The interactive effect of chronic exposure to noise and job complexity on changes in blood pressure and job satisfaction: A longitudinal study of industrial employees.

The hypothesis of this study was that noise exposure level and job complexity interact to affect changes in blood pressure (BP) levels and job satisfaction over 2–4 yrs of follow-up. Results showed that among workers exposed to high noise, those with complex jobs showed increases in BP that were more than double shown by those with simple jobs. Under low noise exposure, there was a small increase in BP for workers with complex jobs but about a 3-fold increase in workers with simple jobs. The prevalence of elevated BP showed a similar trend. Job satisfaction increased among workers with complex jobs but was much less in those exposed to high noise. It was concluded that exposure to occupational noise has a greater negative impact on changes in BP and job satisfaction over time among those performing complex jobs. In contrast, job complexity had a clear beneficial effect for workers exposed to low noise. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Wideband enhancement of television images for people with visual impairments

Wideband enhancement was implemented by detecting visually relevant edge and bar features in an image to produce a bipolar contour map. The addition of these contours to the original image resulted in increased local contrast of these features and an increase in the spatial bandwidth of the image. Testing with static television images revealed that visually impaired patients (n = 35) could distinguish the enhanced images and preferred them over the original images (and degraded images). Most patients preferred a moderate level of wideband enhancement, since they preferred natural-looking images and rejected visible artifacts of the enhancement. Comparison of the enhanced images with the originals revealed that the improvement in the perceived image quality was significant for only 22% of the patients. Possible reasons for the limited increase in perceived image quality are discussed, and improvements are suggested.     

Properties of light reflected from road signs in active imaging

Night vision systems in vehicles are a new emerging technology. A crucial problem in active (laser-based) systems is distortion of images by saturation and blooming due to strong retroreflections from road signs. We quantify this phenomenon. We measure the Mueller matrices and the polarization state of the reflected light from three different types of road sign commonly used. Measurements of the reflected intensity are also taken with respect to the angle of reflection. We find that different types of sign have different reflection properties. It is concluded that the optimal solution for attenuating the retroreflected intensity is using a linear polarized light source and a linear polarizer with perpendicular orientation (with regard to the source) at the detector. Unfortunately, while this solution performs well for two types of road sign, it is less efficient for the third sign type.     

Helicobacter pylori serostatus in backpackers following travel to tropical countries

OBJECTIVE: To investigate the role of heparin in the postreperfusion coagulopathy during liver transplantation with heparinase-guided thromboelastography. DESIGN: A prospective, interventional study. SETTING: A university-affiliated hospital. PARTICIPANTS: Twenty-six patients undergoing orthotopic liver transplantation (OLT). INTERVENTIONS: Blood drawn at five intervals for thromboelastography assessment with native (12 patients) or celite blood (14 patients) compared with simultaneous thromboelastography traces with added heparinase. MAIN RESULTS: In the native samples, the prolonged R (reaction) and K (coagulation) time and decreased alpha angle were corrected in heparinase thromboelastograph traces immediately before reperfusion and 10 minutes postreperfusion. In the celite-accelerated samples, the heparinase traces showed correction of the R and K times and alpha angle only at the 10-minute postreperfusion stage. In seven patients who had thromboelastography performed after protamine administration, there were no differences between celite and heparinase-celite traces. CONCLUSIONS: Heparinase-treated thromboelastography offered compelling evidence for the presence of heparin-like activity after liver graft reperfusion. The objective evidence provided by this modification of thromboelastography-guided protamine administration and was useful in identifying one of the many potential causes of postreperfusion bleeding in patients undergoing OLT.     

Personal and interpersonal predictors of supervisors' avoidance of evaluating subordinates.

Supervisors' decisions about whether to formally evaluate their subordinates for each of 2 consecutive performance appraisal periods were found to be related to a linear combination of the following variables: subordinate's time under current supervisor, subordinate's job experience, subordinate–supervisor trust, supervisor's initiating structure behaviors, and subordinate's confidence in the operation of the performance appraisal system. A follow-up analysis, in which the criterion was the consistency with which subordinates were rated in both performance appraisal periods, suggested that relations among the predictors, relative to the criterion, may be quite complex. This complexity may reflect the decision strategy used by raters to combine information on the focal predictors when deciding whether to evaluate a particular subordinate. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Does Hydride Ion Transfer from Silanes to Carbenium Ions Proceed Via a Rate-Determining Formation of a Silicenium Ion or Via a Rate-Determining Electron Transfer? An Ab Initio Quantum Mechanical Study and a Curve-Crossing Analysis

The hydride transfer reactions from simple silanes to carbenium ions are studied by ab initio calculations. The simplest reaction, H₄Si + CH₃⁺ → H₃Si⁺ + CH₄, is also studied with inclusion of the solvent effect (with the SCRF method) in the ab initio scheme. Under all conditions the preferred mechanism is the synchronous hydride transfer (SHT), which is barrierless in the gas phase but possesses small barriers in solution. The mechanistic alternative involving a rate-determining single electron transfer (SET) step followed by H-atom abstraction is found to be of very high energy. Modelling of the primary isotope effect for the SHT process of H₃SiH(D) + CH₃* → H₃Si⁺ + H₃CH(D) shows that the primary isotope effect is small, between ca. 1.1 and 2.7, for the entire relevant range of Si—H(D) distances (1.5–2.3 Å). Furthermore, the pattern of the computed primary isotope effect shows it to be an insensitive probe of the SHT mechanism. The curve-crossing method is used to model the mechanistic dichotomy. It is shown that the reaction profiles for both SHT and SET arise from an avoided crossing between the ground state and a charge transfer state of the R₃SiH//R′₃C⁺ reactant pair. Thus, in the SHT mechanism a single electron switches sites in synchronicity with bond reorganization, while in SET the electron switch precedes the bond coupling. This avoided bond coupling is the foremost disadvantage of the SET mechanism. The common origin of the avoided crossing elucidates the reason why SHT exhibits characteristics of an electron transfer process without actually being a SET process.     

Civilian-military pooling of health care resources in Haiti: a theory of complementarities perspective

The 2010 Haiti earthquake brought attention to the global need for rapid deployment of disaster relief health care services. In such large-scale disasters, a variety of international organisations provide temporary services until the damaged local health care system recovers. However, the disaster environment can pose operational and temporal challenges that may impede the effectiveness of relief services, and research is needed to provide both theory and methods for improving coordination and collaboration among relief organisations. This study investigates opportunities and barriers for relief organisations to pool complementary resources originating from multiple countries, by examining five case studies that represent the breadth of organizational types, including charter (civilian, military, university-affiliated and public/private), facility type (primary, secondary, and tertiary care), and duration of stay. The study yields a set of research propositions that chart avenues for future studies in this emerging field of research at the intersection of health care humanitarian operations and organisation theory.