998 resultados para Distribuição teórica de probabilidades
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A hanseníase no Brasil ainda é um problema a ser equacionado e, no Estado de São Paulo, há varias regiões com altas taxas de detecção. O presente estudo objetivou analisar a distribuição e quantificar a dependência espacial das taxas médias de detecção da hanseníase no Estado de São Paulo, no período de 1991-2002, empregando técnicas geoestatísticas. Verificou-se tendência levemente decrescente das taxas médias de detecção para o Estado de São Paulo. Altos índices do indicador podem ser visualizados nas regiões oeste e noroeste de São Paulo. A dependência espacial encontrada foi de aproximadamente 30 km. Com os resultados encontrados, conclui-se que a análise de superfície das taxas médias de detecção pode auxiliar na escolha de áreas prioritárias visando aos exames de coletividade e ao incremento dos exames nos contatos dos casos detectados.
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The following work is to interpret and analyze the problem of induction under a vision founded on set theory and probability theory as a basis for solution of its negative philosophical implications related to the systems of inductive logic in general. Due to the importance of the problem and the relatively recent developments in these fields of knowledge (early 20th century), as well as the visible relations between them and the process of inductive inference, it has been opened a field of relatively unexplored and promising possibilities. The key point of the study consists in modeling the information acquisition process using concepts of set theory, followed by a treatment using probability theory. Throughout the study it was identified as a major obstacle to the probabilistic justification, both: the problem of defining the concept of probability and that of rationality, as well as the subtle connection between the two. This finding called for a greater care in choosing the criterion of rationality to be considered in order to facilitate the treatment of the problem through such specific situations, but without losing their original characteristics so that the conclusions can be extended to classic cases such as the question about the continuity of the sunrise
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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
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In the present work we use a Tsallis maximum entropy distribution law to fit the observations of projected rotational velocity measurements of stars in the Pleiades open cluster. This new distribution funtion which generalizes the Ma.xwel1-Boltzmann one is derived from the non-extensivity of the Boltzmann-Gibbs entropy. We also present a oomparison between results from the generalized distribution and the Ma.xwellia.n law, and show that the generalized distribution fits more closely the observational data. In addition, we present a oomparison between the q values of the generalized distribution determined for the V sin i distribution of the main sequence stars (Pleiades) and ones found for the observed distribution of evolved stars (subgiants). We then observe a correlation between the q values and the star evolution stage for a certain range of stel1ar mass
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Ising and m-vector spin-glass models are studied, in the limit of infinite-range in-teractions, through the replica method. First, the m-vector spin glass, in the presence of an external uniform magnetic field, as well as of uniaxial anisotropy fields, is consi-dered. The effects of the anisotropics on the phase diagrams, and in particular, on the Gabay-Toulouse line, which signals the transverse spin-glass ordering, are investigated. The changes in the Gabay-Toulouse line, due to the presence of anisotropy fields which favor spin orientations along the Cartesian axes (m = 2: planar anisotropy; m = 3: cubic anisotropy), are also studied. The antiferromagnetic Ising spin glass, in the presence of uniform and Gaussian random magnetic fields, is investigated through a two-sublattice generalization of the Sherrington-Kirpaktrick model. The effects of the magnetic-field randomness on the phase diagrams of the model are analysed. Some confrontations of the present results with experimental observations available in the literature are discussed
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In this work we have studied the effects of random biquadratic and random fields in spin-glass models using the replica method. The effect of a random biquadratic coupling was studied in two spin-1 spin-glass models: in one case the interactions occur between pairs of spins, whereas in the second one the interactions occur between p spins and the limit p > oo is considered. Both couplings (spin glass and biquadratic) have zero-mean Gaussian probability distributions. In the first model, the replica-symmetric assumption reveals that the system presents two pha¬ses, namely, paramagnetic and spin-glass, separated by a continuous transition line. The stability analysis of the replica-symmetric solution yields, besides the usual instability associated with the spin-glass ordering, a new phase due to the random biquadratic cou¬plings between the spins. For the case p oo, the replica-symmetric assumption yields again only two phases, namely, paramagnetic and quadrupolar. In both these phases the spin-glass parameter is zero. Besides, it is shown that they are stable under the Almeida-Thouless stability analysis. One of them presents negative entropy at low temperatures. We developed one step of replica simmetry breaking and noticed that a new phase, the biquadratic glass phase, emerge. In this way we have obtained the correct phase diagram, with.three first-order transition lines. These lines merges in a common triple point. The effects of random fields were studied in the Sherrington-Kirkpatrick model consi¬dered in the presence of an external random magnetic field following a trimodal distribu¬tion {P{hi) = p+S(hi - h0) +Po${hi) +pS(hi + h0))- It is shown that the border of the ferromagnetic phase may present, for conveniently chosen values of p0 and hQ, first-order phase transitions, as well as tricritical points at finite temperatures. It is verified that the first-order phase transitions are directly related to the dilution in the fields: the extensions of these transitions are reduced for increasing values of po- In fact, the threshold value pg, above which all phase transitions are continuous, is calculated analytically. The stability analysis of the replica-symmetric solution is performed and the regions of validity of such a solution are identified
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Conselho Nacional de Desenvolvimento Científico e Tecnológico
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INTRODUCTION: Cardiac and pulmonary manifestations of the Chagas disease (CD) affect between 20-30% of the infected subjects. The chronic Chagas cardiomyopathy (CCC) has some peculiarities such as arrhythmias and, especially heart failure (HF) and is potentially lethal due to left ventricular dysfunction. How respiratory disorders, patients get progressive loss of functional capacity, which contributes to a poor quality of life related to disease. Measurements of lung volume by the movement of the chest wall surface are an alternative evaluation of lung function and kinematics of complex thoracoabdominal for these patients. OBJECTIVE: evaluate the kinematics of the thoracoabdominal complex through the regional pulmonary volumes and to correlate with functional evaluation of the cardiorrespiratory system in patients with Chagas disease at rest. MATERIALS AND METHODS: a cross-section study with 42 subjects had been divided in 3 groups, 15 composed for patients with CCC, 12 patients with HF of different etiologies and 15 healthful presented control group. An optoelectronic plethysmography (POE), Minnesota questionnaire, six minute walk test, spirometer and manovacuometer was used. RESULTS: It was observed in the 6MWT where group CRL presented greater distance 464,93±44,63m versus Group HF with 399,58± 32,1m (p=0,005) and group CCC 404±68,24m (p=0,015), both the groups presented difference statistics with regard to Group CRL. In the manovacuometer 54,59±19,98; of the group CCC and 42,11±13,52 of group IC found group CRL presented 81,31±15,25 of the predicted versus, presenting in relation to group CRL. In the POE it observed a major contribution in abdominal compartment in patients with IC if compared like CCC and control groups. On the basis of the questionnaire of quality of life of Minessota, verified a low one groups CCC and IC 43,2±15,2 and 44,4±13,1, respectively (p<0,05) when compared with the control group (19,6±17,31). CONCLUSION: it seems that the patients with CCC possess same functional and respiratory characteristics, observed for the POE, 6MWT, manovacuometer and spirometer to the patients of group HF, being able to consider similar interventions for this complementary group as therapeutical of this neglected disease
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Universidade Federal do Rio Grande do Norte
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The work is to make a brief discussion of methods to estimate the parameters of the Generalized Pareto distribution (GPD). Being addressed the following techniques: Moments (moments), Maximum Likelihood (MLE), Biased Probability Weighted Moments (PWMB), Unbiased Probability Weighted Moments (PWMU), Mean Power Density Divergence (MDPD), Median (MED), Pickands (PICKANDS), Maximum Penalized Likelihood (MPLE), Maximum Goodness-of-fit (MGF) and the Maximum Entropy (POME) technique, the focus of this manuscript. By way of illustration adjustments were made for the Generalized Pareto distribution, for a sequence of earthquakes intraplacas which occurred in the city of João Câmara in the northeastern region of Brazil, which was monitored continuously for two years (1987 and 1988). It was found that the MLE and POME were the most efficient methods, giving them basically mean squared errors. Based on the threshold of 1.5 degrees was estimated the seismic risk for the city, and estimated the level of return to earthquakes of intensity 1.5°, 2.0°, 2.5°, 3.0° and the most intense earthquake never registered in the city, which occurred in November 1986 with magnitude of about 5.2º
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Autism comprises a heterogeneous group of neurodevelopmental disorders that affects the brain maturation and produces sensorial, motor, language and social interaction deficits in early childhood. Several studies have shown a major involvement of genetic factors leading to a predisposition to autism, which are possibly affected by environmental modulators during embryonic and post-natal life. Recent studies in animal models indicate that alterations in epigenetic control during development can generate neuronal maturation disturbances and produce a hyper-excitable circuit, resulting in typical symptoms of autism. In the animal model of autism induced by valproic acid (VPA) during rat pregnancy, behavioral, electrophysiological and cellular alterations have been reported which can also be observed in patients with autism. However, only a few studies have correlated behavioral alterations with the supposed neuronal hyper-excitability in this model. The aim of this project was to generate an animal model of autism by pre-natal exposure to VPA and evaluate the early post-natal development and pre-puberal (PND30) behavior in the offspring. Furthermore, we quantified the parvalbumin-positive neuronal distribution in the medial prefrontal cortex and Purkinje cells in the cerebellum of VPA animals. Our results show that VPA treatment induced developmental alterations, which were observed in behavioral changes as compared to vehicle-treated controls. VPA animals showed clear behavioral abnormalities such as hyperlocomotion, prolonged stereotipies and reduced social interaction with an unfamiliar mate. Cellular quantification revealed a decrease in the number of parvalbumin-positive interneurons in the anterior cingulate cortex and in the prelimbic cortex of the mPFC, suggesting an excitatory/inhibitory unbalance in this animal model of autism. Moreover, we also observed that the neuronal reduction occurred mainly in the cortical layers II/III and V/VI. We did not detect any change in the density of Purkinje neurons in the Crus I region of the cerebellar cortex. Together, our results strengthens the face validity of the VPA model in rats and shed light on specific changes in the inhibitory circuitry of the prefrontal cortex in this autism model. Further studies should address the challenges to clarify particular electrophysiological correlates of the cellular alterations in order to better understand the behavioral dysfunctions
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The knowledge of Anastrepha zenildae behavioral aspects combined with the biology of Tephritidae may contribute to monitoring and control programs of this fruit fly that is considered as economically important to the Rio Grande do Norte state. In order to characterize the daily activity profile of this species, we studied the behaviors of resting, locomotion, feeding, cleaning, courtship, copulation and oviposition of animals submitted to an artificial 12:12h light-dark cycle (750:1lux) with controlled temperature (26±2 °C). The observations were made with groups of 16 males and 16 females during 3 consecutive days each generation from parental to F5. Resting, locomotion, feeding and cleaning data were recorded as frequency and time of occurrence by scanning technique in 15 minutes windows per hour, with a record each minute. Courtship, copulation and oviposition were recorded as frequency, time of occurrence and duration by al occurrences technique. Resting was the most frequent behavior with males resting more than females. Locomotion was more evident in the first half of the ligh phase with higher values in females. Cleaning and feeding behaviors were more frequent in the second half of the light phase for both sexes with females eating more frequently than males. During the courtship, males were grouped in lek formations showing wings vibration and pheromone liberation. Courtship occurred more frequently 4 to 7 h after lights on (81,9%) with copulations being more frequent 6 h after lights on with a mean duration of 58,1±40,4 min. Copulation attempts were observed in males inside and outside the lek with aggressive behavior being observed only between males in the lek. Oviposition behavior was similar to that described for other species of the genus with a peak of this activity 2-3 h after the lights on, mean duration of 43, 7±34, 8 sec and 2 to 5 eggs by event. According to the results, sexual behavior of A. zenildae is temporally different of other sympatric species of the genus, being favorable to the reproductive isolation as well as the use of resources as oviposition substrate.
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Lemon sharks, Negaprion brevirostris, are common in the Fernando de Noronha Archipelago, but detailed information about the species in this site is lacking. The aim of this study was to describe the spatial distribution, grouping behavior, habitat use and behavioral ecology of juvenile lemon sharks in the archipelago, and their interaction with some environmental and ecological factors. During 2006 and 2007, the presence and spatial distribution of juvenile sharks were quantified through scuba diving and snorkeling at several sites of the archipelago. In 2008 the habitat use of juvenile sharks was quantified through visual census while snorkeling along 300 x 8 m strip transects. During these transects the grouping behavior of lemon sharks was quantified by ad libitum. Results indicate that Fernando de Noronha Archipelago is used as a nursery area for lemon sharks, and the parturition occurs from November to April. Juveniles preferred using shallower areas available by the tide variation and formed groups only in the presence of adult conspecifics. This preference for shallower habitats and the group behavior probably are anti-predatory tactics used by juvenile lemon sharks, in response to the low availability of shelter and high predation risk of the studied areas. Quantifications of prey availability and predation risk of juveniles showed that, in general, lemon sharks are trading-off food by security and investing in sites with higher possibility of energetic return. Behavioral observations enabled to record juvenile carangid fishes following juvenile lemon sharks, remora host-parasite and juvenile sharks foraging on schools of herrings and octopuses. We also recorded the behavior of juvenile sharks following conspecifics of similar size, circling with two or three individuals and smaller individuals giving way to larger juveniles. When adults are present, juvenile lemon sharks are more social than solitary, indicating that predation is one of the factors that contribute to social behaviors of the species. Results also suggest that when grouped the juveniles have a hierarchical organization according to body size. Furthermore, observation of large adult females with several fresh mating bites and scars in the same habitats used by juvenile lemon sharks, indicates that Fernando de Noronha Archipelago is used as nursery and mating grounds by this species
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Cortical interneurons are characterized by their distinct morphological, physiological and biochemical properties, acting as modulators of the excitatory activity by pyramidal neurons, for example. Various studies have revealed differences in both distribution and density of this cell group throughout distinct cortical areas in several species. A particular class of interneuron closely related to cortical modulation is revealed by the immunohistochemistry for calcium binding proteins calbindin (CB), calretinina (CR) and parvalbumin (PV). Despite the growing amount of studies focusing on calcium binding proteins, the prefrontal cortex of primates remains relatively little explored, particularly in what concerns a better understanding of the organization of the inhibitory circuitry across its subdivisions. In the present study we characterized the morphology and distribution of neurons rich in calcium-binding proteins in the medial, orbital and dorsolateral areas of the prefrontal cortex of the marmoset (Callithrix jacchus). Using both morphometric and stereological techniques, we found that CR-reactive neurons (mainly double bouquet and bipolar cells) have a more complex dendritic arborization than CB-reactive (bitufted and basket cells) and PV-reactive neurons (chandelier cells). The neuronal densities of CR- and CB-reactive cells are higher in the supragranular layers (II/III) whilst PV-reactive neurons, conversely, are more concentrated in the infragranular layers (V/VI). CR-reactive neurons were the predominant group in the three regions evaluated, being most prevalent in dorsomedial region. Our findings point out to fundamental differences in the inhibitory circuitry of the different areas of the prefrontal cortex in marmoset
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The temporal allocation of the active phase in relation to light and dark cycle (LD) changes during puberty in humans, degus, rats and rhesus. In marmosets, the animal model used in several biomedical researches, there is evidence of a delay at the beginning of the active phase and an increase in total daily activity after onset of puberty. However, as this aspect was evaluated in animals maintained in natural environmental conditions, it was not possible to distinguish between the effects of puberty and of seasonality. Furthermore, as motor activity is the result of different behaviors in this species, it is also important to characterize the diurnal distribution of other behaviors in juvenile stage. With the aim of characterizing the circadian rhythm of motor activity and the diurnal profile of affiliative behavior in marmosets, the motor activity of 5 dyads juveniles between 4 and 12 months of age and their parents was recorded continuously for actímetro. The families were maintained under artificial LD 12:12 h, constant temperature and humidity. The duration of grooming behavior, proximity and social play among juveniles was recorded 2 times a week in sessions of 15 minutes each hour of the active phase. Afetr onset of puberty in juvenile, it was observed that there was no change in the parameters of circadian motor activity rhythm which were common to most animals. Despite the absence of pubertal modulation, it was observed that the circadian activity profiles have stronger synchrony between individuals of the same family than that of different families, which may indicate that the circadian activity rhythm was modulated by the dynamics of social interactions. In relation to age, the total daily activity and the ratio between evening and morning activity (EA/MA) were higher in juveniles than in adults, which may be associated with differences in the circadian timing system between age groups. Furthermore, the onset of the 10 consecutive hours of higher activity (M10) occurred earlier in adult males than in other members of the group, probably as a way to avoid competition for resources in one of the first activities of the day that is foraging. During the juvenile stage, there was an increase in total daily activity that may be associated with increased motor ability of juveniles. In addition to the circadian activity rhythm, the daytime profile of proximity and social play behaviors was similar between the 5th and 12th month of life of juveniles, in which the interval between 7- 10 h in the morning showed the highest values of proximity and lower values of play social. Moreover, the duration of the grooming showed a similar distribution to adults from the 8th month, wherein the higher values occurring at the interval between 11 14 h of day. Considering the results, the parameters of the circadian activity rhythm had a greater influence of social factors than puberty. In relation to age, there were no changes related to the allocation of the active phase in relation to the LD cycle, but total daily activity, the ratio AV/AM and the start of the M10 is possible to observe differences between juveniles and adults