Showing papers by "University of Minnesota published in 1987"

A foundation for the study of group decision support systems

Abstract: Technical developments in electronic communication, computing, and decision support, coupled with new interest on the part of organizations to improve meeting effectiveness, are spurring research in the area of group decision support systems GDSS. A GDSS combines communication, computing, and decision support technologies to facilitate formulation and solution of unstructured problems by a group of people. This paper presents a conceptual overview of GDSS based on an information-exchange perspective of decision making, Three levels of systems are described, representing varying degrees of intervention into the decision process. Research on GDSS is conceived as evolving over time from the study of simple "shell" systems, consisting of menus of features available for selection by a group, to consideration of sophisticated rule-based systems that enable a group to pursue highly structured and novel decision paths. A multi-dimensional taxonomy of systems is proposed as an organizing framework for research in the area. Three environmental contingencies are identified as critical to GDSS design: group size, member proximity, and the task confronting the group. Potential impacts of GDSS on group processes and outcomes are discussed, and important constructs in need of study are identified.

Fine phase mixtures as minimizers of energy

Abstract: Solid-solid phase transformations often lead to certain characteristic microstructural features involving fine mixtures of the phases. In martensitic transformations one such feature is a plane interface which separates one homogeneous phase, austenite, from a very fine mixture of twins of the other phase, martensite. In quartz crystals held in a temperature gradient near the α-β transformation temperature, the α-phase breaks up into triangular domains called Dauphine twins which become finer and finer in the direction of increasing temperature. In this paper we explore a theoretical approach to these fine phase mixtures based on the minimization of free energy.

The agent-structure problem in international relations theory

Abstract: While neorealism and world-system theory both claim to be “structural” theories of international relations, they embody very different understandings of system structure and structural explanation. Neorealists conceptualize system structures in individualist terms as constraining the choices of preexisting state agents, whereas world-system theorists conceptualize system structures in structuralist terms as generating state agents themselves. These differences stem from what are, in some respects, fundamentally opposed solutions to the “agent-structure” or “micromacro” problem. This opposition, however, itself reflects a deeper failure of each theory to recognize the mutually constitutive nature of human agents and system structures—a failure which leads to deep-seated inadequacies in their respective explanations of state action. An alternative solution to the agent-structure problem, adapted from “structuration theory” in sociology, can overcome these inadequacies by avoiding both the reduction of system structures to state actors in neorealism and their reification in world-system theory. Structuration theory requires a philosophical basis in scientific realism, arguably the “new orthodoxy” in the philosophy of natural science, but as yet largely unrecognized by political scientists. The scientific realist/structuration approach generates an agenda for “structural-historical” research into the properties and dispositions of both state actors and the system structures in which they are embedded.

Marketing's Interaction with Other Functional Units: A Conceptual Framework and Empirical Evidence:

Abstract: The authors develop a framework for examining how and why marketing personnel interact with personnel in other functional areas in planning, implementing, and evaluating marketing activities. Build...

Key issues in information systems management

Abstract: The results from a five-part Delphi survey of chief IS executives and corporate general managers indicate the most critical information systems management issues and consensus on their importance. The research project is the second in a series of such studies conducted by the Society for Information Management and the MIS Research Center at the University of Minnesota. The research confirmed the expected in some areas and revealed surprises in other areas. While strategic planning continued to top all issue sin importance, many changes have occurred since 1983. Three new issues have joined the top ten issues in importance. Also, the rank order of several issues in the top ten has shifted. Survey results are discussed in terms of the differing views of IS executives and corporate general managers. A review of how these views have changed over time is also presented. A number of conclusions are drawn about managing information systems and about the changing nature of the IS executive's job.

Marketing's Role in the Implementation of Business Strategies: A Critical Review and Conceptual Framework:

Abstract: The authors review and integrate various theoretical perspectives, normative statements, and pieces of empirical evidence about the organizational structures and processes best suited for implement...

Leisure-time physical activity levels and risk of coronary heart disease and death. The Multiple Risk Factor Intervention Trial.

Abstract: The relation of self-selected leisure-time physical activity (LTPA) to first major coronary heart disease (CHD) events and overall mortality was studied in 12 138 middle-aged men participating in the Multiple Risk Factor Intervention Trial. Total LTPA over the preceding year was quantitated in mean minutes per day at baseline by questionnaire, with subjects classified into tertiles (low, moderate, and high) based on LTPA distribution. During seven years of follow-up, moderate LTPA was associated with 63% as many fatal CHD events and sudden deaths, and 70% as many total deaths as low LTPA ( P P ( JAMA 1987;258:2388-2395)

Sex-biased dispersal and inbreeding avoidance in birds and mammals.

Abstract: Sex differences in dispersal distance are widespread in birds and mammals, but the predominantly dispersing sex differs consistently between the classes There has been persistent debate over the relative importance of two factors — intrasexual competition and inbreeding avoidance — in producing sex-biased dispersal, and over the sources of the difference in dispersal patterns between the two classes Recent studies cast new light on these questions

Primary sensory neurons of the rat showing calcitonin gene-related peptide immunoreactivity and their relation to substance P-, somatostatin-, galanin-, vasoactive intestinal polypeptide- and cholecystokinin-immunoreactive ganglion cells.

Abstract: By use of the indirect immunofluorescence technique the distribution of calcitonin gene-related peptide (CGRP)-like immunoreactivity (LI) has been analyzed in cervical and lumbar dorsal root ganglia of untreated and colchicine-treated rats. In addition, lumbar ganglia were examined 2 weeks after transection of the sciatic nerve. The occurrence of CGRP-positive cells in relation to ganglion cells containing substance P-, somatostatin-, galanin-, cholecystokinin (CCK)-, and vasoactive intestinal polypeptide (VIP)/peptide histidine isoleucin (PHI)-LI has been evaluated on consecutive sections as well as using elution-restaining and double-staining techniques.

Item Clusters and Computerized Adaptive Testing: A Case for Testlets

Abstract: It is observed that many sorts of difficulties may preclude the uneventful construction of tests by a computerized algorithm, such as those currently in favor in Computerized Adaptive Testing (CAT). In this essay we discuss a number of these problems, as well as some possible avenues of solution. We conclude with the development of the "testlet," a bundle of items that can be arranged either hierarchically or linearly, thus maintaining the efficiency of an adaptive test while keeping the quality control of test construction that is possible currently only with careful expert scrutiny. Performance on the separate testlets is aggregated to yield ability estimates. In the old days of testing a wise examiner confronted a nervous examinee and asked questions. After getting some initial idea of the examinee's ability or knowledge level, the examiner would not waste time asking questions that were too difficult or too easy. Instead, he or she would focus questions on the area around the examinee's proficiency level. This made for a challenging and efficient test. It was also subjective and expensive. This state of affairs changed during the First World War with the Army Alpha. The mass processing of recruits into the armed services demonstrated that standardized tests could make the training and accessioning process more efficient. Substituting for the wise examiner was a broad-range test made up of many multiple-choice questions. This had several advantages, among which were its vastly reduced cost per unit and its objectivity-everyone took the same test, and it was scored in the same way for everyone. It also had some disadvantages. As a written document, a test form could be stolen, and because of its broad audience it had to contain items that would tax the least able of the prospective

An enthalpy method for convection/diffusion phase change

Abstract: An enthalpy formulation for convection/diffusion phase change is developed. The essential feature of this formulation is that latent heat effects are isolated in a source term. This formulation is applicable to a general convection/diffusion phase change, i.e. it is valid in the cases of evolution of latent heat either at an isothermal temperature or over a temperature range. Before implementation of the enthalpy formulation, a technique is required to ensure that velocities predicted to be in a solid region actually take the value zero. Three alternative schemes for achieving this are presented. The enthalpy formulation and velocity correction schemes are independent of the numerical technique. As an example of how the method can be implemented a control volume numerical discretization is chosen. This implementation is applied to two test problems: a solidification phase change in a cavity under conduction and the same phase change under conduction and natural convection. The natural convection problem is used to compare the performances of the various velocity correction schemes. The results of the problems are in good agreement with available analytical solutions and previous numerical solutions.

Multiple recurrent genomic defects in follicular lymphoma. A possible model for cancer.

Abstract: Several steps in the clinical evolution of human neoplasia are associated with a variety of recurrent chromosomal defects that could prove essential to the understanding of cancer. We found 15 types of nonrandom chromosomal abnormalities in a study of 71 patients with follicular lymphoma; 10 of the types appeared to influence the histopathological findings, clinical course, or response to treatment. A translocation, t(14;18), observed in 85 percent of all patients appeared to be the main determinant of a follicular pattern. Ten patients with a t(14;18) as a single defect had the histologic features of follicular small cleaved-cell lymphoma. Most did not require treatment for one to four years, because their tumors had an initial indolent course. In contrast, patients with follicular small cleaved-cell lymphoma with t(14;18) and deletion 13q32 acquired the hematologic features of leukemia and had an acceleration of the disease. A deletion 6q together with a complete or partial trisomy 7 or trisomy 12 (or both) was associated with the clinically more aggressive follicular mixed small- and large-cell or large-cell histologic type, which often evolves from follicular small-cell lymphoma. A complete or partial trisomy 3, 18, or 21 correlated almost exclusively with follicular large-cell lymphoma. In all follicular stages, a trisomy 2 or duplication 2p often accompanied an accelerated clinical course and a poor response to treatment. This study suggests that several discrete genomic defects may govern the evolution of a patient's malignant disease.

A human major histocompatibility complex class i gene that encodes a protein with a shortened cytoplasmic segment

Abstract: We have cloned genomic DNA encoding a non-HLA-A, -B, -C class I gene located within a HindIII-generated restriction fragment of 6.0 kilobase pairs. This gene, designated HLA-6.0, is as homologous to HLA-A and HLA-B as they are to each other. The HLA class I protein encoded by HLA-6.0 is similar in organization to the HLA-A-, -B-, and -C-encoded proteins except that an in-frame termination codon prevents translation of a majority of the cytoplasmic region of the HLA-6.0 polypeptide. Moreover, the promoter region of HLA-6.0 resembles the promoter region of a Qa region gene. These structural features of HLA-6.0 suggest that this non-HLA-A, -B, -C gene is a structural homolog of a murine Qa region class I gene.

The impact of cumulative change in early adolescence.

Abstract: This article examines the impact of experiencing several major life transitions simultaneously in early adolescence For many children, entry into the new life period of adolescence is marked by the transition from a relatively intimate elementary school setting into a more complex, impersonal junior high school environment This major shift in organizational context is often accompanied by dramatic changes in biology and social definition We hypothesized that transitions will be easier for children to cope with if the various adolescent changes come into focus at different stages rather than simultaneously In a longitudinal study conducted in a large Midwestern city, schoolchildren were followed from sixth into seventh grade in 2 different types of school systems The effect of multiple life changes (school transition, pubertal development, early dating behavior, residential mobility, family disruption) on students' self-esteem, academic grade-point average, and participation in extracurricular activities was analyzed The results identify children who are forced to cope with several life transitions concurrently as a group at risk Theoretical implications are discussed, with development of the notion that individuals need an "arena of comfort" in at least some spheres of their lives

Constrained Global Optimization: Algorithms and Applications

Abstract: Convex sets and functions.- Optimality conditions in nonlinear programming.- Combinatorial optimization problems that can be formulated as nonconvex quadratic problems.- Enumerative methods in nonconvex programming.- Cutting plane methods.- Branch and bound methods.- Bilinear programming methods for nonconvex quadratic problems.- Large scale problems.- Global minimization of indefinite quadratic problems.- Test problems for global nonconvex quadratic programming algorithms.

With the Boys: Little League Baseball and Preadolescent Culture

Abstract: What are boys like? Who is the creature inhabiting the twilight zone between the perils of the Oedipus complex and the Strum und Drang of puberty? In With the Boys, Gary Alan Fine examines the American male preadolescent by studying the world of Little League baseball. Drawings on three years of firsthand observation of five Little Leagues, Fine describes how, through organized sport and its accompanying activities, boys learn to play, work, and generally be "men."

Advances in our understanding of thyroid hormone action at the cellular level.

Abstract: Introduction DESPITE the fact that the clinical and biological importance of the thyroid hormones have been recognized for approximately 100 yr (1–3), until recently our understanding of the biological effects of these hormones has been largely descriptive and based on a catalog of effects observed to accompany an excess or deficiency of these hormones. In the past 15 yr, however, there has been substantial progress in defining the molecular basis of thyroid hormone action at the nuclear level. In the mid-60s Tata and colleagues (4, 5) first proposed that the nucleus might be the target for thyroid hormone action. This inference was based on sequential measurements of thyroid hormone effects in thyroidectomized animals treated with T4. Nevertheless, the importance and uniqueness of this pathway were not fully appreciated (6). Full understanding of the nuclear site of initiation of thyroid hormone action was dependent on the recognition that T3 was the active hormone, that T4 largely served as a precursor ...

Victimization Among Preschoolers: Role of Attachment Relationship History

Abstract: The association between preschool children's attachment history and a relational pattern labeled “victimization” was examined. The sample consisted of 38 children 4 to 5 years of age. These children were assigned to pairs and observed during a series of free play interactions. The pairings included various combinations of secure and anxious attachment histories. These dyads were rated for the presence or absence of victimization. Results showed that victimization could be reliably identified and was clearly associated with attachment history. Furthermore, the presence of a child with an “avoidant” attachment history was associated with victimization and the presence of a child with a “secure” attachment history was associated with nonvictimization.

Nociceptive action of excitatory amino acids in the mouse: effects of spinally administered opioids, phencyclidine and sigma agonists.

Abstract: Intrathecal administration of the excitatory amino acid (EAA) agonists, N-methyl-D-aspartate (NMDA), quisqualate (Quis) or kainic acid (KA), in the spinal subarachnoid space of mice produced a dose-related biting and scratching behavior. Higher doses appeared aversive, suggesting a nociceptive action for EAAs in the spinal cord. Intrathecally administered NMDA, but not Quis or KA, produced a hyperalgesic effect in the tail-flick and hot-plate tests. To test the hypothesis that EAA agonists are involved in transmission of nociceptive information in the spinal cord, we tested the effect of various opioid, sigma and phencyclidine compounds on the action of NMDA in the tail-flick, hot-plate and biting and scratching nociceptive tests. Our results indicated that the involvement of mu, sigma and phencyclidine receptors was predominant in blockade of the behavioral and hyperalgesic effects of intrathecally administered NMDA. Delta receptors appeared less involved, and involvement of kappa receptors was not detectable in blockade of the behavioral and hyperalgesic effects of intrathecally administered NMDA. Quis and KA effects were not altered by any of these agonists. Agonist doses required to inhibit NMDA-induced hyperalgesia in the tail-flick and hot-plate tests were significantly less than those needed to inhibit biting and scratching behavior. The adrenergic agonist norepinephrine inhibited NMDA- but not Quis- or KA-induced biting and scratching behavior. This action appeared to be alpha-1 mediated because it was reversed by phentolamine but not by yohimbine. These results suggest that the actions of EAAs in the spinal cord are differentially affected by various opioid phencyclidine, sigma and adrenergic receptor agonists and support the hypothesis that EAAs are involved in the transmission of nociceptive information in the spinal cord.

Optical Flow Estimation: An Error Analysis of Gradient-Based Methods with Local Optimization

Abstract: Multiple views of a scene can provide important information about the structure and dynamic behavior of three-dimensional objects. Many of the methods that recover this information require the determination of optical flow-the velocity, on the image, of visible points on object surfaces. An important class of techniques for estimating optical flow depend on the relationship between the gradients of image brightness. While gradient-based methods have been widely studied, little attention has been paid to accuracy and reliability of the approach. Gradient-based methods are sensitive to conditions commonly encountered in real imagery. Highly textured surfaces, large areas of constant brightness, motion boundaries, and depth discontinuities can all be troublesome for gradient-based methods. Fortunately, these problematic areas are usually localized can be identified in the image. In this paper we examine the sources of errors for gradient-based techniques that locally solve for optical flow. These methods assume that optical flow is constant in a small neighborhood. The consequence of violating in this assumption is examined. The causes of measurement errors and the determinants of the conditioning of the solution system are also considered. By understanding how errors arise, we are able to define the inherent limitations of the technique, obtain estimates of the accuracy of computed values, enhance the performance of the technique, and demonstrate the informative value of some types of error.

Experiments on turbidity currents over an erodible bed

Abstract: Experiments were conducted to determine the behaviour of turbidity currents laden with non-cohesive silt (silica flour) moving down a slope the bed of which is covered with similar silt. Each current was sustained with constant inlet conditions for six to eight minutes. The motion of the head was not studied; measurements were concentrated on the continuous part of the current that was essentially constant in time but developing in space. Only supercritical currents were studied. The currents were free to erode sediment from, and deposit sediment on, the bed. Measurements of vertical profiles of downstream velocity and sediment concentration allowed for the development of approximate similarity relations. These relations can be used to estimate most of the shape factors that occur in the vertically-integrated equations of motion. The values do not deviate grossly from those found by using a "top-hat" function, i.e. a step function, such that velocity or concentration equals its average value in the layer ...