Income segregation,income inequality and mortality in North American metropolitan areas

There is a large sociological literature on racial- class-, and economically- based segregation in the United States and there is some evidence that residential segregation by income may have deleterious health consequences for residents of large U.S. cities. The health consequences of segregation in Canadian metropolitan areas, however, remain unknown and the comparison with the U.S. is always compelling. In this paper, we investigate the hypothesis that residential segregation by income may be associated with mortality in Canadian and U.S. metropolitan areas. Given the strong relationship between individual level socioeconomic status and health, it follows that metropolitan areas which isolate individuals economically could produce conditions that severely limit the life chances and therefore the health chances of the most vulnerable. To investigate the association between residential segregation by income and population health, we examined the relationship between working-age mortality and Jargowsky's (1996) neighbourhood sorting index (NSI) for a large group of North American metropolitan areas. We found a relationship between increased segregation and increased mortality for U.S. metropolitan areas but no such relationship for Canadian metropolitan areas. We also determined that income segregation could not be considered in isolation from income inequality – that, in effect, income inequality provides the propensity for meaningful segregation to occur. We further demonstrated the importance of considering both income inequality and income segregation together, especially when the analysis is intended to compare metropolitan areas. We conclude with a discussion of the need for an improved measure of segregation to better reflect the theoretical arguments for the relationship between concentration of poverty and affluence and population health.     

Nutrient changes in the Mississippi River and system responses on the adjacent continental shelf

The Mississippi River system ranks among the world's top 10 rivers in freshwater and sediment inputs to the coastal ocean. The river contributes 90% of the freshwater loading to the Gulf of Mexico, and terminates amidst one of the United States' most productive fisheries regions and the location of the largest zone of hypoxia, in the western Atlantic Ocean. Significant increases in riverine nutrient concentrations and loadings of nitrate and phosphorus and decreases in silicate have occurred this century, and have accelerated since 1950. Consequently, major alterations have occurred in the probable nutrient limitation and overall stoichiometric nutrient balance in the adjacent continental shelf system. Changes in the nutrient balances and reduction in riverine silica loading to, the continental shelf appear to have led to phytoplankton species shifts offshore and to an increase in primary production. The phytoplankton community response, as indicated by long-term changes in biological uptake of silicate and accumulation of biologically bound silica in sediments, has shown how the system has responded to changes in riverine nutrient loadings. Indeed, the accumulation of biologically bound silica in sediments beneath the Mississippi River plume increased during the past two decades, presumably in response to, increased nitrogen loading. The duration, size, and severity of hypoxia has probably increased as a consequence of the increased primary production. Management alternatives directed at water pollution issues within the Mississippi River watershed may have unintended and contrasting impacts on the coastal waters of the northern Gulf of Mexico.     

Genetic variation in the soft-shelled Clam,Mya arenaria

Genetic variability for two popula-tions, Maine and Maryland, of the soft-shelled clam,Mya arenaria, was estimated from electrophoretic anal-yses of whole clams. Polymorphism (12.5% in Maine and 16.7% in Maryland clams) and heterozygosity per individ-ual (4.6% in Maine and 6.6% in Maryland) were low for the two populations based on 40 loci in Maine and 42 loci in MarylandMya.     

The Raman spectra of several orthorhombic calcium oxide perovskites

We have obtained Raman spectra for a number of orthorhombic perovskites CaBO₃, where B=Ti, Ge, Zr or Sn. The room temperature Raman spectrum of CaTiO₃ was compared with cubic SrTiO₃ to assign first- and second-order features. Partially polarized micro-Raman spectra were obtained for CaTiO₃ perovskite. The CaBO₃ perovskites showed a sequence of increasing complexity in their Raman spectra with increasing degree of orthorhombic distortion from the ideal cubic structure. The spectral changes cannot easily be correlated with changes in chemistry or structure of the perovskite. High temperature micro-Raman spectra for CaGeO₃ perovskite were obtained by laser-heating a 15 μm sample. None of the low frequency Raman modes were soft, but showed only normal anharmonicity up to approximately 700 K.     

The prediction of mineral solubilities in natural waters: The Na-K-Mg-Ca-H-Cl-SO4-OH-HCO3-CO3-CO2-H2O system to high ionic strengths at 25°C

The mineral solubility model of Harvie and Weare (1980) is extended to the eight component system, Na-K-Mg-Ca-H-Cl-SO₄-OH-HCO₃-CO₃-CO₂-H₂O at 25°C to high concentrations. The model is based on the semi-empirical equations of Pitzer (1973) and co-workers for the thermodynamics of aqueous electrolyte solutions. The model is parameterized using many of the available isopiestic, electromotive force, and solubility data available for many of the subsystems. The predictive abilities of the model are demonstrated by comparison to experimental data in systems more complex than those used in parameterization. The essential features of a chemical model for aqueous electrolyte solutions and the relationship between pH and the equilibrium properties of a solution are discussed.     

Influence of mesoscale winds on the turbulent structure of the urban boundary layer over St. Louis

Two fair weather afternoons have been examined, where the urban boundary layer over St. Louis, though exhibiting similar thermal characteristics, had a markedly different kinematic structure. The turbulent nature of the boundary layer was examined through analysis of double theodolite wind profiles at an urban and at a rural site on each day. On 14 July 1975, the winds increased with height above the inversion at both sites and on the following day, the winds decreased above the boundary layer in the same region. While the mean wind speed in the lowest 0.8 km agl was similar on both days, the turbulence characteristics of the urban boundary-layer winds were distinctly different on these two afternoons. This was evidenced by the variance of the wind and is in agreement with simultaneous aircraft measurements reported by Hildebrand and Ackerman (1984). A similar difference in turbulence was not found over the rural site. It is suggested that the enhanced turbulence at the urban site on 14 July is likely associated with the wind profile immediately above the boundary layer, where the downward flux of high momentum air from above the inversion may have resulted in stronger mechanical mixing within the boundary layer.     

The influence of carbon on trace element partitioning behavior

Carbon has been proposed as a potential light element in planetary cores, included in models of planetary core formation, and found in meteoritic samples and minerals. To better understand the effect of C on the partitioning behavior of elements, solid/liquid partition coefficients (D = (solid metal)/(liquid metal)) were determined for 17 elements (As, Au, Co, Cr, Cu, Ga, Ge, Ir, Ni, Os, Pd, Pt, Re, Ru, Sb, Sn, and W) over a range of C contents in the Fe-Ni-C system at 1 atm. The partition coefficients for the majority of the elements increased as the C content of the liquid increased, an effect analogous to that of S for many of the elements. In contrast, three of the elements, Cr, Re, and W, were found to have anthracophile (C-loving) preferences, partitioning more strongly into the metallic liquid as the C content increased, resulting in decreases to their partition coefficients. For half of the elements examined, the prediction that partitioning in the Fe-Ni-S and Fe-Ni-C systems could be parameterized using a single set of variables was not supported. The effects of S and C on elemental partitioning behavior can be quite different; consequently, the presence of different non-metals can result in different fractionation patterns, and that uniqueness offers the opportunity to gain insight into the evolution of planetary bodies.