Comportamento dos íons pb(ii) e cd(ii) na Interface óxido - solução aquosa

TCC (graduação) - Universidade Federal de Santa Catarina. Centro de Ciências Físicas e Matemáticas. Curso de Química.Para um maior conhecimento referente ao movimento (transporte e mobilidade) de íons metálicos, na interface sólido-solução aquosa, é necessário avaliar o comportamento dos íons metálicos com relação a adsorção/dessorção dos mesmos em vários tipos de superfícies. A cinética e o equilíbrio na adsorção das espécies metálicas Pb(II) e Cd(II) em relação aos adsorventes argilominerais, como a hematita e a alumina dependem da presença de sítios do adsorvente que estejam disponíveis para ligação. No presente estudo é descrito o comportamento de Pb(II) e do Cd(II) em solução na presença de γ-alumina e α-hematita, utilizando-se diferentes técnicas analíticas que foram otimizadas. As determinações de Pb(II) utilizando um eletrodo íon seletivo, mostram: i) limite de detecção (2,44±0,50) x10-6 mol L-1 e, ii) limite de quantificação de (6,11±0,50) x 10-6 mol L-1. Os resultados da intracalibração entre os métodos espectrofluorimétrico e de eletrodo seletivo a íon , para determinar Pb(II) na presença de γ-alumina são satisfatórios. O tempo de equilíbrio para a adsorção do Cd(II) e Pb(II) em γ-alumina e α-hematita mostram que após um tempo de menos de uma hora é atingido o equilíbrio. Os parâmetros de Langmuir calculados para adsorção de Pb(II) em γ- alumina mostram uma capacidade de adsorção de 22 g Kg-1 de γ-alumina e uma constante de Langmuir de 2,36 x 106 mol L-1

Density forecasting in financial risk modelling

As a result of an increasingly stringent regulation aimed at monitoring financial risk exposures, nowadays the risk measurement systems play a crucial role in all banks. In this thesis we tackle a variety of problems, related to density forecasting, which are fundamental to market risk managers. The computation of risk measures (e.g. Value-at-Risk) for any portfolio of financial assets requires the generation of density forecasts for the driving risk factors. Appropriate testing procedures must then be identified for an accurate appraisal of these forecasts. We start our research by assessing whether option-implied densities, which constitute the most obvious forecasts of the distribution of the underlying asset at expiry, do actually represent unbiased forecasts. We first extract densities from options on currency and equity index futures, by means of both traditional and original specifications. We then appraise them, via rigorous density forecast evaluation tools, and we find evidence of the presence of biases. In the second part of the thesis, we focus on modelling the dynamics of the volatility curve, in order to measure the vega risk exposure for various delta-hedged option portfolios. We propose to use a linear Kalman filter approach, which gives more precise forecasts of the vega risk exposure than alternative, well-established models. In the third part, we derive a continuous time model for the dynamics of equity index returns from a data set of 5-minute returns. A model inferred from high-frequency typical of risk measures calculations. The last part of our work deals with evaluating density forecasts of the joint distribution of the risk factors. We find that, given certain specifications for the multivariate density forecast, a goodness-of-fit procedure based on the Empirical Characteristic Function displays good statistical properties in detecting misspecifications of different nature in the forecasts

Sports practices related to alcohol and tobacco use among high school students

Objective: To examine the relationship between alcohol and tobacco use and sports in a national sample of secondary students. Methods: This cross-sectional study enrolled a representative sample of secondary students from public and private schools from all 27 Brazilian state capitals. Students were assessed in 2010 by a self-report questionnaire including questions on drug use and sport activity in the last month (n=13,872). Results: Subjects who played sports exhibited a higher frequency of alcohol use and heavy episodic drinking than their peers who did not play sports. Practices that were associated with higher odds of heavy episodic drinking in the last month included gym, weight training (adjusted odds ratio [aOR]: 2.0, 95% confidence interval [95%CI] 1.6-2.4), and soccer (aOR: 1.3, 95%CI 1.1-1.5). Fighting, martial arts, or capoeira were associated with smoking (aOR: 1.9, 95%CI 1.2-3.2). Conclusion: These results suggest a relationship between some sports preferences and a higher risk of alcohol or tobacco use among Brazilian secondary students. This relationship should be considered in preventive programs.Universidade Federal de São Paulo (UNIFESP) Department of PsychobiologyUNIFESP, Department of PsychobiologySciEL

The effect of cultural origin on COVID-19 infection rates

We examine whether a community’s cultural origin affects COVID-19 infection rates by exploiting cultural differences in the bilingual province of South Tyrol in Northern Italy. We find lower infection rates in municipalities with a relatively higher proportion of German speakers, even after controlling for widely used measures of social and civic capital. Our findings can be explained by a more future-oriented behaviour of German speakers in comparison with Italian speakers

Typing of Enterococcus faecium by polymerase chain reaction and pulsed field gel electrophoresis

Polymerase chain reaction (PCR) with JB1 or REP consensus oligonucleotides and pulsed field gel electrophoresis (PFGE) were used to study genomic DNA extracted from 31 strains of enterococci. Eleven ATCC strains, representative of 11 species of Enterococcus, were initially tested by JB1-PCR, revealing that Enterococcus malodoratus and Enterococcus hirae presented identical banding patterns. Eight Enterococcus faecium isolates from Stanford University and 12 from São Paulo Hospital were studied by JB1-PCR, REP-PCR 1/2R and PFGE. Among the isolates from Stanford University, 5 genotypes were defined by JB1-PCR, 7 by REP-PCR 1/2R and 4 by PFGE. Among the isolates from São Paulo Hospital, 9 genotypes were identified by JB1-PCR, 6 by REP-PCR and 5 by PFGE. The three methods identified identical genotypes, but there was not complete agreement among them.Universidade Estadual de Maringá Centro de Ciências da Saúde Departamento de EnfermagemUniversidade Federal de São Paulo (UNIFESP) Departamento de Doenças Infecciosas e ParasitáriasUNIFESP, Depto. de Doenças Infecciosas e ParasitáriasSciEL

Molecular confirmation of Maize rayado fino virus as the Brazilian corn streak virus

Maize rayado fino virus (MRFV), present in various countries in Latin America, has shown similarities to corn streak virus that occurs in Brazil, regarding pathogenic, serological and histological characteristics. In the current report both virus were molecularly compared to confirm the similarities between them. MRFV was identified by nucleic acid hybridization in samples of maize tissues exhibiting symptoms of "corn stunt" disease, collected from two Brazilian States - São Paulo and Minas Gerais. The coat protein gene and 3'non-translated region of MRFV were amplified from infected tissues by reverse transcription-polymerase chain reaction (RT-PCR) using MRFV-specific primers, and were characterized by nucleotide sequence and phylogenetic analysis of the cloned PCR products. Phylogenetic analysis of the relationships between the Brazilian isolates and isolates obtained from Latin America and the United States reveals a close relationship to isolates from Brazil, Peru and Bolivia. Results support the proposal that the Brazilian corn streak virus be regarded as an isolate of MRFV and provide evidence for the presence of MRFV in "corn stunt' disease in Brazil.O vírus do rayado fino do milho (MRFV), presente em vários países da América Latina, tem mostrado semelhança ao vírus da risca do milho que ocorre no Brasil, em relação a características patogênicas, sorológicas e histológicas. No presente trabalho, ambos os vírus foram comparados molecularmente, visando confirmar a similaridade entre os mesmos. O MRFV foi identificado por hibridização de ácido nucléico em amostras de tecido que apresentavam sintomas de enfezamento, coletadas nos estados de São Paulo e Minas Gerais. O gene da capa protéica e a região 3' não traduzida do MRFV foram amplificados, a partir de tecidos infectados, através da transcrição reversa por reação em cadeia da polimerase (RT-PCR), usando-se os iniciadores específicos para o vírus, obtendo-se a seqüência nucleotídica e a análise filogenética dos produtos de PCR clonados. A análise filogenética relacionando isolados brasileiros, da América Latina e dos Estados Unidos revela a estreita relação entre isolados do Brasil, do Peru e da Bolívia. Os resultados demonstraram que o vírus da risca do milho, presente no Brasil, pode ser considerado como um isolado do MRFV e também evidenciaram a presença do MRFV associado à doença conhecida como enfezamento do milho que ocorre no Brasil

Managers' cultural origin and corporate response to an economic shock

We exploit the exogenous Covid-19 shock in a bicultural area of Italy to identify cultural differences in the way companies respond to economic shocks. Firms with managers of diverse cultural backgrounds resort to different forms of government aid, diverge in their investment decisions, and have different growth rates. These findings are consistent with cultural differences in time preferences and debt aversion. Specifically, we find that the response of managers belonging to a more long-term oriented culture is characterized by a lower recourse to debt, more investments and higher growth rates. Overall, our results show that the cultural origin of managers significantly affects firms’ reaction to economic shocks and real economic outcome

Managers' cultural origin and corporate response to an economic shock

We exploit the exogenous Covid-19 shock in a bicultural area of Italy to identify cultural differences in the way companies respond to economic shocks. Firms with managers of diverse cultural backgrounds resort to different forms of government aid, diverge in their investment decisions, and have different growth rates. These findings are consistent with cultural differences in time preferences and debt aversion. Specifically, we find that the response of managers belonging to a more long-term oriented culture is characterized by a lower recourse to debt, more investments and higher growth rates. Overall, our results show that the cultural origin of managers significantly affects firms' reaction to economic shocks and real economic outcomes