Showing papers by "University of Southern California published in 1969"

First-Order Raman Effect in Wurtzite-Type Crystals

Abstract: First-order Raman scattering from BeO, ZnO, ZnS, and CdS, all having the wurtzite structure (${C}_{6v}$), has been investigated. A discussion of the effects of the competition between the long-range electrostatic forces and the short-range forces due to anisotropy in the interatomic force constants on the vibrational spectrum has been included. A series of scattering diagrams are presented showing the geometrical arrangements necessary to observe all the $k=0$ phonons for this type of crystal structure. In BeO the ${E}_{2}$ mode was resolved from the transverse modes for the first time. The assignments of the ${E}_{2}$ modes in ZnS differ from previous investigations. From absolute intensity measurements, electro-optic coefficients for BeO, ZnO, and CdS were determined.

Inversion of multivariable linear systems

Abstract: A new algorithm for constructing an inverse of a multivariable linear dynamical system is presented. This algorithm, which is considerably more efficient than previous methods, also incorporates a relatively simple criterion for determining if an inverse system exists. New insight into the structure of a system inverse is gained by consideration of the inverse system representations resulting from the algorithm. A precise bound on the number of output differentiations required is obtained as well as a bound on the total number of integrators and differentiators necessary to realize the inverse. This latter bound is equal to the order of the original system. A further advantage of the algorithm and theory developed is that it is applicable to both time-invariant systems and time-variable systems which satisfy certain regularity conditions. One application is also given: a complete description of the set of initial states necessary and sufficient for a specified function to be the output of an invertible system.

Hadamard transform image coding

Abstract: The introduction of the fast Fourier transform algorithm has led to the development of the Fourier transform image coding technique whereby the two-dimensional Fourier transform of an image is transmitted over a channel rather than the image itself. This devlopement has further led to a related image coding technique in which an image is transformed by a Hadamard matrix operator. The Hadamard matrix is a square array of plus and minus ones whose rows and columns are orthogonal to one another. A high-speed computational algorithm, similar to the fast Fourier transform algorithm, which performs the Hadamard transformation has been developed. Since only real number additions and subtractions are required with the Hadamard transform, an order of magnitude speed advantage is possible compared to the complex number Fourier transform. Transmitting the Hadamard transform of an image rather than the spatial representation of the image provides a potential toleration to channel errors and the possibility of reduced bandwidth transmission.

Optimal recursive estimation with uncertain observation

Abstract: In classical estimation theory, the observation is always assumed to contain the signal to be estimated. In practice, certain observations, or sequences of observations, may contain noise alone, only the probability of occurrence of such cases being available to the estimator. An example is trajectory tracking where the signal is first detected and then the estimator is allowed to process it for tracking purposes. However, any detection decision is associated with a false-alarm probability, which is the probability that the detected signal contains only noise. Minimum mean-square estimators are derived for two different forms of this problem; 1) when it is possible that the observation at any sample time contains signal or is noise alone, independent of the situation at any other sample, and 2) when the entire sequence of observations contains signal or is only noise. The estimators derived are of recursive form. A simple example is given for illustration.

Normalized thermionic-field (T-F) emission in metal-semiconductor (Schottky) barriers

Abstract: Thermionic field (T-F) emission in uniformly doped metal-semiconductor (Schottky) barriers is analyzed to yield a normalized solution in closed form for the forward and reverse current (I)-voltage (V) relationship. A quasi one-dimensional approach and Maxwell-Boltzmann statistics are used. The formulation is expressed in terms of the ‘flat-band’ current density Im, the band bending Eb in the semiconductor depletion region, the materials constant E0 0 ( ln [ I I m ] = − E b E 0 0 at 0°K in the WKB approximation), and kT. The kinetic energy in units of Eb at which the maximum injection of carriers occurs in the semiconductor is shown to be cosh -2(kT/E0 0). Current flow in the temperature range between pure thermionic emission (kT/E0 0 ⪢ 1) and pure field emission (kT/E0 0 ⪡ 1) is analyzed and criteria for the transition of T-F emission to thermionic and to field emission are given. Computer solutions for the energy distribution of the injected carriers and for the normalized I-V characteristic are presented in graphical form. The results permit a straightforward calculation of the barrier height and the impurity concentration in the semiconductor from measurements of current density and differential resistance at a single applied bias. Application of these results explains a reported discrepancy between barrier heights deduced from photothreshold, C-V and I-V characteristics of WGaAs and AuGaAs Schottky barriers. A relatively constant excess temperature T0 (i.e., ln I ∝ (T + T0) when V ⪢ kT/q) is predicted in the case of large Eb/E0 0 in the higher kT/E0 0 range where thermionic emission is nearly predominant. I ∝ [exp(qV/kT) − 1] is shown to be a general expectation for all Schottky barriers near zero bias when the I-V characteristic is dominated by either thermionic or thermionic-field emission. The assumption of a Gaussian energy distribution of carriers leads to values for the slope of ln I vs. V in reasonable agreement with the results of the computer analysis, but the prediction of the absolute value of the current density deviates rapidly from the computed value when kT/E0 0 departs appreciably from unity. The Gaussian distribution also does not provide the smooth transition from T-F to thermionic emission characteristic of the computer solution.

Feedback control of a class of linear systems with jump parameters

Abstract: A class of linear systems are studied which are subject to sudden changes in parameter values An algorithm similar in form to Kushner's stochastic maximum principle is derived and the relationship between these algorithms discussed Systems in which the performance measure is quadratic are investigated in detail and a differential equation is derived which yields the optimal feedback gains

Cultivation in vitro of cells derived from a human rhabdomyosarcoma.

Abstract: Two cell lines were derived from an embryonal rhabdomyosarcoma. Cells of both lines grew as monolayers in liquid medium and formed colonies in agar medium. Each line consisted of 2 cytologic types resembling those of the original tumor—spindle cells and large multinucleated cells. No myofibrils could be demonstrated in the cells by light or by electron microscopy nor were virus particles detected. Cells of both lines probably contained myosin-ATPase and cells of line #2 contained myoglobin. Chromosome studies of cell line #1 revealed a stem-line of 51 chromosomes with a consistent karyotype. Three passages of cell line #2 were studied, and no evidence of a stem-line was noted. Chromosome counts ranged from 45 to 170, and consistent marker chromosomes in most cells were present in the form of large metacentrics in the C group.

The pigeon retina: quantitative aspects of the optic nerve and ganglion cell layer.

Abstract: Studies of electron micrographs of pigeon optic nerve showed numerous unmyelinated fibers (29% of total) and more than twice as many total fibers as previously reported. The 2.4 million axons had a mean diameter below 1 μ, close to the limit of resolution of light microscopy. This probably accounts for the large discrepancy between light and electron microscopic counts. Studies of retinal whole mounts showed an irregular distribution of cells in the ganglion cell layer including a minor posterior fovea and an area of increased density in the posterior-superior quadrant. Sample counts produced an estimate of over 4.8 million cell bodies in this layer. Cytological investigation indicated that over 85% of these cells were neuronal. The considerable excess of neuron cell bodies over axons in thought to be explained by the presence of large numbers of amacrine cells, cells which do not project axons into the optic nerve.

Bathymetry and Marine Geology of the Andaman Basin, and Tectonic Implications for Southeast Asia

Abstract: The Andaman Basin extends 1200 km from Burma to Sumatra and 650 km from the Malay Peninsula to the Andaman and Nicobar islands. The eastern portion of the basin is the Malay continental margin, a 250 km wide shelf which was cut into Malayan Paleozoic and Mesozoic rocks during the Early and Middle Tertiary. Subsequent folding and faulting modified the shelf, forming at least two major terraces, the Sumatra Shelf-basin and a 650 km long continental slope. Only a discontinuous veneer of Cenozoic sediments covers the continental margin, except for the Sumatra Shelf-basin, in which over 1 km of sediment has collected. The Andaman-Nicobar Ridge, western boundary of the basin, consists of an Upper Cretaceous serpentinite-ophiolite-radiolarite core overlain by Paleocene to Miocene graywackes and shales at least 3000 m thick. Between the ridge and the Malay continental margin lies the Central Andaman Trough, two elongate basaltic seamounts 220 km long, and a complex system of rift valleys and associated smaller volcanic seamounts. Maximum depths of 4400 m in the Andaman Basin are located in the major branch of the rift system, the 700 km long Nicobar Rift Valley which is the proper boundary between the Andaman-Nicobar Ridge and the Central Andaman Trough. Sediments in the Central Trough are 1.5 km thick, surprisingly thin in view of the huge Irrawaddy River sediment load which enters the north end of the basin and is trapped in the basin by surface currents. Large volumes of detritus which must have been produced during the Tertiary planation of the Malay shelf also cannot be accounted for by the minor Andaman Basin fill. The great thicknesses of pre-Late Miocene Tertiary sediments in the Andaman-Nicobar Ridge were derived from the northeast, an area now occupied by submerged youthful rift topography. It is concluded that the sediments derived from planation of the Malay shelf were shed into an adjacent Tertiary trough which was subsequently molded into the Andaman-Nicobar Ridge during Oligocene to Miocene time. The continental margin and the Andaman-Nicobar Ridge were then rifted apart by Late Miocene to Recent movements which formed the Andaman Basin as a rhombochasm. Geophysical data support this interpretation. The entire southeast Asian margin is marked by evidences of south-southeastward movement. Dextral strike-slip along Sumatra and sinistral strike-slip along the Philippine Rift are documented in the literature. The Java Trench along the front of the block has been interpreted as a product of thrusting. Parallelism of the Philippine Trench and Philippine Rift is understandable when the trench is interpreted as a rhombochasm.

Temperature of the Great Toe as an Indication of the Severity of Shock

Abstract: To establish whether changes in skin temperature would provide objective indication of the presence and severity of shock, hemodynamic and temperature measurements were obtained with the aid of a digital computer. Values obtained 3 hours after admission and 3 hours prior to discharge or death in 100 patients who presented with clinical signs of circulatory shock were analyzed. Temperature was measured with standard thermistor probes at five sites: the digital pad of the third finger, the large toe, the deltoid region of the arm, the lateral portion of the thigh, and the rectum. A significant correlation was demonstrated between the cardiac output and temperature of the toe (r = 0.71). Correlations were increased to 0.73 when corrections were made for changes in ambient temperature. A stepwise regression analysis provided no significant improvement in the predictability of cardiac index when the values for temperatures of other skin sites were included. Discriminant function analysis showed that an early m...

Curve Fitting by Segmented Straight Lines

Abstract: In many situations approximation of a set of data by a polygonal curve is more advantageous than approximation by a polynomial. If the join points of the polygonal curve are known, the problem is quite simple. If, however, they are to be chosen in some expeditious fashion, considerable numerical difficulties can arise if the curve-fitting problem is approached directly. In this paper it is shown that dynamic programming offers a simple direct approach to the determination of an optimal fit.

CONGENITAL ATRESIA AND STENOSIS OF THE DUODENUM A Review Compiled from the Members of the Surgical Section of the American Academy of Pediatrics

Abstract: A review is presented of 503 patients with congenital duodenal obstruction, compiled from 65 hospitals by the Surgical Section of the American Academy of Pediatrics. Four hundred eighty-seven patients underwent primary operative correction of the malformation with an overall early and late mortality rate of 36%. Complications from associated major congenital malformations were the leading cause of death. Many of these anomalies were potentially correctable had they been recognized and early treatment instituted. More than half of the infants with duodenal atresia had associated malformations. Thirty percent of the patients had Down9s syndrome. End-to-side or side-to-side duodenoduodenostomy or jejunostomy are the most commonly used operative techniques for duodenal atresia. General anesthesia and tube gastrostomy are usually employed.

The Function of Laryngeal Muscles in Regulating Fundamental Frequency and Intensity of Phonation

Abstract: The activity of three intrinsic laryngeal muscles in the regulation of fundamental frequency and intensity of phonation was studied electromyographically in six subjects. The regulatory mechanism o...

Personality Correlates of Opinion Leadership and Innovative Buying Behavior

Abstract: Relationship of standardized personality variables to opinion leadership and innovativeness is assessed using the California Psychological Inventory. In general, correlation and regression analysis...

Deficits in Sensory Integration in Educationally Handicapped Children

Abstract: Sixty-four neuromuscular, perceptual, and cognitive measurements made on 36 children with educational handicaps were subjected to Q-technique factor analysis. The two major patterns of deficits associated with low academic achievement were (1) auditory, language, and sequencing, and (2) postural and bilateral integration. Both of these syndromes were differentiated from syndromes of apraxia and tactile defensiveness.

Multiple-Phonon-Resonance Raman Effect in CdS

Abstract: Data are presented that tie the multiple-phonon-resonance Raman effect in CdS to the fluorescent-emission spectrum. The one-phonon selection rules differ from those of the ordinary Raman effect. A possible theoretical approach to this effect is suggested.

Venous Distensibility in Essential Hypertension

Abstract: Forearm venous distensibility was measured in patients with essential hypertension and in normotensive subjects in both the horizontal and 60° feet-down positions. The hypertensive patients exhibited a reduced venous distensibility compared with the normal subjects and, furthermore, showed minimal change on being tilted, whereas distensibility decreased 27% in the normal subjects. Treatment of the hypertensives with various antihypertensive drugs increased venous distensibility above pre-treatment values. These findings indicate that a state of increased venomotor tone exists in essential hypertension.

Richardson constant and tunneling effective mass for thermionic and thermionic-field emission in Schottky barrier diodes

Abstract: An appreciable difference is shown to be expected to exist between the experimentally measured Richardson constant and the ‘ideal’ Richardson constant associated with the flux of a Maxwellian distribution of carriers in a semiconductor. The equality which must exist between the Richardson constant for the forward and reverse characteristics is discussed. The semiconductor charge carrier energy—wave vector relationship rather than that of the metal is shown to be dominant because it controls the cone of acceptance for carriers incident on the barrier from the metal side. The effective mass in the ideal Richardson constant for T-F emission is shown to be the same as that for thermionic emission. This mass, which is associated with the E - k relationship transverse to the direction of current flow, can be considerably different from the tunneling effective mass which is the effective mass component in the direction of the current flow.

Near Fields of Truncated-Gaussian Apertures*

Abstract: Near-field irradiance patterns have been calculated for plane-wave gaussian beams truncated by circular apertures. The Kirchhoff diffraction integral was integrated numerically, using the small-angle Fresnel approximation. The effect of truncation was important when the aperture radius was less than twice the spot size of the gaussian beam.

A model for micellar emulsions

Abstract: A model is presented whereby oil external micellar emulsions (microemulsions) are treated as systems of swollen aqueous micelles in which Laplace and osmotic pressures are balanced. The model accounts for several of the features of these systems, and, in particular, for the ability of a micellar emulsion phase to be in equilibrium with an external aqueous electrolyte phase. The importance of obtaining equilibrium distribution data is stressed.