Showing papers by "Northwestern University published in 1980"

Two algorithms for constructing a Delaunay triangulation

Abstract: This paper provides a unified discussion of the Delaunay triangulation. Its geometric properties are reviewed and several applications are discussed. Two algorithms are presented for constructing the triangulation over a planar set ofN points. The first algorithm uses a divide-and-conquer approach. It runs inO(N logN) time, which is asymptotically optimal. The second algorithm is iterative and requiresO(N 2) time in the worst case. However, its average case performance is comparable to that of the first algorithm.

Distribution Channels as Political Economies: A Framework for Comparative Analysis:

Abstract: This paper presents a unifying framework for the analysis of distribution channels which encompasses both economic and sociopolitical determinants of channel member behavior and provides a suitable...

Banting Lecture 1980: of Pregnancy and Progeny

Abstract: A profile characteristic of fuel economy in the mother during normal pregnancy has been delineated. The evidence indicates that pregnancy changes the metabolism of every class of foodstuff. The mechanisms by which the conceptus may be implicated are reviewed. The gestational interactions create a pattern of “accelerated starvation” whenever food is withheld, especially in late pregnancy, and they tend to “facilitate anabolism” when food is ingested. The consequent heightened metabolic oscillations during the shuttlings from fed to fasted state provide a basis for more aggressive therapy with exogenous insulin when endogenous insulin is lacking in pregnancy. It is emphasized that developing fetal structures may be exquisitely attuned to fine alterations in maternal fuel economy and that pregnancy complicated by diabetes may merely exaggerate these normal dependencies since maternal insulin affects all maternal fuels. The manifest changes in the offspring of mothers with. even the mildest limitations in insulin reserve, i.e., gestational diabetes, attest to the sensitivity of the relationships. It is suggested that concepts of teratogensis should be expanded to include alterations occurring subsequent to organogenesis during the differentiation and proliferation of fetal cells. Such changes could cause long-range effects upon behavioral, anthropometric, and metabolic functions. It is hypothesized that all of these could constitute expressions of fuel-mediated teratogenesis and that the potentialities should be incorporated into any evaluation of the outcome of pregnancy in gestations attended by disturbances in maternal fuel metabolism.

Hypolipidaemic hepatic peroxisome proliferators form a novel class of chemical carcinogens.

Abstract: Several drugs, including clofibrate (ethyl-a-p-chlorophenoxyisobutyrate)1, are now available for the treatment of hyperlipidaemias2,3 and others are in the process of preclinical or clinical evaluation4,5. Clofibrate, the most widely used hypo-lipidaemic drug in Europe and the US2, as well as other potent hypolipidaemic agents, cause massive hepatomegaly when administered to rats6–8, mice7,8 or hamsters (J.K.R., unpublished). This hepatomegaly is characteristically associated with a marked increase of peroxisomes (Fig. 1) in the liver cells of all three species6–8. These ubiquitous cytoplasmic organelles9,10contain catalase, several hydrogen peroxide-generating oxi-dases, carnitine acetyltransferase11 as well as enzymes involved in the β-oxidation of long-chain fatty acids12. The activities of these enzymes in liver are elevated in association with peroxisome proliferation8,13. As hepatomegaly and peroxisome proliferation persist for as long as these drugs are administered to the animals, we initiated chronic toxicity studies with selected hepatic peroxisome proliferators in CSb mice and F344 rats. Liver tumours were observed in both rats and mice fed nafeno-pin (2-methyl-2[p-(l,2,3,4-tetrahydro-l-naphthyl)phenoxy]-propionic acid)14–16 or Wy-14,643 ([4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio]acetic acid)17, two structurally unrelated compounds (Fig. 2, compounds 2 and 3) which are several times more potent than clofibrate in inducing peroxisome proliferation and hypolipidaemia8. Recent evidence indicates that clofibrate (Fig. 2, compound 1) is also carcinogenic when fed to rats at a concentration of 0.5% in the diet18,19. We report here that BR-931 ([4-chloro-6-(2,3-xylidino)-2-pyrimidinylthio(N-β-hydroxyethyl)-acetamide])20 and tibric acid(2-chloro-5-(3,5-dimethylpiperidinosulphonyl)benzoic acid)8, two potent hypolipidaemic hepatic peroxisome proliferators (Fig. 2, compounds 4 and 5) induce hepatocellular carcinomas in CSb mice and/or F344 rats. Thus, the development of liver tumours, in animals fed five structually diverse hypolipidaemic compounds (Fig. 2) supports our hypothesis that potent hepatic peroxisome proliferators as a class are carcinogenic.

Self-Interest vs. Symbolic Politics in Policy Attitudes and Presidential Voting

Abstract: This article contrasts short-term self-interest and longstanding symbolic attitudes as determinants of (1) voters' attitudes toward government policy on four controversial issues (unemployment, national health insurance, busing, and law and order), and (2) issue voting concerning those policy areas. In general, we found the various self-interest measures to have very little effect in determining either policy preferences or voting behavior. In contrast, symbolic attitudes (liberal or conservative ideology, party identification, and racial prejudice) had major effects. Nor did self-interest play much of a role in creating “issue publics” that were particularly attentive to, informed about, or constrained in their attitudes about these specific policy issues. Conditions that might facilitate more self-interested political attitudes, specifically having privatistic (rather than public-regarding) personal values, perceiving the policy area as a major national problem, being high in political sophistication, perceiving the government as responsive, or having a sense of political efficacy, were also explored, but had no effect. The possibility that some long-term self-interest might be reflected in either group membership or in symbolic attitudes themselves is examined. While such possibilities cannot be definitively rejected, problems with interpreting standard demographic findings as self-interest effects are discussed.

Heart rate as a prognostic factor for coronary heart disease and mortality: findings in three chicago epidemiologic studies

Abstract: The associations between heart rate and death from the cardiovascular diseases (CVD), coronary heart disease (CHD) and sudden death from CHD, along with death from all causes and non-cardiovascular causes, are examined for three groups of middle-aged white males: 1233 men aged 40-59 years followed for 15 years from the Chicago Peoples Gas Company study; 1899 men aged 40-55 years followed for 17 years from the Chicago Western Electric Company study; and 5784 men aged 45-64 years followed an average of five years from the Chicago Heart Association Detection Project in Industry. In univariate analyses, mortality from both cardiovascular and non-cardiovascular causes generally increases with increasing heart rate. In bivariate analyses, using the Cox regression model to control for age, heart rate is significantly related to mortality from all causes in each study, with the associations again due to both cardiovascular and non-cardiovascular causes. In multivariate Cox regression, controlling for age, blood pressure, serum cholesterol, cigarettes smoked per day and relative weight, heart rate is a significant risk factor for sudden CHD death and non-CVD death in two of the three studies, with the association with sudden death being U-shaped in one of the studies. Although heart rate may be an independent risk factor for sudden CHD death, the associations with other CVD death and non-sudden CHD death, in general, appear to be secondary to associations between heart rate and other cardiovascular risk factors.

The interactive effect of personality, time of day, and caffeine: A test of the arousal model.

Abstract: The personality dimension of introversion/extraversion is one of the few personality dimensions that can be reliably identified from study to study and investigator to investigator. The importance of this demension within personality theory is due both to the stability of the trait and the influential theory of H. J. Eysenck. The basic assumption in Eysenck's theory of introversion/extraversion is that the personality differences between introverts and extraverts reflect some basic difference in the resting level of cortical arousal or activation. Assuming that there is a curvilinear relationship (an inverted U) between levels of stress and performance leads to a test of this arousal theory. That is, moderate increases in stress should hinder the performance of introverts who are presumably already highly aroused. However, the same moderate increase in stress might help the performance of the presumably underaroused extraverts. Revelle, Amaral, and Turriff reported that the administration of moderate doses of caffeine hindered the performance of introverts and helped the performance of extraverts on a cognitive task similar to the verbal test of the Graduate Record Examination. Assuming that caffeine increases arousal, this interaction between introversion/extraversion and drug condition supports Eysenck's theory. This interaction was explored in a series of experiments designed to replicate, extend, and test the generality of the original finding. The interaction between personality and drug condition was replicated and extended to additional cognitive performance tasks. However, these interactions were affected by time of day and stage of practice, and the subscales of introversion/extraversion, impulsivity, and sociability, were differentially affected. In the morning of the first day, low impulsives were hindered and high impulsives helped by caffeine. This pattern reversed in the evening of the first day, and it reversed again in the evening of Day 2. We concluded that the results from the first day of testing require a revision of Eysenck's theory. Instead of a stable difference in arousal between low and high impulsives, it appeared that these groups differed in the phase of their diurnal arousal rhythms. The result is that low impulsives are more aroused in the morning and less aroused in the evening than are the high impulsives. A variety of peripheral or strategic explanations (differences in caffeine consumption, guessing strategies, distraction, etc.) for the observed performance increments and decrements were proposed and tentatively rejected. It seems probable that some fundamental change in the efficiency with which information is processes is responsible for these performance changes.

A linearised relativistic augmented-plane-wave method utilising approximate pure spin basis functions

Abstract: The authors describe a fully relativistic augmented-plane-wave (APW) method where the basis functions are pure spin functions in the large component. This feature allows spin-mixing interactions to be separated and treated more efficiently than in the standard relativistic APW method. These basis functions are constructed by solving an approximate relativistic radial equation. In addition, the energy derivative is used in the construction of the basis functions so that one obtains adequate variational freedom solving a linear secular equation. Both the utility and the limitations of the technique are discussed.

Chemical, spectral, structural, and charge transport properties of the "molecular metals" produced by iodination of Nickel Phthalocyanine

Abstract: : Partial oxidation of metallophthalocyanines with iodine has provided an extensive new class of molecular conductors. As illustrated in the present case with nickel phthalocyanine, the properties of the resulting solid state array of pi-cation radicals include electrical conductivity which is comparable with that of the best-known stacked molecular conductors. A particularly intriguing feature of NiPcI1.0 charge transport is a transition from metallic to semi-conducting behavior which apparently is not reflected in the magnetic properties of the carriers. It is tempting to speculate that this behavior reflects a change in carrier mobility brought about by some subtle structural rearrangement such as a change in the ordering of the triiodide chains. In a broader perspective, the iodinated metallophthalocyanines, such as those reported here, represent the first entry into a widening area of conductive materials based upon the ligand pi systems of mixed-valent metallo-macrocyclic arrays. Clearly the insights gleaned and the methodology developed will lead to an ever-deepening understanding of those molecular characteristics which facilitate charge conduction and which optimize materials performance.

Fear in the Neighborhoods: an Investigation of the Impact of Crime

Abstract: Residents in four Chicago neighborhoods were surveyed to determine the rela tionship between fear of crime and official crime rates. Several anomalies were found. Citizens' perceptions of dangerous areas in their neighborhoods match, for the most part, official records of crimes committed there. However, assessments of neighborhoods' specific crime problems and personal risks do not consistently cor respond with official statistics. The authors argue that citizens' perceptions of crime are shaped not so much by the neighborhood conditions reflected in the crime statistics, but rather by the level of incivility in their communities. Indicators of incivility are conditions, more frequently confronted, indicating that community social control is weak. These include abandoned buildings, vandalism, drug use, and loitering teenagers. The authors demonstrate the correspondence between levels of fear and concern about incivility. They suggest that fear of crime is trig gered by a broad range of neighborhood condi...

Perceived usefulness of information: a psychometric examination*

Abstract: The perceived usefulness of information is an important construct for the design of management information systems. Yet an examination of existing measures of perceived usefulness shows that the instruments developed have not been validated nor has their reliability been verified. In this paper a new instrument for measuring two dimensions of perceived usefulness is developed. The results of an empirical study designed to test the reliability and construct validity of this instrument in a capital-budgeting setting are presented.

Distributional and Procedural Aspects of Satisfaction With Citizen-Police Encounters

Abstract: Using data from a survey of a sample of the residents of Evanston, Illinois, the hypothesis of Thibaut and Walker—that the procedures utilized to resolve a dispute have an impact upon satisfaction that is independent of outcomes received—is tested in the context of police-citizen encounters, It is found that when citizens call the police for assistance or are stopped by the police, their perception of the fairness of their treatment by the police has an impact upon their satisfaction with the police that is independent of whether the police: (1) solve the problem about which the citizen calls; or (2) cite the citizen they have stopped for a violation of the law. These findings suggest that issues of procedural justice have a much broader range of applicability than to the courtroom settings within which they have previously been studied.

Reviewing the literature: A comparison of traditional methods with meta-analysis.

Abstract: Meta-analysis is the name given to a set of techniques for reviewing research in which the data from different studies are statistically combined. Meta-analysts have criticized the more traditional qualitative methods of review on three principal grounds: (1) that relevant information is ignored in favor of a simplistic box count of the number of studies in which a particular relationship is and is not statistically significant; (2) that the sample of studies for review often contains important biases; and (3) that box counts ignore statistical interactions. Our discussion suggests that these criticisms are not intrinsic to qualitative reviews, but rather represent poor practices by reviewers using traditional methods. Moreover, although meta-analysis has some advantages, it is not without its unique limitations. Our comparison of both methods is applied to the qualitative literature review of Zuckerman (1979) and the meta-analysis of Arkin, Cooper, and Kolditz (1980) which reached different conclusions about the “existence” of self-serving attributions in studies of interpersonal influence.

The marketing of social causes: the first 10 years.

Abstract: The application of marketing to the promotion of social causes was proposed a decade ago. The authors position social marketing as an approach to social change, describe its evolution, and review s...

Renewal of taste bud cells in rat circumvallate papillae.

Abstract: The life span of taste bud cells in rat circumvallate papillae was measured by autoradiography after labeling them with a pulse of [3H]thymidine. Specimens of circumvallate papillae were taken daily 1.5-18.5 days after the isotope was administered; thereafter, specimens were taken on alternate days until 25.5 days. For each time interval, the number of labeled cell nuclei was counted in 200-450 taste buds and plotted as the ratio of labeled cells/taste bud v. time faster injection of [3H]TdR. In all, 6958 taste buds were counted. The total number of labeled cells (dark plus light) per taste bud reached peaks at 6.5, 13.5 and 20.5 days. The curve for the number of labeled dark cells/bud had essentially the same shape as that for total cells. The number of labeled light cells/bud reached a modest peak at 6.5 days and slowly declined to a plateau for the remainder of the experiment. The data show that an average of 2 days elapsed after injection before labeled dark cells entered the bud and they spent an average of 7 days in the non-proliferating taste bud compartment; thus, the life span of the dark cell was 9 days. The life span of the light cell was difficult to estimate quantitatively, but this cell type was labeled at a much slower rate than dark cells and is assumed to have a signifcantly longer tenure in the taste bud.

Pituitary Gonadotropin-Releasing Hormone Receptors during the Rat Estrous Cycle

Abstract: The binding of [6-alanine]gonadotropin-releasing hormone to pituitary plasma membranes increased threefold between metestrus and early proestrus in female rats. Receptor numbers fell rapidly on the afternoon of proestrus coincident with the preovulatory gonadotropin surge. The numbers of receptors for gonadotropin-releasing hormone were positively correlated with concentrations of estradiol in serum; this pattern may be a necessary component of increased pituitary sensitivty to gonadotropin-releasing hormone observed during proestrus.

Moving contact lines and rivulet instabilities. Part 1. The static rivulet

Abstract: A rivulet is a narrow stream of liquid located on a solid surface and sharing a curved interface with the surrounding gas. Capillary instabilities are investigated by a linearized stability theory. The formulation is for small, static rivulets whose contact (common or three-phase) lines (i) are fixed, (ii) move but have fixed contact angles or (iii) move but have contact angles smooth functions of contact-line speeds. The linearized stability equations are converted to a disturbance kinetic-energy balance showing that the disturbance response exactly satisfies a damped linear harmonic-oscillator equation. The ‘damping coefficient’ contains the bulk viscous dissipation, the effect of slip along the solid and all dynamic effects that arise in contact-line condition (iii). The ‘spring constant’, whose sign determines stability or instability in the system, incorporates the interfacial area changes and is identical in cases (ii) and (iii). Thus, for small disturbances changes in contact angle with contact-line speed constitute a purely dissipative process. All the above results are independent of slip model at the liquid–solid interface as long as a certain integral inequality holds. Finally, sufficient conditions for stability are obtained in all cases (i), (ii) and (iii).