Context.—Biliary atresia is an inflammatory cholangiopathy of infancy that results in progressive fibrosis and obliteration of bile ducts and represents the main indication for liver transplant in young children. In spite of extensive investigation, its etiology has remained poorly understood. Timely surgical intervention (Kasai procedure) may result in significant benefit to these patients and represents the final goal of an accurate diagnostic evaluation. Objective.—To present an overview of biliary atresia, including clinical and surgical approaches to this disease, with emphasis on the histopathologic evaluation. Data Sources.—Review of relevant literature indexed in PubMed (US National Library of Medicine). Conclusion.—A well-coordinated multidisciplinary approach is required in the assessment of suspected cases of biliary atresia. Pathologic examination of biopsy specimens is an integral part of the diagnostic algorithm and, therefore, plays a pivotal role in the diagnostic evaluation of this disease.

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This Working Paper should not be reported as representing the views of the IMF and the National Treasury of Brazil. The views expressed in this Working Paper are those of the author(s) and do not necessarily represent those of the IMF or IMF policy, nor those of the National Treasury of Brazil. Working Papers describe research in progress by the author(s) and are published to elicit comments and to further debate. This paper characterizes the term structure of Treasury bond yields for Brazil, and estimates a Nelson-Siegel Model to reproduce its stylized facts for the period 2004-2010. For this purpose, this paper uses a software developed by Fund staff. In addition, the paper estimates two versions of the Nelson-Siegel Model that incorporates macroeconomic variables with the aim of assessing the dynamic interactions between the yield curve and the macroeconomy.

Since 1987, many countries have decided on their electricity market liberalization, increasing their degree of maturity, efficiency and, finally, liquidity. This paper aims at presenting the main concepts of liquidity and its importance for the satisfactory functioning of electricity markets. Likewise, it assesses the Brazilian electricity market liquidity by presenting the perspective of the electricity contracts traded in Brazil, focusing on the free market, exploring further the contribution of various classes of agents in the liquidity of these products. For instance, it portrays the current liquidity scenario by presenting the churn rates of conventional and special energy short and long term contracts and the liquidity relative rates which are an innovative adaptation from the stock market to calculate the liquidity of the referred products. Finally, this paper lists some actions that could be implemented by the Brazilian electricity market in order to improve its liquidity level.

The Policy Research Working Paper Series disseminates the findings of work in progress to encourage the exchange of ideas about development issues. An objective of the series is to get the findings out quickly, even if the presentations are less than fully polished. The papers carry the names of the authors and should be cited accordingly. The findings, interpretations, and conclusions expressed in this paper are entirely those of the authors. They do not necessarily represent the views of the International Bank for Reconstruction and Development/World Bank and its affiliated organizations, or those of the Executive Directors of the World Bank or the governments they represent.