NGC 2782: a merger remnant with young stars in its gaseous tidal tail

We have searched for young star-forming regions around the merger remnant NGC 2782. By using GALEX FUV and NUV imaging and HI data we found seven UV sources, located at distances greater than 26 kpc from the center of NGC 2782, and coinciding with its western HI tidal tail. These regions were resolved in several smaller systems when Gemini/GMOS r-band images were used. We compared the observed colors to stellar population synthesis models and we found that these objects have ages of ~1 to 11 Myr and masses ranging from 10^3.9 to 10^4.6 Msun. By using Gemini/GMOS spectroscopic data we confirm memberships and derive high metallicities for three of the young regions in the tail (12+log(O/H)=8.74\pm0.20, 8.81\pm0.20 and 8.78\pm0.20). These metallicities are similar to the value presented by the nuclear region of NGC 2782 and also similar to the value presented for an object located close to the main body of NGC 2782. The high metallicities measured for the star-forming regions in the gaseous tidal tail of NGC 2782 could be explained if they were formed out of highly enriched gas which was once expelled from the center of the merging galaxies when the system collided. An additional possibility is that the tail has been a nursery of a few generations of young stellar systems which ultimately polluted this medium with metals, further enriching the already pre-enriched gas ejected to the tail when the galaxies collided.Comment: 11 pages, 5 figures. Accepted for publication in MNRA

Product Analytics Based On Demographic Democratization

Product analytics is a blend of computational methods with the express purpose of facilitating the multifaceted process of decision-making based on demographic and consumer preferences.  This complex subject is derived from consensus theory and includes structured analytics, categories, and the combination of evidence.  The methodology is applicable to a wide range of business, economic, social, political, and strategic decisions.  The paper describes a product allocation application to demonstrate the concepts

Global Perspectives and Experiences of Community Psychologists for the Promotion of Social Change and the Construction of Radical Solidarities

In this special issue we seek to document and learn from exemplars from around the world of interventions and other forms of applied work in organisational, community, and everyday social settings that are aimed at producing social change and changing oppressive social and cultural realities. This introduction presents the colonial origins of oppression and strategies for building social change based on radical solidarity. Colonialism, violence, and social inequality are interconnected. We realize that it is urgent to generate solitarily social change to transform these historical and transnational realities of oppression. Social change is realized through the praxis developed in historically deprived community contexts, respecting individuals' cultural and identity characteristics. Radical solidarity is necessary to question possible practices of colonial tutelage of communities. Likewise, praxis for social change must be developed creatively at the various levels of action and respect the intersectional trajectories of groups and individuals. We present diverse praxis experiences for social change in different contexts and levels of action developed by community psychologists, seeking to build a network of radical solidarity focused on dismantling colonial power

Global Perspectives and Experiences of Community Psychologists for the Promotion of Social Change and the Construction of Radical Solidarities

In this special issue we seek to document and learn from exemplars from around the world of interventions and other forms of applied work in organisational, community, and everyday social settings that are aimed at producing social change and changing oppressive social and cultural realities. This introduction presents the colonial origins of oppression and strategies for building social change based on radical solidarity. Colonialism, violence, and social inequality are interconnected. We realize that it is urgent to generate solitarily social change to transform these historical and transnational realities of oppression. Social change is realized through the praxis developed in historically deprived community contexts, respecting individuals' cultural and identity characteristics. Radical solidarity is necessary to question possible practices of colonial tutelage of communities. Likewise, praxis for social change must be developed creatively at the various levels of action and respect the intersectional trajectories of groups and individuals. We present diverse praxis experiences for social change in different contexts and levels of action developed by community psychologists, seeking to build a network of radical solidarity focused on dismantling colonial power

A proposed mechanism for nitrogen acquisition by grass seedlings through oxidation of symbiotic bacteria

In this paper we propose and provide evidence for a mechanism, oxidative nitrogen scavenging (ONS), whereby seedlings of some grass species may extract nitrogen from symbiotic diazotrophic bacteria through oxidation by plant-secreted reactive oxygen species (ROS). Experiments on this proposed mechanism employ tall fescue (Festuca arundinaceae) seedlings to elucidate features of the oxidative mechanism. We employed 15N2 gas assimilation experiments to demonstrate nitrogen fixation, direct microscopic visualization of bacteria on seedling surfaces to visualize the bacterial oxidation process, reactive oxygen probes to test for the presence of H2O2 and cultural experiments to assess conditions under which H2O2 is secreted by seedlings. We also made surveys of the seedlings of several grass species to assess the distribution of the phenomenon of microbial oxidation in the Poaceae. Key elements of the proposed mechanism for nitrogen acquisition in seedlings include: 1) diazotrophic bacteria are vectored on or within seeds; 2) at seed germination bacteria colonize seedling roots and shoots; 3) seedling tissues secrete ROS onto bacteria; 4) bacterial cell walls, membranes, nucleic acids, proteins and other biological molecules are oxidized; 5) nitrates and/or smaller fragments of organic nitrogen-containing molecules resulting from oxidation may be absorbed by seedling tissues and larger peptide fragments may be further processed by secreted or cell wall plant proteases until they are small enough for transport into cells. Hydrogen peroxide secretion from seedling roots and bacterial oxidation was observed in several species in subfamily Pooideae where seeds possessed adherent paleas and lemmas, but was not seen in grasses that lacked this feature or long-cultivated crop species

Coupled-channels effects in elastic scattering and near-barrier fusion induced by weakly bound nuclei and exotic halo nuclei

The influence on fusion of coupling to the breakup process is investigated for reactions where at least one of the colliding nuclei has a sufficiently low binding energy for breakup to become an important process. Elastic scattering, excitation functions for sub-and near-barrier fusion cross sections, and breakup yields are analyzed for $^{6,7}$Li+$^{59}$Co. Continuum-Discretized Coupled-Channels (CDCC) calculations describe well the data at and above the barrier. Elastic scattering with $^{6}$Li (as compared to $^{7}$Li) indicates the significant role of breakup for weakly bound projectiles. A study of $^{4,6}$He induced fusion reactions with a three-body CDCC method for the $^6$He halo nucleus is presented. The relative importance of breakup and bound-state structure effects on total fusion is discussed.Comment: 29 pages, 9 figure

Growth and mortality of Ctenochaetus striatus, Stegastes nigricans and Sargocentron microstoma in Tiahura Reef, Moorea Island, French Polynesia

Growth parameters and mortality rates were estimated from length-frequency data sampled in 1982, using the FiSAT software, for three coral reef fish species, the surgeon fish (Ctenochaetus striatus), the damselfish (Stegastes nigricans) and the squirrel fish (Sargocentron microstoma) in Tiahura Reef, Moorea Island, French Polynesia

Validity of the Néel-Arrhenius model for highly anisotropic CoxFe3−xO4 nanoparticles

We report a systematic study on the structural and magnetic properties of CoxFe3−xO4 magnetic nanoparticles with sizes between 5 and 25 nm, prepared by thermal decomposition of Fe(acac)3 and Co(acac)2. The large magneto-crystalline anisotropy of the synthesized particles resulted in high blocking temperatures (42 K < TB < 345 K for 5 < d < 13 nm) and large coercive fields (HC ≈ 1600 kA/m for T = 5 K). The smallest particles (⟨d⟩=5 nm) revealed the existence of a magnetically hard, spin-disordered surface. The thermal dependence of static and dynamic magnetic properties of the whole series of samples could be explained within the Neel–Arrhenius relaxation framework by including the thermal dependence of the magnetocrystalline anisotropy constant K1(T), without the need of ad-hoc corrections. This approach, using the empirical Brükhatov-Kirensky relation, provided K1(0) values very similar to the bulk material from either static or dynamic magnetic measurements, as well as realistic values for the response times (τ0 ≈ 10−10s). Deviations from the bulk anisotropy values found for the smallest particles could be qualitatively explained based on Zener's relation between K1(T) and M(T).This work was supported by the Spanish Ministerio de Economia y Competitividad (MINECO, Project Nos. MAT2010-19326 and MAT2013-42551).Peer Reviewe