The realisation of JSD specifications in object oriented languages

Jackson System Development (JSD) is an operational software development method which addresses most of the software lifecycle either directly or by providing a framework into which more specialised techniques can fit. The method has two major phases: first an abstract specification is derived that is in principle executable; second the specification is implemented using a variety of transformations. The object oriented paradigm is based on data abstraction and encapsulation coupled to an inheritance architecture that is able to support software reuse. Its claims of improved programmer productivity and easier program maintenance make it an important technology to be considered for building complex software systems. The mapping of JSD specifications into procedural languages typified by Cobol, Ada, etc., involves techniques such as inversion and state vector separation to produce executable systems of acceptable performance. However, at present, no strategy exists to map JSD specifications into object oriented languages. The aim of this research is to investigate the relationship between JSD and the object oriented paradigm, and to identify and implement transformations capable of mapping JSD specifications into an object oriented language typified by Smalltalk-80. The direction which the transformational strategy follows is one whereby the concurrency of a specification is removed. Two approaches implementing inversion - an architectural transformation resulting in a simulated coroutine mechanism being generated - are described in detail. The first approach directly realises inversions by manipulating Smalltalk-80 system contexts. This is possible in Smalltalk-80 because contexts are first class objects and are accessible to the user like any other system object. However, problems associated with this approach are expounded. The second approach realises coroutine-like behaviour in a structure called a `followmap'. A followmap is the results of a transformation on a JSD process in which a collection of followsets is generated. Each followset represents all possible state transitions a process can undergo from the current state of the process. Followsets, together with exploitation of the class/instance mechanism for implementing state vector separation, form the basis for mapping JSD specifications into Smalltalk-80. A tool, which is also built in Smalltalk-80, supports these derived transformations and enables a user to generate Smalltalk-80 prototypes of JSD specifications.

The use of ERS-1 crossovers and TOPEX/Poseidon repeat pass data for global sea surface variability studies

In previous sea-surface variability studies, researchers have failed to utilise the full ERS-1 mission due to the varying orbital characteristics in each mission phase, and most have simply ignored the Ice and Geodetic phases. This project aims to introduce a technique which will allow the straightforward use of all orbital phases, regardless of orbit type. This technique is based upon single satellite crossovers. Unfortunately the ERS-1 orbital height is still poorly resolved (due to higher air drag and stronger gravitational effects) when compared with that of TOPEX/Poseidon (T/P), so to make best use of the ERS-1 crossover data corrections to the ERS-1 orbital heights are calculated by fitting a cubic-spline to dual-crossover residuals with T/P. This correction is validated by comparison of dual satellite crossovers with tide gauge data. The crossover processing technique is validated by comparing the extracted sea-surface variability information with that from T/P repeat pass data. The two data sets are then combined into a single consistent data set for analysis of sea-surface variability patterns. These patterns are simplified by the use of an empirical orthogonal function decomposition which breaks the signals into spatial modes which are then discussed separately. Further studies carried out on these data include an analysis of the characteristics of the annual signal, discussion of evidence for Rossby wave propagation on a global basis, and finally analysis of the evidence for global mean sea level rise.

Assessing the efficacy of structural merger remedies:choosing between theories of harm?

This paper shows that many structural remedies in a sample of European merger cases result in market structures which would probably not be cleared by the Competition Authority (CA) if they were the result of merger (rather than remedy).This is explained by the fact that the CA’s objective through remedy is to restore premerger competition, but markets are often highly concentrated even before merger. If so, the CA must often choose between clearing an ‘uncompetitive’merger, or applying an unsatisfactory remedy. Here, the CA appears reluctant to intervene against coordinated effects, if doing so enhances a leader’s dominance.

Unilateral versus coordinated effects:comparing the impact on consumer welfare of alternative merger outcomes

The nature of tacitly collusive behaviour often makes coordination unstable, and this may result in periods of breakdown, during which consumers benet from reduced prices. This is allowed for by adding demand uncertainty to the Compte et al. (2002) model of tacit collusion amongst asymmetric rms. Breakdowns occur when a rm cannot exclude the possibility of a deviation by a rival. It is then possible that an outcome with collusive behaviour, subject to long/frequent break downs, can improve consumer welfare compared to an alternative with sustained unilateral conduct. This is illustrated by re-examining the Nestle/Perrier merger analyzed by Compte et al., but now also taking into account the potential for welfare losses arising from unilateral behaviour.

Assessing the efficacy of structural merger remedies:choosing between theories of harm?

Previous empirical assessments of the effectiveness of structural merger remedies have focused mainly on the subsequent viability of the divested assets. Here, we take a different approach by examining how competitive are the market structures which result from the divestments. We employ a tightly specified sample of markets in which the European Commission (EC) has imposed structural merger remedies. It has two key features: (i) it includes all mergers in which the EC appears to have seriously considered, simultaneously, the possibility of collective dominance, as well as single dominance; (ii) in a previous paper, for the same sample, we estimated a model which proved very successful in predicting the Commission’s merger decisions, in terms of the market shares of the leading firms. The former allows us to explore the choices between alternative theories of harm, and the latter provides a yardstick for evaluating whether markets are competitive or not – at least in the eyes of the Commission. Running the hypothetical post-remedy market shares through the model, we can predict whether the EC would have judged the markets concerned to be competitive, had they been the result of a merger rather than a remedy. We find that a significant proportion were not competitive in this sense. One explanation is that the EC has simply been inconsistent – using different criteria for assessing remedies from those for assessing the mergers in the first place. However, a more sympathetic – and in our opinion, more likely – explanation is that the Commission is severely constrained by the pre-merger market structures in many markets. We show that, typically, divestment remedies return the market to the same structure as existed before the proposed merger. Indeed, one can argue that any competition authority should never do more than this. Crucially, however, we find that this pre-merger structure is often itself not competitive. We also observe an analogous picture in a number of markets where the Commission chose not to intervene: while the post-merger structure was not competitive, nor was the pre-merger structure. In those cases, however, the Commission preferred the former to the latter. In effect, in both scenarios, the EC was faced with a no-win decision. This immediately raises a follow-up question: why did the EC intervene for some, but not for others – given that in all these cases, some sort of anticompetitive structure would prevail? We show that, in this sample at least, the answer is often tied to the prospective rank of the merged firm post-merger. In particular, in those markets where the merged firm would not be the largest post-merger, we find a reluctance to intervene even where the resulting market structure is likely to be conducive to collective dominance. We explain this by a willingness to tolerate an outcome which may be conducive to tacit collusion if the alternative is the possibility of an enhanced position of single dominance by the market leader. Finally, because the sample is confined to cases brought under the ‘old’ EC Merger Regulation, we go on to consider how, if at all, these conclusions require qualification following the 2004 revisions, which, amongst other things, made interventions for non-coordinated behaviour possible without requiring that the merged firm be a dominant market leader. Our main conclusions here are that the Commission appears to have been less inclined to intervene in general, but particularly for Collective Dominance (or ‘coordinated effects’ as it is now known in Europe as well as the US.) Moreover, perhaps contrary to expectation, where the merged firm is #2, the Commission has to date rarely made a unilateral effects decision and never made a coordinated effects decision.

Evaluating the impact of a web-based resource on student learning

This paper reports on an experiment of using a publisher provided web-based resource to make available a series of optional practice quizzes and other supplementary material to all students taking a first year introductory microeconomics module. The empirical analysis evaluates the impact these supplementary resources had on student learning. First, we investigate which students decided to make use of the resources. Then, we analyse the impact this decision has on their subsequent performance in the examination at the end of the module. The results show that, even after taking into account the possibility of self-selection bias, using the web-based resource had a significant positive effect on student learning.

The attitudes of students and academic staff towards electronic course support:are we convergent?

The present study investigates the views and attitudes of both the students and staff with regard to the usefulness of electronic course support throughout all four years of the MPharm programme at Aston University. Students were sampled between January and March 2001 using a self-completion questionnaire administered during the start of a practical or tutorial class. All internal academic staff were interviewed using a semi-structured interview format. Response rates were 100 and 89.5%, respectively. The study found that students rapidly embraced the use of electronic course support within the undergraduate programme, although they view its role as augmenting traditional course delivery. This view was mirrored by the academic staff, although only around a half currently place their material on the University's virtual learning environment (VLE), WebCT. The failure of staff to completely embrace the VLE is grounded in a lack of confidence and ability in its use. A majority of the academic staff indicated that they wish to be trained further in the use of information technology. Academic institutions need to understand and meet these needs in parallel with the introduction of any electronic course support.

Transferring knowledge of manufacturing techniques in multinational corporations:preliminary findings

With the growth of the multinational corporation (MNC) has come the need to understand how parent companies transfer knowledge to, and manage the operations of, their subsidiaries. This is of particular interest to manufacturing companies transferring their operations overseas. Japanese companies in particular have been pioneering in this regard, with techniques such as the Toyota Production System (TPS) for transferring the ethos of Japanese manufacturing and maintaining quality and control in overseas subsidiaries. A great deal has been written about the process of transferring Japanese manufacturing techniques, but much less is understood about how the subsidiaries themselves, which are required to make use of such techniques, actually acquire and incorporate them into their operations. The research on which this paper is based therefore examines how, from the perspective of the subsidiary, knowledge of manufacturing techniques is transferred from the parent company. There is clearly a need to take a practice-based view to understanding how the local managers and operatives incorporate knowledge about manufacturing techniques into their working practices. In-depth qualitative research was, therefore, conducted in the subsidiary of a Japanese multinational, Denso Corporation, involving three main manufacturing initiatives (or philosophies), namely ‘TPS’, ‘TPM’ and ‘TS’. The case data were derived from 52 in-depth interviews with project members, moderate participant observations, and documentations. The aim of this paper is to present the preliminary findings from the case analyses. The research contributes to our understanding of knowledge transfer in relation to the circumstances of the selection between adaptation and replication of knowledge in the subsidiary from its parent. In particular this understanding relates to transfer across different flows and levels in the organisational hierarchy, how the whole process is managed, and also how modification takes place.