QoS Considerations in OBS Switched Backbone Net-Works

Optical Burst Switching (OBS) was proposed as a hybrid switching technology solution to handle the multi-Terabit volumes of traffic anticipated to traverse Future Generation backbone Networks. With OBS, incoming data packets are assembled into super-sized packets called data bursts and then assigned an end to end light path. Key challenging areas with regards to OBS Networks implementation are data bursts assembling and scheduling at the network ingress and core nodes respectively as they are key to minimizing subsequent losses due to contention among themselves in the core nodes. These losses are significant contributories to serious degradation in renderable QoS. The paper overviews existing methods of enhancing it at both burst and transport levels. A distributed resources control architecture is proposed together with a proposed wavelength assignment algorithm

Clock Synchronisation Assisted Clock and Data Recovery for Sub-Nanosecond Data Centre Optical Switching

In current `Cloud' data centres, switching of data between servers is performed using deep hierarchies of interconnected electronic packet switches. Demand for network bandwidth from emerging data centre workloads, combined with the slowing of silicon transistor scaling, is leading to a widening gap between data centre traffic demand and electronically-switched data centre network capacity. All-optical switches could offer a future-proof alternative, with potentially under a third of the power consumption and cost of electronically-switched networks. However, the effective bandwidth of optical switches depends on their overall switching time. This is dominated by the clock and data recovery (CDR) locking time, which takes hundreds of nanoseconds in commercial receivers. Current data centre traffic is dominated by small packets that transmit in tens of nanoseconds, leading to low effective bandwidth, as a high proportion of receiver time is spent performing CDR locking instead of receiving data, removing the benefits of optical switching. High-performance optical switching requires sub-nanosecond CDR locking time to overcome this limitation. This thesis proposes, models, and demonstrates clock synchronisation assisted CDR, which can achieve this. This approach uses clock synchronisation to simplify the complexity of CDR versus previous asynchronous approaches. An analytical model of the technique is first derived that establishes its potential viability. Following this, two approaches to clock synchronisation assisted CDR are investigated: 1. Clock phase caching, which uses clock phase storage and regular updates in a 2km intra-building scale data centre network interconnected by single-mode optical fibre. 2. Single calibration clock synchronisation assisted CDR}, which leverages the 20 times lower thermal sensitivity of hollow core optical fibre versus single-mode fibre to synchronise a 100m cluster scale data centre network, with a single initial phase calibration step. Using a real-time FPGA-based optical switch testbed, sub-nanosecond CDR locking time was demonstrated for both approaches

Reducing Internet Latency : A Survey of Techniques and their Merit

Bob Briscoe, Anna Brunstrom, Andreas Petlund, David Hayes, David Ros, Ing-Jyh Tsang, Stein Gjessing, Gorry Fairhurst, Carsten Griwodz, Michael WelzlPeer reviewedPreprin

Foundations of Behavioral Health

Even in the twenty-first century, the public health community continues to face formidable challenges. There is a need for more integrative and collaborative approaches in public health initiatives, considering the complex relationships among the social determinants of health within natural and built environments, population health and health-care systems, and economic, education, and social and community contexts. The continuing changes in the landscape of public health challenge our ability to reconceptualize our approach to how health-care professionals can contribute to health promotion, health education, and disease prevention efforts in communities constantly facing the globalization of communicable and noncommunicable diseases and environmental threats due to man-made and natural disasters

Understanding the role of evidence in e-cigarette regulation and policy development

Background: Public health recommendations should be informed by the best available evidence. E-cigarette policy has varied across jurisdictions, contrasting with the previous coordinated approach of international tobacco control communities. An understanding of such divergence may help inform future public health policy. Using e-cigarettes as a case study, this thesis examines the role and use of evidence in the development of public health recommendations. Methods: This multi-methods case study focused on e-cigarette recommendations from the WHO, UK, Australia, and USA; and comprised: a document analysis of recommendations; a citation network analysis of the evidence cited and their conflicts of interest (COI); an analysis of the guideline development documents which described the processes for developing recommendations, including managing COI; expert interviews with individuals involved in developing recommendations; and triangulation across these data sources. Results: Analysis of public health recommendations showed that different jurisdictions supported different e-cigarette policy approaches, with the UK following a ‘harm reduction’ approach, while the WHO, Australia, and USA followed a more ‘precautionary’ approach. Analysing the evidence cited by the recommendation documents revealed that substantial COI, such as pre-existing relationships between the e-cigarette and tobacco industries, were present within the cited evidence. Examination of the processes for collecting and managing COI, illustrated variation across public health bodies, often with a lack of transparency. Triangulating across the data demonstrated the myriad contextual factors (e.g., previous and current tobacco policies) influencing the role and use of evidence in the development of e-cigarette recommendations. I highlight how internal contextual factors (e.g., the remit of the document) were often influenced by external contextual factors (e.g., epidemiological features of smoking and vaping) and interact in subtle ways to frame the focus of recommendations and the evidence underpinning them. Conclusion: Contextual factors are crucial in understanding divergence in e-cigarette recommendations across jurisdictions, with similar evidence used by public health bodies internationally. COI are common in the evidence base and a lack of standardisation in managing COI might threaten evidence-informed decision-making. This thesis suggests internal and external contextual factors interact and that this interplay may help explain the divergence in e-cigarette policy approaches

A mixed methods investigation into aspects of medication wastage in Malta.

Reducing medication wastage is a paramount objective in promoting appropriate utilisation of finite resources and preventing negative consequences. The aim of this research was to investigate aspects of medication wastage in Malta by applying mixed methods research and, by doing so, contribute original knowledge to this area. A systematic review was conducted to appraise critically, synthesize and present the available evidence on the possible causative factors associated with medication wastage and the effectiveness of any interventions focusing on wastage reduction as an outcome measure. Findings indicated that only one published paper reported a definition of medication wastage. The main factors contributing to wastage were change in medication, patient's death, resolution of patient's condition and passed expiry date. Very few studies reported medication wastage as an outcome measure. The Delphi technique was applied to define medication wastage and its contributory factors in the context of the Maltese population. A definition for medication wastage was generated with 86% of panellists agreeing/totally agreeing and sixty-one possible factors leading to wastage were identified by the panellists. The perspectives of the Maltese population, healthcare professionals and students on medication wastage were investigated through cross-sectional surveys. Results of questionnaires indicate lack of patient education and knowledge with the free healthcare system and the overstocking of medication by patients due to previous or potential out of stock situations as contributors to medication wastage. The beliefs and behaviours regarding medication wastage of the Maltese public and healthcare professionals were explored during focus groups. The theoretical domains framework was adopted to design the focus group guide and to interpret systematically the findings. Five key themes emerged which were proposed as solutions to minimise medication wastage: system effects, practitioner effects, patients effects, political effects and awareness and educational effects Research results and findings from all four phases will facilitate the systematic development of strategies and policies, with emphasis on prioritisation, with the aim of minimising medication wastage at all levels

Digital Research Cycles: How Attitudes Toward Content, Culture And Technology Affect Web Development.

It has been estimated that one third of the world\u27s population does not have access to adequate health care. Some 1.6 billion people live in countries experiencing concentrated acquired immune deficiency syndrome (AIDS) epidemics. Many countries in Africa--and other low-income countries--are in dire need of help providing adequate health care services to their citizens. They require more hands-on care from Western health workers--and training so more African health workers can eventually care for their own citizens. But these countries also need assistance acquiring and implementing both texts--the body of medical information potentially available to them--and technology--the means by which that information can be conveyed. This dissertation looks at these issues and others from a multi-faceted approach. It combines a survey of the developers of Web sites designed for use by health workers in low-income countries and a proposal for a novel approach to communication theory, which could help improve health communication and other social marketing practices. It also includes an extensive review of literature regarding a number of topics related to these issues. To improve healthcare services in low-income countries, several things should occur. First, more health workers--and others--could visit African countries and other places to provide free, hands-on medical care, as this researcher\u27s group did in Uganda. Such trips are ideal occasions for studying the cultural differences between mzungu (white man) and the Ugandan people. A number of useful medical texts have been written for health workers in low-income countries. Others will be published as new health information becomes available. But on what medium will they be published? Computers? Personal digital assistants? During the past 10 years the Internet became an ideal venue for conveying information. Unfortunately, people in target countries such as Uganda encounter cultural differences when such new technologies are diffused. This dissertation looks at cultural and technological difficulties encountered by people in low-income countries who attempt to diffuse information and communication technologies (ICT). Once a technology has been successfully adopted, someone will look for ways to use it to help others. There are hundreds of sites on the Internet--built by Web developers in Western countries--that are designed for use by health workers in low-income countries. However, these Web developers also experience cultural and technological differences, based on their knowledge of and attitudes toward best practices in their field. This research includes a survey of Web developers which determined their attitudes toward best practices in their field and tested this researcher\u27s hypothesis that there is no significant difference among the developers\u27 attitudes toward the content on their sites, their audience\u27s cultural needs and the various technological needs their audience has. It was found that the Web developers agree with 17 of 18 perceived best practices and that there is a significant difference between Web developers\u27 attitudes toward their audience\u27s technological needs and their attitudes toward quality content and the audience\u27s cultural needs. Creation of the survey herein resulted in this researcher generating a new way of thinking about communication theory--called digital research cycles. The survey was based on a review of literature and is rooted in the belief that any successful communication of a computer-mediated message in the information age is a behavior which is influenced by the senders\u27 and receivers\u27 attitudes and knowledge about textual style, the audience, technology and the subject matter to which the message pertains