Generalized annealing algorithms for discrete optimization problems.

Despite the success of simulated annealing to find near-optimal solutions of intractable discrete optimization problems, there have been attempts to enhance the algorithm by modifying transition probabilities. However, the asymptotic behavior of modified algorithms is very difficult to analyze, i.e., well-known convergence results of simulated annealing usually become inapplicable to other annealing algorithms. In this research, we consider a generalized annealing algorithm, the acceptance probability of which depends on the cost of the current solution, the cost of the solution candidate, and the control parameter. We present convergence results that relax sufficient conditions provided by most general convergence theorems in the literature. We study the asymptotic behavior of the stationary distribution corresponding to the generalized annealing algorithm. Using a novel approach that relies on the Markov Chain Tree Theorem, we provide a convergence theorem for the stationary distribution. By exploiting the same insights, we analyze the limiting stationary distribution of a generalized annealing algorithm that uses local information other than the cost of the current solution to guide the search. The class of convergent transition probabilities can be further extended by employing an adaptive cooling schedule. By so doing, we can relax the condition that the transition probabilities asymptotically behave like an exponential function. Based on an adaptive cooling schedule scheme, we present conditions that guarantee the convergence to optimal solutions. We develop a novel stochastic search algorithm called functional annealing that combines the attractive features of both simulated annealing and a local search technique. The algorithm can thereby benefit from exploiting a very large-scale neighborhood structure. Furthermore, we incorporate functional annealing with statistical learning techniques to enhance the finite-time performance of the algorithm. Our computational results on the Quadratic Assignment Problem reveal that functional annealing algorithms outperform many existing ones. We also present theoretical and computation results from the use of functional annealing for solving a discrete stochastic optimization problem.Ph.D.Applied SciencesOperations researchUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/125513/2/3192788.pd

Antimicrobial Usage and Antimicrobial Resistance in Animal Production in Southeast Asia: A Review

Southeast Asia is an area of great economic dynamism. In recent years, it has experienced a rapid rise in the levels of animal product production and consumption. The region is considered to be a hotspot for infectious diseases and antimicrobial resistance (AMR). We reviewed English-language peer-reviewed publications related to antimicrobial usage (AMU) and AMR in animal production, as well as antimicrobial residues in meat and fish from 2000 to 2016, in the region. There is a paucity of data from most countries and for most bacterial pathogens. Most of the published work relates to non-typhoidal Salmonella (NTS), Escherichia coli (E. coli), and Campylobacter spp. (mainly from Vietnam and Thailand), Enterococcus spp. (Malaysia), and methicillin-resistant Staphylococcus aureus (MRSA) (Thailand). However, most studies used the disk diffusion method for antimicrobial susceptibility testing; breakpoints were interpreted using Clinical Standard Laboratory Institute (CSLI) guidelines. Statistical models integrating data from publications on AMR in NTS and E. coli studies show a higher overall prevalence of AMR in pig isolates, and an increase in levels of AMR over the years. AMU studies (mostly from Vietnam) indicate very high usage levels of most types of antimicrobials, including beta-lactams, aminoglycosides, macrolides, and quinolones. This review summarizes information about genetic determinants of resistance, most of which are transferrable (mostly plasmids and integrons). The data in this review provide a benchmark to help focus research and policies on AMU and AMR in the region

The pharmacology of flukicidal drugs

Peer reviewe