Universidad Nacional de Colombia

Regional Hydroclimatic Sensitivity of Monthly Precipitation Anomalies to ENSO in the Colombian Andes and Orinoquia

El Niño–Southern Oscillation (ENSO) modulates tropical South American rainfall, but its Colombian expression is filtered by terrain, rainfall regime, moisture pathways, and atmospheric state. We quantify ENSO-related sensitivity of standardized precipitation anomalies in the Colo...

History of divergence and gene flow shaping geographic variation in Andean warblers (Myioborus).

Studying how genetic variation is structured across space, and how it relates to divergence in phenotypic traits relevant to reproductive isolation, is important for our understanding of the speciation process. We used ddRAD-seq data to examine genetic variation across the distri...

Anchors for Homology-Based Scaffolding

Homology-based scaffolding orders contigs based on conserved collinearity of homologous sequences across related species. Existing methods often rely on costly whole-genome alignments or show limited robustness when integrating multiple references. Here, we introduce an anchor-ba...

On Pell, Narayana and Padovan Languages and Their Generalizations

In this article, we study several languages associated with classical integer sequences such as the Pell, Narayana, and Padovan sequences, as well as various generalizations. Some of these languages arise naturally in the context of graph theory. We show that a subset of these la...

Recovering Latent Association from Likert-Type Responses: A Monte Carlo Comparison of Pearson, Spearman, Kendall, and Polychoric Correlations Under Discretization, Response Perturbation, and Gumbel-Copula Dependence

Likert-type responses are often analyzed as continuous scores, although their categories are ordered rather than truly metric. This study uses Monte Carlo simulation to examine how ordinal discretization, response perturbation, and non-Gaussian dependence affect four association...

Bayesian Inference for the Automultinomial Model With an Application to Landcover Data

ABSTRACT Multicategory lattice data arise in a wide variety of disciplines such as image analysis, biology, and forestry. We consider modeling such data with the automultinomial model, which can be viewed as a natural extension of the autologistic model to multicategory responses...

Skew-symmetric augmented matrices and a characterization of virtual doodles

Abstract In this paper, we present a brief overview of the concept of doodles from the perspective of J. S. Carter’s work on classifying immersed curves and the work of J. Carter, S. Kamada, and M. Saito on stable equivalence of knots on surfaces and virtual knot cobordisms. We u...

Data-Driven Ensemble Machine Learning for Multi-Horizon Microalgal Bioprocess Forecasting

Microalgal bioprocesses increasingly rely on predictive modelling to support automated control and reduce the cost of laboratory experimentation. Yet, the scarcity of high-quality datasets and the nonlinear nature of microalgal growth severely limit the accuracy and robustness of...

Computer Vision-Based Information Extraction from Electrical Assets: A Systematic Literature Review

Automated inspection of electrical equipment has become increasingly important as utilities seek to replace inefficient manual processes in infrastructure management. Electrical-equipment nameplates contain critical technical information, but automatically extracting this informa...

An Artificial Intelligence–Based Index for Climate Resilience Assessment of Community Aqueducts in Tropical Andean Watersheds: Application in Colombia

Abstract Community-managed water supply systems, or community aqueducts, are complex socioecological systems that are highly vulnerable to climate variability and change. Assessing climate resilience is therefore essential to inform decision-making processes aimed at strengthenin...

A New Bis(8-hydroxyquinolinylmethyl) Perhydrobenzimidazole Obtained from a Cyclic Aminal Derived from trans-1,2-Diaminocyclohexane and 8-Hydroxyquinoline

The reaction of 8-hydroxyquinoline and (2R,7R,11S,16S)-1,8,10,17-tetraazapentacyclo [8.8.1.1.8,170.2,70.11,16]icosane under Mannich-type conditions afforded a new quinoline-functionalized diazabicyclic derivative in 27% yield. The structure of the product was established by FT-IR...

Applied Statistical Validation of GC–FID Acetaldehyde Determination in Extra-Neutral Alcohol Using Recovery, Relative Bias, and Factorial Analysis of Variance

Acetaldehyde is routinely monitored in neutral alcohol, but pooled precision summaries can obscure changes in performance across the working range. This study evaluated 446 valid GC–FID verification results obtained by three anonymized analysts on two gas chromatographic systems...

Psychometric properties of the Functional Assessment of Cancer Therapy–Lung (FACT-L) scale to measure health-related quality of life

Abstract Purpose To validate the Functional Assessment of Cancer Therapy–Lung (FACT-L) scale and assess its psychometric properties in patients with lung cancer in Colombia. Methods The analysis included exploratory and confirmatory factor analysis, internal consistency (248 pati...