Changes in commodity prices, such as the fall in coffee prices from 2000 to 2004, affect land use decisions on farms, and the environmental services they provide. A survey of 50 farms showed a 35% loss in the area under coffee between 2000 and 2004 below 700 m with the majority of this area (64 %) being coffee agroforest systems that included native forest species. Loss of coffee only occurred on large and medium-scale farms; there was no change in area on cooperatives. Coffee productivity declined below 1,100 m altitude for sun and Inga shade coffee, but only below 700 m altitude for agroforest coffee. Coffee productivity was 37-53% lower under agroforests than other systems. Increases in rubber and pasture were related to low altitude large-scale farms, and bananas and timber plantations to mid-altitude farms. Average aboveground carbon stocks for coffee agroforests of 39 t C ha(-1) was similar to rubber plantations, but one-third to one half that of natural forest and timber plantations, respectively. Coffee agroforests had the highest native tree diversity of the productive systems (7-12 species ha(-1)) but lower than natural forest (31 species ha(-1)). Conversion of coffee agroforest to other land uses always led to a reduction in the quality of habitat for native biodiversity, especially avian, but was concentrated among certain farm types. Sustaining coffee agroforests for biodiversity conservation would require targeted interventions such as direct payments or market incentives specifically for biodiversity.

Due to the global alert about the risk of contagion and propagation of Covid-19, a situation that has changed in the educational processes, this has forced the system to migrate towards a more dynamic and connected model of teaching and learning, which has allowed not to interrupt and to continue with the training processes, in a remote and assisted way. In this research, the profile of the engineering and science student is analyzed, and its relationship with the learning of physics in this crisis. For this purpose, the technique of simple random sampling of a certain population was applied, a research instrument was designed and validated by pairs of experts, its reliability was established based on Cronbach’s Alpha test, and the instrument was applied to 354 students of the faculty of engineering and basic sciences, of the Universidad Francisco de Paula Santander, located in the city of Cúcuta, Colombia, during a 15-day time window, the analysis of the data and variables is carried out from the design of a mathematical model of logistic regression, where the dependent variable represents the feeling of emotional affect by the obligatory social isolation. The results indicated that the students feel emotionally affected in 88.56% generating implications in the learning of physics and in their academic performance, especially those who comply the profile: being female, single, not having received training in the use of digital platforms, without academic difficulties but who feel that their academic performance has been affected.

RESUMENEl artículo presenta la evolución de los servicios de telefonía móvil en Latinoamérica contextualizados en las diferentes generaciones tecnológicas, las características del software para dispositivos móviles y una propuesta de método de trabajo para el desarrollo de aplicaciones para móviles. El método se basa en la conceptualización de las tecnologías y las metodologías ág-iles para el desarrollo de software, y su objetivo principal es facilitar la creación de nuevas aplicaciones y servicios exitosos. El método se desarrolla en cinco etapas: etapa de análisis, donde se obtienen y clasifican los requerimientos y se personaliza el servicio; etapa de diseño, momento en el que se define el escenario tecnológico y se estructura la solución por medio de algún diagrama o esquema, integrando tiempos y recursos; etapa de desarrollo, cuando se implementa el diseño en un producto de software; etapa de prueba de funcionamiento, donde se emula y simula el producto ajustando detalles, se instala en equipos reales y se evalúa el rendimiento, y posteriormente se evalúa el potencial de éxito; y finalmente, en la etapa de entrega, se define el canal de distribución Palabras clave: comunicación móvil; servicio de información; software de código abierto.

Introduction: This article is the result of research entitled “Signal processing system for the detection of people in agglomerations in areas of public space in the city of Cúcuta”, developed at the Universidad Francisco de Paula Santander in 2020.Problem: The high percentage of false positives and false negatives in people detection processes makes decision making in video surveillance, tracking and tracing applications complex. Objective: To determine which technique for the detection of people presents better results in terms of respon-se time and detection hits.Methodology: Two techniques for the detection of people in uncontrolled environments are validated in Python with videos taken inside the Universidad Francisco de Paula Santander: Background subtraction and the YOLO algorithm.Results: With the background subtraction technique, we obtained a hit rate of 84.07 % and an average response time of 0.815 seconds. Likewise, with the YOLO algorithm the hit rate and average response time are 90% and 4.59 seconds respectively.Conclusion: It is possible to infer the use of the background subtraction technique in hardware tools such as the Pi 3B+ Raspberry board for processes in which the analysis of information in real time is prioritized, while the YOLO algorithm presents the characteristics required in the processes in which the information is analyzed after the acquisition of the image.Originality: Through this research, aspects required for the real-time analysis of information obtained in pro-cesses of people detection in uncontrolled environments were analyzed. Limitations: The analyzed videos were taken only at the Universidad Francisco de Paula Santander. Also, the Raspberry Pi 3B+ board overheats when processing the video images, due to the full resource requirement of the device.

El artículo presenta el desarrollo e implementación de una aplicación para teléfonos inteligentes, que supervisa y controla un proceso industrial a través del sistema embebido Raspberry, conectado a Internet mediante el protocolo de intérprete de órdenes seguras. El sistema integra las ventajas de la instrumentación virtual y la movilidad, con el objetivo de mejorar los procesos de producción y la competitividad de las empresas. La aplicación fue elaborada con la metodología para el desarrollo de aplicaciones móviles, que contempla las fases de análisis, diseño, desarrollo, pruebas de funcionamiento y entrega. Además, la aplicación fue utilizada en una planta piloto para verificar su correcto funcionamiento y rendimiento en un entorno real para evaluar su usabilidad. Se concluye que la aplicación tiene potencial de éxito para ser implementada a gran escala, siendo de fácil manipulación, atractiva y eficiente.