79 research outputs found
HST/ACS observations of shell galaxies: inner shells, shell colours and dust
AIM:Learn more about the origin of shells and dust in early type galaxies.
METHOD: V-I colours of shells and underlying galaxies are derived, using HST
Advanced Camera for Surveys (ACS) data. A galaxy model is made locally in
wedges and subtracted to determine shell profiles and colours. We applied
Voronoi binning to our data to get smoothed colour maps of the galaxies.
Comparison with N-body simulations from the literature gives more insight to
the origin of the shell features. Shell positions and dust characteristics are
inferred from model galaxy subtracted images. RESULT: The ACS images reveal
shells well within the effective radius in some galaxies (at 1.7 kpc in the
case of NGC 5982). In some cases, strong nuclear dust patches prevent detection
of inner shells. Most shells have colours which are similar to the underlying
galaxy. Some inner shells are redder than the galaxy. All six shell galaxies
show out of dynamical equilibrium dust features, like lanes or patches, in
their central regions. Our detection rate for dust in the shell ellipticals is
greater than that found from HST archive data for a sample of normal early-type
galaxies, at the 95% confidence level. CONCLUSIONS: The merger model describes
better the shell distributions and morphologies than the interaction model. Red
shell colours are most likely due to the presence of dust and/or older stellar
populations. The high prevalence and out of dynamical equilibrium morphologies
of the central dust features point towards external influences being
responsible for visible dust features in early type shell galaxies. Inner
shells are able to manifest themselves in relatively old shell systems.Comment: accepted by A&A; 36 Figures, 25 pages. A version with full resolution
Figures can be found here: http://www.astro.rug.nl/~sikkema/shells.p
Effect of resource spatial correlation and Hunter-Fisher-Gatherer mobility on social cooperation in Tierra del Fuego
This article presents an agent-based model designed to explore the development of cooperation
in hunter-fisher-gatherer societies that face a dilemma of sharing an unpredictable resource
that is randomly distributed in space. The model is a stylised abstraction of the
Yamana society, which inhabited the channels and islands of the southernmost part of
Tierra del Fuego (Argentina-Chile). According to ethnographic sources, the Yamana developed
cooperative behaviour supported by an indirect reciprocity mechanism: whenever
someone found an extraordinary confluence of resources, such as a beached whale, they
would use smoke signals to announce their find, bringing people together to share food and
exchange different types of social capital. The model provides insight on how the spatial
concentration of beachings and agents’ movements in the space can influence cooperation.
We conclude that the emergence of informal and dynamic communities that operate as a
vigilance network preserves cooperation and makes defection very costly.MICINN http://www.idi.mineco.gob.es/ CSD2010-00034 (SimulPast CONSOLIDER-INGENIO 2010) and HAR2009-06996; the government of Castilla y Leónhttp://www.jcyl.es/ GREX251-2009; the Argentine CONICET http://www.conicet.gov.ar/PIP-0706; and the Wenner-Gren Foundation for Anthropological Researchhttp://www.wennergren.org/ "Social Aggregation: A Yamana Society's Short Term Episode to Analyse Social Interaction, Tierra del Fuego, Argentina". The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscrip
Molecular, Cellular and Physiological Evidences for the Anorexigenic Actions of Nesfatin-1 in Goldfish
Nesfatin-1 is a recently discovered anorexigen encoded in the precursor peptide, nucleobindin-2 (NUCB2) in mammals. To date, nesfatin-1 has not been described in any non-mammalian species, although some information is available in the sequenced genomes of several species. Our objective was to characterize nesfatin-1 in fish.In the present study, we employed molecular, immunohistochemical, and physiological studies to characterize the structure, distribution, and appetite regulatory effects of nesfatin-1 in a non-mammalian vertebrate. A very high conservation in NUCB2 sequences, especially in the nesfatin-1 region was found in lower vertebrates. Abundant expression of NUCB2 mRNA was detected in several tissues including the brain and liver of goldfish. Nesfatin-1-like immunoreactive cells are present in the feeding regulatory nucleus of the hypothalamus and in the gastrointestinal tract of goldfish. Approximately 6-fold increase in NUCB2 mRNA levels was found in the liver after 7-day food-deprivation, and a similar increase was also found after short-term fasting. This points toward a possible liver specific role for NUCB2 in the control of metabolism during food-deprivation. Meanwhile, ∼2-fold increase at 1 and 3 h post-feeding and an ∼3-fold reduction after a 7-day food-deprivation was observed in NUCB2 mRNA in the goldfish hypothalamus. In vivo, a single intraperitoneal injection of the full-length native (goldfish; gf) nesfatin-1 at a dose of 50 ng/g body weight induced a 23% reduction of food intake one hour post-injection in goldfish. Furthermore, intracerebroventricular injection of gfnesfatin-1 at a dose of 5 ng/g body weight resulted in ∼50% reduction in food intake.Our results provide molecular, anatomical and functional evidences to support potential anorectic and metabolic roles for endogenous nesfatin-1 in goldfish. Collectively, we provide novel information on NUCB2 in non-mammals and an anorexigenic role for nesfatin-1 in goldfish
Mesoscopic effects in an agent-based bargaining model in regular lattices
The effect of spatial structure has been proved very relevant in repeated games. In this work we propose an agent based
model where a fixed finite population of tagged agents play iteratively the Nash demand game in a regular lattice. The
model extends the multiagent bargaining model by Axtell, Epstein and Young [1] modifying the assumption of global
interaction. Each agent is endowed with a memory and plays the best reply against the opponent’s most frequent demand.
We focus our analysis on the transient dynamics of the system, studying by computer simulation the set of states in which
the system spends a considerable fraction of the time. The results show that all the possible persistent regimes in the global
interaction model can also be observed in this spatial version. We also find that the mesoscopic properties of the interaction
networks that the spatial distribution induces in the model have a significant impact on the diffusion of strategies, and can
lead to new persistent regimes different from those found in previous research. In particular, community structure in the
intratype interaction networks may cause that communities reach different persistent regimes as a consequence of the
hindering diffusion effect of fluctuating agents at their borders.Spanish Ministry of Science and Innovation, references TIN2008-06464-C03-02 and CSD2010-00034 (CONSOLIDER-INGENIO 2010), and by the Junta de Castilla y Leon, references VA006A009, BU034A08 and GREX251-200
MAGAL Constellation -- Using a Small Satellite Altimeter Constellation to Monitor Local and Regional Ocean and Inland Water Variations
Marketing as a means to transformative social conflict resolution: lessons from transitioning war economies and the Colombian coffee marketing system
Social conflicts are ubiquitous to the human condition and occur throughout markets, marketing processes, and marketing systems.When unchecked or unmitigated, social conflict can have devastating consequences for consumers, marketers, and societies, especially when conflict escalates to war. In this article, the authors offer a systemic analysis of the Colombian war economy, with its conflicted shadow and coping markets, to show how a growing network of fair-trade coffee actors has played a key role in transitioning the country’s war economy into a peace economy. They particularly draw attention to the sources of conflict in this market and highlight four transition mechanisms — i.e., empowerment, communication, community building and regulation — through which marketers can contribute to peacemaking and thus produce mutually beneficial outcomes for consumers and society. The article concludes with a discussion of implications for marketing theory, practice, and public policy
Functional annotation of human long noncoding RNAs via molecular phenotyping
Long noncoding RNAs (lncRNAs) constitute the majority of transcripts in the mammalian genomes, and yet, their functions remain largely unknown. As part of the FANTOM6 project, we systematically knocked down the expression of 285 lncRNAs in human dermal fibroblasts and quantified cellular growth, morphological changes, and transcriptomic responses using Capped Analysis of Gene Expression (CAGE). Antisense oligonucleotides targeting the same lncRNAs exhibited global concordance, and the molecular phenotype, measured by CAGE, recapitulated the observed cellular phenotypes while providing additional insights on the affected genes and pathways. Here, we disseminate the largest-todate lncRNA knockdown data set with molecular phenotyping (over 1000 CAGE deep-sequencing libraries) for further exploration and highlight functional roles for ZNF213-AS1 and lnc-KHDC3L-2.Peer reviewe
Mechanism of imidazolium ionic liquids toxicity in Saccharomyces cerevisiae and rational engineering of a tolerant, xylose-fermenting strain
Faith and Fair Trade: The Moderating Role of Contextual Religious Salience
Normative and historical arguments support the idea that religion potentially shapes decisions to support fair trade products. That said, the question of how religion influences organizational decision-makers to purchase fair trade products in a business-to-business context has remained largely unaddressed. This research examines the interactive effect of individual religious commitment and contextual religious salience on an individual's willingness to pay a price premium for a fair trade product, when buying on behalf of an organization. Findings from two experimental studies (involving 75 and 87 working individuals, respectively) reveal that the effect of a decision-maker's religious commitment on his or her willingness to pay a price premium, for the purchase of a fair trade product on behalf of an organization, is moderated by the contextual salience of religion. Specifically, when religion is highly salient in the organizational context, religious commitment is positively related to the decision-maker's willingness to pay a premium for the fair trade product; when contextual religious salience is low, religious commitment and willingness to pay a premium are unrelated. Implications for theory and practice are presented. © 2013 Springer Science+Business Media Dordrecht
Effect of methylimidazole on cellulose/ionic liquid solutions and regenerated material therefrom
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