Publications

On-road transportation is responsible for 28% of all U.S. fossil-fuel CO2 emissions. Mapping vehicle emissions at regional scales is challenging due to data limitations. Existing emission inventories use spatial proxies such as population and road density to downscale national or state-level data. Such procedures introduce errors where the proxy variables and actual emissions are weakly correlated, and limit analysis of the relationship between emissions and demographic trends at local scales. We develop an on-road emission inventory product for Massachusetts-based on roadway-level traffic data obtained from the Highway Performance Monitoring System (HPMS). We provide annual estimates of on-road CO2 emissions at a 1 × 1 km grid scale for the years 1980 through 2008. We compared our results with on-road emissions estimates from the Emissions Database for Global Atmospheric Research (EDGAR), with the Vulcan Product, and with estimates derived from state fuel consumption statistics reported by the Federal Highway Administration (FHWA). Our model differs from FHWA estimates by less than 8.5% on average, and is within 5% of Vulcan estimates. We found that EDGAR estimates systematically exceed FHWA by an average of 22.8%. Panel regression analysis of per-mile CO2 emissions on population density at the town scale shows a statistically significant correlation that varies systematically in sign and magnitude as population density increases. Population density has a positive correlation with per-mile CO2 emissions for densities below 2000 persons km(-2), above which increasing density correlates negatively with per-mile emissions.

Right ventricular (RV) failure is a complex problem with poor outcomes. Diagnosis requires a high degree of clinical suspicion, because many of the signs and symptoms of this condition are nonspecific and can be acute or chronic. Identification of the underlying aetiology, which can include pulmonary hypertension, cardiomyopathy, myocardial infarction, congenital or valvular heart disease, and sepsis, is essential. Echocardiography is the technique of choice for first-line assessment, but cardiac MRI is the current gold standard for anatomical and functional assessment of the right ventricle. Therapy for RV failure should be directed at the underlying cause, although management of symptoms is also important. Therapeutic options range from pharmacological treatment to mechanical RV support and heart transplantation. The complex 3D geometry of the right ventricle and its intricate interactions with the left ventricle have left many questions about RV failure unanswered. However, promising new targeted therapies are under development and mechanical support is becoming increasingly feasible. The next decade will be an exciting time for advances in our understanding and management of RV failure.