Condições macroeconômicas, estrutura de capital e risco de crédito

Dissertação (mestrado)—Universidade de Brasília, Faculdade de Economia, Administração e Contabilidade, Programa de Pós-Graduação em Administração, 2018.Este estudo examina o impacto da interação do risco macroeconômico sobre os spreads de crédito das corporações. Utilizando os spreads dos Credit Default Swaps (CDS), foi possível identificar que, em média, os spreads de crédito diminuem conforme a taxa de crescimento do PIB (Produto Interno Bruto) e o retorno sobre os títulos corporativos aumentam, porém, o spread aumenta à medida que a volatilidade do crescimento do PIB, o nível de endividamento da empresa, a volatilidade implícita das ações da empresa e a incerteza econômica também crescem. Foi possível identificar forte correlação entre as variáveis macroeconômicas com o spread de crédito das empresas, e também foi identificado que o spread não depende somente de variáveis macroeconômicas, mas também de variáveis endógenas das próprias empresas. A partir de utilização da classificação de rating da agência Standard & Poors foi possível identificar que as variáveis endógenas tornam-se mais importantes na determinação do spread de CDS a partir da piora na classificação de risco da empresa.This study examines the impact of the interaction of macroeconomic risk on corporate credit spreads. Using the spreads of credit default swaps (CDS), we find that, on average, credit spreads decrease as the GDP (gross domestic product) growth rate and the return on corporate bonds increase. However, the spread increases as the volatility of GDP growth, the company’s leverage, the implied volatility of the company’s stock and economic uncertainty also increase. The relationship between the macroeconomic variables and the credit spread of the companies, including the influence of an indicator of investor sentiment, the Economic Policy Uncertainty Index, was investigated. This study suggests that the spread depends not only on macroeconomic variables but also on endogenous variables of the companies themselves. Using rating classifications, we find that endogenous variables become more important in determining the CDS spread in companies with poorer credit ratings

Reavaliação do potencial metalogenético dos domínios anómalos associados às mineralizações auríferas da Faixa Vila Verde - Ponte da Barca

Tese de mestrado, Geologia Económica (Prospeção Mineral) Universidade de Lisboa, Faculdade de Ciências, 2017A área de estudo corresponde à faixa de Vila Verde – Ponte da Barca, que se insere no sector NW da Zona Centro-Ibérica. Nesta faixa encontram-se várias ocorrências de mineralizações de Au hospedadas em filões de quartzo, sendo as mais conhecidas as de Godinhaços, Grovelas, Marrancos e Entre Ambosos- Rios. O encaixante é na sua maioria composto por diferentes fácies de rochas graníticas e, na área de Marrancos por sequências de rochas metassedimentares do Silúrico. As ocorrências são conhecidas desde tempos romanos e foram feitos vários estudos anteriores a esta dissertação, existindo inclusive indícios de explorações, como em Marrancos. O objetivo principal desta dissertação é revisitar o conhecimento adquirido sobre a faixa e reavaliar o potencial metalogenético que esta possa ter, principalmente em Au, estudando seis locais de maneira a obter um panorama geral da área. As seis áreas foram Coto da Cruz, Froufe, Godinhaços, Grovelas, Marrancos e Monte das Corujeiras. Para responder a esta problemática o estudo partiu de um relatório técnico que forneceu dados de sedimentos de corrente e dados de mineralometria para toda a região, e dados de geoquímica de solos e geofísicos para as áreas de Godinhaços, Grovelas e Marrancos. Para este conjunto alargado de dados foi possível criar mapas de isoteores, utilizando como método de interpolação o “inverso do quadrado da distância”. Os mapas foram mais tarde filtrados com base em análises multifractais, separando os valores de fundo dos valores anómalos. A conjugação de diferentes mapas permitiu estabelecer relações prováveis entre elementos, indicando que o As é o elemento que melhor se relaciona com o Au, uma vez que os teores mais elevados de As observados no mapa são compatíveis com os locais onde se verificou uma maior contagem do número de partículas de Au. Foram ainda colhidas amostras nas seis áreas referidas de filão mineralizado e, sempre que possível, de encaixante. Estas amostras foram depois descritas em amostra de mão e em petrografia e foi selecionado um conjunto representativo delas para análises de química mineral pontual. As amostras de encaixante correspondentes a rochas graníticas foram processadas para análises de fluorescência de Raio-X. O estudo petrográfico demonstra que a mineralogia principal das mineralizações é constituída por quartzo, sericite, clorite, sulfuretos, principalmente arsenopirite, e minerais secundários resultantes da meteorização, nomeadamente escorodite (Fe3+AsO4·2H2O), hematite e goethite. Registou-se a presença de pelos menos mais três espécies minerais de arsenato, surgindo nas áreas de Coto da Cruz, Godinhaços e Grovelas. O Au está acomodado na estrutura da arsenopirite ou incluso nos cristais, como fundamentado pela química mineral, ou livre no filão como Au nativo ou electrum, habitualmente associado a domínios alterados para escorodite. Associado à arsenopirite encontra-se bismutinite, que nos indica que a arsenopirite precipitou numa altura precoce da circulação de fluidos hidrotermais. As evidências petrográficas indicam o estabelecimento de condições ideais que permitiam a dissolução da arsenopirite, dos bordos para o interior, e consequente precipitação de escorodite. O transporte do Au não é assegurado, uma vez não haver atividade de Cl suficiente para formar complexos aquosos cloretados, e como tal o Au deverá estar retido nos primeiros horizontes do perfil de meteorização. O transporte por outros complexos é inviabilizado pelas condições físico-químicas inferidas para o fluido meteórico atuante. Os resultados obtidos ao longo do presente estudo demonstram que o Au precipitou numa fase precoce do sistema hidrotermal, e o próprio sistema teve uma expressão reduzida a nível regional, associada ao retrabalhamento e mobilização tardia da mineralização, e como tal o potencial da Faixa hospedar mineralizações auríferas economicamente importantes é reduzido.The study area matches the Vila Verde – Ponte da Barca ore belt, which is in the NW part of the Central- Iberian Zone. This ore belt is comprised of several quartz vein-hosted Au mineralization, and some of the most well-known are Godinhaços, Grovelas, Marrancos and Entre Ambos-os-Rios. The host rocks found here are mostly granitic rocks of several facies, and in the Marrancos region the host rock is a sequence of metasedimentary rocks from the Silurian age. The Au occurrences are acknowledged since roman times and several studies have already been conducted prior to this thesis, and there are reports of explorations and exploitations, like the one in Marrancos. The main objective for this dissertation is to revisit the knowledge acquired for this ore belt and re-evaluate the metallogenetic potential that it may have, especially regarding Au, by studying six different areas to get a general view of the area. These six areas where: Coto da Cruz, Froufe, Godinhaços, Grovelas, Marrancos and Monte das Corujeiras. To answer this problem the study derived from a technical report which contained stream sediments and mineralometric data from campaigns for the whole ore belt, and geochemical and geophysical data from smaller, more precise, campaigns done in Godinhaços, Grovelas and Marrancos. For this large set of data it was possible to create isoconcentration maps using the “inversed squared distance” interpolation method. The maps were later filtered recurring to multifractal analysis, separating the base values from the anomalous ones. The conjugation of different maps allowed to establish probable relations between elements, concluding that As is the one who better relates with Au from the mineralometric data, since higher concentrations of As as observed in the map coincide with the places where the highest number of Au particles was accounted for. There were also collected samples from the mineralization in the six areas mentioned above. Whenever possible, host rock samples were also collected. All the samples were studied macroscopically and petrographically and a small representative set of them were selected for mineral chemistry analysis. Samples that belonged to granitic host rocks where processed for X-Ray fluorescence. The petrographical study shows that the main mineralogy in the mineralizations in composed by quartz, sericite chlorite, sulphides, mainly arsenopyrite, and secondary minerals that resulted from weathering, namely scorodite (Fe3+AsO4·2H2O), hematite and goethite. There is also the record of at least three other arsenate mineral species, which were found in Coto da Cruz, Godinhaços and Grovelas, respectively. Au takes part in the arsenopyrite in its structure or as an inclusion, as supported by the mineral chemistry, and free in the vein as native Au or electrum, commonly associated to scocrodite-rich dominions. Also associated with arsenopyrite is bismuthinite, which indicate that the arsenopyrite must have precipitated during the initial stages of the hydrothermal system. The petrographical evidences also point that there were ideal conditions to dissolve arsenopyrite from the rim to the centre, and consequently deposit scorodite. However, the Au transport was not assured, since there wasn’t sufficiently high Cl activity for Au to be transported as chloride aqueous complex, so the most likely place to find Au are in the first layers of the weathering profile. Transport by other complexes is also not possible due to the chemical properties of the meteoric fluid. Results show that Au precipitated during an early stage of the hydrothermal system, and that the hydrothermal system itself had a small expression, associated with reworking and late mobilization of the mineralization, and as such the potential for this ore belt to host economically important Au occurrences is slim

Effects of arterial oxygen tension and cardiac output on venous saturation: a mathematical modeling approach

OBJECTIVES: Hemodynamic support is aimed at providing adequate O2 delivery to the tissues; most interventions target O2 delivery increase. Mixed venous O2 saturation is a frequently used parameter to evaluate the adequacy of O2 delivery. METHODS: We describe a mathematical model to compare the effects of increasing O2 delivery on venous oxygen saturation through increases in the inspired O2 fraction versus increases in cardiac output. The model was created based on the lungs, which were divided into shunted and non-shunted areas, and on seven peripheral compartments, each with normal values of perfusion, optimal oxygen consumption, and critical O2 extraction rate. O2 delivery was increased by changing the inspired fraction of oxygen from 0.21 to 1.0 in steps of 0.1 under conditions of low (2.0 L.min-1) or normal (6.5 L.min-1) cardiac output. The same O2 delivery values were also obtained by maintaining a fixed O2 inspired fraction value of 0.21 while changing cardiac output. RESULTS: Venous oxygen saturation was higher when produced through increases in inspired O2 fraction versus increases in cardiac output, even at the same O2 delivery and consumption values. Specifically, at high inspired O2 fractions, the measured O2 saturation values failed to detect conditions of low oxygen supply. CONCLUSIONS: The mode of O2 delivery optimization, specifically increases in the fraction of inspired oxygen versus increases in cardiac output, can compromise the capability of the "venous O2 saturation" parameter to measure the adequacy of oxygen supply. Consequently, venous saturation at high inspired O2 fractions should be interpreted with caution

Sepsis-associated encephalopathy: not just delirium

Sepsis is a major cause of mortality and morbidity in intensive care units. Organ dysfunction is triggered by inflammatory insults and tissue hypoperfusion. The brain plays a pivotal role in sepsis, acting as both a mediator of the immune response and a target for the pathologic process. The measurement of brain dysfunction is difficult because there are no specific biomarkers of neuronal injury, and bedside evaluation of cognitive performance is difficult in an intensive care unit. Although sepsis-associated encephalopathy was described decades ago, it has only recently been subjected to scientific scrutiny and is not yet completely understood. The pathophysiology of sepsis-associated encephalopathy involves direct cellular damage to the brain, mitochondrial and endothelial dysfunction and disturbances in neurotransmission. This review describes the most recent findings in the pathophysiology, diagnosis, and management of sepsis-associated encephalopathy and focuses on its many presentations

Testosterone represses ubiquitin ligases atrogin-1 and Murf-1 expression in an androgen-sensitive rat skeletal muscle in vivo

Pires-Oliveira M, Maragno AL, Parreiras-E-Silva LT, Chiavegatti T, Gomes MD, Godinho RO. Testosterone represses ubiquitin ligases atrogin-1 and Murf-1 expression in an androgen-sensitive rat skeletal muscle in vivo. J Appl Physiol 108: 266-273, 2010. First published November 19, 2009; doi:10.1152/japplphysiol.00490.2009.-Skeletal muscle atrophy induced by denervation and metabolic diseases has been associated with increased ubiquitin ligase expression. in the present study, we evaluate the influence of androgens on muscle ubiquitin ligases atrogin-1/MAFbx/FBXO32 and Murf-1/Trim63 expression and its correlation with maintenance of muscle mass by using the testosterone-dependent fast-twitch levator ani muscle (LA) from normal or castrated adult male Wistar rats. Gene expression was determined by qRT-PCR and/or immunoblotting. Castration induced progressive loss of LA mass (30% of control, 90 days) and an exponential decrease of LA cytoplasm-to-nucleus ratio (nuclear domain; 22% of control after 60 days). Testosterone deprivation induced a 31-fold increase in LA atrogin-1 mRNA and an 18-fold increase in Murf-1 mRNA detected after 2 and 7 days of castration, respectively. Acute (24 h) testosterone administration fully repressed atrogin-1 and Murf-1 mRNA expression to control levels. Atrogin-1 protein was also increased by castration up to 170% after 30 days. Testosterone administration for 7 days restored atrogin-1 protein to control levels. in addition to the well known stimulus of protein synthesis, our results show that testosterone maintains muscle mass by repressing ubiquitin ligases, indicating that inhibition of ubiquitin-proteasome catabolic system is critical for trophic action of androgens in skeletal muscle. Besides, since neither castration nor androgen treatment had any effect on weight or ubiquitin ligases mRNA levels of extensor digitorum longus muscle, a fast-twitch muscle with low androgen sensitivity, our study shows that perineal muscle LA is a suitable in vivo model to evaluate regulation of muscle proteolysis, closely resembling human muscle responsiveness to androgens.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Universidade Federal de São Paulo, Dept Pharmacol, BR-04044020 São Paulo, BrazilUniv São Paulo, Fac Med Ribeirao Preto, Dept Biochem & Immunol, Ribeirao Preto, BrazilUniversidade Federal de São Paulo, Dept Pharmacol, BR-04044020 São Paulo, BrazilFAPESP: 05/59006-1FAPESP: 2006/58629-8Web of Scienc

Balanço energético de um incinerador de leito fixo para incineração de resíduos sólidos da indústria coureiro-calçadista

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CO2 gasification of elephant grass in a fixed bed reactor

In order to supply the growing world demand of energy and relieve the global warming, biomass is considered a potential clean energy source. In this work, the thermochemical conversion of the elephant grass, through CO2 gasification, for the production of a combustible gas was evaluated. The gasification experiment was conducted at the temperature of 900 °C for 90 min under a carbon dioxide atmosphere. CO presented a maximum production rate of 2.25 mmol/min.gbiomass and a maximum concentration of 82 %mol/mol. The fuel gas produced had an average high heating value of 8.5 MJ/Nm³. Considerable hydrogen production rates were observed throughout the experiment. The experiment had an energy yield of 28.4 kJ/gbiomass. Tar produced was mainly composed of primary products and phenolic derivatives compounds. The results showed that CO2 gasification of elephant grass has the potential to produce a combustible gas allowing the reduction of CO2emissions to the atmosphere

Factors associated with variation in intracranial pressure in a model of intra-abdominal hypertension with acute lung injury

OBJETIVO: Avaliar o efeito de alterações hemodinâmicas, respiratórias e metabólicas sobre a pressão intracraniana em um modelo de lesão pulmonar aguda e síndrome compartimental abdominal. MÉTODOS: Oito porcos Agroceres foram submetidos, após a instrumentação, a cinco cenários clínicos: 1) estado basal com baixa pressão intra-abdominal e pulmão sadio; 2) pneumoperitôneo, com pressão intra-abdominal de 20 mm Hg; 3) lesão pulmonar aguda induzida por lavagem pulmonar e desativação de surfactante; 4) pneumoperitôneo com pressão intra-abdominal de 20 mm Hg na vigência de lesão pulmonar aguda e com PEEP baixo; e 5) PEEP ajustado a 27 cm H2O na vigência de pneumoperitôneo e lesão pulmonar aguda. Variáveis respiratórias e hemodinâmicas foram coletadas. Análise multivariada foi realizada buscando as variáveis associadas com elevação da pressão intracraniana nos cinco cenários estudados. RESULTADOS: Após a análise multivariada, nas situações não associadas com lesão pulmonar aguda apenas a pressão de platô das vias aéreas se correlacionou positivamente com a pressão intracraniana. Nos modelos associados com lesão pulmonar aguda, a pressão de platô de vias aéreas, a pressão arterial de CO2, o CO2 no final da expiração e a pressão venosa central se correlacionaram positivamente com incrementos da pressão intracraniana. CONCLUSÃO: Em um modelo de disfunção orgânica múltipla com situações clínicas associadas com aumento da pressão torácica e abdominal, o incremento da pressão intracraniana desencadeado pela elevação da pressão abdominal parece ser decorrente da piora da complacência do sistema respiratório e da redução do gradiente para drenagem venosa cerebral ocasionado pela elevação da pressão venosa central.OBJECTIVE: To evaluate the effects of hemodynamic, respiratory and metabolic changes on intracranial pressure in a model of acute lung injury and abdominal compartment syndrome. METHODS: Eight Agroceres pigs were submitted to five different clinical scenarios after instrumentation: 1) a baseline condition with low intra-abdominal pressure and healthy lungs; 2) pneumoperitoneum with 20 mmHg intra-abdominal pressure; 3) acute lung injury induced by pulmonary lavage with surfactant deactivation; 4) pneumoperitoneum with 20 mmHg intra-abdominal pressure with lung pulmonary injury and low positive end-expiratory pressure; and 5) 27 cmH2O positive end-expiratory pressure with pneumoperitoneum and acute lung injury. Respiratory and hemodynamic variables were collected. A multivariate analysis was conducted to search for variables associated with increased intracranial pressure in the five scenarios. RESULTS: Only plateau airway pressure showed a positive correlation with intracranial pressure in the multivariate analysis. In the models with acute lung injury, plateau airway pressure, CO2 arterial pressure, end tidal CO2 and central venous pressure were positively correlated with increased intracranial pressure. CONCLUSION: In a model of multiple organ dysfunction with associated clinical conditions causing increased intra-thoracic and abdominal pressure, increased intracranial pressure triggered by elevated intra-abdominal pressure is apparently caused by worsened respiratory system compliance and a reduced brain venous drainage gradient due to increased central venous pressure

Simultaneous production of mesoporous biochar and palmitic acid by pyrolysis of brewing industry wastes

Pyrolysis of malt bagasse was carried out to obtain simultaneously a mesoporous biochar and an oil fraction rich in palmitic acid. The best result for biochar production was at 500 °C with holding time of 10 min. The yields of biochar and pyrolytic oil in this condition were, 29.7 and 33.9 wt%, respectively. The pyrolysis temperature and holding time influenced the yields of the products. An increase in pyrolysis temperature (from 500 to 700 °C) and holding time (from 10 to 50 min) caused a decrease in biochar yield, a reduction in the volatile matter content and an increase in the amount of ash. Additionally, in the range studied in this work, the increase of the pyrolysis temperature caused a decrease in the specific surface area and total pore volume of the biochar. Meanwhile, the biochar presented interesting functional groups and a mesoporous character, which can be a precursor to obtain adsorbents, or even, be used as adsorbent. The pyrolytic oil was composed of oxygenated aromatic compounds, the main fraction being palmitic acid (27.3%), which can be used in a number of applications, including biodiesel production. This work demonstrated that an available and problematic waste, malt bagasse, can be converted simultaneously into a mesoporous biochar and, into a pyrolytic oil rich in palmitic acid. Biochar and pyrolytic oil, in turn, are products of great value and can be applied in several fields