O uso de modelos ocultos de Markov no estudo do fluxo de rios intermitentes

In this work, we present our understanding about the article of Aksoy [1], which uses Markov chains to model the flow of intermittent rivers. Then, we executed an application of his model in order to generate data for intermittent streamflows, based on a data set of Brazilian streams. After that, we build a hidden Markov model as a proposed new approach to the problem of simulation of such flows. We used the Gamma distribution to simulate the increases and decreases in river flows, along with a two-state Markov chain. The motivation for us to use a hidden Markov model comes from the possibility of obtaining the same information that the Aksoy’s model provides, but using a single tool capable of treating the problem as a whole, and not through multiple independent processes

Teoria da Ruína em um Modelo de Markov com dois Estados

In this work, we present a risk theory application in the following scenario: In each period of time we have a change in the capital of the ensurance company and the outcome of a two-state Markov chain stabilishs if the company pays a benece it heat to one of its policyholders or it receives a Hightimes c > 0 paid by someone buying a new policy. At the end we will determine once again by the recursive equation for expectation the time ruin for this company

O paradoxo da superdifusão de uma caminhada aleatória com memória exponencial

The random walk models with temporal correlation (i.e. memory) are of interest in the study of anomalous diffusion phenomena. The random walk and its generalizations are of prominent place in the characterization of various physical, chemical and biological phenomena. The temporal correlation is an essential feature in anomalous diffusion models. These temporal long-range correlation models can be called non-Markovian models, otherwise, the short-range time correlation counterparts are Markovian ones. Within this context, we reviewed the existing models with temporal correlation, i.e. entire memory, the elephant walk model, or partial memory, alzheimer walk model and walk model with a gaussian memory with profile. It is noticed that these models shows superdiffusion with a Hurst exponent H > 1/2. We study in this work a superdiffusive random walk model with exponentially decaying memory. This seems to be a self-contradictory statement, since it is well known that random walks with exponentially decaying temporal correlations can be approximated arbitrarily well by Markov processes and that central limit theorems prohibit superdiffusion for Markovian walks with finite variance of step sizes. The solution to the apparent paradox is that the model is genuinely non-Markovian, due to a time-dependent decay constant associated with the exponential behavior. In the end, we discuss ideas for future investigations.

A gestão da qualidade nos cursos de graduação a distância da UFRN/SEDIS : a percepção dos discentes

This dissertation has as objective at analyzing the students' perception about the quality of graduate courses distance of the Federal University of Rio Grande do Norte, which was motivated by the following research problem: the perception that graduate students of the distance of the UFRN have on the quality of the undergraduate? To this end, we sought to gather evidence for a satisfactory approach that addresses the complexity of the subject studied: quality management, distance learning and quality in the Higher Education Institutions. We chose to adopt as a research method, case study on the procedure of the research, exploratory research-descriptive about the objective and quantitative research when tackling the problem. The object of the study were six graduate courses distance UFRN/SEDIS, having as target the students of the courses. The sample was calculated using the Stratified sampling on which 217 students, the courses surveyed were selected. The survey instrument consisted of 21 structured questions, of which seven questions designed to identify the profile of students, seven issues of perceptions (manifest variables) on quality management in distance learning, where students have given values (responses) for 24 statements (which address the central theme of this dissertation) composite based on a 5-point Likert s scale, and six questions about general characteristics that may interfere with students' perception about the quality. Was used as statistical method (data analysis), descriptive statistics and exploratory factor analysis. The results show the identification of four latent factors (obtained by exploratory factor analysis), namely: (1) infrastructure and management - polo presence, (2) teaching-learning processes, (3) communication tools and integration; (4) tutors. We also observed that aspects related to infrastructure and management at the pole face had the lowest score among the factors observed, requiring special attention by the education institution. On the other hand, teachers and teaching learning processes were the items with better performance in the perception of students. It is concluded that the perception of students in relation to quality in distance education courses, the median is trending positive perception, ie the perception of overall quality of the courses is not assertive and unison, but tends to positive perception. Thus, the results, it is expected that the managers of the institution to focus attention on critical points in order to minimize them (or eliminate them) and maximize the positive aspects that are perceived by the students

Avaliação do cuidado de enfermagem na perspectiva da segurança do paciente em unidades de terapia intensiva: na visão de profissionais, pacientes e familiares

Technological advances combined with healthcare assistance bring increased risks related to patient safety, causing health institutions to be environments susceptible to losses in the provided care. Sectors of high complexity, such as Intensive Care Units have such characteristics highlighted due to being spaces designed for the care of patients in serious medical condition, when the use of advanced technological devices becomes a necessity. Thus, the aim of this study was to assess nursing care from the perspective of patient safety in intensive care units. This is an evaluative research, which combines various forms of data collection and analysis in order to conduct a deepened investigation. Data collection occurred in loco, from April to July 2014 in hospitals equipped with adult intensive care unit services. For this, a checklist instrument and semi-structured interviews conducted with patients, families, professionals were used in order to evaluate the structure-process-outcome triad. The instrument for nursing care assessment regarding Patient Safety included 97 questions related to structure and processes. Interviews provided data for outcome analysis. The selection of interviewees/participants was based on the willingness of potential participants. The following methods were used to collect data resulting from the instrument: statistical analysis of inter-rater reliability measure known as kappa (K); observations from judges resulting from the observation process; and added information obtained from the literature on the thematic. Data analysis from the interviews was carried out with IRAMUTEQ software, which used Descending Hierarchical Classification and Similarity analysis to aid in data interpretation. Research steps followed the ethical principles presented by Resolution No. 466 of December 12, 2012, and the results were presented in three manuscripts: 1) Evaluation of patient safety in Intensive Care Units: a focus on structure; 2) Health evaluation processes: a nursing care perspective on patient safety; 3) Patient safety in intensive care units: perception of nurses, family members and patients. The first article, related to the structure, refers to the use of 24 items of the employed instrument, showing that most of the findings were not aligned with the adequacy standards, which indicates poor conditions in structures offered in health services. The second article provides an analysis of the pillar of Processes, with the use of 73 items of the instrument, showing that 50 items did not meet the required standards for safe handling due to the absence of adequate scientific guidance and effective communication in nursing care process. For the third article, results indicate that intensive care units were safe places, yet urges for changes, especially in the physical structure and availability of materials and communication among professionals, patients and families. Therefore, our findings suggest that the nursing care being provided in the evaluated intensive care units contains troubling shortcomings with regards to patient safety, thereby evidencing an insecure setting for the assistance offered, in addition to a need for urgent measures to remedy the identified inadequacies with appropriate structures and implement protocols and care guidelines in order to consolidate an environment more favorable to patient safety.

A produção do cuidado no período gravídico-puerperal: experiência de mulheres usuárias de serviços públicos de saúde

Despite numerous government projects aimed at reorganizing and qualifying obstetric and neonatal care in Brazil, it remains problematic, with repercussions for maternal and newborn mortality and humanized care of both the mother and child. The objective of this study was to analyze the care provided to women during the pregnancy-puerperium cycle, based on reports of public health service users regarding their pregnancy and delivery experiences, using comprehensiveness and humanization as reference. The study applied a qualitative approach and the methodological strategy consisted of listening to the women, in order to identify, based on the meanings of their discourse concerning their experiences with health services, continuities and discontinuities of care during the pregnancy-puerperium cycle. Study participants were women who gave birth at a municipal public maternity, residents of Natal, Brazil, who at the time of the interviews, were between 10 and 42 days postpartum. Seven women reported their pregnancy and delivery experiences at public services. As interviews and observation took place, the material produced was also analyzed, in order to achieve simultaneous production and data analysis. Using systematization, a dialogue was established between the women’s discourses and production in the field of Collective Health, with respect to concepts and discussion about obstetric and neonatal care as well as the Comprehensiveness and Humanization of such care. Participant discourses underscored aspects related to prenatal care starting at pregnancy and its repercussions as well as prenatal monitoring by health services; aspects associated with care during labor and delivery, as well as those involved in postpartum in the maternity, both with respect to newborn and maternal careç and lastly, puerperium care after discharge from the maternity. Analysis of results sought to identify lines of continuity and discontinuity in the comprehensiveness and humanization of care. Based on these lines and as final contributions of the study, the following paths were proposed to achieve comprehensive and humanized production of health care for women during the pregnancy-puerperium cycle: Path 1- Reassess care in the maternal and newborn health network, aimed at comprehensiveness in terms of guaranteeing access to the various services and technological resources available to enhance health and life. Path 2- Reorganize work processes in order to attain comprehensive and humanized care for women in the pregnancy-puerperium cycle. Path 3 – Qualify the professional-user relationship in care management during the pregnancy-puerperium cycle. Path 4 – Invest in the qualification of communication processes in the different dimensions of care during the pregnancy-puerperium cycle.

A produção do cuidado no período gravídico-puerperal: experiência de mulheres usuárias de serviços públicos de saúde

Despite numerous government projects aimed at reorganizing and qualifying obstetric and neonatal care in Brazil, it remains problematic, with repercussions for maternal and newborn mortality and humanized care of both the mother and child. The objective of this study was to analyze the care provided to women during the pregnancy-puerperium cycle, based on reports of public health service users regarding their pregnancy and delivery experiences, using comprehensiveness and humanization as reference. The study applied a qualitative approach and the methodological strategy consisted of listening to the women, in order to identify, based on the meanings of their discourse concerning their experiences with health services, continuities and discontinuities of care during the pregnancy-puerperium cycle. Study participants were women who gave birth at a municipal public maternity, residents of Natal, Brazil, who at the time of the interviews, were between 10 and 42 days postpartum. Seven women reported their pregnancy and delivery experiences at public services. As interviews and observation took place, the material produced was also analyzed, in order to achieve simultaneous production and data analysis. Using systematization, a dialogue was established between the women’s discourses and production in the field of Collective Health, with respect to concepts and discussion about obstetric and neonatal care as well as the Comprehensiveness and Humanization of such care. Participant discourses underscored aspects related to prenatal care starting at pregnancy and its repercussions as well as prenatal monitoring by health services; aspects associated with care during labor and delivery, as well as those involved in postpartum in the maternity, both with respect to newborn and maternal careç and lastly, puerperium care after discharge from the maternity. Analysis of results sought to identify lines of continuity and discontinuity in the comprehensiveness and humanization of care. Based on these lines and as final contributions of the study, the following paths were proposed to achieve comprehensive and humanized production of health care for women during the pregnancy-puerperium cycle: Path 1- Reassess care in the maternal and newborn health network, aimed at comprehensiveness in terms of guaranteeing access to the various services and technological resources available to enhance health and life. Path 2- Reorganize work processes in order to attain comprehensive and humanized care for women in the pregnancy-puerperium cycle. Path 3 – Qualify the professional-user relationship in care management during the pregnancy-puerperium cycle. Path 4 – Invest in the qualification of communication processes in the different dimensions of care during the pregnancy-puerperium cycle.

Utilizando processos geométricos da história da matemática para o ensino de equações do 2º grau

The present work had as principal objective to analyze the, 9th grade students understanding about the solutions of an equation of the 2° degree, using geometric processes of the History of the Mathematics. To do so, the research had as base the elaboration and application of a group of teaching activities, based on Jean Piaget's construtivism. The research consisted of a methodological intervention, that has as subjects the students of a group of 9th grade of the State School José Martins de Vasconcelos, located in the municipal district of Mossoró, Rio Grande do Norte. The intervention was divided in three stages: application of an initial evaluation; development of activities‟ module with emphasis in constructive teaching; and the application of the final evaluation. The data presented in the initial evaluation revealed a low level of the students' understanding with relationship to the calculation of areas of rectangles, resolution of equations of the 1st and 2nd degrees, and they were to subsidize the elaboration of the teaching module. The data collected in the initial evaluation were commented and presented under descriptive statistics form. The results of the final evaluation were analyzed under the qualitative point of view, based on Richard Skemp's theory on the understanding of mathematical concepts. The general results showed a qualitative increase with relationship to the students' understanding on the mathematical concepts approached in the intervention. Such results indicate that a methodology using the previous student‟s knowledge and the development of teaching activities, learning in the construtivist theory, make possible an understanding on the part of the students concerning the thematic proposal

Estimação e previsão no processo INARCH(2)

In the last decades the study of integer-valued time series has gained notoriety due to its broad applicability (modeling the number of car accidents in a given highway, or the number of people infected by a virus are two examples). One of the main interests of this area of study is to make forecasts, and for this reason it is very important to propose methods to make such forecasts, which consist of nonnegative integer values, due to the discrete nature of the data. In this work, we focus on the study and proposal of forecasts one, two and h steps ahead for integer-valued second-order autoregressive conditional heteroskedasticity processes [INARCH (2)], and in determining some theoretical properties of this model, such as the ordinary moments of its marginal distribution and the asymptotic distribution of its conditional least squares estimators. In addition, we study, via Monte Carlo simulation, the behavior of the estimators for the parameters of INARCH(2) processes obtained using three di erent methods (Yule- Walker, conditional least squares, and conditional maximum likelihood), in terms of mean squared error, mean absolute error and bias. We present some forecast proposals for INARCH(2) processes, which are compared again via Monte Carlo simulation. As an application of this proposed theory, we model a dataset related to the number of live male births of mothers living at Riachuelo city, in the state of Rio Grande do Norte, Brazil.

Estimação e previsão no processo INARCH(2)

In the last decades the study of integer-valued time series has gained notoriety due to its broad applicability (modeling the number of car accidents in a given highway, or the number of people infected by a virus are two examples). One of the main interests of this area of study is to make forecasts, and for this reason it is very important to propose methods to make such forecasts, which consist of nonnegative integer values, due to the discrete nature of the data. In this work, we focus on the study and proposal of forecasts one, two and h steps ahead for integer-valued second-order autoregressive conditional heteroskedasticity processes [INARCH (2)], and in determining some theoretical properties of this model, such as the ordinary moments of its marginal distribution and the asymptotic distribution of its conditional least squares estimators. In addition, we study, via Monte Carlo simulation, the behavior of the estimators for the parameters of INARCH(2) processes obtained using three di erent methods (Yule- Walker, conditional least squares, and conditional maximum likelihood), in terms of mean squared error, mean absolute error and bias. We present some forecast proposals for INARCH(2) processes, which are compared again via Monte Carlo simulation. As an application of this proposed theory, we model a dataset related to the number of live male births of mothers living at Riachuelo city, in the state of Rio Grande do Norte, Brazil.