Essays in heterogeneous agent macroeconomics

This thesis is comprised of three chapters. The first article studies the determinants of the labor force participation of elderly American males and investigates the factors that may account for the changes in retirement between 1950 and 2000. We develop a life-cycle general equilibrium model with endogenous retirement that embeds Social Security legislation and Medicare. Individuals are ex ante heterogeneous with respect to their preferences for leisure and face uncertainty about labor productivity, health status and out-of-pocket medical expenses. The model is calibrated to the U.S. economy in 2000 and is able to reproduce very closely the retirement behavior of the American population. It reproduces the peaks in the distribution of Social Security applications at ages 62 and 65 and the observed facts that low earners and unhealthy individuals retire earlier. It also matches very closely the increase in retirement from 1950 to 2000. Changes in Social Security policy - which became much more generous - and the introduction of Medicare account for most of the expansion of retirement. In contrast, the isolated impact of the increase in longevity was a delaying of retirement. In the second article, I develop an overlapping generations model of criminal behavior, which extends prior research on crime by taking into account individuals' labor supply decisions and the stigma effect that affects convicted offenders, lowering their likelihood of employment. I use the model to guide a quantitative assessment of the determinants of crime and of a counterfactual experiment in which an income redistribution policy is thought as an alternative to greater law enforcement. The model economy considered in this paper is populated by heterogeneous agents who live for a realistic number of periods, have preferences over consumption and leisure, and differ in terms of their age, their skills as well as their employment shocks. In addition, savings may be precautionary and allow partial insurance against the labor income shocks. Because of the lack of full insurance, this model generates an endogenous distribution of wealth across consumers, enabling us to assess the welfare implications of the redistribution policy experiment. I calibrated the model using the US data for 1980 and then use the model to investigate the changes in criminality between 1980 and 1996. The main results that come out of this study are: 1) Law enforcement policy was the most important factor behind the fall in criminality in the period, while the increase in inequality was the most important single factor promoting crime; 2) Stigmatization is not a free-cost crime control policy; 3) Income redistribution can be a powerful alternative policy to fight crime. Finally, the third article studies the impact of HIV/AIDS on per capita income and education. It explores two channels from HIV/AIDS to income that have not been sufficiently stressed by the literature: the reduction of the incentives to study due to shorter expected longevity and the reduction of productivity of experienced workers. In the model individuals live for three periods, may get infected in the second period and with some probability die of Aids before reaching the third period of their life. Parents care for the welfare of the future generations so that they will maximize lifetime utility of their dynasty. The simulations predict that the most affected countries in Sub-Saharan Africa will be in the future, on average, thirty percent poorer than they would be without AIDS. Schooling will decline in some cases by forty percent. These figures are dramatically reduced with widespread medical treatment, as it increases the survival probability and productivity of infected individuals.

Bank networks and firm credit: an agent based model approach

Starting from the idea that economic systems fall into complexity theory, where its many agents interact with each other without a central control and that these interactions are able to change the future behavior of the agents and the entire system, similar to a chaotic system we increase the model of Russo et al. (2014) to carry out three experiments focusing on the interaction between Banks and Firms in an artificial economy. The first experiment is relative to Relationship Banking where, according to the literature, the interaction over time between Banks and Firms are able to produce mutual benefits, mainly due to reduction of the information asymmetry between them. The following experiment is related to information heterogeneity in the credit market, where the larger the bank, the higher their visibility in the credit market, increasing the number of consult for new loans. Finally, the third experiment is about the effects on the credit market of the heterogeneity of prices that Firms faces in the goods market.

Contagion in financial networks: a network theory and agent-based approaches to modeling the spread of risk in financial systems

Esta dissertação estuda a propagação de crises sobre o sistema financeiro. Mais especi- ficamente, busca-se desenvolver modelos que permitam simular como um determinado choque econômico atinge determinados agentes do sistema financeiro e apartir dele se propagam, transformando-se em um problema sistêmico. A dissertação é dividida em dois capítulos,além da introdução. O primeiro capítulo desenvolve um modelo de propa- gação de crises em fundos de investimento baseado em ciência das redes.Combinando dois modelos de propagação em redes financeiras, um simulando a propagação de perdas em redes bipartites de ativos e agentes financeiros e o outro simulando a propagação de perdas em uma rede de investimentos diretos em quotas de outros agentes, desenvolve-se um algoritmo para simular a propagação de perdas através de ambos os mecanismos e utiliza-se este algoritmo para simular uma crise no mercado brasileiro de fundos de investimento. No capítulo 2,desenvolve-se um modelo de simulação baseado em agentes, com agentes financeiros, para simular propagação de um choque que afeta o mercado de operações compromissadas.Criamos também um mercado artificial composto por bancos, hedge funds e fundos de curto prazo e simulamos a propagação de um choque de liquidez sobre um ativo de risco securitizando utilizado para colateralizar operações compromissadas dos bancos.

Adição de superplastificante e anti-segregante à base de CMC em pastas de cimento para Poços de Petróleo

Oil well cementing materials consist of slurries of Special class Portland cement dispersed in water. Admixtures can be used to provide the necessary fluidity, so the material can be efficiently pumped down as well as penetrate porous rocks with controlled filter loss. Construction admixtures can be used to modify the properties of oil well cements provided they can withstand and hold their properties at the higher than ambient temperatures usually encountered in oil fields. In civil construction, superplasticizer play the role of dispersants that reduce the facto r of water cement improve mechanical properties and fluidity of the cement, whereas anti-segregation agents improve the workability of the slurry. In the present study, oil well cement slurries were produced adding both a dispersant and an anti-segregation agent conventionally used in Portland CPII-Z-32 RS cement aiming at materials for primary cementing and squeeze operations. Three basic aspects were evaluated: fluidity, filter loss and the synergetic effect of the admixtures at two temperatures, i.e., 27°C and 56°C, following API RP 10B practical recommendations. The slurries were prepared using admixture concentrations varying from 2.60 Kgf/m3 (0.02 gallft3) to 5.82 Kgf/m3 (0.045 galJft3) BWOC. The density of the slurries was set to 1.89 g/cm3 (15.8 Ib/gal). 0.30 to 0.60% BWOC of a CMC-based anti-segregation agent was added to the cement to control the filter loss. The results showed that the addition of anti-segregation at concentrations above 0.55% by weight of cement resulted in the increased viscosity of the folders in temperatures evaluated. The increasing the temperature of the tests led to a reduction in the performance of anti-segregation. At concentrations of 5.20 kgf/m3 (0,040 gallft3) and 5.82 Kgf/m3 (0,045 gal/ft 3) observed a better performance of the properties evaluated in the proposed system. At low temperature was observed instability in the readings of rheology for all concentrations of anti-segregation. Contents that increasing the concentration of anti¬-segregation is limited concentrations greater than 0.55 % BWOC of the CMC in temperature analyzed. The use of the system with CMC promoted a good performance against the properties evaluated. The principal function of anti¬-segregation was optimized with increasing concentration of superplasticizer, at temperatures above the 2rC. The study of the behaviour of systemic additives, resulting in slurries of cement, which can be optimized face studies of other intrinsic properties in oil fields

Processamento e caracterização da blenda poli (metacrilato de metila) (PMMA) elastomerico e poli (tereftalato de etileno) (PET) pós-consumo

This work studied the immiscible blend of elastomeric poly(methyl methacrylate) (PMMA) with poly(ethylene terephthalate) (PET) bottle grade with and without the use of compatibilizer agent, poly(methyl methacrylate-co-glycidyl methacrylate - co-ethyl acrylate) (MGE). The characterizations of torque rheometry, melt flow index measurement (MFI), measuring the density and the degree of cristallinity by pycnometry, tensile testing, method of work essential fracture (EWF), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) were performed in pure polymer and blends PMMA/PET. The rheological results showed evidence of signs of chemical reaction between the epoxy group MGE with the end groups of the PET chains and also to the elastomeric phase of PMMA. The increase in the concentration of PET reduced torque and adding MGE increased the torque of the blend of PMMA/PET. The results of the MFI also show that elastomeric PMMA showed lower flow and thus higher viscosity than PET. In the results of picnometry observed that increasing the percentage of PET resulted in an increase in density and degree crystallinity of the blends PMMA/PET. The tensile test showed that increasing the percentage of PET resulted in an increase in ultimate strength and elastic modulus and decrease in elongation at break. However, in the phase inversion, where the blend showed evidence of a co-continuous morphology and also, with 30% PET dispersed phase and compatibilized with 5% MGE, there were significant results elongation at break compared to elastomeric PMMA. The applicability of the method of essential work of fracture was shown to be possible for most formulations. And it was observed that with increasing elastomeric PMMA in the formulations of the blends there was an improvement in specific amounts of essential work of fracture (We) and a decrease in the values of specific non-essential work of fracture (βWp)

Análise comparativa entre simuladores de linha de fluxo e diferenças finitas para um reservatório de petróleo submetido a injeção de água

Water injection is the most widely used method for supplementary recovery in many oil fields due to various reasons, like the fact that water is an effective displacing agent of low viscosity oils, the water injection projects are relatively simple to establish and the water availability at a relatively low cost. For design of water injection projects is necessary to do reservoir studies in order to define the various parameters needed to increase the effectiveness of the method. For this kind of study can be used several mathematical models classified into two general categories: analytical or numerical. The present work aims to do a comparative analysis between the results presented by flow lines simulator and conventional finite differences simulator; both types of simulators are based on numerical methods designed to model light oil reservoirs subjected to water injection. Therefore, it was defined two reservoir models: the first one was a heterogeneous model whose petrophysical properties vary along the reservoir and the other one was created using average petrophysical properties obtained from the first model. Comparisons were done considering that the results of these two models were always in the same operational conditions. Then some rock and fluid parameters have been changed in both models and again the results were compared. From the factorial design, that was done to study the sensitivity analysis of reservoir parameters, a few cases were chosen to study the role of water injection rate and the vertical position of wells perforations in production forecast. It was observed that the results from the two simulators are quite similar in most of the cases; differences were found only in those cases where there was an increase in gas solubility ratio of the model. Thus, it was concluded that in flow simulation of reservoirs analogous of those now studied, mainly when the gas solubility ratio is low, the conventional finite differences simulator may be replaced by flow lines simulator the production forecast is compatible but the computational processing time is lower.

Utilização intracoágulo de espuma fibrinolítica - preparação, caracterização e atividade in vitro de uma espuma de estreptoquinase e proposta de uma nova abordagem terapêutica

Foam was developed as a novel vehicle for streptokinase with the purpose of increasing the contact time and area between the fibrinolytic and the target thrombus, which would lead to a greater therapeutic efficacy at lower doses, decreasing the drug s potential to cause bleeding. Fibrinolytic foams were prepared using CO2 and human albumin (at different v:v ratios), as the gas and liquid phases, respectively, and streptokinase at a low total dose (100,000 IU) was used as fibrinolytic agent conveyed in 1 mL of foam and in isotonic saline solution. The foams were characterized as foam stability and apparent viscosity. The thrombolytic effect of the streptokinase foam was determined in vitro as thrombus lysis and the results were compared to those of a fibrinolytic solution (prepared using the same dose of streptokinase) and foam without the fibrinolytic. In vitro tests were conducted using fresh clots were weighed and placed in test tubes kept at 37 ° C. All the samples were injected intrathrombus using a multiperforated catheter. The results showed that both foam stability and apparent viscosity increased with the increase in the CO2:albumin solution ratio and therefore, the ratio of 3:1 was used for the incorporation of streptokinase. The results of thrombus lysis showed that the streptokinase foam presented the highest thrombolytic activity (44.78 ± 9.97%) when compared to those of the streptokinase solution (32.07 ± 3.41%) and the foam without the drug (19.2 ± 7.19%). We conclude that fibrinolytic foam showed statistically significant results regarding the enhancement of the lytic activity of streptokinase compared to the effect of the prepared saline solution, thus it can be a promising alternative in the treatment of thrombosis. However, in vivo studies are needed in order to corroborate the results obtained in vitro

Susceptibility of citrus species to Alternaria alternata, the causal agent of the Alternaria brown spot

Alternaria alternata, the causal agent of Alternaria brown spot (ABS), causes necrosis on leaves, twigs, and fruit, reducing the productivity and quality of fruits. Tangerines and their hybrids are highly susceptible to the disease. Species, hybrids, and cultivars of Citrus from the germplasm bank of the Estacao Experimental de Citricultura de Bebedouro, São Paulo, Brazil, were evaluated in 2004 and 2005 with respect to their resistance to A. alternata, both through natural infection and by inoculation. Detached leaves were also used to demonstrate susceptibility or resistance to the disease. Ten cultivars of Satsumas (Citrus unshiu), and 14 cultivars of Clementine mandarin (C. clementina) did not show any symptoms of the disease in their leaves, either through natural infection or when inoculated in the field. The Burguess SRA-412, Wallent SRA-438, Carvalhais, Ampefy SRA-459, Ananas SRA, and Macaque SRA-426 mandarin hybrids (C. reticulata) did not show symptoms of the disease under natural or artificial infection in the field. Some cultivars of C. deliciosa, C. tangerina, C. erythrosa, and C. temple showed symptoms of the disease, even though no previous record of their susceptibility to Alternaria brown spot had been previously reported. The hybrids Fairchild, Nova, Page, Fortune, and Sunburst were susceptible to the disease. However, Fremont mandarin (a crossing between C. clementina and C. reticulata), Encore (C. nobilis x C. deliciosa), and Fallglo (C. reticulata x C. paradisi) did not show symptoms in field, and few symptoms were verified in detached leaves. These materials are promising for the cultivation of tangerines, and will enable genetic improvement for the development of cultivars resistant to Alternaria brown spot. (c) 2007 Elsevier B.V. All rights reserved.

Biofertilizer for control of Guignardia citricarpa, the causal agent of citrus black spot

Biofertilizers generated from the anaerobic and aerobic digestion of cattle manure, known as Bio1 and Bio2, respectively, were studied with regard to their microbial composition and effect on the mycelial growth of Phyllosticta citricarpa, the causal agent of citrus black spot (CBS). Two field experiments were conducted to determine the biofertilizer's potential (Bio1) in controlling CBS (2001/2002 and 2002/2003 crops). It was observed that the greatest number of microorganisms was found in the aerobically produced biofertilizer. Bio2 did not inhibit the mycelial growth of P. citricarpa. Mycelial growth of P. citricarpa was inversely proportional to the Bio1 biofertilizer concentration. In the 2001/2002 cropping season, the Biol effect in controlling CBS was directly proportional to its concentration, at the rate of 0 (healthy fruit), with R-2 = 0.88. Biol had a significant effect in controlling CBS, at a concentration of 10%, during the 2001/2002 cropping season, with DI values of 0.246 and 0.229 for the. 10 and 20% doses, respectively, compared to DI of 0.329 for the control. A directly proportional effect of the biofertilizer concentration on the percentage of fruits with a rating of zero was. also observed in the 2002/2003 cropping season, with R-2 = 0.48. However, even at doses higher than in the preceding cropping season, the biofertilizer was less effective, possibly due to a higher occurrence of the disease. Copper oxychloride and combined applications of copper oxychloride and carbendazim plus mancozeb controlled the disease. The possibility of using the biofertilizer as a protective biofungicide to replace copper oxychloride, especially in organic agriculture, should be explored. (c) 2005 Elsevier Ltd. All rights reserved.

The predatory mite Stratiolaelaps scimitus as a control agent of the fungus gnat Bradysia matogrossensis in commercial production of the mushroom Agaricus bisporus

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

A new method for inoculation of fruit with Guignardia citricarpa, the causal agent of citrus black spot

Citrus black spot (CBS) is a fungal disease, caused by Guignardia citricarpa, that has a high economic impact on citrus. Although G. citricarpa has been associated with black spot of citrus, an adequate pathogenicity test is still not available. Thus, our objective was to develop and evaluate a simple, safe, and practical pathogenicity test. We used fruits from Pera-Rio and Valencia sweet orange trees from two different orchards, located in the State of São Paulo, Brazil. Inoculation was performed by placing six disks colonized by G. citricarpa, onto the peel of healthy fruits, previously bagged. In the Pera-Rio sweet orange grove, initial symptoms of the false melanose type resulting from the inoculations were observed 55 days after inoculation (dai). In the Valencia grove, initial symptoms also of the false melanose type resulting from the inoculations occurred 73 dai. A total of 92.8% and 86.6% of the Pera Rio and Valencia fruits inoculated, respectively, showed symptoms of CBS. Citrus black spot symptoms were not observed in any of the control fruits.

Genetic Diversity and Population Differentiation of the Causal Agent of Citrus Black Spot in Brazil

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

EFFECT of DIFFERENT SOLID AMOUNTS IN THE PHYSICAL and MICROSCOPICAL PROPERTIES of SiC POROUS CERAMICS

The presence of pores in ceramics is directly related to the chosen forming process. So, in the starch consolidation method, the ceramics show, after burning, pores with morphology similar to that presented by this organic material. on the other hand, the increase in solid load leads up to alterations in dispersion viscosity, increasing the thermal stresses during drying and sintering processes. In order to verify the solid percentage influence in ceramic final properties, samples were prepared with silicon carbide in different compositions using or not starch as binder agent and pore forming element. The characterization of the ceramic pieces was performed by superficial roughness measurements, porosity besides by optical and scanning electron microscopy. The results showed ceramics with SiC and starch presented physical and microscopic properties slightly higher in relation to those with only ceramic powder in their composition. The presence of organic material, agglomerated and foam during the forming were essential for the final properties of the studied samples.

Obtenção e caracterização de um compósito de poliuretano de mamona e pó de vidro para aplicações em insolantes térmicos

Thermal insulation is used to protect the heated or cooled surfaces by the low thermal conductivity materials. The rigid ricin polyurethane foams (PURM) are used for thermal insulation and depend on the type and concentration of blowing agent. Obtaining PURM occurs by the use of polyol, silicone, catalyst and blowing agent are pre -mixed, reacting with the isocyanate. The glass is reusable, returnable and recyclable heat insulating material, whose time of heat dissipation determines the degree of relaxation of its structure; and viscosity determines the conditions for fusion, operating temperatures, annealing, etc. The production of PURM composites with waste glass powder (PV) represents economical and renewable actions of manufacturing of thermal insulating materials. Based on these aspects, the study aimed to produce and characterize the PURM composites with PV, whose the mass percentages were 5, 10, 20, 30, 40 and 50 wt%. PURM was obtained commercially, while the PV was recycled from the tailings of the stoning process of a glassmaking; when the refining process was applied to obtain micrometer particles. The PURM + PV composites were studied taking into account the standard sample of pure PURM and the influence of the percentage of PV in this PURM matrix. The results of the chemical, physical and morphological characterization were discussed taking into account the difference in the microstructural morphology of the PURM+PV composites and the pure PURM, as well the results of the physicochemical, mechanical e thermophysical tests by values obtained of density, hardness, compressive strength, specific heat, thermal conductivity and diffusivity. In general, the structure of pure PURM showed large, elongated and regular pores, while PURM+PV composites showed irregular, small and rounded pores with shapeless cells. This may have contributed to reducing their mechanical strength, especially for PURM - PV50. The hardness and density were found to have a proportional relationship with the PV content on PURM matrix. The specific heat, thermal diffusivity and thermal conductivity showed proportional relationship to each other. So, this has been realized that the increasing the PV content on PURM matrix resulted in the rise of diffusivity and thermal conductivity and the decrease of the specific heat. However, the values obtained by the PURM composites were similar the values of pure PURM, mainly the PURM-PV5 and PURM-PV10. Therefore, these composites can be applied like thermal insulator; furthermore, their use could reduce the production costs and to preserve the environment

Estudo da cristalização de parafinas em sistemas solventes/tensoativos/água

The WAT is the temperature at the beginning of the appearance of wax crystals. At this temperature the first wax crystals are formed by the cooling systems paraffin / solvents. Paraffins are composed of a mixture of saturated hydrocarbons of high molecular weight. The removal of petroleum from wells and the production lines means a surcharge on produced oil, thus solubilize these deposits formed due to modifications of thermodynamics has been a constant challenge for companies of oil exploration. This study combines the paraffin solubilization by microemulsion systems, the determination of WAT systems paraffin / solvent and performance of surfactant in reducing the crystallization. We used the methods: rheological and the photoelectric signal, validating the latter which was developed to optimize the data obtained due to sensitivity of the equipment used. Methods developed for description of wax precipitation are often in poor agreement with the experimental data, they tend to underestimate the amount of wax at temperatures below the turbidity point. The Won method and the Ideal solution method were applied to the WAT data obtained in solvent systems, best represented by the second interaction of Won method using the solvents naphtha, hexane and LCO. It was observed that the results obtained by WAT photoelectric signal when compared with the viscosity occur in advance, demonstrating the greatest sensitivity of the method developed. The ionic surfactant reduced the viscosity of the solvent systems as it acted modifying the crystalline structure and, consequently, the pour point. The curves show that the WAT experimental data is, in general, closer to the modeling performed by the method of Won than to the one performed by the ideal solution method, because this method underestimates the curve predicting the onset of paraffin hydrocarbons crystallization temperature. This occurs because the actual temperature measured was the crystallization temperature and the method proposes the fusion temperature measurement.