Adriana Ramirez Ramirez Ramirez - Academia.edu (original) (raw)
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Papers by Adriana Ramirez Ramirez Ramirez
We present a math-heuristic algorithm for the lot sizing problem with carryover. The proposed alg... more We present a math-heuristic algorithm for the lot sizing problem with carryover. The proposed algorithm uses mathematical programming techniques in a metaheuristic fashion to iteratively solve smaller portions of the original problem. More specifically, we draw ideas from the corridor method to design and impose exogenous constraints on the original problem and, subsequently, we solve to optimality the constrained problem using a MIP solver. The algorithm iteratively builds new corridors around the best solution found within each corridor and, therefore, explores adjacent portions of the search space. In the attempt of fostering diversification while exploring the original search space, we generate a pool of incumbent solutions for the corridor method and, therefore, we reapply the corridor method using different starting points. The algorithm has been tested on instances of a standard benchmark library and the reported results show the robustness and effectiveness of the proposed scheme.
We present a hybrid algorithm for the multi level capacitated lot sizing problem with setup carry... more We present a hybrid algorithm for the multi level capacitated lot sizing problem with setup carry-over. The problem is an extension of the classical capacitated lot sizing problem. The inclusion of setup carry-over implies that the setup state of a machine can be extended over two, or more, consecutive periods. The proposed algorithm is based upon a hybrid approach, where a metaheuristic, an LP solver and a dynamic programming scheme are iteratively used within a Lagrangean framework. Finally, three repair heuristics aimed at finding feasible solutions in the neighborhood of an incumbent, infeasible solution, are presented. The algorithm is tested on 480 benchmark instances from the literature and promising results are obtained, both in terms of solution quality and computational time.
Journal of Pharmacy and Pharmacology, 2002
Pain-induced functional impairment in the rat (PIFIR) is a model of inflammatory and arthritic pa... more Pain-induced functional impairment in the rat (PIFIR) is a model of inflammatory and arthritic pain similar to that of clinical gout. Nociception is induced by the intra-articular injection of uric acid into the right hind limb, inducing its dysfunction. Animals then receive analgesic drugs and the recovery of functionality over time is assessed as an expression of antinociception. We have examined the role of peripheral prostaglandins synthesized by cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) in inflammatory pain using the PIFIR model. Rofecoxib (a selective COX-2 inhibitor) and SC-560 (a selective COX-1 inhibitor) both produced dose-dependent effects. When the inhibitors were administered before uric acid, they showed similar potency, but the antinociceptive efficacy of SC-560 was lower than rofecoxib; the best antinociceptive effects were obtained with the dose of 100 microg/articulation of each inhibitor (pre-treatment). In post-treatment (inhibitors administered after the uric acid), rofecoxib showed the least antinociceptive effect and SC-560 was more potent than rofecoxib. The inhibition of both COX-1 and COX-2 produced a more profound analgesic effect than the inhibition of either COX-1 or COX-2 alone. The present data support the idea that both COX isoforms contribute to the development and maintenance of local inflammatory nociception. Thus, it could be expected that inhibition of both COX-1 and COX-2 is required for non-steroidal anti-inflammatory drugs (NSAID)-induced antinociception in the rat. These findings suggest that the therapeutic effects of NSAIDs may involve, at least in part, inhibition of COX-1 and COX-2.
We present a math-heuristic algorithm for the lot sizing problem with carryover. The proposed alg... more We present a math-heuristic algorithm for the lot sizing problem with carryover. The proposed algorithm uses mathematical programming techniques in a metaheuristic fashion to iteratively solve smaller portions of the original problem. More specifically, we draw ideas from the corridor method to design and impose exogenous constraints on the original problem and, subsequently, we solve to optimality the constrained problem using a MIP solver. The algorithm iteratively builds new corridors around the best solution found within each corridor and, therefore, explores adjacent portions of the search space. In the attempt of fostering diversification while exploring the original search space, we generate a pool of incumbent solutions for the corridor method and, therefore, we reapply the corridor method using different starting points. The algorithm has been tested on instances of a standard benchmark library and the reported results show the robustness and effectiveness of the proposed scheme.
We present a hybrid algorithm for the multi level capacitated lot sizing problem with setup carry... more We present a hybrid algorithm for the multi level capacitated lot sizing problem with setup carry-over. The problem is an extension of the classical capacitated lot sizing problem. The inclusion of setup carry-over implies that the setup state of a machine can be extended over two, or more, consecutive periods. The proposed algorithm is based upon a hybrid approach, where a metaheuristic, an LP solver and a dynamic programming scheme are iteratively used within a Lagrangean framework. Finally, three repair heuristics aimed at finding feasible solutions in the neighborhood of an incumbent, infeasible solution, are presented. The algorithm is tested on 480 benchmark instances from the literature and promising results are obtained, both in terms of solution quality and computational time.
Journal of Pharmacy and Pharmacology, 2002
Pain-induced functional impairment in the rat (PIFIR) is a model of inflammatory and arthritic pa... more Pain-induced functional impairment in the rat (PIFIR) is a model of inflammatory and arthritic pain similar to that of clinical gout. Nociception is induced by the intra-articular injection of uric acid into the right hind limb, inducing its dysfunction. Animals then receive analgesic drugs and the recovery of functionality over time is assessed as an expression of antinociception. We have examined the role of peripheral prostaglandins synthesized by cyclooxygenase-1 (COX-1) and cyclooxygenase-2 (COX-2) in inflammatory pain using the PIFIR model. Rofecoxib (a selective COX-2 inhibitor) and SC-560 (a selective COX-1 inhibitor) both produced dose-dependent effects. When the inhibitors were administered before uric acid, they showed similar potency, but the antinociceptive efficacy of SC-560 was lower than rofecoxib; the best antinociceptive effects were obtained with the dose of 100 microg/articulation of each inhibitor (pre-treatment). In post-treatment (inhibitors administered after the uric acid), rofecoxib showed the least antinociceptive effect and SC-560 was more potent than rofecoxib. The inhibition of both COX-1 and COX-2 produced a more profound analgesic effect than the inhibition of either COX-1 or COX-2 alone. The present data support the idea that both COX isoforms contribute to the development and maintenance of local inflammatory nociception. Thus, it could be expected that inhibition of both COX-1 and COX-2 is required for non-steroidal anti-inflammatory drugs (NSAID)-induced antinociception in the rat. These findings suggest that the therapeutic effects of NSAIDs may involve, at least in part, inhibition of COX-1 and COX-2.