Showing papers by "University of Southern California published in 1979"

Handbook of the Psychology of Aging

Abstract: The Handbook of the Psychology of Aging, Seventh Edition, provides a basic reference source on the behavioral processes of aging for researchers, graduate students, and professionals. It also provides perspectives on the behavioral science of aging for researchers and professionals from other disciplines. The book is organized into four parts. Part 1 reviews key methodological and analytical issues in aging research. It examines some of the major historical influences that might provide explanatory mechanisms for a better understanding of cohort and period differences in psychological aging processes. Part 2 includes chapters that discuss the basics and nuances of executive function; the history of the morphometric research on normal brain aging; and the neural changes that occur in the brain with aging. Part 3 deals with the social and health aspects of aging. It covers the beliefs that individuals have about how much they can control various outcomes in their life; the impact of stress on health and aging; and the interrelationships between health disparities, social class, and aging. Part 4 discusses the emotional aspects of aging; family caregiving; and mental disorders and legal capacities in older adults. * Contains all the main areas of psychological gerontological research in one volume* Entire section on neuroscience and aging* Begins with a section on theory and methods* Edited by one of the father of gerontology (Schaie) and contributors represent top scholars in gerontology

Quantitative design and evaluation of enhancement/thresholding edge detectors

Abstract: Quantitative design and performance evaluation techniques are developed for the enhancement/thresholding class of image edge detectors. The design techniques are based on statistical detection theory and deterministic pattern-recognition classification procedures. The performance evaluation methods developed include: a)deterministic measurement of the edge gradient amplitude; b)comparison of the probabilities of correct and false edge detection; and c) figure of merit computation. The design techniques developed are used to optimally design a variety of small and large mask edge detectors. Theoretical and experimental comparisons of edge detectors are presented.

Extreme ultraviolet observations from Voyager 1 encounter with Jupiter

Abstract: The global hydrogen Lyman alpha, helium (584 angstroms), and molecular hydrogen band emissions from Saturn are qualitatively similar to those of Jupiter, but the Saturn observations emphasize that the H(2) band excitation mechanism is closely related to the solar flux. Auroras occur near 80 degrees latitude, suggesting Earth-like magnetotail activity, quite different from the dominant Io plasma torus mechanism at Jupiter. No ion emissions have been detected from the magnetosphere of Saturn, but the rings have a hydrogen atmosphere; atomic hydrogen is also present in a torus between 8 and 25 Saturn radii. Nitrogen emission excited by particles has been detected in the Titan dayglow and bright limb scans. Enhancement of the nitrogen emission is observed in the region of interaction between Titan's atmosphere and the corotating plasma in Saturn's plasmasphere. No particle-excited emission has been detected from the dark atmosphere of Titan. The absorption profile of the atmosphere determined by the solar occultation experiment, combined with constraints from the dayglow observations and temperature information, indicate that N(2) is the dominant species. A double layer structure has been detected above Titan's limb. One of the layers may be related to visible layers in the images of Titan.

Linear feature extraction and description

Abstract: A technique of edge detection and linking for linear feature extraction and its applications to detection of roads and runway like structures is described. Experimental results are included.

Image segmentation by clustering

Abstract: This paper describes a procedure for segmenting imagery using digital methods and is based on a mathematical-pattern recognition model. The technique does not require training prototypes but operates in an "unsupervised" mode. The features most useful for the given image to be segmented are retained by the algorithm without human interaction, by rejecting those attributes which do not contribute to homogeneous clustering in N-dimensional vector space. The basic procedure is a K-means clustering algorithm which converges to a local minimum in the average squared intercluster distance for a specified number of clusters. The algorithm iterates on the number of clusters, evaluating the clustering based on a parameter of clustering quality. The parameter proposed is a product of between and within cluster scatter measures, which achieves a maximum value that is postulated to represent an intrinsic number of clusters in the data. At this value, feature rejection is implemented via a Bhattacharyya measure to make the image segments more homogeneous (thereby removing "noisy" features); and reclustering is performed. The resulting parameter of clustering fidelity is maximized with segmented imagery resulting in psychovisually pleasing and culturally logical image segments.

Prognosis of Patients with Severe Head Injury

Abstract: The relationship between clinical features of brain dysfunction in the first week after severe head injury and outcome 6 months later has been analyzed for 1000 patients. Depth of coma, pupil reaction, eye movements, and motor response pattern, and patient age prove to be the most reliable predictors. The degree of brain dysfunction changes markedly soon after injury, and more reliable predictions of outcome result when assessment is based on the best level of functioning recorded in each early epoch. Predictions based on very early assessment are, therefore, often unduly pessimistic. Individual predictions of outcome, based on a large data bank, provide a powerful tool for assessing the relative efficacy of alternative treatments.

A comparison of two methods for determining the weights of belonging to fuzzy sets

Abstract: Saaty has solved a basic problem in fuzzy set theory using an eigenvector method to determine the weights of belonging of each member to the set. In this paper, a weighted least-square method is utilized to obtain the weights. This method has the advantage that it involves the solution of a set of simultaneous linear algebraic equations and is thus conceptually easier to understand than the eigenvector method. Examples are given for estimating the relative wealth of nations and the relative amount of foreign trade of nations. Numerical solutions are obtained using both the eigenvector method and the weighted least-square method, and the results are compared.

Theory of bistability in nonlinear distributed feedback structures

Abstract: We show that optical bistability can occur in a distributed feedback structure with an intensity‐dependent refractive index. Analytical expressions for the transmissivity are obtained and a comparison with Fabry‐Perot‐type devices is presented.

Experiments on the Weis-Fogh mechanism of lift generation by insects in hovering flight. Part 1. Dynamics of the ‘fling’

Abstract: From a series of experiments using simplified mechanical models we suggest certain minor modifications to the Weis-Fogh (1973)–Lighthill (1973) explanation of the so-called ‘clap and fling’ mechanism for the generation of large lift coefficients by insects in hovering flight. Of particular importance is the production and motion of a leading edge, separation vortex that accounts for virtually all of the circulation generated during the initial phase of the ‘fling’ process. The magnitude of this circulation is substantially larger than that calculated using inviscid theory. During the motion that subsequently separates the wings, the vorticity over each of them is convected and combined to become a tip vortex of uniform circulation spanning the space between them. This combined vortex moves downwards as a part of a ring, of large impulse, that is then continuously fed from quasi-steady separation bubbles that move with the wings as they continue to open at a large angle of attack. Such effects are able to account for the large lift forces generated by the insect.

Risk factors for cancer of the testis in young men.

Abstract: An individual matched case-control study of testis cancer in 131 men under age 40 was conducted to investigate antecedent risk factors including events during prenatal life. Ten patients were born with an undescended testis compared to only two controls (p less equal to 0.02), a previously reported risk factor. Two new risk factors were uncovered: six patients-mothers received hormones during the index pregnancy compared to only one control-mother, and eight patient-mothers and two control-mothers reported excessive nausea as a complication of the index pregnancy. A hypothesis linking these three factors is presented: viz, that a major risk factor for testis cancer is a relative excess of certain hormones (in particular estrogen) at the time of differentiation of the testes.

High-Resolution X-Ray Photoelectron Spectroscopy as a Probe of Local Atomic Structure: Application to Amorphous Si O 2 and the Si-Si O 2 Interface

Abstract: The chemical structure of thin Si${\mathrm{O}}_{2}$ films and Si${\mathrm{O}}_{2}$-Si interfaces has been investigated using high-resolution x-ray photoelectron spectroscopy. The data are consistent with a continuous random network of four-, six-, seven-, and eight-member rings of Si${\mathrm{O}}_{4}$ tetrahedra joined together by bridging oxygens. This distribution changes substantially within 30 \AA{} of the Si${\mathrm{O}}_{2}$-Si interface. The near-interface region is comprised of ${\mathrm{Si}}_{2}$${\mathrm{O}}_{3}$, SiO, and ${\mathrm{Si}}_{2}$O. This structure is interpreted by means of a structure-induced-charge-transfer model.

Streamwise vortices associated with the bursting phenomenon

Abstract: The streamwise and spanwise velocity components and the gradients of these components normal to the wall were examined by using hot-film sensors and flush-mounted wall elements to study the vortex structures associated with the bursting phenomenon. Quadrant probability analysis and conditional sampling techniques indicated that pairs of counter-rotating streamwise vortices occur frequently in the wall region of a bounded turbulent shear flow. A streamwise momentum defect occurred between the vortices as low-speed fluid was ‘pumped’ away from the wall by the vortex pair. The defect region was long and narrow and possibly forms the low-speed streak as observed in visualization studies. The velocity defect was terminated by a strong acceleration followed by a high speed region.

A forced directed component placement procedure for printed circuit boards

Abstract: This paper deals with the problem of placing components on a carrier, such as a printed circuit board (PCB). We present a new mathematical formulation of the concept of force directed placement, and describe an efficient computational procedure for solving the resulting system of equations. The placement procedure is broken down into two phases, Phase I being the "relative location phase," and Phase II being the "slot assignment or component overlap resolution phase." In Phase I of the procedure, we solve a set of simultaneous equations, based upon the interconnection topology of the system of components, in an endeavor to determine the optimum relative location of every component with respect to every other component. The equations are set up such that there are attractive forces between components sharing a common signal, and repulsive forces between components having no signals in common. The results of Phase I are often unacceptable from a physical standpoint because there is a great deal of overlap among the components. Phase II eliminates component overlap by either of two methods, depending upon the physical properties of the carrier. If the carrier is subdivided into slots, then the components are assigned to these slots using a criteria which minimiZes the total distance that all components need be moved. We perform this assignment by using the linear assignment algorithm. If the carrier is such that components are allowed to reside anywhere, then a different technique to resolve component overlap is used. A parametric analysis of the procedure is given based upon 12 different PCB's. These results show comparisons of this method to the work of others, and provide some insight into the method's absolute merits.

Chordoma: A Clinicopathologic Study of Metastasis

Abstract: Thirty cases of chordoma were reviewed with respect to the incidence of distant metastases. Follow-up information was obtained in 27 (90%), and the incidence of metastases was approximately 30%. The sites of the metastasizing primary tumors were predominantly sacral and vertebral. The sites of the metastases were predominantly skin and bone, although metastases were found in the lungs and lymph nodes. In two of the three patients with dermal metastases, the metastases were present prior to the diagnosis of the primary lesions. All three dermal metastases were initially diagnosed as mixed tumors of the skin, and all three patients had at least four such lesions of the skin. Accurate prediction of which chordomas will eventually metastasize is difficult. Clinically, local aggressiveness and radiotherapy were positively correlated with this ability; histologically, more anaplastic chordomas were more likely to metastasize.

Potentiation of Neuromuscular Transmission by an Octopaminergic Neurone in the Locust

Abstract: 1. Spikes in the octopaminergic dorsal unpaired median (DUM) neurone which innervates the extensor tibiae muscle of the locust metathoracic leg (DUMETi) produce direct and indirect effects on muscle tension. 2. Direct effects include a slowing of an intrinsic rhythm of contraction and relaxation, a relaxation of muscle tone and a small hyperpolarization of the muscle membrane potential. The latter two effects are weak and variable. All three effects are mimicked by superfusion of octopamine and are mediated by octopamine receptors on the muscle fibres. 3. Indirect effects are found when the DUMETi neurone is stimulated at the same time as the motoneurones innervating the extensor muscle. They include (a) potentiation of tension generated in the extensor muscle by spikes in the slow excitatory motoneurone (SETi), (b) reduction in duration of each twitch contraction generated by SETi due to an increase in the rate at which the muscle relaxes, (c) increase in the amplitude of the synaptic potential generated by SETi. These various effects have a time course of several minutes and far outlast the duration of DUMETi stimulation. They can be mimicked by superfusion of octopamine. 4. The effect of DUMETi on neuromuscular transmission is mediated by receptors with a high affinity for octopamine located both on the muscle and on the terminals of the slow motoneurone. The presence of the presynaptic receptors is revealed by the increase in the frequency of spontaneous miniature end plate potentials recorded in the muscle in the presence of octopamine. 5. DUMETi is a member of a group of similar aminergic neurones and it is suggested that they may share a role in modulating transmission at peripheral neuromuscular synapses, and possibly central synapses.

A simple proof of the mean ergodic theorem for nonlinear contractions in Banach spaces

Abstract: The following theorem is proven:if E is a uniformly rotund Banach space with a Frechet differentiable norm, C is a bounded nonempty closed convex subset of E, and T: C→C is a contraction, then the iterates {Tnx} are weakly almost-convergent to a fixed-point of T.

Untreated Periodontal Disease: A Longitudinal Study

Abstract: Thirty diagnosed but untreated patients with moderate to advanced periodontal disease were examined a minimum of two times. The examination time intervals ranged between 18 and 115 months. 2. A total of 83 teeth were lost between examinations. 3. Excluding a patient who lost 25 teeth, a total of 58 teeth were lost. The adjusted tooth loss was 0.61 tooth per patient per year (or 0.36 with the elimination of 22 "hopeless" teeth). 4. The mandibular and maxillary molars had the greatest percentage of tooth loss between examinations. 5. All 29 patients completing the study had progessive increases in pocket depth during their time in the study. Increases in the mean annual pocket depths per tooth per patient varied from 0.24 millimeter per year to 2.46 millimeters per year. 6. The disto-lingual and mesio-lingual interproximal surfaces had the greatest increases in surface pocket depths. The lingual and buccal surfaces had the smallest increases in pocket depth. 7. The rate of increase in pocket depths was less in patients over 44 years of age. 8. The teeth which were lost had greater initial pocket depths and mobility scores than those which were present at both examinations. 9. There was no correlation between increases in pocket depth and changes in mobility. 10. All 29 patients showed radiographic evidence of progressive bone resorption between examinations. The posterior segments of the mouth had the largest amounts of bone loss between the first and last examinations.

The Similarity of Individual Directed and Group Directed Leader Behavior Descriptions

Abstract: The similarity between individual directed and group directed leadership descriptions of subordinates was examined among 308 public utility employees. The correlations among the variables revealed ...