Parallel Optimisations of Perceived Quality Simulations

Processor architectures have changed significantly, with fast single core processors replaced by a diverse range of multicore processors. New architectures require code to be executed in parallel to realize these performance gains. This is straightforward for small applications, where analysis and refactoring is simple or existing tools can parallelise automatically, however the organic growth and large complicated data structures common in mature industrial applications can make parallelisation more difficult. One such application is studied, a mature Windows C++ application used for the visualisation of Perceived Quality (PQ). PQ simulations enable the visualisation of how manufacturing variations affect the look of the final product. The application is commonly used, however suffers from performance issues. Previous parallelisation attempts have failed. The issues associated with parallelising a mature industrial application are investigated. A methodology to investigate, analyse and evaluate the methods and tools available is produced. The shortfalls of these methods and tools are identified, and the methods used to overcome them explained. The parallel version of the software is evaluated for performance. Case studies centring on the significant use cases of the application help to understand the impact on the user. Automated compilers provided no parallelism, while the manual parallelisation using OpenMP required significant refactoring. A number of data dependency issues resulted in some serialised code. Performance scaled with the number of physical cores when applied to certain problems, however the unresolved bottlenecks resulted in mixed results for users. Use in verification did benefit, however those in early design stages did not. Without tools to aid analysis of complex data structures, parallelism could remain out of reach for industrial applications. Methods used here successfully, such as serialisation, and code isolation and serialisation, could be used effectively by such tools

Measuring Controlled-NOT and two-qubit gate operation

Accurate characterisation of two-qubit gates will be critical for any realisation of quantum computation. We discuss a range of measurements aimed at characterising a two-qubit gate, specifically the CNOT gate. These measurements are architecture-independent, and range from simple truth table measurements, to single figure measures such as the fringe visibility, parity, fidelity, and entanglement witnesses, through to whole-state and whole-gate measures achieved respectively via quantum state and process tomography. In doing so, we examine critical differences between classical and quantum gate operation.Comment: 10 pages (two-column). 1 figur

A review of soil NO transformation: associated processes and possible physiological significance on organisms

NO emissions from soils and ecosystems are of outstanding importance for atmospheric chemistry. Here we review the current knowledge on processes involved in the formation and consumption of NO in soils, the importance of NO for the physiological functioning of different organisms, and for inter- and intra-species signaling and competition, e.g. in the rooting zone between microbes and plants. We also show that prokaryotes and eukaryotes are able to produce NO by multiple pathways and that unspecific enzymo-oxidative mechanisms of NO production are likely to occur in soils. Nitric oxide production in soils is not only linked to NO production by nitrifying and denitrifying microorganisms, but also linked to extracellular enzymes from a wide range of microorganisms. Further investigations are needed to clarify molecular mechanisms of NO production and consumption, its controlling factors, and the significance of NO as a regulator for microbial, animal and plant processes. Such process understanding is required to elucidate the importance of soils as sources (and sinks) for atmospheric NO