Relações interorganizacionais e confiança no setor da carcinicultura: um estudo de caso na camanor produtos marinhos

This study investigated how the types of confidence based on competence and good will act in the formation and maintenance of cooperation relationships between the Camanor and its partners (Aquatec, Purina, Caçuá, Uvifrios and Malta / Cleyton). It used organizational approaches on networks based primarily on studies of Powell (1987, 1990), Das and Teng (2000, 2001), Child (2001) and Contractor and Lorange (2004) which have described the advantages that cooperative relationships can provide, as well as their limits as alternative governance structures. Confidence has been considered an important factor affecting the actions and development of organizations involved in networks or in strategic alliances (ZAHEER; HARRIS, 2006) and is the most appropriate control mechanism in these situations (SYDOW, 1998). Confidence is seen from two different approaches: the economic and the sociological (ZAHEER; HARRIS, 2006). To facilitate the understanding of confidence some typologies have been created, as proposed by Barney and Hansen (1994), Lane (1998), Das and Teng (2000), Child (2001) and Wever, Martens and Vandenbempt (2005). This study made use of the case study as proposition of Yin (2005). Semi-structured interviews were held with pre-determined routes, in a single stage performed in early 2008. The research subjects were owners and / or responsible for Camanor and its business partners (Aquatec, Purina, Caçuá, Uvifrios and Malta / Cleyton). Also secondary data were collected in several sites related to the industry and enterprises studied, in addition to data collected by previous studies conducted by CARCINEREDES (2006). The primary data were analyzed using the analysing technique of the content proposed by Bardin (1994). Regarding the secondary data, they were qualitatively analyzed according to documentary analysis technique (BARDIN, 1994). Thus, through the data collected, could be concluded that although there is confidence based on good faith in relationships(UZZI, 1998; OF; TENG, 2001), their presence does not determine the formation and / or maintenance of a partnership, serves only in order to facilitate the relationship, making them more flexible. The confidence based on competence (DAS; TENG, 2001) influenced the formation and maintenance of relations studied. Because whether or not to form a relationship with another organization it is used the perception of the partner acts, namely the reputation (image) as decision basis. And it is through the verification of the performance of the partner activities that will determine the continuation of the partnership

Utilização de um aplicativo de simulação computacional na avaliação de desempenho térmico de protótipo de habitação de interesse social (his)

This Masters Degree dissertation seeks to make a comparative study of internal air temperature data, simulated through the thermal computer application DesignBuilder 1.2, and data registered in loco through HOBO® Temp Data Logger, in a Social Housing Prototype (HIS), located at the Central Campus of the Federal University of Rio Grande do Norte UFRN. The prototype was designed and built seeking strategies of thermal comfort recommended for the local climate where the study was carried out, and built with panels of cellular concrete by Construtora DoisA, a collaborator of research project REPESC Rede de Pesquisa em Eficiência Energética de Sistemas Construtivos (Research Network on Energy Efficiency of Construction Systems), an integral part of Habitare program. The methodology employed carefully examined the problem, reviewed the bibliography, analyzing the major aspects related to computer simulations for thermal performance of buildings, such as climate characterization of the region under study and users thermal comfort demands. The DesignBuilder 1.2 computer application was used as a simulation tool, and theoretical alterations were carried out in the prototype, then they were compared with the parameters of thermal comfort adopted, based on the area s current technical literature. Analyses of the comparative studies were performed through graphical outputs for a better understanding of air temperature amplitudes and thermal comfort conditions. The data used for the characterization of external air temperature were obtained from the Test Reference Year (TRY), defined for the study area (Natal-RN). Thus the author also performed comparative studies for TRY data registered in the years 2006, 2007 and 2008, at weather station Davis Precision Station, located at the Instituto Nacional de Pesquisas Espaciais INPE-CRN (National Institute of Space Research), in a neighboring area of UFRN s Central Campus. The conclusions observed from the comparative studies performed among computer simulations, and the local records obtained from the studied prototype, point out that the simulations performed in naturally ventilated buildings is quite a complex task, due to the applications limitations, mainly owed to the complexity of air flow phenomena, the influence of comfort conditions in the surrounding areas and climate records. Lastly, regarding the use of the application DesignBuilder 1.2 in the present study, one may conclude that it is a good tool for computer simulations. However, it needs some adjustments to improve reliability in its use. There is a need for continued research, considering the dedication of users to the prototype, as well as the thermal charges of the equipment, in order to check sensitivity

Atividade antiplasmódica e toxicológica de plantas medicinais usadas popularmente no Brasil : uma abordagem etnobotânica

Malaria is a disease of global distribution, recognized by governments around the world as a serious public health problem, affecting more than 109 countries and territories and endangering more than 3.3 billion people. The economic costs of this disease are also relevant: the African continent itself has malaria-related costs of about $ 12 billion annually. Nowadays, in addition to chloroquine, Plasmodium falciparum is resistant to many drugs used in the treatment of malaria, such as amodiaquine, mefloquine, quinine and sulfadoxine-pyrimethamine; resistance of Plasmodium vivax to treatments, although less studied, is also reported. Nature, in general, is responsible for the production of most known organic substances, and the plant kingdom is responsible for the most of the chemical diversity known and reported in the literature. Most medicinal plants commercialized in Brazil, however, are of exotic origin, which makes the search for endemic medicinal plants, besides a patent necessity, a fascinating subject of academic research and development. This study aimed to: (i) verify the antimalarial activity of ethanolic and hydroalcoholic extracts of Boerhavia paniculata Rich. And acetonic extract of Clethra scabra Pers. in Swiss albino mice infected by Plasmodium berghei NK65, (ii) observe possible combined effects between the course of infection by P. berghei NK65 and administration of these extracts in Swiss albino mice, and (iii) conduct a preliminary study of the acute toxicity of these extracts in Swiss albino mice. All extracts notable pharmacological activities - with parasite infections inhibitions ranging from 22% to 54%.These characteristics suggest that the activities are relevant, although comparatively lower than the activity displayed by the positive control group (always above 90%). The general framework of survival analysis demonstrates an overall reduction in survival times for all groups. Necroscopy has not pointed no change in color, shape, size and/or consistency in the evaluated organs - the only exception was the livers of rats submitted to treatment to hydroalcoholic extracts: these organs have been presented in a slightly congestive aspect with mass increasing roughly 28% higher than the other two groups and a p-value of 0.0365. The 250 mg/Kg ethanolic group has been pointed out by the Dunn s post test, as the only class with simultaneous inequalities (p<0.05) between positive and negative control groups. The extracts, notably ethanol extract, have, in fact, a vestigial antimalarial activity, although well below from the ones perceived to chloroquine-treated groups; nevertheless, the survival times of the animals fed with the extracts do not rise by presence of such therapy. Both the toxicopharmacological studies of the synergism between the clinical course of malaria and administration of extracts and the isolated evaluation of toxicity allow us to affirm the absence of toxicity of the extracts at the level of CNS and ANS, as well as their non-influence on food and water consumption patterns, until dosages of 500 mg/Kg. Necroscopic analysis leads us to deduct a possible hepatotoxic effect of hydroalcoholic extract at dosages of 500 mg/Kg, and an innocuous tissue activity of the ethanol extract, in the same dosage. We propose a continuation of the studies of these extracts, with protocol modifications capable of addressing more clearly and objectively their pharmacological and toxicological aspects

A influência do sorriso gengival no vedamentos labial

Ideally the smile should expose minimal gingival, therefore patients with gummy smile and passive eruption altered or excessive marginal gingivae, usually excessive gingival display because incomplete anatomical crown exposure is present. If the maxillary incisor show at rest is optimal, active upper incisor intrusion should not be iniciated. To achieve a smile with minimal gingival exposure, the anatomic crown should be fully exposed by surgical crown lengthening. Precise determination of the location of cementoenamel junction prior to surgery, precise placement of incisions and correct establish of biological width are necessary in order to achive this goal. One protocol is decribed and clinical results from 15 brazilian subjects, after three years post surgery are showed

Análise jurídico-constitucional do fomento aos campos maduros de produção de petróleo no Brasil

The oil activities in Brazil had been started in an intensive way in the end of the 30 s and in the beginning of the 40 s. Many of the brazilians fields discovered in the past are nowadays in decline. They are called ―mature fields‖. These fields, because of the decline situation that characterizes them, are not interesting for the majors. The majors want the big fields and big productions. On the other hand, they could be interesting for the small and medium enterprises. The mature oil fields are instruments of development, they have oil and the oil production is an activity connected with many social and economics benefits: jobs, taxes, royalties, etc. The Brazilian State, in this context, needs to realize actions to promote the activities in the mature oil fields, especially with the work of the small and mediums enterprises. Many of the onshore brazilian mature fields are located at the Northeast, a region matched by many social and economic problems. The activities in the mature fields of the Northeast Region could solve some of its problems. The present research analyses the mature oil fields and its situations in Brazil, making criticisms and suggestions. The methodology adopted is theoretical and descriptive, with literature review, case law and legislation (Constituição Federal de 1988, ―Law of the Oil‖). This research examines the following points: mature fields rounds and its documents, name and definition of the mature fields, definition of small and medium enterprises, environmental aspects, concentration of certain activities of the sector and the royalties

Reconfigurações industriais das regiões metropolitanas do Nordeste: uma análise a partir do emprego formal

Industrial development experienced by Brazil from the 1950s, changed the concentration of population in the country. The process of development of domestic industry, concentrated in urban areas, crowded growing portion of the population.The Southeast region during the first stage of industrialization driven by the state, with the implementation of Plan goals, captained the major industrial projects implemented in the period and became the main industrial center of the country.In the decade from 1960 to 1980 the state action was marked by numerous regional development projects, softening the industrial concentration and Brazilian investment redirected to the Northeast.The second National Development Plan implemented in the 1970s led to major investments Northeast.This period marked the widespread urban growth and institutionalization of the first metropolitan areas in Brazil.The change of this developmental process is altered with the fiscal and financial crisis of the state in the 1980s and 1990s and spending cuts aimed at national development, reorienting the economy to liberal policies of economic liberalization and reduction of activity in the economy.Industrial policy was relegated to local development plans from the 1990s to the federating units fitting the wide use of tax incentives, the "war tax" to the continued industrialization process.In this context of the national economy work seeks to analyze the industrial setting in the metropolitan areas of Fortaleza, Recife and Salvador between 1995 and 2010.Although the metropolitan areas of Fortaleza, Recife and Salvador are the main urban centers of the Northeast, responsible for the advancement of industrial development, reconfigurations occurred between 1995 and 2010 by changing the level of industrial specialization built by regional division of labor in these regions.The work will be carried out by the method of descriptive analysis of the literature review on regional and urban development.Constitute quantitative method as the secondary data analysis of formal employment from the Annual Social Information (RAIS) Ministry of Labour and Employment (MTE).Using data RAIS / MTE analyzes the industrial specialization index using the Locational Quotient (LQ).Thus, it is assumed as a parameter analysis QL> 1, when the region has become specialized in a particular sector or QL <1, when the region does not have expertise in industrial sector analyzed.The conclusion of study indicates that there was in these metropolitan areas maintained the same bias hub.Fiscal policies, the states, was not successful in diversifying the productive structure and the Northeast region itself.This result is demonstrated by the need and dependence on state investments in the region to promote development.Industrial policies of recent years have been positive to meet the objectives of employment generation, but there must be specific policies for better diversification of production, in addition to integrating the economy of the Northeast sector and regionally

Formação de professores, saberes, reflexividade e apropriação da cultura digital no Projeto Um Computador por Aluno (UCA)

This study investigates teacher training and cognitive practice of teachers in a Basic Education school that adopted the Project One Computer per Student (OCS) in their school routine. Its relevance consists in provide directions for the continuation of training activities on the Project and guide the teachers with their pedagogical practices using the laptop model one to one. The thesis defended is that the educator formation for social using of digital media (specially the laptops from the Project UCA) gives space to establish new sociotechnical relationships, of new social and professionals practices, new identitary components and a process of reflexivity and knowledge reconstruction to teach. We reaffirm the importance of reflexivity and appropriation of digital culture for the better development of teaching practice using the Information and Communication Technologies (ICTs), giving focus to the aspects of social and professional use of the technology. The study is part of the qualitative aspect and is a procedural tracking based on principles of ethnographic research. As procedures and methodological tools, were used: intensive observation of school environments, documental analysis, focal group, semi-structured questionnaires and semi-structured individual interviews. The research was held in a public school in the city of Parnamirim - RN. The subject sample relates to 17 teachers, coming from the elementary school I and II, Youth and Adult Education and High School, who went through the process of training UCA and having entered the laptops in their teaching. The research corpus is structured based on the messages built into the process of data collection and is analyzed based on principles of Content Analysis, specified by Laurence Bardin (2011). Was taken as theoretical reference studies by Tardif (2000; 2011), Pimenta (2009), Gorz (2004, 2005), Giddens (1991), Dewey, J. (1916), Boudieu (1994; 1999), Freire (1996; 2005), among others. The analysis indicates a process of reconstruction / revision of knowledge to teach and work in digital culture, being these knowledges guided by the experience of the subjects investigated. The reconstructed knowledges will be revealed from a categorization process. The following groups of knowledges: "technical knowledges", "didactic-methodological knowledges and knowledges of professionalization" were built on the assumption of ownership of digital culture in the educational context. The analysis confirms the appearance of new ways of sociability when acquiring other forms of acting and thinking ICTs, despite the environment adverse to the reflexivity shared among the teachers. Also reveals, based on the ownership concept present on the data analysis, the construction of meanings of belonging and transformation of individuals into social routes from the interweaving of the teaching practice with the digital culture. Emphasizes, finally, the importance of a training for use of ICTs that exceeds the instrumentation, in other words, what we call "technical knowledges", but taking on its structural basis the shared reflection, the opening for the ressignificance (new meaning) and reconstruction of new knowledges and practices and that really allows, to the teacher, the living of an experience capable of providing socio-technical transformations of their relationships

Multiplicando veredas entre guimarães rosa e oswaldo lamartine

Universidade Federal do Rio Grande do Norte

Determinacão do período orbital de sistemas binários clipsantes

In this work is presented a new method for the determination of the orbital period (Porb) of eclipsing binary systems based on the wavelet technique. This method is applied on 18 eclipsing binary systems detected by the CoRoT (Convection Rotation and planetary transits) satellite. The periods obtained by wavelet were compared with those obtained by the conventional methods: box Fitting (EEBLS) for detached and semi-detached eclipsing binaries; and polynomial methods (ANOVA) for contact binary systems. Comparing the phase diagrams obtained by the different techniques the wavelet method determine better Porb compared with EEBLS. In the case of contact binary systems the wavelet method shows most of the times better results than the ANOVA method but when the number of data per orbital cicle is small ANOVA gives more accurate results. Thus, the wavelet technique seems to be a great tool for the analysis of data with the quality and precision given by CoRoT and the incoming photometric missions.

Análise sísmica usando transformada de Curvelet

Oil prospecting is one of most complex and important features of oil industry Direct prospecting methods like drilling well logs are very expensive, in consequence indirect methods are preferred. Among the indirect prospecting techniques the seismic imaging is a relevant method. Seismic method is based on artificial seismic waves that are generated, go through the geologic medium suffering diffraction and reflexion and return to the surface where they are recorded and analyzed to construct seismograms. However, the seismogram contains not only actual geologic information, but also noise, and one of the main components of the noise is the ground roll. Noise attenuation is essential for a good geologic interpretation of the seismogram. It is common to study seismograms by using time-frequency transformations that map the seismic signal into a frequency space where it is easier to remove or attenuate noise. After that, data is reconstructed in the original space in such a way that geologic structures are shown in more detail. In addition, the curvelet transform is a new and effective spectral transformation that have been used in the analysis of complex data. In this work, we employ the curvelet transform to represent geologic data using basis functions that are directional in space. This particular basis can represent more effectively two dimensional objects with contours and lines. The curvelet analysis maps real space into frequencies scales and angular sectors in such way that we can distinguish in detail the sub-spaces where is the noise and remove the coefficients corresponding to the undesired data. In this work we develop and apply the denoising analysis to remove the ground roll of seismograms. We apply this technique to a artificial seismogram and to a real one. In both cases we obtain a good noise attenuation

The influence of visual inter-hemispheric connections on spiking, assembly and LFP activities, and their phase relationship during figure-ground stimulation

Desde os descobrimentos pioneiros de Hubel e Wiesel acumulou-se uma vasta literatura descrevendo as respostas neuronais do córtex visual primário (V1) a diferentes estímulos visuais. Estes estímulos consistem principalmente em barras em movimento, pontos ou grades, que são úteis para explorar as respostas dentro do campo receptivo clássico (CRF do inglês classical receptive field) a características básicas dos estímulos visuais como a orientação, direção de movimento, contraste, entre outras. Entretanto, nas últimas duas décadas, tornou-se cada vez mais evidente que a atividade de neurônios em V1 pode ser modulada por estímulos fora do CRF. Desta forma, áreas visuais primárias poderiam estar envolvidas em funções visuais mais complexas como, por exemplo, a separação de um objeto ou figura do seu fundo (segregação figura-fundo) e assume-se que as conexões intrínsecas de longo alcance em V1, assim como as conexões de áreas visuais superiores, estão ativamente envolvidas neste processo. Sua possível função foi inferida a partir da análise das variações das respostas induzidas por um estímulo localizado fora do CRF de neurônios individuais. Mesmo sendo muito provável que estas conexões tenham também um impacto tanto na atividade conjunta de neurônios envolvidos no processamento da figura quanto no potencial de campo, estas questões permanecem pouco estudadas. Visando examinar a modulação do contexto visual nessas atividades, coletamos potenciais de ação e potenciais de campo em paralelo de até 48 eletrodos implantados na área visual primária de gatos anestesiados. Estimulamos com grades compostas e cenas naturais, focando-nos na atividade de neurônios cujo CRF estava situado na figura. Da mesma forma, visando examinar a influência das conexões laterais, o sinal proveniente da área visual isotópica e contralateral foi removido através da desativação reversível por resfriamento. Fizemos isso devido a: i) as conexões laterais intrínsecas não podem ser facilmente manipuladas sem afetar diretamente os sinais que estão sendo medidos, ii) as conexões inter-hemisféricas compartilham as principais características anatômicas com a rede lateral intrínseca e podem ser vistas como uma continuação funcional das mesmas entre os dois hemisférios e iii) o resfriamento desativa as conexões de forma causal e reversível, silenciando temporariamente seu sinal, permitindo conclusões diretas a respeito da sua contribuição. Nossos resultados demonstram que o mecanismo de segmentação figurafundo se reflete nas taxas de disparo de neurônios individuais, assim como na potência do potencial de campo e na relação entre sua fase e os padrões de disparo produzidos pela população. Além disso, as conexões laterais inter-hemisféricas modulam estas variáveis dependendo da estimulação feita fora do CRF. Observamos também uma influência deste circuito lateral na coerência entre potenciais de campo entre eletrodos distantes. Em conclusão, nossos resultados dão suporte à ideia de um mecanismo complexo de segmentação figura-fundo atuando desde as áreas visuais primárias em diferentes escalas de frequência. Esse mecanismo parece envolver grupos de neurônios ativos sincronicamente e dependentes da fase do potencial de campo. Nossos resultados também são compatíveis com a hipótese que conexões laterais de longo alcance também fazem parte deste mecanismo

Triagem antifúngica de extratos obtidos de espécies vegetais do nordeste brasileiro

The increase in the incidence of fungal infections due to the drug-resistance or to the number of patients with immune alterations such as AIDS, chemotherapy or organ transplantation, has done the research necesseray for new antifungal drugs. The species from Northeastern Brazil may become an important source of innovative natural molecules. To evaluate the antifungal activity of 10 medicinal plants from Northeastern Brazil, traditionally used as antimicrobial agents, 30 crude extracts (CE) were tested in vitro against four standard species of Candida spp. The CE most promising of these plants were evaluated against yeasts of the oral cavity of kidney transplant patients and through a bioassay-guided fractionation. The extracts form leaves of E. uniflora, the stem bark of L. ferrea and leaves of P. guajava showed significant activity against all yeasts evaluated, with MIC values between 15.62 and 62.5 μg/mL. E. uniflora also showed fungicidal properties against all yeasts, especially against Candida dubliniensis. In patients with immune systems compromised, such as transplanted, oral candidiasis manifests mainly due to immunosuppressive therapy, and resistance to conventional antifungals. The CE of E. uniflora presented range of MIC values between 1.95 to 1000 μg/mL, and lower MIC50 and MIC90 values were observed against C. non-albicans. Due the better results, the CE of E. uniflora was elected to performe the bioassay-guided fractionation. Thus it was possible to obtain enriched fractions, which showed good inhibitory ability against ATCC strains of Candida spp. It was also possible to perform experiments to verify the production of biofilm in two strains of C. dubliniensis and action of extracts and fractions on the same. With this, we observed a behavior between the yeast ATCC and clinical isolate. In addition, CE, fractions and subfractions of E. uniflora inhibit planktonic cells to preventing the growth of biofilm. The preliminary chemical characterization of the fractions obtained revealed the presence of polyphenols (especially flavonoids and tannins). Finally, the results suggests that among the plant species studied, E. uniflora showed a pattern very promising as regards the antifungal, requiring further study of purification and structural elucidation of compounds in order to verify that the antifungal effect found can be attributed to a specific compound or some mechanism depends on synergistic the mixture of polyphenols

Arcabouço geofísico, isostasia e causas do magmatismo cenozóico da província Borborema e de sua margem continental (Nordeste do Brasil)

The Borborema Province (BP) is a geologic domain located in Northeastern Brazil. The BP is limited at the south by the São Francisco craton, at the west by the Parnaíba basin, and both at the north and east by coastal sedimentary basins. Nonetheless the BP surface geology is well known, several key aspects of its evolution are still open, notably: i)its tectonic compartmentalization established after the Brasiliano orogenesis, ii) the architecture of its cretaceous continental margin, iii) the elastic properties of its lithosphere, and iv) the causes of magmatism and uplifting which occurred in the Cenozoic. In this thesis, a regional coverage of geophysical data (elevation, gravity, magnetic, geoid height, and surface wave global tomography) were integrated with surface geologic information aiming to attain a better understanding of the above questions. In the Riacho do Pontal belt and in the western sector of the Sergipano belt, the neoproterozoic suture of the collision of the Sul domain of the BP with the Sanfranciscana plate (SFP) is correlated with an expressive dipolar gravity anomaly. The positive lobule of this anomaly is due to the BP lower continental crust uplifting whilst the negative lobule is due to the supracrustal nappes overthrusting the SFP. In the eastern sector of the Sergipano belt, this dipolar gravity anomaly does not exist. However the suture still can be identified at the southern sector of the Marancó complex arc, alongside of the Porto da Folha shear zone, where the SFP N-S geophysical alignments are truncated. The boundary associated to the collision of the Ceará domain of the BP with the West African craton is also correlated with a dipolar gravity anomaly. The positive lobule of this anomaly coincides with the Sobral-Pedro II shear zone whilst the negative lobule is associated with the Santa Quitéria magmatic arc. Judging by their geophysical signatures, the major BP internal boundaries are: i)the western sector of the Pernambuco shear zone and the eastern continuation of this shear zone as the Congo shear zone, ii) the Patos shear zone, and iii) the Jaguaribe shear zone and its southwestern continuation as the Tatajuba shear zone. These boundaries divide the BP in five tectonic domains in the geophysical criteria: Sul, Transversal, Rio Grande do Norte, Ceará, and Médio Coreaú. The Sul domain is characterized by geophysical signatures associated with the BP and SFP collision. The fact that Congo shear zone is now proposed as part of the Transversal domain boundary implies an important change in the original definition of this domain. The Rio Grande do Norte domain presents a highly magnetized crust resulted from the superposition of precambrian and phanerozoic events. The Ceará domain is divided by the Senador Pompeu shear zone in two subdomains: the eastern one corresponds to the Orós-Jaguaribe belt and the western one to the Ceará-Central subdomain. The latter subdomain exhibits a positive ENE-W SW gravity anomaly which was associated to a crustal discontinuity. This discontinuity would have acted as a rampart against to the N-S Brasiliano orogenic nappes. The Médio Coreaú domain also presents a dipolar gravity anomaly. Its positive lobule is due to granulitic rocks whereas the negative one is caused by supracrustal rocks. The boundary between Médio Coreaú and Ceará domains can be traced below the Parnaíba basin sediments by its geophysical signature. The joint analysis of free air anomalies, free air admittances, and effective elastic thickness estimates (Te) revealed that the Brazilian East and Equatorial continental margins have quite different elastic properties. In the first one 10 km < Te < 20 km whereas in the second one Te ≤ 10 km. The weakness of the Equatorial margin lithosphere was caused by the cenozoic magmatism. The BP continental margin presents segmentations; some of them have inheritance from precambrian structures and domains. The segmentations conform markedly with some sedimentary basin features which are below described from south to north. The limit between Sergipe and Alagoas subbasins coincides with the suture between BP and SFP. Te estimates indicates concordantly that in Sergipe subbasin Te is around 20 km while Alagoas subbasin has Te around 10 km, thus revealing that the lithosphere in the Sergipe subbasin has a greater rigidity than the lithosphere in the Alagoas subbasin. Additionally inside the crust beneath Sergipe subbasin occurs a very dense body (underplating or crustal heritage?) which is not present in the crust beneath Alagoas subbasin. The continental margin of the Pernambuco basin (15 < Te < 25 km) presents a very distinct free air edge effect displaying two anomalies. This fact indicates the existence in the Pernambuco plateau of a relatively thick crust. In the Paraíba basin the free air edge effect is quite uniform, Te ≈ 15 km, and the lower crust is abnormally dense probably due to its alteration by a magmatic underplating in the Cenozoic. The Potiguar basin segmentation in three parts was corroborated by the Te estimates: in the Potiguar rift Te ≅ 5 km, in the Aracati platform Te ≅ 25 km, and in the Touros platform Te ≅ 10 km. The observed weakness of the lithosphere in the Potiguar rift segment is due to the high heat flux while the relatively high strength of the lithosphere in the Touros platform may be due to the existence of an archaean crust. The Ceará basin, in the region of Mundaú and Icaraí subbasins, presents a quite uniform free air edge effect and Te ranges from 10 to 15 km. The analysis of the Bouguer admittance revealed that isostasy in BP can be explained with an isostatic model where combined surface and buried loadings are present. The estimated ratio of the buried loading relative to the surface loading is equal to 15. In addition, the lower crust in BP is abnormally dense. These affirmations are particularly adequate to the northern portion of BP where adherence of the observed data to the isostatic model is quite good. Using the same above described isostatic model to calculate the coherence function, it was obtained that a single Te estimate for the entire BP must be lower than 60 km; in addition, the BP north portion has Te around 20 km. Using the conventional elastic flexural model to isostasy, an inversion of crust thickness was performed. It was identified two regions in BP where the crust is thickened: one below the Borborema plateau (associated to an uplifting in the Cenozoic) and the other one in the Ceará domain beneath the Santa Quitéria magmatic arc (a residue associated to the Brasiliano orogenesis). On the other hand, along the Cariri-Potiguar trend, the crust is thinned due to an aborted rifting in the Cretaceous. Based on the interpretation of free air anomalies, it was inferred the existence of a large magmatism in the oceanic crust surrounding the BP, in contrast with the incipient magmatism in the continent as shown by surface geology. In BP a quite important positive geoid anomaly exists. This anomaly is spatially correlated with the Borborema plateau and the Macaú-Queimadas volcanic lineament. The integrated interpretation of geoid height anomaly data, global shear velocity model, and geologic data allow to propose that and Edge Driven Convection (EDC) may have caused the Cenozoic magmatism. The EDC is an instability that presumably occurs at the boundary between thick stable lithosphere and oceanic thin lithosphere. In the BP lithosphere, the EDC mechanism would have dragged the cold lithospheric mantle into the hot asthenospheric mantle thus causing a positive density contrast that would have generated the main component of the geoid height anomaly. In addition, the compatibility of the gravity data with the isostatic model, where combined surface and buried loadings are present, together with the temporal correlation between the Cenozoic magmatism and the Borborema plateau uplifting allow to propose that this uplifting would have been caused by the buoyancy effect of a crustal root generated by a magmatic underplating in the Cenozoic

Caracterização tectono-estratigráfica da sequência transicional na sub-bacia de Sergipe

This thesis deals with the tectonic-stratigraphic evolution of the Transitional Sequence in the Sergipe Sub-basin (the southern segment of the Sergipe-Alagoas Basin, Northeast Brazil), deposited in the time interval of the upper Alagoas/Aptian stage. Sequence boundaries and higher order internal sequences were identified, as well as the structures that affect or control its deposition. This integrated approach aimed to characterize the geodynamic setting and processes active during deposition of the Transitional Sequence, and its relations with the evolutionary tectonic stages recognized in the East Brazilian Margin basins. This subject addresses more general questions discussed in the literature, regarding the evolution from the Rift to the Drift stages, the expression and significance of the breakup unconformity, the relationships between sedimentation and tectonics at extensional settings, as well as the control on subsidence processes during this time interval. The tectonic-stratigraphic analysis of the Transitional Sequence was based on seismic sections and well logs, distributed along the Sergipe Sub-basin (SBSE). Geoseismic sections and seismic facies analysis, stratigraphic profiles and sections, were compiled through the main structural blocks of this sub-basin. These products support the depositional and tectonic-stratigraphic evolutionary models built for this sequence. The structural analysis highlighted similarities in deformation styles and kinematics during deposition of the Rift and Transitional sequences, pointing to continuing lithospheric extensional processes along a NW trend (X strain axis) until the end of deposition of the latter sequence was finished by the end of late Aptian. The late stage of extension/rifting was marked by (i) continuous (or as pulses) fault activity along the basin, controling subsidence and creation of depositional space, thereby characterizing upper crustal thinning and (ii) sagstyle deposition of the Transitional Sequence at a larger scale, reflecting the ductile stretching and thinnning of lower and sub crustal layers combined with an increasing importance of the thermal subsidence regime. Besides the late increments of rift tectonics, the Transitional Sequence is also affected by reactivation of the border faults of SBSE, during and after deposition of the Riachuelo Formation (lower section of the Transgressive Marine Sequence, of Albian age). It is possible that this reactivation reflects (through stress propagation along the newlycreated continental margin) the rifting processes still active further north, between the Alagoas Sub-basin and the Pernambuco-Paraíba Basin. The evaporitic beds of the Transitional Sequence contributed to the development of post-rift structures related to halokinesis and the continental margin collapse, affecting strata of the overlying marine sequences during the Middle Albian to the Maastrichtian, or even the Paleogene time interval. The stratigraphic analysis evidenced 5 depositional sequences of higher order, whose vertical succession indicates an upward increase of the base level, marked by deposition of continental siliciclastic systems overlain by lagunar-evaporitic and restricted marine systems, indicating that the Transitional Sequence was deposited during relative increase of the eustatic sea level. At a 2nd order cycle, the Transitional Sequence may represent the initial deposition of a Transgressive Systems Tract, whose passage to a Marine Transgressive Sequence would also be marked by the drowning of the depositional systems. At a 3rd order cycle, the sequence boundary corresponds to a local unconformity that laterally grades to a widespread correlative conformity. This boundary surface corresponds to a breakup unconformity , being equivalent to the Pre-Albian Unconformity at the SBSE and contrasting with the outstanding Pre-upper Alagoas Unconformity at the base of the Transitional Sequence; the latter is alternatively referred, in the literature, as the breakup unconformity. This Thesis supports the Pre-Albian Unconformity as marker of a major change in the (Rift-Drift) depositional and tectonic setting at SBSE, with equivalent but also diachronous boundary surfaces in other basins of the Atlantic margin. The Pre-upper Alagoas Unconformity developed due to astenosphere uplift (heating under high lithospheric extension rates) and post-dates the last major fault pulse and subsequent extensive block erosion. Later on, the number and net slip of active faults significantly decrease. At deep to ultra deep water basin segments, seaward-dipping reflectors (SDRs) are unconformably overlain by the seismic horizons correlated to the Transitional Sequence. The SDRs volcanic rocks overly (at least in part) continental crust and are tentatively ascribed to melting by adiabatic decompression of the rising astenospheric mantle. Even though being a major feature of SBSE (and possibly of other basins), the Pre-upper Alagoas Unconformity do not correspond to the end of lithospheric extension processes and beginning of seafloor spreading, as shown by the crustal-scale extensional structures that post-date the Transitional Sequence. Based on this whole context, deposition of the Transitional Sequence is better placed at a late interval of the Rift Stage, with the advance of an epicontinental sea over a crustal segment still undergoing extension. Along this segment, sedimentation was controled by a combination of thermal and mechanical subsidence. In continuation, the creation of oceanic lithosphere led to a decline in the mechanical subsidence component, extension was transferred to the mesoceanic ridge and the newly-formed continental margin (and the corresponding Marine Sequence) began to be controlled exclusively by the thermal subsidence component. Classical concepts, multidisciplinary data and new architectural and evolutionary crustal models can be reconciled and better understood under these lines

Superparamagnetismo em Jacobsitas sintéticas

In this experimental study sintetic samples of Jacobsites (MnFe2O4) were synthesized by the Pechini method and calcined within ambient atmosphere and afterwards in the vacuum from 400 to 700ºC, the range of calcination temperatures. The X-Ray Diffraction (XRD) and the Scanning Electronic Microscopy (SEM) analysis have shown that the samples treated at 400ºC temperature are composed by a simple type of spinel phase, with a crystallite size of 8:8nm for the sample calcined in ambient atmosphere and 20; 1nm for the sample treated in the vacuum, showing that the cristallite average size can be manipulated by the atmosphere control. The hysteresis loops for the sample calcined at 400ºC in ambient atmosphere reveal features of superparamagnetic behavior with magnetization 29:3emu=g at the maximum field of 1:2T. The sample calcined in 400oC under vacuum show magnetization = 67emu=g at the maximum field of 1:5T. The sample treated at 500oC, under ambient atmosphere, has shown besides the spinel phase, secondary phases of hematite (Fe2O3) and bixbyite (FeMnO3). The hysteresis loops demonstrate a sharp drop of the magnetization compared to the previous sample. The analysis has revealed that for the samples treated in higher temperatures (600ºC and 700ºC) its observed the absence of the spinel phase and the maintenance of the bixbyite and hematite. The hysteresis loops for those samples in accordance to the external magnetic field are straight lines crossing the origin, consistent with the antiferromagnetic behavior of the phases.The Mössbauer espectroscopy show to the sample calcined at 400ºC within ambiente atmosphere two sextet and one doublet. The two sextets are assigned to the hyperfine fields related to the magnetic deployment in the nuclei of Fe3+ ions, at the tetraedric and octaedric sites. The doublet is assigned to superparamagnetic behavior of the particles with smaller diameter than dc . Now the sample calcined at 400ºC under vacuum only show two sextet