584 research outputs found

    Payroll Reform

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    A Mean and Green Fighting Machine: Wartime Environmental Assessments and the Canadian Forces

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    In the absence of comprehensive international conventions addressing environmental harms caused by war, existing Canadian law may provide the appropriate framework to reduce the environmental impact caused by the activities of Canada’s military. In particular, the Canadian Environmental Assessment Act and the Cabinet Directive on the Environmental Assessment of Policy, Plan and Program Proposals are two existing mechanisms that can be used to help minimize the environmental harms that may result from Canadian Forces operations

    Variable Neighbourhood Search: A Case Study for a Highly-Constrained Workforce Scheduling Problem

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    This paper describes a Variable Neighbourhood Search (VNS) combined with simulated annealing to tackle a highly constrained workforce scheduling problem at British Telecommunications plc (BT). A refined greedy algorithm is firstly designed to create an initial solution which meets all hard constraints and satisfies some of the soft constraints. The VNS is then used to swap out less promising combinations, continually moving towards a more optimal solution until meeting finishing requirements. The results are promising when compared to the stand- alone greedy algorithm. We believe there is scope for this to be extended in several ways, i.e. into a more complex variation of VNS to further improve results, to be applied to further data sets and workforce scheduling problem scenarios, and to have input parameters to the algorithm selectively optimized to discover what kind of improvements in efficiency and fitness are possible. There is also scope for this to be used in similar combinatorial optimization problems

    Privileged Structure: Novel Indane Scaffolds as Potential Anticancer and Anti-Inflammatory Agents

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    The identification and use of “privileged structures” can increase the reliability and shorten the process in the drug discovery and drug design (a-b). Indane scaffolds occur in various natural products and they constitute the privileged structure that is ubiquitous in many biologically and pharmaceutically active molecules (c-e). Our research group has been working on the synthesis and pharmacological activity of nature identical and synthetically modified indanes and indanones for 20 years. In the current study, the molecular design is centred on elaboration of a fern derived bioactive pharmacophore. The fern is used in traditional Taiwanese medicine to treat inflammation, allergy, stomach cramps and fever (f). Using a synthetic approach we have designed a novel chemical scaffold which can be modified to inhibit angiogenesis and 5-lipoxygenase activity. The parent scaffold and a number of strategically modified derivatives were initially screened using the Zebra fish (Danio rerio) model of tumour angiogenesis (g). This screen led to the identification of two lead molecules, which were then further evaluated in in vitro cell lines and colorectal explants. Results from these experiments establish that the lead compounds affect inter-segmental vessel formation. These molecules also inhibit cell invasion and tube formation. When evaluated in ex vivo colorectal cancer explants where the molecules significantly affected angiogenic and inflammatory protein secretions. These small molecules also alter gene expression. Modification of the scaffold can inhibit 5-lipoxygenase activity. These data suggest that the new scaffold may have significant potential in the treatment of angiogenesis and inflammatory related diseases

    Transcriptional profile of isoproterenol-induced cardiomyopathy and comparison to exercise-induced cardiac hypertrophy and human cardiac failure

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    <p>Abstract</p> <p>Background</p> <p>Isoproterenol-induced cardiac hypertrophy in mice has been used in a number of studies to model human cardiac disease. In this study, we compared the transcriptional response of the heart in this model to other animal models of heart failure, as well as to the transcriptional response of human hearts suffering heart failure.</p> <p>Results</p> <p>We performed microarray analyses on RNA from mice with isoproterenol-induced cardiac hypertrophy and mice with exercise-induced physiological hypertrophy and identified 865 and 2,534 genes that were significantly altered in pathological and physiological cardiac hypertrophy models, respectively. We compared our results to 18 different microarray data sets (318 individual arrays) representing various other animal models and four human cardiac diseases and identified a canonical set of 64 genes that are generally altered in failing hearts. We also produced a pairwise similarity matrix to illustrate relatedness of animal models with human heart disease and identified ischemia as the human condition that most resembles isoproterenol treatment.</p> <p>Conclusion</p> <p>The overall patterns of gene expression are consistent with observed structural and molecular differences between normal and maladaptive cardiac hypertrophy and support a role for the immune system (or immune cell infiltration) in the pathology of stress-induced hypertrophy. Cross-study comparisons such as the results presented here provide targets for further research of cardiac disease that might generally apply to maladaptive cardiac stresses and are also a means of identifying which animal models best recapitulate human disease at the transcriptional level.</p

    The thing about replicas - why historic replicas matter

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    Reproduction of archaeological material was a significant and serious enterprise for antiquarians and museums in the long nineteenth century. Embedding many stories and embodying considerable past human energy, behind their creation, circulation, use and after-life lies a series of specific social networks and relationships that determined why, when and in what circumstances they were valued, or not. Summarising the context of their production, circulation and changing fortunes, this paper introduces the ways in which they are important and the specific benefits and aspects of a biographical approach to their study. Beyond the evidential, the study of existing replicas provides a historical and contemporary laboratory in which to explore the concepts of value and authenticity, and their application in cultural heritage and collections management, offering us a richer insight into the history of ourselves as archaeologists and curators

    Superhumps in Cataclysmic Binaries. XXV. q_crit, epsilon(q), and Mass-Radius

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    We report on successes and failures in searching for positive superhumps in cataclysmic variables, and show the superhumping fraction as a function of orbital period. Basically, all short-period systems do, all long-period systems don't, and a 50% success rate is found at P_orb=3.1+-0.2 hr. We can use this to measure the critical mass ratio for the creation of superhumps. With a mass-radius relation appropriate for cataclysmic variables, and an assumed mean white-dwarf mass of 0.75 M_sol, we find a mass ratio q_crit=0.35+-0.02. We also report superhump studies of several stars of independently known mass ratio: OU Virginis, XZ Eridani, UU Aquarii, and KV UMa (= XTE J1118+480). The latter two are of special interest, because they represent the most extreme mass ratios for which accurate superhump measurements have been made. We use these to improve the epsilon(q) calibration, by which we can infer the elusive q from the easy-to-measure epsilon (the fractional period excess of P_superhump over P_orb). This relation allows mass and radius estimates for the secondary star in any CV showing superhumps. The consequent mass-radius law shows an apparent discontinuity in radius near 0.2 M_sol, as predicted by the disrupted magnetic braking model for the 2.1-2.7 hour period gap. This is effectively the "empirical main sequence" for CV secondaries.Comment: PDF, 45 pages, 9 tables, 12 figures; accepted, in press, to appear November 2005, PASP; more info at http://cba.phys.columbia.edu
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