Welcome to Research Repository UCD

Research Repository UCD is a digital collection of open access scholarly research publications from University College Dublin. Research Repository UCD collects, preserves and makes freely available publications including peer-reviewed articles, working papers and conference papers created by UCD researchers. Where material has already been published it is made available subject to the open-access policies of the original publishers. This service is maintained by UCD Library.

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  • Publication
  • Publication
    Corporate governance, accountability and mechanisms of accountability : an overview
    Purpose – This paper reviews traditional corporate governance and accountability research, to suggest opportunities for future research in this field. The first part adopts an analytical frame of reference based on theory, accountability mechanisms, methodology, business sector/context, globalisation and time horizon. The second part of the paper locates the seven papers in the special issue in a framework of analysis showing how each one contributes to the field. The paper presents a frame of reference which may be used as a 'roadmap' for researchers to navigate their way through the prior literature and to position their work on the frontiers of corporate governance research. Design/methodology/approach – The paper employs an analytical framework, and is primarily discursive and conceptual. Findings – The paper encourages broader approaches to corporate governance and accountability research beyond the traditional and primarily quantitative approaches of prior research. Broader theoretical perspectives, methodological approaches, accountability mechanism, sectors/contexts, globalisation and time horizons are identified. Research limitations/implications – Greater use of qualitative research methods are suggested, which present challenges particularly of access to the “black box” of corporate boardrooms. Originality/value – Drawing on the analytical framework, and the papers in the special issue, the paper identifies opportunities for further research of accountability and corporate governance.
      32629Scopus© Citations 260
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    Elderly care in Ireland - provisions and providers
    (University College Dublin. School of Social Justice, 2010-04) ;
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  • Publication
    Equality in education : an equality of condition perspective
    (Sage Publications, 2005) ;
    Transforming schools into truly egalitarian institutions requires a holistic and integrated approach. Using a robust conception of 'equality of condition', we examine key dimensions of equality that are central to both the purposes and processes of education: equality in educational and related resources; equality of respect and recognition; equality of power; and equality of love, care and solidarity. We indicate in each case some of the major changes that need to occur if we are to promote equality of condition. Starting with inequalities of resources, and in particular with inequalities tied to social class, we argue for abandoning rigid grouping policies, challenging the power of parents in relation to both selection and grouping, and changing curricula and assessment systems to make them more inclusive of the wide range of human intelligences. In relation to respect and recognition, we call for much more inclusive processes for respecting differences, not only in schools' organizational cultures, but also in their curriculum, pedagogy and assessment systems. Regarding inequalities of power, we call for democratization of both teacher-student relationships and school and college organization. For promoting equality of love, care and solidarity, we argue that schools need to develop an appreciation of the intrinsic role that emotions play in the process of teaching and learning, to provide a space for students and teachers to talk about their feelings and concerns, and to devise educational experiences that will enable students to develop their emotional skills or personal intelligences as a discrete area of human capability.
      22444Scopus© Citations 122
  • Publication
    Discretionary disclosure strategies in corporate narratives : incremental information or impression management?
    (University of Florida. Fisher School of Accounting, 2007) ;
    The purpose of this paper is to review and synthesize the literature on discretionary narrative disclosures. We explore why, how, and whether preparers of corporate narrative reports use discretionary disclosures in corporate narrative documents and why, how, and whether users react thereto. To facilitate the review, we provide three taxonomies based on: the motivation for discretionary narrative disclosures (opportunistic behavior, i.e. impression management, versus provision of useful incremental information); the research perspective (preparer versus user); and seven discretionary disclosure strategies. We also examine the whole range of theoretical frameworks utilized by prior research, and we put forward some suggestions for future research.
  • Publication
    Using Twitter to recommend real-time topical news
    Recommending news stories to users, based on their preferences,has long been a favourite domain for recommender systems research. In this paper, we describe a novel approach to news recommendation that harnesses real-time micro-blogging activity, from a service such as Twitter, as the basis for promoting news stories from a user's favourite RSS feeds. A preliminary evaluation is carried out on an implementation of this technique that shows promising results.
      21014Scopus© Citations 323
  • Publication
    From asset based welfare to welfare housing? The changing function of social housing in Ireland
    (Routledge, 2011) ;
    This article examines a distinctive and significant aspect of social housing in Ireland – its change in function from an asset-based role in welfare support to a more standard model of welfare housing. It outlines the nationalist and agrarian drivers which expanded the initial role of social housing beyond the goal of improving housing conditions for the poor towards the goal of extending home ownership and assesses whether this focus made it more similar to the ‘asset based welfare’ approach to housing found in south-east Asia than to social housing in western Europe. From the mid-1980s, the role of Irish social housing changed as the sector contracted and evolved towards the model of welfare housing now found in many other western countries. Policy makers have struggled to address the implications of this transition and vestiges of social housing’s traditional function are still evident, consequently the boundaries between social housing, private renting and home ownership in Ireland have grown increasingly nebulous.
      20157Scopus© Citations 26
  • Publication
    Constructive approaches towards water treatment works sludge management : an international review of beneficial re-uses
    (Taylor & Francis, 2007-03) ;
    Till date, virtually all known drinking water processing systems generate an enormous amount of residual sludge, and what else to do with this rapidly increasing 'waste' stream in an economic and environmentally sustainable manner remains a significant environmental issue. Perhaps, the realization of this fact has led to series of concerted efforts aimed at beneficial re-uses in an effort to close the loop between efficient water treatment and sustainable sludge management. This paper therefore presents a comprehensive review of available literature on attempts at beneficial reuses of water treatment plant sludge, in an effort to provide a compendium of recent and past developments, and update our current state of knowledge. Four broad categories of uses, which included over eleven possible ways in which waterworks sludges can be reused were identified and examined. Obvious advantages of such reuse options were highlighted and knowledge gaps identified. Future issues that will assist in the development of sustainable waterworks sludge management options with a multi-prong approach were equally discussed.
      19427Scopus© Citations 340
  • Publication
    Expansive cements and soundless chemical demolition agents : state of technology review
    Expansive cements and soundless chemical demolition agents (SCDAs) were first introduced in the early 1970s but failed to gain widespread adoption for selective removal of rock and concrete due to their proprietary nature and a lack of usage guidelines. Nearly 40 years later, the patents have expired, and a large number of competitive products have entered the market. These factors coupled with a heightened interest in their potential environmental benefits have greatly expanded their usage. Specifically, these chemicals can be introduced into a pattern of small, drilled holes in concrete and/or rock. After a specific period (usually less than 24 hours), the in-situ material will crack sufficiently that it can be removed without the use of traditional explosives or further percussive efforts. The products generate substantially less noise and vibration than usually associated with the removal of rock and concrete. This paper provides a state-of-the-technology review of five available products. The focus is on the proposed applicability of various products under specific conditions. Special attention is paid to the viability of such agents under varying temperatures and with materials of particular strengths.
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    Clustering with the multivariate normal inverse Gaussian distribution
    Many model-based clustering methods are based on a finite Gaussian mixture model. The Gaussian mixture model implies that the data scatter within each group is elliptically shaped. Hence non-elliptical groups are often modeled by more than one component, resulting in model over-fitting. An alternative is to use a mean–variance mixture of multivariate normal distributions with an inverse Gaussian mixing distribution (MNIG) in place of the Gaussian distribution, to yield a more flexible family of distributions. Under this model the component distributions may be skewed and have fatter tails than the Gaussian distribution. The MNIG based approach is extended to include a broad range of eigendecomposed covariance structures. Furthermore, MNIG models where the other distributional parameters are constrained is considered. The Bayesian Information Criterion is used to identify the optimal model and number of mixture components. The method is demonstrated on three sample data sets and a novel variation on the univariate Kolmogorov–Smirnov test is used to assess goodness of fit.
      17291Scopus© Citations 49
  • Publication
    Inequality and crime
    (MIT Press, 2000-11)
    This paper considers the relationship between inequality and crime using data from urban counties. The behavior of property and violent crime are quite different. Inequality has no effect on property crime but a strong and robust impact on violent crime, with an elasticity above 0.5. By contrast, poverty and police activity have significant effects on property crime, but little on violent crime. Property crime is well explained by the economic theory of crime, while violent crime is better explained by strain and social disorganization theories.
      16744Scopus© Citations 381
  • Publication
    Agent-based coordination for the sensor web
    The approach described advocates the use of a multi-agent system, and specifically the use of multi-agent distributed constraint optimisation algorithms. Developing software for low powered sensing devices introduces several problems to be addressed; the most obvious being the limited computational resources available. In this paper we discuss an implementation of ADOPT, a pre-existing algorithm for distributed constraint optimisation, and describe how it has been integrated with a reflective agent platform developed for resource constrained devices, namely Agent Factory Micro Edition (AFME). The usefulness of this work is illustrated through the canonical multi-agent coordination problem, namely graph colouring.
      15932Scopus© Citations 2
  • Publication
    Visualization in sporting contexts : the team scenario
    Wearable sensor systems require an interactive and communicative interface for the user to interpret data in a meaningful way. The development of adaptive personalization features in a visualization tool for such systems can convey a more meaningful picture to the user of the system. In this paper, a visualization tool called Visualization in Team Scenarios (VTS), which can be used by a coach to monitor an athlete’s physiological parameters, is presented. The VTS has been implemented with a wearable sensor system that can monitor players’ performance in a game in a seamless and transparent manner. Using the VTS, a coach is able to analyze the physiological data of athletes generated using select wearable sensors, and subsequently analyse the results to personalize training schedules thus improving the performance of the players.
  • Publication
    Provision of childcare services in Ireland
    (University College Dublin. School of Social Justice, 2008-03) ;
    External report commissioned by and presented to the EU Directorate-General Employment and Social Affairs, Unit G1 'Equality between women and men'
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    Curriculum Design in Higher Education: Theory to Practice
    (University College Dublin. Teaching and Learning, 2015-09)
    This eBook emphasises the theory to practice of curriculum design in higher education. The book focuses on programme (not module) level of design; incorporates face-to-face, blended and online curricula; attempts to link theory to practice by giving some practical resources and/or exercises; draws the author's experiences of working and researching into curriculum design in the Irish higher education sector; is aimed at all staff involved in curriculum design, including academic staff (faculty), institutional managers, educational developers and technologists, support staff, library staff and curriculum researchers; is primarily drawn from literature and experiences in the higher education sector, however those in adult and further education may also find it useful. The structure of this book is based on a curriculum design process that the author has developed as part of her experience and research on curriculum design. 
  • Publication
    Michael White's narrative therapy
    (Springer Verlag, 1998)
    A systematized description of a number of practices central to Michael Whites' narrative approach to therapy is given. These include collaborative positioning of the therapist, externalizing the problem, excavating unique outcomes, thickening the new plot, and linking the new plot to the past and the future. The practices of remembering and incorporation, using literary means to achieve therapeutic ends, and facilitating taking-it-back practices are also described. A number of questions are given which may be useful for those concerned with narrative therapy to address.
      14668Scopus© Citations 94
  • Publication
    Financial statement fraud : some lessons from US and European case studies
    (Wiley-Blackwell, 2007-07) ;
    This paper studies 14 companies which were subject to an official investigation arising from the publication of fraudulent financial statements. The research found senior management to be responsible for most fraud. Recording false sales was the most common method of financial statement fraud. Meeting external forecasts emerged as the primary motivation. Management discovered most fraud, although the discovery was split between incumbent and new management.
      14646Scopus© Citations 33
  • Publication
    Focus groups versus individual interviews with children : A comparison of data
    (Routledge (Taylor & Francis), 2006) ;
    In recent years there has been an increase in the use of qualitative data collection techniques in research with children. Among the most common of these methods are focus groups and individual interviews. While many authors claim that focus groups have advantages over individual interviews, these claims have not been tested empirically with children. The present study reports on the use of focus groups and interviews to collect qualitative data from 116 children in three age groups, with mean ages of 8.4, 11.5 and 14.3 years. The children were randomly allocated to participate in either focus groups or individual interviews where they were presented with identical material and questions relating to their beliefs about peers with psychological disorders. In line with previous research, the interviews produced significantly more relevant and unique ideas about the causes of these disorders than the focus groups, but the latter gave rise to greater elaboration of ideas. The participating children showed no significant difference in their preference for one method over the other. Thus, whether to choose individual interviews or focus groups is likely to depend on the nature of the research question in any given study.
      13752Scopus© Citations 37
  • Publication
    The effectiveness of family therapy and systemic interventions for child-focused problems
    (Wiley, 2009-02)
    This review updates a similar paper published in the Journal of Family Therapy in 2001. It presents evidence from meta-analyses, systematic literature reviews and controlled trials for the effectiveness of systemic interventions for families of children and adolescents with various difficulties. In this context, systemic interventions include both family therapy and other family-based approaches such as parent training. The evidence supports the effectiveness of systemic interventions either alone or as part of multimodal programmes for sleep, feeding and attachment problems in infancy; child abuse and neglect; conduct problems (including childhood behavioural difficulties, ADHD, delinquency and drug abuse); emotional problems (including anxiety, depression, grief, bipolar disorder and suicidality); eating disorders (including anorexia, bulimia and obesity); and somatic problems (including enuresis, encopresis, recurrent abdominal pain, and poorly controlled asthma and diabetes).
      13623Scopus© Citations 143
Recent Submissions
  • Publication
    Preparation of iminosugars from aminopolyols via selective oxidation using galactose oxidase
    (Royal Society of Chemistry (RSC), 2022-11-07) ; ; ;
    Minimally protected aminopolyols are novel substrates for the galactose oxidase variant F2. Site-selective oxidation proceeds at the terminal primary alcohol, followed by spontaneous cyclisation to afford stable hemiaminal/hemiacetal anomers of the piperidine and azepane scaffolds, with isolated yields of up to 94%. Simultaneous deprotection and reduction occured readily to afford valuable and biologically relevant iminosugars.
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    Transaminase-Mediated Amine Borrowing via Shuttle Biocatalysis
    (American Chemical Society (ACS), 2022-01-14) ; ; ;
    Shuttle catalysis has emerged as a useful methodology for the reversible transfer of small functional groups, such as CO and HCN, and goes far beyond transfer hydrogenation chemistry. While a biocatalytic hydrogen-borrowing methodology is well established, the biocatalytic borrowing of alternative functional groups has not yet been realized. Herein, we present a new concept of amine borrowing via biocatalytic shuttle catalysis, which has no counterpart in chemo-shuttle catalysis and allows efficient intermolecular amine shuttling to generate reactive intermediates in situ. By coupling this dynamic exchange with an irreversible downstream step to displace the reaction equilibrium in the forward direction, high conversion to target products can be achieved. We showcase the potential of this amine-borrowing methodology using a biocatalytic equivalent of both the Knorr-pyrrole synthesis and Pictet–Spengler reaction.
  • Publication
    Combining bio- and organocatalysis for the synthesis of piperidine alkaloids
    (Royal Society of Chemistry (RSC), 2022-02-07) ; ; ;
    There is continued interest in developing cascade processes for the synthesis of key chiral building blocks and bioactive natural products (or analogues). Here, we report a hybrid bio-organocatalytic cascade for the synthesis of a small panel of 2-substituted piperidines, relying on a transaminase to generate a key reactive intermediate for the complexity building Mannich reaction.
      6Scopus© Citations 4
  • Publication
    rms-prod 1
    (UCD, 2023-01-06)
  • Publication
    rms-test 1
    (Springer Nature, 2023-01-04)
  • Publication
    An assessment of commonage groups and the knowledge transfer needs of upland farmers
    (University College Dublin. School of Agriculture and Food Science, 2022) ;
    Commonages represent ~7% of Agricultural land in Ireland. As predominantly high nature value areas these are of particular interest for preservation and restoration works to encourage biodiversity. However as commonly managed areas this presents a management issue as all parties commonly farming these lands need to work collectively together to make a positive environmental impact. The SUAS project brings together groups of farmers together on these commonages to discuss and address the issues as per each individual commonage. Together proposals are made to address the issues and produce results. In the pursuit of this collective action there is a potential hurdle in achieving harmonised collaboration due to the personal and cultural differences in participants. This study draws on the experiences of SUAS in order to determine key factors and lessons which aid and enhance the collaboration process so that future collaborative projects of a similar nature in Ireland or further afield can share in these lessons. As discovered from the study, key aspects to delivering successful collaboration include: (1) Farmer involvement in all aspects of the project from the beginning. (2) The input of an external facilitator and project manager with distinctly separate roles. (3) Project Manager traits including open and effective communication skills, facilitation and conflict resolution skills, locally knowledgeable, local to the vicinity, an effective and fair leader. Additionally, the study investigated knowledge transfer needs for the scale up of similar projects in Ireland. Lessons include: (1) Farmers require more upland specific research in order to address both production and environmental issues. (2) New information derived from this research is likely to be best received through traditional information sources such as newspapers as opposed to more innovative digital methods. (3) Farmers wish to have the development of future upland agri-environment schemes carried out in a manner that broadly resembles a locally led bottom up approach to their design and implementation.
  • Publication
    Frequency Control of Virtual Power Plants
    (University College Dublin. School of Electrical and Electronic Engineering, 2022) ;
    The Virtual Power Plant (VPP) concept refers to the aggregation of Distributed Energy Resources (DERs) such as solar and wind power plants, Energy Storage Systems (ESSs), flexible loads, and communication networks, all coordinated to operate as a single generating unit. Using as starting point a comprehensive literature review of the VPP concept and its frequency regulation technologies, the thesis proposes a variety of frequency control and state estimation approaches of VPPs, as follows. First, the thesis studies the impact of coordinated frequency control of VPPs on power system transients, in which ESSs are utilized to provide fast frequency regulation. The thesis also proposes a simple yet effective coordinated control of DERs and ESSs able to integrate the total active power output of the DERs, and, thus, to improve the overall power system dynamic performance. The impact of topology on the primary frequency regulation of VPPs is also investigated. With this regard, two types of VPPs topologies are considered, that is, a topology where the DERs that compose the VPP are scattered all-over the transmission grid; and a topology where the DERs are all connected to the same distribution system that is connected to the rest of the transmission grid through a single bus. Next, the thesis proposes a control scheme to improve the dynamic response of power systems through the automatic regulators of converter-based DERs. In this scheme, both active and reactive power control of DERs are varied to regulate both frequency and voltage, as opposed to current practice where frequency and voltage controllers are decoupled. To properly compare the proposed control with conventional schemes, the thesis also defines a metric that captures the combined effect of frequency/voltage response at any given bus of the network. Finally, the thesis presents an on-line estimation method to track the equivalent, time-varying inertia as well as the fast frequency control droop gain provided by VPPs. The proposed method relies on the estimation of the rate of change of the active and reactive power at the point of connection of the VPP with the rest of the grid. It provides, as a byproduct, an estimation of the VPP’s internal equivalent reactance based on the voltage and reactive power variations at the point of connection. Throughout the thesis, the proposed techniques are duly validated through time domain simulations and Monte Carlo simulations, based on real-world network models that include stochastic processes as well as communication delays.
  • Publication
    Low-Complexity Digital Predistortion for 5G Massive MIMO and Handset Transmitters
    (University College Dublin. School of Electrical and Electronic Engineering, 2022)
    The demand for new wireless communication systems to support high mobility and low latency necessitates a rethink of the architecture of wireless communication systems as well as the design of their key components. This thesis presents several novel techniques to solve the major challenges in digital predistortion (DPD) for millimeter wave multi-input multi-output (MIMO) and handset transmitters to lower the hardware cost and computational complexity of the fifth generation (5G) communication systems. The first part of the thesis focuses on the architecture of the MIMO DPD solution for 5G transmitters. To extract DPD model coefficients, a feedback data acquisition path is required. In conventional single-input single-output (SISO) systems, the output is usually acquired directly from the power amplifier (PA) with a coupler. In massive MIMO systems, the number of RF chains is large. Using dedicated feedback paths for each PA separately is not feasible. To lower the hardware cost, a novel data acquisition scheme is proposed to obtain the output signals in far field over the air (OTA) using a single antenna and feedback loop, and then reconstruct the output of each PA. Simulation and experimental results demonstrate that the proposed OTA data acquisition can accurately reconstruct the output of each PA in the MIMO systems and the DPD solutions derived from the reconstructed data can successfully linearize the nonlinear MIMO transmitters. In the multi-user scenario, the nonlinearity of the transmitters varies with the movement of user equipments (UEs), and the DPD model coefficients need to be updated accordingly. To meet the requirement of high mobility, the complexity of the system update must be low. In the second part of the thesis, we present a new DPD system, where DPD model can be updated fast and accurately without capturing PA output or applying costly model extraction algorithms. In the proposed method, nonlinear characteristics of the PA are encoded into low-dimensional PA features using feature extraction algorithms. To identify DPD model coefficients, PA features are extracted first and the DPD model coefficients are then generated directly by DPD generator with PA features. Experimental results show that the proposed DPD solution can linearize PA with very low complexity compared to that using the conventional solutions. Finally, the focus shifts to handset transmitters. Conventionally, DPD is usually deployed for high power base stations. With the continuously increasing bandwidth, DPD may also be required for handset PAs in 5G communication systems. Different from the models used for base stations, DPD model for handset PAs must have very low complexity because of the stringent power budget limit. At the same time, the tolerance for load mismatch must also be considered. The third part of the thesis analyzes the characteristics of handset PAs with load mismatch and introduces a low-complexity DPD model based on magnitude-selective affine (MSA) function. Experimental results demonstrate that the extended MSA (EMSA) model shows better linearization performance while keeping much lower complexity than the conventional DPD models.
  • Publication
    Superparamagnetic Nanoparticles for the Assessment of Intracellular Nanoparticle-Cell Interactions
    (University College Dublin. School of Chemistry, 2022) ;
    Since their discovery, nanomaterials have been employed in an increasing number of products and applications. Thanks to their unique properties they enabled the advancement of many technologies and improved our lives under several aspects. Because of their nanometric dimensions, nanomaterials interact with the biological matter in a completely different way compared to their smaller (molecular scale) or larger (macro scale) counterparts. Despite the efforts of the scientific community in unravelling the network of machineries involved in the interaction of nanomaterials with the cells and human body, our understanding of the bio-nano interactions is still limited. The lack of knowledge around the dynamics that regulate the nanoparticles’ (NPs) trafficking in the human body is limiting the development of nanomedicine and, at the same time, is rising concerns in the regulatory bodies for the safe commercialisation of nanomaterial-based products. One of the main issues related to this critical gap in the knowledge is the lack of methodologies and tools that prevents unravelling the complexity of the bio-nano interactions. Techniques commonly used for the study of the intracellular dynamics result limiting for the study of the NPs intracellular trafficking for which the combination of different analysis and methodologies is required to obtain reliable and robust results. However, the correlation of data from different techniques is difficult when different NPs systems are used for the experiments. In this thesis, we develop new tools and methodologies for the study of the bio-nano interactions, exploiting one of the unique properties of iron oxide NPs, the superparamagnetism. In this context, superparamagnetic NPs are extremely useful tools because allow to label the machineries involved in the intracellular trafficking of NPs and enable their isolation from the biological matrix, which in order allows a more in-depth downstream analysis. To label the machineries involved in the intracellular trafficking with superparamagnetic NPs, two strategies are possible: exploiting the natural uptaking mechanisms of the cells or targeting specific compartments with NPs designed ad hoc. To exploit the first strategy, we designed multifunctional core-shell NPs with iron oxide multicores that provided the superparamagnetic properties and a silica shell doped with an organic fluorophore. Combining the magnetic and fluorescent properties in one nanoconstruct enabled to resolve the NPs intracellular trafficking by optical microscopy and to isolate the vesicles loaded with the NPs by magnetic separation, at different stages of their voyage inside the cell. The vesicles were then analysed with a set of technique to evaluate their integrity and functionality. To exploit the second strategy, we designed antibody grafted iron oxide NPs for the targeting of specific biological species. For this purpose, we adopted a thoughtful strategy of NPs surface modification that enabled the grafting of the antibody through bio-orthogonal chemistries, stabilise the particles in biological conditions, and limit the adsorption of undesired biomolecules typically responsible for NPs off-targeting. Although this second nanoconstruct is still under development, the preliminary results showed excellent targeting ability and specificity. Overall, the work presented in this thesis provides a solid base for the isolation, by magnetic separation, of biological species involved in the NPs intracellular trafficking and for the development of methodologies for the investigation of the machineries involved in the process.
  • Publication
    Circularly Polarized Antennas for 5G Millimetre-Wave Communications
    (University College Dublin. School of Electrical and Electronic Engineering, 2022)
    The need of a higher data rate, lower latency, and cost efficiency led to the fifth-generation (5G) emerging as a new communication standard. This generation includes many unused frequencies with high available bandwidth channels that can provide higher capacities such as millimeter-wave (mm-wave) bands. One of the main challenges of working at high frequencies of this generation is path loss that needs to be addressed. To overcome this issue, a high gain antenna with a small size is required. Consequently, the first major question arises: how to effectively increase the gain and efficiency of the antenna at a high frequency with a small size. Importantly, it is vital to transport as much as data is possible without any sensitivity to the alignment of the transmitter or receiver antenna that can be satisfied by using circularly polarized (CP) radiating waves. Thus, the second research question emerges: how to provide high gain small size antenna with CP at high frequencies. To address the first two major research questions in this thesis we designed a miniature dual-band CP antenna that works at 28 GHz and 38 GHz with high gain. This antenna can be implemented in mobile devices, unmanned aerial vehicles (UAVs), and base stations (BSs) because of the small sizes of 11 × 14 × 0.508 mm3. For getting a deep insight into the structure and the design procedures of the dual-band antenna, characteristic mode analysis (CMA) is employed. Note that the CMA is not sensitive to the feeding position and the material in this analysis is not lossy. Therefore, after using CMA, the optimization is conducted in the full-wave simulation as the feeding is added to the structure, and the material is lossy. The single CP antenna covered the bands of 27-28.4 GHz and 34.7-40 GHz, with a maximum gain of 6.3 dBiC and 5.51 dBiC at 28 GHz and 38 GHz, respectively, whereas the radiation efficiency is 94% and 96% with the ARBW of 2.5% and 1.5%. A phased antenna array is then constructed to provide a higher gain for this designed dual-band antenna. In a phased antenna array we consider four designed single element antennas close to each other to create a 2 × 2 antenna array with high gain at 28 GHz and 38 GHz. For a 4 × 4 antenna array, an electromagnetic band-gap (EBG) is used to reduce the mutual coupling between elements in the array. The radiating signals will be sent to different users with circular polarization via electronic beamforming. The position of each antenna element is also optimized to provide the constructive radiating wave towards our desired directions. The array was able to steer the beam between -26.5 to 29.5 degrees for the lower band and -29.5 to 35.5 degrees for the higher band with the maximum gain of 12.8 dBiC and 11.5 dBiC, respectively. Another method to enhance the gain is implementing a lens structure in front of the radiating antenna. Here, a significant challenge is to maintain the CP of the incoming CP wave while the gain is increased. Therefore, the third research question is how to design a lens with the capability of enhancing the gain and keeping the CP when the lens is fed by a CP antenna source. Concerning the third major research question, in this thesis, we designed a CP lens structure. First, a multi-layer lens with a thickness of 2.03 mm was designed, and then a one-layer lens structure with a thickness of just 0.508 mm was made. The lens was located in front of different radiating antennas. These lens structures resulted in significant gain enhancement for various feeding antennas working at 28 GHz. The unit cell of the one-layer lens can provide a broad phase shift compared to the multi-layer counterpart. The proposed lens structures not only increased the gain of the incoming CP wave but also kept its polarization to overcome the issues of reflectivity, absorption, inclement weather, and mis
  • Publication
    Contributions to the theory and development of low-jitter bang-bang integrated frequency synthesizers
    (University College Dublin. School of Electrical and Electronic Engineering, 2022)
    The advent of next-generation wireless standards demands ever-increasing data-rate communication systems. It mainly involves a higher carrier frequency to take advantage of wider bandwidth channels and more complex modulation schemes to pack more information into each symbol. In this context, the bottleneck is represented by the frequency synthesizer used to generate the local oscillator signal for the transceiver, which has to operate under stringent low output jitter requirements. Such performance must be provided at low power dissipation and area consumption in order to meet the requirements of low-cost and high integration level of the modern communication systems. The digital phase locked loop architecture can meet the required jitter performance while synthesizing fractional-N frequencies. Such PLLs offer significant advantages over their traditional analog counterpart in terms of area occupation, flexibility and scalability in advanced deep sub-µm CMOS technologies. The digital PLL topology based on a bang-bang phase detector, denoted bang-bang PLL, which is a single bit digital phase detector, leads to a less complex and more power-efficient architecture, but, on the other hand, it also introduces a hard nonlinearity in the loop, making the analysis of the bang-bang topology more challenging than in the multi-bit case. A comprehensive phase noise analysis of bang-bang digital PLLs is presented which overcomes the limitations of previous models and it is valid in all cases where physical noise sources (i.e. reference and DCO) are dominant with respect to quantization errors. In particular, (i) input-referred jitter is estimated by means of a linear time-domain analysis derived from a nonlinear DPLL model, and (ii) phase noise spectra are predicted using a discrete-time domain model that accounts for time-variant effects that arise from the intrinsic multirate nature of the DPLL. The possibility of accurately determining the DPLL jitter and phase noise spectra, enabled by the novel analysis presented in this thesis, is key to significantly speeding up the design-space exploration phase, since it allows one to perform quick and precise parametric sweeps. However, even when designed properly, bang-bang PLLs are affected by the unavoidable bang-bang phase detector quantization noise, which is added on top of the intrinsic reference and DCO phase noise. The quantization noise can be appreciated in the PLL's output spectrum as increased in band noise with respect to the analog counterpart, that, in fact, still achieves superior performance in terms of jitter-power. This results in worse integrated jitter performance for the same intrinsic levels of reference and oscillator phase noise. To overcome the binary phase detector quantization noise in DPLLs, state-of-the-art works rely on a multi-bit time-to-digital converter to digitize the PLL phase error with a physical resolution below the input jitter, leading to increased design complexity, with an associated area and power penalty. In order to overcome the ultimate limit of the bang-bang PLL, a digital PLL based on a bang-bang phase detector with adaptively optimized noise shaping has been fabricated in a 28nm CMOS process. The prototype occupies a core area of 0.21 mm2 and draws 10.8 mW power from a 0.9 V supply. The integrated jitter is 69.52 fs and 80.72 fs for the integer-N and the fractional-N case, respectively. Achieving a jitter-power figure-of-merit of -251.5 dB in fractional-N mode, the proposed system effectively bridges the gap to analog implementations. The first chapter of this work is introductory, and is intended to give some background information needed to underpin the remaining part of the thesis. The following chapters, 2, 3 and 4, collect the results achieved during the PhD activity, and each of them is associated with a publication. In the last chapter, conclusions are drawn and the open points are discussed in order to be considered for future work.
  • Publication
    Sport in Dublin in the nineteenth century
    (University College Dublin. School of History, 2022) ;
    Despite the recent growth of academic interest in Irish sport history, the emergence of formally organized sport in nineteenth-century Irish urban areas has received scant attention. This thesis addresses such a gap and maps out the transition from a traditional world of play to a modern sporting scene in Dublin, Ireland’s capital city. It is argued that the development of a modern capitalist society in the eighteenth century and the resulting emergence of an associational culture, the bureaucratisation of state apparel, the development of faster and cheaper means of transportation, and the dissemination of information contributed to the nineteenth-century codification, commercialisation, and internationalisation of sport. Such change was especially observed among elite pastimes in the earliest part of the century, but as living standards increased from mid-century, the model spread to the city’s middle class and eventually reached the working class by the 1880s. Drawing extensively from contemporary newspapers and archival material, this thesis stresses the roles of social class, gender, education, urbanisation, religion, and politics in shaping the modern sporting scene in Dublin. Conversely, it emphasises how sport was central to the evolution of the nineteenth-century city and its importance to the everyday life of its inhabitants. By correlating such findings with broader evolutions then taking place in Britain and Ireland, the present research assesses the extent to which the development of sport in Dublin fitted national and international trends but also highlights its original features. In so doing, it enriches our understanding of Ireland’s sporting past.
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    Modelling and Simulation of Long-Term Dynamics in Power Systems
    (University College Dublin. School of Electrical and Electronic Engineering, 2021) ;
    A reliable and cost-effective operation of power systems involves different tasks over different time horizons ranging from tens of milliseconds (protection) to years (planning). Generally, power system operators routinely check the effectiveness of these tasks separately (depending on time constants) through computer studies based on mathematical models. While the modelling and simulation of short-term dynamics of power systems (e.g. electromagnetic and transient simulation) have received tremendous attention in the literature, that is not the case for long-term dynamics. In this context, this thesis aims to assist power system operators in addressing the modelling and simulation of long-term dynamics in modern power systems (minutes to years). To do so, the thesis presents novel mathematical and software tools that allow studying the long-term impact interactions between different short-term electricity markets models and power systems, and the impact of energy policy incentives on the evolution of Renewable Energy Sources (RESs) technologies, particularly that of solar Photovoltaics (PVs). Short-term electricity markets are essential tools to guarantee the reliable operation of the power system. They are moving closer to real-time and using finer time resolutions (e.g. 5 minutes) in response to the large-scale integration of variable RESs. This means that their dynamics evolve with a timescale similar to some long-term power system dynamics, e.g. the Automatic Generation Control (AGC). Consequently, assessing the impact interactions between such markets and the dynamic response of the power grid becomes increasingly important. The contributions on this topic are as follows: (i) Investigate the effect of real-time electricity markets modelled as a sort of discrete AGC or Market-based Automatic Generation Control (MAGC) on power system dynamics. In particular, a thorough analysis using Time Domain Simulations (TDSs) is provided. (ii) Propose a short-term dynamic electricity market model that includes the memory effect of market participants. Particularly, the effect of the memory of suppliers on the decision-making (generator schedules) and dynamic response of the grid is discussed. (iii) Investigate the impact interactions between sub-hourly deterministic Unit Commitment (d-UC) and stochastic Unit Commitment (s-UC) and the power grid. Furthermore, the thesis also proposes a dynamic model based on nonlinear delay Differential-Algebraic Equations (DAEs) able to predict the evolution of PV installations for different countries. This model is a valuable tool that can help policymakers in the decision-making process, such as the definition of the Feed-in Tariff (FiT) price and the duration of the incentives. Finally, the proposed models and tools are duly validated throughout the thesis by means of numerical tests based on benchmark test systems.
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    Labour and Factory Utopias: Olivettian Writers and Testimonial Intent
    (University College Dublin. School of Languages, Cultures and Linguistics, 2022) ;
    The aim of this research is to posit the existence of a link between visions of factory utopia and Italian industrial literature in Italy during the twentieth century, and to suggest the presence of a testimonial intent behind these works. The writers I study have come to be defined as ‘Olivettian writers’, given their proximity to Adriano Olivetti, an entrepreneur from Ivrea, in Northern Italy, who was active during the first half of the twentieth century. Olivetti surrounded himself with writers and poets such as Ottiero Ottieri, Paolo Volponi, Libero Bigiaretti and Giancarlo Buzzi, and these authors worked alongside him in the advertising office and in the Human Resources departments of Olivetti Inc. in both the factories in Ivrea and Pozzuoli (Naples). My purpose here is to answer three questions: first, whether there is a relationship between labour and visions of utopia in Italian industrial literature; secondly, why the topic of factory life was explored by the authors who worked alongside the Italian entrepreneur Adriano Olivetti and to what extent these authors agreed with Olivetti’s vision? Finally, I examine whether there is a testimonial intent behind Italian industrial novels. In answering these questions, the thesis engages with ideas of utopian working conditions, socialism, and factory life. To do so, I will consider Marx’s theory of alienation since the condition of alienation is one of the main reasons for Adriano Olivetti’s alternative vision of utopia, although he also acknowledges the limits of Marx’s analysis. Then, after introducing the literary authors who surrounded Olivetti and their own reception of the entrepreneur’s utopia, I will analyse three novels written by Olivetti’s authors in detail: Donnarumma all’assalto by Ottiero Ottieri (1959), Memoriale (1962) and Le mosche del capitale (1989) by Paolo Volponi. I mainly utilise a narratological methodology, drawing on the work of Roland Barthes, Gérard Genette, Mieke Bal. I also draw on Mikhail Bakhtin’s analyses of narrative discourse and Michel Foucault’s studies on disciplinary power, while acknowledging, when necessary, links and connections with structuralist theory. The novelty of my perspective lies in the narratological analysis of these works, in taking into consideration their paratexts – which have often been overlooked, and especially in relation to discussions of industrial literature as a genre – and in interrogating the possibility of the presence of a testimonial intent in these novels. Given the centrality of the topic of labour, I refer to Marxist criticism and, in particular, I consider I quaderni dal carcere by Antonio Gramsci, since Gramsci has been fundamental in establishing Marxist criticism in Italy. Finally, since a clear definition of Italian industrial literature is still under debate, I will demonstrate how the testimonial intent behind these novels is fundamental to a full characterisation of that part of Italian literature concerned with factories and workers’ alienation.
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    The Physiochemical and Biological Characterization of Nanostructured Materials Derived from Natural Processes
    (University College Dublin. School of Chemistry, 2022) ;
    The thesis focuses on the study of nanostructured materials obtained from natural sources. The work presented in this thesis was designed to 1) develop protocols for a complete Physico-chemical characterization of micro-and nanomaterials derived from calcified seaweed. Such protocols were achieved by combining several different characterization techniques and were able to unravel unexpected material features at the nanoscale; 2) obtain nanostructured metallic particles from the calcified seaweeds through a multistep extraction protocol and investigate their interactions with cells. The extensive characterization work carried out along this project, especially using electron microscopy, also allowed to develop methods for the visualization of endogenous biological material associated with nanoparticles after their interaction with biomolecules and the intracellular environment.
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    Complex Nanostructures and Bio-Nanoscale Interactions: Well Defined Synthesis, Identification and Biological Effects
    (University College Dublin. School of Chemistry, 2022)
    In this thesis, a framework was proposed in chapter II, aiming to identify distinct shape populations and build a quantitative linkage of well-defined nanoscale shapes to biological impacts. This inductive nanoscale shape discovery and evaluation framework is biologically relevant, and we believe by utilizing machine learning it could benefit the field of shape dependent therapy. In chapter III, the shape dependent histone modifications were reported. As histone modifications are one of the crucial epigenetic regulators that control chromatin structure and gene transcription, shape dependent histone modifications indicate that some important cellular phenotypes differences induced by nanoscale shapes may be related to the histone modifications, which opens a new window for the investigation of nanoscale shape effects and nano therapy. In chapter IV, we proposed a method to modify the surface of the nanostructures by endogenous cellular processes and studies found that this re-engineered particle complex was able to transfer the loading genes to recipient cells, which indicates their potential to work as an efficient nucleic acid delivery machine.
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    Rethinking legal and procedural rules in rights-based systemic climate change litigation: a comparative study of European countries
    (University College Dublin. School of Law, 2022) ;
    This PhD thesis by papers examines the extent to which climate change requires us to rethink or recraft legal doctrines and procedural rules in rights-based systemic mitigation cases in Europe. The three doctrines focused on, in each of the respective papers, are standing, justiciability, and causation. The thesis begins by contextualising and locating the research in the wider body of climate litigation scholarship before unpacking the thesis’ epistemological and theoretical stance: a stance broadly supportive of rights-based approaches. To arrive at this position, the thesis engages with various critiques of rights-based approaches to climate action. The thesis illustrates how a rights-based framing can and should be a practical and effective discourse for dealing with climate issues, but that creative scholarly thinking is required when it comes to dealing with standing, justiciability, and causation. The thesis then proceeds in three papers. The first paper investigates whether an exceptional approach to standing rules is needed in rights-based systemic mitigation cases to reconcile the gatekeeping function of European domestic and regional courts like the Court of Justice of the European Union with the complexity and urgency of the climate crisis. The paper shows that developing inclusive standing rules for rights-based systemic mitigation cases does not require (European) courts to stretch existing standing rules to breaking point but rather to engage seriously with the existing access to justice obligations and the wider purposes of the UNECE Aarhus Convention. The second paper explores the question of what role (if any) do judges already play and should judges play in reviewing the adequacy of states’ climate mitigation policies in rights-based systemic mitigation cases? It asks whether the role of judges needs to be reconceived in the era of climate breakdown? The central finding of the second paper is that judges can and should scrutinise actions of the other two branches on climate mitigation and that it is possible to do so in a manner that does not do violence to the doctrine of the separation of powers. The third and final paper examines the question of causation and the fair allocation of responsibility in rights-based systemic mitigation cases, using a climate justice framing. It looks at whether the widely accepted political theory contributions on climate justice particularly in relation to fair burden sharing, harm avoidance, and a just distribution of the remaining carbon budget can (and ought to) be incorporated or reflected in judicial reasoning on causation in rights-based systemic climate litigation. It examines if and how wider use of the European Court of Human Rights’ lenient approach to causation at the national level could be a way of overcoming causal difficulties that might otherwise extricate wealthy developed country governments that are signatories to the European Convention on Human Rights from responsibility. It also illustrates how rights-based arguments might be a way of operationalising climate justice in judicial reasoning in rights-based systemic mitigation cases in Europe. The central claim of the thesis is that each of the knotty doctrinal questions – standing, justiciability and causation – can be resolved in rights-based systemic mitigation cases without upending the existing legal order in Europe where expansive and creative interpretations of these doctrines are embraced. The value of pursuing these kinds of interpretations is that they allow fundamental rights to deliver on their emancipatory promises in the face of a worsening climate crisis.
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    Optical Eye Modelling for Myopia Control
    (University College Dublin. School of Mechanical and Materials Engineering, 2022)
    Myopia is posing a big threat to the global eye health and putting the young generation in danger of blindness. To prevent the development of high myopia, optical lenses have been developed based on the findings that the peripheral optical properties of the eye can affect myopia progression. As the core for many applications in myopia control, a realistic eye model should be established that reproduces the optical and structural features of the human eye. Based on the ocular data obtained from the recent measurement technologies, this thesis investigates the peripheral optical features of the ocular components and develops new models to achieve a more realistic description of the human eye for the wide visual field. As the most complex component in the eye model, a new crystalline lens model is proposed in Chapter 2 to represent the structural and functional features of the lens of children. The model has the capability of involving most parameters measurable on the in vivo human lens, while maintaining realistic values of optical power and spherical aberration. Starting from the lens model proposed in Chapter 2, Chapter 3 develops a method for evaluating the peripheral refracting properties of the lens. The impacts of the lens structural parameters to the peripheral lens power are systematically evaluated. Specifically, the contribution of the gradient refractive index structure to the peripheral lens power has been revealed. In Chapter 4, a fast computation method based on generalized ray tracing is developed to analyze the peripheral optical power of the cornea defined in a similarly way as proposed in Chapter 3. The method is tested on the realistic corneal model constructed from measurement data. The contribution of the cornea to the ocular refractions over the entire visual field can be formulated based on the proposed procedure. Chapter 5 and 6 investigates the role of the retinal contour to the peripheral optical properties of the eye. Specifically, a highly efficient method is proposed that can reproduce the peripheral spherical equivalent refraction over the entire visual field by retinal contour modeling. Overall, this work contributes a theoretical framework and knowledge base on the peripheral optics of the human eye, which are instrumental for developing potential approaches aimed for higher efficacy in myopia control.
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    Investigations of Tribological Performance of Structured Surfaces on Bioimplants
    (University College Dublin. School of Mechanical and Materials Engineering, 2022)
    Bioimplants are man-made medical devices to replace the malfunctional natural joints. In the past six decades, total joint replacement is credited as one of the most successful surgical operations. Metal alloy matching with polymer is the most common material combination used in the bearing parts of artificial joints. However, most commercial products have a relatively short in-vivo lifespan due to the unsatisfactory tribological performance of bearing parts. This study aims at increasing the longevity of bioimplants by modifying the surface topographies of bearing parts, including surface roughness and surface texturing. This thesis starts with the motivation of carrying out this project, followed by a comprehensive literature review. In Chapter 3, the validity of molecular-mechanical frictional theory is tested for the bioimplant application using the pin-on-disk tribometer. By a long-term sliding test (10 km) and the dynamic analysis, the study firstly highlights the importance for the metallic bearing surface to keep its original surface finish after implantation other than only getting a superfinished surface before implantation. As a result, surface texturing approach is proposed to achieve this goal. In Chapter 4, the impact of four potential working mechanisms related to surface texturing in bioimplants are investigated. An important finding on the role of hydrodynamic pressure on the tribological performance of textured implants is presented: the extra lifting force provided by hydrodynamic pressure is negligible. This unique property distinguishes the bioimplants application from other conventional bearing systems. Further numerical simulation and experimental experiments attribute this novel finding to the working conditions of implanted joints: slow sliding speed and low viscosity lubricating solution. Alternatively, a new understanding, namely squeezing effect, is established to explain the increased thickness of lubricant film which helps to improve the tribological performance of textured bioimplants. Meanwhile, a novel failure mechanism, interlocking effect (stress concentration and two-body abrasive wear), is put forward to explain why some pattern designs, such as sharp-corner structure, are detrimental to the bioimplants. Afterwards, a technical solution, namely round-corner structure, is developed to resolve the interlocking effect. In Chapter 5, sliding orientation is found to play a minor role on the tribological performance of textured bioimplants and this phenomenon is explained by the proposed working mechanism of squeezing effect. Furthermore, the regularly arranged texturing patterns are proved to be more suitable for bioimplants than the irregularly arranged micro patterns. Finally, an orthogonal experiment is designed to reveal the influential level of five main pattern parameters: area density > size > shape > depth > distribution mode. The conclusion is that the optimal pattern design with specific parameters: triangle structure with 200 µm side length, 8-10 µm depth, 10% area density and square distribution mode, can provide the optimized tribological performance. In Chapter 6, a long-term wear experiment with 1 million cycles is carried out to compare the tribological performance between the only polished bioimplants and the ones with optimal structured bearing part. The study confirms that, by applying the optimal structured surface, the in-vivo longevity of polymer-based bioimplants can be effectively increased.
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    Extracellular Vesicles in Cardiovascular Disease – Modulation of Circulating Extracellular Vesicle Signatures by Rivaroxaban Therapy
    (University College Dublin. School of Biomolecular and Biomedical Science, 2021) ;
    Thrombosis remains a major cause of mortality and morbidity worldwide. Common risk factors include pro-inflammatory conditions, endothelial dysfunction, and aberrant platelet activation, all augmenting the patient’s risk of developing a thrombus. Intriguingly, these risk factors also manifest in increased levels of circulating extracellular vesicles (EVs). EVs are a heterogenous group of membrane vesicles released from all cells. Due to the expression of tissue factor and phospholipids on their surface, EVs can accelerate thrombus formation. To circumvent adverse events in thrombotic disease, pharmacological thromboprophylaxis is frequently indicated. Rivaroxaban, a direct FXa inhibitor, mediates anti-inflammatory and cardiovascular-protective effects besides its well-established anticoagulant properties, however, these remain poorly characterized. Given the prevalent role of EVs in thrombotic diseases, we hypothesized that Rivaroxaban’s anti-inflammatory properties are reflected upon differential molecular profiles of circulating EVs. Here, we used single vesicle analysis and comparative proteomics to, for the first time, characterise small (<200nm) and large (200-1000nm) plasma EVs from patients with non-valvular atrial fibrillation (AF), venous thromboembolism (VTE) and stable cardiovascular disease (CVD) treated with Rivaroxaban compared with cohort-specific controls. We identified profound changes in circulating EV profiles and proteomic signatures that may contribute to Rivaroxaban’s pleiotropic effects. Circulating EV profiles were fundamentally altered across the cohorts analysed. While AF patients displayed profoundly reduced levels of total small EVs, we identified a decrease in the proportion of large EVs between 400-700 nm in VTE patients. Patients with stable CVD, on the other hand, indicated increased small EV mode size with a concomitant increase in the proportion of large EVs between 600-800 nm. Comparative proteomic characterisation of enriched EV fractions revealed differential expression of proteins involved in the regulation of complement activation, vascular integrity, and inflammation, collectively mirroring the reported anti-inflammatory and cardioprotective characteristics associated with Rivaroxaban therapy. In summary, we have determined that circulating EV profiles are powerful surrogate markers of the Rivaroxaban-mediated pleiotropic effects. Regardless of the underlying thrombotic disease, Rivaroxaban appears to confer vascular protective effects in both venous and arterial thrombotic conditions. While several mechanisms, including inhibition of protease activated receptor or NF-¿B signalling, have been proposed to contribute to these vascular protective characteristics mediated by Rivaroxaban, we here provide original evidence that the modulation of circulating EV signatures may pose a distinct mechanism through which Rivaroxaban therapy may elicit such pleiotropic effects, an exciting finding that may be leveraged when planning future studies exploring personalized management strategies, such as identification of those patients most likely to benefit from this therapy, particularly in jurisdictions where access to therapy may be restricted. Alleviating the underlying pro-inflammatory state of patients with thrombosis poses a promising future therapeutic target to avert major adverse thrombotic events. Further investigations into Rivaroxaban-mediated changes in circulating EV signatures may provide a future avenue to open Rivaroxaban’s use for extended patient cohorts, such as rheumatoid arthritis.