Quantum computers operate in a fundamentally different way to normal digital computers. It has been demonstrated how in priciple such computers may revolutionise some tasks such as secure communication and cryptography, and it is now understood how they can be used in simulating and understanding quantum systems such as atoms, molucules and atomic nuclei. Recently, real quantum computers have been built at a basic, and the promise of revolutionary new applications has begun to be demonstrated in test cases, with the pace of development continuing rapidly. The technical difficulties of creating robust quantum computing hardware mean that current systems are noisy, with processing power below what one would ideally like to solve ones chosen problems. One needs, therefore, to develop well-tailored algorithms for today's quantum computers to get the most out of them, and to prepare for the next advances in technology. In this project, we will develop algorithms which will run on today's quantum computers, and be tested on simulartors or near-term future systems, to understand how best to simulate nuclear physics problems. The key here is to understand the particular symmetries that are present in nuclei, and to use those to guide the algorithms we are developing. In part we can take many hints from developments in other quantum systems - in particular those whose properties are defined by electronic states in materials - but must adapt to the details of atomic nuclei. This Scientific Exchance Visit project will link together a team from the University of Surrey whose expertise lies in nuclear physics with one at EPFL in Lausanne, Switzerland, to marry together techniques developed for electronic material study on quantum computer systems, to nuclear physics problems, to benefit the UK research programme in nuclear physics in answering questions covering the nature of nuclear matter, how nuclei are created in stellar reactions, and to undertstand the nuclear data relevant to the UK nuclear industry.

This proposal is for a research visit to share research ideas in sparse representations and compressed sensing between the signal processing labs in EPFL and the Edinburgh Compressed Sensing research group. Sparse representations have emerged as a very powerful technique for describing data in signal and image processing, and increasingly in many areas of machine learning. The underlying structure that they expose helps make challenging tasks such as detection, classification, separation and signal acquisition tractable and aids computational efficiency. Compressed sensing is a subfield of sparse approximation that involves a radical re-thinking of the sampling process and enables their acquisition (sensing) through many fewer samples than would be predicted by the traditional Nyquist criterion. It has generated a wealth of interest in recent years, not just within the signal processing community but across many related disciplines and applications: from seismology and radar to genomic sequencing. In this project we will explore the next generation of sparse representaions and compressed sensing schemes that combine advanced imaging modalities with novel structured signal models.

Abstracts are not currently available in GtR for all funded research. This is normally because the abstract was not required at the time of proposal submission, but may be because it included sensitive information such as personal details.

Primary microcephaly is a hereditary disease characterised by reduced brain size from birth and mental retardation. It occurs in ~1 in 10,000 individuals in some populations, but, importantly, it is one of few diseases where we can directly trace the effects of single mutations to brain development and cognitive functions. As a result primary microcephaly cases have proved instructive in identifying crucial brain development factors for which no backup systems exist. Centrosomes, are small organelles in human cells that organise a network of thin filaments (known as microtubules) that are essential for cells to grow, duplicate, move and sense their surroundings. Defects in centrosomes have been implicated in microcephaly. Five out of nine genes known to cause the disease correspond to centrosome components, and these include three proteins known to be essential for the formation of these organelles. In addition to microcephaly, centrosomal defects are causative agents for multiple human medical conditions, including male sterility, ciliopathies and possibly cancer. Thus, understanding how centrosomes form is an important biological question with direct medical relevance. Over the last few years our group, and others, have shown how a single protein, SAS-6, forms the initial framework onto which centrosomes are build. Crucial to this understanding was a combination of biophysical, structural and cell biology tools that allowed us to analyse the shape of essential proteins, envision how such proteins might join to form molecular machines, and test these insights in human cells. Here, we propose to build upon our understanding of the initial centrosomal framework by studying three protein components (Cep135, CPAP and STIL) that link to it. We have selected these components because they are essential for centrosomes, they appear to be connected to one another and to SAS-6, and importantly, they are all directly implicated in primary microcephaly. We believe that understanding the role of these three proteins will also inform us on how centrosomes are formed in normal cells and how defects in them cause severe diseases. We expect that these results will underpin future efforts on how to treat such diseases. Our group has long experience in the biophysical and structural biology methods necessary for the pursuit of this project. However, we do not rely on our core competencies alone. Our goal of understanding the centrosome structure is shared with internationally acclaimed groups in Oxford and abroad, with whom we collaborate. Our network of laboratories provides the broadest possible base of technical expertise and, thus, the best hope for determining how centrosomes form.

Most chemical synthesis is performed in solution because in this phase it is easy to ensure that there are a large number of reactive collisions between reactant molecules. In addition, solution chemistry is well understood and we thus have a high degree of control over the reactions that can be performed and the products that can be synthesised. The problem with this approach is twofold. Firstly, the solvents many solvents are environmentally unfriendly and secondly separating the product from the solution at the end of the reaction often requires distillation, which requires a large input of energy and which introduces an extra step to the whole process. It would thus be enormously beneficial if this step could be avoided and if the solvent could be eliminated. Mechanochemical reactions allow for just this possibility. In these processes the reactants are powdered crystals. These powders are mixed together and mechanical work is done on the mixture in, for example, a mortar and pestle, a ball mill or an extruder. Experiments have demonstrated that it is possible to do a wide range of reactions in this way i.e., "mechanochemically". Furthermore, these mechanochemical processes are seen in some quarters to be the best way to synthesise systems known as co-crystals in which one or more chemical components are packed together into an ordered, crystalline structure. However, wider use of these processes and commercialization of these technologies is prevented because of the relative lack of understanding of the fundamental mechanisms that are in play in these reactions. The aim of this project is to examine what happens in a mechanochemical reaction by performing molecular dynamics simulations using a computer. Such simulations are useful because it is possible to keep track of the positions of all the atoms at all times. This, however, is also the difficulty as specialized tools are required to make sense of large volume of high dimensional data that emerges from such simulations. One of our intentions is, therefore, to develop computational tools for studying these highly complex processes. Throughout the work a reaction between two pharmaceutically active molecules, aspirin and meloxicam, will be studied. We will construct models for nanoparticles composed of each of these molecule types and will use non-equilibrium molecular dynamics simulations to force collisions between these particles to occur. Collisions will be performed for a range of collision velocities and for a number of different collision geometries. We will investigate head on collisions between the particles and glancing collisions as well as collisions in which we will change the relative orientations of the two crystal structures. For all these various kinds of collisions we will investigate the degree to which the two chemical components mix and the degree to which the crystallinity of the structure is disrupted by the collision. This work will give us one of the first visualizations of the zone of reaction in a mechanochemical process. More importantly, however, it will provide us with a way of rationalising what is being observed in the reactive zone. This work will thus provide new fundamental insights into how and why these reactions proceed and will serve as a basis for future work on the comercial exploitation of these reactions.