1,628 research outputs found

    CS, HC3N and CH3CCH multi-line analyses towards starburst galaxies. The evolution of cloud structures in the central regions of galaxies

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    We aim to study the properties of the dense molecular gas towards the inner few 100 pc of four nearby starburst galaxies dominated both by photo dissociation regions (M82) and large-scale shocks (NGC253, IC342 and Maffei2), and to relate the chemical and physical properties of the molecular clouds with the evolutionary stage of the nuclear starbursts. We have carried out multi-transitional observations and analyses of three dense gas molecular tracers, CS, HC3N and CH3CCH, using Boltzmann diagrams in order to determine the rotational temperatures and column densities of the dense gas, and using a Large Velocity Gradients model to calculate the H2 density structure in the molecular clouds. The CS and HC3N data indicate the presence of density gradients in the molecular clouds, showing similar excitation conditions, and suggesting that they arise from the same gas components. In M82, CH3CCH has the highest fractional abundance determined in a extragalactic source (10^-8). The density and the chemical gradients found in all galaxies can be explained in the framework of the starburst evolution. The young shock-dominatedstarburst galaxies, like presumably Maffei2, show a cloud structure with a rather uniform density and chemical composition which suggests low star formation activity. Molecular clouds in galaxies with starburst in an intermediate stage of evolution, such as NGC253 and IC342, show clouds with a large density contrast (two orders of magnitude) between the denser regions (cores) and the less dense regions (halos) of the molecular clouds and relatively constant chemical abundance. Finally, the galaxy with the most evolved starburst, M82, has clouds with a rather uniform density structure, large envelopes of atomic/molecular gas subjected to UV photodissociating radiation from young star clusters, and very different chemical abundances of HC3N and CH3CCH.Comment: 14 pages + 1 appendix of 2 pages; 7 figures. Accepted for publication in Astronomy and Astrophysic

    A lambda=3 mm molecular line survey of NGC1068. Chemical signatures of an AGN environment

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    We aimed to study the molecular composition of the interstellar medium (ISM) surrounding an Active Galactic Nucleus (AGN), by making an inventory of molecular species and their abundances, as well as to establish a chemical differentiation between starburst galaxies and AGN. We used the IRAM-30 m telescope to observe the central 1.5-2 kpc region of NGC1068, covering the frequencies between 86.2 GHz and 115.6 GHz. Using Boltzmann diagrams, we calculated the column densities of the detected molecules. We used a chemical model to reproduce the abundances found in the AGN, to determine the origin of each detected species, and to test the influence of UV fields, cosmic rays, and shocks on the ISM. We identified 24 different molecular species and isotopologues, among which HC3N, SO, N2H+, CH3CN, NS, 13CN, and HN13C are detected for the first time in NGC1068. We obtained the upper limits to the isotopic ratios 12C/13C=49, 16O/18O=177 and 32S/34S=5. Our chemical models suggest that the chemistry in the nucleus of NGC1068 is strongly influenced by cosmic rays, although high values of both cosmic rays and far ultraviolet (FUV) radiation fields also explain well the observations. The gas in the nucleus of NGC1068 has a different chemical composition as compared to starburst galaxies. The distinct physical processes dominating galaxy nuclei (e.g. C-shocks, UV fields, X-rays, cosmic rays) leave clear imprints in the chemistry of the gas, which allow to characterise the nucleus activity by its molecular abundances.Comment: 16 pages, 6 figures, 7 tables. Accepted for publication in Astronomy and Astrophysic

    Forgetting in chimpanzees (Pan troglodytes): What is the role of interference?

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    Humans are constantly acquiring new information and skills. However, forgetting is also a common phenomenon in our lives. Understanding the lability of memories is critical to appreciate how they are formed as well as forgotten. Here we investigate the lability of chimpanzees’ short-term memories and assess what factors cause forgetting in our closest relatives. In two experiments, chimpanzees were presented with a target task, which involved remembering a reward location, followed by the presentation of an interference task—requiring the recollection of a different reward location. The interference task could take place soon after the presentation of the target task or soon before the retrieval of the food locations. The results show that chimpanzees’ memories for the location of a reward in a target task were compromised by the presentation of a different food location in an interference task. Critically, the temporal location of the interference task did not significantly affect chimpanzees’ performance. These pattern of results were found for both Experiment 1—when the retention interval between the encoding and retrieval of the target task was 60 seconds- and Experiment 2—when the retention interval between the encoding and retrieval of the target task was 30 seconds. We argue that the temporal proximity of the to-be-remembered information and the interference item during encoding is the factor driving chimpanzees’ performance in the present studies

    The Politics of Walking: Rural Women Encounters with Space and Memoir

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    A group of elderly and retired women from a northern village in Spain (they call themselves las chicas, the girls), try gather every week to take a walk together. Assembling my ethnographic notes, I describe the walk and offer an analytical foray into the following questions: What can we learn about the rural and the relationship of these women with the rural? What is the specificity of walking here? Walking is a practice that has in this case a twofold capacity: walking creates a mobile space for visibility in in which rural women’s work is considered private, and thus, walking provides a precious inter-subjective space for relationality; and second, the walk enacts a particular archaeology of memoir. The landscape bears witness to the socioeconomic changes of the rural environment. Such memoirs are actualized in the walk. Finally, as las chicas walk, not only do they travel across space and time, their movement allows for a particular methodological engagement of the researcher with the methods of research. Mobilities often question what hinders mobilities. But here my question is, what is the walking telling us about both the rural and these women in the rural context

    Las Villas del Libro como oferta especializada del turismo cultural en pequeñas ciudades históricas. Propuesta de planificación turística en Astorga = Book Towns as a specific offer of cultural tourism in small historical cities. A tourism planning proposal for Astorga

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    La cultura ha evolucionado con el paso del tiempo al igual que lo han hecho las diferentes tipologías de turismo cultural. En este sentido, el TFG que presentamos introduce la función turística del patrimonio histórico, artístico y cultural, tanto en España como en Castilla y León y desarrolla una propuesta específica de turismo cultural en Astorga. Dentro de las tipologías del turismo cultural se encuentra el turismo literario que, a pesar de ser relativamente reciente en España, muestra un gran potencial de crecimiento, tanto en aquellos lugares relacionados directamente con la literatura española, como por ejemplo la Ruta del Quijote, como en poblaciones donde el libro se convierte en protagonista, como en Urueña, donde se ha llevado a cabo un proyecto denominado Villa del Libro, basado en el empleo de espacios públicos y privados para la compraventa de libros y desarrollo de eventos que tienen que ver con la literatura. Por ello, empleando como ejemplo el caso de Urueña, en este TFG se propone presentar Astorga, un municipio de la provincia de León, como Villa del Libro ya que, además de contar con un patrimonio histórico y cultural muy valioso, presenta ciertas características y un pasado ligado a las letras que podrían hacer de Astorga un destino literario

    Evaluation of misalignments within a concentrator photovoltaic module by the module optical analyzer: a case of study concerning temperature effects on the module performance

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    Instituto de Energía Solar, Universidad Politécnica de Madrid (IES-UPM) has developed a method [referred to as the luminescence inverse (LI) method] and equipment [called module optical analyzer (MOA)] to fast measure the optical-angular properties of a CPV module without illumination system nor module movement. This paper presents how the MOA can investigate the optical performance of concentrator photovoltaic (CPV) modules optical-angular performance (in particular, misalignments between the optical components comprising the module) at different temperature conditions

    Heavy neutral leptons from kaons in effective field theory

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    In the framework of the low-energy effective theory containing in addition to the Standard Model fields heavy neutral leptons (HNLs), we compute the decay rates of neutral and charged kaons into HNLs. We consider both lepton-number-conserving and lepton-number-violating four-fermion operators, taking into account also the contribution of active-heavy neutrino mixing. Assuming that the produced HNLs are long-lived, we perform simulations and calculate the sensitivities of future long-lived-particle (LLP) detectors at the high-luminosity LHC to the considered scenario. When applicable, we also recast the existing bounds on the minimal mixing case obtained by NA62, T2K, and PS191. Our findings show that for some of the effective operators considered the future LLP detectors, in particular, MATHUSLA and ANUBIS, will probe (i) new parts of the parameter space spanned by HNL mass and active-heavy neutrino mixing, and (ii) new-physics scales in excess of 20002000 TeV.Comment: Result figures have been updated and text was changed accordingl

    Narratives of learning in a permacultural cooperative: some inspiring ideas for Science Education in the light of Freire's pedagogy

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    In the last decades, agroecological and permacultural initiatives and organizations have grown. These initiatives attend to notions of food sovereignty and alternative models of agricultural production. The confluence of different actors and social initiatives through which experiences and knowledge of cultivating food are shared, and new ones are created, reveals a high educational potential. In light of impending global catastrophes such as climate change and pressing inequalities, new alternatives and diverse forms of sociability are necessary to open up possible futures for life on a damaged planet. Freirean approaches to science education must align with transdisciplinary social and political movements, and generate reflective practices and methods. This article addresses the case of an art and permaculture cooperative (APC) to analyze how communities work together to disrupt and dismantle inequities in science and education and make a more livable world. We offer a critical and contra-hegemonic pedagogical perspective on science education, one that forges new epistemic territories grounded in cooperation, art, permaculture, relationship, and diverse ecologies. The APC is the only one of its kind in Argentina. It has carried out its socio-ecological activities and interventions in ways that respect the characteristics of the natural ecosystem, agriculture and permaculture. We use narratives and case study methods to reveal how people’s subjective narratives give meaning to their experiences and learnings. The APC as a learning context has the potential to transform reality, promoting the development and strengthening of popular science education for liberation, one that honors diverse ecologies, and meaningfully addresses new socio-environmental challenges and concerns.Fil: Martin, Rocío Belén. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Villa Maria. Instituto Academico de Ciencias Humanas; ArgentinaFil: Palombo, Nahuel Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto Multidisciplinario de Biología Vegetal. Universidad Nacional de Córdoba. Facultad de Ciencias Exactas Físicas y Naturales. Instituto Multidisciplinario de Biología Vegetal; ArgentinaFil: Martinenco, Rebeca Mariel. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Villa Maria. Instituto Academico de Ciencias Humanas; ArgentinaFil: Manavella, Agustina Maria. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de Villa María. Instituto Académico Pedagógico de Ciencias Sociales; Argentin
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