Browsing by Author "Johnson, William"

Now showing 1 - 3 of 3
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    1993 Study of Visitor Experiences and Benefits at Itasca State Park: Final Report
    (1997) Nickerson, Ron; Anderson, Dorothy H.; Perger, Barbara; Pierskalla, Chad; Johnson, William
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    Associations between birth weight/gestational age and social/cognitive functioning across development: Do differences endure?
    (2018-08) Johnson, William
    This study uses data from the Minnesota Longitudinal Study of Risk and Adaptation (N = 267) to test whether birth weight and gestational age prospectively predict cognitive functioning and social competence throughout childhood, adolescence and early adulthood. Using multiple developmentally appropriate indicators of cognitive and social functioning, structural model comparisons test whether Enduring Effects or Revisionist Effects models of development better explain the associations between birth weight/gestational age and cognitive/social functioning. Of the four comparisons (birth weight predicting cognitive functioning, gestational age predicting cognitive functioning, birth weight predicting social competence, gestational age predicting social competence), only birth weight and cognitive functioning were consistently associated across development. The Revisionist Effects model best explained these relations, such that direct associations did not persist over time. Instead, birth weight had direct associations with cognitive functioning in early childhood that were carried forward through stability in cognitive outcomes through early adulthood. These findings are discussed in context of other tests of the Enduring Effects vs. Revisionist Effects models, developmental theory, and intervention application.
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    Electrochemical Assisted Phosphorus Precipitation of the Liquid Fraction of Dairy Manure in Microbial Electrolysis Cells: A Look into Phosphorus Removal
    (2015-09-04) Johnson, William
    A cost and energy efficient method of liquid dairy manure solution treatment was investigated with the use of Microbial Electrolysis Chamber technology. The electrolysis chamber would precipitate phosphorus out of solution with the use of an applied voltage and the present microbes in the manure. It was seen that higher voltages around 1.0 V would remove roughly 35% of the total phosphorus out of solution. Reactors with a smaller induced voltage did not follow a steady trend and instead all remove between 8-16% of the total phosphorus in solution. This MEC treatment method does not remove as much as MFC and other removal technologies, but has proven to be very cost efficient. The economic feasibility of this experiment will allow it to be studied more in-depth and on a larger scale.