Parra J.-H.,University of Manizales |
Duvallet A.,University of Paris 13
European Spine Journal | Year: 2011
The objective of the study was to compare the maximal aerobic capacity of patients with chronic low back pain with healthy asymptomatic controls matched for age, gender and level of physical activity at work and during sports activities. Reported data in the literature with respect to aerobic capacity in patients with chronic low back pain are not conclusive. Nevertheless, based on the assumption that chronic low back pain leads to deconditioning, physical training programs are widely used as a treatment. A total of 70 patients with chronic low back pain and 70 healthy asymptomatic subjects completed questionnaires regarding demographics and performed a graded maximal exercise test until exhaustion on a cycle ergometer. The maximal aerobic power was measured by indirect calorimetry. Heart rate, respiratory exchange ratio and blood lactate levels were also measured. The test was considered maximal when VO2max achievement criteria were obtained. VO2max values were compared among groups. The absolute and normalized for weight values of VO2max measured in patients with chronic low back pain were significantly lower than that of the control group. Independent comparison between men and women showed that absolute values of VO2max are also significantly lower in men and women with chronic low back pain. Women reached absolute and normalized for weight VO2max values significantly lower than those of men, both in chronic low back pain and control group. In conclusion, chronic low back pain patients, especially women, seem to have a reduced aerobic capacity compared to healthy asymptomatic subjects. © 2010 Springer-Verlag.
Duarte A.,University of Caldas |
Sarache W.,National University of Colombia |
Costa Y.,Upper Austria University of Applied Sciences |
Costa Y.,University of Manizales
Energy | Year: 2016
The fossil fuel consumption is still a global concern that has received great deal of attention from Chemical Engineering and Operation Research fields. In this sense, this paper presents a SCND (Supply Chain Network Design) for second-generation biofuel production. For this aim, we proposed a mathematical model that includes, simultaneously, economic and environmental issues. The model feasibility has been tested in Colombia. In this case study, the bioethanol production from Coffee Cut Stem (Coffee-CS) is examined considering the three main echelons of the supply chain. Experimental results showed that Coffee-CS is a profitable and sustainable feedstock for biofuel production. © 2016 Elsevier Ltd.
Costa Salas Y.J.,University of Manizales |
Martinez Perez C.A.,University "Marta Abreu" of Las Villas |
Bello R.,University "Marta Abreu" of Las Villas |
Oliveira A.C.,Federal University of Maranhao |
Chaves A.A.,Federal University of Sao Paulo
Expert Systems with Applications | Year: 2014
The hybridization of population-based meta-heuristics and local search strategies is an effective algorithmic proposal for solving complex continuous optimization problems. Such hybridization becomes much more effective when the local search heuristics are applied in the most promising areas of the solution space. This paper presents a hybrid method based on Clustering Search (CS) to solve continuous optimization problems. The CS divides the search space in clusters, which are composed of solutions generated by a population meta-heuristic, called Variable Mesh Optimization. Each cluster is explored further with local search procedures. Computational results considering a benchmark of multimodal continuous functions are presented. © 2014 Elsevier Ltd. All rights reserved.
An alternative solution for the repair of electrical breakdowns after natural disasters based on ant colony optimization [Solución alternativa para la reparación de averías eléctricas posterior a desastres naturales usando optimización basada en colonias de hormigas]
Costa-Salas Y.J.,University of Manizales |
Sarache-Castro W.A.,National University of Colombia
DYNA (Colombia) | Year: 2014
Abundant literature is available for the route planning based on meta-heuristic algorithms. However, most researches in this field are developed under normal scenarios (e.g. normal weather conditions). The natural disasters, such as hurricanes, on the contrary, impose hard constraints to these combinatorial problems. In this paper, a route-planning problem is solved, specifically, for the repair of electrical breakdowns that occur after natural disasters. The problem is modeled using an assignment-based integer programming formulation proposed for the Multiple Traveling Salesman Problem (mTSP). Moreover, this paper proposes the creative application of an algorithm based on Ant Colony Optimization (ACO), specifically Multi-type Ant Colony System (M-ACS), where each colony represents a set of possible global solutions. Ants cooperate and compete by means of "frequent" pheromone exchanges aimed to find a solution. The algorithm performance has been compared against other ACO variant, showing the efficacy of the proposed algorithm on realistic decision-making. © The authors; licensee Universidad Nacional de Colombia.
Intra-European rural migrations. Territorialities and rural dynamics in the South of France and the North of Spain [Migraciones rurales intraeuropeas. Territorialidades y dinámicas rurales en el sur de Francia y en el norte de España]
Nates B.,University of Manizales
Cuadernos de Desarrollo Rural | Year: 2012
This paper studies territorialities and contemporary rural dynamics in the south of France and the north of Spain based on the impact of intra-European rural migrations. Its methodology is based on: 1) the understanding and the practise of categories and classifications such as fields of knowledge and relation; 2) fieldwork data as the starting point for developing an ethnography based on observations, interviews and maps. Furthermore, secondary information was considered in order to measure the global significance of this phenomenon. Consequently, the paper highlights the existence of conflicts and negotiations between immigrants and local people, theoretical concepts applicable to similar situations, and the extension of the thematic corpus on rural migrations -studies which, in Europe, have focused on migration in southern continents.