Pelicice F.M.,Federal University of Tocantins |
Pompeu P.S.,Federal University of Lavras |
Agostinho A.A.,State University of Maringa
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.
Pompeu P.S.,Federal University of Lavras |
Agostinho A.A.,State University of Maringa |
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.
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.
[Perception of cancer causes and risk, family history and preventive behaviors of users in oncogenetic counseling]. [Percepção de causas e risco oncológico, história familiar e comportamentos preventivos de usuários em aconselhamento oncogenético.]
Silva T.B.,Federal University of Tocantins
Revista da Escola de Enfermagem da U S P | Year: 2013
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.
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.