Supporting choices about HIV disclosure in the workplace: A cross-Canada survey of strategies.

Background: People living with human immunodeficiency virus (HIV) often make highly personal decisions about whether or not to disclose their HIV status in the workplace.

Objective: We aimed to determine current practices that support people living with HIV to make workplace disclosure decisions and to understand factors that affect disclosure decision-making.

Methods: Ninety-four people who provide health, social and peer-based services responded to an on-line survey about their experiences supporting workplace disclosure decisions of employees living with HIV.

Wave optics simulation of atmospheric turbulence and reflective speckle effects in CO2 lidar.

Laser speckle can influence lidar measurements from a diffuse hard target. Atmospheric optical turbulence will also affect the lidar return signal. We present a numerical simulation that models the propagation of a lidar beam and accounts for both reflective speckle and atmospheric turbulence effects.

Blue moons and large fires.

Theoretical analysis of simulations of optical effects from the 1950 Canadian forest fires has revealed what conditions are necessary for large fires to cause blue moons and suns. This study shows how large fires can be used to improve our understanding of long range pollution transport on a global scale as well as the evolution of aerosol radiative effects so important to global climate studies. The most important aerosol characteristics are the initial submicron smoke particle concentration and areal extent of the fire and its effect on fire plume dispersion.

Comparisons of meteorological structure parameters in complex terrain using optical and acoustical techniques.

Remotely sensed wind, temperature changes with height, and turbulence have been compared with in situ instrumentation using optical and acoustic techniques across and within valleys. These comparisons have provided data useful in the interpretation of spatial averages inherent in remote sensing with spatial and temporal representativity of point meteorological measurements in complex terrain. Of particular interest in this study was comparison of the optical turbulence derived index-of-refraction structure function C(n) with the acoustically derived temperature structure function C(T) over divergent scales across and within a valley.

Visibility of distant mountains as a measure of background aerosol pollution.

A relationship is developed between the visibility of distant mountains seen from an aircraft and a level of background aerosol pollution for a model atmosphere. It is found that the distance at which Mt. Rainier can be seen on clean-air days, which are typical of background aerosol levels, is consistent with the level of aerosol light-scattering measurements in other background situations.

Blue moon: is this a property of background aerosol?

Stellar extinction measurements made at three astronomical observatories showed that on ~50% of the nights the extinction due to aerosol light scattering increased rather than decreased with increasing wavelength (anomalous extinction) for wavelengths close to 500 nm. This extinction behavior is analyzed in this paper and limits are established for the aerosol characteristics necessary for this phenomenon to exist, including geometric standard deviations, imaginary part of refractive index, mean radius, and gaseous NO(2).

Atmospheric aerosol: does a background level exist?

Measurements of light-scattering made with an integrating nephelometer at Point Barrow, Alaska, and Mount Olympus, Washington, are in agreement in magnitude, and both sets of measurements also are in agreement with other measurements of light-scattering and turbidity made in remote locations. This agreement suggests that a background level of aerosol exists and that the concept of a background is applicable.