Two construction workers based at Brazil's Arena Amazônia in Manaus died in separate incidents on Saturday, adding to safety concerns as the country races to finish building in time to host the 2014 World Cup. Marcleudo de Melo Ferreira…died in a hospital…after falling nearly 115 feet from the roof of the stadium…The body of a second worker, José Antonio da Silva Nascimento, 49, was later found at the site's convention centre, which will host meetings during the World Cup…Andrade Gutierrez, the Brazilian firm building the Amazon stadium, said in a statement that Ferreira worked for a company that had been contracted to build the arena's cover and an internal investigation of the incident would be conducted….