Showing papers by "University of Iowa published in 1983"

Design and Analysis of Simulated Consumer Choice or Allocation Experiments: An Approach Based on Aggregate Data:

Abstract: The authors integrate concepts in conjoint analysis and discrete choice theory in econometrics to develop a new approach to the design and analysis of controlled consumer choice or resource allocat...

Effects of need for cognition on message evaluation, recall, and persuasion.

Abstract: This research concerns the relation among need for cognition, message processing, and persuasion. Pairs of subjects holding approximately the same attitude toward instituting senior comprehensive exams and differing widely in their scores on the need for cognition scale were recruited to participate in the first study. In Experiment 1, subjects read a set of either strong or weak arguments supporting the recommendation that senior comprehensive exams be instituted. Results revealed that argument quality had a greater impact on the message evaluations and source impressions provided by individuals high than by those low in need for cognition and that subjects high in need for cognition reported expending more cognitive effort and recalled more message arguments regardless of argument quality. The major findings in Experiment 1 were replicated in Experiment 2 with a different topic (i.e., raising student tuition) and cover story. In addition, the inclusion of a postcommunication attitude measure revealed that the attitudes of individuals high in need for cognition were more affected by argument quality than those of subjects low in need for cognition. Together, these studies document a reliable difference among individuals in their tendency to derive information from and elaborate on externally provided message arguments.

An Algorithm for Restricted Least Squares Regression

Abstract: A commonly occurring problem in statistics is that of minimizing a least squares expression subject to side constraints. Here a simple iterative algorithm is presented and shown to converge to the desired solution. Several examples are presented, including finding the closest concave (convex) function to a set of points and other general quadratic programming problems. The dual problem to the basic problem is also discussed and a solution for it is given in terms of the algorithm. Finally, extensions to expressions other than least squares are given.

Inhibition of transcription of the phosphoenolpyruvate carboxykinase gene by insulin

Abstract: Insulin regulates the synthesis of several proteins in a variety of tissues1. Before techniques were available to quantify the amount of specific mRNAs, insulin was thought to regulate the synthesis of proteins by influencing the rate of translation of a fixed amount of mRNA. A very different interpretation is called for by experiments which show that insulin alters the amount of several specific mRNAs2–5, but little is known about the mechanism. Insulin decreases the rate of synthesis of the critical gluconeogenic enzyme phosphoenolpyruvate carboxykinase (PEPCK) in both liver6 and H4IIE heptoma cells7,8. We recently showed that insulin acts directly on H4IIE cells to decrease mRNAPEPCK activity without any other hormone intermediaries8. This effect is mediated by the insulin receptor and occurs at insulin concentrations which are well within the physiological range (10−12–10−9 M)8. Here we extend these studies to show that insulin specifically inhibits transcription of the PEPCK gene. This inhibition results in a rapid decrease in the concentration of nuclear PEPCK transcripts which is followed, in turn, by a proportionate decline in cytoplasmic mRNAPEPCK and synthesis of the protein.

The plasma sheet boundary layer

Abstract: A spatially distinct, temporally variable, transition region between the magnetotail lobes and the central plasma sheet designated the plasma sheet boundary layer has been identified from a survey of particle spectra and three-dimensional distributions as sampled by the ISEE 1 LEPEDEA. The instrumentation and data presentation are described, and the signatures of the magnetotail plasma regimes are presented and discussed for the central plasma sheet and lobe and the plasma sheet boundary layer. Comparisons of plasma parameters and distribution fucntions are made and the evolution of ion velocity distributions within the plasma sheet boundary layer is discussed. The spatial distribution of the plasma sheet boundary layer is considered and ion composition measurements are presented.

The effects of new science curricula on student performance

Abstract: This study summarizes the results of a quantitative synthesis of the retrievable primary research dealing with the effects of new science curricula on student performance. This study synthesizes the results of 105 experimental studies involving more than 45,000 students and utilizes the quantitative synthesis perspective to research integration known as meta-analysis (Glass, 1976). A total of 27 different new science curricula involving one or more measures of student performance are included in this meta-analysis. Data were collected for 18 a priori selected student performance measures. The results of this meta-analysis reveal definite positive patterns of student performance in new science curricula. Across all new science curricula analyzed, students exposed to new science curricula performed better than students in traditional courses in general achievement, analytic skills, process skills, and related skills (reading, mathematics, social studies and communication), as well as developing a more positive attitude toward science. On a composite basis, the average student in new science curricula exceeded the performance of 63% of the students in traditional science courses.

Dexamethasone suppression tests in antidepressant treatment of melancholia. The process of normalization and test-retest reproducibility.

Abstract: • Pilot studies suggest that changes in response to the dexamethasone suppression test (DST) in melancholic patients receiving antidepressants might represent a laboratory marker of clinical progress. We performed weekly DSTs in 31 hospitalized patients with major depressive disorder, primary and endogenous subtypes, during drug-free and subsequent treatment periods. Most nonsuppressors had progressive normalization of DST responses in conjunction with clinical improvement, DST normalization usually preceded or coincided with good clinical response, and failure to normalize was often associated with poorer clinical outcome. Occasional patients with baseline dexamethasone suppression become nonsuppressive after withdrawal from medication, but the DST has no apparent value as a serial marker in patients with welldocumented normal DST findings. Our results extend the construct validity of the DST as a state-related marker in nonsuppressors and suggest future clinical applications.

Arterial Baroreflexes in Humans

Abstract: The sections in this article are: 1 Techniques 1.1 Carotid Sinus Massage 1.2 Electrical Stimulation of Carotid Sinus Nerves 1.3 Section or Anesthesia of Carotid Sinus Nerves and Vagi 1.4 Occlusion of Common Carotid Arteries 1.5 Neck Chamber 1.6 Vasoactive Drugs 1.7 Nonselective Techniques 2 Arterial Baroreceptor Control of Heart Rate 2.1 Autonomic Mediation 2.2 Other Properties 2.3 Relationship to Base-Line R-R Interval 2.4 Relationship to Respiratory Cycle 3 Arterial Baroreceptor Control of Atrioventricular Conduction and Ventricles 4 Carotid Baroreceptor Control of Blood Pressure 5 Carotid Baroreceptor Influence on Cardiac Output and Total Peripheral Resistance 6 Arterial Baroreceptor Control of Regional Circulations 7 Arterial Baroreceptor Control of Veins 8 Set Point of Carotid Baroreflex 9 Aortic Baroreflexes 10 Factors That Modify Arterial Baroreceptor Control of Circulation 10.1 Age 10.2 Exercise 10.3 Mental Stress 10.4 Sleep 10.5 Anesthesia 10.6 Central Blood Volume and Posture 11 Pathological States 11.1 Hypertension 11.2 Heart Disease 11.3 Carotid Sinus Syndrome 11.4 Other Pathological Conditions 12 Modification of Arterial Baroreflexes by Drugs 12.1 β-Adrenergic Antagonists 12.2 Cardiac Glycosides 12.3 Antihypertensive Drugs

Field dependence and attitude change: Source credibility can alter persuasion by affecting message-relevant thinking

Abstract: The present study shows that for a personally relevant counterattitudinal issue, a highly credible source can alter persuasibility by increasing a subject's message-relevant thinking. Previous failures to show this effect were probably due to the highly thoughtful nature of typical research subjects, when confronted with involving issues. In the present study, field-dependent and field-independent subjects heard convincing or refutable counterattitudinal speeches given by sources of high or low credibility. Results indicated that subjects who are typically low in differentiation of stimuli (field-dependent subjects) showed differential persuasion to strong and weak arguments only when they were presented by a highly credible source. For subjects who are typically high in propensity to differentiate stimuli (field-independent subjects), the arguments were differentially persuasive for both high and low credible sources. These results are consistent with the hypothesis that increasing source credibility can enhance message-relevant thought for subjects who typically do not scrutinize message content.

A porous-wavemaker theory

Abstract: A porous-wavemaker theory is developed to analyse small-amplitude surface waves on water of finite depth, produced by horizontal oscillations of a porous vertical plate. Analytical solutions in closed forms are obtained for the surface-wave profile, the hydrodynamic-pressure distribution and the total force on the wavemaker. The influence of the wave-effect parameter C and the porous-effect parameter G, both being dimensionless, on the surface waves and on the hydrodynamic pressures is discussed in detail.

Soliton experiments in plasmas

Abstract: The experiments on solitons in plasmas performed during the period 1970 to 1982 are reviewed. Suggestions for future experiments are presented.

Auroral hiss, Z-mode radiation and auroral kilometric radiation in the polar magnetosphere: DE-1 observations

Abstract: The polar-orbiting DE 1 spacecraft has provided the first measurements of high-latitude auroral phenomena. Three types of plasma-wave emissions were observed: auroral hiss, Z-mode radiation, and auroral kilometric radiation. Whistler mode auroral hiss emissions were observed on virtually every pass over the auroral zone. The shape of the auroral hiss frequency-time spectrum is explained by a whistler mode propagation effect if the radiation is emitted from a spatially localized source below the spacecraft. Broadband Z emissions have been observed in the low-density region over the auroral zone and polar cap. The auroral hiss may be distinguished from the Z-mode radiation by the sharp upper cutoff of the whistler mode at the local electron plasma frequency. Auroral kilometric radiation usually occurs at frequencies above electron gyrofrequency, indicating that this radiation is propagating in the free-space R-X mode.

Postpartum depression. A role for social network and life stress variables.

Abstract: Depressed (N = 11) and nondepressed (N = 19) women who had recently given birth were compared on several life stress measures and indices of structural and qualitative characteristics of their social networks. We predicted that depressed subjects diagnosed on the basis of Research Diagnostic Criteria would have experienced more stressful life events since the beginning of pregnancy and since delivery. We also predicted that depressed subjects would have fewer confidants and receive less instrumental and emotional support from their network members. These predictions were largely confirmed, except that the two groups did not differ on number of confidants. The social support provided by spouses appeared to be especially important. Implications of these findings for life events and social network research are discussed.

The effects of departmental demography on turnover: The case of a university.

Abstract: The argument developed here is that turnover or exit behavior is, in part, a characteristic of the demography of the social system itself. University academic departments with a dominant cohort and...

Evidence for gene-environment interaction in the development of adolescent antisocial behavior

Abstract: Data from three adoption studies are used to test for gene-environment interaction in the development of adolescent antisocial behaviors. Results indicate significant increases in antisocial behaviors when an adoptee has both a genetic factor and an adverse environmental factor present. The increase in number of antisocial behaviors due to both genetic and environmental factors acting together is far greater than the predicted increase from either factor acting alone.

The importance of terminology in teaching K-12 science

Abstract: Several recent reports concerning the status of science education in K-12 classrooms have emphasized the centrality of textbooks to instruction. Some initial investigations of the nature of textbooks have suggested that typically more new words and terms are introduced than one would expect to find in a similar time frame as foreign languages are studied. This is a review of these initial studies, a review of the studies of mastery of vocabulary in foreign languages, and a review of general research concerning the vocabulary development, especially as it pertains to reading. Twenty-five of the most commonly used textbooks in K-12 science classrooms are analyzed in terms of the occurrence of special/technical words. The number of words introduced at every level is considerable-often more than would be required if a new language were being introduced. In addition, the number of new words in science often approaches the total number that could be expected in terms of total vocabulary increase at a given grade level for a given student. There is strong evidence that one major fact of the current crisis in science education is the considerable emphasis upon words/terms/definitions as the primary ingredient of science-at least the science that a typical student encounters and that he/she is expected to master.

Medium Promoting Sporulation of Bacillus larvae and Metabolism of Medium Components.

Abstract: A new medium, designated TMYGP broth, was developed that allowed the honeybee pathogen Bacillus larvae NRRL B-3650 to produce up to 5 × 108 spores per ml of culture (microscopic count). This species normally sporulates poorly, if at all, in artificial broth media. An aeration rate lower than that normally used to cultivate other Bacillus species was required for sporulation. During the exponential growth phase, acids were produced by catabolism of yeast extract components, causing a decrease in pH of the medium. Thereafter, the pH began to increase, probably because of derepression of the citric acid cycle and consumption of the acids. Only after this time did usage of glucose from the medium occur. Thus, glucose usage seems to be regulated by catabolite repression. The presence of glucose was needed for one or more of the later events of sporulation. Of many substances tested, only gluconic acid and glucosamine partially substituted for glucose as a requirement for sporulation. Pyruvate was also required for good sporulation. It was metabolized during the late-exponential phase of growth.