Aplicações da teoria da percolação à modelagem e simulação de reservatórios de petróleo

In this thesis we study some problems related to petroleum reservoirs using methods and concepts of Statistical Physics. The thesis could be divided percolation problem in random multifractal support motivated by its potential application in modelling oil reservoirs. We develped an heterogeneous and anisotropic grid that followin two parts. The first one introduce a study of the percolations a random multifractal distribution of its sites. After, we determine the percolation threshold for this grid, the fractal dimension of the percolating cluster and the critical exponents ß and v. In the second part, we propose an alternative systematic of modelling and simulating oil reservoirs. We introduce a statistical model based in a stochastic formulation do Darcy Law. In this model, the distribution of permeabilities is localy equivalent to the basic model of bond percolation

Propriedades críticas de sistemas fora do equilíbrio via simulação Monte Carlo

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Estrutura genética de Chromis multilineata (Guichenot, 1853) (Perciformes Pomacentridae) na costa NE do Brasil e ilhas oceânicas: evidências de um passado evolutivo instável.

The fauna of Brazilian reef fishes comprises approximately 320 species distributed along the coast of the mainland and islands ocean. Little is known about the levels of connectivity between their populations, but has been given the interest in the relations between the offshore and the islands of the Brazil, in a biogeographical perspective. The oceanic islands Brazilian hosting a considerable number of endemic species, which are locally abundant, and divide a substantial portion of its reef fish fauna with the Western Atlantic. Among the richest families of reef fish in species are Pomacentridae. This study analyzed through analysis of sequences of the mitochondrial DNA control region (D-loop), the standards-breeding population of C. Multilineata in different areas of the NE coast of Brazil, involving both oceanic islands (Fernando de Noronha Archipelago and of St. Peter and St. Paul) and continental shelf (RN and BA). To this aim, partial sequences were used in the region HVR1 of mtDNA (312pb). The population structure and parameters for the estimates of genetic variability, molecular variance (AMOVA), estimation of the index for fixing (FST) and number of migrants were determined. The phylogenetic relationships between the populations were estimated using neighbor-joining (NJ) method. A group of Bayesian analysis was used to verify population structure, according to haplotype frequency of each individual. The genetic variability of populations was extremely high. The populations sampled show moderate genetic structure, with a higher degree of genetic divergence being observed for the sample of the Archipelago of St. Peter and St. Paul. At smaller geographical scale, the sample of Rio Grande do Norte and the Archipelago of Fernando de Noronha do not have genetic differentiation. Three moderately differentiated population groups were identified: a population group (I), formed by the Rio Grande do Norte (I') and the archipelago of Fernando de Noronha (I''), and two other different groups formed by the island population of the archipelago of Saint Peter and St. Paul (II) and Bahia (III). The genetic patterns found suggest that the species has suffered a relatively recent radiation favoring the absence of shared haplotypes. C. multilineata seems to constitute a relatively homogenous population along the West Atlantic coast, with evidence of a moderate population genetic structure in relation to the Archipelago of St. Peter and St. Paul. These data supports the importance of the dispersal larvae by marine current and the interpopulation similarity this species.

caracterização in situ e estrutura genética de populações de Gossypium mustelinum

Gossypium mustelinum Miers ex Watt is the only cotton species native from Brazil. It is endemic of the semi-arid region from North-east of the country, where it occur near from resilient water sources. The threats to the in situ conservation of the populations are caused by human interference in its habitat, mainly by excessive cattle graze and deforestation. Establish efficient strategies of in situ conservation depend on the accomplishment of a diagnosis of how the specie is found in its natural environment, and the knowledge about the genetic structure of the populations. The objectives of this work were i) to determine the in situ conditions of two populations present in rivers from basin of Rio Paraguaçu at the Bahia State, ii) to evaluate the structure and genetic variability presented in both populations, iii) to establish in situ and ex situ conservation strategies. It were realized collection in november 2007, when was realized in situ characterization of G. mustelinum. SSR markers were used for analyze 218 genotypes deriving from two populations of the G. mustelinum, localized at Tocó river and the Capivara river. The allelic frequencies, the heterozigosity and the F statics were estimated. All the plants were classified as wild and natives, and there was no evidence of the use the plants or its parts. The populations showed different conservation conditions in situ. Few plantlets were found in sites with excessive cattle feed, an indication that the damages in young plants should be high enough to compromise the renovation of the populations. On the other hand, populations were well preserved when the anthropic damages was low or inexistent. The 14 SSR primer pairs amplified 17 loci with a medium number of 5 alleles per locus (a total of 85 alleles). The high level of endogamy estimated (FIS=0,808) and the low observed heterozygosity (H0=0,093) were indicatives that the populations reproduce mainly by selfing, geitonogamy and crosses between related individuals. The genetic diversity was high (HE=0,482) and the differentiation between the populations was very high (FST=0,328). At least two sites from both populations of G. mustelinum must be preserved to achieve suitable in situ conservation. Actions that preserve the gallery forest and keep the cattle away should implemented, and could be as simple as erecting a fence. It is not possible anticipated if the in situ preservation will be possible. Therefore collections and ex situ preservation of representative specimens are essential to conserve the genetic diversity of native G. mustelinum

Estrutura genética de populações de Amphobotrys ricini, agente causal do mofo cinzento da mamoneira

The gray mold, causal organism Amphobotrys ricini, is one of the major diseases of castor bean. Difficulties in managing plant disease arises form the limited understanding of the genetic structure of A. ricini, their complexity and variability make it difficult to control. Genetic structure can be used to infer the relative impact of different forces that influence the evolution of pathogen populations, that allow to predict the potencial for pathogen populations to envolve in agricultural ecosystems. Growers protect their crop by applying fungicides, but there aren t fungicides to provide significant control of gray mold of castor bean. The objectives of this work were use RAPD to determine the genetic structure of A. ricini subpopulations in Paraíba and assay the sensitivity of A. ricini isolates to azoxystrobin and carbendazim. To determine the genetic structure of A. ricini subpopulations in Paraíba, 23 isolates were colleted from two different geographic location (subpopulation). These isolates were analysed by RAPD using 22 random decamer primers, purchased from OPERON, produced a total of 80 markers polimorphics. The resulting matrixes were analysed using PopGene version 1.32. Sensitivity to azoxystrobin and carbendazim of 30 isolates, colleted form Paraíba and Alagoas, was estimated based on spore germination and colony growth inhibition. The stock solutions were added toV8 medium after sterilization to produce final concentrations of 0, 0.01, 0.1, 1, 10, and 100 µg/ml of carbendazim and 0, 0.001, 0.01, 0.1, 1, and 10 µg/ml of azoxystrobin. All statistical analyses were performed using SAS to estimate the dose that inhibited fungal growth by 50% (ED50 values). The genetic diversity within subpopulations (Hs=0,271) accounted for 92% of the total genetic diversity (Ht=0,293), while genetic diversity between subpopulations (Gst = 0,075) represented only 7,5%. The estimated number of migrants per generation (NM ) was 6,15. Nei s average gene identity across 80 RAPD loci was 0,9468. Individual ED50 values, for the 30 isolates screened for their sensitivity to azoxystrobin, ranged From a maximum of 0,168 µg/ml to a minimum of 0,0036 µg/ml. The ED50 values for carbendazim varied within the range of 0,026 to 0,316 µg/ml

Gestão de estoques: uma proposta de reposição contínua para material médico hospitalar e medicamentos em um hospital universitário federal do estado do Rio Grande do Norte

The inventory management in hospitals is of paramount importance, since the supply materials and drugs interruption can cause irreparable damage to human lives while excess inventories involves immobilization of capital. Hospitals should use techniques of inventory management to perform replenishment in shorter and shorter intervals, in order to reduce inventories and fixed assets and meet citizens requirements properly. The inventory management can be an even bigger problem for public hospitals, which have restrictions on the use of resources and decisionmaking structure more bureaucratized. Currently the University Hospital Onofre Lopes (HUOL) uses a periodic replacement policy for hospital medical supplies and medicines, which involves one moment surplus stock replenishment, the next out of stock items. This study aims to propose a system for continuous replenishment through order point for inventory of medical supplies and medicines to the hospital HUOL. Therefore, a literature review of Federal University Hospitals Management, Logistics, Inventory Management and Replenishment System in Hospitals was performed, emphasizing the demand forecast, classification or ABC curve and order point system. And also, policies of inventory management and the current proposal were described, dealing with profile of the mentioned institution, the current policy of inventory management and simulation for continuous replenishment order point. For the simulation, the sample consisted of 102 and 44 items of medical and hospital drugs, respectively, selected using the ABC classification of inventory, prioritizing items of Class A, which contains the most relevant items in added value, representing 80 % of the financial value in 2012 fiscal year. Considering that it is a public organization, subject to the laws, we performed two simulations: the first, following the signs for inventory management of Instruction No. 205 (IN 205 ), from Secretary of Public Administration of the Presidency ( SEDAP / PR ), and the second, based on the literature specializing in inventory management hospital. The results of two simulations were compared to the current policy of replenishment system. Among these results are: an indication that the system for continuous replenishment reorder point based on IN 205 provides lower levels of safety stock and maximum stock, enables a 17% reduction in the amount spent for the full replenishment of inventories, in other words, decreasing capital assets, as well as reduction in stock quantity, also the simulation made from the literature has indicated parameters that prevent the application of this technique to all items of the sample. Hence, a change in inventory management of HUOL, with the application of the continuous replenishment according to IN 205, provides a significant reduction in acquisition costs of medical and hospital medicine

Modelos de sobrevivência com fração de cura e erro de medida nas covariáveis

In this work, we study the survival cure rate model proposed by Yakovlev et al. (1993), based on a competing risks structure concurring to cause the event of interest, and the approach proposed by Chen et al. (1999), where covariates are introduced to model the risk amount. We focus the measurement error covariates topics, considering the use of corrected score method in order to obtain consistent estimators. A simulation study is done to evaluate the behavior of the estimators obtained by this method for finite samples. The simulation aims to identify not only the impact on the regression coefficients of the covariates measured with error (Mizoi et al. 2007) but also on the coefficients of covariates measured without error. We also verify the adequacy of the piecewise exponential distribution to the cure rate model with measurement error. At the end, model applications involving real data are made

Estrutura do dossel e acúmulo de forragem dos capins piatã e marandu sob pastejo com ovinos

The objective of this scientific work was to evaluate the tillering and mass production of Brachiaria brizantha Piatã and Marandu grasses with two statures of post-grazing. The experimental lineation was in factorial arrangement (2 pastures x 2 residue stature) with subplots (grazing cycle). The experimental period was from March to October of 2012. The target stature on pre-grazing was 50 cm and on post-grazing 15 and 25 for each cultivar. The following variables were analyzed: tiller population density, forage mass, morphological components, accumulation and accumulation rate. Three grazing cycles were obtained. Marandu grass presented larger forage mass on pre-grazing and lower stem production than piatã grass. No difference was observed between the two cultivars regarding the leaf blade production. There was no difference on forage mass, leaf blade, stem, and dead material production between the two statures of post-grazing. The pastures managed at 25 cm presented accumulation rate compared to those with 15 cm. Concerning the accumulation rate on the two cultivars, piatã and marandu grasses, Marandu grass presented higher amount than the piatã grass, and also presented higher values on the rate of basal tiller appearing on 15 cm stature post-pasture feature. Piatã grass managed at 25 cm developed smaller tiller amount on the second generation and greater tiller amount on the third generation than marandu grass. The greater tiller population density was observed on 25cm post-grazing pastures. There was no statistical difference of density between the two cultivars and between the cycles. Accordingly, it is concluded that piatã and marandu cultivars can be managed with 15cm and 25 cm post-grazing statures