The Universidad Distrital Francisco José de Caldas (Spanish: Universidad Distrital Francisco José de Caldas) is a public, coeducational, research university based in Bogotá, Colombia. It is the second most important public higher education institution in the city, after the National University of Colombia, with a population of 26,140 students. It was founded in 1948, by Priest Daniel de Caicedo, who would become its first rector, with the support of the Bogotá City Council, as the Municipal University of Bogotá (Spanish: Universidad Municipal de Bogotá). It changed its name to the current in 1957 when the municipality of Bogotá became a district. Its establishment was officialized by the 1970 decree No. 1030, issued by the national government. The university offers 70 programs at undergraduate and postgraduate levels, including four masters and one doctorate.The university is member of the Association of Colombian Universities (ASCUN), the Iberoamerican Association of Postgraduate Universities (AUIP), and the Iberoamerican University Network Universia.
Polyhydroxyalkanoates (PHAs) are biodegradable biobased polymers with the potential to replace conventional plastics. To reduce production costs while contributing to wastewater treatment, mixed microbial cultures (MMCs) have been proposed as a sustainable platform for PHA production. This process comprises three stages: (1) acidogenic fermentation of wastewater streams to generate volatile fatty acids (VFAs), (2) selection and enrichment of MMCs under feast–famine conditions, and (3) PHA accumulation using the selected biomass. The aim of this study was to evaluate the selection and enrichment of MMCs for PHA production within a circular economy framework. VFAs obtained by sludge acidogenic fermentation were used as the carbon source, and two operational factors organic load (500–1500 mg COD L-1) and cycle length (3 or 6 days) were tested in a 3 × 2 factorial design. The condition of 500 mg COD L-1 with a 3-day cycle achieved the highest performance, with statistically significant effects (p < 0.05) for both main factors and their interaction. Pilot-scale validation in a 16-L working volume reactor confirmed these results, yielding 83.3 mg PHA L-1 (reported as PHB-equivalents following acid hydrolysis to crotonic acid and HPLC quantification) and a yield of 0.28 g COD g COD-1 ( Y_PHA/VFA , expressed as COD-based PHA produced per COD of VFA consumed). Molecular analysis revealed species classically associated with PHA dynamics (Paracoccus sp., Alcaligenes sp.) and the presence of Diaphorobacter limosus, suggesting complementary roles under selective pressure. These findings highlight wastewater valorization into bioplastics as a viable route within the circular economy framework.
Tropical ecosystems play a critical role in global climate regulation and host the highest biodiversity on Earth, yet their long-term responses to climate change remain poorly understood. The Miocene has garnered significant attention in recent years as an interval with potential analogs for future climate change, with pCO(2) levels and continental configurations like the modern. However, most Miocene paleoclimate reconstructions rely on marine or high-latitude records, leaving tropical terrestrial environments underrepresented, which limits our ability to test climate model predictions for lower latitudes and understand the relationship between climate and biosphere during this time. We integrate pedogenic carbonate clumped isotope paleothermometry and phytolith analyses to investigate Neotropical vegetation and climate change between the middle and late Miocene comprising the La Venta Konzentrat-Lagerstatte and overlying deposits, Colombia. Our record suggests a substantial similar to 18 degrees C decline in soil temperature, accompanied by declining delta C-13 values in soil-respired CO2. Phytolith assemblages from the late Miocene indicate closed-canopy forests that do not fully match any single modern analog, consistent with vegetation shaped by Miocene climatic and biogeographic conditions. Together, these results point to increasingly cool and densely vegetated landscapes in northern South America during the middle to late Miocene, in contrast with regional and global interpretations of widespread aridification. However, the magnitude of reconstructed cooling exceeds global expectations, and Quaternary soil-carbonate temperatures at the site are anomalously warm relative to modern climate, indicating that soil processes specific to tropical settings may influence temperatures inferred from carbonate clumped isotope paleothermometry. These findings underscore the need for expanded terrestrial proxy records and improved calibration of carbonate formation in tropical soils to refine paleotemperature reconstructions in the Neotropics.
This paper introduces a distributed sensitivity-conditioning approach for bilevel optimization in networked microgrids. The proposed method enhances the coordination between subsystems by embedding sensitivity-based predictive terms into the dynamic updates, thereby improving convergence stability without requiring strict time-scale separation. Unlike conventional singular perturbation techniques, the sensitivity-conditioning formulation enables faster and more robust convergence of the distributed dynamics under heterogeneous subsystem speeds. The approach is applied to a networked microgrid scenario where local agents perform decentralized optimization considering both internal generation and energy exchange with neighboring microgrids. Simulation results demonstrate that the proposed algorithm achieves efficient coordination, reduces convergence time, and maintains stability under diverse operating conditions. The results highlight the method’s potential as a scalable and computationally efficient alternative for real-time distributed energy management and bilevel control in power network applications.
Mining plays a crucial role in Colombia's economy, yet its governance presents significant challenges due to the sector's complexity and the need to balance economic, social, and environmental concerns. While national-level planning has historically guided the sector's development, it often overlooks local dynamics, limiting its effectiveness in addressing region-specific challenges. This study proposes a system dynamics framework for mining planning that shifts from a national perspective to a district-level approach, enabling a more granular analysis of territorial dynamics. Five prioritized mining districts were modelled using system dynamics, integrating economic, environmental, and social variables to simulate alternative policy and market scenarios. Results highlight key trade-offs between production, employment, environmental impacts, and social conflict across districts, providing insights for policymakers to improve governance, enhance sector formalization, and promote sustainable mining practices. The findings underscore the importance of territorial planning in achieving a more resilient and equitable mining sector in Colombia.
Most genera of Apicotermitinae described in the Neotropics are still regarded as monotypic. In this paper, we describe a second species for the so far monotypic genus Chasitermes: Chasitermes tupan sp. nov., discovered in the Amazon Rainforest. The worker is characterized by external features, such as a strongly dilated tibia, and internal features, such as a very dilated first procodeal segment and long enteric valve seating. The description of this new taxon within the Apicotermitinae emphasizes the diversity of species of this subfamily, which remains largely unexplored in the Neotropics.
