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Preparing a schedule for physicians in the emergency room is a complex task, which requires taking into account a large number of (often conflicting) rules, related to various aspects: limits on the number of consecutive shifts or weekly hours, special rules for night shifts and weekends, seniority rules, vacation periods, individual preferences,... In this paper, we present a mathematical programming approach to facilitate this task. The approach models the situation in a major hospital of the Montreal region (approximately 20 physicians are members of the working staff). We show that the approach can significantly reduce the time and the effort required to construct a six-month schedule. A human expert, member of the working staff, typically requires a whole dedicated week to perform this task, with the help of a spreadsheet. With our approach, a schedule can be completed in less than one day. Our approach also generates better schedules than those produced by the expert, because it can take into account simultaneously more rules than any human expert can do.

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Neutral endopeptidase (neprilysin or NEP, EC 3.4.24.11) is a zinc metallo-endopeptidase expressed in many eukaryotic cell types and displaying several important physiological roles. In the brain (and central nervous system), this enzyme is involved in the molecular mechanism of pain by its action in the degradation of enkephalin molecules. In the kidney, NEP is implicated in the degradation of regulatory factors involved in the control of arterial pressure, including atrial natriuretic peptide and bradykinin. In this study we assessed the potential of the fission yeast Schizosaccharomyces pombe to overproduce rabbit NEP and secreted NEP (sNEP, a soluble derivative of this integral membrane protein). Both recombinant NEP and sNEP were produced at high levels (5 mg/l) in this system. Enzymic studies revealed that these recombinant proteins were fully active and exhibit kinetic parameters similar to those of the bona fide enzyme. Immunofluorescence microscopy and enzymic assays demonstrated that recombinant NEP is correctly targeted to the cell membrane. Furthermore, co-immunoprecipitation studies showed that folding intermediates of NEP and sNEP, produced in S. pombe, interact in the endoplasmic reticulum (ER) with binding protein (BiP) and calnexin (Cnx1p). The amount of sNEP coprecipitated with both BiP and Cnx1p augmented when cells were subjected to various stresses causing the accumulation of unfolded proteins in the ER. The interactions of NEP with BiP and Cnx1p were, however, more refractive to the same stresses.

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Levels of airborne asbestos for six Colorado public school facilities with sprayed-on asbestos materials were documented using three analytical techniques. Phase contrast microscopy showed levels up to the thousandths of a fiber per cubic centimeter (f/cc), scanning electron microscopy (SEM) up to the hundredths of a f/cc, and transmission electron microscopy coupled to selected area electron diffraction and energy dispersive X-ray analysis (TEM-SAED-EDXA) up to the tenths of an asbestos f/cc. Phase contrast microscopy was found to be an inadequate analytical technique for documenting the levels of airborne asbestos fibers in the schools: only large fibers which were not embedded in the filter were counted, and asbestos fibers were not distinguished from nonasbestos.

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Accurate and reproducible radon daughter measurements are essential to protect workers in the mining industry and assure compliance with federal regulations. The precision and accuracy of the MDA Model 811 Instant Working Level Meter (IWLM) has been questioned when it is used in a high gamma environment of an underground uranium mine due to the increased statistical uncertainty associated with the background radiations. Comparative side by side sampling at a single underground mine station exhibiting a 3.0 mR/h "gamma background" was conducted utilizing the IWLM, the Kusnetz and the Tsivoglou methods. A total of fifty sets of samples were taken, with half using an unshielded IWLM and the other half using a lead shield to reduce the effect of the high gamma background radiation. IWLM, Kusnetz and "baseline" Tsivoglou measurements were then analyzed. A significantly large error was associated with the IWLM in both the shielded and unshielded data groups.

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The standard method of asbestos sample analysis by phase-contrast microscopy excludes fibers which are below the resolution limits of the light microscope. Electron microscopic studies revealed that fibers in these small size ranges comprise the majority of fibers in asbestos dust. This research was conducted to determine if the development of a mathematical model for predicting concentrations of small fibers (less than 5 microns length) based on phase-contrast concentrations was feasible. The model presented in this paper was evaluated for its practical utility and was determined to be of minimal value; however, it was felt that the development of a reasonably accurate model can be arrived at through continued research.

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This study documented the formaldehyde exposures of a group of veterinary medicine students. It also investigated the feasibility of biologically monitoring the exposures. The biological monitoring was based on the fact that the formaldehyde is metabolized in the body to formic acid, and may then be excreted in the urine. Therefore, exposures to formaldehyde could theoretically create a shift in the formic acid levels in the urine. Normal baseline levels of urinary formic acid were first established for each subject. The baselines of most students were quite variable. Very few exhibited a "tight variability" in their baseline. Next, three sets of pre- and post-exposure urine samples were taken. A series of paired t-tests were run on these "pre" and "post" sets. The results indicated that no significant formic acid shift was seen. A subset of the samples was "corrected" for specific gravity. However, this adjustment did not have an effect upon the relative formic acid levels. In addition, no significant formic acid shift was seen in the adjusted group. Exposure levels of the students were less than 0.5 ppm of formaldehyde. Therefore, the main conclusion of the study was that biological monitoring of formaldehyde exposures (via formic acid shifts) at these low levels was not a feasible technique.

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Aerosol control is a significant problem in agriculture and industry. Two separate studies were conducted to determine the effectiveness of a "negative air ionization" system in aerosol control. The first study was conducted with a turkey "brooder" barn and a control for a six-week period. The second study was conducted with a turkey "grow-out" barn and a control for a twelve-week period. Sampling parameters for both studies included environmental aerosol sampling, ion imbalance measurements, relative humidity, temperature and barometric pressure measurements and daily turkey mortality. Study two also included post study bird weights. Results of sampling parameters were consistent between study one and study two. No significant difference was found between test and control total average aerosol concentration for both studies. Ion imbalance measurements served to indicate that test environments were negatively ionized while control environments experienced normal environmental conditions. Meteorological parameters did not significantly affect aerosol concentrations. Normal variations in bird mortality were observed in the first study, but death rates increased with ionization in the latter. Overall, it was determined that the "negative air ionization" could not be considered as an effective means of aerosol control in turkey rearing confinements.

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Three passive samplers are now commercially available for NO2. This field validation, conducted in an underground mine, attempted to address both the precision and accuracy of the three now commercially available. The probable sources of NO2 were identified as diesel engines and blasting operations. Comparative sampling was conducted with the passive samplers versus the standard "baseline" impingement method. The three NO2 samplers were as follows: 1) PRO-TEK (DuPont); 2) Palmes (MDA); 3) VaporGard (MSA). Three sets of data consisting of impingers and passive sampler results were taken on top of a moving diesel vehicle over a three-day period. An expanded metal screen was welded in a "free standing" plane above the vehicle to serve as a sampling platform. The evaluation of concentration data suggested that correlations of accuracy and precision versus the impinger method were best for the Palmes and VaporGard samplers. The PRO-TEK sampler does not seem to produce accurate data, but it is somewhat precise. Factors of sensitivity, accuracy, precision, cost, ease of analysis, and stability must be weighed.

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Forty-one public schools in Colorado were drawn at random and surveyed for asbestos-containing materials. After bulk samples of possible asbestos materials from the schools were collected and analyzed, the K2 asbestos screening test was used to eliminate samples that did not contain asbestos. Samples with positive results on the K2 test were analyzed by an outside laboratory by polarized light microscopy. The risk of potential exposure presented by these materials was then assessed for each site from which a sample was taken. Of 113 samples collected, results were negative for asbestos for only 10.6 percent by the K2 test. Of the 101 samples for which results were positive, 56 actually contained 1 or more forms of asbestos. Twelve of these 56 samples were from sprayed material; the remaining 44 were from other materials containing asbestos. Of the 41 schools sampled, 31 had asbestos materials in one of more locations. The potential exposure values for these materials ranged from very low to very high, but the majority had high-exposure potentials. Estimates based on the survey of the 41 schools indicated that 63 to 89 percent of the public schools in Colorado have asbestos materials that present potentially serious hazards, not only to the children, teachers, and staff, but also to members of the community who use the school buildings after regular school hours.

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A study was conducted to characterize the aerosol found in turkey rearing confinements, to study biological response to inhalation of the aerosol, and to evaluate a water spray, dust suppression system in one confinement as compared to a control barn. A significant reduction in aerosol concentration in the "sprayed" barn was inferred by many environmental and biological sampling parameters. Similarity of physical and biological factors in both study populations, with the exception of the dust suppression system, implied that a mortality rate increase of 1.74 of control versus "sprayed" barn was directly related to aerosol concentration.

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Accepted practice by most professional industrial hygienists in government and industry is to use "closed-face" filter cassette techniques as standard sampling procedures for the majority of aerosols. A two-phase, field study was conducted to determine whether a gravimetric bias exists between "open" and "closed-face" sampling methods. Phase I involved an in-depth analysis of the potential gravimetric viability as it applies to an industrial paint spray mist, and Phase II was a series of pilot studies, of small sample base, to determine if this phenomena exists over a range of aerosol types. Dusts of wood, grain, cellulose, Portland cement and perlite, welding fumes, and chromic acid mist were sampled in Phase II. Paired breathing zone samples, "open" and "closed-face", 37 mm, 3-piece filter cassettes were utilized in both phases of the study. In both phases of the study, "open-face" concentrations were consistently higher than "closed-face" concentrations, with the exception of cellulose dust. Based on the concentration for both sampling techniques, the data suggests that "closed-face" sampling techniques (4.0 mm inlet diameter) might be size selective against large particles. This could lead to an underestimation of a worker's total aerosol exposure.

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