Effectiveness of an intervention to increase construction workers' use of hearing protection

In this project we tested the effectiveness of a theory-based intervention (video, pamphlets, and guided practice session) to increase the use of hearing protection devices (HPDs) among Midwestern construction workers and a national group of plumber/pipefitter trainers. Posttest measures were collected 10-12 months following this intervention. Pender's Health Promotion Model (1987) provided the conceptual basis for development of the training program. A total of 837 high-noise-exposed workers were included in the analysis: 652 regional Midwestern construction workers and 185 national plumber/pipefitter trainers. Effectiveness of the intervention was determined through the sequence of analyses recommended by Braver and Braver (1988) for the Solomon Four-Group Design. Analysis of variance and covariance of postintervention use and intention to use HPDs and a meta-analytic test were done. These analyses indicated that the intervention significantly increased use of HPDs but had no effect on intention to use HPDs in the future. Pretesting had no effect on use. Actual or potential applications of this research include guidance in the development of successful theory-based interventions to increase use of HPDs.     

Radioprotectant Activity of Dicopper(II) Tetrakis(3,5- Diisopropylsalicylate) and Manganese(II) bis(3,5- Diisopropylsalicylate) Alone and in Combination

Dicopper(ll) tetrakis(3,5-diisopropylsalicylate), (Cu(II)(2)(3,5-DIPS)(4), manganese(II) bis(3,5-diisopropylsalicylate), Mn(II)3,5-DIPS)(2) or combinations of them were used to treat gamma-irradIated mice in examining the possibility that combination treatments might be more effective in increasing survival than treatment with either complex alone. Doses of 0, 10, 20, or 40 mumol of each complex per kilogram of body mass were administered subcutaneously in a factorial design before 9 Gy gamna irradiation, an LD(90) dose of irradiation. Doses of 0, 10, 20, or 40 mumol Cu(II)(2)(3, 5-DIPS)(4) per kg of body mass produced 12, 28, 28, or 36 % survival, respectively, while doses of 0, 10, 20, or 40 mumol (II)(3), 5-DIPS)(2) per kg of body mass prduced 12, 36, 20, or 24 % survival, respectively. However, the combination of 20 mumol Cu(II)(2)(3, 5-DIPS)(4) and 10 mumol Mn(II)(3, 5-DIPS)(2) produced the greatest survival, 48 %, which was 300 % greater than vehicle-treated mice (P=0.01). It is concluded that specific combination treatments can be used to maximize survival of lethally irradiated mice.     

Characteristics of different nucleic acid staining dyes for DNA fragment sizing by flow cytometry

An efficient and reliable double-stranded DNA (dsDNA) staining protocol for DNA fragment sizing by flow cytometry is presented. The protocol employs 0.8 microM of PicoGreen to label a wide range of DNA concentrations (0.5 ng/mL to 10,000 ng/mL) without regard to the solution dye/bp ratios and without initial quantification of the DNA analyte concentration. Using a combination of spectrofluorometry and flow cytometry experiments, we found that PicoGreen exhibited better overall performance than all the tested dsDNA binding dyes, such as TOTO-1. Fluorometric titration revealed that typical DNA staining protocols designed on the basis of the dye/bp ratio were highly dependent upon the DNA concentration for optimal results. PicoGreen was the least sensitive to the solution dye/bp ratio and was highly fluorescent in the presence of dsDNA. Using this new protocol, accurate histograms of HindIII digested lambda DNA were demonstrated for DNA concentrations ranging from 5 to 2000 ng/mL, and for dye/bp ratios from 106:1 to 1:4 at 0.8 microM of PicoGreen. The new one-step protocol is broadly applicable to any sensitive, laser-induced fluorescence method for detection of nucleic acids.     

Zinc binding drives the folding and association of the homo-trimeric gamma-carbonic anhydrase from Methanosarcina thermophila

Carbonic anhydrase from the archeon Methanosarcina thermophila (Cam) is a homo-trimeric enzyme, the left-handed beta-helical subunits of which bind three catalytic Zn(2+) ions at symmetry-related subunit interfaces. The observation of activity for holo-Cam at nanomolar concentrations provides a minimal estimated free energy of folding and assembly of the trimeric holo-complex of approximately 70 kcal (mol trimer)(-1) at standard state. Although the direct measurement of stability by chemical denaturation was precluded by the irreversible unfolding of the holo-enzyme, the reversible unfolding of metal-free apo-Cam is well described by a three-state model involving the folded apo-trimer, the folded monomer and the unfolded monomer. The monomer is estimated to have a stability of 4.0 +/- 0.3 kcal (mol monomer)(-1). The association to form apo-trimer contributes 13.2 +/- 0.4 kcal (mol trimer)(-1), a value confirmed by analytical ultracentrifugation measurements. Far- and near-UV circular dichroism data show a progressive increase in secondary and tertiary structure as the apo-monomer is converted to holo-trimer. The literature value for the free energy of binding of one Zn(2+) ion to a canonical active site, 16.4 kcal mol(-1), is consistent with the presumption that the >45 kcal (mol trimer)(-1) generated by the binding of three ions represents the major contribution to the stability of the holo-trimeric Cam.     

High-energy,efficient, 30-Hz ultraviolet laser sources for airborne ozone-lidar systems

Two compact, high-pulse-energy, injection-seeded, 30-Hz frequency-doubled Nd:YAG-laser-pumped Ti: sapphire lasers were developed and operated at infrared wavelengths of 867 and 900 nm. Beams with laser pulse energy >30 mJ at ultraviolet wavelengths of 289 and 300 nm were generated through a tripling of the frequencies of these Ti:sapphire lasers. This work is directed at the replacement of dye lasers for use in an airborne ozone differential absorption lidar system. The ultraviolet pulse energy at 289 and 300 nm had 27% and 31% absolute optical energy conversion efficiencies from input pulse energies at 867 and 900 nm, respectively.     

Color and defective color vision as factors in the conspicuity of signs and signals

The conspicuity of road traffic signs and signals for a group of observers with the color vision defect of deuteranopia is compared with that for a control group of observers with normal color vision. Conspicuity was measured by the proportion of reports of target objects detected in 300-ms presentations of projected slides of road scenes. There were two instructions, one designed to measure attention conspicuity and the other, search conspicuity. The attention conspicuity of red, orange, and green color-coded traffic control devices was significantly less for deuteranopes than for the observers with normal color vision, but this was not true for yellow and blue color-coded signs. This result is consistent with our understanding of the color perceptions of deuteranopes. The reduction of conspicuity was not so great for the search conspicuity condition. We conclude that redundant color coding does contribute to the conspicuity of signs and signals and that deuteranopes--and probably those with other severe forms of defective color vision--have a significantly reduced ability to notice colored targets, such as road signs and signals, in complex visual environments. The actual and potential application of this work is in the design of signs so they are conspicuous, especially when the user group includes people with defective color vision.     

Integrated contour detection and pose estimation for fluoroscopic analysis of knee implants

With fluoroscopic analysis of knee implant kinematics the implant contour must be detected in each image frame, followed by estimation of the implant pose. With a large number of possibly low-quality images, the contour detection is a time-consuming bottleneck. The present paper proposes an automated contour detection method, which is integrated in the pose estimation. In a phantom experiment the automated method was compared with a standard method, which uses manual selection of correct contour parts. Both methods demonstrated comparable precision, with a minor difference in the Y-position (0.08 mm versus 0.06 mm). The precision of each method was so small (below 0.2 mm and 0.3 degrees) that both are sufficiently accurate for clinical research purposes. The efficiency of both methods was assessed on six clinical datasets. With the automated method the observer spent 1.5 min per image, significantly less than 3.9 min with the standard method. A Bland-Altman analysis between the methods demonstrated no discernible trends in the relative femoral poses. The threefold increase in efficiency demonstrates that a pose estimation approach with integrated contour detection is more intuitive than a standard method. It eliminates most of the manual work in fluoroscopic analysis, with sufficient precision for clinical research purposes.     

Effects of varying the threshold of alarm systems and workload on human performance

The purpose of this research was to investigate the effects of varying the threshold of alarm systems and workload on human response to alarm signals and performance on a complex task. A receiver operating characteristic (ROC) curve was selected to reflect the sensitivity of the alarm system. The threshold of the alarm system was manipulated by changing the value of beta along the ROC curve. A total of 84 students participated in experiment 1 and 48 students participated in experiment 2. Participants performed a compensatory-tracking, a resource management and a monitoring task. As expected, results showed that participants responded significantly faster to true alarm signals when they were using the system with the highest threshold under low-workload conditions. Results also indicated that changing the threshold of the alarm system had a significant effect on overall performance and this effect was greater under high-workload conditions. However, contrary to expectations, the highest level of performance was achieved by setting the threshold at a low level. Results from both experiments revealed that the advantage of faster alarm reaction time as a result of increasing the system's threshold was lost because of its increased probability of missed events.