High resolution CO images of Seyfert Galaxies

The CO (J = 1-0) emission of three Seyfert galaxies, NGC 3227, NGC 7469, and NGC 5033 was imaged. The CO emission in NGC 3227 and NGC 7469 appears as compact structures centered on the active nuclei, containing substantial fractions of the single-dish flux. In NGC 3227, 10 percent of the CO flux detected by the interferometer is contained within the ionized narrow-line region. The unresolved molecular gas concentrations in the nucleus of NGC 3227 imply a CO mass of 65 million solar masses concentrated within a diameter less than 50 pc. The CO emission in NGC 5033 is not detected at this resolution, implying a CO structure size of 20 to 60 arcsec. Continuum emission at 2.7 mm is not detected in any of the three galaxies. In the center of NGC 7469, the H2 mass is comparable to the dynamical mass. Kinematic studies of the detected gas reveal a rotational motion of the gas in NGC 3227 and NGC 7469, allowing identification of the gas in NGC 7469 with a nuclear starburst. These data are consistent with the idea that interactions between galaxies cause gas to concentrate in their nuclei thereby feeding starburst and Seyfert activity

Defining a Primary Market and Estimating Demand for Major Bicycle-Sharing Program in Philadelphia, Pennsylvania.

Public bicycle-sharing (bike share) programs have become increasingly popular in recent years, particularly in Europe, with a number of cities recently implementing systems and high levels of usage. North American efforts have been more limited to date, with high-profile recent examples including a small program in Washington, D.C., and a substantial seasonal program in Montreal, Canada. Because there are no established large-scale programs in the United States, planners exploring potential system designs and feasibilities are faced with an unusual degree of uncertainty about who would ride, where they might ride, and how often they might ride. A large-scale bike share system is under consideration in Philadelphia, Pennsylvania. This paper discusses the methods and findings of a two-phase project that (a) used a raster-based geographic information system analysis to identify a primary geographic market area for a bike share program and (b) applied bike share trip diversion rates observed in peer European cities to estimate daily bike share trips in the primary market area. This analysis resulted in estimates for daily usage in Philadelphia that ranged from roughly 6,000 to 23,000 for two scales of market area and three demand scenarios (low, middle, and high). As bike share systems continue to proliferate in different settings, new data can refine the methods used here to provide increasing levels of certainty in the future