Estimation of dynamically evolving ellipsoids with applications to medical imaging

The estimation of dynamically evolving ellipsoids from noisy lower-dimensional projections is examined. In particular, this work describes a model-based approach using geometric reconstruction and recursive estimation techniques to obtain a dynamic estimate of left-ventricular ejection fraction from a gated set of planar myocardial perfusion images. The proposed approach differs from current ejection fraction estimation techniques both in the imaging modality used and in the subsequent processing which yields a dynamic ejection fraction estimate. For this work, the left ventricle is modeled as a dynamically evolving three-dimensional (3-D) ellipsoid. The left-ventricular outline observed in the myocardial perfusion images is then modeled as a dynamic, two-dimensional (2-D) ellipsoid, obtained as the projection of the former 3-D ellipsoid. This data is processed in two ways: first, as a 3-D dynamic ellipsoid reconstruction problem; second, each view is considered as a 2-D dynamic ellipse estimation problem and then the 3-D ejection fraction is obtained by combining the effective 2-D ejection fractions of each view. The approximating ellipsoids are reconstructed using a Rauch-Tung-Striebel smoothing filter, which produces an ejection fraction estimate that is more robust to noise since it is based on the entire data set; in contrast, traditional ejection fraction estimates are based only on true frames of data. Further, numerical studies of the sensitivity of this approach to unknown dynamics and projection geometry are presented, providing a rational basis for specifying system parameters. This investigation includes estimation of ejection fraction from both simulated and real data.     

Human factors in operating systems related to delay and displacement of retinal feedback.

Evaluated theories of response to altered retinal feedback i.e., associative learning doctrines and the feedback-compensation hypothesis in relation to their application in defining human factors principles in machine and perceptual training designs. Using 12 Ss, controlled comparisons were made of the relative effects of reversed and delayed feedback of head and eye movements under conditions in which head movements could not compensate altered feedback of eye movements and vice versa. Findings, e.g., the accuracy of ocular tracking, etc., are discussed. Some results indicate that there was little or no learned adaptation to the reversed and delayed vision produced by head and eye movements. Findings support a behavioral cybernetic interpretation of the guidance factors in man-machine and perceptual systems relationships by showing that the effects of altered feedback in machine and systems operation are determined by movement capabilities in compensating displacements and delays in sensory input. Results also suggest that visual impairments may be produced by delays in the retinal feedback effects of eye and head movements and that these defects may require dynamic methods of optometric diagnosis and training for their measurement and correction. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Temperaturmessungen an Sauerstoffschiebern

Die Aufklärung von Unfällen an Sauerstoffschiebern, die gegen eine drucklose Leitung öffneten, ließ thermodynamische Ursachen vermuten. Bei der hohen Affinität des Schieberwandmaterials Stahl zum reinen Sauerstoff genügt die punktförmige Erzeugung der Entzündungstemperatur zum Beginn einer explosionsartigen Verbrennung des Schieberkörpers. Theoretisch und versuchsmäßig wird nachgewiesen, daß thermodynamische Prozesse existieren, die bei geeigneter Abstimmung der beteiligten geometrischen und thermodynamischen Parameter als Unfallursache in Frage kommen. Zur Nachprüfung wurde das Temperaturverhalten realer Sauerstoffschieber beim Betrieb mit Druckluft experimentell ermittelt.     

False feedback and longevity of the conditioned GSR during extinction: Some implications for aversion therapy.

Investigated the effects of 2 cognitive variables on GSR extinction rates. Exp. I replicated findings that Ss made aware of the onset of nonshocked trials exhibited extinction of a conditioned emotional response more rapidly than Ss not made aware. Exp. I and II (80 and 20 Ss, respectively) further demonstrated that extinction, even under conditions of awareness, can be significantly retarded when false feedback concerning the S's current emotional responsivity is supplied during extinction trials. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ebbinghaus' Bibliography.

The interesting note by Dennis ("Bibliographies of eminent psychologists." Amer. Psychologist, 1954, 9, pp. 35-36) on the bibliographies of eminent psychologists contains an error regarding Hermann Ebbinghaus' bibliography that should be corrected before it becomes a legend. Dennis states that "Ebbinghaus is decidedly the low man [of his group], his bibliography containing only 13 items." In this connection, attention is invited to Shakow's ("Bibliography of Hermann Ebbinghaus", Amer. J. Psychol., 1930, 42, pp 516-518) bibliography of Ebbinghaus in which 44 titles are listed. The difference between the number of titles listed by Shakow and given by Dennis is not great. One may be accurate however, and still demonstrate that Ebbinghaus' published work is surprisingly small for a man of his stature and reputation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Feedback analysis of learning and performance in steering and tracking behavior.

Tested the assumption that steering and tracking behavior are interrelated in terms of the extent of self-produced stimulation involved in the 2 tasks. Steering was defined as involving maximal, and stimulus tracking as involving minimal levels of movement-regulated sensory information. 3 tasks steering, as governed by breath-produced target movement, stimulus tracking, and a hand-yoked target control task were compared under conditions in which the difficulty of the steering and stimulus tracking tasks were exactly equated. Results show that steering performance was more accurate and learned more rapidly than stimulus tracking. Oscillograph records of all aspects of performance indicate that the 2 tasks differed psychophysiologically in terms of how the self-timed respiratory activities and the external manual-visual responses were continuously and dynamically interrelated to control visual input. Results suggest that the modes and conditions of feedback control of dynamic sensory input not only determine accuracy of performance and rate of learning, but also define how internally-timed organic functions are integrated to determine learning in motor skills and other activities. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Ausscheidungsteilchen in hochkohlenstoffhaltigem chromlegiertem Stahl

Röntgenographische Untersuchungen sowie elektronenmikroskopische Durchstrahlungs- und Feinbereichsbeugungs-Untersuchungen an Dünnschliffen aus einem Stahl mit rd. 1,45% G und 1,4% Cr nach martensitischem Härten und Anlassen bis 10 000 min bei 40 bis 100°C zur Ermittlung der beim Anlassen auftretenden Ausscheidungsphasen (Kohlenstoff und Karbide). Folgerungen über deren morphologische und kristallographische Merkmale.     

Anwendung des quantitativen Fernsehmikroskopes und der Elektronenstrahlmikrosonde für die Untersuchung des Systems Eisen—Kohlenstoff—Phosphor bei 900 bis 1000°C

Neue Wege, mit geringem Aufwand an Legierungen metallische Mehrstoffsysteme im festen Zustand zu untersuchen: 1. durch Mengenmessung der Phasen mit dem quantitativen Fernsehmikroskop und Errechnung der Sättigungskonzentrationen, 2. durch Ermittlung der Phasenzusammensetzung mit der Elektronenstrahlmikrosonde. Vergleich der herkömmlichen und neuen Verfahren. Untersuchung der Eisenecke des Systems Eisen–Phosphor–Kohlenstoff bei 900, 950 und 1000°C.     

After Legislation--Comments and Rejoinders.

Karl C. Pratt comments that the issues so cogently stated by C. Deutsch ("After Legislation--What Price Psychology?"; American Psychologist, 1958, 13, 645-652) are fundamental and deserve consideration by our profession. Deutsch has clearly stated the case for a broader conception of the science of psychology than such legislation formalizes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Perceptions of the ideal community.

A stratified random sample of 4,619 adults living in 3 different-sized communities in Indiana responded to a mail survey assessing their orientations to the ideal residential community. Ratings of the importance of 11 attributes of a community were factor analyzed, yielding 3 dimensions: (a) Maintenance, (b) Personal Relations, and (c) Recreation. (PsycINFO Database Record (c) 2010 APA, all rights reserved)