Conduit artery structure and function in lowlanders and native highlanders: relationships with oxidative stress and role of sympathoexcitation

Research detailing the normal vascular adaptions to high altitude is minimal and often confounded by pathology (e.g. chronic mountain sickness) and methodological issues. We examined vascular function and structure in: (1) healthy lowlanders during acute hypoxia and prolonged ( 2 weeks) exposure to high altitude, and (2) high-altitude natives at 5050 m (highlanders). In 12 healthy lowlanders (aged 32 ± 7 years) and 12 highlanders(Sherpa; 33 ± 14 years) we assessed brachial endothelium-dependent flow-mediated dilatation(FMD), endothelium-independent dilatation (via glyceryl trinitrate; GTN), common carotid intima–media thickness (CIMT) and diameter (ultrasound), and arterial stiffness via pulse wave velocity (PWV; applanation tonometry). Cephalic venous biomarkers of free radical-mediated lipid peroxidation (lipid hydroperoxides, LOOH), nitrite (NO2 –) and lipid soluble antioxidants were also obtained at rest. In lowlanders, measurements were performed at sea level (334 m) and between days 3–4 (acute high altitude) and 12–14 (chronic high altitude) following arrival to 5050 m. Highlanders were assessed once at 5050 m. Compared with sea level, acute high altitude reduced lowlanders’ FMD (7.9 ± 0.4 vs. 6.8 ± 0.4%; P = 0.004) and GTN-induced dilatation (16.6 ± 0.9 vs. 14.5 ± 0.8%; P = 0.006), and raised central PWV (6.0 ± 0.2 vs. 6.6 ± 0.3 m s−1; P = 0.001). These changes persisted at days 12–14, and after allometricallyscaling FMD to adjust for altered baseline diameter. Compared to lowlanders at sea level and high altitude, highlanders had a lower carotid wall:lumen ratio ( 19%, P 0.04), attributable to a narrower CIMT and wider lumen. Although both LOOH and NO2 – increased with high altitude in lowlanders, only LOOH correlated with the reduction in GTN-induced dilatation evident during acute (n = 11, r=−0.53) and chronic (n = 7, r=−0.69; P 0.01) exposure to 5050 m. In a follow-up, placebo-controlled experiment (n=11 healthy lowlanders) conducted in a normobaric hypoxic chamber (inspiredO2 fraction (FIO2 )=0.11; 6 h), a sustained reduction in FMD was evident within 1 h of hypoxic exposure when compared to normoxic baseline (5.7±1.6 vs. 8.0 ±1.3%; P < 0.01); this decline in FMD was largely reversed following α1-adrenoreceptor blockade. In conclusion, high-altitude exposure in lowlanders caused persistent impairment in vascular function, which was mediated partially via oxidative stress and sympathoexcitation. Although a lifetime of high-altitude exposure neither intensifies nor attenuates the impairments seen with short-term exposure, chronic high-altitude exposure appears to be associated with arterial remodelling

Competition and Prosociality: A Field Experiment in Ghana

Competitive bonuses are commonly used to promote higher productivity in the workplace. Yet, these types of incentives could have negative spillovers on coworkers' prosocial behavior in subsequent tasks. To investigate this question, we conduct a lab-in-the-eld experiment in Ghana. In a between-subjects design, participants complete a real-eort task under a competitive, threshold, or random payment while holding payment dierentials constant across treatments. Before and after, we measure prosociality through a public goods and a social value orientation game. Competition reduces prosociality when the dispersion of payments is high. However, when there is less at stake, competition does not aect prosociality

A model system for the evaluation of individual program plans

Individual Program Plans are an essential component of quality assurance in service delivery to people with an intellectual disability. This paper describes a system for the evaluation of such plans. One hundred and sixty- three plans were analysed from clients being serviced by 11 Community Living Support Services. While the plans prepared by non-government agencies were generally superior, the average level of plan presentation was poor. Only 14% offered any criterion for evaluating performance objectives, the average number of skill building objectives was less then three per plan, and only 39% of plans were current. It is concluded that if Individual Program Plans are to realize their quality assurance potential, the issues of staff resources, staff training in plan preparation and overall professional accountability will need to be addressed

A model system for the construction and evaluation of general service plans

The appropriate delivery of service to people with an intellectual disability can be facilitated with the use of General Service Plans (GSPs). However, the guidelines for their construction are inadequate. This paper provides a suggested content for such plans, a protocol for their evaluation, and an assessment of GSPs in Victoria constructed between 1987 and 1990. It is concluded that the suggested evaluation procedures have face validity and are simple to implement. A large number of GSPs were found to have been inadequately prepared. © 1994, Taylor & Francis Group, LLC. All rights reserved

Betriebsfeste Bemessung von Steckverbindungen in Steuergeräten

Pressfit technology as a cold contacting technology connects the printed circuit board to the external connection of the control module. The main function of the pressfit connection is the transportation of electrical signals and power. Depending on the construction the fixation of the printed circuit board cann occur as a further function. The reliability requirements indicate that these functions are preserved over life time. A design model of the pressfit connection was developed for measuring the functions during cyclic mechanical loads. Furthermore, a suitable test bench was designed for applying the mechanical loads from production and operation. The failure mechanisms and resulting failures which occur under cyclic mechanical loads were acquired with the design model. The focal point was the contact zone because it is as the joint between the pressfit and the plated through hole a possible weak spot. It was shown that the electrical resistance of the contact zone could lead to a functional failure of the pressfit connection because of fretting corrosion in the goss slip mode. A correlation between the mechanical load capacity of the contact zone and the electrical resistance was establsihed. For this, the multi physical functions of the joint were used with the objective to avoid fretting corrosion in gross slip mode during lifetime. A suitable test method to detect the load capacity in three dimensions was developed