11,724 research outputs found

    Retired galaxies: not to be forgotten in the quest of the star formation -- AGN connection

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    We propose a fresh look at the Main Galaxy Sample of the Sloan Digital Sky Survey by packing the galaxies in stellar mass and redshift bins. We show how important it is to consider the emission-line equivalent widths, in addition to the commonly used emission-line ratios, to properly identify retired galaxies (i.e. galaxies that have stopped forming stars and are ionized by their old stellar populations) and not mistake them for galaxies with low-level nuclear activity. We find that the proportion of star-forming galaxies decreases with decreasing redshift in each mass bin, while that of retired galaxies increases. Galaxies with M⋆>1011.5M⊙M_\star > 10^{11.5} M_\odot have formed all their stars at redshift larger than 0.4. The population of AGN hosts is never dominant for galaxy masses larger than 1010M⊙10^{10} M_\odot. We warn about the effects of stacking galaxy spectra to discuss galaxy properties. We estimate the lifetimes of active galactic nuclei (AGN) relying entirely on demographic arguments --- i.e. without any assumption on the AGN radiative properties. We find upper-limit lifetimes of about 1--5 Gyr for detectable AGN in galaxies with masses between 101010^{10}--1012M⊙10^{12} M_\odot. The lifetimes of the AGN-dominated phases are a few 10810^8 yr. Finally, we compare the star-formation histories of star-forming, AGN and retired galaxies as obtained by the spectral synthesis code STARLIGHT. Once the AGN is turned on it inhibits star formation for the next ∼\sim 0.1 Gyr in galaxies with masses around 1010M⊙10^{10} M_\odot, ∼\sim 1 Gyr in galaxies with masses around 1011M⊙10^{11} M_\odot.Comment: accepted for MNRAS figure resolution has been degraded with respect to what will be published in MNRA

    The Spanish food industry on global supply chains and its impact on water resources

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    The study of the impact of economic activities on natural resources through global supply chains is increasingly demanded in the context of the growing globalization of economies and product fragmentation. Taking Spain as a case study and a sector with significant economic and environmental impacts, the agri-food industry, the objective of this work is two-fold. First, we estimate the associated water impact, both from the production and consumption perspectives, paying special attention to the water embodied in production exchanges among countries and sectors. To that aim, we use an environmentally-extended multiregional input-output model (MRIO). Second, we assess the main driving factors behind changes in direct and embodied water consumption between the years 1995 and 2009 by means of a structural decomposition analysis. The MRIO model provides a comprehensive estimate of the economic linkages among regions and economic sectors and, therefore, allows calculating the environmental impacts over international value chains. The results indicate that the food industry exerts large impacts on global water resources, particularly given the remarkable interactions with the domestic and foreign agricultural sectors, These growing linkages show how consumption patterns, and, therefore, lifestyles, involve large environmental impacts through the whole and global supply chains

    Income, economic structure and trade: Impacts on recent water use trends in the European Union

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    From the mid-1990s to the recent international economic crisis, the European Union (EU27) experienced a significant economic growth and a flat population increase. During these years, the water resources directly used by the EU countries displayed a growing but smooth trend. However, European activities intensively demanded water resources throughout the whole global supply chain. The growth rate of embodied water use was three times higher than the growth in water directly used by these economies. This was mainly due to the large upsurge of virtual water imports in the EU (e.g., about 25% of the change in water imports in the world was directly linked to the increasing imports in the EU27 countries). In this context, we analyze water use changes in the EU27 from 1995 to 2009, combining the production and consumption perspectives. To that aim, we use the environmentally extended input-output approach to obtain the volume of water embodied in domestic production and in trade flows at the sector and country levels. In the empirical analysis, we utilize multi-regional input-output data from the World Input Output Database. In addition, by means of a structural decomposition analysis we identify and quantify the factors explaining changes in these trends. We focus both on the role of domestic production and trade and estimate the associated intensity, technology and scale effects. This analysis is done for different clusters, identifying singular patterns depending on income criteria. Our results confirm the boost of demand growth in that period, the positive but negligible effect of structural change, and the decline in water intensity which, however, was not enough to compensate the effects on water associated to the economic expansion in the period. These findings also point at a gradual substitution of domestic water use for virtual water imports. More concretely, in most countries the food industry tended to reduce its backward linkages with the domestic agricultural sector, increasing the embodied water in agricultural imports from non-European regions

    Globalization and natural resources: the expansion of the Spanish agrifood trade and its impact on water consumption, 1965–2010

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    Beginning in 1960, the Spanish agricultural sector underwent an intensive process of development, resulting in important structural changes, not only in the sector itself, but also in the relationship of the agrarian system to natural resources. These changes were closely related to the growth of per capita income and Spain’s increasing integration into international markets. In the last five decades, the volume of Spanish agricultural trade has increased strongly, with a concomitant increase in the consumption of domestic water resources, requiring the construction of water infrastructure for irrigation. This paper examines the impact on water use in Spain during a period of economic modernization and trade liberalization. More specifically, we are interested in obtaining virtual water trade flow trends and identifying the major drivers responsible for these trajectories, via a decomposition analysis. Our results point to a large increase in virtual water exports and imports, primarily driven by the scale effect, that is, by the growing integration into international markets. The composition effect and changes in water intensity entailed a moderation in water consumption

    Rendimento de grãos verdes em função da densidade de plantas de feijão-caupi e milho consorciado.

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    O trabalho teve como objetivo avaliar a influência do número de plantas, por área, de feijão-caupi e milho consorciado sobre o rendimento de grãos verdes. O delineamento estatístico foi o de blocos casualizados, em esquema fatorial, com quatro repetições. Utilizaram-se quatro densidades (3,0; 6,0; 9,0 e 12,0 plantas m-2) de feijão-caupi (cultivar BRS Guariba) associado às densidades (2,0; 4,0; 6,0 e 8,0 plantas ha-1) de milho CMS 47. Não houve efeito da interação densidade de plantas de feijão-caupi x densidade de plantas de milho. As funções ajustadas mostraram rendimentos máximos de espiga verde empalhada e despalhada de 8.850 kg.ha-1 e 5.415 kg.ha-1, nas densidades de 80 mil plantas ha-1 de milho, combinadas a 69 mil plantas e 73 mil plantas de feijão-caupi ha-1, respectivamente. Os maiores rendimentos de vagens verdes e grãos verdes foram de 2.058 kg.ha-1 e 1.180 kg.ha-1, nas densidades de 98 mil plantas ha-1 e 99 plantas ha-1, associadas a 20 mil plantas ha-1 de milho. Os componentes de produção número de espiga verde por planta e número de vagem verde por planta foram os mais afetados com o número de plantas por área, que decresceram com o aumento da densidade de plantas

    Delirium Pós-Operatório em Cirurgia Vascular

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    OBJECTIVES: The objectives of this study were to determine the incidence of Postoperative Delirium and to identify specific perioperative risk factors in patients undergoing Vascular Surgery. Other goals were to study its impact in hospital length of stay and to create an algorithm to deal with patients under suspicion of Postoperative Delirium. MATERIAL AND METHODS: A total of 56 consecutive vascular surgery patients were prospectively evaluated. Exclusion criteria were age less than 18, dementia, abnormal level of consciousness, psychiatric disorder and visual or hearing impairment. Mini Mental State Examination were applied during pre-anesthetic visit. In patients with clinical indicators of delirium the Confusion Assessment Method was applied. Patients were assessed during 5 days after surgery. RESULTS: The overall incidence of delirium was 12,5%, developped mostly by the second to fifth postoperative day. Patients with delirium presented moderate to severe pain. Patients who received combined general and regional anesthesia didn't develop delirium. The median hospital length of stay was 21 in patients with delirium and 7 days in patients without (p 0.001). CONCLUSIONS: The overall incidence of postoperative delirium was lower than previously reported. The incidence of delirium was higher in ICU patients and pain was associated with postoperative delirium suggesting the opportunity to control postoperative factores. The development of delirium in the second and fifth day indicated the need for early and more prolonged preventive and diagnosing measures. Clinical and costly considerations of prolonged hospital stay shown in this cohort warrant strong debate strategies to be applied.info:eu-repo/semantics/publishedVersio

    Oscillatory dynamics of a superconductor vortex lattice in high amplitude ac magnetic fields

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    In this work we study by ac susceptibility measurements the evolution of the solid vortex lattice mobility under oscillating forces. Previous work had already shown that in YBCO single crystals, below the melting transition, a temporarily symmetric magnetic ac field (e.g. sinusoidal, square, triangular) can heal the vortex lattice (VL) and increase its mobility, but a temporarily asymmetric one (e.g. sawtooth) of the same amplitude can tear the lattice into a more pinned disordered state. In this work we present evidence that the mobility of the VL is reduced for large vortex displacements, in agreement with predictions of recent simulations. We show that with large symmetric oscillating fields both an initially ordered or an initially disordered VL configuration evolve towards a less mobile lattice, supporting the scenario of plastic flow.Comment: 5 pages, 4 figures. To appear in Phys. Rev.
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