Relation between parameters of dust and parameters of molecular and atomic gas in extragalactic star-forming regions

The relationships between atomic and molecular hydrogen and dust of various sizes in extragalactic star-forming regions are considered, based on observational data from the Spitzer and Herschel infrared space telescopes, the Very Large Array (atomic hydrogen emission) and IRAM (CO emission). The source sample consists of approximately 300 star-forming regions in 11 nearby galaxies. Aperture photometry has been applied to measure the fluxes in eight infrared bands (3.6, 4.5, 5.8, 8, 24, 70, 100, and 160$\mu$m), the atomic hydrogen (21cm) line and CO (2--1) lines. The parameters of the dust in the starforming regions were determined via synthetic-spectra fitting, such as the total dust mass, the fraction of polycyclic aromatic hydrocarbons (PAHs), etc. Comparison of the observed fluxes with the measured parameters shows that the relationships between atomic hydrogen, molecular hydrogen, and dust are different in low- and high-metallicity regions. Low-metallicity regions contain more atomic gas, but less molecular gas and dust, including PAHs. The mass of dust constitutes about $1\%$ of the mass of molecular gas in all regions considered. Fluxes produced by atomic and molecular gas do not correlate with the parameters of the stellar radiation, whereas the dust fluxes grow with increasing mean intensity of stellar radiation and the fraction of enhanced stellar radiation. The ratio of the fluxes at 8 and 24$\mu$m, which characterizes the PAH content, decreases with increasing intensity of the stellar radiation, possibly indicating evolutionary variations of the PAH content. The results confirm that the contribution of the 24$\mu$m emission to the total IR luminosity of extragalactic star-forming regions does not depend on the metallicity.Comment: Published in Astronomy Reports, 2017, vol. 61, issue

Citizenship education in the Framework of 2030 Agenda and environmental justice

Este artículo busca analizar las orientaciones de la Unesco para una educación coherente con los Objetivos de Desarrollo Sostenible (ODS) señalados en la agenda; identificar sus debilidades y fortalezas para la formación de una ciudadanía comprometida con la justicia ambiental; y proponer una alternativa para subsanar las deficiencias identificadas. Se ha utilizado una metodología hermenéutica aplicada al estudio de la bibliografía y documentos. Los resultados indican que las directrices formativas de Unesco no agotan las finalidades prioritarias que el movimiento por la justicia ambiental atribuye a la educación, aunque pueden contribuir a ellas; las respectivas fortalezas de ambos enfoques podrían dar lugar a sinergias con efectos recíprocamente beneficiosos. En el artículo se destacan las características significativas de la Agenda 2030 y el concepto de justicia ambiental. Se analizan las competencias clave en sostenibilidad que la Unesco propone y se valoran desde la perspectiva de la justicia ambiental. El cuarto apartado está dedicado al tipo de ciudadanía cuya formación ambos enfoques precisan. Finalmente, se hace una propuesta integradora sobre las necesidades formativas para alcanzar tanto los ODS como la justicia ambientalThis article seeks to analyze the guidelines of Unesco for an education consistent with the Sustainable Development Objectives (SDO) set out in the agenda; identify their weaknesses and strengths for the education of a citizenship committed to environmental justice; and propose an alternative to remedy the deficiencies identified. A hermeneutic methodology has been used for the analysis of bibliography and documents. The results shown that Unesco's training guidelines do not exhaust the priority objectives that the environmental justice movement attributes to education, although they can contribute to them; the respective strengths of both approaches could lead to synergies with reciprocal beneficial effects. The article highlight the significant features of Agenda 2030 and the concept of environmental justice. The key competences in sustainability that Unesco proposes are analyzed next, and they are evaluated from the perspective of environmental justice. The fourth section is devoted to the type of citizenship that is required for the education considered in both approaches. Finally, we made an integrative proposal about the educational needs to achieve ODS and environmental justiceProyecto EDU2015-66591-R financiado por el Ministerio de Economía, Industria y Competitividad del Gobierno de Españ

The charge role in the cosmic dust evolution

В работе рассматривается влияние заряда космических пылинок на их фоторазрушение, эрозию и фрагментацию. На основе численного моделирования эволюции ансамбля пылинок сделан вывод о важности учета заряда для исследования пыли. Исследовано влияние заряда на оптические свойства мелкой пыли, проведено моделирование спектров инфракрасного излучения нейтральных и заряженных пылинок.In this work we consider the role of cosmic dust grain charge on the dust photodestruction, erosion, and fragmentation. A numerical simulation of dust ensemble evolution is used as a base for the conclusion on the necessity of taking the grain charge into account in dust studies. An influence of charge on optical properties of small grains is studied, and infrared emission spectra of neutral and charged grains are modelled.Работа выполнена при поддержке гранта РФФИ 17-02-00521

Science signaling podcast: 21 July 2015

© 2015 American Association for the Advancement of Science. All rights Reserved. This Podcast features an interview with Cristina Murga and Rocio Vila-Bedmar, authors of a Research Article that appears in the 21 July 2015 issue of Science Signaling, about how deleting the kinase GRK2 can counteract some of the metabolic effects of a bad diet. Obesity affects many of the body's normal functions, most notably metabolism. Obesity is associated with insulin resistance and reduced glucose tolerance, which can lead to type 2 diabetes. It also promotes hepatic steatosis, the accumulation of fat in the liver. Vila-Bedmar et al. show that deleting GRK2 can prevent further weight gain and hepatic steatosis and improve glucose sensitivity in obese mice. Deleting GRK2 improved these metabolic consequences of high-fat diet-induced obesity even if the kinase was deleted after the mice had already become obese and resistant to insulin.Peer Reviewe

Efficiency of the top-down PAH-to-fullerene conversion in UV irradiated environments

Polycyclic aromatic hydrocarbons (PAHs) and fullerenes play a major role in the physics and chemistry of the interstellar medium. Based on a number of recent experimental and theoretical investigations we developed a model in which PAHs are subject to photo-dissociation (carbon and hydrogen loss) and hydrogenation. We take into account that dehydrogenated PAHs may fold into closed structures -- fullerenes. Fullerenes, in their turn, can be also hydrogenated, becoming fulleranes, and photo-dissociated, losing carbon and hydrogen atoms. The carbon loss leads to shrinking of fullerene cages to smaller ones. We calculate the abundance of PAHs and fullerenes of different sizes and hydrogenation level depending on external conditions: the gas temperature, intensity of radiation field, number density of hydrogen atoms, carbon atoms, and electrons. We highlight the conditions, which are favourable for fullerene formation from PAHs, and we conclude that this mechanism works not only in H-poor environment but also at modest values of hydrogen density up to 10$^{4}$~cm$^{-3}$. We found that fulleranes can be formed in the ISM, although the fraction of carbon atoms locked in them can be maximum around 10$^{-9}$. We applied our model to two photo-dissociation regions, Orion Bar and NGC 7023. We compare our estimates of the fullerene abundance and synthetic band intensities in these objects with the observations and conclude that our model gives good results for the closest surroundings of ionising stars. We also demonstrate that additional fullerene formation channels should operate along with UV-induced formation to explain abundance of fullerenes far from UV sources.Comment: Accepted to MNRAS. 19 pages, 12 figure

Direct observation of the influence of the As-Fe-As angle on the Tc of superconducting SmFeAsO1−x_{1-x}Fx_{x}

The electrical resistivity, crystalline structure and electronic properties calculated from the experimentally measured atomic positions of the compound SmFeAsO$_{0.81}$F$_{0.19}$ have been studied up to pressures ~20GPa. The correlation between the pressure dependence of the superconducting transition temperature (Tc) and crystallographic parameters on the same sample shows clearly that a regular FeAs$_{4}$ tetrahedron maximizes Tc, through optimization of carrier transfer to the FeAs planes as indicated by the evolution of the electronic band structures.Comment: 15pages, 4 figure

Correlated pressure effects on structure and superconductivity in LaFeAsO0.9F0.1

We have studied the structural and superconductivity properties of the compound LaFeAsO0.9F0.1 under pressures up to 32GPa using synchrotron radiation and diamond anvil cells. We obtain an ambient pressure bulk modulus K_0 = 78(2)GPa, compressibility comparable to some cuprates. At high pressures, the sample is in the overdoped region, with a linear decrease with pressure variation of the superconducting transition temperature.Comment: 15 pages, 4 figures, 1 tabl