Towards Probabilistic and Partially-Supervised Structural Health Monitoring

One of the most significant challenges for signal processing in data-based structural health monitoring (SHM) is a lack of comprehensive data; in particular, recording labels to describe what each of the measured signals represent. For example, consider an offshore wind-turbine, monitored by an SHM strategy. It is infeasible to artificially damage such a high-value asset to collect signals that might relate to the damaged structure in situ; additionally, signals that correspond to abnormal wave-loading, or unusually low-temperatures, could take several years to be recorded. Regular inspections of the turbine in operation, to describe (and label) what measured data represent, would also prove impracticable -- conventionally, it is only possible to check various components (such as the turbine blades) following manual inspection; this involves travelling to a remote, offshore location, which is a high-cost procedure. Therefore, the collection of labelled data is generally limited by some expense incurred when investigating the signals; this might include direct costs, or loss of income due to down-time. Conventionally, incomplete label information forces a dependence on unsupervised machine learning, limiting SHM strategies to damage (i.e. novelty) detection. However, while comprehensive and fully labelled data can be rare, it is often possible to provide labels for a limited subset of data, given a label budget. In this scenario, partially-supervised machine learning should become relevant. The associated algorithms offer an alternative approach to monitor measured data, as they can utilise both labelled and unlabelled signals, within a unifying training scheme. In consequence, this work introduces (and adapts) partially-supervised algorithms for SHM; specifically, semi-supervised and active learning methods. Through applications to experimental data, semi-supervised learning is shown to utilise information in the unlabelled signals, alongside a limited set of labelled data, to further update a predictive-model. On the other hand, active learning improves the predictive performance by querying specific signals to investigate, which are assumed the most informative. Both discriminative and generative methods are investigated, leading towards a novel, probabilistic framework, to classify, investigate, and label signals for online SHM. The findings indicate that, through partially-supervised learning, the cost associated with labelling data can be managed, as the information in a selected subset of labelled signals can be combined with larger sets of unlabelled data -- increasing the potential scope and predictive performance for data-driven SHM

The development of the protective tariff legislation in the United States

Abstract unavailable

The range of axial rotation of the glenohumeral joint.

Accepted versio

Ammonium Fluoride as a Hydrogen-disordering Agent for Ice

The removal of residual hydrogen disorder from various phases of ice with acid or base dopants at low temperatures has been a focus of intense research for many decades. As an antipode to these efforts, we now show using neutron diffraction that ammonium fluoride (NH4F) is a hydrogen-disordering agent for the hydrogen-ordered ice VIII. Cooling its hydrogen-disordered counterpart ice VII doped with 2.5 mol% ND4F under pressure leads to a hydrogen-disordered ice VIII with ~31% residual hydrogen disorder illustrating the long-range hydrogen-disordering effect of ND4F. The doped ice VII could be supercooled by ~20 K with respect to the hydrogen-ordering temperature of pure ice VII after which the hydrogen-ordering took place slowly over a ~60 K temperature window. These findings demonstrate that ND4F-doping slows down the hydrogen-ordering kinetics quite substantially. The partial hydrogen order of the doped sample is consistent with the antiferroelectric ordering of pure ice VIII. Yet, we argue that local ferroelectric domains must exist between ionic point defects of opposite charge. In addition to the long-range effect of NH4F-doping on hydrogen-ordered water structures, the design principle of using topological charges should be applicable to a wide range of other 'ice-rule' systems including spin ices and related polar materials.Comment: 23 pages, 4 figures, 2 table

The Anatomy of Quantum Many-Body Scars: Origins and Implementations

Quantum many-body scars (QMBS) are a mechanism for many-body interacting systems to resist thermalisation. QMBS systems host a subset of atypical, non thermal eigenstates which are responsible for coherent oscillatory dynamics when these systems are prepared in special initial states. There exist two categories of QMBS. Firstly, there are `exact scars', which arise due to spectrum generating algebras (SGA), resulting in perfect oscillations for all times. On the other hand, there exist `approximate scars', which have been observed in experiment and are responsible for decaying oscillatory dynamics. The purpose of this thesis is to explain the origin of approximate scars, make predictions of new models expected to host them, and to realise approximate scarred dynamics experimentally. We show approximate scars arise due to algebraic structures analogous to SGA. These structures are known as `broken' Lie algebras. Understanding approximate scars at the level of a Lie algebra allows us to systematically derive higher order corrections which interpolate between approximate scarring and exact scarring. In addition, for models with a single revival frequency, indicative of some su(2) algebraic structure, we introduce a complementary approach of studying embedded hypercubic structures contained within the adjacency graph of the scarred Hamiltonian. Inspired by the notions of approximate algebraic relations and embedded graph structures, we introduce a general method of constructing scarred models via kinetic constraints. Finally, by utilising the suppressed entropy growth typical of QMBS models, we implement scarred dynamics on a quantum computer

Surveying ‘Dating Violence’ and Stalking Victimisation among Students at an English University : Findings and Methodological Reflections on Using a US Survey Instrument

Domestic abuse and stalking in higher education (HE) have been overlooked in research in comparison to sexual harassment and sexual violence. This article reports on survey data from 725 students at an English university using measures of stalking and ‘dating violence’—physical and psychological violence from an intimate partner—from a US survey instrument (the Administrator Researcher Campus Climate Collaborative (ARC3) survey). According to this measure, 26% of respondents had been subjected to ‘dating violence’ and 16% to stalking behaviours. However, these findings need to be contextualised within a critical discussion about the use of the ARC3 survey tool in the English context. The ARC3 questions on ‘dating violence’ focus on physical and ‘psychological violence’; the questions therefore omit further types of domestic abuse under UK definitions. In relation to stalking, US definitions—as captured in the ARC3 survey instrument—define specific behaviours. By contrast, in England and Wales, stalking involves behaviours that engender fear or distress in a pattern of behaviour over time. These differences mean that the ARC3 modules on stalking and ‘dating violence’ would need to be significantly adapted to be suitable for use in England and Wales

Physical activity advocacy and promotion: The South African experience

Background. The global mandate by the WHO World Health Report of 2002, Global Strategy for Diet, Physical Activity and Health, were mirrored by the policy environment in South Africa. The ‘Vuka South Africa – Move for your Health’ campaign was an example of an initiative adopted by national government, promoting physical activity (PA) for health. Methods. This manuscript describes the process, events and lessons learned during the initial phase of Vuka SA from 2004 to 2010. Data were obtained from the grey literature, minutes and reports of meetings and from stakeholders. Results. Utilising a multi-sectoral approach, this initiative was partnered by governmental and non-governmental organisations, the private sector and tertiary institutions. The main anticipated short-term outcome was an increased awareness of the message (‘move for your health’), with a view to achieving increased population levels of participation in health-enhancing physical activity over the long term. Vuka SA was initiated by the National Department of Health and launched in 2005. Subsequently, 36 partner organisations participated in two national workshops, who together with provincial health promoters undertook to promote the campaign. This was followed by an international training course on PA and public health for policy makers and programme implementers, and the subsequent call for the development of an African Physical Activity Network. Discussion. Although the campaign has not yet undergone rigorous evaluation and participation at present appears to be modest, there are promising examples of multi-sectoral awareness and advocacy activities resulting in some national dissemination of the role of PA in health promotion

The Cambridge Law Corpus: A Corpus for Legal AI Research

We introduce the Cambridge Law Corpus (CLC), a corpus for legal AI research. It consists of over 250 000 court cases from the UK. Most cases are from the 21st century, but the corpus includes cases as old as the 16th century. This paper presents the first release of the corpus, containing the raw text and meta-data. Together with the corpus, we provide annotations on case outcomes for 638 cases, done by legal experts. Using our annotated data, we have trained and evaluated case outcome extraction with GPT-3, GPT-4 and RoBERTa models to provide benchmarks. We include an extensive legal and ethical discussion to address the potentially sensitive nature of this material. As a consequence, the corpus will only be released for research purposes under certain restrictions

Many patients with persistent pain one year after TKA report improvement by 5-7 years: A mixed methods study

This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal.Background: Approximately 20% of patients report pain 12 months after TKA. No studies have investigated patients’ experiences of living with persistent postsurgical pain 5 to 7 years after TKA by combining a qualitative and quantitative methodology. Question/purpose: In a mixed-methods study, we explored patients’ experiences of living with persistent pain up to 7 years after primary TKA. We asked: In a subgroup analysis of patients who reported persistent pain 1 year after TKA surgery, how do patients live with persistent pain at the 5- to 7-year postoperative timepoint? Methods: This follow-up study was part of a longitudinal study of pain, symptoms, and health-related quality of life in patients who underwent TKA for osteoarthritis. The present study targeted a subgroup of patients (22% [45 of 202]) identified in the longitudinal study who reported no improvement in pain interference with walking at 12 months after surgery. Inclusion criteria were: all 31 patients in this subgroup who attended their 5-year follow-up at the hospital and lived within a 2-hour drive from the hospital. Eight patients declined or were unable to participate due to illness or death. Hence, the final sample consisted of 23 patients (13 women and 10 men). The participants’ mean age at surgery was 66 6 10 years. There were no differences in sociodemographic baseline data between the 23 included and the 22 excluded participants. A mixed-methods approach was employed, in which the quantitative data were followed up and investigated with qualitative interviews. Instruments used were the Brief Pain Inventory preoperatively, 12 months, and 5 years after surgery, as well as a semistructured interview guide. The individual interviews were conducted at one timepoint 5 to 7 years postsurgery to capture how pain was experienced at that timepoint. The interviews were audiorecorded, transcribed, and analyzed using qualitative content analysis. Meaning units were identified, condensed, and sorted into subthemes that were interpreted and abstracted into themes, guided by the research question. With a small sample, the quantitative analysis focused on descriptive statistics and nonparametric statistics when comparing demographics of included and nonincluded patients. In addition, two multivariate mixed models for repeated measures were employed to estimate within‐patient and between‐patient variations as well as to assess the effect of time on the pain outcomes. Results: Pain with walking decreased from 12 months to 5 years postoperatively (estimated mean score 7 versus 4, difference of means -3 [95% CI -5 to -2]; p < 0.001). Pain with daily activity decreased from 12 months to 5 years postoperatively (estimated mean score 6 versus 3, difference of means -3 [95% CI -4 to -1]; p < 0.001). Pain intensity (average pain) decreased from 12 months to 5 years postoperatively (estimated mean score 5 versus 4, difference of means -1 [95% CI -3 to 0]; p = 0.03). The results are presented as point estimates rounded up to whole numbers. The qualitative data analysis yielded three themes: persistent limitations after TKA, regained wellness over time, and complexity in physical challenges. Intermittent pain with certain movements resulted in limitations with some activities in everyday life and seemed to persist beyond 5 years. Multiple painful body sites and presence of comorbidities seemed to interfere with regained wellness over time. Conclusion: In this subgroup of patients experiencing postsurgical persistent pain 12 months after primary TKA, persistent postsurgical pain still limited certain activities for the participants, although pain seemed to be less influential in their everyday lives after 5 years to 7 years. Clinicians may use these findings to inform and guide patients with delayed improvements in pain into more realistic expectations for recovery, rehabilitation, and strategies for coping with pain and impaired function. However, it is imperative to rule out other reasons for pain in patients reporting pain 12 months and longer after surgery and to be attentive of possible changes in pain over time.publishedVersio

Posthumanist and new materialist perspectives as navigational tool in art education research: A diffractive analysis

An art project conducted with twelve Grade 10 learners at an art centre in Cape Town from April 2016 to June 2016 was analysed diffractively using perspectives of posthumanism and new materialism. This post-qualitative approach to research was an attempt to move away from research methods based on humanist thinking. Data consisted of the art project, learners' responses in terms of source book content and work produced, informal discussions, and videos and photographs taken during the work processes. Several specific agential cuts were performed on the data, some of which are presented here. The analysis of these entanglements of data provided rich content and interesting lines of flight, which led to thought-provoking questions about art education, sensory education, and the possibilities of applying posthumanist thought and methods in the South African art classroom