A solution for fault-tolerance in replicated database systems

A distributed database system is subject to site failure and link failure. This paper presents a reactive system approach to achieving the fault-tolerance in such a system. The reactive system concepts are an attractive paradigm for system design, development and maintenance because it separates policies from mechanisms. In the paper we give a solution using different reactive modules to implement the fault-tolerant policies and the failure detection mechanisms. The solution shows that they can be separated without impact on each other thus the system can adapt to constant changes in user requirements.

Geographical dislocation and adjustment in university students: the impact of attachment, autonomy and coping behaviour on stress and well-being

The relative contribution of geographical dislocation, attachment styles, coping behaviours, and autonomy, to successful student adjustment, was examined in relation to stress and well-being. A sample of 142 on campus first year university students, across four Victorian university campuses completed self-report questionnaires. Questionnaires included demographic, social network, intrapsychic (attachment and autonomy), and coping variables. Multiple regression analysis revealed that being female, not having made a friend to confide in personal matters, lower achieved autonomy, and use of emotion-focused coping predicted higher levels of student stress. A second multiple regression analysis revealed that living away from home, and preferring others to approach oneself to initiate conversation or friendships predicted lower well-being, whilst increased frequency of phone and email contact, and greater secure parent and peer attachment, predicted greater well-being. Pearson's correlations indicated that securely attached students used more problem focused coping and social support, whereas insecurely attached students used more emotion focused coping. Qualitative data indicated student concerns about being away from family and friends, finance, course direction and structure, social opportunities on campus, and generally adjusting to the university culture. It was concluded that first year on-campus students would benefit from program initiatives targeting enhancement of on-campus social opportunities, development of autonomy, problem focused coping behaviour, interpersonal and social assertiveness.

The cost of recovery protocols in web-based database systems

The cost of recovery protocols is important with respect to system performance during normal operation and failure in terms of overhead, and time taken to recover failed transactions. The cost of recovery protocols for web database systems has not been addressed much. In this paper, we present a quantitative study of cost of recovery protocols. For this purpose, we use an experiment setup to evaluate the performance of two recovery algorithms, namely the, two-phase commit algorithm and log-based algorithm. Our work is a step towards building reliable protocols for web database systems.

A novel middleware based web database model

In this paper, we propose a novel model for web-based database systems based on the multicast and anycast' protocols. In the model, we design a middleware, castway, which locates between the database server and the Web server. Every castway in a distributed system operates as a multicast node and an anycast node independently, respectively. The proposed mechanism can balance the workload among the distributed database servers, and offers the "best" server to serve for a query. Three algorithms are employed for the model: the requirement-based probing algorithm for anycast routing, the atomic multicast update algorithm for database synchronization, and the job deviation algorithm for system workload balance. The simulations and experiments show that the proposed model works very well.

Workforce trends in specialist and GP obstetric practice in Victoria

OBJECTIVE: To provide a contemporary picture of the general practitioner and specialist obstetric workforce in Victoria.

DESIGN, PARTICIPANTS AND SETTING: Postal census by questionnaire of all 317 Fellows and 961 Diplomates on the Victorian database of the Royal Australian and New Zealand College of Obstetricians and Gynaecologists in September 2003.

MAIN OUTCOME MEASURES: Sex, age and geographical distributions and patterns of retirement from and recruitment to the GP and specialist obstetric workforce in Victoria.

RESULTS: 244 Fellows (77.0%) and 652 Diplomates (67.8%) participated. The average age of Diplomates was 42 years; only 20% were involved in procedural obstetrics. Of GPs practising procedural obstetrics, 56% intended to cease within 7 years. Two-thirds of specialist obstetricians continued to practise obstetrics. Among those ceasing obstetrics, almost half had done so since 2000. Among Fellows ceasing obstetric practice, there is a peak in the 50-60-years age group, but cessation of obstetric practice occurred across all age groups.

CONCLUSION: The proportion of GPs involved in procedural obstetrics has fallen markedly over the past decade, with half of those ceasing practice in the 40-50-years age group. New GPs entering the workforce with the Diploma and overseas doctors are unlikely to meet the procedural workforce shortfall. Attracting the large cohort of doctors aged 40-50 years back to obstetric practice must be a priority. Given the pattern of retirements from obstetrics, there will be insufficient numbers of specialists to maintain current levels of service. The reasons include non-participation in obstetrics by new graduates and international medical graduates, the inadequate number of new graduates, and the predominance of women among specialists aged under 40 years, whose work output tends to be affected by family commitments.

CIDB: Chlamydia Interactive Database for cross-querying genomics, transcriptomics and proteomics data

Chlamydiae are important pathogens of humans, birds and a wide range of animals. They are a unique group of bacteria, characterized by their developmental cycle. Chlamydia has been difficult to study because of their obligate intracellular growth habit and lack of a genetic transformation system. However, the past 5 years has seen the full genome sequencing of seven strains of Chlamydia and a rapid expansion of genomic, transcriptomic (RT-PCR, microarray) and proteomic analysis of these pathogens. The Chlamydia Interactive Database (CIDB) described here is the first database of its type that holds genomic, RT-PCR, microarray and proteomics data sets that can be cross-queried by researchers for patterns in the data. Combining the data of many research groups into a single database and cross-querying from different perspectives should enhance our understanding of the complex cell biology of these pathogens. The database is available at: http://www3.it.deakin.edu.au:8080/CIDB/.

Development and applications of an experimental database for structural engineering education

A great number of research organisations in Japan have been conducting structural steel experiments for many years, particularly seismic tests of steel structures like cyclic-loading and pseudo-dynamic tests, in order to determine their seismic performances. However, the original test data gained by most research organisations are not well stored in an appropriate manner for distribution and possible usage by others. With the rapid development of information networks, structural engineers and researchers are able to exchange various types of test data through the Internet. In this paper, the authors present the development of a distributed collaborative database system for structural steel experiments. The database is made available on the Internet, and the use of Java language enables efficient interactive retrieval. The potential applications of the developed database system for structural engineering education are validated for the retrieval of experimental data and seismic numerical analysis.

A provisional database for the silicon content of foods in the United Kingdom

Si may play an important role in bone formation and connective tissue metabolism. Although biological interest in this element has recently increased, limited literature exists on the Si content of foods. To further our knowledge and understanding of the relationship between dietary Si and human health, a reliable food composition database, relevant for the UK population, is required. A total of 207 foods and beverages, commonly consumed in the UK, were analysed for Si content. Composite samples were analysed using inductively coupled plasma–optical emission spectrometry following microwave-assisted digestion with nitric acid and H2O2. The highest concentrations of Si were found in cereals and cereal products, especially less refined cereals and oat-based products. Fruit and vegetables were highly variable sources of Si with substantial amounts present in Kenyan beans, French beans, runner beans, spinach, dried fruit, bananas and red lentils, but undetectable amounts in tomatoes, oranges and onions. Of the beverages, beer, a macerated whole-grain cereal product, contained the greatest level of Si, whilst drinking water was a variable source with some mineral waters relatively high in Si. The present study provides a provisional database for the Si content of UK foods, which will allow the estimation of dietary intakes of Si in the UK population and investigation into the role of dietary Si in human health.

An exploration of sense of community, part 3: dimensions and predictors of psychological sense of community in geographical communities

Within the discipline of community psychology there remains considerable debate as to the latent structure of psychological sense of community (PSOC). One of the few theoretical discussions is that of McMillan and Chavis (1986), who hypothesized four dimensions: Belonging; Fulfillment of Needs; Influence; and Shared Connections. Discussion has also emerged in the literature regarding the role of identification within PSOC. However few studies have empirically investigated the role of identification in PSOC. The current study explored PSOC in a sample of residents of rural, regional and urban geographical communities (N = 669). In an endeavor to clarify the underlying dimensions of PSOC, a test battery included several measures of PSOC as well as measures of identification with the community. The study also examined the role of demographic factors in predicting PSOC. Results provided support for McMillan and Chavis' (1986) four dimensions of PSOC. Further, a fifth dimension emerged, that of Conscious Identification, suggesting that identification is separate to existing dimensions of PSOC. The demographic factors significantly associated with PSOC were type of region, with rural participants displaying higher PSOC than their urban counterparts; participation in local organizations; having children; and a vision of one’s neighborhood as broader than just a street or block. These results, and the implications for PSOC research, are discussed.

Experimentation and self learning in continuous database marketing

We present a method for continuous database marketing that identifies target customers for a number of marketing offers using predictive models. The algorithm then selects the appropriate offer for the customer. Experimental design principles are encapsulated to capture more information that will be used to monitor and refine the predictive models. The updated predictive models are then used for the next round of marketing offers.

A systemic approach to the database marketing process

The role of database marketing (DBM) has become increasingly important for organisations that have large databases of information on customers with whom they deal directly. At the same time, DBM models used in practice have increased in sophistication. This paper examines a systemic view of DBM and the role of analytical techniques within DBM. It extends existing process models to develop a systemic model that encompasses the increased complexity of DBM in practice. The systemic model provides a framework to integrate data mining, experimental design and prioritisation decisions. This paper goes on to identify opportunities for research in DBM, including DBM process models used in practice, the use of evolutionary operations techniques in DBM, prioritisation decisions, and the factors that surround the uptake of DBM.

A scalable and robust framework for agent-based heterogeneous database operation

How to operate database efficiently and unfailingly in agent-based heterogeneous data source environment is becoming a big problem. In this paper, we contribute a framework and develop a couple of agent-oriented matchmakers with logical ring organization structure to match task agents' requests with middleware agents of databases. The middleware agent is a wrapper of a specific database and is run on the same server with the database management system. The matchmaker is of the features of proliferation and self-cancellation according to the sensory input from its environment. The ring-based coordination mechanism of matchmakers is designed. Two kinds of matchmakers, namely, host and duplicate, are designed for improving the scalability and robustness of agent-based system. The middleware agents are improved for satisfying the framework. We demonstrate the potentials of the framework by case study and present theoretical and empirical evidence that our approach is scalable and robust.