Bordism Invariants of the Mapping Class Group

We define new bordism and spin bordism invariants of certain subgroups of the mapping class group of a surface. In particular, they are invariants of the Johnson filtration of the mapping class group. The second and third terms of this filtration are the well-known Torelli group and Johnson subgroup, respectively. We introduce a new representation in terms of spin bordism, and we prove that this single representation contains all of the information given by the Johnson homomorphism, the Birman-Craggs homomorphism, and the Morita homomorphism.Comment: 34 pages, 7 figure

Femmes / Action / Religion

In the history of women, Christianity plays an ambiguous role. God may no doubt speak to whom He pleases, in a manner which breaks apart the relationships of subordination. At the same time, the concept of divine sanction for existing authority relations, and the full panapoly of ecclesistical institutions, have historically provided a powerful justification for the maintenance of the status quo. Christinaity at a wide variety of places and times has supported subordinate roles for women

Equations provide tubular information on effects of uniform and variable loads on thin, flat, circular plates

Unit-mass system of derivation of equations determines the deflection, slope, and moments for thin, flat, circular plates subjected to either a uniform or a symmetrical variable load. The derived equations are computed, organized in tabular form, and graphically depicted

Modification of air flows within an industrial carcass chiller using delta wing vortex generators

The chilling of carcasses after slaughter has a considerable bearing on process costs and quality of the meat. Uniform air distribution is essential for the optimal operation of carcass chillers, yet many existing chillers have highly variable and ineffective air flow. This directly affects the uniformity of evaporative weight loss and carcass cooling rates within the chiller. Delta plan aerofoils are known to convert a unidirectional air stream, progressively into a rotational and then turbulent multidirectional fragments of moving air. The aim of this research was to evaluate the use of delta wings to improve air flows inside a venison carcass chiller of typical design used in the New Zealand meat industry. Air flow patterns within the chiller were characterised by measuring mean air speeds with a hot-wire anemometer over 61 grid points at 4 levels in height. Air speeds were found to be highly time-variable so the mean, standard deviation and range of 60 one second air speed measurements were used to represent the air flow at each point on the grid. The measurement of air velocity (speed and direction) using three othoganally mounted propeller anemometers had limited success, as air speeds within the chiller were often below the threshold of the anemometer. Measurements before the installation of the delta wings indicated that a poor air flow distribution existed within the chiller as the majority of air was found to circulate around the walls and floor, producing near stagnant conditions between the carcasses. Delta wings were constructed in two sizes from thin aluminium sheets. Wings were installed into the chiller by suspending them from the ceiling within the evaporator fan delivery air stream. Two wing configurations were trialed: The first wing configuration utilised 3 large delta wings mounted in front of the evaporator fans followed by a row of 6 small wings then a row of 7 small wings (3,6,7). The second delta wing configuration utilised a row of 6 large wings closest to the evaporator fans followed by a row of 9 small wings then a row of 13 small wings (6,9,13). The second delta wing configuration showed superior performance over the first. In comparison to the unmodified chiller without wings, the mean air speeds in the critical region amongst the carcasses increased from 0.4 m/s to 0.6 m/s; the standard deviation of mean air speeds decreased from 0.33 m/s to 0.22 m/s and the percentage of mean air speeds between half and twice the mean increased from 84% to 95%. The second configuration of delta wings also produced a 14% increase in the mean air turbulence intensity (measure of the time-variability in air speed) and reduced the variability of evaporative weight loss within the chiller. Overall, the delta wings were found to be an economic way to improve the performance of a chiller by providing a more uniform and effective air distribution without increasing fan power. This can result in a reduction in chilling times and less potential for weight loss. Their use in both new and existing chillers is recommended

From print to Web: issues in re-purposing for an Open Resources Repository

The Open Educational Resources (OER) movement has gained rapid support for its goals of universal access to education. The UK Open University's contribution is OpenLearn, a project funded by the William and Flora Hewlett Foundation which, over the next two years, aims to re-purpose several thousand study-hours of existing learning materials for online delivery. The UK Open University has gained a hard-won reputation for the quality of its learning materials and integrated Supported Open Learning model. However, these materials are, as a rule, developed within the framework of long courses that typically require between 300 and 600 hours of study. Furthermore, many of the courses are 'interdisciplinary' in that they are developed by teams that include members associated with different faculties. The courses are, therefore, generally structured in terms of themes that run throughout the course and may span a variety of academic disciplines. Also, despite the breadth of knowledge brought into play when a course is developed, the courses normally reflect pedagogical and disciplinary assumptions and views that are prevalent in the UK. Based on the authors' experience of the OpenLearn project, this paper explores some of the key issues encountered when re-purposing resources. These issues include how to provide material not supported by tutorial guidance, the suitability of media components for conversion and the inter-relationship between the multimedia components. The paper will also briefly discuss the requirements for evaluation of the re-purposing process. The issues raised are potentially of relevance to other re-purposing initiatives