Constraints on feedback processes during the formation of early-type galaxies

Galaxies are found to obey scaling relations between a number of observables. These relations follow different trends at the low- and the high-mass ends. The processes driving the curvature of scaling relations remain uncertain. In this letter, we focus on the specific family of early-type galaxies, deriving the star formation histories of a complete sample of visually classified galaxies from SDSS-DR7 over the redshift range 0.01<z<0.025, covering a stellar mass interval from 10^9 to 3 x 10^11 Msun. Our sample features the characteristic "knee" in the surface brightness vs. mass distribution at Mstar~3 x 10^10 Msun. We find a clear difference between the age and metallicity distributions of the stellar populations above and beyond this knee, which suggests a sudden transition from a constant, highly efficient mode of star formation in high-mass galaxies, gradually decreasing towards the low-mass end of the sample. At fixed mass, our early-type sample is more efficient in building up the stellar content at early times in comparison to the general population of galaxies, with half of the stars already in place by redshift z~2 for all masses. The metallicity-age trend in low-mass galaxies is not compatible with infall of metal-poor gas, suggesting instead an outflow-driven relation.Comment: 12 pages,3 figures, accepted for publication in ApJ

Characterizing the nature of Fossil Groups with XMM

We present an X-ray follow-up, based on XMM plus Chandra, of six Fossil Group (FG) candidates identified in our previous work using SDSS and RASS data. Four candidates (out of six) exhibit extended X-ray emission, confirming them as true FGs. For the other two groups, the RASS emission has its origin as either an optically dull/X-ray bright AGN, or the blending of distinct X-ray sources. Using SDSS-DR7 data, we confirm, for all groups, the presence of an r-band magnitude gap between the seed elliptical and the second-rank galaxy. However, the gap value depends, up to 0.5mag, on how one estimates the seed galaxy total flux, which is greatly underestimated when using SDSS (relative to Sersic) magnitudes. This implies that many FGs may be actually missed when using SDSS data, a fact that should be carefully taken into account when comparing the observed number densities of FGs to the expectations from cosmological simulations. The similarity in the properties of seed--FG and non-fossil ellipticals, found in our previous study, extends to the sample of X-ray confirmed FGs, indicating that bright ellipticals in FGs do not represent a distinct population of galaxies. For one system, we also find that the velocity distribution of faint galaxies is bimodal, possibly showing that the system formed through the merging of two groups. This undermines the idea that all selected FGs form a population of true fossils.Comment: 9 pages, 3 figures. Submitted 01/12/2011 to MNRAS, referee report received 21/02/2012, accepted 22/02/201

Analysis of the pedagogical perspective of the MOOCs available in Portuguese

After an initial stage of exponential growth in MOOCs, a need has arisen of to address several different aspects of these innovations in order to understand and develop them from different perspectives, such as this one, with the analysis of pedagogical dimensions aimed at improving course design. This paper presents an updated review of the literature and proposes five research lines for an in-depth approach. This study is part of a broader research project1 and here analyses 356 MOOCs delivered in Portuguese by 16 different platforms. The research design is quantitative, non-experimental and transversal. An adaptation of the MOOC Educational and Interactive Indicators Instrument —INdiMOOC-EdI— was used in the data collection process. The reliability and internal consistency analysis of that adaptation for the whole sample resulted in a Cronbach alpha score of 0.731. The data obtained enable us to classify the existing MOOCs in Portuguese according to descriptive, formative, and interactive components. These different types correlate with the quality indices, being negative in the first dimension (descriptive) and positive in the second and third ones (formative and interactive).Funded by the call for R&D&i projects named: «Estudio del impacto de las erubricas federada en evaluación de las competencias en el practicum» (Study on the impact of federated eRubrics in the evaluation of the competences in the practicum). Plan Nacional de I+D+i de Excelencia (National R&D&i Excellence Plan) (2014-16) no. EDU2013-41974-

Scenarios for oil palm expansion in degraded and deforested lands in the Brazilian Amazon to meet biodiesel demand

Palm oil production for biodiesel in Brazil is characterized by its high productivity in some environmental conditions, under the Sustainable Palm Oil Production Program. The program seeks to avoid deforestation for oil palm cultivation, recover degraded lands, and focus on social inclusion and family farming. This paper assesses the possible socio-environmental impacts of the expansion of palm oil until 2030, focusing on land-use change and impacts. Land-use data came from the TerraClass initiative for the analysis of degraded forests using geoprocessing. We produced two oil expansion scenarios. The first one reflects current trends in palm oil production expansion and deforestation in Pará State (S1). The second one considers the exclusive use of deforested/degraded land for oil palm crops (S2). The results demonstrate that degraded/deforested land in the current palm oil-producing municipalities is only sufficient for the projected level of expansion for 2020, requiring a stronger public policy to recover degraded areas for oil palm cultivation with social inclusion of family farming.Palm oil production for biodiesel in Brazil is characterized by its high productivity in some environmental conditions, under the Sustainable Palm Oil Production Program. The program seeks to avoid deforestation for oil palm cultivation, recover degraded lands, and focus on social inclusion and family farming. This paper assesses the possible socio-environmental impacts of the expansion of palm oil until 2030, focusing on land-use change and impacts. Land-use data came from the TerraClass initiative for the analysis of degraded forests using geoprocessing. We produced two oil expansion scenarios. The first one reflects current trends in palm oil production expansion and deforestation in Pará State (S1). The second one considers the exclusive use of deforested/degraded land for oil palm crops (S2). The results demonstrate that degraded/deforested land in the current palm oil-producing municipalities is only sufficient for the projected level of expansion for 2020, requiring a stronger public policy to recover degraded areas for oil palm cultivation with social inclusion of family farming.Palm oil production for biodiesel in Brazil is characterized by its high productivity in some environmental conditions, under the Sustainable Palm Oil Production Program. The program seeks to avoid deforestation for oil palm cultivation, recover degraded lands, and focus on social inclusion and family farming. This paper assesses the possible socio-environmental impacts of the expansion of palm oil until 2030, focusing on land-use change and impacts. Land-use data came from the TerraClass initiative for the analysis of degraded forests using geoprocessing. We produced two oil expansion scenarios. The first one reflects current trends in palm oil production expansion and deforestation in Pará State (S1). The second one considers the exclusive use of deforested/degraded land for oil palm crops (S2). The results demonstrate that degraded/deforested land in the current palm oil-producing municipalities is only sufficient for the projected level of expansion for 2020, requiring a stronger public policy to recover degraded areas for oil palm cultivation with social inclusion of family farming.Palm oil production for biodiesel in Brazil is characterized by its high productivity in some environmental conditions, under the Sustainable Palm Oil Production Program. The program seeks to avoid deforestation for oil palm cultivation, recover degraded lands, and focus on social inclusion and family farming. This paper assesses the possible socio-environmental impacts of the expansion of palm oil until 2030, focusing on land-use change and impacts. Land-use data came from the TerraClass initiative for the analysis of degraded forests using geoprocessing. We produced two oil expansion scenarios. The first one reflects current trends in palm oil production expansion and deforestation in Pará State (S1). The second one considers the exclusive use of deforested/degraded land for oil palm crops (S2). The results demonstrate that degraded/deforested land in the current palm oil-producing municipalities is only sufficient for the projected level of expansion for 2020, requiring a stronger public policy to recover degraded areas for oil palm cultivation with social inclusion of family farming

On the Nature of Fossil Galaxy Groups: Are they really fossils ?

We use SDSS-DR4 photometric and spectroscopic data out to redshift z~0.1 combined with ROSAT All Sky Survey X-ray data to produce a sample of twenty-five fossil groups (FGs), defined as bound systems dominated by a single, luminous elliptical galaxy with extended X-ray emission. We examine possible biases introduced by varying the parameters used to define the sample and the main pitfalls are discussed. The spatial density of FGs, estimated via the V/V_ MAX} test, is 2.83 x 10^{-6} h_{75}^3 Mpc^{-3} for L_x > 0.89 x 10^42 h_{75}^-2 erg/s consistent with Vikhlinin et al. (1999), who examined an X-ray overluminous elliptical galaxy sample (OLEG). We compare the general properties of FGs identified here with a sample of bright field ellipticals generated from the same dataset. These two samples show no differences in the distribution of neighboring faint galaxy density excess, distance from the red sequence in the color-magnitude diagram, and structural parameters such as a$_{4}$ and internal color gradients. Furthermore, examination of stellar populations shows that our twenty-five FGs have similar ages, metallicities, and $\alpha$-enhancement as the bright field ellipticals, undermining the idea that these systems represent fossils of a physical mechanism that occurred at high redshift. Our study reveals no difference between FGs and field ellipticals, suggesting that FGs might not be a distinct family of true fossils, but rather the final stage of mass assembly in the Universe.Comment: 18 pages, Accepted to A