Doctor of Philosophy

dissertationThe purpose of the present research was to investigate text; comprehension of narrative text;s at varying levels of comprehension and examine how metacomprehension varies as a function of the level of comprehension when making retrospective (posttest) confidence judgments of performance. Using Kintsch's construction-integration theory of text; comprehension, three types of question were developed to probe text;base and situation model levels of text; representation at three levels of difficulty: (a) text;base, literal (easiest), (b) situation model, temporal ordering (low difficulty inferences), and (c) situation model, propositional logic (high difficulty inferences). Differences in percent correct, response time in milliseconds per character, and max amplitude of pupil size confirmed the predicted difficulty of the three question types, except that there was no significant difference in pupil size between the literal and temporal ordering questions. The three types of questions were then used to examine the effect of question difficulty on metacomprehension judgments of confidence, absolute accuracy (calibration accuracy and bias), and relative accuracy (Goodman-Kruskal gamma coefficient or G). Results showed that readers were sensitive to different levels of comprehension and showed different levels of metacomprehension confidence and accuracy depending on the type of question. As predicted, absolute accuracy showed the effects of anchoringand-adjustment when making these judgments across question type. That is, subjects appeared to be anchoring on a moderate estimate of success that corresponded most closely in this study to performance on literal questions and adjusted their confidence for temporal ordering and propositional logic questions. The results related to bias provided support for the hard-easy effect, with propositional logic questions (i.e., hard questions) showing overconfidence and literal questions (i.e., easy questions) showing no significant bias, although bias scores did not discriminate between temporal ordering and propositional logic questions. As predicted, relative accuracy (G) appeared to be stable across question types with no significant differences by question type. As with previous studies, the differences in the results concerning absolute versus relative accuracy suggest that the two types of accuracy are measuring different components of metacomprehension

Dispersion Modeling of Mercury Emissions from Coal-Fired Power Plants at Coshocton and Manchester, Ohio

Author Institution: Department of Civil and Environmental Engineering, University of CincinnatiMercury emissions from coal-fired power plants are estimated to contribute to approximately 46% of the total U. S. anthropogenic mercury emissions and required to be regulated by maximum achievable control technology (MACT) standards. Dispersion modeling of mercury emissions using the AERMOD model and the Industrial Source Complex Short Term (ISCST3) model was conducted for two representative coal-fired power plants at Coshocton and Manchester, Ohio. Atmospheric mercury concentrations, dry mercury deposition rates, and wet mercury deposition rates were predicted in a 5 × 5 km area surrounding the Conesville and JM Stuart coal-fired power plants. In addition, the analysis results of meteorological parameters showed that wet mercury deposition is dependent on precipitation, but dry mercury deposition is influenced by various meteorological factors

Direction Detector on an Excitable Field: Field Computation with Coincidence Detection

Living organisms process information without any central control unit and without any ruling clock. We have been studying a novel computational strategy that uses a geometrically arranged excitable field, i.e., "field computation." As an extension of this research, in the present article we report the construction of a "direction detector" on an excitable field. Using a numerical simulation, we show that the direction of a input source signal can be detected by applying the characteristic as a "coincidence detector" embedded on an excitable field. In addition, we show that this direction detection actually works in an experiment using an excitable chemical system. These results are discussed in relation to the future development of "field computation."Comment: 6 pages, 3 figure

Noise-assisted spike propagation in myelinated neurons

We consider noise-assisted spike propagation in myelinated axons within a multi-compartment stochastic Hodgkin-Huxley model. The noise originates from a finite number of ion channels in each node of Ranvier. For the subthreshold internodal electric coupling, we show that (i) intrinsic noise removes the sharply defined threshold for spike propagation from node to node, and (ii) there exists an optimum number of ion channels which allows for the most efficient signal propagation and it corresponds to the actual physiological values.Comment: 8 pages, 12 figures, accepted for publication in Phys. Rev.