886 research outputs found

    Mediación socioformativa: del aprendizaje a la formación integral

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    Los cambios acelerados de las últimas décadas, el desarrollo tecnológico y los grandes retos de la humanidad exigen a la educación una transformación a fondo, basada en la mejora de los procesos que se gestan desde las instituciones formadoras de docentes, los programas de actualización del magisterio, las universidades, los planes de estudio que se imparten en los diversos niveles y, ante todo, en los estilos de interacción que se manifiestan dentro y fuera de las aulas entre los estudiantes y educadores (Tobón et al., 2015). Todo esto, desde una visión sistémica conlleva un espíritu de transformación, de centrar la formación de los ciudadanos del siglo XXI en la resolución de problemas del contexto, superando la linealidad, fragmentación del conocimiento y el dominio de contenidos (Tobón et al., 2014)

    EVALUACIÓN DE LA PROMOCIÓN DEL CRECIMIENTO DE CYNODON DACTYLON L. POR RIZOBACTERIAS PRODUCTORAS DE FITOHORMONAS AISLADAS DE UN SUELO CONTAMINADO CON HIDROCARBUROS DERIVADOS DEL PETRÓLEO

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    The selection of plant growth-promotingrhizobacteria (PGPR) can be based on the in vitro analysis of their auxin-producingand growth-promoting capabilities. Thisstudy determined the intrinsic productionof indole acetic acid (IAA) by rhizobacteriaisolated from petroleum-contaminated soiland tested its potential for growth promotion. The three isolated rhizobacteria (I,II and III) were high producers of indoleacetic acid in vitro. Cynodon dactylonL. was inoculated with these isolates inhydroponic systems. The Rhizobacteriumspp. strains I and II showed plant growthpromotion without the addition of Trp (acommon precursor in the biosynthesis ofIAA), whereas strain III required the addition of Trp to promote foliar developmentin C. dactylon.El analizar rizobacterias por su potencialin vitro de producción de auxinas puedeproveer de una base rentable para la selección de cepas efectivas, particularmente siesta capacidad se emplea en combinacióncon el análisis de su actividad promotoradel crecimiento. Este estudio consistió enla caracterización de la producción intrínseca de rizobacterias aisladas de un suelocontaminado con hidrocarburos derivadosdel petróleo de producir ácido indolacéticoy el efecto de éstas sobre el crecimientoin vitro de Cynodon dactylon L, inoculada con estas rizobacterias en sistemashidropónicos. Las rizobacterias aisladasI, II y III resultaron altas productoras invitro de ácido indolacético. Se evidenció también la promoción del crecimientode las plantas de Cynodon dactylon L.con la inoculación de las rizobacterias Iy II. En experimentos con la adición detriptofano al medio y la inoculación conla rizobacteria III se observó la accióndirecta de la presencia del precursor enla biosíntesis de ácido indolacético quefavoreció el desarrollo radical y foliar delas plantas

    Exposure to secondhand and thirdhand smoke in private vehicles: Measurements in air and dust samples

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    Background: This study aimed to estimate airborne nicotine concentrations and nicotine, cotinine, and tobaccospecific nitrosamines (TSNAs) in settled dust from private cars in Spain and the UK. Methods: We measured vapor-phase nicotine concentrations in a convenience sample of 45 private cars from Spain (N = 30) and the UK (N = 15) in 2017-2018. We recruited non-smoking drivers (n = 20), smoking drivers who do not smoke inside the car (n = 15), and smoking drivers who smoke inside (n = 10). Nicotine, cotinine, and three TSNAs (NNK, NNN, NNA) were also measured in settled dust in a random subsample (n = 20). We computed medians and interquartile ranges (IQR) of secondhand smoke (SHS) and thirdhand smoke (THS) compounds according to the drivers' profile. Results: 24-h samples yielded median airborne nicotine concentrations below the limit of quantification (LOQ) (IQR

    Pervasive gaps in Amazonian ecological research

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    Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

    Pervasive gaps in Amazonian ecological research

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    Measurement of the top quark forward-backward production asymmetry and the anomalous chromoelectric and chromomagnetic moments in pp collisions at √s = 13 TeV

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    Abstract The parton-level top quark (t) forward-backward asymmetry and the anomalous chromoelectric (d̂ t) and chromomagnetic (μ̂ t) moments have been measured using LHC pp collisions at a center-of-mass energy of 13 TeV, collected in the CMS detector in a data sample corresponding to an integrated luminosity of 35.9 fb−1. The linearized variable AFB(1) is used to approximate the asymmetry. Candidate t t ¯ events decaying to a muon or electron and jets in final states with low and high Lorentz boosts are selected and reconstructed using a fit of the kinematic distributions of the decay products to those expected for t t ¯ final states. The values found for the parameters are AFB(1)=0.048−0.087+0.095(stat)−0.029+0.020(syst),μ̂t=−0.024−0.009+0.013(stat)−0.011+0.016(syst), and a limit is placed on the magnitude of | d̂ t| < 0.03 at 95% confidence level. [Figure not available: see fulltext.

    MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV

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    Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe

    Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

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    A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

    Measurement of prompt open-charm production cross sections in proton-proton collisions at root s=13 TeV

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    The production cross sections for prompt open-charm mesons in proton-proton collisions at a center-of-mass energy of 13TeV are reported. The measurement is performed using a data sample collected by the CMS experiment corresponding to an integrated luminosity of 29 nb(-1). The differential production cross sections of the D*(+/-), D-+/-, and D-0 ((D) over bar (0)) mesons are presented in ranges of transverse momentum and pseudorapidity 4 < p(T) < 100 GeV and vertical bar eta vertical bar < 2.1, respectively. The results are compared to several theoretical calculations and to previous measurements.Peer reviewe

    Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

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    A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV
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