In this paper, differential evolution (DE) algorithms are presented to solve the generalized assignment problem (GAP), which is basically concerned with finding the minimum cost assignment of jobs to agents such that each job is assigned to exactly one agent, subject to capacity constraint of agents. The first algorithm is unique in terms of solving a discrete optimization problem on a continuous domain. The second one is a discrete/combinatorial variant of the traditional differential evolution algorithm working on a discrete domain. The objective is to present a continuous optimization algorithm dealing with discrete spaces hence to solve a discrete optimization problem. Both algorithms are hybridized with a "blind" variable neighborhood search (VNS) algorithm to further enhance the solution quality, especially to end up with feasible solutions. They are tested on a benchmark suite from OR Library. Computational results are promising for a continuous algorithm such that without employing any problem-specific heuristics and speed-up methods, the DE variant hybridized with a "blind" VNS local search was able to generate competitive results to its discrete counterpart.
Objectives: Clinical trial productivity has not been investigated in the Gulf Cooperation Council (GCC) region, including Oman, Saudi Arabia, United Arab Emirates (UAE), Qatar, Bahrain, and Kuwait. We aim to assess the productivity of clinical trials conducted in the GCC region. Specifically, we aim to estimate the number of clinical trials conducted and estimate the proportion of clinical trials conducted in the GCC countries published in peer-reviewed journals. Methods: The clinical trials registry of the U.S. National Library of Medicine (NLM) was searched for clinical trials conducted from January 2000 to October 2019. The productivity was assessed by the publication status of the trials in the registry and through the search in Medline indexed journals. Results: A total of 682 trials were found from the GCC region, with an overall trend of 4.1 trials each year. However, the clinical trial productivity from our area contributes to only 0.37% of the trials globally. When comparing the raw data, Saudi Arabia shows the highest proportion by contributing 66.6% of the clinical trials from the region (p < 0.001). Oman contributed 3.5 %. After normalization to population, Qatar shows to be the highest with 42.78 trials per million. A total of 238 trials were conducted before 2016, of which 46.6% were published. Conclusion: Saudi Arabia is the leading country in clinical trial productivity in the GCC region. Countries should utilize the triple helix model to a partnership with industry and improve their contribution to science. Keywords: Productivity; Clinical Trials; Publication; Oman; Gulf Cooperative Council.
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