Search

An airborne lidar was used to study the smoke plume from the burning of a controlled oil spill on the ocean. The ratio of the amount of light (at a wavelength, λ, of 0.532 u.m) backscattered by the smoke to the amount of light extinguished by the smoke was determined by measuring the strength of a laser beam after it had passed through the smoke plume, been reflected from the ocean, and passed through the smoke plume again, and comparing this to the strength of the laser beam reflected directly from the ocean. The optical depth of the smoke (at λ = 0.532 µm) was typically between 0.2 and 0.5. The mass fluxes of smoke particles that passed through four vertical cross sections of the (nonsteady state) smoke plume were estimated from lidar measurements to be 142, 175, 423, and 414 g

Airborne measurements of aerosol light-scattering efficiencies are presented for a portion of the northeast Atlantic seaboard of the United States during July 1993. The measurements suggest a value for the sulfate light-scattering efficiency in the range 2.2-3.2 m{sup 2} g{sup -1}, which is lower than the value used in recent modeling assessments of the climate impact of aerosols. In general, the sulfate light-scattering efficiency decreased with increasing altitude in a manner consistent with concurrent measurements of aerosol size distributions. Some limited measurements of cloud condensation nuclei and sea-salt particles are also presented. 28 refs., 8 figs., 4 tabs.

The American Society of Echocardiography (ASE) recognizes that cardiac sonographers are frequently multiskilled and multicredentialed. It is the position of the ASE that, above all, persons who perform cardiac ultrasonography should be fully trained and credentialed in cardiac sonography. If a person is multiskilled (practices another health-related discipline), he or she should be appropriately trained and credentialed in that discipline as well. Possession of multiple credentials provides some evidence that the person has met specific minimum competencies in those areas.This position supports effective, efficient, and high-quality patient care.