Flowfield measurements in a model scramjet combustion using laser-induced iodine fluorescence

Preliminary designs were completed for an iodine mixing chamber and the optical setup to be used with a modified wind tunnel in obtaining accurate, spatially resolved measurements of variables in the flowfield of a model nonreacting scramjet combustor. Schematics of the iodine-seeded wind tunnel and a sketch of the charcoal filter for removing the iodine are included along with a cutaway section of the laboratory

Comments on Estimating Population Rate of Increase from Age Frequency Data

Although many papers have described assumptions and calculations of r from different kinds of data, none has compared estimates of r for the same real data set under different assumptions. We used the age distributions of gray foxes collected during six trapping seasons to estimate and compare r and lₓ series derived under different assumptions. Because trapped foxes are killed, they are believed by some to represent death history data. We found this treatment underestimates mortality so overestimates survivorship and leads to erroneous conclusions about the population. Use of a projection matrix allowed prediction of population size and thus allowed us to predict observed rate of increase. Use of projection matrices also resulted in the most conservative estimated of r

Cartographic Trend Analysis of Furbearer Harvest Distributions in Arkansas

Average by-county fur harvest for the last nine harvest seasons (1977-1985) was used as data points to be interpolated using nearest neighbor algorithms in computer-assisted trend analyses. COMPLOT maps were produced which represented a surface of harvest densities drawn over a map of Arkansas. Twelve furbearer species are examined, and topographic features of harvest density for each are interpreted in terms of ecology and/or buyer distribution. The trend surface technique removed some of the error inherent to harvest records, and produced an aesthetic graphical display of the information that was more easily interpreted and explained than other methods of analysis usually allow

Mensural Discrimination of the Skulls of Arkansas Peromyscus

Twelve parameters were measured on skulls of four species of Peromyscus from Arkansas. Univariate statistical tests, multivariate analyses of variance, and principal axis factor analyses were performed on the data set and/or subsets in a search for species-level discriminating characters. Total length of skull was found to discriminate between skulls of P. maniculatis, P. leucopus, and a combined group of P. attwateri and P. gossypinus. Furthermore, the ratio of interorbital width and length of nasal bone was found to adequately discriminate between skulls of P. attwateri and P. gossypinus

Dental Pathology in Selected Carnivores from Arkansas

The occurrence and kinds of dental pathology in wild carnivore populations in Arkansas were investigated through examination of 1295 skulls of bobcat (Felis rufus), river otter (Lutra canadensis), gray fox (Urocyon cinereoargenteus), coyote (Canis latrans), and raccoon (Procyon lotor). Pulpitis or abscesses in broken or otherwise exposed teeth were noted in all species, but bobcats had the fewest exposures while otter and gray foxhad the most. Osteomyelitis occurred in all species except the bobcat. Caries were noted in the coyote, raccoon, and gray fox. Otter and coyote had alveolar thinning, and coyote had enamel dysplasia and maxillary sinusitis

Barriers and Bridges: An Action Plan for Overcoming Obstacles and Unlocking Opportunities for African American Men in Pittsburgh

Among the region's residents, Pittsburgh's African American men have historically and disproportionately faced unprecedented barriers to economic opportunities. This study, supported by The Heinz Endowments, focuses on structural barriers that contribute to persistent racial disparities in the Pittsburgh region. Structural barriers are obstacles that collectively affect a group disproportionately and perpetuate or maintain stark disparities in outcomes. Structural barriers can be policies, practices, and other norms that favor an advantaged group while systematically disadvantaging a marginalized group. A community touched by racebased structural barriers can be identified by the racial and economic stratification of its residents; Pittsburgh, like many large cities in the United States, fits that description