Showing papers by "Louisiana State University published in 1986"

The problem of rigor in qualitative research.

Abstract: There are few explicit discussions in nursing literature of how qualitative research can be made as rigorous as it is relevant to the perspective and goals of nursing. Four factors complicate the debate about the scientific merits of qualitative research: the varieties of qualitative methods, the la

A joint economic-lot-size model for purchaser and vendor

Abstract: In a typical purchasing situation, the issues of price, lot sizing, etc, usually are settled through negotiations between the purchaser and the vendor Depending on the existing balance of power, the end result of such a bargaining process may be a near-optimal or optimal ordering policy for one of the parties (placing the other in a position of significant disadvantage) or, sometimes, inoptimal policies for both parties This paper develops a joint economic-lot-size model for a special case where a vendor produces to order for a purchaser on a lot-for-lot basis under deterministic conditions The focus of this model is the joint total relevant cost It is shown that a jointly optimal ordering policy, together with an appropriate price adjustment, can be beneficial economically for both parties or, at the least, does not place either at a disadvantage

An application of the cox proportional hazards model to bank failure

Abstract: The purpose of this study is to present the Cox proportional hazards model and to apply this model to the prediction of bank failures. The Cox model, which has been used extensively in biomedical applications, has not been previously employed in the finance literature. The principal advantage of the Cox model over other classification techniques is that it models the expected time to failure. Results of the study indicate that total classification accuracy of the Cox model is similar to that of discriminant analysis, although the Cox model produces somewhat lower type I errors. In a comparison of actual and predicted times to failure, the Cox model tends to identify bankruptcies prior to the actual failure date.

Isolation of an HTLV-III-related retrovirus from macaques with simian AIDS and its possible origin in asymptomatic mangabeys

Abstract: Acquired immune deficiency syndrome (AIDS) has become a worldwide epidemic1–6, so the development of vaccines and antiviral agents effective against the causative agent, human T-lymphotropic virus type III (HTLV-III), is vital. This work would be greatly simplified if a suitable animal model could be developed. Here we report the isolation of an HTLV-III-related retrovirus, STLV-III/Delta, from rhesus macaques (Macaca mulatta) with transmissible simian AIDS (SAIDS) and from asymptomatic sooty mangabeys (Cercocebus atys). SAIDS was initially diagnosed in several macaques previously inoculated with tissue homogenates of mangabey origin. Western blot analysis of both the mangabey and macaque sera demonstrated the presence of antibody cross-reactive primarily with the HTLV-III proteins p24 and p61. In a related experiment, analysis of these same sera revealed simian antibody to STLV-III/Delta proteins similar, but not identical, to those of HTLV-III with estimated relative molecular masses (Mrs) of 16,000 (16K), 26K, 35K, 45K, 60K and 110K. Infection of the mangabey, an African primate, with an HTLV-III-related virus may provide a clue to the origin of HTLV-III in humans. The apparent difference in susceptibility to SAIDS-like disease between infected macaques and mangabeys suggests that these species may respond differently to STLV-III infection.

Predictors of the Performance of Project Groups in R & D Organizations

Abstract: Results from 32 project groups in a large R&D organization showed that group cohesiveness, physical distance, job satisfaction, and innovative orientation were associated with performance of projec...

Host-associated Genetic Differentiation in Fall Armyworm (Lepidoptera: Noctuidae): a Sibling Species Complex?

Abstract: Fall armyworm, Spodoptera frugiperda (J. E. Smith), is a major agricultural pest of many crops throughout its distribution in the Western Hemisphere. Its polyphagy has been attributed to a lack of dietary specialization. Results presented here suggest that this is not the case and that the fall armyworm is composed of genetically differentiated strains, each exhibiting different host specificity. At least two host strains exist, one that feeds on corn and another on rice and Bermuda grass. Collections from Bermuda grass in Louisiana and rice in Puerto Rico are genetically identical at 11 polymorphic enzyme loci and are significantly different from populations on corn in Puerto Rico and Louisiana at 5 loci. In a split progeny experiment in which offspring from the two host strains were reared on both corn and rice, the host plant upon which larvae fed had no influence on the genotype of survivors. Thus, genetic differences are not caused by feeding on the host plant but are inherent in the strains. If the two strains are determined to be reproductively isolated, as implicated by preliminary hybridization data, then at least two sibling species exist.

Sex Differences in Leadership: How Real Are They?

Abstract: A meta-analytic review of 17 studies examining sex differences in leadership indicates that male and female leaders exhibit equal amounts of initiating structure and consideration and have equally satisfied subordinates. Male leaders are rated as more effective than female leaders, but only in laboratory settings. A moratorium on research comparing male and female leaders on measures of initiating structure, consideration, subordinate satisfaction, and effectiveness is proposed.

Combinatorics: Set Systems, Hypergraphs, Families of Vectors and Combinatorial Probability

Abstract: Frontispiece Preface 1. Notation 2. Representing sets 3. Sperner systems 4. The Littlewood - Offord problem 5. Shadows 6. Random sets 7. Intersecting hypergraphs 8. The Turan problem 9. Saturated hypergraphs 10. Well-separated systems 11. Helly families 12. Hypergraphs with a given number of disjoint edges 13. Intersecting families 14. Factorizing complete hypergraphs 15. Weakly saturated hypergraphs 16. Isoperimetric problems 17. The trace of a set system 18. Partitioning sets of vectors 19. The four functions theorem 20. Infinite ramsey theory References Index.

Comparison of the Piso, Simpler, and Simplec Algorithms for the Treatment of the Pressure-Velocity Coupling in Steady Flow Problems

Abstract: The performance of the PISO, SIMPLER, and SIMPLEC algorithms for the treatment of the pressure-velocity coupling in steady flow problems is examined by comparing the computational effort required to obtain the same level of convergence in four test problems. For problems in which the momentum equation is not coupled to a scalar variable the PISO algorithm is superior, but when the scalar variable is strongly coupled to the momentum equation SIMPLER and SIMPLEC exhibit better behavior and reasonable solutions with the PISO algorithm are obtained only for small time steps. Clear superiority of SIMPLER over SIMPLEC or vice versa is not observed, although the iterative formulations of these two algorithms exhibit more robust behavior than the corresponding time-marching formulations.

Low-Level Segmentation of Aerial Images with Fuzzy Clustering

Abstract: A low-level segmentation methodology based upon fuzzy clustering principles is developed. The approach utilizes region growing concepts and a pyramid data structure for the hierarchical analysis of aerial images. It is assumed that measurement vectors corresponding to perceptually homogeneous regions cluster together in the measurement space. The fuzzy c-means (FCM) clustering algorithm is used in the formulation. Utilization of the fuzzy partitioning allows one to derive a correspondence between the cluster membership function values and (the proportions of) the classes constituting a region. Thus cluster membership values can be used to split mixture regions into smaller regions at a higher resolution level. The feasibility of the methodology is evaluated using a three-channel Landsat image. The results show that the FCM clustering can be used in the single-level segmentation; and that cluster membership function values derived using this algorithm can be utilized effectively as indicators of region homogeneity.

Contextual Interference Effects in Learning Three Badminton Serves

Abstract: This study investigated the generalizability of results of contextual interference effects by extending previous laboratory research to a field setting. Thirty female subjects (N = 30) learned three badminton serves in either a blocked (low interference), serial (mixed interference), or random (high interference) practice schedule. The subjects practiced the serves three days a week for three weeks. On the day following the completion of practice the subjects were given a retention and transfer test. Results replicated previous findings of contextual interference research by showing a significant group by block interaction between acquisition trials, retention, and transfer. The random group performed better on both retention and transfer than the blocked group. The significant trial block by contextual interference interaction also supports the generalizability of contextual interference effects, as posited by Shea and Morgan (1979), to the teaching of motor skills.

Conceptual and Definitional issues in the Assessment of Children's Social Skills: Implications for Classifications and Training

Abstract: Conceptual and definitional issues involved in the assessment of children's social skills are specified and developed. A distinction is made between social competence and social skill and three approaches to conceptualizing social competence are presented. Several definitions of social skill are provided and critiqued. A classification of children's social skill difficulties, based, in part, upon Bandura's (1977a) distinction between acquisition versus performance deficits, is presented. The value of establishing the social significance of social skill difficulties and assessing the social importance of the effects of social skills training is advocated.

The product enthusiast: implications for marketing strategy

Abstract: Product enthusiasts, increasingly prevalent in American society, represent significant marketplace forces because of their high levels of information seeking, opinion leadership, and innovativeness. For marketers to best serve these consumers, many commonly used marketing strategies must be altered or adapted. In this article, marketing mix elements serve as a framework to discuss strategic issues relevant to this category of consumer.

The effects of group cohesion and leader behavior on subordinate satisfaction.

Abstract: The present study examined the effects of group cohesiveness and leader behavior on subordinate satisfaction in a military organiza tion. A total of 203 cadets completed measures of group cohesiveness, leader initiating structure, leader consideration, and several satisfac tion scales. Analyses indicated that (1) subordinates were more satisfied with leaders who exhibited high levels of initiating struc ture and consideration; (2) subordinates in high-cohesiveness groups were more satisfied than subordinates in low-cohesiveness groups; and (3) leader initiating structure and consideration were more positively related to subordinate satisfaction in high-cohesiveness groups than in low-cohesiveness groups. The results demonstrate the necessity of including group process variables in leadership theory and research. Implications of the findings forgroup effectiveness are also discussed.

Economic Interdependence and International Conflict: Some Cross-national Evidence

Abstract: This study examines the relationship between economic interdependence and international conflict. Two schools of thought exist on this issue: some prominent writers suggest that interdependence produces greater international conflict, while others suggest that it produces a decline in conflict. These arguments are reviewed and empirically tested here. Previous empirical studies bearing on this issue are found to use inadequate measures and biased samples. More comprehensive analyses presented here suggest that interdependence can have mixed consequences. Several measures of interdependence that embody its costly aspects are found to be positively associated with conflict, implying that interdependence produces increased international conflict. However, when these measures are controlled for, another key measure is found to be inversely related to conflict. This suggests that both schools of thought may be correct: while the costly aspects of interdependence seem to produce greater international conflict, its beneficial aspects appear to produce a decline in conflict. In recent years, international interdependence has emerged as an important phenomenon in world poiitics and a popular concept in the international relations literature. International issues as diverse as trade embargoes, environmental degradation, nuclear arms races, and the transmission of inflation have been grouped together under the rubric of interdependence. Early writers on interdependence, such as Cooper (1968), focused mainly on the problems it creates for domestic and foreign economic policymaking. More recently, a number of studies have appeared that examine the implications of interdependence for international politics. The most influential of these has been Keohane and Nye (1977). However, other than a few studies that examine whether interdependence is increasing or declining worldwide, I no broad, comparative analyses of the impact of interdependence on international politics

Reinforcing properties of cocaine in the medial prefrontal cortex: Primary action on presynaptic dopaminergic terminals

Abstract: The presynaptic mechanisms involved in the initiation of cocaine reinforcement were investigated using neurotoxin lesions. Rats were trained to intracranially self-administer cocaine (50 to 90 pmol) into the medial prefrontal cortex and after dose-effect analyses were completed, each rat received a unilateral 6-hydroxydopamine lesion (4 micrograms in 0.2 microliter) at the self-administration site. The lesion selectively decreased dopamine content in the medial prefrontal cortex (-45%) and decreased cocaine-maintained responding to vehicle levels. Lever-pressing could be reinstated by substituting dopamine (300 pmol) but not serotonin for cocaine. Dopamine self-administration was attenuated by including equimolar concentrations of the D2 dopaminergic antagonist sulpiride in the injectate. These results suggest that the initiation of reinforcing neuronal activity in the medial prefrontal cortex appears to result in part through the direct interaction of cocaine with presynaptic reuptake sites associated with dopaminergic nerve endings. The resulting increased synaptic concentration of the neurotransmitter may then interact with postsynaptic D2 binding sites to activate neuronal systems involved in the mediation of this reinforcement.

Stromatolites from the 3,300-3,500-Myr Swaziland Supergroup, Barberton Mountain Land, South Africa

Abstract: A morphologically variable assemblage of stromatolites has been discovered in thin chert layers within the Fig Tree Group of the Swaziland Supergroup, South Africa. They are commonly low-relief, nearly stratiform, laterally linked domes. Rarer forms include pseudocolumns and crinkly stratiform stromatolites. The stromatolites grew on a substrate of altered komatiitic lava and sediments deposited on the lava surface, and in most places are covered by later komatiitic flows. Abundant fine-grained tourmaline included within the stromatolite laminae suggests that stromatolites formed in an environment dominated by boron-rich hot-spring emissions and evaporitic brines.

Mechanism of Soot Formation in Acetylene-Oxygen Mixtures

Abstract: A computational study of the chemical kinetic effects of oxygen addition on the process of soot formation from hot acetylene is reported. The results, which are supported by trends observed in shock-tube experiments, reveal that the reaction pathway to soot identified previously for acetylene pyrolysis remains essentially unchanged in an oxidative environment. The main effects of oxygen are: (1) promotion of fuel decomposition, which alters the initiation route to soot; (2) supplementary rapid production of hydrogen atoms in the initial, small-molecule reactions, which drives the concentration of hydrogen above the equilibrium value with respect to H2 and thus enhances polymeric growth of polycyclic aromatics; (3)oxidation of aromatic radicals by molecular oxygen, which removes them from the polymeric growth. The computational results indicate a crucial need for kinetic studies of high temperature reactions between molecular oxygen and hydrocarbon radicals.

A biomechanical analysis of mandibular scaling in old world monkeys

Abstract: Scaling of mandibular dimensions in male Old World monkeys was investigated. Mandibular condyle length, width, and area were regressed separately against body mass and mandibular length for a total of 14 species of Cercopithecoids. Scaling of mandibular depth and width against both body mass and mandibular length were also investigated. When results of regression analysis using the two different independent variables (body mass and mandibular length) were compared, there were significant pattern differences in scaling of cercopithecines versus colobines. Compared to body mass, male cercopithecines had relatively large mandibles (length, width, and depth) and also relatively large condyles (length, width, and area). However, compared to mandibular length, cercopithecines had relatively transversely thin and shallow mandibles and relatively narrow condyles. It is shown that a “biomechanical” interpretation of mandibular scaling patterns against body mass in Old World monkeys demonstrates only that cercopithecines have prognathic faces, an already well-known and well-documented condition. When the biomechanical effects of prognathic faces are controlled for (by scaling against mandibular length), it is shown that cercopithecines possess special adaptations in condyle length while colobines possess special adaptations in condyle width and mandibular depth and width. These results clearly demonstrate the importance of selecting a relevant reference variable in scaling studies where biomechanical interpretations are attempted.

Entity — Relationship modeling and fuzzy databases

Abstract: This work describes an integration of an entity/relationship model and fuzzy databases. It outlines a formal model for representing fuzziness in the ER model, and sketchs a version of the ER algebra, adapted to manipulating fuzzy databases.

Fresh water on the Louisiana and Texas shelf

Abstract: Hydrographic data collected on monthly cruises over the West Louisiana and Texas shelf from 1963 to 1965 were analyzed and the volume of fresh water on the shelf was estimated for each data set. The freshwater volume exhibits an annual cycle that is dominated by the spring flood of the Mississippi and Atchafalaya rivers. During the winter, shelf freshwater content is low, with the highest content appearing as a discontinuous band along the inner shelf. In summer an isolated high-content region is present in the center of the shelf. This high-content region dissipates and the pattern migrates toward the southeast in the late summer. By late fall the winter distribution is again present. A fill time for the freshwater volume on the shelf was also estimated for each cruise. The freshwater volume appears, in most cases, to have originated near the time of the previous spring flood. Two of the study years had river discharges well below the long-term mean, while the third-year discharge approximated the long-term mean. These results, then, may not be applicable to large-discharge years.

Toxoplasma Modifies Macrophage Phagosomes by Secretion of a Vesicular Network Rich in Surface Proteins

Abstract: Modification of macrophage phagosomes begins shortly after formation as Toxoplasma cells secrete membranous vesicles that form a reticulate network within the vacuole. The Toxoplasma-modified compartments then resist normal endocytic processing and digestion. We have used the pronounced Ca++-dependent stability of the intraphagosomal membrane (IPM) network to purify and characterize the structural proteins of this assembly. In addition to the structural matrix, Toxoplasma secretes a discrete set of soluble proteins, including a newly described 22-kD calcium-binding protein. The IPM network adheres to intact Toxoplasma cells after host cell lysis in the presence of 1 mM Ca++; however, the network readily disperses in calcium-free buffer and was purified as vesicles that sedimented at 100,000 g. Purified IPM vesicles were specifically recognized by immune sera from mice with chronic Toxoplasma infection and consisted primarily of a 30-kD protein when analyzed by SDS PAGE. IPM network proteins share a major antigenic component located on the surface of extracellular Toxoplasma cells as shown by immunoperoxidase electron microscopy using a polyclonal antibody prepared against the IPM vesicles. Moreover, in Toxoplasma-infected macrophages, anti-IMP antibody confirmed that the extensive IPM array contains proteins also found on the Toxoplasma cell surface. Our results indicate the IMP network represents a unique structural modification of the phagosome comprised in part of Toxoplasma surface proteins.

Segmentation of a Thematic Mapper Image Using the Fuzzy c-Means Clusterng Algorthm

Abstract: In this paper, a segmentation procedure that utilizes a clustering algorithm based upon fuzzy set theory is developed. The procedure operates in a nonparametric unsupervised mode. The feasibility of the methodology is demonstrated by segmenting a six-band Landsat-4 digital image with 324 scan lines and 392 pixels per scan line. For this image, 100-percent ground cover information is available for estimating the quality of segmentation. About 80 percent of the imaged area contains corn and soybean fields near the peak of their growing season. The remaining 20 percent of the image contains 12 different types of ground cover classes that appear in regions of diffferent sizes and shapes. The segmentation method uses the fuzzy c-means algorithm in two stages. The large number of clusters resulting from this segmentation process are then merged by use of a similarity measure on the cluster centers. Results are presented to show that this two-stage process leads to separation of corn and soybean, and of several minor classes that would otherwise be overwhelmed in any practical one-stage clustering.