Showing papers by "University of Southern California published in 1985"
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TL;DR: Virtual time is a new paradigm for organizing and synchronizing distributed systems which can be applied to such problems as distributed discrete event simulation and distributed database concurrency control.
Abstract: Virtual time is a new paradigm for organizing and synchronizing distributed systems which can be applied to such problems as distributed discrete event simulation and distributed database concurrency control. Virtual time provides a flexible abstraction of real time in much the same way that virtual memory provides an abstraction of real memory. It is implemented using the Time Warp mechanism, a synchronization protocol distinguished by its reliance on lookahead-rollback, and by its implementation of rollback via antimessages.
2,280 citations
TL;DR: The adaptive noise smoothing filter is a systematic derivation of Lee's algorithm with some extensions that allow different estimators for the local image variance and its easy extension to deal with various types of signal-dependent noise.
Abstract: In this paper, we consider the restoration of images with signal-dependent noise. The filter is noise smoothing and adapts to local changes in image statistics based on a nonstationary mean, nonstationary variance (NMNV) image model. For images degraded by a class of uncorrelated, signal-dependent noise without blur, the adaptive noise smoothing filter becomes a point processor and is similar to Lee's local statistics algorithm [16]. The filter is able to adapt itself to the nonstationary local image statistics in the presence of different types of signal-dependent noise. For multiplicative noise, the adaptive noise smoothing filter is a systematic derivation of Lee's algorithm with some extensions that allow different estimators for the local image variance. The advantage of the derivation is its easy extension to deal with various types of signal-dependent noise. Film-grain and Poisson signal-dependent restoration problems are also considered as examples. All the nonstationary image statistical parameters needed for the filter can be estimated from the noisy image and no a priori information about the original image is required.
1,475 citations
TL;DR: In this paper, survey data from 142 employees and 968 customers from 28 branches of a bank were analyzed with the following results: moderate support was found for previous work on correlates of role stress for boundary role employees and good support for relationships between branch employees' and branch customers' service perceptions and attitudes.
Abstract: : Survey data from 142 employees and 968 customers from 28 branches of a bank were analyzed with the following results: (1) Moderate support was found for previous work on correlates of role stress for boundary role employees and good support was found for relationships between branch employees' and branch customers' service perceptions and attitudes; (2) Some significant relationships were reported between branch employees' perceptions of organizational human resources practices and branch customers' attitudes about service; and (3) employee attitudes and customer attitudes were related to their own and one another's turnover intentions. Results were discussed from the perspective of promoting an integration of consumer and organizational behavior in the service sector.
1,396 citations
TL;DR: The t(14;18)(q32;q21) chromosomal translocation present in over 60% of human follicular lymphomas is characterized and an unexpected rearrangement of an Ig heavy-chain gene is exploited to clone the chromosomal breakpoint.
1,206 citations
TL;DR: Evidence emerged suggesting that human diabetes mellitus has a multifactorial etiology, and larger doses of insulin were required to normalize the blood sugar in patients with the milder nonketotic form of the disease common in the older population, whereas smaller doses were adequate for younger, ketosis-prone diabetics.
Abstract: I. Origin of the Insulin Sensitivity Concept HISTORICALLY, the study of the pathogenesis of diabetes mellitus was in the traditional pattern of endocrinology: removal of the pancreas led to experimental diabetes, and administration of insulin, a pancreatic isolate, ameliorated the diabetic symptoms (1, 2). These observations led to the widely held belief that human diabetes was primarily a disease of the pancreas, characterized by the inability of the B cell to secrete sufficient insulin to control glycemia. After insulin became available, evidence emerged suggesting that human diabetes mellitus has a multifactorial etiology. Early investigators identified an unexpected variability among diabetics in the ability of injected insulin to ameliorate hyperglycemia (3–5). Larger doses of insulin were required to normalize the blood sugar in patients with the milder nonketotic form of the disease common in the older population, whereas smaller doses were adequate for younger, ketosis-prone diabetics.
1,146 citations
TL;DR: The absolute or convective character of inviscid instabilities in parallel shear flows can be determined by examining the branch-point singularities of the dispersion relation for complex frequencies and wavenumbers.
Abstract: The absolute or convective character of inviscid instabilities in parallel shear flows can be determined by examining the branch-point singularities of the dispersion relation for complex frequencies and wavenumbers. According to a criterion developed in the study of plasma instabilities, a flow is convectively unstable when the branch-point singularities are in the lower half complex-frequency plane. These concepts are applied to a family of free shear layers with varying velocity ratio their average velocity. It is demonstrated that spatially growing waves can only be observed if the mixing layer is convectively unstable, i.e. when the velocity ratio is smaller than Rt = 1.315. When the velocity ratio is larger than Rt, the instability develops temporally. Finally, the implications of these concepts are discussed also for wakes and hot jets.
803 citations
TL;DR: An approach to the coordinated sharing and interchange of computerized information is described emphasizing partial, controlled sharing among autonomous databases.
Abstract: An approach to the coordinated sharing and interchange of computerized information is described emphasizing partial, controlled sharing among autonomous databases. Office information systems provide a particularly appropriate context for this type of information sharing and exchange. A federated database architecture is described in which a collection of independent database systems are united into a loosely coupled federation in order to share and exchange information. A federation consists of components (of which there may be any number) and a single federal dictionary. The components represent individual users, applications, workstations, or other components in an office information system. The federal dictionary is a specialized component that maintains the topology of the federation and oversees the entry of new components. Each component in the federation controls its interactions with other components by means of an export schema and an import schema. The export schema specifies the information that a component will share with other components, while the import schema specifies the nonlocal information that a component wishes to manipulate. The federated architecture provides mechanisms for sharing data, for sharing transactions (via message types) for combining information from several components, and for coordinating activities among autonomous components (via negotiation). A prototype implementation of the federated database mechanism is currently operational on an experimental basis.
623 citations
TL;DR: Two feature extraction methods for the classification of textures using two-dimensional Markov random field (MRF) models are presented and it is shown that the sample correlations over a symmetric window including the origin are optimal features for classification.
Abstract: The problem of texture classification arises in several disciplines such as remote sensing, computer vision, and image analysis. In this paper we present two feature extraction methods for the classification of textures using two-dimensional (2-D) Markov random field (MRF) models. It is assumed that the given M × M texture is generated by a Gaussian MRF model. In the first method, the least square (LS) estimates of model parameters are used as features. In the second method, using the notion of sufficient statistics, it is shown that the sample correlations over a symmetric window including the origin are optimal features for classification. Simple minimum distance classifiers using these two feature sets yield good classification accuracies for a seven class problem.
531 citations
TL;DR: In this article, the authors consider the case where particles are gravitationally trapped near a four-dimensional submanifold of the higher-dimensional spacetime and construct a Kaluza-Klein model in five dimensions.
482 citations
TL;DR: Results are evidence that the central nervous system is capable of a plastic response in Alzheimer's disease, and adaptive growth responses occur along with the degenerative events.
Abstract: Two markers of neuronal plasticity were used to compare the response of the human central nervous system to neuronal loss resulting from Alzheimer's disease with the response of rats to a similar neuronal loss induced by lesions. In rats that had received lesions of the entorhinal cortex, axon sprouting of commissural and associational fibers into the denervated molecular layer of the dentate gyrus was paralleled by a spread in the distribution of tritiated kainic acid-binding sites. A similar expansion of kainic acid receptor distribution was observed in hippocampal samples obtained postmortem from patients with Alzheimer's disease. An enhancement of acetylcholinesterase activity in the dentate gyrus molecular layer, indicative of septal afferent sprouting, was also observed in those patients with a minimal loss of cholinergic neurons. These results are evidence that the central nervous system is capable of a plastic response in Alzheimer's disease. Adaptive growth responses occur along with the degenerative events.
472 citations
TL;DR: The authors situates the narrative paradigm in regard to major social scientific and humanistic theories, and applies the paradigm in an interpretation and assessment of the conversation between Socrates and Callicles in Plato's Gorgias.
Abstract: This essay situates the narrative paradigm in regard to major social scientific and humanistic theories, and applies the paradigm in an interpretation and assessment of the conversation between Socrates and Callicles in Plato's Gorgias.
TL;DR: Pulmonary complications, including pulmonary edema and congestion, appeared to be the most significant factor contributing to death and occurred even in those cases where the pancreatic damage appears to be only moderate in extent, which should contribute significantly to an increase in survival in this disease.
Abstract: A large retrospective autopsy study of patients was analyzed to evaluate the major etiologic and pathologic factors contributing to fatal acute pancreatitis (AP). From an autopsy population of 50,227 patients, 405 cases were identified where AP was defined as the official primary cause of death. AP was classified according to morphological and histological, but not biochemical, criteria. Patients with AP died significantly earlier than a control autopsy population of 38,259 patients. Sixty percent of the AP patients died within 7 days of admission. Pulmonary edema and congestion were significantly more prevalent in this group, as was the presence of hemorrhagic pancreatitis. In the remaining 40% of patients surviving longer than 7 days, infection was the major factor contributing to death. Major etiologic groups in AP were chronic alcoholism; postabdominal surgery; common duct stones; a small miscellaneous group including viral hepatitis, drug, and postpartum cases; and a large idiopathic group comprising patients with cholelithiasis, diabetes mellitus, and ischemia. The prevalence of established diabetes mellitus in the AP group was significantly higher than that observed in the autopsy control series, suggesting that this disease should be considered as an additional risk factor influencing survival in AP. Pulmonary complications, including pulmonary edema and congestion, appeared to be the most significant factor contributing to death and occurred even in those cases where the pancreatic damage appeared to be only moderate in extent. Emphasis placed on the early recognition and treatment of pulmonary edema in all cases of moderate and severe AP should contribute significantly to an increase in survival in this disease.
01 Jul 1985-Graphical Models \/graphical Models and Image Processing \/computer Vision, Graphics, and Image Processing
TL;DR: This paper addresses the subproblem of identifying corresponding points in the two images by processing groups of collinear connected edge points called segments using the "minimum differential disparity" criterion, and produces a sparse array disparity map of the analyzed scene.
Abstract: Images are 2-dimensional projections of 3-dimensional scenes, therefore depth recovery is a crucial problem in image understanding, with applications in passive navigation, cartography, surveillance, and industrial robotics. Stereo analysis provides a more direct quantitative depth evaluation than techniques such as shape from shading, and its being passive makes it more applicable than active range finding imagery by laser or radar. This paper addresses the subproblem of identifying corresponding points in the two images. The primitives we use are groups of collinear connected edge points called segments, and we base the correspondence on the "minimum differential disparity" criterion. The result of this processing is a sparse array disparity map of the analyzed scene. �9 1985 Academic Press, Inc.
TL;DR: The nature of the Fourier coefficients of a bent function is examined and a proof for the non-existence of bent functions over Jqm, m odd, is given for many values of q of the form q = 2 (mod 4).
TL;DR: Automatic programming consists not only of an automatic compiler, but also some Means of acquiring the high-level specification to be compiled, some means of determining that it is the intended specification, and some (interactive) means of translating this high- level specification into a lower-level one which can be automatically compiled.
Abstract: Automatic programming consists not only of an automatic compiler, but also some means of acquiring the high-level specification to be compiled, some means of determining that it is the intended specification, and some (interactive) means of translating this high-level specification into a lower-level one which can be automatically compiled.
TL;DR: The studies suggest that the diminished glucose tolerance of aging in normal weight men has multifactorial causality, and both beta-cell dysfunction and insulin resistance are important.
Abstract: To identify the pathogenic factors responsible for glucose intolerance of aging, we measured a variety of metabolic parameters, including insulin sensitivity and islet cell function, in 10 young (18−36 yr old) and 10 older (57−82 yr old) men of normal body weight. Subject groups had equivalent fasting plasma glucose and fat cell size values.Frequently sampled iv glucose tolerance tests were performed, and the data were analyzed by computer using the minimal model approach. This technique yields the following measures: S1, the insulin sensitivity index; φ1 and φ2, indices of first and second phase β-cell responsiveness to glucose; n, fractional insulin clearance, and SG, a measure of dynamic glucose disappearance dependent on glucose per se. We also evaluated β-cell responsiveness independently by measuring the plasma insulin response to arginine injections at three levels of glycemia and calculated potentiation slope from the relationship between the acute insulin response to arginine and the prestimulus ...
TL;DR: In this article, a pipeline structure is developed to realize the Massey-Omura multiplier in the finite field GF(2m) with the simple squaring property of the normal basis representation used together with this multiplier.
Abstract: Finite field arithmetic logic is central in the implementation of Reed-Solomon coders and in some cryptographic algorithms. There is a need for good multiplication and inversion algorithms that can be easily realized on VLSI chips. Massey and Omura [1] recently developed a new multiplication algorithm for Galois fields based on a normal basis representation. In this paper, a pipeline structure is developed to realize the Massey-Omura multiplier in the finite field GF(2m). With the simple squaring property of the normal basis representation used together with this multiplier, a pipeline architecture is also developed for computing inverse elements in GF(2m). The designs developed for the Massey-Omura multiplier and the computation of inverse elements are regular, simple, expandable, and therefore, naturally suitable for VLSI implementation.
TL;DR: The authors review some basic econo- metric methods that have been used to analyze such data sets and also indicate areas of research where panel data may be useful, but they do not discuss the use of panel data in their analysis.
Abstract: Observations for a number of cross-sectional units over time have become increasingly available. The new data sources enable econometricians to construct and test more complicated behavioral models than a single cross sectional or time series data set would allow. The availability of new data sources, however, also raises new issues. In this paper we review some basic econo- metric methods that have been used to analyze such data sets. We also indicate areas of research where panel data may be useful.
Emory University1, University of Miami2, Louisiana State University3, University of Minnesota4, Icahn School of Medicine at Mount Sinai5, University of Oklahoma6, University of Southern California7, Wills Eye Institute8, University of California, Los Angeles9, University of Iowa10, University of Texas at Austin11, Johns Hopkins University12, Tufts University13, University of Illinois at Urbana–Champaign14, Harvard University15, National Institutes of Health16
TL;DR: The Prospective Evaluation of Radial Keratotomy (PERK) study is a nine-center, self-controlled clinical trial of a standardized technique of radial keratotomy in 435 patients who had physiologic myopia with a preoperative refraction between -2.00 and -8.00 diopters.
TL;DR: The authors propose des criteres for deciding quelles differences de parametrage entre L1 and L2 doivent faire l'objet d'un enseignement explicite au moyen d'une grammaire pedagogique.
Abstract: Dans le cadre d'une didactique des langues etrangeres s'appuyant sur le concept de grammaire universelle l'A. propose des criteres pour decider quelles differences de parametrage entre L1 et L2 doivent faire l'objet d'un enseignement explicite au moyen d'une grammaire pedagogique
TL;DR: The “estrogen window hypothesis” of the etiology of breast cancer proposes that unopposed estrogen stimulation is the most favorable state for tumor induction and that normal postovulation progesterone secretion reduces susceptibility.
Abstract: The "estrogen window hypothesis" of the etiology of breast cancer proposes that unopposed estrogen stimulation is the most favorable state for tumor induction and that normal postovulation progesterone secretion reduces susceptibility. The authors believe that epidemiologic and experimental studies suggest rather that the opposite is true, i.e., that breast cancer risk is directly related to the cumulative number of regular ovulatory cycles. Unlike the endometrium, breast tissue mitotic activity is enhanced in the luteal phase of the menstrual cycle. Regular vigorous physical activity is one method of reducing the frequency of ovulatory cycles, and such exercise could markedly reduce a woman's lifetime risk of developing breast cancer.
TL;DR: Four cases of CMS in this series showed malignant change that was manifested as papillary adenocarcinoma, suggesting the need for complete surgical removal of these premalignant neoplasms.
Abstract: This study of 17 cases describes a homogeneous clinicopathologic group of tumors previously subsumed under the general term, hepatobiliary cystadenoma. This unique group of neoplasms that the authors have termed "cystadenoma with mesenchymal stroma" (CMS), occurred exclusively in women and showed two essential tumor components: a cyst lining of columnar to cuboidal, mucin secreting epithelium; and a moderately to densely cellular stroma composed of spindle (rarely oval) cells. The stromal element appeared similar to primitive mesenchyme, both on light and electron microscopic study, showing variable differentiation toward fibroblasts, smooth muscle, adipose tissue and capillaries. Cases of hepatobiliary "cystadenoma" in the literature with histology similar to CMS had similar sex and age incidences, while histologically dissimilar cases, lacking the mesenchymal stroma, had significantly different parameters. Four cases of CMS in this series showed malignant change that was manifested as papillary adenocarcinoma, suggesting the need for complete surgical removal of these premalignant neoplasms.
TL;DR: In this paper, the generic existence of general equilibria in incomplete markets was shown for fixed securities under smooth preference assumptions, except for an exceptional set of endowments and securities, a closed set of measure zero.
TL;DR: In this article, the Laughlin-Jastrow wave functions for incompressible fluid states of two-dimensional electrons at Landau-level filling factor 1/m were presented.
Abstract: We present Laughlin-Jastrow wave functions for incompressible fluid states of two-dimensional electrons at Landau-level filling factor 1/m that satisfy periodic boundary conditions. This rederivation of Laughlin-type states emphasizes that it is correct short-distance behavior of the wave functions rather than angular momentum considerations that lie behind the explanation of the fractional quantized effect.
TL;DR: In this article, the incompressible states of interacting two-dimensional electrons in a high magnetic field have been studied by finite-size calculations in the spherical geometry and the excitation spectrum at the Landau-level filling is described.
Abstract: The incompressible states of interacting two-dimensional electrons in a high magnetic field has been studied by finite-size calculations in the spherical geometry. The excitation spectrum at $\frac{1}{3}$ Landau-level filling is described, and the Laughlin-Jastrow character of the Coulomb-interaction ground state is unambiguously confirmed. As the interaction is varied, a transition to a gapless compressible state is observed.
TL;DR: This article argued that most of this research is confounded and that any resulting change in student learning or performance may be attributed to the uncontrolled effects of different instructional methods, content and/or novelty.
Abstract: Despite considerable evidence in research that computer-based instruction enhances student learning, an argument is presented that most of this research is confounded. Wherever computers are used to deliver instruction (including the teaching of programming languages), any resulting change in student learning or performance may be attributed to the uncontrolled effects of different instructional methods, content and/or novelty. The evidence for this confounding places the independent variables in most of these studies in doubt and diminishes the role of educational computing research in the development of instructional theory but not in instructional development or delivery.
TL;DR: A promising approach is shown to be provided by a refinement of the previously developed Protein Dipoles Langevin Dipoles model, which seems to represent consistently the microscopic dielectric of the protein and the surrounding water molecules.
TL;DR: A pipeline structure of a transform decoder similar to a systolic array is developed to decode Reed-Solomon (RS) codes, using a modified Euclidean algorithm for computing the error-locator polynomial.
Abstract: A pipeline structure of a transform decoder similar to a systolic array is developed to decode Reed-Solomon (RS) codes. An important ingredient of this design is a modified Euclidean algorithm for computing the error-locator polynomial. The computation of inverse field elements is completely avoided in this modification of Euclid's algorithm. The new decoder is regular and simple, and naturally suitable for VLSI implementation. An example illustrating both the pipeline and systolic array aspects of this decoder structure is given for a (15,9) RS code.