Geology of the Mt. Prospect Region, Western Connecticut

Guidebook for field trips in Connecticut and adjacent areas of New York and Rhode Island: New England Intercollegiate Geological Conference 77th annual meeting, Yale University, New Haven, Connecticut, October 4-6, 1985: Trip C

TIME-COURSE OF SPATIO-TEMPORAL ADAPTATION; WITH RESPECT TO THE EXISTENCE OF SEPARATE SPATIAL AND TEMPORAL VISUAL MECHANISMS

A series of experiments examined the hypothesis that spatial and temporal variation are processed by separate visual mechanisms. The first set of experiments determined that contrast thresholds set using spatial and temporal criteria covaried for counterphase-flickered gratings over a wide range of spatial and temporal frequencies. The two threshold curves appeared more independent when gratings were drifted, but this probably resulted from different patterns of eye movements within the two tasks. A second set of experiments measured the time-course of adaptation under conditions designed to isolate the two hypothetical mechanisms, in an attempt to record a temporal fingerprint characterizing each mechanism. A test-probe procedure was used to determine contrast thresholds over 60 seconds of adaptation rise-time and 128 seconds of decay. Time constants of exponential curves fit to these data showed no pattern which could be related to the two mechanism hypothesis. A corresponding experiment categorized the appearance of near-threshold gratings during adaptation buildup and decay. When corrected for false-alarm rates, the perception of the stimuli were always pattern, or both pattern and flicker, even when a temporal mechanism should have performed the detection. These results uniformly fail to support the two mechanism hypothesis

Antipsychotic Adherence Patterns and Health Care Utilization and Costs Among Patients Discharged After a Schizophrenia-Related Hospitalization

This study aimed to assess antipsychotic adherence patterns and all-cause and schizophrenia-related health care utilization and costs sequentially during critical clinical periods (i.e., before and after schizophrenia-related hospitalization) among Medicaid-enrolled patients experiencing a schizophrenia-related hospitalization

Vehicle egomotion estimation using computer vision

Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Aeronautics and Astronautics, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 107-108).A vision based navigation alter is developed for application on UAVs and tested in simulation. This alter is meant to allow the UAV to navigate in GPS-denied environments using measurements from a suite of cameras. The extended Kalman alter integrates measurements from multiple non-overlapping cameras as well as an IMU and occasional GPS. Simulations are conducted to evaluate the performance of the alter in a variety of fight regimes as well as to assess the value of using multiple cameras. Simulations demonstrate the value of using multiple cameras for egomotion estimation. Multiple non-overlapping cameras are useful for resolving motion in an unobservable direction that manifests as an ambiguity between translation and rotation. Additionally, multiple cameras are extremely useful when flying in an environment such as an urban canyon, where features remain in the fields of view for a very short period of time.by Robert Martin Panish.S.M

Self-directed growth of AlGaAs core-shell nanowires for visible light applications

Al(0.37)Ga(0.63)As nanowires (NWs) were grown in a molecular beam epitaxy system on GaAs(111)B substrates. Micro-photoluminescence measurements and energy dispersive X-ray spectroscopy indicated a core-shell structure and Al composition gradient along the NW axis, producing a potential minimum for carrier confinement. The core-shell structure formed during the growth as a consequence of the different Al and Ga adatom diffusion lengths.Comment: 20 pages, 7 figure