13506 research outputs found
Sort by
Synthesis, Characterisation and Applications of Zinc-Substituted Zeotypes
Get PDFZincosilicate zeotypes are microporous materials that show interesting properties, particularly suitable for ion exchangin divalent cations and application in Lewis-acid reactions. The synthesis of zincosilicates with the MFI framework type was carried out exploring different methodologies and an ideal synthesis strategy was found, using KOH as the inorganic mineralising agent. Solid state NMR and other spectroscopic characterisation techniques (such as XAS and DRIFTS) revealed the structural features of the synthesised materials and confirmed the hypothesis that the addition of KOH in the synthesis gel would help heal the silanol defect sites in the framework, improving the ion exchange properties of the materials. The zeotypes were used as catalysts in chemical reactions such as methane activation (for its direct conversion into methanol) and the conversion of ethanol to acetaldehyde. For the latter, the zeotype materials showed remarkable results, with high selectivity and productivity of acetaldehyde. This work showed the potential of zincosilicate zeotype in heterogeneous catalysis, thanks to the improvement and optimisation of thei properties during the synthesis stage. Moreover, it paves the way for further studies which will explore the synthesis of zeotypes with different framework types and Lewis acid properties and the potential application in chemical reactions
Characterisation of the bZIP Transcription Factor Hac1 Key Domains in Transcriptional Repression of Early Meiotic Genes
Get PDFIn Saccharomyces cerevisiae, accumulation of unfolded proteins in the endoplasmic reticulum promotes HAC1 mRNA splicing by the transmembrane kinase-endoribonuclease Ire1. Spliced Hac1 consists of 238 amino acids (Hac1i), compared to its unspliced form of 230 amino acids (Hac1u). Hac1i negatively regulates differentiation in response to nitrogen starvation, such as meiosis. Hac1i represses transcription of early meiotic genes (EMGs) under the control of URS1 promoter element. URS1 sites act as repressor sequences during mitosis and function as activator sites during meiosis. Recruitment of Rpd3L histone deacetylase complex by Ume6-Ime1 to URS1 facilitates repression of EMGs by Hac1i in response to nitrogen starvation, interfering with sporulation.
The bZIP transcription factor Hac1i consists of a DNA-binding domain, leucine zipper domain, and a C-terminal transactivation domain. These domains share highly conserved residues with other well studied bZIP transcription factors, such as Gcn4. Here we observe the effect of different Hac1 constructs in regulating EMGs transcription through USR1 in nitrogen sensing. We constructed and characterised Hac1u, and three classes of point mutants in the different domains of the Hac1i transcription factor, Hac1i-N49L mutation in the DNA-binding domain, Hac1i-L67P/L74P/V81P mutants in the leucine zipper, and a S238A mutation in the transactivation domain requirement. Experiments with URS1-lacZ reporter genes demonstrated that Hac1i has higher repression potential than Hac1u and requires its transactivation domain for repression of EMGs in response to nitrogen starvation. Hac1i bZIP mutant residues partially disrupt repression of EMGs transcription by Hac1i; consequently, these point mutations interfere with binding of Hac1 to DNA, dimerisation of Hac1, and transcriptional activation by Hac1. Data from these T4C-URS1-lacZ reporter experiments were confirmed using northern analysis of EMGs such as IME2, HOP1, and SPO13. Further northern analysis eliminated several known constituents of Rpd3L histone deacetylase complex (DEP1, CTI6, RXT2, RXT3, PHO23, SDS3, SAP30), as transcriptional targets of Hac1i. In summary, Hac1i, its bZIP domain key residues, and its transactivation domain are required to repress transcription of EMG via URS1 in response to nutrient sensing. Overall, the findings provided novel insights into how Hac1 represses early meiotic genes via the bZIP characteristics in S. cerevisiae. Future work will investigate and develop methods to screen and identify Hac1i potential targets involved in negatively regulating EMGs in response to nitrogen starvation, and characterisation whether Hac1 inhibits nucleosomal acetylation in the promoters of EMGs
Funny Bones: Ecomorphology of the Bovid Distal Humerus and its Paleontological Implications
Get PDFWhen seeking to understand early human evolution, it is fundamental to understand the ecology of the environment in which those early humans lived. This is an important overlap between the fields of anthropology and palaeontology, and here I take an ecomorphological approach involving the study of variation in bone morphology as a proxy for ecology in bovids. The family Bovidae (Mammalia: Artiodactyla) dominated ecosystems at the time of early human (Homo sapiens) evolution, and continue to in many areas today, as well as frequently having been domesticated throughout human history. For these reasons, bovids provide an excellent study group for this research. The main aim of this project is to develop the bovid distal humerus as an ecological proxy using 3D geometric morphometrics on 116 scans of extant bovid species, representing 11 of the approximately 16 extant bovid tribes, and 40% of known extant species. The humerus is particularly informative due to its extensive roles in weight-bearing and forelimb use. This study focuses on the distal humerus (the elbow articulation) as this section of bone is dense and frequently preserved in the bovid fossil record, and additionally a great many attachment and origin sites for muscles involved in lower forelimb movement are concentrated at the distal humerus. I find evidence that aspects of distal humerus morphology have evolved convergently across bovids, relating to body mass and habitat preference, and that distal humerus morphology can be a proxy to infer such information in bovids. This information can be utilized to understand the ecology of extinct bovids, and in the final part of this project I apply this to the case of the unusual Pleistocene bovid Rusingoryx atopocranion, which is known to have been hunted by early humans. The results indicate that the unusual distal humerus morphology observed in Rusingoryx is directly related to the animal being highly adapted for cursoriality on the hard, flat terrain of the Kenyan shores of Lake Victoria in the Pleistocene
Defending Digitalisation: The Case for Platform-Specific Legislation in the UK
Get PDFThe rise of new technologies has changed the world of work, and the 21st century labour market is one in which new methods of work are emerging all the time. Platform work, attained through the use of online or mobile applications, is one such method.
Platform workers are often classified as self-employed and, therefore, are not afforded any basic labour protections, such as access to minimum wage. They often benefit from some flexibility, yet are still subject to controls enforced by the platforms. Thus, platform workers are stuck in a no-mans-land between classification as independent contractors and having ‘worker’ status. The result for platform workers is that they cannot be sure of their labour rights. This thesis makes the case for the introduction of platform-specific legislation, arguing that this is the only means through which we can clarify the protected status of platform workers, to help them find their way across this no-mans-land.
This thesis is split into four Chapters. First, it will begin by determining the nature of platform work, and why it does not sit neatly into any of the three categories of protected status. Second, there will be detailed analysis of the Uber litigation and, in particular, focus on the decision of the Supreme Court. Whilst this is a welcome decision for the protection of platform workers, it does not clarify their protected status. Third, it will be showed that the current tripartite test to determine protected status, requiring mutuality, personal service and control, is completely unsuited to platform work and is the source of much of the confusion surrounding protected status. Instead, a legislative route must be taken to clarify this. Finally, the thesis shall turn to the form such legislation should take, looking to both California’s Assembly Bill Number 5, and the European Union’s recent proposal for a Directive on improving working conditions in platform work, for inspiration. Ultimately, this thesis aims to suggest a legislative test which would clarify the protected status of platform workers once and for all
Externalism or Bust - Why Internalism is Incapable of Producing Moral Reasons
Get PDFConsider the following two commonly held views in Ethics. Firstly, that for something to be a reason for an agent to act it must be capable of motivating them (‘reasons internalism’). Secondly, that agents have reasons – most obviously moral reasons - to act in at least some ways whatever their motivations may be. These two views would at least appear to be in conflict with each other. Internalists however, maintain that they can be reconciled.
It is argued that, given the nature of moral reasons, no such reconciliation could succeed. The argument is based in part on exploring the different attempts at reconciliation offered by three contemporary philosophers within the internalist tradition – David Gauthier, Mark Schroeder & Christine Korsgaard – each of which is shown to fail. It is then argued that this failure at reconciliation is endemic to internalism; internalism necessarily involves imposing a flawed constraint on what normative reasons can exist, which in practice makes it incompatible with the existence of moral reasons
Learner Profiling: Demographics Identification Based on NLP, Machine Learning, and MOOCs Metadata
Get PDFMassive Open Online Courses (MOOCs) have become universal learning resources, and the COVID- 19 pandemic is rendering these platforms even more necessary. Many types of research are ongoing to improve the learning resources provided to learners via MOOCs. These platforms also bring an incredible diversity of learners in terms of their demographics; thus, much MOOCs research relies on the learners’ demographics data. Traditionally, these data are extracted from pre-course questionnaires that are filled-in by the learners themselves. However, besides introducing potential cognitive overhead (asking learners to fulfil tasks outside of the main purpose of learning), this leads to a clear bias in any research based on these questionnaires. The latter is because only about 10% of the MOOCs learners provide (a given type of) demographics data (with the intersection of all types of demographic data being significantly below 10%), while others do not provide any type of their demographic data. Thus, the population data obtained via questionnaires is not representative of the actual population in the MOOCs. To resolve this issue, a research area called Learner Profiling (LP) is investigated in this thesis. This area naturally extends from a research area called Author Profiling (AP), which aims at identifying traits about authors in different domains. In- stead, LP aims to identify learners’ demographics in the online educational domain. This research specifically focused on identifying the employment status, gender, and academic level of learners in MOOCs. Classifying the employment status of learners was based on the semantic representation of their comments, and comparing the sequential with the parallel ensemble deep learning architecture (Convolutional Neural Networks and Recurrent Neural Networks). This obtained an average high accuracy of 96.3% for the best proposed method; using NLP based approach for balancing the training samples. Additionally, the task of classifying the gender of learners was tackled based on the syntactic knowledge from the learners’ comments. Different tree-structured Long-Short-Term Memory models were compared and, as a result, the researcher proposed a novel version of a bi-directional composition function for existing architectures. In addition, 18 different combinations of word-level encoding and sentence-level encoding functions for this task were compared and evaluated. Based on the results, the novel bi-directional model outperforms all other models and the highest accuracy result among the proposed models is the one based on the combination of Feedforward Neural Network and the Stack-augmented Parser-Interpreter Neural Network (82.60% classification accuracy). Next, the learner’s academic level was identified based on training small size - rich data - i.e. not only textual content (data including learner activity data). The researcher argues here that to classify a learner trait from the sparse textual content, researchers need to use additionally other features stemming from the MOOC platform, such as derived from learners’ actions on that platform. Accordingly, time stamps, quizzes, and discussions were examined, as learners’ behavioural data sources for the classification problem. This novel approach for the task achieves a high accuracy (89% on average), even with a simple classifier, irrespective of data size. To conclude, such classification models as used in this thesis show that they can achieve highly accurate results and that pre-course questionnaires to extract the demographic information with a high cognitive overhead could become obsolete
Physiological and Fitness Profile of Female Lacrosse Athletes
Get PDFLacrosse was a Native Americans game that originated long before it was first documented in the 17th century. Its purpose was not only used for religious, medical, and ceremonial purposes, but for fitness and teaching life lessons. Though the men’s game was developed in the mid 1800s, the first women’s lacrosse game was not played until the late 1800s in St. Andrews Scotland as it had previously been deemed inappropriate and too physically demanding for women. Since its start in 1890, the women’s game has changed dramatically. The modern game of lacrosse is characterized as a highly competitive field-based team sport that implements repeated bouts of sprinting and continuous change of direction. In the last four years, women’s lacrosse has undergone rule changes that have fundamentally changed the way the game is played. As such, the aim of this thesis was to highlight how these rule changes have affected the physiological profile of a female lacrosse athlete and if any positional differences could be determined. Nine female lacrosse athletes from a BUCS premier league team participated in a study that measured anthropometrics (stature, body mass, and sum of 8 skinfold thickness), body composition (FFM, FM and BF%) and a battery of fitness tests used to quantify the key elements of lacrosse: speed (36.6 m sprint), agility (pro- agility test), power (CMJ), and endurance (Yo-Yo IR Test Level 1). The participants in this study were taller, heavier, and had more FFM but a higher BF% compared to previous research on the anthropometric and body composition measures of women’s lacrosse athletes. In the physiological testing, the participants had a faster acceleration (9.1 m sprint), but slower agility (pro-agility test) and less explosive power (CMJ height). These measures could reflect a decreased reliance on the anaerobic ATP-PC system and increased reliance on the aerobic energy system because the recent rule changes. Alternatively, these results could be affirming the importance of maintaining a high FFM, low FM, and therefore lower BF%, and its effect on performance. Because of the uneven distribution of positions among participants, no positional differences could be confirmed. It is of note that the midfielders in this thesis had the best overall performance on the physiological testing battery, which supports previous theories about the position. More research should be completed provide a better understanding of the physiological profile of a female lacrosse athlete as well as if positional differences exist considering the recent rule changes
Network Scale Sediment Transport Modelling with the Perspective of Improved Sediment Connectivity and Delivery: A case of small dam removal.
Get PDFAbstract
Sediment movement from the headwater region (source) to the catchment outlet (sink) constantly transforms the river geomorphology and produces various geomorphic features. The geomorphic diversity in the river supports hydro-morphic sediment conditions that formulate suitable physical habitat for the riverine ecosystem. Water, sediment, and organic matter must flow uninterrupted for a healthy ecosystem. However, humans have raised civil engineering structures on many rivers. River fragmentation (dam/weirs) in the European river has crossed the 630,000 marks, and the projected number is 1 million. Fragmentation restricts the free movement of discharge, sediment, organic matter, and riverine species. The impacts of dams on river geomorphology, discharge and sediments are well documented. At the same time, the declining riverine species trend is a significant cause of concern.
Recent studies revealed a 95% decline since 1970 (in the living planet index). Though, dam removal is gaining momentum to reverse the negative impacts on the riverine ecosystem. Dam removal studies have shown positive outcomes on river geomorphology and ecology. However, it would not be admissible to remove all the obstacles present on the river course; for example, there is a considerable cost involved and the economic benefits offered during the lifespan of a dam. Political will is another obstacle in river restoration projects beyond the cost and benefits analysis of the dams and weirs.
The previous dam removal studies addressed site-specific geomorphological and ecological recovery, though case studies often lack long term monitoring. Thus, a few cases reported no significant differences in the river. Still, the presence of a dam or weirs footprint impacts the upstream and downstream river course, which turns a river's lotic environment into a lentic. In addition, the existence of multiple dams or weirs further deteriorates the river's condition by restricting water and matter movement. Thus, dam or weir removal impact assessment must be studied for the catchment and river network scale.
The current study is applied to the Eamont river catchment (396.2 km2), located in the lake district region, which receives maximum rainfall in the U.K. region. Hard rocks dictate the regional geology, and rivers are confined. Thus, no significant changes in river form have occurred in the Eamont catchment rivers. However, rivers of the Eamont catchment have high stream power and sediment continuity. 2 major and 20 small weirs interrupt the natural sediment transport. Additionally, enormous Ullswater and other lakes provide local sinks in the catchment. The catchment area and the number of obstacles present in the Eamont river catchment offers a suitable catchment setting to address the European river fragmentation case.
Two models and other tools are employed to quantify the impacts of multiple obstacles (dam and wires) on a river network. In hierarchical processes and quantification bases, the tools can be briefly summarised; First, a semi-distributed hydrological model SWAT that has quantified the distributed discharge for 166 reaches, at daily frequency, over 55 years (1960 – 2015). Second, SWAT model calibration and validation in SWAT-CUP, using the SUFI algorithm. Third, the DJI-4 drone's images were captured for gravel bars at low altitudes for higher ground resolution. Forth, the Metashape application processed orthophotos of gravel bars, which are further processed in BASEGRAIN, to perform optical-granulometry and develop grain size distribution at the river network scale. Fifth, integration of hydrologic and grain size distribution information in the CASCADE framework for sediment connectivity, dam and weir removal impact analysis on sediment flux, at the network scale.
The CASCADE framework provided sediment entrainment, transport, and deposition pattern on the Eamont network. The study's key findings have highlighted that the Lowther River contributes more sediment than the Eamont river, despite the high entrainment in the headwater regions. The entrained sediment gets deposited in the Brothers water and Ullswater lake on the Eamont river course. Whilst the Lowther river's significant deposition takes place in Haweswater reservoir. The main reason why Lowther River provide high sediment flux is that it has a high gradient and transport power than Eamont.
Moreover, based on the geomorphological difference between the Eamont river and its tributary Lowther, the presence of multiple weirs with approximately similar sediment trap efficiency, the CASCADE simulation showed higher sediment flux would be released when weir removal activity was performed on the Lowther River.
The current study had presented an opportunity to analyse the multiple river obstacle (dam/ weirs) impacts on sediment flux and sediment connectivity at a network scale. Such an experiment can be applied to formulate the dam removal planning for a complex river catchment. However, future integration of the CASCADE framework with ecological modelling would improve the analysis of riverine ecosystem benefits
Correlation and Development of Fluvial Systems: Implications for three-dimensional Facies Models
Get PDFThe variety of controls on the deposition of fluvial systems, whether autocyclic or allocyclic including tectonic, climatic or eustatic influences, produce complex spatial architectural geometries and facies variations, which are challenging to correlate and predict across sedimentary basins. In extensional basins, tectonic subsidence is the main influence upon generation of accommodation space and the spatial distribution of drainage networks. This is further complicated during marine transgressions when a direct competition exists between tectonism, climate, and sea-level rise producing a complex series of interactions. This is manifested in a change in depositional style such as bed thickness, geometry or grain size changes of a fluvial sequence. Establishing predictive basin-scale models and frameworks linking controls on sedimentation to preserved architecture is vital, especially as fluvial systems are prolific reservoirs for the extraction or injection of fluids and targets for mineral resources globally. The multi-disciplinary and multi-scale approach of this research using sedimentology, chemostratigraphy and statistical-based facies modelling aims to investigate the Triassic syn-rift fluvial architecture in the Central Iberian Basin, north-eastern Spain, to build a correlated, basin-wide depositional model constrained by the main controls on fluvial architectural development. Observations from outcrops are incorporated in fluvial facies models to investigate the three-dimensional facies and fluid flow relationships.
Firstly, on the basin scale, the use of chemostratigraphy identified key horizons independent of fluvial architecture and, in combination with sedimentology, allowed a high-resolution spatial and temporal correlation of Triassic syn-rift fluvial sandstones, identifying a major fluvial system along ~80 km of the rifted basin margin for ~10 Ma. The advance of the Middle Triassic Tethyan marine transgression (0.04–0.02 m/year) is recorded by a transition from a fluvial succession to marginal marine clastic sediments and sabkha evaporites and subsequently widespread thick carbonate deposition infilling the basin and recording the final stage of syn-rift deposition. The nonmarine to marine transition is characterised by significant changes in the fluvial architecture from predominantly braided to meandering and a transition from a tectonically to a climatically driven fluvial system.
Secondly, outcrops of the syn-rift Triassic Upper Buntsandstein fluvial succession revealed three phases of development for the fluvial system. Stage one is dominated by an early ephemeral, sheetflood system comprised of isolated, single-storey laminated sand sheets. Stage two is identified by a distinct basin-wide correlative boundary characterised by changing geochemical sediment composition and sharp transition to multi-storey, braided fluvial systems. Stage three comprises highly amalgamated, multi-storey channels with an increased occurrence of floodplain and paleosols facies. This transition is directly attributed to the rapidly approaching Tethyan marine transgression with the Central Iberian Basin.
Finally, statistically-based facies modelling has been utilized to quantitatively determine relationships between fluvial channel shapes, channel widths, net-to-gross and fluid flow characteristics of the Triassic fluvial succession in the Central Iberian Basin. Using field data sets from outcrops allowed detailed conditioning of statistical models with multi-point statistical simulations producing the most realistic and truthful representation of the fluvial architecture compared to the outcrops. The complexity of the facies models as represented by different channel shapes is in relation to the overall recovery factor, where models built from simple, well-defined channel shapes result in the highest recovery factors. In high net-to-gross systems, as recognised from the models, internal heterogeneities are the main drivers and controls for fluid flow and are best represented utilising process-based models. In contrast, in decreasing net-to-gross fluvial systems, data conditioning becomes more important as sand body external configurations increase their impact on fluid flow behaviour and are best represented using multi-point statistical simulation models.
This research contributes to the understanding of sedimentation in rift basins, the spatial and architectural distribution of fluvial facies and their representations in models as many fluvial successions are targets for carbon capture and hydrogen storage and prime gas reservoirs in north-western Europe
Composing Institutions and Institutionalising Composers: Value and Discipline in Contemporary English University Composition
Get PDFACADEMICS IN the field of composition are under numerous pressures and influences. This thesis is based on extensive interviews with composer-academics and examines the field of university composition as the intersection of art worlds, an academic discipline, and an organisationally managed form or work. In-so-doing, it theorises the particular ways in which the field is formed, maintained, and reformed by social and organisational pressures. This particularly concerns the theorisation of conflict and looks at how contradictions between different pressures have the potential to change the practices of composer-academics.
Two key themes are placed at the centre of this theorisation: the value of authenticity and the discipline of rationalisation. The former attributes legitimacy to composers whose work is seen as autonomous and the latter extends the managerialism of the university organisation through the key rationalising technic of grammatisation. Throughout, these two ideas are in play, at every juncture setting up a tension between freedom and control.
The first part lays out the field by considering its composition and ways in which it may usefully be categorised. Part Two examines the practices of research (composing) and teaching and looks at how the university organisation interacts with these. With organisational rationalism taken as the constant, the ideal typical institutions laid out suggest an affinity for certain forms of experimental composition and a banking approach to teaching. The final part flips this, taking the ideal type of autonomy as the constant and theorising what a university that is not in conflict with this fundamental artistic (and academic) ideal could look like in the form of the ‘Liminal University’
Data sources:
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! 👇