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Thermomechanical behavior of steel structural configurations subjected to cyclic cryogenic conditions in Martian environment
No full textMars is a potential destination for future human colonization, and the construction of sustainable habitats capable of withstanding its extreme low-temperature fluctuations is critical. Numerical simulations are employed to assess the thermal and mechanical performance of three common extraterrestrial structural configurations — Arch, Dome, and Cylinder — under Martian diurnal temperature fluctuations. The study employs stainless steel as the primary material. Key focus areas include stress concentration, displacement, and fatigue failure in the structures. The key findings are: (1) A 3-meter-thick regolith shielding significantly slows heat conduction, mitigating the impact of extreme temperature fluctuations on the steel structure. A fitted curve demonstrates how the structure gradually reaches thermal equilibrium under sustained temperature cycling, correlating temperature cycles with the minimum surface temperature of the steel structure; (2) The introduction of thermal cycles and internal-external pressure differences leads to changes in structural performance, with the regolith shielding providing the most effective protection for the Cylinder configuration; (3) Expansion and contraction caused by thermal cycles are constrained by the fixed base plate, resulting in structural failure originating from the bottom connections. Comparative analysis reveals that the Dome configuration offers superior load distribution and spatial efficiency, making it optimal for Martian habitats subjected to uniform pressure. The results highlight the thermal responses and fatigue behaviors of different steel structural configurations under Mars's extreme environmental conditions, providing scientific support for the selection and design of Martian habitat structures, offering strategies for optimization in structural design, and contributing to the development of reliable structural solutions for future Mars exploration and human settlement.</p
Generative AI in UK Higher Education: contentions and considerations for policy and practice
No full textFearing the unknown: Exploring risk factors for anxiety in children with nighttime fears.
No full textNighttime fears (NF) commonly occur in children aged 4 - 7 years of age. However, there are cases where fears persist into late childhood, and can impact on daily functioning and sleep behaviour. NF have been associated with symptoms of generalised anxiety, fear, and separation anxiety. Research in anxiety in children has highlighted key risk factors, such as behavioural inhibition and attention control, in the emergence of anxiety disorders in later life. Once factor, fear of the unknown, is a relatively new idea which has limited research into its role in anxiety development. Fear of the unknown is defined as ‘an individual’s dispositional incapacity to endure the aversive response triggered by the perceived absence of salient, key, or sufficient information’ (Carleton, 2016b; p. 31). and has been recognised to be distinctly different that intolerance of uncertainty, another important risk factor for anxiety. The current project investigated the risk factors for anxiety and the impact of nighttime fear (NF) in childhood and later adolescence. Prevalence of NF in children across the ages of 4-12 years concurrently and associations with anxiety and fear were investigated, measuring cognitive risk factors such as attentional control (AC), behavioural inhibition (BI) and fear of the unknown (FOTU). The aim was to understand the emergence and stability of NF in childhood, investigating associations between key variables in the context of risk factors, including child temperamental risk and the presence of fears and phobias in parents, including NF. A systematic review & meta-analysis, a triadic report survey and lab based/online experiment was conducted to further our understanding of risk factors of anxiety, specifically looking children with NF. The overall findings suggest multiple key components to further investigate regarding NF acquisition, as well as better understanding of treatments and interventions as well as a deeper look into the differences between unknowns and uncertainty
Pseudomonas aeruginosa clinical isolates can encode plastic-degrading enzymes that allow survival on plastic and augment biofilm formation
No full textMultiple bacteria encoding plastic-degrading enzymes have been isolated from the environment. Given the widespread use of plastic in healthcare, we hypothesized that bacterial clinical isolates may also degrade plastic. This could render plastic-containing medical devices susceptible to degradation and failure and potentially offer these pathogens a growth-sustaining substrate, enabling them to persist in the hospital-built environment. Here, we mined the genomes of prevalent pathogens and identified several species encoding enzymes with homology to known plastic-degrading enzymes. We identify a clinical isolate of Pseudomonas aeruginosa that encodes an enzyme that enables it to degrade a medically relevant plastic, polycaprolactone (PCL), by 78% in 7 days. Furthermore, this degradation enables the bacterium to utilize PCL as its sole carbon source. We also demonstrate that encoding plastic-degrading enzymes can enhance biofilm formation and pathogenicity. Given the central role of plastic in healthcare, screening nosocomial bacteria for plastic-degrading capacity should be an important future consideration.</p
The geoarchaeology of agricultural terraces in Europe: construction, resilience and implications for sediment delivery
No full textAlthough the primary purpose of agricultural terracing can be assumed to be food production, it has been suggested that a secondary purpose was the control of soil erosion. In this paper, we explore this thesis with multi-proxy data from the TerrACE project, which studied 20 sites in a latitudinal transect across Europe. These sites show that terrace construction was often related to previous slope instability or erosion and that terracing maintained greater soil depths than the surrounding slopes. In some cases, it seems likely that the observation of landsliding that lowered slope angles and produced an accumulation of fractured regolith may have led to opportunistic terracing. The almost universal occurrence of multiple-phase sequences revealed maintenance and re-use that protected buried soil organic carbon. Three case studies show; headwater sediment and carbon retention by terracing, how terracing could be resilient to severe regional environmental events (eruption of Thera) and, lastly, the modelling of failure and sediment supply from vineyard terraces. Although there is no doubt that terracing reduced soil loss from slopes, whether the perception of an erosion risk was part of the conscious reasons for terrace construction is far harder to ascertain, but cross-cultural awareness of these factors does seem to be likely
Effect of channel width on the performance of a modular hall effect thruster operating on xenon, krypton, and argon
No full text‘Follow the Science’: Popular Trust in Scientific Experts During the Coronavirus Pandemic
No full textThe coronavirus pandemic increased the role played by scientific advisers in counselling governments and citizens on issues around public health. This raises questions about how citizens evaluate scientists, and in particular the grounds on which they trust them. Previous studies have identified various factors associated with trust in scientists, although few have systematically explored a range of judgements and their relative effects. This study takes advantage of scientific advisers’ heightened public profile during the pandemic to explore how people’s trust in scientists is shaped by perceptions about their features and traits, along with evaluations of their behaviour and role within the decision-making process. The study also considers people’s trust in politicians, thereby identifying whether trust in scientists reflects similar or distinctive considerations to trust in partisan actors. Data are derived from specially-designed conjoint experiments and surveys of nationally representative samples in Britain and the US
Children’s spaces of belonging in schools: bringing theories and stakeholder perspectives into dialogue
No full textThis paper discusses the question: What is the explanatory power of bringing into dialogue theories of space and place with participatory research approaches that focus on joint perspectives of pupils, teachers and researchers in understanding the dynamics of children’s places of belonging in schools? It advances an argument that understanding children’s spaces of belonging in schools is relatively limited, particularly from a theoretically sophisticated stance or from children’s perspectives. The paper concludes that bringing together concepts of relational space as analytical tools with a participatory approach can create a third space that challenges binary positioning of ‘in/out’ with the potential to act as a safe haven for reflection and growth.</p
Simultaneous wireless power and data transfer system with full-duplex mode based on half-cycle OFDM
No full textA simultaneous wireless power and data transfer system (SWPDT) with full-duplex mode based on half-cycle orthogonal frequency division multiplexing (OFDM) technology is proposed to suppress interference from the power and ipsilateral carriers. The power carrier is regarded as the subcarrier carrying all the “1” data, which is used as the reference frequency, and the data subcarrier frequencies are determined according to the orthogonal properties of the power and data carriers to achieve full-duplex transmission. Demodulation integration cycle is reduced to half of the fundamental wave period, which doubles the data transmission rate. Depending on the proposed OFDM-based modulation and demodulation scheme, there is no need to use additional topologies to suppress interference from the power carrier and crosstalk from ipsilateral data source. In this article, simplified models of power and data transmission channels are developed, analyzed, and optimized to improve the data transmission gain. Finally, a 220 W experimental prototype was built, and tests show that the full-duplex communication rate could reach 170 kbps, which validates the correctness and effectiveness of the proposed SWPDT system
In-situ shear modulus reduction with strain in stiff fissured clays and weathered mudstones
No full textThe non-linear stress-strain behaviour of stiff clays and weak rocks at small and medium strains may be a critical consideration in the design of geotechnical structures. Empirical methods have been developed for estimating the maximum shear modulus and the normalised shear modulus reduction with strain of fine-grained soils. These are usually expressed as functions of the void ratio (or specific volume) and average effective (confining) stress, based on results from laboratory tests. However, the fidelity of these equations has not been widely evaluated in-situ. This paper describes the use of in-situ measurements from an instrumented embankment to calculate the operational in-situ shear modulus of the underlying stiff clays and weathered mudstones at medium and large strains. It is shown that the shear modulus at very small strain of the weathered clays increased linearly with depth, consistent with empirical equations. The gradient of the normalised, non-linear stiffnesses of the clays were comparable with those measured in laboratory tests of fine-grained soils, at a range of strains. However, the values for the reference strain, where the maximum shear modulus reduces by 50%, were lower than was predicted by the empirical equations.<br/
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