Institute Matematica

Rio Grande, Brazil

Institute Matematica

Rio Grande, Brazil
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Montealegre-Quijano S.,Grande Rio University | Montealegre-Quijano S.,São Paulo State University | Cardoso A.T.C.,Grande Rio University | Silva R.Z.,Federal University of Pernambuco | And 2 more authors.
Fisheries Research | Year: 2014

Size at maternity and size at maturity of the blue shark Prionace glauca were studied from samples collected during ten commercial longline fishing cruises off southern Brazil and in adjacent international waters. The sharp increase of the amplitude of the values of reproductive variables at a given fork length (FL) was evidence that from that FL reproduction occurred. Thus, we calculated the proportion of mature sharks in FL classes to estimate the median size at maturity. The accelerated growth of the claspers started before the beginning of the testis maturation and semen production, whereas the accelerated development of the ovary and the oviducal glands started simultaneously. Although most females with mating marks were mature, few had sperm stored in the oviducal glands. The population parameter of size at 50% of maturity was estimated at 171.2. cm FL for females and 180.2. cm FL for males. The median size at maternity was estimated in 193.9. cm FL and half of the females with five to six years old were recruited for reproductive phase of life. As most shark species, P. glauca in the Southwest Atlantic reach maturity at about three-fourths of its maximum size and half of its maximum age. Median litter size was 33 embryos. A positive not significant linear relationship between the uterine fecundity and the size of the pregnant female was observed. © 2014 Elsevier B.V.

Proietti M.C.,Grande Rio University | Reisser J.W.,Grande Rio University | Reisser J.W.,University of Western Australia | Kinas P.G.,Institute Matematica | And 4 more authors.
Marine Ecology Progress Series | Year: 2012

Genetic structure and natal origins of green turtle mixed stocks in southern Brazil were assessed based on analyses of mtDNA control region sequences from the Arvoredo Island (n = 115) and Cassino Beach (n = 101) feeding areas. These were compared to other mixed aggregations to examine structuring, and to Atlantic Ocean nesting colonies to evaluate natal origins through Bayesian mixed stock analysis (MSA). In order to develop novel priors, surface drifter trajectories in the Atlantic were analyzed and combined with rookery data, and we used Kulback-Leibler information measures in order to compare the difference of information among the 4 proposed priors. Each study area presented 12 haplotypes, 10 of which were shared at similar frequencies. Haplotypes CM-A8 and CM-A5 represented ∼60 and 20%, respectively, and remaining haplotypes accounted for <5% of samples. The 2 study areas were genetically similar to all feeding grounds in the western South Atlantic except Almofala, in northeast Brazil, and genetically different from Caribbean and North American mixed stocks. Drifter trajectory analysis revealed that drifters from Ascension and Trindade Islands have a larger chance of reaching Brazil. The priors drifter data and rookery size/drifter data combined contained the most information, but stock estimates were not greatly changed. MSA indicated that Ascension, Aves/Surinam and Trindade were the main stock contributors to the study areas. Since impacts on mixed stocks may affect populations thousands of km away, the results presented here have important implications for the conservation of this endangered species. © 2012 Inter-Research.

Gibert K.,Polytechnic University of Catalonia | Conti D.,University of Los Andes, Venezuela | Conti D.,Institute Matematica
AI Communications | Year: 2015

Clustering techniques find homogeneous and distinguishable prototypes. Careful interpretation of these prototypes is crucial to assist the experts to better organize this know-how and to really improve their decision-making processes. The Traffic Lights Panel was introduced in 2009 as a postprocessing tool to provide understanding of clustering prototypes. In this work, annotated Traffic Lights Panel (aTLP) is presented as an enrichment of the TLP to manage the intrinsic uncertainty related with prototypes themselves. The aTLP handles uncertainty through a quantification of the prototypes' purity based on the variation coefficients (VC) and an associated color-based uncertainty model, with two dimensions-tone and saturation-representing nominal trend and purity of the prototype. An application to a waste-water treatment plant in Slovenia, in a discrete and continuous approach, suggests that aTLP seems a useful and friendly tool able to reduce the gap between data mining and effective decision support, towards informed-decisions. © 2015 - IOS Press and the authors.

Franco T.,Institute Matematica | Goncalves P.,Pontifical Catholic University of Rio de Janeiro | Goncalves P.,University of Minho | Simon M.,French Institute for Research in Computer Science and Automation
Communications in Mathematical Physics | Year: 2016

We consider the weakly asymmetric simple exclusion process in the presence of a slow bond and starting from the invariant state, namely the Bernoulli product measure of parameter (Formula presented.). The rate of passage of particles to the right (resp. left) is (Formula presented.) (resp. (Formula presented.)) except at the bond of vertices (Formula presented.) where the rate to the right (resp. left) is given by (Formula presented.) (resp. (Formula presented.)). Above, (Formula presented.), (Formula presented.), (Formula presented.). For (Formula presented.), we show that the limit density fluctuation field is an Ornstein–Uhlenbeck process defined on the Schwartz space if (Formula presented.), while for (Formula presented.) it is an energy solution of the stochastic Burgers equation. For (Formula presented.), it is an Ornstein–Uhlenbeck process associated to the heat equation with Robin’s boundary conditions. For (Formula presented.), the limit density fluctuation field is an Ornstein–Uhlenbeck process associated to the heat equation with Neumann’s boundary conditions. © 2016 Springer-Verlag Berlin Heidelberg

Marangoni J.C.,Institute Matematica | Costa C.S.B.,Institute Oceanografia Laboratorio Of Ecologia Vegetal Costeira
Estuaries and Coasts | Year: 2012

Spartina alterniflora and Spartina densiflora are native salt marsh plants from the Atlantic coast; their habitats in Patos Lagoon estuary (southern Brazil) are characterized by a microtidal regime (<0.5 m) and, during El Niño events, high estuarine water levels and prolonged flooding due to elevated freshwater discharge from a 200,000-km 2 watershed. During and between El Niño events, the vegetative propagation of these two Spartina species in the largest estuary of southern Brazil (Patos Lagoon) was evaluated by monitoring transplanted plants for 10 years (short-term study) and interpreting aerial photos of natural stands for 56 years (long-term study). During the short-term study, S. alterniflora quickly occupied mud flats (up to 208 cm year -1) by elongation of rhizomes, whereas S. densiflora showed a modest lateral spread (up to 13 cm year -1) and generated dense circular-shaped stands. However, moderate and strong El Niño events can promote excessive flooding and positive anomalies in the estuarine water level that reduce the lateral spread and competitive ability of S. densiflora. During the long-term study, natural stands of S. alterniflora and S. densiflora had steady lateral spread rates of 152 and 5. 2 cm year -1, respectively, over mud flats. In the microtidal marshes of the southwest Atlantic, the continuous long-term lateral expansion of both Spartina species embodies periods of intense flooding stress (moderate and strong El Niños), when there is a decrease of vegetative propagation and less stressful low water periods of fast spread over mud flats (non-El Niño periods and weak intensity El Niños). © 2012 Coastal and Estuarine Research Federation.

Savicki D.L.,Federal University of Rio Grande do Sul | Savicki D.L.,Institute Matematica | Vielmo H.A.,Federal University of Rio Grande do Sul | Krenzinger A.,Federal University of Rio Grande do Sul
Renewable Energy | Year: 2011

A numerical analysis of the three-dimensional temperature and velocity fields in horizontal cylindrical storage tanks was performed. The phenomena of laminar natural convection and vertical stratification of temperature were considered. The developed three-dimensional transient computing code solves the equations of energy and momentum through the finite volume method. The simulation of fluid cooling process inside the tank showed the formation of stratified temperature profiles that matched those obtained experimentally. Based on several simulations, a correlation was proposed for determining the degree of thermal stratification inside the tank regarding thermal and geometrical parameters. From this correlation, an expression was proposed to predict the fluid temperature profiles along the time. This information is very important in many applications, such as in thermosiphon solar water heating systems, where the global efficiency of the system increases with the thermal stratification degree of the working fluid. Another case studied considered that the tank was connected to solar collectors, aiming at investigating the influence of the inlet jet position with and without a baffle plate on the preservation of the thermal stratification. Results showed that the baffle plate modified the velocity and temperature fields close to the inlet jet, allowing a better thermal stratification. Also the suitable choice of the inlet jet position allowed the formation of a more effective thermal stratification. Some other aspects of the internal dynamics of this kind of storage tank are presented and discussed. For the cases studied, the inlet jet next to the top led to a greater thermal stratification. However, it was verified that when the inlet jet temperature remains constant for a long period of time, and thus its temperature approaches the temperature of the water inside the tank, for the same height, the temperature profiles obtained become similar to the case of the inlet located at usual height of 2/3 of the diameter. © 2010 Elsevier Ltd.

Bakri L.,Federico Santa María Technical University | Casteras J.-B.,Institute Matematica
Nonlinearity | Year: 2015

Let (M, g) be a compact riemannian manifold of dimension . We consider two Paneitz-Branson type equations with general coefficients and where Ag and Bg are smooth symmetric (2, 0)-tensors, , and ε is a small positive parameter. Under suitable assumptions, we construct solutions to (E.1) and (E.2) which blow up at one point of the manifold when ε tends to 0. In particular, we extend the result of Deng and Pistoia 2011 (to the case where Ag is the one defined in the Paneitz operator) and the result of Pistoia and Vaira (2013 Int. Math. Res. Not. 2013 3133-58) (to the case n = 8 and (M, g) locally conformally flat). © 2015 IOP Publishing Ltd & London Mathematical Society.

Lazo M.J.,Institute Matematica | Ferreira A.A.,São Paulo State University
Physical Review E - Statistical, Nonlinear, and Soft Matter Physics | Year: 2010

An integrable asymmetric exclusion process with impurities is formulated. The model displays the full spectrum of the stochastic asymmetric XXZ chain plus new levels. We derive the Bethe equations and calculate the spectral gap for the totally asymmetric diffusion at half filling. While the standard asymmetric exclusion process without impurities belongs to the KPZ universality class with an exponent 3 2, our model has a scaling exponent 5 3. © 2010 The American Physical Society.

Lazo M.J.,Institute Matematica
Physics Letters, Section A: General, Atomic and Solid State Physics | Year: 2011

Fractional derivatives and integrations of non-integers orders was introduced more than three centuries ago but only recently gained more attention due to its application on nonlocal phenomenas. In this context, several formulations of fractional electromagnetic fields was proposed, but all these theories suffer from the absence of an effective fractional vector calculus, and in general are non-causal or spatially asymmetric. In order to deal with these difficulties, we propose a spatially symmetric and causal gauge invariant fractional electromagnetic field from a Lagrangian formulation. From our fractional Maxwell's fields arose a definition for the fractional gradient, divergent and curl operators. © 2011 Elsevier B.V. All rights reserved.

Lazo M.J.,Institute Matematica | Krumreich C.E.,Institute Matematica
Journal of Mathematical Physics | Year: 2014

In the present work, we redefine and generalize the action principle for dissipative systems proposed by Riewe by fixing the mathematical inconsistencies present in the original approach. In order to formulate a quadratic Lagrangian for non-conservative systems, the Lagrangian functions proposed depend on mixed integer order and fractional order derivatives. As examples, we formulate a quadratic Lagrangian for a particle under a frictional force proportional to the velocity and to the classical problem of an accelerated point charge. © 2014 AIP Publishing LLC.

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