Amazon forests maintain consistent canopy structure and greenness during the dry season.

The seasonality of sunlight and rainfall regulates net primary production in tropical forests. Previous studies have suggested that light is more limiting than water for tropical forest productivity, consistent with greening of Amazon forests during the dry season in satellite data. We evaluated four potential mechanisms for the seasonal green-up phenomenon, including increases in leaf area or leaf reflectance, using a sophisticated radiative transfer model and independent satellite observations from lidar and optical sensors.

IgG subclasses and DNA detection of HHV-6 and HHV-7 in healthy individuals.

Human herpesvirus 6 (HHV-6) and 7 (HHV-7) are common opportunistic agents in immunocompromised hosts, although infection with HHV-6 and HHV-7 can also be observed in immunocompetent hosts. Despite similar biology and epidemiology, this study evaluated differences in the IgG subclass distribution associated with HHV-6 and HHV-7 in seropositive, healthy persons. The identified subclasses were also compared with the detection of HHV-6 and HHV-7 DNA.