11 research outputs found

    Optimising a nonlinear utility function in multi-objective integer programming

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    In this paper we develop an algorithm to optimise a nonlinear utility function of multiple objectives over the integer efficient set. Our approach is based on identifying and updating bounds on the individual objectives as well as the optimal utility value. This is done using already known solutions, linear programming relaxations, utility function inversion, and integer programming. We develop a general optimisation algorithm for use with k objectives, and we illustrate our approach using a tri-objective integer programming problem.Comment: 11 pages, 2 tables; v3: minor revisions, to appear in Journal of Global Optimizatio

    Operational Research in Education

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    Operational Research (OR) techniques have been applied, from the early stages of the discipline, to a wide variety of issues in education. At the government level, these include questions of what resources should be allocated to education as a whole and how these should be divided amongst the individual sectors of education and the institutions within the sectors. Another pertinent issue concerns the efficient operation of institutions, how to measure it, and whether resource allocation can be used to incentivise efficiency savings. Local governments, as well as being concerned with issues of resource allocation, may also need to make decisions regarding, for example, the creation and location of new institutions or closure of existing ones, as well as the day-to-day logistics of getting pupils to schools. Issues of concern for managers within schools and colleges include allocating the budgets, scheduling lessons and the assignment of students to courses. This survey provides an overview of the diverse problems faced by government, managers and consumers of education, and the OR techniques which have typically been applied in an effort to improve operations and provide solutions

    Adipose tissue, serum adipokines, and ghrelin in patients with ankylosing spondylitis.

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    International audienceAdipokines such as leptin and adiponectin are involved in the regulation of inflammation. Ghrelin, a gastric peptide playing a role in the appetite regulation, possesses anti-inflammatory properties. In this study, we evaluated the circulating levels of adipokines (leptin as potential proinflammatory and adiponectin as anti-inflammatory marker) and ghrelin and the fat mass in patients with ankylosing spondylitis (AS). Serum leptin, adiponectin, and ghrelin were evaluated in 53 AS patients with active disease (mean Bath Ankylosing Spondylitis Disease Activity Index >40) and 35 controls. Fat and lean masses were determined using dual-energy x-ray absorptiometry. Fat and lean masses did not differ between patients and controls. Ankylosing spondylitis patients had lower leptin levels compared with controls, even after adjustment for fat mass (AS vs controls: leptin, 7.6 +/- 1.3 ng/mL vs 10.3 +/- 1.5 ng/mL; leptin [in nanograms per milliliter]/fat mass [in kilograms], 0.28 +/- 0.04 vs 0.44 +/- 0.04; P = .006 and P = .0003, respectively). Serum adiponectin did not differ between patients and controls, whereas circulating ghrelin was higher in AS patients (1354.6 +/- 70.5 pg/mL vs 1008.0 +/- 82.5 pg/mL; P = .001). However, all these results were significant only for male patients. No correlation was found between leptin and adiponectin, and erythrocyte sedimentation rate, C-reactive protein levels, tumor necrosis factor alpha, or Bath Ankylosing Spondylitis Disease Activity Index. Ankylosing spondylitis patients had no changes in fat mass. Leptin production was reduced in contrast with normal levels of adiponectin. These adipokine results, together with high serum ghrelin levels, may influence the inflammatory response in AS
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