Bounds on end-to-end performance of networks employing erasure control coding

Erasure control coding has been exploited in communication networks with an aim to improve the end-to-end performance of data delivery across the network. To address the concerns over the strengths and constraints of erasure coding schemes in this application, we examine the performance limits of two erasure control coding strategies, forward erasure recovery and adaptive erasure recovery. Our investigation shows that the throughput of a network using an (n, k) forward erasure control code is capped by r =k/n when the packet loss rate p ≤ (te/n) and by k(l-p)/(n-te) when p > (t e/n), where te is the erasure control capability of the code. It also shows that the lower bound of the residual loss rate of such a network is (np-te)/(n-te) for (te/n) < p ≤ 1. Especially, if the code used is maximum distance separable, the Shannon capacity of the erasure channel, i.e. 1-p, can be achieved and the residual loss rate is lower bounded by (p+r-1)/r, for (1-r) < p ≤ 1. To address the requirements in real-time applications, we also investigate the service completion time of different schemes. It is revealed that the latency of the forward erasure recovery scheme is fractionally higher than that of the scheme without erasure control coding or retransmission mechanisms (using UDP), but much lower than that of the adaptive erasure scheme when the packet loss rate is high. Results on comparisons between the two erasure control schemes exhibit their advantages as well as disadvantages in the role of delivering end-to-end services. To show the impact of the bounds derived on the end-to-end performance of a TCP/IP network, a case study is provided to demonstrate how erasure control coding could be used to maximize the performance of practical systems. © 2010 IEEE.

Radiation Dose to the Lens of the Eye from Computed Tomography Scans of the Head

While it is well known that exposure to radiation can result in cataract formation, questions still remain about the presence of a dose threshold in radiation cataractogenesis. Since the exposure history from diagnostic CT exams is well documented in a patient’s medical record, the population of patients chronically exposed to radiation from head CT exams may be an interesting area to explore for further research in this area. However, there are some challenges in estimating lens dose from head CT exams. An accurate lens dosimetry model would have to account for differences in imaging protocols, differences in head size, and the use of any dose reduction methods.

The overall objective of this dissertation was to develop a comprehensive method to estimate radiation dose to the lens of the eye for patients receiving CT scans of the head. This research is comprised of a physics component, in which a lens dosimetry model was derived for head CT, and a clinical component, which involved the application of that dosimetry model to patient data.

The physics component includes experiments related to the physical measurement of the radiation dose to the lens by various types of dosimeters placed within anthropomorphic phantoms. These dosimeters include high-sensitivity MOSFETs, TLDs, and radiochromic film. The six anthropomorphic phantoms used in these experiments range in age from newborn to adult.

First, the lens dose from five clinically relevant head CT protocols was measured in the anthropomorphic phantoms with MOSFET dosimeters on two state-of-the-art CT scanners. The volume CT dose index (CTDIvol), which is a standard CT output index, was compared to the measured lens doses. Phantom age-specific CTDIvol-to-lens dose conversion factors were derived using linear regression analysis. Since head size can vary among individuals of the same age, a method was derived to estimate the CTDIvol-to-lens dose conversion factor using the effective head diameter. These conversion factors were derived for each scanner individually, but also were derived with the combined data from the two scanners as a means to investigate the feasibility of a scanner-independent method. Using the scanner-independent method to derive the CTDIvol-to-lens dose conversion factor from the effective head diameter, most of the fitted lens dose values fell within 10-15% of the measured values from the phantom study, suggesting that this is a fairly accurate method of estimating lens dose from the CTDIvol with knowledge of the patient’s head size.

Second, the dose reduction potential of organ-based tube current modulation (OB-TCM) and its effect on the CTDIvol-to-lens dose estimation method was investigated. The lens dose was measured with MOSFET dosimeters placed within the same six anthropomorphic phantoms. The phantoms were scanned with the five clinical head CT protocols with OB-TCM enabled on the one scanner model at our institution equipped with this software. The average decrease in lens dose with OB-TCM ranged from 13.5 to 26.0%. Using the size-specific method to derive the CTDIvol-to-lens dose conversion factor from the effective head diameter for protocols with OB-TCM, the majority of the fitted lens dose values fell within 15-18% of the measured values from the phantom study.

Third, the effect of gantry angulation on lens dose was investigated by measuring the lens dose with TLDs placed within the six anthropomorphic phantoms. The 2-dimensional spatial distribution of dose within the areas of the phantoms containing the orbit was measured with radiochromic film. A method was derived to determine the CTDIvol-to-lens dose conversion factor based upon distance from the primary beam scan range to the lens. The average dose to the lens region decreased substantially for almost all the phantoms (ranging from 67 to 92%) when the orbit was exposed to scattered radiation compared to the primary beam. The effectiveness of this method to reduce lens dose is highly dependent upon the shape and size of the head, which influences whether or not the angled scan range coverage can include the entire brain volume and still avoid the orbit.

The clinical component of this dissertation involved performing retrospective patient studies in the pediatric and adult populations, and reconstructing the lens doses from head CT examinations with the methods derived in the physics component. The cumulative lens doses in the patients selected for the retrospective study ranged from 40 to 1020 mGy in the pediatric group, and 53 to 2900 mGy in the adult group.

This dissertation represents a comprehensive approach to lens of the eye dosimetry in CT imaging of the head. The collected data and derived formulas can be used in future studies on radiation-induced cataracts from repeated CT imaging of the head. Additionally, it can be used in the areas of personalized patient dose management, and protocol optimization and clinician training.

The Roles of ‘Conventional’ and Demand-Responsive Bus Services

Purpose - The roles of ‘conventional’ (fixed-route and fixed-timetable) bus services is examined and compared to demand-responsive services, taking rural areas in England as the basis for comparison. It adopts a ‘rural’ definition of settlements under a population of 10,000. Design/methodology/approach - Evidence from the National Travel Survey, technical press reports and academic work is brought together to examine the overall picture. Findings - Inter-urban services between towns can provide a cost-effective way of serving rural areas where smaller settlements are suitably located. The cost structures of both fixed-route and demand-responsive services indicate that staff time and cost associated with vehicle provision are the main elements. Demand-responsive services may enable larger areas to be covered, to meet planning objectives of ensuring a minimum of level of service, but experience often shows high unit cost and public expenditure per passenger trip. Economic evaluation indicates user benefits per passenger trip of similar magnitude to existing average public expenditure per trip on fixed-route services. Considerable scope exists for improvements to conventional services through better marketing and service reliability. Practical implications - The main issue in England is the level of funding for rural services in general, and the importance attached to serving those without access to cars in such areas. Social implications - The boundary between fixed-route and demand-responsive operation may lie at relatively low population densities. Originality/value - The chapter uses statistical data, academic research and operator experience of enhanced conventional bus services to provide a synthesis of outcomes in rural areas.

Rules for the governance of coastal and marine ecosystem services: An evaluative framework based on the IAD framework

There is an increasing need for a comprehensive institutional understanding pertaining to ecosystem services (ESs) in coastal and marine fields. This paper develops a systematic framework to inform coastal and marine governance about the integration of ES concepts. First, as a theoretical basis, we analyze the generic rules that are part of the Institutional Analysis and Development (IAD) framework. Second, by an extensive literature review, we formulate a set of ES-specific rules and develop an evaluative framework for coastal and marine governance. Third, we examine this evaluative framework in a specific action situation, namely coastal strategic planning concerning Qingdao, China. Results from the literature review and the case study reveal that when designing ES-specific rules for coastal and marine governance, there are several socio-spatial and economic aspects that should be taken into account: (1) conceive of stakeholders as ES users, (2) capture the effect of ecological scaling, (3) understand ES interactions and clarify indirect impacts and causalities, (4) account for ES values, and (5) draw on economic choices for use rights to deal with ES issues.

Bio-fuelling the Hummer? Transdisciplinary Thoughts on Techno-Optimism and Innovation in the Transition from Unsustainability

An overarching aim of this chapter is to offer an informed and critical analysis of ‘techno-optimism’, informed by an explicitly transdisciplinary approach. A transdisciplinary perspective is one in which knowledge production goes beyond the academy to include end non-academic stakeholders and users. In effect it seeks to ‘upstream’ the involvement of non-academic interests in research design and knowledge production, as opposed to limiting those non-academic interests to the dissemination end point stage of research, which is the dominant research model. Techno-optimism is understood as an exaggerated and unwarranted belief in human technological abilities to solve problems of unsustainability while minimising or denying the need for large-scale social, economic and political transformation. More specifically, techno-optimism is the belief that the negative environmental and social costs of high-consumption, affluent, consumer societies and associated ways of life within capitalist orthodox economic growth orientated socio-economic systems, can be solved or eradicated through technological innovation and breakthroughs. Business as usual can be ‘greened’; a capitalist, growth-based economy can be made more ‘resource efficient’, consumerism less ‘resource intensive’ (and maybe a little bit more ethical). Techno-optimism, to be deliberately provocative for a moment, can therefore be described as a ‘biofuel the hummer’ response to the challenges (and opportunities) of the crisis of unsustainability. What I mean by that analogy is the seductive promise and premise of techno-optimism of not questioning or doubting the status quo (the hummer), hence it’s putative (but entirely false) non-political character. The capitalist, consumerist, growth-based socio-economic system is thus removed from critical analysis (usually on the implicit or explicit assumption of either the normative rightness of this system, or on strategic political grounds that it is naive or utopian to envisage widespread support for a non or post-capitalist consumer system). Techno-optimism simply enables a different means (biofuel) to the same ends.

Catalysing the Irish Energy Transition: Capacities and Challenges

The transition to a “low carbon, climate resilient and environmentally sustainable economy by the end of the 
year 2050” has been conceptualised as the “national transition objective” in the Irish Climate Action and Low Carbon Development Bill, passed in late 2015. This has raised a myriad of questions over how this can be operationalised and resourced and whether it can maintain political momentum. This paper assesses the utility of framings informed by the transitions (MLP) and technological innovation systems perspectives in contributing to transformative societal processes, by examining their application in an Irish case study on policy and technology. Through a qualitative exploration of the broader societal and policy context of the energy sector and a more detailed examination of the innovation systems of selected niche technologies (bioenergy and electric vehicles), the Irish case study sought to identify potential catalysts for a sustainability transition in the energy sector in Ireland: where these exist, how these are being built or enabled, and barriers to change. Following a discussion on the theoretical approaches used, a description will be given of how these were applied in the conducting of the research on transition in Ireland case study and the key findings which emerged. A critical reflection will then be made on the utility of these perspectives (as applied) to contribute to broader processes of societal transformation in Ireland.

Policy for the Provision and Management of Cleaning Services (PDF 464KB)

This policy sets out the Department’s commitment to maintaining and improving environmental cleanliness in Northern Ireland (NI). It has been developed with the aim that best management practice, staff training and continued monitoring of performance will lead to services being maintained and improved in a challenging financial climate. The detail of the policy is presented in the three sections which follow this executive summary. Section 1 – Introduction and Background. This section sets out the aims, objectives and scope of the policy. It also sets out the key principles which should apply to cleaning services. Section 2 - Developments since the launch of Cleanliness Matters Strategy in October 2005. This outlines events and progress since 2005 and indicates how these are shaping the proposed strategic direction. Section 3 - The Way Forward. This section sets out the areas for attention over the coming years.  

What do GPs and Bereaved Parents Think About Paediatric Oncologists and Palliative Care?

Aim The aim of the study was to examine the experiences of bereaved parents and general practitioners (GPs) following the death of a child with cancer within the family home. This presenta-tion focuses on one of the findings; the parent and GP views on the hospital consultants’ involvement in the palliative care. Design A community based qualitative study.Setting West Midlands region, UK. Participants Purposeful sample of 18 GPs and 11 bereaved families. The sample was drawn from the families and GPs of children who had been treated for cancer at a regional childhood cancer centre and who subsequently died within the family home. Methods One-to-one semi-structured tape-recorded interviews were undertaken with GPs and bereaved parents following the death at home of a child with cancer. GPs were contacted three months after the death of the child and the parents at six months. Thematic analysis of the transcriptions was undertaken. Findings Parents described feeling abandoned at the transition to palliation when management of care transferred to the GP. Families did not perceive a seamless service of medical care between hospital and community. Where offered consultant contact was valued by families and GPs. Text and email were used by families as a means of asking the consultant questions. The GPs lacked role clarity where the consultant continued involvement in the care. Conclusions The transition to palliation and the transfer of care to community services needs to be sensitively and actively man-aged for the family and the GP. Medical care between tertiary andprimary care should be seen as a continuum. Improving GP: consultant communication could aid role clarity, identify mecha-nisms for support and advice, and promote the active engagement of the GP in the care. Exploring opportunities for integrated con-sultant: GP working could maximise mutual learning and support and enhance care provision. The level, access and duration of ongoing contact between consultants and families/GPs require clarity.

Providing Palliative Care for the Child with Cancer: The Experience of GPs

Background Childhood cancers are rare and general practitioners (GPs) have limited experience in caring for these children and even less in providing their palliative care. Most families prefer that their child is cared for at home in the palliative phase of their illness, with professional support from those known to them (Chambers and Oakhill 1995, Vickers and Carlisle 2000, Craft and Killen 2007). A community based qualitative study examined the experiences of ten GPs following their involvement in the care of a child with cancer receiving palliative care within the family home. Methods Data collection was through 1:1 in-depth interviews and facilitated case discussion supported by field notes and grounded theory analysis (chronological comparative data analysis identifying generated themes). Social worlds theory was used as a framework to aid examination, and facilitate critical understanding, of the experiences of the GPs. Findings This presentation focuses on five of the findings relating to the experiences of the GP; the impact of minimal contact; lack of knowledge and experience, uncertain role, out of hours service provision and the emotional toll. Findings highlighted that GPs often have to re-establish their role at the child’s transition to palliative care. Factors hindering the GP in this process include a deficit of specialist knowledge and experience of paediatric palliative care and lack of role clarity. Conclusions/points of interest Strategies for enhancing the role of the Macmillan team in supporting GPs have been identified by this study, such as enhanced collaborative working. Findings have also provided further confirmation of the substantial variation in out of hours medical palliative care provision; with evidence that some GPs work beyond their remit in providing informal out of hours care. This presentation details the findings of one aspect (the experiences of GPs) of a wider study that explored the experiences of 54 community based health professionals (GPs, community nurses and allied health professionals) who had been involved in caring for a dying with cancer receiving palliative care at home (Neilson 2009).

Event Monitoring Web Services for Heterogeneous Information Systems

Heterogeneity has to be taken into account when integrating a set of existing information sources into a distributed information system that are nowadays often based on Service- Oriented Architectures (SOA). This is also particularly applicable to distributed services such as event monitoring, which are useful in the context of Event Driven Architectures (EDA) and Complex Event Processing (CEP). Web services deal with this heterogeneity at a technical level, also providing little support for event processing. Our central thesis is that such a fully generic solution cannot provide complete support for event monitoring; instead, source specific semantics such as certain event types or support for certain event monitoring techniques have to be taken into account. Our core result is the design of a configurable event monitoring (Web) service that allows us to trade genericity for the exploitation of source specific characteristics. It thus delivers results for the areas of SOA, Web services, CEP and EDA.

The Effect of Non-Audit Services on Auditor Independence : A study on 11 food retail- and wholesale companies in the United Kingdom

Purpose – The purpose of this study is to investigate the effect of non-audit services on auditor independence, and the importance of non-audit services as a source of income for audit firms in the United Kingdom. Design/method/approach – This study will examine 11 companies in the food retail- and wholesale industry during 2007 - 2014. Five indicators have been used; (1) Appointed auditor and provision of non-audit services to audit clients; (2) Auditor tenure; (3) Non-audit services in relation to total services; (4) Tax-services in relation to non-audit services, (5) Big Four’s revenue. Information has been collected using the quantitative approach through annual- and transparency reports. The threshold used to measure possible independence threats (self-review-, self-interest- and familiarity threat) has been set at 18,5 %. Findings – This study concludes that the jointly provision of audit- and nonaudit services possibly causes impairment of auditor independence, and that non-audit services is an important source of income for audit firms. The findings showed that in 99 %, companies purchased non-audit services from their statutory auditor. Non-audit services in relation to total services surpassed the threshold in 78 % of all financial years. Likewise, tax-services in comparison to non-audit services exceeded the threshold in 65 % of all financial years. The Big Four’s revenue from non-audit services to audit clients in relation to total revenue is almost constantly below the threshold. However, in all financial years except from one, total revenue from non-audit services surpassed revenue from audit services by far. Contribution – The study contributes to the ongoing discussion about nonaudit services effect on auditor independence. Originality/value – This study is one of few that provide detailed information about non-audit services in the food retail- and wholesale industry. It highlights social and ethical issues with regard to agency relationships.  

Spanish monarchy and the Portuguese Republic: two routes to democratization

From 1974 to 1986 the Iberian Peninsula was the arena of major political changes. The process then undertaken was characterized by the transition from two Iberian authoritarian regimes to two democracies, which enabled both countries to join the European Economic Community (EEC) on 1 January 1986. However, the political vicissitudes until full membership of what became the European Union (EU) was achieved were very different and were decisively, although not exclusively, influenced by the fact Portugal was a republic and Spain a monarchy. In Portugal the 1974 revolution took place with consequent shift of the head of state while in Spain the engine of change was precisely the head of state: King Juan Carlos I. It is also true that despite the dangers to democracy (terrorism in Spain and some radicalism in Portugal) both societies supported the political parties committed to the democratic process in elections, which helped avoid tensions that could have defeated the process. Likewise, it is possible to argue that in Spain a plan to achieve democracy within the rule of law (an archetypal transition) was designed by the head of state, while in Portugal there was no pre-established plan – the programme of the Armed Forces Movement (Movimento das Forças Armadas [MFA]) was a weak and precarious compromise between different visions of the road to follow, enabling an intense political struggle that almost led to civil war and a dangerous state of crisis.

Unmet health needs in patients with coronary heart disease: implications and potential for improvement in caring services

BACKGROUND: Improving the quality of health care services requires tailoring facilities to fulfil patients' needs. Satisfying patients' healthcare needs, listening to patients' opinions and building a closer provider-user partnership are central to the NHS. Few published studies have discussed cardiovascular patients' health needs, but they are not comprehensive and fail to explore the contribution of outcome to needs assessment. METHOD: A comprehensive self-administered health needs assessment (HNA) questionnaire was developed for concomitant use with generic (Short Form-12 and EuroQOL) and specific (Seattle Angina Questionnaire) health-related quality of life (HRQL) instruments on 242 patients admitted to the Acute Cardiac Unit, Nottingham. RESULTS: 38% reported difficulty accessing health facilities, 56% due to transport and 32% required a travelling companion. Mean HRQOL scores were lower in those living alone (P < 0.05) or who reported unsatisfactory accommodation. Dissatisfaction with transport affected patients' ease of access to healthcare facilities (P < 0.001). Younger patients (<65 y) were more likely to be socially isolated (P = 0.01). Women and patients with chronic disease were more likely to be concerned about housework (P < 0.05). Over 65 s (p < 0.05) of higher social classes (p < 0.01) and greater physical needs (p < 0.001) had more social needs, correlating moderately (0.32 < r < 0.63) with all HRQL domains except SAQ-AS. Several HRQL components were highly correlated with the HNA physical score (p < 0.001). CONCLUSIONS: Patients wanted more social (suitable accommodation, companionship, social visits) and physical (help aids, access to healthcare services, house work) support. The construct validity and intra-class reliability of the HNA tool were confirmed. Our results indicate a gap between patients' health needs and available services, highlighting potential areas for improvement in the quality of services

Metabolomics as a tool to explore the staphylococcal biofilm

Orthopaedic infections can be polymicrobial existing as a microbiome. Infections often incorporate staphylococcal species, including Staphylococcus aureus. Such infections can lead to life threatening illness and implant failure. Furthermore, biofilm formation on the implant surface can occur, increasing pathogenicity, exacerbating antibiotic resistance and altering antimicrobial mechanism of action. Bacteria change dramatically during the transition to a biofilm growth state: phenotypically; transcriptionally; and metabolically, highlighting the need for research into molecular mechanisms involved in biofilm formation. Metabolomics can provide a tool to analyse metabolic changes which are directly related to the expressed phenotype. Here, we aimed to provide greater understanding of orthopaedic infection caused by S. aureus and biofilm formation on the implant surface. Through metagenome analysis by employing: implant material extraction; DNA extraction; microbial enrichment; and whole genome sequencing, we present a microbiome study of the infected prosthesis to resolve the causative species of orthopaedic hip infection. Results highlight the presence of S. aureus as a primary cause of orthopaedic infection along with Enterococcus faecium and the presence of secondary pathogen Clostridium difficile. Although results were hindered by the presence of host contaminating DNA even after microbial enrichment, conclusions could be made over the potential increased pathogenicity caused by the presence of a secondary pathogen and highlight method and sample preparation considerations when undertaking such a study. Following this finding, studies were focused on an orthopaedic clinical isolate of S. aureus and a metabolome extraction method for staphylococcal biofilms was developed using cell lysis through bead beating and solvent metabolome extraction. The method was found to be reproducible when coupled with liquid chromatography-mass spectrometry (LC-MS) and bioinformatics, allowing for the detection of significant changes in metabolism between planktonic and biofilm cultures to be identified and drug mechanism of actions (MOA) to be studied. Metabolomics results highlight significant changes in a number of metabolic pathways including arginine biosynthesis and purine metabolism between the two cell populations, evidence of S. aureus responding to their changing environment, including oxygen availability and a decrease in pH. Focused investigations on purine metabolism looking for biofilm modulation effects were carried out. Modulation of the S. aureus biofilm phenotype was observed through the addition of exogenous metabolites. Inosine increased biofilm biomass while formycin B, an inosine analogue, showed a dispersal effect and a potential synergistic effect in biofilm dispersal when coupled with gentamycin. Changes in metabolism between planktonic cells and biofilms highlight the requirement for antimicrobial testing to be carried out against planktonic cells and biofilms. Untargeted metabolomics was used to study the MOA of triclosan in S. aureus. The triclosan target and MOA in bacteria has already been characterised, however, questions remain over its effects in bacteria. Although the use of triclosan has come under increasing speculation, its full effects are still largely unknown. Results show that triclosan can induce a cascade of detrimental events in the cell metabolism including significant changes in amino acid metabolism, affecting planktonic cells and biofilms. Results and conclusions provide greater understanding of orthopaedic infections and specifically focus on the S. aureus biofilm, confirming S. aureus as a primary cause of orthopaedic infection and using metabolomic analysis to look at the changing state of metabolism between the different growth states. Metabolomics is a valuable tool for biofilm and drug MOA studies, helping understand orthopaedic infection and implant failure, providing crucial insight into the biochemistry of bacteria for the potential for inferences to be gained, such as the MOA of antimicrobials and the identification of novel metabolic drug targets.

The relationship of early social, mental, and behavioral experiences with adult obesity and Alcohol Use Disorder

Stressful life events early in life, including symptoms of mental disorders or childhood maltreatment, may increase risk for worse mental and physical health outcomes in adulthood. The purpose of this dissertation was to examine the effects of childhood Attention Deficit Hyperactivity Disorder (ADHD) symptoms and maltreatment experience on two adult outcomes: obesity and alcohol use disorder (AUD). Mediational effects of adolescent characteristics were explored. This dissertation used Waves I, III, and IV of the National Longitudinal Study of Adolescent to Adult Health. In Paper 1 (Chapter 3), we investigated the association between multiple types of child maltreatment and adult objective (body mass index; BMI) and subjective (self-rated) obesity, as well as mediating effects by adolescent characteristics including depressive symptoms and BMI. Results showed that after adjusting for sex, race/ethnicity, and maternal education, physical maltreatment was moderately associated with adulthood obesity as measured by BMI and self-reported obesity, while sexual maltreatment was more strongly associated with the objective measure but not the subjective measure. The indirect effects of mediation of adolescent BMI and depressive symptoms were statistically significant. In Paper 2 (Chapter 4), the objective was to examine mediation by adolescent depressive symptoms, alcohol consumption, peer alcohol consumption, and delinquency in the relationship between ADHD symptoms and adult AUD. The indirect effects of mediation of adolescent delinquency, alcohol consumption, and peer alcohol consumption were statistically significant in single and multiple mediator models. In Paper 3 (Chapter 5), the objective was to assess the joint effects of maltreatment/neglect on adult AUD. After adjusting for sex, race/ethnicity, child maltreatment, and parental AUD, ADHD symptoms were significantly associated with increased odds of AUD. There was no strong evidence of multiplicative interaction by maltreatment. This association was stronger for males than females, although the interaction term was not statistically significant. This dissertation adds to the literature by examining relationships between several major public health problems: ADHD symptoms, childhood maltreatment, AUD, depressive symptoms, and obesity. This project has implications for understanding how early life stress increases risk for later physical and mental health problems, and identifying potential intervention targets for adolescents.