Evaluation of Fish and Macroinvertebrate Indices of Biotic Integrity in the Bioassessment of the Illinois River Basin

Evaluating performances of the fish and invertebrate Indices of Biotic Integrity (IBIs) for a region is important to maintain rigorous assessment of the environmental quality of streams, especially with increasing urbanization. Timing of the assessment is considered important, with the critical season (low flow, high temperature) preferred, but the primary season (spring– summer) may be as efficient. I assisted with the collection and analysis of fish and macroinvertebrates using methods developed by the United States Environmental Protection Agency’s (USEPA) Rapid Bioassessment Protocols (RBPs) and the Arkansas Department of Environmental Quality (ADEQ), along with obtaining habitat and chemical assessments during primary and critical periods during 2007-2009 at ten sites in the Illinois River Basin up and downstream of two wastewater treatment plants (WWTPs). My objectives were to (1) compare fish and macroinvertebrate IBIs for use in the Illinois River Basin; (2) investigate correlations with each IBI and its metrics to nutrient, habitat, and watershed variables; (3) compare the efficacy of the IBIs during both critical and primary seasons; and (4) determine how two WWTPs in the area affect downstream water quality into Oklahoma. The two IBIs were strongly correlated with each other (Rs of 0.59); however, macroinvertebrates outperformed the fish. More regionally specific fish metrics should allow for better performing fish IBIs, but adequate performance was found. Combining the seasons’ data allowed for a more comprehensive and statistically significant assessment; however, the primary season evaluated each site comparably to the combined data and generally outperformed the critical seasons. The combined and primary seasons’ macroinvertebrate IBIs revealed sites with lowered environmental quality below the WWTPs but with quick returns to reference conditions. My results indicate that it may be possible to test IBIs during only the primary seasons to get efficient water quality and site comparison assessments

Representation by Integrating Reproducing Kernels

Based on direct integrals, a framework allowing to integrate a parametrised family of reproducing kernels with respect to some measure on the parameter space is developed. By pointwise integration, one obtains again a reproducing kernel whose corresponding Hilbert space is given as the image of the direct integral of the individual Hilbert spaces under the summation operator. This generalises the well-known results for finite sums of reproducing kernels; however, many more special cases are subsumed under this approach: so-called Mercer kernels obtained through series expansions; kernels generated by integral transforms; mixtures of positive definite functions; and in particular scale-mixtures of radial basis functions. This opens new vistas into known results, e.g. generalising the Kramer sampling theorem; it also offers interesting connections between measurements and integral transforms, e.g. allowing to apply the representer theorem in certain inverse problems, or bounding the pointwise error in the image domain when observing the pre-image under an integral transform

The High Speed Water Tunnel three-component balance

An experimental program was initiated in the High Speed Water Tunnel to measure force coefficients for hydrofoils under cavitating conditions. This program necessitated either a new force balance or a major modification of the existing one. Various balance configurations and pressure seal designs which were considered are described. A balance modification design was selected which consists of an appendage bolted between the existing balance and the water tunnel working section. This appendage alters the basic geometry of the force balance so that the model is now mounted on a parallelogram linkage instead of on a simple pivoted lever. The addition of the parallelogram force table suspension to the old balance renders the modified balance unresponsive to moments which in the old balance, interacted with forces and resulted in errors in the force readings. This modification which is described in detail was accomplished and resulted in a successful force balance capable of accurate measurement of forces on cavitating and noncavitating hydrofoils; and, in fact, it is expected to replace the old force balance for all force measurement work in the High Speed Water Tunnel. The cost and construction time for the balance modification were considerably less than would have been required for an entirely new force balance of comparable accuracy and sensitivity

Cohort Changes in the Transition from School to Work: What Changed and What Consequences Did it have for Wages?

This study examines the changes in the school-to-work transition in the United States over the latter part of the twentieth century and their consequences for the wages of young adults. In particular, we document the various types of work and schooling experiences acquired by youth who came to adulthood in the U.S. during the late 1960s, 1970s, and through the 1980s. We pay particular attention to how the differences across cohorts in these transitions vary by gender and race/ethnicity and how these differences affected their subsequent wage attainment. Evidence is evaluated using data from National Longitudinal Surveys of Young Women, Young Men, and Youth 1979. In general, we find that indicators of educational attainment, working while in school and non-school related work increased across cohorts for almost all racial/ethnic and gender groups. This was especially true for young women. Furthermore, various indicators of personal and family backgrounds changed in ways consistent with an improvement across cohorts in the preparation of young men and women for their attainment of schooling and work experience and their success in the labor market. The one exception to this general picture of improvement across cohorts was Hispanic men, who experienced a notable decline in educational attainment, the acquisition of full time work early in their adult lives and in a variety of personal and family background characteristics. With respect to hourly wage rates, we find that wages over the ages 16 through 27 declined across cohorts. However, the rate of growth of wages with age, particularly over adult ages, increased across cohorts for all racial/ethnic and gender groups, except black and Hispanic men. To assess the relative importance that changes in the school, work, military and other experiences had on wages across generations, we employ the decomposition proposed by Juhn, Murphy and Pierce (1993) to decompose the across-cohort wage changes in observable determinants, in their associated prices and in unobservable determinants, using a standard regression specification for the determinants of life cycle wages. We find that the dominant factor explaining the declines in wages across cohorts is attributable to changes in the prices of observable characteristics and to changes in unobservable determinants. At constant skill prices, changes in the skill composition across youth cohorts would have increased their wages, most especially for Hispanic women, followed by black women, white women, black men, and then white men. In striking contrast, Hispanic males’ wages would still have declined across cohorts purely accounting for compositional changes. We interpret this result as coming from the changing skill composition of immigrants. Our results also highlight the need for accounting for the endogeneity and selectivity of early skill acquisition.