Now showing items 1-20 of 9639

    • Experimental investigations and finite element analyses of interface heat partition in a friction brake system. New modelling paradigm for describing friction brake systems to support studies of interface temperature, contact pressure, heat flux distribution and heat partition ratio by experiment and FE simulation

      Qi, Hong Sheng; Wood, Alastair S.; Qui, Le (University of BradfordFaculty of Engineering and Informatics, 2018)
      Operating temperature range is one of the primary design considerations for developing effective disc brake system performance. Very high braking temperatures can introduce effects detrimental to performance such as brake fade, premature wear, brake fluid vaporization, bearing failure, thermal cracks, and thermally-excited vibration [2]. This project is concerned with investigating deficiencies and proposing improvements in brake system Finite Element (FE) models in order to provide high quality descriptions of thermal behaviour during braking events. The work focuses on brake disc/pad models and the degree of rotational freedom allowed for the pad. Conventional models [10] allow no motion/or free motion of the pad. The present work investigates the effect on disc/pad interface temperature and pressure distributions of limited relaxations of this rotational restriction. Models are proposed, developed and validated that facilitate different rotational degrees of freedom (DoF) of the pad. An important influencing factor in friction brake performance is the development of an interface tribo-layer (ITL). It is reasonable to assume that allowing limited rotational motion of the pad will impact the development of the ITL (e.g. due to different friction force distributions) and hence influence temperature. Here the ITL is modelled in the numerical simulations as a function of its thickness distribution and thermal conductivity. Different levels of ITL thermal conductivity are defined in this work and results show that conductivity significantly a1qwffects interface temperature and heat partition ratio. The work is based around a set of test-rig experiments and FE model developments and simulations. For the experimental work, a small-scale test rig is used to investigate the friction induced bending moment effect on the pad/disc temperature. Significant non-uniform wear is observed across the friction surface of the pad, and reasons for the different wear rates are proposed and analyzed together with their effect on surface temperature. Following on from experiment a suite of models is developed in order to evidence the importance of limited pad motion and ITL behaviours. A 2D coupled temperature-displacement FE model is used to quantify the influence of different pad rotational degrees of freedom and so provide evidence for proposing realistic pad boundary settings for 3D models. Normal and high interface thermal conductance is used in 2D models and results show that the ITL thermal conductivity is an important factor influencing the maximum temperature of contact surfaces and therefore brake performance. The interface heat partition ratio is calculated by using the heat flux results and it is confirmed that this value is neither constant nor uniform across the interface surfaces. Key conclusions from the work are (i) that ITL thermal conductivity is an important factor influencing the interface temperature/heat flux distribution and their maximum values, (ii) that allowed motion of the pad significantly affects the interface pressure distribution and subsequently the temperature distribution, (iii) that the transient heat partition in friction braking is clearly quite different to the conventional friction-pair steady heat partition (the heat partition ratio is not uniformly distributed along the interface) and (iv) that the thickness of the ITL increases through braking events, reducing the heat transfer to the disc, and so providing a possible explanation for increasing pad temperature observed over the life time of a brake pad.
    • Prostanoid-mediated Inhibition of IL-6 Trans-Signalling in Pulmonary Arterial Hypertension: a Role for Suppressor of Cytokine Signalling 3?

      Palmer, Timothy M.; Williams, Jamie J.L.; Nasim, Md. Talat; Elies, Jacobo; Durham, Gillian A. (University of BradfordSchool of Pharmacy and Medical Sciences Faculty of Life Sciences, 2019)
      Pulmonary arterial hypertension (PAH) is a rare, devastating disease with no cure. Current treatment consists of a cocktail of vasodilators which relieve symptoms of PAH but do not treat the cause. Thus, there is a need for novel drugs that target the underlying pathological causes of PAH. PAH is a multi-factorial, but one key contributor is the pro-inflammatory cytokine IL-6 which stimulates pro-inflammatory and pro-angiogenic signalling mediated by the JAK/STAT pathway. One way in which IL-6 signalling via JAK/STAT is inhibited is via SOCS3 in a type of negative feedback loop whereby IL-6 induces transcription of SOCS3, which then attenuates further JAK/STAT signalling. SOCS3 can also be induced by cAMP. This is interesting as prostanoids, a type of drug used in the treatment of PAH due to its vasodilator effects and the only type to show any efficacy improving the life expectancy of PAH patients, acts by mobilising cAMP. Thus, prostanoid stimulation of cAMP could potentially limit IL-6 signalling via the induction of SOCS3. This is a novel mechanism of prostanoids which has not previously been considered. This study investigated the capability of prostanoids to limit the pro-inflammatory/pro-angiogenic effects of IL-6 that enable PAH to develop. Initial experiments confirmed that vascular endothelial cells responded to prostanoids which increased SOCS3 and limited IL-6 signalling activity. Further experiments utilising SOCS3 KO endothelial cell models demonstrated prostanoid inhibition of IL-6 signalling was due in part to SOCS3. In conclusion, this project has confirmed that prostanoids do limit the pro-inflammatory effects induced by IL-6 and that this is in part due to SOCS3. Although the exact mechanism is yet to be discovered, it will be beneficial in the treatment of PAH as it provides currently unexploited drug targets which can be considered for future PAH therapies.
    • Managing risk; how doctors, nurses and pharmacists optimise the use of medicines in acute hospitals in Northern Ireland: a grounded theory study.

      Lucas, Beverley J.; Blenkinsopp, Alison; Friel, Anne B.M. (University of BradfordSchool of Pharmacy and Medical Sciences, Faculty of Life Sciences, 2018)
      Medicines optimisation requires healthcare professionals to work collaboratively to meet the medication needs of patients. A grounded theory was produced which explains how doctors, nurses and pharmacists work to optimise the use of medicines in acute hospital settings in Northern Ireland. Seventeen semi-structured, one-to-one interviews were conducted with doctors, nurses and pharmacists. Concurrent data collection and analysis was carried out using coding, particular to grounded theory, adopting a constant comparative approach, writing memos and using theoretical sampling as described by Strauss and Corbin (1998). The core category was managing risk. Participants had an implicit understanding of the need to continually manage risk when working with the complex and the routine. They used personal and systemic checks and balances which could be viewed either as duplication of effort or indicative of a culture of safety. Multi-professional interdependencies and support for new, professional, non-medical roles were highlighted. Working together was a further strategy to ensuring each patient gets the right medicine. Establishing an agreed framework for working with medicines at ward level could support the safer use of medicines. It is anticipated that this theory will contribute to the design of systems involved in medicines use in acute hospitals in Northern Ireland.
    • Development of digital imaging technologies for the segmentation of solar features and the extraction of filling factors from SODISM images

      Qahwaji, Rami S.R.; Ipson, Stanley S.; Alasta, Amro F.A. (University of BradfordSchool of Electrical Engineering and computer. Science Faculty of Engineering and Informatics, 2018)
      Solar images are one of the most important sources of available information on the current state and behaviour of the sun, and the PICARD satellite is one of several ground and space-based observatories dedicated to the collection of that data. The PICARD satellite hosts the Solar Diameter Imager and Surface Mapper (SODISM), a telescope aimed at continuously monitoring the Sun. It has generated a huge cache of images and other data that can be analysed and interpreted to improve the monitoring of features, such as sunspots and the prediction and diagnosis of solar activity. In proportion to the available raw material, the little-published analysis of SODISM data has provided the impetus for this study, specifically a novel method of contributing to the development of a system to enhance, detect and segment sunspots using new hybrid methods. This research aims to yield an improved understanding of SODISM data by providing novel methods to tabulate a sunspot and filling factor (FF) catalogue, which will be useful for future forecasting activities. The developed technologies and the findings achieved in this research will work as a corner stone to enhance the accuracy of sunspot segmentation; create efficient filling factor catalogue systems, and enhance our understanding of SODISM image enhancement. The results achieved can be summarised as follows: i) Novel enhancement method for SODISM images. ii) New efficient methods to segment dark regions and detect sunspots. iii) Novel catalogue for filling factor including the number, size and sunspot location. v) Novel statistical method to summarise FFs catalogue. Image processing and partitioning techniques are used in this work; these methods have been applied to remove noise and detect sunspots and will provide more information such as sunspot numbers, size and filling factor. The performance of the model is compared to the fillers extracted from other satellites, such as SOHO. Also, the results were compared with the NOAA catalogue and achieved a precision of 98%. Performance measurement is also introduced and applied to verify results and evaluate proposal methods. Algorithms, implementation, results and future work have been explained in this thesis.
    • Design and Linearization of Energy Efficiency Power Amplifier in Nonlinear OFDM Transmitter for LTE-5G Applications. Simulation and measurements of energy efficiency power amplifier in the presence of nonlinear OFDM transmitter system and digital predistortion based on Hammerstein-Wiener method

      Abd-Alhameed, Raed A.; Mohammed, Buhari A. (University of BradfordFaculty of Engineering and Informatics, 2019)
      This research work has made an effort to understand a novel line of radio frequency power amplifiers (RFPAs) that address initiatives for efficiency enhancement and linearity compensation to harmonize the fifth generation (5G) campaign. The objective is to enhance the performance of an orthogonal frequency division multiplexing-long term evolution (OFDM-LTE) transmitter by reducing the nonlinear distortion of the RFPA. The first part of this work explores the design and implementation of 15.5 W class AB RF power amplifier, adopting a balanced technique to stimulate efficiency enhancement and redeeming exhibition of excessive power in the transmitter. Consequently, this work goes beyond improving efficiency over a linear RF power amplifier design; in which a comprehensive investigation on the fundamental and harmonic components of class F RF power amplifier using a load-pull approach to realise an optimum load impedance and the matching network is presented. The frequency bandwidth for both amplifiers was allocated to operate in the 2.620-2.690 GHz of mobile LTE applications. The second part explores the development of the behavioural model for the class AB power amplifier. A particular novel, Hammerstein-Wiener based model is proposed to describe the dynamic nonlinear behaviour of the power amplifier. The RF power amplifier nonlinear distortion is approximated using a new linear parameter approximation approach. The first and second-order Hammerstein-Wiener using the Normalised Least Mean Square Error (NLMSE) algorithm is used with the aim of easing the complexity of filtering process during linear memory cancellation. Moreover, an enhanced adaptive Wiener model is proposed to explore the nonlinear memory effect in the system. The proposed approach is able to balance between convergence speed and high-level accuracy when compared with behavioural modelling algorithms that are more complex in computation. Finally, the adaptive predistorter technique is implemented and verified in the OFDM transceiver test-bed. The results were compared against the computed one from MATLAB simulation for OFDM and 5G modulation transmitters. The results have confirmed the reliability of the model and the effectiveness of the proposed predistorter.
    • Sex and age differences in attitudes and intention to adopt personalised nutrition in a UK sample

      Stewart-Knox, Barbara; Poinhos, R.; Fischer, A.R.H.; Chaudhrey, M.; Rankin, A. (2022)
      There has been an increase in development of technologies that can deliver personalised dietary advice. Devising healthy, sustainable dietary plans will mean taking consideration of extrinsic factors such as individual social circumstances. The aim of this study was to identify societal groups more or less receptive to and likely to engage with digitally delivered personalised nutrition initiatives. Sample and Methods: Volunteers were recruited via a social research agency from within the UK. The resultant sample (N=1061) was 49% female, aged 18-65 years. Results: MANOVA (Tukey HSD applied) indicated that females and younger people (aged 18-29 years) had more favourable attitudes and were more likely to intend to adopt personalised nutrition. There were no differences in attitude toward or intention to adopt personalised nutrition between different education levels, income brackets or occupational groups. Conclusion: These results imply that females and younger people may be most likely to adopt personalised nutrition in the future. Initiatives to promote personalised nutrition should target males and older people.
    • Mattering Mediates Between Fairness and Well-being

      Scarpa, M.P.; Di Martino, Salvatore; Prilleltensky, I. (2021-11-03)
      Research has suggested a fundamental connection between fairness and well-being at the individual, relational, and societal levels. Mattering is a multidimensional construct consisting of feeling valued by, and adding value to, self and others. Prior studies have attempted to connect mattering to both fairness and a variety of well-being outcomes. Based on these findings, we hypothesize that mattering acts as a mediator between fairness and well-being. This hypothesis was tested through Covariance-Based Structural Equation Modeling (CB-SEM) using multidimensional measures of fairness, mattering, and well-being. Results from a Latent Path Analysis conducted on a representative sample of 1,051U.S. adults provide support to our hypothesis by revealing a strong direct predictive effect of mattering onto well-being and a strong indirect effect of fairness onto well-being through mattering. Results also show that mattering is likely to fully mediate the relationship between fairness and multiple domains of well-being, except in one case, namely, economic well-being. These findings illustrate the value of a focus on mattering to understand the relationship between fairness and well-being and to provide future directions for theory, research, and practice. Theoretical implications for the experience of citizenship and participation, along with cross-cultural considerations, are also discussed.
    • Deep Quantile Regression for Unsupervised Anomaly Detection in Time-Series

      Tambuwal, Ahmad I.; Neague, Daniel (Springer, 2021-09-30)
      Time-series anomaly detection receives increasing research interest given the growing number of data-rich application domains. Recent additions to anomaly detection methods in research literature include deep neural networks (DNNs: e.g., RNN, CNN, and Autoencoder). The nature and performance of these algorithms in sequence analysis enable them to learn hierarchical discriminative features and time-series temporal nature. However, their performance is affected by usually assuming a Gaussian distribution on the prediction error, which is either ranked, or threshold to label data instances as anomalous or not. An exact parametric distribution is often not directly relevant in many applications though. This will potentially produce faulty decisions from false anomaly predictions due to high variations in data interpretation. The expectations are to produce outputs characterized by a level of confidence. Thus, implementations need the Prediction Interval (PI) that quantify the level of uncertainty associated with the DNN point forecasts, which helps in making better-informed decision and mitigates against false anomaly alerts. An effort has been made in reducing false anomaly alerts through the use of quantile regression for identification of anomalies, but it is limited to the use of quantile interval to identify uncertainties in the data. In this paper, an improve time-series anomaly detection method called deep quantile regression anomaly detection (DQR-AD) is proposed. The proposed method go further to used quantile interval (QI) as anomaly score and compare it with threshold to identify anomalous points in time-series data. The tests run of the proposed method on publicly available anomaly benchmark datasets demonstrate its effective performance over other methods that assumed Gaussian distribution on the prediction or reconstruction cost for detection of anomalies. This shows that our method is potentially less sensitive to data distribution than existing approaches.
    • Blockchain adoption in the maritime supply chain: Examining barriers and salient stakeholders in containerized international trade

      Balci, G.; Surucu-Balci, Ebru (2021-12)
      This study aimed to investigate the relationships between blockchain adoption barriers and identified the salient stakeholders for blockchain adoption in containerized international trade. The interpretative structural modelling and Cross-Impact Matrix Multiplication Applied to Classification analyses indicated that the most impactful among the eight barriers are lack of support from influential stakeholders, lack of understanding regarding blockchain, and lack of government regulations. The stakeholder mapping analysis demonstrated that the high salient stakeholders among 11 legitimate stakeholders are container lines, ports, beneficial cargo owners, freight forwarders/third party logistics, and customs authorities. The study is original and contributes to theory and practice as it uncovers both impactful barriers and critical stakeholders by adopting a stakeholder theory perspective and offers significant implications to practice, policy, and theory by combining these two analyses.
    • Living with dementia under COVID-19 restrictions Coping and support needs among people with dementia and carers from the IDEAL cohort

      O'Rourke, G.; Pentecost, C.; Van den Heuvel, E.; Victor, C.; Quinn, Catherine; Hillman, A.; Litherland, R.; Clare, L. (2021)
      Stringent social restrictions imposed during 2020 to counter the spread of the COVID-19 pandemic could significantly affect the wellbeing and quality of life of people with dementia living in the community and their family carers. We explored the impact of COVID-19 restrictions on people with dementia and family carers in England and considered how negative effects might be mitigated. We conducted semi-structured telephone interviews with 11 people with dementia and 11 family carers who were ongoing participants in the IDEAL cohort during the initial ‘lockdown’ period in May and June 2020, and follow-up interviews with five people with dementia and two carers as restrictions were eased in July. We analysed interview data and triangulated the findings with issues raised in dementia-specific online forums. Findings showed some people with dementia were coping well, but others experienced a range of negative impacts, with varying degrees of improvement as restrictions were eased. The need for clear personalised information relating to COVID-19 and the value of support in the form of regular ‘just checking’ phone calls was emphasised. This exceptional situation provides a natural demonstration of how social and psychological resources shape the potential to ‘live well’ with dementia. While some support is recommended for all, a personalised approach to determine needs and coping ability would ensure that further practical and emotional support is targeted effectively.
    • Developing a Management Guide (the DemPower App) for Couples Where One Partner Has Dementia: Nonrandomized Feasibility Study

      Lasrado, R.; Bielsten, T.; Hann, M.; Schumm, J.; Reilly, Siobhan T.; Davies, L.; Swarbrick, C.; Dowlen, R.; Keady, J.; Hellström, I. (2021-11-16)
      Promoting the health and well-being of couples where one partner has dementia is an overlooked area of care practice. Most postdiagnostic services currently lack a couple-centered approach and have a limited focus on the couple relationship. To help address this situation, we developed a tablet-based self-management guide (DemPower) focused on helping couples enhance their well-being and relationship quality. The aim of this study is to investigate the feasibility and acceptability of the DemPower app. A nonrandomized feasibility design was used to evaluate the DemPower intervention over 3 months among couples where a partner had a diagnosis of dementia. The study recruited 25 couples in the United Kingdom and 19 couples in Sweden. Outcome measures were obtained at baseline and postintervention. The study process and interventions were evaluated at various stages. The study was completed by 48% (21/44) of couples where one partner had dementia, of whom 86% (18/21) of couples accessed all parts of the DemPower app. Each couple spent an average of 8 hours (SD 3.35 hours) using the app during the study period. In total, 90% (19/21) of couples reported that all sections of DemPower were useful in addressing various aspects of daily life and helped to focus on how they interacted in their relationship. Of the 4 core subjects on which the DemPower app was structured, home and neighborhood received the highest number of visits. Couples used activity sections more often than the core subject pages. The perception of DemPower's utility varied with each couple's lived experience of dementia, geographic location, relationship dynamics, and opportunities for social interaction. A 5.2-point increase in the dementia quality of life score for people with dementia and a marginal increase in the Mutuality scale (+1.23 points) for caregiver spouses were found. Design and navigational challenges were reported in the DemPower app. The findings suggest that the DemPower app is a useful resource for couples where one partner has dementia and that the implementation of the app requires the support of memory clinics to reach couples at early diagnosis. ISRCTN Registry ISRCTN10122979;
    • Impact of COVID-19 on ‘living well’ with mild-to-moderate dementia in the community: findings from the IDEAL cohort

      Clare, L.; Martyr, A.; Gamble, L.D.; Pentecost, C.; Collins, R.; Dawson, E.; Hunt, A.; Parker, S.; Allan, L.; Burns, A.; et al. (2021)
      Background. Negative impacts of the COVID-19 pandemic on people with dementia have been widely-documented, but most studies have relied on carer reports and few have compared responses to information collected before the pandemic. Objective. We aimed to explore the impact of the pandemic on community-dwelling individuals with mild-to-moderate dementia and compare responses with pre-pandemic data. Methods. During the second wave of the pandemic we conducted structured telephone interviews with 173 people with dementia and 242 carers acting as informants, all of whom had previously participated in the IDEAL cohort. Where possible we benchmarked responses against pre-pandemic data. Results. Significant perceived negative impacts were identified in cognitive and functional skills and ability to engage in self-care and manage everyday activities, along with increased levels of loneliness and discontinuity in sense of self and a decline in perceived capability to ‘live well’. Compared to pre-pandemic data there were lower levels of pain, depression and anxiety, higher levels of optimism, and better satisfaction with family support. There was little impact on physical health, mood, social connections and relationships, or perceptions of neighbourhood characteristics. Conclusion. Efforts to mitigate negative impacts of pandemic-related restrictions and restore quality of life could focus on reablement to address the effects on participation in everyday activities, creating opportunities for social contact to reduce loneliness, and personalised planning to reconnect people with their pre-COVID selves. Such efforts may build on the resilience demonstrated by people with dementia and carers in coping with the pandemic.
    • Using a smartphone on the move: do visual constraints explain why we slow walking speed?

      Rubio Barañano, Alejandro; Faisal, Muhammad; Barrett, Brendan T.; Buckley, John G. (Springer Nature, 2021)
      Viewing one’s smartphone whilst walking commonly leads to a slowing of walking. Slowing walking-speed may occur because of safety concerns or because of visual constraints. We determine how walking-induced phone motion affects the ability to read on-screen information. Phone-reading performance (PRP) was assessed whilst participants walked on a treadmill at various speeds. The fastest speed was repeated, wearing an elbow-brace (Braced) or with the phone mounted stationary (Fixed). An audible cue (‘text-alert’), indicated participants had 2 seconds to lift/view the phone and read aloud a series of digits. PRP was the number of digits read correctly. Each condition was repeated 5 times. 3D-motion analyses determined phone-motion relative to the head, from which the variability in acceleration in viewing distance, and in the gaze angles in the up-down and right-left directions were assessed. A main-effect of condition indicated PRP decreased with walking speed; particularly so for the Braced and Fixed conditions (p=0.022). Walking condition also affected the phone’s relative motion (p
    • Energy Efficient RF for UDNs

      Abdulkhaleq, Ahmed M.; Sajedin, M.; Al-Yasir, Yasir I.A.; Mejillones, S.C.; Parchin, N.O.; Rayit, A.; Elfergani, Issa T.; Rodriguez, J.; Abd-Alhameed, Raed A.; Oldoni, M.; et al. (Springer, 2021-11)
      Multi-standard RF front-end is a critical part of legacy and future emerging mobile architectures, where the size, the efficiency, and the integration of the elements in the RF front-end will affect the network key performance indicators (KPIs). This chapter discusses power amplifier design for both handset and base station applications for 5G and beyond. Also, this chapter deals with filter-antenna design for 5G applications that include a synthesis-based approach, differentially driven reconfigurable planar filter-antenna, and an insensitive phased array antenna with air-filled slot-loop resonators.
    • A new fractional-order chaotic system with its analysis, synchronization, and circuit realization for secure communication applications

      Rahman, Z.S.A.; Jasim, B.H.; Al-Yasir, Yasir I.A.; Hu, Yim Fun; Abd-Alhameed, Raed A.; Alhasnawi, B.N. (2021-10-15)
      This article presents a novel four-dimensional autonomous fractional-order chaotic system (FOCS) with multi-nonlinearity terms. Several dynamics, such as the chaotic attractors, equilibrium points, fractal dimension, Lyapunov exponent, and bifurcation diagrams of this new FOCS, are studied analytically and numerically. Adaptive control laws are derived based on Lyapunov theory to achieve chaos synchronization between two identical new FOCSs with an uncertain parameter. For these two identical FOCSs, one represents the master and the other is the slave. The uncertain parameter in the slave side was estimated corresponding to the equivalent master parameter. Next, this FOCS and its synchronization were realized by a feasible electronic circuit and tested using Multisim software. In addition, a microcontroller (Arduino Due) was used to implement the sug-gested system and the developed synchronization technique to demonstrate its digital applicability in real-world applications. Furthermore, based on the developed synchronization mechanism, a secure communication scheme was constructed. Finally, the security analysis metric tests were investigated through histograms and spectrograms analysis to confirm the security strength of the employed communication system. Numerical simulations demonstrate the validity and possibility of using this new FOCS in high-level security communication systems. Furthermore, the secure communication system is highly resistant to pirate attacks. A good agreement between simulation and experimental results is obtained, showing that the new FOCS can be used in real-world applications.
    • Directional and Isolated UWB-MIMO Antenna Based Uniplanar UWB-FSS Array and T-strip for Bi-static Microwave Imaging: Baggage-Scanner

      Abdulhasan, R.A.; Alias, R.; Ramli, K.N.; Seman, F.C.; Abd-Alhameed, Raed A.; Jawhar, Y.A. (Wiley, 2021)
      This article presented a novel compact multi-input-multi-output (MIMO) hexagonal monopole antenna with a uniplanar compact frequency-selective-surface (FSS) array for microwave imaging (MWI). The ultra-wideband (UWB) dual-element linear MIMO antenna was designed on the FR4 substrate with 50 Ω coplanar waveguide feed, T-strip isolation, novel numerical calculation, and equivalent circuit analyses. The main issues of realising high-resolution images based on planer UWB antenna for MWI are the low gain, omnidirectional pattern, design size, and mutual coupling of MIMO design. A novel technique was proposed to solve a hybrid issue (mutual coupling) of the MIMO reflected-waves from the FSS array and direct-wave. The uniplanar UWB-FSS unit cell was compacted by combining a square-loop and cross-dipole with a size of 0.095λ×0.095λ. The novel isolated UWB-MIMO antenna and UWB-FSS array (IMAF) were integrated, after investigating the distance between the antenna and FSS. The fabricated IMAF with a stable gain improvement of 4.5 dBi higher than the antenna without FSS, directional radiation pattern, size of 30×73.8×21.6 mm3 observed that a low mutual coupling of -27 dB, and operation bandwidth of 3.0-11.7 GHz. Moreover, a handbag was scanned experimentally via the bi-static approach to detect a small concealed object. The MWI system based on the MIMO antenna with FSS was displayed image resolution of 55% higher than that of MIMO antenna without FSS. The new baggage-scanner approach confirmed that the proposed MIMO antenna with FSS array can lead the humanity for healthy MWI applications.
    • CLEAR - Orthokeratology

      Vincent, S.J.; Cho, P.; Chan, K.Y.; Fadel, D.; Ghorbani Mojarrad, Neema; González-Méijome, J.M.; Johnson, L.; Kang, P.; Michaud, L.; Simard, P.; et al. (2021-04)
      Orthokeratology (ortho-k) is the process of deliberately reshaping the anterior cornea by utilising specialty contact lenses to temporarily and reversibly reduce refractive error after lens removal. Modern ortho-k utilises reverse geometry lens designs, made with highly oxygen permeable rigid materials, worn overnight to reshape the anterior cornea and provide temporary correction of refractive error. More recently, ortho-k has been extensively used to slow the progression of myopia in children. This report reviews the practice of ortho-k, including its history, mechanisms of refractive and ocular changes, current use in the correction of myopia, astigmatism, hyperopia, and presbyopia, and standard of care. Suitable candidates for ortho-k are described, along with the fitting process, factors impacting success, and the potential options for using newer lens designs. Ocular changes associated with ortho-k, such as alterations in corneal thickness, development of microcysts, pigmented arcs, and fibrillary lines are reviewed. The safety of ortho-k is extensively reviewed, along with an overview of non-compliant behaviours and appropriate disinfection regimens. Finally, the role of ortho-k in myopia management for children is discussed in terms of efficacy, safety, and potential mechanisms of myopia control, including the impact of factors such as initial fitting age, baseline refractive error, the role of peripheral defocus, higher order aberrations, pupil size, and treatment zone size.
    • Fast versus gradual adaptation of soft monthly contact lenses in neophyte wearers

      Wolffsohn, J.S.; Ghorbani Mojarrad, Neema; Vianya-Estopa, M.; Nagra, M.; Huntjens, B.; Terry, L.; Sweeney, L.E.; Dutta, D.; Joshi, M.R.; Wright, D.; et al. (2021)
      To determine if a gradual adaptation period is necessary for neophytes when fitted with modern hydrogel or silicone hydrogel reusable disposable contact lenses. Across four sites, 74 neophytes (18-28 years) were randomly assigned to a reusable lens cleaned nightly with Opti-Free® Puremoist® multi-purpose contact lens solution: Proclear® (hydrogel) or Biofinity® (silicone hydrogel) and an adaptation schedule: fast (10 h wear from the first day) or gradual (4 h on the first day, increasing their wear time by 2 h on each subsequent day until they had reached 10 h). Masked investigators graded ocular surface physiology and non-invasive tear breakup time (NIBUT) and a range of comfort, vision and lens handling subjective ratings (0-100 visual analogue scales) were recorded at the baseline visit and after 10 h of lens wear, 4-6 days and 12-14 days after lens fitting. Subjective scores were also repeated after 7 days. There was no difference (p > 0.05) in ocular surface physiology or NIBUT between fast and gradual adaptation groups at any time point in either lens type with the exception of increased corneal staining (p = 0.019) in the silicone hydrogel fast adaptation group after 4-6 days, but was similar by 12-14 days. Subjective scores were also similar across the visits and lens types with the exception of 'lens awareness' (p = 0.019) which was less in the gradual versus the fast adaptation silicone hydrogel lens group at 12-14 days. There seems to be no clinical benefit for recommending a gradual adaptation period in new wearers fitted with modern soft reusable disposable contact lenses. The findings of this work add to a growing body of evidence suggesting that such advice is unnecessary in regular soft contact lens wear, which has important ramifications for the initial clinical management of these patients.
    • Why do firm fundamentals predict returns? Evidence from short selling activity

      Mazouz, K.; Wu, Yuliang (Elsvier, 2022-01)
      This study uses short selling activity to test whether the relation between fundamentals and future returns is due to rational pricing or mispricing. We find that short sellers target firms with fundamental performance below market expectations. We also show that short selling activity reduces the return predictability of fundamentals by speeding up the price adjustments to negative fundamental signals. To further investigate whether the returns earned by short sellers reflect rational risk premia or mispricing, we exploit a natural experiment, namely Regulation of SHO, which creates exogenous shocks to short selling by temporarily relaxing short-sale constraints. Evidence from the experiment confirms that the superior returns to short sellers result from exploiting overpricing. Overall, our study suggests that the return predictability of fundamentals reflects mispricing rather than rational risk premia.
    • Sustainability and the Circular Economy

      Clift, R.; Martin, G.; Mair, Simon (Elsevier, 2022)
      Sustainability is a triad including techno-economic efficiency, compatibility with the “Planetary Boundaries”, and equity - enabling a decent quality of life for all. Circular Economy models often focus only on closing material flows in order to increase economic activity or market share. This overlooks the equity dimension. Here we focus on the Performance Economy, which extends the Circular Economy in ways that can enhance equity. The Performance Economy model concentrates on making best use of stocks in the economy, including labour which is a renewable resource. Extending product life through re-use, remanufacturing and reprocessing and shifting from non-renewable inputs (including energy) to renewable inputs (including labour) can improve resource efficiency and increase the supply of rewarding employment. The Performance Economy requires changes in business practices more than technological innovation, including a different view of the functions of value chains, and can be promoted by different approaches to taxation.