Universidad del Norte, Colombia

About: Universidad del Norte, Colombia is a education organization based out in Barranquilla, Colombia. It is known for research contribution in the topics: Population & Context (language use). The organization has 3562 authors who have published 4355 publications receiving 37861 citations. The organization is also known as: University of the North, Colombia & Uninorte.

Out of Amazonia and back again: historical biogeography of the species-rich neotropical genus Philodendron (Araceae).

Abstract: The origin of Neotropical species diversity is strongly associated with the geological history of South America. Since the Miocene, a number of species radiations across different Neotropical lineages coincided with the rise of the Andes and the formation of the Isthmus of Panama. The species-rich genus Philodendron Schott (Araceae) is widely distributed across Neotropical rainforests, originating in the Late Oligocene and diversifying more intensely from the Miocene onward. It is likely that its diversification process and distribution patterns are associated with recent geological changes in the Americas. To test this hypothesis, we sampled the species diversity of Philodendron across its entire geographic range and used a combination of three non-coding plastid regions (petD, rpl16, and trnK/matK) to obtain a comprehensive time-calibrated phylogeny. We then inferred geographic range evolution and explored the impact of the Andean orogeny on speciation, extinction, and dispersal. The genus Philodendron originated ∼29 million years ago (mya) and experienced the earliest diversification events ∼25 mya in the Pan-Amazonian rainforests. From the Middle Miocene onward, multiple geographic range expansion events occurred from Amazonia to southeast Brazil and to the area which would become the Choco and the northern Andes. From the Pliocene onward, Philodendron reached Central America and the Caribbean islands, and Andean lineages recolonized and diversified in Amazonia. In Philodendron, higher diversification rates are found in the adjacent lowland rainforests of the northern Andes compared with other regions in the Neotropics, demonstrating a potential indirect impact of the Andean uplift on species radiations in lowland regions.

El fenómeno de consumo y el consumo en marketing

Abstract: En este articulo se presentan las principales caracteristicas que tipifican el fenomeno de consumo en las sociedades contemporaneas. Para lograrlo, primero se revisan algunas aproximaciones conceptuales del consumo, visto como fenomeno social, asociandolo con el simbolismo de consumo, los rituales, las posesiones y el materialismo como motores propulsores de la concepcion y practica del marketing de hoy.

Robust Data Assimilation Using $L_1$ and Huber Norms

Abstract: Data assimilation is a process used to fuse information from priors, observations of nature, and numerical models, in order to obtain best estimates of the parameters or state of a physical system of interest. Presence of large errors in some observational data, e.g., data collected from a faulty instrument, negatively affect the quality of the overall assimilation results. This work develops a systematic framework for robust data assimilation. The new algorithms continue to produce good estimates of parameters or state in the presence of observation outliers. The approach is based on replacing the traditional $L_2$ norm formulation of data assimilation problems with formulations based on $L_1$ and Huber norms. Numerical experiments using the Lorenz-96 and the shallow water on the sphere models illustrate how the new algorithms outperform traditional data assimilation approaches in the presence of data outliers.

Fuzzy knowledge discovery and decision-making through clustering and Dynamic tables : Application in Colombian business Finance

Abstract: This article aims to analyze financially the companies belonging to the Colombian services sector through the Altman Z Score model and to make a new model based on the use of fuzzy logic. The methodology for the development of fuzzy models based on clustering and pivot tables was used for the development of the fuzzy inference model. The data were obtained from the Legis Comex database on financial information for the year 2017 for the services sector of Colombia. In total, there were 5,372 companies. The type of problem for this case study is classification. Results show 90% of accuracy, with an average absolute deviation of 0.096 (less than 10%) with a Kappa index of 84.7%, indicating excellent performance in the task of classifying a company's bankruptcy risk. As a main conclusion we can establish that the implemented methodology could be considered a learning technique because it uses multiple layers of processing that help represent the behavior of data with multiple levels of abstraction, helping to convert linear problems into nonlinear due to the uniqueness of fuzzy logic.