Distributed systems status and control

Concepts are investigated for an automated status and control system for a distributed processing environment. System characteristics, data requirements for health assessment, data acquisition methods, system diagnosis methods and control methods were investigated in an attempt to determine the high-level requirements for a system which can be used to assess the health of a distributed processing system and implement control procedures to maintain an accepted level of health for the system. A potential concept for automated status and control includes the use of expert system techniques to assess the health of the system, detect and diagnose faults, and initiate or recommend actions to correct the faults. Therefore, this research included the investigation of methods by which expert systems were developed for real-time environments and distributed systems. The focus is on the features required by real-time expert systems and the tools available to develop real-time expert systems

Beyond the hegemonic narrative – a study of managers

Purpose – The aim is to analyse managerial behaviour using narrative analysis to identify stories that are often ignored, silenced or missed by the hegemonic managerialist narrative. Design/methodology/approach – An ethnographic narrative based on an 18 month period of participant observation where the author was a manager in a business unit acquired by another company for $1 billion. Findings – Strategy can be diverted or altered by managers lower down the organization in a counter strategy process. This is consistent with Dalton where managers lower down the organization adapt and change strategy to make it work in practice. Research limitations/implications – Participant observation and ethnomethodological narrative analysis have the potential to go beyond the hegemonic managerialist literature and identify a much more complex picture. However, such research is always open to criticism as being from the author's “own perspective” and appearing to claim “omnipresence.” Other stories have been given voice but it is never possible to say that all stories have been recovered from the silencing processes of the organization. Practical implications – A clearer understanding of how management operates counter strategies within an organization in practice. This enables organizations to reconsider how they engage managers beyond the hegemonic narrative. Originality/value – This paper aims to provide an insight into management behaviour beyond the usual treatment of managers as an amorphous mass as is common in most of the hegemonic managerialist narrative. When managers are told the narratives in this paper they can recount their own similar stories yet these are rarely told

Handel's Performing Versions: A Study of Four Music Theatre Works from the 'Second Academy' Period

The dissertation is a reconstruction and evaluation of the different versions of Handel's operas Partenope and Arianna, and his oratorios Esther and Deborah, as composed and as performed under his direction. The first public performances of all four works were given at the King's Theatre in London during the early 1730s, a period commonly described as 'The Second Academy' (1729-34). Chapter 1 examines the organization of the Second Academy, surveys Handel's opera seasons between 1729 and 1737, and presents hypotheses about the composer's artistic planning during a period of unparalleled independence. This establishes the context for the first public performances of Partenope, Arianna in Creta, Esther and Deborah within Handel's career, and outlines his contemporary revivals of these music dramas. Chapters 2-5 present the four case studies in chronological order of their first performances: each chapter contains an investigation of the work's sources, observations about Handel's compositional process, and descriptions of each performing version prepared under his direction (including those made for Oxford and Dublin). Chapter 6 assesses the composer's alterations to both the music and the libretto texts of the four works between the first performance of Partenope in 1730 and his last revival of Esther in 1757 (two years before his death). Using examples drawn from all of his versions of the four case studies, the musico-dramatic impact and artistic significance of his revisions are discussed. There is a long-standing assumption that Handel ruined his own music dramas when revising them for revivals: the dissertation takes the unhindered view of Handel's working methods and creative personality across a remarkable span of his working life (1730-57), and presents evidence that all versions need critical consideration

Innovation and business performance - a provisional multi-regional analysis

Although much attention has focussed on the determinants of firms' innovation performance, the relationship between innovation and business performance is less well defined. In this paper we use data from identical plant level surveys conducted in six regions of the UK, Germany and Ireland to examine this relationship and identify some of the implications for regional innovation initiatives. The survey data used was collected by postal survey during 1999 and 2000. In all over 2000 plants responded to the surveys which provide regionally representative information about innovation activity, IT adoption and a number of indicators of business performance. Four main indicators of business performance are examined here: sales and employment growth, export performance, profitability and productivity (value added per employee). The analysis is based on a simultaneous econometric model explaining plants' innovation activity and business performance. Discussion focuses on a number of key themes. First, core-periphery differences are explored by contrasting analytical results for peripheral (Northern Ireland, Scotland) and 'core' regions (Bavaria, Baden-Wurttemberg) within the sample. Second, attention is focussed on the performance effects of firms, different innovation profiles relating to product and process development but also radical and more incremental innovation activity. Thirdly, contrasts between small and larger businesses are considered and the sensitivity of firms, innovation and performance to their operating environment is explored. The paper concludes with an assessment of the implications of the analysis for regional innovation initiatives and their potential impact on business development.

Rebounding case notifications of chlamydia : an epidemiological game of 'Clue'?

The genus Chlamydiae encompasses a unique class of obligate intracellular bacteria that can cause disease in a wide range of animals. In humans, Chlamydia trachomatis infections are common and are frequently observed in diseases of the eye, genital and respiratory tracts. Prevalent worldwide, Chlamydia infections can progress to chronic inflammatory sequellae and are the leading cause of curable sexually transmitted disease and preventable blindness. After falling in the face of intensified control efforts, case notifications of sexually transmitted Chlamydia in many countries are rising. In many jurisdictions, this unprecedented rise of Chlamydia case notifications has occurred after the introduction of wide spread control programs, and has been discussed to be a result of either increased testing volume, improvements to testing technologies, changes in sexual behaviour, or increased reinfection rates brought about by deleterious effects of treatment on acquired immunity. This thesis seeks to answer the question of why observed Chlamydia case notifications have rebounded? I have attempted to answer this question using simple dynamical models of Chlamydia transmission framed from immunological and epidemiological perspectives. Model structures are drawn from frameworks previously used for studying sexually transmitted infections, and represent a combination of theoretical and data-oriented formulations, as well as different (hierarchical) ecological scales. The results of this thesis highlight that increased testing volumes, rather than changes in the sensitivity and specificity of testing technologies, sexual behaviour, or truncated immunological responses brought about by treatment can explain the increase in observed chlamydia case notifications, and that simple explanations for these observed rates appear to have been dismissed in favor of an increase to the underlying prevalence. In addition to providing insights into current epidemiological trends, this thesis has also been able to produce significant insights into the natural history of chlamydial infection. In particular, the phenotype of an individual's immunobiology that results from multiple chlamydial infections suggests that longer periods between initial and repeat infection may increase an individual's chlamydial load, their duration of infection, as well as non-intuitively the formation of protective immunity, persistent infection, and the potential for immunopathogenesis. Additional population-scale analyses in this thesis also suggest the existence of a period of immunity that is, on average, much longer lasting than currently discussed in contemporary literature. The results of this research outline a potential way forward through filling several gaps in the immunological and epidemiological understanding of Chlamydia infections that involves both reviewing existing data as well as continued research using "systems science" approaches

The epidemiology of infectious mononucleosis in Northern Scotland : a decreasing incidence and winter peak

Peer reviewedPublisher PD

New light on Galactic post-asymptotic giant branch stars. I. First distance catalogue

We have commenced a detailed analysis of the known sample of Galactic post-asymptotic giant branch (PAGB) objects compiled in the Toru\'n catalogue of Szczerba et al., and present, for the first time, homogeneously derived distance determinations for the 209 likely and 87 possible catalogued PAGB stars from that compilation. Knowing distances are essential in determining meaningful physical characteristics for these sources and this has been difficult to determine for most objects previously. The distances were determined by modelling their spectral energy distributions (SED) with multiple black-body curves, and integrating under the overall fit to determine the total distance-dependent flux. This method works because the luminosity of these central stars is very nearly constant from the tip of the AGB phase to the beginning of the white-dwarf cooling track. This then enables us to use a standard-candle luminosity to estimate the SED distances. For Galactic thin disk PAGB objects, we use three luminosity bins based on typical observational characteristics, ranging between 3500 and 12000 L_sun. We further adopt a default luminosity of 1700 L_sun for all halo PAGB objects. We have also applied the above technique to a further sample of 69 related nebulae not in the current edition of the Toru\'n catalogue. In a follow-up paper we will estimate distances to the subset of RV Tauri variables using empirical period-luminosity relations, and to the R\,CrB stars, allowing a population comparison of these objects with the other subclasses of PAGB stars for the first time.Comment: 24 pages, 8 tables, 4 figures. Submitted to MNRAS. Appendix B containing full list of SED figures excluded in this versio

Current crisis or artifact of surveillance: insights into rebound chlamydia rates from dynamic modelling

<p>Abstract</p> <p>Background</p> <p>After initially falling in the face of intensified control efforts, reported rates of sexually transmitted chlamydia in many developed countries are rising. Recent hypotheses for this phenomenon have broadly focused on improved case finding or an increase in the prevalence. Because of many complex interactions behind the spread of infectious diseases, dynamic models of infection transmission are an effective means to guide learning, and assess quantitative conjectures of epidemiological processes. The objective of this paper is to bring a unique and robust perspective to observed chlamydial patterns through analyzing surveillance data with mathematical models of infection transmission.</p> <p>Methods</p> <p>This study integrated 25-year testing volume data from the Canadian province of Saskatchewan with one susceptible-infected-treated-susceptible and three susceptible-infected-treated-removed compartmental models. Calibration of model parameters to fit observed 25-year case notification data, after being combined with testing records, placed constraints on model behaviour and allowed for an approximation of chlamydia prevalence to be estimated. Model predictions were compared to observed case notification trends, and extensive sensitivity analyses were performed to confirm the robustness of model results.</p> <p>Results</p> <p>Model predictions accurately mirrored historic chlamydial trends including an observed rebound in the mid 1990s. For all models examined, the results repeatedly highlighted that increased testing volumes, rather than changes in the sensitivity and specificity of testing technologies, sexual behaviour, or truncated immunological responses brought about by treatment can, explain the increase in observed chlamydia case notifications.</p> <p>Conclusions</p> <p>Our results highlight the significant impact testing volume can have on observed incidence rates, and that simple explanations for these observed increases appear to have been dismissed in favor of changes to the underlying prevalence. These simple methods not only demonstrate geographic portability, but the results reassure the public health effort towards monitoring and controlling chlamydia.</p

A unified framework of immunological and epidemiological dynamics for the spread of viral infections in a simple network-based population

<p>Abstract</p> <p>Background</p> <p>The desire to better understand the immuno-biology of infectious diseases as a broader ecological system has motivated the explicit representation of epidemiological processes as a function of immune system dynamics. While several recent and innovative contributions have explored unified models across cellular and organismal domains, and appear well-suited to describing particular aspects of intracellular pathogen infections, these existing immuno-epidemiological models lack representation of certain cellular components and immunological processes needed to adequately characterize the dynamics of some important epidemiological contexts. Here, we complement existing models by presenting an alternate framework of anti-viral immune responses within individual hosts and infection spread across a simple network-based population.</p> <p>Results</p> <p>Our compartmental formulation parsimoniously demonstrates a correlation between immune responsiveness, network connectivity, and the natural history of infection in a population. It suggests that an increased disparity between people's ability to respond to an infection, while maintaining an average immune responsiveness rate, may worsen the overall impact of an outbreak within a population. Additionally, varying an individual's network connectivity affects the rate with which the population-wide viral load accumulates, but has little impact on the asymptotic limit in which it approaches. Whilst the clearance of a pathogen in a population will lower viral loads in the short-term, the longer the time until re-infection, the more severe an outbreak is likely to be. Given the eventual likelihood of reinfection, the resulting long-run viral burden after elimination of an infection is negligible compared to the situation in which infection is persistent.</p> <p>Conclusion</p> <p>Future infectious disease research would benefit by striving to not only continue to understand the properties of an invading microbe, or the body's response to infections, but how these properties, jointly, affect the propagation of an infection throughout a population. These initial results offer a refinement to current immuno-epidemiological modelling methodology, and reinforce how coupling principles of immunology with epidemiology can provide insight into a multi-scaled description of an ecological system. Overall, we anticipate these results to as a further step towards articulating an integrated, more refined epidemiological theory of the reciprocal influences between host-pathogen interactions, epidemiological mixing, and disease spread.</p

Susceptibility of Pediococcus isolates to antimicrobial compounds in relation to hop-resistance and beer-spoilage

<p>Abstract</p> <p>Background</p> <p>Though important in the context of food microbiology and as potential pathogens in immuno-compromised humans, bacterial isolates belonging to the genus <it>Pediococcus </it>are best known for their association with contamination of ethanol fermentation processes (beer, wine, or fuel ethanol). Use of antimicrobial compounds (e.g., hop-compounds, Penicillin) by some industries to combat <it>Pediococcus </it>contaminants is long-standing, yet knowledge about the resistance of pediococci to antimicrobial agents is minimal. Here we examined <it>Pediococcus </it>isolates to determine whether antibiotic resistance is associated with resistance to hops, presence of genes known to correlate with beer spoilage, or with ability to grow in beer.</p> <p>Results</p> <p>Lactic acid bacteria susceptibility test broth medium (LSM) used in combination with commercially available GPN3F antimicrobial susceptibility plates was an effective method for assessing antimicrobial susceptibility of <it>Pediococcus </it>isolates. We report the finding of Vancomycin-susceptible <it>Pediococcus </it>isolates from four species. Interestingly, we found that hop-resistant, beer-spoilage, and beer-spoilage gene-harbouring isolates had a tendency to be more susceptible, rather than more resistant, to antimicrobial compounds.</p> <p>Conclusion</p> <p>Our findings indicate that the mechanisms involved in conferring hop-resistance or ability to spoil beer by <it>Pediococcus </it>isolates are not associated with resistance to antibiotics commonly used for treatment of human infections. Also, Vancomycin-resistance was found to be isolate-specific and not intrinsic to the genus as previously believed.</p