Waste in North America (Detroit Incinerator, Toronto Landfill, PCB Disposal and Transport, Etc.), Hazardous and Non-Hazardous Wastes: Trade or Environmental Issue - Introduction

hazardous and non-hazardous waste--Canada, hazardous and non-harzdous waste--United State

Torsion-induced persistent current in a twisted quantum ring

We describe the effects of geometric torsion on the coherent motion of electrons along a thin twisted quantum ring. The geometric torsion inherent in the quantum ring triggers a quantum phase shift in the electrons' eigenstates, thereby resulting in a torsion-induced persistent current that flows along the twisted quantum ring. The physical conditions required for detecting the current flow are discussed.Comment: 9 pages, 3 figure

Parallel String Sample Sort

We discuss how string sorting algorithms can be parallelized on modern multi-core shared memory machines. As a synthesis of the best sequential string sorting algorithms and successful parallel sorting algorithms for atomic objects, we propose string sample sort. The algorithm makes effective use of the memory hierarchy, uses additional word level parallelism, and largely avoids branch mispredictions. Additionally, we parallelize variants of multikey quicksort and radix sort that are also useful in certain situations.Comment: 34 pages, 7 figures and 12 table

Response of students to statement-bank feedback: The impact of assessment literacy on performances in summative tasks

Efficiency gains arising from the use of electronic-marking tools that allow tutors to select comments from a statement bank are well documented, but how students use this type of feedback for learning remains under-explored. In this study, Natural Science students (N=161) were emailed feedback reports on a spreadsheet assessment that included an invitation to reply placed at different positions. Outcomes suggest that students either read feedback completely, or not at all. Although mean marks for repliers (M=75.5%, N=39) and non-repliers (M=57.2%, N=68) were significantly different (p<.01), these two groups of students possessed equivalent attendance records and similar submission rates and performances in a contemporaneous formatively-assessed laboratory report. Notably, average marks for a follow-up summative laboratory report, using the same assessment criteria as the formative task, were 10% higher for students who replied to the original invite within feedback on the spreadsheet assessment. It is concluded that the repliers represent a group of assessment-literate students and that statement-bank feedback can foster learning under appropriate conditions: A simple ‘fire’ analogy for feedback is advanced that advocates high quality information on progress (fuel) and a curricular atmosphere conducive to learning (oxygen). However, only if students are assessment literate (ignition) will feedback illuminate

Union renewal in historical perspective

This article revisits contemporary union renewal/revival debates through comparison with the late 1930s resurgence of trade unionism in the UK’s engineering industry. It is argued that the 1930s union renewal arose from more favourable contextual conditions than those currently obtaining. It was led by political activists, with better-articulated organisation and greater resonance in the working class than their contemporary counterparts, and who were assisted by state policy and pro-worker forces. Conclusions are drawn in relation to current debates

Preliminary Study of Turbulent Flow in the Lower Plenum of a Gas-Cooled Reactor

A preliminary study of the turbulent flow in a scaled model of a portion of the lower plenum of a gas-cooled advanced reactor concept has been conducted. The reactor is configured such that hot gases at various temperatures exit the coolant channels in the reactor core, where they empty into a lower plenum and mix together with a crossflow past vertical cylindrical support columns, then exit through an outlet duct. An accurate assessment of the flow behavior will be necessary prior to final design to ensure that material structural limits are not exceeded. In this work, an idealized model was created to mimic a region of the lower plenum for a simplified set of conditions that enabled the flow to be treated as an isothermal, incompressible fluid with constant properties. This is a first step towards assessing complex thermal fluid phenomena in advanced reactor designs. Once such flows can be computed with confidence, heated flows will be examined. Experimental data was obtained using three-dimensional Particle Image Velocimetry (PIV) to obtain non-intrusive flow measurements for an unheated geometry. Computational fluid dynamic (CFD) predictions of the flow were made using a commercial CFD code and compared to the experimental data. The work presented here is intended to be scoping in nature, since the purpose of this work is to identify improvements that can be made to subsequent computations and experiments. Rigorous validation of computational predictions will eventually be necessary for design and analysis of new reactor concepts, as well as for safety analysis and licensing calculations