Showing papers by "University of California, Santa Barbara published in 1979"

Effects of large organic material on channel form and fluvial processes

Abstract: \ SUMMARY Stream channel development in forested areas is profoundly influenced by large organic debris (logs, limbs and rootwads greater than 10 cm in diameter) in the channels. In low gradient meandering streams large organic debris enters the channel through bank erosion , mass wasting, blowdown, and collapse of trees due to ice loading. In small streams large organic debris may locally influence channel morphology and sediment transport processes because the stream may not have the competency to redistribute the debris. In larger streams flowing water may move large organic debris, concentrating it into distinct accumulations . (debris jams). Organic debris may greatly affect channel form and process by: increasing or decreasing stabilty of stream banks; influencing development of midchannel bars and short braided reaches; and faciltating, with other favourable circumstances, development of meander cutoffs. In steep gradient mountain streams organic debris may enter the channel by all the processes mentioned for low gradient streams. In addition, considerable debris may also enter the channel by way of debris avalanches or debris torrents. In small to intermediate size mountain streams with steep valley walls and little or no floodplain or flat valley floor, the effects of large organic debris on the fluvial processes and channel form may be very significant. Debris jams may locally accelerate or retard channel bed and bank erosion and/or deposition; create sites for significant sediment storage; and produce a stepped channel profile, herein referred to as ' organic stepping , which provides for variable channel morphology and flow conditions. The effed of live or dead trees anchored by rootwads into the stream bank may not only greatly retard bank erosion but also influence channel width and the development of small scour holes along the channel beneath tree roots. Once trees fall into the stream , their influence on the channel form and process may be quite different than when they were defending the banks , and, depending on thesize of the debris , size of the stream , and many other factors, their effects range from insignificant to very important.

Smooth Pycnophylactic Interpolation for Geographical Regions

Abstract: Census enumerations are usually packaged in irregularly shaped geographical regions. Interior values can be interpolated for such regions, without specification of “control points,” by using an analogy to elliptical partial differential equations. A solution procedure is suggested, using finite difference methods with classical boundary conditions. In order to estimate densities, an additional nonnegativity condition is required. Smooth contour maps, which satisfy the volume preserving and nonnegativity constraints, illustrate the method using actual geographical data. It is suggested that the procedure may be used to convert observations from one bureaucratic partitioning of a geographical area to another.

Melting of Io by Tidal Dissipation

Abstract: The dissipation of tidal energy in Jupiter's satellite Io is likely to have melted a major fraction of the mass. Consequences of a largely molten interior may be evident in pictures of Io's surface returned by Voyager I.

Reconstructive tomography and applications to ultrasonics

Abstract: Computer technology has brought about a revolution in radiology. By combining the computer with X rays it is possible (in principle) to obtain tomographic images of any cross section in the human body. These techniques are now used for medical diagnosis in all the major hospitals of the world. But X rays are not the only kind of radiation for which computer-assisted tomography is feasible. Microwaves, electron beams, ultrasound, fast subatomic particles from accelerators, gamma rays from such sources as positron annihilation, and even magnetic fields can also be used. This paper is mainly concerned with ultrasound. Acoustic energy can often give a view of a cross section not available with X rays or other types of radiation. A mapping of acoustic and elastic discontinuities can be expected to give a basically different pattern than a mapping of X-ray absorption and scattering coefficients. Several methods of ultrasonic tomography are discussed including methods based on geometric optics and a Doppler-oriented approach. A major portion of the paper is concerned with introducing ways to take into account diffraction effects. Because of the wavelength differences, these effects are far more important for ultrasound than for X rays.

Syntactic/semantic interactions in programmer behavior: A model and experimental results

Abstract: This paper presents a cognitive framework for describing behaviors involved in program composition, comprehension, debugging, modification, and the acquisition of new programming concepts, skills, and knowledge. An information processing model is presented which includes a long-term store of semantic and syntactic knowledge, and a working memory in which problem solutions are constructed. New experimental evidence is presented to support the model of syntactic/semantic interaction.

γ-Aminobutyric Acid, a Neurotransmitter, Induces Planktonic Abalone Larvae to Settle and Begin Metamorphosis

Abstract: gamma-Aminobutyric acid (a simple amino acid and potent neurotransmitter in human brain and other tissues of higher animals) and certain of its congeners rapidly and synchronously induce planktonic larvae of the red abalone, Haliotis rufescens, to settle and commence behavioral and developmental metamorphosis. These naturally occurring inducers of algal origin apparently are responsible, in part, for the substrate-specific recruitment, induction of settling, and the onset of metamorphosis of abalone and other planktonic larvae upon specific algae which provide naturally favorable habitats for the young of these species in coastal waters. These observations provide a convenient experimental model for further analysis of the basic molecular mechanisms by which environmental and endogenous factors control the recruitment and development of planktonic larvae. Halogenated organic pesticides significantly interfere with larval settling, as quantified in a new bioassay based upon these findings.

Least squares glottal inverse filtering from the acoustic speech waveform

Abstract: Covariance analysis as a least squares approach for accurately performing glottal inverse filtering from the acoustic speech waveform is discussed. Best results are obtained by situating the analysis window within a stable closed glottis interval. Based on a linear model of speech production, it is shown that both the moment of glottal closure and opening can be determined from the normalized total squared error with proper choices of analysis window length and filter order. Results from actual speech are presented to illustrate the technique.

A Cognitive -Attributional Analysis of Stereotyping1

Abstract: Publisher Summary The chapter summarizes evidence indicating that cognitive biases can result in the perceiver holding stereotypic conceptions of social groups; that is, cognitive mechanisms alone may be the foundation of perceived intergroup differences. The chapter reveals the significant role of cognitive mechanisms at several possible points in the overall attribution process. The cognitive orientation presented in the chapter provides a new perspective for understanding why stereotypes are so persistent over time and resistant to change. Stereotypes, as cognitive schemas, can influence the encoding, interpretation, retention, and retrieval of subsequently obtained information about members of stereotyped groups, along with the perceiver's causal attributions regarding the target person's behavior. The chapter discusses a number of cognitive biases, which have bearing on the stereotyping process. One of the primary challenges faced by researches in this field is the question of how these biases can be altered or modified in cases where they yield consequences hat reduce, rather than facilitate effectiveness. The chapter considers the question of what behavioral consequences result from the perceiver holding a stereotype of a particular group.

Reaction Kinetics in Aqueous Surfactant Solutions

Abstract: During the past two decades there has been considerable interest in reactions which can be carried out at interfaces. One aspect of this work has involved the catalysis or inhibition of solution reactions by submicroscopic entities such as polyelectrolytes, cyclodextrins, or micelles. (Work in these areas is discussed in Ref. 1, which provides a comprehensive summary of micellar catalysis and inhibition up to 1974.) These reactions often occur at the interface between the solvent, which is usually water or an aqueous organic mixture, and the submicroscopic particle or aggregate. There has been the hope that these interfacial systems would mimic enzymic catalysts, and at the least give some evidence on the factors which govern this catalysis, and many of the reactions studied, e.g., de-acylation and dephosphorylatum, are of biological interest [2–6].

Depth-related enzymic activities in muscle, brain and heart of deep-living pelagic marine teleosts

Abstract: The activities [units-1 wet weight tissue] of lactate dehydrogenase (LDH), pyruvate kinase (PK), malate dehydrogenase (MDH) and isocitrate dehydrogenase (IDH) in white skeletal muscle, brain and heart of 24 pelagic teleost fishes were determined. In addition, for several of the foregoing species, citrate synthase (CS) activities were examined in white skeletal muscle. In muscle, the activities of all these enzymes decrease exponentially with increasing minimum depth of occurrence of the species; this decrease closely parallels the decrease in respiratory rate found previously for these same species. The decline in enzymic activity with increasing minimum depth of occurrence is much greater than the decline in body protein content of the whole fishes, suggesting a disproportionately rapid fall in enzyme concentration in comparison to contractile and structural protein concentrations. The similar reductions in activities of both glycolytic (LDH and PK) and citric acid cycle (CS, MDH and IDH) enzymes with depth indicate that both standard and active metabolisms of deeper-dwelling species are reduced relative to shallower-dwelling forms. There is no suggestion of increased anaerobic capacity with depth or in relation to species, occurrence in the oxygen minimum layer. In brain and heart, there is no significant decrease in enzymic activity with increasing minimum depth of occurrence. These two tissues have similar capacities for metabolism in most fishes, when comparisons are based on enzymic activity per gram wet weight of tissue.

Rational Expectations and Learning from Experience

Abstract: I. Introduction, 47.—II. The model, 49.—III. Conclusions, 54. The universal form of conscious behavior is thus action designed to change a future situation inferred from a present one. It involves perception and, in addition, twofold inference. We must infer what the future situation would have been without our interference, and what change will be wrought in it by our action. Fortunately or unfortunately, none of these processes is infallible, or indeed ever accurate and complete (Knight, 1921, pp. 201–02). The correspondence of expectations that makes it possible for all parties to achieve what they are striving for is in fact brought about by a process of learning by trial and error which must involve a constant disappointment of some expectations. The process of adaptation operates, as do the adjustments of any self-organizing system, by what cybernetics has taught us to call negative feedback: responses to the differences between the expected and the actual results of actions so that these differences will be reduced (Hayek, 1976, pp. 124–25).

Quantum effects in the early universe. I. Influence of trace anomalies on homogeneous, isotropic, classical geometries

Abstract: The use of the effective-action method to calculate quantum effects in the early universe is described. An application is made to the calculation of the effect of one-loop contributions of conformally invariant matter fields on the evolution of homogeneous, isotropic, spatially flat classical geometries containing classical radiation.

Is there liquid water on Europa

Abstract: It is possible that tidal dissipation in an ice crust on Europa preserved a liquid water layer beneath it, provided that the three-body orbital resonance for Io, Europa, and Ganymede is ancient. The liquid water layer could be a continuing source of the observed surface frost. If Europa's water mantle were ever completely frozen, heating by tidal dissipation would not exceed that produced by radioactive elements, and the mantle would remain frozen.

Twenty years of research on advance organizers: assimilation theory is still the best predictor of results

Abstract: Forty-four published research studies involving advance organizers were reviewed. Twenty-seven studies included an advance organizer vs. a control group (standard advance organizer study) and 17 studies included an advance organizer vs. a post organizer group (modified advance organizer study). Results of the studies were compared to the predictions of several theories. In addition, four specific predictions of assimilation theory were evaluated: that advance organizers should have a stronger effect for poorly organized text than for well organized text, that advance organizers should have a stronger positive effect for learners lacking prerequisite knowledge, that advance organizers should have a stronger effect for learners lacking prerequisite abilities, and that advance organizers should have an especially strong effect on measures of transfer rather than retention.

Fragmentation in a rotating protostar - A comparison of two three-dimensional computer codes

Abstract: The collapse of an isothermal protostellar cloud with pressure, gravity, and rotation included is followed with two independent computer codes. For the initial condition, a nonaxisymmetric perturbation of mode m = 2 and 50% amplitude is introduced into a cloud of 1 solar mass with a mean density of 1.44 x 10 to the -17g/cu cm and a uniform angular velocity of 1.6 x 10 to the -12 rad/sec. The collapse is followed through an increase in density of over four orders of magnitude to the point where a binary protostar forms. The agreement between the results of the two calculations is good.

Coral Reef Growth in the Galápagos: Limitation by Sea Urchins

Abstract: The regular echinoid Eucidaris thouarsii is a conspicuous omnivore on coral bottoms in the Galapagos. Unlike Eucidaris in Panama and mainland Ecuador, Galapagos Eucidaris are large and abundant and graze heavily in the open on live corals day and night. These differences are probably due in large part to more intense predation by fishes on mainland compared with island urchin populations. An assessment of coral growth versus coral attrition from grazing shows that Eucidaris interferes with the establishment of pocilloporid reef frame and therefore reduces reef growth in the Galapagos.

Oxygen consumption rates of midwater fishes as a function of depth of occureence

Abstract: Oxygen consumption was measured in 23 pelagic fish species whose minimum dept of occureence ranged from zero to 1,000 m. Weight-specific respiratory rate declined rapidly with increasing minimum depth of occureence. The decrease is partially due to environmental and compositional factors that covary with depth. Decreasing temperature accounts for 2% and the increased water content of deeper living species accounts for 30% of the observed decline. Other factors that might contribute to the decreasing oxygen consumption rate either had no significant effect (size, ash-free dry weight) or were considered to have small effects on the basis of existing evidence (pressure). The unexplained remainder of the decline appears to be an inherent characteristics of deeper living species that may be thought of as a decrease in aerobic metabolism per unit of muscle.

Models of the Significance of Interlocking Corporate Directorates

Abstract: . Four different models explaining the significance of the patterns of interlocking directorates in the American economy are delineated and examined to discover a few of the behavioral predictions inherent in each. Empirical tests are employed to examine the general pattern of replacement of interlocking relationships between the largest American firms when ended through the death of an outside director. Another test employed is to examine the stability of interlock patterns over time. From the results it is concluded that interlocking directorates do not generally represent evidence of close interconnections between specific corporations but do connect some stable, city-based groups.

Existence of a negative Poisson ratio in fcc crystals

Abstract: The Poisson ratios along two principal crystal directions normal to a [110] uniaxial load are generally of opposite algebraic sign for fcc crystals. A theoretical basis for this behavior is revealed.

Temporal variability of phytoplankton in tropical lakes.

Abstract: Temporal variability of ecological systems continues to receive theoretical and empirical attention but remains inadequately documented at low latitudes. Results of my comparative investigation of photosynthetic rates of phytoplankton in 6 equatiorial African lakes and similar information from 20 South American, Asian and African lakes studied by others provide the data for an assessment of the range of seasonal variability (expressed as coefficients of variation, CV) among tropical lakes. Sampling intervals varied from 1 week to 3 months and usually spanned at least one year. Within Africa the coefficient of variation ranged from 15% to 61%, and among all the lakes the coefficient of variation ranged from 15% to 86%. The Spearman rank correlation coefficient of the CV's of photosynthesis versus latitude is 0.24 and is not significant at the 0.05 level. Coefficients of variation of photosynthetic rates of phytoplankton in a diverse set of 45 temperate and arctic lakes ranged from 29% to 155% and were significantly different from the set of 26 tropical lakes by the Mann-Whitney U test. When all 71 lakes are compared, the Spearman rank correlation coefficient of CV's of photosynthesis versus latitude is 0.71 and is significant at the 0.0005 level. Three temporal patterns were recognized among tropical lakes. Most tropical lakes exhibit pronounced seasonal fluctuations that usually correspond with variations in rainfall, river discharges or vertical mixing. A second pattern occurs in lakes with muted fluctuations (coefficient of variation less than 20%) in which diel changes often exceed month to month changes. A third pattern is distinguished by an abrupt change from one persistent algal assemblage (i.e., extant for at least 10 generations) and level of photosynthetic activity to another persistent condition.

Homogeneous catalysis of the water gas shift reaction by ruthenium and other metal carbonyls. Studies in alkaline solutions

Abstract: Homogeneous catalysis of the water gas shift reaction (H/sub 2/O + CO reversible H/sub 2/ + CO/sub 2/) has been demonstrated for a number of metal carbonyl complexes under alkaline conditions. Characterization of the catalysts based on ruthenium carbonyl in alkaline, aqueous ethoxyethanol solution demonstrates that the principal species present under the reaction conditions are the carbonyl hydride anions H/sub 3/Ru/sub 4/(CO)/sub 12//sup -/ and HRu/sub 3/CO)/sub 11//sup -/. (The room temperature synthesis of the latter ion by the reaction of Ru/sub 3/(CO)/sub 12/ in alcoholic KOH is described). The catalysis rate shows a first-order dependence on both the CO partial pressure and the total ruthenium concentration. Cyclic mechanisms proposed to explain these observations involve nucleophilic attack of water or of hydroxide on coordinated CO followed by decarboxylation to give hydridic species from which H/sub 2/ is eliminated in a CO-assisted, rate-limiting step. It is noted that catalysts prepared by adding both iron and ruthenium carbonyls to the same solution are more active than either the ruthenium-based or the iron-based catalysts alone. These mixed metal catalyst solutions are shown to contain mixed metal clusters, and it is proposed that the synergetic effect on catalytic activity may result from greater reactivitymore » of the mixed metal clusters toward elimination of dihydrogen.« less

A Comparison of the Efficiencies of the Shotgun and the Bow in Neotropical Forest Hunting

Abstract: Whenever introduced into Amazonia and its neighboring regions, the shotgun has quickly replaced the bow and arrow and other aboriginal weapons of the hunt. The quick and widespread adoption of the shotgun is plainly a matter of its superiority over most aboriginal weapons. This paper compares the hunting efficiencies of the shotgun and the bow by means of a controlled field experiment among the Ye'kwana and Ygnomamo Indians of the Upper Orinoco River of southern Venezuela. It also examines the impact of the shotgun on local animal populations and the economic changes brought about by the need to cash-crop in order to purchase Western hunting technology.