AGN and their host galaxies in the local Universe: two mass independent Eddington ratio distribution functions characterize black hole growth

We use a phenomenological model to show that black hole growth in the local Universe (z < 0.1) can be described by two separate, mass independent Eddington ratio distribution functions (ERDFs). We assume that black holes can be divided into two independent groups: those with radiatively efficient accretion, primarily hosted by optically blue and green galaxies, and those with radiatively inefficient accretion, which are mainly found in red galaxies. With observed galaxy stellar mass functions as input, we show that the observed AGN luminosity functions can be reproduced by using mass independent, broken power law shaped ERDFs. We use the observed hard X-ray and 1.4 GHz radio luminosity functions to constrain the ERDF for radiatively efficient and inefficient AGN, respectively. We also test alternative ERDF shapes and mass dependent models. Our results are consistent with a mass independent AGN fraction and AGN hosts being randomly drawn from the galaxy population. We argue that the ERDF is not shaped by galaxy-scale effects, but by how efficiently material can be transported from the inner few parsecs to the accretion disc. Our results are incompatible with the simplest form of mass quenching where massive galaxies host higher accretion rate AGN. Furthermore, if reaching a certain Eddington ratio is a sufficient condition for maintenance mode, it can occur in all red galaxies, not just the most massive ones.Comment: 33 pages, 15 figures, accepted for publication in ApJ, Fig. 6 shows the main resul

Stronger Constraints on the Evolution of the MBH−σ∗M_{\rm{BH}}-\sigma_* Relation up to z∼0.6z\sim0.6

We revisit the possibility of redshift evolution in the $M_{\rm{BH}}-\sigma_*$ relation with a sample of 22 Seyfert 1 galaxies with black holes (BHs) in the mass range $10^{6.3}-10^{8.3}~M_\odot$ and redshift range $0.03<z<0.57$ with spectra obtained from spatially resolved Keck/Low-Resolution Imaging Spectrometer observations. Stellar velocity dispersions were measured directly from the Mg Ib region, taking into consideration the effect of Fe II contamination, active galactic nucleus (AGN) dilution, and host-galaxy morphology on our measurements. BH masses are estimated using the H$\beta$ line width, and the luminosity at 5100 \overset{\lower.5em\circ}{\mathrm{A}} is estimated from surface brightness decomposition of the AGN from the host galaxy using high-resolution imaging from the Hubble Space Telescope. Additionally, we investigate the use of the [O III]$\lambda5007$ emission line width as a surrogate for stellar velocity dispersion, finding better correlation once corrected for Fe II contamination and any possible blueshifted wing components. Our selection criteria allowed us to probe lower-luminosity AGNs and lower-mass BHs in the non-local universe than those measured in previous single-epoch studies. We find that any offset in the $M_{\rm{BH}}-\sigma_*$ relation up to $z\sim0.6$ is consistent with the scatter of local BH masses, and address the sources of biases and uncertainties that contribute to this scatter.Comment: Accepted 14 May 2019 for publication in ApJ. 42 pages, 12 figures, 4 tables. Corrected for typographical error

Extended X-ray emission in the IC 2497 - Hanny's Voorwerp system: energy injection in the gas around a fading AGN

We present deep Chandra X-ray observations of the core of IC 2497, the galaxy associated with Hanny's Voorwerp and hosting a fading AGN. We find extended soft X-ray emission from hot gas around the low intrinsic luminosity (unobscured) AGN ($L_{\rm bol} \sim 10^{42}-10^{44}$ erg s$^{-1}$). The temperature structure in the hot gas suggests the presence of a bubble or cavity around the fading AGN (\mbox{E_{\rm bub}} \sim 10^{54} - 10^{55} erg). A possible scenario is that this bubble is inflated by the fading AGN, which after changing accretion state is now in a kinetic mode. Other possibilities are that the bubble has been inflated by the past luminous quasar ($L_{\rm bol} \sim 10^{46}$ erg s$^{-1}$), or that the temperature gradient is an indication of a shock front from a superwind driven by the AGN. We discuss the possible scenarios and the implications for the AGN-host galaxy interaction, as well as an analogy between AGN and X-ray binaries lifecycles. We conclude that the AGN could inject mechanical energy into the host galaxy at the end of its lifecycle, and thus provide a source for mechanical feedback, in a similar way as observed for X-ray binaries.Comment: 9 pages, 5 figures, accepted for publication in MNRA

Rastrojo de maíz: producción teórica de etanol lignocelulósico en relación a la fecha de siembra

El efecto de la fecha de siembra sobre el rendimiento y la calidad bioenergética del rastrojo de maíz (Zea mays L.) es poco conocido. Este recurso está siendo reconsiderado debido a que no compite con los alimentos y tiene un bajo costo. El objetivo fue determinar el efecto de la fecha de siembra en la producción teórica de etanol del rastrojo en híbridos comerciales de maíz. Cuatro híbridos fueron evaluados en dos fechas de siembra en un diseño de bloques completos aleatorizados con arreglo factorial y tres repeticiones. Se analizaron variables de rendimiento y calidad bioenergética. Además, se determinaron mediante regresión lineal los perfiles verticales de distribución del rendimiento (tn/ha) y del rendimiento en etanol teórico potencial (L/ha), dividiendo al rastrojo en estratos de 20 cm desde la base al ápice. La fecha de siembra tardía fue superior a la temprana. Produjo un mayor rendimiento de rastrojo (11,32 vs. 9,37 tn/ha) y en etanol teórico potencial (3,78 vs. 2,47 mil L/ha). Hubo un aporte decreciente de cada estrato desde la base hasta el ápice de la planta. No obstante, la fecha de siembra tardía produjo mayor acumulación de biomasa por estrato, aportando mayor remanente al suelo ante una misma altura de corte.Trabajo presentado por el Instituto de Investigación Agropecuaria, Ambiente y Salud (IIPAAS

A percolation model with disaggregation and aggregation

A model of percolation with disaggregation and aggregation (PDA) is proposed and studied by means of the Monte Carlo simulation on the square lattice. The critical concentration φc, the correlation length exponent and the fractal and spreading dimensions of the largest cluster at φc have been computed. The obtained results suggest that the PDA model belongs to the same universality class than the standard percolation model. Nevertheless, the critical concentration (φc=0.464±0.005) of the former is quite different from the critical probability (pc=0.5927) of the later model.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Study of recombination reactions of particles adsorbed on fractal and multifractal substrata

Recombination reactions of adsorbed particles on fractal and multifractal media are discussed within the framework of the random walk arguments. Theoretical results, which predict anomalous reaction orderX>2 in the low coverage regime, are checked by means of Monte Carlo simulations on two-dimensional structures and good agreement is found. Thermal desorption experiments on rough surfaces are simulated by studying temperature programmed reactions on fractal percolating clusters. For this case the simulations giveX≅2.5, i. e. the fractal reaction order is greater than the classical one (X=2). The influence of chemisorbed impurities (poison) on the recombination reaction is also studied and the reaction order is found to increase beyondX=2.5 when increasing the concentration of poison. Isothermal (recombination) desorption from energetically heterogeneous surfaces is simulated on two-dimensional substrata with multifractal distributions of activation energy of diffusion. For this caseX (withX>2) depends on the energetic heterogeneity of the substrata (X=2 for an homogeneous substratum). The obtained results point out that the fractal chemical kinetic behaviour is not only restricted to the low concentration regime, but it also covers the medium coverage regime, i.e. it holds for a monolayer surface coverageθ≦0.4 in fractal percolating clusters.Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicada

Evaluación de la calidad de suelos agrícolas por medio de índices

Para evaluar la calidad del suelo se deben seleccionar propiedades químicas, físicas y/o biológicas del suelo que sean sensibles a las prácticas de manejos y puedan ser utilizadas como indicadores tempranos de los cambios que se producen. La materia orgánica es el indicador más ampliamente utilizado, si bien los mejores resultados se obtienen combinándolo en los índices relacionados con la funcionalidad del suelo.Fil: Duval, Matias Ezequiel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida(i); ArgentinaFil: López, Fernando Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida(i); ArgentinaFil: Martinez, Juan Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida(i); ArgentinaFil: Iglesias, Julio O.. Universidad Nacional del Sur. Departamento de Agronomía; ArgentinaFil: Galantini, Juan Alberto. Universidad Nacional del Sur. Departamento de Agronomía; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Bahía Blanca. Centro de Recursos Naturales Renovables de la Zona Semiárida(i); ArgentinaFil: Wall, Luis Gabriel. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Modelo lattice-Boltzmann para flujo multifásico con transferencia de calor en GPU

En este trabajo se presentan las tareas de formación de recursos humanos y de investigación y desarrollo en la programación del modelo de lattice-Boltzmann para flujo multifásico con transferencia de calor en unidades de procesamiento gráfico (GPU) en el departamento Mecánica Computacional (Centro Atómico Bariloche) donde un estudiante del Instituto Balseiro lleva a cabo su proyecto integrador de grado para obtener el título de ingeniero mecánico. Desde el año 2019 un grupo de docentes investigadores del departamento Mecánica Computacional busca innovar en la resolución de problemas ingenieriles que emplean herramientas de cálculo numérico para modernizar los métodos empleados y maximizar el aprovechamiento de las técnicas y de las herramientas de hardware que se disponen. Las tareas involucradas permiten incorporar estudiantes de último año de ingeniería del Instituto Balseiro para formarse y generar la tesina de grado como resultado de su actividad en este proyecto. Se discutirán los recursos informáticos empleados, los ejes de investigación, los resultados obtenidos y futuros, y las producciones asociadas. Mostraremos que el uso de entornos de desarrollo colaborativos, en proyectos de investigación y desarrollo para la formación de nuevos profesionales, ayudan a compartir la realización de tareas, permitiendo incorporar nuevas formas de trabajo para docentes investigadores y estudiantes, con importantes consecuencias tales como la valoración del trabajo colaborativo que los alumnos podrán capitalizar luego en su carrera.Eje: Procesamiento distribuido y paralelo.Red de Universidades con Carreras en Informátic

Flow analysis method for hydroxyproline determination to assess collagen content in fish skin

Collagen is a protein with several applications, with weak antigenicity, low toxicity, and high nutritional value. Usually, it is extracted from bovine skin, but a project was designed proposing an alternative to extract collagen from fish skin. This alternative was tested by assessing the collagen content in fish skin based on the determination of hydroxyproline (HYP), one of the most abundant amino acid present in collagen (Sotelo et al., 2016). Therefore, the determination of HYP requires the hydrolysis of the fish skin, to break collagen in its amino acids, and the HYP value quantified relates to the collagen content. This was previously assessed to be 38 μg of HYP per mg of pure collagen. In this context, the aim of the described work was to develop an automatic method based on flow injection analysis approach to determine HYP. The determination was based on the redox reaction with permanganate (Farokhi et al., 2002) and the consequent decrease of colour intensity registered. The best conditions for the determination were studied, namely, reagent concentration, sample volume, flow rate and reaction time. The developed method enables the determination of the HYP in a faster, simpler and accurate way, with less toxic solutions.info:eu-repo/semantics/publishedVersio

Collagen determination in fish skin: development of a flow analysis system for quantification of hydroxyproline

Collagen is a protein with various applications, namely in the food area. It has valuable properties, since it is a polymer with weak antigenicity, low toxicity, and high nutritional value, among other features [1]. Its extraction from mammalian sources, i.e., bovines, is decreasing due to health and environmental problems and, therefore, fish have become a good alternative for collagen resources [2].One way to quantify the collagen present in fish skin, in order to obtain high-value fractions, is the determination of hydroxyproline (HYP), an amino acid highly present in collagen [1]. The determination of HYP from fish skin requires the hydrolysis of a skin section, to break collagen in its amino acids and the HYP value quantified is compared to the amount present in pure collagen, studied previously (38 μg of HYP per mg of pure collagen). The quantification of HYP is based on its oxidation combined with the reaction with DAB (dimethylaminobenzaldehyde) that forms a chromophore-coloured product. The HYP can then be correlated with the spectrophotometric measurement of this coloured product. A batchwise approach was performed to study the best reaction conditions, namely different reagents, heating times and proportions.The main goal of this work is to develop an automated flow injection analysis (FIA) method, to miniaturize the determination of HYP. Several operation parameters like flow rates, number of channels, tube diameters and lengths of reactors will be studied to optimize the developed FIA method.info:eu-repo/semantics/publishedVersio