The performance of orthogonal arrays with adjoined or unavailable runs

University of Technology Sydney. Faculty of Science.Orthogonal arrays are a class of fractional factorial designs that are optimal according to a range of optimality criteria. This makes it tempting to construct fractional factorial designs by adjoining additional runs to an OA, or by removing runs from an OA, when the number of runs available for the experiment is only slightly larger or smaller than the number in the OA. In this thesis we examine the performance of OA plus p runs designs and OA minus t runs designs in the context of D-optimality and model-robustness. Although we attempt to make general observations where possible, our primary goal is to inform the use of quantitative factors, hence we focus on factors at more than two levels to allow for some curvature in the model. We begin by considering the performance of these designs under a main effects only model, and show that optimality depends only on the pairwise Hamming distance of the adjoined (or removed) runs. We present an algorithm for finding optimal Hamming distances and provided general methods for constructing optimal sets of runs once the optimal pairwise Hamming distances have been identified. In order to consider the performance of these designs when interaction terms are included in the model, it transpired that we require a complete set of geometrically non-isomorphic designs to study. Thus, we enumerate all geometric isomorphism classes for symmetric OAs with ternary factors and 18 runs, and prove that these classes cover the entire OA[18; 3m] space. We then consider the inclusion of a subset of linear-by-linear interactions in the model, and derive matrices to be optimised under this setting. We conduct an empirical study on the OA[18; 3m] we have enumerated and give examples of D-optimal and model-robust designs for each of the design spaces, that is, for each of m = 3, 4, 5, 6 and 7

The implementation of educational policy: A case study of the Open College of South London.

An 'Open College' system derives from a policy designed to redress educational inequalities among the inner city adult population. It is a development in the post-school sector of education which brings together different types of institutions in a quasi-federal structure. Its aim is to develop course provision for adult returners which will facilitate their progression to higher education, further education and/or into employment. Whether or not a policy achieves what the policy-makers intended, it is hypothesised, depends on the way in which it is perceived by the key people within the organisation and the action which they take to effect its implementation. Successful outcomes are dependent on there being "commitment, communication and capacity" at each level of the operation. A case study is an appropriate means of examining the relative importance of the various factors. It involves in-depth interviews with the policy-makers (the politicians and administrators), the policy-implementers (the central co-ordinators and principals in the institutions) and the policy-deliverers (the co-ordinators and tutors in the institutions). To ascertain the factors which ultimately make for successful outcomes for those concerned, a longitudinal study of adult students in one of the designated areas of course development was undertaken. An eclectic theoretical research model is adopted, because no one perspective is thought to be appropriate at all levels of the processes of policy formulation and implementation. Attention is paid to the political, social and economic context of London and Britain in the 1980s. The micro study in a macro framework also facilitates generalisation. In establishing what factors make for successful outcomes for a policy concerned with equal opportunitiees in education in a deprived inner city area, it is hoped that it might be possible to throw some light upon the factors which make for the successful implementation of policy more generally

Analogy Mining for Specific Design Needs

Finding analogical inspirations in distant domains is a powerful way of solving problems. However, as the number of inspirations that could be matched and the dimensions on which that matching could occur grow, it becomes challenging for designers to find inspirations relevant to their needs. Furthermore, designers are often interested in exploring specific aspects of a product-- for example, one designer might be interested in improving the brewing capability of an outdoor coffee maker, while another might wish to optimize for portability. In this paper we introduce a novel system for targeting analogical search for specific needs. Specifically, we contribute a novel analogical search engine for expressing and abstracting specific design needs that returns more distant yet relevant inspirations than alternate approaches

“This is pretend. We are just playing.” Exploring young children’s imaginative play with, and educators’ provision of, digital technologies in play-based settings.

Digital technologies have become commonplace in nearly all areas of the modern life in Western society. Mobile phone users now have the ability to watch movies, surf the internet and perform all the functionalities of a computer on increasingly smaller devices. Children are capable of not only taking photos and movies, but they can successfully upload them to social media. They now have an online presence from a very early age, sometimes even before they are born. What does this mean for early childhood educational settings, where play is valued as the way children learn? Children are arriving at these services with a wide range of prior experiences including more technical knowledge than ever before, and sometimes, more than their educators. The early childhood field began by debating the appropriateness of using technologies with young children, but current literature has moved on to now focus on exploring their engagement with technologies, and on the positive benefits of building children’s knowledge of technologies, prior to formal schooling. What is not clearly defined is how children engage with these devices when they are provided in play-based, learning settings. Educators often struggle to integrate these technologies into their play-based pedagogies, and to support children’s meaning making when their play involves these devices. While some targeted professional development for educators aims to build their knowledge around how to provide technologies for young children, these efforts have not been very effective when integrating them into play-based pedagogy. What is needed is greater understanding of how to provide technologies in meaningful ways, and how to implement child-focused pedagogies incorporating technologies that support children’s play and learning. This thesis aims to explore the integration between children’s imaginative play with digital technologies, and the influences on educators’ provision of these devices in play-based settings. The research was conducted in two kindergarten settings, in suburbs of Melbourne, Australia. The children were aged four to six years and were attending kindergarten in the year prior to school entry. An ethnographic study was conducted over a 12-week period, with data being collected via video recordings, photographs, observations, conversations with children, interviews with educators and a researcher journal. The first contribution to knowledge that this thesis makes is the introduction of the Imaginative Affordance Framework, which combines Vygotsky’s (1966) concepts of mediation and imagination with Gibson’s (1979) concept of affordance. The framework was used to analyse the data collected and establish the findings related to the children’s imaginative play with digital technologies and to understand the educators’ provision of these devices. The findings were presented and discussed as six paradoxes: working technologies versus non-working technologies; solitary individuals working with devices versus groups of children on devices; play-based, child centred programmes versus adult controlled programmes; nature discourse versus technologies as not natural; traditional kindergarten activities versus newer technological activities; and, children learning to navigate the rules pertaining to working technologies versus their desire to play according to their own volition. Based on the findings three recommendations were presented. These related to the children, the educators and the wider community and policy makers. The second contribution to knowledge filled the gap in current understanding, established in the literature review, around how children engage with digital technologies in their imaginative play, influenced by what and how the devices are provided by their educators. The reasons behind the educators’ provision are discussed and their position as neoliberal subjects is recognised and explored. A diagram of provision is presented and suggestions for professional learning to address the intervention points within the diagram are made. The thesis concludes with recommendations of potential research that would further extend the knowledge base of this topic

Chemical characteristics of macroscopic pyrogenic carbon following millennial-scale environmental exposure

Pyrogenic Carbon (PyC) is ubiquitous in global environments, and is now known to form a significant, and dynamic component of the global carbon cycle, with at least some forms of PyC persisting in their depositional environment for many millennia. Despite this, the factors that determine the turnover of PyC remain poorly understood, as do the physical and chemical changes that this material undergoes when exposed to the environment over tens of thousands of years. Here, we present the results of an investigation to address these knowledge gaps through chemical and physical analysis of a suite of wood PyC samples exposed to the environment for varying time periods, to a maximum of >90,000 years. This includes an assessment of the quantity of resistant carbon, known as Stable Polyaromatic Carbon (SPAC) versus more chemically labile carbon in the samples. We find that, although production temperature is likely to determine the initial ‘degradation potential’ of PyC, an extended exposure to environmental conditions does not necessarily mean that remaining PyC always progresses to a ‘SPAC-dominant’ state. Instead, some ancient PyC can be composed largely of chemical components typically thought of as environmentally labile, and it is likely that the depositional environment drives the trajectory of preservation versus loss of PyC over time. This has important implications for the size of global PyC stocks, which may have been underestimated, and also for the potential loss of previously stored PyC, when its depositional environment alters through environmental or climatic changes

A Critical Time Window for Organismal Interactions in a Pelagic Ecosystem

To measure organismal coherence in a pelagic ecosystem, we used moored sensors to describe the vertical dynamics of each step in the food chain in shelf waters off the west shore of Oahu, Hawaii. Horizontally extensive, intense aggregations of phytoplankton, zooplankton, and micronekton exhibited strong diel patterns in abundance and vertical distribution, resulting in a highly variable potential for interaction amongst trophic levels. Only around dusk did zooplankton layers overlap with phytoplankton layers. Shortly after sunset, micronekton ascended from the deep, aggregating on the island’s shelf. Short-lived departures in migration patterns were detected in depth, vertical distribution, density, and total abundance of micronekton when zooplankton layers were present with typical patterns resuming within one hour. Layers of zooplankton began to disappear within 20 minutes of the arrival of micronekton with no layers present after 50 minutes. The effects of zooplankton layers cascaded even further up the food chain, affecting many behaviors of dolphins observed at dusk including their depth, group size, and inter-individual spacing. As a result of these changes in behavior, during a 30-minute window just after dusk, the number of feeding events observed for each dolphin and consequently the feeding time for each individual more than doubled when zooplankton layers were present. Dusk is a critical period for interactions amongst species in this system from phytoplankton to top predators. Our observations that short time windows can drive the structure and function of a complex suite of organisms highlight the importance of explicitly adding a temporal dimension at a scale relevant to individual organisms to our descriptions of heterogeneity in ocean ecosystems

A new Holocene sea-level record for Singapore

Relative sea-level (RSL) records from far-field regions distal from ice sheets remain poorly understood, particularly in the early Holocene. Here, we extended the Holocene RSL data from Singapore by producing early Holocene sea-level index points (SLIPs) and limiting dates from a new ~40 m sediment core. We merged new and published RSL data to construct a standardized Singapore RSL database consisting of 88 SLIPs and limiting data. In the early Holocene, RSL rose rapidly from −21.0 to −0.7 m from ~9500 to 7000 cal. yrs. BP. Thereafter, the rate of RSL rise decelerated, reaching a mid-Holocene highstand of 4.0 ± 4.5 m at 5100 cal. yrs. BP, before falling to its present level. There is no evidence of any inflections in RSL when the full uncertainty of SLIPs is considered. When combined with other standardized data from the Malay-Thai Peninsula, our results also show substantial misfits between regional RSL reconstructions and glacial isostatic adjustment (GIA) model predictions in the rate of early Holocene RSL rise, the timing of the mid-Holocene highstand and the nature of late-Holocene RSL fall towards the present. It is presently unknown whether these misfits are caused by regional processes, such as subsidence of the continental shelf, or inaccurate parameters used in the GIA model

A critical scale in plankton aggregations across coastal ecosystems

We examined the characteristics of biological patches at four different locations to assess the relationship of patch vertical scale, amplitude, and persistence. In contrast to patches of larger animals, we found that the majority of coherent aggregations of plankton at each site were vertically compressed, with most smaller than 5m vertically. A subset of these layers, often referred to as thin layers in the literature, was distinguished by high intensity and greater persistence but not thickness. Our results suggest that similar to 5m is a critical vertical scale below which aggregations of plankton frequently occur, pointing toward a controlling characteristic or a process common to a variety of regions and organism types. Given the commonality of this scale, insights into physical-biological dynamics gleaned from previous studies of the most intense and persistent of these patches may be applied more generally, leading to a better understanding of the ecosystem effects of heterogeneous plankton distributions.Keywords: spatial structure, patchiness, scale, plankto

Scaling relations for seismic cycles on mid-ocean ridge transform faults

Author Posting. © American Geophysical Union, 2009. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geophysical Research Letters 36 (2009): L21301, doi:10.1029/2009GL040115.Mid-ocean ridge transform faults (RTFs) have thermal structures that vary systematically with tectonic parameters, resulting in predictable seismic characteristics and clear seismic cycles. We develop a scaling relation for repeat time, tR, of the largest expected earthquake, MC: tR = μ−1Δσ2/3CMc1/3AT1/4V−1, where μ is the shear modulus, Δσ is the stress drop, CMc is a constant, AT is the area above 600°C, and V is the slip rate. We identify repeating MC earthquakes by measuring differential arrival times of first orbit Rayleigh waves to determine centroid offsets between pairs of events. Comparing our observations of tR (5–14 years for earthquakes on Gofar and Blanco RTFs) with predictions from our scaling relation, we can constrain RTF stress drops. Specific tests of this scaling relation are proposed for earthquakes on Blanco, Gofar, Discovery, and Clipperton RTFs, which are all expected to have large ruptures in the next few years.JM was supported by the Deep Ocean Exploration Institute at WHOI. MB was supported by a Tyco Postdoctoral Fellowship and NOAA grant NA05NOS4001153 at UNH