1,515 research outputs found

    A new Variable Curvature concept for Linear Fresnel Reflectors Solar Concentrating Systems

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    In a Linear Fresnel Reflector (LFR) solar concentrating system [1] a series of single axis linear reflectors target the sunrays to a longitudinal facedown receiver on top of a fixed structure. The LFR technology offers simplicity and reduced costs when compared with the standard Parabolic Trough technology, but it also suffers from reduced optical performance, especially with large incidence angles. The present preliminary study explores the possibilities of a variable curvature geometrical concept for a LFR that would achieve a more focused solar print over the receptor than in a traditional fixed geometry system.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Seasonal and spatial variability of rainfall redistribution under Scots pine and Downy oak forests in Mediterranean conditions

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    The large degree of temporal and spatial variability of throughfall input patterns may lead to significant changes in the volume of water that reach the soil in each location, and beyond in the hydrological response of forested hillslopes. To explore the role of vegetation in the temporal and spatial redistribution of rainfall in Mediterranean climatic conditions two contrasted stands were monitored. One is a Downy oak forest (Quercus pubescens) and the other is a Scots pine forest (Pinus sylvestris), both are located in the Vallcebre research catchments (NE Spain, 42º 12¿N, 1º 49¿E). These plots are representative of Mediterranean mountain areas with spontaneous afforestation by Scots pine as a consequence of the abandonment of agricultural terraces, formerly covered by Downy oaks. The monitoring design of each plot consists of a set of 20 automatic rain recorders and 40 automatic soil moisture probes located below the canopy. 100 hemispheric photographs of the canopy were used to place the instruments at representative locations (in terms of canopy cover) within the plot. Bulk rainfall, stemflow and meteorological conditions above the forest cover are also automatically recorded. Canopy cover as well as biometric characteristics of the plots are also regularly measured. This work presents the first results describing the variability of throughfall beneath each forest stand and compares the persistence of temporal patterns among stands, and for the oaks stand among the leafed and the leafless period. Furthermore, canopy structure, rainfall characteristics and meteorological conditions of rainfall events are evaluated as main drivers of throughfall redistribution

    The pivotal functionality of the amyloid protein TasA in bacillus physiology and fitness

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    Biofilms are complex bacterial communities formed on any virtual surface and composed of cells embedded in an extracellular matrix. Studies on Bacillus subtilis have demonstrated this tissue-like structure comprised of diverse exopolymeric substances (eps) including exopolysaccharides, the protein BslA, and TasA and TapA the two main components of the amyloid fibers that confer robustness to the architecture of the biofilm. It has been demonstrated that the genetic pathways involved in formation of biofilms are active in the interaction of B. subtilis with plant surfaces. Indeed, we previously showed that surfactin acts as a self-trigger of biofilm in the plant phylloplane, which connected with the suppressive activity of B. subtilis against phytopathogenic fungi. These findings led us to hypothesize a major contribution of the extracellular matrix in the ecology of B. subtilis in the poorly explore plant phylloplane. In this work, we show that the amyloid protein TasA has a meaningful role in adhesion and biofilm formation over the plant phylloplane, however, despite the inability of the tasA mutant to form a biofilm, it still retained a similar antagonistic activity compared to the wild type strain. An in-depth transcriptomic analysis of the mutant led us to find unexpected variations in the expression levels of over 300 genes, including the overexpression of: i) production of acetoin ii) secondary metabolites and non-ribosomal peptides iii) eps and other biofilm-related components and iv) general stress, among others. These findings suggested that besides the structural role, TasA might have a regulatory function on the physiological stage of the cells. Indeed, an allele of TasA unable to restore biofilm formation allowed us to separate both functions, supporting the importance of this functional amyloid in regulating bacterial physiology and fitness.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Percepción y Grado de satisfacción familiar con el programa de Mentorías Universitarias para ACIs MENTORAC UMA 2013-2014

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    En MENTORAC UMA se realizaron 17 talleres de enriquecimiento desde febrero a junio de 2014, dirigidos a alumnado de entre 14 y 17 años, identificado con altas capacidades intelectuales (ACIs). Las actividades fueron desarrolladas por 16 profesores universitarios, que actuaron de mentores. Al finalizar el programa en septiembre de 2014, se reunió a las familias de los 90 alumnos participantes y se diseñó ad hoc el Cuestionario de Valoración para familias Mentorac (CVF-M), para medir diferentes dimensiones como la satisfacción con el programa, el beneficio escolar, el aumento de la motivación académica, o el grado de confort intelectual y personal del alumnado asistente, entre otros aspectos. Los resultados muestran un alto grado de satisfacción general con el programa. Se presentan y discuten los beneficios que, según los padres y madres, han obtenido los alumnos asistentes, así como los aspectos de mejora que solicitaron las familias encuestadas.universidad de malaga, campus de excelencia inetrnacional andalucia tec

    Study of tyrosine and dopa enantiomers as tyrosinase substrates initiating L‐ and D‐melanogenesis pathways

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    Tyrosinase starts melanogenesis and determines its course, catalyzing the oxidation by molecular oxygen of tyrosine to dopa, and that of dopa to dopaquinone. Then, nonenzymatic coupling reactions lead to dopachrome, which evolves toward melanin. Recently, it has been reported that d‐tyrosine acts as tyrosinase inhibitor and depigmenting agent. The action of tyrosinase on the enantiomers of tyrosine (l‐tyrosine and d‐tyrosine) and dopa (l‐dopa and d‐dopa) was studied for the first time focusing on quantitative transient phase kinetics. Post‐steady‐state transient phase studies revealed that l‐dopachrome is formed more rapidly than d‐dopachrome. This is due to the lower values of Michaelis constants for l‐enantiomers than for d‐enantiomers, although the maximum rates are equal for both enantiomers. A deeper analysis of the inter‐steady‐state transient phase of monophenols demonstrated that the enantiomer d‐tyrosine causes a longer lag period and a lower steady‐state rate, than l‐tyrosine at the same concentration. Therefore, d‐melanogenesis from d‐tyrosine occurs more slowly than does l‐melanogenesis from l‐tyrosine, which suggests the apparent inhibition of melanin biosynthesis by d‐tyrosine. As conclusion, d‐tyrosine acts as a real substrate of tyrosinase, with low catalytic efficiency and, therefore, delays the formation of d‐melanin

    Timed mind maps using MINDMANAGER & MS-PROJECT for educational innovation

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    The adaptation to the European Higher Education Area (EHEA) is becoming a great challenge for the University Community, especially for its teaching and research staff, which is involved actively in the teaching-learning process. It is also inducing a paradigm change for lecturers and students. Among the methodologies used for processes of teaching innovation, system thinking plays an important role when working mainly with mind maps, and is focused to highlighting the essence of the knowledge, allowing its visual representation. In this paper, a method for using these mind maps for organizing a particular subject is explained. This organization is completed with the definition of duration, precedence relationships and resources for each of these activities, as well as with their corresponding monitoring. Mind maps are generated by means of the MINDMANAGER package whilst Ms-PROJECT is used for establishing tasks relationships, durations, resources, and monitoring. Summarizing, a procedure and the necessary set of applications for self organizing and managing (timed) scheduled teaching tasks has been described in this paper

    ¿Trabajo significativo o no significativo? El caso del egresado universitario español

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    La school-to-work transition ha adquirido un especial interés en la investigación como consecuencia de la alta segmentación laboral que se ha venido produciendo a nivel europeo en las últimas décadas, máxime en el sur de Europa. La dualidad del mercado laboral se manifiesta particularmente en grupos vulnerables como jóvenes y mujeres, generando situaciones de precariedad laboral y exclusión social. De hecho, lo anterior ocupa un lugar destacado dentro de los principales planes de acción europeos (e.g., Agenda 2030 de Desarrollo Sostenible de Naciones Unidas). Dada las consecuencias negativas que tiene la entrada al mercado laboral a través de trabajos de poca calidad, investigaciones previas se centran en analizar la school-to-work transition a través del concepto de “primer trabajo significativo” propuesto por Eurostat. No obstante, y aunque la educación universitaria es el nivel educativo que mayores garantías proporciona para su obtención, son escasos los trabajos que se centran en este colectivo. De esta forma, y tomando la teoría del mercado dual de trabajo como punto de partida, esta investigación analiza los determinantes académicos (tipo de universidad, área de conocimiento, educación financiera, estancia en el extranjero, prácticas curriculares y extracurriculares, trabajo estudiantil, habilidades TIC e idiomas) que contribuyen a la obtención de un trabajo significativo por parte del egresado universitario español en un contexto de gran dualidad laboral y desde una perspectiva de género, tanto a corto (tras su graduación) como a medio-largo plazo (a los 3-4 años de graduación). Asimismo, incluye por primera vez, hasta donde nuestro conocimiento alcanza, la adecuación formativa al puesto de trabajo en la definición de trabajo significativo. A nivel metodológico, se utilizan modelos de elección discreta con corrección del sesgo de selección a través de los datos contenidos en la última Encuesta de Inserción Laboral de Titulados Universitarios (EILU-2019).Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

    Detection of Relevant Heavy Metal Concentrations in Human Placental Tissue: Relationship between the Concentrations of Hg, As, Pb and Cd and the Diet of the Pregnant Woman

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    Heavy metals can cross the placental barrier and reach the fetal compartment, threatening fetal development. Pregnant women can acquire these through food, drinking water, toxic habits or simply by breathing polluted air. The placenta has been described as a biomarker of maternal and fetal exposure to different toxic elements. Objectives: The main objective of this study was to test the possible existence of heavy metal deposits (Pb, As, Cd and Hg) in the placentas of women who gave birth at term in our setting, analyzing the influence of daily life and dietary habits. Methods: We studied 103 placentas, obtained by consecutive sampling, of women that delivered in the Regional Maternity Hospital of Malaga between March and June, 2021. As, Cd and Pb concentrations were analyzed using mass spectrometry techniques. Hg concentration was studied according to US EPA method 7473. Women also answered a questionnaire with epidemiological variables. Results: Detectable concentrations were found in 14.56% [As], 44.6% [Cd], 81.5% [Pb] and 100% [Hg]. [Pb] and [As] correlated significantly (Spearman’s Rho of 0.91 and <0.001), as did [Hg] and [Cd] (Spearman’s Rho 0.256, p < 0.004). The [Pb] and [AS] concentrations were significantly higher in cases of tap water consumption. [Hg] concentrations predicted the birth weight of female newbornsThis research received no external funding. This article is part of Soledad Molina-Mesa’s doctoral thesis. Partial funding for open access charge: Universidad de Málag

    Spanish study of anticoagulation in haemodialysis

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    This study's objectives were to determine which anticoagulation methods are commonly used in patients who are undergoing haemodialysis (HD) in Spain, on what criteria do they depend, and the consequences arising from their use. MATERIAL AND METHOD: Ours was a cross-sectional study based on two types of surveys: a "HD Centre Survey" and a "Patient Survey". The first survey was answered by 87 adult HD units serving a total of 6093 patients, as well as 2 paediatric units. Among these units, 48.3% were part of the public health system and the remaining 51.7% units were part of the private health system. The patient survey analysed 758 patients who were chosen at random from among the aforementioned 78 HD units. RESULTs: A) HD Centre Survey: The majority of adult HD units (n=61, 70.2%) used both kinds of heparin, 19 of them (21.8%) only used LMWH and 7 of them (8%) only used UFH. The most frequently applied criteria for the use of LMWH were medical indications (83.3% of HD units) and ease of administration (29.5%). The most frequently used methods for adjusting the dosage were clotting of the circuit (88.2% of units), bleeding of the vascular access after disconnection (75.3%), and patient weight (57.6%). B) Patient Survey: The distribution of the types of heparin used was: UFH: 44.1%, LMWH: 51.5%, and dialysis without heparin in 4.4% of patients. LMWH was more frequently used in public medical centres (64.2% of patients) than in private medical centres (46.1%) (P<.001). LMWH was more frequently used in on-line haemodiafiltration (HF) than in high-flux HD (P<.001). Antiplatelet agents were given to 45.5% of patients, oral anticoagulants to 18.4% of patients, and both to 5% of patients. Additionally, 4.4% of patients had suffered bleeding complications during the previous week, and 1.9% of patients suffered thrombotic complications. Bleeding complications were more frequent in patients with oral anticoagulants (P=.001), although there was no association between the type of heparin and the occurrence of bleeding or thrombotic complications. CONCLUSIONS: We are able to conclude that there is a great amount of disparity in the criteria used for the medical prescription of anticoagulation in HD. It is advisable that each HD unit revise their own results as well as those from other centres, and possibly to create an Anticoagulation Guide in Haemodialysis
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