139 research outputs found

    DR21 Main: A Collapsing Cloud

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    The molecular cloud, DR21 Main, is an example of a large-scale gravitational collapse about an axis near the plane of the sky where the collapse is free of major disturbances due to rotation or other effects. Using flux maps, polarimetric maps, and measurements of the field inclination by comparing the line widths of ion and neutral species, we estimate the temperature, mass, magnetic field, and the turbulent kinetic, mean magnetic, and gravitational potential energies, and present a 3D model of the cloud and magnetic field.Comment: 27 Pages, submitted to ApJ, corrected typos, referee comments adde

    Dispersion of Magnetic Fields in Molecular Clouds. II.

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    We expand our study on the dispersion of polarization angles in molecular clouds. We show how the effect of signal integration through the thickness of the cloud as well as across the area subtended by the telescope beam inherent to dust continuum measurements can be incorporated in our analysis to correctly account for its effect on the measured angular dispersion and inferred turbulent to large-scale magnetic field strength ratio. We further show how to evaluate the turbulent magnetic field correlation scale from polarization data of sufficient spatial resolution and high enough spatial sampling rate. We apply our results to the molecular cloud OMC-1, where we find a turbulent correlation length of ÎŽ ≈ 16 mpc, a turbulent to large-scale magnetic field strength ratio of approximately 0.5, and a plane-of-the-sky large-scale magnetic field strength of approximately 760 ÎŒG

    Neighborhood Retail Commercial Study: Cleveland, Ohio

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    While affordable housing is the foundation of neighborhood revitalization, retail commercial development is also a pressing development issue facing urban legacy city neighborhoods. Retail opportunity in urban legacy city neighborhoods has been decimated over many years as population has declined, and competing commercial centers have blossomed. And yet, retail commercial development holds opportunities for local community resident investment and entrepreneurship, training of youth and others in entry-level jobs, and creation of vibrant opportunities for resident and business interaction. This project was defined to answer some critical questions about retail development in urban neighborhoods. What are the typical urban shopping patterns, as opposed to the suburban patterns that are used in standard market studies? How do households with varying purchasing power drive the economic demand in their neighborhoods – and what role do outside shoppers play? In the shadow of significant general merchandise and big-box retail development, what could and should be the “critical mass” of retail development in a typical neighborhood main street that can thrive, and for which neighborhood developers and merchants’ associations can strive? To study these questions, six typical neighborhoods in Cleveland were selected for analysis. Methodology included a survey of over 700 residents and visitors at neighborhood events; interviews of key informants in the banking, real estate, CDC, nonprofit, merchant and City sectors; competitor analysis; demographic and employment analysis; a detailed inventory of neighborhood businesses; and a niche analysis of supply and demand in each neighborhood. Neighborhoods were also compared to each other. Findings included a higher level of neighborhood loyalty to convenient local shopping than might be expected, perhaps a reflection of the high proportion of households without access to a car; and sizeable leakage in multiple categories. Beauty salons and barber shops, auto repair, grocery, convenience, and full service restaurants showed the greatest strength across all neighborhoods. There was no apparent pattern of retail square footage quantity in relation to population, households or neighborhood Primary Market Area purchasing power. Findings underscore the need for continued focus on housing, critical mass in close proximity, strengthening neighborhood anchor assets, and promoting business success strategies in order to support viable commercial retail main streets in the long term

    North American Free Trade and U.S. Agriculture

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    4 pp., 1 figureThe use of trade agreements to achieve both domestic and international trade policy objectives is increasing. This may cause either more market access and rising exports, or more import competition and lower prices. This publication provides a long-term view of U.S.-Mexico trade and the implications of the North American Free Trade Agreement (NAFTA)

    Dispersion of Magnetic Fields in Molecular Clouds. I

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    We describe a method for determining the dispersion of magnetic field vectors about large-scale fields in turbulent molecular clouds. The method is designed to avoid inaccurate estimates of magnetohydrodynamic or turbulent dispersion - and help avoiding inaccurate estimates of field strengths - due to large-scale, non-turbulent field structure when using the well-known method of Chandrasekhar and Fermi. Our method also provides accurate, independent estimates of the turbulent to large-scale magnetic field strength ratio. We discuss applications to the molecular clouds OMC-1, M17, and DR21(Main).Comment: 19 pages, 2 figures, 1 table, accepted for publication in the Ap
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