Spectral analysis of tropospheric aerosol measurements obtained with a new fast response sensor.

A new fast response sensor was used in aircraft studies of fluctuations in the size distributions of tropospheric aerosol and their relation to fluctuations of trace gas concentrations and light scattering coefficients. Spectral analysis of data upwind of Buffalo, New York, and Houston, Texas, suggests important roles for atmospheric turbulence and chemical reaction in aerosol fluctuations.

A comprehensive noise survey of the S-70A-9 Black Hawk helicopter.

PURPOSE: This paper reports the results of a comprehensive noise survey of the Sikorsky S-70A-9 Black Hawk helicopter environment and provides an assessment of the hearing protection devices worn by Australian Army personnel exposed to that environment. METHODS AND RESULTS: At-ear noise levels were measured at 4 positions in the cabin of the Black Hawk under various flight conditions and at 13 positions outside the Black Hawk under various ground running conditions using the Head Acoustic Measurement System (Head, GmbH). The attenuation properties of the hearing protection devices (HPDs) normally worn by aircrew and maintenance crews (the ALPHA helmet and the Roanwell MX-2507 Communications headset) were also assessed. At-ear sound pressure levels that would be experienced by personnel wearing their normal HPDs were determined at the positions they would normally occupy in and around the aircraft. CONCLUSION: Results indicate that HPDs do not provide adequate hearing protection to meet current hearing conservation regulations which allow a permissible noise exposure of 85 dB(A) for an 8-h day.

Back pain in Australian military helicopter pilots: a preliminary study.

BACKGROUND: Several studies have highlighted the problem of back pain among helicopter pilots, but few have controlled for potential confounding factors in their analyses, or sought to examine the effects of back pain on operational readiness and flying performance. There have been no previous studies of the prevalence of back pain among Australian military pilots. METHODS: The prevalence, risk factors, and consequences of low back pain were assessed in a cross-sectional survey of 200 Australian military helicopter pilots by self-completion questionnaire. RESULTS: Responses were received from 131 (66%) of available pilots. The overall prevalence of reported back pain was 64% (95% CI 56%-72%), with a further 28% of pilots describing back discomfort while flying. More than half the pilots (55%) indicated that back pain had interfered with their concentration while flying, with 16% reporting that they had hurried flying missions because of pain. A minority of pilots (7%) had refused to fly because of back problems. After adjusting for age, education, BMI, posture and numbers of hours flown, multiple logistic regression modelling indicated that a prior history of back injury was the most significant predictor of back pain among rotary wing pilots (OR 2.63, 95% CI 1.11-6.23). CONCLUSIONS: We conclude that the prevalence of back pain in Australian military helicopter pilots is unacceptably high and may be limiting operational readiness, pilot performance, flying safety, and pilot health. Urgent attention needs to be given to improved ergonomic design in aircraft, and both back pain prevention and back injury rehabilitation programs.

Metal accumulation and sublethal effects in the sea anemone, Aiptasia pallida, after waterborne exposure to metal mixtures.

The marine environment is subjected to contamination by a complex mixture of metals from various anthropogenic sources. Measuring the biological responses of organisms to a complex mixture of metals allows for examination of metal-specific responses in an environmentally realistic exposure scenario. To address this issue, the sea anemone, Aiptasia pallida was exposed to a control and a metal mixture (copper, zinc, nickel, and cadmium) at three exposure levels (10, 50, and 100 µg/L) for 7 days. Anemones were then transferred to metal-free seawater for an additional 7 days after the metal exposure to assess metal depuration and recovery. Metal accumulation, activity of the enzymes catalase, glutathione reductase, and carbonic anhydrase, as well as, cell density of the symbiotic zooxanthellae were measured over 14 days. Metal accumulation in A. pallida occurred in a concentration dependent manner over the 7-day exposure period. Altered enzyme activity and tentacle retraction of the host, as well as decreased zooxanthellae cell density were observed responses over the 7 days, after exposure to a metal concentration as low as 10 µg/L. Metal depuration and physiological recovery were dependent on both the metal and the exposure concentration. Understanding how A. pallida and their symbionts are affected by metal exposures in the laboratory may allow better understanding about the responses of symbiotic cnidarians in metal polluted aquatic environments.

The role of patients' expectations and goals in the behavioral and pharmacological treatment of obesity.

OBJECTIVE: To investigate weight loss expectations and goals among obese treatment seekers and to examine the relationships of these expectations and goals to treatment outcomes. METHOD: Participants were 180 obese men and women (age 43.8+/-10.1 years; body mass index 37.6+/-4.2 kg/m(2)) who received one of four-year-long treatments that combined behavioral and pharmacological methods. Before treatment, they reported the amount of weight they realistically expected to lose after 4, 12, 26 and 52 weeks of treatment, as well as their ultimate weight loss goals. Expectations and goals were compared across treatment groups and examined in relation to previous weight loss efforts, weight loss and regain in treatment, attrition, satisfaction with treatment and mood. RESULTS: Participants in all treatment groups expected reductions at week 52 that were significantly greater than the 5-15% of initial weight they were told was realistic and significantly more than they had ever lost before. Weight loss expectations were unrelated to achieved weight loss in all groups but one, in which greater expectations were associated with greater losses. Failure to meet weight loss expectations for the first 26 weeks of treatment was related to lower satisfaction ratings, but was not related to weight regain or attrition over the next 26 weeks. Symptoms of depression were reduced from baseline, regardless of whether participants achieved or failed to achieve their expected weight losses. CONCLUSION: Across groups, we observed no negative consequences of having (and failing to meet) unrealistic expectations for weight loss.

Propagation of laser breakdown and detonation waves in transparent droplets.

A computer model is used to study recent experiments investigating laser-induced plasma formation and explosion of single liquid aerosol droplets. The model accounts for the formation and evolution of the plasma and the resulting fluid flow; it does not account for the initial breakdown. The model shows all the qualitative features of the experiment, including laser-supported detonation waves, which at high laser intensities rapidly convert the whole droplet into a plasma. In addition, quantitative agreement with measured velocities has been obtained to within approximately 50%.

Explosive vaporization of single droplets by lasers: comparison of models with experiments.

A computer model of the explosive vaporization of single water droplets by pulsed CO(2)-laser radiation is compared with the relevant experiments. The model shows excellent quantitative agreement with the experiments, to our knowledge the first time such agreement has been observed. The importance of fluid mechanics during the pulse is demonstrated, and a second computer model illustrates how a spherically symmetric explosion can evolve even under conditions of nonuniform heating. The two models reconcile the differences between predictions made by Mie theory and observations of droplet heating.

Laser evaporation of droplets.

A rigorous theoretical development is given for isobaric radial droplet evaporation (IRDE) induced by laser radiation. This rigorous development in the form of a computer code, IRDE is used to assess the accuracy of previous approximate theories for the description of this process as well as to derive a new and improved approximate theory.

Laser beam propagation in an evaporating polydisperse aerosol.

The effect of polydispersity on laser beam propagation through an evaporating aerosol is studied theoretically in the single scattering approximation. The general theory is discussed. Evolution of the size distribution due to laser-induced evaporation in a spatially homogeneous system is then examined. The character of a polydisperse aerosol's evolution due to laser-induced evaporation is shown to differ markedly from that found in ordinary thermal evaporation; among other unusual features, at higher beam intensities, the size distribution is found first to narrow and subsequently to broaden. Laser beam propagation in a polydisperse aqueous fog is simulated. The penetration time through a fog for a model monodisperse fog is found to be substantially larger than that found for the correct polydisperse fog. A temperature pulse has been shown to propagate through a fog with a maximum value asymptotically decreasing with time to a constant value.

Effect of coagulation on extinction in an aerosol plume propagating in the atmosphere.

Model studies based on the K-theory diffusion assumption have been carried out on aerosol plumes issuing from a crosswind line source in which advection, vertical diffusion, coagulation, sedimentation, and dry deposition are occurring. Procedures are described and a few typical results are presented. It is shown that in appropriate conditions coagulation can play an important role in altering extinction in the plume. An important coupling effect between coagulation and sedimentation/deposition has been demonstrated. In a coagulating plume it is found that total particle mass concentration cannot be inferred from measurements of extinction without a detailed consideration of the effects of coagulation. In realistic atmospheric simulations isopleths of extinction in the plume cross section show complex forms resulting from the wind gradient and its interactions with vertical diffusion and the coagulation and sedimentation/deposition processes.

Charged aerosol particles and air pollution.

Possible environmental effects and the importance of charged aerosol particles are examined. Some calculations of the evolution of the charge distribution of the atmospheric aerosol are presented. Several possible environmental effects of particle charge are noted including effects on particle coagulation, dry deposition, and deposition in the lung. Finally some problems in aerosol charging are reviewed as they pertain to various technical operations in air pollution control.

The effects of 6 weeks training on the physical fitness of female recruits to the British army.

The purpose of this study was to evaluate the influence of British army recruit training on the physical fitness and strength of female recruits. A total of 73 females (aged 17-23 years) of a single intake of Women's Royal Army Corps (WRAC) recruits were tested at the beginning and end of their 6-week recruit training programme at the WRAC training centre, Guildford. The battery of tests comprised the maximal cycle time for a standard NATO test as an indirect method of determination of maximal oxygen intake (VO2 max) using a cycle ergometer; maximal isometric hand grip strength (Max Grip); maximal isometric 38 cm upright pull strength (Max 38) and maximal incremental dynamic lift to 152 cm (IDL 152). In addition, body-weight and the sum of biceps, triceps, suprailiac and subscapular skinfold thicknesses were measured in order to assess alterations in fat-free mass and percentage of body fat (BF). The recruits responded to training with significant increases in mean VO2 max from 45.7 ml kg-1 min-1 (SD = 5.2) to 46.7 ml kg-1 min-1 (SD = 4.4) or 2.2% (p < .05), mean Max Grip from 263.1 N (SD = 52.2) to 304.9 N (SD = 54.0) or 15.9% (p < 0.001) and mean IDL 152 from 328.0 N (SD = 78.1) to 361.2 N (SD = 74.6) or 10.1% (p < 0.001). There was a significant increase in the mean body-weight of 0.61 kg or 1% (p < 0.05), mean fat-free mass of 1.05 kg or 2.4% (p < 0.001), and a significant reduction in the mean % BF by 3.3% (p < 0.001). It is concluded that female recruit training in the British army is effective in terms of increasing aerobic fitness, physical strength and fat-free mass and in reducing the percentage of body fat.

Time-resolved Raman spectroscopy from reacting optically levitated microdroplets.

Time-resolved Raman spectroscopy is evaluated as a tool for studying reactions in aerosol microdroplets. As a test reaction, the absorption of D(2)O vapor by an optically levitated glycerol droplet is considered. With the present apparatus, time scales of the order of 1 s have been resolved. By considering the relative amplitude of various features, the composition of the suspended droplet can be estimated as a function of time. In addition, for the D(2)O-glycerol system the average temperature of the optically levitated droplet can be deduced.