Showing papers by "City University London published in 2022"

Lateral–torsional buckling resistance prediction model for steel cellular beams generated by Artificial Neural Networks (ANN)

Abstract: The present paper aims to develop an Artificial Neural Network (ANN) formula to predict the lateral-torsional buckling (LTB) resistance of slender steel cellular beams. A finite element model is developed and validated through experimental tests followed by a parametric study. 768 models are employed to train the ANN formula. The results are compared with the analytical models as well as the equation predicted by ANN. It was concluded that the ANN model with seven neurons can accurately predict the LTB resistance of cellular beams as well as the LTB combined with web-post buckling or web distortional buckling modes. Hence, the ANN-based formula can be adopted as design tool.

China's catching-up in artificial intelligence seen as a co-evolution of corporate and national innovation systems

Abstract: Inspired by Christopher Freeman's work on how radical technical change opens up for shifts in world leadership and on the role of innovation systems in this process, this paper explores China's emergence as a lead country in artificial intelligence as reflecting a co-evolution of Corporate and National Innovation Systems. Taking Freeman's (1987) work on Japan as our lead, we focus on the domestic interaction within and on the openness of China's national innovation system. To follow up on his prediction of the increasing importance of big companies as network leaders, we introduce the concept “corporate innovation system” with special attention to two Chinese tech giants: Alibaba and Tencent.

The challenges of viewpoint-taking when learning a sign language: Data from the ‘frog story’ in British Sign Language:

Abstract: Little is known about how hearing adults learn sign languages. Our objective in this study was to investigate how learners of British Sign Language (BSL) produce narratives, and we focused in particular on viewpoint-taking. Twenty-three intermediate-level learners of BSL and 10 deaf native/early signers produced a narrative in BSL using the wordless picture book Frog, where are you? (Mayer, 1969). We selected specific episodes from part of the book that provided rich opportunities for shifting between different characters and taking on different viewpoints. We coded for details of story content, the frequency with which different viewpoints were used and how long those viewpoints were used for, and the numbers of articulators that were used simultaneously. We found that even though learners’ and deaf signers’ narratives did not differ in overall duration, learners’ narratives had less content. Learners used character viewpoint less frequently than deaf signers. Although learners spent just as long as deaf signers in character viewpoint, they spent longer than deaf signers in observer viewpoint. Together, these findings suggest that character viewpoint was harder than observer viewpoint for learners. Furthermore, learners were less skilled than deaf signers in using multiple articulators simultaneously. We conclude that challenges for learners of sign include taking character viewpoint when narrating a story and encoding information across multiple articulators simultaneously.

New Ways of Supporting Child Abuse and Sexual Violence Survivors: a social justice call for an innovative commissioning pathway

Abstract: This report outlines the needs of child sexual abuse and sexual violence survivors in relation to the current conceptualisation and provision for 'personality disorder'. It has been collaboratively written by a socially diverse collective of survivors of child sexual abuse (CSA) and sexual violence (SV). Many of us have been forced to accept a personality disorder diagnosis and we wanted to come together to share our experiences and to propose less harmful approaches to future service provision for our population.We are asking for trauma-specific pathways, separate from personality disorder (or any re-named personality disorder) services. As a group, we have been profoundly harmed by both the application of the personality disorder construct, i.e. the ways in which services treat us as a result of the construct, and also by the treatment pathways which are harmful for our population.As a group, we suffer from high levels of dissociation and trauma specifically related to our CSA/SV experiences. These have long been neglected because the only current provision for people like us sits within the personality disorder (PD) field.In addition to this, we are bringing attention to the harm caused by current behaviourist approaches and systems that criminalise our distress rather than provide alternative support.We explain how LGBTQ+ survivors are being doubly failed by services in that they are having their sexuality and gender identity understood and pathologised as a symptom of 'PD' leading to increased shame and self-hatred.Ultimately, this report highlights how we have been failed and re-traumatised by state systems that are supposed to protect and support us when we were at our most vulnerable. It also shows how 'PD' has been used to silence and reframe our experiences. We finish by making recommendations for new trauma-specific pathways and services that are completely removed from a personality disorder frame of understanding.

Massive gauge particles versus Goldstone bosons in non-Hermitian non-Abelian gauge theory

Abstract: Abstract We investigate the Englert–Brout–Higgs–Guralnik–Hagen–Kibble mechanism for non-Hermitian field theories with local non-Abelian gauge symmetry in different regions of their parameter spaces. We demonstrate that the two aspects of the mechanism, that is giving mass to gauge vector bosons and at the same time preventing the existence of massless Goldstone bosons, remain to be synchronized in all regimes characterized by a modified CPT symmetry. In the domain of parameter space where the “would be Goldstone bosons” can be identified the gauge vector bosons become massive and the Goldstone bosons cease to exist. The mechanism is also in tact at the standard exceptional points. However, at the zero exceptional points, that is when the eigenvalues of the mass squared matrix vanish irrespective of the symmetry breaking, the mechanism breaks down as the Goldstone bosons cannot be identified and the gauge vector bosons remain massless. This breakdown coincides with the vanishing of the CPT inner product of symmetry breaking vacua defined on the eigenvector space of mass squared matrix. We verify this behaviour for a theory with SU(2) symmetry in which the complex scalar fields are taken in the fundamental as well as in the adjoint representation.

Symmetry resolved entanglement of excited states in quantum field theory. Part II. Numerics, interacting theories and higher dimensions

Abstract: In a recent paper we studied the entanglement content of zero-density excited states in complex free quantum field theories, focusing on the symmetry resolved entanglement entropy (SREE). By zero-density states we mean states consisting of a fixed, finite number of excitations above the ground state in an infinite-volume system. The SREE is defined for theories that possess an internal symmetry and provides a measure of the contribution to the total entanglement of each symmetry sector. In our work, we showed that the ratio of Fourier-transforms of the SREEs (i.e. the ratio of charged moments) takes a very simple and universal form for these states, which depends only on the number, statistics and symmetry charge of the excitations as well as the relative size of the entanglement region with respect to the whole system's size. In this paper we provide numerical evidence for our formulae by computing functions of the charged moments in two free lattice theories: a 1D Fermi gas and a complex harmonic chain. We also extend our results in two directions: by showing that they apply also to excited states of interacting theories (i.e. magnon states) and by developing a higher dimensional generalisation of the branch point twist field picture, leading to results in (interacting) higher-dimensional models.

What are the strategies for implementing primary care models in maternity? A systematic review on midwifery units

Abstract: Midwifery Units (MUs) are associated with optimal perinatal outcomes, improved service users' and professionals' satisfaction as well as being the most cost-effective option. However, they still do not represent the mainstream option of maternity care in many countries. Understanding effective strategies to integrate this model of care into maternity services could support and inform the MU implementation process that many countries and regions still need to approach.A systematic search and screening of qualitative and quantitative research about implementation of new MUs was conducted (Prospero protocol reference: CRD42019141443) using PRISMA guidelines. Included articles were appraised using the CASP checklist. A meta-synthesis approach to analysis was used. No exclusion criteria for time or context were applied to ensure inclusion of different implementation attempts even under different historical and social circumstances. A sensitivity analysis was conducted to reflect the major contribution of higher quality studies.From 1037 initial citations, twelve studies were identified for inclusion in this review after a screening process. The synthesis highlighted two broad categories: implementation readiness and strategies used. The first included aspects related to cultural, organisational and professional levels of the local context whilst the latter synthesised the main actions and key points identified in the included studies when implementing MUs. A logic model was created to synthesise and visually present the findings.The studies selected were from a range of settings and time periods and used varying strategies. Nonetheless, consistencies were found across different implementation processes. These findings can be used in the systematic scaling up of MUs and can help in addressing barriers at system, service and individual levels. All three levels need to be addressed when implementing this model of care.

Multi-modal open world user identification

Abstract: User identification is an essential step in creating a personalised long-term interaction with robots. This requires learning the users continuously and incrementally, possibly starting from a stat...

The origin of photoplethysmography

Abstract: This chapter covers comprehensively all available theories and hypotheses relating to the origin of the photoplethysmogram (PPG). The basic principles of PPG, based on the modified Beer–Lambert law, and its relation to blood volume variations, mechanical movements of the tissue-components, and the orientation of the red blood cells are presented. Furthermore, the chapter covers in detail the principles of light–tissue interactions in PPG and presents UpToDate research utilizing advanced Monte Carlo simulations relating to light–tissue interaction variables (i.e., optical pathlength, light penetration, absorbance, etc.) for both reflectance and transmittance PPG. This most recent research enables further understanding and knowledge in the contribution of different tissue layers and sublayers in the formation of the PPG waveform and hence aids further with the “quest” of understanding and explaining the origin of the PPG.

Symmetry resolved entanglement of excited states in quantum field theory. Part I. Free theories, twist fields and qubits

Abstract: A bstract The excess entanglement resulting from exciting a finite number of quasiparticles above the ground state of a free integrable quantum field theory has been investigated quite extensively in the literature. It has been found that it takes a very simple form, depending only on the number of excitations and their statistics. There is now mounting evidence that such formulae also apply to interacting and even higher-dimensional quantum theories. In this paper we study the entanglement content of such zero-density excited states focusing on the symmetry resolved entanglement, that is on 1+1D quantum field theories that possess an internal symmetry. The ratio of charged moments between the excited and grounds states, from which the symmetry resolved entanglement entropy can be obtained, takes a very simple and universal form, which in addition to the number and statistics of the excitations, now depends also on the symmetry charge. Using form factor techniques, we obtain both the ratio of moments and the symmetry resolved entanglement entropies in complex free theories which possess U(1) symmetry. The same formulae are found for simple qubit states.

Gelatin-based cellular solids: Fabrication, structure and properties

Abstract: Although most cellular polymers are made from thermoplastics using different foaming technologies, gelatin and many other natural polymers can form hydrogels and convert them to cellular solids using various techniques, many of which differ from traditional plastic foaming, and so does their resulting structures. Cellular solids from natural hydrogels are porous materials that often exhibit a combination of desirable properties, including high specific surface area, biochemical activity, as well as thermal and acoustic insulation properties. Among natural hydrogels, gelatin-based porous materials are widely explored due to their availability, biocompatibility, biodegradability and relatively low cost. In addition, gelatin-based cellular solids have outstanding properties and are currently subject to increasing scientific research due to their potential in many applications, such as biocompatible cellular materials or biofoams to facilitate waste treatment. This article aims at providing a comprehensive review of gelatin cellular solids processing and their processing-properties-structure relationship. The fabrication techniques covered include aerogels production, mechanical foaming, blowing agents use, 3D printing, electrospinning and particle leaching methods. It is hoped that the assessment of their characteristics provides compiled information and guidance for selecting techniques and optimization of processing conditions to control material structure and properties to meet the needs of the finished products.

Bank Sectoral Concentration and Risk: Evidence from a Worldwide Sample of Banks

Abstract: We propose a novel, stock-return based, technique to measure three aspects of banks' sectoral concentration that feature prominently in episodes of bank risk: specialization (capturing high exposures), differentiation (capturing deviation from peer banks), and financial sector exposure (capturing direct connectedness) and show external validity for these measures. We find that both individual and systemic bank risk decrease with specialization. Differentiation is particularly and positively related to individual bank risk, whereas direct connectedness of banks is particularly and positively related to systemic bank risk. These findings inform the theoretical and policy debate on the relationship between sectoral concentration and banks' stability.

Photoplethysmography in oxygenation and blood volume measurements

Abstract: Since its discovery, photoplethysmography (PPG) has been almost exclusively associated with pulse oximetry, a noninvasive and continuous technique measuring oxygen saturation levels in blood. This chapter will describe how PPG signals are utilized in pulse oximetry to measure blood oxygen saturation (SpO2). The chapter will also provide a snapshot on the capabilities and potentials of PPG in the clinical monitoring of oxygenation and perfusion. The first part of the chapter covers the principles, latest advancements, and applications of pulse oximetry, whereas the second part covers the application of PPG in measuring blood volume changes and perfusion among other parameters.

Tradition as a resource: Robust and radical interpretations of operatic tradition in the Italian opera industry, 1989–2011

Abstract: Research Summary A major challenge that organizations face in cultural industries in dealing with cherished traditions is how to best mediate between adherence to tradition and pursuit of innovation, how to accommodate renewal without stifling tradition. We address this conundrum by integrating ideas from consumer-oriented psychological research on evaluative judgments and design-oriented innovation research. We show that firms can improve customers' perceptions of value by offering robust interpretations of traditional products that preserve the most familiar aspects of a tradition while departing from it on more peripheral features; however, when the interpretation is more radical—that is, it alters core elements of the tradition—customers are more likely to experience incongruity with their schemas, resulting in a negative perception of value. We also postulate that different audience segments will respond differently to the (re)interpreted tradition because individuals vary in the use of generic schemas depending on their level of expertise, and different schemas may accommodate smaller or greater changes in a configuration of attributes. We develop and test these hypotheses in the context of the Italian opera industry over the period 1989 to 2011. The results offer insights into how firms can maintain a sense of continuity with a revered tradition while ensuring its renewal over time. Managerial Summary Reinterpreting revered traditions is a way to exploit timeless resources encased in history by recasting them in new ways. This article reveals how firms can balance tradition and innovation through the design choices they make, thus expanding the range of strategic tools that can be leveraged to influence customers' perceptions of value. In doing so, it helps managers address the need for renewal, while at the same time remaining sensitive to the heterogeneity of different customer segments, by manipulating the core and/or peripheral features of a product (here the opera). Although firms in cultural industries often face the challenge of resolving the tension between the preservation of tradition and risky innovation, many other firms across different industries also confront the issue of developing new products while building intimate links with their traditions.