University of Oxford
  • Oxford, Oxfordshire, United Kingdom
Recent publications
The purpose of this paper is to investigate the topological properties of solution sets for a class of nonlinear evolution hemivariational inequalities. We firstly obtain the nonemptiness and the compactness of the solution set for hemivariational inequalities by applying the Kakutani–KyFan fixed point theorem, Gronwall’s inequality and the multivalued analysis. Then by using Hyman’s theorem, we show that the solution set for presented problem is an Rδ set. Finally, some applications to infinite dimensional control systems are given.
Objective Functional neuroimaging may provide a viable means of assessment and communication in patients with Guillain-Barré Syndrome (GBS) mimicking the complete locked-in state. Functional neuroimaging has been used to assess residual cognitive function and has allowed for binary communication with other behaviourally non-responsive patients, such as those diagnosed with unresponsive wakefulness syndrome. We evaluated the potential application of functional neuroimaging using a clinical-grade scanner to determine if individuals with severe GBS retained auditory function, command following, and communication. Methods Fourteen healthy participants and two GBS patients were asked to perform motor imagery and spatial navigation imagery tasks while being scanned using functional magnetic resonance imaging. The GBS patients were also asked to perform additional functional neuroimaging scans to attempt communication. Results The motor imagery and spatial navigation task elicited significant activation in appropriate regions of interest for both GBS patients, indicating intact command following. Both patients were able to use the imagery technique to communicate in some instances. Patient 1 was able to use one of four communication tasks to answer a question correctly. Patient 2 was able to use three of seven communication tasks. However, two questions were incorrectly answered while a third was non-verifiable. Conclusions GBS patients can respond using mental imagery and these responses can be detected using functional neuroimaging. Furthermore, these patients may also be able to use mental imagery to provide answers to ‘yes’ or ‘no’ questions in some instances. We argue that the most appropriate use of neuroimaging-based communication in these patients is to allow them to communicate wishes or preferences and assent to previously expressed decisions, rather than to facilitate decision-making.
Multi-modal distributions of some physics-based model parameters are often encountered in engineering due to different situations such as a change in some environmental conditions, and the presence of some types of damage and non-linearity. In statistical model updating, for locally identifiable parameters, it can be anticipated that multi-modal posterior distributions would be found. The full characterization of these multi-modal distributions is important as methodologies for structural condition monitoring in structures are frequently based in the comparison of the damaged and healthy models of the structure. The characterization of posterior multi-modal distributions using state-of-the-art sampling techniques would require a large number of simulations of expensive-to-run physics-based models. Therefore, when a limited number of simulations can be run, as it often occurs in engineering, the traditional sampling techniques would not be able to capture accurately the multi-modal distributions. This could potentially lead to large numerical errors when assessing the performance of an engineering structure under uncertainty. Therefore, an approach is proposed for drastically reducing the number of models runs while yielding accurate estimates of highly multi-modal posterior distributions. This approach introduces a cyclical annealing schedule into the Variational Bayes Monte Carlo (VBMC) method to improve the algorithm’s phase of exploration and the finding of high probability areas in the multi-modal posteriors throughout the different cycles. Three numerical and one experimental investigations are used to compare the proposed cyclical VBMC with the standard VBMC algorithm, the monotonic VBMC and the Transitional Ensemble Markov Chain Monte Carlo (TEMCMC). It is shown that the standard VBMC fails in capturing multi-modal posteriors as it is unable to escape already found regions of high posterior density. In the presence of highly multi-modal posteriors, the proposed cyclical VBMC algorithm outperforms all the other approaches in terms of accuracy of the resulting posterior, and number of model runs required.
It is a crucial decision-making issue to determine the batch size in production for manufacturing enterprises which implement multi-variety and small batch production. Regarding the current limitations, little research has been done on the relationship between batch sizing and the amount of information needed for production management. This paper first constructs the functional expression between the number of batches and the system entropy according to the measured property of entropy itself. Then, the two theorems on the relationship between the number of batches and the system entropy are theoretically put forward for the first time, i.e., an increase in the number of batches will reduce the system entropy, thus reducing the information required to manage production. Also, the two theorems are fully proved based on the proposed functions. In an empirical study, the variations between the system entropy functions and the number of batches are comparatively analyzed by designating two cases of 10 and 20 machining units. Consequently, the results of graphical representation once again illustrate the validity of the developed two theorems. The conclusions of this study not only provide a crucial information-theoretic basis for the feasible arrangement of batch size with an expert decision support system but contribute to guiding practical production for assembly line managers.
Electric vehicles (EVs) are playing an important role in power systems due to their significant mobility and flexibility features. Nowadays, the increasing penetration of renewable energy resources has been observed in modern power systems, which brings many benefits for improving climate change and accelerating the low-carbon transition. However, the intermittent and unstable nature of renewable energy sources introduces new challenges to both the planning and operation of power systems. To address these issues, vehicle-to-grid (V2G) technology has been gradually recognized as a valid solution to provide various ancillary service provisions for power systems. Many studies have developed model-based optimization methods for EV dispatch problems. Nevertheless, this type of method cannot effectively handle the highly dynamic and stochastic environment due to the complexity of power systems. Reinforcement learning (RL), a model-free and online learning method, can capture various uncertainties through numerous interactions with the environment and adapt to various state conditions in real-time. As a result, using advanced RL algorithms to solve various EV dispatch problems has attracted a surge of attention in recent years, leading to many outstanding research papers and important findings. This paper provides a comprehensive review of popular RL algorithms categorized by single-agent RL and multi-agent RL, and summarizes how these advanced algorithms can be applied to various EV dispatch problems, including grid-to-vehicle (G2V), vehicle-to-home (V2H), and V2G. Finally, key challenges and important future research directions are discussed, which involve five aspects: (a) data quality and availability; (b) environment setup; (c) safety and robustness; (d) training performance; and (e) real-world deployment.
This paper uses network analysis to study the structural properties of international environmental cooperation. We investigate four pertinent hypotheses. First, we quantify how the growing popularity of environmental treaties since the early 1970s has led to the emergence of an environmental collaboration network and document how collaboration is accelerating. Second, we show how over time the network has become denser and more cohesive, and distances between countries have become shorter, facilitating more effective policy coordination and knowledge diffusion. Third, we find that the network, while global, has a noticeable European imprint: initially, the United Kingdom and more recently France and Germany have been the most important players to broker environmental cooperation. Fourth, international environmental coordination started with fisheries and the sea but is now most intense on waste and hazardous substances. The network of air and atmosphere treaties has distinctive topological features, lacks the hierarchical organization of other networks, and is the network most significantly shaped by UN-sponsored treaties.
The freedom to choose between options is strongly linked to notions of free will. Accordingly, several studies have shown that individuals demonstrate a preference for choice, or the availability of multiple options, over and above utilitarian value. Yet we lack a decision-making framework that integrates preference for choice with traditional utility maximisation in free choice behaviour. Here we test the predictions of an inference-based model of decision-making in which an agent actively seeks states yielding entropy (availability of options) in addition to utility (economic reward). We designed a study in which participants freely navigated a virtual environment consisting of two consecutive choices leading to reward locations in separate rooms. Critically, the choice of one room always led to two final doors while, in the second room, only one door was permissible to choose. This design allowed us to separately determine the influence of utility and entropy on participants' choice behaviour and their self-evaluation of free will. We found that choice behaviour was better predicted by an inference-based model than by expected utility alone, and that both the availability of options and the value of the context positively influenced participants' perceived freedom of choice. Moreover, this consideration of options was apparent in the ongoing motion dynamics as individuals navigated the environment. In a second study, in which participants selected between rooms that gave access to three or four doors, we observed a similar pattern of results, with participants preferring the room that gave access to more options and feeling freer in it. These results suggest that free choice behaviour is well explained by an inference-based framework in which both utility and entropy are optimised and supports the idea that the feeling of having free will is tightly related to options availability.
Due to environmental interference and defects in measured objects, measurement signals are frequently affected by unpredictable noise and periodic defects. Moreover, there is a lack of effective methods for accurately distinguishing defect components from measurement signals. In this study, a distribution-based selective optimisation method (SOM) is proposed to mitigate the effects of noise and defect components. The SOM can be seen as a binary- or multiple-class signal classifier based on an error distribution, which can simultaneously eliminate periodic defect components of measurement signals and proceed with signal-fitting regression. The effectiveness, accuracy, and feasibility of the SOM are verified in theoretical and realworld measurement settings. Based on theoretical simulations under various parameter conditions, some criteria for selecting operation variables among a selection of parameter conditions are explained in detail. The proposed method is capable of separating defect components from measurement signals while also achieving a satisfactory fitting curve for the measurement signals. The proposed SOM has broad application prospects in signal processing and defect detection for mechanical measurements, electronic filtering, instrumentation, part maintenance, and other fields.
Everyday stressors are a normal part of adolescence, yet young people differ markedly in their responses. Emotional intelligence (EI), a set of emotion-related adaptive traits and skills, is thought to be an important individual difference that acts as a ‘stress buffer’ to safeguard adolescent well-being. EI correlates with reduced perceived life stress levels, but, to date, there is no attempt to understand how EI might underpin young people's responses to acute, situational stress. This paper explores how EI, measured as both an ability (AEI) and trait (TEI), regulates induced acute stress, using a novel, potent social stressor. Across two studies, we tested the extent to which EI moderated attention allocation to emotion (eye movements), psychological reactivity (mood), and physiological reactivity (heart rate) in older adolescents (study 1 n = 58; study 2 n = 60; age 16–18 years). Findings suggest that higher TEI (but not AEI) can ‘dampen’ the physiological stress response (study 1), facilitating protection against allostatic overload. However, being better at perceiving emotion (but not TEI) predicted attention towards happy stimuli when stressed (study 2). Preliminary findings suggest that, while TEI and AEI contribute differentially to stress regulation mechanisms, higher AEI may not necessarily be adaptive for young people facing social stressors.
[In Press - the final version is pending some proofing corrections]. Cognitive models of insomnia highlight internal and external cognitive-biases for sleep-related "threat" in maintaining the disorder. This systematic review of the sleep-related attentional and interpretive-bias literature includes meta-analytic calculations of each construct. Searches identified N=21 attentional-bias and N=8 interpretive-bias studies meeting the inclusion/exclusion criteria. Seventeen attentional-bias studies compared normal-sleepers and poor-sleepers/insomnia patients. Using a random effects model, meta-analytic data based on standardized mean differences of attentional-bias studies determined the weighted pooled effect size to be moderate at .60 (95%CI:0.26-0.93). Likewise, seven of eight interpretive-bias studies involved group comparisons. Meta-analytic data determined the weighted pooled effect size as moderate at .44 (95%CI:0.19-0.69). Considering these outcomes, disorder congruent cognitive-biases appear to be a key feature of insomnia. Despite statistical support, absence of longitudinal data limits causal inference concerning the relative role cognitive-biases in the development and maintenance of insomnia. Methodological factors pertaining to task design, sample and stimuli are discussed in relation to outcome variation. Finally, we discuss the next steps in advancing the understanding of sleep-related biases in insomnia.
Resilience Engineering principles are becoming increasingly popular in healthcare to improve patient safety. FRAM is the best-known Resilience Engineering method with several examples of its application in healthcare available. However, the guidance on how to apply FRAM leaves gaps, and this can be a potential barrier to its adoption and potentially lead to misuse and disappointing results. The article provides a self-reflective analysis of FRAM use cases to provide further methodological guidance for successful application of FRAM to improve patient safety. Five FRAM use cases in a range of healthcare settings are described in a structured way including critical reflection by the original authors of those studies. Individual reflections are synthesised through group discussion to identify lessons for the operationalisation of FRAM in healthcare. Four themes are developed: (1) core characteristics of a FRAM study, (2) flexibility regarding the underlying epistemological paradigm, (3) diversity with respect to the development of interventions, and (4) model complexity. FRAM is a systems analysis method that offers considerable flexibility to accommodate different epistemological positions, ranging from realism to phenomenology. We refer to these as computational FRAM and reflexive FRAM, respectively. Practitioners need to be clear about their analysis aims and their analysis position. Further guidance is needed to support practitioners to tell a convincing and meaningful “system story” through the lens of FRAM.
Zinc oxide tetrapods have remarkable functional and mechanical properties with potential applications in different fields including nanoelectronic and optoelectronic sensing, functional composites and coatings, as well as energy harvesting and storage. Based on the 3D shape of these microparticles, they can be assembled into highly porous (up to 98%) macroscopic ceramic framework structures that can be utilized as a versatile template for the fabrication of other multi-scaled foam-like materials. Here we investigated the three-dimensional structure of low density interconnected zinc oxide tetrapod networks by high resolution X-ray computed tomography. In situ observations during mechanical loading show inhomogeneous development of anelastic strain (damage) during compression, and homogeneous elastic recovery on unloading. Individual tetrapods are observed to deform by arm rotation to accommodate strain.
Background Melioidosis is a neglected tropical infection caused by the environmental saprophyte Burkholderia pseudomallei. Methods We conducted a prospective, observational study at nine hospitals in northeastern Thailand, a hyperendemic melioidosis zone, to define current characteristics of melioidosis patients and quantify outcomes over one year. Findings 2574 individuals hospitalised with culture-confirmed melioidosis were screened and 1352 patients were analysed. The median age was 55 years, 975 (72%) were male and 951 (70%) had diabetes. 561 (42%) patients presented with lung infection, 1042 (77%) were bacteraemic, 442 (33%) received vasopressors/inotropes and 547 (40%) received mechanical ventilation. 1307 (97%) received an intravenous antibiotic against B. pseudomallei. 335/1354 (25%) patients died within one month and 448/1331 (34%) of patients died within one year. Most patients had risk factors for melioidosis, but patients without identified risk factors did not have a reduced risk of death. Of patients discharged alive, most received oral trimethoprim-sulfamethoxazole, which was associated with decreased risk of post-discharge death; 235/970 (24%) were readmitted, and 874/1015 (86%) survived to one year. Recurrent infection was detected in 17/1018 patients (2%). Patients with risk factors other than diabetes had increased risk of death and increased risk of hospital readmission. Interpretation In northeastern Thailand patients with melioidosis experience high rates of bacteraemia, organ failure and death. Most patients discharged alive survive one year although all-cause readmission is common. Recurrent disease is rare. Strategies that emphasize prevention, rapid diagnosis and intensification of early clinical management are likely to have greatest impact in this and other resource-restricted regions. Funding US NIH/NIAID U01AI115520.
We seek to establish qualitative convergence results to a general class of evolution PDEs described by gradient flows in optimal transportation distances. These qualitative convergence results come from dynamical systems under the general name of LaSalle Invariance Principle. By combining some of the basic notions of gradient flow theory and dynamical systems, we are able to reproduce this invariance principle in the setting of evolution PDEs under general assumptions. We apply this abstract theory to a non-exhaustive list of examples that recover, simplify, and even extend the results in their respective literatures.
The EU's Forest Law Enforcement, Governance and Trade Action Plan (FLEGT) adopted in 2003 includes bilateral trade agreements known as Voluntary Partnership Agreements (VPAs) signed between the EU and timber-supplying countries. The EU has invested more than 1.5 billion euros in VPAs; however, only one of the seven concerned countries has managed to complete all the necessary requirements to expire FLEGT licences. Since there is no research that comprehensively integrates the scientific evidence regarding the effects of this policy, this study systematically reviews all empirical scientific studies on the effects of VPAs. We found that almost all relevant studies are case reports that use qualitative data and focus on only one country at a time, mainly Ghana, Cameroon, or Indonesia. The evidence suggests that while VPAs have contributed to the establishment of governance structures, tools, and procedures they have not been able to solve social problems (i.e., inequality and injustice) and have potentially harmed the economies of EU timber suppliers. Evidence on the effects of VPAs on illegal logging and trade and the environment remains limited. Thus, future research should focus on more countries; use a greater range of methods, including comparative experimental designs; explore possible intended effects on under-researched categories; and systematically investigate unintended effects on other categories within and outside the forestry sector.
Wildlife-friendly food labels are used to reduce information asymmetry and thus enhance agrobiodiversity conservation via marketing mechanisms. The labels make different claims depending on the certification requirements and conservation targets. However, little is known about consumer preferences for the different claims on the labels. Here, we evaluated consumer preferences for wildlife-friendly labels, with a focus on input- and outcome-based claims, by applying a choice experiment. Our results showed that consumers preferred fish labels with outcome claims to those with input claims; in contrast, consumer utility was not increased by outcome claims but by input claims in bird labels. The differences in preferences for certification requirements and for flagship species highlight the importance of strategic certification and labelling in encouraging people to conserve biodiversity. Our empirical evidence provides insights to balance biodiversity conservation with food security through conservation marketing.
Invasive fungal infection serves as a great threat to human health. Discrimination between fungal and bacterial infections at the earliest stage is vital for effective clinic practice; however, traditional culture-dependent microscopic diagnosis of fungal infection usually requires several days, meanwhile, culture-independent immunological and molecular methods are limited by the detectable type of pathogens and the issues with high false-positive rates. In this study, we proposed a novel culture-independent phenotyping method based on single-cell Raman spectroscopy for the rapid discrimination between fungal and bacterial infections. Three Raman biomarkers, including cytochrome c, peptidoglycan, and nucleic acid, were identified through hierarchical clustering analysis of Raman spectra across 12 types of most common yeast and bacterial pathogens. Compared to those of bacterial pathogens, the single cells of yeast pathogens demonstrated significantly stronger Raman peaks for cytochrome c, but weaker signals for peptidoglycan and nucleic acid. A two-step protocol combining the three biomarkers was established and able to differentiate fungal infections from bacterial infections with an overall accuracy of 94.9%. Our approach was also used to detect ten raw urinary tract infection samples. Successful identification of fungi was achieved within half an hour after sample obtainment. We further demonstrated the accurate fungal species taxonomy achieved with Raman-assisted cell ejection. Our findings demonstrate that Raman-based fungal identification is a novel, facile, reliable, and with a breadth of coverage approach, that has a great potential to be adopted in routine clinical practice to reduce the turn-around time of invasive fungal disease (IFD) diagnostics.
J. M. Coetzee’s ‘Jesus’ trilogy extends and intensifies his long-term interest in engaging with a wide range of texts, themes, and assumptions that help constitute the history of Western European philosophy. In this commentary, Stephen Mulhall extends his own earlier work on Coetzee’s previous stagings of the ancient quarrel between philosophy and literature by identifying and following out various ways in which the ‘Jesus’ trilogy activates and interrogates themes drawn from Wittgenstein’s later philosophy. These themes include rival conceptions of counting and reading, the relation between concepts and wider forms of life, and the intertwined fate of philosophy, literature, and religion in a resolutely secular world. In these ways, Wittgenstein’s and so Coetzee’s visions of the world disclose their uncanny intimacy with issues and values central to the critique of modernity elaborated in the work of Nietzsche, Heidegger, and Sartre.
Flexible behavior requires guidance not only by sensations that are available immediately but also by relevant mental contents carried forward through working memory. Therefore, selective-attention functions that modulate the contents of working memory to guide behavior (inside-out) are just as important as those operating on sensory signals to generate internal contents (outside-in). We review the burgeoning literature on selective attention in the inside-out direction and underscore its functional, flexible, and future-focused nature. We discuss in turn the purpose (why), targets (what), sources (when), and mechanisms (how) of selective attention inside working memory, using visual working memory as a model. We show how the study of internal selective attention brings new insights concerning the core cognitive processes of attention and working memory and how considering selective attention and working memory together paves the way for a rich and integrated understanding of how mind serves behavior. Expected final online publication date for the Annual Review of Psychology, Volume 74 is January 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
Shared picture-book reading is well-recognized as beneficial for children's early language development, especially where “dialogic book-sharing” techniques are used. Possible benefits of dialogic book-sharing to other aspects of child development have been little investigated, and it has not been widely studied in European populations. We conducted a randomized trial of dialogic book-sharing in Children's Centers in the UK, with parents of 2- to- 4-year-old children, hypothesizing that it would benefit parenting and a range of child developmental outcomes. Intervention group parents (n = 110) received 7, weekly, group training sessions, and control parents (n = 108) the usual center input. Parenting and a range of child outcomes (language, attention, executive function, social development, and emotional-behavior difficulties) were assessed on 3 occasions: before, after, and 4–6 month following intervention. For all study outcomes we compared controls with each of the Intention-to-Treat population and the per-protocol population (participants attending the requisite number of sessions); and, for primary child outcomes only, the population of parents who engaged well with the intervention. There were substantial benefits of dialogic book-sharing training to parental behavior during book-sharing, especially for sensitivity and cognitive scaffolding. For all 3 sets of comparisons there were small-medium effects of on child expressive language, and, for the per protocol and engaged populations, similar sized effects on child receptive language and attention. There was no evidence of benefit of dialogic book-sharing for the other areas of child development; we suggest that specific intervention components need to be added to standard dialogic book-sharing to effect change in these areas.
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Maru Mormina
  • Ethox Centre
Simon Proud
  • Department of Physics
Sebastian Engelstaedter
  • School of Geography and the Environment
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University of Oxford, University Offices, Wellington Square, OX1 2JD, Oxford, Oxfordshire, United Kingdom
Head of institution
The Rt Hon the Lord Patten of Barnes, CH
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http://www.ox.ac.uk
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