Spitzer Space Telescope Observations of Low Mass X-ray Binaries

We present preliminary results from our archival Spitzer Space Telescope program aimed at characterizing the mid-IR properties of compact objects, both isolated and in binary systems, i.e. white dwarfs, X-ray binaries, cataclysmic variables, and magnetars. Most of these sources are too faint at mid-IR wavelengths to be observable from the ground, so this study provides the very first comprehensive look at the mid-IR emission of these objects. Here we present our results for the low mass X-ray binaries. We considered all of the systems listed in the most recent catalog of Liu et al. (2007) that have known optical counterparts. The particular goals of our projects encompass: to establish the mid-IR spectral energy distribution, to search for the signatures of jets, circumbinary disks, low mass or planetary companions and debris disks, and to study the local environment of these sources.Comment: 6 pages, updated and expanded version of article to appear in Proceedings of "A Population Explosion: The Nature and Evolution of X-ray Binaries in Diverse Environments", 28 Oct - 2 Nov, St. Pete Beach, FL; eds. R.M. Bandyopadhyay, S. Wachter, D. Gelino, C.R. Gelino; AIP Conference Proceedings Serie

Conductance of electrolytes in 1-propanol solutions from −40 to 25°C

Conductance data for solutions of LiCl, NaBr, NaI, KI, KSCN, RbI, Et4NI, Pr4NI, Bu4NI, Bu4NClO4, n-Am4NI, i-Am4NI, n-Hept4NI, Me2Bu2NI, MeBu3NI, EtBu3NI, i-Am3BuNI, and i-Am3BuNBPh4 in 1-propanol at –40, –30, –20, –10, 0, 10, and 25°C are communicated and discussed. Evaluation of the data is performed on the basis of a conductance equation that includes a term in c3/2. Single ion conductances at 25 and 10°C are determined with the help of transference numbers t o + (KSCN/PrOH); the data are compared to data estimated by other methods. Ion-pair association constants and their temperature dependence are discussed in terms of contact and solvent separated ion pairs, and the role of non-coulombic forces is shown with the help of an appropriate splitting of the Gibbs energy of ion-pair formation

Borrowing Constraints and the Tenure Choice of Young Households

In this paper we analyze the factors that affect the tenure choice of young adults, highlighting the impact of mortgage lender imposed borrowing constraints. The data set is a panel of youth age 20-33 for the years 1985-90. Our methods differ from most prior studies in many ways including consideration of possible sample selection bias, a richer model of the stochastic error structure, better measurement of which households are bound by borrowing constraints, and a fuller consideration of the endogeneity of wealth and income. Once all changes are implemented, we find ownership tendencies to be quite sensitive to economic variables. Specifically, potential earnings, the relative cost of owning a home, and especially borrowing constraints affect the tendency to own a home. In our sample of youth, 37% of households are constrained even after choosing their loan-to-value ratio to minimize the impact of the separate wealth and income requirements. The constraints reduce the probability of ownership of these households by 10 to 20 percentage points (a third to a half) depending on the particular characteristics of the household.

Green investment strategies: a positive force in cities

Deterioration of urban neighborhoods is known to induce out migration, but how well do public investments to reverse decline actually work? To evaluate Philadelphia’s greening investment, researchers measured property buyers’ willingness to pay more—and found that greening works.Community development