Showing papers by "University of Calgary published in 1997"

Retaliation in the workplace: the roles of distributive, procedural, and interactional justice

Abstract: The authors investigated the relationship between organizational justice and organizational retaliation behavior—adverse reactions to perceived unfairness by disgruntled employees toward their employer—in a sample of 240 manufacturing employees. Distributive, procedural, and interactional justice interacted to predict organizational retaliation behavior. A relation between distributive justice and retaliation was found only when there was low interactional and procedural justice. The 2-way interaction of distributive and procedural justice was observed only at a low level of interactional justice, and the 2-way interaction of distributive and interactional justice was observed only at a low level of procedural justice.

Mitosis-specific phosphorylation of histone H3 initiates primarily within pericentromeric heterochromatin during G2 and spreads in an ordered fashion coincident with mitotic chromosome condensation.

Abstract: We have generated and characterized a novel site-specific antibody highly specific for the phosphorylated form of the amino-terminus of histone H3 (Ser10). In this study, we used this antibody to examine in detail the relationship between H3 phosphorylation and mitotic chromosome condensation in mammalian cells. Our results extend previous biochemical studies by demonstrating that mitotic phosphorylation of H3 initiates nonrandomly in pericentromeric heterochromatin in late G2 interphase cells. Following initiation, H3 phosphorylation appears to spread throughout the condensing chromatin and is complete in most cell lines just prior to the formation of prophase chromosomes, in which a phosphorylated, but nonmitotic, chromosomal organization is observed. In general, there is a precise spatial and temporal correlation between H3 phosphorylation and initial stages of chromatin condensation. Dephosphorylation of H3 begins in anaphase and is complete immediately prior to detectable chromosome decondensation in telophase cells. We propose that the singular phosphorylation of the amino-terminus of histone H3 may be involved in facilitating two key functions during mitosis: (1) regulate protein-protein interactions to promote binding of trans-acting factors that "drive" chromatin condensation as cells enter M-phase and (2) coordinate chromatin decondensation associated with M-phase.

Strategic Management of the Family Business: Past Research and Future Challenges

Abstract: This article reviews the literature on family business from a strategic management perspective. In general, this literature is dominated by descriptive articles that typically focus on family relationships. However, the literature does not usually address how these relationships affect the performance of a family business. Taking a strategic management perspective, we outline a new set of objectives for family-business research. We also identify some of the key issues and gaps that should be explored in future studies if research is to contribute to improving the management practices and performance of family firms.

Advancing the Theory of Adaptive Structuration: The Development of a Scale to Measure Faithfulness of Appropriation

Abstract: Adaptive Structuration Theory AST is rapidly becoming an influential theoretical perspective in research on advanced information technologies. However, there still exists a paucity of methods to capture critical AST constructs. This paper describes the development of an instrument to capture the extent to which users of an advanced information technology believe they have appropriated its structures faithfully. The development of such instruments is considered critical if the theoretical base provided by AST is to be fully exploited in understanding the use of advanced information technologies. The development procedure, which occurred in the context of the use of an electronic meeting system, was carried out in three phases that began with initial item development and proceeded through an exploratory to a confirmatory phase. Three experiments, two in the exploratory phase and one in the confirmatory phase, were performed. In the final phase, structural equation modeling techniques were used to confirm the convergent, discriminant, and nomological validity of the resulting five-item scale.

Range of antinuclear antibodies in "healthy" individuals

Abstract: Objective. To determine the range of antinuclear antibodies (ANA) in “healthy” individuals compared with that in patients with systemic lupus erythematosus (SLE), systemic sclerosis (SSc; scleroderma), Sjogren's syndrome (SS), rheumatoid arthritis (RA), or soft tissue rheumatism (STR). Methods. Fifteen international laboratories experienced in performing tests for ANA by indirect immunofluorescence participated in analyzing coded sera from healthy individuals and from patients in the 5 different disease groups described above. Except for the stipulation that HEp-2 cells should be used as substrate, each laboratory used its own in-house methodology so that the data might be expected to reflect the output of a cross-section of worldwide ANA reference laboratories. The sera were analyzed at 4 dilutions: 1:40, 1:80, 1:160, and 1:320. Results. In healthy individuals, the frequency of ANA did not differ significantly across the 4 age subgroups spanning 20–60 years of age. This putatively normal population was ANA positive in 31.7% of individuals at 1:40 serum dilution, 13.3% at 1:80, 5.0% at 1:160, and 3.3% at 1:320. In comparison with the findings among the disease groups, a low cutoff point at 1:40 serum dilution (high sensitivity, low specificity) could have diagnostic value, since it would classify virtually all patients with SLE, SSc, or SS as ANA positive. Conversely, a high positive cutoff at 1:160 serum dilution (high specificity, low sensitivity) would be useful to confirm the presence of disease in only a portion of cases, but would be likely to exclude 95% of normal individuals. Conclusion. It is recommended that laboratories performing immunofluorescent ANA tests should report results at both the 1:40 and 1:160 dilutions, and should supply information on the percentage of normal individuals who are positive at these dilutions. A low-titer ANA is not necessarily insignificant and might depend on at least 4 specific factors. ANA assays can be a useful discriminant in recognizing certain disease conditions, but can create misunderstanding when the limitations are not fully appreciated.

Neuronal position in the developing brain is regulated by mouse disabled-1

Abstract: During mammalian brain development, immature neurons migrate radially from the neuroectoderm to defined locations, giving rise to characteristic cell layers. Here we show that targeted disruption of the mouse disabled1 (mdab1) gene disturbs neuronal layering in the cerebral cortex, hippocampus and cerebellum. The gene encodes a cytoplasmic protein, mDab1 p80, which is expressed and tyrosine-phosphorylated in the developing nervous system. It is likely to be an adaptor protein, docking to others through its phosphotyrosine residues and protein-interacting domain. The mdab1 mutant phenotype is very similar to that of the reeler mouse. The product of the reeler gene, Reelin, is a secreted protein that has been proposed to act as an extracellular signpost for migrating neurons. Because mDab1 is expressed in wild-type cortical neurons, and Reelin expression is normal in mdab1 mutants, mDab1 may be part of a Reelin-regulated or parallel pathway that controls the final positioning of neurons.

How people revisit web pages

Abstract: We report on users' revisitation patterns to World Wide Web (web) pages, and use the results to lay an empirical foundation for the design of history mechanisms in web browsers. Through history, a user can return quickly to a previously visited page, possibly reducing the cognitive and physical overhead required to navigate to it from scratch. We analysed 6 weeks of detailed usage data collected from 23 users of a well-known web browser. We found that 58% of an individual's pages are revisits, and that users continually add new web pages into their repertoire of visited pages. People tend to revisit pages just visited, access only a few pages frequently, browse in very small clusters of related pages and generate only short sequences of repeated URL paths. We compared different history mechanisms, and found that the stack-based prediction method prevalent in commercial browsers is inferior to the simpler approach of showing the last few recently visited URLs with duplicates removed. Other predictive approaches fare even better. Based on empirical evidence, eight design guidelines for web browser history mechanisms were then formulated. When used to evaluate the existing hypertext-based history mechanisms, they explain why some aspects of today's browsers seem to work well, and other's poorly. The guidelines also indicate how history mechanisms in the web can be made even more effective.f1f1This article is a major expansion of a conference paper (Tauscher & Greenberg, 1997). This research reported in this article was performed as part of an M.Sc. project (Tauscher, 1996).

The science of reconstruction of the anterior cruciate ligament.

Abstract: Very few subjects in contemporary orthopaedic surgery have evoked as much controversy, thought, and opinion as that of when and how to optimally reconstruct the anterior cruciate ligament of the knee. Fueled by an annual incidence of acute rupture of the anterior cruciate ligament that has been estimated to be one in 3000 in the American population—approximately 95,000 new injuries each year196—and combined with the fact that more than 50,000 knees that have such an injury are reconstructed annually in the United States alone149, it is not surprising that there has been a virtual explosion of literature on this topic. During the last twenty years, more than 2000 scientific articles on the anterior cruciate ligament have been published, including numerous excellent reviews47,149,151,255,282,294 and textbooks72,89,145. It is a challenging task to attempt to synthesize these sources and to try to resolve the conflicts that are inherent in such a massive body of information. Although many relevant issues will continue to be debated until better basic-science and clinical information becomes available, a number of scientifically supported concepts can be identified within the existing knowledge base. This knowledge can help orthopaedic surgeons to understand the reasons for previous and current successes and failures of reconstruction of the anterior cruciate ligament, and it can help them to plan the care of patients who have an injury of the ligament. In the present review, the current scientific understanding of reconstruction of the anterior cruciate ligament is discussed in a sequence based on the order in which clinical decisions are made. An overview of the normal function of the knee joint and the anterior cruciate ligament is followed by a discussion of decisions that must …

Anatomy of pharynx in patients with obstructive sleep apnea and in normal subjects

Abstract: Isono, Shiroh, John E Remmers, Atsuko Tanaka, Yasuhide Sho, Jiro Sato, and Takashi Nishino. Anatomy of pharynx in patients with obstructive sleep apnea and in normal subjects.J. Appl. Physiol. 82(4...

Characterizing quality of life among patients with chronic mental illness: a critical examination of the self-report methodology.

Abstract: Objective: The purposes of the study were 1) to characterize the quality of life of three patient groups with chronic mental illness, 2) to evaluate differences in reported life quality among the three groups, and 3) to evaluate the validity of a self-report methodology by comparing these results with several objective indicators of life quality. Method: The study group consisted of chronically mentally ill patients with schizophrenia (N=69), bipolar disorder (N=37), or major depression (N=35). Subjects were administered the Quality of Life Index, and comparisons of both objective and self-report life quality indices were made among the three groups. Quality of life ratings of these subjects were also compared with those of patients with a chronic physical illness. Results: The two groups with mood disorders reported significantly lower scores on the Quality of Life Index than the patients with schizophrenia. Moreover, the scores on the Quality of Life Index for patients with schizophrenia were very similar to those of the comparison group of physically ill patients. The opposite trend emerged when groups were compared with respect to objective indicators of life quality. Schizophrenic patients experienced more objectively aversive life circumstances than either of the affectively disturbed groups. Conclusions: The validity of self-report measures of life satisfaction is questioned, particularly for use with affectively disturbed populations, since scores may be influenced by affective bias, poor insight, and recent life events. (Am J Psychiatry 1997; 154:99‐105)

Patterns in phytoplankton taxonomic composition across temperate lakes of differing nutrient status

Abstract: We describe the relationships between summer average total phosphorus (TP) and the biomass of six major phytoplankton taxonomic groups from 91 north temperate lakes. Both regression and a locally weighted smoothing (LOWESS) analyses show that all groups increase with TP but over different nutrient ranges. At nutrient extremes, i.e. very low and high levels of TP, the few taxonomic groups that dominate total biomass are generally dissimilar. In oligotrophic and eutrophic lakes, most group biomass curves show corresponding increases or decreases, but different rates of change. The curves converge at intermediate TP levels (-10-30 p,g liter-l) where there is increased equitability among algal groups. In highly eutrophic lakes, the slope of the total biomass curve decreases, as do all the relative abundances of all groups except blue-greens and diatoms. We conclude that the curvilinearity of the TP-total biomass curve is not attributable to a single taxonomic group, because all groups show some nonlinearity in relation to TP We suggest that morphological diversity, differential herbivory, and, in particular, mixing regime may explain some of the-observed patterns.

Towards a paradigm shift in marketing? An examination of current marketing practices

Abstract: In recent years, the traditional Transaction approach to marketing has been challenged to the point where a number of authors have suggested that a “paradigm shift” is occurring. The “newparadigm” is commonly referred to as Relationship Marketing, and has been used to reflect a number of different types of relational marketing activity, including Database, Interaction and Network marketing. This paper investigates current marketing practice to clarify the relevance of these alternative approaches using four case studies and a survey of 134 firms. The results do not support the notion of a complete “paradigm shift”. Rather, the findings show that for many firms, transactional marketing is relevant and practised concurrently with various types of relational marketing. It is concluded that while relational marketing issues are currently receiving attention from academics and practitioners alike, the role of transactional marketing should not be ignored or underestimated.

Substituting quantum entanglement for communication

Abstract: We show that quantum entanglement can be used as a substitute for communication when the goal is to compute a function whose input data are distributed among remote parties. Specifically, we show that, for a particular function among three parties (each of which possesses part of the function's input), a prior quantum entanglement enables one of them to learn the value of the function with only two bits of communication occurring among the parties, whereas, without quantum entanglement, three bits of communication are necessary. This result contrasts the well-known fact that quantum entanglement cannot be used to simulate communication among remote parties.

A minimal role for selectins in the recruitment of leukocytes into the inflamed liver microvasculature.

Abstract: A two-step paradigm for leukocyte recruitment has been established in a number of tissues including the mesentery, skin, and muscle, and necessitates an initial rolling step via the selectins before firm leukocyte adhesion via the integrins. In view of the many inflammatory diseases that involve the liver, we investigated the importance of rolling and the selectins in the hepatic microvasculature and compared the responses to that of the commonly used mesentery or cremaster microvasculature. We visualized the liver microvasculature using intravital microscopy and we determined that within the liver the majority of leukocytes adhere within the sinusoids (80%) in response to a chemotactic stimulus such as FMLP (20% in postsinusoidal venules) whereas leukocytes adhere exclusively within postcapillary venules in tissue like the mouse cremaster. In the sinusoids, the adhesive response to FMLP is not dependent upon selectins inasmuch as adhesion was not reduced in the sinusoidal vessels of P-selectin-deficient mice or E-selectin/P-selectin- deficient animals in the presence or absence of L-selectin antibody. No rolling or adhesion was detected in response to FMLP in the selectin-deficient cremaster microvasculature. Immunoneutralization of selectins with fucoidan in wildtype mice eliminated rolling and adhesion in the cremaster but failed to affect adhesion in the liver sinusoids in response to FMLP. More long-term leukocyte recruitment with lipopolysaccharide (4 h) was also impaired in the cremaster but not the liver microvasculature in selectin-deficient animals. Leukocyte adhesion in the sinusoids was reduced in P-selectin-deficient mice also lacking intercellular adhesion molecule-1 (ICAM-1). This study for the first time demonstrates that selectins are not an essential step for leukocyte recruitment into the inflamed liver microvasculature.

Clinical pharmacokinetics of diclofenac : Therapeutic insights and pitfalls

Abstract: Diclofenac is a nonsteroidal anti-inflammatory drug (NSAID) of the phenylacetic acid class. When given orally the absorption of diclofenac is rapid and complete. Diclofenac binds extensively to plasma albumin. The area under the plasma concentration-time curve (AUC) of diclofenac is proportional to the dose for oral doses between 25 to 150mg. Substantial concentrations of drug are attained in synovial fluid, which is the proposed site of action for NSAIDs. Concentration-effect relationships have been established for total bound, unbound and synovial fluid diclofenac concentrations. Diclofenac is eliminated following biotransformation to glucoroconjugated and sulphate metabolites which are excreted in urine, very little drug is eliminated unchanged. The excretion of conjugates may be related to renal function. Conjugate accumulation occurs in end-stage renal disease; however, no accumulation is apparent upon comparison of young and elderly individuals. Dosage adjustments for the elderly, children or for patients with various disease states (such as hepatic disease or rheumatoid arthritis) may not be required. Significant drug interactions have been demonstrated for aspirin (acetylsalicylic acid), lithium, digoxin, methotrexate, cyclosporin, cholestyramine and colestipol.

Spontaneous Autoimmune Diabetes in Monoclonal T Cell Nonobese Diabetic Mice

Abstract: It has been established that insulin-dependent diabetes mellitus (IDDM) in nonobese diabetic (NOD) mice results from a CD4+ and CD8+ T cell–dependent autoimmune process directed against the pancreatic beta cells. The precise roles that beta cell–reactive CD8+ and CD4+ T cells play in the disease process, however, remain ill defined. Here we have investigated whether naive beta cell–specific CD8+ and CD4+ T cells can spontaneously accumulate in pancreatic islets, differentiate into effector cells, and destroy beta cells in the absence of other T cell specificities. This was done by introducing Kd– or I-Ag7–restricted beta cell–specific T cell receptor (TCR) transgenes that are highly diabetogenic in NOD mice (8.3- and 4.1-TCR, respectively), into recombination-activating gene (RAG)-2–deficient NOD mice, which cannot rearrange endogenous TCR genes and thus bear monoclonal TCR repertoires. We show that while RAG-2−/− 4.1-NOD mice, which only bear beta cell–specific CD4+ T cells, develop diabetes as early and as frequently as RAG-2+ 4.1-NOD mice, RAG-2−/− 8.3-NOD mice, which only bear beta cell–specific CD8+ T cells, develop diabetes less frequently and significantly later than RAG-2+ 8.3-NOD mice. The monoclonal CD8+ T cells of RAG-2−/− 8.3-NOD mice mature properly, proliferate vigorously in response to antigenic stimulation in vitro, and can differentiate into beta cell–cytotoxic T cells in vivo, but do not efficiently accumulate in islets in the absence of a CD4+ T cell–derived signal, which can be provided by splenic CD4+ T cells from nontransgenic NOD mice. These results demonstrate that naive beta cell– specific CD8+ and CD4+ T cells can trigger diabetes in the absence of other T or B cell specificities, but suggest that efficient recruitment of naive diabetogenic beta cell–reactive CD8+ T cells to islets requires the assistance of beta cell–reactive CD4+ T cells.

Measures of acutance and shape for classification of breast tumors

Abstract: Most benign breast tumors possess well-defined, sharp boundaries that delineate them from surrounding tissues, as opposed to malignant tumors. Computer techniques proposed to date for tumor analysis have concentrated on shape factors of tumor regions and texture measures. While shape measures based on contours of tumor regions can indicate differences in shape complexities between circumscribed and spiculated tumors, they are not designed to characterize the density variations across the boundary of a tumor. Here, the authors propose a region-based measure of image edge profile acutance which characterizes the transition in density of a region of interest (ROI) along normals to the ROI at every boundary pixel. The authors investigate the potential of acutance in quantifying the sharpness of the boundaries of tumors, and propose its application to discriminate between benign and malignant mammographic tumors. In addition, they study the complementary use of various shape factors based upon the shape of the ROI, such as compactness. Fourier descriptors, moments, and chord-length statistics to distinguish between circumscribed and spiculated tumors. Thirty-nine images from the Mammographic Image Analysis Society (MIAS) database and an additional set of 15 local cases were selected for this study. The cases included 16 circumscribed benign, 7 circumscribed malignant, 12 spiculated benign, and 19 spiculated malignant lesions. All diagnoses were proven by pathologic examinations of resected tissue. The contours of the lesions were first marked by an expert radiologist using X-Paint and X-Windows on a SUN-SPARCstation 2 Workstation. For computation of acutance, the ROI boundaries were iteratively approximated using a split/merge and end-point adjustment technique to obtain the best-fitting polygonal approximation. The jackknife method using the Mahalanobis distance measure in the BMDP (Biomedical Programs) package was used for classification of the lesions using acutance and the shape factors as features in various combinations. Acutance alone resulted in a benign/malignant classification accuracy of 95% the MIAS cases. Compactness alone gave a circumscribed/spiculated classification rate of 92.3% with the MIAS cases. Acutance in combination with a moment-based shape measure and a Fourier descriptor-based measure gave four-group classification rate of 95% with the MIAS cases. The results indicate the importance of including lesion edge definition with shape information for classification of tumors, and that the proposed measure of acutance fills this need.

Measuring the Importance of Transaction Costs in Cattle Marketing

Abstract: Transaction cost economics recognizes that transactions do not occur in a frictionless economic environment. Information, negotiation, and monitoring costs arise in any transaction and can influence the vertical coordination outcome. This paper demonstrates a method for measuring the influence of transaction costs on slaughter cattle marketing. The paper focuses on the factors affecting the choice between liveweight (live-ring auction) and deadweight (direct-to-packer) sales. Using Tobit limited dependent variable analysis, data from a survey of UK farmers are used to estimate the relative importance of various transaction costs and farm characteristic variables for the choice of marketing channel.

Personal names and the attentional blink: a visual "cocktail party" effect.

Abstract: Four experiments were carried out to investigate an early- versus late-selection explanation for the attentional blink (AB). In both Experiments 1 and 2, 3 groups of participants were required to identify a noun (Experiment 1) or a name (Experiment 2) target (experimental conditions) and then to identify the presence or absence of a 2nd target (probe), which was their own name, another name, or a specified noun from among a noun distractor stream (Experiment 1) or a name distractor stream (Experiment 2). The conclusions drawn are that individuals do not experience an AB for their own names but do for either other names or nouns. In Experiments 3 and 4, either the participant's own name or another name was presented, as the target and as the item that immediately followed the target, respectively. An AB effect was revealed in both experimental conditions. The results of these experiments are interpreted as support for a late-selection interference account of the AB.

Luminal trypsin may regulate enterocytes through proteinase-activated receptor 2

Abstract: Proteinase-activated receptor 2 (PAR-2) is a recently characterized G-protein coupled receptor that is cleaved and activated by pancreatic trypsin. Trypsin is usually considered a digestive enzyme in the intestinal lumen. We examined the hypothesis that trypsin, at concentrations normally present in the lumen of the small intestine, is also a signaling molecule that specifically regulates enterocytes by activating PAR-2. PAR-2 mRNA was highly expressed in the mucosa of the small intestine and in an enterocyte cell line. Immunoreactive PAR-2 was detected at the apical membrane of enterocytes, where it could be cleaved by luminal trypsin. Physiological concentrations of pancreatic trypsin and a peptide corresponding to the tethered ligand of PAR-2, which is exposed by trypsin cleavage, stimulated generation of inositol 1,4,5-trisphosphate, arachidonic acid release, and secretion of prostaglandin E2 and F1α from enterocytes and a transfected cell line. Application of trypsin to the apical membrane of enterocytes and to the mucosal surface of everted sacs of jejunum also stimulated prostaglandin E2 secretion. Thus, luminal trypsin activates PAR-2 at the apical membrane of enterocytes to stimulate secretion of eicosanoids, which regulate multiple cell types in a paracrine and autocrine manner. We conclude that trypsin is a signaling molecule that specifically regulates enterocytes by triggering PAR-2.

Understanding contemporary marketing: Development of a classification scheme

Abstract: The term Relationship Marketing has been used in a multitude of ways to describe and define marketing in the contemporary environment. This has led to the term being loosely defined and applied in the literature, resulting in frustration for both researchers and practitioners. Therefore, a classification scheme is developed from analysis of the extant literature, and used to systematically examine the meaning of marketing across twelve dimensions which reflect issues related to marketing practice. From this scheme, the authors identify two ‘perspectives’ of marketing, which encompass four distinguishable ‘types’ of marketing. Implications for future research in the area are discussed.

The Role of Bulky Substituents in Brookhart-Type Ni(II) Diimine Catalyzed Olefin Polymerization: A Combined Density Functional Theory and Molecular Mechanics Study

Abstract: The role of the bulky ligands in Ni(II) diimine catalyzed ethylene polymerization has been examined with a combined density functional theory quantum mechanics and molecular mechanics (QM/MM) model. Specifically, we have examined the catalytic center of the type (ArNC(R)−C(R)NAr)NiII-R‘+, where R = Me and Ar = 2,6-C6H3(i-Pr)2. The Ar and R groups were treated by a molecular mechanics force field while density functional theory was applied to the remainder of the system. The chain propagation, chain branching, and chain termination processes have been investigated with the hybrid method and found to have barriers of ΔH⧧ = 11.8, 15.3, and 18.4 kcal/mol, respectively, which is in excellent agreement with experiment in both absolute and relative terms. This is in stark contrast to the pure QM model in which the influence of the bulky Ar and R groups was neglected and the established order of the barriers is not even reproduced. The role played by the bulky substituents is dual in nature. First, the Ar and R g...