Performance Indicators for Natural Resource and Environmental Policy: Contributions from American Institutional Law and Economics

Article published in the Duke Environmental Law & Policy Forum

A Longitudinal Analysis of Cars, Transit, and Employment Outcomes

Access to cars and transit can influence individuals’ ability to reach opportunities such as jobs, health care, and other important activities. While access to cars and public transit varies considerably across time, space, and across populations, most research portrays car access as a snapshot in time; some people have a car and others do not. But does this snapshot approach mask variation in car ownership over time? And how does access to particular types of transportation resources influence individuals’ economic outcomes? The authors improve upon existing research by using panel data from 1999 to 2013 from the Panel Study of Income Dynamics (PSID) to examine levels of automobile access in groups that have variable access: poor families, immigrants, and people of color. They further employ two new national datasets of access to jobs using public transit. These datasets are used to examine the effect of transit and automobile access on income growth over time within families, controlling for a number of relevant variables. The research found that for most families, being “carless” is a temporary condition. While 13% of families in the US are carless in any given year, only 5% of families are carless for all seven waves of data examined in the analysis. The research also found that poor families, immigrants, and people of color (particularly blacks) are considerably more likely to transition into and out car owner-ship frequently and are less likely to have a car in any survey year than are non-poor families, the US-born, and whites. The research also found that improving automobile access is associated with a decreased probability of future unemployment and is associated with greater income gains. However, the analysis suggests that the costs of owning and maintaining a car may be greater than the income gains associated with in-creased car ownership. The relationship between public transit and improved economic outcomes is less clear. The research found that living in areas with access to high-quality public transportation has no relationship with future earnings. However, transit serves an important purpose in providing mobility for those who cannot or choose not to own a car

Niche Modeling: Ecological Metaphors for Sustainable Software in Science

This position paper is aimed at providing some history and provocations for the use of an ecological metaphor to describe software development environments. We do not claim that the ecological metaphor is the best or only way of looking at software - rather we want to ask if it can indeed be a productive and thought provoking one.Comment: Position paper submitted to: Workshop on Sustainable Software for Science: Practice and Experiences (WSSSPE) SC13, Sunday, 17 November 2013, Denver, CO, US

Use of Coherent Transition Radiation to Set Up the APS RF Thermionic Gun to Produce High-Brightness Beams for SASE FEL Experiments

We describe use of the Advanced Photon Source (APS) rf thermionic gun, alpha magnet beamline, and linac to produce a stable high-brightness beam in excess of 100 amperes peak current with normalized emittance of 10 pi mm-mrad. To obtain peak currents greater than 100 amperes, the rf gun system must be tuned to produce a FWHM bunch length on the order of 350 fs. Bunch lengths this short are measured using coherent transition radiation (CTR) produced when the rf gun beam, accelerated to 40 MeV, strikes a metal foil. The CTR is detected using a Golay detector attached to one arm of a Michelson interferometer. The alpha magnet current and gun rf phase are adjusted so as to maximize the CTR signal at the Golay detector, which corresponds to the minimum bunch length. The interferometer is used to measure the autocorrelation of the CTR radiation. The minimum phase approximation is used to derive the bunch profile from the autocorrelation. The high-brightness beam is accelerated to 217 MeV and used to produce SASE in five APS undulators installed in the Low- Energy Undulator Test Line (LEUTL) experiment hall. Initial optical measurements showed a gain length of 1.3 m at 530 nm. * Work supported by U. S. Department of Energy, Office of Basic Energy Sciences, under Contract No. W-31-109-ENG-38.Comment: LINAC2000 MOB17 3 pages 8 figure