Black carbon aerosol number and mass concentration measurements by picosecond short-range elastic backscatter lidar.

Black carbon aerosol emissions are recognized as contributors to global warming and air pollution. There remains, however, a lack of techniques to remotely measure black carbon aerosol particles with high range and time resolution. This article presents a direct and contact-free remote technique to estimate the black carbon aerosol number and mass concentration at a few meters from the emission source. This is done using the Colibri instrument based on a novel technique, referred to here as Picosecond Short-Range Elastic Backscatter Lidar (PSR-EBL). To address the complexity of retrieving lidar products at short measurement ranges, we apply a forward inversion method featuring radiometric lidar calibration. Our method is based on an extension of a well-established light-scattering model, the Rayleigh-Debye-Gans for Fractal-Aggregates (RDG-FA) theory, which computes an analytical expression of lidar parameters. These parameters are the backscattering cross-sections and the lidar ratio for black carbon fractal aggregates. Using a small-scale Jet A-1 kerosene pool fire, we demonstrate the ability of the technique to quantify the aerosol number and mass concentration with centimetre range-resolution and millisecond time-resolution.

Comparison of patient and caregiver perception of pain from commonly performed accident and emergency services procedures.

OBJECTIVE: To compare the perception by naive patients, emergency services clinicians and nurses, of healthcare-induced pain for procedures performed frequently by accident and emergency services. METHODS: A prospective, three-part anonymous survey, given to caregivers and patients at arrival accident and emergency services. The primary endpoint was the a priori estimated pain score for 10 procedures performed frequently by accident and emergency services. The same estimation was performed with the 'willingness to pay' method (amount allocated a priori to avoid this pain). RESULTS: Fifty surveys were analyzed in each group, with a significant difference for pain perception between caregivers and patients concerning four procedures: local anesthesia, fracture or dislocation reduction, dressing change and abscess incision. Caregivers always overestimated pain scores compared with patients. No difference was noted for the remaining five procedures: intravenous line insertion and removal, urethral catheterization, wound suture and nasogastric intubation. CONCLUSION: Caregivers should be aware of the most feared procedures by patients to establish pre-emptive analgesia when possible, inform patients and achieve reassurance.