In the last decade, the web infrastructure has evolved to support on-the-fly access of services provided by different vendors. Potentially, this enables collaborations that are cross-boundary and obey precise non-trivial patterns of conversation. However, today services are still used separately, with little integration and guarantees of safety and quality of service. To enable the digital economy to concretely benefit from service integration and open collaborations among several parties, it is critical to ensure safety guarantees (e.g., deadlock freedom) that encompass whole systems, and not just single services. Moreover, as services are developed separately and composed on-the-fly, verification should be modular. Modularity is supported by existing frameworks based on multiparty session types (MPST), which allow effective static (behavioural) local type-checking of programs against global protocol specifications involving several parties. Unfortunately, the state of the art on session types does not sufficiently address non-functional aspects of program correctness. A quality-aware approach to process engineering is particularly critical, as quality properties may affect the functional behaviour of the overall system. For example, the response time of a remote database may affect the deadlock freedom of complex interactions with several clients. This project will focus on time, which is at the basis of many critical safety and quality properties, as many non-trivial collaborations rely on some notion of deadline or timeout (e.g., the Twitter Streaming API requires clients to "...reconnect no more than twice every four minutes"). The aim of the project is to provide a framework for engineering time-sensitive distributed protocols. Protocols are intended here as ad-hoc, application level, abstract specifications of the interaction patterns that actual distributed implementations should follow. Some examples of protocol are the Post Office Protocol (POP2) or Map-Reduce. The framework we propose will be practical, formally grounded, and support: specification of time-sensitive protocols, their modular implementation as executable programs, and modular automated verification of programs against protocols via type-checking. We will provide two languages, one for the specification and one for the implementation of time-sensitive protocols, and establish their relationship in terms of a verification (i.e., behavioural type-checking) framework based on MPST. Modularity and formality will derive from using MPST. Three open challenges will be addressed, which are critical for the practical applicability of MPST to timed session programming: expressiveness, tractability, and embedding into concrete languages and tools. By expressiveness we mean the ability of the programming primitives to set flexible schedules for the timing of actions and support run-time adjustments (e.g., depending on the actual timing in which actions are executed, or on the run-time system load). This will yield robustness of the overall approach by enabling programs to adapt to unpredicted run-time delays. When verifying programs with such flexible time schedules, tractability will be ensured by combining static and dynamic verification (i.e., via hybrid typing). Hybrid typing of timed interactions is still an unexplored direction, but a promising one in terms of efficiency of verification and robustness. Finally, the programming primitives for timed session programming will be embedded into a mainstream programming language that can be directly used by practitioners. Concretely, we will provide a Java API for time-aware session programming and a hybrid type-checking tool for programs written with this API. This will enable timely assessment of the theory, wide access to the project's results from academics and practitioners, and support impact.

Doping is the incorporation of chosen atomic impurities to make a material behave better or differently. When Shuji Nakamura developed a method of producing electrically conducting GaN by activating magnesium (Mg) atoms, he continued a tradition fundamental to all modern electronic devices. Mg doping of GaN allowed production of p-n junctions for today's ubiquitous 'white' light-emitting diodes (LED) and won Nakamura a share in the 2014 Physics Nobel prize. In the same way, europium (Eu) doping of oxide phosphors provided the necessary red optical emission in the 'fluorescent' lamps of a previous lighting revolution. We now propose to take the science of Eu-doped GaN beyond the limited goal of improving red III-nitride LEDs. We aim to explore the potential of hysteretic photochromic switching (HPS), recently discovered by us in GaN co-doped with Eu and Mg, to form the basis of a new solid state qubit or quantum bit. First trials of rare earth (RE-) doped semiconductors, carried out in the late 1980's, suggested that materials with a wider band gap would show better high-temperature performance, thus favouring II-VI materials and III-nitrides over conventional semiconductors like silicon. However it was not until the present century that III-N semiconductors, grown as high-quality epitaxial thin films on sapphire, were good enough to test this conjecture; another decade passed before Fujiwara demonstrated an LED based on GaN doped with Eu during growth (2010). Extensive comparative studies of Eu doping methods by the proposer and coworkers in the decade 2001-2011 established that, while such thick GaN:Eu samples could produce brighter overall emission, material produced by ion implantation, followed by annealing, was actually more efficient per dopant ion, by up to 400 times at low temperatures. We also showed that the defect responsible for the GaN:Eu red LED emission was the 'prime' defect, Eu2, consisting of an isolated Eu ion on a Ga lattice site. The commoner Eu1 defect has a more complex emission spectrum, suggesting a Eu atom perturbed by a lattice defect, such as a vacancy or interstitial atom. The total number of such complex centres reported in the GaN:Eu literature is larger than 10. While attempting to improve the light emission advantage further by implanting Eu in p-type or n-type GaN templates, we discovered hysteretic photochromic switching (HPS) in GaN(Mg):Eu: p-type, Mg-doped GaN samples implanted with Eu ions and annealed. The HPS shows itself in the temperature dependence of the photoluminescence spectrum. At room temperature, the dominant emission, due to the centre Eu0, shows a sharp line at 619 nm. For comparison, Eu1 has a peak at 622 nm and Eu2 at 621 nm. On cooling the sample, the Eu0 intensity increases, as expected, until about 230 K, when it appears to saturate. Below 30 K, we observe a surprising rapid decline of Eu0 as the temperature decreases towards the base temperature of the cooling system. At the same time, an Eu1-like spectrum emerges and effectively replaces Eu0 at 11 K. We deduce that Eu0 somehow switches to Eu1 on cooling over a narrow temperature range. This switching does not reverse if the temperature is then increased from 11 K through 30 K. In fact, Eu1 fades rather slowly, allowing Eu0 to reappear only above ~ 100 K; this is hysteresis. Sample emission is maximum at about 200 K and then fades, reversibly, between 230 K and room temperature. The occurrence of photochromic switching near 20 K on cooldown followed by luminescence hysteresis on warming is given the acronym HPS (hysteretic photochromic switching). The surprises continue: for samples cooled in the dark, switching from Eu0 to Eu1 can be seen in the time domain; and a resonance line appears at an intermediate wavelength between Eu0 and Eu1. The proposed project aims to determine if the resonance is an actual superposition of Eu0 and Eu1, promising a novel and simple solid state qubit based on Mg acceptor defects.

Volcanic eruptions that form lava domes pose a significant hazard, as they tend to last for extended periods of time (often weeks to months) and can often switch quickly from slow effusion to violent explosion. The start of a new lava dome eruption offers a rare opportunity to carry out a rapid study to understand where the new lavas came from; and to test ideas about how the eruption will progress. On December 27, 2020, a new lava dome eruption began in the summit crater of the Eastern Caribbean volcano of La Soufriere, on the island of St Vincent, after a short period of unusual seismic activity. The new lava dome has been growing steadily, erupting on to the floor of the summit crater, next to an old lava dome that erupted in 1979. Scientists at the University of the West Indies Seismic Research Centre (SRC) have been monitoring events, and collected some new lava samples on January 16, 2021. St Vincent had two previous lava-dome eruptions in the 1970s. In 1971-2, a lava-dome formed in the summit crater, which at that time was flooded. After 3-4 months of slow dome growth the eruption ended, and there was no explosive activity. Scientists collected one lava dome sample at the time, and a piece of this is now held in the Smithsonian Institution in the USA. In 1979, a new eruption began with a series of violent explosions, and then switched to a steady lava-dome eruption for the next 5 months. Our rapid-response study of the newly-erupting lavas on St Vincent will answer the question of where the new magma has come from. There are several possibilities that we anticipate, and our observations will allow us to work out which possibility is the most likely: - Is this a new batch of magma, which has just risen up into the volcano? And if so, can we understand why? - Is this a batch of magma that was left over from an earlier eruption, which has been disturbed, and has begun to erupt as a result? And if so, can we understand how the system was disturbed? In both cases, our findings will feed directly into the continuing investigations by the scientific team in charge of the volcano response, and will help to develop and firm up ideas about what will happen next in the eruption.

Geological dykes - sheets of rock that are often oriented vertically or steeply inclined to the bedding of preexisting rocks - typically intrude because stresses either 1) overcome rock strength or 2) exploit existing fractures created by preceding tectonic activity. Normally, it is impossible to tell these two possibilities apart because intrusion occurs along the rift zone - i.e., in the same direction as the faults within the rift. More generally, it is also poorly known how many types of fractures increase in size to form larger faults for similar reasons. Some existing mechanical models can explain how the displacements of faults scales with their length. However, they leave open questions of how fractures not showing such scaling develop. The role of pre-existing fractures in creating pathways for dyke propagation could be important for guiding the propagation. This potential "irrationality" of dyke intrusion is crucial for interpreting the nature (and source) of intense earthquake crises in volcanic systems, and ultimately for managing volcanic crises when knowledge of potential eruption sites would otherwise be an asset. For instance, if dykes are shown to preferentially follow pre-existing structural weaknesses, then detailed mapping of faults could provide important constraints for volcano eruption hazard maps and scenario-planning. An exciting opportunity to tackle this outstanding scientific problem is now presented by a rare, intense earthquake crisis in one of the most geometrically extreme, fissure-fed volcanoes on Earth, the volcanic ridge of São Jorge Island (Azores), which contains faults oblique to the rift zone. Starting on 19 March 2022, the region's seismicity levels raised extraordinarily from only 5 earthquakes recorded in 01/01-18/03, to over 27,000 M 2-3.3 events recorded from March 19th until now. Unfortunately, current earthquake locations are substantially uncertain because of geometric limitations of the existing seismic network, which includes only seismic stations in the islands. These uncertainties prevent us from relating the earthquakes to known faults and volcanic centres. Further, the limited data coverage and quality of existing networks have hindered the construction of detailed 3-D seismic tomography images of the region, with only 1-D velocity models being available based on land data. In order to address these issues, we propose to deploy a temporary seismic network of five ocean bottom seismometers (OBSs) around São Jorge and ten land broadband (BB) stations on São Jorge and surrounding islands. This will substantially enhance the region's seismic data coverage, leading to an unprecedented dataset: (1) showing how seismicity associated with a dyke intrusion relates to known faults; and (2) enabling the construction of the first detailed 3-D subsurface images of the crust and of the volcanic edifice in this rare example of a dyke in an environment with faults oblique to the rift zone. More generally, this project will bring key new insights into the structure and plumbing network of tall and narrow fissure-fed volcanic systems such as São Jorge. It will also shed new light on the mechanics of dyke intrusions and their kinematic evolution in general.

The vision of this Fellowship proposal is to provide a unique capacity internationally, where proteins, metabolites and trace elements can be imaged and co-located at the sub-micron scale, under ambient pressure. This is not available using any other technique and will provide significant benefits to researchers in industry and academia studying the fluxes of metabolites, proteins and other biomarkers in tissues and cells. The Fellowship will develop a new emerging world leader and provide training to a team of researchers in this new field. The vision will be achieved by developing a novel toolbox for molecular speciation, to be used alongside ion beam analysis (IBA). The Fellowship will tackle this challenge with three interconnecting work packages, each investigating a different approach to augmenting the molecular speciation that can be provided alongside or with IBA techniques. These approaches can be summarised as follows: 1. Multimodal mass spectrometry and ion beam trace element imaging; 2. Microscale (point) protein and metabolite characterisation alongside ion beam trace element imaging; 3. Multiplexed ion beam imaging of biomolecules and proteins using antibody-lanthanide tags. This will provide a step change in the UK's capability in the characterisation of biological materials. This proposal will enhance the >£10M investment that EPSRC has recently made in renewing the UK National Ion Beam Centre (UKNIBC) contract and investment in associated equipment (EP/P001440/1; EP/I036516/1), ensure continuing provision of cutting-edge capability in the UK and provide enhanced capabilities at the UKNIBC. It will also ensure the primary benefits go to the needs of UK industry and academia and support the development of applications across RCUK priority areas, with significant economic and societal benefits.