Showing papers by "University of Texas at Arlington published in 1990"

Discrete Cosine Transform: Algorithms, Advantages, Applications

Abstract: Discrete Cosine Transform. Definitions and General Properties. DCT and Its Relations to the Karhunen-Loeve Transform. Fast Algorithms for DCT-II. Two Dimensional DCT Algorithms. Performance of the DCT. Applications of the DCT. Appendices. References. Index.

Naturalistic Social Cognition: Empathic Accuracy in Mixed-Sex Dyads

Abstract: The research paradigm that Ickes and his colleagues developed for the study of naturalistic social cognition was used to explore the phenomenon of empathic accuracy in the initial, unstructured interactions of 38 mixed-sex (male-female) dyads. The results indicated that an important aspect of empathic accuracy—content accuracy—could be measured reliably (a = .94) with the procedure used. The results further indicated that content accuracy was, to a large extent, an emergent product of social interaction processes occurring at the level of the dyad. Although many of the findings could be explained in informational terms, some significant motivational influences were observed as well. For example, content accuracy was influenced by the partner's physical attractiveness and, more generally, by the perceiver's apparent interest in the partner (as indexed by various thought/feeling measures). The individual difference variables of grade point average and selfmonitoring also predicted the subjects' levels of content accuracy; however, gender and self-report measures of empathic skills and empathic accuracy did not. If the study of subjective phenomena involving or occurring within a single conscious mind is the domain of mainstream cognitive psychology, it follows logically that the study of intersubjective phenomena involving or occurring between at least two conscious minds is the proper domain of cognitive social psychology (Ickes, Tooke, Stinson, Baker, & Bissonnette, 1988). The logic of this conclusion has been consensually validated by both present and past reviewers of social cognition research. For example, Markus and Zajonc (1985) ended their Handbook chapter on cognitive social psychology by stating that "the properties of social perception and social cognition that make them distinct are reciprocity and intersubjectivity" (p. 213). They noted that "many earlier authors, such as Mead (1934), Merleau-Ponty (1970), Asch, (1952), and Heider (1958)," have drawn essentially the same conclusion. In general, intersubjective phenomena can be characterized as those involving some form of interdependence between the contents or processes of at least two conscious minds (cf. Wegner, Giuliano, & Hertel, 1985). Given this definition, intersubjective phenomena are clearly not the most frequently studied phenomena in cognitive social psychology (Ickes et al., 1988). In most studies of human social cognition, researchers have not inquired how the contents and processes of one mind are interdependent with those of another. Instead, using as their models the studies conducted in more traditional areas of psychology, they have inquired how the contents and processes of

Guided-mode resonances in planar dielectric-layer diffraction gratings

Abstract: The guided-mode resonance behavior of the evanescent and propagating fields associated with an unslanted, planar diffraction grating is studied by means of the rigorous coupled-wave theory. For weakly modulated gratings, the condition on the guided-mode wave number of the corresponding unmodulated dielectric-layer waveguide may be used to predict the range of the incident angle or wavelength within which the resonances can be excited. Furthermore, the locations of the resonances are predicted approximately by the eigenvalue equation of the waveguide. As the modulation amplitude increases, the location and shape of the resonances are described in detail by the rigorous coupled-wave theory. The results presented demonstrate that the resonances can cause rapid variations in the intensity of the external propagating diffracted waves.

The ratio of nitrogen to phosphorus resupplied by herbivores: zooplankton and the algal competitive arena

Abstract: The influence of pelagic herbivores on the competitive arena of their prey is examined in three models of herbivore physiology. One hallmark of pelagic herbivory is the rapid and fight cycling of nutrients among algae, herbivores,and the dissolved phase. An implication of this cycling is that the ratio of elements released by the herbivore is a "supply ratio" as defined in resource-competition theory. The nitrogen (N)-to-phosphorus (P) supply ratio depends on the assumptions made regarding grazer physiology. Three alternative models are considered: (1) a constant, mass-specific basal metabolic release of N and P; (2) a constant efficiency of accumulating N and P in grazer biomass; and (3) an adjusting efficiency of N and P accumulation that maintains a homeostatic ratio of N to P (N:P) in the bodies of the grazers. All three models predict a positive correlation between the N:P in the algal pool and that released by the animals. Previously published data provided strong supportive evidence for this relati...

Chapter 1 – discrete cosine transform

Abstract: Publisher Summary This chapter presents discrete cosine transform. The development of fast algorithms for efficient implementation of the discrete Fourier transform (DFT) by Cooley and Tukey in 1965 has led to phenomenal growth in its applications in digital signal processing (DSP). The discovery of the discrete cosine transform (DCT) in 1974 has provided a significant impact in the DSP field. While the original DCT algorithm is based on the FFT, a real arithmetic and recursive algorithm, developed by Chen, Smith, and Fralick in 1977, was the major breakthrough in the efficient implementation of the DCT. A less well-known but equally efficient algorithm was developed by Corrington. Subsequently, other algorithms, such as the decimation-in-time (DIT),decimation-in-frequency (DIF), split radix, DCT via other discrete transforms such as the discrete Hartley transform (DHT) or the Walsh-Hadamard transform (WHT), prime factor algorithm (PFA), a fast recursive algorithm, and planar rotations, which concentrate on reducing the computational complexity and/or improving the structural simplicity, have been developed. The dramatic development of DCT-based DSP is by no means an accident.

Top management team group factors, consensus, and firm performance

Abstract: The results of recent consensus-performance research have been equivocal. Substantive and methodological issues are examined to suggest reasons for this equivocality. Top management team composition, structure, and decision processes are proposed as antecedents to the consensus-performance relationship. An argument is developed for a curvilinear aggregate consensus-performance relationship, moderated by environmental dynamism. A model and associated propositions are advanced to further descriptive and normative theory.

Prey-size selection by freshwater flagellated protozoa

Abstract: Planktonic bacteria may represent a substantial nutrient resource available to support the next higher trophic level in the microbial loop (heterotrophic flagellates). In this work we examined the utilization of different size classes of bacteria by flagellated protozoan predators of various sizes. The emphasis was to determine if prey-size selection was a function of predator size. Pseudomonas sp. was grown in chemostats under conditions to yield “large” (mean size, 1.19 pm’) or “small” individuals (mean size, 0.36 pm3). Cells were fluorescently labeled (DTAF), mixed in various proportions, and fed to four protozoans ranging in size from 21 to 119 pm3. Bacteria in food vacuoles were enumerated and measured. Size distributions of both offered and taken prey were compared, and a selectivity index was calculated. Protozoans of all four sizes preferred large bacteria (between 0.8 and 1.2 pm’). Since the work of Brooks and Dodson

Interlayer magnetic coupling in Fe/Cr multilayered structures

Abstract: We have calculated the mgnetic coupling of two layers of iron through an intervening layer of chromium. We use the mixing interaction between iron atoms at the interfaces with the conduction electrons of chromium and the band structure of paramagnetic chromium. When we take into account the roughness of the interface, our calculated coupling reproduces the essential features of the coupling found in Fe/Cr superlattices.

The Richness Imperative and Cognitive Style: The Role of Individual Differences in Media Choice Behavior.

Abstract: This article proposes a new thesis about the role of individual differences in managers' media choice behavior. It argues that individual differences influence media choice only under conditions of low message equivocality. When equivocality is high, a “richness imperative” masks the influence of individual differences. Managers are compelled to use richer media to match the equivocality of the message. However, in low-equivocality situations, richness demands are lowered. Any medium is capable of carrying the message. Thus managers have more freedom to act on their preferences, and individual differences are more likely to influence behavior. The findings of an exploratory study provide some support for this theoretical notion. As hypothesized, the judging/perspective attitude, as measured by the Myers Briggs Type Indicator, influenced media choice under conditions of low equivocality but not under conditions of high equivocality. However, tolerance for ambiguity did not significantly influence media cho...

A transactions data analysis of the variability of common stock returns during 1980–1984

Abstract: Using transactions data for a large sample of NYSE stocks for six months in 1971–1972 and calendar year 1982, Wood, McInish and Ord (1985) (WMO) show that the graph of the variability of index returns across days against time of day has a crude U-shaped pattern This study demonstrates that relatively high variability of returns at the beginning and end of the trading day also occurs during calendar years 1980, 1981, 1983 and 1984 In addition, the variability of intra-minute returns across stocks is shown to have a crude U-shaped pattern when plotted against time of day A model is developed and tested that explains this pattern of variability of intra-minute returns in terms of variability of market returns over the trading day The empirical results are consistent with this explanation

Thermal tolerance, evaporative water loss, air-water oxygen consumption and zonation of intertidal prosobranchs: a new synthesis

Abstract: Duration of emergence increases with tidal height on rocky shores therefore, emergence adaptations in intertidal species such as littorine and other prosobranch gastropods have been considered correlated with zonation patterns; temperature tolerance, desiccation resistance and aerial respiration rate all commonly assumed to increase progressively with increasing zonation level. Such direct correlations are rarely observed in nature. Maximal aerial gas exchange occurs in mid-shore, not high shore species. Temperature tolerance and desiccation resistance do not increase directly with shore height. Thus, hypotheses regarding physiological correlates of zonation require revaluation. A new hypothesis is presented that the high tide mark presents a single major physiological barrier on rocky shores. Above it, snails experience prolonged emergence and extensive desiccation; below it, predictable submergence and rehydration with each tidal cycle. Thus, desiccation stress is minimal below the high tide mark and maximal above it. Therefore, species restricted below high tide (the eulittoral zone) should display markedly different adaptive strategies to emergence than those above it (the eulittoral fringe). A review of the literature indicated that adaptations in eulittoral species are dominated by those allowing maintenance of activity and foraging in air including: evaporative cooling; low thermal tolerance; elevated aerial O2 uptake rates; and high capacity for radiant heat absorption. Such adaptations exacerbate evaporative water loss. In contrast, species restricted to the eulittoral fringe display adaptive strategies that minimize desiccation and prolong survival of emergence including: foot withdrawal, preventing heat conduction from the substratum; aestivation in air; elevated thermal tolerance reducing necessity for evaporative cooling; position maintenance by cementation to the substratum and increased capacity for heat dissipation. In order to test of this hypothesis the upper thermal limits, tissue and substratum temperatures on emergence in direct sunlight and evaporative water loss and tissue temperatures on emergence in 40 °C were evaluated for specimens of six species of eulittoral and eulittoral fringe gastropods from a granite shore on Princess Royal Harbour near Albany, Western Australia. The results were consistant with adaptation to the proposed desiccation barrier at high tide. The eulittoral species, Austrocochlea constricta, Austrocochlea concamerata, Nerita atramentosa and Lepsiella vinosa, displayed adaptations dominated by maintenance of activity and foraging during emergence while the eulittoral fringe littorine species, Bembicium vittatum and Nodilittorina unifasciata displayed adaptations dominated by minization of activity and evaporative water loss during emergence. The evolution of adaptations allowing tolerance of prolonged desiccation have allowed littorine species to dominate high intertidal rocky shore gastropod faunas throughout the world’s oceans.

Chemoreceptor modulation of endogenous respiratory rhythms in vertebrates.

Abstract: The relative contributions of O2- and CO2-sensitive chemoreceptor information to centrally generated respiratory patterns have changed dramatically during vertebrate evolution. Chemoafferent input from branchial O2 chemoreceptors modulates centrally generated respiratory patterns but is not critical for respiratory rhythmogenesis in fishes. In air-breathing fishes, branchial O2 chemoreceptors monitoring internal and external stimuli control the relative contributions of the gills and air-breathing organ to net ventilation, and chemoafferent input is necessary for initiating air breathing. In the transition from water to air breathing by amphibious vertebrates, rhythmic patterns of branchial ventilation are completely replaced by arrhythmic and intermittent patterns of air breathing, and there is progressive dependence on CO2 as a source of respiratory drive. Periodic initiation of air breathing in resting animals appears to depend on attaining a threshold level of afferent activity from O2- and CO2/pH-sensitive chemoreceptors, since hyperoxia and/or hypocapnia can abolish air breathing in all air-breathing vertebrates. Conversely, chemoreceptor stimulation in amphibians and reptiles converts intermittent to more continuous air breathing patterns, suggesting that adequate biasing input from chemoreceptors activates a central rhythm generator. Chemoafferent input in homeotherms serves as one of several sources of drive for rhythmic breathing and supplies feedback for blood gas homeostasis in the face of metabolic or environmental change.

Attitudes toward people with disabilities.

Abstract: Attitudes toward people with disabilities are learned, emotionally toned predispositions. This study compares such attitudes held by nursing faculty, beginning nursing students, graduating nursing students, registered nurses, and people with disabilities. Results of the study indicate that persons with disabilities were significantly more positive in their attitudes. Faculty held the least positive attitude, closely followed by graduating nursing students.

Effects of Sectioning Cranial Nerves IX and X on Cardiovascular and Ventilatory Reflex Responses to Hypoxia and Nacn in Channel Catfish

Abstract: Summary The afferent pathways mediating cardiovascular and ventilatory hypoxic reflexes were identified in anaesthetized, spontaneously breathing (ASB) channel catfish, Ictalurus pimctatus (Rafinesque), by bilateral section of cranial nerve IX and branchial branches of cranial nerve X to the four gill arches (Xbi-Xb4). Cardiovascular and ventilatory responses to hypoxia and NaCN were attenuated by partial denervation of the gills. There were no significant cardiovascular or ventilatory reflex responses to either hypoxia or NaCN after total branchial denervation. This suggests that hypoxic reflexes in channel catfish are mediated by O2-sensitive chemoreceptors located peripherally in the gills and innervated by cranial nerves IX and X.

Evolution of a Plio-Pleistocene volcanogenic-alluvial fan: The Puye Formation, Jemez Mountains, New Mexico

Abstract: The Plio-Pleistocene Puye Formation, north-central New Mexico, contains >15 km 3 of volcaniclastic alluvial sediments deposited in response to rift-margin volcanism associated with the later evolution of the Tschicoma volcanic center, northeastern Jemez Mountains. Stratigraphic and sedimentologic evidence indicates that aggradation of Puye deposits was nearly continuous and contemporaneous with graben development and establishment of the Rio Grande as the through-flowing axial drainage system in this region. Much of the Puye sediments debouched into an adjacent subsiding depocenter, resulting in near-complete preservation of this wedge-shaped volcanogenic fan. Primary-pyroclastic and reworked facies in the Puye Formation exhibit distinctive 5- to 30-m scale cyclicity directly related to volcanic activity in the northeastern Jemez highlands. Reworked-pyroclastic and conglomeratic sequences deposited by high-energy braided streams, sediment-charged sheet-floods, sediment-gravity flows, and in shallow lakes reflect markedly increased sediment loads during and following explosive eruptions. Individual sequences change markedly in character with increased distance from the source area. Analysis of these abrupt lateral and vertical variations reveals that Puye sedimentation was controlled by the influences of semiarid climate and syndepositional tectonism, although the associations that most characterize the fan resulted largely from explosive volcanism. Cessation of fan growth is attributed to waning sediment supply as a result of volcanic quiescence and to the onset of basinwide pedimentation associated with downcutting of the ancestral Rio Grande. The Puye fan therefore provides a detailed record of rift-basin alluvial sedimentation, complete with closely spaced tephrostratigraphic control, and it records the growth and partial denudation of high-standing, northeastern Jemez Mountains volcanoes.

Personality Moderating Variables: A Warning about Statistical Artifact and a Comparison of Analytic Techniques

Abstract: Personality moderating variables act to qualify the relationship between a personality trait measure and a relevant behavioral criterion. Two data analytic techniques that can be used to test for significant moderating effects are the “median split” (MS) approach and the “moderated multiple regression” (MMR) approach. The goals of the present research were (a) to apply the MS approach to computer-simulated data in which the moderator and trait extremity are confounded, to determine the extent of artifact, and (b) to compare the performance (Type I and Type II error rates) of the two approaches when applied to confounded and nonconfounded data. It was found that when the MS approach was applied to confounded data in which no real moderating effect existed, this approach produced an alarming rate of apparent, but spurious, moderating effects. When the MMR approach was applied to the same data, the rate of spurious effects was reduced to that expected by chance. When both approaches were applied to simulated data which contained genuine moderating effects, the MMR approach consistently resulted in more correct detections of these effects than the MS approach. We conclude that researchers should always employ the MMR rather than the MS approach when testing for personality moderator variable effects.

Psychic Powers, Astrology & Creationism in the Classroom? Evidence of Pseudoscientific Beliefs Among High School Biology & Life Science Teachers

Abstract: Many authors and researchers have noted the popularity of pseudoscientific beliefs in the United States.1,2 Although pseudoscience is not a new phenomenon (it has been around at least as long as science itself [Trefil 1978]), some suggest that pseudoscientific beliefs have become even more widespread in recent decades.3 The last three decades have also seen a decline in scientific literacy in the general public (Hively 1988). Unless the simultaneity of these two trends is purely coincidental-which seems highly unlikely-it may well be that understanding the mechanisms behind the origin and transmission of pseudoscientific beliefs will shed some light on the decline in scientific literacy.It is scarcely necessary to argue that knowledge and understanding of science has become more and more vital in this increasingly complex, high technology world. A much wider cross-section of the population is today asked to decide on matters involving issues with a substantial high technology component (e.g., SDI, space and environmental programs). To the extent that the promulgation of pseudoscientific beliefs is interfering with this knowledge and understanding, it must be addressed if we are to reverse the rising tide of scientific illiteracy. This paper examines one important potential source of pseudoscientific belief in the population-the extent to which those given the responsibility of transmitting knowledge of science to our high school students actually hold pseudoscientific beliefs themselves. The first section of the analysis presents evidence for the prevalence of pseudoscientific belief among the general public. Previously suggested sources for pseudoscientific beliefs are explored in the second section. We then focus in detail on one potential source of pseudoscientific belief-science teachers. The extent and specific types of pseudoscientific belief held by a sample of high school life science and biology teachers are examined, as well as the demographic and social correlates of such beliefs. Finally, the implications of high school science teachers' pseudoscientific beliefs for science education are discussed.

Differential expression of mRNA and protein encoding retinal and pineal S-antigen during the light/dark cycle.

Abstract: S-Antigen is a soluble cell protein unique to the retina and pineal gland. In the former, it is a well-characterized molecule that participates in light-induced signal transduction in photoreceptor cells. In the latter, the functional role is presently not known. The expression of S-antigen and its mRNA was examined in the rat retina and pineal gland throughout the diurnal cycle and with light interruption of the dark cycle. A cDNA for rat S-antigen was isolated from a pineal gland library to examine the mRNAs. A 1.7-kb mRNA for S-antigen was observed in both the pineal gland and the retina. Retinal S-antigen mRNA was expressed throughout the diurnal cycle and increased with light interruption of the dark cycle. In contrast, pineal gland S-antigen mRNA levels were detectable only during the dark and were absent preceding and during light. The phenotypic expression of immunoreactive S-antigen, identified with two S-antigen monoclonal antibodies (MAbs), MAb A9C6 and MAb C10C10, was analyzed by sodium dodecyl sulfate (SDS)-polyacrylamide gel (PAGE) and isoelectric focusing (IEF) electrophoresis. Immunoblot analysis of gels after SDS-PAGE revealed a single 46-kDa protein in retina. In contrast, two bands of approximately 43 and 46 kDa were identified in the pineal gland. Immunoblots of the retinal extracts separated by IEF electrophoresis revealed five S-antigen isomers, which vary quantitatively throughout the diurnal cycle and when light interrupted the dark cycle. Immunoblots of the pineal gland samples separated by IEF electrophoresis indicated that the pineal gland possesses four pineal gland-specific forms of S-antigen in addition to the five forms present in the retina. The differences observed in the mRNA and protein analyses suggest tissue-specific structural components for S-antigen in the retina and pineal gland that are not regulated in the same manner.

Politics, lack of career progress, and work/home conflict: Stress and strain for working women

Abstract: This study examines the stress experienced by working women in terms of politics, lack of career progress, and work/home conflicts, the symptoms of distress and satisfaction associated with these stressors, and the organizational resources available for managing these demands. Subjects were 195 female personnel professionals. A different pattern of results emerged for politics and lack of career progress in contrast to work/home conflicts. Specifically, politics and lack of career progress were associated with greater strain symptoms and reduced satisfaction, and organizational resources were associated with lower levels of these stressors. Work/home conflicts were associated with greater strain symptoms, but were unrelated to satisfaction and organizational resources. This suggests that organizations identify the most effective targets of their resources to achieve beneficial results.

Growth of diamond films and characterization by Raman, scanning electron microscopy, and x-ray photoelectron spectroscopy

Abstract: We have deposited diamond films on Si〈111〉 using hot filament assisted chemical vapor deposition at low pressures ∼25 Torr. Diamond films deposited at different relative concentrations of methane (ranging from 0.25% to 2.0%) in methane-hydrogen mixtures have been characterized by Raman spectroscopy, scanning electron microscopy, and x-ray photoelectron spectroscopy. With varying methane concentration, Raman spectra show features characteristic of crystalline diamond, diamond-like carbon, and polycrystalline graphite. Scanning electron micrographs show densely packed diamond crystallites. SEM measurements made on diamond films grown as a function of time show that the median grain size of the diamond crystallites increases linearly with time during the initial phase of the growth. X-ray photoelectron spectroscopy reveals differences between the diamond sp3 covalent bonding and sp2 graphitic bonding as well as the extent of s-p hybridization as a function of methane concentration. The plasmon loss shoulder, characteristic of graphite, is absent from the spectrum of 0.25% methane concentration film. But it appears in the XPS spectra of films grown at higher concentrations.

Sliding-mode controller design of a single-link flexible manipulator under gravity

Abstract: This is follow-up research of the regulator design for a single-link flexible manipulator using the sliding-mode technique (Yeung and Chen 1989). In this paper, we have extended the controller design for the regulation problem to that for the tracking problem when the single-link manipulator is moving on a horizontal plane. In addition, by placing strain gauges along the flexible arm (Hastings and Book 1985) we can substitute strain measurements for the need to estimate modal functions, which is a step close to implementational reality. Extension of the controller design is also carried out to the regulation of a flexible arm under gravity. A PID compensation is needed to compensate for the steady-state offset due to gravity. The controller design presented is simple and requires no inertia matrix inversion, no modal estimation and no payload forecast. Simulation studies demonstrate the robustness of the control against input disturbance and payload variations

Lake Morphometry and Light in the Surface Layer

Abstract: Mean irradiance in the surface layer was calculated as a percent of incident irradiance using Secchi depths and thermocline depths for two sets of lakes: (1) 20 nearly circular lakes in northwest Minnesota, USA, sampled at a similar season, and (2) 1140 lakes of heterogeneous shapes in Ontario, Canada, sampled throughout the ice-free season. For both, as lake area increased, the thickness of the surface layer increased. Consequently, lakes larger in area had lower mean irradiance in their surface layer. Lake depth had less influence, but in the Ontario lakes, as depth increased, attenuation decreased, and mean irradiance increased. Lake area (log transformed) explained ca. one-half of the variation in mean irradiance in the homogeneous sampling of Minnesota lakes, while area and depth together explained less of the variation in the heterogeneous sampling of Ontario lakes. Shape, i.e. shoreline development, was unimportant compared with the gross measures of size, area and depth. Mean irradiance is complex...

Theoretical study of the application of positron-induced Auger-electron spectroscopy

Abstract: The interpretation and prospective applications of the novel surface-science technique positron-induced Auger-electron spectroscopy (PAES) have been investigated theoretically by calculations of annihilation rates of surface-trapped positrons with core electrons. The positron surface state is described by the corrugated-mirror model and core-annihilation rates are calculated with use of the independent-particle model. At clean surfaces of Al, Ni, Cu, and Au, 1--5 % of surface-trapped positrons are found to annihilate with core electrons and thus give rise to Auger-electron emission. On low-Miller-index surfaces more than 80% of the core annihilations take place with electrons from the topmost layer of atoms, which demonstrates the extreme surface sensitivity of PAES. Adsorption of impurities is found to reduce the substrate Auger signals, and the intensity of Auger lines due to the adsorbate increases with increasing coverage in agreement with recent experiments by Mehl et al. The results are found to depend markedly on whether the adsorbate atoms occupy subsurface sites or chemisorption sites above the surface, demonstrating that PAES can be useful in studies of adsorbate location. The applicability of PAES to studies of alloy surfaces and surface segregation is illustrated by calculations for Cu-Au surfaces. A set of bulk positron calculations shows that most elements are expected to have strong PAES signals.