Showing papers by "University of California, Santa Barbara published in 1976"

Quasiparticle and phonon lifetimes in superconductors

Abstract: Low-energy quasiparticle scattering, recombination, and branch-mixing lifetimes and phonon pair-breaking and scattering lifetimes are calculated for superconductors. The quasiparticle calculations relate these lifetimes to the low-frequency behavior of ${\ensuremath{\alpha}}^{2}(\ensuremath{\Omega})F(\ensuremath{\Omega})$. Results are obtained using the low-frequency approximate form ${\ensuremath{\alpha}}^{2}(\ensuremath{\Omega})F(\ensuremath{\Omega})=b{\ensuremath{\Omega}}^{2}$, with $b$ determined from electron tunneling measurements. For the strong-coupling superconductors Pb and Hg, the full tunneling form for ${\ensuremath{\alpha}}^{2}(\ensuremath{\Omega})F(\ensuremath{\Omega})$ is used. The phonon lifetimes are shown to depend on ${\ensuremath{\alpha}}^{2}(\ensuremath{\Omega})$. Results are compared with experiment.

Distance measures for speech processing

Abstract: The properties and interrelationships among four measures of distance in speech processing are theoretically and experimentally discussed. The root mean square (rms) log spectral distance, cepstral distance, likelihood ratio (minimum residual principle or delta coding (DELCO) algorithm), and a cosh measure (based upon two nonsymmetrical likelihood ratios) are considered. It is shown that the cepstral measure bounds the rms log spectral measure from below, while the cosh measure bounds it from above. A simple nonlinear transformation of the likelihood ratio is shown to be highly correlated with the rms log spectral measure over expected ranges. Relationships between distance measure values and perception are also considered. The likelihood ratio, cepstral measure, and cosh measure are easily evaluated recursively from linear prediction filter coefficients, and each has a meaningful and interrelated frequency domain interpretation. Fortran programs are presented for computing the recursively evaluated distance measures.

1: Mastery Learning:

Abstract: Mastery learning is a philosophically based approach to the design of classroom environments that is currently creating controversy in the educational research and development community. Critics of mastery learning assert that mastery approaches to instruction are rigid, mechanistic, training strategies (Groff, 1974; Jaynes, 1975); that they can only give students the simple skills required to survive in a closed society (Cronbach, 1972); and that they do not appreciate the complexities of school learning (L. S. Bowen, 1975). Adherents of mastery approaches to instruction maintain that they are flexible, humanistic, educational strategies (Levin, 1974; Scriven, 1975); that they can provide students with the complex skills needed to prosper in an increasingly open society (H. M. Levin, 1975); and that they do take into account the realities of classroom life (Block & Anderson, 1975). In this chapter we propose to introduce the basic ideas and practices that have generated this controversy, as well as to review the associated research. We begin the chapter with a broad overview of mastery learning philosophy, theory, and practice. We then take a relatively microscopic view of four types or classes of research generated by these ideas and practices. In the final section we take a more macroscopic view of this research and ask what our findings may mean in practical, theoretical, and ideological terms.

Localized time-dependent perturbations in metals : formalism and simple examples

Abstract: Methods introduced by Keldysh to treat non-equilibrium problems are applied to strong, localized time-dependent perturbations in metals. After having introduced the formalism, we treat simple examples which are linked to the dynamics of atoms near surfaces : ionization probabilities of atoms leaving a metallic surface and friction coefficients of atoms near a metallic surface.

Stimulus control of self-destructive behavior in a psychotic child

Abstract: This study attempted to isolate some of the stimulus variables that controlled the self-destructive behavior of a psychotic child. In Experiment 1, the child was exposed to several demand and nondemand situations. In Experiment 2, the situation containing demands was modified so that demands now occurred in the context of a positive, ongoing interaction between the child and the adult therapist. The rates of self-destructive behavior underwent several orderly changes: (1) Rates were high in demand situations and low in nondemand and modified-demand situations; (2) rates decreased sharply when a stimulus correlated with the termination of demands was introduced; and (3) rates of self-destruction typically showed gradual increases within each of those sessions which contained only demands. These results were interpreted as suggesting that (1) self-destruction, under certain circumstances, may be conceptualized as an escape response which is negatively reinforced by the termination of a demand situation and (2) certain modifications of the social environment may provide discriminative stimuli for behaviors other than self-destruction, thereby decreasing this behavior.

A Mathematical Model of the Human Temperature Regulatory System - Transient Cold Exposure Response

Abstract: A mathematical model of the human temperature regulatory system which utilizes finite difference techniques and includes new anatomical and basal physiological information, with more detail than previous models, is presented. A cold stress control system which includes both a feedback signal based on head core temperature and feedforward signals based on the skin temperature and the skin heat flux is postulated. Model and direct experimental results (seven temperatures, cardiac output, metabolism, and arm blood flow) are compared for a transient cold exposure. The substantial agreement found suggests that the skin heat flux could be an important input to the temperature regulatory system.

Pb and Sr isotopic data bearing on the origin of volcanic rocks from the Mariana island-arc system

Abstract: Analyses of the isotopic composition of Pb in (1) western Pacific Ocean sediments [Jurassic(?) to Pleistocene in age, including clays and biogenic oozes], (2) Pacific Ocean basaltic rocks, (3) Mariana frontal arc volcanic rocks (Eocene to Miocene), and (4) Mariana active arc volcanic rocks [Pliocene (?) to Holocene] indicate that Pacific Ocean sediments could not have been a significant component of the source material for the Mariana arc volcanic rocks. Calculations involving the average concentrations and isotopic compositions of Pb in oceanic sediments, sea-floor basaltic rocks, and the Mariana arc volcanic rocks suggest that the sediment component must have been less than 1 percent of this source material. The Pb isotopic compositions of the Mariana arc volcanic rocks lie, within experimental error, along the trend of available Pacific Ocean basalt analyses in versus 207 Pb/ 204 Pb versus 206 Pb/ 204 Pb and 208 Pb/ 204 Pb versus 206 Pb/ 204 Pb diagrams. Isotopic analyses of Pb in Pacific Ocean sediments do not lie along this trend; they have higher 207 Pb/ 204 Pb and 208 Pb/ 204 Pb values for comparable 206 Pb/ 204 Pb ratios. Clayey sediments generally have higher 208 Pb/ 204 Pb and 207 Pb/ 204 Pb ratios than biogenic oozes regardless of the age of the sediment. Comparison of combined Sr and Pb isotopic analyses for (1) mantle-derived materials erupted through oceanic crust, (2) altered ocean-floor basaltic rocks, and (3) volcanic rocks from oceanic island arcs suggests that the Mariana arc volcanic rocks were derived, at least in part, from altered Pacific lithosphere subducted beneath the Mariana arc. Unaltered basalts from the Mariana inter-arc basin (Mariana Trough) have Pb and Sr isotopic compositions that are very similar to those reported for some Hawaiian volcanic rocks but distinct from Mariana active and frontal arc compositions. These observations, in addition to existing major-and trace-element data, support a mantle origin for the interarc basin volcanic rocks. Dacites dredged from the Mariana remnant arc (South Honshu Ridge) have Pb isotopic compositions that are within experimental error of the active-arc analyses, consistent with a genetic relation.

Orbital Resonances in the Solar System

Abstract: Orbital resonances are defined as any system of two or more satellites (including planets) orbiting the same primary and whose orbital mean motions are in a ratio of small whole numbers. Known orbital resonances in the solar system are identified, including those involving Jupiter's satellites Io, Europa, and Ganymede; Saturn's satellites Mimas and Tethys, Enceladus and Dione, and Titan and Hyperion; Saturn's ring gaps and Mimas; various asteroids and Jupiter; and the planets Neptune and Pluto. The stability of orbital resonances is examined, the origin of orbital commensurabilities is investigated, and a simple model of the simplest kind of eccentricity-type resonance is outlined. A method is described by which tides carry a noncommensurate pair of satellites into a stable libration, and current ideas concerning the formation of the gaps in Saturn's rings and the asteroid belt are discussed. Various approaches to the analysis of orbital resonances are laid out and illustrated. Three two-body commensurabilities in Saturn's satellite system are analyzed numerically.

Mathematics and sex

Abstract: (1976). Mathematics and Sex. The American Mathematical Monthly: Vol. 83, No. 8, pp. 595-614.

A framework for social motives.

Abstract: In any complex social system, the choices of a single person often affect the outcomes of others. When one takes the others' outcomes into account in making choices, we say one is manifesting a social motive. We assume that an individual's social motives are manifested in his social preferences. Any theory of decision or choice requires information about preferences, and so in addition to attempting to clarify definitions of social motives, this study provides a framework for theories of social decision. To begin, we establish operational definitions for the motives of self-interest, self-sacrifice, altruism, aggression, cooperation, and competition. These definitions are based on the simple operators of summations and differences. Then we examine some supplementary motives involving proportionality operators. Next we eliminate the assumption that an individual has a fixed preference structure which is applied to all social choices. This leads to a focus on the specific distribution of consequences resulting in conditional motives; conditional motives reflect varying basic motives depending on whether the individual is ahead or behind. All these motives are represented graphically, and a correspondence matrix is given to illustrate the interrelationships among the motives. Finally, we investigate combinations of the motives since such composites are less restrictive and can better account for observed behavior. Linear combinations are interesting but still too restrictive. Conjunctive, disjunctive and lexicographic combinations offer useful possibilities for characterizing particular social motives. Complex combinations involving general nonlinear forms arise and some representative forms are explored.

Ergotism: the satan loosed in Salem?

Abstract: Purpose To compare rates of symptomatic intracranial hemorrhage (SICH) and good clinical outcome at 90 days in patients with ischemic strokes from anterior circulation emergent large vessel occlusions (ELVO) treated with mechanical thrombectomy using either Solumbra or A Direct Aspiration first-Pass Thrombectomy (ADAPT) techniques. Methods We compared clinical characteristics, procedural variables, and clinical outcomes in patients with anterior circulation ELVOs treated with mechanical thrombectomy using either a Solumbra or ADAPT technique at our institution over a 38-month period. SICH was defined using the SITS-MOST criteria. A good clinical outcome was defined as a modified Rankin Scale score of 0–2 at 90 days. Results One hundred patients were included, 55 in the Solumbra group and 45 in the ADAPT group. Patients in the ADAPT group had higher National Institutes of Health Stroke Scale (NIHSS) (19.2 vs 16.8, p=0.02) and a higher proportion of internal carotid artery terminus thrombi (42.2% vs 20%, p=0.03) than patients in the Solumbra group. Patients in the ADAPT group had a trend toward a lower rate of SICH than patients in the Solumbra group (2.2% vs 12.7%, p=0.07). Patients in the ADAPT group had a significantly higher rate of good clinical outcome at 90 days than patients in the Solumbra group (55.6% vs 30.9%, p=0.015). Use of the ADAPT technique (OR 6 (95% CI 1.0 to 31.2), p=0.049) was an independent predictor of a good clinical outcome at 90 days in our cohort. Conclusions In our cohort, the ADAPT technique was associated with significantly higher good clinical outcomes at 90 days in patients with acute ischemic stroke due to anterior circulation ELVOs treated with mechanical thrombectomy.

The simultaneous on-line estimation of parameters and states in linear systems

Abstract: The practical implementation of adaptive controllers using minicomputers requires algorithms which are both numerically economical and robust. The problem of combined state and parameter estimation for adaptive controllers was originally posed as a nonlinear filtering problem. The only known nonlinear filter which can be practically implemented on a small computer is the extended Kalman filter. The extended Kalman filter, however, often diverges, thus, there is a need for economical, robust parameter-state estimators. A simple suboptimal parameter and state estimator is presented which fills this need. The filter is based on a particular canonical form for the state-space equations of a linear system which allows the parameters and states to be estimated separately using two linear estimators. If an innovations model is used, the steady-state Kalman filter gains can be estimated and thus, during steady-state operation, the estimates of the states can be easily obtained. Numerical exampies are presented which demonstrate the increased robustness and speed of the proposed linear estimator over the extended Kalman filter.

Chapter 13 Induction and Isolation of Mutants in Tetrabymena

Abstract: Publisher Summary This chapter describes induction and isolation of mutants in Tetrahymena . Tetrahymena pyriformis is a unicellular animal well suited to studies of cell and molecular biology. It can be grown in pure culture to high concentrations, in practically unlimited volumes, with a remarkably short-vegetative doubling time (down to 2 hours under favorable conditions) and is thus extremely useful for the production and purification of cellular organelles and macromolecules. It is also well suited for genetic studies, having a diploid germ line with only five pairs of chromosomes, which are transmitted during conjugation according to the standard rules of the Mendelian genetics. The cells can be cloned efficiently, and conjugation is under precise experimental control. Clones can be readily frozen and indefinitely stored under liquid nitrogen. The chapter covers the methods used in the induction and isolation of Tetrahymena mutants, including (1) recent technical advances in handling the large numbers of cells required to isolate rare mutants and (2) recently developed strategies designed to increase the frequency of mutants. The chapter also describes elements of the Tetrahymena genetics, genetic analysis, and uses of the mutants. Design of conditions for isolating desired mutants is discussed in the chapter along with the limitations of the use of mutants.

Theory of vibrational mode intensities in inelastic electron tunneling spectroscopy

Abstract: We use a transfer-Hamiltonian formalism to develop a theory for the intensity of vibrational modes in inelastic electron tunneling spectroscopy (IETS) of organic molecules in metal-insulator-metal junctions. The initial and final electron states are localized on opposite sides of the insulating barier and are described by Wentzel-Kramers-Brillouin (WKB) wave functions. The interaction potential between the tunneling electron and the vibrating molecule is a sum of Coulomb potentials; each element in the sum corresponding to a partial charge localized on an atom in the molecule. The theory predicts properly the magnitudes of the integrated intensities in IETS as well as the ratio of intensities for opposite bias voltages. It also predicts that Raman-active modes should be comparable in intensity to infrared modes, even neglecting bond polarizabilities, and that modes forbidden to optical spectroscopies may be observable in IETS. We further describe how the orientation of the doped molecules on the surface can be inferred from IETS intensities.

Quantization and bit allocation in speech processing

Abstract: The topic of quantization and bit allocation in speech processing is studied using an L 2 norm. Closed-form expressions are derived for the root mean square (rms) spectral deviation due to variations in one, two, or multiple parameters. For one-parameter variation, the reflection coefficients, log area ratios, and inverse sine coefficients are studied. It is shown that, depending upon the criterion chosen, either log area ratios or inverse sine quantization can be viewed as optimal. From a practical point of view, it is shown experimentally that very little difference exists among the various quantization methods beyond the second coefficient. Two-parameter variations are studied in terms of formant frequency and bandwidth movement and in terms of a two-pair quantization scheme. A lower bound on the number of quantization levels required to satisfy a given maximum spectral deviation is derived along with the two-pair quantization scheme which approximately satisfies the bound. It is shown theoretically that the two-pair quantization scheme has a 10-bit superiority over other above-mentioned quantization schemes in the sense of theoretically assuring that a maximum overall log spectral deviation will not be exceeded.

Some detrimental effects of using extra stimuli to guide learning in normal and autistic children.

Abstract: This study was designed to assess the effectiveness of using prompts (extra "guiding" stimuli) for teaching normal and autistic children. One group of normal children was pretrained on a color discrimination. Later, the colors were used as prompts (presented simultaneously with new training stimuli) to teach four new discriminations. Another group of normal children was trained on the same discriminations with a trial-and-error procedure (i.e., no prompting). A third group consisted of autistic children who were trained on these discriminations using the prompt procedure. Analyses of the results showed the following. (1) The trial-and-error group of normal children acquired more discriminations than the prompt group of normal children. (2) A comparison of the two prompt groups showed that the autistics failed to transfer from the prompt cue to the training cue more often than the normal children; rather, the autistics generally continued responding to the faded color cue. (3) Autistic and normal children who failed to acquire the discriminations when trained with a prompt procedure did acquire these discriminations when no prompt was used. That is, the results suggest that the presentation of an extra guiding stimulus was detrimental to the acquisition of training discriminations for all subjects, and particularly so far autistic children. Therefore, the common practice of providing extra guiding stimuli in proportion to the severity of the learning disorder may actually be harmful to the learning of new skills. Implications of these results for future research are discussed.

Competitive Interactions and the Species Diversity of Corals

Abstract: The species diversity of a coral reef community is affected by many factors. If we consider only sessile organisms, for example plants or aquatic animals such as sponges, corals, etc., competition for space is obviously an important factor. On a small area of hard substrate with very little spatial variation in local physical conditions, one might expect that a single species would be superior to all others in competition and would eliminate them and eventually cover the surface.

Wear striations on the incisors of ceropithecid monkeys as an index of diet and habitat preference

Abstract: Wear striations on the incisors of Old World monkeys were examined in order to determine associations between the distributions of striations, diet, and habitat preference. Significant differences exist between the Cercopithe-cinae and the Colobinae in respect to the orientation of incisor wear striations. In the Colobinae striations are oriented in a predominantly mesiodistal direction. In the Cercopithecinae striations usually have a labiolingual orientation. Comparisons of terrestrial and arboreal genera indicate that significant differences exist between the two groups in respect to the density of striations on the oc-clusal wear facets of maxillary central incisors. Arboreal and terrestrial monkeys also differ in the frequency of individual incisor wear facets completely devoid of wear striations.

Does Mercury have a molten core

Abstract: A feasible nonseismic observational experiment is proposed for determining the existence and extent of a conducting molten core within Mercury. This experiment would utilize the effects of a liquid core on the dynamics of Mercury's rotation; two necessary conditions for performing it are that the core must not follow the mantle's forced librations in longitude but must follow the mantle on the timescale of the 250,000-yr precession. A method is developed by assuming these conditions to be satisfied, and bounds are established on the core viscosity for which they are satisfied. It is shown that the value of the ratio of the moment of inertia of the mantle to the largest principal moment of inertia of the entire planet would indicate whether the core is most probably solid, partially fluid, or entirely fluid. Techniques are suggested for determining the unknowns required to compute the necessary ratio.

A method for the deletion of restriction sites in bacterial plasmid deoxyribonucleic acid.

Abstract: A general method has been developed for the deletion of restriction endonuclease sites in bacterial plasmid DNA. The procedure involves partial digestion of the covalently closed circular plasmid DNA with an appropriate restriction endonuclease under conditions which allow accumulation of unit-length linear DNA molecules, controlled digestion of the exposed 5′ ends with the λ 5′-exonuclease, and in vivo recircularization of the resulting linear DNA in a bacterial host cell. The method has been used for the deletion of one of the two EcoRI sites in the plasmid pML2 (colE1-Km). Two of the resulting plasmids, pCR1 and pCR11, have a single EcoRI cleavage site, but retain genetic determinants specifying resistance to colicin E1 and kanamycin, and thus may be useful as vectors for the cloning and amplification of DNA in bacteria.