957 research outputs found

    Modelo de innovación académica, de la Universidad Técnica Particular de Loja – Ecuador (UTPL)

    Get PDF
    Hoy en día, las universidades son consideradas actores vitales en los sistemas transnacionales; las nuevas estructuras sociales, económicas y políticas que se observan en la sociedad exigen cambios significativos en la gestión universitaria: innovación, nuevos mecanismos de producción del conocimiento, mayor interacción universidad-empresa-gobierno-sociedad, acuerdos de financiación, sistemas de acreditación, programas formativos adaptados a las exigencias del medio, profesores e investigadores competentes, uso de la Web 2.0, investigación aplicada desde la Universidad, estrategias de rendición de cuentas, así como la puesta en marcha de la integración de un Espacio Común de Educación Superior; América Latina, el Caribe y la Unión Europea se han comprometido a ser partícipes en la construcción de este Espacio que se prevé este listo en el año 2015. Una aspiración que, de llevarse a cabo, significaría un salto cualitativo y cuantitativo en el desarrollo de los países latinoamericanos y del Caribe. Por ello las universidades latinoamericanas debemos prepararnos para ese cambio y una forma de hacerlo es generar modelos universitarios que involucren la diversidad de elementos que conforman una universidad de calidad en el Siglo XXI.Peer Reviewe

    Technical solutions to prevent heat stress induced crop growth reduction for three climatic regions in Mexico

    Get PDF
    In the last 15 years a significant increase in greenhouse area has occurred in Mexico, from a modest 50 hectares in 1990 to over 2,000 hectares in 2004. The rapid increase in greenhouse area is a result of an attractive export market, USA. Mexican summer midday temperatures are well above crop optimum and cooling is needed if heat stress induced crop growth reduction is to be prevented. The objective of this study was to determine the effectiveness and feasibility of greenhouse cooling systems for tomato culture under desert, humid tropic and temperate Mexican weather conditions. These climate regions are represented by Mexicali, Merida and Huejutla respectively. The cooling systems included a variety of passive and active systems, which through an engineering design methodology were combined to suit the climate conditions of the 3 regions. The evaluation was conducted via simulation, taking into account the most important temperature effects on crop growth and yield. The results showed that the cooling systems were effective in decreasing heat stress to plants. Investment costs of greenhouse with cooling equipment were under USD 50 m-2 and operational costs were under USD 10 m-2 for all equipment combinations and treatments except for the humid tropic climate of Merida. Solutions for Merida were both economically and physically not feasible due to too high humidity levels. This model study clearly indicates that cooling is feasible in desert and moderate climate regions of Mexico but in humid tropic climate regions feasibility is a problem. Application of design methodology and design evaluation with help of simulation greatly contributed to pointing out effective and non-effective solutions to reduce heat stress in hot climates

    Compressive Object Tracking using Entangled Photons

    Get PDF
    We present a compressive sensing protocol that tracks a moving object by removing static components from a scene. The implementation is carried out on a ghost imaging scheme to minimize both the number of photons and the number of measurements required to form a quantum image of the tracked object. This procedure tracks an object at low light levels with fewer than 3% of the measurements required for a raster scan, permitting us to more effectively use the information content in each photon.Comment: 10 pages, 4 figure

    Evaluación del potencial de mitigación de las estrategias de adaptación implementadas en los Territorios Sostenibles Adaptados al Clima (TeSAC)

    Get PDF
    El propósito de este estudio fue identificar el patrón espacial de la erosión hídrica del suelo actual y potencial y determinar el efecto de la condiciones de clima (precipitación), cobertura, prácticas de conservación e implementación de estrategias de adaptación al cambio climático para la zona de estudio delimitada en el municipio de Popayán – Colombia y en el departamento de Matagalpa – Nicaragua, por medio de la ecuación de pérdida de suelo (USLE), la cual se rige por cinco factores: Factores de erosión del suelo (K), índice de erosión de lluvia y escurrimiento (R), cultivo/vegetación y factor de manejo (C), factor de prácticas de conservación (P) y factor topográfico (LS). Donde se logró identificar que el efecto de la cobertura de suelo y las estrategias de adaptación a largo plazo son un factor importante como medida de conservación del recurso suelo

    The Role of Aryl Hydrocarbon Receptor and Crosstalk with Estrogen Receptor in Response of Breast Cancer Cells to the Novel Antitumor Agents Benzothiazoles and Aminoflavone

    Get PDF
    Many estrogen-receptor- (ER-) expressing breast cancers become refractory to ER-based therapies. New antitumor drugs like aminoflavone (AF) and benzothiazoles (Bzs) have been developed and have exquisite antitumor activity in ER+MCF-7 and T47D cells and in a MCF-7 nude mouse model. ER(−) breast cancer cells like MDA-MB-231 are less susceptible. We previously found in MCF-7 cells that these drugs activate the aryl hydrocarbon receptor (AhR) via translocation to the nucleus, induction of AhR-specific DNA binding activity, and expression of CYP1A1, whose transcription is controlled by the AhR-ARNT transcription factor. CYP1A1 metabolizes AF and Bz to a species which directly or after further metabolism damages DNA. In contrast an AhR-deficient variant of MCF-7 or cells with predominantly nuclear AhR expression, such as MDA-MB 231, are resistant. Thus, these drugs, unlike other neoplastic agents, require AhR-mediated signaling to cause DNA damage. This is a new treatment strategy for breast cancers with intact AhR signaling

    COVID-19 policy analysis: labour structure dictates lockdown mobility behaviour

    Get PDF
    Countries and cities around the world have resorted to unprecedented mobility restrictions to combat COVID-19 transmission. Here we exploit a natural experiment whereby Colombian cities implemented varied lockdown policies based on ID number and gender to analyse the impact of these policies on urban mobility. Using mobile phone data, we find that the restrictiveness of cities' mobility quotas (the share of residents allowed out daily according to policy advice) does not correlate with mobility reduction. Instead, we find that larger, wealthier cities with more formalized and complex industrial structure experienced greater reductions in mobility. Within cities, wealthier residents are more likely to reduce mobility, and commuters are especially more likely to stay at home when their work is located in wealthy or commercially/industrially formalized neighbourhoods. Hence, our results indicate that cities' employment characteristics and work-from-home capabilities are the primary determinants of mobility reduction. This finding underscores the need for mitigations aimed at lower income/informal workers, and sheds light on critical dependencies between socio-economic classes in Latin American cities

    Microplastics in the Antarctic marine system: An emerging area of research

    Get PDF
    It was thought that the Southern Ocean was relatively free of microplastic contamination; however, recent studies and citizen science projects in the Southern Ocean have reported microplastics in deep-sea sediments and surface waters. Here we reviewed available information on microplastics (including macroplastics as a source of microplastics) in the Southern Ocean. We estimated primary microplastic concentrations from personal care products and laundry, and identified potential sources and routes of transmission into the region. Estimates showed the levels of microplastic pollution released into the region from ships and scientific research stations were likely to be negligible at the scale of the Southern Ocean, but may be significant on a local scale. This was demonstrated by the detection of the first microplastics in shallow benthic sediments close to a number of research stations on King George Island. Furthermore, our predictions of primary microplastic concentrations from local sources were five orders of magnitude lower than levels reported in published sampling surveys (assuming an even dispersal at the ocean surface). Sea surface transfer from lower latitudes may contribute, at an as yet unknown level, to Southern Ocean plastic concentrations. Acknowledging the lack of data describing microplastic origins, concentrations, distribution and impacts in the Southern Ocean, we highlight the urgent need for research, and call for routine, standardised monitoring in the Antarctic marine system

    Carbohydrate to Protein Ratio in Perennial Ryegrass: Effects of Defoliation Stage and Nitrogen Rate

    Get PDF
    In intensive grass-based systems, perennial ryegrass (Lolium perenne L) grazed at early stages has a high crude protein content (CP) and low water soluble carbohydrate (WSC) relative to animal requirements. This imbalance leads to low nitrogen (N) use efficiency and a large loss of N excreted to the environment (Dijkstra et al. 2011). Previous research has shown the importance of the WSC:PC ratio as a useful factor that determines the improvement of the animal’s performance in terms of nitrogen utilization (Cosgrove et al. 2007). However, little is known about how the management of defoliation at specific growth stages can modify the WSC:CP ratio and other nutritive parameters related to N use efficiency. The objective of this study was to determine the changes of WSC:CP ratio and other nutritive parameters related to N use efficiency in response to nitrogen fertilizer rate and defoliation frequency based on leaf stage

    Sustainable Biorefineries: What was Learned from the Design, Analysis and Implementation

    Get PDF
    Bioeconomies need sustainable technologies and strategies for biomass processing. One of the best ways to do that is to consider biorefineries as a practical way to achieve real developments in the industry for integral production of energy, food, feed and chemicals under an ideal dream of replacing today’s crude-oil and basically using the accessible biomass in the world as much as possible. Additionally, the existent biofuel facilities are constantly adding new processing lines without integral design strategies, and possibly repeating the past design and implementation errors in refineries based on crude-oil. In recent years, more as a fashion or tendency, these processing lines from biofuels industry have been integrated in a system called “biorefinery” and many sectors have supported this idea through policies to incentivize the development of the bio-based economies adopting this concept. The design of biorefineries is presented as a relevant topic due to the multiple processing paths that could be available to obtain a set of desirable products. However, after many scientific efforts in design through well validated methodologies the biorefineries currently are not working properly or are more close to a conventional standalone biomass processing. Some big facilities already implemented today as biorefineries are closed or working just as standalone process (biofuels plant), but not through a promising multiproduct biorefinery configuration for which the resulting design was developed. In this work, 13 biorefineries were analysed including 4 industrial cases that were implemented after specific design and different industrial plants that use different raw materials of renewable origin. To achieve this, different strategic cases were considered: raw materials with inherent logistics restrictions, technical, economic, environmental assessments together with social considerations and finally market restrictions. As a result, and based on different case studies (where these process engineering strategies where applied through conceptual design using Aspen Plus and Potential Environmental Impacts) the positive and negative lessons are discussed in detail. The main result is an overall learning from different cases of study for future design, analysis and implementation of new biorefineries with a real sustainability and avoiding a repetition of the same evolution that risky and controversial crude-oil refineries had
    corecore