Low levels of methylmercury induce DNA damage in rats: protective effects of selenium

In this study we examined the possible antigenotoxic effect of selenium (Se) in rats chronically exposed to low levels of methylmercury (MeHg) and the association between glutathione peroxidase (GSH-Px) activity and DNA lesions (via comet assay) in the same exposed animals. Rats were divided into six groups as follows: (Group I) received water; (Group II) received MeHg (100 mu g/day); (Group III) received Se (2 mg/L drinking water); (Group IV) received Se (6 mg/L drinking water); (Group V) received MeHg (100 mu g/day) and Se (2 mg/L drinking water); (Group VI) received MeHg (100 mu g/day) and Se (6 mg/L drinking water). Total treatment time was 100 days. GSH-Px activity was determined spectrophotometrically and DNA damage was determined by comet assay. Mean GSH-Px activity in groups I, II, III, IV, V and VI were, respectively: 40.19 +/- A 17.21; 23.63 +/- A 6.04; 42.64 +/- A 5.70; 38.50 +/- A 7.15; 34.54 +/- A 6.18 and 41.39 +/- A 11.67 nmolNADPH/min/gHb. DNA damage was represented by a mean score from 0 to 300; the results for groups I, II, III, IV, V and VI were, respectively: 6.87 +/- A 3.27; 124.12 +/- A 13.74; 10.62 +/- A 3.81; 13.25 +/- A 1.76; 86.87 +/- A 11.95 and 76.25 +/- A 7.48. There was a significant inhibition of GSH-Px activity in group II compared with group I (P < 0.05). Groups V and VI did not show a difference in enzyme activity compared with groups III and IV, showing the possible protective action of Se. Comet assay presented a significant difference in DNA migration between group II and group I (P < 0.0001). Groups V and VI showed a significant reduction in MeHg-induced genotoxicity (P < 0.001) when compared with group II. A negative correlation (r = -0.559, P < 0.05) was found between GSH-Px activity and DNA lesion, showing that the greater the DNA damage, the lower the GSH-Px activity. Our findings demonstrated the oxidative and genotoxic properties of MeHg, even at low doses. Moreover, Se co-administration reestablished GSH-Px activity and reduced DNA damage.

Likelihood estimate of treatment effects under selection bias

We consider methods for estimating causal effects of treatment in the situation where the individuals in the treatment and the control group are self selected, i.e., the selection mechanism is not randomized. In this case, simple comparison of treated and control outcomes will not generally yield valid estimates of casual effects. The propensity score method is frequently used for the evaluation of treatment effect. However, this method is based onsome strong assumptions, which are not directly testable. In this paper, we present an alternative modeling approachto draw causal inference by using share random-effect model and the computational algorithm to draw likelihood based inference with such a model. With small numerical studies and a real data analysis, we show that our approach gives not only more efficient estimates but it is also less sensitive to model misspecifications, which we consider, than the existing methods.

Effects of computer reminders on complications of peripheral venous catheters and nurses' adherence to a guideline in paediatric care : a cluster randomised study

BACKGROUND: Reminder systems in electronic patient records (EPR) have proven to affect both health care professionals' behaviour and patient outcomes. The aim of this cluster randomised trial was to investigate the effects of implementing a clinical practice guideline (CPG) for peripheral venous catheters (PVCs) in paediatric care in the format of reminders integrated in the EPRs, on PVC-related complications, and on registered nurses' (RNs') self-reported adherence to the guideline. An additional aim was to study the relationship between contextual factors and the outcomes of the intervention. METHODS: The study involved 12 inpatient units at a paediatric university hospital. The reminders included choice of PVC, hygiene, maintenance, and daily inspection of PVC site. Primary outcome was documented signs and symptoms of PVC-related complications at removal, retrieved from the EPR. Secondary outcome was RNs' adherence to a PVC guideline, collected through a questionnaire that also included RNs' perceived work context, as measured by the Alberta Context Tool. Units were allocated into two strata, based on occurrence of PVCs. A blinded simple draw of lots from each stratum randomised six units to the control and intervention groups, respectively. Units were not blinded. The intervention group included 626 PVCs at baseline and 618 post-intervention and the control group 724 PVCs at baseline and 674 post-intervention. RNs included at baseline were 212 (65.4 %) and 208 (71.5 %) post-intervention. RESULTS: No significant effect was found for the computer reminders on PVC-related complications nor on RNs' adherence to the guideline recommendations. The complication rate at baseline and post-intervention was 40.6 % (95 % confidence interval (CI) 36.7-44.5) and 41.9 % (95 % CI 38.0-45.8), for the intervention group and 40.3 % (95 % CI 36.8-44.0) and 46.9 % (95 % CI 43.1-50.7) for the control. In general, RNs' self-rated work context varied from moderately low to moderately high, indicating that conditions for a successful implementation to occur were less optimal. CONCLUSIONS: The reminders might have benefitted from being accompanied by a tailored intervention that targeted specific barriers, such as the low frequency of recorded reasons for removal, the low adherence to daily inspection of PVC sites, and the lack of regular feedback to the RNs. TRIAL REGISTRATION: Current Controlled Trials ISRCTN44819426.

Effects of the real plan of the Brazilian banking system

The aim of this paper is to assess the progress of the banking sector before and shortly after the Real Plan. We began by assessing the drop in the inflation revenues (negative real interest rates paid by the excess of demand deposits over total reserve requirements) as a result of the change in inflation from 40% a month for the pre-Real Plan period to a monthly average of 3.65% (IGP-DI), between July 1994 and May 1995. Then, using the financial statement data of a group of 90 banks, we attempt to estimate the net losses due to the inflation drop analyzing the profitability and other parameters of the banking industry. The calculations are made separately for private, state and federal banks. A later analysis on performance using information given to CVM (Securities Exchange Commission) by the six major private banks in the country is also discussed herein.

On the economic and fiscal effects of infrastructure investment in Brazil

This article studies the productive impact of infrastructure investment in Brazil. Public-capital expenditures in the country have decreased continuously over the last two decades, and this paper shows the significant impact this has had on infrastructure stocks. Cointegration analysis is used to investigate the long-run association between output and infrastructure, the results being then used to study the short-run dynamic of these variables. Whether in the short or long run, the productive impact of infrastructure was found to be relevant. Other group of simulations studies the impact of expanding capital expenditures through debt finance on debt to GDP ratio as well as on public cash áow and net worth.

Property rights as a public policy tool: an empirical analysis of the social and economic effects

Secure property rights are considered a key determinant of economic development. However, the evaluation of the causal effects of land titling is a difficult task. The Brazilian government through a program called "Papel Passado" has issued titles, since 2004, to over 85,000 families and has the goal to reach 750,000. Furthermore, another topic in Public Policy that is crucial to developing economies is income generation and child labor force participation. Particularly, in Brazil, about 5.4 million children and teenagers between 5 and 17 years old are still working. This thesis examines the direct impact of securing a property title on income and child labor force participation. In order to isolate the causal role of ownership security, this study uses a comparison between two close and very similar communities in the City of Osasco case (a town with 650,000 people in the São Paulo metropolitan area). One of them, Jardim Canaã, was fortunated to receive the titles in 2007, the other, Jardim DR, given fiscal constraints, only will be part of the program schedule in 2012, and for that reason became the control group. Also, this thesis also aims to test if there is any relationship between land title and happiness. The estimates suggest that titling results in a substantial decrease of child labor force participation, increase of income and happiness for the families that received the title compared to the others.

The effects of tax incentives for small firms on employment levels

This paper will examine the effects of tax incentives for small businesses on employment level evaluating a program with this purpose implemented in Brazil in the 1990s. We first develop a theoretical framework which guides both the de nition of the parameters of interest and their identi cation. Selection problems both into the treatment group and into the data sample are tackled by combining fixed effects methods and regression discontinuity design on alternative sub-samples of a longitudinal database of manufacturing firms. The results show that on the one hand the size composition of the treated fi rms may be changed due to the survival of some smaller firms that would have exited had it not been eligible to the program. On the other hand, the treated firms who do not depend on the program to survive do employ more workers.

Assessing Dodd Frank Effects on banking capital structure and Banker´s Pay structure

The systemic financial crisis that started in 2008 in the United States had some severe effects in the economic activity and required the bailout of financial institutions with the use of taxpayer’s money. It also originated claims for stronger regulatory framework in order to avoid another threat in the financial market. The Dodd Frank Act was proposed and approved in the United States in the aftermath of the crisis and brought, among many other features, the creation of the Financial Stability Oversight Council and the tougher inspection of financial institutions with asset above 50 billion dollars. The objective of this work is to study the causal effect of the Dodd Frank Act on the behavior of the treatment group subject to monitoring by the Financial Stability Oversight Council (financial institutions with assets above 50 billion dollars) regarding capital and compensation structure in comparison to the group that was not treated. We use data from Compustat and our empirical strategy is the Regression Discontinuity Design, not usually applied to the banking literature, but very useful for the present work since it allows us to compare the treatment group and the non-treatment group in the year of the enactment of the law (2010). No change of behavior was observed for the Capital Structure. In the Compensation Schemes, however, a decrease was found in the item other compensation for CEOs and CFOs. We also performed a robustness check by running a placebo test on the variables in the year before the law was enacted. No significance was found, which supports the conclusion that our main results were caused by the enactment of the DFA.

The effects of small firm tax incentives on employment levels

This paper aims to evaluate the impact on employment growth of a tax incentive program targeting Brazilian manufacturing small businesses (SIMPLES). This evaluation is conducted for two distinct periods: for the year 1997, when the program was first implemented, and for the year 1999, when the eligibility rule was modified to allow the eligibility of a broader group of firms. The evaluation takes into account two distinct channels through which the charted effects operate. The first is the employment variation in the firms that became eligible for the incentives, and the second is the change in the survival probability experienced by the same group of firms. Moreover, each of these channels can be activated either by the tax reduction dimension of the program or by its dimension of red tape simplification. Our results identify positive effects on employment growth for the tax incentive program only in the dimension of red tape simplification and its effects on the 1997 sample.

Can a great resume hurt? Gender and contrast effects on recruiting

Recruiters make many inferences about applicants' abilities and interpersonal attributes on the basis of applicants' resumes. For example, every once in a while, a good resume leaves a strong positive impression and the recruiter creates a high expectation for the selection interview. What if a disappointing interview follows? Will the great resume help or hurt the candidate? The purpose of this study is to assess the impact of a good resume on the recruiter’s evaluation of a candidate when a non-enthusiastic interview follows as well as the interacting role of gender. The results of two online experiments (n=454) where participants played the role of the recruiter, showed that, on average, a very good resume (vs. no resume) before a non-enthusiastic interview did not affect the recruiter’s evaluation of the candidate. However, when the recruiter’s and the candidate’s gender were taken into consideration, a different picture emerged. While no effect was found for male recruiters, the candidate’s resume had a clear significant impact on female recruiter’s evaluations: when the candidate was also a female, the good resume shown before the non-enthusiastic interview performance tended to help, whereas when the candidate was a male, the good resume had a significant negative effect on female recruiters’ evaluation of the candidate. In sum, in situations where the resume had a strong impact on the recruiter’s evaluation (female recruiters), the direction of the effect was moderated by the candidate’s gender. Gender differences in information processing as well as in-group/out-group biases due to gender matching are used to hypothesize and explain the main findings.

The effects of government deficit on equilibrium real exchange rates and stock prices

This paper studies the effect of government deficits on equilibrium real exchange rates and stock prices. The theoretical part modifies a two-country cash-in-advance model like used in Lucas(1982) and Sargent(1987) in order to accommodate an exchange rate market and a government that pursues fiscal and monetary policy targets. The implied result is that unanticipated shocks in government deficits raise expectations of both taxes and inflation and, therefore, are associated with real exchange rate devaluations and lower stock prices. This finding is strongly supported by empirical evidence for a group of 19 countries, representing 76% of world production

Peer effects on locus of control

Eu analiso o papel que a interação entre pares tem na determinação do Locus de Controle, uma medida de quão pessoalmente responsável as pessoas se sentem com relação a diferentes aspectos de suas vidas. Eu estabeleço identificação através de variação no tamanho do grupo e de variáveis instrumentais baseadas na estrutura de painel dos dados. Eu estudo a questão no contexto escolar, utilizando os dados de alunos no Ensino Fundamental de um município brasileiro, que inclui o questionário de Tel Aviv de Locus de Controle. Minhas estimativas não apresentam sinais de peer effects endógenos ou contextuais.

Creditor's protection and bank loans: lack of competition hamprers bankruptcy reform's effects

This dissertation investigates how credit institutions’ market power limits the effects of creditor protection rules on the interest rate and the spread of bank loans. We use the Brazilian Bankruptcy Reform of June/2005 (BBR) as a legal event affecting the institutional environment of the Brazilian credit market. The law augments creditor protection and aims to improve the access of firms to the credit market and to reduce the cost of borrowing. Either access to credit or the credit cost are also determined by bank industry competition and the market power of suppliers of credit. We derive a simple economic model to study the effect of market power interacting with cost of lending. Using an accounting and operations dataset from July/2004 to December/2007 provided by the Brazilian Central Bank, we estimate that the lack of competition in the bank lending industry hinders the potential reducing effect of the BBR on the interest rate of corporate loans by approximately 30% and on the spread by approximately 23%. We also find no statistical evidence that the BBR affected the concentration level of the Brazilian credit market. We present a brief report on bankruptcy reforms around the world, the changes in the Brazilian legislation and on some recent related articles in our introductory chapter. The second chapter presents the economic model and the testable hypothesis on how the lack of competition in the lending market limits the effects of improved creditor protection. In this chapter, we introduce our empirical strategy using a differences-in-differences model and we estimate the limiting effect of market power on the BBR’s potential to reduce interest rates and on the spread of bank loans. We use the BBR as an exogenous event that affects collateralized corporate loans (treatment group) but that does not affect clean consumer loans (control group) to identify these effects, using different concentration measures. In Chapter 3, we propose a two-stage empirical strategy to handle the H–Statistics proposed by Panzar and Rosse as a measure of market competition. We estimate the limiting effects of the lack of competition in replacing the concentration statistics by the H–Statistics. Chapter 4 presents a structural break test of the concentration index and checks if the BBR affects the dynamic evolution of the concentration index.

The influence of the tag-along rights in the value of companies: an event study of the effects on the market and service companies

The aim of this work is to check the effect of granting tag-along rights to stockholders by analyzing the behavior of the return of the stock. To do so we carried out event studies for a group of 21 company stocks, divided into service provider companies and others, who granted this right to their stockholders after Law 10,303 was passed in October, 2001. In the test we used two models for estimating abnormal returns: adjusted to the market and adjusted to the risk and market. The results of the tests we carried out based on these models did not capture abnormal returns (surpluses), telling us that the tag-along rights did not affect the pattern of daily returns of the stocks of companies traded on BOVESPA (The Sao Paulo Stock Exchange). We did not expect this result because of the new corporate governance practices adopted by companies in Brazil.

Bacteriologic investigation of the effects of sodium hypochlorite and chlorhexidine during the endodontic treatment of teeth with apical periodontitis

SIQUEIRA JR. et al. Bacteriologic investigation of the effects of sodium hypochlorite and chlorhexidine during the endodontic treatment of teeth with apical periodontitis. Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endod., v. 104, n. 1, p. 122-130, 2007.