Girls Count: A Global Investment & Action Agenda

Explains how girls' welfare affects overall economic and social outcomes. Outlines steps to disaggregate health, education, and other data by age and gender; invest strategically in girls' programs; and ensure equitable benefits for girls in all sectors

System design for the square kilometre array : new views of the universe

The Square Kilometre Array (SKA) radio telescope is being designed as a premier scientific instrument of the 21st century, using novel technologies to maximise its scientific capability. The SKA has an aggressive project timeline, dynamic and evolving scientific requirements, and a large design exploration space with many interdependent sub-systems. These complexities increase the difficulty in developing cost-effective design solutions that maximise the scientific capability of the telescope within construction and operations funding constraints.To gain insight into specific design challenges in this thesis, I have developed parametric models of the telescope system that relate cost to key performance metrics. I examine, as case studies, three aspects of the SKA design that have had little investigation compared to the rest of the telescope to date, but show considerable potential for discovering new astronomical phenomena.First, I present fast transient survey strategies for exploring high time resolution parameter space, and consider the system design implications of these strategies. To maximise the scientific return from limited processing capacity, I develop a new metric, ‘event rate per beam’, to measure the cost-effectiveness of the various search strategies. The most appropriate search strategy depends on the observed sky direction and the source population; for SKA Phase 1, low-frequency aperture arrays tend to be more effective for extragalactic searches, and dishes more effective for directions of increased scatter broadening, such as near the Galactic plane.Second, I compare the cost of two design solutions for low-frequency sparse aperture array observations (70–450 MHz) that achieve similar performance: a single-band implementation with a wideband antenna design; and a dual-band implementation, with each array observing approximately half the fractional bandwidth. Perhaps somewhat surprisingly, despite the dual-band array having twice the number of antenna elements, neither a representative single or dual-band implementation is cheaper a priori, although the uncertainties are currently high. In terms of the broader telescope system design, I show that the central processing, antenna deployment and site preparation costs are potentially significant cost drivers that have so far had insufficient attention.Third, the recent site decision gives rise to the question of how to cost-effectively provide data connectivity to widely separated antennas, to enable high angular resolution observations with the SKA dish array in Africa. To facilitate the design of such a data network, I parametrise the performance and cost of an exemplar network using three simple metrics: maximum baseline length; number of remote stations (grouped antennas) on long baselines; and the product of bandwidth and number of station beams. While all three metrics are cost drivers, limiting the beam–bandwidth product reduces cost without significantly impacting scientific performance.The complexities of the SKA design environment prevent straightforward analyses of cost-effective design solutions. However, the case studies in this thesis demonstrate the importance of parametric performance and cost modelling of the telescope system in determining cost-effective design solutions that are capable of revealing large regions of unexplored parameter space in the radio Universe. The analytical approach to requirements analysis and performance-cost modelling, combined with pragmatic choices to narrow the exploration space, yields new insights into cost-effective SKA designs. Continuation of this approach will be essential to successfully integrate the forthcoming results from various verifications systems into the SKA design over the next few years

Classifying complex topics using spatial-semantic document visualization: An evaluation of an interaction model to support open-ended search tasks

This thesis was submitted for the degree of Doctor of Philosophy and awarded by Brunel University.In this dissertation we propose, test and develop a novel search interaction model to address two key problems associated with conducting an open-ended search task within a classical information retrieval system: (i) the need to reformulate the query within the context of a shifting conception of the problem and (ii) the need to integrate relevant results across a number of separate results sets. In our model the user issues just one highrecall query and then performs a sequence of more focused, distinct aspect searches by browsing the static structured context of a spatial-semantic visualization of this retrieved document set. Our thesis is that unsupervised spatial-semantic visualization can automatically classify retrieved documents into a two-level hierarchy of relevance. In particular we hypothesise that the locality of any given aspect exemplar will tend to comprise a sufficient proportion of same-aspect documents to support a visually guided strategy for focused, same-aspect searching that we term the aspect cluster growing strategy. We examine spatial-semantic classification and potential aspect cluster growing performance across three scenarios derived from topics and relevance judgements from the TREC test collection. Our analyses show that the expected classification can be represented in spatial-semantic structures created from document similarities computed by a simple vector space text analysis procedure. We compare two diametrically opposed approaches to layout optimisation: a global approach that focuses on preserving the all similarities and a local approach that focuses only on the strongest similarities. We find that the local approach, based on a minimum spanning tree of similarities, produces a better classification and, as observed from strategy simulation, more efficient aspect cluster growing performance in most situations, compared to the global approach of multidimensional scaling. We show that a small but significant proportion of aspect clustering growing cases can be problematic, regardless of the layout algorithm used. We identify the characteristics of these cases and, on this basis, demonstrate a set of novel interactive tools that provide additional semantic cues to aid the user in locating same-aspect documents