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The ventilation of buildings and other mitigating measures for COVID-19: A focus on wintertime
No full textThe year 2020 has seen the emergence of a global pandemic as a result of the disease COVID-19. This report reviews knowledge of the transmission of COVID-19 indoors, examines the evidence for mitigating measures, and considers the implications for wintertime with a focus on ventilation
Physical effects of water droplets interacting with turbulent premixed flames: A Direct Numerical Simulation analysis
No full textThree-dimensional carrier-phase Direct Numerical Simulations (DNS), combined with a Lagrangian representation of individual droplets, have been employed in this parametric study to examine the physical effects of liquid water mist interacting with laminar and turbulent premixed stoichiometric n-heptane air flames. Significant reductions of flame temperature and burning velocity have been observed in the presence of water droplets. In agreement with the laws governing evaporation, a strongly non-linear influence of the droplet size on the overall burning rate has been noted, whereas the influence of water loading is fairly linear. Different regimes of droplet-flame interaction are known to exist and this has been investigated by numerical experiments focusing on the influence of the latent heat of vaporization. When using realistic fluid properties of water, the cooling effect due to the enthalpy sink of evaporating droplets outweighs the dilution effect due to the local release of steam. Under turbulent conditions, the effectiveness of the droplets in reducing the overall burning rate changes owing to the transient nature of the droplet-flame interaction. Furthermore, it was found that the evaporating droplets significantly diminish the flame-generated turbulence and this leads to weaker turbulent wrinkling of the flame surface as compared to gaseous premixed reference simulations without droplets. Based on a comparison of the time scales representing droplet evaporation and the droplet residence time within the flame, a reduced-order model is proposed to account for both the cooling and dilution effects with respect to flame temperature and laminar burning velocity
A review on self-healing polymers for soft robotics
No full textThe intrinsic compliance of soft robots provides safety, a natural adaptation to its environment, allows to absorb shocks, and protects them against mechanical impacts. However, a literature study shows that the soft polymers used for their construction are susceptible to various types of damage, including fatigue, overloads, interfacial debonding, and cuts, tears and perforations by sharp objects. An economic and ecological solution is to construct future soft robotic systems out of self-healing polymers, incorporating the ability to heal damage. This review paper proposes criteria to evaluate the potential of a self-healing polymer to be used in soft robotic applications. Based on these soft robotics requirements and on defined performance parameters of the materials, linked to the mechanical and healing properties, the different types of self-healing polymers already available in literature are critically assessed and compared. In addition to a description of the state of the art on self-healing soft robotics, the paper discusses the driving forces and limitations to spur the interdisciplinary combination between self-healing polymer science and soft robotics
The role of reversible and irreversible covalent chemistry in targeted protein degradation
No full textProteolysis-targeting chimeras (PROTACs) that degrade disease-causing proteins by hijacking the endogenous ubiquitin-proteasome system have emerged as an exciting and transformative technology in both chemical biology and drug discovery. Currently, the majority of PROTACs use reversible non-covalent ligands for both the target protein of interest (POI) and E3 ligase. In this review, we explore the burgeoning role of reversible and irreversible covalent chemistry in targeted protein degradation. We highlight the key advantages of targeted covalent inhibitors, whether as the target POI or E3 ligase ligand, such as their ability to enhance the selectivity of PROTACs, enable access to more of the “undruggable” proteome and expand the repertoire of recruited E3 ligases
Qualitative research methods in neurosurgery: an unexplored avenue.
No full textOBJECTIVE: Explore the value and potential of qualitative research to neurosurgery and provide insight and understanding to this underused methodology. BACKGROUND: The definition of qualitative research is critically discussed and the heterogeneity within this field of inquiry explored. The value of qualitative research to the field of neurosurgery is articulated through its contribution to understanding complex clinical problems. DISCUSSION: To resolve some of the misunderstanding of qualitative research, this paper discusses research design choices. We explore approaches that use qualitative techniques but are not, necessarily, situated within a qualitative paradigm in addition to how qualitative research philosophy aids researchers to conduct interpretive inquiry that can reveal more than simply what was said by participants. Common research designs associated with qualitative inquiry are introduced, and how complex analysis may contribute more in-depth insights is explained. Approaches to quality are discussed briefly to support improvements in qualitative methods and qualitative manuscripts. Finally, we consider the future of qualitative research in neurosurgery, and suggest how to move forward in the qualitative neurosurgical evidence base. CONCLUSION: There is enormous potential for qualitative research to contribute to the advancement of person-centred care within neurosurgery. There are signs that more qualitative research is being conducted and that neurosurgical journals are increasingly open to this methodology. While studies that do not engage fully within the qualitative paradigm can make important contributions to the evidence base, due regard should be given to immersive inquiry within qualitative paradigms to allow complex, in-depth, investigations of the human experience
Distributed dynamic fibre-optic strain monitoring of the behaviour of a skewed masonry arch railway bridge
No full textSkewed masonry arch railway bridges are common, yet their structural behaviour under typical working loads, along with gradual changes in behaviour due to degradation, can be difficult to determine. This paper aims to address this problem through detailed monitoring of a damaged, skewed masonry arch railway bridge in the UK, which was recently repaired. A comprehensive Structural Health Monitoring system was installed, including an array of fibre-optic Fibre Bragg Grating (FBG) sensors to provide distributed sensing data across a large portion of the bridge. This FBG monitoring data is used, in this paper, to investigate the typical dynamic structural response of the skewed bridge in detail, and to quantify the sensitivity of this response to a range of variables. It is observed that the dynamic bridge response is sensitive to the time of day, which is a proxy for passenger loading, to the train speed, and to temperature. It is also observed that the sensitivity of the response to these variables can be local, in that the response can differ throughout the bridge and be affected by existing local damage. Identifying these trends is important to distinguish additional damage from other effects. The results are also used to evaluate some typical assumptions regarding bridge behaviour, which may be of interest to asset engineers working with skewed masonry arch bridges
Technology or behaviour? Balanced disruption in the race to net zero emissions
No full textDelivering net zero emissions requires changing patterns of energy generation, consumption and land use. Mitigation efforts so far have mostly focused on reducing the emissions intensity of energy. Future decarbonisation must look outside the energy sector to disrupt markets, infrastructure, systems and behaviour. This study quantifies the disruption to technological markets and individual behaviours embodied in possible decarbonisation pathways for the United Kingdom. We review 12 strategies for decarbonisation proposed by a range of sources, including public and industry bodies, academic organisations and advocacy groups. The broad scope of perspectives yields a large set of possible mitigation options. A novel metric captures the embedded disruption across dual axes of technological and behavioural change. We find a distinct bias towards technological disruption through the pursuit of fast deployment and speculative technologies. Behavioural mitigation remains undervalued. The predominance of supply-side decarbonisation in global climate discourse means that a technological bias, illustrated here for the UK, is seen in mitigation strategies across the world. Historical evidence shows that technological diffusion takes decades, especially in energy markets, while behaviour change can be swifter. A technological bias reduces the likelihood of achieving net zero global emissions in time to limit global warming to 2 °C. To win the race against climate change, governments should rebalance policy efforts and spending across technological and behavioural options for mitigation
In Situ Observation of Low-Power Nano-Synaptic Response in Graphene Oxide Using Conductive Atomic Force Microscopy.
No full textMultiple studies have reported the observation of electro-synaptic response in different metal/insulator/metal devices. However, most of them analyzed large (>1 µm2 ) devices that do not meet the integration density required by industry (1010 devices/mm2 ). Some studies emploied a scanning tunneling microscope (STM) to explore nano-synaptic response in different materials, but in this setup there is a nanogap between the insulator and one of the metallic electrodes (i.e., the STM tip), not present in real devices. Here, it is demonstrated how to use conductive atomic force microscopy to explore the presence and quality of nano-synaptic response in confined areas <50 nm2 . Graphene oxide (GO) is selected due to its easy fabrication. Metal/GO/metal nano-synapses exhibit potentiation and paired pulse facilitation with low write current levels <1 µA (i.e., power consumption ≈3 µW), controllable excitatory post-synaptic currents, and long-term potentiation and depression. The results provide a new method to explore nano-synaptic plasticity at the nanoscale, and point to GO as an important candidate for the fabrication of ultrasmall (<50 nm2 ) electronic synapses fulfilling the integration density requirements of neuromorphic systems
Designing a High-Performance Boundary Element Library with OpenCL and Numba
No full textThe Bempp boundary element library is a well-known library for the simulation of a range of electrostatic, acoustic, and electromagnetic problems in homogeneous bounded and unbounded domains. It originally started as a traditional C++ library with a Python interface. Over the last two years, we have completely redesigned Bempp as a native Python library, called Bempp-cl, that provides computational backends for OpenCL (using PyOpenCL) and Numba. The OpenCL backend implements kernels for GPUs and CPUs with SIMD optimization. In this article, we discuss the design of Bempp-cl, provide performance comparisons on different compute devices, and discuss the advantages and disadvantages of OpenCL as compared to Numba
Investigating dynamic interconnections between organic farming adoption and freshwater sustainability
No full textAs freshwater overexploitation in agriculture is rising, the application of alternative farming practices, particularly in water-scarce areas, is critical for the sustainability of the sector. Organic agriculture constitutes an opportunity for freshwater conservation, further improving biodiversity and human health. Notwithstanding literature efforts on the driving factors of organic farming and the impact of the latter on freshwater resources, a dynamic investigation of the interconnections between organic farming diffusion and freshwater sustainability is lacking. This research adopts a systems thinking perspective on the transition from conventional to organic agriculture. The developed system dynamics model explores the feedback mechanisms underpinning organic farming adoption and freshwater use by integrating, for the first time, the effects of: (i) farmers' water-related environmental and economic awareness patterns; and (ii) policy incentives and word of mouth about organic production benefits. The model is validated and tested based on a real-world wine grapes' case. The simulation outcomes highlight that the growers' intense environmental awareness could accelerate organic farming adoption, further promoting freshwater sustainability in case organic agriculture operations generate considerably low freshwater consumption coefficients. Overall, the proposed modelling framework is anticipated to act as a strategic tool for informing policy-makers about the system's state over time to plan potential interventions towards water-friendly organic farming