Multi-tracer analysis to estimate the historical evolution of pollution in riverbed sediment of subtropical watershed, the lower course of the Piracicaba River, São Paulo, Brazil.

The main land use/land cover changes (LULCC) have been associated with population growth and energy policies in the São Paulo State, Brazil, since 1970. The LULCC can alter the behavior of trace elements in different environmental systems, with the riverbed sediments being the main reservoirs or sinks for trace elements, and thus become a valuable environmental archive on temporal changes. Thus, the main purpose of the study was to apply a multi-tracer analysis to estimate the historical evolution of pollution in riverbed sediment of a subtropical watershed, the lower course of the Piracicaba River, São Paulo, Brazil.

Likelihood ratios for fetal trisomy 21 based on nasal bone length in the second trimester: how best to define hypoplasia?

Objective: To determine the best measure of fetal nasal bone hypoplasia for trisomy 21 risk assessment in the second trimester.

Methods: This was a prospective, observational study performed at a single institution between February 2003 and December 2005. Fetuses with nasal bone length recorded sonographically between 16 and 20.