Diversficaçâo e avaliaçâo de carteiras nos mercados de capitais dos principais países Latino-Americanos

The present study has the objective of verifying if simultaneous investments in several international stock markets are more attractive than in only one national stock market, in other words, if the first ones present a superior risk-return relationship. It can be admitted that if there is a total integration among the analyzed countries, there is little advantage in the international diversification, but if the countries are less integrated, the diversification would bring advantages in risk-return terms. The empirical work is based on Markowitz portfolio theory, CAPM and in the portfolio performance measures of Sharpe, Treynor, and Jensen. The analysis was made for the period of February 1993 to January 2003, based in the most liquid stocks negotiated in the stock market of the main countries of Latin America. The results showed that portfolio diversification in international markets is a better approach.O presente estudo tem o objetivo de verificar se investimentos simultâneos em vários mercados internacionais de ações são mais atrativos do que aqueles realizados somente em um único mercado nacional, ou seja, se os primeiros apresentam uma relação risco-retorno superior. Pode-se admitir que se houver uma total integração entre os países analisados, tem-se pouca vantagem na diversificação internacional, mas se os mesmos forem menos integrados, a diversificação traria vantagens em termos de risco e retorno. A base empírica do trabalho está fundamentada na teoria de carteiras de Markowitz, no CAPM e nos índices de medição do desempenho de carteiras de Sharpe, Treynor e Jensen. A análise foi feita para o período de fevereiro de 1993 a janeiro de 2003, com base nas ações mais negociadas nas bolsas dos principais países da América Latina. Os resultados mostraram que a diversificação de carteiras em mercados internacionais é mais indicada

Characterisation of microbial attack on archaeological bone

As part of an EU funded project to investigate the factors influencing bone preservation in the archaeological record, more than 250 bones from 41 archaeological sites in five countries spanning four climatic regions were studied for diagenetic alteration. Sites were selected to cover a range of environmental conditions and archaeological contexts. Microscopic and physical (mercury intrusion porosimetry) analyses of these bones revealed that the majority (68%) had suffered microbial attack. Furthermore, significant differences were found between animal and human bone in both the state of preservation and the type of microbial attack present. These differences in preservation might result from differences in early taphonomy of the bones. © 2003 Elsevier Science Ltd. All rights reserved