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Properties of moduli spaces of supersymmetric quiver gauge theories with 8 supercharges
No full textThe thesis focuses on the study of moduli spaces of 3d N = 4 supersymmetric field theories.
Two aspects are emphasized. Firstly, discrete quotients of the Coulomb branch are studied.
Secondly, the Hasse diagram for Higgs branches are studied. Both aspects are given by
diagrammatic operations on the quiver diagrams.
In the Introduction and Background part, the framework of supersymmetry and the nec
essary mathematics underlying the following two chapters are introduced at a pedagogical
level.
In the second part, it is shown that two families of quivers, the quivers with complete
graphs and the quivers with multiple adjoint loops, have Coulomb branches related by
a quotient of a permutation symmetry. Quotient of cyclic groups is also studied. The
two operations can be combined to generate a quotient by a semi-direct product group of
permutation and cyclic groups. The quotient relations are demonstrated by the Molien
sum and Abelionization process. Examples are included to demonstrate the operations.
In the third part, a bottom to up quiver subtraction algorithm is introduced. The algorithm
can generate the whole Hasse diagram for the Higgs branch of a single-laced unitary quiver.
The interesting feature of the algorithm is that it gives the monodromy of slices around
the leaves. It also calculates the Namikawa Weyl group.Open Acces
Concentration without complexity: enhancing stationary photoelectrochemical reactor performance with diffuse light concentrating optics
No full textPreprint versio
International Institute for Sustainable Development (IISD) SDG Knowledge Hub - Maximising Emerging Trends in Locally-Led AI Solutions for Climate Action
No full textTo unlock the full potential of AI within the Network, the CTCN can deepen its collaboration with NDEs, grounding AI solutions in strategic priorities and research agendas.
Sharing practical use cases that demonstrate how AI addresses climate challenges will help countries strengthen the effectiveness and impact of climate technology implementation
Research Computing Engagement: a skill for many, a job for few
No full textResearch or advanced computing services at universities are growing and expanding in scale and complexity and it is becoming increasingly important to engage users effectively so that the services are designed and run with them, not just for them. In many institutions this work is done by people whose job titles vary widely – or for whom “engagement’ is only one part of a much broader role – yet the underlying skills and competencies are remarkably similar and increasingly essential.
Since taking on a dedicated Research Engagement Lead role, I have connected with colleagues throughout the research computing network; Infrastructure Engineers, Research Software Engineers (RSE), data science support, library and digital scholarship teams, and other digital Research Technical Professional (dRTP) roles. Across these communities, core engagement competencies repeatedly emerge: active listening and translation between researcher and technical perspectives; community-building and facilitation; understanding research workflows and pain points; strategic communication; and the ability to influence infrastructure and service decisions without always having formal authority.
This talk will use examples from my time at Imperial College London and discussions with colleagues in other institutions to illustrate how these skills are applied in practice – from “light-touch” activities such as newsletters and drop-in sessions, through to deeper collaborations that shape the design and adoption of new computing systems. Rather than focusing on specific technologies, it will emphasise the transferable capabilities that underpin effective engagement, and how these can be developed and recognised within institutions.
By framing research computing engagement as a cross-cutting skill set, rather than a narrowly defined job, the talk aims to offer practical insights for the HPC-SIG community: how to identify and support staff already doing this work, how to embed engagement into technical projects, and how community-focused practice can contribute to sustainability, responsible use of resources, and more impactful digital research infrastructure
Renewal theory for Brownian motion across a stochastically gated interface
No full textStochastically gated interfaces play an important role in a variety of cellular transport processes,
including diffusion through membrane ion channels and intercellular gap junctions. Most stud ies of stochastically-gated interfaces are based on macroscopic models that track the particle
concentration averaged with respect to different realisations of the gate dynamics. In this paper
we develop a novel probabilistic model of single-particle Brownian motion (BM) through a
stochastically gated interface. We proceed by constructing a renewal equation for one-dimensional
BM with an interface at the origin, which effectively sews together a sequence of BMs on the half line with a totally absorbing boundary at x = 0. Each time the particle is absorbed, the stochastic
process is immediately restarted according to the following rule: if the gate is closed then BM
restarts on the same side of the interface, whereas if the gate is open then BM restarts on either
side of the interface with equal probability. In order to ensure that diffusion restarts in a state that
avoids immediate re-absorption. we assume that whenever the particle reaches the interface it is
instantaneously shifted a distance ϵ from the origin. We explicitly solve the renewal equation for
ϵ > 0 and show how the solution of a corresponding forward Kolmogorov equation is recovered in
the limit ϵ → 0. However, the renewal equation provides a more general mathematical framework
for modelling a stochastically gated interface by explicitly separating the first passage time problem
of detecting the gated interface (absorption) and the subsequent rule for restarting BM. We illus trate this by calculating the non-equilibrium stationary state across an interface in the presence of
stochastic resetting. We conclude by discussing some of the mathematical challenges in extending
the theory to higher-dimensional interface
Burned area mapping across the Arctic-boreal zone with Landsat and Sentinel-2 imagery
No full textWildfires in the Arctic-boreal zone have increased in frequency over recent decades, carrying substantial ecological, social, and economic consequences. Remote sensing is crucial for mapping burned areas, monitoring wildfire dynamics, and evaluating their impacts. However, existing high-latitude burned area products suffer from significant discrepancies, particularly in Siberia, and their coarse spatial resolutions limit accuracy and utility. To address these gaps, we developed a convolutional neural network model to map burned areas at a 30 m resolution across the Arctic- boreal zone using Landsat and Sentinel-2 imagery. Using vegetation indices including the normalized burn ratio, normalized difference vegetation index, and normalized difference infrared index our model achieved strong performance, with an Intersection Over Union (IOU) of 0.77 and an F1 score of 0.85 on unseen test data. Performance was higher in North America (IOU = 0.84) than in Eurasia (IOU = 0.72), reflecting regional differences in fire regimes and data quality. Predictions for six representative years showed our model’s burned area closely matched the median values of Landsat, MODIS, and VIIRS-based products, although alignment varied annually and spatially. Visual assessments indicated our approach was generally more accurate, notably in detecting unburned vegetation islands within fire perimeters missed by other products. This research has numerous potential applications, such as analysing feedback between vegetation and burn patterns, characterizing spatial dynamics of unburned islands, and improving carbon emission estimates through detailed burn severity assessments
Variation of instability characteristics and resulting electron transport under external modulation in E×B plasmas
No full textCross-field electron transport in partially magnetized plasmas arises from collective, nonlinear instability dynamics that remain only partially understood despite their importance to a wide range of E×B plasma devices. In systems such as Hall thrusters, azimuthal instabilities strongly affect electron confinement and spectral energy distribution, motivating efforts to examine how external modulation may influence these effects. Here, one- and two-dimensional particle-in-cell simulations are employed to investigate how an axially applied oscillatory electric field modifies the instability spectra and the associated cross-field electron transport. The simulations adopt local slab idealizations of an E×B discharge designed to isolate modulation-instability coupling mechanisms, and the conclusions should be interpreted within this controlled modelling framework. The simulations show that the plasma response depends sensitively on modulation frequency and amplitude. Notably, modulation near 40 MHz diminishes the amplitude of the electron cyclotron drift instability and reduces axial electron transport by up to 30%, while modulation near the electron cyclotron frequency leads to spectral broadening and enhanced transport. Bicoherence analysis of the azimuthal electric field fluctuations indicates nonlinear coupling among instability modes, suggesting that modulation reshapes energy pathways, thereby explaining the observed spectral variations. We further show that modulation modifies the phase alignment between azimuthal-electric-field and electron-density fluctuations, in turn directly affecting the observed suppression or amplification of electron transport across modulation regimes. The results provide quantitative evidence of how external modulation can alter instability characteristics in E×B plasmas and point to strategies for controlling electron transport in cross-field plasma technologies, such as Hall thrusters and magnetrons
Using regression and XGBoost analysis to explore expertise related to united nations sustainable development goals and research impact metrics among nursing faculty: a retrospective cross-sectional machine learning study
No full textBackground
The United Nations Sustainable Development Goals (SDGs) offer a comprehensive global framework for promoting health, equity and sustainability. Whereas alignment with the SDGs is increasingly encouraged in academic institutions, the extent to which faculty
expertise in SDGs influences traditional research impact metrics remains insufficiently explored.
Objective
To investigate the relationship between nursing faculty expertise in SDGs and research
impact metrics.
Methods
A retrospective cross-sectional design was employed using data from 121 nursing faculty members at Mahidol University, Thailand. Information on SDG-related expertise and research performance was obtained from the Mahidol University Research Excellence Database (MUREX) and Scopus. Descriptive statistics, Pearson’s correlation, and multiple linear regression analyses were used to examine associations between SDG expertise, academic experience, and research impact metrics, including H-index, citation count, and research output. Extreme Gradient Boosting (XGBoost) and Synthetic Minority Over-sampling Technique (SMOTE) were applied to improve predictive modelling and address class imbalance.
Results
Faculty members with greater expertise in SDGs demonstrated significantly higher research impact metrics. SDG expertise significantly predicted H-Index (β=0.65, p<0.001), total citations (β=31.77, p=0.004), and total research output (β=2.41, p<0.001). Research experience was also a significant predictor of research impact. XGBoost outperformed traditional regression models, identifying SDG expertise and international collaboration as the strongest predictors of research impact. Faculty aligned with SDG13 (Climate Action) had a high percentage of top-cited publications, suggesting
an intersection between research visibility and global sustainability priorities. Certain SDGs (e.g., SDG12: Responsible Consumption and SDG15: Life on Land) were
underrepresented, indicating potential gaps in nursing research.
Conclusion
SDG expertise is a key determinant of academic impact, reinforcing the need for greater institutional support for SDG-aligned research. Findings suggest that interdisciplinary collaboration and engagement with broader sustainability challenges may enhance faculty research visibility. Future research should explore longitudinal trends and policy implications for integrating SDGs into faculty assessment frameworks
From defect to design feature: optimising LB-PBF-induced porosity for altering tribological behaviours of cocrmo surfaces for orthopaedic applications
No full textAdditive manufacturing has expanded the design possibilities for orthopaedic implants, enabling complex geometries and patient-specific customisation that are difficult to achieve with conventional manufacturing. Among these techniques, Laser Beam Powder Bed Fusion (LB-PBF) has been widely adopted for processing metals. Cobalt-chromium-molybdenum (CoCrMo) alloys have been the standard bearing material in many designs of artificial hip joints for their high mechanical strength and wear resistance. Despite extensive work on LB-PBF mechanical properties and on the tribology of conventionally manufactured CoCrMo, the tribology of LB-PBF CoCrMo remains not well understood. Porosity is an intrinsic feature of LB-PBF, arising from the interaction of process parameters and thermal histories. In the context of articulating surfaces, LB-PBF process-induced pores represent a microstructural feature whose effects on tribological performances have yet to be fully defined. Understanding whether such features behave as defects to be eliminated or as functional surface textures with potential performance benefits requires a combined additive manufacturing-tribology approach. This thesis addresses this gap by progressing from elucidating fundamental process-structure relationships, through assessing tribological behaviours of LB-PBF CoCrMo, to demonstrating the feasibility of manufacturing bearing surfaces with spatially tailored porosity. The results demonstrate that LB-PBF process-induced porosity in CoCrMo can be systematically controlled through the combined effects of process parameters, enabling porosity levels ranging from near-dense to highly porous. Tribological evaluation showed that the effects of porosity are strongly affected by lubrication conditions: under protein-rich lubrication, friction and wear performance depend on the porosity level, whereas under water lubrication, higher porosity led to increased friction and apparent wear volume loss. The fabrication and testing of hybrid bearing surfaces with locally engineered porosity revealed that spatial porosity contrasts introduced additional complexity and increased frictional variability and wear. The outcomes provide a foundation for optimising LB-PBF processing strategies and exploring new design approaches for orthopaedic implants.Open Acces
Toward the crystallographic and microstructural mechanisms of plant leaf waxes as diffusion barriers
No full textWaxes within the leaf cuticle, the outermost layer of the plant leaf, play a defining role as a transpiration barrier and also serve as an important target for agrochemical interventions for crop protection. A prevailing model for this behaviour is the role of wax ‘bricks’ in building the diffusion barrier. This review brings together crystallographic and microstructural research to highlight the variety of crystalline, disordered, and amorphous structural features known in waxes. We trace two predominant research routes applied to leaf waxes: one directed at simplified waxes but with highly detailed descriptions of molecular packing and a second focused on the diffusion characteristics of the complex system of the cuticle and its multicomponent wax compositions. Bringing these routes together will develop sufficiently complex but tractable structural models for waxes, often dominated by a single or a few components in common crop plants. A complete description of leaf wax function will enable ways to control diffusion through the development of targeted interventions for drought tolerance