Crossney K.B.,West Chester University
Professional Geographer | Year: 2010
U.S. housing policy strengthens the local specificity of capital through support for homeownership and the mortgage lending industry. As access to capital and homeownership rates have grown, predatory lending has emerged as a significant danger to homeowners and their surrounding communities. The geographic distribution is not well understood, likely due to the unavailability of mortgage data to identify instances of predatory lending. This article examines the spatial distribution of predatory lending in Philadelphia, Pennsylvania, using public mortgage and property data. Predatory lending is spatially clustered within the city, suggesting a spatial component of abusive lending patterns not previously addressed. U.S. housing policy and intervention strategies designed to prevent and reduce the incidence of predatory lending should address the spatial aspects of predatory lending to target efforts and prevent weakening local connections between capital and communities. © 2010 by Association of American Geographers.
Kolasinski K.W.,West Chester University
Journal of Physical Chemistry C | Year: 2010
The Turner mechanism of porous silicon formation during stain etching was developed and accepted without surface-sensitive data and without an understanding that nanostructures are being formed. Here it is shown that an oxide intermediate does not play a role in the formation of nanocrystalline porous Si films. Furthermore, a mechanistic understanding of etching and nanostructure formation leads to the formulation of seven rules for the rational design of stain etchants. These rules are used to develop three new formulations of stain etchants containing Fe 3+, VO 2 +, and Ce 4+, which are demonstrated to effectively produce porous silicon. These new formulations represent a significant advance in stain etching as they avoid many of the problems associated with common nitrate-/nitrite-based stain etchants including no need for " activation", short induction times, and the reproducible production of homogeneous films of unprecedented thickness. © 2010 American Chemical Society.
Sudol J.J.,West Chester University |
Haghighipour N.,University of Hawaii at Manoa
Astrophysical Journal | Year: 2012
Debates regarding the age and inclination of the planetary system orbiting HR 8799, and the release of additional astrometric data following the discovery of the fourth planet, prompted us to examine the possibility of constraining these two quantities by studying the long-term stability of this system at different orbital inclinations and in its high-mass configuration (7-10-10-10 M Jup). We carried out 1.5 million N-body integrations for different combinations of orbital elements of the four planets. The most dynamically stable combinations survived less than 5 Myr at inclinations of 0° and 13°, and 41, 46, and 31 Myr at 18°, 23°, and 30°, respectively. Given such short lifetimes and the location of the system on the age-luminosity diagram for low-mass objects, the most reasonable conclusion of our study is that the planetary masses are less than 7-10-10-10 M Jup and the system is quite young. Two trends to note from our work are as follows. (1) In the most stable systems, the higher the inclination, the more the coordinates for planets b and c diverge from the oldest archival astrometric data (released after we completed our N-body integrations), suggesting that either these planets are in eccentric orbits or have lower orbital inclinations than that of planet d. (2) The most stable systems place planet e closer to the central star than is observed, supporting the conclusion that the planets are more massive and the system is young. We present the details of our simulations and discuss the implications of the results. © 2012 The American Astronomical Society. All rights reserved.
Petrie G.J.D.,U.S. National Solar Observatory |
Sudol J.J.,West Chester University
Astrophysical Journal | Year: 2010
We characterize the changes in the longitudinal photospheric magnetic field during 38 X-class and 39 M-class flares within 65° of disk center using 1 minute GONG magnetograms. In all 77 cases, we identify at least one site in the flaring active region where clear, permanent, stepwise field changes occurred. The median duration of the field changes was about 15 minutes and was approximately equal for X-class and for M-class flares. The absolute values of the field changes ranged from the detection limit of ∼10 G to as high as ∼450 G in two exceptional cases. The median value was 69 G. Field changes were significantly stronger for X-class than for M-class flares and for limb flares than for disk-center flares. Longitudinal field changes less than 100 G tended to decrease longitudinal field strengths, both close to disk center and close to the limb, while field changes greater than 100 G showed no such pattern. Likewise, longitudinal flux strengths tended to decrease during flares. Flux changes, particularly net flux changes near disk center, correlated better than local field changes with GOES peak X-ray flux. The strongest longitudinal field and flux changes occurred in flares observed close to the limb. We estimate the change of Lorentz force associated with each flare and find that this is large enough in some cases to power seismic waves. We find that longitudinal field decreases would likely outnumber increases at all parts of the solar disk within 65° of disk center, as in our observations, if photospheric field tilts increase during flares as predicted by Hudson et al. © 2010. The American Astronomical Society.
Kolasinski K.W.,West Chester University
Journal of the American Chemical Society | Year: 2013
Visible or UV light activates H-terminated Si surfaces because of the presence of a photogenerated hole in a Si-Si back-bond. Enhancing the lifetime of this hole at the surface increases reactivity. On the basis of photodynamics and electron transfer theory, the prevalence of two mechanisms of photoactivation (internal photoemission versus interband photoexcitation followed by electron transfer) are explored. To act as an effective trap, an acceptor state for the excited electron must either be populated directly by photoexcitation or the state must lie in a band gap (or both). It is predicted that oxidants with a properly positioned acceptor level will enhance the reactivity of porous silicon or silicon nanocrystals in a size selective manner. © 2013 American Chemical Society.