High-Level Abstractions for Programming Network Policies

The emergence of network programmability enabled by innovations such as active network- ing, SDN and NFV offers tremendous flexibility to program network policies. However, it also poses a new demand to network operators on programming network policies. The motivation of this dissertation is to study the feasibility of using high-level abstractions to simplify the programming of network policies. First, we propose scenario-based programming, a framework that allows network operators to program stateful network policies by describing example behaviors in representative scenarios. Given these scenarios, our scenario-based programming tool NetEgg automatically infers the controller state that needs to be maintained along with the rules to process network events and update state. The NetEgg interpreter can execute the generated policy implementation on top of a centralized controller, but also automatically infers flow-table rules that can be pushed to switches to improve throughput. We study a range of policies considered in the literature and report our experience regarding specifying these policies using scenarios. We evaluate NetEgg based on the computational requirements of our synthesis algorithm as well as the overhead introduced by the generated policy implementation. Our results show that our synthesis algorithm can generate policy implementations in seconds, and the automatically generated policy implementations have performance comparable to their hand-crafted implementations. Our preliminary user study results show that NetEgg was able to reduce the programming time of the policies we studied. Second, we propose NetQRE, a high-level declarative language for programming quantitative network policies that require monitoring a stream of network packets. Based on a novel theoretical foundation of parameterized quantitative regular expressions, NetQRE integrates regular-expression-like pattern matching at flow-level as well as application-level payloads with aggregation operations such as sum and average counts. We describe a compiler for NetQRE that automatically generates an efficient implementation from the specification in NetQRE. Our evaluation results demonstrate that NetQRE is expressive to specify a wide range of quantitative network policies that cannot be naturally specified in other systems. The performance of the generated implementations is comparable with that of the manually-optimized low-level code. NetQRE can be deployed in different settings. Our proof-of-concept deployment shows that NetQRE can provide timely enforcement of quantitative network policies

Developing a model of mental health self-care support for children and young people through an integrated evaluation of available types of provision involving systematic review, meta-analysis and case study

Background The mental health of children and young people (CYP) is a major UK public health concern. Recent policy reviews have identified that service provision for CYP with mental health needs is not as effective, responsive, accessible or child-centred as it could be. Following on from a previous National Institute for Health Research (NIHR) study into self-care support for CYP with long-term physical health needs, this study explored self-care support’s potential in CYP’s mental health. Objectives To identify and evaluate the types of mental health self-care support used by, and available to, CYP and their parents, and to establish how such support interfaces with statutory and non-statutory service provision. Design Two inter-related systematic literature reviews (an effectiveness review with meta-analysis and a perceptions review), together with a service mapping exercise and case study. Setting Global (systematic reviews); England and Wales (mapping exercise and case study). Participants (case study) Fifty-two individuals (17 CYP, 16 family members and 19 staff) were interviewed across six sites. Main outcome measures (meta-analysis) A measure of CYP’s mental health symptomatology. Data sources (literature reviews) MEDLINE, Cumulative Index to Nursing and Allied Health Literature (CINAHL), PsycINFO, All Evidence-Based Medicine (EBM) Reviews, Applied Social Sciences Index and Abstracts (ASSIA) and Education Resources Information Center (ERIC). Review methods Titles and abstracts of papers were screened for relevance then grouped into studies. Two independent reviewers extracted data from studies meeting the inclusion criteria. A descriptive analysis and meta-analysis were conducted for the effectiveness review; descriptive analyses were conducted for the perceptions review. These analyses were integrated to elicit a mixed-methods review. Results Sixty-five of 71 included studies were meta-analysable. These 65 studies elicited 71 comparisons which, when meta-analysed, suggested that self-care support interventions were effective at 6-month [standardised mean difference (SMD) = −0.20; 95% confidence interval (CI) −0.28 to −0.11] and 12-month (SMD = −0.12; 95% CI −0.17 to −0.06) follow-ups. However, judged against Cochrane criteria, the studies were mostly low quality. Key elements of self-care support identified in the perceptions review were the acquisition of knowledge and skills, peer support and the relationship with the self-care support agent; CYP also had different perceptions from adults about what is important in self-care support. The mapping exercise identified 27 providers of 33 self-care support services. According to the case study data, effective self-care support services are predicated on flexibility; straightforward access; non-judgemental, welcoming organisations and staff; the provision of time and attention; opportunities to learn and practise skills relevant to self-care; and systems of peer support. Conclusions Mental health self-care support interventions for CYP are modestly effective in the short to medium term. Self-care support can be conceptualised as a process which has overlap with ‘recovery’. CYP and their families want choice and flexibility in the provision of such interventions and a continued relationship with services after the nominal therapy period. Those delivering self-care support need to have specific child-centred attributes. Future work Future work should focus on under-represented conditions (e.g. psychosis, eating disorders, self-harm); the role of technology, leadership and readiness in self-care support; satisfaction in self-care support; the conceptualisation of self-care support in CYP’s mental health; and efficacy and cost-effectiveness

Modeling the near-UV band of GK stars, Paper II: NLTE models

We present a grid of atmospheric models and synthetic spectral energy distributions (SEDs) for late-type dwarfs and giants of solar and 1/3 solar metallicity with many opacity sources computed in self-consistent Non-Local Thermodynamic Equilibrium (NLTE), and compare them to the LTE grid of Short & Hauschildt (2010) (Paper I). We describe, for the first time, how the NLTE treatment affects the thermal equilibrium of the atmospheric structure (T(tau) relation) and the SED as a finely sampled function of Teff, log g, and [A/H] among solar metallicity and mildly metal poor red giants. We compare the computed SEDs to the library of observed spectrophotometry described in Paper I across the entire visible band, and in the blue and red regions of the spectrum separately. We find that for the giants of both metallicities, the NLTE models yield best fit Teff values that are ~30 to 90 K lower than those provided by LTE models, while providing greater consistency between \log g values, and, for Arcturus, Teff values, fitted separately to the blue and red spectral regions. There is marginal evidence that NLTE models give more consistent best fit Teff values between the red and blue bands for earlier spectral classes among the solar metallicity GK giants than they do for the later classes, but no model fits the blue band spectrum well for any class. For the two dwarf spectral classes that we are able to study, the effect of NLTE on derived parameters is less significant.Comment: Submitted to The Astrophysical Journal. Observed spectrophotometric library, and grids of NLTE and LTE) synthetic spectra for GK stars available at http://www.ap.smu.ca/~ishort/PHOENI

Vascular Function Intervention Trial in sickle cell disease (V-FIT): Trial Protocol

This protocol outlines procedures for capturing participant information as part of the V-FIT study. The protocol should not be used as a guide for the treatment of other participants; every care was taken in its drafting, but corrections or amendments may be necessary. This trial adheres to the principles outlined in the International Conference on Harmonisation Good Clinical Practice (ICH GCP) guidelines, protocol and all applicable local regulations

Spin-dependent phenomena and device concepts explored in (Ga,Mn)As

Over the past two decades, the research of (Ga,Mn)As has led to a deeper understanding of relativistic spin-dependent phenomena in magnetic systems. It has also led to discoveries of new effects and demonstrations of unprecedented functionalities of experimental spintronic devices with general applicability to a wide range of materials. In this article we review the basic material properties that make (Ga,Mn)As a favorable test-bed system for spintronics research and discuss contributions of (Ga,Mn)As studies in the general context of the spin-dependent phenomena and device concepts. Special focus is on the spin-orbit coupling induced effects and the reviewed topics include the interaction of spin with electrical current, light, and heat.Comment: 47 pages, 41 figure

Automated Fixing of Programs with Contracts

This paper describes AutoFix, an automatic debugging technique that can fix faults in general-purpose software. To provide high-quality fix suggestions and to enable automation of the whole debugging process, AutoFix relies on the presence of simple specification elements in the form of contracts (such as pre- and postconditions). Using contracts enhances the precision of dynamic analysis techniques for fault detection and localization, and for validating fixes. The only required user input to the AutoFix supporting tool is then a faulty program annotated with contracts; the tool produces a collection of validated fixes for the fault ranked according to an estimate of their suitability. In an extensive experimental evaluation, we applied AutoFix to over 200 faults in four code bases of different maturity and quality (of implementation and of contracts). AutoFix successfully fixed 42% of the faults, producing, in the majority of cases, corrections of quality comparable to those competent programmers would write; the used computational resources were modest, with an average time per fix below 20 minutes on commodity hardware. These figures compare favorably to the state of the art in automated program fixing, and demonstrate that the AutoFix approach is successfully applicable to reduce the debugging burden in real-world scenarios.Comment: Minor changes after proofreadin