269 research outputs found

    Recent Developments in Technology-Enhanced Learning: A Critical Assessment

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    Producción CientíficaOur societies are considered knowledge societies in which lifelong learning is becoming increasingly important. At the same time, digital technologies are entering almost every aspect of our lives and now play an important role in education. The last decade has seen numerous new developments in the field of technology-enhanced learning. In 2004, George Siemens presented connectivism as a learning theory for the digital age. His ideas inspired the creation of Massive Open Online Courses (MOOCs), which have recently received a great deal of attention. Theoretical works on the use of digital devices for learning have focused on the affordances users perceive in these devices. Design research has also shown us that learning environments enriched by digital technologies are extremely complex and should be viewed as learning ecologies. The discussions on connectivism and MOOCs, affordances of digital devices, and design research have taken place in different discourses that have paid hardly any attention to each other. It is important to point out, however, that the developments in technology-enhanced learning not only can but need to be related to each other.Nuestras sociedades son consideradas sociedades del conocimiento, donde el aprendizaje a lo largo de la vida obtiene cada vez más importancia. Al mismo tiempo, las tecnologías digitales forman parte de casi todos los aspectos de nuestra vida y juegan un papel importante en la educación. En la última década se han visto numerosos avances en el ámbito del aprendizaje enriquecido por la tecnología. En 2004, George Siemens presentó el conectivismo como teoría del aprendizaje para la era digital. Sus ideas inspiraron la creación de cursos online masivos abiertos (MOOCs), que han sido objeto de gran atención recientemente. La literatura científica relacionada con el uso de dispositivos digitales para el aprendizaje se ha centrado en las potencialidades que los usuarios perciben de estos dispositivos. La investigación del diseño también nos ha mostrado que los entornos de aprendizaje enriquecidos por la tecnología son complejos y deben ser vistos como ecologías de aprendizaje. Las discusiones sobre conectivismo y MOOCs, las potencialidades de los dispositivos digitales y la investigación del diseño han aparecido en diferentes discursos observados de manera aislada. En este sentido, es importante señalar que los avances en el aprendizaje enriquecido por la tecnología no solo pueden sino que deben mostrarse relacionados entre sí

    The 5 Objects Test: Normative data from a Spanish community sample

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    [EN]Objective: The objective of this study was to provide normative data for the 5 Objects Test in a large Spanish community sample, as well as some validity evidence. Methods: The sample was composed of 427 participants (of which 220 females, age 15 to 95 years old; educational level range: 2–17 years). Normative data are provided, as well as correlations with test scores from Benton Visual Retention test, Rey-Osterrieth Complex Figure and Mini Mental State Examination. Results: No association was found between delayed recall score and level of education, age or gender. Immediate recall score was correlated with age. Both immediate and delayed recall significantly correlated with the criteria, evidencing concurrent validity. Conclusions: It is recommended that the 5 Objects Test be used for assessing persons in primary care, including those from different linguistic backgrounds or with limited language use. Delayed recall scores are especially recommended given the lack of association with demographic variables

    Tribological behavior of oils additised with a phosphonium-derived ionic liquid compared to a commercial oil

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    Purpose: The purpose of this paper is to study the antifriction, antiwear and tribolayer formation properties of the trihexyltetradecylphosphonium bis(2,4,4-trimethylpentyl) phosphinate ionic liquid (IL) as additive at 1 wt.% in two base oils and their mixtures, comparing the results with those of a commercial oil. Design/methodology/approach: The mixture of the base oils used in the formulation of the commercial oil SAE 0W20 plus the IL was tested under rolling/sliding and reciprocating conditions to determine the so-called Stribeck curve, the tribolayer formation and the antifriction and antiwear behaviors. Findings: The use of this IL as additive in these oils does not change their viscosity; improves the antifriction and antiwear properties of the base oils, making equal or outperforming these properties of the SAE 0W20; and the thickness and formation rate of the tribolayer resulting from the IL-surface interaction is highly dependent on the type of base oil and influence on the friction and wear results. Originality/value: The use of this IL allows to replace partial or totally commercial antifriction and antiwear additives. Peer review: The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-05-2020-0179/

    Phosphonium-based ionic liquids as grease additives in rolling bearing tests

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    Two phosphonium-derived ionic liquids: trihexyltetradecylphosphonium bis(2-ethylhexyl)phosphate (IL1) and trihexyltetradecylphosphonium tricyanomethanide (IL2) were used as additives in lithium complex- (G1) and anhydrous calcium-based (G2) greases at 5 wt%. Friction torque and wear tests were performed using a modified four-ball machine for testing rolling bearings in order to determine the friction and wear reducing properties of these grease samples in a real component. The IL2 improved the friction reduction performance of both greases, especially G1. Both ILs improved the antiwear behaviour of grease G2. Grease G2 showed higher oxidation and thermal ageing levels than G1, but the addition of the ILs, IL2 in particular, improved this issue

    Cranberry-derived phenolic metabolites and urinary tract infections

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    Resumen del póster presentado a la 7th International Conference on Polyphenols and Health, celebrada en Tours (Francia) del 27 al 30 de octubre de 2015.The beneficial effects of cranbeny products against urinary tract infections (UTIs) have been attributed, at least partly, to their A-type proanthocyanidin (PAC) content. A-type PACs have shown uropathogenic Escherichia coli (UPEC)-anti-adhesive activity, although they are unlikely to appear in urine at relevant concentrations as they are poorly absorbed. One leading hypothesis is that PAC-derived metabolites present in urine would operate in the phase of UPEC adyherence to uroepithelial cells, preventing bacterial colonization. In addition to this, and as it is becoming evident that the intestine is a reservoir for uropathogenic bacteria, other hypothesis is that. A-type proanthocyanidins specifically decrease the transient intestinal colonisation b UPEC, consequently reducing the risk of UTI incidence. In any case, gut microbiota (and its inter-individual variability) seems to be an important factor to be considered. In this communication, we summarize our results from different approaches aimed to look into the mechanisms that are behind the protedive action of cranberry polyphenols against ITUs: 1)in vitro fermentations of cranbeny polyphenols with colonic microbiota, that were performed to access the microbial-derived metabolic profile of cranbeny polyphenols as well as their effect on gut microbiota survival, 2) an in vivo trial with model mouse intraurethral-inoculated wilh UPEC, that evaluated the effectiveness of cranbeny supplementation in bacterial infection as well as its impact on faecal phenolic metabolism and faecal microbiota, 3) testing the UPEC-antiadhesive capacity of cranbeny phenolic compounds and their metabolites in bladder epithelial cell culíures, and 4) ex vivo studies of UPEC-antiadhesive capacity of mice mines collected after cranbeny supplementation.Ministry of Economy and Competitiveness (MiNECO) (Projects AGL-2010-17499 and AGL2012-40172-C02-01) and the Comunidad Autónoma de Madrid (Project ALIBIRD S2013/ABI-2728), Spain.Peer Reviewe

    Comparative effects of A- and B-type proanthocyanidins in the prevention of urinary tract infection in mice

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    Resumen del póster presentado a la VI International Conference on Polyphenols and Health celebrada en Buenos Aires (Argentina) del 16 al 19 de octubre de 2013.Consumption of cranberry (Vaccinium macrocarpum) is widely recommended forprophylaxis against urinary tract infections (UTI) in women. Among cranberry components, A-type proanthocyanins would be implicated in these preventive effects against UTI. However, proanthocyanidins are poorly absorbed in the small intestine, but subjected to extensive biotransformation in the colon, although studies are almost restricted to B-type proanthocyanidins. Therefore, the hypothesis of this study is that urinary metabolome from of A-type and B-type proanthocyanidins-mainly derived from their colonic catabolism-differ,and only metabolites from the A-type procyanidins have protective effects against UTI. To test this hypothesis, JAXc3H/OuJ female mice previously fed with specific diet (control, 1% cranberry extract and 1% grape seed extract) for 2 weeks, were inoculated with the uropathogenic E. coli (ATCC 53503™) to provoke infection, and maintained 2 weeks more before being sacrificed. Urine samples were collected at different times and subjected to E.coli counting, leukocytary esterase and nitrites analyses, and mieloperoxidase task. Samples of kidney and bladder tissues were also collected for E. coli counting and histopathologic analysis. Additionally, the capacity of the urine samples to inhibit bacterial adherence was tested in the T24 bladder cell line (ATCC HTB4 ™).Peer reviewe

    Holistic screening of collapsing honey bee colonies in Spain: A case study

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    Background: Here we present a holistic screening of collapsing colonies from three professional apiaries in Spain. Colonies with typical honey bee depopulation symptoms were selected for multiple possible factors to reveal the causes of collapse. Results: Omnipresent were Nosema ceranae and Lake Sinai Virus. Moderate prevalences were found for Black Queen Cell Virus and trypanosomatids, whereas Deformed Wing Virus, Aphid Lethal Paralysis Virus strain Brookings and neogregarines were rarely detected. Other viruses, Nosema apis, Acarapis woodi and Varroa destructor were not detected. Palinologic study of pollen demonstrated that all colonies were foraging on wild vegetation. Consequently, the pesticide residue analysis was negative for neonicotinoids. The genetic analysis of trypanosomatids GAPDH gene, showed that there is a large genetic distance between Crithidia mellificae ATCC30254, an authenticated cell strain since 1974, and the rest of the presumed C. mellificae sequences obtained in our study or published. This means that the latter group corresponds to a highly differentiated taxon that should be renamed accordingly. Conclusion: The results of this study demonstrate that the drivers of colony collapse may differ between geographic regions with different environmental conditions, or with different beekeeping and agricultural practices. The role of other pathogens in colony collapse has to bee studied in future, especially trypanosomatids and neogregarines. Beside their pathological effect on honey bees, classification and taxonomy of these protozoan parasites should also be clarified
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