Bounding Global Aerosol Radiative Forcing of Climate Change.

Aerosols interact with radiation and clouds. Substantial progress made over the past 40 years in observing, understanding, and modeling these processes helped quantify the imbalance in the Earth's radiation budget caused by anthropogenic aerosols, called aerosol radiative forcing, but uncertainties remain large. This review provides a new range of aerosol radiative forcing over the industrial era based on multiple, traceable, and arguable lines of evidence, including modeling approaches, theoretical considerations, and observations. Improved understanding of aerosol absorption and the causes of trends in surface radiative fluxes constrain the forcing from aerosol-radiation interactions. A robust theoretical foundation and convincing evidence constrain the forcing caused by aerosol-driven increases in liquid cloud droplet number concentration. However, the influence of anthropogenic aerosols on cloud liquid water content and cloud fraction is less clear, and the influence on mixed-phase and ice clouds remains poorly constrained. Observed changes in surface temperature and radiative fluxes provide additional constraints. These multiple lines of evidence lead to a 68% confidence interval for the total aerosol effective radiative forcing of -1.6 to -0.6 W m-2, or -2.0 to -0.4 W m-2 with a 90% likelihood. Those intervals are of similar width to the last Intergovernmental Panel on Climate Change assessment but shifted toward more negative values. The uncertainty will narrow in the future by continuing to critically combine multiple lines of evidence, especially those addressing industrial-era changes in aerosol sources and aerosol effects on liquid cloud amount and on ice clouds.

Antibiotic-seeking behavior in college students: what do they really expect?

Injudicious use of antibiotics contributes to increased bacterial resistance, and patient expectations encourage physicians to overuse antibiotics. The authors evaluated the level of ill college students' antibiotic-seeking behavior to determine if receiving an antibiotic prescription influenced patients' satisfaction with visits to a clinician. Of 129 students with upper respiratory complaints presenting to a university health center, 55% expected an antibiotic prescription. Antibiotic expectation was significantly more likely among students who thought they had a bacterial versus a viral infection (90% vs 40%; p < .01). A clear diagnosis, an explanation of the rationale for treatment, and an antibiotic prescription were significantly associated with patient satisfaction. Clinicians prescribed an antibiotic for 36% of the students; only 13% of these 46 had requested an antibiotic during the visit. At some previous time, one third of the students had taken an antibiotic prescribed for an earlier illness or for another person. Better patient education and improved clinician-patient communication can potentially help to reduce the injudicious use of antibiotics.