Showing papers by "University of Oregon published in 1984"

Porter's (1980) Generic Strategies as Determinants of Strategic Group Membership and Organizational Performance

Abstract: A multimethod, multivariate analysis of “intended” strategies provides empirical support for the presence of strategic groups based upon Porter's (1980) generic strategies. Variations in intraindus...

Expanded Intonation Contours in Mothers' Speech to Newborns.

Abstract: The prosodic characteristics of "motherese" were examined in the speech of 24 German mothers to their newborns. Each subject was recorded in three observational conditions, while addressing (a) her 3to 5-day-oId baby (M-B Speech); (b) the absent infant, as if present (Simulated M-B Speech); and (c) the adult interviewer (M-A Speech). For each subject, 2-minute speech samples from each condition were acoustically analyzed. It was found that in M-B Speech, mothers spoke with higher pitch, wider pitch excursions, longer pauses, shorter utterances, and more prosodic repetition than in M-A Speech. Furthermore, 77% of the utterances in the M-B Speech sample conformed to a limited set of prosodic patterns that occurred only rarely in adult-directed speech, i.e., they consisted of characteristic "expanded" intonation contours, or they were whispered. The prosody of mothers' speech is discussed in terms of its immediate influence within the context of motherinfant interaction, as well as its potential long-range contribution to perceptual, social, and linguistic development.

Resolving 20 years of inconsistent interactions between lexical familiarity and orthography, concreteness, and polysemy.

Abstract: Numerous word recognition studies conducted over the past 2 decades are examined. These studies manipulated lexical familiarity by presenting words of high versus low printed frequency and most reported an interaction between printed frequency and one of several second variables, namely, orthographic regularity, semantic concreteness, or polysemy. However, the direction of these interactions was inconsistent from study to study. Six new experiments clarify these discordant results. The first two demonstrate that words of the same low printed frequency are not always equally familiar to subjects. Instead, subjects' ratings of "experimental familiarity" suggest that many of the low-printed-frequency words used in prior studies varied along this dimension. Four lexical decision experiments reexamine the prior findings by orthogonally manipulating lexical familiarity, as assessed by experiential familiarity ratings, with bigram frequency, semantic concreteness, and number of meanings. The results suggest that of these variables, only experiential familiarity reliably affects word recognition latencies. This in turn suggests that previous inconsistent findings are due to confounding experiential familiarity with a second variable.

Spectral sensitivity of a novel photoreceptive system mediating entrainment of mammalian circadian rhythms.

Abstract: Environmental light cycles are the dominant synchronizers of circadian rhythms in the field, and artificial light cycles and pulses are the major tools used in the laboratory to analyse properties of circadian systems1–4. It is therefore surprising that few studies have analysed the physical parameters of light stimuli that affect circadian rhythms. There have previously been no spectral sensitivity measurements for phase shifting the circadian rhythms of mammals and only two preliminary reports on the wavelength dependence of this response exist3,4. Using the magnitude of phase shift caused by a single 15-min pulse of monochromatic light given 6 h after activity onset, we have now characterized the spectral sensitivity of the photoreceptors responsible for phase shifting the locomotor rhythm of the hamster (Mesocricetus auratus). The sensitivity curve for this response has a maximum near 500 nm and is similar to the absorption spectrum for rhodopsin. Although the spectral sensitivity is consistent with a rhodopsin-based photopigment, two features of the photoreceptive system that mediates entrainment are unusual: the threshold of the response is high, especially for a predominantly rod retina like that of the hamster, and the reciprocal relationship between intensity and duration holds for extremely long durations (up to 45 min). These results suggest that the photoreceptive system mediating entrainment is markedly different from that involved in visual image formation.

MINERVA 2: A simulation model of human memory

Abstract: An overview of a simulation model of human memory is presented. The model assumes: (1) that only episodic traces are stored in memory, (2) that repetition produces multiple traces of an item, (3) that a retrieval cue contacts all memory traces simultaneously, (4) that each trace is activated according to its similarity to the retrieval cue, and (5) that all traces respond in parallel, the retrieved information reflecting their summed output. The model has been applied with success to a variety of phenomena found with human subjects in frequency and recognition judgment tasks, the schema-abstraction task, and paired-associate learning. Application of the model to these tasks is briefly summarized.

Heuristic Algorithms for Task Assignment in Distributed Systems.

Abstract: Investigate the problem of static task assignment in distributed computing systems, i.e. given a set of k communicating tasks to be executed on a distributed system of n processors, to which processor should each task be assigned? The author proposes a family of heuristic algorithms for Stone's classic model of communicating tasks whose goal is the minimization of the total execution and communication costs incurred by an assignment. In addition, she augments this model to include interference costs which reflect the degree of incompatibility between two tasks. Whereas high communication costs serve as a force of attraction between tasks, causing them to be assigned to the same processor, interference costs serve as a force of repulsion between tasks, causing them to be distributed over many processors. The inclusion of interference costs in the model yields assignments with greater concurrency, thus overcoming the tendency of Stone's model to assign all tasks to one or a few processors. Simulation results show that the algorithms perform well and in particular, that the highly efficient Simple Greedy Algorithm performs almost as well as more complex heuristic algorithms. >

The Psychology of the Withdrawal Process: A Cross-Validational Test of Mobley's Intermediate Linkages Model of Turnover in Two Samples.

Abstract: A study investigating the validity of Mobley's (1977) model of the intermediate linkages in the turnover decision process among employees working in two diverse settings yielded a pattern of results generally consistent with the model. However, except for commitment to the organization, regression analyses failed to double cross-validate either within or between samples.

The development of photoreceptors in the zebrafish, Brachydanio rerio. I. Structure

Abstract: Morphological development of photoreceptors in the central retina of the zebrafish, Brachydanio rerio, was studied by using light and electron microscopic techniques. Outer segments (OS) first appeared at 2.5 days postfertilization (d2.5). On d3, synaptic elaborations were seen. By d8, two OS types were present and were identified as cones. The first indication of rod formation was also evidenced at this time, when vitreally positioned nuclei were observed and rodlike cells were infrequently detected in electron micrographs. At d12, the full complement of zebrafish photoreceptors, rods and four cone types, was identified. From this time on cells grew until adult dimensions were reached at d24. These structural observations are consistent with results of functional studies which utilized physiological and behavioral techniques.

Inhibitory Self-Control in Preschool Children.

Abstract: Inhibitory self-control is proposed as a temperamental dimension. Soviet theory suggests that internal inhibition provides the basis for verbally regulated inhibi tion and is temperamentally determined. This relationship was investigated in 40 children aged 40 to 49 months. Significant correlations between performance on a measure of internal inhibition (spontaneous alternation) and two measures of verbally regulated inhibition (a pinball game and Simon-says) were found. Motor inhibition, measured with a drawing task, did not form part of the cluster. The cluster correlations are independent of age, although all measures show a large age effect. Age independence and generality across tasks suggest a temperamen tal basis for inhibitory self-control. Possible mechanisms are discussed.

Is the avian circadian system a neuroendocrine loop

Abstract: Avian circadian organization is a result of a complex interaction of photoreceptive and oscillatory components. The known components include the pineal gland, the lateral eyes, the suprachiasmatic nuclei (SCN), and extraocular brain photoreceptors. The pathways by which these components integrate circadian rhythmicity suggest a neuroendocrine loop in which the SCN inhibits pineal and ocular oscillators during the course of subjective day via a multisynaptic neuronal pathway which includes the superior cervical ganglia (SCG). During the night, the pineal in turn inhibits SCN activity via its secretion of the hormone melatonin into the blood circulation. This neuroendocrine loop, it is proposed, synchronizes multiple oscillators within each component and maintains the stability and precision of the system.

Generation of specific behaviors in a locust by local release into neuropil of the natural neuromodulator octopamine

Abstract: The natural insect neuromodulator octopamine (OCT) was released iontophoretically into regions of neuropil in locust metathoracic ganglia. A narrowly-defined site was found on one side of the ganglion at which release caused a prolonged bout of repetitive flex-extend-flex movements of the tibia on the injected side, at a frequency of from 2-3.5 Hz. When a bout had terminated, repetition of the OCT release caused an extremely similar bout to occur, and again with further treatments, indefinitely. OCT iontophoresis at the equivalent site on the contralateral side caused the contralateral flexor to make stepping movements. Two sites were found, in each half of the ganglion, at which similar OCT release evoked a bout of flight motor activity at 10 Hz. The flight bout involved both sides synchronously and nearly equally, except for a slightly greater motor output on the injected side. Evoked bouts lasted from 20 sec to 25 min depending on the preparation and amount of OCT released. At a site in the 6th abdominal ganglion of mature female locusts OCT release suppressed ongoing rhythmic oviposition digging evoked by severing the ventral nerve cord. A number of previously undescribed DUM neurons was encountered and their dendritic patterns, which are distinctive, determined following dye injection. A hypothesis, termed the Orchestration Hypothesis is presented, which considers how modulator neurons such as locust octopaminergic neurons, might be involved in the generation of specific behaviors.

Empirical Research in International Marketing: 1976–1982

Abstract: This paper reviews empirical research in international marketing published during the period 1976–82 The review focuses on what has been researched and how the research has been conducted This research is evaluated; a cooperative, multidisciplinary empirical research program in international marketing is then proposed

The perception of transparency with achromatic colors.

Abstract: Metelli has proposed a model of the intensity relationships in perceptual transparency based on Talbot’s law of color fusion. Four constraints follow from the application of Talbot’s law. Experiments 1 and 2 show that violations of constraints i and ii adversely affect the perception of transparency, while violations of constraints iii and iv do not. Many common occurrences of transparency are in terms of subtractive, rather than additive, color mixture. The constraints derived from the Metelli model are also shown to hold for subtractive color mixture with a filter. An assumption of the Metelli model is that the degree of perceived transparency varies linearly with reflectance. Experiment 3 indicates that the degree of perceived transparency with “partim transparency” varied linearly, not with reflectance, but with lightness, a nonlinear function of reflectance. Experiment 4 indicates that judgments of the degree of transparency with “complete transparency” are based on stimulus relations that differ from those that determine whether the perception of transparency occurs. The results are discussed in terms of how the pattern of intensities relates to other stimulus information, such as figural configuration, in producing the perception of transparency.

Utilization of Contextual Information in Determining the Meaning of Unfamiliar Words.

Abstract: TWO STUDIES were conducted to evaluate students' ability to utilize contextual information in learning the meaning of unfamiliar words. A descriptive study involving fourth-, fifth-, and sixth-grade children was designed to examine the differential effects of form and proximity of contextual information on students'learning of unfamiliar words. An experimental study involving the same-aged students was conducted to examine the differential effects of three intervention strategies designed to facilitate the use of contextual information in learning the meanings of unfamiliar words. The results of the descriptive study suggest that students were better able to determine the meaning of unfamiliar words when (a) contextual clues were provided, (b) students were older, (c) the clues were in synonym rather than inference form, and (d) contextual clues were closer to the unfamiliar word. In the experimental study, rule-plus-systematic-practice and systematic-practice-only conditions produced higher transfer scores than a nointervention condition.

Characteristics of Leg Movements and Patterns of Coordination in Locusts Walking on Rough Terrain

Abstract: A cinematographic analysis was made of locusts walking on a variety of terrains to determine the tactics used by single legs to find a site for support and the patterns of leg coordina tion when walking on rough terrain Three tactics were used by individual legs for finding a support site: (1)rhythmic searching movements initiated when the leg failed to contact the substrate at the end of the swing phase, (2) a tactile reflex to lift the leg above an object contacted during swing phase, and (3) local searching movements once the leg had contacted a potential supporting surface Animals did not adopt rigid gaits when walking on rough terrains The wide range of stepping patterns was due mainly to variation in the timing of stepping in opposite legs of the same segment However, there was a tendency for the stepping movements of opposite legs to be either 180° out of phase or exactly in phase In- phase stepping of the middle legs was observed frequently when animals walked over a ditch or up onto an eleva

Binding of N-carboxymethyl dipeptide inhibitors to thermolysin determined by X-ray crystallography: a novel class of transition-state analogues for zinc peptidases

Abstract: The mode of binding of the specific thermolysin inhibitor N-(1-carboxy-3-phenylpropyl)-L-leucyl-L-tryptophan (KI approximately 5 X 10(-8) M) [Maycock, A. L., DeSousa, D. M., Payne, L. G., ten Broeke, J., Wu, M. T., & Patchett, A. A. (1981) Biochem. Biophys. Res. Commun. 102, 963-969] has been determined by X-ray crystallography and refined to an R value of 17.1% at 1.9-A resolution. The inhibitor binds to thermolysin with both oxygens of the N-carboxymethyl group liganded to the zinc to give overall pentacoordination of the metal. The bidentate ligation of the inhibitor differs from the monodentate binding seen previously for carboxylate-zinc interactions in thermolysin and is closer to the bidentate geometry observed for the binding of hydroxamates [Holmes, M. A., & Matthews, B. W. (1981) Biochemistry 20, 6912-6920]. The geometry of the inhibitor and its interactions with the protein have a number of elements in common with the presumed transition state formed during peptide hydrolysis. The observed zinc ligation supports the previous suggestion that a pentacoordinate intermediate participates in the mechanism of catalysis. However, the alpha-amino nitrogen of the inhibitor is close to Glu-143, suggesting that this residue might accept a proton from an attacking water molecule (as proposed before) and subsequently donate this proton to the leaving nitrogen. By analogy with thermolysin, it is proposed that a related mechanism should be considered for peptide cleavage by carboxypeptidase A.(ABSTRACT TRUNCATED AT 250 WORDS)

The effects of single instance, multiple instance, and general case training on generalized vending machine use by moderately and severely handicapped students.

Abstract: This report provides an experimental analysis of generalized vending machine use by six moderately or severely retarded high school students. Dependent variables were training trials to criterion and performance on 10 nontrained "generalization" vending machines. A multiple-baseline design across subjects was used to compare three strategies for teaching generalized vending machine use. Training occurred with (a) a single vending machine, (b) three similar machines, or (c) three machines that sampled the range of stimulus and response variation in a defined class of vending machines. Results indicated that the third approach was the most effective method of obtaining generalized responding. Methodological implications for the experimental analysis of generalization and programmatic implications for teaching generalized behaviors are discussed.

Attitudes and social adaptation : a person-situation interaction approach

Abstract: Introduction. Person-oriented theories of attitude change. Situation-oriented theories of attitude change. An interactive theory of attitude change. Scope of persons: personality and persuasibility. Methodology in attitude research. Scope of situations. Attitudes and behaviors. Scope of interactions. Conclusions. References. Name index.

Do Cooperators Exit More Readily than Defectors

Abstract: Standard prisoners' dilemma games offer players the binary choice between cooperating and defecting, but in a related game there is the third possibility of leaving the game altogether. We conceptualize exiting as taking the individual beyond the reach of externalities generated in the original group, and on that basis—together with the assumption of self-interested (dollar-maximizing) behavior on the part of all players—we derive the prediction that the exit option will drain the community or group more of cooperators than of defectors.But experimental data do not support this prediction; cooperators do not leave more frequently than defectors and, in fact, there is evidence that defectors are more prone to leave than cooperators. We consider and reject the possibility that this failure of prediction results from the (admitted) greater optimism of cooperators about the incidence of cooperation “here,” and present data supporting the hypothesis that cooperators often stay when their personal interest is with exiting because of the same ethical or group-regarding impulse that (presumably) led them to cooperate in the first place. Cooperation can be produced for a group or community either by inducing people to cooperate or by inducing those who are going to cooperate to stay in the game, and ethical considerations seem to underlie the decision to stay as well as the decision to cooperate while staying.

Gradual and Abrupt Shifts in Ocean Chemistry During Phanerozoic Time

Abstract: The clearest records of changes in chemistry of the exogenic cycle are found in mineral inventories (NaCl, CaSO4, Ccarb, Corg, P), isotope ratios (δ34Ssft, δ13Ccarb, 87Sr/86Srcarb,87Sr/86Srapt), 87Sr/86Srapt), and trace elements (Ce/Laaptand heavy metals in black shales) vs. age. While these variations can be simplistically modelled in the long-term to confine all variations to the larger sedimentary reservoirs, there are several reasons to assert that some of the variability is internal to the smaller oceanic (and atmospheric) reservoirs, especially for short-term events. These are controlled by complex feedback loops, perhaps ultimately forced by plate-tectonic activity cycles. Many links are only speculative.

The Phoenix Agenda: Essential Reform in Teacher Education

Abstract: -All of us are familiar with the ancient story of the Phoenix and its symbolism of rebirth from a desperate situation. No field could better use the magical properties of the Phoenix than teacher education. The field is not just surrounded by critics, it is inhabited by them. Its graduates, current students, faculty, and administrators generate at least as much fury toward it as do the politicians, pundits, and serious scholars who reside outside it. Complaints about teacher education are wondrous in their variety and devastating in their implications. Its students are inferior. Its academic components are too brief and too weak. It is too theoretical and irrelevant to the real world of the schools. It is excessively devoted to pedagogy. It gives too little attention to teaching and practical matters. It squelches the creativity of its students. It resists innovation. Its graduates resist innovation. It is susceptible to faddism.

Pentoxifylline: A New Drug for the Treatment of Intermittent Claudication; Mechanism of Action, Pharmacokinetics, Clinical Efficacy and Adverse Effects

Abstract: During the past decade, the effectiveness of peripheral vasodilator drugs in the treatment of chronic occlusive arterial disease has been questioned. Pentoxifylline is a hemorheologic agent with primary actions that include increasing erythrocyte flexibility, reducing blood viscosity and increasing microcirculatory flow and tissue perfusion. The result is improved supply of oxygen to ischemic muscles of the limbs. In several double-blind studies, pentoxifylline increased walking distance of patients with intermittent claudication in comparison to placebo or vasodilators. Like other methylxanthines, pentoxifylline is well absorbed in the gastrointestinal tract, almost completely metabolized in the body and excreted in the urine. The most significant difference in its pharmacokinetics is that, unlike other methylxanthines, it is bound to the erythrocytic membrane where it is initially metabolized. Although pentoxifylline has been shown to be effective in the treatment of intermittent claudication, additional research is needed to determine its use as adjunctive therapy in patients with concurrent coronary or cerebrovascular disease.