Lo efímero interminable: pinturas de José Luis Feliciano

Obra Gráfica

Perspectivas de jóvenes universitarias durante la pandemia de COVID-19

This paper aims to describe the perceptions of undergraduate female students from public and private institutions about distance education during confinement due to COVID-19 in three cities in the state of Yucatan. The methodology used was mixed research methods, based on semi- structured interviews and data analysis from national and international sources. Among the findings the challenges of both groups of students in the implementation of online education during the first months of the pandemic in 2020 were recorded. This paper's distinctiveness is that it contributes to research on the advancement of girls’ education, through the collection of primary information, in order to make suggestions that allow them to continue in the national educational system.

Barreras de acceso geográfico a los servicios de salud oral en el departamento del Tolima, Colombia.

Cross-sectional descriptive mixed study carried out for the 47 municipalities of the department of Tolima, Colombia, neighboring the department of Cundinamarca, where Bogota, the capital of the country, is located. The objective was to analyze the geographical access barriers and the inventory of human talent and dental services in this department. A distance and time measurement system was applied to identify the duration of travel from each municipality to Ibagué (departmental capital) by public transport. The geographical accessibility barrier determinant endorsed by the World Health Organization (W.H.O.) is a trip duration greater than four hours. It was found that the first level of care in the public sector is present in all municipalities, the second level is in six; the third only in Ibague. Displacement by public transport represents a geographical access barrier in six municipalities; the number of dentists in the public sector does not satisfactorily cover the needs of the population, since more than 50% of the municipalities have a deficit of more than four general dentists and there is a low presence of specialists. In the department of Tolima there are geographical accessibility barriers to health and, specifically, to oral health.

Interseccionalidad: recurso para la producción de espacios urbano-arquitectónicos inclusivos

Recently, the concept of intersectionality has acquired bigger visibility because of the interest and alert that have awaken in our society a range of social rights fights and movements, among them, and in a remarkable way, feminism. However, their demands and the theories derived from the ideas of these groups do not seem to have passed through the consciousness, knowledge or practice of architects, urbanists, and others involved in the urban-architectural production in Mexico. Most actions that harm, force, discriminate or marginalize people occur in the built environment which, itself, is not neutral. On the contrary, through its materiality and inner dynamics, the built environment manifests -and gets incorporated into- the social processes of the context, perpetuating or modifying its constructs. Because of this, we consider it is fundamental to think about the links between the approaches generated by the ones that drive social change and the collective work related with the production of the built environment. The concept of intersectionality has a main role in this paper for what it makes evident: the privilege and domination that certain conditions have over others -as well as their possible intersections-, which can affect anyone at some point.

Modelo de estimación de pesos de árbol filogenético para un cuartet, aplicando conjugación de Hadamard

The subject on this paper is that part of algebraic phylogenetics which proposes a method to infere the expected values of three kinds of nucleotide substitutions on the branches of a phylogenetic tree that explains the ancestral relations among an associated set of lineages. A tool known as Hadamard conjugation is presented, which –because it connects both the probability distribution of the different substitution patterns on the leaves of the phylogenetic tree, and the complete set of expected values of substitutions on its branches– may indeed be a resource to phylogenetic reconstruction. Based on this, a likelihood function is built for a quartet associated with an alignment of four nucleotide sequences.

Métodos de reconstrucción filogenética II: inferencia bayesiana

Phylogenetic reconstruction through Bayesian inference is currently widely used. The main advantage of this method is the direct output of posterior probabilities for each clade on the final phylogeny. Thus, it does not require bootstrapping as a measure of uncertainty. Moreover, Bayesian inference is perfectly fit for dating phylogenies through molecular clocks. In this paper, the basics of Bayesian inference applied to phylogenetic reconstruction are described, starting with an explanation of Bayes’ theorem. Then, the use of the Metropolis-Hastings algorithm to sample topologies from the posterior distribution is characterized and illustrated through a simple example. At the end, there is a mention of the software used for Bayesian phylogeny reconstruction.

Filogenias: conceptos y generalidades

Any research in biology is an exercise of comparison that includes the study of evolution. The investigation of evolutionary patterns in either of its two approaches (micro or macroevolutionary) raises methodological challenges for any researcher interested in these topics. These approaches have a common interest in understanding the origin the relationships between the studied organisms, although the temporal scales and the level of organization in which they focus are different. Currently, phylogenies are the most robust tool to explain ancestor-descendant relationships between a set of organisms. These diagrams, which are two-dimensional (cladograms) or multidimensional (networks), can be estimated with different approximations (maximum parsimony, máximum likelihood, and bayesian inference) according to the data available and the purpose of the investigation. This review presents an introduction to the methods available for the construction of phylogenies, including the traditional perspective that uses diagrams based on dichotomies and the new trends that try to visualize more complex patterns through evolutionary networks.

Indagando aspectos evolutivos con filogenias: reloj molecular y otras técnicas útiles en biología comparada

The first step for evolutionary studies is usually to establish a hypothesis of relationships between members of the study group. After this, there is a wide range of possibilities depending on the researcher's interest. This contribution presents the generalities of some of the methodologies most commonly used in macroevolutionary studies: the molecular clock and the reconstruction of ancestral characters. Information on other useful techniques for comparative studies that use a phylogenetic framework is also presented, such as phylogenetic signal estimation, independent contrasts, orthonormal decomposition, and phylogenetic principal component analysis.

Politopos en filogenética

We introduce mathematical notions used in phylogenetics and three sorts of phylogenetics polytopes. The Tight span and the Lipschitz polytope are both associated to finite metric spaces and can be connected to distance-preserving embeddings, while the balanced minimum evolution (BME) polytope is associated to natural numbers.

Métodos de reconstrucción filogenética I: máxima verosimilitud

Phylogenetic inference is widely used in evolutionary biology, aiming to find evolutionary relationships between different species and report the result in the form of a phylogenetic tree (phylogeny). There are several statistical methods used for phylogenetic inference. In this review, the method of maximum likelihood for phylogenetic reconstruction is presented. This technique consists of finding the likelihood of multiple candidate phylogenies, and report the one with the highest likelihood as a representative of the evolutionary relationships of a group of species. In this paper, the likelihood calculation of a phylogeny from multiple-species DNA sequences is reviewed. Also, some key DNA mutation models to calculate transition probabilities between nucleotides are presented. Such transition probabilities are used in the likelihood calculation of a given phylogeny. A simple example is shown to illustrate the necessary steps to infer a phylogeny, as well as the most common software for maximum likelihood inference for larger DNA alignments.