Showing papers by "University of Southern California published in 1980"

Optimal Capital Structure Under Corporate and Personal Taxation

Abstract: In this paper, a model of corporate leverage choice is formulated in which corporate and differential personal taxes exist and supply side adjustments by firms enter into the determination of equilibrium prices of debt and equity. The presence of corporate tax shield substitutes for debt such as accounting depreciation, depletion allowances, and investment tax credits is shown to imply a market equilibrium in which each firm has a unique interior optimum leverage decision (with or without leverage-related costs). The optimal leverage model yields a number of interesting predictions regarding cross-sectional and time-series properties of firms’ capital structures. Extant evidence bearing on these predictions is examined.

Continuum model for solitons in polyacetylene

Abstract: Solitons in a one-dimensional charge-density-wave system with half-filled electron bands are studied theoretically with a continuum model. This model is a continuum version of the one of polyacetylene recently considered by Su, Schrieffer, and Heeger (SSH). We have analyzed a variational solution with the displacement order parameter $\ensuremath{\Delta}(x)={\ensuremath{\Delta}}_{0}tanh(\frac{x}{\ensuremath{\xi}})$ with $\ensuremath{\xi}$ as a variational parameter. It is shown within the weak-coupling limit that the soliton (creation) energy takes the minimum value $(\frac{2}{\ensuremath{\pi}}){\ensuremath{\Delta}}_{0}$ with $\ensuremath{\xi}=\frac{\ensuremath{\hbar}{v}_{F}}{{\ensuremath{\Delta}}_{0}}$, where $2{\ensuremath{\Delta}}_{0}$ and ${v}_{F}$ are the dimerization energy gap and the Fermi velocity, respectively. These results agree quite well with numerical results by SSH for the discrete system. Furthermore, we show that the above $\ensuremath{\Delta}(x)$ is an exact solution of the self-consistent Bogoliubov-de Gennes equation.

Fibrolamellar carcinoma of the liver: a tumor of adolescents and young adults with distinctive clinico-pathologic features.

Abstract: Clinical and pathologic features of 23 patients with a distinctive histologic and clinical variant of hepatocellular carcinoma are summarized. The variant pattern of hepatocellular carcinoma is most common in the age group 5--35 years and occurs equally in either sex. The distinctive histologic features include 1) deeply eosinophilic neoplastic hepatocytes, many of which contain intracytoplasmic hyaline globules and distinct pale bodies and 2) fibrosis arranged in a lamellar fashion around the neoplastic hepatocytes. The histologic and gross features of the tumor have been confused both with focal nodular hyperplasia and with hepatocellular adenoma. The average survival of 32 months and the high operability rate of 48% far exceed the survival or operability for ordinary hepatocellular carcinoma. Thus, this tumor type must be recognized and considered separately when evaluating therapeutic results in large series of patients with hepatocellular carcinoma.

The Anticurvature Filing Method to Prepare the Curved Root Canal

Abstract: A method of preparation of the curved root canal is described by which endodontic filling material can be introduced with little risk of damage to the canal walls.

On the numerical solution of the discrete-time algebraic Riccati equation

Abstract: In this paper we shall present two new algorithms for solution of the diserete-time algebraic Riccati equation. These algorithms are related to Potter's and to Laub's methods, but are based on the solution of a generalized rather than an ordinary eigenvalue problem. The key feature of the new algorithms is that the system transition matrix need not be inverted. Thus, the numerical problems associated with an ill-conditioned transition matrix do not arise and, moreover, the algorithm is directly applicable to problems with a singular transition matrix. Such problems arise commonly in practice when a continuous-time system with time delays is sampled.

Regional Assignment of Genes for Human Esterase D and Retinoblastoma to Chromosome Band 13q14

Abstract: The expression of human esterase D was evaluated quantitatively and qualitatively in five persons with partial deletions or duplications of chromosome 13. The results showed that the locus of this enzyme is at band 13q14. Deletion of this same band in other subjects has been found previously to indicate a predisposition to the development of retinoblastoma, which was present in the four individuals in this study who had partial deletions of chromosome 13. Because of this close synteny, esterase D evaluation should aid in the diagnosis and genetic counseling of retinoblastoma.

Predictors of pronunciation accuracy: a reexamination

Abstract: Suter (1976) studied the correlations between English pronunciation accuracy scores and a battery of 20 variables for 61 normative speakers of English. Although he found that 12 of the 20 were significantly correlated with pronunciation accuracy, he did not attempt to assess the relative importance of the 12 in accounting for the criterion's variance. By limiting his analysis to a consideration of zero order correlations it was not possible to determine which of the significant predictors were true predictors of pronunciation accuracy in and of themselves and which were only significant predictors by virtue of their substantial correlations with other, more efficient predictors of pronunciation accuracy. In the present paper we apply more advanced techniques to the analysis of the predictors and conclude that only 4 variables, one of them a composite of 2 of Suter's predictors, are useful in accounting for the variability of subjects' pronunciation accuracy scores.

A Model of Human Occupation, Part 1. Conceptual Framework and Content

Abstract: This paper, the first of four, presents the structure and content of a model of occupation. The model is proposed as the first step in the development of paradigm of occupation for the field of occupational therapy and is designed for application in practice and research. It draws upon the theory of open systems to build a structural framework. Concepts relevant to human occupation are integrated into this framework. Subsequent papers will add concepts to the model and demonstrate its application in clinical practice.

Phase-conjugating mirror with continuous-wave gain

Abstract: We demonstrate a phase-conjugating mirror that has a continuous-wave power reflectivity much greater than unity (gain ~100). This mirror uses nonresonant degenerate four-wave mixing in a single crystal of barium titanate (BaTiO3). With our mirror we have (1) observed cw self-oscillation in an optical resonator formed by this mirror and a normal mirror, (2) demonstrated a cw oscillator that, in spite of phase-distorting material placed inside the resonator, will always emit a TEM00 mode, and (3) demonstrated an optical image amplifier. This mirror will work at any visible wavelength and with weak (milliwatt or weaker) pump beams.

Optimal Hankel-norm model reductions: Multivariable systems

Abstract: This paper represents a first attempt to derive a closed-form (Hankel-norm) optimal solution for multivariable system reduction problems. The basic idea is to extend the scalar ease approach in [5] to deal with the multivariable systems. The major contribution lies in the development of a minimal degree approximation (MDA) theorem and a computation algorithm. The main theorem describes a closed-form formulation for the optimal approximants, with the optimality verified by a complete error analysis. In deriving the main theorem, some useful singular value/vector properties associated with block-Hankel matrices are explored and a key extension theorem is also developed. Imbedded in the polynomial-theoretic derivation of the extension theorem is an efficient approximation algorithm. This algorithm consists of three steps: i) compute the minimal basis solution of a polynomial matrix equation; ii) solve an algebraic Riccati equation; and iii) find the partial fraction expansion of a rational matrix.

A Multivariate Model of the Term Structure

Abstract: THE TERM STRUCTURE OF interest rates has a very important role in economic theory. On the macroeconomic level the term structure serves as a key transmission link between the monetary and real sectors. On the microeconomic level the term structure not only serves as a tool for bond pricing, but the term structure also has an important role in the valuation of most financial claims. The concept of an equilibrium term structure under uncertainty was introduced by Merton [41] in 1973. Since then, Brennan and Schwartz [4, 5], Vasicek [51], Cox, Ingersoll, and Ross [11, 12], Richard [46], Long [33], and Dothan [16] have made important contributions to the theory of the term structure and equilibrium bond pricing. At this time, "closed form" solutions for the equilibrium term structure have been derived in several special, but important, cases where the term structure is generated from univariate or bivariate stochastic processes such as the elastic random walk, geometric random walk, and square root process. However, it is arguable that the term structure of interest rates is embedded in a large macroeconomic system. Hence, it is arguable that there are generally many economic factors which are related to the term structure. The primary objective of this paper is to develop a multivariate model of the term structure that can accommodate an arbitrary number of economic relationships. The model is of a general form and can be linked with many alternative macroeconomic systems. The major assumptions of the model to be developed are that the set of stochastic factors related to the term structure follow a joint elastic random walk, that the instantaneous riskless rate can be represented as a linear combination of the same factors, and that the market prices of risk (corresponding to the different factors) are, at most, time dependent. The resulting model of the term structure can be expressed in a form that is consistent with traditional notions of the term structure. Even with multiple factors, the term structure can always be expressed in a form characterized by expectations of future short-term rates plus a liquidity premium. We will restrict our attention to the pricing of default-free, purediscount bonds. While this special case is of interest in its own right, a model for pricing the default-free, pure-discount bond also plays an important role in pricing default-free coupon bonds, risky pure-discount bonds, and, as Cox, Ingersoll, and Ross show, the valuation of most financial claims [12].

Terminal accuracy of unexpectedly loaded rapid movements: evidence for a mass-spring mechanism in programming.

Abstract: Experiments using rapid-positioning movements in humans, where the subject is suddenly and unexpectedly provided with a change in the load characteristics of the limb, are described. Taken together, the pattern of results supports a mass-spring model of unidirectional limb action, where the limb moves to a position defined by the relative tensions in the agonist and antagonist. As well, various results provide evidence contrary to predictions from an impulse-timing viewpoint, where the motor program times the onset of impulses to the musculature, and against a feedback-processing viewpoint, where limb position is defined by minimizing positioning error indicated by feedback. The evidence suggests that the role of phasing in motor programs may be different for unidirectional actions on the one hand and multi-directional and/or multi-component actions on the other.

Formal Methods in Communication Protocol Design

Abstract: While early protocol design efforts had to rely largely on seat-of-the-pants methods, a variety of more rigorous techniques have been developed recently. This paper surveys the formal methods being applied to the problems of protocol specification, verification, and implementation. In the specification area, both the service that a protocol layer provides to its users and the internal operations of the entities that compose the layer must be defined. Verification then consists of a demonstration that the layer will meet its service specification and that each of the components is correctly implemented. Formal methods for accomplishing these tasks are discussed, including state transition models, program verification, symbolic execution, and design rules.

On the formation of nonlinear internal waves from the gravitational collapse of mixed regions in two and three dimensions

Abstract: The paper shows how trains of nonlinear, dispersive waves can be produced by allowing a region of mixed fluid, with a potential energy greater than its surroundings, to collapse towards its equilibrium state. The number of waves and their amplitude depend on the properties of the mixed region and of the ambient stratification. Three different geometrical configurations have been chosen and while each gives qualitatively the same results the form taken by the generated waves and the final equilibrium shape of the mixed region depend critically on these geometrical factors. The internal waves produced by this mechanism are related to waves produced in natural systems and it is shown that the observations support at least one possible explanation for those found in the oceans and planetary atmospheres.

Frame Synchronization Techniques

Abstract: A basic theory of frame synchronization for a singlechannel digital communication system is presented, along with extensive references to the literature. The design of frame markers is discussed and comparisons are drawn with more exotic techniques such as comma-free coding.

Hyper-responsivity to touch and vestibular stimuli as a predictor of positive response to sensory integration procedures by autistic children.

Abstract: Sensory processing disturbance in autistic children as a predictor of response to sensory integrative procedures was investigated. Ten autistic children, ages 3-1/2 to 13 years (mean, 7.4 years), were initially evaluated in regard to their hypo-, hyper-, or normal responsivity to visual, auditory, tactile, vestibular, proprioceptive, olfactory, and gustatory stimuli. After evaluation, each child received therapy that provided somatosensory and vestibular stimulation and elicited adaptive responses to these stimuli. At the end of one year of therapy, each child's progress was judged in relationship to that of the others, and the group was divided into the six best and the four poorest respondents. Stepwise discriminant analysis identified which initial test variables predicted good or poor responses to therapy. The good respondents showed tactile defensiveness, avoidance of movement, gravitational insecurity, and an orienting response to an air puff. Results suggest that children who registered sensory input but failed to modulate it responded better to therapy than those who were hypo-responsive or failed to orient to sensory input.