51 research outputs found

    Propuesta didáctica sobre nutrición en educación primaria basada en experiencias significativas

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    Treball Final de Grau en Mestre o Mestra d'Educació Primària. Codi: MP1040. Curs acadèmic: 2018/2019La asignatura de ciencias naturales en las escuelas es una de las más problemáticas en cuanto se trata de hacer comprender a los alumnos y alumnas los contenidos curriculares, posiblemente provocado por no utilizar las metodologías adecuadas ni tener en cuenta las ideas previas y las preguntas que se hace el alumnado sobre lo que les rodea. En estas ciencias escolares se debe buscar, por encima de todo, potenciar la curiosidad, la observación, la investigación y el cuestionamiento sobre todo aquello que les rodea, ya que dará lugar a aprendizajes mucho más significativos. En este trabajo se han analizado algunas investigaciones sobre las dificultades que se encuentran en las clases de ciencias, tanto en docentes como en alumnado, con la intención de ofrecer herramientas que sirvan para mejorar el proceso de enseñanza-aprendizaje actual. Por ello, también se han creado tres secuencias didácticas de diferentes niveles para la enseñanza de la nutrición en todas las etapas de primaria con el fin de ofrecer una ayuda a otros docentes que quieran innovar y centrar las clases de ciencias naturales en el contexto, la experimentación y la investigación. Los niños y las niñas son curiosos por naturaleza y debemos aprovechar esta característica al máximo, utilizando metodologías donde ellos sean los protagonistas y los conceptos tengan sentido dentro de lo que vive el niño o la niña en su día a día.At school, the subject of natural sciences is one of the most problematic ones in terms of making students understand the course contents, probably due to the usage of inadequate methodologies or the fact of not taking into account the students’ previous ides and questions asked about their surroundings. When teaching these sciences, teachers must seek, above all, to enhance curiosity, observation, research and the questioning about everything that surrounds them as these will lead to a much more significant learning. In the present dissertation, different studies about the difficulties found in science classes, both in teachers and students, have been analyzed with the intention of offering tools that serve to improve the current teaching-learning process. Therefore, it has also been created three didactic sequences of different levels for the teaching of nutrition in all the stages of primary school, in order to offer help to other teachers who want to innovate and focus the natural sciences classes in the context, experimentation and research. Children are curious by nature and we must make the most of this characteristic by using methodologies where they are the protagonists and where the concepts make sense within what the child lives in their everyday life

    Holographic Lens Resolution Using the Convolution Theorem

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    The similarity between object and image of negative asymmetrical holographic lenses (HLs) stored in a low-toxicity photopolymer has been evaluated theoretically and experimentally. Asymmetrical experimental setups with negative focal lengths have been used to obtain HLs. For this purpose, the resolution of the HLs was calculated using the convolution theorem. A USAF 1951 test was used as an object and the impulse responses of the HLs, which in this case was the amplitude spread function (ASF), were obtained with two different methods: using a CCD sensor and a Hartmann Shack (HS) wavefront sensor. For a negative asymmetrically recorded HL a maximum resolution of 11.31 lp/mm was obtained. It was evaluated at 473 nm wavelength. A theoretical study of object-image similarity had carried out using the MSE (mean squared error) metric to evaluate the experimental results obtained quantitatively.This research was funded by Universidad de Alicante (UAFPU20-23); Generalitat Valenciana (CIDEXG/2022/60, CDEIGENT/2018/024, IDIFEDER/2021/014, PROMETEO/2021/006); Ministerio de Ciencia e Innovación (PID2019-106601RB-I00, PID2021-123124OB-I00)

    Holographic solar concentrators stored in an eco-friendly photopolymer

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    In this work it is shown the first characterization of holographic solar concentrators recorded in Biophotopol - one of the greenest photopolymers. Biophotopol is an acrylate-based and water-soluble photopolymer with good recycling properties. The composition of this photopolymer and their thickness are easily changeable, which implies an important advantage vs. others commercialized photopolymers. Good diffraction efficiency and wide acceptance angles are achieved on phase volume transmission holograms by using an optimized composition and thin layers. A curing stage with a white incoherent light has been performed to obtain high temporal stability together with a good diffraction efficiency. Finally, the performance of the holographic lenses as holographic solar concentrators has been evaluated with an electronic setup connected to a polycrystalline silicon photovoltaic cell and a high intensity solar simulator emitting a standard solar spectrum (AM1.5G).This work has financial support from: Ministerio de Ciencia e Innovación, Spain, under project PID2019-106601RB-I00 and FIS2017-82919-R/(MINECO/AE/FEDER, UE); Generalitat Valenciana, Spain, under project CDEIGENT/2018/024

    CCD and Hartmann-Shack wavefront sensor to analyse holographic lens resolution

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    Nowadays, the study and optimization of volume holographic lenses (HLs) stored in low-toxicity photopolymers have a great interest. HLs are now a component of optical imaging systems that are mostly used in head-mounted displays for virtual and augmented reality or as non-image systems in light deflectors and concentrators. One of the most important parameters used when working with imaging systems is the resolution of the optical system. In this work, the similarity between the object and image of negative asymmetrical HLs stored in a low-toxicity photopolymer named Biophotopol has been evaluated theoretically and experimentally. For this purpose, the resolution of the HLs was calculated using the Convolution Theorem. A USAF 1951 test was used as an object and the impulse responses of the HLs were obtained with two different sensors: CCD and Hartmann-Shack (HS) wavefront sensor. In addition, the resolution of the HLs has been obtained by two different methods: one using the Convolution Theorem, using both the CCD and the HS wavefront sensor, and the other by forming the USAF test image on the CCD sensor. Finally, a theoretical study of object-image similarity was carried out using the MSE (mean squared error) metric to evaluate the quantitative experimental results.This research was funded by Universidad de Alicante (UAFPU20-23); Generalitat Valenciana (CIDEXG/2022/60, IDIFEDER/2021/014, PROMETEO/2021/006); Ministerio de Ciencia e Innovación (PID2019-106601RB-I00, PID2021-123124OB-I00)

    Carbon dioxide activation assisted by a bis(chlorodimethylsilyl)cyclopentadienyl titanium compound

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    A great deal of interest has focused on the role of metal ions\ud as the active centers in the fixation of CO2 and its transformation. Activation of CO2 by hydroxo and oxo metal complexes to afford metal hydrogencarbonato and carbonato\ud species, respectively, is related to the function of the carbonic\ud anhydrase metalloenzyme, which catalyzes the physiologically\ud important hydration of CO2 to hydrogencarbonate

    Role of Circulating Angiotensin Converting Enzyme 2 in Left Ventricular Remodeling following Myocardial Infarction: A Prospective Controlled Study.

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    Angiotensin-converting enzyme 2 (ACE2) cleaves Angiotensin-II to Angiotensin-(1-7), a cardioprotective peptide. Serum soluble ACE2 (sACE2) activity is raised in chronic heart failure, suggesting a compensatory role in left ventricular dysfunction. Our aim was to study the relationship between sACE2 activity, infarct size, left ventricular systolic function and remodeling following ST-elevation myocardial infarction (STEMI). A contrast-enhanced cardiac magnetic resonance study was performed acutely in 95 patients with first STEMI and repeated at 6 months to measure LV end-diastolic volume index, ejection fraction and infarct size. Baseline sACE2 activities, measured by fluorescent enzymatic assay 24 to 48 hours and at 7 days from admission, were compared to that obtained in 22 matched controls. Patients showed higher sACE2 at baseline than controls (104.4 [87.4-134.8] vs 74.9 [62.8-87.5] RFU/µl/hr, p<0.001). At seven days, sACE2 activity significantly increased from baseline (115.5 [92.9-168.6] RFU/µl/hr, p<0.01). An inverse correlation between sACE2 activity with acute and follow-up ejection fraction was observed (r = −0.519, p<0.001; r = −0.453, p = 0.001, respectively). Additionally, sACE2 directly correlated with infarct size (r = 0.373, p<0.001). Both, infarct size (β = −0.470 [95%CI:−0.691:−0.248], p<0.001) and sACE2 at 7 days (β = −0.025 [95%CI:−0.048:−0.002], p = 0.030) were independent predictors of follow-up ejection fraction. Patients with sACE2 in the upper tertile had a 4.4 fold increase in the incidence of adverse left ventricular remodeling (95% confidence interval: 1.3 to 15.2, p = 0.027). In conclusion, serum sACE2 activity rises in relation to infarct size, left ventricular systolic dysfunction and is associated with the occurrence of left ventricular remodeling

    Shrinkage studies and optimization of multiplexed holographic lenses with high diffractive efficiency and wide angular response

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    Today, the advancement of optical systems that can harness clean and renewable energy sources is a major focus for researchers and innovators worldwide. As we strive to create a sustainable future, this challenge has become increasingly critical to our success. Fresnel lenses are widely used as traditional concentrators, but they have a small acceptance angle, and the reflective elements need continuous maintenance of the surface reflectivity. Transmitting Holographic Optical Elements (HOEs) are an alternative to conventional lenses because they are more economical and versatile. Their material is usually a flexible photopolymer so that the optical element can be attached to different types of support, depending on whether one type of handling is required or another, and they tend to have low weight and volume, as well as a simple way of manufacturing. In addition, also provide an extended focusing area which helps to protect solar cells from heating damage. A theoretical and experimental study on the shrinkage of multiplexed holographic lenses (MHL) that were stored in a low-toxicity photopolymer was carried out. To accomplish the study, a K-space tool was used. Furthermore, an optimization analysis of the angular distance between peaks was performed. To determine efficiency, an evaluation of the short-circuit current under solar illumination with varying incident reconstruction angles was done.This research was funded by Universidad de Alicante (UAFPU20-23); Generalitat Valenciana (CIDEXG/2022/60, IDIFEDER/2021/014, PROMETEO/2021/006); Ministerio de Ciencia e Innovación (PID2019-106601RB-I00, PID2021-123124OB-I00)

    Development of high efficiency and wide acceptance angle holographic solar concentrators for breakthrough photovoltaic applications

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    Solar concentrator systems represent an important challenge in our society for outstanding photovoltaic (PV) applications. Fresnel lenses or parabolic mirrors concentrate sunlight in a small solar cell surface. On the one hand, Fresnel lenses have an exceedingly small acceptance angle and require expensive tracking systems to follow the path of the Sun. On the other hand, conventional parabolic mirrors need periodic maintenance of the surface reflectivity. Holographic optical elements (HOEs) represent a suitable alternative to Fresnel lenses and solar reflectors, they are cheaper and more versatile. Particularly, multiplexed holographic solar concentrators (HSCs) give an insight into promising possibilities for Building-Integrated Concentrating PV (BICPV). A good trade-off between wide acceptance angle and high diffraction efficiency represents an important milestone in the area. Our research group obtained the higher acceptance angle in a multiplexed HSC design (Morales et. al. Opt. Express 30, 25366 (2022)). This design was composed of seven holographic multiplexed lenses in Biophotopol material with thick thickness, 197 μm. In the present work, more efficient holographic solar concentrators than previous works are shown. As far as we know, it has been obtained the best trade-off between high efficiency and wide acceptance angle HSC-PV solar cell systems.Generalitat Valenciana (CIDEXG/2022/60, IDIFEDER/2021/0.14, PROMETEO/2021/006); Ministerio de Ciencia e Innovación (PID2019-106601RB-I00; PID2021-123124OB-I00); Universidad de Alicante (UAFPU20-23)

    Quality and measurement aberrations on holographic lenses

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    Abstract: In this paper, we have evaluated the quality of holographic lenses stored in an environmentally friendly photopolymer. Optical quality metrics has been used to test the holographic lenses. The metrics values obtained shows that the negative asymmetrical holographic lenses have the best optical quality.Work funded by Ministerio de Ciencia, Innovación y Universidades, Spain, under project PID2019-106601RB-I00; Generalitat Valenciana, Spain, under projects CDEI-GENT/2018/024, PROMETEO/2021/006, and IDIFEDER/2021/014 (co-funded by European Union through the FEDER Programme); Universidad de Alicante, Spain: Predoctoral Fellowship FPU-UA to Tomás Lloret

    Potential bycatch impact on distinct sea turtle populations is dependent on fishing ground rather than gear type in the Mediterranean Sea

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    Bycatch is one of the main threats affecting marine megafauna worldwide, not only because of its prevalence, but also because the impact of high levels of bycatch in small oceanic regions may spread over whole oceans due to the complex dispersal patterns of bycaught species. Here, we use intrinsic and genetic markers to understand the impact of bycatch on the Atlantic and Mediterranean populations of the loggerhead turtle sharing the same foraging grounds in the western Mediterranean Sea. Turtles of Atlantic origin settle on the continental shelf later and at a larger size than turtles of Mediterranean origin and hence have been suggested to be more vulnerable to pelagic fishing gears, whereas those of Mediterranean origin would be more vulnerable to neritic ones. To assess whether this hypothesis holds true, we compared the genetic make-up of turtle bycatch from drifting longlines and bottom trawl/trammel nets in three different regions (eastern mainland Spain, southern Balearic Islands and southern Italy). A total of 176 incidentally caught turtles were considered, and size and habitat use, as revealed by stable isotopes, were incorporated to the analysis. No genetic, size or isotopic differences were found between turtles caught with drifting longlines and bottom trawl/trammel nets within any of the three regions. However, genetic, size and isotopic differences were detected among regions, regardless of the fishing gear. Thus, the population make-up of loggerhead bycatch depends on the area where the fishing operations are conducted, but not on the fishing gear used. Accordingly, the actual impact of loggerhead bycatch in the Mediterranean Sea will depend not only on the total number of turtles taken, but also on the geographic distribution of the fishing effort
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