Sobre a composição química em estrelas evoluídas do aglomerado aberto M67

The Galaxy open clusters have a wide variety of physical properties that make them valuable laboratories for studies of stellar and chemical evolution of the Galaxy. In order to better settle these properties we investigate the abundances of a large number of chemical elements in a sample of 27 evolved stars of the open cluster M67 with different evolutionary stages (turn-off, subgiant and giant stars). For such a study we used high-resolution spectra (R 47 000) and high S/N obtained with UVES+FLAMES at VLT/UT2, covering the wavelength interval 4200-10 600 Å. Our spectral analysis is based on the MARCS models of atmosphere and Turbospectrum spectroscopic tool. The oxygen abundances were determined from the [O I] line at 6300 Å. In addition, we have also computed abundances of Si I, Na I, Mg I, Al I, Ca I, Ti I, Co I, Ni I, Zr I, La II and Cr I. The abundances investigated in this work, combined with their stellar parameters, offers an opportunity to determine the level of mixing and convective dilution of evolved stars in M67. Based on the obtained parameters, the abundances of these seem to follow a similar trend to the curve of solar abundances. Additionally, following strategies of other studies have investigated the relative abundances as a function of effective temperature and metallicity, where it was possible to observe an abundance of Na, Al and Si to the stars in the field of giants. A large dispersion from star to star, is observed in the ratios [X / Fe] for the Co, Zr and La, and the absence of Zr and La, in the stars of the turn-off. Comparisons made between our results and other studies in the literature show that values of abundances are in agreement and close to the limits of the errors

Estimativa de expoentes críticos em Percolação

In Percolation Theory, functions like the probability that a given site belongs to the infinite cluster, average size of clusters, etc. are described through power laws and critical exponents. This dissertation uses a method called Finite Size Scaling to provide a estimative of those exponents. The dissertation is divided in four parts. The first one briefly presents the main results for Site Percolation Theory for d = 2 dimension. Besides, some important quantities for the determination of the critical exponents and for the phase transistions understanding are defined. The second shows an introduction to the fractal concept, dimension and classification. Concluded the base of our study, in the third part the Scale Theory is mentioned, wich relates critical exponents and the quantities described in Chapter 2. In the last part, through the Finite Size Scaling method, we determine the critical exponents fi and. Based on them, we used the previous Chapter scale relations in order to determine the remaining critical exponents

Síntese, sinterização e caracterização de ferrita de níquel

In this work we obtain nickel ferrite by the combustion synthesis method whcih involves synthesising in an oven at temperatures of 750oC, 950oC and 125oC. The precursors oxidizing used were nickel nitrate, ferric as an oxidizing and reducing urea (fuel). After obtaining the mixture, the product was deagglomerated and past through a 270 mesh sieve. To assess the structure, morphology, particle size, magnetic and electrical properties of nanoparticles obtained the samples were sintered and characterized by x-ray distraction (XRD), x-ray fluorescence spectroscopy (FRX); scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), vibrating sample magnetometer (MAV ) and electrical permittivity. The results indicated the majority of phase inverse spinel ferrite and Hematite secondary phase nickel and nickel oxide. Through the intensity of the distraction, the average size of the crystallization peaks were half-height width which was calculated using the Scherrer equation. From observing the peaks of all the reflections, it appears that samples are crystal clear with the formation of nanoparticles. Morphologically, the nanoferritas sintered nickel pellet formation was observed with three systems of particle size below 100mn, which favored the formation of soft pellets. The average size of the grains in their micrometric scale. FRX and EDS showed qualitatively the presence of iron elements nickel and oxygen, where through quantitative data we can observe the presence of the secondary phase. The magnetic properties and the saturation magnetization and the coercive field are in accordance with the nickel, ferrite where the curve of hysteresis has aspects of a soft material. Dielectric constant values are below 10 and low tangent loss

Mapeamento da zona costeria protegida por arenitos de praia (Beachrocks) em Nísia Floresta - RN

The goal of this work comprises the detailed mapping of the coastal zone of the south coast of the State of Rio Grande do Norte. The emphasis of the study is the units of beachrocks and the features of the physical environment associated. The mapping of the beachrocks and of the adjacent coastal features is justified, among other aspects, by the fact that the beachrocks constitute an important protection agent against the sea erosion. By one side, they dissipate the energy of the sea waves and make possible the imprisonment of sediments in the foreshore. The beachrocks in the studied area are constituted of discontinuous strips, parallel to the coast line presenting emerged in some places, even in the highest tides, entirely submerged or partially buried by coastal sediments. These sandstones compose the landscape of big part of the coast and they are responsible for the partial dissipation of the energy of the waves on the studied coast. The methodology used in this work consisted of different techniques were used, as the use of aerial pictures of small format (FAPEFs), acquisition of data of system of global positioning (GPS) and later elaboration of thematic maps and of digital models of soil (MDTs). The results obtained in the mapping of the use and occupation of the soil, demonstrate the existence of strong human pressure in the coastal area (built lots and no built), occupying about 54,74% of built areas. This problem has been taking to degradation risks due to the inconsequent expansion of divisions into lots and tourist enterprises. The MDT came as an excellent resource, as visual as functional, being possible to visualize several angles and to act in three dimensions the relief of the area in study, as well as to identify the present features in the coastal area. By the importance of the bodies of beachrocks as a protection agent against the coastal erosion, faces were delimited in the sandstones based in geometric criteria, classifying them in, central face, outside face, inside face, break and undermiming. These last two associates to the erosion and washout in the base of these bodies. Field data indicate clearly that the most important process in the fracturing of the bodies is associated with mechanisms related to the gravity, being the joints formed by processes of gravitational sliding. Finally, the mapping of the coastal zone starting from aerial pictures of small format it made possible the identification of the elements that compose the beach strip, for accomplishing with larger detailed level and by presenting a better monitoring of the dynamics of the coastal zone

O processo de urbanização turística em Natal: a perspectiva do residente

The objective of the study was to analyze and discuss the process of urbanization in the tourist city of Natal focusing on the actions of the resident agent as a producer of space tourism. The production and expertise in the areas of the city for the performance of tourism have led to the intensification of social problems of nature that comes to few expelling the residents of the beaches. The cut space of the study included the four beaches of Natal / RN, the praias do Centro, Via Costeira, Ponta Negra beach in the Redinha. For this, was conducted a case study, using the technique of questioning, with the application of one hundred and sixteen (116) questionnaires to residents, with age from thirty-five years, between the four of the City Administrative Regions. The results show that the process of urbanization has interferido tourism on the practices of the recreation of residents in the areas as tourism has shown a trend seen in the intensifying problems of social order, such as prostitution, insecurity, pollution of beaches, etc. The combination of these problems are reflected negatively on the tourist areas and are gradually removing the residents. Through this framework problematic, given to tourist areas in the city, the resident still has not positioned the way criticizes the defense of these, choosing not express or adopting a form of discrete event, such as the gradual exit of the areas and electing tourist beaches in other municipalities. The results are of great significance for the direction of a trip planning committed with the participation of the resident in the planning process. The study is to corroborate with the importance of the participation of the resident, before the trip planning, as it is a fundamental agent for the sustainability of space tourism

Geografia, turismo e meio ambiente: uma nova face do litoral dos municípios de Extremoz e Ceará-Mirim

La presente pesquisa contempla reflexiones referentes de la actividad turística en la organización socio-espacial en el litoral de las comarcas de Extremoz y Ceará-Mirim, región de la Grande Natal. Nuestro objetivo principal es el estudio de las transformaciones del espacio y de sus implicaciones socio-ambientales en curso en el proceso de producción del espacio turístico en el litoral de las referidas comarcas desde 1997 hasta 2007, momento de importancia publica-privada que, a partir del PRODETUR, tuvo la base para el incremento de las potencialidades turísticas. En este sentido, varias fueron las técnicas para una mejor compresión de las aspiraciones y de la percepción de los actores envueltos con la actividad turística (comerciantes, turistas, populación y poder publico local) para conocer cuales son sus consideraciones en cuanto a los cambios que proceden de la implantación de la actividad turística en el lugar, cuanto a la mejora de la calidad de vida, de la generación de empleo y de renta, comercialización, conservación, preservación del ambiente, cumplimiento de la legislación, afirmación cultural así como las acciones puestas en ejecución en las comarcas. Para tal necesidad, se buscó analizar los datos estadísticos a partir del uso de los cuestionarios con preguntas estructuradas y semi-abiertas como instrumento de colecta de información que les era correlacionada con la opinión de los actores locales de modo que podamos formar y entender los elementos básicos que son parte de los espacios turísticos en foco. Fueran utilizadas fotografías aéreas de las comarcas de Extremoz y Ceará-Mirim, provistas por el IDEMA, con la intención de percibir acerca de los cambios del espacio y las implicaciones socio-ambientales de la área en estudio. Concluimos en función de los resultados que el modelo de Turismo concebido por lo Brasil, estimulado y financiado por lo Gobierno Federal, está insertado en el contexto de la economía global y, por lo tanto, el Estado del Rio Grande del Norte, en específico los espacios litoraneos de las comarcas de Extremoz y Ceará-Mirim, que poseen características similares a este modelo, con sus particularidades, que si traduzca por la exclusión social, formas de apropiación privada de los espacios público y áreas de protección ambiental como las playas, las dunas y las lagunas, el desacato o no el cumplimiento de la legislación ambiental, aumento de las desigualdad de renta en una región que posee una problemática social grave y sin inversión, implantación de la infraestructura, ausencia de política pública local, donde los intereses económicos son prioridad delante de las aclamaciones populares. Se sugiere un repensar cuanto al modelo actual de desarrollo adoptado, que el planeamiento sea pautado en base a la participación integrada de los varios agentes implicados con la actividad turística, incluyendo en la medida del posible, las aspiraciones de la población local como precusoras de sus reales necesidades, donde esta acción interactiva contestará ciertamente en un esfuerzo significativo en la construcción de un nuevo paradigma, modelo del desarrollo sustentable, siendo posible superar gradualmente el incremento de la pobreza, de la exclusión y de los impactos ambientales, donde la calidad de vida sea factor fundamental

As transformações fundiárias da comunidade de sibaúma-rn com o advento do turismo

The genesis of the research emerges from reflection about the space dynamics of the capital and to the capital. The expansion and the incorporation of territory for capital reveal, in part, strategies of the capitalism production way, which shows the search for accumulation conditions, expanding the alternatives of territory use that is, nowadays, selective and uneven. The present work verified the mechanisms where the capital imposes its practices through the agrarian structure and the valuation of land market, meaning, in our knowledge, that the reproduction of inequalities is showed, many times, by the wide land speculation and the fast land valuation. For this, the snip space will be the Sibaúma community, belonging to Tibau do Sul district, located in Rio Grande do Norte state. It‟s a rural area that has, gradually, changing through the advent of urban characteristics, given the association of public and private investments, both domestic and international. Through the empirical observations, inside the Sibaúma community, it was found expansion strategies, incorporation and appropriation of territory by capital. As a result of this practice, it‟s occurring the land valuation and the presence of a process of socio-spatial segregation, through the encouraging the opening of new subdivisions, mainly for construction of second homes and tourism enterprises in order to meet the demand of a higher socioeconomic level. The areas still available in Sibaúma, constitute into a reserve of value for the achievement of capitalist rent, being a mechanism of capital reproduction. In this way, to studying the socio-spatial transformations, caused by spatial valuation, we turn to the project of social space designed by Santos(2006), from the perspective of capitalist production of space, by understanding the historical process of formation, the mechanisms and the actions of social actors that produce and consume space

Ilha de Santana e Alto de Santa Rita: a produção do espaço a partir do turismo em Caicó e Santa Cruz - RN

Tourism is an activity that uses the spatial objects and also produces and because it creates an economic activity areas for leisure. So for this to occur itdoes need a space reorganized, with infrastructure to receive visitors. And in the process of construction / reconstruction of tourist destination the state comes as a precursor, creating public policies that tourism can develop. Thus, this paper examines the transformation process by which the spaces are aiming to become tourist, and what changes occur in socio-spatial dynamic of the city in which this activity is inserted. The spatial area of study refers to the Alto de Santa Rita, Santa Cruz and the Isla de Santana Tourist Complex in Caicó both in Rio Grande do Norte. The reconstruction of the Island de Santana did not occur randomly, in order that the spatial changes were performed to meet the demand for which Caicó had to perform his greatest social and religious event, the Feast of Santana, which occurs since its colonization in year 1748 and also the Carnival these two events being considered as a strong tourist attraction of the city. And the Santa Rita High was built in order to enter the city of Santa Cruz in the script of religious tourism of the state through the devotion of the patron. The Dissertation isstructured in five parts, the first refers to the introduction of the work, while the second examines how tourism wound to the Rio Grande do Norte and internalizesthe third part deals with the spaces for tourism in these cities, the the fourthidentifies as the symbolism of these spaces influence the transformation and the latter reveals how these spaces affect the socio-economic structure of cities across the events

Síntese e caracterização estrutural, magnética e térmica da hidroxiapatita dopada com ferro

In this work, composites were prepared using high energy mechanical milling from the precursors hydroxyapatite - HAp (Ca10(PO4)6(OH)2) and metallic iron ( -Fe ). The main goal here is to study composites in order to employ them in magnetic hyperthermia for cancer therapy. The produced samples were characterized by X-ray di raction (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), magnetization curves as a function of applied eld (MxH), and nally measurements of magnetic hyperthermia. The XRD patterns of the milled samples HAp/Fe revealed only the presence of precursor materials. The SEM showed clusters with irregular shapes. The magnetization curves indicated typical cases of weak ferromagnetic behavior. For samples submitted to grinding and annealing, the identi ed phases were: HAp (Ca10(PO4)6(OH)2), hematite (Fe2O3) and Calcium Iron Phosphate (Ca9Fe(PO4)7). Analyzing the results of MxH, there was a reduction of the saturation magnetization, given that the Fe was incorporated into HAp. Hysteresis curves obtained at 300 K are characteristics of samples possessing over a phase. At 77 K, the behavior of the hysteresis curve is in uenced by the presence of hematite, which is antiferromagnetic. Already at T = 4.2 K, it is observed a weak ferromagnetic behavior. Furthermore, there is the e ect of exchange bias. Regarding the magnetic hyperthermia, the results of temperature measurements as a function of the alternating eld are promising for applications in magnetic hyperthermia and other biomedical applications.

Obtenção e caracterização de complexos polieletrolíticos de quitosana e poli (metacrilato de sódio)

Polyelectrolyte complexes (PECs) nanoparticles were prepared using chitosan and sodium polymethacrylate. The complex formation was investigated using turbidimetry, conductometry, viscometry, and dynamic light scattering. The presence of excess positive charges was evidenced by zeta potential measurements. The particle diameter was characterized by dynamic light scattering and the morphology by atomic force microscopy. In all experiments an abrupt change in behavior was observed at a carboxyl:amino molar ratio around 0.7−0.8. Those changes in behavior were related to a proposed mechanism of complex formation based on the decrease of macromolecular dimensions of soluble polyelectrolyte complex clusters, followed by phase segregation

Contribuições de modelagem de equações estruturais na análise de dados em modelos comportamentais de destino turístico

A fragilidade brasileira quanto à competitividade turística é um fato observável nos dados da Organização Mundial do Turismo. O Brasil caiu em 2011, da 45ª para a 52ª posição, apesar de liderar no atributo recursos naturais e estar colocado na 23° em recursos culturais. Assim, grandes interesses e esforços têm sido direcionados para o estudo da competitividade dos produtos e destinos turísticos. O destino turístico é caracterizado por um conjunto complexo e articulado de fatores tangíveis e intangíveis, apresentando alta complexidade, dados de elevada dimensionalidade, não linearidade e comportamento dinâmico, tornando-se difícil a modelagem desses processos por meio de abordagens baseadas em técnicas estatísticas clássicas. Esta tese investigou modelos de equações estruturais e seus algoritmos, aplicados nesta área, analisando o ciclo completo de análise de dados, em um processo confirmatório no desenvolvimento e avaliação de um modelo holístico da satisfação do turista; na validação da estrutura do modelo de medida e do modelo estrutural, por meio de testes de invariância de múltiplos grupos; na análise comparativa dos métodos de estimação MLE, GLS e ULS para a modelagem da satisfação e na realização de segmentação de mercado no setor de destino turístico utilizando mapas auto-organizáveis de Kohonen e sua validação com modelagem de equações estruturais. Aplicações foram feitas em análises de dados no setor de turismo, principal indústria de serviços do Estado do Rio Grande do Norte, tendo sido, teoricamente desenvolvidos e testados empiricamente, modelos de equações estruturais em padrões comportamentais de destino turístico. Os resultados do estudo empírico se basearam em pesquisas com a técnica de amostragem aleatória sistemática, efetuadas em Natal-RN, entre Janeiro e Março de 2013 e forneceram evidências sustentáveis de que o modelo teórico proposto é satisfatório, com elevada capacidade explicativa e preditiva, sendo a satisfação o antecedente mais importante da lealdade no destino. Além disso, a satisfação é mediadora entre a geração da motivação da viagem e a lealdade do destino e que os turistas buscam primeiro à satisfação com a qualidade dos serviços de turismo e, posteriormente, com os aspectos que influenciam a lealdade. Contribuições acadêmicas e gerenciais são mostradas e sugestões de estudo são dadas para trabalhos futuros.

Situações geográficas em movimento nas praias da área de proteção ambiental de Jenipabu: das ideologias ambientais ao território usado pelo circuito inferior do turismo

The Área de Proteção Ambiental de Jenipabu was created by Decreto 12,620/95, covering the beaches of Redinha Nova, Santa Rita and Jenipabu and Campina communities in the municipality of Extremoz, and Africa community fragment, in Natal. This protected area was created in the context of expansion of tourism in Rio Grande do Norte, in the 1990s, in which PRODETUR investments made possible the installation of infrastructure equipment, mainly in the Via Costeira and Ponta Negra beach in Natal by inserting it in the sun and sea tourism route to Northeast Brazil. In this context the beach Jenipabu in Extremoz, became one of the main attractions for those visiting Natal, due to the natural elements of its landscape, its dune field, which is offered to tourists the buggy ride. In December 1994 the excess buggy rides held in these dunes led to IBAMA ban their access to buggy for carrying out environmental study. This measure resulted in the creation of APAJ in 1995 with the goal of ordering the use and occupation to protect its ecosystems, especially the dunes, the disordered tourism. Given this context, this work aims to analyze the process of creating the APAJ and changes in the geographic space of its beaches, Redinha Nova, Santa Rita and Jenipabu, from the materialization of tourism process, as well as their implications for its residents. To this end, this paper presents a discussion of environmental currents that developed in the western portion of the globe, focusing on the need to regulate small areas of the national territory in protected areas, and an analysis of public policies that enabled the implementation tourism in APAJ as well as the laws and decrees governing the process of creation and management. Using the theory of circuits of urban economy of the Santos (2008) to analyze the territory used by tourism on the beaches of Redinha Nova, Santa Rita and Jenipabu, showing their dependent relationship with the territory used by the upper circuit on the Via Costeira and in the Ponta Negra beach and its influence on the APAJ urbanization process. Ending with the analysis of the influence of the materialization of tourism in the transformation of stocks ways of being-in-space and space-be of the Santa Rita and Jenipabu beaches in each geographical situation of APAJ among the first decades of the twentieth century to the 2014. Fieldwork was conducted between 2012 and 2014, performing actions of qualitative interviews with older residents of Santa Rita and Jenipabu beaches, interviews with structured questionnaire with merchants of APAJ and collecting GPS points trades, identifying and mapping the territory used by the lower circuit in APAJ beaches.

Antecedentes da intenção de uso de comentários de viagem on-line na escolha de um meio de hospedagem

The Internet is present in each step of a trip planning. The constant technological advances has made major changes in the tourism industry. This is noticeable by the growing number of people who share their travel experiences on the Internet. This study has aimed to analyze the factors that influence the use of the Online Travel Reviews (OTR) in choosing an accommodation. It was done an investigation into the comments available on the internet about information on touristic products and services, specifically about accommodations. The research proposed to understand the influencing factors of OTR, in the Brazilian context, through the Technology Acceptance Model, Motivational Theory, Similarity, and Trustworthiness. The methodology used was a descriptive-exploratory study, with a quantitative approach, and bibliographic research. The study used a Structural Equation Modeling technique called Partial Least Squares (PLS), to test and evaluate the proposed research model. Data collection was performed with 308 guests hosted in five hotels in Ponta Negra (Natal/RN), who have used the OTRs in choosing an accommodation. The research tested fifteen hypotheses, where nine were confirmed, and six were rejected. The results showed that guests have attitude and intention to use the OTRs to choose an accommodation.

Posicionamento estratégico de destinos: uma análise através da percepção dos operadores de Turismo da cidade de São Paulo sobre o destino Natal, Brasil

El turismo constituye una actividad propulsora de mejorías económicas y sociales en incontables lugares alrededor del mundo, y la ciudad de Natal se posiciona como uno de los principales destinos turísticos del Nordeste brasileño. De ese modo, el objetivo del presente estudio consistió en analizar el posicionamiento estratégico del destino Natal por medio de la percepción de los operadores de turismo de la ciudad de São Paulo, principal mercado emisor de turistas del país. El estudio de carácter descriptivo-exploratorio utilizó un abordaje cualitativo y tuvo, como universo de investigación, operadoras de turismo de la capital paulista que comercializan el destino Natal. En la colecta de datos, se utilizaron la investigación bibliográfica y el estudio de campo, siendo este último efetivado por medio de un guión de entrevista semiestruturado. Ya la técnica utilizada para el análisis de los datos fue el análisis de contenido, iniciada mediante selección del material recolectado y concluida con el proceso de categorización. Cuanto a los resultados del estudio, se percibió que el paulistano que viaja al destino Natal tiene un perfil demográfico que sugiere a la práctica del turismo sustentable, está a la busca del turismo de sol y playa, y valora las bellezas naturales del lugar. Los operadores de turismo entrevistados evaluaron, positivamente, la ciudad de Natal, y destacaron los siguientes atributos del destino: playas, bellezas naturales, hostelería, receptividad de los autóctonas, gastronomía, de entre otros. Además, los respondentes demostraron tener un fuerte encariño al destino. En lo que se refiere a los aspectos negativos, prevaleció la observancia de la ineficacia de los gobiernos locales, donde el deterioro de la malla aérea y la incipiente promoción del destino fueron apuntados como los dos principales gargalos. Al analizar la competencia, se identificó que Fortaleza, Porto de Galinhas y Maceió son los tres principales concurrentes de Natal, siendo el destino pernambucano lo que presenta mejor evaluación. Por fin, se observó que no existe una diferenciación relevante en el destino Natal.

Transporte longitudinal de sedimento na zona costeira de Natal/RN

The longshore sediment transport (LST) is determinant for the occurrence of morphological changes in coastal environments. Understanding their movement mechanisms and transport is an essential source of information for the project design and coastal management plans. This study aims to characterize, initially, the active hydrodynamic circulation in the study area, comprised of four beach sectors from the south coast of Natal, assessing the average annual LST obtained through three proven equations (CERC, Kamphuis and Bayram et al.), defining the best formulation for the study area in question, and analyze the seasonal variability and the decadal transport evolution. The coastal area selected for this work constitutes one of the main tourist corridors in the city, but has suffered serious damage resulting from associated effects of hydrodynamic forcings and their disorderly occupation. As a tool was used the Coastal Modelling System of Brazil (SMC-Brazil), which presents integrated a series of numerical models and a database, properly calibrated and validated for use in developing projects along the Brazilian coastline. The LST rates were obtained for 15 beach profiles distributed throughout the study area. Their extensions take into account the depth of closure calculated by Harllermeier equation, and regarding the physical properties of the sediment, typical values of sandy beaches were adopted, except for the average diameter, which was calculated through an optimization algorithm based on equilibrium profile formulation proposed by Dean. Overall, the results showed an intensification of hydrodynamic forcings under extreme sea wave conditions, especially along the headlands exist in the region. Among the analyzed equations, Bayram et al. was the most suitable for this type of application, with a predominant transport in the south-north direction and the highest rates within the order of 700.000 m3 /year to 2.000.000 m3 /year. The seasonal analysis also indicated a longitudinal transport predominance in the south to north, with the highest rates associated with the fall and winter seasons. In these periods are observed erosive beach states, which indicate a direct relationship between the sediment dynamics and the occurrence of more energetic sea states. Regarding the decadal evolution of transportation, it was found a decrease in transport rate from the 50’s to the 70’s, followed by an increase until the 2000’s, coinciding with the beginning of urbanization process in some stretches of the studied coastline.