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Showing papers by "Northwestern University published in 1984"


ReportDOI
TL;DR: This paper developed a forecasting procedure based on a Bayesian method for estimating vector autoregressions, which is applied to 10 macroeconomic variables and is shown to improve out-of-sample forecasts relative to univariate equations.
Abstract: This paper develops a forecasting procedure based on a Bayesian method for estimating vector autoregressions. The procedure is applied t o 10 macroeconomic variables and is shown to improve out-of-sample forecasts relative to univariate equations. Although cross-variable responses are damped by the prior, considerable interaction among the variables is shown to be captured by the estimates We provide unconditional forecasts as of 1982:12 and 1983:3. We also describe how a model such as this can be used to make conditional projections and to analyze policy alternatives. As an example, we analyze a Congressional Budget Office forecast made in 1982: 12 Although no automatic causal interpretations arise from models like ours, they provide a detailed characterization of the dynamic statistical interdependence of a set of economic variables, information that may help in evaluating causal hypotheses without containing any such hypotheses.

1,539 citations


Journal ArticleDOI
TL;DR: In this paper, the authors construct a pair of linear examples to study the collapse time of a fixed exchange-rate regime and derive a stochastic model for the same problem.

1,412 citations


Journal ArticleDOI
TL;DR: In this paper, an analysis of when it will be beneficial for agents engaged in the production of information to form coalitions is presented, cast in a financial market framework, thus leading to an identification of conditions sufficient for the existence of financial intermediaries.
Abstract: This paper is an analysis of when it will be beneficial for agents engaged in the production of information to form coalitions. The model is cast in a financial market framework, thus leading to an identification of conditions sufficient for the existence of financial intermediaries. Intermediation is shown to improve welfare if informational asymmetries are present, and the information generated to rectify these asymmetries is potentially unreliable. The usual appeal to transactions costs to explain intermediation is not needed.

1,148 citations


Journal ArticleDOI
TL;DR: In this paper, a model of distribution-manufacturer working relationships from the perspective of social exchange theory and channels of distribution is presented, based upon work from social exchange theories and channels.
Abstract: Building upon work from social exchange theory and channels of distribution, a model of distributor-manufacturer working relationships from the distributor's perspective is presented. An initial em...

1,122 citations


Journal ArticleDOI
15 Jun 1984-Science
TL;DR: The expression of T and TnAntigens has pathogenic and clinical consequences, and the antigens themselves are powerful histological markers in carcinoma diagnosis and frequently in prognosis.
Abstract: Primary and metastatic carcinomas are epithelial in origin and comprise by far the largest group of malignant tumors in humans. In most of these tumors, T and Tn antigens, whose epitopes have been synthesized, are uncovered and immunoreactive. In all other tissues T and Tn antigens are masked and not accessible to the immune system; they are generally precursors in normal complex carbohydrate chains. Thus, carcinomas have antigens recognized as foreign by the patients' immune system. The expression of T and Tn antigens has pathogenic and clinical consequences, and the antigens themselves are powerful histological markers in carcinoma diagnosis and frequently in prognosis. Most patients distinguish their carcinoma from all other cells, as shown by strong autoimmune responses to T antigen. These responses are readily measured by assays, and they allow detection of carcinomas with greater sensitivity and specificity frequently earlier than previously possible. Moreover, the extent of T and Tn expression often correlates with carcinoma differentiation; on a molecular level, clustered T- and Tn-active structures on carcinoma cell surfaces may be involved in invasion.

976 citations




Journal ArticleDOI
TL;DR: In this paper, the authors discuss the suitability of linear regression and structural equation methods for ordinal variables in the sociological literature when some variables are ordinal, and discuss the use of ordinal dependent and independent variables into structural equation models in a way that explicitly recognizes their ordinality.
Abstract: Most discussions of ordinal variables in the sociological literature debate the suitability of linear regression and structural equation methods when some variables are ordinal. Largely ignored in these discussions are methods for ordinal variables that are natural extensions of probit and logit models for dichotomous variables. If ordinal variables are discrete realizations of unmeasured continuous variables, these methods allow one to include ordinal dependent and independent variables into structural equation models in a way that (I) explicitly recognizes their ordinality, (2) avoids arbitrary assumptions about their scale, and (3) allows for analysis of continuous, dichotomous, and ordinal variables within a common statistical framework. These models rely on assumed probability distributions of the continuous variables that underly the observed ordinal variables, but these assumptions are testable. The models can be estimated using a number of commonly used statistical programs. As is illustrated by an empirical example, ordered probit and logit models, like their dichotomous counterparts, take account of the ceiling andfloor restrictions on models that include ordinal variables, whereas the linear regression model does not. Empirical social research has benefited during the past two decades from the application of structural equation models for statistical analysis and causal interpretation of multivariate relationships (e.g., Goldberger and Duncan, 1973; Bielby and Hauser, 1977). Structural equation methods have mainly been applied to problems in which variables are measured on a continuous scale, a reflection of the availability of the theories of multivariate analysis and general linear models for continuous variables. A recurring methodological issue has been how to treat variables measured on an ordinal scale when multiple regression and structural equation methods would otherwise be appropriate tools. Many articles have appeared in this journal (e.g., Bollen and Barb,

694 citations


Journal ArticleDOI
TL;DR: It is shown that the genetic variance/covariance matrix of quantitative genetic theory measures developmental constraints due to internal selection and non-random mutation, and microevolutionary theory takes account of developmental constraints on evolution by natural selection through the genetic Variance/Covariances matrix.

666 citations


Journal ArticleDOI
TL;DR: In this article, a finite element formulation and algorithm for the nonlinear analysis of the large deflection, materially nonlinear response of impulsively loaded shells is presented, which can treat about 200 element-time-steps per CPU second on a CYBER 170/730 computer in the explicit time integration mode.

617 citations


Journal ArticleDOI
TL;DR: In this article, it is shown that failure occurs by progressive distributed damage during which the material exhibits strain-softening, i.e., a gradual decline of stress at increasing strain.
Abstract: In heterogeneous materials such as concretes or rocks, failure occurs by progressive distributed damage during which the material exhibits strain‐softening, i.e., a gradual decline of stress at increasing strain. It is shown that strain‐softening which is stable within finite‐size regions and leads to a nonzero energy dissipation by failure can be achieved by a new type of nonlocal continuum called the imbricate continuum. Its theory is based on the hypothesis that the stress depends on the change of distance between two points lying a finite distance apart. This continuum is a limit of a discrete system of imbricated (regularly overlapping) elements which have a fixed length, l, and a cross‐section area that tends to zero as the discretization is refined. The principal difference from the existing nonlocal continuum theory is that the equation of motion involves not only the averaging of strains but also the averaging of stress gradients. This assures that the finite element stiffness matrices are symmet...

Journal ArticleDOI
TL;DR: In this article, the authors propose a theoretical framework for understanding and integrating people's and animals' covariation assessment, which is determined by the interaction between two sources of information: the organism's prior expectations about the covariation between two events and current situational information provided by the environment about the objective contingency between the events.
Abstract: In this article, we propose a theoretical framework for understanding and integrating people's and animals' covariation assessment. We argue that covariation perception is determined by the interaction between two sources of information: (a) the organism's prior expectations about the covariation between two events and (b) current situational information provided by the environment about the objective contingency between the events. Both accuracies and errors in people's and animals' covariation assessments are analyzed within this interactional theoretical framework. We then review four lines of research in support of this analysis. Finally, we consider the issue of accuracy versus rationality in covariation assessment. A consensus has been forming among learning, clinical, and social psychologists: The ability to detect the relationships or covariations among stimuli, behaviors, and outcomes in one's environment is an important component of adaptive behavior. The covariation between two events may be defined in terms of their co-occurrence (i.e., the degree to which one event occurs more often in the presence than in the absence of the other event). Information about the relationships or covariations between events in the world provides people and animals with a means of explaining the past, controlling the present, and predicting the future, thereby maximizing the likelihood that they can obtain desired outcomes and avoid aversive ones. The concept of covariation provides a cornerstone for a number of substantive areas within psychology. For example, contemporary learning theorists point to the role of ob

Journal ArticleDOI
TL;DR: In this paper, Vygotsky's ideas about the zone of proximal development are elucidated and extended by inclusion of the theoretical constructs of situation definition, intersubjectivity, and semiotic mediation.
Abstract: Vygotsky's ideas about the zone of proximal development are elucidated and extended by inclusion of the theoretical constructs of situation definition, intersubjectivity, and semiotic mediation.


Journal ArticleDOI
08 Mar 1984-Nature
TL;DR: The results suggest that the photoreceptive system mediating entrainment is markedly different from that involved in visual image formation, and the reciprocal relationship between intensity and duration holds for extremely long durations.
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.


Journal ArticleDOI
TL;DR: In this paper, a mesh stabilization technique for controlling the hourglass modes in under-integrated hexahedral and quadrilateral elements is described, based on simple requirements that insure the consistency of the finite element equations in the sense that the gradients of linear fields are evaluated correctly.

Journal ArticleDOI
TL;DR: In this article, the phosphazene polymer (NP(OC2H40C2H4OCH3)n, MEEP, was synthesized and amorphous solvent-free salt complexes were performed with LiSo3CF3, NaSO3 CF3, Sr(SO 3CF3)2, and AgSO3cf3.25.
Abstract: : The phosphazene polymer (NP(OC2H40C2H4OCH3)n, MEEP, was synthesized and amorphous solvent-free salt complexes were performed with LiSo3CF3, NaSO3CF3, Sr(SO3CF3)2, and AgSO3CF3. A material with the composition (LiSO3CF3)0.25. MEEP has a conductivity of .00008 ohm/cm at 30 C, which is much higher than corresponding poly (ethylene oxide) complexes. The phosphazene electrolytes are promising materials for ambient-temperature high energy density batteries.

Journal ArticleDOI
TL;DR: In this paper, the authors propose that good design can enhance products, environment, communications, and corporate identity, and that design is a potent strategic tool that companies can use to gain a sustainable competitive advantage.
Abstract: Design is a potent strategic tool that companies can use to gain a sustainable competitive advantage. Yet most companies neglect design as a strategy tool. What they don't realize is that good design can enhance products, environment, communications, and corporate identity.

Journal ArticleDOI
TL;DR: In this article, Weinert, Wimmer, and Freeman have developed an all-electron full-potential linearized augmented plane wave (FLAPW) method for bulk solids, which solves the Kohn-Sham equations for a general charge density and potential.
Abstract: The development of the all-electron full-potential linearized augmented-plane-wave (FLAPW) method for bulk solids is reported. As in the thin-film FLAPW approach, the bulk FLAPW method solves the Kohn-Sham equations for a general charge density and potential. The formalism of Weinert, Wimmer, and Freeman for determining highly accurate total energies of solids within density-functional theory is implemented with all the necessary terms obtained from the FLAPW energy-band calculation. The resulting total-energy FLAPW approach is used to obtain highly accurate total-energy curves for bcc and fcc tungsten from which a number of structural properties (lattice parameters, bulk moduli, etc.) are derived. Calculated total energies have a relative precision of 0.1 mRy; a difference of 34 mRy is found between the (stable) bcc and fcc phases. The use of a simple quadratic form near the equilibrium value of the atomic volume is shown to lead to relatively large errors for the bulk modulus. Finally it is shown that in this all-electron method, all numerical approximations are controlled in that their effects can be minimized. One can therefore conclude that the FLAPW method is very well suited for testing the quality of various implementations of density-functional theory.


Journal ArticleDOI
01 Sep 1984-Networks
TL;DR: The goal is to find interesting cases for which the solution can be obtained without the explicit construction of the entire visibility graph, which solve the problems by constructing the shortest-path tree from the source to all the vertices of the obstacles and to the destination.
Abstract: In this paper we address the problem of constructing a Euclidean shortest path between two specified points (source, destination) in the plane, which avoids a given set of barriers. This problem had been solved earlier for polygonal obstacles with the aid of the visibility graph. This approach however, has an Ω(n2) time lower bound, if n is the total number of vertices of the obstacles. Our goal is to find interesting cases for which the solution can be obtained without the explicit construction of the entire visibility graph. The two cases are (i) the path must lie within an n-vertex simple polygon; (ii) the obstacles are n disjoint and parallel line segments. In both instances greedy O(n log n) time algorithms can be developed which solve the problems by constructing the shortest-path tree from the source to all the vertices of the obstacles and to the destination.

Journal ArticleDOI
TL;DR: In this paper, a continuous reactor based on the fluidized bed technique was developed in order to study the kinetics and the mechanisms of the initial stages of weathering of albite.

Journal ArticleDOI
TL;DR: Trois et al. as mentioned in this paper mettent a l'epreuve l'hypothese de l'impact impersonnel (limitation of l'influence des mass media sur les jugements lies au risque lorsqu'ils sont emis au niveau de la societe).
Abstract: Trois etudes mettent a l'epreuve l'hypothese de l'impact impersonnel (limitation de l'influence des mass media sur les jugements lies au risque lorsqu'ils sont emis au niveau de la societe) aupres de plusieurs centaines de sujet devant repondre au niveau de la societe et au niveau personnel a un questionnaire portant sur les risques exposes dans une sequence televisee

Journal ArticleDOI
TL;DR: In this paper, a method for constructing all Pareto-optimal allocations for a dynamic economy with many heterogeneous consumers, under certainty, in which both the technology and consumer preferences are recursive but preferences need not be additively separable over time.

Journal ArticleDOI
TL;DR: In this article, the authors explore the role of perceived injustice in generating dissatisfaction with legal authorities and compare the influence of case outcomes upon attitudes toward judges and courts to that of distributive and procedural justice.
Abstract: The purpose of this study is to explore the role of perceived injustice in generating dissatisfaction with legal authorities. Using data collected in interviews with a sample of defendants in traffic and misdemeanor court, I compare the influence of case outcomes upon attitudes toward judges and courts to that of distributive and procedural justice. The results suggest that among the defendants studied the major determinant of satisfaction with legal authorities is perceived fairness. Once the influence of perceived fairness is considered, case outcomes explain no additional variation in attitudes toward courts and judges. In the conclusion, possible implications of this finding are discussed.

Journal Article
TL;DR: It is demonstrated that TAM are potent stimulators of neovascularization and endothelial cell proliferation and that depletion of macrophages from tumor cell suspensions significantly decreased their angiogenic potential.

Journal ArticleDOI
TL;DR: In this paper, a common belief among marketing practitioners is that increasing the vividness of a message enhances its persuasiveness, and this belief has received support in experimental investigations, but vividness has not yet been shown to improve the effectiveness of marketing messages.
Abstract: A common belief among marketing practitioners is that increasing the vividness of a message enhances its persuasiveness. This belief has received support in experimental investigations, but vividne...

Journal ArticleDOI
TL;DR: Recovery of visual function included a dramatic improvement in ERG and ERP amplitudes over several weeks, and there is no definite evidence of systemic involvement in patients with unilateral ocular findings.
Abstract: • We examined 11 young patients with unilateral ocular findings that included multiple white dots at the level of the retinal pigment epithelium (RPE) or the deep retina, vitreal cells, RPE granularity in the macula, reduced visual acuity, electroretinogram (ERG) and early receptor potential (ERP) amplitudes, and fluorescein leakage from disc capillaries and late staining of the RPE. Recovery of visual function included a dramatic improvement in ERG and ERP amplitudes over several weeks. The etiology of this syndrome remains uncertain; there is no definite evidence of systemic involvement.

Journal ArticleDOI
15 May 1984-Cancer
TL;DR: The results suggest that warfarin, as a single anticoagulant agent, may favorably modify the course of some, but not all, types of human malignancy, among which is small cell carcinoma of the lung.
Abstract: VA Cooperative Study #75 was established to test in a controlled, randomized trial the hypothesis that warfarin anticoagulation would favorably affect the course of certain types of malignancy. No differences in survival were observed between warfarin-treated and control groups for advanced non-small cell lung, colorectal, head and neck and prostate cancers. However, warfarin therapy was associated with a significant prolongation in the time to first evidence of disease progression (P = 0.016) and a significant improvement in survival (P = 0.018) for patients with small cell carcinoma of the lung, including the subgroup of patients with disseminated disease at the time of randomization (P = 0.013). A trend toward improved survival with warfarin treatment was observed for the few patients admitted to this study with non-small cell lung cancer who had minimal disease at randomization. These results suggest that warfarin, as a single anticoagulant agent, may favorably modify the course of some, but not all, types of human malignancy, among which is small cell carcinoma of the lung. Further trials of warfarin may be indicated in patients with limited disease who have cell types that failed to respond when advanced disease was present.