Fases magnéticas de sistemas nanoestruturados de terras-raras

There is presently a worldwide interest in artificial magnetic systems which guide research activities in universities and companies. Thin films and multilayers have a central role, revealing new magnetic phases which often lead to breakthroughs and new technology standards, never thought otherwise. Surface and confinement effects cause large impact in the magnetic phases of magnetic materials with bulk spatially periodic patterns. New magnetic phases are expected to form in thin film thicknesses comparable to the length of the intrinsic bulk magnetic unit cell. Helimagnetic materials are prototypes in this respect, since the bulk magnetic phases consist in periodic patterns with the length of the helical pitch. In this thesis we study the magnetic phases of thin rare-earth films, with surfaces oriented along the (002) direction. The thesis includes the investigation of the magnetic phases of thin Dy and Ho films, as well as the thermal hysteresis cycles of Dy thin films. The investigation of the thermal hysteresis cycles of thin Dy films has been done in collaboration with the Laboratory of Magnetic Materials of the University of Texas, at Arlington. The theoretical modeling is based on a self-consistent theory developed by the Group of Magnetism of UFRN. Contributions from the first and second neighbors exchange energy, from the anisotropy energy and the Zeeman energy are calculated in a set of nonequivalent magnetic ions, and the equilibrium magnetic phases, from the Curie temperature up to the Nèel temperature, are determined in a self-consistent manner, resulting in a vanishing torque in the magnetic ions at all planes across the thin film. Our results reproduce the known isothermal and iso-field curves of bulk Dy and Ho, and the known spin-slip phases of Ho, and indicate that: (i) the confinement in thin films leads to a new magnetic phase, with alternate helicity, which leads to the measured thermal hysteresis of Dy ultrathin films, with thicknesses ranging from 4 nm to 16 nm; (ii) thin Dy films have anisotropy dominated surface lock-in phases, with alignment of surface spins along the anisotropy easy axis directions, similar to the known spin-slip phases of Ho ( which form in the bulk and are commensurate to the crystal lattice); and (iii) the confinement in thin films change considerably the spin-slip patterns of Ho.

Conexão entre as redes complexas e estatística de Kaniadakis e busca eficiente das propriedades críticas do processo epidêmico difusivo 1D

In this work we study a connection between a non-Gaussian statistics, the Kaniadakis statistics, and Complex Networks. We show that the degree distribution P(k)of a scale free-network, can be calculated using a maximization of information entropy in the context of non-gaussian statistics. As an example, a numerical analysis based on the preferential attachment growth model is discussed, as well as a numerical behavior of the Kaniadakis and Tsallis degree distribution is compared. We also analyze the diffusive epidemic process (DEP) on a regular lattice one-dimensional. The model is composed of A (healthy) and B (sick) species that independently diffusive on lattice with diffusion rates DA and DB for which the probabilistic dynamical rule A + B → 2B and B → A. This model belongs to the category of non-equilibrium systems with an absorbing state and a phase transition between active an inactive states. We investigate the critical behavior of the DEP using an auto-adaptive algorithm to find critical points: the method of automatic searching for critical points (MASCP). We compare our results with the literature and we find that the MASCP successfully finds the critical exponents 1/ѵ and 1/zѵ in all the cases DA =DB, DA DB. The simulations show that the DEP has the same critical exponents as are expected from field-theoretical arguments. Moreover, we find that, contrary to a renormalization group prediction, the system does not show a discontinuous phase transition in the regime o DA >DB.

Espectro de Polariton de Plasmons e Ondas de Luz em Quasi-Cristais

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Estudos de modelos Estocásticos: processo de contato, séries aleatórias e processos difusivos

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Análises estatísticas em redes complexas: propriedades topológicas, críticas e dinâmicas

In this thesis, we address two issues of broad conceptual and practical relevance in the study of complex networks. The first is associated with the topological characterization of networks while the second relates to dynamical processes that occur on top of them. Regarding the first line of study, we initially designed a model for networks growth where preferential attachment includes: (i) connectivity and (ii) homophily (links between sites with similar characteristics are more likely). From this, we observe that the competition between these two aspects leads to a heterogeneous pattern of connections with the topological properties of the network showing quite interesting results. In particular, we emphasize that there is a region where the characteristics of sites play an important role not only for the rate at which they get links, but also for the number of connections which occur between sites with similar and dissimilar characteristics. Finally, we investigate the spread of epidemics on the network topology developed, whereas its dissemination follows the rules of the contact process. Using Monte Carlo simulations, we show that the competition between states (infected/healthy) sites, induces a transition between an active phase (presence of sick) and an inactive (no sick). In this context, we estimate the critical point of the transition phase through the cumulant Binder and ratio between moments of the order parameter. Then, using finite size scaling analysis, we determine the critical exponents associated with this transition

Conceitos e técnicas da mecânica estatística e termodinâmica aplicados ao estudo dos grafos aleatórios

This dissertation briefly presents the random graphs and the main quantities calculated from them. At the same time, basic thermodynamics quantities such as energy and temperature are associated with some of their characteristics. Approaches commonly used in Statistical Mechanics are employed and rules that describe a time evolution for the graphs are proposed in order to study their ergodicity and a possible thermal equilibrium between them

Velocidade da marcha como preditor de fragilidade em uma amostra populacional de idosos brasileiros

Gait speed has been described as a predictive indicator of important adverse outcomes in older populations. Among the criteria to evaluate frailty, gait speed has been identified as the most reliable predictor of fragility, practical and low cost. Objective: This study assesses the discriminating capability of gait speed in determining the presence of fragility in the elderly community in northeast of Brazil. Method: We performed an observational analytic study with a transversal character with a sample of 391 community-living elders, aged 65 years or older, of both sexes, in the city of Santa Cruz-RN. Participants were interviewed using a multidimensional questionnaire to obtain sociodemographic information, physical-related and mental health-related information. The unintentional weight loss, muscle weakness, self-reported exhaustion, slow gait and low-physical activity were considered to evaluate the frailty syndrome. Gait velocity was measured as the time taken to walk the middle 4,6 meters of 8,6 meters (excluding 2 meters to warm-up phase and 2 meters to deceleration phase).We calculate the sensitivity and specificity of gait speed test in different cutoff points for the test run time, from which ROC curve was constructed as a measure of test predictive value to identify frail elders. The prevalence of frailty in Santa Cruz-RN was 17.1%. The gait speed test accuracy was 71%when speed is below 0,91m/s. Among women, the gait speed test accuracy was 80%(gait speed below 0.77m/s) and among men, the test accuracy was 86% (gait spend below 0,82%) (p<0,0001).Conclusion: our findings have clinical relevance when we consider that the detection of frailty presence by the gait speed test can be observed in elderly men and women by a simple, cheap and efficient exam

Comparação e mobilidade, equilíbrio corporal e desempenho muscular segundo a auto-eficácia para quedas em idosas

The aging process modifies various systems in the body, leading to changes in mobility, balance and muscle strength. This can cause a drop in the elderly, or not changing the perceived self-efficacy in preventing falls. Objective: To compare the mobility, body balance and muscle performance according to self-efficacy for falls in community-dwelling elderly. Methods: A cross-sectional comparative study with 63 older (65-80 years) community. Were evaluated for identification data and sociodemographic, cognitive screening using the Mini Mental State Examination (MMSE), effective for the fall of Falls Efficacy Scale International Brazil (FES-I-BRAZIL), Mobility through the Timed Up and Go Test , the balance Berg Balance Scale (BBS) and the Modified Clinical Test tests of Sensory Interaction on Balance (mCTSIB), tandem walk (TW) and Sit to Stand (STS) of the Balance Master® System. Finally, muscle performance by using isokinetic dynamometry. Statistical analysis was performed Student t test for comparison between groups, with p value ≤ 0.05. Results: Comparing the elderly with low-efficacy for falls with high-efficacy for falls, we found significant differences only for the variable Timed Up and Go Test (p = 0.04). With regard to data on balance tests were significant differences in the speed of oscillation firm surface eyes open modified Clinical Test of Sensory Interaction on Test of Balance (p = 0.01). Variables to isokinetic dynamometry were no significant differences in movement knee extension, as regards the variables peak torque (p = 0.04) and power (p = 0.03). Conclusion: The results suggest that, compared to older community with low-and high-efficacy for falls, we observed differences in variables related to mobility, balance and muscle function

Viagem-memória de Nilo Pereira: do Ceará Mirim ao Recife e do Recife ao Ceará Mirim

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Percepção dos idosos sobre saúde bucal

The assessment of oral health status in elderly patients is essential for the development of specific health policies. The prevalence of oral diseases is high in this population. The self-perception of oral health conditions influences the demand for oral care and quality of life for seniors. The aim of this study was to assess self-perception of oral health status in 100 elderly of both sexes, aged 60 years or older and functionally independent the Basic Health Unit of Felipe Camarão II, Natal, Brazil. For comparison of self-perception data was collected in Bom Pastor, Natal / RN. In this research data were collected a questionnaire grouped into two parts. The first part with the socio-demographic data, subjective and objective condition of oral health and access to the service, the second part GOHAI Index. This index consists of 12 items that make it possible to obtain information involving aspects of chewing, speech, phonation, and self-assessed oral health. The results were subjected to statistical tests of Mann-Whitney and Kruskal-Wallis test (α = 0.05), to identify possible predictors of self-evaluation. As a result, 69% were female, ages ranged from 60 to 86 years, with a median of 65 years. In relation to marital status 48% were married. For the years of study, the sample had an average of 3 years. For the last visit to the dentist, only 27% of seniors had visited the Dentist for less than a year. Regarding the questions about the presence of gingival and dental problems were answered by 46% and 21% respectively. The data on the perception of your teeth and gums, 44%. The index showed GOHAI value for self-perception of 30 points to Felipe Camarão and 28 points for the Bom Pastor, both considered a low perception. We identified predictors of self-rated number of people in the room, participate in any associational activity, there is problems with your teeth and your gums. Concluded a negative self-perception of oral health condition by Gone in both areas, influenced by socioeconomic and cultural issues, although they realize the importance given to oral health, but by the misfortunes of other prominent favored little valuing of oral health

Reflexões sobre a formação clínica fenomenológico-existencial na era da técnica

Phenomenology is the focus of this study for its critique of the limits of positivist science, which guides most of the fields of study including Psychology. The clinical formation process in Psychology courses is especially difficult for students-interns who adopt phenomenology as their clinical framework. Such difficulty is due to the incompatibility between theory provided in Psychology courses a science traditionally based on paradigms of scientism , and the theoretical-methodological proposal adopted by the aforementioned approach. As a backdrop for our study, we carefully examined the thought of philosopher Martin Heidegger, especially the Era of Technique. This contemporary technicism society was studied so that we could understand the socio-cultural status where this formation lies. Thus, we questioned if this panorama upon which Clinical Psychology rests favors the development of a phenomenological attitude and a special look at the meanings of existence, as defined in phenomenological clinical practice. Knowing such limits, our research aimed at understanding the experience of formation of clinical psychologists who take part in internships in the field of phenomenology-existentialism. Such study was, then, a phenomenological-hermeneutic research based on Heideggerian ontology and used a semi-structured interview as access tool. Six students of the UFRN higher-degree Psychology course who were doing their supervised internship in clinical psychology and the referred approach took part in this research. The research revealed that the phenomenological-existential formation phase opens a door to discoveries on the part of the intern that transcend the dimension of the other, for they show a self disclosure while a person in the word. Despite the initial discomforts caused by the course curriculum itself and by the freedom for clinical practice, so characteristic of phenomenology, the narratives demonstrate that such difficulties may start a process of search for new meanings, which show a search for sharpening their practices and for a path in balance with the existence of the other

Efeito de diferentes níveis de bicarbonato de sódio em dietas com bagaço de cana-de-açúcar auto-hidrolisado sobre a degradação in situ do milho e farelo de algodão

The objective of this work was to evaluate the buffering effect of sodium bicarbonate (NaHCO3), used in the levels of: 0, 0.7, 1.4 and 2.1% of dry matter, on the in situ degradation of corn and cottonseed meal. A diet with 60% autohidrolised sugar bagasse (BAH) and 40% of concentrate was used, plus urea, minerals and limestone. The rations was calculated to allow 300g of daily gain. After 20 days of adaptation to the treatment (levels of NaHCO3), 5g of each feed was incubated in the rumen of four bovines for 3, 6, 12, 24 and 48 hours, using naylon bag with size of 7,5 x 17,5 cm with pores of 36 micras. A randomized blocks design with four treatment (levels of NaHCO3) were used. The buffer affected the in situ dry matter degradation, whose means were 49.68; 63,10; 67,71; and 60,85% and 25.89; 30.88; 33.48 and; 31.02% for the corn and cottonseed meal, respectively. The level of 1.4% of NaHCO3 provided the highest value of degradability, which did not differ from the 0.7% and 2.1% levels, for the corn. The degradability of protein was not affected by the treatments.

Identidade, espaço e tempo: negociações de sentido sobre a "gente de rua"

This research examines the street children s identity construction processes. Recently, the research about this population has focused on the socialization processes that organize their everyday, their situations of interaction, the meanings of their social practices, their street experience. The concept of identitary forms gives coherence to the set of these phenomena, articulating them theoretically, in order to describe their life conditions and details of their trajectories. This research utilized an ethnographic approach with a group of 11 street people, 9 of them boys and girls 16-18 years old, during 3 months. It included participant observation, informal and formal interviews, that resulted in young s narratives of lifestory. These narratives were interpreted according to the principles of positioning analysis and the Labovian Analysis model of oral narratives of personal experience. The observation of interaction among the studied group and other groups has showed that their social practices, supported on many particular bodily technologies, recreate space and time of these interactions semantically, as mediation of meaning negotiations among groups. Such meanings transform again the environment of these interactions, disclosing interpretative systems by means of which the groups apprehend this interaction in a particular way. These street children s bodily technologies imply identitary forms based on scarcity and abandonment, paradoxicalally related to their self-concept. The analysis of narratives revealed diversity and complexity in the meanings assembly for their street experience; it showed that the semantic arrangements reconstruct the temporal experience, creating a moral climate for each lifestory, and determining more or less aperture of identitary forms to change. The study concludes that space and time, builders of interaction regimes, produce identitary forms; that the narratives and the social practices of the studied group are sustained upon a master discourse that opposes the meanings of the home and the life in the streets

Elaboração e avaliação de indicadores comportamentais de aderência ao tratamento hemodialítico

Introduction: This work intents to characterize behavioral indicators of tack to the hemodialysis treatment in a sample of carrying patients of chronic kidney failure (CKF) in the great Natal/RN. The therapeutical adherence represents the agreement degree between the patient behavior and the health team lapsings. The CKF is the gradual and irreversible loss of the renal function, being the hemodialysis treatment an important alternative to assist or to substitute the kidneys. Method: The sample consisted in 80 chronic kidney patients in hemodialysis treatment in two located clinical centers in the region of the great Natal, RN. It was used as instruments (a) a protocol of clinical data collection, (b) the Millon Index of Personality Styles (MIPS) and (c) a script of halfstructuralized interview. Results: The results show a balance between the genders (51% of female and 48.8% of the male sex), average age and equal average time of dialysis respectively to the 43,4 years (±13,25 years) and 22,04 years (±4,24 years). The marital status of half of the sample is married, predominating basic education (43.6%) and a familiar income until a minimum wage (43.8%). It had been defined six physicianlaboratorial indicators to evaluate the therapeutical adherence, further the use of the evaluation of the health team and the patient themselves. Thus, there was an average adherence around 55.97% of the sample ±18.37%). However only between selfassessment of the patients about the adherence and the assessment made by blood pressure post-dialysis indicated a significant association (p=0,029, qui-square test). On the other hand, there was a significant association (p <0.05, chi-square test) among the criteria for treatment adherence and issues investigated in the interview - the perception on the quality of the health services provided to patients, the difficulties following the prescribed diet, the characterization of the days between dialysis sessions and the perception of patients about the dialysis sessions. It was also noted a significant association (p <0.05, Levene test) between adherence to therapy and scales that constitute the MIPS. The health team characterized the patients more adherent behavior as an attitude of acceptance of the treatment, looking actively for their implementation, for more information and knowledge, and establishing a positive communication with the team and with other patients. Similar results were confirmed by the MIPS evaluation. According to that assessment the more compliant patients adopt a more optimistic attitude, trying to act or adapt themselves to their environment, processing cognitively both concrete and objective information, such as more speculative and symbolic information. In addition they establish a gregarious, cooperative, submissive and flexibly pattern of interpersonal relationships to social demands. These characteristics managed to explain 55.7% of the adherence variation according the health team and 23.3% of the variation according the CaxP laboratory indicator. Conclusions: The MIPS shown to be able to identify the most and least adherent to therapy patients. The use of different adherence indicators is important for an evaluation covering the different facets of this process. The adhesion levels are observed within registered by the relevant literature. There is need for further studies with a larger sample to deepen the data findings in this work

Adaptação e validação da escala de motivação à prática de atividades físicas

The study of the motivation to practice physical activities is relevant once through this it is possible to develop intervention strategies for sedentary population. In this way, the present dissertation aimed to adapt and validate for the Brazilian context the Motives for Physical Activity Measure Revised (MPAM-R). It was investigated yet the relation of some socio-demographic variables (age, gender, Body Mass Index - BMI, types of physical activity; way to practice and time of practice) and the participants means in the motives studied. The physical activity (PA) is defined as any bodily movement produced by skeletal muscles resulting in energy expenditure above the basal level. However, in the present study it was considered motivation for two types of PA: the physical exercises and sports. The Self-Determination Theory (SDT) underlay this research, once it has been used in the sportive context, beyond the facto of it was used as theoretical base to the development of MPAM-R. To attain the proposed goals, it was accomplished translations to Portuguese of the original English scale. Next, was carried out the semantic analysis and the judge analysis. For the empirical analysis of items, participated 309 practitioner of PA, classified in physical exercises practitioners and sports practitioners, with ages between 16 and 74 years, distributed equally by sex. They answered the final version in Portuguese of the MPAM-R and socio-demographic questions. The data was collected in Natal/RN, where the researcher approached people in some places where the PA is practiced, following she communicated that their involvement will be spontaneous and their responses will be confidential. The obtained results pointed the confirmation of the existence of five factors in the final version of the instrument, that was composed by 26 items that presented the following statistics indexes: x² (289) = 757.75, p < 0.000, x²/DF = 2.62, with GFI of 0.83, AGFI of 0.80 and RMSEA of 0.07. The reliability (Cronbach Alpha) of the complete instrument was 0.90, and the indexes of each factor were considered satisfactory too: Enjoyment (α = 0.88), Health (α = 0.84), Appearance (α = 0.79), Competence (α = 0.85) and Social (α = 0.75). It was observed that, in general, the main motive presented by the participants to practice PA was Health. It was verified yet, that women and aged had a higher mean in the Health factor; among the exercise practitioners was found a higher mean in the Appearance factor; and a higher mean in the Social factor was found among those that practice PA with accompaniment. It was concluded that the MPAM-R presented satisfactory psychometric parameters, became it useful in futures researches. Moreover, proposed the accomplishment of new studies that considered others variables to the intent of the better understanding of motivation to practice physical activity