881 research outputs found

    From reflection to action. The experience RoadsMOOC, as educommunicative journey of personal and social transformation

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    Con la intención de experimentar con nuevas formas de aprendizaje a través de la Educomunicación y de los MOOCs sociales o sMOOC, creamos una experiencia de aprendizaje colaborativo y de empoderamiento individual y social, a través de nuestra propuesta “Road sMOOC: Un viaje Eduktransformador”, llevado a cabo en la Plataforma ECOLearning. La finalidad de este sMOOC ha sido emprender un viaje de descubrimiento personal y de alfabetización digital crítica, motivando a los participantes a que dejen aflorar su potencial transformador y que participen activamente en las redes sociales, generando así un aprendizaje colectivo y aumentando el impacto social de nuestras acciones. Se reflexiona sobre los autores que nos inspiraron, sobre lo que entendemos por Educomunicación transformadora y las posibilidades que ofrecen los sMOOC. Finalmente resumimos los objetivos, recursos creados, aprendizajes compartidos y conclusiones que surgen al co-crear una identidad colectiva y un espíritu de trabajo en comunidad como “Eduktransformers”.Intending to experiment with new ways of learning through Educommunication and social or sMOOC MOOCs, we create a collaborative learning experience and individual and social empowerment, through our proposal "Road sMOOC: A Eduktransformador trip" carried out in the Platform ECOLearning.The purpose of this sMOOC has been to embark on a journey of personal discovery and critical digital literacy, encouraging participants to stop bring out its transformative potential and actively participate in social networks, generating a collective learning and increasing the social impact of our actions. We reflect on the authors who inspired us, what we mean by transforming Educommunication and the possibilities offered by sMOOC. Finally, we summarize the objectives, created resources, shared learning and conclusions arising to co-create a collective identity and a spirit of community work as "Eduktransformers"

    Superspace calculation of the four-loop spectrum in N=6 supersymmetric Chern-Simons theories

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    Using N=2 superspace techniques we compute the four-loop spectrum of single trace operators in the SU(2) x SU(2) sector of ABJM and ABJ supersymmetric Chern-Simons theories. Our computation yields a four-loop contribution to the function h^2(\lambda) (and its ABJ generalization) in the magnon dispersion relation which has fixed maximum transcendentality and coincides with the findings in components given in the revised versions of arXiv:0908.2463 and arXiv:0912.3460. We also discuss possible scenarios for an all-loop function h^2(\lambda) that interpolates between weak and strong couplings.Comment: LaTeX, feynmp, 34 pages; v2: typos corrected, formulations improved, references adde

    Introduction. Traces of Terror, Signs of Trauma

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    The article introduces a collection of articles about the spatialization processes of memory of war in contemporary Europe. It is divided in three parts. The first part proposes a transdisciplinary perspective, which includes semiotics, to tackle the relations between space, heritage and cultural memory and to analyse memory narratives conveyed by places. An approach based on the investigation of "terrorscapes" (places with a high density of traces) is proposed. The second part delves on the notion of terrorscapes, focusing on the meaning of "terror" and on the shift of paradigm in European politics of memory after 1989. The third part deals with the European space of memory, questioning the possibility of construction of a shared European memory narrative on XX centuries wars. Last paragraph summarizes the contributions of the volume

    The Impact of the Introduction of Total Mesorectal Excision on Local Recurrence Rate and Survival in Rectal Cancer: Long-Term Results

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    Purpose: To investigate the influence of the introduction of total mesorectal excision (TME) on local recurrence rate and survival in patients with rectal cancer. Methods: A total of 171 consecutive patients underwent anterior or abdominoperineal resection for primary rectal cancer. When the TME technique was introduced, the clinical setting, including the surgeons, remained the same. Group 1 (1993-95, n=53) underwent conventional surgery and group 2 (1995-2001, n=118) underwent TME. All patients were followed for 7years or until death. Results: Between the two groups, no statistically significant differences were present with regards to patient-, treatment-, or tumor-related characteristics apart from the time point of radiotherapy. The total local recurrence rates were 11 of 53 (20.8%) in group 1 and 7 of 118 (5.9%) in group 2, and the rates of isolated local recurrences were 6 of 53 (11.3%) in group 1 and 2 of 118 (1.7%) in group 2. Both differences were highly statistically significant. The disease-free survival in groups 1 and 2 was 60.4 and 65.3% at 5years, and 58.5 and 65.3% at 7years, respectively. Excluding patients with synchronous or metachronous distant metastasis from the analysis, both the disease-free survival and the cancer-specific survival were statistically significantly better in group 2 than in group 1. No statistically significant difference between the two groups was detected regarding the overall survival. Conclusions: The introduction of TME led to an impressive reduction of the local recurrence rate. Survival is mainly determined by the occurrence of distant metastasis, but TME seems to improve survival in patients without systemic diseas

    U-Pb zircon SHRIMP data from the Cana Brava layered complex: new constraints for the mafic-ultramafic intrusions of Northern Goiás, Brazil

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    The Cana Brava Complex is the northernmost and less-known layered intrusion of a discontinuous belt of mafic-ultramafic massifs within the Brasilia Belt, which also comprises the Niquelândia and Barro Alto complexes. Available geochronological determination by means of different systematics (K/Ar, Ar/Ar, Rb/Sr, Sm/Nd and U/Pb) provide a range of possible ages (time span from 3.9 Ga to 450 Ma), hence a precise and statistically reliable age for the Cana Brava Complex is still lacking. Also, preliminary isotopic and geochemical data of the Cana Brava Complex suggest a significant crustal contamination, which could have affected bulk-rock Sr and Nd systematics resulting in meaningless age determinations. In this paper, we present new U-Pb SHRIMP zircon analyses from four samples of different units of the Cana Brava Complex which suggest that the intrusion occurred during the Neoproterozoic, between 800 and 780 Ma, i.e. at the same age of Niquelândia. Discordant older 206Pb/238U ages are provided by inherited zircons, and match the age of the metamorphism of the encasing Palmeirópolis Sequence

    Comparing the Cana Brava and Niquelândia complexes: large mafic-ultramafic intrusions in the lower crust and contamination processes

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    Mafic-ultramafic complexes offer a unique opportunity to study how intrusions of mantlederived melts growth into the deep crust and interact with the country rocks. The Cana Brava and Niquelândia complexes are two mafic-ultramafic bodies which outcrop within the Brasilia Belt (Goias, central Brazil) and that intruded the metavolcanicmetasedimentary sequences of Palmeiropolis and Indaianopolis during a Neoproterozoic continental rifting. The two complexes are parts, together with the Barro Alto complex, of a ~350 km NNE-trend belt of layered bodies which were exhumed during the Gondwana formation. New field, geochemical and isotopic data give new constraints on the model of growth of these complexes and the interactions between parent melts and the lower crust. Field evidences suggest that the complexes grow via multiple-melt intrusions under hyper- to subsolidus shear conditions. During the complex growth, the upper metavolcanic-metasedimentary sequence was delaminated and xenoliths were incorporated and deformed within the crystal mush. The increase of the 87Sr/86Sr(790) along the complex stratigraphy, coupled with a decrease of the εNd(790), provides evidences of strong crustal contamination by the embedded xenoliths. The enrichment in most incompatible elements (e.g. K, Ba and LREE) and hydrous phases (biotite and amphibole) in rocks containing more xenoliths supports also the crustal contamination. The almost linear trend of isotopic contamination suggests that this process involved all the magma colum, similarly to AFC. However, the increase abundance of incompatible elements and H2O contents toward xenoliths-rich bands provide for a local effect of contamination

    Activation of the receptor protein tyrosine kinase EphB4 in endometrial hyperplasia and endometrial carcinoma

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    Background: Members of the Eph family of tyrosine kinases have been implicated in embryonic pattern formation and vascular development; however, little is known about their role in the adult organism. We have observed estrogen-dependent EphB4 expression in the normal breast suggesting its implication in the hormone-controlled homeostasis of this organ. Since the endometrium is a similarly hormone dependent organ and endometrial carcinoma is thought to result from estrogenic stimulation, we have investigated EphB4 expression in normal human endometrium and during its carcinogenesis. Patients and methods: EphB4 expression was analyzed immunohistochemically in 26 normal endometrium specimens, 15 hyperplasias and 102 endometrioid adenocarcinomas and correlated with clinical and prognostic tumor characteristics. Results: In normal endometrial tissue no EphB4 protein was detected. Strikingly, we observed a drastic increase (P <0.0001) in the number of EphB4 protein-expressing glandular epithelial cells in the majority of hyperplasias and carcinomas. Moreover, we found a statistically highly significant positive correlation between EphB4 expression and post-menopausal stage of the patient (P = 0.007). Conclusions: These findings indicate that in the endometrium, EphB4 is an early indicator of malignant development and, thus, EphB4 may represent a potent tool for diagnosis and therapeutic interventio

    Life cycle assessment of hydrogen-powered city buses in the High V.LO-City project: integrating vehicle operation and refuelling infrastructure

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    During the project High V.LO-City, which ended in December 2019, 14 hydrogen fuel cell buses were operated in four European cities. This paper aims at presenting total emissions through the lifetime of fuel cell buses with different hydrogen production options, including the refuelling stations. The environmental assessment of such bus system is carried out using the life cycle assessment methodology. Three hydrogen production pathways are investigated: water electrolysis, chlor-alkali electrolysis and steam methane reforming. Fuel economy during bus operation is around 10.25&nbsp;KgH2/100&nbsp;km, and the refuelling station energy demand ranges between 7 and 9&nbsp;KWh/KgH2. To support the inventory stage, dedicated software tools were developed for collecting and processing a huge amount of bus data and refuelling station performance, for automating data entry and for impacts calculation. The results show that hydrogen-powered buses, compared to a diesel bus, have the potential to reduce emissions during the use phase, if renewables resources are used. On the other hand, impacts from the vehicle production, including battery pack and fuel cell stack, still dominate environmental load. Consequently, improving the emission profile of fuel cell bus system requires to promote clean electricity sources to supply a low-carbon hydrogen and to sharpen policy focus regarding life cycle management and to counter potential setbacks, in particular those related to problem shifting and to grid improvement. For hazardous emissions and resource use, the high energy intensity of mining and refining activities still poses challenges on how to further enhance the environmental advantages of fuel cells and battery packs

    Powerful Radio Sources in the Southern Sky. II. A Swift X-Ray Perspective

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    We recently constructed the G4Jy-3CRE, a catalog of extragalactic radio sources based on the GLEAM 4-Jy (G4Jy) sample, with the aim of increasing the number of powerful radio galaxies and quasars with similar selection criteria to those of the revised release of the Third Cambridge Catalog (3CR). The G4Jy-3CRE consists of a total of 264 radio sources mainly visible from the Southern Hemisphere. Here, we present an initial X-ray analysis of 89 G4Jy-3CRE radio sources with archival X-ray observations from the Neil Gehrels Swift Observatory. We reduced a total of 624 Swift observations, for about 0.9 Ms of integrated exposure time. We found X-ray counterparts for 59 radio sources belonging to the G4Jy-3CRE, nine of them showing extended X-ray emission. The remaining 30 sources do not show any X-ray emission associated with their radio cores. Our analysis demonstrates that X-ray snapshot observations, even if lacking uniform exposure times, as those carried out with Swift, allow us to (i) verify and/or refine the host galaxy identification; (ii) discover the extended X-ray emission around radio galaxies of the intracluster medium when harbored in galaxy clusters, as the case of G4Jy 1518 and G4Jy 1664; and (iii) detect X-ray radiation arising from their radio lobes, as for G4Jy 1863

    Sound velocities and single-crystal elasticity of hydrous Fo90 olivine to 12 GPa

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    Nominally anhydrous minerals (NAMs) may contain significant amounts of water and constitute an important reservoir for mantle hydrogen. The colloquial term ‘water’ in NAMs is related to the presence of hydroxyl-bearing (OH-) point defects in their crystal structure, where hydrogen is bonded to lattice oxygen and is charge-balanced by cation vacancies. This hydrous component may therefore have substantial effects on the thermoelastic parameters of NAMs, comparable to other major crystal-chemical substitutions (e.g., Fe, Al). Assessment of water concentrations in natural minerals from mantle xenoliths indicates that olivine commonly stores ~0 – 200 ppm of water. However, the lack of samples originating from depths exceeding ~250 km coupled with the rapid diffusion of hydrogen in olivine at magmatic temperatures makes the determination of the olivine water content in the upper mantle challenging. On the other hand, numerous experimental data show that, at pressures and temperatures corresponding to deep upper mantle conditions, the water storage capacity of olivine increases to 0.2 – 0.5 wt.%. Therefore, determining the elastic properties of olivine samples with more realistic water contents for deep upper mantle conditions may help in interpreting both seismic velocity anomalies in potentially hydrous regions of Earth's mantle as well as the observed seismic velocity and density contrasts across the 410-km discontinuity. Here, we report simultaneous single-crystal X-ray diffraction and Brillouin scattering experiments at room temperature up to 11.96(2) GPa on hydrous (0.20(3) wt.% H2O) Fo90 olivine to assess its full elastic tensor, and complement these results with a careful re-analysis of all the available single-crystal elasticity data from the literature for anhydrous Fo90 olivine. While the bulk (K) and shear (G) moduli of hydrous Fo90 olivine are virtually identical to those of the corresponding anhydrous phase, their pressure derivatives K´ and G´ are slightly larger, although consistent within mutual uncertainties. We then defined linear relations between the water concentration in Fo90 olivine, the elastic moduli and their pressure derivatives, which were then used to compute the sound velocities of Fo90 olivine with higher degrees of hydration. Even for water concentrations as high as 0.5 wt.%, the sound wave velocities of hydrous and anhydrous olivines were found to be identical within uncertainties at pressures corresponding to the base of the upper mantle. Contrary to previous claims, our data suggest that water in olivine is not seismically detectable, at least for contents consistent with deep upper mantle conditions. In addition to that, our data reveal that the hydration of olivine is unlikely to be a key factor in reconciling seismic velocity and density contrasts across the 410-km discontinuity with a pyrolitic mantle
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