Submicrosecond time transfer between the United States, United Kingdom, and Australia via satellite

During 1972 time transfer experiments were run between the U.S. Naval Observatory and the Royal Greenwich Observatory and, in 1973, between the U.S. Naval Observatory and the Division of National Mapping in Canberra, Australia. In both cases the time transfer agent was the TIMATION 2 satellite, 1969-82B. The satellite ephemerides were computed from data provided by the Defense Mapping Agency TRANET. This net tracked the satellite's Doppler transmissions. The phase of the satellite clock was determined from knowledge of the position of the satellite and of the observer and the computed distance between the two. By monitoring the clock on successive passes the rate of the satellite clock was determined at Washington. By again monitoring the satellite clock at the distant station the satellite clock could be compared to the local clock and this local clock compared to the U.S. Naval Observatory clocks. In 1972 the RMS of observations at Greenwich deviated by approximately 1/4 microsecond from a straight line when compared to the Naval Observatory. In 1973 the observation errors at Canberra were approximately half as great

Optimised analysis and visualisation of metabolic data using graph theoretical approaches

Since the completion of the Human Genome Project in 2003, it has become increasingly apparent that while genomics has a major role to play in the understanding of human biology, information from other disciplines is necessary to explain the web of interacting signals that allow our bodies to function on a day to day basis and respond to rapid changes in our local environment. One such field, that of metabolomics, focuses on the study of the set of low molecular weight compounds (metabolites) involved in metabolism. Metabolomic studies aim to quantify the concentrations of each of these compounds within a subject under particular conditions, resulting in either information on the physiological effects of a disease or environmental factor (such as a toxin) on the organism, or the identification of metabolites or groups of metabolites that serve as biochemical markers for a state or illness. Whilst metabolite concentrations alone can give great insight into a chosen state, additional information can be obtained by considering the ways in which metabolites interact with each other as parts of a larger system. One method of tackling this problem, metabolic networks, is gaining popularity within the community as it offers a complementary approach to the traditional biological method for studying metabolism, the metabolic pathway. Construction methods are varied; ranging from the mapping of experimental data onto pathway diagrams, through the use of correlation-based techniques, to the analysis of time-series data of metabolic fluxes. However, while many attempts have been made to capture and visualise the complex web of reactions within an organism, few have yet succeeded in showing how they can be used to help identify the metabolites that are most significantly involved in the differences between groups of biological samples. This thesis discusses ways in which graphs may be used to aid researchers in both the visualisation and interpretation of metabolomic datasets, and provide a platform for more automated analysis techniques. To that end, it first presents the background to the relevant topics, metabolomics and graph theory, before moving on to show how metabolic correlation networks can be used to identify and visualise differences in metabolism between groups of subjects. It then introduces Linked Metabolites, a software package that has been developed to help researchers explain differences in metabolism by highlighting relationships between metabolites within the metabolic pathways, and to compile those relationships into directed metabolic graphs suitable for analysis using metrics from graph theory. Finally, the thesis explains how the directed metabolic graphs produced by Linked Metabolites could potentially be used to integrate data gathered from the same sample using different experimental techniques, refining the areas of the underlying biochemistry needing further investigation

Thirty Years of Turnstiles and Transport

To characterize transport in a deterministic dynamical system is to compute exit time distributions from regions or transition time distributions between regions in phase space. This paper surveys the considerable progress on this problem over the past thirty years. Primary measures of transport for volume-preserving maps include the exiting and incoming fluxes to a region. For area-preserving maps, transport is impeded by curves formed from invariant manifolds that form partial barriers, e.g., stable and unstable manifolds bounding a resonance zone or cantori, the remnants of destroyed invariant tori. When the map is exact volume preserving, a Lagrangian differential form can be used to reduce the computation of fluxes to finding a difference between the action of certain key orbits, such as homoclinic orbits to a saddle or to a cantorus. Given a partition of phase space into regions bounded by partial barriers, a Markov tree model of transport explains key observations, such as the algebraic decay of exit and recurrence distributions.Comment: Updated and corrected versio

Tailored Education for Patients with Heart Failure

Heart failure is one of the most common chronic heart diseases in the United States. While numerous types of treatment are available for patients with heart failure, one common finding is still present: an increased need for more individualized, tailored patient education. Heart failure is one of the most common reasons for readmission into the hospital within 30 days of discharge. Reimbursement to hospitals and health systems becomes jeopardized when patients are readmitted within 30 days of discharge for the same diagnosis. Finding suggest that a causative agent is there is a lack of individualized patient education. Low literacy levels have been associated with increased mortality and morbidity for patients with heart failure. It is crucial to create individualized, tailored education for the patient with heart failure that is written at the fifth to sixth grade level to help combat health literacy issues. Self-care is the cornerstone for success at managing heart failure. The use of an individualized, tailored educational binder can increase self-care and management of heart failure. Improving self-care can improve outcomes in patients with heart failure and help decrease the 30-day readmission rates

Retrograde transport pathways utilised by viruses and protein toxins

A model has been presented for retrograde transport of certain toxins and viruses from the cell surface to the ER that suggests an obligatory interaction with a glycolipid receptor at the cell surface. Here we review studies on the ER trafficking cholera toxin, Shiga and Shiga-like toxins, Pseudomonas exotoxin A and ricin, and compare the retrograde routes followed by these protein toxins to those of the ER trafficking SV40 and polyoma viruses. We conclude that there is in fact no obligatory requirement for a glycolipid receptor, nor even with a protein receptor in a lipid-rich environment. Emerging data suggests instead that there is no common pathway utilised for retrograde transport by all of these pathogens, the choice of route being determined by the particular receptor utilised

Grain refinement in a AlZnMgCuTi alloy by intensive melt shearing: A multi-step nucleation mechanism

This is a post-print version of the article. Copyright @ 2010 Elsevier B.V.Direct chill (DC) cast ingots of wrought Al alloys conventionally require the deliberate addition of a grain refiner to provide a uniform as-cast microstructure for the optimisation of both mechanical properties and processability. Grain refiner additions have been in widespread industrial use for more than half a century. Intensive melt shearing can provide grain refinement without the need for a specific grain refiner addition for both magnesium and aluminium based alloys. In this paper we present experimental evidence of the grain refinement in an experimental wrought aluminium alloy achieved by intensive melt shearing in the liquid state prior to solidification. The mechanisms for high shear induced grain refinement are correlated with the evolution of oxides in alloys. The oxides present in liquid aluminium alloys, normally as oxide films and clusters, can be effectively dispersed by intensive shearing and then provide effective sites for the heterogeneous nucleation of Al3Ti phase. As a result, Al3Ti particles with a narrow size distribution and hence improved efficiency as active nucleation sites of alpha-aluminium grains are responsible for the achieved significant grain refinement. This is termed a multi-step nucleation mechanism.Funding was obtained from the EPRSC

The Impact of Turfgrass Pest Management System Techniques on Surface and Ground Water Quality

ReportThe impact of various turfgrass pest management strategies (PMS) on water quality has recently become a concern for many golf course superintendents, sports facilities managers and homeowners. With water quality standards becoming increasingly stringent, management practices have had to follow suit. Uses of alternative control strategies have become increasingly important. This includes the use of biological, cultural and preventative control practices to reduce pest pressure, as well as environmental impacts. Turfgrass is, no doubt, a beneficial addition to most ecosystems, yet when mis-managed can cause harm as well. Mis-management of the turfgrass ecosystem can greatly influence the nitrogen, phosphate and pesticide levels in surface and ground water, causing problems for communities that depend on clean water for consumption as well as recreation. Aquatic ecosystems as well can be severely harmed by increased levels of nitrogen and phosphate, which can cause algal bloom, decreased dissolved oxygen levels, and eutrophication, which in turn has an impact on nearly all ecosystems. Pesticides that find their way into surface or ground water pose a problem to exposed species ranging from fish to humans. When managed correctly, turfgrass provides many positive attributes, including increased UV absorption, CO2 remediation, soil stabilization, ground and surface water filtration, and aesthetic benefits. It is our goal to test the impact of three of the most commonly implemented turfgrass pest management systems, (preventative, IPM, and organic systems) on surface and ground water quality and turfgrass performance. The results will hopefully provide answers on how to produce acceptable turfgrass quality while benefiting the environment

The Influence of the effect of solute on the thermodynamic driving force on grain refinement of Al alloys

Grain refinement is known to be strongly affected by the solute in cast alloys. Addition of some solute can reduce grain size considerably while others have a limited effect. This is usually attributed to the constitutional supercooling which is quantified by the growth restriction factor, Q. However, one factor that has not been considered is whether different solutes have differing effects on the thermodynamic driving force for solidification. This paper reveals that addition of solute reduces the driving force for solidification for a given undercooling, and that for a particular Q value, it is reduced more substantially when adding eutectic-forming solutes than peritectic-forming elements. Therefore, compared with the eutectic-forming solutes, addition of peritectic-forming solutes into Al alloys not only possesses a higher initial nucleation rate resulted from the larger thermodynamic driving force for solidification, but also promotes nucleation within the constitutionally supercooled zone during growth. As subsequent nucleation can occur at smaller constitutional supercoolings for peritectic-forming elements, a smaller grain size is thus produced. The very small constitutional supercooling required to trigger subsequent nucleation in alloys containing Ti is considered as a major contributor to its extraordinary grain refining efficiency in cast Al alloys even without the deliberate addition of inoculants.The Australian Research Council (ARC DP10955737)

The contribution of constitutional supercooling to nucleation and grain formation

The concept of constitutional supercooling (CS) including the term itself was first described and discussed qualitatively by Rutter and Chalmers in order to understand the formation of cellular structures during the solidification of tin, and then quantified by Tiller et al. On that basis, Winegard and Chalmers further considered 'supercooling and dendritic freezing of alloys' where they described how CS promotes the heterogeneous nucleation of new crystals and the formation of an equiaxed zone. Since then the importance of CS in promoting the formation of equiaxed microstructures in both grain refined and unrefined alloys has been clearly revealed and quantified. This paper describes our current understanding of the role of CS in promoting nucleation and grain formation. It also highlights that CS, on the one hand, develops a nucleation-free zone surrounding each nucleated and growing grain and, on the other hand, protects this grain from readily remelting when temperature fluctuations occur due to convection. Further, due to the importance of the diffusion field that generates CS, recent analytical models are evaluated and compared with a numerical model. A comprehensive description of the mechanisms affecting nucleation and grain formation and the prediction of grain size is presented with reference to the influence of the casting conditions applied during the practical casting of an alloy