A Longitudinal Analysis of the Impact of Child Custody Loss on Drug Use and Crime Among a Sample of African American Mothers

This study examines the influence of child custody loss on drug use and crime among a sample of African American mothers. Two types of custody loss are examined: informal custody loss (child living apart from mother but courts not involved), and official loss (child removed from mother’s care by authorities). Methods—Using data from 339 African American women, longitudinal random coefficient models analyzed the effects of each type of custody loss on subsequent drug use and crime. Results—Results indicated that both informal and official custody loss predicted increased drug use, and informal loss predicted increased criminal involvement. Findings demonstrate that child custody loss has negative health implications for African American mothers, potentially reducing their likelihood of regaining or retaining custody of their children. Conclusions—This study highlights the need to integrate drug treatment and other types of assistance into family case plans to improve reunification rates and outcomes among mothers, children, and families. Additionally, the finding that informal loss predicts increased drug use suggests that community-based efforts within the mother’s social network could be implemented to intervene before child welfare system involvement becomes necessary

The Dark Halo - Spheroid Conspiracy and the Origin of Elliptical Galaxies

Dynamical modeling and strong lensing data indicate that the total density profiles of early-type galaxies are close to isothermal, i.e., rho_tot ~ r^gamma with gamma approx -2. To understand the origin of this universal slope we study a set of simulated spheroids formed in isolated binary mergers as well as the formation within the cosmological framework. The total stellar plus dark matter density profiles can always be described by a power law with an index of gamma approx -2.1 with a tendency toward steeper slopes for more compact, lower-mass ellipticals. In the binary mergers the amount of gas involved in the merger determines the precise steepness of the slope. This agrees with results from the cosmological simulations where ellipticals with steeper slopes have a higher fraction of stars formed in situ. Each gas-poor merger event evolves the slope toward gamma ~ -2, once this slope is reached further merger events do not change it anymore. All our ellipticals have flat intrinsic combined stellar and dark matter velocity dispersion profiles. We conclude that flat velocity dispersion profiles and total density distributions with a slope of gamma ~ -2 for the combined system of stars and dark matter act as a natural attractor. The variety of complex formation histories as present in cosmological simulations, including major as well as minor merger events, is essential to generate the full range of observed density slopes seen for present-day elliptical galaxies.Comment: Accepted by the Astrophysical Journal, 17 pages, 12 figure

Short-lived star-forming giant clumps in cosmological simulations of z~2 disks

Many observed massive star-forming z\approx2 galaxies are large disks that exhibit irregular morphologies, with \sim1kpc, \sim10^(8-10)Msun clumps. We present the largest sample to date of high-resolution cosmological SPH simulations that zoom-in on the formation of individual M*\sim10^(10.5)Msun galaxies in \sim10^(12)Msun halos at z\approx2. Our code includes strong stellar feedback parameterized as momentum-driven galactic winds. This model reproduces many characteristic features of this observed class of galaxies, such as their clumpy morphologies, smooth and monotonic velocity gradients, high gas fractions (f_g\sim50%) and high specific star-formation rates (\gtrsim1Gyr^(-1)). In accord with recent models, giant clumps (Mclump\sim(5x10^8-10^9)Msun) form in-situ via gravitational instabilities. However, the galactic winds are critical for their subsequent evolution. The giant clumps we obtain are short-lived and are disrupted by wind-driven mass loss. They do not virialise or migrate to the galaxy centers as suggested in recent work neglecting strong winds. By phenomenologically implementing the winds that are observed from high-redshift galaxies and in particular from individual clumps, our simulations reproduce well new observational constraints on clump kinematics and clump ages. In particular, the observation that older clumps appear closer to their galaxy centers is reproduced in our simulations, as a result of inside-out formation of the disks rather than inward clump migration.Comment: 11 pages, 6 figures, 1 table. Accepted for publication in the Astrophysical Journa

The LEAF Platform: Incremental Enhancements for the J2EE

LEAF, the Lean and Extensible Architectural Framework, is an enhancement wrapper for J2EE implementations. Basically, LEAF fixes some identified J2EE issues and extends, as well as simplifies, the use of the J2EE by providing several incremental improvements. These improvements are seamlessly integrated, include an additional component type, allow the same interfaces for local and remote service implementations, offer better J2EE implementation compatibility and ORB interceptors, and encompass several new technical services. This paper explains the need for LEAF through a diagnosis of the J2EE, presents the fundamental concepts underlying LEAF, overviews its implementation, reports on field experiences from using it in a number of commercial projects, and points out some interesting tradeoffs in using the J2EE with and without LEAF

Forming Early-Type Galaxies in LambdaCDM Simulations -I. Assembly histories

We present a sample of nine high resolution cosmological simulations in the mass range of M_vir=7x10^11-4x10^12 M_sun starting from LambdaCDM initial conditions. Our simulations include primordial radiative cooling, photoionization, star formation, supernova II feedback, but exclude supernova driven winds and AGN feedback. The simulated galaxies assemble in two phases, with the initial growth dominated by compact (r<r_eff) in situ star formation fueled by cold, low entropy gas streams resulting in a very similar mean assembly redshift of z_{f,ins}~2.5 for the in situ stellar component in all galaxies. The late growth is dominated by accretion of old stars formed in subunits outside the main galaxy (r>r_eff) resulting in an assembly redshift of z_{f,acc}~0.5-1.5 with much larger scatter. We find a positive correlation between the fraction of accreted stars and the final mass of our galaxies. We show that gravitational feedback strongly suppresses late star formation in massive galaxies contributing to the observed galaxy color bimodality. The accretion of stellar material is also responsible for the observed size growth of early-type galaxies. In addition, we find that the dark matter fractions within the stellar half-mass radii continuously increase towards lower redshift from about f_DM~0.05 at z~3 to f_DM~0.1-0.3 at z=0. Furthermore, the logarithmic slope of the total density profile is nearly isothermal at the present-day (gamma'~1.9-2.2). Finally, the input of gravitational heating lowers the central dark matter densities in the galaxies, with the effect being smaller compared to simulations without supernova feedback.Comment: 23 pages, 16 figures, accepted for publication in Ap

The Two Phases of Galaxy Formation

Cosmological simulations of galaxy formation appear to show a two-phase character with a rapid early phase at z>2 during which in-situ stars are formed within the galaxy from infalling cold gas followed by an extended phase since z<3 during which ex-situ stars are primarily accreted. In the latter phase massive systems grow considerably in mass and radius by accretion of smaller satellite stellar systems formed at quite early times (z>3) outside of the virial radius of the forming central galaxy. These tentative conclusions are obtained from high resolution re-simulations of 39 individual galaxies in a full cosmological context with present-day virial halo masses ranging from 7e11 M_sun h^-1 < M_vir < 2.7e13 M_sun h^-1 and central galaxy masses between 4.5e10 M_sun h^-1 < M_* < 3.6e11 M_sun h^-1. The simulations include the effects of a uniform UV background, radiative cooling, star formation and energetic feedback from SNII. The importance of stellar accretion increases with galaxy mass and towards lower redshift. In our simulations lower mass galaxies ($M_* < 9e10 M_sun h^-1) accrete about 60 per cent of their present-day stellar mass. High mass galaxy ($M_* > 1.7e11 M_sun h^-1) assembly is dominated by accretion and merging with about 80 per cent of the stars added by the present-day. In general the simulated galaxies approximately double their mass since z=1. For massive systems this mass growth is not accompanied by significant star formation. The majority of the in-situ created stars is formed at z>2, primarily out of cold gas flows. We recover the observational result of archaeological downsizing, where the most massive galaxies harbor the oldest stars. We find that this is not in contradiction with hierarchical structure formation. Most stars in the massive galaxies are formed early on in smaller structures, the galaxies themselves are assembled late.Comment: 13 pages, 13 figures, accepted for publication in Ap

Assembly of the Red Sequence in Infrared-Selected Galaxy Clusters from the IRAC Shallow Cluster Survey

We present results for the assembly and star formation histories of massive (~L*) red sequence galaxies in 11 spectroscopically confirmed, infrared-selected galaxy clusters at 1.0 < z < 1.5, the precursors to present-day massive clusters with M ~ 10^15 M_sun. Using rest-frame optical photometry, we investigate evolution in the color and scatter of the red sequence galaxy population, comparing with models of possible star formation histories. In contrast to studies of central cluster galaxies at lower redshift (z < 1), these data are clearly inconsistent with the continued evolution of stars formed and assembled primarily at a single, much-earlier time. Specifically, we find that the colors of massive cluster galaxies at z = 1.5 imply that the bulk of star formation occurred at z ~ 3, whereas by z = 1 their colors imply formation at z ~ 2; therefore these galaxies exhibit approximately the same luminosity-weighted stellar age at 1 < z < 1.5. This likely reflects star formation that occurs over an extended period, the effects of significant progenitor bias, or both. Our results generally indicate that massive cluster galaxy populations began forming a significant mass of stars at z >~ 4, contained some red spheroids by z ~ 1.5, and were actively assembling much of their final mass during 1 < z < 2 in the form of younger stars. Qualitatively, the slopes of the cluster color-magnitude relations are consistent with no significant evolution relative to local clusters.Comment: 24 pages, 9 figures, accepted to Ap

Results from the Super Cryogenic Dark Matter Search (SuperCDMS) experiment at Soudan

We report the result of a blinded search for Weakly Interacting Massive Particles (WIMPs) using the majority of the SuperCDMS Soudan dataset. With an exposure of 1690 kg days, a single candidate event is observed, consistent with expected backgrounds. This analysis (combined with previous Ge results) sets an upper limit on the spin-independent WIMP--nucleon cross section of $1.4 \times 10^{-44}$ ($1.0 \times 10^{-44}$) cm$^2$ at 46 GeV/$c^2$. These results set the strongest limits for WIMP--germanium-nucleus interactions for masses $>$12 GeV/$c^2$