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Continual learning in sensor-based human activity recognition with dynamic mixture of experts
Get PDFFunding: This work is funded by Leverhulme Research Project Grant RPG-2021-355 in the UK.Human activity recognition (HAR) is a key enabler for many applications in healthcare, factory automation, and smart home. It detects and predicts human behaviours or daily activities via a range of wearable sensors or ambient sensors embedded in an environment. As more and more HAR applications are deployed in the real-world environments, there is a pressing need for the ability of continually and incrementally learning new activities over time without retraining the HAR model. Recently, various continual learning techniques have been applied to HAR; however, most of them commit to a large architecture, which might not suit to devices that deploy HAR models. In addition, these techniques often require to deploy the same large architecture on the devices and cannot customise the architecture for different requirements. To tackle this challenge, we present a dynamic mixture-of-experts approach, which grows an expert for each new task and allows flexible composition of experts to suit individual needs of applications. We have empirically evaluated our technique on 4 third-party, publicly available datasets and compared with 11 state-of-the-art continual learning techniques. Our results demonstrate that our technique can achieve better or comparable performance but with much less parameter spaces and training time.Peer reviewe
Kronecker classes, normal coverings and chief factors of groups
Get PDFFunding: The first and third authors are funded by the European Union via the Next Generation EU (Mission 4 Component 1 CUP B53D23009410006, PRIN 2022, 2022PSTWLB, Group Theory and Applications). The second author is an EPSRC Postdoctoral Fellow (EP/X011879/1).For a group G, a subgroup U ≤ G and a group A such that Inn(G) ≤ A ≤ Aut(G) , we say that U is an A-covering group of G if G = ∪a∈AUa. A theorem of Jordan (1872), implies that if G is a finite group, A = Inn(G) and U is an A-covering group of G, then U = G. Motivated by a question concerning Kronecker classes of field extensions, Neumann and Praeger (1990) conjectured that, more generally, there is an integer function ƒ such that if G is a finite group and U is an A-covering subgroup of G, then |G : U| ≤ ƒ(|A : Inn(G)|). A key piece of evidence for this conjecture is a theorem of Praeger [‘Kronecker classes of fields and covering subgroups of finite groups’, J. Aust. Math. Soc. 57 (1994), 17–34], which asserts that there is a two-variable integer function g such that if G is a finite group and U is an A-covering subgroup of G, then |G : U| ≤ g(|A : Inn(G)|,c), where c is the number of A-chief factors of G. Unfortunately, the proof of this theorem contains an error. In this paper, using a different argument, we give a correct proof of the theorem.Peer reviewe
The impact of gendered socialisation and gender equality on psychological traits
Get PDFConsiderable debate exists about the causes of psychological gender differences and the effects of gendered socialisation and other societal factors. The aim of this PhD project was to investigate the impact of gendered socialisation and gender equality on psychological gender differences using both primary and secondary datasets. Chapter 1 provides a broad overview of the relevant academic literature. In Chapter 2, I have presented a meta-analysis on the correlation between national levels of gender equality and the gender gap in children’s mathematics performance, finding no significant overall correlation and thus no support for the existence of a ‘gender equality paradox’ in this area. In Chapter 3, I then investigated whether individual-level factors could be contributing to gender differences by conducting a study on the relationship between gender, feelings of imposterism, self-efficacy and belonging in a sample of university students. I found that women on average experienced higher levels of imposterism, which was linked to low levels of self-efficacy, but not to feelings of belonging. In Chapter 4, I examined the relationship between adult gender division and gendered childhood socialisation in non-industrialised societies using existing ethnographic data, finding that higher adult gender division correlated with larger gender differences in how much adults try to instil different traits in boys and girls. Finally, in Chapter 5, I conducted a study employing a priming paradigm, gathering empirical data on the potential effects priming participants about levels of gender equality on their romantic partner preferences. I found a significant relationship between partner preferences and self-reported feminist attitudes but not an effect of the priming material. The results of this thesis indicate that while socialisation and gender equality do seem to impact gender differences, their effects are not always consistent or straightforward
Motivations in transition : destination choices of inter-provincial migration among Chinese older adults
Get PDFFunding: This research was funded by the National Social Science Foundation of China (21ZDA067 & 21BRK029) and National Natural Science Foundation of China (42001161).Despite the growing interest in the migration of older adults in China, the intricacies linking migration motivations with destination choices remain insufficiently explored. Drawing from China’s unique context, we categorize inter-provincial older migrants into three types: employment-led, dependent, and lifestyle. Using microdata from the Sixth Population Census of 2010 and the 1% Population Sampling Survey of 2015, we examine their evolving motivations and corresponding shifts in destination preferences. The analysis shows an increase in lifestyle-oriented migration and a decrease in dependent migration, while employment-led migration has remained stable relative to the total. Older migrants seeking employment tend to favor destinations further south, prioritizing regional economic conditions. In contrast, those motivated by lifestyle factors exhibit a broader range of destination choices, largely due to their preference for amenities. Dependent older adult migrants consider both job-related and amenity-related factors and demonstrate a stronger tendency to relocate to the east. Amenity-related factors have increasingly influenced the destination choices across all three types of migration over time. Our findings provide deeper insights into the intricacies of migration in old adulthood and highlight the need for tailored policymaking.Peer reviewe
Evaluation of multi-resonant thermally activated delayed fluorescence emitters as photocatalysts
No full textThis thesis explores different classes of multi-resonant thermally activated delayed fluorescence (MR-TADF) compounds as photocatalysts (PCs) in photoinduced electron (PET) and photoinduced energy transfer (PEnT) reactions. The main objective is to expand on the existing library of MR-TADF PCs to cover a broader range of ground- and excited-state redox potentials and to access higher triplet energies than the current initial reported examples.
Chapter 1 introduces photophysical and photochemical processes that take place in photocatalytic reactions. Different PC design strategies are presented and the concept of TADF is elucidated. Relevant examples of literature PCs and photocatalytic reactions are discussed.
Chapter 2 studies four B/N doped MR-TADF emitters in their performance in PET and PEnT reactions. The influence of the structural changes between them on the ground- and excited-state redox potentials is investigated. The photocatalysts are employed in four model reactions and compared to literature reference PCs. Mechanistic studies and photostability tests explore their applicability in these reactions.
Chapter 3 investigates four DiICz-based MR-TADF PCs as sensitizers in PEnT reactions. Two novel MR-TADF compounds were designed and a complete photophysical analysis is presented. In five different PEnT reactions, the influence of the singlet-triplet energy gap on the reaction progression and oxygen sensitivity is studied. The findings are compared to literature reference PCs.
Chapter 4 presents three B/O doped MR-TADF compounds as PCs in PET and PEnT reactions. The optoelectronic properties are presented. These compounds are assessed in three photocatalysis reactions and their performance correlated to their structure."This work was supported by the European Union H2020 research and innovation program for the funding under the Marie S. Curie Grant agreement (PhotoReAct, no. 956324)"--Fundin
Phase diagram of CeRh2As2 for out-of-plane magnetic field
Get PDFFunding: This work is supported by the joint Agence National de la Recherche and Deutsche Forschungsgemeinschaft (DFG) program Fermi-NESt through Grant No. GE602/4-1 (C.G. and E.H.). Additionally, E.H. acknowledges funding by the DFG through CRC1143 (Project No. 247310070) and the Würzburg-Dresden Cluster of Excellence on Complexity and Topology in Quantum Matter—ct.qmat (EXC 2147, Project ID 390858490). This work is supported by the ERC grant (Ixtreme, GA 101125759). S.K. was supported by the Max Planck Society and the DFG—KH 387/1-1. A.R. and M.P. were supported by the Engineering and Physical Sciences Research Council (Grants No. EP/P024564/1, No. EP/V049410/1, and No. EP/L015110/1). M.P. acknowledges financial support by the International Max Planck Research School for Chemistry and Physics of Quantum Materials.The heavy-fermion superconductor (SC) CeRh2As2 (c = 0.35 K) shows two SC phases SC1 and SC2 when a magnetic field is applied parallel to the axis of the tetragonal unit cell. All experiments to date have indicated that the change in SC order parameter detected at 0* ≈ 4T is due to strong Rashba spin-orbit coupling at the Ce sites caused by the locally noncentrosymmetric environments of the otherwise globally centrosymmetric crystalline structure. Another phase (phase I) exists in this material below 0 = 0.54 K. In a previous specific heat study [K. Semeniuk et al., Phys. Rev. B 107, L220504 (2023)], we have shown that phase I persists up to a field 00 ≈ 6T, larger than *. From thermodynamic arguments, we expected the phase-I boundary line to cross phase SC2 at a tetracritical point. However, we could not find any signature of the phase-I line inside the SC2 phase and speculated that this was because the 0() line is almost perpendicular to the axis and therefore invisible to -dependent measurements. This would imply a weak competition between the two order parameters. Here, we report magnetic-field-dependent measurements of the magnetostriction and ac susceptibility on high-quality single crystals. We see clear evidence of the singularity at 0 inside the SC2 phase and confirm our previous prediction. Furthermore, we observe the transition across the *() line in -dependent specific heat measurements, which show that the *() line is not perpendicular to the field axis but has a positive slope. Our findings support recent muon spin resonance results which suggest coexistence of phase I with SC.Peer reviewe
Time to invest in cholera
Get PDFFunding: This work was supported by NIHR and Wellcome.The recent surge in cholera cases globally calls for urgent evaluation of current approaches to prevention and control of the disease. Malawi was one of the worst affected countries in 2022-2023 with the highest number of deaths due to cholera in the world. In this personal view, we look at Malawi as a case example to illustrate how current approaches lack sufficient investment. We review the history of cholera in Malawi and compare previous outbreaks to the 2022/23 outbreak. We discuss contributing factors to the outbreak including a lack of investment in water, sanitation and hygiene (both historically and currently), human resource constraints, and the market structures which make accessing oral cholera vaccine challenging both in the midst of an ongoing outbreak and as a preventative approach. We call for international action to address the economic and structural challenges underlying cholera persistence and propose solutions to prevent future epidemics and to eliminate cholera as a public health threat.Peer reviewe
The role of Kenyan courts in tackling persistent inequalities : navigating deference and accountability
Get PDFKenya’s 2010 Constitution represents a landmark shift towards equality, incorporating diverse conceptions through provisions such as Article 27 on non-discrimination, Article 43 on socio-economic rights, and Article 56 on cultural and religious diversity. This progressive framework seeks to address historical inequalities that marginalized groups—such as women, persons with disabilities, and minorities—have faced in accessing resources, services, and political participation. However, implementation remains the critical determinant of whether these constitutional ideals translate into tangible societal change. This Article examines the role of the judiciary as a constitutional guardian in ensuring the realization of equality-related rights in Kenya’s hybrid democracy, characterized by democratic aspirations alongside authoritarian tendencies. It highlights the judiciary’s dual responsibility to balance deference to State organs with holding them accountable to constitutional mandates. By analyzing key cases, it identifies how courts have navigated tensions between promoting substantive equality and respecting the separation of powers, especially in the context of socio-economic rights and governance challenges. The Article advocates for an equality-sensitive approach to judicial review that integrates both strong-form and soft-form oversight, depending on the case’s circumstances. It emphasizes the application of a contextual and multi-dimensional equality framework—addressing redistribution, recognition, participation, and transformation—to ensure that vulnerable groups are protected. In addition, it proposes a mixed standard of review in socio-economic rights cases, balancing reasonableness with prioritization of the needs of vulnerable groups, and the use of structural interdicts to enforce compliance. Finally, this Article emphasizes the judiciary’s pivotal role in fostering constitutionalism and mitigating systemic inequalities. It calls for continued judicial vigilance, collaborative constitutionalism, and active civil society engagement to uphold the transformative promise of the 2010 Constitution, particularly in Kenya’s complex hybrid democracy.Peer reviewe
Investigating and manipulating electronic transport properties of intercalated transition metal dichalcogenides
No full textThis thesis explores the electronic transport properties of devices based on two-dimensional transition metal dichalcogenides. By developing and optimising fabrication techniques, effective strategies were established for measuring these layered-structure devices, laying the groundwork for examining their unique electronic properties. This work focuses on how changes in external conditions, such as temperature, magnetic field, and electrostatic environment, alter the electronic transport behaviour of the materials and what these changes reveal about the observed phenomena. The main results are detailed in two chapters, each dedicated to a different structure. The first experimental chapter explores the concurrence of Kondo behaviour and magnetic ordering in the intercalated transition metal dichalcogenide AgCrSe₂. Transport measurements across varying temperatures and magnetic fields revealed an unusual upturn in the low-temperature resistivity behaviour, suggesting the single-ion Kondo effect as its origin. By applying Schlottmann’s theoretical framework, it was found that the Kondo temperature and the Néel temperature coincide, indicating a unique correlation. This leads to a new understanding of how magnetic ordering can enable Kondo hybridisation, contrary to the conventional view that magnetic order competes with Kondo scattering. These insights underscore the significance of studying such layered structures, where ionically conductive sheets are intercalated within transition metal planes making exceptional platforms for examining correlated effects and unconventional electronic and magnetic phenomena. The second experimental chapter focuses on the alternately stacked transition metal dichalcogenide 4HbTaS₂. Electrical transport measurements, such as the angular dependence of the upper critical field and the behaviour of the critical current, revealed the 2D nature of superconductivity in this material. Furthermore, ionic liquid gating measurements unveiled a switching effect between resistivity states and suppressed superconductivity under gating. These findings highlight the potential of layered heterostructures to exhibit unique and unconventional electronic transport properties arising from the electronic properties of constituent layers
Examining airlines' environmental and social disclosure : does board gender diversity matter?
Get PDFThis study investigates the influence of board gender diversity (BGD) on environmental and social disclosure (ESD) within the airline industry, an area that remains underexplored despite increasing stakeholder scrutiny. We apply automated textual analysis to annual reports of Skytrax's top global airlines from 2016 to 2022 to measure the extent of ESD and examine its association with female board representation. The results show a positive and significant relationship between BGD and ESD, with a critical mass of at least four female directors required to drive meaningful improvements in disclosure practices. These findings extend the predictions of gender socialization theory (GST) and critical mass theory (CMT) and offer practical implications for policymakers and airline managers, including the adoption of diversity quotas and leadership development initiatives to enhance corporate transparency and accountability.Peer reviewe
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