Statistical disclosure control: Applications in healthcare

Statistical disclosure control is a progressive subject which offers techniques with which tables of data intended for public release can be protected from the threat of disclosure. In this sense disclosure will usually mean information on an individual subject being revealed by the release of a table. The techniques used centre around detecting potential disclosure in a table and then removing this disclosure by somehow adjusting the original table. This thesis has been produced in conjunction with Information and Services Division (Scotland) (ISD) and therefore will concentrate on the applications of statistical disclosure control in the field of healthcare with particular reference to the problems encountered by ISD. The thesis predominately aims to give an overview of current statistical disclosure control techniques. It will investigate how these techniques would work in the ISD scenario and will ultimately aim to provide ISD with advice on how they should proceed in any future update of their statistical disclosure control policy. Chapter 1 introduces statistical disclosure and investigates some of the legal and social issues associated with the field. It also provides information on the techniques which are used by other organisations worldwide. Further there is an introduction to both the ISD scenario and a leading computing package in the area, Tau-Argus. Chapter 2 gives an overview of the techniques currently used in statistical disclosure control. This overview includes technical justification for the techniques along with the advantages and disadvantages associated with using each technique. Chapter 3 provides a decision rule approach to the selection of disclosure control techniques described in Chapter 2 and much of Chapter 3 revolves around a description of the implications derived from the choices made. Chapter 4 presents the results from an application of statistical disclosure control techniques to a real ISD data set concerned with diabetes in children in Scotland. The results include a quantification of the information lost in the table when the disclosure control technique is applied. The investigation concentrated on two and three- dimensional tables and the analysis was carried out using the Tau-Argus computing package. Chapter 5 concludes by providing a summary of the main findings of the thesis and providing recommendations based on these findings. There is also a discussion of potential further study which may be useful to ISD as they attempt to update their statistical disclosure control policy

Implementation of an activity coordinator for an activity-based distributed system

Distributed computing systems offer a number of potential benefits, including: - improved fault-tolerance and reliability - increased processor availability - faster response time - flexibility of system configuration - effective management of geographically distributed resources - integration of special purpose machines into applications In order to realize this potential, support systems that aid in the development of distributed programs are needed. An Activity System facilitates the design and implementation of distributed programs: (1) By allowing the programmer to group functionally related objects into an activity (or job) which is recorded within the system. The information stored concerning relationships between objects may then be used to control their interactions and thus to manage distributed resources. (2) By effectively eliminating the need for the programmer to deal with the underlying details of inter-process communication. The system handles the establishment of communication links between objects in an activity, and controls the routing of messages to activity members. To evaluate the uses of activities in developing distributed programs, I have implemented a portion of such a system; namely, an Activity Coordinator , together with Activity System components and test tools required to verify its functionality. Within the context of an Activity System, the Activity Coordinator provides certain key functions: (1) It maintains a database of information pertaining to objects and activities, and (2) It handles the routing of activity related messages. In future versions of the activity system the Activity Coordinator may also play a more active role in fault recovery. These possibilities will also be discussed

Self-localizing Smart Cameras and Their Applications

As the prices of cameras and computing elements continue to fall, it has become increasingly attractive to consider the deployment of smart camera networks. These networks would be composed of small, networked computers equipped with inexpensive image sensors. Such networks could be employed in a wide range of applications including surveillance, robotics and 3D scene reconstruction. One critical problem that must be addressed before such systems can be deployed effectively is the issue of localization. That is, in order to take full advantage of the images gathered from multiple vantage points it is helpful to know how the cameras in the scene are positioned and oriented with respect to each other. To address the localization problem we have proposed a novel approach to localizing networks of embedded cameras and sensors. In this scheme the cameras and the nodes are equipped with controllable light sources (either visible or infrared) which are used for signaling. Each camera node can then automatically determine the bearing to all the nodes that are visible from its vantage point. By fusing these measurements with the measurements obtained from onboard accelerometers, the camera nodes are able to determine the relative positions and orientations of other nodes in the network. This localization technology can serve as a basic capability on which higher level applications can be built. The method could be used to automatically survey the locations of sensors of interest, to implement distributed surveillance systems or to analyze the structure of a scene based on the images obtained from multiple registered vantage points. It also provides a mechanism for integrating the imagery obtained from the cameras with the measurements obtained from distributed sensors. We have successfully used our custom made self localizing smart camera networks to implement a novel decentralized target tracking algorithm, create an ad-hoc range finder and localize the components of a self assembling modular robot

Applications of complex adaptive systems approaches to coastal systems

This thesis investigatesth e application of complex adaptives ystemsa pproaches (e. g. Artificial Neural Networks and Evolutionary Computation) to the study of coastal hydrodynamica nd morphodynamicb ehaviour.T raditionally, nearshorem orphologicalc oastal systems tudiesh ave developeda n understandingo f thosep hysicalp rocesseso ccurringo n both short temporal, and small spatial scales with a large degree of success. The associated approachesa nd conceptsu sedt o study the coastals ystema t theses calesh ave Primarily been linear in nature.H owever,w hent hesea pproachetso studyingt he coastals ystema re extendedto investigating larger temporal and spatial scales,w hich are commensuratew ith the aims of coastal managementr, esults have had less success.T he lack of successi n developing an understandingo f large scalec oastalb ehaviouri s to a large extent attributablet o the complex behavioura ssociatedw ith the coastals ystem.I bis complexity arises as a result of both the stochastic and chaotic nature of the coastal system. This allows small scale system understandingto be acquiredb ut preventst he Largers caleb ehaviourt o be predictede ffectively. This thesis presentsf our hydro-morphodynamicc ase studies to demonstratet he utility of complex adaptives ystema pproachesfo r studying coastals ystems.T he first two demonstrate the application of Artificial Neural Networks, whilst the latter two illustrate the application of EvolutionaryC omputation.C aseS tudy #I considerst he natureo f the discrepancyb etweent he observedl ocation of wave breakingp atternso ver submergeds andbarsa nd the actual sandbar locations.A rtificial Neural Networks were able to quantitativelyc orrectt he observedlo cations to produce reliable estimates of the actual sand bar locations. Case Study #2 considers the developmenot f an approachf or the discriminationo f shorelinel ocation in video imagesf or the productiono f intertidal mapso f the nearshorer egion. In this caset he systemm odelledb y the Artificial Neural Network is the nature of the discrimination model carried out by the eye in delineating a shoreline feature between regions of sand and water. The Artificial Neural Network approachw as shownt o robustly recognisea rangeo f shorelinef eaturesa t a variety of beaches and hydrodynamic settings. Case Study #3 was the only purely hydrodynamic study consideredin the thesis.I t investigatedth e use of Evolutionary Computationt o provide means of developing a parametric description of directional wave spectra in both reflective and nonreflective conditions. It is shown to provide a unifying approach which produces results which surpassedth ose achievedb y traditional analysisa pproachese vent hough this may not strictly have been considered as a fidly complex system. Case Study #4 is the most ambitious applicationa nd addressetsh e needf or data reductiona s a precursorw hen trying to study large scalem orphodynamicd ata sets.I t utilises EvolutionaryC omputationa pproachesto extractt he significant morphodynamic variability evidenced in both directly and remotely sampled nearshorem orphologiesS. ignificantd atar eductioni s achievedw hilst reWning up to 90% of the original variability in the data sets. These case studies clearly demonstrate the ability of complex adaptive systems to be successfidly applied to coastal system studies. This success has been shown to equal and sometimess urpasst he results that may be obtained by traditional approachesT. he strong performance of Complex Adaptive System approaches is closely linked to the level of complexity or non-linearity of the system being studied. Based on a qualitative evaluation, Evolutionary Computation was shown to demonstrate an advantage over Artificial Neural Networks in terms of the level of new insights which may be obtained. However, utility also needs to consider general ease of applicability and ease of implementation of the study approach.I n this sense,A rtificial Neural Networks demonstratem ore utility for the study of coastals ystems.T he qualitative assessmenatp proachu sedt o evaluatet he cases tudiesi n this thesis, may be used as a guide for choosingt he appropriatenesso f either Artificial Neural Networks or Evolutionary Computation for future coastal system studies

Management of concurrency in a reliable object-oriented computing system

PhD ThesisModern computing systems support concurrency as a means of increasing the performance of the system. However, the potential for increased performance is not without its problems. For example, lost updates and inconsistent retrieval are but two of the possible consequences of unconstrained concurrency. Many concurrency control techniques have been designed to combat these problems; this thesis considers the applicability of some of these techniques in the context of a reliable object-oriented system supporting atomic actions. The object-oriented programming paradigm is one approach to handling the inherent complexity of modern computer programs. By modeling entities from the real world as objects which have well-defined interfaces, the interactions in the system can be carefully controlled. By structuring sequences of such interactions as atomic actions, then the consistency of the system is assured. Objects are encapsulated entities such that their internal representation is not externally visible. This thesis postulates that this encapsulation should also include the capability for an object to be responsible for its own concurrency control. Given this latter assumption, this thesis explores the means by which the property of type-inheritance possessed by object-oriented languages can be exploited to allow programmers to explicitly control the level of concurrency an object supports. In particular, a object-oriented concurrency controller based upon the technique of two-phase locking is described and implemented using type-inheritance. The thesis also shows how this inheritance-based approach is highly flexible such that the basic concurrency control capabilities can be adopted unchanged or overridden with more type-specific concurrency control if requiredUK Science and Engineering Research Council, Serc/Alve

The classroom transferability of a university-based inset programme of workshops in practical work for senior high school Biology educators

Professional criteria for assessing (a) the success and transferability of the programme and (b) the quality of the research evidence gathered from the Biology teachers and their learners in Cape Town, were adopted from a combination of the theoretical frameworks for INSET evaluation recommended by several authors, including the American National Science Standards (1996), Tamir (1997) and Oyasi & Oyasi (2000). The post-workshop data indicated that educators enjoyed the practical activities, and were active in implementing a number of them with their classes in subsequent years. It further revealed that their confidence in engaging in practicalwork improved significantly. To verify or corroborate these findings, ten educators observed at from the 1999 course were interviewed from 2002 to 2005. One educator was observed at two different schools, with different socio-economic backgrounds. The interviews were transcribed and five of the educators were observed while they dealt with the practical activities learnt during this series of workshops. The visual data from the classroom observations, and the interviewswere further processed and compared to the quantitative statistical data. It was It was found that, of the eight schools, four well-resourced schools implemented the programme successfully. This was in terms of the number of practical activities from the course that had been transferred to the classroom. Three of the under-resourced schools, with larger classes, also implemented the course successfully. This was due to the skills and motivation which the educators gained whilst participating in this series of workshops. In two of the schools the high rate of vandalism and the heavy workload of the educators was excessive to the point that they could not implement the programme successfully