Multidimensional stochastic approximation using locally contractive functions

A Robbins-Monro type multidimensional stochastic approximation algorithm which converges in mean square and with probability one to the fixed point of a locally contractive regression function is developed. The algorithm is applied to obtain maximum likelihood estimates of the parameters for a mixture of multivariate normal distributions

Analysis of payload bay magnetic fields due to dc power multipoint and single point ground configurations

An analysis of magnetic fields in the Orbiter Payload Bay resulting from the present grounding configuration (structure return) was presented and the amount of improvement that would result from installing wire returns for the three dc power buses was determined. Ac and dc magnetic fields at five points in a cross-section of the bay are calculated for both grounding configurations. Y and Z components of the field at each point are derived in terms of a constant coefficient and the current amplitude of each bus. The dc loads assumed are 100 Amperes for each bus. The ac noise current used is a spectrum 6 db higher than the Orbiter equipment limit for narrowband conducted emissions. It was concluded that installing return wiring to provide a single point ground for the dc Buses in the Payload Bay would reduce the ac and dc magnetic field intensity by approximately 30 db

Sail GTS ground system analysis: Avionics system engineering

A comparison of two different concepts for the guidance, navigation and control test set signal ground system is presented. The first is a concept utilizing a ground plate to which crew station, avionics racks, electrical power distribution system, master electrical common connection assembly and marshall mated elements system grounds are connected by 4/0 welding cable. An alternate approach has an aluminum sheet interconnecting the signal ground reference points between the crew station and avionics racks. The comparison analysis quantifies the differences between the two concepts in terms of dc resistance, ac resistance and inductive reactance. These parameters are figures of merit for ground system conductors in that the system with the lowest impedance is the most effective in minimizing noise voltage. Although the welding cable system is probably adequate, the aluminum sheet system provides a higher probability of a successful system design

Of sea anemones and clownfish: exploring a mutually beneficial approach to educational development through soft systems methodology.

This report presents a large scale exploration of the roles, practice and influence of members of staff in a central educational development department working alongside academic discipline-based teaching staff in a UK University. The project uses Soft Systems Methodology (SSM) for this exploration. The concept modelled within this doctoral project is one of developmental mentoring embedded in the management and design of an externally funded project – the Pathfinder Project. This includes using the characteristics of developmental mentoring and the five phases of the mentoring relationship. The concept model is compared to and discussed in a real-world situation of discipline-based teaching and learning. This activity takes place throughout the life span of the Pathfinder Project during the academic year 2007-08. This doctoral project heavily influenced the design and delivery of the Pathfinder Project although Pathfinder remains an entity in its own right. The doctoral project and the Pathfinder Project shared data however the analysis, findings, conclusions and recommendations are different. The work-based research questions which this doctoral project seeks to address are concerned with the means to develop ways for a central department to work most effectively with discipline-based teaching staff. The project outcomes offer a model for staff development that helps build staff capability and capacity. From a practitioner/researcher point of view, outcomes also suggest how the experiences and findings of this project can inform the work-based context for educational developers. This project report integrates project outcomes with a reflective critical commentary written in the first person. The project report includes original images throughout the text as could be expected from a user of SSM

Development and initial validation of the determinants of physical activity questionnaire

Background: Physical activity interventions are more likely to be effective if they target causal determinants of behaviour change. Targeting requires accurate identification of specific theoretical determinants of physical activity. Two studies were undertaken to develop and validate the Determinants of Physical Activity Questionnaire. Methods In Study 1, 832 male and female university staff and students were recruited from 49 universities across the UK and completed the 66-item measure, which is based on the Theoretical Domains Framework. Confirmatory factor analysis was undertaken on a calibration sample to generate the model, which resulted in a loss of 31 items. A validation sample was used to cross-validate the model. 20 new items were added and Study 2 tested the revised model in a sample of 466 male and female university students together with a physical activity measure. Results: The final model consisted of 11 factors and 34 items, and CFA produced a reasonable fit χ2 (472) = 852.3, p < .001, CFI = .933, SRMR = .105, RMSEA = .042 (CI = .037-.046), as well as generally acceptable levels of discriminant validity, internal consistency, and test-retest reliability. Eight subscales significantly differentiated between high and low exercisers, indicating that those who exercise less report more barriers for physical activity. Conclusions: A theoretically underpinned measure of determinants of physical activity has been developed with reasonable reliability and validity. Further work is required to test the measure amongst a more representative sample. This study provides an innovative approach to identifying potential barriers to physical activity. This approach illustrates a method for moving from diagnosing implementation difficulties to designing and evaluating interventions

Combining optical trapping in a microfluidic channel with simultaneous micro-Raman spectroscopy and motion detection.

Since their invention by Ashkin optical tweezers have demonstrated their ability and versatility as a non-invasive tool for micromanipulation. One of the most useful additions to the basic optical tweezers system is micro-Raman spectroscopy, which permits highly sensitive analysis of single cells or particles. We report on the development of a dual laser system combining two spatial light modulators to holographically manipulate multiple traps (at 1064nm) whilst undertaking Raman spectroscopy using a 532nm laser. We can thus simultaneously trap multiple particles and record their Raman spectra, without perturbing the trapping system. The dual beam system is built around micro-fluidic channels where crystallisation of calcium carbonate occurs on polymethylmethacrylate (PMMA) beads. The setup is designed to simulate at a microscopic level the reactions that occur on items in a dishwasher, where permanent filming of calcium carbonate on drinking glasses is a problem. Our system allows us to monitor crystal growth on trapped particles in which the Raman spectrum and changes in movement of the bead are recorded. Due to the expected low level of crystallisation on the bead surfaces this allows us to obtain results quickly and with high sensitivity. The long term goal is to study the development of filming on samples in-situ with the microfluidic system acting as a model dishwasher

The effect of heavy metals on differentiated neuronal and glial cells

Heavy metal poisoning poses a serious health risk among populations worldwide. The symptoms presented by exposure are varied and depend upon the species of the metal, the age of the individual and the exposure dose. All heavy metals have debilitating effects on the CNS. Children are especially sensitive to the neurological effects due to the intense growth and activity of a developing nervous system and inadequately developed defences. The aims of this study were to determine the effects of sub-lethal concentrations of numerous heavy metals on neuronal and glial cell differentiation. Using established cellular models, the toxicity of zinc, lead, mercury, methylmercury and thimerosal were investigated using assays of cell viability and morphology on differentiating N2a and C6 cells. Initial research revealed thimerosal, methylmercury and cadmium to be the most toxic compounds tested, in terms of their ability to inhibit the outgrowth of neurites in both cell lines at sub-lethal concentrations. Although cadmium chloride showed similar patterns of toxicity to the mercury compounds, thimerosal and MeHgCl were chosen for further investigation at a molecular level. Methylmercury chloride a common environmental pollutant and thimerosal; a preservative found in many medicines, were chosen for further investigation, as previous work has demonstrated the health risks posed by the two organic mercury compounds but little is known about non-lethal changes that occur in the nervous system, especially with thimerosal

Consistency of Consumer Valuation Under Different Information Sets: An Experimental Auction with Sweet Potatoes

We used a controlled, uniform 5th-price auction to elicit values for sweet potatoes—both when location is known and unknown, and before and after tasting and providing health information. Significant differences were found between pre- and post-consumption valuations and also found that there were significant effects for location of origin and health information. Interestingly, we also find that location of origin not only affects the level of bids, but also the marginal differences in bids between different potatoes. Overall, however, these results suggest little consistency in bid values across information sets, suggesting that attempting to elicit values of attributes in isolation may lead to erroneous results.Consumer/Household Economics, Demand and Price Analysis,

The Impacts of Taste, Location of Origin, and Health Information on Market Demand for Sweet Potatoes

Location of product origin is an often-used marketing device by retailers. This approach is based on the assumption that location of origin signals something to consumers about the underlying quality (or other attributes) of the product. This can be an effective strategy if the signal matches the consumer valuation of the product after consumption. In the same vein, health advertising is used to increase demand for a product that exhibits "healthy" dietary attributes. While there have been numerous studies examining the potential impacts of these attributes on demand, there have been few rigorous studies that examine the consistency of consumer valuations of location of origin before and after they have actually consumed the product (or before and after health advertising). Results show that knowledge of location of origin of sweet potatoes does have an impact on consumer valuation. It was also found that both the information from the taste attribute (experience) and the health attribute (credence) played a significant role in participant valuation.Food Consumption/Nutrition/Food Safety,