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The Determination of Bank Interest Rate Margins - Is There A Role for Macroprudential Policy?
Get PDFJEL Classification: E44, E52, E58, G21, G28.The advent of macroprudential policy alongside monetary policy raises the issue whether macroprudential policy has an additional effect on bank interest rate margins to that of monetary policy, and if so, whether it accentuates or offsets the interest rate effect. In light of this, we estimate combined effects of macroprudential policies and monetary policies on bank interest margins for up to 3,723 banks from 35 advanced countries over 1990-2018. In the short run, tightening of both types of policy tends to narrow the margin, while in the long run, monetary policy typically widens the margin while effects of macroprudential policies are mostly zero or positive, suggestive of countervailing action by banks. There are also significant interactions between macroprudential and monetary policy for several macroprudential policies; a tighter monetary stance is widely found to offset the negative effect of macroprudential policies on margins while a loose monetary policy leaves the negative effects intact, with potential consequences for financial stability. These results are of considerable relevance to policymakers, regulators and bank managers, not least when monetary policies are tight to reduce inflationary pressures.No funding was received for conducting this study. The authors have no relevant financial or non-financial interests to disclose
Single-Axis Solar Tracking Systems: A Comprehensive Design and Performance Study
Get PDFConference paper presented at the 6th International Conference on Industry 4.0 and Smart Manufacturing, Prague, Czech Republic, 20-22 November, 2024.Abundant solar resources and increasing electricity demand make solar energy a promising renewable energy source in Sub-Saharan Africa. However, conventional stationary Photovoltaic (PV) systems face challenges in efficiently capturing solar irradiation. To address this limitation, the implementation of solar tracking systems becomes essential, as they optimize the energy output of PV systems by dynamically adjusting the orientation of the panels to align with the sun’s rays. This study presents a comprehensive design and performance evaluation of single-axis solar tracking systems in Delta State, Nigeria. The investigation focused on the energy provision efficiency of these systems, revealing that the single-axis tracker reached peak performance at year-end, providing 9.333 kWh of available solar energy and 9.296 kWh of user-available energy. Over the year, the system delivered a total of 100.625 kWh of available solar energy and 96.483 kWh of user-available energy. These findings highlight the significant role of solar tracking systems in maximizing energy harvest and underscore their potential for improving energy sustainability in Sub-Saharan Africa
Quantile regression and smoothed empirical likelihood for non-ignorable missing data based on semi-parametric response models
Get PDFMSC (2020) 主题分类 62G05, 62G08In the context of quantile regression with non-ignorable missingness in the response variable, we introduce a semi-parametric exponential tilting model that captures the missingness propensity. To address this, we propose three convolution smoothing-based estimators for quantile regression: inverse probability weighting (IPW), estimation equation imputation (EEI), and augmented IPW (AIPW). These estimators provide consistent estimates for quantile regression coefficients, utilizing the framework of empirical likelihood. We establish theoretical results regarding the asymptotic normality of the three quantile regression estimators, as well as the chi-square property of the corresponding adjusted logarithmic empirical likelihood ratios. Furthermore, we conduct numerical simulations to evaluate the finite-sample performance of these estimators, demonstrating their robustness. To further illustrate the effectiveness of the proposed methods, we apply them to HIV-CD4 data. This application allows us to investigate the differential impact of missing data mechanisms across treatment groups and explore the influence of baseline and previous CD4 and CD8 cell levels on current CD4 cell levels.摘要 在分位回归的响应变量存在不可忽略缺失的情形下,本文引入半参数指数倾斜模型刻画应答概率, 在此基础上提出 3 种卷积平滑分位数回归估计方程: 逆概率加权 (inverse probability weighting, IPW)、估计方程插补 (estimation equation imputation, EEI) 和增强逆概率加权 (augmented IPW, AIPW), 并在经验似然框架下得到倾斜参数和分位回归系数的估计量. 本文在理论上证明3种分位回归估计量等价的渐近正态性和对应调整对数经验似然比函数的渐近χ2性质. 数值模拟比较上述估计量的有限样本表现,验证估计量的稳健性. 本文所提出的方法被应用于CD4(clusterofdifferentiation 4) 数据分析,考察不同治疗组中缺失机制的差异以及基线和前期的CD4和CD8细胞水平对当期CD4细胞水平的影响.北京市自然科学基金(批准号: 1242005)资助项目 [This work was supported by the Beijing Natural Science Foundation (Grant No.: 1242005).
East London Project: a participatory mixed-method evaluation on how removing enforcement could affect sex workers' safety, health and access to services in East London
Get PDFData-sharing statement:
Available data can be obtained from the corresponding author and will be subject to data use agreement between the contractor and the third party requesting the data.Synopsis: This synopsis reports on one component of the research award A participatory mixed-method evaluation on how removing enforcement could affect sex workers’ safety, health and access to services, in East London. For more information about this research please view the award page (https://www.fundingawards.nihr.ac.uk/award/15/55/58).Plain Language Summary:
Some sex workers experience greater levels of violence, anxiety, depression and drug use than people who do not sell sex. This research evaluated the effects of removing police enforcement on sex workers’ safety and health (violence, depression and anxiety) and access to health and social care in East London. The study was participatory: co-researchers with lived experience of sex work or of working closely with sex workers worked with university-based researchers to design, conduct and disseminate the research. We conducted qualitative research (interviews and neighbourhood walks) to understand how police enforcement affected sex workers’ safety, health and service access. We measured how much enforcement affected levels of violence, through a cohort study (recruiting participants and following up with them over time). We then developed a mathematical model to simulate the effects of removing enforcement.
In this urban locality, we found that women (cisgender and transgender) who worked on the street experienced far higher levels of police enforcement and reported more violence from all perpetrators, including police themselves, than those working indoors. They reported higher levels of anxiety and depression and were less likely to be getting help for these problems. In our study, sex workers’ safety and mental health were affected by entrenched poverty, insecure housing, police enforcement and service cuts. Cisgender and transgender women who worked on the street, used drugs, were migrants and/or were women of colour were particularly targeted for enforcement, denied justice and affected by funding cuts to specialist health and support services. Ethnically and racially minoritised sex workers more frequently worked in lower-paid, street-based settings and, regardless of work setting, were more frequently arrested and imprisoned. Our mathematical modelling suggested that stopping the displacement of street-based sex workers alongside the provision of housing could result in a significant (71%) reduction in client violence. Participants recommended redirecting funds from enforcement towards respectful, peer-led services. Findings add weight to existing international evidence on ending enforcement against sex workers and the need to address other of violence and poor health, including reducing poverty, providing housing and commissioning appropriate, community-led services for sex workers.Article history:
The research reported in this issue of the journal was funded by the PHR programme as award number 15/55/58. The contractual start date was in February 2017. The draft manuscript began editorial review in May 2021 and was accepted for publication in June 2022. The authors have been wholly responsible for all data collection, analysis and interpretation, and for writing up their work. The PHR editors and production house have tried to ensure the accuracy of the authors’ manuscript and would like to thank the reviewers for their constructive comments on the draft document. However, they do not accept liability for damages or losses arising from material published in this article.Background:
Sex workers’ risk of violence and ill-health is shaped by their work environments, community and structural factors, including criminalisation.
Aim:
We evaluated the impact of removing police enforcement on sex workers’ safety, health and access to services.
Design:
Mixed-methods participatory study comprising qualitative research, a prospective cohort study, mathematical modelling and routine data collation.
Setting:
Three boroughs in London, UK.
Participants:
People aged ≥ 18 years, who provided in-person sexual services.
Interventions:
Simulated removal of police enforcement.
Outcomes:
Primary – recent or past experience of sexual, physical or emotional violence. Secondary – depression/anxiety symptoms, physical health, chlamydia/gonorrhoea, and service access.
Results:
A combination of enforcement by police, local authorities and immigration, being denied justice when reporting violence, and linked cuts to specialist health and support services created harmful conditions for sex workers. This disproportionately affected cisgender and transgender women who work on the streets, use drugs, are migrants and/or women of colour.
Among women (n = 197), street-based sex workers experienced higher levels than indoor sex workers of recent violence from clients (73% vs. 36%), police (42% vs. 7%) and others (67% vs. 17%); homelessness (65% vs. 7%); anxiety and depression (71% vs 35%); physical ill-health (57% vs 31%); and recent law enforcement (87% vs. 9%).
For street-based sex workers, recent arrest was associated with violence from others (adjusted odds ratio (AOR)) 2.77, 95% confidence interval (CI) 1.11 to 6.94). Displacement by police was associated with client violence (AOR 4.35; 95% CI 1.36 to 13.90) as were financial difficulties (AOR 4.66; CI 1.64 to 13.24). Among indoor sex workers, unstable residency (AOR 3.19; 95% CI 1.36 to 7.49) and financial difficulties (AOR 3.66; 95% CI 1.64 to 8.18) contributed to risk of client violence.
Among all genders (n = 288), ethnically and racially minoritised sex workers (26.4%) reported more police encounters than white sex workers, partly linked to increased representation in street settings (51.4% vs. 30.7%; p = 0.002) but associations remained after adjusting for work setting.
Simulated removal of police displacement and homelessness was associated with a 71% reduction in violence (95% credible interval 55% to 83%). Participants called for a redirection of funds from enforcement towards respectful, peer-led services.
Limitations:
Restriction to one urban locality prevents generalisability of findings. More interviews with under-represented participants (e.g. trans/non-binary sex workers) may have yielded further insights into inequities. Correlation between different risk factors restricted outcomes of interest for the modelling analyses, which were largely limited to experience of violence.
Conclusion:
Our research adds to international evidence on the harms of criminalisation and enforcement, particularly for women who work on street and/or are racially or ethnically minoritised. Findings add weight to calls to decriminalise sex work, tackle institutionally racist, misogynist and otherwise discriminatory practices against sex workers in police and other agencies, and to (re)commission experience-based, peer-led services by and for sex workers particularly benefiting the most marginalised communities.
Future work:
Realist informed trials, co-produced with sex workers, would provide rigorous evidence on effective approaches to protect sex workers’ health, safety and rights.This synopsis presents independent research funded by the National Institute for Health and
Care Research (NIHR) Public Health Research programme as award number 15/55/58
Producing a novel alumina reinforced aluminium matrix composite from aluminium machining waste
No full textThis thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonThis study explores an innovative approach to producing alumina-reinforced aluminium matrix composites (AMCs) directly utilising aluminium alloy machining waste as the primary raw material. By leveraging the machining waste, this research addresses material sustainability and aligns with circular economy principles, minimising resource wastage and promoting environmental sustainability. The focus is on enhancing the naturally occurring alumina on the swarf surface through specific treatments to improve the composite's overall properties. The research methodology employs a multi-technique analysis to monitor and adjust the processing conditions, ensuring optimal material characteristics.
Initially, the aluminium swarf is subjected to high-temperature treatment, followed by Equal Channel Angular Pressing (ECAP) to consolidate the material into a dense, uniform composite. X-ray diffraction (XRD) analysis identifies the phase composition, revealing the transformation of alumina polymorphs under different thermal conditions. Scanning Electron Microscopy with Energy Dispersive Spectroscopy (SEM-EDS) maps the elemental and phase distribution, assessing the interaction between alumina reinforcement and the aluminium matrix. Polarised light observation and Electron Backscatter Diffraction (EBSD) are utilised to evaluate grain refinement, microstructure, and texture, providing insights into the composite's mechanical behaviour.
Key findings indicate that heat treating the aluminium swarf at 650 °C for 2 hours results in the formation of gamma alumina only on the surface. Increasing the temperature to 850 °C transitions the alumina to the alpha phase, known for its superior mechanical properties. Four passes of ECAP using route C effectively consolidate the treated swarf into a composite with no visible macro-porosity, although microporosity around the alumina particulates is still observed. This suggests that while 4 passes, ECAP successfully breaks alumina films and welds adjacent swarfs, this number of passes fails to remove microporosity that could influence the composite's mechanical properties. The composite's performance is further evaluated through tensile and hardness tests, confirming the significant impact of processing conditions on the material's mechanical behaviour. The presence of alpha alumina, achieved through precise heat treatment and the composite's consolidation via ECAP, contributes to enhanced tensile strength and hardness compared to composites with gamma alumina or those processed under less rigorous conditions.
This research contributes to the field of materials science by providing a novel method for repurposing aluminium machining waste into high-value composite materials. By optimising the processing conditions, particularly the heat treatment temperature and the application of ECAP, it is possible to produce AMCs with improved mechanical properties suitable for various high-performance applications. Moreover, this study highlights the potential of using advanced material characterisation techniques to understand the microstructural evolution of composites, guiding the development of more sustainable and efficient manufacturing processes. In conclusion, this study presents a sustainable approach to manufacturing alumina-reinforced AMCs using aluminium machining waste enhanced by high-temperature treatment and ECAP. The findings underscore the importance of processing conditions in determining the composite's microstructure and mechanical properties, offering insights into developing new materials contributing to the circular economy. Future research could explore the long-term performance of these composites in real-world applications and further refine processing techniques to minimise microporosity and enhance material properties
State Estimation for Markovian Jump Neural Networks Under Probabilistic Bit Flips: Allocating Constrained Bit Rates
Get PDFIn this article, the state estimation problem is studied for Markovian jump neural networks (MJNNs) within a digital network framework. The wireless communication channel with limited bandwidth is characterized by a constrained bit rate, and the occurrence of bit flips during wireless transmission is mathematically modeled. A transmission mechanism, which includes coding–decoding under bit-rate constraints and considers probabilistic bit flips, is introduced, providing a thorough characterization of the digital transmission process. A mode-dependent remote estimator is designed, which is capable of effectively capturing the internal state of the neural network. Furthermore, a sufficient condition is proposed to ensure the estimation error to remain bounded under challenging network conditions. Within this theoretical framework, the relationship between the neural network’s estimation performance and the bit rate is explored. Finally, a simulation example is provided to validate the theoretical findings.Natural Science Foundation of Guangdong Province of China (Grant Number: 2021A1515011634 and 2021B1515420008);
10.13039/501100001809-National Natural Science Foundation of China (Grant Number: 62121004, U22A2044 and 62006043);
Key Area Research and Development Program of Guangdong Province of China (Grant Number: 2021B0101410005);
Local Innovative and Research Teams Project of Guangdong Special Support Program of China (Grant Number: 2019BT02X353);
10.13039/501100004543-China Scholarship Council (Grant Number: 202208440312)
Towards 3D Pore Structure of Porous Gypsum Cement Pozzolan Ternary Binder by Micro-Computed Tomography
Get PDFData Availability Statement:
The original contributions presented in the study are included in the article, further inquiries can be directed to the corresponding author.A sophisticated characterisation of a porous material structure has been challenging in material science. Three-dimensional (3D) structure analysis allows the evaluation of a material’s homogeneity, pore size distribution and pore wall properties. Micro-computed tomography (micro-CT) offers a non-destructive test method for material evaluation. This paper characterises a novel ternary binder’s porous structure using micro-CT. Gypsum–cement–pozzolan (GCP) ternary binders are low-carbon footprint binders. Both natural and industrial gypsum were evaluated as a major components of GCP binders. Porous GCP binder was obtained by a foaming admixture, and the bulk density of the material characterised ranged from 387 to 700 kg/m3. Micro-CT results indicate that pores in the range from 0.017 to 3.0 mm can be effectively detected and described for porous GCP binders. The GCP binder structure proved to be dominant by 0.1 to 0.2 mm micropores. For GCP binders produced with natural gypsum, macropores from 2.2 to 2.9 mm are formed, while GCP binders with phosphogypsum possess pores from 0.2 to 0.6 mm. Micro-CT proved to be an effective instrument for characterising the homogeneity and hierarchical pore structure of porous ternary binders.This research is funded by the FLPP (Fundamental and Applied Research Projects) Program in Latvia under the research project lzp-2022/1-0585 “Development and characterization of sustainable gypsum-cement-pozzolanic ternary compositions for 3D printing”
Can AI teach me employability? A multi-national study in three countries
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The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found in the article/supplementary material.This paper examines the impact of using an Artificial Intelligence (AI) teacher for current Higher Education (HE) students from three countries. The study utilized an AI avatar powered by a fine-tuned Large Language Model (LLM), OIMISA, which is trained solely for teaching and learning applications. The AI teacher provided a 9-lesson course on employability and transferable skills. In total 207 students across the three institutions enrolled in the programme. The results demonstrate a noteworthy completion rate of over 47%, along with high levels of engagement across all student cohorts and high satisfaction rates from the students. These show the potential for AI-based virtual teachers across countries for students of HE compared to the use of MOOC platforms.The author(s) declare that no financial support was received for the research, authorship, and/or publication of this article
Grey-box Recursive Parameter Identification of a Nonlinear Dynamic Model for Mineral Flotation
Get PDFThis study presents a grey-box recursive identification technique to estimate key parameters in a mineral flotation process across two scenarios. The method is applied to a nonlinear physics-based dynamic model validated at a laboratory scale, allowing real-time updates of two model parameters, n and C, in response to changing conditions. The proposed approach effectively adapts to process variability and allows for continuous adjustments based on operational fluctuations, resulting in a significantly improved estimation of concentrate grade – one key performance indicator. In Scenario 1, parameters n and C achieved fit metrics of 97.99 and 96.86, respectively, with concentrate grade estimations improving from 75.1 to 98.69 using recursive identification. In Scenario 2, the fit metrics for n and C were 96.27 and 95.48, respectively, with the concentrate grade estimations increasing from 96.27 to 99.45 with recursive identification. The results demonstrate the effectiveness of the proposed grey-box recursive identification method in accurately estimating parameters and predicting concentrate grade in a mineral flotation process
K-moduli of pure states of four qubits
Get PDFMSC classes: 14J45, 14J30, 32Q20.We find all K-polystable limits of divisors in (P^1)^4 of degree (1,1,1,1) and explicitly describe the associated irreducible component of the K-moduli space
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