Recent results obtained by the PIs show that the advection and refraction of near-inertial waves (NIWs) by mesoscale flow is necessarily accompanied by a transfer of energy from the mesoscale to NIWs: the presence of externally forced NIWs stimulates a loss of energy from the geostrophically and hydrostatically balanced component of the flow. This process, stimulated loss of balance (SLOB), should be contrasted with the much more studied and weaker process known as spontaneous loss of balance. The spontaneous version occurs at order one Rossby number and without externally forced waves. But the stimulated version is active even at small Rossby number and hence, we hypothesize, throughout the ocean. The main objectives of this proposal are to assess and develop the hypothesis that SLOB plays a major role in the mesoscale energy budget, and to investigate SLOB by components of the internal wave spectrum other than NIWs, particularly the internal tide (IT). This will be achieved by the development of new, phase-averaged models coupling the dynamics of internal waves with that of the balanced mesoscale flow, and through numerical solution of both these models and of the three-dimensional Boussinesq equations. The outcome will be a quantitative understanding of the role played by SLOB in the ocean energy budget.

Major progress in science is marked by the bringing into its scope aspects of the world that had previously been considered to be fixed and absolute, but are revealed instead to be dynamical and contingent. Darwin's discovery of the origin of the species by the process of evolution by natural selection is a prime example, as is Einstein's discovery that spacetime itself has its own laws of motion that couple its behaviour to the matter within it. Such discoveries always open the door to further questions -- unthinkable before the shift in world-view -- and in the case of spacetime, we are confronted today with questions of a profound and cosmological nature involving the interaction and ultimate relationship between spacetime and quantum matter. This project will develop new quantum software, namely quantum algorithms, to address fundamental physical questions about quantum field theory (QFT) in the early universe, particle astrophysics and black holes on the assumption that spacetime is, at some level, digital or discrete and also respects Lorentz invariance. The fundamental physics aims of this project are: i) discover the effect of discreteness on perturbations of an interacting quantum scalar field theory such as the inflaton in the early universe and, alternatively, model initial density perturbations arising from pre-Big Bang dynamics of an evolving discrete cosmos; ii) account for the entropy of a black hole by a state counting method where the states are discrete states of the horizon; iii) discover phenomenology of quantum particles of astrophysical or cosmological origin in a digital spacetime background. Heeding the stringent bounds on violation of Lorentz invariance, we will use a discrete dataset that can underpin a continuum spacetime approximation and also be Lorentz invariant. A random, discrete partial order or causal set is such a dataset. Such a mathematical object is difficult to deal with analytically and numerical calculations are crucial for progress, especially for obtaining testable predictions from phenomenological models. The numerical methods, however, also have their limitations since classical algorithms require extensive computational power and time, especially in the phenomenologically relevant case of 4-dimensional spacetime. Our approach is to develop numerical methods for those physical questions, that use quantum algorithms, at least for expensive subroutines, and we will prioritise quantum algorithms that can be implemented on Noisy Intermediate Scale Quantum devices. The techniques we will use include: the variational quantum eigensolver, the quantum approximate optimisation algorithm, quantum annealing and adiabatic quantum computing, as well as quantum walks. The ambition is that these quantum algorithms will offer advantage in comparison with classical numerical methods for these novel investigations of the physics of a digital universe, and be an important tool for investigating and testing further discrete models for fundamental physics in the near-future. These quantum algorithms will first be tested in an emulation environment using High Performance Computing and specifically the Archer2 national leading facility. The effects of noise on the performance will be considered and we will extrapolate to understand the scales on which these algorithms will outperform classical numerical methods. Eventually, we aim to run these quantum algorithms on physical devices -- digital quantum computers -- once our confidence in the potential advantage is founded and access to suitable hardware is obtained. We will seek to obtain such access reaching out to hardware developed within the UK National Quantum Technology Programme: via our committed engagement with the Quantum Computing and Simulation Hub, or by approaching the National Quantum Computing Centre and quantum hardware companies involved in the UK National Quantum Technology Programme, such as Rigetti and IBM.

The majority of plant life in the ocean is made up of tiny microscopic plants, termed 'phytoplankton' because they 'photosynthesise' ('fix' carbon from the upper ocean into their tissues). Because of their need for light, phytoplankton live in the uppermost sunlit layers of the ocean. However, when they die most of their carbon-rich remains sink into the deep ocean, locked away from the upper ocean. Because the upper ocean and atmosphere exchange gases comparatively freely, the intensity of this 'biological pump' of carbon from the upper ocean into the abyss can have a profound impact on levels of carbon dioxide in our atmosphere. One of the main groups of carbon-fixing phytoplankton in our oceans are the diatoms. They are an extremely important part of the carbon cycle because they are responsible for up to 90% of the biological pump-mediated carbon transfer to the abyss. Yet remarkably, in today's oceans they are far from achieving their enormous potential as carbon fixers. This underachievement is largely a consequence of the fact that they build their cell walls from silicic acid, an essential nutrient that has a curious distribution. Owing to peculiarities in ocean circulation patterns, silicic acid in the uppermost sunlit ocean, and hence diatoms too, are almost entirely restricted to the relatively small area of the Southern Ocean around Antarctica. Because the Southern Ocean represents only 17% of the total surface area of our oceans, increasing the supply of silicic acid to lower latitudes has the potential to greatly increase the efficiency of the biological carbon pump, with consequences for atmospheric carbon dioxide. By measuring the composition of ice age atmospheres preserved in tiny gas bubbles within Antarctica and Greenland's ice sheets, scientists know that the ice ages were accompanied by large reductions in atmospheric carbon dioxide levels. It has been hypothesised that one way in which these low levels could have been achieved was increased leakage of silicic acid out of the Southern Ocean and into the much larger area of the lower latitudes, thereby greatly expanding the habitat range of diatoms and fuelling an intensified biological carbon pump. It has recently been discovered that a substantial drop in atmospheric carbon dioxide accompanied the onset of ice age cycles three million years ago. In a similar fashion to the hypothesis for the last ice age, the locus of diatom productivity switched from the restricted Southern Ocean to the more geographically extensive lower latitudes during the onset of the ice ages. Because of their importance in the biological carbon pump, this greatly expanded habitat range of diatoms may have contributed to the observed drop in atmospheric carbon dioxide that was likely responsible for initiating the ice ages. Our proposed work aims to determine the mechanism by which oceanic nutrient distributions were reconfigured to produce this unprecedented proliferation of diatom productivity outside the confines of the Southern Ocean. Specifically, we will test our hypothesis that the primary route by which excess nutrients (especially silicic acid) leaked out of the Southern Ocean to lower latitudes was via shallow sub-surface 'thermocline' waters that originate in the ocean around Antarctica. While these nutrient-rich thermocline waters fuel 75% of total biological productivity in lower latitudes, they are, in the modern ocean, almost devoid of the silicic acid required by diatoms. We will determine the chemistry of thermocline waters across an array of globally distributed sites at lower and higher latitudes. With these new datasets, we will test a number of hypotheses for specific changes in the ocean circulation patterns around Antarctica that may have ultimately driven increased efficiency of the biological carbon pump and thereby contributed to the onset of the ice ages.

Earth's magnetic field is generated almost 3000 km below our feet in the liquid iron core by a process known as the geodynamo. The field protects the surface environment and low-orbiting satellites from solar radiation; its existence for at least the last 3.5 billion years therefore has broad implications for the presence of life and the operation of modern global communications. The standard model describing the origin of the geodynamo posits that the field is maintained by slow cooling of the liquid core below a solid mantle and gradual bottom-up freezing of the solid inner core. This model is no longer tenable following the first calculations of the thermal conductivity of iron alloys at core conditions, which predict rapid cooling, a young inner core and pervasive melting of the lower mantle early in Earth's history. In this scenario it is presently unclear how the geodynamo was powered before the inner core formed some 0.5-1 billion years ago. Recent studies have argued that the ancient core could have crystallized from the top down. The central aim of this joint experimental-theoretical project is to understand if and how top-down crystallization generates magnetic fields and influences the thermochemical evolution of Earth's core. The project consists of two major interlinked components: experiments on core analogues and theoretical models of core evolution. Phase equilibria experiments will be carried out at pressure up to 30 GPa and temperature up to 2200 C in the multi-anvil apparatus at UCSD-SIO using NSF-COMPRES assemblies. We will consider the Fe-S-Mg(-O) and Fe-S-O(-Si) systems, building on our recent experimental work in the Fe-S-O system. Chemical analyses of quenched products will be used to determine the chemistry of phases, the liquidus curve and the eutectic temperature for the investigated systems. Results will be applied to the Earth's pressure and temperature conditions using rigorous thermodynamic extrapolation and will also be directly applicable to small terrestrial planets. In parallel we will develop a new theoretical model that describes the thermal and chemical evolution of two-phase regions at the top of Earth's core using techniques that were recently employed to study the Martian core. The model will predict the properties of the two-phase region and the evolution of the magnetic field, which can be tested using a variety of observations, and will therefore provide a coherent description of Earth's core evolution over the past 3.5 billion years. A novel aspect of this proposal is the constant interactions between experiments and theoretical models. Laboratory-based chemistry will be used to refine the models, and numerical results will then be used to motivate new experiments at specific compositions. The proposed study will significantly improve the current understanding of core crystallization in the Earth and also in other planets such as Mercury and Mars.

The project 'ENG-EPSRC EFRI ELiS: Developing probiotic interventions to reduce the emergence and persistence of pathogens in built environments' is an international, multidisciplinary research project that addresses contemporary agendas towards designing and buildings healthy built environments. The project brings together expertise in microbiology, the built environment, infectious disease and antimicrobial resistance (AMR). The proposal responds to the urgency for improving the health of our built environments using an approach that departs from the modern understanding that healthy environments should be based on fewer microbes. Urbanisation, indoor lifestyles and ingrained antibiotic mentalities are selecting for AMR and there is a risk that the current pandemic exacerbates our overreliance on antibiotic approaches which are driving other unintended, longer term public health problems. This approach considers a more nuanced understanding of microbes that recognises that not all microbes are pathogenic. In this manner, future healthy buildings should aim to discriminate between good and bad microbes and in doing so, find ways that can reduce exposure to harmful microbes but also permit the presence and agency of benign environmental microbes roles that are beneficial for human health and the resilience of buildings and cites. The proposal will develop novel probiotic materials for buildings that contain living strains of B.subtilis, a soil derived bacteria that exhibits mechanisms which can inhibit the growth of drug resistant organisms. In the laboratory, we will engineer these probiotic materials for application in buildings that can demonstrate long term survival and ability to prevent AMR bacteria colonisation on these materials and on other building surfaces. In the workshop we will develop novel bio-fabrication approaches that will allow for these living materials to be manufactured in to a series of 1:1 living building component prototypes. These prototypes which will include floor and wall surfaces, furniture components and building panels and cladding will undergo a longitudinal microbial study in a real world building environment at OME, HBBE at Newcastle University, addressing longer term questions of how to progress this approach for building application.