Airborne differential absorption lidar system for measurements of atmospheric water vapor and aerosols.

An airborne differential absorption lidar (DIAL) system has been developed at the NASA Langley Research Center for remote measurements of atmospheric water vapor (H(2)O) and aerosols. A solid-state alexandrite laser with a 1-pm linewidth and > 99.85% spectral purity was used as the on-line transmitter. Solid-state avalanche photodiode detector technology has replaced photomultiplier tubes in the receiver system, providing an average increase by a factor of 1.5-2.5 in the signal-to-noise ratio of the H(2)O measurement. By incorporating advanced diagnostic and data-acquisition instrumentation into other subsystems, we achieved additional improvements in system operational reliability and measurement accuracy. Laboratory spectroscopic measurements of H(2)O absorption-line parameters were perfo med to reduce the uncertainties in our knowledge of the absorption cross sections. Line-center H(2)O absorption cross sections were determined, with errors of 3-6%, for more than 120 lines in the 720-nm region. Flight tests of the system were conducted during 1989-1991 on the NASA Wallops Flight Facility Electra aircraft, and extensive intercomparison measurements were performed with dew-point hygrometers and H(2)O radiosondes. The H(2)O distributions measured with the DIAL system differed by ≤ 10% from the profiles determined with the in situ probes in a variety of atmospheric conditions.

Ozone and aerosol changes during the 1991-1992 airborne arctic stratospheric expedition.

Stratospheric ozone and aerosol distributions were measured across the wintertime Arctic vortex from January to March 1992 with an airborne lidar system as part of the 1992 Airborne Arctic Stratospheric Expedition (AASE II). Aerosols from the Mount Pinatubo eruption were found outside and inside the vortex with distinctly different distributions that clearly identified the dynamics of the vortex. Changes in aerosols inside the vortex indicated advection of air from outside to inside the vortex below 16 kilometers. No polar stratospheric clouds were observed and no evidence was found for frozen volcanic aerosols inside the vortex. Between January and March, ozone depletion was observed inside the vortex from 14 to 20 kilometers with a maximum average loss of about 23 percent near 18 kilometers.

Traumatic left ventricular false aneurysm with significant regurgitation from left ventricular outflow tract to left atrium: delineation by two-dimensional and color flow Doppler echocardiography.

A 22-year-old man was asymptomatic 23 months after an automobile accident but had clinical evidence of progressive mitral insufficiency. Two-dimensional and color flow Doppler echocardiography demonstrated a false aneurysm adjacent to the left ventricular outflow tract and significant regurgitation of blood through a traumatic channel from the left ventricular outflow tract to the left atrium. The patient underwent successful surgical closure of the false aneurysm and repair of the traumatic left atrial regurgitation.

NASA multipurpose airborne DIAL system and measurements of ozone and aerosol profiles.

An airborne differential absorption lidar (DIAL) system has been developed for the remote measurement of gas and aerosol profiles in the troposphere and lower stratosphere. The multipurpose DIAL system can operate from 280 to 1064 nm for measurements of ozone, sulfur dioxide, nitrogen dioxide, water vapor, temperature,pressure, and aerosol backscattering. The laser transmitter consists of two narrow linewidth Nd: YAG pumped dye lasers with automatic wavelength control. The DIAL wavelengths are transmitted with a 00-,usec temporal separation to reduce receiver system complexity. A coaxial receiver system is used to collect and optically separate the DIAL and aerosol lidar returns. Photomultiplier tubes detect the backscattered laser returns after optical filtering, and the analog signals from three tubes are digitized and stored on high-speed magnetic tape. Real-time gas concentration profiles or aerosol backscatter distributions are calculated and displayed for experiment control. Operational parameters for the airborne DIAL system are presented for measurements of ozone, water vapor, and aerosols in the 290-, 720-, and 600-nm wavelength regions, respectively. The first ozone profile measurements from an aircraft using the DIAL technique are discussed in this paper. Comparisons between DIAL and in situ ozone measurements show agreement to within +/-5 ppbv in the lower troposphere. Lidar aerosol data obtained simultaneously with DIAL ozone measurements are presented for a flight over Virginia and the Chesapeake Bay. DIAL system performance for profiling ozone in a tropopause folding experiment is evaluated, and the applications of the DIAL system to regional and global-scale tropospheric investigations are discussed.

Hemolysis induced by cefazolin and cephalothin in a patient with penicillin sensitivity.

A patient with penicillin sensitivity, who had never received a cephalosporin antibiotic previously, developed anemia and spherocytosis following the administration of cefazolin. Hemolysis abated when the drug was discontinued on the fourth day, and recurred on day six when cephalothin therapy was begun. IgG and complement components were present on the patient's erythrocytes, and IgG antibodies in her serum reacted with normal red blood cells which had been coated with benzylpenicillin, cefazolin or cephalothin. Antibodies to cephalothin-coated red blood cells were removed partially by incubating her serum with either benzylpenicillin or cefazolin. Complement-fixing IgG antibodies which reacted with red blood cells coated by cefazolin, cephalothin, and benzylpenicillin were considered to be responsible for hemolysis during the administration of cefazolin and, subsequently, cephalothin. The patient recovered completely following discontinuation of antibiotics, transfusion of red blood cells, and treatment with glucocorticoids. It is concluded that hemolysis may occur during therapy with cefazolin, as well as cephalothin, and may develop rapidly in a patient with penicillin sensitivity.

Inhibition of H+ secretion in the frog gastric mucosa by ATP and related compounds.

Addition of adenosine triphosphate (ATP) to the nutrient (submucosal-facing) solution of the histamine-stimulated in vitro frog (Rana pipiens) gastric mucosa produces a marked reduction in the H+ secretory rate and an increase in transmucosal potential difference (PD) and resistance in both Cl- and Cl-free media. The effects are reversible upon removal of ATP. The threshold concentration is between 1 and 2 mM, and 5 mM produce maximal inhibition. It is shown that the effects of ATP are not due to a change in pH or osmolarity of the nutrient fluid, or to a decrease in the Ca2+ and/or Mg2+ activities of the nutrient fluid. It is also shown that the inhibitory action of ATP is not dependent on a chelation complex between Ca2+ or Mg2+. Adenosine diphosphate also produces effects essentially the same as ATP whereas 5'-adenosine monophosphate and adenosine produce relatively little or no change.