77 research outputs found

    Effective fuel temperature of wwer-1000

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    The main temperature characteristics of a pressurized water reactor are distinguished, supporting its safety and reliable operation. The special role of the uranium fuel effective temperature is emphasized and the accuracy of the analytical determination of the power effect is increased. The calculation of the temperature distribution along the radius of the fuel rod was carried out taking into account the temperature dependence of the thermal conductivity UO2. The design procedure was corrected for using the Finca-Ronchi dependence for the thermal conductivity of 95% density of the theoretical one

    Nuevas formas de asesorar y apoyar a los centros educativos

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    Symposium coordinador por el Prof. Jesús Domingo, donde se describen cuatro experiencias que describen nuevas formas de asesorar y apoyar a los centros educativos: a) Los procesos de asesoramiento: la experiencia de ADEME; b) Proyecto ATLÁNTIDA: educación y cultura democráticas. Procesos de formación de la ciudadanía; c) Ayudando a nuestros centros a mejorar; y d) Innovación, cultura y poder en las instituciones educativas. Un estudio de caso. Se hace un balance general y se evalúan los alcances y las limitaciones encontradas

    Structure, morphology, adhesion and in vitro biological evaluation of antibacterial multi-layer HA-Ag/SiO2/TiN/Ti coatings obtained by RF magnetron sputtering for biomedical applications

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    [EN] Biocompatible and antibacterial multi-layer coatings of hydroxyapatite (HA)-Ag/SiO2/TiN/Ti were obtained on the Ti-6Al-4V alloy, by means of the magnetron sputtering technique. During characterization of the coatings, the chemical composition was evaluated by energy dispersive X-ray spectroscopy and the phase analysis was carried out by X-ray diffraction. The morphology of the coatings was observed by field emission scanning electron microscopy, while transmission electron microscopy was used to appreciate their structure. The adhesion of the coatings to the substrate was evaluated by micro scratch test. The in vitro biological response was evaluated in terms of cytotoxicity, adhesion and differentiation of mouse mesenchymal stem cells, as well as adhesion and bacterial viability of Staphylococcus aureus strain. Through the compositional study carried out, the deposition of the HA phase was verified, with a Ca/P ratio close to 1.67 and the characteristic diffraction peaks of this compound. The structural study of the coatings evidenced the obtention of multi-layer architectures. The use of an intermediate SiO2/TiN/Ti trilayer was found to improve adhesion between HA-Ag and the substrate by 84%. Finally, the in vitro biological tests carried out indicated a potentially non-toxic character in the coatings. Additionally, an antibacterial effect was registered at low concentrations of Ag (3.0.co;2-3Lalueza, P., Monzón, M., Arruebo, M., & Santamaría, J. (2011). Bactericidal effects of different silver-containing materials. Materials Research Bulletin, 46(11), 2070-2076. doi:10.1016/j.materresbull.2011.06.041Peetsch, A., Greulich, C., Braun, D., Stroetges, C., Rehage, H., Siebers, B., … Epple, M. (2013). Silver-doped calcium phosphate nanoparticles: Synthesis, characterization, and toxic effects toward mammalian and prokaryotic cells. Colloids and Surfaces B: Biointerfaces, 102, 724-729. doi:10.1016/j.colsurfb.2012.09.040Yanovska, A. A., Stanislavov, A. S., Sukhodub, L. B., Kuznetsov, V. N., Illiashenko, V. Y., Danilchenko, S. N., & Sukhodub, L. F. (2014). Silver-doped hydroxyapatite coatings formed on Ti–6Al–4V substrates and their characterization. Materials Science and Engineering: C, 36, 215-220. doi:10.1016/j.msec.2013.12.011DeVasConCellos, P., Bose, S., Beyenal, H., Bandyopadhyay, A., & Zirkle, L. G. (2012). Antimicrobial particulate silver coatings on stainless steel implants for fracture management. Materials Science and Engineering: C, 32(5), 1112-1120. doi:10.1016/j.msec.2012.02.020VALLETREGI, M. (2004). Calcium phosphates as substitution of bone tissues. Progress in Solid State Chemistry, 32(1-2), 1-31. doi:10.1016/j.progsolidstchem.2004.07.001Surmenev, R. A., Surmeneva, M. A., Evdokimov, K. E., Pichugin, V. F., Peitsch, T., & Epple, M. (2011). The influence of the deposition parameters on the properties of an rf-magnetron-deposited nanostructured calcium phosphate coating and a possible growth mechanism. Surface and Coatings Technology, 205(12), 3600-3606. doi:10.1016/j.surfcoat.2010.12.039Surmeneva, M. A., Sharonova, A. A., Chernousova, S., Prymak, O., Loza, K., Tkachev, M. S., … Surmenev, R. A. (2017). Incorporation of silver nanoparticles into magnetron-sputtered calcium phosphate layers on titanium as an antibacterial coating. Colloids and Surfaces B: Biointerfaces, 156, 104-113. doi:10.1016/j.colsurfb.2017.05.016Mohseni, E., Zalnezhad, E., Bushroa, A. R., Abdel Magid Hamouda, Goh, B. T., & Yoon, G. H. (2015). Ti/TiN/HA coating on Ti–6Al–4V for biomedical applications. Ceramics International, 41(10), 14447-14457. doi:10.1016/j.ceramint.2015.07.081Ghasemi, S., Shanaghi, A., & Chu, P. K. (2017). Nano mechanical and wear properties of multi-layer Ti/TiN coatings deposited on Al 7075 by high-vacuum magnetron sputtering. Thin Solid Films, 638, 96-104. doi:10.1016/j.tsf.2017.07.049Hamdi, D. A., Jiang, Z.-T., No, K., Rahman, M. M., Lee, P.-C., Truc, L. N. T., … Dlugogorski, B. Z. (2019). Biocompatibility study of multi-layered hydroxyapatite coatings synthesized on Ti-6Al-4V alloys by RF magnetron sputtering for prosthetic-orthopaedic implant applications. Applied Surface Science, 463, 292-299. doi:10.1016/j.apsusc.2018.08.157Qi, J., Yang, Y., Zhou, M., Chen, Z., & Chen, K. (2019). Effect of transition layer on the performance of hydroxyapatite/titanium nitride coating developed on Ti-6Al-4V alloy by magnetron sputtering. Ceramics International, 45(4), 4863-4869. doi:10.1016/j.ceramint.2018.11.183Lenis, J. A., Hurtado, F. M., Gómez, M. A., & Bolívar, F. J. (2019). Effect of thermal treatment on structure, phase and mechanical properties of hydroxyapatite thin films grown by RF magnetron sputtering. Thin Solid Films, 669, 571-578. doi:10.1016/j.tsf.2018.11.045Lenis, J. A., Gómez, M. A., & Bolívar, F. J. (2019). Effect of deposition temperature and target-substrate distance on the structure, phases, mechanical and tribological properties of multi-layer HA-Ag coatings obtained by RF magnetron sputtering. Surface and Coatings Technology, 378, 124936. doi:10.1016/j.surfcoat.2019.124936Sofronia, A. M., Baies, R., Anghel, E. M., Marinescu, C. A., & Tanasescu, S. (2014). Thermal and structural characterization of synthetic and natural nanocrystalline hydroxyapatite. Materials Science and Engineering: C, 43, 153-163. doi:10.1016/j.msec.2014.07.023Lenis, J. A., Bejarano, G., Rico, P., Ribelles, J. L. G., & Bolívar, F. J. (2019). Development of multilayer Hydroxyapatite - Ag/TiN-Ti coatings deposited by radio frequency magnetron sputtering with potential application in the biomedical field. Surface and Coatings Technology, 377, 124856. doi:10.1016/j.surfcoat.2019.06.097Lenis, J. A., Toro, L. J., & Bolívar, F. J. (2019). Multi-layer bactericidal silver - calcium phosphate coatings obtained by RF magnetron sputtering. Surface and Coatings Technology, 367, 203-211. doi:10.1016/j.surfcoat.2019.03.038Valverde, A., Pérez-Álvarez, L., Ruiz-Rubio, L., Pacha Olivenza, M. A., García Blanco, M. B., Díaz-Fuentes, M., & Vilas-Vilela, J. L. (2019). Antibacterial hyaluronic acid/chitosan multilayers onto smooth and micropatterned titanium surfaces. Carbohydrate Polymers, 207, 824-833. doi:10.1016/j.carbpol.2018.12.039Surmeneva, M. A., Chaikina, M. V., Zaikovskiy, V. I., Pichugin, V. F., Buck, V., Prymak, O., … Surmenev, R. A. (2013). The structure of an RF-magnetron sputter-deposited silicate-containing hydroxyapatite-based coating investigated by high-resolution techniques. Surface and Coatings Technology, 218, 39-46. doi:10.1016/j.surfcoat.2012.12.023Nelea, V., Morosanu, C., Iliescu, M., & Mihailescu, I. N. (2003). Microstructure and mechanical properties of hydroxyapatite thin films grown by RF magnetron sputtering. Surface and Coatings Technology, 173(2-3), 315-322. doi:10.1016/s0257-8972(03)00729-1Ding, S.-J., Ju, C.-P., & Lin, J.-H. C. (1999). Characterization of hydroxyapatite and titanium coatings sputtered on Ti-6Al-4V substrate. Journal of Biomedical Materials Research, 44(3), 266-279. doi:10.1002/(sici)1097-4636(19990305)44:33.0.co;2-4Ivanova, A. A., Surmeneva, M. A., Tyurin, A. I., Pirozhkova, T. S., Shuvarin, I. A., Prymak, O., … Surmenev, R. A. (2016). Fabrication and physico-mechanical properties of thin magnetron sputter deposited silver-containing hydroxyapatite films. Applied Surface Science, 360, 929-935. doi:10.1016/j.apsusc.2015.11.087Contreras Romero, E., Cortínez Osorio, J., Talamantes Soto, R., Hurtado Macías, A., & Gómez Botero, M. (2019). Microstructure, mechanical and tribological performance of nanostructured TiAlTaN-(TiAlN/TaN)n coatings: Understanding the effect of quaternary/multilayer volume fraction. Surface and Coatings Technology, 377, 124875. doi:10.1016/j.surfcoat.2019.07.086Deligianni, D. (2001). Effect of surface roughness of the titanium alloy Ti–6Al–4V on human bone marrow cell response and on protein adsorption. Biomaterials, 22(11), 1241-1251. doi:10.1016/s0142-9612(00)00274-xZareidoost, A., Yousefpour, M., Ghaseme, B., & Amanzadeh, A. (2012). The relationship of surface roughness and cell response of chemical surface modification of titanium. Journal of Materials Science: Materials in Medicine, 23(6), 1479-1488. doi:10.1007/s10856-012-4611-9Surmeneva, M. A., Tyurin, A. I., Mukhametkaliyev, T. M., Pirozhkova, T. S., Shuvarin, I. A., Syrtanov, M. S., & Surmenev, R. A. (2015). Enhancement of the mechanical properties of AZ31 magnesium alloy via nanostructured hydroxyapatite thin films fabricated via radio-frequency magnetron sputtering. Journal of the Mechanical Behavior of Biomedical Materials, 46, 127-136. doi:10.1016/j.jmbbm.2015.02.025Quirama, A., Echavarría, A. M., Meza, J. M., Osorio, J., & Bejarano G, G. (2017). Improvement of the mechanical behavior of the calcium phosphate coatings deposited onto Ti6Al4V alloy using an intermediate TiN/TiO2 bilayer. Vacuum, 146, 22-30. doi:10.1016/j.vacuum.2017.09.024Surmeneva, M. A., Kleinhans, C., Vacun, G., Kluger, P. J., Schönhaar, V., Müller, M., … Surmenev, R. A. (2015). Nano-hydroxyapatite-coated metal-ceramic composite of iron-tricalcium phosphate: Improving the surface wettability, adhesion and proliferation of mesenchymal stem cells in vitro. Colloids and Surfaces B: Biointerfaces, 135, 386-393. doi:10.1016/j.colsurfb.2015.07.057Chen, Y., Zheng, X., Xie, Y., Ji, H., Ding, C., Li, H., & Dai, K. (2010). Silver release from silver-containing hydroxyapatite coatings. Surface and Coatings Technology, 205(7), 1892-1896. doi:10.1016/j.surfcoat.2010.08.073Actis, L., Gaviria, L., Guda, T., & Ong, J. L. (2013). Antimicrobial surfaces for craniofacial implants: state of the art. Journal of the Korean Association of Oral and Maxillofacial Surgeons, 39(2), 43. doi:10.5125/jkaoms.2013.39.2.43Parvizi, J., Aggarwal, V., & Rasouli, M. (2013). Periprosthetic joint infection: Current concept. Indian Journal of Orthopaedics, 47(1), 10. doi:10.4103/0019-5413.106884Redey, S. A., Nardin, M., Bernache-Assolant, D., Rey, C., Delannoy, P., Sedel, L., & Marie, P. J. (2000). Behavior of human osteoblastic cells on stoichiometric hydroxyapatite and type A carbonate apatite: Role of surface energy. Journal of Biomedical Materials Research, 50(3), 353-364. doi:10.1002/(sici)1097-4636(20000605)50:33.0.co;2-cSpriano, S., Bosetti, M., Bronzoni, M., Vernè, E., Maina, G., Bergo, V., & Cannas, M. (2005). Surface properties and cell response of low metal ion release Ti-6Al-7Nb alloy after multi-step chemical and thermal treatments. Biomaterials, 26(11), 1219-1229. doi:10.1016/j.biomaterials.2004.04.026Vogler, E. A. (1999). Water and the acute biological response to surfaces. Journal of Biomaterials Science, Polymer Edition, 10(10), 1015-1045. doi:10.1163/156856299x00667Lim, J. Y., Liu, X., Vogler, E. A., & Donahue, H. J. (2004). Systematic variation in osteoblast adhesion and phenotype with substratum surface characteristics. Journal of Biomedical Materials Research, 68A(3), 504-512. doi:10.1002/jbm.a.20087Sengstock, C., Diendorf, J., Epple, M., Schildhauer, T. A., & Köller, M. (2014). Effect of silver nanoparticles on human mesenchymal stem cell differentiation. Beilstein Journal of Nanotechnology, 5, 2058-2069. doi:10.3762/bjnano.5.214Sahuquillo Arce, J. M., Iranzo Tatay, A., Llácer Luna, M., Sanchis Boix, Y., Guitán Deltell, J., González Barberá, E., … Gobernado Serrano, M. (2011). Estudio in vitro de las propiedades antimicrobianas de una espuma de poliuretano que libera iones de plata. Cirugía Española, 89(8), 532-538. doi:10.1016/j.ciresp.2011.02.015Jamuna-Thevi, K., Bakar, S. A., Ibrahim, S., Shahab, N., & Toff, M. R. M. (2011). Quantification of silver ion release, in vitro cytotoxicity and antibacterial properties of nanostuctured Ag doped TiO2 coatings on stainless steel deposited by RF magnetron sputtering. Vacuum, 86(3), 235-241. doi:10.1016/j.vacuum.2011.06.011Chernousova, S., & Epple, M. (2012). Silver as Antibacterial Agent: Ion, Nanoparticle, and Metal. Angewandte Chemie International Edition, 52(6), 1636-1653. doi:10.1002/anie.20120592

    Two-dimensional carbon-based conductive materials with dynamically controlled asymmetric Dirac cones

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    The design of two dimensional graphene-type materials with an anisotropic electron flow direction in the X- and Y-axes opens the door for the development of novel electronic materials with multiple functions in nanoelectronics. In the present work, we have studied the electronic transport properties of a new family of 2D graphene-graphyne hybrids presenting conformationally free phenylethylene subunits. This system ensures two different conductive pathways that are perpendicular to each other: an acene nanoribbon subunit, in the X-axis, with graphene-type conduction, and a free to rotate phenylethylene subunit, in the Y-axis, in which the magnitude of the conduction depends dynamically on the corresponding torsion angle. Our calculations have confirmed that this system presents two different conduction pathways, which are related to the presence of asymmetric Dirac-type cones. Moreover, the Dirac cones can be dynamically modified in the presence of an external gate electrode, which is unprecedented in the literatureWe thank the MICINN (project CTQ-2011.22455) and the Regional Government of Andalucía (project P09-FQM-04571) for financial support and the ‘Centro de Supercomputación de la Universidad de Granada (UGRGRID-CSIRC)’ for computation time. NF and DM thank MICINN for their research contract

    Conductance and application of organic molecule pairs as nanofuses

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    We propose that a pair of organic molecules can mimic the behavior of a macroscopic fuse at nanoscale, one component of the pair being the on state and the other the off state. For this task wemake use of density-functional theory to calculate the physical properties of selected molecules, which have also been synthesized by our team. By this means we obtain the transmission spectra and the current of the proposed devices, which allows us to compare the behavior of the on and off states.Of particular interest is the on/off switch ratios, defined as the current ratios of the on and off structures at the corresponding bias voltage. In a first stage, we examine the best linker between the device and the electrode for high on/off switch ratios. Once this is determined, we test the influence of the electron richness of the system to provide a high on/off switch ratio. The entire analysis is also supported by the molecular projected self-consistent Hamiltonian, which provides a good way of understanding the molecular behavior. All the calculations support that interesting on/off switch ratios of two orders of magnitude could be obtained with these prototypical nanofusesWe thank the Regional Government of Andalucía for financial support (Projects No. P06-FQM-01726 and No. P09-FQM-04571), the “Centro de Supercomputación de la Universidad de Granada,” and the “Centro de Computación Científica-UAM” for computation time. The authors are also grateful to the Spanish Secretaría de Estado de Universidades e Investigación, Ministerio de Educación y Ciencia, for financial support within research projects TEC2007-66812 and TEC2010-16211. N.F. thanks the Regional Government of Andalucía for her research contract, and LAC thanks the University of Granada for his research contrac

    Evaluation of a gelatin-based adhesive for historic paintings that incorporates citronella oil as an eco-friendly biocide

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    [EN] The presented study focuses on evaluating the efficiency of a gelatin-based product that incorporates a plasticizer (glycerol) and a biocide (citronella oil), proposed as an eco-friendly adhesive for polychrome decoration applied in different parts of the architectural complex of the Longshan Temple in Lukang (eighteenth century, Taiwan). Seven laboratory physico-chemical tests were performed: (a) viscosity measurement; (b) drying curves; (c) moisture content determination; (d) water vapor permeability test; (e) mechanical test; (f) adhesion test; (g) susceptibility to fungi colonization test, which provide information on the workability, water content and water barrier properties, as well as mechanical, adhesion, and the biocide properties of the proposed product. The obtained results indicate that the workability, mechanical and adhesive properties of the new adhesive are adequate. Permeability in polychromies is slightly reduced due to the additional barrier effect of the adhesive incorporated into the paint film. The efficiency of citronella oil for preventing the growth of fungus Aspergillus niger on paintings consolidated with the adhesive was also probed. In parallel to these laboratory trials, the micro-invasive tests carried out, using nanoindentation combined with atomic force microscopy (NI-AFM), provided direct evidence for the improvement in the mechanical properties induced by applying the new adhesive to the original polychromies.This work was supported by the Spanish Ministerio de Economia, Industria y Competitividad (MINECO), the Fondo Europeo de Desarrollo Regional (ERDF), and the Agencia Estatal de Investigacion (AEI).Lee, Y.; Martín Rey, S.; Osete Cortina, L.; Martín-Sánchez, I.; Domenech Carbo, MT.; Bolivar-Galiano, F. (2018). Evaluation of a gelatin-based adhesive for historic paintings that incorporates citronella oil as an eco-friendly biocide. Journal of Adhesion Science and Technology. 32(21):2320-2349. https://doi.org/10.1080/01694243.2018.1477411S23202349322

    Ecos de la academia: Revista de la Facultad de Educación, Ciencia y Tecnología - FECYT Nro 6

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    Ecos de la academia, Revista de la Facultad de Educación Ciencia y Tecnología es una publicación científica de la Universidad Técnica del Norte, con revisión por pares a doble ciego que publica artículos en idioma español, quichua, portugués e inglés. Se edita con una frecuencia semestral con dos números por año.En ella se divulgan trabajos originales e inéditos generados por los investigadores, docentes y estudiantes de la FECYT, y contribuciones de profesionales de instituciones docentes e investigativas dentro y fuera del país, con calidad, originalidad y relevancia en las áreas de ciencias sociales y tecnología aplicada.Modelos multidimensionales del bienestar en contextos de enseñanza- aprendizaje: una revisión sistemática. Nuevas tendencias para el área académica de la Publicidad en la zona 1 del Ecuador. Propuesta de un curso de escritura académica bajo la base de modelos experienciales. Aproximación al estudio de las emociones. Seguimiento a egresados y graduados para actualizar el perfil de egreso y profesional. Impacto de la Gerencia de Calidad en el clima organizacional en Educación Básica. Comunicación efectiva del gerente educativo orientada al manejo de conflictos en el personal docente. Meritocracia: Democratización o exclusión en el acceso a la educación superior en Ecuador. Asertividad y desempeño académico en estudiantes universitarios. La creatividad en la formación profesional. Aspectos metodológicos en el proceso de enseñanza- aprendizaje de la gimnasia en estudiantes de Educación Física. English Language Learning Interaction through Web 2.0 Technologies. La sistematización de la práctica educativa y su relación con la metodología de la investigación. El ozono y la oxigenación hiperbárica: una vía para mejorar la recuperación en lesiones deportivas. La labor tutorial: Independencia del aprendizaje en el contexto universitario. Motivación hacia la profesión docente en la Enseñanza Secundaria. El uso académico de Facebook y WhatsApp en estudiantes universitarios... La educación superior en Ecuador: situación actual y factores de mejora de la calidad. El Proyecto de Investigación “Imbabura Étnica”

    Seguimiento de las guías españolas para el manejo del asma por el médico de atención primaria: un estudio observacional ambispectivo

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    Objetivo Evaluar el grado de seguimiento de las recomendaciones de las versiones de la Guía española para el manejo del asma (GEMA 2009 y 2015) y su repercusión en el control de la enfermedad. Material y métodos Estudio observacional y ambispectivo realizado entre septiembre del 2015 y abril del 2016, en el que participaron 314 médicos de atención primaria y 2.864 pacientes. Resultados Utilizando datos retrospectivos, 81 de los 314 médicos (25, 8% [IC del 95%, 21, 3 a 30, 9]) comunicaron seguir las recomendaciones de la GEMA 2009. Al inicio del estudio, 88 de los 314 médicos (28, 0% [IC del 95%, 23, 4 a 33, 2]) seguían las recomendaciones de la GEMA 2015. El tener un asma mal controlada (OR 0, 19, IC del 95%, 0, 13 a 0, 28) y presentar un asma persistente grave al inicio del estudio (OR 0, 20, IC del 95%, 0, 12 a 0, 34) se asociaron negativamente con tener un asma bien controlada al final del seguimiento. Por el contrario, el seguimiento de las recomendaciones de la GEMA 2015 se asoció de manera positiva con una mayor posibilidad de que el paciente tuviera un asma bien controlada al final del periodo de seguimiento (OR 1, 70, IC del 95%, 1, 40 a 2, 06). Conclusiones El escaso seguimiento de las guías clínicas para el manejo del asma constituye un problema común entre los médicos de atención primaria. Un seguimiento de estas guías se asocia con un control mejor del asma. Existe la necesidad de actuaciones que puedan mejorar el seguimiento por parte de los médicos de atención primaria de las guías para el manejo del asma. Objective: To assess the degree of compliance with the recommendations of the 2009 and 2015 versions of the Spanish guidelines for managing asthma (Guía Española para el Manejo del Asma [GEMA]) and the effect of this compliance on controlling the disease. Material and methods: We conducted an observational ambispective study between September 2015 and April 2016 in which 314 primary care physicians and 2864 patients participated. Results: Using retrospective data, we found that 81 of the 314 physicians (25.8%; 95% CI 21.3–30.9) stated that they complied with the GEMA2009 recommendations. At the start of the study, 88 of the 314 physicians (28.0%; 95% CI 23.4–33.2) complied with the GEMA2015 recommendations. Poorly controlled asthma (OR, 0.19; 95% CI 0.13–0.28) and persistent severe asthma at the start of the study (OR, 0.20; 95% CI 0.12–0.34) were negatively associated with having well-controlled asthma by the end of the follow-up. In contrast, compliance with the GEMA2015 recommendations was positively associated with a greater likelihood that the patient would have well-controlled asthma by the end of the follow-up (OR, 1.70; 95% CI 1.40–2.06). Conclusions: Low compliance with the clinical guidelines for managing asthma is a common problem among primary care physicians. Compliance with these guidelines is associated with better asthma control. Actions need to be taken to improve primary care physician compliance with the asthma management guidelines
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