1,744 research outputs found

    Background questionnaires of PISA: a study of the assessment indicators

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    The PISA assessment system has generated and continues to generate intense debate about its structure and usefulness. This article focuses on the context questionnaires as a way to analyze and understand the results properly. The objectives are to analyze the background indicators used in the different editions of the PISA tests, used in different studies and the results of these studies. An overview of the model used is provided to ensure that these indicators are no longer something that accompanies the performance test to reach their true meaning: jointly analyze the performance along with the variables that may be influencing the results. As methodology is used document analysis of publications related to PISA and results, as well as a semantic analysis of scientific work that has generated PISA. The results show that some indicators have remained throughout the various editions of PISA, while others have changed. The translation of a stable model in editions from PISA 2015 in which the most relevant items are included will undoubtedly facilitate the study of results at vertical and horizontal level. Thus, the importance of PISA context questionnaires established to properly understand their results and the need for more complex studies of multilevel or nested that normally used, generally based on descriptive statistics and / or percentagesThe PISA assessment system has generated and continues to generate intense debate about its structure and usefulness. This article focuses on the context questionnaires as a way to analyze and understand the results properly. The objectives are to analyze the context indicators used in the different editions of the PISA tests, used in different studies and the results of these studies. An overview of the model used is provided to ensure that these indicators are no longer something that accompanies the performance test to reach their true meaning: jointly analyze the performance along with the variables that may be influencing the results. As methodology is used document analysis of publications related to PISA and results, as well as a semantic analysis of scientific work that has generated PISA. The results show that some indicators have remained throughout the various editions of PISA, while others have changed. The translation of a stable model in editions from PISA 2015 in which the most relevant items are included will undoubtedly facilitate the study of results at vertical and horizontal level. Thus, the importance of PISA context questionnaires established to properly understand their results and the need for more complex studies of multilevel or nested that normally used, generally based on descriptive statistics and / or percentages

    A Cholinergic Synaptically Triggered Event Participates in the Generation of Persistent Activity Necessary for Eye Fixation

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    An exciting topic regarding integrative properties of the nervous system is how transient motor commands or brief sensory stimuli are able to evoke persistent neuronal changes, mainly as a sustained, tonic action potential firing. A persisting firing seems to be necessary for postural maintenance after a previous movement. We have studied in vitro and in vivo the generation of the persistent neuronal activity responsible for eye fixation after spontaneous eye movements. Rat sagittal brainstem slices were used for the intracellular recording of prepositus hypoglossi (PH) neurons and their synaptic activation from nearby paramedian pontine reticular formation (PPRF) neurons. Single electrical pulses applied to the PPRF showed a monosynaptic glutamatergic projection on PH neurons, acting on AMPA-kainate receptors. Train stimulation of the PPRF area evoked a sustained depolarization of PH neurons exceeding (by hundreds of milliseconds) stimulus duration. Both duration and amplitude of this sustained depolarization were linearly related to train frequency. The train-evoked sustained depolarization was the result of interaction between glutamatergic excitatory burst neurons and cholinergic mesopontine reticular fibers projecting onto PH neurons, because it was prevented by slice superfusion with cholinergic antagonists and mimicked by cholinergic agonists. As expected, microinjections of cholinergic antagonists in the PH nucleus of alert behaving cats evoked a gaze-holding deficit consisting of a re-centering drift of the eye after each saccade. These findings suggest that a slow, cholinergic, synaptically triggered event participates in the generation of persistent activity characteristic of PH neurons carrying eye position signals.Unión Europea Grants BI04-CT98-0546España, Ministerio de Ciencia PB98-0011, BFI2000-00936, BFI2000-1190, y BFI2002-0137

    Augmented Reality as a Tool for Promoting the Tourist Value of the Geological Heritage Around Natural Filming Locations: a Case Study in “Sad Hill” (The Good, the Bad and the Ugly Movie, Burgos, Spain)

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    This research was funded by projects Junta Castilla y Leon SA044G18, University of Salamanca USAL2017/46AC01, and Spanish Ministry of Economy and Competitiveness CGL2015-69919-R.Some natural scenes of films shooting contain landscapes and other elements that are part of the geological heritage, representing an added value for the growing cultural tourism that visits them. In the SE of Burgos province (Spain), near some filming locations of the classic western movie directed by Sergio Leone (1966), “The Good, the Bad and the Ugly”, we have assessed the Geological Heritage of 6 selected sites: (1) Dinosaur tracks; (2) Paleo-river structures preserved; (3) Fossil trees; (4) Sad Hill; (5) Marine Cretaceous fossils; and (6) La Yecla Gorge. Their tourist-cultural, scientific and educational values range from 775 points in La Yecla Gorge site to 450 in Marine Cretaceous fossils site. A virtual tour is presented implementing Augmented Reality on Google Earth with detailed but easily understanding descriptive information of each site, suggested activities for tourism and a free geoapp. The proposed technologies can enhance geotourism, favouring sustainable development and fostering attitudes and skills related to the tourist’s respect for nature.publishersversionpublishe

    The fish family Muraenidae: an ideal group for testing at small-scale the coherency of Macaronesia as a biogeographic unit, with the first report on separate fishery statistics

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    : The present study was conceptualized to study the muraenid species (moray eels) occurring around the volcanic archipelagos of the Azores, Madeira, Selvagens, Canary and Cabo Verde islands (eastern-central Atlantic). The biogeographic patterns of these species were analysed and compared. We then hypothesized that this fish family is an ideal group for testing at small-scale the coherency of Macaronesia and its direct biogeographic units: i.e. the Azores, Webbnesia and Cabo Verde, as proposed in recent scientific literature. Additionally, this paper provides for the first time separate fishery statistics for this group in the region that were analysed to contrast the biogeographic results.En prensa1,00

    Detect coastal disturbances and climate change effects in coralligenous community through sentinel stations

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    This study was implemented to assess the Sessile Bioindicators in Permanent Quadrats (SBPQ) underwater environmental alert method. The SBPQ is a non-invasive and low-cost protocol; it uses sessile target species (indicators) to detect environmental alterations (natural or anthropic) at either the local or global (i.e., climate change) scale and the intrusion of invasive species. The SBPQ focuses on the monitoring of preselected sessile and sensitive benthic species associated with rocky coralligenous habitats using permanent quadrats in underwater sentinel stations. The selected target species have been well documented as bioindicators that disappear in the absence of environmental stability. However, whether these species are good indicators of stability or, in contrast, suffer variations in long-term coverage has not been verified. The purpose of this study was to assess the part of the method based on the hypothesis that, over a long temporal series in a highly structured and biodiverse coralligenous assemblage, the cover of sensitive sessile species does not change over time if the environmental stability characterising the habitat is not altered. Over a ten-year period (2005-2014), the sublittoral sessile biota in the Straits of Gibraltar Natural Park on the southern Iberian Peninsula was monitored at a 28 m-deep underwater sentinel stations. Analyses of the coverages of target indicator species (i.e., Paramuricea clavata and Astroides calycularis) together with other accompanying sessile organisms based on the periodic superimposition of gridded images from horizontal and vertical rocky surfaces allowed us to assess the effectiveness of the method. We conclude that no alterations occurred during the study period; only minimal fluctuations in cover were detected, and the method is reliable for detecting biological changes in ecosystems found in other geographical areas containing the chosen indicator species at similar dominance levels

    Algoritmo Genético aplicado al problema de programación en procesos tecnológicos de maquinado con ambiente Flow Shop

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    Debido a las limitaciones de las técnicas de optimización convencionales, en el siguiente trabajo se presenta una metaheurística basada en un algoritmo genético (AG), para resolver problemas de programación de tipo flow shop, con el objetivo de minimizar el tiempo de finalización de todos los trabajos, más conocido como makespan. Este problema, considerado de difícil solución, es típico de la optimización combinatoria y se presenta en talleres con tecnología de maquinado, donde existen máquinas-herramientas convencionales y se fabrican diferentes tipos de piezas que tienen en común una misma ruta tecnológica (orden del proceso). La solución propuesta se probó con problemas clásicos publicados por otros autores, obteniéndose resultados satisfactorios en cuanto a la calidad de las soluciones encontradas y el tiempo de cómputo empleado

    Short-term effects of impurities in the CO2 stream injected into fractured carbonates.

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    After the Paris Agreement in which 195 countries are involved, the Carbon Capture and Storage (CCS) is now an accepted technology in the United Nations Framework Convention on Climate Change (UNFCCC). In Spain, Fundación Ciudad de la Energía (CIUDEN) has successfully completed the full CCS chain, being CO2 captured in the Technology Development Centre in Cubillos del Sil (León, Spain) whereas that it is geologically stored in a deep saline aquifer, formed by fractured carbonates with poor matrix porosity, located in the Technology Development Plant (TDP) at Hontomín (Burgos, Spain). The results of the field tests, in which up to 150 tons of CO2 and synthetic air (5 %v of N2 and O2) were co-injected on site, are analyzed in this paper comparing the operational parameters gained during the injection of impure CO2 (pressures, temperatures and flow ranges) with its corresponding baseline previously determined (i.e. 1,500 tons of pure CO2 were injected during the reservoir hydraulic characterization). Besides that, the geochemical reactivity analysis of impure CO2 injected in this saline aquifer and its correlation with the results from laboratory tests were assessed. As main conclusions from laboratory scale results, a porosity diminution was measured after the injection of CO2 with 5 %v of SO2; apart from that, without SO2, the effluent pH was in the range of 7-8 whereas in case of CO2 and SO2, a pH of 1-2 was obtained. Otherwise and focused on field scale tests, a density decrease was detected comparing the base case (pure CO2) with the CO2 injection containing 5.1 %v of synthetic air. On the other hand, Ca2+, SO42-, Mg2+ and K+ migration effects in the rock were also detected and analyzed

    IAA : Información y actualidad astronómica (2)

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    Sumario : Investigación: La misión Envisat.-- Una década de investigación con el telescopio espacial Hubble.-- Ventana Abierta: ¿Ciencias o letras?...Jose Carlos del Toro Iniesta.-- Charlas con...John Huchra.-- Especial: 25 años del IAA.-- Actualidad Científica: Plano a gran escala, tal vez, pero no euclídeo.-- Detección óptica de impactos en la cara oscura de la Luna.-- Actividades IAA.-- Agenda.N

    Assessment of targeted selective treatment criteria to control subclinical gastrointestinal nematode infections on sheep farms

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    Control of sheep gastrointestinal nematode (GIN) infections mostly relies on the use of anthelmintics. Refugia-based control strategies as targeted selective treatments (TST) can delay anthelmintic resistance development, but the optimal decision criteria for selecting individuals to be treated in subclinical infection scenarios remain unclear. The present study aimed to evaluate the suitability of body condition score (BCS) and faecal egg counts (FEC) as treatment indicators and to determine their optimized threshold values for treatment in TST by determining the relationships of BCS, FEC and anthelmintic treatment with several productive parameters in pre-mating and pre-partum periods at an individual level. Deworming in pre-mating period increased BCS gain, but its magnitude was directly associated with strongyle FEC before treatment. Deworming also increased fertility in ewes with BCS 400 epg before treatment. These results showed that FEC and especially BCS can be potential decision criteria for the implementation of TST in these types of scenarios. The TST scheme derived from the present results on the control of GIN infections should include anthelmintic treatment of ewes with BCS lower than ˜ 3 approximately five weeks before mating and lambing. In the pre-lambing period, treatment may be unnecessary if flock mean strongyle FEC is lower than ˜ 200 epg, as the proportion of ewes with individual FEC > 400 epg would be very low. The results suggest that implementation of this TST scheme would provide benefits, such as the improvement of productivity, a rational management of parasites in refugia, and preservation of future efficacy of anthelmintics, in comparison to traditional deworming schemes

    Feeding Habits of the Invasive Weakfish (Cynoscion regalis) in the Gulf of Cadiz

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    Weakfish (Cynoscion regalis) has been present in Iberian waters since at least 2011, when it was first recorded in the Guadalquivir estuary. Little is known about the preferences and feeding strategies of weakfish outside of its native range; therefore, in this work, we carried out a comprehensive study between March 2021 and September 2021 to elucidate these matters. In total, the stomach contents of 300 fish were examined. The fish were collected in spring and summer in the Gulf of Cadiz (Spain), with individuals caught ranging from 185 to 590 mm in total length. Due to the sampling period and size range of individuals, ontogenic and seasonal (spring–summer) variations in the diet were also explored. Overall, fish and crustaceans were the dominant groups consumed by weakfish. The European anchovy (Engraulis encrasicolus) and caramote prawn (Penaeus kerathurus) were the most abundant prey in each group. While no differences were found in the percentage of occurrence of fish in the non-empty stomachs analyzed in spring and summer (83%), a small increase was found in the percentage of occurrence of crustaceans from spring (20%) to summer (29%). In addition, the analysis of the results also suggested that weakfish of smaller sizes feed more on crustaceans, while bigger individuals feed mainly on fish. Our findings indicate that weakfish is a fully carnivorous species with a preference for fish. All this is in line with the diet and strategy that weakfish exhibits in its native area and with the first assessment made with the existing population in the Sado Estuary (Portugal). In recent years, due to the appearance of non-native species, there is increasing concern among local fishermen and the local authorities about the reduction in captures of certain species such as Penaeus kerathurus; therefore, this study could help researchers to understand the role of weakfish concerning this matter. The present study contributes to the ecological knowledge about this species in the Iberian Peninsula and the Gulf of Cadiz, helping the local authorities to establish, if needed, an appropriate management program to cope with this recently introduced species
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