Uma análise teórica da evolução da rotação estelar

In the past 50 years, large efforts have been made toward the understanding of the stellar evolution. In the observational context, large sets of precise measurements of projected rotational velocity were produced, in particular by the Natal and Geneva groups. From these data, it is now possible to establish the behavior of stellar rotation from the turnoff to the red giant branch. In addition, these data have shown the role of tidal effects on stellar rotation in close binary systems. Nevertheless, relatively little attention has been paid to theoretical studies on the evolution of rotation along the HR Diagram, a topic itself directly associated to the evolution of the stars. Basically, there are two reasons for such a fact, (i) spherical symmetry is not assumed, what leads to a substantial increase in the numerical complexity of equations and (ii) non rotating models have been very successful in explaining relevant observational data, including the mass-luminosity relation and chemical abundances. In spite of these facts, it is clear that considerable work remains to be done on the role of rotation in the later stages of the evolution, where clear disagreements arise from confrontations between theoretical predictions and observations. In the present work we study the evolutionary behavior of stellar rotation along the HR Diagram, taking into account constraint conditions issued from recent observational survey of rotational velocity carried out with high precision procedures and new evolutionary codes

Cooperação em sagüis comuns callithrix jacchus: condições e restrições

The cooperative behavior is no longer a dilemma for the theory of evolution, since there are models that explain the evolution of this behavior by means of natural selection at the individual level. However, there have been few studies on the proximal factors that interfere with cooperative behavior. In the study of the influence of cognition on cooperation, many authors have been interested in situations in which individuals decide whether to act cooperatively and select partners with different qualities to cooperate. Of the factors studied, we highlight the need for understanding the apparatus and communication between partners to the occurrence of cooperation. Recently, highlight is the proposal that the ability to cooperate would be greater in species with cooperative breeding system. Thus, the common marmoset (Callithrix jacchus) is a New World monkey which stands as a valuable species for this type of study because it presents cooperative actions in nature, such as sharing food and protection of the community territory. Our experiment investigated whether common marmosets unrelated females (n = 6) were able to cooperate using an electrical and a mechanical apparatus, if this cooperation is a byproduct of individual actions or involve social attention, if it occurs inter-individual variation in the use of devices and formation of roles (producer / scrounger) in dyads. We use the number of rewards obtained by animals (Ratio of Correct Pulls) as indicators of cooperation and glances for partners (Ratio of Correct Glances) as indicators of social attention and communication. The results indicate that the type of apparatus was not a constraint for the occurrence of cooperation between the marmosets, but still has not been verified formation of roles in the dyads. The performance of animals in the two devices showed a large variation in the learning time, not having relationship with the performance in the tests phase. In both devices the level of social glances at control phases were casually correlated with any other phase, but the data showed that there was not social attention, that is, the monkeys realized that they gave food to the partners, but the partners did

O Psicólogo no campo do Bem-Estar: cartografias de práticas na saúde e assistência social

The study focuses on the psychology and Social Well-being Policy encounters. The objective is to understand how the psychologists in the health services of Natal, RN, specifically in the Basic Health Units and social assistance, experience their daily practices. The methodology included observation and interviews of 13 psychologists regarding their daily activities and forms of practice in these services. We utilized an interview protocol directed at the affective memory and the professional life history of these technicians. Field notes were used to produce a cartography of the encounter intensities experienced by the researcher in the investigated context. The data analysis enabled the construction of the following analytic axes: 1) Work processes and proximity/ distancing points between these fields; 2) Forms of government and life management in the well-being context; 3) Experiments of self in the daily services. The first axis showed the precariousness of working conditions (remuneration issues, lack of structure, of training and autonomy for the activities). In the second axis the identified care forms produced in these fields indicated an adherence to the production of ideal subjects characterized as autonomous, productive, healthy and aware of own rights . These were considered normative insofar as they express attempts to break with the established patterns. In the third axis, many technicians experienced constraint with the daily activities because they found themselves in contexts that were adverse to the habitual forms of action. This situation provoked two distinct forms of positioning: a) action expressed by compassion, pity and resentment; b) investment in the practices themselves, so as to overcome its limits and to respond innovatively to the difficulties and/or challenges that these contexts provoke

Uma investigação de algoritmos exatos e metaheurísticos aplicados ao nonograma

Nonogram is a logical puzzle whose associated decision problem is NP-complete. It has applications in pattern recognition problems and data compression, among others. The puzzle consists in determining an assignment of colors to pixels distributed in a N  M matrix that satisfies line and column constraints. A Nonogram is encoded by a vector whose elements specify the number of pixels in each row and column of a figure without specifying their coordinates. This work presents exact and heuristic approaches to solve Nonograms. The depth first search was one of the chosen exact approaches because it is a typical example of brute search algorithm that is easy to implement. Another implemented exact approach was based on the Las Vegas algorithm, so that we intend to investigate whether the randomness introduce by the Las Vegas-based algorithm would be an advantage over the depth first search. The Nonogram is also transformed into a Constraint Satisfaction Problem. Three heuristics approaches are proposed: a Tabu Search and two memetic algorithms. A new function to calculate the objective function is proposed. The approaches are applied on 234 instances, the size of the instances ranging from 5 x 5 to 100 x 100 size, and including logical and random Nonograms

Orientação de falhas presentes em testemunhos de sondagens do campo de Xaréu/bacia do Ceará

A research project is being developed by PPGG/UFRN and PETROBRAS in the Xaréu Oil Field located in Ceará Basin, Northeastern Brazil. The objective of the research is to characterize a fractured carbonate reservoir, the Trairi Limestone, in order to drill a borehole with two horizontal legs taking advantage of the natural fracture system to enhance the oil recovery. The present master thesis is part of this research and its contribution is to estimate fault orientation from unoriented cores, using the method proposed by Hesthammer & Henden (2000). In order to orient a fault cutting a bed observed in the core, the bed should be previously oriented. As additional constraint to orient the bed, we use regional bedding orientation obtained from structure maps of Trairi Limestone. Because the number of cores drilled from the Trairi Limestone was too small, we analyzed all cores from the field. As geologic constraint, we admit that all faults were formed as result of the South America and Africa separation, in the context of a regional dextral strike-slip fault formation. In this context, secondary faults are manly T and R faults according Riedel s classification. We analyzed 236.5 m of cores. The dip of bedding varies from 0o to 8o, being the most frequent value equal to 2o. We interpret this result as evidence that the deformation process was manly ruptil. 77 faults were identified in the cores. These faults strike manly to NW and NE with dips, in general, inside the interval 700 - 900. We suggest that the horizontal legs of the borehole should be oriented to NW and NE in order to improve the probability of intercepting open fractures and faults

Incorporação do vínculo de suavidade no ajuste de histórico de reservatórios de petróleo

The history match procedure in an oil reservoir is of paramount importance in order to obtain a characterization of the reservoir parameters (statics and dynamics) that implicates in a predict production more perfected. Throughout this process one can find reservoir model parameters which are able to reproduce the behaviour of a real reservoir.Thus, this reservoir model may be used to predict production and can aid the oil file management. During the history match procedure the reservoir model parameters are modified and for every new set of reservoir model parameters found, a fluid flow simulation is performed so that it is possible to evaluate weather or not this new set of parameters reproduces the observations in the actual reservoir. The reservoir is said to be matched when the discrepancies between the model predictions and the observations of the real reservoir are below a certain tolerance. The determination of the model parameters via history matching requires the minimisation of an objective function (difference between the observed and simulated productions according to a chosen norm) in a parameter space populated by many local minima. In other words, more than one set of reservoir model parameters fits the observation. With respect to the non-uniqueness of the solution, the inverse problem associated to history match is ill-posed. In order to reduce this ambiguity, it is necessary to incorporate a priori information and constraints in the model reservoir parameters to be determined. In this dissertation, the regularization of the inverse problem associated to the history match was performed via the introduction of a smoothness constraint in the following parameter: permeability and porosity. This constraint has geological bias of asserting that these two properties smoothly vary in space. In this sense, it is necessary to find the right relative weight of this constrain in the objective function that stabilizes the inversion and yet, introduces minimum bias. A sequential search method called COMPLEX was used to find the reservoir model parameters that best reproduce the observations of a semi-synthetic model. This method does not require the usage of derivatives when searching for the minimum of the objective function. Here, it is shown that the judicious introduction of the smoothness constraint in the objective function formulation reduces the associated ambiguity and introduces minimum bias in the estimates of permeability and porosity of the semi-synthetic reservoir model

Estimativa da profundidade do embasamento na bacia potiguar usando inversão gravimétrica

The gravity inversion method is a mathematic process that can be used to estimate the basement relief of a sedimentary basin. However, the inverse problem in potential-field methods has neither a unique nor a stable solution, so additional information (other than gravity measurements) must be supplied by the interpreter to transform this problem into a well-posed one. This dissertation presents the application of a gravity inversion method to estimate the basement relief of the onshore Potiguar Basin. The density contrast between sediments and basament is assumed to be known and constant. The proposed methodology consists of discretizing the sedimentary layer into a grid of rectangular juxtaposed prisms whose thicknesses correspond to the depth to basement which is the parameter to be estimated. To stabilize the inversion I introduce constraints in accordance with the known geologic information. The method minimizes an objective function of the model that requires not only the model to be smooth and close to the seismic-derived model, which is used as a reference model, but also to honor well-log constraints. The latter are introduced through the use of logarithmic barrier terms in the objective function. The inversion process was applied in order to simulate different phases during the exploration development of a basin. The methodology consisted in applying the gravity inversion in distinct scenarios: the first one used only gravity data and a plain reference model; the second scenario was divided in two cases, we incorporated either borehole logs information or seismic model into the process. Finally I incorporated the basement depth generated by seismic interpretation into the inversion as a reference model and imposed depth constraint from boreholes using the primal logarithmic barrier method. As a result, the estimation of the basement relief in every scenario has satisfactorily reproduced the basin framework, and the incorporation of the constraints led to improve depth basement definition. The joint use of surface gravity data, seismic imaging and borehole logging information makes the process more robust and allows an improvement in the estimate, providing a result closer to the actual basement relief. In addition, I would like to remark that the result obtained in the first scenario already has provided a very coherent basement relief when compared to the known basin framework. This is significant information, when comparing the differences in the costs and environment impact related to gravimetric and seismic surveys and also the well drillings