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The purpose of this study was to investigate some of the factors influencing the potential interference caused by water vapor when collecting organic vapors on 100 mg charcoal tubes. Atmospheres containing known concentrations of organic vapors at predetermined relative humidities were produced in a flow dilution system. Atmospheres of the solvents toluene, methyl chloroform, methyl isobutyl ketone (MIBK), cyclohexane, acetone, isopropanol, acetonitrile, ethyl acetate, 1-butanol, and perchloroethylene, were screened at 0 and 90 percent relative humidity to select solvents which exhibited varying degrees of effect of humidity for more detailed study. The solvents toluene, methyl chloroform, MIBK and cyclohexane were studied at concentrations ranging from 50 to 1400 ppm, or 1/4 to 8 times the OSHA 8-hour Permissible Exposure Limit (PEL) concentration which enabled comparison of the different solvents at similar molar concentrations. Water vapor levels of approximately 0, 50, 70, 80 and 90 percent relative humidity at 25(DEGREES)C were tested for each concentration of each solvent. The recoveries obtained for the recommended air volume samples taken at all combinations of solvent concentration and humidity ranged from 0.54 to 1.54. Recoveries from dry air varied around 1.00 for all solvents. The presence of humidity in air when sampling toluene at 50 ppm ( 1/4 PEL) reduced the recovery to an average of 0.79. MIBK recoveries at 50 and 100 ppm (PEL = 100 ppm) were reduced to mean values of 0.61 and 0.70, respectively, by the presence of humidity. The trend in the MIBK data indicates reduced recovery with increasing humidity. The mass of solvent collected at 5% breakthrough was markedly affected by variation in relative humidity and vapor concentration. At 90% RH the mean breakthrough mass was approximately 40% of the mass collected in dry air for all vapor concentrations tested. Treatment of the breakthrough data by the Langmuir equation yielded a mean monolayer vapor volume of 63.2 mL of vapor (gas) per gram of charcoal. The Langmuir model could not account for the observed decrease in adsorption capacity with increasing humidity. Treatment of these data by the Dubinin equation yielded a micropore volume of 0.419 mL/g of liquid per gram of charcoal. The Dubinin and Langmuir data evalutions are consistent with the hypothesis that the reduction in capacity observed is due to a decrease in the rate of surface diffusion of adsorbed vapor into the microporous surface as compared to the rate of bulk transport of vapor in the sample gas stream. (Abstract shortened with permission of author.)

In this study, the authors determined whether mental health status affects the use of general medical services, with and without adjustment for the correlated effects of general health perceptions and physical health status on such use. Data were used from the RAND Health Insurance Experiment, which has information on up to 5 years of use of medical services by a nonelderly, civilian, general population. Health status and other covariates were assessed by self-administered questionnaires at enrollment. In the absence of statistical control for general and physical health status, worse mental health status-whether assessed by a global self-report measure or its two component parts, psychological well-being and psychological distress-significantly increased the use of both inpatient and outpatient general medical services. After controlling for general health perceptions, physical health status, demographic factors, and insurance plan coverage, the effects of mental health status on use are reduced, but not eliminated. Psychological distress and psychological well-being retained independent effects on total medical expenses.

To increase the effectiveness of its people, British Petroleum (BP) initiated a global program of change, altering the way managers and staff work together and communicate. As part of this effort, senior management at BP Exploration (BPX), the arm of the company that finds and develops oil and gas reserves, was determined to achieve a more open culture based on committed teams of people who could engage in open and honest 2-way communication to plan and achieve corporate, business, and individual objectives. Upward feedback was used to meet these objectives, and over 90% of BPX's managers and their staff participated. The upward feedback program sought to provide a safe way for employees to address the performance of their manager. Staff completed a questionnaire addressing the effectiveness of their manager in managing people, then met with him or her to discuss the aggregate results in order to develop ways to overcome problems which were identified. The first run of upward feedback has been completed in BPX involving 1,400 managers, and the feedback meetings have been very positive.