1,712 research outputs found

    PolyGloT: A Personalized and Gamified eTutoring System

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    The digital age is changing the role of educators and pushing for a paradigm shift in the education system as a whole. Growing demand for general and specialized education inside and outside classrooms is at the heart of this rising trend. In modern, heterogeneous learning environments, the one-size-fits-all approach is proven to be fundamentally flawed. Individualization through adaptivity is, therefore, crucial to nurture individual potential and address accessibility needs and neurodiversity. By formalizing a learning framework that takes into account all these different aspects, we aim to define and implement an open, content-agnostic, and extensible eTutoring platform to design and consume adaptive and gamified learning experiences. Adaptive technology supplementing teaching can extend the reach of every teacher, making it possible to scale 1-1 learning experiences. There are many successful existing technologies available but they come with fixed environments that are not always suitable for the targeted audiences of the course material. This paper presents PolyGloT, a system able to help teachers to design and implement a gamified and adaptive learning paths. Through it we address some important issues including the engagement, fairness, and effectiveness of learning environments. We do not only propose an innovative platform that could foster the learning process of different disciplines, but it could also help teachers and instructors in organizing learning material in an easy-access repositoryComment: 6 pages; 5 figure

    Optimising the data-collection time of a large-scale data-acquisition system

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    Data-acquisition systems are a fundamental component of modern scientific experiments. Large-scale experiments, particularly in the field of particle physics, comprise millions of sensors and produce petabytes of data per day. Their data-acquisition systems digitise, collect, filter, and store experimental signals for later analysis. The performance and reliability of these systems are critical to the operation of the experiment: insufficient performance and failures result in the loss of valuable scientific data. By its very nature, data acquisition is a synchronous many-to-one operation: every time a phenomenon is observed by the experiment, data from its various sensors must be assembled into a single coherent dataset. This characteristic yields a particularly challenging traffic pattern for computer networks dedicated to data acquisition. If no corrective measures are taken, this pattern, known as incast, results in a significant underutilisation of the network resources, with a direct impact on a data-acquisition systems' throughput. This thesis presents effective and feasible approaches to maximising network utilisation in data-acquisition systems, avoiding the incast problem without sacrificing throughput. Rather than using abstract models, it focuses on an existing large-scale experiment, used as a case-study: the ATLAS detector at the Large Hadron Collider. First, the impact of incast on data-acquisition performance is characterised through a series of measurements performed on the actual data-acquisition system of the ATLAS experiment. As the size of the data sent synchronously by multiple sources to the same destination grows past the size of the network buffers, the throughput falls. A simple but effective mitigation is proposed and tested: at the application-layer, the data-collection receivers can limit the number of senders they simultaneously collect data from. This solution recovers a large part of the throughput lost to incast, but introduces some performance losses of its own. Further investigations are enabled by the development of a complete packet-level model of the ATLAS data-acquisition network in an event-based simulation framework. Comparing real-world measurements and simulation results, the model is shown to be accurate enough to be used for studying the incast phenomenon in a data-acquisition system. Leveraging the simulation model, various optimisations are analysed. The focus is kept on practical software changes, that can realistically be deployed on otherwise unmodified existing systems. Receiver-side traffic-shaping, incast- and traffic-shaping-aware work scheduling policies, tuning of TCP's timeouts, and centralised network packet injection scheduling are evaluated alone and in combination. Used together, the first three techniques result in a very significant increase of the system's throughput, which gets within 10% of the ideal maximum performance, even with a high network traffic load

    Single-step deposition of hexamethyldisiloxane surface gradient coatings with a high amplitude of water contact angles over a polyethylene foil

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    AbstractOne interesting category of nano‐ and micro‐engineered surfaces is surface gradients, which allow the controlled optimization of biointerfaces at a small scale in an extended area length. Plasma coatings offer a large diversity of functionalities at the nanoscale, accompanied by high chemical stability and adhesion on a variety of substrates at ambient temperature. Atmospheric‐pressure plasma‐assisted deposition could be employed for the generation of surface gradients on thermosensitive materials. In this study, a corona plasma jet is used to deposit polydimethylsiloxane/SiO2‐like surface gradients on polyethylene foil by varying the O2 concentration in the discharge during the movement of the plasma source. We obtained, in a single‐step approach, gradient coatings along a length of ∼10 cm, with a gradual variation of both chemistry and surface energy

    A 5'-region polymorphism modulates promoter activity of the tumor suppressor gene MFSD2A

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    <p>Abstract</p> <p>Background</p> <p>The MFSD2A gene maps within a linkage disequilibrium block containing the MYCL1-<it>EcoRI </it>polymorphism associated with prognosis and survival in lung cancer patients. Survival discrepancies between Asians and Caucasians point to ethnic differences in allelic frequencies of the functional genetic variations.</p> <p>Results</p> <p>Analysis of three single-nucleotide polymorphisms (SNPs) mapping in the MFSD2A 5'-regulatory region using a luciferase reporter system showed that SNP rs12072037, in linkage disequilibrium with the MYCL1-<it>EcoRI </it>polymorphism and polymorphic in Asians but not in Caucasians, modulated transcriptional activity of the MFSD2A promoter in cell lines expressing AHR and ARNT transcription factors, which potentially bind to the SNP site.</p> <p>Conclusion</p> <p>SNP rs12072037 modulates MFSD2A promoter activity and thus might affect MFSD2A levels in normal lung and in lung tumors, representing a candidate ethnically specific genetic factor underlying the association between the MYCL1 locus and lung cancer patients' survival.</p

    Plasma and Aerosols: Challenges, Opportunities and Perspectives

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    The interaction of plasmas and liquid aerosols offers special advantages and opens new perspectives for plasma\u2013liquid applications. The paper focuses on the key research challenges and potential of plasma-aerosol interaction at atmospheric pressure in several fields, outlining opportunities and benefits in terms of process tuning and throughputs. After a short overview of the recent achievements in plasma\u2013liquid field, the possible application benefits from aerosol injection in combination with plasma discharge are listed and discussed. Since the nature of the chemicophysical plasma-droplet interactions is still unclear, a multidisciplinary approach is recommended to overcome the current lack of knowledge and to open the plasma communities to scientists from other fields, already active in biphasic systems diagnostic. In this perspective, a better understanding of the high chemical reactivity of gas\u2013liquid reactions will bring new opportunities for plasma assisted in-situ and on-demand reactive species production and material processing

    Isotopic constraints on contamination processes in the Tonian Goiás Stratiform Complex

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    The Tonian Goiás Stratiform Complex (TGSC, Goiás, central Brazil), is one of the largest mafic-ultramafic layered complexes in the world, emplaced during the geotectonic events that led to the Gondwana accretion. In this study, we present trace elements and in-situ U/Pb-Lu-Hf analyses of zircons and 87Sr/86Sr ratios of plagioclases from anorthosites and gabbros of the TGSC. Although formed by three isolated bodies (Cana Brava,Niquelândia and Barro Alto), and characterized by a Lower and Upper Sequence (LS and US), our new U/Pb zircon data confirm recent geochemical, geochronological, and structural evidences that the TGSC has originated from a single intrusive body in the Neoproterozoic. New Hf and Sr isotope ratios construe a complex contamination history for the TGSC,with different geochemical signatures in the two sequences. The low Hf and high Sr isotope ratios of the Lower Sequence (εHf(t) from−4.2 down to −27.5; 87Sr/86Sr=0.706605–0.729226), suggest the presence of a crustal component and are consistent with contamination from meta-pelitic and calc-silicate rocks found as xenoliths within the Seuence. The more radiogenic Hf isotope ratios and low Sr isotope composition of the Upper Sequence (εHf(t) from 11.3 down to −8.4; 87Sr/86Sr=0.702368–0.702452), suggest a contamination from mantle-derived metabasalts in agreement with the occurrences of amphibolite xenoliths in the US stratigraphy. The differential contamination of the two sequences is explained by the intrusion of the TGSC in a stratified crust dominated bymetasedimentary rocks in its deeper part andmetavolcanics at shallower levels. Moreover, the differential thermal gradient in the two crystallizing sequences might have contributed to the preservation and recrystallization of inherited zircon grains in the US and total dissolution or magmatic overgrowth of the LS zircons via melt/rock reaction processes

    New U-Pb SHRIMP-II zircon intrusion ages of the Cana Brava and Barro Alto layered complexes, central Brazil: constraints on the genesis and evolution of the Tonian Goias Stratiform Complex

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    The Cana Brava, Niquelândia and Barro Alto complexes (Goiás, central Brazil) are three of the largest mafic-ultramafic layered complexes in the world and their origin has been a matter of debate for several decades. One hypothesis suggests that Niquelândia and Barro Alto were both formed by two distinct igneous events at 1.3 Ga and at 790Ma and were later overlapped during tectonic exhumation at 650 Ma; according to this reconstruction Cana Brava belongs to the youngest intrusion at 790 Ma. A second hypothesis suggests that the three complexes formed during the same event. Here we provide new U-Pb SHRIMP-II zircon ages for the Cana Brava and Barro Alto complexes, constraining their intrusion age to the Neoproterozoic (between 770 and 800 Ma), coeval with Niquelândia. A review of new and literature ages indicate that these complexes formed during a single igneous event andwere notmodified by regional metamorphism.We propose that the complexes represent fragments of the larger Tonian Goiás Stratiform Complex, which was likely part of a back-arc environment connected to the formation of the GoiásMagmatic Arc at about 790Ma, later disrupted and accreted to the São Francisco craton

    MFSD2A is a novel lung tumor suppressor gene modulating cell cycle and matrix attachment

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    <p>Abstract</p> <p>Background</p> <p>MFSD2A (major facilitator superfamily domain containing 2) gene maps on chromosome 1p34 within a linkage disequilibrium block containing genetic elements associated with progression of lung cancer.</p> <p>Results</p> <p>Here we show that MFSD2A expression is strongly downregulated in non-small cell lung cancer cell lines of different histotypes and in primary lung adenocarcinomas. Experimental modulation of MFSD2A in lung cancer cells is associated with alteration of mRNA levels of genes involved in cell cycle control and interaction with the extracellular matrix. Exogenous expression of MFSD2A in lung cancer cells induced a G1 block, impaired adhesion and migration <it>in vitro</it>, and significantly reduced tumor colony number <it>in vitro </it>(4- to 27-fold, P < 0.0001) and tumor volume <it>in vivo </it>(~3-fold, P < 0.0001). siRNA knockdown studies in normal human bronchial epithelial cells confirmed the role of MFSD2A in G1 regulation.</p> <p>Conclusion</p> <p>Together these data suggest that MFSD2A is a novel lung cancer tumor suppressor gene that regulates cell cycle progression and matrix attachment.</p

    Remote sensing-based estimation of gross primary production in a subalpine grassland

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    This study investigates the performances in a terrestrial ecosystem of gross primary production (GPP) estimation of a suite of spectral vegetation indexes (VIs) that can be computed from currently orbiting platforms. Vegetation indexes were computed from near-surface field spectroscopy measurements collected using an automatic system designed for high temporal frequency acquisition of spectral measurements in the visible near-infrared region. Spectral observations were collected for two consecutive years in Italy in a subalpine grassland equipped with an eddy covariance (EC) flux tower that provides continuous measurements of net ecosystem carbon dioxide (CO2) exchange (NEE) and the derived GPP. Different VIs were calculated based on ESA-MERIS and NASA-MODIS spectral bands and correlated with biophysical (Leaf area index, LAI; fraction of photosynthetically active radiation intercepted by green vegetation, f IPARg), biochemical (chlorophyll concentration) and ecophysiological (green light-use efficiency, LUEg) canopy variables. In this study, the normalized difference vegetation index (NDVI) was the index best correlated with LAI and f IPARg (r = 0.90 and 0.95, respectively), the MERIS terrestrial chlorophyll index (MTCI) with leaf chlorophyll content (r = 0.91) and the photochemical reflectance index (PRI551), computed as (R531 −R551)/(R531 +R551) with LUEg (r = 0.64). Subsequently, these VIs were used to estimate GPP using different modelling solutions based on Monteith’s lightuse efficiency model describing the GPP as driven by the photosynthetically active radiation absorbed by green vegetation (APARg) and by the efficiency (") with which plants use the absorbed radiation to fix carbon via photosynthesis. Results show that GPP can be successfully modelled with a combination of VIs and meteorological data or VIs only. Vegetation indexes designed to be more sensitive to chlorophyll content explained most of the variability in GPP in the ecosystem investigated, characterised by a strong seasonal dynamic of GPP. Accuracy in GPP estimation slightly improves when taking into account high frequency modulations of GPP driven by incident PAR or modelling LUEg with the PRI in model formulation. Similar results were obtained for both measured daily VIs and VIs obtained as 16-day composite time series and then downscaled from the compositing period to daily scale (resampled data). However, the use of resampled data rather than measured daily input data decreases the accuracy of the total GPP estimation on an annual basis.JRC.H.4-Monitoring Agricultural Resource
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