Methane concentrations and fluxes in agricultural and preserved tropical headwater streams.

Tropical streams have been intensively impacted by agricultural activities. Among the most important agricultural activities in Brazil, sugarcane production represents a large impact for economic development and for environmental conditions. Permeating sugarcane fields, several headwater streams can be affected by sugarcane cultivation, in special, aquatic biogeochemical cycles because of the deforestation, fertilization, crop residues and higher temperatures in the tropics.

Prevalence of Obstructive Sleep Apnea and Obesity Among Middle-Aged Women: Implications for Exercise Capacity.

Study Objectives: The aim of the current study was to evaluate the association between obstructive sleep apnea (OSA) and exercise capacity in middle-aged women.

Methods: Consecutive middle-aged female subjects without cardiovascular disease, aged 45 to 65 years, from two gynecological clinics underwent detailed clinical evaluation, portable sleep study, and treadmill exercise test.

Results: We studied 232 women (age: 55.