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Slide 1 of 5 Publicación Acceso Abierto
Cayley–Menger curvature: a geometric approach to discrete curvature on graphs via local simplex embedding
(Journal of Complex Networks, 2026-07-05) Sierra Porta, David; Grupo de Investigación Gravitación y Matemática Aplicada; Semillero de Investigación en Astronomía y Ciencia de Datos
We introduce a discrete curvature measure for graphs based on the Cayley-Menger determinant, which we term Cayley-Menger curvature (κCM). For each node, we construct local tetrahedra from its nearest neighbors under the effective resistance metric, compute the Cayley-Menger determinant to embed them in Euclidean space, and extract the circumradius as a proxy for local curvature. Unlike κFR and κOR, which assign signed curvature values, κCM is strictly positive by construction and is best interpreted as a measure of local geometric compactness with curvature-like behavior, complementary to—rather than a replacement for—signed discrete curvatures. We validate κCM on graphs with analytically known geometric properties—lattices, trees, complete graphs, and cycles—and demonstrate that it produces curvature values consistent with expected flat, hyperbolic, and spherical geometries. Comparison with Forman-Ricci (κFR) and Ollivier-Ricci (κOR) curvatures across a battery of benchmark networks reveals that κCM captures geometric information that is largely independent of these established measures (Spearman |ρ| ⩽ 0.47 in most cases, while κFR and κOR correlate at ρ > 0.7). As a demonstration of practical utility, we show that κCM alone outperforms both κFR and κOR as a feature for community detection in stochastic block models, achieving an order-of-magnitude improvement in Adjusted Rand Index over κFR and κOR used alone, though we note that absolute ARI values remain moderate and the baseline clustering method (Ward linkage) was chosen for simplicity rather than performance; the result demonstrates discriminative power of the κCM feature, not a claim about state-of-the-art community detection. Scalability benchmarks confirm that κCM computes faster than κOR for graphs up to n = 5000 nodes. These results establish the Cayley-Menger curvature as a complementary tool in the discrete curvature toolkit, offering direct geometric interpretability grounded in distance geometry
Slide 2 of 5 Publicación Acceso Abierto
Quasi-Experimental Evaluation of the Association Between Payments for Ecosystem Services and Satellite-Based Vegetation Dynamics in Cundinamarca, Colombia
(Land, 2026-07-25) Vergara Narvaez Andrés; Jiménez Castilla, Tania Isabel; BALLUT DAJUD, GASTON ANTONIO; Grupo de Investigación Instituto de Estudios en Desarrollo Economía y Sostenibilidad – IDEEAS
Payments for Ecosystem Services (PES) are increasingly used to promote conservation, but evidence of their biophysical outcomes remains mixed because participation is rarely assigned at random. This study assessed the association between participation in the Yo Protejo ¡Agua para Todos! PES program and satellite-based vegetation dynamics in Cundinamarca, Colombia, during 2015–2024. Annual NDVI, EVI, and SAVI values were
derived from Landsat 8 and 9 imagery processed in Google Earth Engine. The empirical strategy combined fixed-effects difference-in-differences models, two spatial comparison groups, propensity-score adjustment, inverse probability of treatment weighting, propertyclustered inference, event-study diagnostics, differential-trend models, and property-year robustness analyses. Pre-treatment and covariate-balance diagnostics indicated imperfect
counterfactual comparability, particularly for the external 500–1000 m buffer-ring controls. No vegetation index produced uniformly positive and robust associations across specifications. NDVI showed a small positive association during program implementation under the 500 m neighboring-control definition, but this result was not preserved after differential-trend adjustment or property-year aggregation. EVI produced positive pointlevel estimates under the external control, although this specification retained substantial residual imbalance and the estimates became negative after property-year aggregation. SAVI provided no robust positive evidence and showed negative post-implementation differentials in some external-control models. Overall, the estimated associations were sensitive to the vegetation metric, comparison-group definition, temporal phase, inferential level, and spatial aggregation. The results should therefore be interpreted as specificationdependent adjusted associations rather than definitive causal effects.
Slide 3 of 5 Publicación Acceso Abierto
Cartografía del sexismo y brechas de género en estudios sobre ingeniería latinoamericana (2018-2025)
(2026-07-27) Medina Reyes, María Fernanda; Vázquez Miraz, Pedro; Pastrana Quintana, Camilo Andres; Viloria Núñez, Cesar Augusto; Grupo de Investigación Desarrollo, Salud y Desempeño Humano; Grupo de Investigación Educación e Innovación Educativa; Grupo de Investigación Tecnologías Aplicadas y Sistemas de Información (GRITAS)
Este artículo presenta una revisión bibliográfica de estudios relacionados con el sexismo en carreras de ingeniería en América Latina. Objetivo: el objetivo principal es visibilizar el actual estado del conocimiento regional sobre la desigualdad de género en el ámbito de la enseñanza en ingeniería de esta región. Metodología: a través de una revisión sistemática sobre trabajos recientes relacionados con el sexismo, la ingeniería y la educación superior en América Latina, quedó conformado un corpus de diecinueve (19) estudios, de los cuales siete (7) son artículos científicos. Posteriormente se realizó una segunda búsqueda exclusiva de artículos científicos sobre brecha de género, ingeniería y educación superior en América Latina (N = 22) con el objetivo de comparar los resultados con la revisión anterior. Resultados: los hallazgos evidencian que la comunidad académica que investiga sobre esta temática muestra una tendencia a presentar estudios aplicados que son publicados en congresos y revistas científicas de carácter multidisciplinar, generalmente de acceso abierto y bajo cuartil. Aunque las líneas de investigación suelen converger en los mismos tópicos, se presentan importantes diferencias en función de la terminología empleada. Conclusiones: se recomienda diseñar investigaciones con muestras multinacionales y mayor rigor metodológico para superar las limitaciones identificadas.
Slide 4 of 5 Publicación Acceso Abierto
Heliospheric regimes governing Forbush decreases revealed by multiscale analysis of cosmic rays
(Acta Astronautica, 2026-07-14) Sierra Porta, David; Varotsos, C.; Grupo de Investigación Gravitación y Matemática Aplicada; Semillero de Investigación en Astronomía y Ciencia de Datos
We investigate the dynamical structure of galactic cosmic ray intensity using multiscale analysis applied to daily records from 16 neutron monitor stations over 2010--2025. The objective is to determine whether large Forbush decreases are associated with identifiable statistical states of heliospheric modulation. We identify a statistically distinct heliospheric regime---characterised by elevated long-range persistence and reduced natural-time variance---in which large Forbush decreases are significantly more likely. Multifractal detrended fluctuation analysis and natural time analysis are applied in a rolling framework to characterize long-range correlations and event-order dynamics. The results show that persistent long-range correlations and multifractal
structure are universal across the global network. A coherent evolution driven by the solar cycle is observed, with reduced persistence during the 2019--2020 solar minimum and enhanced organization during active periods. Across nine major Forbush decreases, 78\% occur during intervals of elevated persistence and reduced natural-time variance, indicating a distinct heliospheric regime associated with an increased likelihood of events. No significant relationship is found between these metrics and event magnitude, confirming that the signal reflects
a statistical state rather than a deterministic precursor. The combined analysis demonstrates that multiscale and natural-time approaches provide complementary information, offering a more complete characterization of heliospheric dynamics and reframing Forbush decreases as regime-dependent phenomena rather than isolated stochastic
events.
Slide 5 of 5
