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Identification of new candidate Be/X-ray binary systems in the Small Magellanic Cloud via analysis of S-CUBED source catalog
No full textIt has long been known that a large population of Be/X-ray Binaries (BeXRBs) exists in the Milky Way's neighboring dwarf galaxy, the Small Magellanic Cloud (SMC), due to a recent period of intense star formation. Since 2016, efforts have been made to monitor this population and identify new BeXRBs through the Swift SMC Survey (S-CUBED). S-CUBED's weekly observation cadence has identified many new BeXRBs that exist within the SMC, but evidence suggests that more systems exist that have thusfar escaped detection. A major challenge in identifying new BeXRBs is their transient nature at high-energy wavelengths, which prevents them from being detected via their X-ray emission characteristics when not in outburst. In order to identify sources that may have been missed due to a long period of quiescence, it becomes necessary to devise methods of detection that rely on wavelengths at which BeXRBs are more persistent emitters. In this work, we attempt to use archival analysis of infrared, optical, and ultraviolet observations to identify new candidate BeXRBs that have been overlooked within the S-CUBED source catalog. Using X-ray/optical selection of source properties, unsupervised clustering, SED-fitting to VizieR archival measurements, and ultraviolet light curve analysis, we are able to identify six new candidate BeXRB systems that otherwise would have been missed by automated analysis pipelines. Using these results, we demonstrate the use of ultraviolet through near-infrared observational data in identifying candidate BeXRBs when they cannot be identified using their X-ray emission
A novel dung beetle optimization algorithm based on Lévy flight and triangle walk
No full textThe dung beetle optimization (DBO) algorithm is a meta-heuristic intelligent optimization algorithm with strong search capability and fast convergence speed. With the increasing complexity of engineering optimization problems, the DBO algorithm may get trapped in local optimal solutions during the later stage of optimization. To address this issue, this paper proposes a multi-strategy improved DBO algorithm, namely “Lévy flight triangle walk dung beetle optimization (LTDBO) algorithm”. By introducing Logistic-cubic hybrid mapping to increase the diversity of initial dung beetle populations and adopting foraging strategies based on triangle walks to enhance the randomness of the search phase and strengthen local search capabilities. In addition, we propose a Lévy flight mechanism with nonlinear weight coefficients that effectively balance local and global search capabilities and avoid getting stuck in local optimal solutions. To verify the effectiveness of the LTDBO method, a comparative experimental analysis was conducted on CEC2017 and CEC2022 test suites, comparing it with 9 classic and 5 variants optimization algorithms. The results show that the LTDBO algorithm has higher convergence accuracy and better robustness.</p
Criticality in the evolution of river meanders in the Lower Yellow River in response to anthropogenic-induced hydrological regime shift
No full textTo interpret the planform transition from meandering to straight in depositional river channels, a new approach has recently been proposed, incorporating the channel mobility numbe
Multi-layer vibro-acoustic meta-partitions with embedded Helmholtz resonators
No full textConventional partitions used for sound insulation require additional mass or thickness to improve their low-frequency sound transmission loss performance. This contradicts modern engineering applications, which seek lightweight and compact noise treatment. Acoustic metamaterials, which are usually composed of periodically arranged subwavelength unit cells, have the capabilities to offer extraordinary low-frequency sound insulation while also being lightweight and compact. However, many acoustic metamaterials exhibit only superior performance in a narrow band region compared to a partition constructed from a homogeneous material with equivalent mass, which limits their commercial use. This paper introduces a double-layer meta-partition, consisting of arrays of a new vibro-acoustic metamaterial design. The proposed vibro-acoustic metamaterials contain embedded Helmholtz resonators, thus combining both structural and acoustical resonances to increase the transmission loss at low frequencies without adding mass. Finite-element simulations were carried out to predict the transmission loss performance of the meta-partition and to understand the underlying physics behind the transmission loss peaks and dips. The finite-element simulation results showed that the proposed meta-partition design increased the bandwidth of transmission loss improvement and reduced transmission loss dips caused by partition resonances, such as the mass-air-mass resonance. An experimental proof-of-concept study was performed under impedance tube conditions, testing the proposed metamaterial unit cell samples under different conditions compared to those simulated in the numerical model. Despite different conditions, the experimental results match well with the corresponding simulation results, verifying numerical results for the infinitely large meta-partition
How has COVID-19 affected the working lives, finances, mental and physical health, and lifestyle of a cohort of middle-aged men and women in England?
No full textThis thesis explored the impact of the COVID-19 pandemic on employment circumstances, health, lifestyle and finances among middle-aged people participating in the Health and Employment After Fifty (HEAF) study. Furthermore, it explored how health was affected by changes to their employment precipitated by the pandemic.A range of methodologies were applied, including a systematic review, two cross-sectional on-line surveys, and a qualitative study.In a systematic review we found conclusive evidence that loss of employment precipitated by the pandemic was associated with increased risk or levels of anxiety, although with moderate effects. However, the direction of effect between working from home in lockdown and anxiety was unclear.Quantitative analyses of a large cohort of middle-aged people in England showed that employment circumstances, lifestyle, finances and health changed substantially after the onset of the pandemic. Our data showed clear disparities in how the pandemic affected different sectors of the population. Participants in poorer financial position before the pandemic were more likely to experience worsening of their financial circumstances. Those who transitioned to working from home were more likely to report financial improvements, while all other employment changes were associated with worsening financial circumstances. Additionally, poorer health outcomes were more common among individuals in poorer pre-pandemic health. Compared with participants whose job did not change during the pandemic, those who shifted to home working were more likely to perceive a deterioration in their general health, whereas those who decided to retire were more likely to perceive a deterioration in general and mental health and to experience depression in February 2021. It is important to track the mental and physical health of the general population in the long term, with particular attention given to those who experienced the greatest employment disruptions and showed the least resilience.Finally, interviews with participants who retired since March 2020 showed that, similarly to what was reported pre-pandemic, their decision was influenced by a combination of factors. Certain work-related factors could be targeted to extend working lives and decrease economic inactivity. As postulated by the job demand-control and effort-reward imbalance models, having greater control over work tasks – such as through a flexible job – can mitigate the stress derived from a demanding job and support job retention. Similarly, feeling connected with colleagues and managers and appreciated within the workplace reflects a balance between effort and reward and can contribute to encourage work at older ages
IPEM topical report: results of a 2024 UK survey of artificial intelligence in medical physics and clinical engineering
No full textMedical physics and clinical engineering (MPCE) professionals have a critical role in the safe and effective deployment of artificial intelligence (AI) in healthcare, however their attitudes and opinions towards AI are not well understood. A 2024 survey was launched by the Institute of Physics and Engineering in Medicine to UK MPCE professionals to gather information on the current usage of AI, whether it is believed their role will change, if there is any fear about job replacement, the training being conducted, levels of preparedness, concerns about AI introduction, and barriers to AI deployment. A total of 409 responses were received. It was found that AI is widely used (59% of respondents), with wide disparities between disciplines (radiotherapy 76% compared to clinical engineering 37%). Job losses are predicted by 40% of staff, with junior NHS staff more concerned. Nearly 80% of respondents are investing in their own learning, but only 23% know where to look for training resources. Only 10% of the cohort had some prior AI education. Without prior education on AI, only 13% of respondents feel prepared for AI introduction; but this increases by a factor of three with education. Lack of training and knowledge is the major concern and barrier to AI adoption, while lack of a clear AI governance framework was also frequently cited. This survey provides a snapshot of the current status and attitudes of the UK MPCE workforce towards AI and should be used in guiding future efforts in training and education, addressing discipline disparities and overcoming deployment barriers.</p
Developing magnesium alloys with a combination of strength and ductility based on friction stir-based technologies
No full textMagnesium (Mg) and its alloys are the lightest structural metallic materials. The density of Mg and its alloys is approximately two-thirds of the density of aluminium (Al) alloys and nearly four to five times lighter than steel. Due to the low density and high strength-to-weight ratio, Mg alloys have been used in transportation applications where mass reduction is essential, such as automobiles, aeronautics, and astronautics. The reduction of structural weight can improve the efficiency of fuel usage and produce less emission. However, the high energy cost of Mg production weakens the benefit of less emission by using light-weight Mg alloy structures. Moreover, because of the hexagonal close packed (HCP) crystal structure, Mg alloys often face severe strength-ductility trade-off. As a result, producing Mg alloys with a combination of strength and ductility with lower energy consumption is essential for the development of Mg industry.Friction stir-based technologies are considered promising for the production of Mg alloys with a combination of strength and ductility. As variants developed from friction stir welding (FSW), friction stir based technologies share similar features of the microstructure evolution such as grain refinement, large second phase particle fragmentation, pore closure, etc. The work involved three variants, including stationary shoulder friction stir channelling (SS-FSC, Coreflow®), friction stir processing (FSP), and additive friction stir deposition (AFSD). SS-FSC and FSP were used in combination with spark plasma sintering (SPS) to recycle waste Mg-4Y-3RE (WE43C) scraps, turning them into wires and disks, respectively. AFSD was used to achieve the additive manufacturing (AM) of WE43C. The mechanical stirring and generated friction heat during the processing, and thus dynamic recrystallisation (DRX), especially the continuous dynamic recrystallisation (CDRX) actively participated in the grain evolution. DRX occurred during the fabrication produced refined grains with an average grain size ~1-10 µm in the final products. Besides, the presence of fine thermal stable oxide particles either originated from the oxide film grown during the SPS or in-situ formed during the processing can further assist in controlling the grain size. Due to the mechanical stirring and elevated temperature during the processing, pre-existing second phase particles can be fragmented and partly re-dissolve into the matrix. Pre-existing oxide films, if there were some in the material, can also be fragmented but not re-dissolved. These particles were further redistributed throughout the material. Oxide nanoparticles were also in-situ formed during AFSD and provided extraordinary thermal stability at elevated temperature by pinning the grain boundary migration. Basal texture developed during the deformation. The orientation of the {0001} planes was strongly dependent on the material flow behaviour, which is mainly parallel to the material flow plane. Pores were detected in the material. Pore shape is closely related to the material flow behaviour as they all exhibited flake-like shapes and the thickness were parallel to the normal direction of the material flow plane.Refined grain size provided strengthening effects by the volume increment in grain boundaries, contributing to the strength improvement of the material. For WE43C Mg alloys, when subjected to further ageing treatment at 200 °C, plate-like β1 phase precipitated on {101̅0} planes of α-Mg matrix. These precipitates acted as obstacles to the movement of dislocations and thus increased the strength of the fabricated material. In addition, a quicker ageing response around 30-40 h in these materials was observed, at the cost of a reduction in hardness enhancement. Apart from these factors, pores also played an essential role in the mechanical properties, especially the elongation of the material. FSPed material, where the pore size and fraction were higher than the other two samples, exhibited much lower elongation and even partly failure of the material during tensile tests. Refined grains, weakened gradient basal texture produced by friction stir-based technologies provided the combination of strength and ductility, yet if pores were not well controlled, a significant drop in the ductility could occur.This work explored producing Mg alloy with a good combination of strength and ductility with lower environmental impact using friction stir based technologies. It specifically reveals the effects of processing on the final texture gradient in SS-FSC and the role of oxide formation on the subsequent heat treatment, including the ageing peak shift and strengthening effect, which were not previously investigated in detail
Cultural Strategies Think Kit
No full textThe University of Southampton and Local Government Association have collaborated on developing the recommendations from the Cultural strategies and futures report into an accessible think kit resource pack for creating and sustaining a cultural strategy
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