Integration and the Achievement Gap: Innovation in Dallas, Texas

Educatio

The APM Galaxy Survey:- V. Catalogues of Galaxy Clusters

We describe the construction of catalogues of galaxy clusters from the APM Galaxy survey using an automated algorithm based on Abell-like selection criteria. We investigate the effects of varying several parameters in our selection algorithm, including the magnitude range, and radius from the cluster centre used to estimate the cluster richnesses. We quantify the accuracy of the photometric distance estimates by comparing with measured redshifts, and we investigate the stability and completeness of the resulting catalogues. We find that the angular correlation functions for different cluster catalogues are in good agreement with one another, and are also consistent with the observed amplitude of the spatial correlation function of rich clusters.Comment: 14 pages, PostScript, including 15 figures, submitted to MNRAS. Also available from ftp://ftp-astro.physics.ox.ac.uk/pub/gbd/papers/apm5.ps.g

The richness dependence of galaxy cluster correlations: Results from a redshift survey of rich APM clusters

We analyse the spatial clustering properties of a new catalogue of very rich galaxy clusters selected from the APM Galaxy Survey. These clusters are of comparable richness and space density to Abell Richness Class $\geq 1$ clusters, but selected using an objective algorithm from a catalogue demonstrably free of artificial inhomogeneities. Evaluation of the two-point correlation function $\xi_{cc}(r)$ for the full sample and for richer subsamples reveals that the correlation amplitude is consistent with that measured for lower richness APM clusters and X-ray selected clusters. We apply a maxmimum likelihood estimator to find the best fitting slope and amplitude of a power law fit to $\xi_{cc}(r)$, and to estimate the correlation length $r_{0}$ (the value of $r$ at which $\xi_{cc}(r)$ is equal to unity). For clusters with a mean space density of 1.6\times 10^{-6}\hmpccc (equivalent to the space density of Abell Richness $\geq 2$ clusters), we find r_{0}=21.3^{+11.1}_{-9.3} \hmpc (95% confidence limits). This is consistent with the weak richness dependence of $\xi_{cc}(r)$ expected in Gaussian models of structure formation. In particular, the amplitude of $\xi_{cc}(r)$ at all richnesses matches that of $\xi_{cc}(r)$ for clusters selected in N-Body simulations of a low density Cold Dark Matter model.Comment: MNRAS submitted, 9 pages, LaTeX (mn), 7 figures. Also available at http://www-astronomy.mps.ohio-state.edu/~racc

Density and Velocity Fields from the PSCz Survey

We present the results for the predicted density and peculiar velocity fields and the dipole from the PSCz survey of 15,000 IRAS galaxies over 84% of the sky. We find a significant component to the dipole arising between 6000 and 15,000 km/s, but no significant component from greater distances. The misalignment with the CMB is 20 degrees. The most remarkable feature of the PSCz model velocity field is a coherent large-scale flow along the baseline connecting Perseus-Pisces, the Local Supercluster, Great Attractor and the Shapley Concentration. We have measured the parameter beta using the amplitude of the dipole, bulk flow and point by point comparisons between the individual velocities of galaxies in the MarkIII and SFI datasets, and the large-scale clustering distortion in redshift space.All our results are consistent with beta = 0.6 +- 0.1.Comment: 8 pages, 8 figures. To appear in 'Towards an Understanding of Cosmic Flows', Victoria, July 1999, eds Courteau,S., Strauss,M., Willick,J. PAS

Understanding contributors to racial and ethnic inequities in COVID-19 incidence and mortality rates

BACKGROUND: Racial inequities in Coronavirus 2019 (COVID-19) have been reported over the course of the pandemic, with Black, Hispanic/Latinx, and Native American individuals suffering higher case rates and more fatalities than their White counterparts. METHODS: We used a unique statewide dataset of confirmed COVID-19 cases across Missouri, linked with historical statewide hospital data. We examined differences by race and ethnicity in raw population-based case and mortality rates. We used patient-level regression analyses to calculate the odds of mortality based on race and ethnicity, controlling for comorbidities and other risk factors. RESULTS: As of September 10, 2020 there were 73,635 confirmed COVID-19 cases in the State of Missouri. Among the 64,526 case records (87.7% of all cases) that merged with prior demographic and health care utilization data, 12,946 (20.1%) were Non-Hispanic (NH) Black, 44,550 (69.0%) were NH White, 3,822 (5.9%) were NH Other/Unknown race, and 3,208 (5.0%) were Hispanic. Raw cumulative case rates for NH Black individuals were 1,713 per 100,000 population, compared with 2,095 for NH Other/Unknown, 903 for NH White, and 1,218 for Hispanic. Cumulative COVID-19-related death rates for NH Black individuals were 58.3 per 100,000 population, compared with 38.9 for NH Other/Unknown, 19.4 for NH White, and 14.8 for Hispanic. In a model that included insurance source, history of a social determinant billing code in the patient\u27s claims, census block travel change, population density, Area Deprivation Index, and clinical comorbidities, NH Black race (OR 1.75, 1.51-2.04, p\u3c0.001) and NH Other/Unknown race (OR 1.83, 1.36-2.46, p\u3c0.001) remained strongly associated with mortality. CONCLUSIONS: In Missouri, COVID-19 case rates and mortality rates were markedly higher among NH Black and NH Other/Unknown race than among NH White residents, even after accounting for social and clinical risk, population density, and travel patterns during COVID-19