Multilocal programming and applications

Preprint versionMultilocal programming aims to identify all local minimizers of unconstrained or constrained nonlinear optimization problems. The multilocal programming theory relies on global optimization strategies combined with simple ideas that are inspired in deflection or stretching techniques to avoid convergence to the already detected local minimizers. The most used methods to solve this type of problems are based on stochastic procedures and a population of solutions. In general, population-based methods are computationally expensive but rather reliable in identifying all local solutions. In this chapter, a review on recent techniques for multilocal programming is presented. Some real-world multilocal programming problems based on chemical engineering process design applications are described.Fundação para a Ciência e a Tecnologia (FCT

Solvent-Induced Morphology Control of Polymer Assemblies with Improved Photothermal Features

Organic photothermal agents (OPTAs) are extensively utilized in applications such as therapy and imaging. However, enhancing their photothermal performance often depends on complex molecular designs, which are limited by the challenges of chemical synthesis. Herein, we present a straightforward strategy to optimize the optical absorbance of OPTAs by adjusting the morphology of assemblies of an amphiphilic block copolymer (PEG44-PTA5), leading to enhanced photothermal conversion efficiency. By changing the polarity of the organic solvent in which the polymer was dissolved, addition of water to induce assembly led to the exclusive formation of polymersomes or bicontinuous nanospheres. The morphological variations were confirmed using a range of electron microscopy techniques and small-angle X-ray scattering. Due to their mesoporous structure, the bicontinuous nanospheres exhibited superior light-harvesting capabilities, achieving a high absorption coefficient of 1.1 × 105 M-1 cm-1 and a photothermal conversion efficiency of 45% when irradiated with a 808 nm laser. Our work introduces a facile solvent-induced assembly strategy for precisely controlling the morphology of OPTAs while simultaneously tuning their light absorption properties to enhance photothermal conversion.</p

Statistical Mechanics of Horizontal Gene Transfer in Evolutionary Ecology

The biological world, especially its majority microbial component, is strongly interacting and may be dominated by collective effects. In this review, we provide a brief introduction for statistical physicists of the way in which living cells communicate genetically through transferred genes, as well as the ways in which they can reorganize their genomes in response to environmental pressure. We discuss how genome evolution can be thought of as related to the physical phenomenon of annealing, and describe the sense in which genomes can be said to exhibit an analogue of information entropy. As a direct application of these ideas, we analyze the variation with ocean depth of transposons in marine microbial genomes, predicting trends that are consistent with recent observations using metagenomic surveys.Comment: Accepted by Journal of Statistical Physic

Differences in Development of Oleic and Linoleic Acid in High- and Normal-Oleic Virginia and Runner-Type Peanuts

ABSTRACT A consistent, pure supply of high-oleic (HO) peanuts is important to certain segments of the food industry as it allows for the production of confections and other products with improved shelf-life characteristics. Peanut shellers have struggled with food industry demands for lots which contain greater than 95% high-oleic peanuts. Normal-oleic (NO) and HO cultivars of virginia and runner market type peanuts were grown during the 2012 and 2013 growing season respectively to investigate differences in fatty acid development between HO and NO peanuts. Fatty acid profiles of individual seeds from individual plants taken across the growing season were determined in relation to seed fresh weight. Fatty acid profiles of HO virginia-type seeds from the early sampling date of 78 days after planting (DAP) revealed oleic acid to linoleic acid ratios (O/L) of only 4.0 in the seeds of the greatest fresh weight. As the oleic acid concentration in many of the HO virginia-type peanuts reached 60 to 80% and the linoleic acid concentrations ranged from less than 1.0 to 10 % by the middle sampling date (106 DAP), the O/L ratios of most HO seeds were well above the industry accepted cut-off ratio of 9.0. A similar change in the fatty acids was seen in the HO runner cultivar. Increases in oleic acid and decreases in linoleic acid contents occurred in conjunction with the increased seed fresh weights. The data indicate that HO seed attain high-oleic status as physiological development progresses as seen in the changing seed fresh weight. However at the final sampling dates which corresponded to the harvest dates, O/L ratios of less than 9.0 were still present for the HO cultivars of both market types despite the fresh weight of some seeds being of potential marketable size. It was concluded that some of the perceived contamination of HO seed lots with NO seed could be the result of normal peanut development, especially in the virginia-type cultivar with the larger sized seeds.</jats:p

Bayesian estimation of humpback whale (<i>Megaptera novaeangliae</i>) population abundance and movement patterns in southeastern Alaska

We used a mechanistic movement model within a Bayesian framework to estimate survival, abundance, and rate of increase for a population of humpback whales ( Megaptera novaeangliae ) subject to a long-term photographic capture–recapture effort in southeastern Alaska, USA (SEAK). Multiple competing models were fitted that differed in movement, recapture rates, and observation error using deviance information criterion. The median annual survival probability in the selected model was 0.996 (95% central probability interval (CrI): 0.984, 0.999), which is among the highest reported for this species. Movement among areas was temporally dynamic, although whales exhibited high area fidelity (probability of returning to same area of ≥0.75) throughout the study. Median abundance was 1585 whales in 2008 (95% CrI: 1455, 1644). Incorporating an abundance estimate of 393 (95% confidence interval: 331, 455) whales from 1986, the median rate of increase was 5.1% (95% CrI: 4.4%, 5.9%). Although applied here to cetaceans in SEAK, the framework provides a flexible approach for estimating mortality and movement in populations that move among sampling areas.</jats:p