Stress and birth outcomes evidence from terrorist attacks in Colombia

This paper estimates the impact of random terrorist attacks (landmines) in Colombia on the health of babies born between 1998 and 2003. The results suggest that these types of terrorist activities that occur during a woman´s first trimester of pregnancy have a negative and significant impact on child health outcomes such as birth weight and preterm deliveries, and behaviors such as use of prenatal care. These findings persist when mother fixed effects are included, suggesting that neither observable nor unobservable characteristics of the mothers are driving the main results. Thepaper contributes to the existing literature by identifying yet another important indirect channel through which violence affects economic well being. Given that studies have found a strong link between Low Birth Weight (LBW) and short and long-term socioeconomic outcomes; the negative consequences of violence identified in this paper may have long-term effects on economic activity as they affect the net returns to human capital accumulation of the new generations.

An Empirical Study on Collective Intelligence Algorithms for Video Games Problem-Solving

Computational intelligence (CI), such as evolutionary computation or swarm intelligence methods, is a set of bio-inspired algorithms that have been widely used to solve problems in areas like planning, scheduling or constraint satisfaction problems. Constrained satisfaction problems (CSP) have taken an important attention from the research community due to their applicability to real problems. Any CSP problem is usually modelled as a constrained graph where the edges represent a set of restrictions that must be verified by the variables (represented as nodes in the graph) which will define the solution of the problem. This paper studies the performance of two particular CI algorithms, ant colony optimization (ACO) and genetic algorithms (GA), when dealing with graph-constrained models in video games problems. As an application domain, the "Lemmings" video game has been selected, where a set of lemmings must reach the exit point of each level. In order to do that, each level is represented as a graph where the edges store the allowed movements inside the world. The goal of the algorithms is to assign the best skills in each position on a particular level, to guide the lemmings to reach the exit. The paper describes how the ACO and GA algorithms have been modelled and applied to the selected video game. Finally, a complete experimental comparison between both algorithms, based on the number of solutions found and the levels solved, is analysed to study the behaviour of those algorithms in the proposed domain

Preparation of quantum dots hydrogel nanocomposites with improved cytotoxicity

Nanocomposites are materials with unique properties and a wide range of applications. The combination of different nanostructures with traditional materials gives a variety of possibilities that should be analyzed. Especially, functional fluorescent semiconductor quantum dots (QDs) embedded in polymeric matrices have shown promising fluorescence and biocompatibility properties. These hybrid materials can be used in medical applications such as biodiagnostic and bioimaging. In this study, two hydrogels, one of polyethylene glycol diacrylate (PEGDA) and other of polyacrylamide (PAAm), were prepared with quantum dots of CdTe (4 nm of diameter) and characterized. The aim of this research was to analyze the optical properties of the nanocomposites and their cell viability. QDs nanocomposites were fabricated by a free radical polymerization process. The optical studies showed that the nanocomposites have well defined properties of fluorescence. To study the biocompatibility of the nanocomposites, metastatic B16f10 cell line were used and MTT assay was performed. The nanocomposites had a significant improved cell viability compared with QDs solutions

Comparative study of pheromone control heuristics in ACO algorithms for solving RCPSP problems

Constraint Satisfaction Problems (CSP) belong to a kind of traditional NP-hard problems with a high impact on both research and industrial domains. The goal of these problems is to find a feasible assignment for a group of variables where a set of imposed restrictions is satisfied. This family of NP-hard problems demands a huge amount of computational resources even for their simplest cases. For this reason, different heuristic methods have been studied so far in order to discover feasible solutions at an affordable complexity level. This paper elaborates on the application of Ant Colony Optimization (ACO) algorithms with a novel CSP-graph based model to solve Resource-Constrained Project Scheduling Problems (RCPSP). The main drawback of this ACO-based model is related to the high number of pheromones created in the system. To overcome this issue we propose two adaptive Oblivion Rate heuristics to control the number of pheromones: the first one, called Dynamic Oblivion Rate, takes into account the overall number of pheromones produced in the system, whereas the second one inspires from the recently contributed Coral Reef Optimization (CRO) solver. A thorough experimental analysis has been carried out using the public PSPLIB library, and the obtained results have been compared to those of the most relevant contributions from the related literature. The performed experiments reveal that the Oblivion Rate heuristic removes at least 79% of the pheromones in the system, whereas the ACO algorithm renders statistically better results than other algorithmic counterparts from the literature

Quantitative Analysis and Performance Study of Ant Colony Optimization Models Applied to Multi-Mode Resource Constraint Project Scheduling Problem

Constraint Satisfaction Problems (CSP) belongs to this kind of traditional NP-hard problems with a high impact in both, research and industrial domains. However, due to the complexity that CSP problems exhibit, researchers are forced to use heuristic algorithms for solving the problems in a reasonable time. One of the most famous heuristic al- gorithms is Ant Colony Optimization (ACO) algorithm. The possible utilization of ACO algorithms to solve CSP problems requires the de- sign of a decision graph where the ACO is executed. Nevertheless, the classical approaches build a graph where the nodes represent the vari- able/value pairs and the edges connect those nodes whose variables are different. In order to solve this problem, a novel ACO model have been recently designed. The goal of this paper is to analyze the performance of this novelty algorithm when solving Multi-Mode Resource-Constraint Satisfaction Problems. Experimental results reveals that the new ACO model provides competitive results whereas the number of pheromones created in the system is drastically reduced

Confiabilidad de puentes de concreto presforzado dañados por corrosión

Los puentes vehiculares con frecuencia sufren daños por corrosión, sobre todo, si están ubicados en la costa o si están expuestos a la humedad o impactos químicos. Por tanto, es conveniente contar con recomendaciones técnicas para evaluar su efecto en la seguridad estructural y proveer condiciones aceptables para la operación y el mantenimiento del puente. En este artículo se determina la variación del índice de confiabilidad de Cornell en función del tiempo en una viga en un puente vehicular simplemente apoyado, mediante el análisis del comportamiento en los cambios en los momentos de agrietamiento de las secciones transversales de una viga de concreto presforzado de sección cajón, obtenidos a partir de sus diagramas momento-curvatura. El análisis estadístico se realizó mediante simulación de Monte Carlo considerando como variables aleatorias la resistencia del concreto, el área transversal de acero de presfuerzo y la carga viva, y como variables deterministas las dimensiones de los elementos y la carga muerta. De los resultados obtenidos se observa que, a partir del inicio de la corrosión del acero de presfuerzo, en los primeros 4 años la variación en el índice de confiabilidad resultó poco significativa, mientras que en los años subsecuentes se presenta lo contrario disminuyendo a valores menores de 1.75 a partir de 6 años de iniciada la corrosión, lo cual no garantiza condiciones de operación aceptables para la estructura