Fases e criticalidade no modelo ashkin - teller de três cores

The usual Ashkin-Teller (AT) model is obtained as a superposition of two Ising models coupled through a four-spin interaction term. In two dimension the AT model displays a line of fixed points along which the exponents vary continuously. On this line the model becomes soluble via a mapping onto the Baxter model. Such richness of multicritical behavior led Grest and Widom to introduce the N-color Ashkin-Teller model (N-AT). Those authors made an extensive analysis of the model thus introduced both in the isotropic as well as in the anisotropic cases by several analytical and computational methods. In the present work we define a more general version of the 3-color Ashkin-Teller model by introducing a 6-spin interaction term. We investigate the corresponding symmetry structure presented by our model in conjunction with an analysis of possible phase diagrams obtained by real space renormalization group techniques. The phase diagram are obtained at finite temperature in the region where the ferromagnetic behavior is predominant. Through the use of the transmissivities concepts we obtain the recursion relations in some periodical as well as aperiodic hierarchical lattices. In a first analysis we initially consider the two-color Ashkin-Teller model in order to obtain some results with could be used as a guide to our main purpose. In the anisotropic case the model was previously studied on the Wheatstone bridge by Claudionor Bezerra in his Master Degree dissertation. By using more appropriated computational resources we obtained isomorphic critical surfaces described in Bezerra's work but not properly identified. Besides, we also analyzed the isotropic version in an aperiodic hierarchical lattice, and we showed how the geometric fluctuations are affected by such aperiodicity and its consequences in the corresponding critical behavior. Those analysis were carried out by the use of appropriated definitions of transmissivities. Finally, we considered the modified 3-AT model with a 6-spin couplings. With the inclusion of such term the model becomes more attractive from the symmetry point of view. For some hierarchical lattices we derived general recursion relations in the anisotropic version of the model (3-AAT), from which case we can obtain the corresponding equations for the isotropic version (3-IAT). The 3-IAT was studied extensively in the whole region where the ferromagnetic couplings are dominant. The fixed points and the respective critical exponents were determined. By analyzing the attraction basins of such fixed points we were able to find the three-parameter phase diagram (temperature £ 4-spin coupling £ 6-spin coupling). We could identify fixed points corresponding to the universality class of Ising and 4- and 8-state Potts model. We also obtained a fixed point which seems to be a sort of reminiscence of a 6-state Potts fixed point as well as a possible indication of the existence of a Baxter line. Some unstable fixed points which do not belong to any aforementioned q-state Potts universality class was also found

Jardim do Seridó: A construção dos espaços públicos na Veneza Seridoense nas primeiras décadas do século XX

As the space and the city are objects of desires, interests, seduction, sedition, appropriations, battles, victories, defeats, require to be analyzed historically. This research investigates and discusses the construction of public spaces in Jardim do Seridó City, backwoods of Rio Rio Grande do Norte, in the first decades of twentieth century, when the municipality was chaired by Heráclio Pires Fernandes, who ruled from 1917 to 1930 and was graduated from the University of Pharmacy of Recife, where he contacted the architectural, political and artistic influences circulating in the capital of Pernambuco. In the first decades of the twentieth century, the space of Jardim earns statements and practices, against the discourse of modernity, which sought to justify the title of Veneza Seridoense . At the time, the city had undergone several transformations in its public spaces through the construction of the Butchery, the Market, the Public Roads connecting the city to other urban centers, the building of the Bridge of the Pedra Lavrada Farm, the Elementary School Antônio de Azevedo , the creation of the Music Band Euterpe Jardinense , the Literary and Recreative Guild, the pavilion, the paving, tree planting, lighting, streets naming and listing of the annual painting of households, the arrival of automobiles, mail and telegraph. The construction of these new sceneries and the arrival of equipments generated impacts in the daily life of the population and were received differentiated ways by individuals involved in the process, which shows the tension between old and new, the relationship between history and space

Preparação de resinas de poliuretana à base de óleo de mamona e dietanolamina

The aim of this work was the preparation of polyols from reactions between castor oil and dietanolamine to increase the hydroxyl content and the network degree in the products to application in electronic devices. The polyols and the mixtures obtained were characterized by nuclear magnetic ressonance. Castor oil (CO) is a natural triglyceride - based polyol possessing hydroxyl groups, which allow several reactions that produce many different products. Among them are the polyurethanes (PU), which have been considered an ideal product for the covering of electricelectronic circuits, due to their excellent electrical, shock-absorbing, solvents resistance and hydrolytic stability properties. About 90% of the fatty acids present in the castor oil are ricinoleic acid (12-hydroxyoleic acid), while the remaining 10% correspond to non-hydroxylated fatty acids, mainly linoleic and oleic acids. The chemical analysis of castor oil indicates a hydroxyl number of 2.7. In this work, a polyol was obtained by the reaction of the CO with diethanolamine (DEA), in order to elevate the hydroxyl value from 160 to 230 or to 280 mgKOH/g, and characterized by nuclear magnetic resonance (NMR) 1H and 13C (Mercury 200). The polyadition of the resulting polyol with isophorone diisocianate (IPDI) was carried out at 60°C, and the reaction kinetics was followed by rheological measurements in a Haake RS150 rheometer. The electrical properties were determined in a HP LCR Meter 4262A, at 1.0 Hz and 10.0 KHz. The chemical analysis showed that the polyols obtained presented hydroxyl number from 230 to 280 mgKOH/g. The polyadition reaction with IPDI produced polyurethane resins with the following properties: hardness in the range from 45 shore A to 65 shore D (ASTM D2240); a dielectric constant of 3.0, at 25°C (ASTM D150). Those results indicate that the obtained resins present compatible properties to the similar products of fossil origin, which are used nowadays for covering electric-electronic circuits. Therefore, the PUs from castor oil can be considered as alternative materials of renewable source, free from the highly harmful petroleum - derived solvents

Violência nas escolas: Um novo olhar ante as relações sociais

The most varied ways of manifestation of the violence phenomenon in the contemporary society are each time more found in the media spaces and among society discussions. It makes think about procedures to be taken before the growth and new outbreaks of such phenomenon. The violences manifestations in schools reveal themselves as a reflection of what happens in the scope of social violence. Its dynamics originates in society and reflects itself in scholl, that is, the violences in schools combine internal and external elements to school enviroment of many fields and spheres of which the individuals participate. To reflect about the violences in the schools requires, over all, to make a bridge with the categories: youth and violence. Violences in schools: A new look to the social relations, is a Ms. Sc. Dissertation that has as main objective: to analyze the main existing forms of violence in the school space. For its achievement, it was made a bibliographical survey, questionnaires application (annexed) and observation. Thus, this research articulated the two approaches: qualitative and quantitative. The questionnaires application happened in a state school of the Natal city and amongst yhe criteria for this choice there was the fact of the school had more than 500 pupils, to be located on a strategical place of the city, providing a subjects heterogeneity to be researched, deyond the limitations of available resources financial and material and the available time for the research accomplishment. The scool congregates objective conditions, specifically in what concerns the criteria previously defined: age range, socioenomical level and number of pupils. Amongst the main results obtained, it can be detached that the violence is a phenomenon seen, for the great majority of the research subjects, as a phenomenon connected to the most visible violence forms: the agressions. And a question always present in the public education institutions: infrastructures precariousness, high scool evasion índex and vulnerability among the pupils that makes possible to the pupil to see school as an home extension. Such dissertation concludes that the phenomenon of the violence in scools demands and requires of the most varied subjects involved in the processes na understanding of its determinants so that thus, one can intervene in such phenomenon that does not restrains itself to the physical acts of aggression, but that it is, over all, on a non respecting the different

BRIDGE: uma ferramenta para o Design de Interfaces de Usuário baseada em especificações IMML

With hardware and software technologies advance, it s also happenning modifications in the development models of computational systems. New methodologies for user interface specification are being created with user interface description languages (UIDL). The UIDLs are a way to have a precise description in a language with more abstraction and independent of how will be implemented. A great problem is that even using these nowadays methodologies, we still have a big distance between the UIDLs and its design, what means, the distance between abstract and concrete. The tool BRIDGE (Interface Design Generator Environment) was created with the intention of being a linking bridge between a specification language (the Interactive Message Modeling Language IMML) and its implementation in Java, linking the abstract (specification) to the concrete (implementation). IMML is a language based on models, that allows the designer works in distinct abstraction levels, being each model a distinct abstraction level. IMML is a XML language, that uses the Semiotic Engineering concepts, that deals the computational system, with the user interface and its elements like a metacommunicative artifact, where these elements must to transmit a message to the user about what task must to be realized and the way to reach this goal. With BRIDGE, we intend to supply a lot of support to the design task, being the user interface prototipation the greater of them. BRIDGE allows the design becomes easier and more intuitive coming from an interface specification language

Metais pesados no caranguejo Ucides cordatus (Linnaeus, 1763) e ecotoxicologia de sedimentos do estuario dos Rios Jundiai e Potengi - RN

This study is conducted in the estuary of the rivers Jundiaí and Potengi, one of the most important estuaries of Rio Grande do Norte, which suffers a strong anthropogenic influence from neighboring cities. According to Resolution 344/2005 environments that have high concentrations of metals such as arsenic, cadmium, lead and mercury need ecotoxicological tests. This study aims to evaluate the heavy metals contamination in the estuary through analysis of sediment collected at four points distributed from Macaíba to Natal city, and in the crab Uçá, Ucides cordatus. The study aims also to evaluate the effects of sediment toxicity in the tests organisms Leptocheirus plumulosus. To obtain data about the concentrations of heavy metals in the environment, sediments were collected in January and May 2011 and crab Uçá was collected in June 2011. On the other hand the monitoring was carried out through toxicological tests with sediment collected from July to October 2011. During the collection of sediment samples the physico-chemical parameters of water (dissolved oxygen, pH, chloride, turbidity, conductivity and temperature) were measured by using multi-parametric probe (TROLL 9500). It was possible to identify contamination by metals such as lead, cadmium, arsenic and copper both in the sediment and in the Uçá crab, which characterizes that the consumption of this crustacean may be a risk to human health. Once the concentrations of metals were identified, toxicology tests were performed and revealed toxic effect to organisms in at least one of the four months studied. Point 2 was classified as toxic in three of the four months studied . The heavy metal contamination is a risk to the environment, to aquatic organisms and to the community which survives of resources taken from the environment