2,958 research outputs found

    Mass and motion of globulettes in the Rosette Nebula

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    We have investigated tiny molecular clumps in the Rosette Nebula. Radio observations were made of molecular line emission from 16 globulettes identified in a previous optical survey. In addtion, we collected images in the NIR broad-band JHKs and narrow-band Paschen beta and H2. Ten objects, for which we collected information from several transitions in 12CO and 13CO were modelled using a spherically symmetric model. The best fit to observed line ratios and intensities was obtained by assuming a model composed of a cool and dense centre and warm and dense surface layer. The average masses derived range from about 50 to 500 Jupiter masses, which is similar to earlier estimates based on extinction measures. The globulettes selected are dense, with very thin layers of fluorescent H2 emission. The NIR data shows that several globulettes are very opaque and contain dense cores. Because of the high density encountered already at the surface, the rims become thin, as evidenced by our P beta images. We conclude that the entire complex of shells, elephant trunks, and globulettes in the northern part of the nebula is expanding with nearly the same velocity of ~22 km/s, and with a very small spread in velocity among the globulettes. Some globulettes are in the process of detaching from elephant trunks and shells, while other more isolated objects must have detached long ago and are lagging behind in the general expansion of the molecular shell. The suggestion that some globulettes might collapse to form planetary-mass objects or brown dwarfs is strengthened by our finding of dense cores in several objects.Comment: 15 pages, 15 figures Astronomy and Astrophysics 201

    Broken Punishment Networks in Public Goods Games: Experimental Evidence

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    Abundant evidence suggests that high levels of contributions to public goods can be sustained through self-governed monitoring and sanctions. This experimental study investigates the effectiveness of decentralized sanctioning institutions where punishment opportunities are restricted to agents who are linked through alternative punishment networks. We find that the structure of the punishment network significantly impacts contributions to the public good, but not overall efficiencies. Contributions collapse over decision rounds in groups with limited punishment opportunities, even if the absolute punishment capacity corresponds to the complete punishment network where all agents are allowed to punish each other. However, after allowing for the costs of sanctions, efficiencies are similar across the different networks that allow for punishment and the no-punishment network.public goods experiment, punishment, cooperation, networks

    SPARX: A modeling system for Solar Energetic Particle Radiation SpaceWeather forecasting

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    The capability to predict the parameters of an SEP event such as its onset, peak flux, and duration is critical to assessing any potential space weather impact. We present a new flexible modeling system simulating the propagation of Solar Energetic Particles (SEPs) from locations near the Sun to any given location in the heliosphere to forecast the SEP flux profiles. Solar Particle Radiation SWx (SPARX) uses an innovative methodology that allows implementation within an operational framework to overcome the time constraints of test particle modeling of SEP profiles, allowing the production of near-real-time SEP nowcasts and forecasts, when paired with appropriate near-real-time triggers. SPARX has the capability to produce SEP forecasts within minutes of being triggered by observations of a solar eruptive event. The model is based on the test particle approach and is spatially 3-D, thus allowing for the possibility of transport in the direction perpendicular to the magnetic field. The model naturally includes the effects of perpendicular propagation due to drifts and drift-induced deceleration. The modeling framework and the way in which parameters of relevance for Space Weather forecasting are obtained are described. The first results from the modeling system are presented. These resultsThese results demonstrate that corotation and drift of SEPtreams play an important role in shaping SEP flux profile

    The New Agent: A Qualitative Study to Strategically Adapt New Agent Professional Development

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    The qualitative study reported here assessed the needs of agents related to new agent professional development to improve the current model. Agents who participated in new agent professional development within the last 5 years were selected to participate in focus groups to determine concerns and continued needs. Agents enjoyed networking and struggled with the time away from their home counties. Recommendations for improvement include integrating the idea of pre-entry competencies, developing online new agent professional development sessions, introducing new agents to existing communities of practice, developing new communities of practice, and developing more resources for new agents

    The Impact of New Media on Policy Affecting Agriculture

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    New media have changed the way people communicate and transfer information, but their effects on agenda-setting and the transfer of salience of objects and attributes have not been explored empirically. This study utilized a quantitative content analysis to determine how the blogosphere affects the agricultural policy agenda by analyzing a specific piece of policy that has the potential to effect agriculture. Results indicate a significant predictive relationship of the blogosphere agenda, media agenda, interest group agenda, and public agenda to the policy agenda. This adds new information on agenda-setting in an online environment by concluding agenda-setting occurs in new media environments similarly to traditional media environments. Future studies should consider the influence of the blogosphere on the political agenda
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