Income Diversity Within Neighborhoods and Very Low-Income Families

The past decades have witnessed increasing concern over the family ills engendered by neighborhoods inhabited overwhelmingly by families with limited resources. This study focuses on a different sort of residential context—neighborhoods with substantial income mixing—and the extent to which very low-income (VLI) families—those earning less than 50 percent of the area median income (AMI)—live in them. The study’s primary units of analysis are the 100 largest metropolitan areas in the United States, according to the 2000 Census, and the secondary units of analysis are census tracts. The study specifies six mutually exclusive income groups based on the ratios relative to AMI, as defined by the U.S. Department of Housing and Urban Development. It also specifies four groups of neighborhoods according to their diversity of the six income groups, as measured by an entropy index. The descriptive results show that in 2000 (1) most neighborhoods had high diversity, although a decline is apparent in the overall income diversity of neighborhoods and in the share comprising high-diversity neighborhoods; (2) no neighborhoods with median incomes of less than 50 percent of AMI had high diversity; (3) 19 percent of all high-diversity neighborhoods (on average) consist of VLI families and 65 percent of all VLI families live in high-diversity neighborhoods, although both percentages have declined since 1970; (4) 5 percent of VLI families live in neighborhoods with median incomes of less than 50 percent of AMI, twice the percentage of 1970 but lower than in 1990; and (5) exposure of VLI families to other VLI families and moderate-income groups has steadily fallen since 1970 and concomitantly increased for families that have very high incomes (VHIs); indeed, the exposure to VHI families is approximately the same as exposure to other VLI families. This article addresses the mixed implications of these trends for the potential socioeconomic mobility of VLI families. This research was presented at Wayne State University\u27s 2010 Sociology Student Research & Awards Day. Presentation slides are included as supplemental materials. This research was supported by a grant from the U.S. Department of Housing and Urban Development, Office of Policy Development and Research. The opinions expressed in this article are those of the authors and do not necessarily reflect those of the Department

Upper Jurassic-Lower Cretaceous basinal strata along the Cordilleran Margin: Implications for the accretionary history of the Alexander-Wrangellia-Peninsular Terrane

Upper Jurassic and Lower Cretaceous basinal strata are preserved in a discontinuous belt along the inboard margin of the Alexander-Wrangellia-Peninsular terrane (AWP) in Alaska and western Canada, on the outboard margin of terranes in the Canadian Cordillera accreted to North America prior to Late Jurassic time, and along the Cordilleran margin from southern Oregon to southern California. Nearly all of the basinal assemblages contain turbiditic strata deposited between Oxfordian and Albian time. Arc-type volcanic rocks and abundant volcanic detritus in many of the assemblages suggest deposition within or adjacent to a coeval arc complex. On the basis of the general similarities between the basinal sequences, we propose that they record involvement of the AWP in the Late Jurassic-Early Cretaceous evolution of the Cordilleran margin. A geologically reasonable scenario for the accretion of the AWP includes (1) Middle Jurassic accretion to the Cordilleran margin, in particular the Stikine and Yukon-Tanana terranes, in a dextral transpressional regime, (2) Late Jurassic-Early Cretaceous overall northward translation of the AWP and evolution of a series of transtensional basins within a complex dextral strike-slip system along the Cordilleran margin, and (3) mid-Cretaceous structural imbrication of the AWP and inboard terranes that either terminated or resulted in a change in the character of deposition in the marginal basins. Mid-Cretaceous deformation along the inboard margin of the AWP was broadly synchronous with contractional deformation throughout the Cordillera and most likely due to changes in subduction zone parameters along the Cordilleran margin, outboard of the AWP, rather than collision of the AWP

Ordovician-Silurian volcanogenic massive sulfide deposits on the southern Prince of Wales Island and the barrier islands, southeastern Alaska

Several pyritic massive sulfide deposits have been recognized in an Ordovician-Silurian volcano-plutonic complex in the southern Prince of Wales Island region (Fig. 1). These deposits have been studied as part of a U.S. Geological Survey-California Institute of Technology investigation into the geologic and mineralization history of southern Prince of Wales Island (south of 55° North Latitude; Fig. 1). This report describes the geologic setting of the deposits and presents preliminary chemical analyses of the mineralization

Magnesium-dependent Association and Folding of Oligonucleosomes Reconstituted with Ubiquitinated H2A

The MgCl2-induced folding of defined 12-mer nucleosomal arrays, in which ubiquitinated histone H2A (uH2A) replaced H2A, was analyzed by quantitative agarose gel electrophoresis and analytical centrifugation. Both types of analysis showed that uH2A arrays attained a degree of compaction similar to that of control arrays in 2 mM MgCl2. These results indicate that attachment of ubiquitin to H2A has little effect on the ability of nucleosomal arrays to form higher order folded structures in the ionic conditions tested. In contrast, uH2A arrays were found to oligomerize at lower MgCl2 concentrations than control nucleosomal arrays, suggesting that histone ubiquitination may play a role in nucleosomal fiber association

Analysis and visualization of chromosomal abnormalities in SNP data with SNPscan

BACKGROUND: A variety of diseases are caused by chromosomal abnormalities such as aneuploidies (having an abnormal number of chromosomes), microdeletions, microduplications, and uniparental disomy. High density single nucleotide polymorphism (SNP) microarrays provide information on chromosomal copy number changes, as well as genotype (heterozygosity and homozygosity). SNP array studies generate multiple types of data for each SNP site, some with more than 100,000 SNPs represented on each array. The identification of different classes of anomalies within SNP data has been challenging. RESULTS: We have developed SNPscan, a web-accessible tool to analyze and visualize high density SNP data. It enables researchers (1) to visually and quantitatively assess the quality of user-generated SNP data relative to a benchmark data set derived from a control population, (2) to display SNP intensity and allelic call data in order to detect chromosomal copy number anomalies (duplications and deletions), (3) to display uniparental isodisomy based on loss of heterozygosity (LOH) across genomic regions, (4) to compare paired samples (e.g. tumor and normal), and (5) to generate a file type for viewing SNP data in the University of California, Santa Cruz (UCSC) Human Genome Browser. SNPscan accepts data exported from Affymetrix Copy Number Analysis Tool as its input. We validated SNPscan using data generated from patients with known deletions, duplications, and uniparental disomy. We also inspected previously generated SNP data from 90 apparently normal individuals from the Centre d'Étude du Polymorphisme Humain (CEPH) collection, and identified three cases of uniparental isodisomy, four females having an apparently mosaic X chromosome, two mislabelled SNP data sets, and one microdeletion on chromosome 2 with mosaicism from an apparently normal female. These previously unrecognized abnormalities were all detected using SNPscan. The microdeletion was independently confirmed by fluorescence in situ hybridization, and a region of homozygosity in a UPD case was confirmed by sequencing of genomic DNA. CONCLUSION: SNPscan is useful to identify chromosomal abnormalities based on SNP intensity (such as chromosomal copy number changes) and heterozygosity data (including regions of LOH and some cases of UPD). The program and source code are available at the SNPscan website