5,593 research outputs found

    Overcoming Obstacles to the Siting of Solid Waste Management Facilities

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    [S IV] in the NGC 5253 Supernebula: Ionized Gas Kinematics at High Resolution

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    The nearby dwarf starburst galaxy NGC 5253 hosts a deeply embedded radio-infrared supernebula excited by thousands of O stars. We have observed this source in the 10.5{\mu}m line of S+3 at 3.8 kms-1 spectral and 1.4" spatial resolution, using the high resolution spectrometer TEXES on the IRTF. The line profile cannot be fit well by a single Gaussian. The best simple fit describes the gas with two Gaussians, one near the galactic velocity with FWHM 33.6 km s-1 and another of similiar strength and FWHM 94 km s-1 centered \sim20 km s-1 to the blue. This suggests a model for the supernebula in which gas flows towards us out of the molecular cloud, as in a "blister" or "champagne flow" or in the HII regions modelled by Zhu (2006).Comment: Accepted for publication in the Astrophysical Journal 4 June 201

    Returning to Learning: Adults' Success in College Is Key to America's Future

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    Provides an overview of research on adult learners' characteristics, risk factors, and needs at four-year institutions and in for-credit and non-credit courses, and what changes institutions and governments can implement to help adult students succeed

    NGC 4102: High Resolution Infrared Observations of a Nuclear Starburst Ring

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    The composite galaxy NGC 4102 hosts a LINER nucleus and a starburst. We mapped NGC 4102 in the 12.8 micron line of [NeII], using the echelon spectrometer TEXES on the NASA IRTF, to obtain a data cube with 1.5" spatial and 25 km/s spectral, resolution. Combining near-infrared, radio, and the [NeII] data shows that the extinction to the starburst is substantial, more than 2 magnitudes at K band, and that the neon abundance is less than half solar. We find that the star formation in the nuclear region is confined to a rotating ring or disk of 4.3" (~300 pc) diameter, inside the Inner Lindblad Resonance. This region is an intense concentration of mass, with a dynamical mass of ~3 x 10^9 solar masses, and of star formation. The young stars in the ring produce the [NeII] flux reported by Spitzer for the entire galaxy. The mysterious blue component of line emission detected in the near-infrared is also seen in [NeII]; it is not a normal AGN outflow.Comment: submitted to Ap

    Trading on Preconceptions: Why World War I Was Not a Failure of Economic Interdependence

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    World War I is generally viewed by both advocates and critics of commercial liberal theory as the quintessential example of a failure of economic integration to maintain peace. Yet this consensus relies on both methodologically flawed inference and an incomplete accounting of the antecedents to the war. Crucially, World War I began in a weakly integrated portion of Europe with which highly integrated powers were entangled through the alliance system. Crises among the highly interdependent European powers in the decades leading up to the war were generally resolved without bloodshed. Among the less interdependent powers in Eastern Europe, however, crises regularly escalated to militarized violence. Moreover, the crises leading to the war created increased incentives for the integrated powers to strengthen commitments to their less interdependent partners. In attempting to make these alliances more credible, Western powers shifted foreign policy discretion to the very states that lacked strong economic disincentives to fight. Had globalization pervaded Eastern Europe, or if the rest of Europe had been less locked into events in the east, Europe might have avoided a “Great War.” </jats:p

    The SISO CSPI PDG standard for commercial off-the-shelf simulation package interoperability reference models

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    For many years discrete-event simulation has been used to analyze production and logistics problems in manufactur-ing and defense. Commercial-off-the-shelf Simulation Packages (CSPs), visual interactive modelling environ-ments such as Arena, Anylogic, Flexsim, Simul8, Witness, etc., support the development, experimentation and visua-lization of simulation models. There have been various attempts to create distributed simulations with these CSPs and their tools, some with the High Level Architecture (HLA). These are complex and it is quite difficult to assess how a set of models/CSP are actually interoperating. As the first in a series of standards aimed at standardizing how the HLA is used to support CSP distributed simula-tions, the Simulation Interoperability Standards Organiza-tion’s (SISO) CSP Interoperability Product Development Group (CSPI PDG) has developed and standardized a set of Interoperability Reference Models (IRM) that are in-tended to clearly identify the interoperability capabilities of CSP distributed simulations

    Summer Drivers of Atmospheric Variability Affecting Ice Shelf Thinning in the Amundsen Sea Embayment, West Antarctica

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    Satellite data and a 35-year hindcast of the Amundsen Sea Embayment summer climate using the Weather Research and Forecasting model are used to understand how regional and large-scale atmospheric variability affects thinning of ice shelves in this sector of West Antarctica by melting from above and below (linked to intrusions of warm water caused by anomalous westerlies over the continental shelf edge). El Nino episodes are associated with an increase in surface melt but do not have a statistically significant impact on westerly winds over the continental shelf edge. The location of the Amundsen Sea Low and the polarity of the Southern Annular Mode (SAM) have negligible impact on surface melting, although a positive SAM and eastward shift of the Amundsen Sea Low cause anomalous westerlies over the continental shelf edge. The projected future increase in El Nino episodes and positive SAM could therefore increase the risk of disintegration of West Antarctic ice shelves
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