62880 research outputs found
Sort by
Analog ensemble forecasts of solar wind parameters: quantification of the predictability and time‐domain spectral performance
Get PDFForecasting multiscale properties of the solar wind is one of the important aspects of space weather prediction as mesoscales, larger than 1 min, can affect the magnetosphere. Amongst forecasting techniques, the analog ensemble (AnEn) method allows the forecast of a quantity from its past behavior, is easy and quick to implement, and results in an ensemble of time series. A comparison of optimal AnEn forecasts of Wind spacecraft observations of near-Earth solar wind properties with the persistence and climatology baselines allows a quantification of the predictability of the magnetic and velocity components and magnitude. The AnEn predictions were found to be as accurate as persistence for short-term forecasts and climatology for long-term ones, and performed better than both baselines for more than 60% of the samples for a particular lead time. Furthermore, using an AnEn instead of the baselines enables prediction of the full spectrum of solar wind fluctuations. However, using the standard averaging method to generate a unique forecast from the AnEn ensemble results in a loss of power in the small-scale fluctuations. To prevent this loss, a new spectral reduction method is proposed and compared to the standard averaging method as well as the synodic recurrence baseline. The AnEn spectral-reduced forecast is shown to be more time-accurate than the synodic baseline and more frequency-accurate than the mean-reduced forecasts. Such a reduced forecast is then confirmed to be useful as a comparative baseline in performance diagnostics of space weather models
Combining spectroelectrochemistry and theory in photo-assisted electrocatalytic carbon dioxide reduction by Group-6 and -7 metal carbonyl complexes
No full textAnthropogenic emissions of CO2 contributing to global warming and their detrimental effects are of
concern for the future. This, in combination with depleted fossil fuel resources have led to
development of recycling and closing the carbon cycle, to provide a sustainable source of chemical
feedstocks and fuels. Transition metal complexes have revealed their potential to catalytically convert
CO2 by electrochemical techniques to desirable products, including CO and formate. Significant
research into the application, catalytic mechanisms and activities, followed by subsequent
optimisation have resulted in a vast collection of viable electrocatalysts. Diversifying the metal centre
and modification of the ligand assembly from the extensive library available, has shown to exhibit
high activities and tuneable selectivities, where the cooperation between the metal(s) and ligands is
necessary to efficiently reduce CO2. During the initial development of this field, expensive scarce
transition metals such as Re, Ru, Os, Rh and Ir were relied on, however in recent years, focus has
shifted to cheaper Earth-abundant transitional metals including Mn, Fe, Ni and Cu. In the wider
community the Group-6 triad (Cr, Mo, W) has received little attention, leading to one of the two main
aims of this Thesis; the investigation of a series of novel complexes and their redox chemistry.
Chapter 1 provides an overview of the field and the challenges faced, as well as the significant
landmarks of promising catalysts explored. Chapter 2, provides an introduction to the experimental
techniques employed in this work. The novel research, introduced in Chapter 3, reports on cyclic
voltammetry (CV) and spectroelectrochemistry (SEC) of a series of complexes; [M(CO)4(6,6’-
dmbpy)] (M = Cr, W; 6,6’-dimethyl-2,2’-bipyridine) and [M(CO)4(tBu-DAB)] (M = Cr, Mo, W; tBu-DAB = 1,4-di-tert-butyl-1,4-diazabuta-1,3-diene). This provided an insight into the contribution of
the metal centre upon the redox pathways and bonding properties. Favouring a low-energy pathway
probed by changes of the electrode and solvent, unlocked generation of the active catalyst at less
negative overpotentials. The combination of a Au cathodic surface and NMP (N-methyl-2-
pyrrolidone) solvent, exhibit synergy by facilitating this lower cathodic route. The synergy between
electrochemistry and photochemistry termed the photo-assisted (PA) technique unlocks the catalyst
close to the first electrochemical reduction, drastically lowering the energy cost required. In the
literature, [Mo(CO)4(6,6’-dmbpy)] was among the first complexes studied by PA; however, this study
applies this method on an entire series of fresh complexes where the metal centre and ligand variation
were examined.
Chapter 4 reveals a pioneering marriage between the established redox-active and photoreactive
Group-7 carbonyl complexes and Room-Temperature Ionic Liquids (RT-ILs), investigated by both
CV and SEC methods. In recent years, the RT-ILs have earned significant interest due to their
promising catalytic abilities while offering a green alternative to traditional volatile organic solvents.
By acting as both a solvent and electrolyte, they can act to lower the overpotential to generate the
active species, as well as heavily influence the cathodic pathway. The cationic component of
[BMIM][OTf] (1-butyl-3-methylimidazolium trifluoromethanesulphonate), fragments can associate
with the parent [M(CO)3(α-diimine)X] (M = Mn, Re) converting to the cationic [M(CO)3(α-diimine)(1-mIm)]+
, lowering the initial reduction energy cost. This dramatic effect inspired the
inclusion of 1-mIm (1-methylimidazole) as a simple additive to standard THF measurements,
providing a median viewpoint between pure organic and RT-IL conditions. In the presence of CO2,
the RT-IL facilitates CO2 reduction by the complex at low overpotentials, but can also independently
reduce CO2 at the necessary potential. In the future, this important approach of combining RT-ILs and
electrocatalysts may aid upcoming investigations.
Chapters 5 and 6 describe the electrochemical and photochemical properties, respectively, of a
representative series of seven [MoII(η3-allyl)(CO)2(NCS)(P∩P)] (P∩P = 1,2-bis(di-R-phosphino)-R’)
complexes. These ligands include incremental changes to the backbone forming 4- to 7-membered
metallocycles as well as variation of the diphosphino substituents introducing both electron-donating
and -withdrawing effects. These compounds were synthesised and characterised, and their cathodic
paths explored by CV and SEC, supported by DFT calculations. The simplified reduction pathway
generates the supposed active 2-electron reduced 5-coordinate [Mo(η3-allyl)(CO)2(P∩P)]–
at the first
reduction wave, via dissociation of NCS– via an ECE mechanism. Interestingly and rather unusually,
these complexes (differently from their α-diimine analogues) exhibit no catalytic activity towards CO2
reduction. Instead, they favour the formation of a dinuclear CO2-bridged adduct. UV photoirradiation
of the parent complex triggers photoisomerisation to a remarkable trans(CO)-[Mo(η3-allyl)(CO)2(NCS)(P∩P)] species that in the absence of excitation, undergoes thermal isomerisation to
regenerate the parent. This new phosphine series serves as an expansion to the collection of studied
Group-6 electrocatalysts of this structure type, from the commonly employed α-diimine ligands, and
although they have preliminarily been found catalytically inactive, they contribute interesting redox
and photochemical behaviour to this field
Can’t count, won’t count! Investigating pre-service teachers’ mathematics anxiety and the extent that a subject knowledge intervention can reduce anxiety in mathematics
Get PDFThe purpose of this study is to seek to understand the effects of mathematics anxiety (MA)
among pre-service teachers in England, exploring how past mathematical experiences and the
educational environment contribute to negative perceptions of mathematics. This is
important as MA can impact negatively on how mathematics is taught and portrayed in
school, which can affect children’s learning and performance (Maloney & Beilock, 2012).
The study also investigates the extent to which a mathematics subject knowledge intervention
could reduce MA while positively enhancing key emotional and cognitive constructs such as
motivation, self-concept, self-efficacy, and mindset, as well as improving participants’
conceptual understanding of mathematics.
MA is a pervasive issue that significantly impacts individuals' engagement with mathematics,
particularly in educational settings (e.g., Hembree, 1990; Boaler, 2016). Framed around
Appraisal theory, the thesis examines the interplay between emotions, self-beliefs, and
mathematical conceptual understanding in shaping pre-service teachers' attitudes and self-appraisals towards mathematics.
The research utilized a pragmatic paradigm, taking a mixed methods approach combining
quantitative and qualitative methods to assess the extent of MA and its relation to the key
cognitive and emotional constructs mentioned above. 31 pre-service teachers from a
university in the south-east of England completed the survey, of which 14 took part in the
interviews and 12 partook in the intervention. Quantitative data (surveys) were analysed
using statistical analysis while the qualitative data (interviews and expressive writing) were
analysed using Thematic analysis to identify key themes.
The main conclusions of the study are that prior experiences with procedural learning
approaches often contribute to the development of MA, as these methods prioritise rote
memorization over deep conceptual understanding. This, in turn, fosters negative emotional
responses and low confidence, leading to negative appraisals of ability in pre-service
teachers. Results also suggest that a mathematics subject knowledge intervention can reduce
MA while positively enhancing emotions, self-appraisals and self-beliefs, while also
highlighting the importance of collaborative learning in positively enhancing a negative
mathematical outlook. Features of the intervention, such as the use of concrete manipulatives,
mathematical tasks grounded in real-life contexts, peer collaboration, and expressive writing,
appeared to support cognitive restructuring and emotional engagement. However, the
findings also indicate that for some individuals whose attitudes and beliefs about mathematics
remained largely unchanged, a preparatory phase focused on fostering emotional safety and
addressing deeper affective barriers may be necessary before such cognitive shifts can take
place.
The research recommends the provision of regular mathematics workshops to enhance pre-service teachers’ mathematical conceptual understanding within a safe learning environment
that promotes collaboration. It also recommends that training opportunities explicitly address
the role of emotion in learning mathematics and explore ways to support emotional readiness
and reappraisal. The findings have broader implications for educational practice and ITT
programme development, particularly in designing interventions that target both cognitive
and emotional dimensions. This thesis contributes to current theories on MA by aligning with
and adding to existing theories by incorporating a broader context in which MA develops and
can be addressed
Knowledge sources for Industry 4.0 technologies in European regions: the role of inward FDIs
Get PDFThis study investigates the extent to which inward innovative FDIs can contribute to European regions’ potential to access external knowledge useful for the development of Industry 4.0 (I4.0) technologies. By contributing to recent research on regional I4.0, we maintain that incoming multinational companies enable regions to access knowledge generated abroad that is usable for local I4.0 inventions. Using citation data about I4.0 patent applications and innovative FDIs, we estimate a gravity model that supports this idea. The knowledge base of I4.0 technologies developed in European NUTS 3 regions positively correlates with innovative inward FDIs. The correlation is driven by both greenfield FDIs and cross-border M&As, with FDIs originating outside Europe providing the greatest contribution to knowledge transfer. The findings are consistent with the relative weakness of Europe in the development of I4.0 technologies and suggest that placed-based FDI policies could help European regions to overcome this gap
Is progression in primary languages possible? Reflections from a large-scale longitudinal research study
Get PDFThe Curriculum and Assessment Review’s Interim Report (CAR, 2025) flagged potential
concerns relating to the efficacy of languages teaching particularly in primary schools. In
response, this paper explores how “substantial progress” (DfE, 2013) in language learning
can be defined in terms of both linguistic and non-linguistic outcomes and discusses recent
research evidence indicating that demonstrable progress in language learning throughout the
four years of learning at primary school is possible. In light of the numerous challenges
primary schools face with implementing the languages curriculum, the key factors (e.g.,
amount and quality of language input, teacher confidence and expertise, continuity across key
stages) which may impact progression are discussed
Generalized global self-optimizing control for chemical processes: part II objective-guided controlled variable learning approach
No full textSelf-optimizing control (SOC) aims to maintain near-optimal process operation by judiciously selecting controlled variables (CVs). In this series of work, the generalized global SOC (g2SOC) approach is proposed, which extends the concept of SOC to the whole operation space and uses general nonlinear functions to design CVs instead of linear combinations. In the first part of this series work, two numerical approaches for g2SOC are proposed: the optimization-based approach and the regression-based approach, based on a theoretical analysis of the existence of perfect self-optimizing CVs. The CVs designed by the former perform better, but are usually infeasible for large-scale problems. In this paper, we propose an algorithm called objective-guided controlled variable learning (OGCVL) that combines the advantages of both and has a better scalability. OGCVL is proposed for efficient CV design that seamlessly integrates symbolic and numerical computation techniques. Finally, the effectiveness of the OGCVL method is verified in two numerical examples. Both examples illustrate show that the OGCVL method is able to achieve good results while maintaining computational efficiency and is also feasible in large-scale problems
The Earth System Grid Federation (ESGF) virtual aggregation (CMIP6 v20240125)
Get PDFThe Earth System Grid Federation (ESGF) holds several petabytes of climate data distributed across millions of files held in data centres worldwide. The processes of obtaining and manipulating the scientific information (climate variables) held in these files are non-trivial. The ESGF Virtual Aggregation is one of several solutions to provide an out-of-the-box aggregated and analysis-ready view of those variables. Here, we discuss the ESGF Virtual Aggregation in the context of the existing infrastructure and some of those other solutions providing analysis-ready data. We describe how it is constructed, how it can be used, and its benefits for model evaluation data analysis tasks, and we provide some performance evaluation. It will be seen that the ESGF Virtual Aggregation provides a sustainable solution to some of the problems encountered in producing analysis-ready data without the cost of data replication to different formats, albeit at the cost of more data movement within the analysis compared to some alternatives. If heavily used, it may also require more ESGF data servers than are currently deployed in data node deployments. The need for such data servers should be a component of ongoing discussions about the future of the ESGF and its constituent core services
Wake characteristics of multiscale buildings in a turbulent boundary layer
Get PDFUrban forms characterised by multi-scale roughness can drastically modify the wind structure within cities affecting both pedestrian comfort and air quality at street level. For simplicity, most urban flow studies focus on cuboid buildings with a single length scale. We consider six forms to assess how additional length scales impact urban flow: two reference cuboid cases (standard and tall) that differ in aspect ratio (mean building height to width), plus two additional fractal iterations of each. The six models have the same mean building width, height, and frontal area but their length scale characteristics differ. These are used in wind tunnel experiments within a deep turbulent boundary layer. The length scale differences are found to affect the drag force exerted by the buildings in a non-negligible way (up to 5% and 13% for standard and tall buildings, respectively). The added length scales also modify the wake lateral spread and intensity of the turbulence fluctuations, with the smaller length scales having the lower (higher) intensity of fluctuations in the near (far) wake. Additionally, the strength of the vortex shedding emanating from the buildings is reduced by introducing systematically smaller length scales. This work suggests that the omission of additional length scales can lead to inaccuracies in drag and wake recovery estimations. The reduction in the intensity of vortex shedding found with each fractal iteration could have engineering applications (e.g. reducing vibration)
Towards developing an operational Indian ocean dipole warning system for Southeast Asia
Get PDFTwo strong positive Indian Ocean Dipole (IOD) events in 2019 and 2023 led to multiple disasters over Southeast Asia, highlighting the need for warnings of IOD events. This paper presents a stock-take of the current criteria for IOD monitoring and prediction and describes the development of an IOD warning system for Southeast Asia. We examined how subjective choices such as observational datasets, baseline periods, and time averaging affect IOD event identification. Our findings indicate that the choice of sea-surface temperature dataset and time averaging (monthly vs. 3-monthly mean) lead to marked differences in the Dipole Mode Index (DMI), the index used for the monitoring and prediction of IOD events, and hence between various centers on IOD state. The southern Maritime Continent can experience the impact of the IOD on rainfall even when the IOD has not met the current operational criterion, suggesting a need for an impact-based threshold for the IOD. We assess the skill of models in capturing the strength and phase of the IOD and report errors in IOD predictions. While most models are skillful in capturing the active phase of the IOD, many models have an overactive IOD strength. Calibration of DMI-based monitoring products is therefore recommended for the most skilful IOD predictions. Finally, we describe an objective standard operating procedure to assist climate forecasters in issuing timely alerts of IOD events
Prevalence and characterisation of antimicrobial resistance, virulence factors and Multilocus Sequence Typing (MLST) of Escherichia coli isolated from broiler caeca
Get PDFThis study was undertaken to determine the effect of bird age and administering either Lactococcus lactis ssp. lactis 1 (LL) or Limosilactobacillus fermentum 1 (LF) in the drinking water on the prevalence of antimicrobial resistance by phenotypic test, multilocus se-quence typing (MLST) and virulence genes of Escherichia coli (E. coli) isolated from broiler caeca by whole-genome sequencing (WGS) analysis. Male (Ross 308) day-old chicks (240) were reared for 28 days. Water was provided either untreated (CON) or with LL (107/mL) or LF (107/mL) via a nipple drinker on three days each week during the starter phase (days 1, 3, 5, 7, 9 and 11 d) in eight replicate pens per treatment, with initially ten chicks per pen. One chick from each pen was sacrificed when LL or LF was added to the water, and again on d 14 and 28. There was no evidence that LL and LF had any effect on the prevalence of antimicrobial resistance and virulence genes in E. coli isolates. The popu-lation density of Lactobacillus sp. and coliforms decreased with age (p < 0.001). The high resistance of E. coli to ampicillin and tetracycline was maintained throughout the life of the broilers. The prevalence of virulence genes was greatest during the starter phase but declined when birds were 28 days of age (p < 0.05). In birds < 14 d of age, E. coli MLST 457, 1640, 1485 and 155 were dominant, and these carried iucD, irp2, astA, iutA and iroN genes. When birds were 28 d of age, MLST 1286, 1112 and 973 predominated, and these carried few virulence genes. This suggests that young birds were more susceptible to putative pathogenic E. coli than older birds. Supporting the development of a healthy microbiome that might control the proliferation of potentially pathogenic E. coli is an area of future research