64 research outputs found

    Uncertainty Principle Enhanced Pairing Correlations in Projected Fermi Systems Near Half Filling

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    We point out the curious phenomenon of order by projection in a class of lattice Fermi systems near half filling. Enhanced pairing correlations of extended s-wave Cooper pairs result from the process of projecting out s-wave Cooper pairs, with negligible effect on the ground state energy. The Hubbard model is a particularly nice example of the above phenomenon, which is revealed with the use of rigorous inequalities including the Uncertainty Principle Inequality. In addition, we present numerical evidence that at half filling, a related but simplified model shows ODLRO of extended s-wave Cooper pairs.Comment: RevTex 11 pages + 1 ps figure. Date 19 September 1996, Ver.

    Influence of oral beclomethasone dipropionate on early non-infectious pulmonary outcomes after allogeneic hematopoietic cell transplantation: results from two randomized trials.

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    Early non-infectious pulmonary complications represent a significant cause of mortality after hematopoietic cell transplantation (HCT). We tested the hypothesis that oral beclomethasone dipropionate (BDP) is effective for preventing early non-infectious pulmonary complications after allogeneic HCT. We retrospectively reviewed the medical records of 120 patients, 60 in each treatment arm, to identify non-infectious and infectious pulmonary events and pulmonary function test results from all patients who participated in two randomized trials of oral BDP for treatment of acute gastrointestinal GVHD. 17-Beclomethasone monopropionate (17-BMP), the active metabolite of BDP, was evaluated in blood from the right atrium in four patients. Thirty-three of 42 (79%) placebo-treated patients experienced a decrease of the DL(CO) from pretransplant to day 80 after transplant, compared with 27 of 49 (55%) BDP-treated patients (P=0.02). In the first 200 days after randomization, there were no cases of non-infectious pulmonary complications in BDP-treated patients, vs four cases among placebo-treated patients (P=0.04). Levels of 17-BMP were detected in atrial blood at steady state. Delivery of a potent glucocorticoid such as 17-BMP to the pulmonary artery after oral dosing of BDP may be useful in modulating pulmonary inflammation and preventing the development of non-infectious pulmonary complications after allogeneic HCT.Bone Marrow Transplantation advance online publication, 29 June 2009; doi:10.1038/bmt.2009.129

    Comparison of Steady State and Generational Genetic Algorithms for Use in Nonstationary Environments

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    The objective of this study is a comparison of two models of the genetic algorithm, the generational and incremental/steady state genetic algorithms, for use in nonstationary/dynamic environments. It is experimentally shown that choice of a suitable version of the genetic algorithm can improve its performance in such environments. This can extend ability of the genetic algorithm to track environmental changes which are relatively small and occur with low frequency without need to implement an additional technique for tracking changing optima. 1 Introduction The genetic algorithm is a proven search/optimisation technique [Holland 1975] based on an adaptive mechanism of biological systems. In our previous work we showed that the genetic algorithm is a suitable on-line optimization method to balance the load of the presses in a sugar beet pressing station [Fogarty,Vavak,Cheng 1995] and in load balancing of multiple burner boiler [Vavak,Fogarty,Jukes 1995]. Because both mentioned applica..
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