• Canada
• 2021-2021close
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Following the polar amplification of global warming in recent decades, we have witnessed unprecedented changes in the coverage and seasonality of Arctic sea ice, enhanced freshwater storage within the Arctic seas, and greater nutrient demand from pelagic primary producers as the annual duration of open-ocean increases. These processes have the potential to change the phenology, species composition, productivity, and nutritional value of Arctic sea ice algal blooms, with far-reaching implications for trophic functioning and carbon cycling in the marine system. As the environmental conditions of the Arctic continue to change, the habitat for ice algae will become increasingly disrupted. Ice algal blooms, which are predominantly species of diatom, provide a concentrated food source for aquatic grazers while phytoplankton growth in the water column is limited, and can contribute up to half of annual Arctic marine primary production. Conventionally ice algae have been studied as a single community, without discriminating between individual species. However, the composition of species can vary widely between regions, and over the course of the spring, as a function of local environmental forcing. Consequently, current approaches for estimating Arctic-wide marine productivity and predicting the impact of climate warming on ice algal communities are likely inaccurate because they overlook the autecological (species-specific) responses of sea ice algae to changing ice habitat conditions. Diatom-ARCTIC will mark a new chapter in the study of sea ice algae and their production in the Arctic. Our project goes beyond others by integrating the results derived from field observations of community composition, and innovative laboratory experiments targeted at single-species of ice algae, directly into a predictive biogeochemical model. The use of a Remotely-Operated Vehicle during in situ field sampling gives us a unique opportunity to examine the spatio-temporal environmental controls on algal speciation in natural sea ice. Diatom-ARCTIC field observations will steer laboratory experiments to identify photophysiological responses of individual diatom species over a range of key growth conditions: light, salinity and nutrient availability. Additional experiments will characterise algal lipid composition as a function of growth conditions - quantifying food resource quality as a function of species composition. Furthermore, novel analytical tools, such as gas chromatography mass spectrometry and compound specific isotope analysis will be combined to better catalogue the types of lipid present in ice algae. Field and laboratory results will then be incorporated into the state-of-the-art BFM-SI biogeochemical model for ice algae, to enable accurate simulations of gross and net production in sea ice based on directly observed autecological responses. The model will be used to characterise algal productivity in different sea ice growth habitats present in the contemporary Arctic. By applying future climate scenarios to the model, we will also forecast ice algal productivity over the coming decades as sea ice habitats transform in an evolving Arctic. Our project targets a major research gap in Phase I of the CAO programme: the specific contribution of sea ice habitats to ecosystem structure and biogeochemical functioning within the Arctic Ocean. In doing so, Diatom-ARCTIC brings together and links the activities of ARCTIC-Prize and DIAPOD, while further building new collaborations between UK and German partners leading up to the 2019/20 MOSAiC campaign.

Modern society faces a fundamental problem: the reliability of complex, evolving software systems on which it critically depends cannot be guaranteed by the established, non-mathematical techniques, such as informal prose specification and ad-hoc testing. Modern companies are moving fast, leaving little time for code analysis and testing; concurrent and distributed programs cannot be adequately assessed via traditional testing methods; users of mobile applications neglect to apply software fixes; and malicious users increasingly exploit programming errors, causing major security disruptions. Trustworthy, reliable software is becoming harder to achieve, whilst new business and cyber-security challenges make it of escalating importance. Developers cope with complexity using abstraction: the breaking up of systems into components and layers connected via software interfaces. These interfaces are described using specifications: for example, documentation in English; test suites with varying degrees of rigour; static typing embedded in programming languages; and formal specifications written in various logics. In computer science, despite widespread agreement on the importance of abstraction, specifications are often seen as an afterthought and a hindrance to software development, and are rarely justified. Formal specification as part of the industrial software design process is in its infancy. My over-arching research vision is to bring scientific, mathematical method to the specification and verification of modern software systems. A fundamental unifying theme of my current work is my unique emphasis on what it means for a formal specification to be appropriate for the task in hand, properly evaluated and useful for real-world applications. Specifications should be validated, with proper evidence that they describe what they should. This validation can come in many forms, from formal verification through systematic testing to precise argumentation that a formal specification accurately captures an English standard. Specifications should be useful, identifying compositional building blocks that are intuitive and helpful to clients both now and in future. Specifications should be just right, providing a clear logical boundary between implementations and client programs. VeTSpec has four related objectives, exploring different strengths of program specification, real-world program library specification and mechanised language specification, in each case determining what it means for the specification to be appropriate, properly evaluated and useful for real-world applications. Objective A: Tractable reasoning about concurrency and distribution is a long-standing, difficult problem. I will develop the fundamental theory for the verified specification of concurrent programs and distributed systems, focussing on safety properties for programs based on primitive atomic commands, safety properties for programs based on more complex atomic transactions used in software transactional memory and distributed databases, and progress properties. Objective B: JavaScript is the most widespread dynamic language, used by 94.8% of websites. Its dynamic nature and complex semantics make it a difficult target for verified specification. I will develop logic-based analysis tools for the specification, verification and testing of JavaScript programs, intertwining theoretical results with properly engineered tool development. Objective C: The mechanised specification of real-world programming languages is well-established. Such specifications are difficult to maintain and their use is not fully explored. I will provide a maintainable mechanised specification of Javascript, together with systematic test generation from this specification. Objective D: I will explore fundamental, conceptual questions associated with the ambitious VeTSpec goal to bring scientific, mathematical method to the specification of modern software systems.

Many applications of THz radiation require sources that are compact, low-cost, and operate at room temperature. In this project, a low-noise optically-controlled THz array antenna system will be developed, addressing a significant barrier in the adoption of THz technology. We will demonstrate a novel 'system on a chip', integrating a thin film antenna array, photodiode array, semiconductor optical amplifier (SOA) array and optical beam forming network. The SOA array enhances the pump power and ensures all array elements are evenly pumped. The beam former is used to control the phase difference between the THz radiation from different THz antennas, and thus scanning of THz beam can be realized. A THz repetition frequency mode-locked laser will be used as the light source to lock the phase of optical signals in the chip, greatly reducing the linewidth of the THz emission. The advantages of this THz emitter system include a high peak intensity due to radiation from the antennas combining coherently, room temperature operation, continuous-wave operation, compact form factor, and a narrow steerable beam. The sources will be assessed for use in systems for high-bandwidth wireless communications and for medical imaging.

In this project, the team of researchers will address the problem of autonomous robotic grasping of objects in challenging scenes. We consider two industrially and economically important open challenges which require advanced vision-guided grasping. 1) “Bin-picking” for manufacturing, where components must be grasped from a random, self-occluding heap inside a bin or box. Parts may have known models, but will only be partially visible in the heap and may have complex shapes. Shiny/reflective metal parts make 3D vision difficult, and the bin walls provide difficult reach-to-grasp and visibility constraints. 2) Waste materials handling, which may be hazardous (e.g. nuclear) waste, or materials for recycling in the circular economy. Here the robot has no prior models of object shapes, and grasped materials may also be deformable (e.g. contaminated gloves, hoses). The proposed project comprises two parallel thrusts: perception (visual and tactile) and action (planning and control for grasping/manipulation). However, perception and action are tightly coupled and this project will build on recent advances in “active perception” and “simultaneous perception and manipulation” (SPAM). In the first thrust, we will exploit recent advances in 3D sensor technology and develop perception algorithms that are robust in challenging environments, e.g. handling shiny (metallic) or transparent (glass/perspex) objects, self-occluding heaps, known objects which may be deformable or fragmented, and unknown objects which lack any pre-existing models. In the second thrust, autonomous grasp planners will be developed with respect to visual features perceived by algorithms developed in the first thrust. Grasps must be planned to be secure, but also provide affordances to facilitate post-grasp manipulative actions, and also afford collision-free reach-to-grasp trajectories. Perceptual noise and uncertainty will be overcome in two ways, namely using computationally adaptive algorithms and mechanically adaptive underactuated hands. An object initially grasped by an accessible feature may need to be re-grasped (for example a tool that is not initially graspable by its handle). We will develop re-grasping strategies that exploit object properties learned during the initial grasp or manipulative actions. Overarching themes in the project are: methods that are generalisable across platforms; reproducibility of results; and the transfer of data. Therefore, the methods proposed in the two thrusts will be tested for reproducibility by implementing them in the different partner’s laboratories, using both similar and different hardware. Large amounts of data will be collected throughout these tests, and published online as a set of international benchmark vision and robotics challenges, curated by Université Laval once the project is completed.

Carbohydrates, or sugars, are ubiquitous throughout nature and perform a number of important functions in our cells. Carbohydrates can exist in long chains, called polysaccharides, which is how energy is stored from the food we eat, why wood is strong and is responsible for the molecular glue that sticks our cells together. At the other end of the scale, single or a few sugars can be appended to other biomolecules such as proteins and lipids and are important in cell processes such as signalling and defence against pathogens. The structure and sequence of carbohydrates is complex and highly variable, but unlike DNA there is no genetic code that can be read to determine how it should exist. Instead, carbohydrate structure and sequence is defined only the enzymes, nature's catalysts, that make and break-down the carbohydrate molecules. We are interested in an enzyme, called HexD, which cleaves a sugar called N-acetyl galactosamine from substrates. Little work has been done to characterise human HexD, and the substrate on which it acts in cells, and its function, are unknown. However, it has been shown that HexD is found in the synovial fluid of patients suffering from rheumatoid arthritis, and thus understanding HexD at the molecular level could have an important impact on the health of patients suffering from the disease in the longer term. Our preliminary work on HexD suggests it may act on proteins in cells, but further investigations are needed to understand this fully. We have also revealed that HexD has some unprecedented activities, which we will dissect. The over-arching aim of the project is to understand the biological role played by HexD, and we will do this by gaining fundamental insights into how HexD works at the molecular level. We will make HexD in the laboratory and study how it works, test various substrates in order to understand its catalytic activities, and identify proteins with which it interacts in cells. We will also develop specific inhibitors against HexD, which will significantly slow its activity. These inhibitors will be administered to cells, and we will examine the effect on how the cells grow and work, to aid our understanding of the role played by HexD. In addition, we will change (increase and decrease) the levels of HexD in cells and similarly monitor the effect. Overall, these experiments will advance our understanding of the biological function of HexD.