The Frozen Core Approximation and Nuclear Screening Effects in Single Electron Capture Collisions

Fully Differential Cross Sections (FDCS) for single electron capture from helium by heavy ion impact are calculated using a frozen core 3-Body model and an active electron 4-Body model within the first Born approximation. FDCS are presented for H+, He2+, Li3+, and C6+ projectiles with velocities of 100 keV/amu, 1 MeV/amu, and 10 MeV/amu. In general, the FDCS from the two models are found to differ by about one order of magnitude with the active electron 4-Body model showing better agreement with experiment. Comparison of the models reveals two possible sources of the magnitude difference: the inactive electron's change of state and the projectile-target Coulomb interaction used in the different models. Detailed analysis indicates that the uncaptured electron's change of state can safely be neglected in the frozen core approximation, but that care must be used in modeling the projectile-target interaction

Adaptation and Resilience of Interdependent Infrastructure Systems: a Complex Systems Perspective

The effects of disruption upon one or more components in interdependent infrastructure systems and the ability of the system to return to normal operations, is investigated in this paper. This addresses the concept of resilience, and examines the trade-off between redundancy and efficiency, as well as the adaptive ability of a system to respond to disruptions and continue to operate, albeit not necessarily as it did initially

The Impact of Settlement Design on Tropical Deforestation Rates and Resulting Land Cover Patterns

Policymakers in the Brazilian Amazon face the challenge of meeting environmental and developmental goals as cities and towns within these tropical forests continue to face migration pressure. Alternative government planning strategies have been implemented to address forest clearing in conjunction with meeting social agendas. This paper uses panel estimation methods to investigate the impact of settlement design on land use. Results indicate that new settlement designs developed to further social interaction have had a negative impact on land cover and land use transformation. Thus, while new settlement designs appear to positively impact stated social goals, including greater contact between families and access to water and services, these social advances have come at the expense of environmental goals.deforestation, land use/land cover change, smart growth, settlement design, Amazon, Brazil, Environmental Economics and Policy, Land Economics/Use,

Plug replaces weld filler as seal in complex casting

Expandable metal plug is inserted to provide a seal to support the mold core with small blocks, referred to as chaplets, during the casting of a complex volute. Weld-warpage and multiple X ray inspection are eliminated by use of this technique

Dark Matter Halos in Galaxies and Globular Cluster Populations

We combine a new, comprehensive database for globular cluster populations in all types of galaxies with a new calibration of galaxy halo masses based entirely on weak lensing. Correlating these two sets of data, we find that the mass ratio $\eta \equiv M_{GCS}/M_{h}$ (total mass in globular clusters, divided by halo mass) is essentially constant at $\langle \eta \rangle \sim 4 \times 10^{-5}$, strongly confirming earlier suggestions in the literature. Globular clusters are the only known stellar population that formed in essentially direct proportion to host galaxy halo mass. The intrinsic scatter in $\eta$ appears to be at most 0.2 dex; we argue that some of this scatter is due to differing degrees of tidal stripping of the globular cluster systems between central and satellite galaxies. We suggest that this correlation can be understood if most globular clusters form at very early stages in galaxy evolution, largely avoiding the feedback processes that inhibited the bulk of field-star formation in their host galaxies. The actual mean value of $\eta$ also suggests that about $1/4$ of the \emph{initial} gas mass present in protogalaxies collected into GMCs large enough to form massive, dense star clusters. Finally, our calibration of $\langle \eta \rangle$ indicates that the halo masses of the Milky Way and M31 are $(1.2\pm0.5)\times 10^{12} M_{\odot}$ and $(3.9\pm1.8)\times 10^{12} M_{\odot}$ respectively.Comment: 6 pages, ApJL in pres