79 resultados para Distribuições de probabilidades


Relevância:

10.00% 10.00%

Publicador:

Resumo:

Avaliar os dados de aleitamento materno e alimentação complementar de crianças menores de um ano, do Rio Grande do Norte (RN), de acordo com o que é preconizado pelas políticas e ações de alimentação e nutrição. Métodos: Foi analisado o banco de dados da Chamada Neonatal do RN, pesquisa realizada pelo Ministério da Saúde em 2010. A amostra analisada foi de 837 pares mãe/filho que responderam ao questionário da pesquisa nos municípios investigados. Foram analisadas a prevalência de dados de aleitamento materno exclusivo (AME), na primeira hora de vida, parcial (AMP) e total (AMT), assim como dos alimentos ingeridos, pelas crianças, nas ultimas 24 horas anterior a entrevista. As frequências e médias foram feitas pelo comando Complex samples, no SPSS® 20.0, com IC95%. Foram estimadas as medianas de tempo de AME e AMT, assim como a mediana de tempo de introdução dos grupos de alimentos consumidos, em relação a idade da criança pelo método de probitos. Foi feita associação das probabilidades de tempo de AME e AMT com as variáveis sociodemográficas e de pré-natal (p<0.05). Resultados: Foram encontradas médias de idades de 5,28 ± 3,4 meses e 25,9 ± 6,4 anos, para crianças e mães, respectivamente. A prática de aleitamento na primeira hora de vida foi considerada boa (66,6%) e o percentual de AME (20%) razoável,segundo a Organização Mundial da Saúde, 2008. Mais da metade das crianças (55,1%) estavam em AMP. No total 60% estavam sendo amamentadas (AMT) ao final do primeiro ano de vida. O AME teve mediana de 63 dias e AMT de 358 dias. Estes dados não se diferenciaram muito entre a capital e os municípios do interior. A maioria das mães entrevistadas (73,8%) referiu ter tido orientação sobre aleitamento no pré- natal, tendo associação (p=0,03) com a probabilidade de tempo de AME, porém com pouca explicabilidade (R2= 0,011). Água ou chá, alimentos lácteos, frutas, legumes e verduras foram introduzidos precocemente com medianas menores que 180 dias. O aleitamento tende a diminuir e os alimentos tendem a aumentar o consumo de acordo com a idade da criança, com aumento exponencial do grupo calorias vazias . Conclusões: Conclui-se que mesmo com maioria das crianças amamentadas até um ano de vida, poucas estavam em AME e introduziram alimentos precocemente, não tendo resultado satisfatório frente ao preconizado pelas políticas públicas de alimentação e nutrição

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Este trabalho aborda o problema de otimização em braquiterapia de alta taxa de dose no tratamento de pacientes com câncer, com vistas à definição do conjunto de tempos de parada. A técnica de solução adotada foi a Transgenética Computacional apoiada pelo método L-BFGS. O algoritmo desenvolvido foi empregado para gerar soluções não denominadas cujas distribuições de dose fossem capazes de eiminar o câncer e ao mesmo tempo preservar as regiões normais

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The study of solar neutrinos is very important to a better comprehension of the set of nuclear reactions that occurs inside the Sun and in solar type stars. The ux of neutrinos provides a better comprehension of the stellar structure as a whole. In this dissertation we study the ux of neutrinos in a solar model, addressing the neutrino oscillation, analyzing with the intention of determining and verify the distribution from a statistical point of view, since this ux depends on the particles intrinsic velocity distributions in stellar plasma. The main tool for this analysis was the Toulouse-Geneva Stellar Evolution Code, or TGEC, which allow us to obtain the neutrino ux values per reaction and per layer inside the Sun, allowing us to compare the observational results for the neutrino ux detected on experiments based on Cl37 (Homestake), Ga71 (SAGE, Gallex/GNO) and water (SNO). Our results show the nal distribution for neutrino ux as a function of the depth using the coordinates of mass and radius. The dissertation also shows that the equations for this ux are present in TGEC.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We use a tight-binding formulation to investigate the transmissivity and the currentvoltage (I_V) characteristics of sequences of double-strand DNA molecules. In order to reveal the relevance of the underlying correlations in the nucleotides distribution, we compare theresults for the genomic DNA sequence with those of arti_cial sequences (the long-range correlated Fibonacci and RudinShapiro one) and a random sequence, which is a kind of prototype of a short-range correlated system. The random sequence is presented here with the same _rst neighbors pair correlations of the human DNA sequence. We found that the long-range character of the correlations is important to the transmissivity spectra, although the I_V curves seem to be mostly inuenced by the short-range correlations. We also analyze in this work the electronic and thermal properties along an _-helix sequence obtained from an _3 peptide which has the uni-dimensional sequence (Leu-Glu-Thr- Leu-Ala-Lys-Ala)3. An ab initio quantum chemical calculation procedure is used to obtain the highest occupied molecular orbital (HOMO) as well as their charge transfer integrals, when the _-helix sequence forms two di_erent variants with (the so-called 5Q variant) and without (the 7Q variant) _brous assemblies that can be observed by transmission electron microscopy. The di_erence between the two structures is that the 5Q (7Q) structure have Ala ! Gln substitution at the 5th (7th) position, respectively. We estimate theoretically the density of states as well as the electronic transmission spectra for the peptides using a tight-binding Hamiltonian model together with the Dyson's equation. Besides, we solve the time dependent Schrodinger equation to compute the spread of an initially localized wave-packet. We also compute the localization length in the _nite _-helix segment and the quantum especi_c heat. Keeping in mind that _brous protein can be associated with diseases, the important di_erences observed in the present vi electronic transport studies encourage us to suggest this method as a molecular diagnostic tool

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Considering a quantum gas, the foundations of standard thermostatistics are investigated in the context of non-Gaussian statistical mechanics introduced by Tsallis and Kaniadakis. The new formalism is based on the following generalizations: i) Maxwell- Boltzmann-Gibbs entropy and ii) deduction of H-theorem. Based on this investigation, we calculate a new entropy using a generalization of combinatorial analysis based on two different methods of counting. The basic ingredients used in the H-theorem were: a generalized quantum entropy and a generalization of collisional term of Boltzmann equation. The power law distributions are parameterized by parameters q;, measuring the degree of non-Gaussianity of quantum gas. In the limit q

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We considered prediction techniques based on models of accelerated failure time with random e ects for correlated survival data. Besides the bayesian approach through empirical Bayes estimator, we also discussed about the use of a classical predictor, the Empirical Best Linear Unbiased Predictor (EBLUP). In order to illustrate the use of these predictors, we considered applications on a real data set coming from the oil industry. More speci - cally, the data set involves the mean time between failure of petroleum-well equipments of the Bacia Potiguar. The goal of this study is to predict the risk/probability of failure in order to help a preventive maintenance program. The results show that both methods are suitable to predict future failures, providing good decisions in relation to employment and economy of resources for preventive maintenance.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

In survival analysis, the response is usually the time until the occurrence of an event of interest, called failure time. The main characteristic of survival data is the presence of censoring which is a partial observation of response. Associated with this information, some models occupy an important position by properly fit several practical situations, among which we can mention the Weibull model. Marshall-Olkin extended form distributions other a basic generalization that enables greater exibility in adjusting lifetime data. This paper presents a simulation study that compares the gradient test and the likelihood ratio test using the Marshall-Olkin extended form Weibull distribution. As a result, there is only a small advantage for the likelihood ratio test

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Relevância:

10.00% 10.00%

Publicador:

Resumo:

We present a dependent risk model to describe the surplus of an insurance portfolio, based on the article "A ruin model with dependence between claim sizes and claim intervals"(Albrecher and Boxma [1]). An exact expression for the Laplace transform of the survival function of the surplus is derived. The results obtained are illustrated by several numerical examples and the case when we ignore the dependence structure present in the model is investigated. For the phase type claim sizes, we study by the survival probability, considering this is a class of distributions computationally tractable and more general

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The central objective of a study Non-Homogeneous Markov Chains is the concept of weak and strong ergodicity. A chain is weak ergodic if the dependence on the initial distribution vanishes with time, and it is strong ergodic if it is weak ergodic and converges in distribution. Most theoretical results on strong ergodicity assume some knowledge of the limit behavior of the stationary distributions. In this work, we collect some general results on weak and strong ergodicity for chains with space enumerable states, and also study the asymptotic behavior of the stationary distributions of a particular type of Markov Chains with finite state space, called Markov Chains with Rare Transitions

Relevância:

10.00% 10.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Relevância:

10.00% 10.00%

Publicador:

Resumo:

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

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The study of mortality by various differentials has been an important tool to guide public health policies, due to better describing the events of deaths in a population. This research aims to seek disparities in mortality according to educational level, sex and adulthood in large Brazilian regions and consequently for Brazil as a whole. A vast literature has shown that people with more education tend to have lower risk of death. Studies on inequalities in mortality by level of education in Brazil are still very specific and has still known very little about Brazil about mortality according to educational level, due to lack of information about the well-filled school in the records of deaths arising from the Mortality Information System (MIS) of the Ministry of Health. This data source has shown improvement in the coverage of sub reports in the last decade, however, it has still perceived negligence in completing the question regarding schooling of death (about 30% of registered deaths in 2010 to Brazil, Given this scenario, this work contributes to the national literature on the behavior of adult mortality differentials having as proposed, using data from the new variable mortality of the 2010 Census (CD 2010), assuming the characteristics of education of the head the household for deaths occurring in the same. It is therefore considered that the probability of mortality is homogeneous within the household. Events of deaths were corrected only for the records come from households where the head possessed levels of schooling and Instruction Elementary Education No Incomplete and Primary Education and Secondary Education Complete Incomplete through the Generations Extinct Adjusted method. With deaths already corrected, probabilities of death were calculated between 15 and 60 years life, as well as tables by sex and level of education to all regions of Brazil. No que se refere às probabilidades de morte por idade, nas idades entre 15 e 60 anos as maiores probabilidades seguem um gradiente, maior probabilidade para os menos escolarizados. Results corroborate the literature, the more educated the population is, the greater the life expectancy. In all Brazilian regions, life expectancy of the female population is greater than that of men at all levels of schooling. With respect to probabilities of death by age between the ages of 15 and 60 years the most likely follow a gradient, most likely to the least educated. At older ages (from 70 years), this behavior has presented another pattern, the lowest level of education has the lowest odds in the regions, North, Northeast, South and Midwest, except in the Southeast region

Relevância:

10.00% 10.00%

Publicador:

Resumo:

When searching for food, animals often make decisions of where to go, how long to stay in a foraging area and whether or not to return to the last visited spot. These decisions can be enhanced by cognitive traits and adjusted based on previous experience. In social insects such as ants, foraging efficiency have an impact on both individual and colony level. The present study investigated, in the laboratory, the effect of distance from food, capture success and food size, and reward rate on decisions of where to forage in Dinoponera quadriceps, a ponerine ant that forage solitarily and individually make their foraging decisions. We also investigated the influence of learning on the performance of workers over successive trips searching for food by measuring the patch residence time in each foraging trip. Four scenarios were created differing in food reward rates, food size offered and distances colony-food site. Our work has shown that as a rule-of-thumb, workers of D. quadriceps return to the place where a prey item was found on the previous trip, regardless of distance, food size and reward rate. When ants did not capture preys, they were more likely to change path to search for food. However, in one of the scenarios, this decision to switch paths when unsuccessful was less evident, possibly due to the greater variation of possible outcomes ants could experience in this scenario and cognitive constraints of D. quadriceps to predict variations of food distribution. Our results also indicated a learning process of routes of exploration as well as the food site conditions for exploration. After repeated trips, foragers reduced the patch residence time in areas that they did not capture food and quickly changed of foraging area, increasing their foraging efficiency.

Relevância:

10.00% 10.00%

Publicador:

Resumo:

The discovery of giant stars in the spectral regions G and K, showing moderate to rapid rotation and single behavior, namely with constant radial velocity, represents one important topic of study in Stellar Astrophysics. Indeed, such anomalous rotation clearly violates the theoretical predictions on the evolution of stellar rotation, since in evolved evolutionary stages is expected that the single stars essentially have low rotation due to the evolutionary expansion. This property is well-established from the observational point of view, with different studies showing that for single giant stars of spectral types G and K values of the rotation are typically smaller than 5kms−1 . This Thesis seeks an effective contribution to solving the paradigm described above, aiming to search for single stars of spectral types G and K with anomalous rotation, tipically rotation of moderate to rapid, in other luminosity classes. In this context, we analyzed a large stellar sample consisting of 2010 apparently single stars of luminosity classes IV, III, II and Ib with spectral types G and K, with rotational velocity v sin i and radial velocity measurements obtained from observations made by CORAVEL spectrometers. As a first result of impact we discovered the presence of anomalous rotators also among subgiants, bright giants and supergiants stars, namelly stars of luminosity classes IV, II and Ib, in contrast to previous studies, that reported anomalous rotators only in the luminosity class III classic giants. Such a finding of great significance because it allows us to analyze the presence of anomalous rotation at different intervals of mass, since the luminosity classes considered here cover a mass range between 0.80 and 20MJ, approximately. In the present survey we discovered 1 subgiant, 9 giants, 2 bright giants and 5 Ib supergiants, in spectral regions G and K, with values of v sin i ≥ 10kms−1 and single behavior. This amount of 17 stars corresponds to a frequency of 0.8% of G and K single evolved stars with anomalous rotation in the mentioned classes of luminosities, listed at the Bright Star Catalog, which is complete to visual magnitude 6.3. Given these new findings, based on a stellar sample complete in visual magnitude, as that of the Bright Star Catalog, we conducted a comparative statistical analysis using the Kolmogorov- Smirnov test, from where we conclude that the distributions of rotational velocity, v sin i, for single evolved stars with anomalous rotation in luminosity classes III and II, are similar to the distributions of v sin i for spectroscopic binary systems with evolved components with the same spectral type and luminosity class. This vii result indicates that the process of coalescence between stars of a binary system might be a possible mechanism to explain the observed abnormal rotation in the referred abnormal rotators, at least among the giants and bright giants, where the rotation in excess would be associated with the transfer of angular momentum for the star resulting from the merger. Another important result of this Thesis concerns the behavior of the infrared emission in most of the stars with anomalous rotation here studied, where 14 stars of the sample tend to have an excess in IR compared with single stars with low rotation, within of their luminosity class. This property represents an additional link in the search for the physical mechanisms responsible for the abnormal observed rotation, since recent theoretical studies show that the accretion of objects of sub-stellar mass, such as brown dwarfs and giant planets, by the hosting star, can significantly raise its rotation, producing also a circumstellar dust disk. This last result seems to point in that direction, since it is not expected that dust disks occurring during the stage of star formation can survive until the stages of subgiants, giants and supergiants Ib. In summary, in this Thesis, besides the discovery of single G and K evolved stars of luminosity classes IV, II and Ib with anomalously high rotation compared to what is predicted by stellar evolution theory, we also present the frequency of these abnormal rotators in a stellar sample complete to visual magnitude 6.3. We also present solid evidence that coalescence processes in stellar binary systems and processes of accretion of brown dwarfs star or giant planets, by the hosting stars, can act as mechanisms responsible for the puzzling phenomenon of anomalous rotation in single evolved stars.