and loudness compose the set of parameters used to identify subjects in the smart building. In order to select features, the Fisher's criterion was used. For the classification task, K-Means and K-NN algorithms were performed along with different methodologies for test and validation. Moreover, the best sets were gathered, increasing the accuracy of classification. Several experiments were performed with 15 subjects wearing 6 different footwear. The classification rates were in the range from 33.5% to 97.5%. © 2010 IEEE.

Loading Federal University of Tocantins collaborators
Loading Federal University of Tocantins collaborators