Estudo da precocidade diagnóstica dos melanomas cutâneos primários em Porto Alegre por análise de imagem computadorizada

Fundamentos: A literatura tem demonstrado que a detecção precoce e a remoção cirúrgica em fases iniciais reduz a mortalidade do melanoma e que, em conseqüência, a identificação do melanoma em fases curáveis deve ser encorajada. Objetivos: O interesse principal do estudo foi conhecer se os melanomas cutâneos, no meio, estão sendo diagnosticados em fases iniciais, através de método reprodutível e armazenável. Metodologia: Foi realizado um estudo transversal com os casos de melanomas cutâneos primários, analisados nos laboratórios de patologia de Porto Alegre, de 1° de janeiro de 1994 a 30 de junho de 1995, a fim de avaliar se os diagnósticos foram realizados em estágios precoces. Os casos foram revisados por três dermatopatologistas, que classificaram quanto ao tipo histológico e quanto ao nível de invasão de Clark. Foi realizado um consenso com pelo menos duas concordâncias. A espessura de Breslow foi considerada fator prognóstico determinante e foi medida através de um sistema de análise de imagem computadorizada, por dois membros da equipe. Resultados: Do total de 279 casos que preencheram os critérios de inclusão, 2,15% eram intraepiteliais. Dos melanomas invasivos, 52% tinham espessura ≤ 1,5 mm. Quando agrupado por sexo e procedência, as mulheres de Porto Alegre, capital do estado do Rio Grande do Sul, tiveram a mais alta taxa de diagnóstico precoce (75% ≤ 1,5 mm). O tronco foi o sítio predominante no homem e freqüente na mulher. O melanoma de espalhamento superficial foi o tipo histológico mais freqüente (80,9%), seguido pelo nodular (10,1%). Para definir os determinantes do diagnóstico precoce, foram realizados cruzamentos simples, dos melanomas intraepiteliais somados aos de espessura <0,76 mm, com o sexo, a idade, a procedência, a situação previdenciária, a região anatômica e o tipo histológico. A análise de variáveis múltiplas demonstrou que apenas o sexo (feminino), o sítio anatômico (outras regiões exceto membros inferiores) e a procedência (Porto Alegre) mostraram-se variáveis independentes para determinar um diagnóstico precoce. A idade ≥ 40 anos apresentou significância próxima ao limite. O tipo histológico foi excluído do modelo, uma vez que gerou instabilidade estatística. Conclusão: Embora o número de casos fosse pequeno, o diagnóstico do melanoma ainda é tardio (52% com até 1,5 mm de espessura). Entretanto, existe um subgrupo de diagnóstico precoce que são mulheres, sobretudo de Porto Alegre, possivelmente por estarem mais atentas e informadas sobre os riscos do melanoma. As mudanças no estilo de vida, nas últimas décadas, provavelmente são responsáveis pela maior incidência no tronco e pela alta freqüência de melanoma de espalhamento superficial encontrada. A análise da espessura tumoral por projeção em tela de computador mostrou-se um recurso auxiliar vantajoso.

A Modular and digitally programmable interface based on band-pass sigma-delta modulator for mixed-signal systems-on-chip

The focus of this thesis is to discuss the development and modeling of an interface architecture to be employed for interfacing analog signals in mixed-signal SOC. We claim that the approach that is going to be presented is able to achieve wide frequency range, and covers a large range of applications with constant performance, allied to digital configuration compatibility. Our primary assumptions are to use a fixed analog block and to promote application configurability in the digital domain, which leads to a mixed-signal interface. The use of a fixed analog block avoids the performance loss common to configurable analog blocks. The usage of configurability on the digital domain makes possible the use of all existing tools for high level design, simulation and synthesis to implement the target application, with very good performance prediction. The proposed approach utilizes the concept of frequency translation (mixing) of the input signal followed by its conversion to the ΣΔ domain, which makes possible the use of a fairly constant analog block, and also, a uniform treatment of input signal from DC to high frequencies. The programmability is performed in the ΣΔ digital domain where performance can be closely achieved according to application specification. The interface performance theoretical and simulation model are developed for design space exploration and for physical design support. Two prototypes are built and characterized to validate the proposed model and to implement some application examples. The usage of this interface as a multi-band parametric ADC and as a two channels analog multiplier and adder are shown. The multi-channel analog interface architecture is also presented. The characterization measurements support the main advantages of the approach proposed.

Uma interface para o aumento da faixa de freqüências de operação de FPAAS

O crescente avanço nas mais diversas áreas da eletrônica, desde instrumentação em baixa freqüência até telecomunicações operando em freqüências muito elevadas, e a necessidade de soluções baratas em curto espaço de tempo que acompanhem a demanda de mercado, torna a procura por circuitos programáveis, tanto digitais como analógicos, um ponto comum em diversas pesquisas. Os dispositivos digitais programáveis, que têm como grande representante os Field Programmable Gate Arrays (FPGAs), vêm apresentando um elevado e contínuo crescimento em termos de complexidade, desempenho e número de transistores integrados, já há várias décadas. O desenvolvimento de dispositivos analógicos programáveis (Field Programmable Analog Arrays – FPAAs), entretanto, esbarra em dois pontos fundamentais que tornam sua evolução um tanto latente: a estreita largura de banda alcançada, conseqüência da necessidade de um grande número de chaves de programação e reconfiguração, e a elevada área consumida por componentes analógicos como resistores e capacitores, quando integrados em processos VLSI Este trabalho apresenta uma proposta para aumentar a faixa de freqüências das aplicações passíveis de serem utilizadas tanto em FPAAs comerciais quanto em outros FPAAs, através da utilização de uma interface de translação e seleção de sinais, mantendo características de programabilidade do FPAA em questão, sem aumentar em muito sua potência consumida. A proposta, a simulação e a implementação da interface são apresentadas ao longo desta dissertação. Resultados de simulação e resultados práticos obtidos comprovam a eficácia da proposta.

Efeitos biológicos dos campos eletromagnéticos de ultra alta freqüência

Vários estudos têm sugerido que seres vivos podem ser suscetíveis aos campos eletromagnéticos (CEMs). Os supostos efeitos dos Campos Eletromagnéticos de Ultra Alta Freqüência (CEMUAFs) em sistemas biológicos são pouco conhecidos. Os relatos de um possível efeito biológico dependente da alteração de estados de oxidação entre pares de radicais sugerem um mecanismo de transdução orgânica para os campos. Outros trabalhos obtiveram alterações na sinalização celular e defesas antioxidantes após a exposição CEMUAFs e, tais alterações, poderiam ser um agente causador de doenças como, por exemplo, a leucemia infantil, esta já correlacionada com a exposição aos CEMs. Desta forma o objetivo deste estudo foi investigar se o CEMUAF (834 MHz) poderia interferir com o balanço oxidativo de planárias e ratos, assim como, estudar a participação de enzimas responsáveis pela hidrólise de nucleotídeos, enzimas estas reconhecidas por serem influenciadas pela ação de radicais livres. As planárias foram expostas por 1, 3 e 6 dias (8 h/dia). Após a exposição foi feito um homogenato de todo o corpo de cada animal. Foi encontrado um aumento na atividade da superóxido desmutase (SOD) e um decréscimo na atividade da catalase (CAT) e na defesa antioxidante não-enzimática (TRAP) após 6 dias de exposição. Adicionalmente, houve um aumento na freqüência de micronúcleos (MN) após 3 e 6 dias de exposição. Não houve alteração nos parâmetros de dano oxidativo a lipídios (TBARS) e proteínas (Carbonil) em nenhum dos tempos de exposição. Estes resultados sugerem um aumento nos níveis de radicais livres e de danos aos ácidos nucléicos. Estudos posteriores deverão determinar se estes efeitos apresentam ou não associações do tipo causa e efeito. Foram utilizados três modelos com ratos. No primeiro modelo, animais com idades de 30, 80 e 210 dias foram expostos por 6 dias (7:30 h/dia). Não foram encontradas mudanças nos parâmetros de TRAP, TBARS e Carbonil em nenhuma das idades expostas ao CEMUAF. Estes resultados sugerem que os tempos de exposição utilizados não foram suficientes para causar alguma mudança perceptível nos parâmetros de estresse oxidativo. No segundo modelo, utilizou-se o sangue e fígado dos neonatos expostos ao CEMUAF ainda no útero de suas mães durante todo o seu desenvolvimento embrionário (8:30 h/dia). Não foram encontradas mudanças em nenhum parâmetro oxidativo. Foi encontrado um aumento na freqüência de MN nas hemácias, sugerindo um efeito genotóxico da irradiação do celular afetando o tecido hematopoiético dos fetos. No terceiro modelo, utilizou-se o sangue de ratos adultos (180 dias) expostos por 12 dias (8:30 h/dia). Os níveis da hidrólise de ATP e ADP estavam aumentados no grupo irradiado. Nenhum efeito foi observado nas atividades da SOD e da CAT, sugerindo nenhuma participação de radicais livres nestes resultados. Ainda são necessários muitíssimos estudos para determinar quais os mecanismos transdutores dos CEMUAFs em sistemas biológicos e de que forma esta interação ocorre, porém estes resultados sugerem: (a) um papel para os radicais livres sobre, pelo menos, alguns dos efeitos atribuídos aos CEMUAFs e (b) que os organismos em fase de formação podem ser mais sensíveis aos campos. Por fim, sugerimos que sistemas biológicos podem sofrer a ação da irradiação com uma quantidade de energia muito menor do que a esperada para promover algum efeito no metabolismo.

Conditional alphas and realized betas

This paper proposes a two-step procedure to back out the conditional alpha of a given stock using high-frequency data. We rst estimate the realized factor loadings of the stocks, and then retrieve their conditional alphas by estimating the conditional expectation of their risk-adjusted returns. We start with the underlying continuous-time stochastic process that governs the dynamics of every stock price and then derive the conditions under which we may consistently estimate the daily factor loadings and the resulting conditional alphas. We also contribute empiri-cally to the conditional CAPM literature by examining the main drivers of the conditional alphas of the S&P 100 index constituents from January 2001 to December 2008. In addition, to con rm whether these conditional alphas indeed relate to pricing errors, we assess the performance of both cross-sectional and time-series momentum strategies based on the conditional alpha estimates. The ndings are very promising in that these strategies not only seem to perform pretty well both in absolute and relative terms, but also exhibit virtually no systematic exposure to the usual risk factors (namely, market, size, value and momentum portfolios).

Effect of intensification on grow out of the Amazon River prawn, Macrobrachium amazonicum

The effects of intensification on growth, survival, productivity, population structure, and distribution of harvested biomass in individual size classes of Macrobrachium amazonicum in semi-intensive culture were evaluated. Postlarvae (0.01 g) were stocked in 12 ponds at densities of 10, 20, 40, and 80/m(2) (three replicates per treatment) and raised for 5.5 mo. Average individual weight significantly decreased and productivity significantly increased as stocking density increased (P < 0.001), while survival was not affected (P > 0.05). Prawn mean weight at harvest ranged from 3.6 (80/m(2)) to 7.0 g (10/m(2)). Average survival ranged from 65.5% (40/m(2)) to 72.8% (20/m(2)), while productivity ranged from 508 (10/m(2)) to 2051 kg/ha (80/m(2)). Harvested biomass showed a clear bimodal distribution in individual size classes indicating the occurrence of heterogeneous growth, which may affect management and market strategies. Harvested biomass of prawns weighing more than 7 g (the best market size) increases for stocking densities up to 40/m(2) and stabilizes between 40 and 80/m(2). Growth reduction was associated with a decreasing frequency and average weight of green claw 1 and green claw 2 male morphotypes and adult females as density increased. Thus, the distribution of male morphotypes and sexually mature females are affected by density-dependent factors. Results suggest that prawn density plays an important role on M. amazonicum grow-out phase, as has been demonstrated for other species of the genus Macrobrachium. M. amazonicum tolerates grow-out intensification and may be raised in both semi-intensive and intensive systems stocked at very high densities yielding high productivity.

High-resolution electrocardiography in the diagnosis of arrhythmogenic right ventricular cardiomyopathy in Boxer dogs

Com o objetivo de avaliar a importância da eletrocardiografia de alta resolução no diagnóstico da cardiomiopatia arritmogênica do ventrículo direito do Boxer, 20 cães sem evidências de doença cardíaca estrutural à avaliação ecodopplercardiográfica foram agrupados de acordo com a frequência de arritmias ventriculares, avaliadas pela eletrocardiografia ambulatorial de 24 horas, e submetidos ao exame eletrocardiográfico de alta resolução. Duração do complexo QRS filtrado, duração dos sinais de baixa amplitude (menor que 40µV) dos últimos 40 milissegundos do complexo QRS e raiz quadrada média da voltagem ao quadrado dos últimos 40 milissegundos do complexo QRS (RMS40) foram as variáveis avaliadas. Não foram observadas diferenças significativas entre os grupos em relação às variáveis estudadas. Sendo assim, os resultados do presente estudo sugerem que a eletrocardiografia de alta resolução não é uma ferramenta útil no auxílio diagnóstico da cardiomiopatia arritmogênica do ventrículo direito dos cães da raça Boxer que não apresentam alterações miocárdicas evidentes ou disfunção sistólica.

Cultura organizacional orientada à qualidade: um survey nas concessionárias automotivas brasileiras certificadas com a ISO 9001

The study aims identify the existence of quality culture in Brazilian automotive dealerships with ISO 9001, motivated by this research problem: exist a quality culture in this dealerships, which facilitates the adoption of quality practices supported by ISO 9001? For referencing, the theoretical review was written in five themes: organizational culture, quality culture, total quality management, ISO 9001 quality management system and the Brazilian automobile industry. As regards the methodological aspects, the research has an applied nature, with a quantitative approach, being exploratory in their objectives, and bibliographic, documental and survey as technical procedures. The organizations participating in the study were all Brazilian automotive dealerships certified with ISO 9001. The research intended cover all the 80 active dealers with ISO 9001 certification identified by the Brazilian Committee for Quality (ABNT CB-25). The survey recorded participation of 32 companies (response rate 40%). The questionnaire was sent to seller managers, formatted into five sections: 1) introductory message 2) manager profile, 3) reasons for implementation and benefits generated by ISO 4) adoption levels of quality practices and 5) diagnosis of organizational culture. The questions contained in sections 2 and 3 were structured in multiple choice, and in the remaining sections were structured in Likert 5-point scale. The statistical method used (data analysis), was the descriptive statistics, for data representation in frequency percentage (FP) and standard level (SL). The results showed that the interviewed dealerships have an organizational culture with very high levels of prevalence in "outcome orientation" and "attention to detail" cultural dimensions. In addition, about the other two dimensions considered conducive to quality (innovation and teamwork/respect for people), both observed high prevalence. Based on the present results, concluded that the organizational culture of Brazilian dealerships with ISO 9001 are quality oriented, being conducive to adoption of quality practices supported by TQM Systems. However, it is important to mention that the quality culture identified is not sufficiently developed to adopt quality practices at optimal levels, which sets up an unfavorable scenario to deals with highly rigorous customer

Reconhecimento de voz através de unidades menores do que a palavra, utilizando Wavelet Packet e SVM, em uma nova estrutura hierárquica de decisão

The automatic speech recognition by machine has been the target of researchers in the past five decades. In this period have been numerous advances, such as in the field of recognition of isolated words (commands), which has very high rates of recognition, currently. However, we are still far from developing a system that could have a performance similar to the human being (automatic continuous speech recognition). One of the great challenges of searches for continuous speech recognition is the large amount of pattern. The modern languages such as English, French, Spanish and Portuguese have approximately 500,000 words or patterns to be identified. The purpose of this study is to use smaller units than the word such as phonemes, syllables and difones units as the basis for the speech recognition, aiming to recognize any words without necessarily using them. The main goal is to reduce the restriction imposed by the excessive amount of patterns. In order to validate this proposal, the system was tested in the isolated word recognition in dependent-case. The phonemes characteristics of the Brazil s Portuguese language were used to developed the hierarchy decision system. These decisions are made through the use of neural networks SVM (Support Vector Machines). The main speech features used were obtained from the Wavelet Packet Transform. The descriptors MFCC (Mel-Frequency Cepstral Coefficient) are also used in this work. It was concluded that the method proposed in this work, showed good results in the steps of recognition of vowels, consonants (syllables) and words when compared with other existing methods in literature

Análise de superfícies seletivas de freqüência para aplicações em ondas milimétricas

This work consists in the development of a theoretical and numerical analysis for frequency selective surfaces (FSS) structures with conducting patch elements, such as rectangular patches, thin dipoles and cross dipoles, on anisotropic dielectric substrates. The analysis is developed for millimeter wave band applications. The analytical formulation is developed in the spectral domain, by using a rigorous technique known as equivalent transmission line method, or immitance approach. The numerical analysis is completed through the use of the Galerkin's technique in the Fourier transform domain, using entire-domain basis functions. In the last decades, several sophisticated analytical techniques have been developed for FSS structure applications. Within these applications, it can be emphasized the use of FSS structures on reflecting antennas and bandpass radomes. In the analysis, the scattered fields of the FSS geometry are related to the surface induced currents on the conducting patches. After the formulation of the scattering problem, the numerical solution is obtained by using the moment method. The choice of the basis functions plays a very important role in the numerical efficiency of the numerical method, once they should provide a very good approximation to the real current distributions on the FSS analyzed structure. Thereafter, the dyadic Green's function components are obtained in order to evaluate the basis functions unknown coefficients. To accomplish that, the Galerkin's numerical technique is used. Completing the formulation, the incident fields are determined through the incident potential, and as a consequence the FSS transmission and reflection characteristics are determined, as function of the resonant frequency and structural parameters. The main objective of this work was to analyze FSS structures with conducting patch elements, such as thin dipoles, cross dipoles and rectangular patches, on anisotropic dielectric substrates, for high frequency applications. Therefore, numerical results for the FSS structure main characteristics were obtained in the millimeter wave bando Some of these FSS characteristics are the resonant

A implementação do você em cartas pessoais norte-riograndenses do século XX

Considering the theoretical and methodological presuppositions of Variationist Sociolinguistics (cf. WEINREICH; LABOV; HERZOG, 2006; LABOV, [1972] 2008), in this dissertation, we describe and analyze the process of variation/change involving the personal pronouns tu and você, and its extension in the pronominal paradigm in Brazilian Portuguese (BP), in three sets of personal letters written by people from Rio Grande do Norte (RN) along the 20th century. The discursive universe of those letters is news from the cities in which the informers lived and the themes from their everyday life (trade, jobs, trips, family and politics). Part of the analyzed letters integrate the written by hand minimum corpus of the Projeto de História do Português Brasileiro no Rio Grande do Norte (PHPB-RN). We are based on previous studies about the pronominal system in BP Menon (1995), Faraco (1996), Lopes e Machado (2005), Rumeu (2008), Lopes (2009), Lopes, Rumeu e Marcotulio (2011), Lopes e Marcotulio (2011) e Martins e Moura (2012) , which register the form você replaces tu from the end of the first half of 20th century and attest the following situation: while (a) the imperative verbal forms, (b) the explicit subjects and (c) prepositional complement pronouns are favorable contexts for você, the (d) non imperative verbal forms (with null subject), (e) the non prepositional complement pronoun and (f) the possessive pronoun are contexts of resistance of tu. The results got in this dissertation confirm, partially, the statements defended by the previous studies regarding the favorable contexts for the implementation of você in BP: (i) there are, in the letters from the first two decades of 20th century (1916 to 1925), high frequency of the usage of the form você (98%); (ii) in the personal letters of RN especially in the love letters, in which there are higher recurrence of intimate subjects the discursive universe proved to be itself very relevant in the determination/conditions of the forms of tu; (iii) the unique feminine informer of our sample uses, almost categorically, the forms of tu in letters of the period from 1946 to 1972; (iv) the letters corresponding to the period from 1992 to 1994 present a significant usage of the forms associated to the innovating você, letting appear the change is already implemented in the system of BP and there are, in that set of letters, strong evidences that make us state the pronominal forms of non prepositional complement (accusative/ dative) related to tu are also implemented in a system with an almost categorical usage of você

Análise molecular dos éxons 8 a 11 do gene da p53 em amostras de câncer de colo de útero no Rio Grande do Norte

Mutations on TP53 gene are common in human cancer but not in cervical cancer where they are rarely found and the inactivation and degradation of p53 protein are attributed to the action of E6 viral oncogene from high risk human papillomavirus (HPV). Analysis of cervical cancer cell lines suggests that HPV negative samples shows mutation on TP53, but clinical approaches didn t confirmed this hypothesis. However, in most TP53 mutations studies on cervical cancer, only the exons 5 to 8 were analyzed. Approximately 90% of mutations described are on this region. Recent studies on several cancer suggests that mutation frequency in the other exons must be considered. The aim of this work was to verify whether mutations on coding and non-coding regions occur in cancer tissue from cervical cancer in patients from Rio Grande do Norte using Denaturing Gradient Gel Electrophoresis (DGGE) as screening tool. Exons 8 to 11 were analyzed including some introns from 80 tumor samples and 8 peripheral blood samples from healthy women. DNA were submitted to PCR using primers with GC clamp on the end of one of them. The results were observed for each region after DGGE and silver staining. It was observed no amplified fragment with different migration profile from those obtained from DNA of peripheral blood. These results agree with those from literature where TP53 mutations in cervical cancer have been described in a very low frequency

Modeling of interfaces in two-dimensional problems using solid finite elements with high aspect ratio

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Características sociodemográficas, hábitos de sono, estado cognitivo e funcional após acidente vascular cerebral

ABSTRACT Introduction: The cerebrovascular accident (CVA) is an important cause of neurological impairment. Few data about the factors associated with morbidity of cerebrovascular accident are found in Brazil. Objectives: Evaluate sociodemographic characteristics, sleep habits, cognitive and functional status of patients with cerebrovascular accident. Methods: The patients evaluated through questionnaire Step 1 to survey the sociodemographic characteristics and Modified Rankin Scale for functional assessment. The neurological degree was evaluated by the National Institutes of Health Stroke Scale (NIHSS), the sleep Habits questionnaire for sleep and cognitive status by the Mini-Examination of the Mental State (MEMS). The data were analyzed using the chi-square test to determine differences in proportions of variables and linear regression analysis. Results: 305 patients were evaluated and the larger number of subjects was between 50 and 69 years (40%), most patients had no formal education (40.3%) and had ischemic type of cerebrovascular accident (72.5%). In the analysis of the functionality it was found that most patients had moderate impairment (55.1%). The results of the sleep habits showed that 63,6% of patients had one more person in the bedroom,12,3% complained about too much noise in the 11 room and 35% of too much light. From these patients 5,8% were smokers, 7,8% and 70,1% drank coffee drinkers, 28,6% had difficulty in initiate to sleep and woke up 37,6% in the middle of the night. Were showed complaints about nightmares (11%), feeling of suffocation (37,7%) and 35% felt very sleepy during the day. In addition, 95% were unemployed, 80,5% did not perform physical activities and 95,4% did not perform mental activities. The cognitive screening conducted a determined association of cognitive status with age and education level and neurological status. Conclusion: The study showed a high frequency of cases of cerebrovascular accident with functional dependence in a moderate degree, identified that many patients do not follow hygienic measures of sleep and found that the assessment of cognitive deficits must take into consideration the age, educational level and degree of neurological patients. We suggest the need for programs of assistance to victims of cerebrovascular accident patients, with a multidimensional approach including the rehabilitation team, the role of sleep medicine and Neuropsychology, so that patients have access to a more appropriate functional rehabilitation, develop a lifestyle that ensures a good sleep quality and are evaluated and rehabilitated with regard to cognitive impairment

Uso de habitat e comportamento do boto-cinza sotalia guianensis em uma zona estuarina do estado de Sergipe, nordeste do Brasil a biotecnologia vegetal como alternativa para a cotonicu

To clarify the functional mechanisms of habitat use is necessary to analyze it in conjunction with the conduct performed by animals. The occurrence, distribution and use of space are characteristic of a species resulting from habitat selection that is in search of conditions favorable to its survival. One can relate the physical and biological factors of the environment with the ecological characteristics of the species, since these factors act by regulating the ecological success of organisms, and from there you can get important information about the habitat use and behavior of individuals. This study aimed to characterize the use of habitat and diurnal activity expressed by the Guiana dolphin, Sotalia guianensis in an estuarine area of Sergipe state, Brazil, analyzing the influence of tide and time days on the occurrence of animals and behavior s state, and group s size and composition in this cetacean species. From March 2009 to February 2010, focal groups observations of dolphins were made from fixed - point and records snapshots of data taken every 5 min. in the interval from 6 a.m to 6 p.m, in alternating shifts. The results showed that the constant presence of animals in the area of the Sergipe River estuary indicates that this is an important area of occurrence of S. guianensis, which use the region mainly in the morning, at low tide and as a feeding. As in other regions of northeastern Brazil, small groups formed 2-12 individuals were most common, with adults and immatures. The high frequency of immature animals may indicate that this area of the estuary is used as brood area and parental care of pups and young animals, since the immature animals were very associated with adults and monitoring the activities of foraging / feeding may be related to a form of learning or training of such behavior