Genetic multi-armed bandits: a reinforcement learning approach for discrete optimization via simulation

This paper proposes a new algorithm, referred to as GMAB, that combines concepts from the reinforcement learning domain of multi-armed bandits and random search strategies from the domain of genetic algorithms to solve discrete stochastic optimization problems via simulation. In particular, the focus is on noisy large-scale problems, which often involve a multitude of dimensions as well as multiple local optima. Our aim is to combine the property of multi-armed bandits to cope with volatile simulation observations with the ability of genetic algorithms to handle high-dimensional solution spaces accompanied by an enormous number of feasible solutions. For this purpose, a multi-armed bandit framework serves as a foundation, where each observed simulation is incorporated into the memory of GMAB. Based on this memory, genetic operators guide the search, as they provide powerful tools for exploration as well as exploitation. The empirical results demonstrate that GMAB achieves superior performance compared to benchmark algorithms from the literature in a large variety of test problems. In all experiments, GMAB required considerably fewer simulations to achieve similar or (far) better solutions than those generated by existing methods. At the same time, GMAB's overhead with regard to the required runtime is extremely small due to the suggested tree-based implementation of its memory. Furthermore, we prove its convergence to the set of global optima as the simulation effort goes to infinity

Efecto del CO2 en la germinación de embriones somáticos de Coffea arabica L. cv. ‘Caturra rojo’ y Clematis tangutica K.

The in vitro environment is a factor that in recent years has begun to investigate, because gases such as oxygen, carbon dioxide and ethylene play an important role in the morphogenesis of somatic embryos and their development in plants. The objective of this work was to determine the effect of the CO2 on the germination of coffee somatic embryos (Coffea arabica L. cv. 'Caturra rojo') and clematis (Clematis tangutica K.). Three gas mixtures composed of CO2 concentrations (2.5, 5.0 and 10.0%) combined with 21% O2 and two controls (passive exchange and forced ventilation) were used. A positive effect of CO2 on the germination of somatic embryos in the torpedo stage in coffee and clematis was obtained, because in the treatments with passive exchange, where there was CO2 accumulation, germination of the somatic embryos was superior to the treatments with Forced ventilation. With 2.5% and 5.0% CO2, the germination process is stimulated while with 10.0% CO2 there is an inhibition of germination with the appearance of malformations and hyperhydricity. Keywords: gaseous atmosphere, carbon dioxide, somatic embryogenesis, secondary embryogenesis, hyperhydricityEl ambiente in vitro es un factor que en los últimos años se ha comenzado a investigar, debido a que los gases como el oxígeno, dióxido de carbono y el etileno juegan un papel importante en la morfogénesis de los embriones somáticos y su desarrollo en plantas. El objetivo de este trabajo fue determinar el efecto del CO2 en la germinación de embriones somáticos cafeto (Coffea arabica L. cv. ‘Caturra rojo’) y clematis (Clematis tangutica K.). Se emplearon tres mezclas de gases compuesta por concentraciones de CO2 (2.5, 5.0 y 10.0%) combinada con 21% O2 y dos controles (intercambio pasivo y ventilación forzada). Se obtuvo un efecto positivo del CO2 sobre la germinación de los embriones somáticos en etapa de torpedo en cafeto y clematis, porque en los tratamientos con intercambio pasivo, donde hubo acumulación de CO2, la germinación de los embriones somáticos fue superior a los tratamientos con ventilación forzada. Con 2.5% y 5.0% de CO2 se estimula el proceso de germinación, mientras que con 10.0% de CO2 se produce una inhibición de la germinación con la aparición de malformaciones e hiperhidricidad. Palabras clave: atmósfera gaseosa, dióxido de carbono, embriogénesis somática, embriogénesis secundaria, hiperhidricida

Vascular proteomics in metabolic and cardiovascular diseases.

The vasculature is essential for proper organ function. Many pathologies are directly and indirectly related to vascular dysfunction, which causes significant morbidity and mortality. A common pathophysiological feature of diseased vessels is extracellular matrix (ECM) remodelling. Analysing the protein composition of the ECM by conventional antibody-based techniques is challenging; alternative splicing or post-translational modifications, such as glycosylation, can mask epitopes required for antibody recognition. By contrast, proteomic analysis by mass spectrometry enables the study of proteins without the constraints of antibodies. Recent advances in proteomic techniques make it feasible to characterize the composition of the vascular ECM and its remodelling in disease. These developments may lead to the discovery of novel prognostic and diagnostic markers. Thus, proteomics holds potential for identifying ECM signatures to monitor vascular disease processes. Furthermore, a better understanding of the ECM remodelling processes in the vasculature might make ECM-associated proteins more attractive targets for drug discovery efforts. In this review, we will summarize the role of the ECM in the vasculature. Then, we will describe the challenges associated with studying the intricate network of ECM proteins and the current proteomic strategies to analyse the vascular ECM in metabolic and cardiovascular diseases