Is Smart Growth Fair Growth: Do Urban Growth Boundaries Keep Out Racial Minorities?

Objective: I investigate whether urban growth boundaries (UGBs) contribute to the exclusion of racial minorities and/or have an effect on levels of racial residential segregation. Methods: I study 43 pairs of places throughout the U.S. (each pair is comprised of a place with a UGB and a place without a UGB but is otherwise similar to its partner). I use Census data and a residential segregation index from 1990 and 2000 for blacks, Hispanics, and whites. I compare changes in the number of in-migrating blacks and Hispanics to these pairs of cities as well as the amount of population growth in them, and also examine city pairs’ levels of residential segregation. Results: I find that UGBs do not reduce blacks’ or Hispanics’ in-migration or population size. Also, the results show that UGBs are not a cause of Hispanic-white segregation, but might contribute to a small increase in black-white segregation, though most places in this study have dissimilarity indexes in the low range. Conclusion: My results should reduce concerns that UGBs are a barrier to racial minorities

Is Smart Growth Fair Growth: Do Urban Growth Boundaries Keep out Racial Minorities?

As many American metropolitan areas spread outward, urban sociologists are interested in the effects of sprawl and in efforts to limit suburban expansion. To rein in urban sprawl, land use measures known as “smart growth initiatives” are gaining popularity. Urban growth boundaries are the particular type of initiative examined in this research. An urban growth boundary delineates where development is encouraged and where it is discouraged or prohibited. My first research question is whether urban growth boundaries contribute to the exclusion of racial minorities. I also explore whether urban growth boundaries affect residential segregation. I study 86 places throughout the U.S.: 43 matched pairs of places (with each pair comprised of a place with an urban growth boundary and a place without a boundary but otherwise similar to its partner). I also consider Atlanta, with no constraints on growth, and Portland, Oregon, a smart growth leader. Census data and residential segregation indexes from 1990 and 2000 for whites, blacks, and Hispanics are analyzed. The analysis consists of comparing change in the number of blacks and Hispanics due to in-migration and population growth in places with and without urban growth boundaries, and examining levels of segregation in them. I find that urban growth boundaries do not reduce blacks’ or Hispanics’ in-migration or population size. Also, the preponderance of the results supports the view that urban growth boundaries are not a cause of racial residential segregation

Biphasic calcium phosphate and polymer-coated bovine bone matrix for sinus grafting in an animal model

Autogenous bone grafting requires a donor site and may lose substantial volume during remodeling. Several bone replacement materials (BRMs) are under development to overcome these limitations, especially for indications for minimally intervention surgeries. The objective of our study was to assess the potential of an equine collagen cone reinforced with biphasic calcium phosphate (CC-BCP) particles and deproteinized bovine bone matrix (BBM) coated with polylactic acid, and poly-ε-caprolactone copolymer (BBM-PCC) and then to compare the outcomes with a deproteinized BBM and an equine CC without a filler in a sheep sinus grafting model in the Elleven female sheep were selected. Two experimental sites on each side of the animals were prepared using an extraoral approach for maxillary sinus wall. The four treatments were performed in each animal through a standardized 10-mm access window. While the BBM access was covered with a collagen membrane, all other sites were closed with an equine collagen membrane. All animals were euthanized after 16 weeks. New bone (NB), residual graft particles, and connective tissue were measured in undemineralized resin-embedded sections. As a result, one sheep did not survive the surgery. All sites in the remaining 10 sheep healed uneventfully. All CC and BBM-PCC grafts resorbed and failed to augment the sinuses. BBM and CC-BCP, in contrast, showed some histologic evidence of NB and surgical site augmentation. The NB fraction in the latter two groups accounted for 10 ± 9 and 4 ± 5%, respectively (p > 0.05). In conclusion, BBM-PCC and collagen cone performed poorly for sinus floor augmentation, while deproteinised BBM and reinforced collagen cone demonstrated comparable outcomes

Depth of post-depositional remanence acquisition in deep-sea sediments: a case study of the Brunhes-Matuyama reversal and oxygen isotopic Stage 19.1

Although post-depositional remanent magnetization (PDRM) in deep-sea sediments appears to be acquired during the earliest stages of sediment compaction, the natural variability of the PDRM lock-in depth in deep-sea sediments is poorly understood and as yet unquantified. Here we consider variations in the relative stratigraphic positions of oxygen isotopic interglacial Stage 19.1 and the Brunhes-Matuyama (B/M) Chronozone reversal for eight deep-sea sediment cores. Results from a similar study of the displacement between a widespread microtektite layer and the B/M boundary are also included [1]. The PDRM lock-in depth and the temporal relationships between the B/M and Stage 19.1 datums can be determined from the offsets between the paleomagnetic and the isotopic (and microtektite) stratigraphies. For cores with sedimentation rates greater than 1 cm kyr−1, the depth offset between the paleomagnetic and isotopic datums is a linear function of sedimentation rate. A simple model (r2 = 0.77) demonstrates that (1) PDRM acquisition occurs ∼ 16 cm below the sediment surface, and (2) the B/M reversal occurs 6 kyr (±2 kyr) after the Stage 19.1 datum, and the Stage 19.1 datum occurs 9 kyr (±3 kyr) after the deposition of the Australasian microtektite strewnfield. This example argues against simple geophysical models linking geomagnetic field reversals to climate change or impact events. The B/M boundary is anomalously deep (30–50 cm) in very low accumulation rate sediments ( < 1 cm kyr−1) and this may reflect the unusual physical properties of these sediments. A review of the geotechnical literature suggests that very low accumulation rate sediments have sufficient time to develop enhanced interparticle rigidity (structural strength) which inhibits early compaction and, hence, PDRM acquisition

Evidence for a mid-Pleistocene change of ice-drift pattern in the Nordic seas

Sediment proxy records from a continuous, 1.5 million year long deep-sea sediment core from a site in the western Norwegian Sea were used to obtain new insights into the nature of palaeoceanographic change in the northern North Atlantic (Nordic seas) during the climatic shift of the Mid-Pleistocene Revolution (MPR). Red-green sediment colour and magnetic susceptibility records both reveal significant differences in their mean values when comparing the intervals older than 700 000 yr (700 ka) with those from the past 500 kyr. The timing and duration of these changes indicates that the MPR in the Nordic seas is characterised by a gradual transition lasting about 200 kyr. Together with further sedimentological evidence this suggests that the mid-Pleistocene climate shift was accompanied by a general change in ice-drift pattern. It is further proposed that prior to the onset of the major late Pleistocene glaciations in the Northern Hemisphere a significant proportion of the ice in the eastern Nordic seas originated from a southern provenance, whereas later it dominantly came from the surrounding landmasses

Astronomic timescale for the Pliocene Atlantic δ18O and dust flux records of Ocean Drilling Program site 659

High-resolution benthic oxygen isotope and dust flux records from Ocean Drilling Program site 659 have been analyzed to extend the astronomically calibrated isotope timescale for the Atlantic from 2.85 Ma back to 5 Ma. Spectral analysis of the δ18O record indicates that the 41-kyr period of Earth's orbital obliquity dominates the Pliocene record. This is shown to be true regardless of fundamental changes in the Earth's climate during the Pliocene. However, the cycles of Sahelian aridity fluctuations indicate a shift in spectral character near 3 Ma. From the early Pliocene to 3 Ma, the periodicities were dominantly precessional (19 and 23 kyr) and remained strong until 1.5 Ma. Subsequent to 3 Ma, the variance at the obliquity period (41 kyr) increased. The timescale tuned to precession suggests that the Pliocene was longer than previously estimated by more than 0.5 m.y

A stratigraphically controlled multi-proxy chronostratigraphy for the Eastern Mediterranean

An Accelerator Mass Spectrometry (AMS) 14C dated multiparameter event stratigraphy is developed for the Aegean Sea on the basis of highly resolved (centimeter to subcentimeter) multiproxy data collected from four late glacial to Holocene sediment cores. We quantify the degree of proportionality and synchroneity of sediment accumulation in these cores and use this framework to optimize the confidence levels in regional marine, radiocarbon-based chronostratigraphies. The applicability of the framework to published, lower-resolution records from the Aegean Sea is assessed. Next this is extended into the wider eastern Mediterranean, using new and previously published high-resolution data from the northern Levantine and Adriatic cores. We determine that the magnitude of uncertainties in the intercore comparison of AMS 14C datings based on planktonic foraminifera in the eastern Mediterranean is of the order of ±240 years (2 SE). These uncertainties are attributed to synsedimentary and postsedimentary processes that affect the materials dated. This study also offers a background age control that allows for vital refinements to radiocarbon-based chronostratigraphy in the eastern Mediterranean, with the potential for similar frameworks to be developed for any other well-studied region