Performance of optical sensors for cloud measurements deployed by the ARM Aerial Facility during ACE-ENA.

During the Aerosol and Cloud Experiment in the Eastern North Atlantic (ACE-ENA), a variety of in situ optical sensors using shadow imaging, scattering and holography were deployed by the Atmospheric Radiation Measurement (ARM) Aerial Facility to determine cloud properties. Taking advantage of the wide, overlapping range of instrumentation, we compare in situ cloud data from several different measurement methods for droplets up to 100 µm. Data processing was tailored to the encountered conditions, leading to good agreement. Improvements include noise reduction for holography and better out-of-focus correction for shadow imaging. Comparison between direct liquid water content measurements and optical sensors showed better agreement at higher droplet number concentrations (>120/c m 3).

Amazon boundary layer aerosol concentration sustained by vertical transport during rainfall.

The nucleation of atmospheric vapours is an important source of new aerosol particles that can subsequently grow to form cloud condensation nuclei in the atmosphere. Most field studies of atmospheric aerosols over continents are influenced by atmospheric vapours of anthropogenic origin (for example, ref. 2) and, in consequence, aerosol processes in pristine, terrestrial environments remain poorly understood. The Amazon rainforest is one of the few continental regions where aerosol particles and their precursors can be studied under near-natural conditions, but the origin of small aerosol particles that grow into cloud condensation nuclei in the Amazon boundary layer remains unclear. Here we present aircraft- and ground-based measurements under clean conditions during the wet season in the central Amazon basin. We find that high concentrations of small aerosol particles (with diameters of less than 50 nanometres) in the lower free troposphere are transported from the free troposphere into the boundary layer during precipitation events by strong convective downdrafts and weaker downward motions in the trailing stratiform region. This rapid vertical transport can help to maintain the population of particles in the pristine Amazon boundary layer, and may therefore influence cloud properties and climate under natural conditions.

Performance Assessment of Portable Optical Particle Spectrometer (POPS).

Accurate representation of atmospheric aerosol properties is a long-standing problem in atmospheric research. Modern pilotless aerial systems provide a new platform for atmospheric in situ measurement. However, small airborne platforms require miniaturized instrumentation due to apparent size, power, and weight limitations. A Portable Optical Particle Spectrometer (POPS) is an emerged instrument to measure ambient aerosol size distribution with high time and size resolution, designed for deployment on a small unmanned aerial system (UAS) or tethered balloon system (TBS) platforms. This study evaluates the performance of a POPS with an upgraded laser heater and additional temperature sensors in the aerosol pathway. POPS maintains its performance under different environmental conditions as long as the laser temperature remains above 25 °C and the aerosol flow temperature inside the optical chamber is 15 °C higher than the ambient temperature. The comparison between POPS and an Ultra-High Sensitivity Aerosol Spectrometer (UHSAS) suggests that the coincidence error is less than 25% when the number concentration is less than 4000 cm-3. The size distributions measured by both of them remained unaffected up to 15,000 cm-3. While both instruments' sizing accuracy is affected by the aerosol chemical composition and morphology, the influence is more profound on the POPS.

Mini-Mental State Examination is superior to plasma glucose concentrations in monitoring patients with suspected hypoglycaemic disorders during the 72-hour fast.

OBJECTIVE: To determine whether systematic evaluation of cognitive function by the Mini-Mental State Examination (MMSE) allows the objective detection and documentation of cognitive deterioration in patients referred for evaluation of suspected hypoglycaemic disorders by the 72-h fast. DESIGN: Prospective case series. METHODS: In 50 patients referred for evaluation of suspected hypoglycaemic disorders, the MMSE score (maximum 30 points) was assessed at the start and at the end of the fast. RESULTS: The fast was terminated before 72 h in 14 patients because they developed neuroglycopenic symptoms due to hypoglycaemic disorders. Their MMSE score fell from a median of 29 points (range 20-30) at the beginning to 17 points (range 0-24) at the termination of the fast. The score dropped by > or =6 points in all patients with hypoglycaemic disorders. Median (range) plasma glucose concentration at the end of the fast was 2.1 (1.1-2.5) mmol/l. Thirty-six individuals developed no neuroglycopenic symptoms throughout the 72-h fast, their MMSE score remained between 27 and 30 throughout the fast and their median plasma glucose concentration dropped to 2.9 (2-3.6) mmol/l. CONCLUSIONS: Systematic evaluation of cognitive function by the MMSE at the beginning and at the termination of the fast allows objective determination and documentation of the deterioration of the cognitive state in patients with hypoglycaemic disorders. A decline in the cognitive performance by > or =6 points in the MMSE score rather than a distinct plasma glucose concentration should be used as the criterion to terminate the prolonged fast before 72 h.

Case study of modeled aerosol optical properties during the SAFARI 2000 campaign.

We present modeled aerosol optical properties (single scattering albedo, asymmetry parameter, and lidar ratio) in two layers with different aerosol loadings and particle sizes, observed during the Southern African Regional Science Initiative 2,000 (SAFARI 2,000) campaign. The optical properties were calculated from aerosol size distributions retrieved from aerosol layer optical thickness spectra, measured using the NASA Ames airborne tracking 14-channel sunphotometer (AATS-14) and the refractive index based on the available information on aerosol chemical composition. The study focuses on sensitivity of modeled optical properties in the 0.3-1.5 microm wavelength range to assumptions regarding the mixing scenario. We considered two models for the mixture of absorbing and nonabsorbing aerosol components commonly used to model optical properties of biomass burning aerosol: a layered sphere with absorbing core and nonabsorbing shell and the Maxwell-Garnett effective medium model. In addition, comparisons of modeled optical properties with the measurements are discussed. We also estimated the radiative effect of the difference in aerosol absorption implied by the large difference between the single scattering albedo values (approximately 0.1 at midvisible wavelengths) obtained from different measurement methods for the case with a high amount of biomass burning particles. For that purpose, the volume fraction of black carbon was varied to obtain a range of single scattering albedo values (0.81-0.91 at lambda=0.50 microm). The difference in absorption resulted in a significant difference in the instantaneous radiative forcing at the surface and the top of the atmosphere (TOA) and can result in a change of the sign of the aerosol forcing at TOA from negative to positive.

Factors effecting manubrium-regeneration in hydromedusae (Coelenterata).

1. Umbrellar fragments of the leptomedusaCampanularia johnstoni with or without parts of the radial canal demonstrate a gradient in the potential for manubrium regeneration and in regeneration time. 2. Implantation experiments exclude the manubrium as a source of inhibition or induction in the regeneration of another manubrium. One special case of inhibition appears to be due to competition for a common substrate. 3. Medusa fragments consisting of only peripheral umbrella (C-fragments) undergo a considerably different restitution process as compared with fragments including a central portion of the umbrella (A-fragments). Vital stain is seen to disperse in the subumbrellar tissues during this process in C-fragments, whereas vital stain in A-fragments is observed to accumulate and later on is incorporated into the regenerating manubrium. 4. The mesogloea of different-sized A-fragments retains a stable form when freed of its adhering cellular components, after a 12-24 h regeneration period; for C-fragments, however, the same result is not observed until 72 to 96 h after their excision. 5. InPodocoryne carnea the observed gradients in manubrium regeneration can be abolished when the subumbrellar tissues are separated from the mesogloea by collagenase treatment. 6. A model for manubrium regeneration in interradial fragments, based on the influence of tension exerted by the cicatrization process and the counteracting mesogloeal force, is presented and discussed.

Cloud physics lidar: instrument description and initial measurement results.

The new Cloud Physics Lidar (CPL) has been built for use on the NASA ER-2 high-altitude aircraft. The purpose of the CPL is to provide multiwavelength measurements of cirrus, subvisual cirrus, and aerosols with high temporal and spatial resolution. The CPL utilizes state-of-the-art technology with a high repetition rate, a low-pulse-energy laser, and photon-counting detection. The first deployment for the CPL was the Southern African Regional Science Initiative's 2000 field campaign during August and September 2000. We provide here an overview of the instrument and initial data results to illustrate the measurement capability of the CPL.

Dynamics of cytochrome P4502E1 activity in man: induction by ethanol and disappearance during withdrawal phase.

BACKGROUND/AIMS: Chronic ethanol consumption results in the induction of hepatic cytochrome P4502E1 (CYP2E1) in man, which is believed to play an important role in the pathogenesis of alcoholic liver disease. However, the amount and duration of alcohol intake associated with CYP2E1 induction is not known but limited information is available on the disappearance of CYP2E1 following alcohol withdrawal. METHODS: To study these questions, five healthy male volunteers received ethanol daily (40 g/day) over 4 weeks. CYP2E1 induction was monitored by using the chlorzoxazone test before and every week following the start of alcohol ingestion. In addition, CYP2E1 was also determined in five alcoholics 1, 3, 8 and 15 days following ethanol withdrawal and in five patients with non-alcoholic liver disease. RESULTS: A significant CYP2E1 induction occurred 1 week following the ingestion of 40 g ethanol per day and increased further after 4 weeks. The disappearance of CYP2E1 was found to be significant 3 days following ethanol withdrawal and further decreased up to day 8. Thereafter, no significant change occurred and CYP2E1 activities were comparable with those in patients with non-alcoholic liver disease. CONCLUSIONS: These data show a significant and quick induction of CYP2E1 activity, already at moderate alcohol consumption, which may be of importance in the pathogenesis of alcoholic liver disease, of ethanol, drug and vitamin A interactions and in alcohol associated carcinogenesis.