23,278 research outputs found
Johnson - James B. Johnson (1883)
No full textNon-graduate, left first term, Junior, 1881. Entered Preparatory, 1878. Born in 1850. Residence, Homer City, Pa. Phrenakosmian, Phi Delta Theta. Handwritten on back: ""Yours Magnificently J. B. Johnson"
Jessie Johnson Interview
No full textInterview in which Jessie Johnson discusses emigrated from Pittsburg, PA to Newark in 1944, among other topics
Photograph of Catharine F. Johnson
No full textColor photograph of Catharine F. Johnson. Back reads: "Aunt Foldie Fletcher Scott Johnson at desk. Phila. Pa.
Robustness of computational time reversal imaging in media with elastic constant uncertainties
No full textIn order to image a source or a scatterer embedded in a three dimensional solid, acoustic/elastic wave data from an actual experiment are time reversed and backpropagated through a numerical model of the medium. The model makes use of estimates for the elastic constants of the laboratory solid. These estimates may not be very precise, for example, due to experimental uncertainties. Poor characterization of the medium leads to the degradation of the time reversal focus, therefore, to poor medium imaging. In this work, we report on the results of investigating the time reversal focus degradation as the estimates depart from the real values. Very small deviations from the medium's actual elastic constants degrade the time reversal focus dramatically. However, decreasing the total duration of the signals used for time reversal can attenuate the degradation in some cases. We propose a new method to compensate for the deviations of the model medium's elastic constants from the actual values. Finally, we explore the effects of scatterers that may exist in the laboratory medium, but are not included in the model medium, and show that their presence does not produce significant effects on the time reversal focu
Rapid Online Assessment of Reading and Phonological Awareness (ROAR-PA)
No full textPhonological awareness (PA) is at the foundation of reading development: PA is introduced before formal reading instruction, has predictive value for later reading abilities, is a primary target for early intervention, and is considered one of the core mechanisms in developmental dyslexia. Conventional approaches to assessing PA are time-consuming and resource intensive: assessments must be individually administered, require expertise, and scoring verbal responses is challenging and subjective. Therefore, we introduce a rapid, automated, online measure of PA — The Rapid Online Assessment of Reading - Phonological Awareness (ROAR-PA) — that can be widely implemented in classrooms and research studies without a test administrator. We explored whether this gamified, online task, that relies on touchscreen/click responses, can serve as an accurate and reliable measure of PA and as a good predictor of reading development. We found that ROAR-PA is well correlated with standardized measures of PA (CTOPP-2, r = .80) and reading (Woodcock-Johnson, r = .50), for children from Pre-K through fourth grade and achieves exceptional reliability ( = .96) in a 12-minute automated, online assessment. Furthermore, validation in 50 first and second grade classrooms shows reliable implementation in large, public school classrooms with predictive value of future reading development
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