957 research outputs found

    The stability of the optical flux variation gradient for 3C120

    Full text link
    New BB- and VV-band monitoring in 2014 - 2015 reveals that the Seyfert 1 Galaxy, 3C120, has brightened by a magnitude of 1.41.4, compared to our campaign that took place in 2009 - 2010. This allowed us to check for the debated luminosity and time-dependent color variations claimed for SDSS quasars. For our 3C120 data, we find that the B/VB/V flux ratio of the variable component in the bright epoch is indistinguishable from the faint one. We do not find any color variability on different timescales ranging from about 11 to 18001800 days. We suggest that the luminosity and time-dependent color variability is an artifact caused by analyzing the data in magnitudes instead of fluxes. The flux variation gradients of both epochs yield consistent estimates of the host galaxy contribution to our 7.5" aperture. These results confirm that the optical flux variation gradient method works well for Seyfert galaxies.Comment: 8 pages, 6 figures. Accepted for publication in section 4. Extragalactic astronomy of Astronomy and Astrophysics v2: Language-Editor Versio

    Spatial productivity spillovers across Spanish municipalities

    Get PDF
    Whilst a great deal of e¤ort has been dedicated to identification of agglomeration effects on labour productivity, the measurement of spatial productivity spillovers is a question that has been addressed only occasionally along the New Economic Geography literature. We estimate agglomeration effects, nonetheless conditioned to the possible existence of spatial productivity spillovers across Spanish municipalities in year 2001. To this respect, we find that agglomeration effects are in the same order of magnitude than thoseencountered when measured in the standard way. Further, these agglomeration efects coexist with very strong spatial productivity spillovers in a close neighbourhood of 10 km. Finally, these spatial e¤ects are shown to quickly diminish as distance increases.IV estimation, elevation, spatial externalities, productivity, neighbourhood, Spain

    How are monospecific stands of invasive trees formed? Spatio-temporal evidence from Douglas fir invasions

    Get PDF
    Invasive plant species can produce many impacts on native communities. Impacts can be especially important when the non-natives reach high densities, producing monospecific stands where little grows besides the non-native species. We propose three basic pathways by which monospecific stands of invasive tree species are formed: (i) gradually from the propagule source, (ii) via synchronous establishment and (iii) following several pulses of synchronous establishment. Different patterns can produce different impacts through time and may require different management techniques. This study aims to further our understanding of how monotypic stands of invasive species arise. We documented how monospecific stands are formed during invasion processes by studying patterns of spatio-temporal establishment of several monospecific stands of Douglas fir in Patagonia. We obtained data on tree density, year of establishment, size, distance to the seed source and other related measurements for this tree species along transects from the original seed source (80-year-old plantations) to the edge of the monospecific stand. We found that these monospecific stands arose in a more complex way than expected. While individuals established on average simultaneously over all distances from the seed source, there was substantial variation in time of establishment at all distances. Also, tree density was higher near the source than far from it. Different factors can account for the observed pattern of tree establishment, including seed dispersal, mycorrhizal facilitation and herbivory. Our results elucidate the complexities of spatio-temporal pattern of formation in monospecific stands. This understanding can improve management strategies and techniques for this invasion and other plant invasions in different regions.Fil: Nuñez, Martin Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; ArgentinaFil: Paritsis, Juan. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

    Factors facilitating and hindering the invasion of exotic conifer in Isla Victoria

    Get PDF
    Las especies invasoras constituyen una seria amenaza a la biodiversidad y producen cambios a gran escala en las comunidades nativas y alterando los procesos de los ecosistemas. En la actualidad, los bosques Andino-Patagónicos exhiben una diversidad amplia de especies introducidas, tanto terrestres como acuáticas. Muchas de estas especies poseen un potencial invasor elevado, al tiempo que constituyen la base de diversas actividades de importancia económica para la región, como, por ejemplo, los cotos de caza de ciervos y jabalíes,la pesca deportiva de salmónidos y las forestaciones con coníferas introducidas. La situación descripta para la Patagonia brinda un escenario ideal para probar y/o generar nuevas hipótesis sobre la ecología de las invasiones. En un campo más práctico, determinar el impacto y conocer las relaciones entre las especies nativas y exóticas permitirán establecer prioridades en las acciones de manejo, así como también mitigar los efectos no deseados o inesperados como consecuencia de las tareas de erradicación o control. Presentamos aquí una síntesis de losestudios propios llevados a cabo para entender el patrón de invasión de pináceas encontrado en un bosque nativo de Nothofagus/Austrocedrus en Isla Victoria, Parque Nacional Nahuel Huapi. Entre los mecanismos estudiados encontramos que algunos de ellos la facilitan (e.g., ciervos introducidos), mientras que otros la retrasan (depredación de semillas, baja presencia de micorrizas) o no tienen un efecto sustancial en la invasión (presión de propágulos). Estos resultados y otros antecedentes disponibles a la fecha de ésta y otras regiones del mundo, permiten sugerir estrategias de manejo para impedir o retrasar una invasión masiva de pináceas, las cuales deberían posiblemente estar enfocadas a evitar nuevas introducciones, reducir las poblaciones de los herbívoros exóticos y mantener los ecosistemas nativos con bajos niveles de impacto antrópico. Al mismo tiempo, consideramos importante emprender estudios específicamente diseñados para analizar los efectos de las tareas de erradicación y/o control sugeridas.Invasive species constitute a serious threat to biodiversity, producing wide-scale changes in native communities and altering ecosystem processes. The Andean-Patagonian forests currently exhibit a wide diversity of terrestrial as well as aquatic introduced species. Many of these introduced species possess a high invasive potential, while at the same time have economical relevance to the region, such as sport fishing and hunting, and pine plantations. The described situation for Patagonia offers an ideal scenario to test and generate new hypotheses about the ecology of tree invasions. In a more practical domain, determining the impact and knowing the relationship between native and exotic species will permit the establishment of priorities in management actions, as well as also avoiding or mitigating the undesirable or unexpected effects that arise from eradication or control tasks. Here, we present a synthesis of our own studies carried out to understand the factors driving the pattern of pine invasion in the native Nothofagus/Austrocedrus forests on Isla Victoria, Nahuel Huapi National Park. Among studied factors, we found that some of them facilitate the invasion (e.g, introduced herbivores), while others can delay (e.g, low presence of mycorrhizae fungi, seed predation) or have neutral effects on the invasions (e.g., propagule pressure). These results and others currently available from this region and elsewhere allow us to suggest management actions to prevent or hinder a major pine invasion, which should be focused on avoiding new introductions, reducing the abundance of introduced large mammals and preserve native ecosystems with low levels of anthropic disturbances. At the same time, we consider important to start well designed studies to analyze the effects of these management actions.Fil: Relva, Maria Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones En Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Reg.universidad Bariloche. Instituto de Investigaciones En Biodiversidad y Medioambiente; ArgentinaFil: Nuñez, Martin Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones En Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Reg.universidad Bariloche. Instituto de Investigaciones En Biodiversidad y Medioambiente; Argentin

    The European Map of Job Flows

    Get PDF
    The European Map of Job Flows (EMJF) is a term used to denote a dataset of meso- and macro-level variables describing different aspect of labour mobility within national labour markets in Europe. In this paper, EMJF is centred on the notion of job “flows”, namely the changes in the level of employment at different breakdowns and levels of aggregation. EMJF is very rich in information content due to the wide variety of possible breakdown of the data and in this sense it is a “map” mostly in the virtual sense, namely, that it is not possible to visualise in the form of geographic maps all the wealth of available information. In terms of its value as a research product and tool, EMJF is mostly an intermediate product in the sense that it is a convenient means to organise the relevant information, which could subsequently be used for different analytical and research purposes. It provides both for cross-sections/snapshots of job flows at different point in time but also it allows their assessment and analysis over longer periods of time. In this sense, EMJF can be widely used for various types of labour-market analysis and research. EMJF’s visual components can also be a convenient tool for policy makers dealing with labour market policies at different level (regional, national or supra-national) in the decision-making process. Here we present a Compilation of a EMJF on the basis of firm-level data In this sense the job flows are built up on the basis of firm-level data for individual countries, following a common methodology. We adopt an approach of establishing such a EMJF on the basis of the AMADEUS dataset developed by the consultancy Bureau van Dijk. The dataset in its most extended version contains balance sheet data and ownership data for almost 14 million firms from 43 different European countries (September 2009 update). For many EU countries the dataset has in principle access to the entire universe of firms which have to report a balance sheet. In terms of countries, the geographic coverage of AMADEUS encompasses information for all the 27 members of the European Union (albeit with different qualities in terms of national coverage) as well as other 16 European countries that complete the geographical and political definition of the continent. Another interesting feature of the database is given by the detailed definition of a firm's location, with data available on the region (NUTS2) and the city in which the firm operates. This project deliverable presents the main results from the final stage of MICRO-DYN work on the EMJF. It discusses the approach to building the EMJF on the basis of AMADEUS data and illustrates the analytical potential of the EMJF as a research tool with a range of Europe-wide analytical exercises. Probably the most important outcome of this research effort is the demonstrated capability to perform meta-analysis at the European level of important labour market characteristics on the basis of firm-level data.job flows, europe, labor market, microdata

    Static and dynamic measures of human brain connectivity predict complementary aspects of human cognitive performance

    Get PDF
    In cognitive network neuroscience, the connectivity and community structure of the brain network is related to cognition. Much of this research has focused on two measures of connectivity - modularity and flexibility - which frequently have been examined in isolation. By using resting state fMRI data from 52 young adults, we investigate the relationship between modularity, flexibility and performance on cognitive tasks. We show that flexibility and modularity are highly negatively correlated. However, we also demonstrate that flexibility and modularity make unique contributions to explain task performance, with modularity predicting performance for simple tasks and flexibility predicting performance on complex tasks that require cognitive control and executive functioning. The theory and results presented here allow for stronger links between measures of brain network connectivity and cognitive processes.Comment: 37 pages; 7 figure

    Brain Modularity Mediates the Relation between Task Complexity and Performance

    Full text link
    Recent work in cognitive neuroscience has focused on analyzing the brain as a network, rather than as a collection of independent regions. Prior studies taking this approach have found that individual differences in the degree of modularity of the brain network relate to performance on cognitive tasks. However, inconsistent results concerning the direction of this relationship have been obtained, with some tasks showing better performance as modularity increases and other tasks showing worse performance. A recent theoretical model (Chen & Deem, 2015) suggests that these inconsistencies may be explained on the grounds that high-modularity networks favor performance on simple tasks whereas low-modularity networks favor performance on more complex tasks. The current study tests these predictions by relating modularity from resting-state fMRI to performance on a set of simple and complex behavioral tasks. Complex and simple tasks were defined on the basis of whether they did or did not draw on executive attention. Consistent with predictions, we found a negative correlation between individuals' modularity and their performance on a composite measure combining scores from the complex tasks but a positive correlation with performance on a composite measure combining scores from the simple tasks. These results and theory presented here provide a framework for linking measures of whole brain organization from network neuroscience to cognitive processing.Comment: 47 pages; 4 figure

    Rural women’s invisible work in census and state rural development plans: The Argentinean Patagonian case

    Get PDF
    This article reviews the invisibility and the recognition of rural female work in the Patagonian region of Argentina over time. The analysis is carried out based on (a) the systematisation of research articles (b) a historical study of censuses, and (c) the systematisation of rural development plans related to the subject. The article adopts an ecofeminist perspective. The results have been organised into four sections. (1) An overview of the later Patagonian integration; (2) the work of Patagonian women in history; (3) the recognition of rural production in censuses; (4) Patagonian family farming. We found out that the metaphors that relate women with the land are used to deny both rural female work and the family land use. One of its consequences is that Patagonia has become one of the most affected by extractivism. We conclude reviewing the forms of economic and political recognition, which could intervene in future planning.Fil: Nuñez, Paula Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Diversidad Cultural y Procesos de Cambio. Universidad Nacional de Río Negro. Instituto de Investigaciones en Diversidad Cultural y Procesos de Cambio; ArgentinaFil: Michel, Carolina Lara. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Diversidad Cultural y Procesos de Cambio. Universidad Nacional de Río Negro. Instituto de Investigaciones en Diversidad Cultural y Procesos de Cambio; ArgentinaFil: Leal Tejeda, Paula Alejandra. Universidad Autónoma de Chile; ChileFil: Nuñez, Martin Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

    El faisán plateado (Lophura nycthemera) introducido en la Patagonia: Abundancia, estructura de los grupos, patrones de actividad y asociación con el disturbio humano

    Get PDF
    Los fasiánidos son uno de los grupos de aves introducidas con mayor impacto en los ecosistemas nativos. En la Patagonia varias especies de fasiánidos están establecidas o en proceso de establecimiento, por lo que es relevante conocer sus impactos sobre los ecosistemas. El Faisán Plateado (Lophura nycthemera) fue introducido en Isla Victoria en la década de 1950 y se estableció exitosamente en toda la isla. El objetivo de este trabajo es estudiar la población de esta especie en Isla Victoria en términos de abundancia y su asociación con el disturbio humano como un primer paso para conocer su impacto potencial en el ecosistema. Se realizaron capturas fotográficas mediante fototrampeo y observaciones directas en transectas lineales ubicadas en áreas con niveles alto y bajo de disturbio humano. Con los datos de las capturas fotográficas se estimó un índice de abundancia relativa para comparar el uso de hábitat entre las dos áreas. Se utilizó la técnica de muestreo a distancia para estimar la densidad poblacional a partir de las observaciones directas. El Faisán Plateado usó más las áreas con un alto nivel de disturbio, lo que sugiere que la presencia de hábitats modificados podría facilitar su establecimiento y dispersión en la Patagonia. Las densidades poblacionales, tanto en las áreas con alto como con bajo nivel de disturbio, fueron mayores que las reportadas en su área de distribución nativa, mostrando que esta especie ha tenido un gran éxito en Isla Victoria. La alta abundancia, junto con características distintivas tales como el gran tamaño, los hábitos de alimentación y el comportamiento social, pueden moldear las interacciones con las especies nativas e influenciar su impacto sobre las comunidades nativasPhasianids are one of the groups of introduced birds with highest impact on native ecosystems. In Patagonia several phasianids are established or in process of establishment, thus it is relevant to know their impacts on ecosystems. The Silver Pheasant (Lophura nycthemera) was introduced to Isla Victoria in the 1950’s and successfully established all over the island. The aim of this work is to study the population of this species on Isla Victoria in terms of abundance and association to human disturbance as a first step to know its potential impact in the ecosystem. We conducted camera-trapping and direct observations in linear transects located in highly disturbed and in lowly disturbed areas. Using camera-trapping data we estimated an index of relative abundance to compare habitat use between areas. We used the distance-sampling approach to estimate population density with the data from direct observations. The Silver Pheasant used much more frequently areas with a high level of disturbance, suggesting that the presence of disturbed habitats could facilitate establishment and spread of this species in Patagonia. Population densities in areas with high and with low levels of disturbance were higher than those reported from the native distribution area, showing that the Silver Pheasant had a great success on Isla Victoria. The high abundance, together with distinctive characteristics such as a large body size, foraging habits and social behaviour can shape the interactions with native species and influence its impact on native communitiesFil: Martin Albarracin, Valeria Leticia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; ArgentinaFil: Amico, Guillermo Cesar. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentina. Universidad Nacional del Comahue. Centro Regional Universitario Bariloche. Laboratorio de Ecotono; ArgentinaFil: Nuñez, Martin Andres. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Biodiversidad y Medioambiente. Universidad Nacional del Comahue. Centro Regional Universidad Bariloche. Instituto de Investigaciones en Biodiversidad y Medioambiente; Argentin

    Young people’s expressed needs for comprehensive sexuality education in Ecuadorian schools

    Get PDF
    This study analyses the expressed sexuality education needs of young people from Azuay, a region of Ecuador characterised by a large proportion of young people whose parents have migrated abroad, a group often considered at risk to developing of sexual health problems. Multi-stage stratified cluster sampling was used to recruit young people aged 11 and 19 years to the study. The expressed needs of participants were analysed in relation to gender, parents’ migratory status, age and geographical location. Survey findings revealed that young people expressed high needs with respect to the different components of Comprehensive Sexuality Education: gender roles, sexual and reproductive health, sexual citizenship, pleasure, violence, diversity and relationships. Ordinal regression analyses revealed few significant differences in relation to socio-demographic variables, which was surprising, in particular, with respect to the group of young people with migrating parents. Given the high levels of expressed needs, the findings carry important implications for the design and implementation of future sexuality education programmes
    corecore