In this article, we study a method to compare queueing systems and their fluid limits. For a certain class of queueing systems, it is shown that the expected workload (and certain functions of the workload) is higher in the queueing system than in the fluid approximation. This class is characterized by convexity of the value function in the state component(s) where external arrivals occur. The main example that we consider is a tandem of multiserver queues with general service times and Markov-modulated arrivals. The analysis is based on dynamic programming and the use of phase-type distributions. Numerical examples to illustrate the results are also given.

Insular communities in Colombia have had significant lags in human development. As a strategy to help overcome these shortcomings, this paper proposes the use of technological tools such as Snap Circuits and Arduino boards. The results obtained in the first phase of the research show that this type of technology succeeds in attracting secondary school students and contributes to the generation of capacities. It should also be noted that, in order to positively impact the human development indices of these populations, a long-term effort is required that also addresses different dimensions and strategies..

La informalidad laboral tiene un gran peso sobre la economía mundial y Colombia no es la excepción; históricamente el país se ha caracterizado por manejar altas tasas de informalidad relacionadas a su vez con variables indicadoras de pobreza. El propósito del documento es analizar este vínculo[1] en las 13 principales ciudades y áreas metropolitanas de Colombia, bajo el escenario COVID-19. Con este objetivo, se realizó un análisis de correlación simple y un modelo probit que mide el impacto de variables que componen el Índice de Pobreza Multidimensional (IPM) y variables sociodemográficas (edad y género), sobre la probabilidad de ser empleado informal. El estudio da como resultado que la variable que más impacta esta probabilidad es la pobreza monetaria. Finalmente, se describe la importancia de reducir la informalidad para avanzar en el cumplimiento de las metas nacionales relacionadas con la Agenda 2030 para el Desarrollo Sostenible. [1] El análisis de la informalidad laboral se realizó a nivel del jefe del hogar. El DANE considera jefe del hogar a la persona que, por su edad o por ser el principal sostén económico de la familia o por otras razones, es reconocida por sus miembros como tal. Puede ser hombre o mujer (2020, pág. 16).

Satellite monitoring of changes in tree cover is essential for evaluating the performance of environmental conservation systems, as it supports territorial planning in regions subject to high anthropogenic pressure. This study analyzes changes in tree cover loss and gain in the department of Cundinamarca (Colombia) between 2017 and 2024 using Land Use/Land Cover (LULC) maps generated from Sentinel-2 imagery and deep-learning-based classification models. A post-classification comparison and cross-tabulation matrices were used to quantify losses, gains and areas without change, integrating a multiscale analysis by administrative provinces and by environmental protection mechanisms, including RUNAP protected areas, indigenous reservations and Payments for Environmental Services (PES) schemes. The results indicate that 80% of the tree cover remained unchanged, the areas with gain 9.49% and the areas with loss 10.28%, resulting in a marginal net loss of 0.79%; More than 80% of tree cover transformation was associated with agricultural expansion, mainly towards rangeland, while urban conversion represented a spatially concentrated but irreversible process. Areas under conservation systems showed a buffering effect against tree cover loss, with better performance in RUNAP areas and indigenous reservations, and heterogeneous results in the PES schemes. The accuracy evaluation showed a Kappa coefficient of 0.84, confirming the robustness of the methodological approach. This study demonstrates that integrating deep-learning-based LULC products is a reproducible and cost-effective tool for the analysis of coverage changes, and provides key empirical evidence for the design of conservation, territorial planning and environmental governance policies in transformed Andean regions.