Filtering and scalability in the ECO distributed event model

Event-based communication is useful in many application domains, ranging from small, centralised applications to large, distributed systems. Many different event models have been developed to address the requirements of different application domains. One such model is the ECO model which was designed to support distributed virtual world applications. Like many other event models, ECO has event filtering capabilities meant to improve scalability by decreasing network traffic in a distributed implementation. Our recent work in event-based systems has included building a fully distributed version of the ECO model, including event filtering capabilities. This paper describes the results of our evaluation of filters as a means of achieving increased scalability in the ECO model. The evaluation is empirical and real data gathered from an actual event-based system is used

Meta-analysis of equine gastro-intestinal microbiome research and evaluation of the impact of fructooligosaccharide supplementation on the gastro-intestinal microbiome of thoroughbred youngstock during nutritional stress

Horses are trickle feeders and hindgut fermenters, and rely on the microbial fermentation of a fiber-rich diet for their energy. The gastro-intestinal (GI) microbiome is not only vital for digestion, it may also have an important role in the overall health of a horse through interaction with the immune system. Disturbances in the GI microbiome, for example through an inappropriate diet, can lead to gastro-intestinal and systemic diseases. To avoid this, prebiotic and probiotic supplementation has been proposed to stabilize the microbiome during times of dietary change. However, little evidence exists for the efficacy of this approach.To understand the role of the GI microbiome in horse health and disease, it is important to determine the composition of the ‘normal’ equine microbiome and what factors can influence it. However, there is large variation between studies investigating the equine GI microbiome, which could be due to technical variation in the scientific methods used and/or small sample sizes that could bias the findings.To address these issues, two studies were performed that examined the influence of different factors on the equine GI microbiome: The first study was a meta-analysis of equine GI microbiome data, in which we re-analyzed the raw 16S sequencing data from 29 studies and performed a batch mean correction to account for some of the technical variation. The second study was a case-control field study that examined the impact of Fructooligosaccharide supplementation in a group of Thoroughbred yearlings undergoing a dietary change.The meta-analysis showed that technical factors, such as the sequencing instrument and gene region of the 16S gene used, have a strong impact on the GI microbial composition, such that the influence of biological factors was not visible at a global scale when comparing different studies using multivariate analysis. However, after batch mean correction of some of the technical variation, there was strong variation between different sample types and regions of the GI tract, as well as differential bacterial abundances between age groups, genders, diets and different diseases.The prebiotic field study showed a stronger shift in microbial composition in control horses than in horses given prebiotics during a time of nutritional stress. This may indicate a stabilizing effect of prebiotic supplementation during dietary change. However, the study was limited by a difference in baseline microbial compositions between horses with prebiotic supplementation and those without, which shows the importance of taking a baseline sample during longitudinal studies.Overall, these studies highlight the need for a more standardized global approach in investigating the equine GI microbiota if studies are to be comparable. This could be achieved by creating a protocol for equine GI microbiome research and a database where the generated data can be shared and compared to advance research in this field

Three-dimensional hybrid vortex solitons

We show, by means of numerical and analytical methods, that media with a repulsive nonlinearity which grows from the center to the periphery support a remarkable variety of previously unknown complex stationary and dynamical three-dimensional solitary-wave states. Peanut-shaped modulation profiles give rise to vertically symmetric and antisymmetric vortex states, and novel stationary hybrid states, built of top and bottom vortices with opposite topological charges, as well as robust dynamical hybrids, which feature stable precession of a vortex on top of a zero-vorticity base. The analysis reveals stability regions for symmetric, antisymmetric, and hybrid states. In addition, bead-shaped modulation profiles give rise to the first example of exact analytical solutions for stable three-dimensional vortex solitons. The predicted states may be realized in media with a controllable cubic nonlinearity, such as Bose-Einstein condensates.Comment: To appear in the New Journal of Physic

Exponentially Localized Magnetic Fields for Single-Spin Quantum Logic Gates

An infinite array of parallel current-carrying wires is known, from the field of neutral particle optics, to produce an exponentially localized magnetic field when the current direction is antiparallel in adjacent wires. We show that a finite array of several tens of superconducting Nb nanowires can produce a peak magnetic field of 10mT that decays by a factor of 10^4 over a length scale of 500nm. Such an array is readily manufacturable with current technology, and is compatible with both semiconductor and superconducting quantum computer architectures. A series of such arrays can be used to individually address single single-spin or flux qubits spaced as little as 100nm apart, and can lead to quantum logic gate times of 5ns.Comment: 5 pages, incl. 4 figure

Fine structure and optical pumping of spins in individual semiconductor quantum dots

We review spin properties of semiconductor quantum dots and their effect on optical spectra. Photoluminescence and other types of spectroscopy are used to probe neutral and charged excitons in individual quantum dots with high spectral and spatial resolution. Spectral fine structure and polarization reveal how quantum dot spins interact with each other and with their environment. By taking advantage of the selectivity of optical selection rules and spin relaxation, optical spin pumping of the ground state electron and nuclear spins is achieved. Through such mechanisms, light can be used to process spins for use as a carrier of information