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A CFD comparison of interfacial phase change models for boil-off, self-pressurisation and thermal stratification in liquid hydrogen storage tanks
No full textLiquid hydrogen (LH 2) is a promising energy carrier for future clean fuel technologies. However, its cryogenic storage and handling pose significant challenges, particularly due to self-pressurisation and boil-off from ambient heat ingress. Accurate modelling of these phenomena is essential for the safe and efficient design of LH2 storage systems. A key aspect of such modelling is the selection and implementation of an appropriate interfacial phase change model. This study presents a comparative assessment of three widely used phase change models; the Schrage model, the Modified Energy Jump (MeJ) model, and the Lee model. A parametric study was conducted across three coefficients for each model, with validation performed against five experimental benchmark cases from NASA's K-Site and MHTB cryogenic tanks, focusing on planar interface problems with thermally induced phase change under normal gravity. A CFD approach using STAR-CCM+ was employed to evaluate each model's ability to predict tank pressure, temperature, and boil-off behaviour. The Schrage model demonstrated the most robust and accurate results, exhibiting minimal sensitivity to coefficient variation and offering both numerical stability and physical fidelity. It demonstrated a maximum mean absolute percentage error (MAPE) of just 3.0% in its pressurisation predictions. The MeJ model showed comparable accuracy when its heat transfer coefficient was appropriately selected, highlighting its reliance on an empirically derived coefficient. In contrast, the Lee model performed the poorest, exhibiting numerical divergence at high coefficient values and substantial deviation in its prediction of self-pressurisation, with errors of up to 11% MAPE. These findings provide practical guidance for the selection and implementation of phase change models in CFD simulations and highlight key considerations for modelling LH2 storage tanks in industrial applications
Synergy for Poverty Reduction: The Complementary Roles of Microfinance and Agricultural Input Subsidies in Tanzania
Get PDFThis paper investigates how and to what extent state-funded interventions can synergise with non-state programmes to achieve broader welfare effects for households in developing countries. We study two prominent programmes that benefit different groups of low-income households: state-funded agricultural input subsidies (AISs) and microfinance from non-state lenders. We use household data from Tanzania to estimate the effects of AISs and microfinance on the welfare of farmers and examine whether, as complementary, the two programmes benefit different groups of farmers. Using control function and instrumental variable approaches to control for the endogeneity of AISs and microfinance, we find that both programmes are effective in increasing household consumption. Moreover, results show that the two programmes operate in a complementary manner, whereby AISs are effective among low and middle-income farmers but not among well-off farmers. On the contrary, microfinance is effective among well-off farmers but not among low-income farmers
Ranking-based Self-Supervised Representation Learning for Skeleton-based Action Recognition
Get PDFRecently, researchers have achieved significant results in the skeleton-based action recognition. To better model the skeleton sequences, we drive the encoder to learn more discriminative representations in the self-supervised setting. We find that instead of clustering feature vectors to assign pseudo labels for samples as in DeepCluster, ranking them is a more reasonable, reliable, and efficient way to learn more effective feature representations. With this intuition, we propose a novel self-supervised learning framework, DeepRank. Specifically, we rank triplets of skeleton sequences with the ranking labels, obtained from the relative distances among them. Besides, to deeply mine complementary discriminative information that exists in different modalities of skeleton sequences, we further propose Multi-View DeepRank (MV-DeepRank) to enable encoders to comprehensively learn complementary features from multiple modalities. Extensive experimental results on the NTU RGB+D, NTU RGB+D 120, PKU-MMD I, and PKU-MMD II datasets under various evaluation settings demonstrate the generality, transferability, and superiority of our proposed self-supervised learning frameworks. Notably, our frameworks surpass the previous methods that employ the same backbone networks as ours by at least 1.8% (ST-GCN) and 2.1% (STTFormer) under the finetuning setting. Additionally, DeepRank gains a significant advantage on computational complexities, O(1), over the contrastive learning-based methods, O(batchsize), and the clustering-based methods, O(numberofclusters)
Navigating cultural barriers: a qualitative study exploring clinicians’ experiences of providing mental health support for ethnic minority groups in England
Get PDFBackgroundEthnic minority populations are increasing in England, however individuals from ethnic minority backgrounds are less likely to access mental health support compared with their White British counterparts, despite experiencing parallel but also unique risks of developing mental health difficulties. Understanding the barriers for ethnic monitory groups to accessing mental health services is therefore crucial. As clinicians are at the forefront of access to healthcare for all people, their perspectives on how ethnic minority groups are supported with their mental health are underexplored but may illuminate barriers to accessing mental health support. This study aimed to investigate clinicians' experiences in supporting patients from ethnic minority backgrounds with mental health difficulties.MethodFourteen clinicians participated in semi-structured interviews about their experiences of delivering mental healthcare to people from ethnic minority groups. The sample consisted of clinicians specialising in mental health (n=9) and General Practitioners (n=5) with 14.1 mean years of experience. Interviews explored clinicians’ approach to support, confidence when providing care, patient outlook on mental health and treatment, as well as service constraints. Data were analysed using reflexive thematic analysis. ResultsThree main themes were identified: 1) Clinician personal factors impacting their approaches to supporting patients from ethnic minority groups; 2) Clinicians' perspectives on how patients perceive mental health and mental health services; 3) Structural factors and level of training provided affects consultation and treatment. Perceived patient barriers to accessing support included cultural incompatibility, stigma and mistrust. Clinicians discussed the limited time and financial resources of services and how this restricted their capacity to make accommodations. Conclusions This study highlights the importance of a comprehensive, multi-level strategy to overcome barriers to accessing mental health support among ethnic minority groups. Key recommendations include reviewing current training around culturally sensitive care, reforming systemic practices to foster inclusivity, and encouraging community engagement to reduce stigma and build trust in mental health services. Further research should focus on how cultural adaptations to services may improve engagement and explore the impact of intersectionality within and across individual ethnic groups. Such initiatives are crucial for achieving equitable mental health outcomes across diverse populations
Additive manufacturing of PEDOT:PSS anode for biophotovoltaic devices
Get PDFThis work delivers a novel anode for biological photovoltaic systems (BPVs) from inkjet-printed conductive poly (3,4-ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS), achieving improved power density (+97 %). BPVs harness photosynthetic microorganisms to generate electricity, requiring an anode to collect charge from the biofilm. Transparent, conductive, and biocompatible, PEDOT:PSS is an ideal candidate to replace transparent conductive oxide anodes. This is the first report analysing feasibility of additively manufactured PEDOT:PSS anodes for BPVs, using inkjet-printing. A competitive sheet resistance (29.5 Ωsq−1) and optical transparency (≈97 %) were achieved. The biocompatibility of inkjet-printed PEDOT:PSS film surface was confirmed with 50 ± 5.6 % occupancy by Leptolyngbya. The long term stability of inkjet-printed PEDOT:PSS anode was determined after no delamination of inkjet-printed PEDOT:PSS film on plastic substrates after 2 years of immersion in growth medium (Blue Green 11, BG11). However, trade-offs exist between optical transparency, electrical resistance, number of printed layers, formulation, and microbial occupancy. These were evaluated to optimise the performance of the inkjet-printed PEDOT:PSS anodes, outperforming Indium Tin Oxide (ITO)-coated Polyethylene Terephthalate (PET) with 97 % higher power density. This study proposes a new approach to fabricate thin-film anodes with surface texture maximising the surface area for microbial attachment, whilst upholding the same spatial area of the BPV device
Examining Sponge City coverage and perceptions in global news media
Get PDFMany countries are developing sustainable urban water management approaches to tackle the increasing risks of rainstorms due to climate change. As such, in China the Sponge City Program (SCP) was adopted in 2013. To ensure successful adoption, the SCP should incorporate social indicators, such as public perception and uptake. News media is a key channel to relay information to the public, yet the role and influence of media outlets in portraying the SCP have not been investigated. We reviewed 786 online news articles published from 2014 to 2022. Our analysis found alignment between media reports and academic research on high-level SCP functions (mainly urban water management, and its ecological, socio-cultural, and economic co-function) and its challenges (financial constraints, technical difficulties, and governance issues). However, the media often lacked nuance, such as the detailed extent to which SCP can mitigate flooding, which could pose risks for future practices. This study highlights the critical role of online media in shaping public perceptions and influencing decision-making within SCP similar approaches, and the need to understand the complexities of flood processes and SCP to drive policy changes. As the narrative and coverage of such approaches evolve and mature, we recommend greater engagement between academics and the media
The Construction of Epistemic Normativity
Get PDFThis article aims to solve a puzzle for instrumental conceptions of epistemic normativity. The puzzle is this: If the usefulness of epistemic norms explains their normative grip on us, why does it seem improper to violate these norms even when doing so would benefit us? To solve this puzzle, we argue that epistemic instrumentalists must adopt a more social approach to normativity. In particular, they should not account for the nature of epistemic norms by appealing to the goals of individual agents. Rather, they should appeal to norms or rules of inquiry that serve our collective goals. We argue that epistemic normativity grows out of our need to promote a deep kind of coordination in our basic epistemic practices. By subscribing to an appropriate system of norms, we can coordinate epistemic rule-following across the community. This makes testimony more trustworthy and reliable. This account not only solves a puzzle about epistemic instrumentalism but also sheds new light on the foundations of normativity and emphasizes the need for a truly social epistemology
Safety and efficacy of adjunct dexamethasone in adults with herpes simplex virus encephalitis in the UK (DexEnceph): a multicentre, observer-blind, randomised, phase 3, controlled trial
Get PDFBackgroundHerpes simplex virus (HSV) encephalitis is characterised by inflammation and swelling of the brain, resulting in death or severe neurocognitive sequelae. HSV encephalitis is treated with the antiviral aciclovir but still has substantial mortality and morbidity. Adjunct corticosteroids are sometimes used, but whether they improve the outcome is unclear. We aimed to establish the safety and efficacy of adjunct corticosteroids in HSV encephalitis.MethodsIn this multicentre, observer-blind, randomised, phase 3 trial, adults with HSV encephalitis admitted to 53 hospitals in the UK were randomly assigned to receive intravenous dexamethasone (10 mg, four times daily for 4 days) plus intravenous aciclovir (10 mg/kg three times daily for at least 14 days; dexamethasone group), or intravenous aciclovir alone (control group). Eligible patients aged 16 years or older had suspected encephalitis (a febrile illness with new onset seizure, new focal neurological signs or alteration in consciousness, cognition, personality, or behaviour), with positive HSV type 1 or type 2 PCR test in CSF. Participants were randomly assigned by the trial team at the recruiting site, using a secure web-based randomisation programme. The primary outcome was verbal memory score at 26 weeks, measured by the Wechsler Memory Scale (WMS)-IV auditory memory index. Analyses of primary and secondary outcomes were performed according to the modified intention-to-treat principle, and safety analyses were based on whether participants received at least one dose of the study drug. Trial neuropsychologists assessing the primary outcome, and statisticians involved in the study's primary outcome, were masked to treatment group allocation. The trial is registered with the International Standard Randomised Controlled Trial Number Registry, ISRCTN11774734, and EudraCT, EudraCT2016-004835-19, and is completed.FindingsBetween Sept 22, 2016, and Feb 2, 2022, 94 patients with HSV encephalitis were recruited, 47 (20 [43%] female and 27 [57%] male) to the dexamethasone group, and 47 (24 [51%] female and 23 [49%] male) to the control group. Dexamethasone was initiated a median 7 (IQR 4–8) days after hospital admission. Seven patients withdrew consent, and six were lost to follow-up. Thus, 81 were included in the modified intention-to-treat analysis (39 in the treatment group and 42 in the control group). The primary outcome, verbal memory score at 26 weeks, did not differ significantly between the groups (71 [SD 26] in the dexamethasone group, and 69 [SD 25] in the control group; adjusted difference 1·77 [95% CI –9·57 to 13·12; p=0·76). There were 27 adverse events involving 18 (38%) participants in the control group, and 25 adverse events involving 18 (40%) participants in the dexamethasone group. The most common serious adverse events were seizures requiring readmission to hospital (affecting one [2%] patient in the dexamethasone group and one [2%] patient in the control group) and thrombotic events, including deep vein thrombosis (affecting one [2%] patient in the dexamethasone group) and pulmonary embolism (affecting one [2%]patient in the dexamethasone group). There were no treatment-related deaths.InterpretationIn adults with HSV encephalitis, dexamethasone plus aciclovir had a satisfactory safety profile but did not improve verbal memory score compared with aciclovir alone. Given the established role of corticosteroids in other inflammatory encephalitides, our findings suggest that their early use in suspected encephalitis is unlikely to be harmful. Future studies should assess more targeted immunomodulatory approaches in HSV encephalitis
Cost-effectiveness of pramipexole augmentation for acute phase and maintenance therapy of treatment-resistant depression compared to placebo augmentation: economic evaluation of the PAX-D randomised controlled trial
Get PDFBackground: Pramipexole augmentation of antidepressant treatment for treatment-resistant depression (TRD) has been shown to improve symptom burden over 12 weeks but with some adverse effects compared to placebo augmentation. We aimed to evaluate the cost-effectiveness of pramipexole augmentation for TRD. Methods: We conducted an economic evaluation as part of the PAX-D trial over 12 and 48 weeks. Two costing perspectives, National Health Service and Personal Social Services (NHS + PSS) and societal, were adopted. The primary outcome was quality-adjusted life year (QALY) based on the EQ-5D-5L. Secondary outcomes included year of full capability (YFC) based on the ICECAP-A, and capability-weighted life year (CWLY) based on the OxCAP-MH. Incremental cost-effectiveness ratios (ICERs), cost-effectiveness planes and cost-effectiveness acceptability curves were reported alongside sensitivity analyses. The trial was registered with ISCTRN (ISRCTN84666271) and EudraCT (2019-001023-13) and is complete. Findings: From the NHS + PSS perspective, mean incremental cost of pramipexole was £60 (95% CI: −£55, £176) over 12 weeks and £811 (95% CI: £110, £1513) over 48 weeks. The difference in QALY gained was 0.012 (95% CI: 0.003, 0.021) over 12 weeks and 0.090 (95% CI: 0.036, 0.144) over 48 weeks, equivalent to 4 (95% CI: 1, 8) and 33 (95% CI: 13, 52) days in perfect health. The ICER was £5069/QALY (95% CI: −£3642, £35,608) over 12 weeks and £9007/QALY (95% CI: £2,219, £27,258) over 48 weeks, representing over 90% probability of cost-effectiveness at £20,000/QALY threshold. From the societal perspective, pramipexole was on average cost saving and more effective over 48 weeks. Alternative analyses provided consistent conclusions. Interpretation: Pramipexole augmentation for TRD has demonstrated both clinical and cost-effectiveness. Further trials, directly comparing pramipexole to other augmentation strategies, will be useful in determining the position of this repurposed medication in the treatment pathway of depression. Funding: National Institute for Health and Care Research, Efficacy and Mechanism Evaluation Programme
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