RELEVANCY OF THE SOCIAL SCIENCES IN THE POLICY ARENA: IMPLICATIONS FOR AGRICULTURAL ECONOMICS

Agricultural and Food Policy,

FORCES DRIVING THE FUTURE OF EXTENSION

Teaching/Communication/Extension/Profession,

DISTRIBUTIONAL ISSUES IN FOOD AND AGRICULTURAL POLICY: CONCEPTS AND ISSUES

Agricultural and Food Policy,

THE ROLE OF THE UNIVERSITY IN PUBLIC POLICY EDUCATION

Teaching/Communication/Extension/Profession,

RESULTS OF THE NASULGC'S NATIONAL SYNTHESIS CONFERENCE IN RELATION TO THE OVERALL LAND GRANT UNIVERSITY METAMORPHOSIS

Teaching/Communication/Extension/Profession,

LAND GRANT UNIVERSITIES ARE CHANGING

Teaching/Communication/Extension/Profession,

Successful threshing ring management

Cover title.Includes bibliographical references

GETTING FROM ECONOMIC ANALYSIS TO POLICY ADVICE

Agricultural and Food Policy,

3D motion : encoding and perception

The visual system supports perception and inferences about events in a dynamic, three-dimensional (3D) world. While remarkable progress has been made in the study of visual information processing, the existing paradigms for examining visual perception and its relation to neural activity often fail to generalize to perception in the real world which has complex dynamics and 3D spatial structure. This thesis focuses on the case of 3D motion, developing dynamic tasks for studying visual perception and constructing a neural coding framework to relate neural activity to perception in a 3D environment. First, I introduce target-tracking as a psychophysical method and develop an analysis framework based on state space models and the Kalman filter. I demonstrate that target-tracking in conjunction with a Kalman filter analysis framework produce estimates of visual sensitivity that are comparable to those obtained with a traditional forced-choice task and a signal detection theory analysis. Next, I use the target-tracking paradigm in a series of experiments examining 3D motion perception, specifically comparing the perception of frontoparallel motion with the perception of motion-through-depth. I find that continuous tracking of motion-through-depth is selectively impaired due to the relatively small retinal projections resulting from motion-through-depth and the slower processing of binocular disparities. The thesis then turns the neural representation of 3D motion and how that underlies perception. First I introduce a theoretical framework that extends the standard neural coding approach, incorporating the environment-to-retina transformation. Neural coding typically treats the visuals stimulus as a direct proxy for the pattern of stimulation that falls on the retina. Incorporating the environment-to-retina transformation results in a neural representation fundamentally shaped by the projective geometry of the world onto the retina. This model explains substantial anomalies in existing neurophysiological recordings in primate visual cortical neurons during presentations of 3D motion and in psychophysical studies of human perception. In a series of psychophysical experiments, I systematically examine the predictions of the model for human perception by observing how perceptual performance changes as a function of viewing distance and eccentricity. Performance in these experiments suggests a reliance on a neural representation similar to the one described by the model. Taken together, the experimental and theoretical findings reported here advance the understanding of the neural representation and perception of the dynamic 3D world, and adds to the behavioral tools available to vision scientists.Neuroscienc

Profitable Farming Systems for the Intensive Spring Wheat Area in South Dakota

The plan of the Department of Farm Economics of South Dakota State College is to study in detail the organization and operation of farms in each of the principal type-of-farming areas in the State. The object of these studies is to determine the systems of farming likely to give good results in an area over a period of years, including enterprise combinations which appear advantageous; practices giving good results in the principal enterprises; and adjustments between and within the enterprises likely to be desirable with changing conditions