Functional Reliability of Structures

A general theoretical foundation of structural system reliability analysis is presented. Both an analytical and a numerical formulation for evaluating a relative reliability measure of a structural system is developed in which general random factors affecting both strength and loading can be included. The reliability of a suspension bridge is analyzed as an example; the effect of dead load, used as a proof load, is also studied.     

Models of transformative learning for social justice: comparative case studies of non-formal development education in Britain and Spain

This paper presents comparative case studies of non-formal development education by non-profit organisations in two European countries. The study aimed to explore the extent to which such activities provide opportunities for transformative learning. The research was qualitative and began with interviews with educators across 14 organisations in Britain and Spain. Case studies were then identified, purposefully selecting interesting non-formal activities. This paper presents four activities and analyses their potential for transformative learning, drawing together ideas from the literature and the cross-case analysis of the perspectives of development education practitioners. By using the framework of transformative learning pedagogies, this research can inform non-formal education with aims regarding social justice in a range of contexts. It is argued that while there are scarce opportunities for sustained non-formal development education, these cases contribute to knowledge by providing examples of how participative methodologies can generate critical thinking and thus offer learning opportunities that are transformational.     

Accuracy in student self-assessment: directions and cautions for research

Student self-assessment is a central component of current conceptions of formative and classroom assessment. The research on self-assessment has focused on its efficacy in promoting both academic achievement and self-regulated learning, with little concern for issues of validity. Because reliability of testing is considered a sine qua non for the validity of assessment interpretations, and research into the human ability to self-evaluate work raises concerns about the quality of students’ judgements, it is sensible to investigate the accuracy of students’ self-assessments. This article reviews relevant literature from educational psychology and psychometrics to define the need for a better understanding of accuracy in self-assessment as well as to identify possible pitfalls in measuring accuracy that could undermine its effectiveness by, for example, trading the focus on formative feedback for summative scoring or rating. The article concludes with recommendations for the design of research on accuracy in self-assessment.     

Paraprotein interference with turbidimetric gentamicin assay

Introduction

Gentamicin due to its low level of resistance and rapid bactericidal activity is commonly used to treat gram-negative bacteria. However, due to its toxic effects it needs to be monitored. To date, no interference has been reported with gentamicin assays.

Materials and methods

A patient with leg cellulitis and sepsis received a single dose of gentamicin and a sample was sent for gentamicin analysis. The sample showed high blank absorbance readings on Beckman DxC800 and DC800 analysers with various dilutions. A second sample was received and analysed on a Roche Cobas system to obtain a result. A third sample was received 107 hours later with the same results and this sample was then analysed neat and post ethanol precipitation on all the turbidimetric assays available on the DxC800 analyser.

Results

The high blank absorbance was observed upon addition of the reactive reagents due to protein precipitation. Although not obvious from the patient protein results, it was shown the presence of high IgM paraprotein, 18.9 g/L (reference range 0.4-2.3 g/L) was the cause of precipitation, giving high blank readings. Of all the other turbidimetric assays, only vancomicin and valproate showed similar high blank absorbance readings. To be able to provide more rapid results it was shown ethanol could be used as a precipitant of proteins in both calibrators and patient samples with acceptable recovery.

Conclusion

IgM paraprotein was identified as the cause of interference with the gentamicin, vancomicin and valproate assays. Protein interference in these assays can be overcome by precipitation with ethanol.Key words: turbidimetry, IgM, paraprotein, interference     

Isometric exercise and cognitive function: an investigation of acute dose–response effects during submaximal fatiguing contractions

The purpose of this study was to explore the dose–response relationship between exercise and cognitive performance using an acute bout of isometric exercise. University students (N = 55) were randomly assigned to control, 30%, 50% and 70% of maximum voluntary handgrip contraction groups. Participants performed a modified Stroop task before and after completion of an isometric handgrip endurance trial at their assigned exercise intensity. Ratings of perceived exertion (RPE) and forearm muscle activation (EMG) showed linear trends of progressively greater RPE and muscle activation at greater exercise intensity levels. Regression analysis showed significant (P < .05) linear degradations in frequency of errors on the Stroop task with increasing exercise intensity. We conclude that performing isometric exercise until exhaustion is associated with reduced cognitive performance and that higher intensity isometric exercise leads to greater performance impairments in a linear dose–response manner.     

Concurrent validation of the Actigraph gt3x+, Polar Active accelerometer,Omron HJ-720 and Yamax Digiwalker SW-701 pedometer step counts in lab-based and free-living settings

Activity monitors are frequently used to assess activity in many settings. But as technology advances, so do the mechanisms used to estimate activity causing a continuous need to validate newly developed monitors. The purpose of this study was to examine the step count validity of the Yamax Digiwalker SW-701 pedometer (YX), Omron HJ-720 T pedometer (OP), Polar Active accelerometer (PAC) and Actigraph gt3x+ accelerometer (AG) under controlled and free-living conditions. Participants completed five stages of treadmill walking (n = 43) and a subset of these completed a 3-day free-living wear period (n = 37). Manually counted (MC) steps provided a criterion measure for treadmill walking, whereas the comparative measure during free-living was the YX. During treadmill walking, the OP was the most accurate monitor across all speeds (±1.1% of MC steps), while the PAC underestimated steps by 6.7–16.0% per stage. During free-living, the OP and AG counted 97.5% and 98.5% of YX steps, respectively. The PAC overestimated steps by 44.0%, or 5,265 steps per day. The Omron pedometer seems to provide the most reliable and valid estimate of steps taken, as it was the best performer under lab-based conditions and provided comparable results to the YX in free-living. Future studies should consider these monitors in additional populations and settings.