38541 research outputs found
Sort by
Modelling and simulation of thin film flow in porous media
Get PDFThis thesis explores the behaviour of thin film flow in both porous and non-porous media, considering both single and two-fluid systems. It establishes a comprehensive mathematical framework to describe the flow dynamics under different physical conditions, aiming to clarify the transition between these two regimes. In the case of porous media, the flow is described by the Brinkman equation, which incorporates the effects of permeability and viscous shear.
On the other hand, the Navier-Stokes equation is used to model flow in non-porous media. The model for porous media seamlessly transitions to the non-porous scenario as the permeability parameter, approaches zero, ensuring a consistent approach across both domains. Likewise, the two-fluid system simplifies to a single-fluid model when the parameter , which indicates the viscosity ratio of the fluid, is set to zero.
The thin-film equations are solved numerically with the Chebfun framework, known for its efficient and accurate spectral methods suitable for complex equations. The numerical results examine key parameters such as stability and flow rates and emphasize the relationship between permeability, fluid interactions, and boundary conditions
Reconstitution of the Core Ccr4-Not Complex and Evidence for Possible Interaction between YTHDF2 and Human CNOT9
Get PDFIn eukaryotic cells, shortening and removal of the poly(A) tail of cytoplasmic mRNA (deadenylation) is a key step in mRNA degradation. Studies have shown that the Ccr4-Not complex plays a fundamental role in regulating gene expression at the posttranscriptional level. The different parts of this complex are connected by flexible linkers, which act like bridges to hold the structure together and enable it to work properly. However, it’s currently unclear whether these linkers have preferred conformations or have considerable flexibility. To purify and generate different sub-complexes of Ccr4-Not for biochemical and structural investigation, and further investigate the remodeling and structural dynamics of the Ccr4-Not complex, we focused on purifying and analyzing two important subcomplexes of the core Ccr4-Not complex: the Nuclease/CNOT9 module and the Nuclease/CNOT9/NOT module. I demonstrated the practicality and efficiency of the strategy of co-expressing protein complexes and purifying proteins using Immobilised metal affinity chromatography (IMAC). Secondly, I investigated recruitment of Ccr4-Not complex by YTHDF2 RNA binding protein via CNOT9, since YTHDF2 protein plays a central role in the degradation of m6A-modified mRNA, which is mainly achieved through interaction with the Ccr4-Not complex. In order to explore the interaction between CNOT9 and YTHDF2 domain and further figure out the mechanistic basis of mRNA degradation mediated by YTHDF2 through the Ccr4-Not complex, I demonstrated through peptide pull-down experiments that human CNOT9 can interact with YTHDF2
Contextual sensitivity analysis for urban industrial heritage quarter regeneration: taking Shanghai as a case study
Get PDFThe language of house-museums from private to public: a case-study of Leighton House
Get PDFThis study examines the transformation of private houses into public museums, focusing primarily on properties originally built as artist studio houses. It explores the relationship between these artist studio houses and their new roles as museums, particularly emphasising the intimate and personalised aspects of these spaces. The research aims to understand how these places maintain their private narratives while also functioning as public cultural institutions.
The study focuses on three primary inquiries: the unique characteristics of artist studio House-Museums, the methods adopted by museum curators and/or directors for interpreting and managing their spaces, and the changing roles and perspectives of visitors during their public museum visits.
Employing a grounded theory approach within an interpretivist framework, this research uses a mixed-methods strategy to investigate the complex, multi-layered nature of the case study of artist Frederic Leighton’s studio house in Holland Park, London, and the full spectrum of visitor experiences. This approach allows theories to emerge from the data collected during the case visits, thereby accommodating the intricate and often subjective experiences of museum visitors.
The results are presented within a new analytical framework: The 3T Conception which explains the evolution of these once-private residences into public museums through the processes of Transformation, Transposition, and Transgression. Transformation refers to the physical conversion of private houses into public spaces. Transposition involves recontextualising the artist’s personal artifacts, daily furniture, and private spaces for public viewing and needs. Transgression refers to the visitor experience of crossing both physical and experiential boundaries, significantly altering the nature and perception of the House-Museum.
The findings of the research enhance the understanding of the complex dynamics associated with the transition of private residences into public cultural institutions. It suggests that the interpretation and display strategies used by semi-private artist studio houses may struggle to adequately integrate both realms of private space and public display, adding to the questioning of ambiguous, confusing, or conventional notions of museum spaces. Additionally, it suggests a reassessment of visitor involvement in these distinctive environments; House-Museums
Vibrational response of complex structures to high-frequency correlated loads
Get PDFDistributed Electric Propulsion (DEP) is an innovative aircraft concept where thrust is generated by an array of electrically powered propellers. The application of electric propulsion systems ensures that a significant proportion of the cabin noise within DEP aircraft is the result of structural vibrations driven by Turbulent Boundary Layer (TBL) effects. The purpose of this thesis is thus to extend the Dynamical Energy Analysis (DEA) approach to consider excitations by high frequency correlated pressure fields, such as the TBL pressure field.
In Chapter 1 of this thesis, the rationale of the project is expressed and the necessity for a high-frequency vibrational modelling approach is explored.
In Chapter 2, several high-frequency modelling approaches are evaluated, and the advantages of the DEA approach are highlighted. A detailed review of the DEA methodology then follows. Several TBL pressure field models are then evaluated, based upon their suitability for implementation within DEA.
In Chapter 3, the approach for modelling correlated pressure fields within DEA is developed. This is first applied to model the excitation of small structural regions by homogeneous pressure fields, before being extended to consider full body excitations. Following this, the vibrational behaviour of flat plates is considered under TBL pressure fields for various material, boundary, and flow conditions. Here, the plate response is found to be highly spatially variant and extremely dependent on the system conditions which has received minimal attention in prior studies.
In Chapter 4 the implementation of correlated point-forces, representing vibrations originating from the DEP propeller array, within DEA is explored. Here, the observed vibrational response is found to be the sum of the individual contributions plus a spatially oscillating interference term. This results in complex interference patterns, which are highly variable under different source arrangements. It is also demonstrated that in some situations these interference effects generate steerable beams of vibrational energy, which may be beneficial for sound and wear reduction. The implemented approach however leads to non-physical negative phase-space densities, and an approach to rectify this using the Husimi Density Function (HDF) is discussed
A critical discourse analysis of twitter posts during the Sheraton move: a case study of the online public sphere in Malaysia
Get PDFMy thesis is a study of Malaysian political communication on Twitter by political elites, media organisations, and societal users. Using the Sheraton Move as a case study, I deconstruct 102 872 tweets during the period which witnessed Pakatan Harapan losing its hard-fought victory of the 14th General Elections in 2018. An exploration of literature showed that research of the effect of Twitter usage remain fragmented. Against the theoretical backdrop of Habermas’ public sphere, I propose a framework to better understand the Malaysian Twittersphere. For this, I divide the Malaysian Twittersphere into three communicative levels: the structural, representational, and interactional. I used a mixed method approach that combined critical discourse analysis of expert interviews, focus group discussion of users, archival research with quantitative content analytics to examine the reactions during the Sheraton Move on Twitter.
At the interactional level, societal users report they ‘felt’ democratic agency, particularly in the use of hashtags, mentions and retweets. Findings elucidate how the platform’s architecture amplified and suppressed these vernaculars impacting the reach of tweets. Community detection analysis suggested ways to understand the formation of echo-chambers and illustrate how what each user sees on the platform is algorithmically curated to optimise engagement. Put differently, social media platforms allowed each citizen to exist in individualised media environments. At the representational level, my analysis demonstrated that political communication on Twitter is often constructed as ‘emancipatory’, although almost 90% of tweets were produced in the societal sphere, thematic analysis findings of narratives challenging oppressive structures of power were almost absent. At the structural level, I was able to explain the reinstatement of the political elites on top of the societal hierarchy challenging prevailing notions of net neutrality over themes of deliberative democracy on digital platforms. This suggests that while democratic agency was found to exist in the interactional and part of the representational level, democratic impediments were found to be rife at the structural level.
Overall, the integration of the interactional, representational, and structural levels into a framework provides a basis to advance the understanding of the historically contentious political communication in Malaysia considering the intersectionality of race, class, and technology. Findings from my research offer some reflections about why cautious optimism is needed when viewing technologies that offer the promise of transforming the public sphere
Metaethics and psychology: an investigation into the links between autism, OCD, and depression and metaethics
Get PDFMy thesis examines how psychological conditions impact metaethical theories. More precisely, I look at three separate mental health conditions and how they impact three different metaethical theories. My thesis argues that certain mental health perspectives should inform certain metaethical theories. These mental health conditions are Autism, Obsessive compulsive disorder (OCD), and Major Depressive Disorder, and I will look at how these conditions link to three separate metaethical theories, which are Moral Hermeneutic Fictionalism, Weak Motivational Internalism, and the Humean Theory of Motivation. As I will argue in this thesis that mental health conditions should inform metaethical theories, I will use the mental health conditions specified as case studies to support my overall argument. My findings also yield the conclusion that mental health conditions have different impacts on metaethical perspectives, but nonetheless, these conditions do have an impact on metaethics
Corporate hedging and default risk: a multinational perspective
Get PDFThis thesis discusses three topics regarding hedging by non-financial companies and its impact on default probability with insights from a multinational analysis. The first paper investigates the impact of derivatives on firm’s default probability with a sample of European non-financial firms. The second paper studies the influence of currency hedging strategies with foreign exchange derivatives and foreign debts on default risk. The third paper examines the effect of long-term and short-term interest rate derivatives on the likelihood of default.
The first paper explores the influence of the use of derivative on the risk of default among non-financial firms with a cross-country approach. By using a unique sample of hand collected derivative usage of non-financial firms in nine different European countries, including the UK, France, Germany, Denmark, Italy, Norway, the Netherlands, Spain and Sweden, over the period of 1999 to 2015, our findings suggest that derivative hedging reduces default probability. Our study also shows that the reduction of default risk is more intensive under the use of interest rate (IR) derivatives compared to foreign exchange (FX) and commodity (CP) derivatives. Additionally, our paper records evidence that derivative usage has a statistically bigger negative influence on short-term than long-term default risk. The negative correlation of derivatives and default risk stays robust after performing a wide range of robustness test for possible endogeneity emerging from derivative usage and probability of default. Moreover, our study documents some new evidence that firms with extremely high financial distress may hedge less, as evidenced by the increase in default likelihood. As for the role of creditor rights on the effect of derivative use toward default risk, our results support the notion that firms would hedge more and reduce more risk in countries where creditor protection is strong. Furthermore, we present findings indicating that the efficacy of derivatives diminishes in the presence of lower economic risk within a country.
In the second paper, we investigate the effect of different currency hedging strategies, from foreign exchange (FX) derivatives and foreign currency (FC) debt, used by non-financial firms on default probability with a sample of non-financial firms in six countries including France, Germany, Italy, Norway, Spain and the United Kingdom from 1999 to 2015. Our results show that hedging with FC debt does not reduce and may even increase default probability. Furthermore, generally, we find that linear derivative strategies (FX forwards or swaps) reduce probability of default better than a non-linear strategy (FX options), contrary to our expectation. However, we record that non-linear strategy is more optimal, in terms of default risk reduction, for firms with high growth, whereas low growth firms benefit more from linear strategies. In addition, our results show that currency forwards reduce short-term default likelihood better than swaps, while currency swaps impact more on long-run default risk. Moreover, we document evidence that the effect of foreign debt on default risk is more positive as debt enforcement is more efficient. Interestingly, our findings demonstrate that FC debt could be an effective tool for reducing the likelihood of default, especially for companies operating in countries with weak debt enforcement efficiency and a significant proportion of foreign sales. The empirical analysis employs a battery of robustness tests to control for dynamic endogeneity issues. These findings extend our knowledge of the risk reduction effects of various hedging methods.
The third paper compares the effectiveness of long-term (swaps) and short-term IR derivatives (forwards and options) in reducing default risk for non-financial firms in Germany, France, Spain, Italy, Denmark, Sweden, the Netherlands, Norway and the UK for the period from 1999 to 2015. Interestingly, we find that IR swap contracts are more effective than their short-term counterparts (IR forwards and options) in managing both short and long-term default probability. This could be explained by the fact that long-term derivatives are designed to hedge firm’s total exposure, both short and long term. However. we document evidence that firms in countries which promote the use of short-term liabilities can benefit more, in terms of default risk reduction, from the use of short-term derivatives. In particular, German and Spanish firms that rely more intensively on short-term liabilities experience a larger decrease in the likelihood of default by using short-term IR derivatives compared to long-term contracts. In addition, our findings show that among the short-term derivatives, IR option derivatives reduce the probability of default more effectively than IR forwards. We also document evidence that firms of medium size tend to exhibit a more pronounced reduction in their default probability using IR swaps, while the impact on default risk is insignificant for the smallest and largest firms, potentially due to factors such as less access to derivative markets for small firms and access to fixed-rate borrowing options for large firms. Overall, our findings are novel and able to deliver significant contribution to corporate hedging literature
Recognising and responding to acute deterioration in care home residents. a mixed-methods study
No full textBackground:
Older adults living in care homes are among some of the frailest and most vulnerable in society. Often living with multiple long-term conditions (MLTC), frailty, sarcopenia and age-related changes to immunity means they are at greater risk of becoming unwell and acutely deteriorating. Early recognition and response to acute deterioration is associated with better prognosis and clinical outcomes. However, much of the evidence has emerged from studies conducted in younger population cohorts. Further, initiatives to support identifying and managing this condition in older adults are based on practices adopted from acute inpatient hospital settings. There is a shortage of research on what acute deterioration means for older adults living in care homes and little is known about how care home staff recognise and respond to acute deterioration in residents.
Aims:
The studies in this thesis aimed to understand acute deterioration from the perspectives of care home staff. Specifically, to establish usual practice, explore how care home staff recognise and respond to acute deterioration in residents and identify the barriers and facilitators of this condition to inform future recommendations regarding this aspect of care.
Method
A concurrent mixed-methods design was used to gain a comprehensive understanding of acute deterioration in care homes from the perspective of care home staff. Four work packages were conducted. A scoping review sourced the available evidence regarding acute deterioration in care homes. A care home survey was conducted to establish usual acute deterioration practices in English care homes. Semi-structured interviews were conducted with care home staff to better understand acute deterioration from their perspectives and finally, a Nominal Group Technique (NGT) was conducted with care home staff and topic experts to establish agreed priorities for identifying and managing acute deterioration in care home residents.
Results:
The scoping review included n=11 journal articles. Findings evidenced the concept of acute deterioration was poorly defined. The studies showed acute deterioration was captured tangentially – in relation to other aspects of care and not as the main phenomenon of interest. There were multiple interrelated factors within and external to the care home that influenced how this condition was managed
The survey yielded n=146 responses from fourteen different geographical regions of England. Most responses came from staff aged ≥25 years (95.9%). Just under half of survey responses were from managers (44.5%). The survey identified four acute deterioration tools being used in care homes – NEWS2 (34.2%), RESTORE2 (23.3%), Significant 7 (6.2%) and Stop & Watch (11%). Just over a fifth (21.9%) of responses stated no acute deterioration tool was in use. Respondents were asked to rank their confidence levels in escalating concerns about a resident to different healthcare professionals and services such as GPs. Overall, most respondents selected ‘very confident’ Similarly, respondents who reported not using a tool were asked their confidence levels in escalating their concerns. The majority of responses were also ‘very confident’.
Semi-structured interviews were conducted with twenty care home staff including: registered nurses, care assistants and managers. The findings showed acute deterioration was difficult for staff to define and encompassed different levels of deterioration. However, the relationships staff had with residents enabled them to identify acute deterioration. Findings also highlighted how acute deterioration tools such as NEWS2 and RESTORE2 were boundary objects. Care home staff used them as they provided a universal language to communicate concerns about a resident to external healthcare professionals. Further, some of the findings illuminated potential risks associated with using these tools. Specifically, potential delays in treating acute deterioration because of a mismatch between care home staff’s assessments of residents (indicated deterioration) and clinical indicators (vital signs) not triggering a response.
The Nominal Group Technique NGT brought together an expert panel of experienced care home staff (registered nurses, care assistants and care home managers) and academic/topic experts. The panel co-produced n=31 agreed priorities on what was important to identify acute deterioration, what was important to handover, and what was needed to manage acute deterioration. The top priorities from each round were ‘physical signs and symptoms’, ‘changes in physical symptoms’ and ‘adequate staffing levels’. The agreed priorities offer valuable insights into the needs of care homes to manage acute deterioration and raised important questions about service user needs and the necessary provisions required to support care home residents.
Conclusion:
This thesis has provided a contextual understanding and overview of acute deterioration in care homes from the perspectives of care home staff. This viewpoint was underrepresented in the current body of evidence. The findings from this PhD have helped to bridge this knowledge gap. This thesis lays the foundation for future research on acute deterioration, focusing on establishing appropriate escalation responses and developing frailty-specific strategies for managing and responding to residents' needs. To achieve this, co-production approaches and the involvement of key collaborators (e.g. care home staff and GPs) working together is needed
Access Repository Dashboard
Do you manage Open Research Online? Become a CORE Member to access insider analytics, issue reports and manage access to outputs from your repository in the CORE Repository Dashboard! 👇