Showing papers by "University of British Columbia published in 1993"

Strategic assets and organizational rent

Abstract: We build on an emerging strategy literature that views the firm as a bundle of resources and capabilities, and examine conditions that contribute to the realization of sustainable economic rents. Because of (1) resource-market imperfections and (2) discretionary managerial decisions about resource development and deployment, we expect firms to differ (in and out of equilibrium) in the resources and capabilities they control. This asymmetry in turn can be a source of sustainable economic rent. The paper focuses on the linkages between the industry analysis framework, the resource-based view of the firm, behavioral decision biases and organizational implementation issues. It connects the concept of Strategic Industry Factors at the market level with the notion of Strategic Assets at the firm level. Organizational rent is shown to stem from imperfect and discretionary decisions to develop and deploy selected resources and capabilities, made by boundedly rational managers facing high uncertainty, complexity, and intrafirm conflict.

A predictive model for aggressive non-Hodgkin's lymphoma

Abstract: BACKGROUND Although many patients with intermediate-grade or high-grade (aggressive) non-Hodgkin's lymphoma are cured by combination chemotherapy, the remainder are not cured and ultimately die of their disease. The Ann Arbor classification, used to determine the stage of this disease, does not consistently distinguish between patients with different long-term prognoses. This project was undertaken to develop a model for predicting outcome in patients with aggressive non-Hodgkin's lymphoma on the basis of the patients' clinical characteristics before treatment. METHODS Adults with aggressive non-Hodgkin's lymphoma from 16 institutions and cooperative groups in the United States, Europe, and Canada who were treated between 1982 and 1987 with combination-chemotherapy regimens containing doxorubicin were evaluated for clinical features predictive of overall survival and relapse-free survival. Features that remained independently significant in step-down regression analyses of survival were incorporated into models that identified groups of patients of all ages and groups of patients no more than 60 years old with different risks of death. RESULTS In 2031 patients of all ages, our model, based on age, tumor stage, serum lactate dehydrogenase concentration, performance status, and number of extranodal disease sites, identified four risk groups with predicted five-year survival rates of 73 percent, 51 percent, 43 percent, and 26 percent. In 1274 patients 60 or younger, an age-adjusted model based on tumor stage, lactate dehydrogenase level, and performance status identified four risk groups with predicted five-year survival rates of 83 percent, 69 percent, 46 percent, and 32 percent. In both models, the increased risk of death was due to both a lower rate of complete responses and a higher rate of relapse from complete response. These two indexes, called the international index and the age-adjusted international index, were significantly more accurate than the Ann Arbor classification in predicting long-term survival. CONCLUSIONS The international index and the age-adjusted international index should be used in the design of future therapeutic trials in patients with aggressive non-Hodgkin's lymphoma and in the selection of appropriate therapeutic approaches for individual patients.

Interferon beta-1b is effective in relapsing-remitting multiple sclerosis. II. MRI analysis results of a multicenter, randomized, double-blind, placebo-controlled trial

Abstract: We performed yearly MRI analyses on 327 of the total 372 patients in a multicenter, randomized, double-blind, placebo-controlled trial of interferon beta-1b (IFNB). Clinical results are presented in the preceding companion paper. Baseline MRI characteristics were the same in all treatment groups. Fifty-two patients at one center formed a cohort for frequent MRIs (one every 6 weeks) for analysis of disease activity. The MRI results support the clinical results in showing a significant reduction in disease activity as measured by numbers of active scans (median 80% reduction, p = 0.0082) and appearance of new lesions. In addition, there was an equally significant reduction in MRI-detected burden of disease in the treatment as compared with placebo groups (mean group difference of 23%, p = 0.001). These results demonstrate that IFNB has made a significant impact on the natural history of MS in these patients.

The Effect of Errors in Means, Variances, and Covariances on Optimal Portfolio Choice

Abstract: There is considerable literature on the strengths and limitations of mean-variance analysis. The basic theory and extensions of MV analysis are discussed in Markowitz [1987] and Ziemba & Vickson [1975]. Bawa, Brown & Klein [1979] and Michaud [1989] review some of its problems…

Testing identifiability and specification in instrumental variable models

Abstract: The paper develops and explores tests, based on standard moment specifications, for the identifiability of parameters apparently estimable by instrumental variables. An asymptotic expansion under standard restrictive assumptions on the error distribution suggests a correction to the asymptotic distribution. A small sampling experiment indicates that the tests are of use.

The relationship between trinucleotide (CAG) repeat length and clinical features of Huntington's disease

Abstract: Huntington's disease (HD) is associated with the expansion of a CAG trinucleotide repeat in a novel gene. We have assessed 360 HD individuals from 259 unrelated families and found a highly significant correlation (r = 0.70, p = 10(-7)) between the age of onset and the repeat length, which accounts for approximately 50% of the variation in the age of onset. Significant associations were also found between repeat length and age of death and onset of other clinical features. Sib pair and parent-child analysis revealed that the CAG repeat demonstrates only mild instability. Affected HD siblings had significant correlations for trinucleotide expansion (r = 0.66, p < 0.001) which was not apparent for affected parent-child pairs.

Clinical trial of indomethacin in Alzheimer's disease

Abstract: In a 6-month, double-blind, placebo-controlled study, 100 to 150 mg/d indomethacin appeared to protect mild to moderately impaired Alzheimer's disease patients from the degree of cognitive decline exhibited by a well-matched, placebo-treated group. Over a battery of cognitive tests, indomethacin patients improved 1.3% (+/- 1.8%), whereas placebo patients declined 8.4% (+/- 2.3%)--a significant difference (p < 0.003). Caveats include adverse reactions to indomethacin and the limited scale of the trial.

Analysis of 462 transplantations from unrelated donors facilitated by the national marrow donor program

Abstract: Background and Methods Allogeneic bone marrow transplantation is curative in a substantial number of patients with hematologic cancers, marrow-failure disorders, immunodeficiency syndromes, and certain metabolic diseases. Unfortunately, only 25 to 30 percent of potential recipients have HLA-identical siblings who can act as donors. In 1986 the National Marrow Donor Program was created in the United States to facilitate the finding and procurement of suitable marrow from unrelated donors for patients lacking related donors. Results During the first four years of the program, 462 patients with acquired and congenital lymphohematopoietic disorders or metabolic diseases received marrow transplants from unrelated donors. The probability of engraftment by 100 days after transplantation was 94 percent, although 8 percent of patients later had secondary graft failure. The probability of grade II, III, or IV acute graft-versus-host disease was 64 percent, and the probability of chronic graft-versus-host disease at...

Identification and differential subcellular localization of the neuronal class C and class D L-type calcium channel alpha 1 subunits.

Abstract: To identify and localize the protein products of genes encoding distinct L-type calcium channels in central neurons, anti-peptide antibodies specific for the class C and class D alpha 1 subunits were produced Anti-CNC1 directed against class C immunoprecipitated 75% of the L-type channels solubilized from rat cerebral cortex and hippocampus Anti-CND1 directed against class D immunoprecipitated only 20% of the L-type calcium channels Immunoblotting revealed two size forms of the class C L-type alpha 1 subunit, LC1 and LC2, and two size forms of the class D L-type alpha 1 subunit, LD1 and LD2 The larger isoforms had apparent molecular masses of approximately 200-210 kD while the smaller isoforms were 180-190 kD, as estimated from electrophoresis in gels polymerized from 5% acrylamide Immunocytochemical studies using CNC1 and CND1 antibodies revealed that the alpha 1 subunits of both L-type calcium channel subtypes are localized mainly in neuronal cell bodies and proximal dendrites Relatively dense labeling was observed at the base of major dendrites in many neurons Staining in more distal dendritic regions was faint or undetectable with CND1, while a more significant level of staining of distal dendrites was observed with CNC1, particularly in the dentate gyrus and the CA2 and CA3 areas of the hippocampus Class C calcium channels were concentrated in clusters, while class D calcium channels were generally distributed in the cell surface membrane of cell bodies and proximal dendrites Our results demonstrate multiple size forms and differential localization of two subtypes of L-type calcium channels in the cell bodies and proximal dendrites of central neurons The differential localization and multiple size forms may allow these two channel subtypes to participate in distinct aspects of electrical signal integration and intracellular calcium signaling in neuronal cell bodies The preferential localization of these calcium channels in cell bodies and proximal dendrites implies their involvement in regulation of calcium-dependent functions occurring in those cellular compartments such as protein phosphorylation, enzyme activity, and gene expression

On the ontological expressiveness of information systems analysis and design grammars

Abstract: . Information systems analysis and design (ISAD) methodologies provide facilities for describing existing or conceived real‐world systems. These facilities are ontologically expressive if they are capable of describing all real‐world phenomena completely and clearly. In this paper we formally examine the notion of the ontological expressiveness of a grammar and discuss some of its implications for the design and use of ISAD methodologies. We identify some generic ways in which ontological expressiveness may be undermined in a grammar and some potential consequences of these violations. We also examine ontological expressiveness within the context of some other desirable features that might be considered in the design of ISAD methodologies.

Precision measurements of the temperature dependence of lambda in YBa2Cu3O6.95: Strong evidence for nodes in the gap function.

Abstract: A miniature superconducting resonator operating at 1.3 K and 900 MHz has been used to measure the change in λ(T) from 1.3 K to T c in very high quality single crystals of YBa 2 Cu 3 O 6.95 . The data, which have a resolution of 1-2 A, show a strong linear term extending from approximately 3 to 25 K. We believe the strong linear dependence to be characteristic of the pure system and that its apparent absence in thin films and some crystals is due to the presence of defects

Importance of timing for thoracic irradiation in the combined modality treatment of limited-stage small-cell lung cancer. The National Cancer Institute of Canada Clinical Trials Group.

Abstract: PURPOSEThe importance of the timing of thoracic irradiation (TI) in the combined modality therapy of limited-stage small-cell lung cancer (SCLC) was assessed in a randomized trial.METHODSAll 308 eligible patients received cyclophosphamide, doxorubicin, and vincristine (CAV) alternating with etoposide and cisplatin (EP) every 3 weeks for three cycles of each chemotherapy regimen. Patients randomized to early TI received 40 Gy in 15 fractions over 3 weeks to the primary site concurrent with the first cycle of EP (week 3), and late TI patients received the same radiation concurrent with the last cycle of EP (week 15). After completion of all chemotherapy and TI, patients without progressive disease received prophylactic cranial irradiation (25 Gy in 10 fractions over 2 weeks).RESULTSAlthough complete remission rates were not significantly different between the two arms, progression-free survival (P = .036) and overall survival (P = .008) were superior in the early TI arm. Patients in the late TI arm had a hi...

Small airways dimensions in asthma and in chronic obstructive pulmonary disease.

Abstract: The purpose of this study was to compare the dimensions of the peripheral airways in fatal asthma with those from patients with nonfatal asthma, mild COPD, and normal lung function. Lung specimens from eight individuals who had fatal asthmatic attacks were obtained at postmortem and compared with similar specimens from three asthmatic patients who died of an unrelated cause and four specimens obtained from known asthmatic patients who required lung resection for tumor. These 15 asthmatic lungs were also compared with lungs resected for peripheral neoplasms from 15 patients with normal airway function (FEV1, % of predicted > 85) and 15 patients with mild chronic airflow obstruction (FEV1, % of predicted < 85). All membranous airways with a long-short diameter ratio of 3:1 or less were examined. The smooth muscle and the tissue areas external and internal to the muscle layer were traced using a Bioquant BQ System 4. The same system was used to evaluate the fraction of the submucosa and adventitia taken up by blood vessels. The adventitial, submucosal, and muscle area of the asthmatic airways were greater than those of COPD and control (p < 0.01), and the muscle area was greater in COPD than in control lungs (p < 0.05). These parameters were also greater in the 8 patients with fatal asthma compared with the 7 patients with nonfatal asthma (p < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Microglia in degenerative neurological disease

Abstract: Microglia express many leukocyte surface antigens which are upregulated in such chronic degenerative neurological diseases as Alzheimer's disease (AD) and amyotrophic lateral sclerosis (ALS). These surface antigens include leukocyte common antigen, immunoglobulin Fc receptors, MHC class I and class II glycoproteins, β2-integrins, and the vitronectin receptor. Ligands for these receptors are also found. They include immunoglobulins, complement proteins of the classical pathway, T lymphocytes of the cytotoxic/suppressor and helper/inducer classes, and vitronectin. T lymphocytes marginate along capillary venules, with some penetrating into the tissue matrix. Immunoglobulins and complement proteins are synthesized locally in brain, although they may also come from the bloodstream if the blood-brain barrier is compromised. The membrane attack complex, which is formed from C5b-9, the terminal components of complement, has been identified in AD and multiple sclerosis brain tissue. In addition, proteins designed to defend against bystander lysis caused by the membrane attack complex, including protectin, C8 binding protein, clusterin, and vitronectin, are associated with damaged neuronal processes in AD. Autodestruction may play a prominent part in these 2 diseases.

Here's the Beef: Factors, Determinants, and Segments in Consumer Criticism of Advertising:

Abstract: A comprehensive model of attitudes toward advertising includes three personal utility factors (product information, social image information, and hedonic amusement) and four socioeconomic factors (...

The Effect of Corticosteroids for Acute Optic Neuritis on the Subsequent Development of Multiple Sclerosis

Abstract: Background Optic neuritis is often the first clinical manifestation of multiple sclerosis, but little is known about the effect of corticosteroid treatment for optic neuritis on the subsequent risk of multiple sclerosis. Methods We conducted a multicenter study in which 389 patients with acute optic neuritis (and without known multiple sclerosis) were randomly assigned to receive intravenous methylprednisolone (250 mg every six hours) for 3 days followed by oral prednisone (1 mg per kilogram of body weight) for 11 days, oral prednisone (1 mg per kilogram) alone for 14 days, or placebo for 14 days. Neurologic status was assessed over a period of two to four years. The patients in the first group were hospitalized for three days; the others were treated as outpatients. Results Definite multiple sclerosis developed within the first two years in 7.5 percent of the intravenous-methylprednisolone group (134 patients), 14.7 percent of the oral-prednisone group (129 patients), and 16.7 percent of the placebo grou...

Structure and functional expression of a member of the low voltage-activated calcium channel family.

Abstract: Oscillatory firing patterns are an intrinsic property of some neurons and have an important function in information processing. In some cells, low voltage-activated calcium channels have been proposed to underlie a depolarizing potential that regulates bursting. The sequence of a rat brain calcium channel alpha 1 subunit (rbE-II) was deduced. Although it is structurally related to high voltage-activated calcium channels, the rbE-II channel transiently activated at negative membrane potentials, required a strong hyperpolarization to deinactivate, and was highly sensitive to block by nickel. In situ hybridization showed that rbE-II messenger RNA is expressed in regions throughout the central nervous system. The electrophysiological properties of the rbE-II current are consistent with a type of low voltage-activated calcium channel that requires membrane hyperpolarization for maximal activity, which suggests that rbE-II may be involved in the modulation of firing patterns.

Expression of Thy-1 on human hematopoietic progenitor cells.

Abstract: Expression of Thy-1 on hematopoietic cells from human fetal liver (FL), cord blood (CB), and bone marrow (BM) was studied with a novel anti-Thy-1 antibody, 5E10. Specificity of 5E10 for human Thy-1 was demonstrated by immunoprecipitation of a 25-35-kD molecule, and the sequence of a cDNA that was cloned by immunoselection of COS cells transfected with a cDNA library derived from a 5E10+ cell line. Two- and three-color immunofluorescence staining experiments revealed that the Thy-1 expression is restricted to, an average, 1-4% of FL, CB, and BM cells, and binding to these cell types is essentially restricted to a very small subset of lymphoid cells and approximately 25% of CD34+ cells. Thy-1+ CD34+ cells were further characterized as CD38lo/CD45RO+/CD45RA-/CD71lo/c-kit(lo) and rhodamine 123dull. When CD34+ cells were sorted on the basis of Thy-1 expression, the majority of clonogenic cells were recovered in the CD34+Thy-1- fraction, whereas the majority of cells capable of producing myeloid colonies after 5-8 wk of long-term culture (long-term culture initiating cells) were recovered in the Thy-1+CD34+ fraction. In addition to CD34+ cells, Thy-1 was found to be expressed on a variable, very small number (< 1%) of CD34- mononuclear cells in BM, CB, and peripheral blood that were further characterized as CD3+ CD4+ lymphocytes. The restricted expression of Thy-1 on primitive hematopoietic cells is in agreement with a previous report (Baum et al., 1992. Proc. Natl. Acad. Sci. USA. 89:2804) in which Thy-1 expression was used to enrich for primitive hematopoietic cells from fetal tissue. Compared with those previous studies, we found Thy-1 expression on a larger proportion of CD34+ cells (25% in our study vs. 5% in Baum et al.) and furthermore performed studies on Thy-1 expression on CD34+ cells from CB, FL, and BM in relation to markers that are known to be differentially expressed on hematopoietic cells. Taken together our results indicate that Thy-1-specific antibody 5E10 is an attractive tool for further studies on the biology and purification of human stem cells.

Infants' ability to consult the speaker for clues to word reference.

Abstract: This research examines whether infants actively seek information from a speaker regarding the referent of the speaker's utterance. Forty-eight infants (in three age groups: 1;2–1;3, 1;4–1;5, and 1;6–1;7) heard novel labels for novel objects in two situations: follow-in labelling (the experimenter looked at and labelled the toy of the infant's focus) vs. discrepant labelling (the experimenter looked at and labelled a different toy than that of the infant's focus). Subsequently, half of the infants were asked comprehension questions (e.g. ‘Where's the peri?’). The other half were asked preference questions (e.g. ‘Where's the one you like?’), to ensure that their comprehension performance was not merely the result of preferential responding. The comprehension results revealed developmental change in both (a) infants' ability to establish new word-object mappings (infants aged 1;2–1;3 failed to establish stable word-object links even in follow-in labelling), and (b) infants' ability to pinpoint the correct referent during discrepant labelling (only infants aged 1;6–1;7 succeeded). Thus the period between 1;2 and 1;7 represents a time of change in infants' ability to establish new word-object mappings: infants are becoming increasingly adept at acquiring new labels under minimal learning conditions.

Challenges to theory development in entrepreneurship research

Abstract: Why do some new ventures succeed while others fail? What is the essence of entrepreneurship? Who is most likely to become a successful entrepreneur and why? How do entrepreneurs make decisions? What market, regulatory, and organizational environments foster the most successful entrepreneurial activities? Entrepreneurship research is plagued by these and other fundamental unanswered questions, for which there does not exist a cohesive explanatory, predictive, or normative theory. In this article we identify major challenges for entrepreneurship theory development, and offer insights into promising directions for future research. Our conclusion suggests that it may be too ambitious to expect a complete and robust theory due to the interdisciplinary nature of entrepreneurship. However, we show that by integrating perspectives and by applying analytic, empirical and experimental tools from a range of fields, some of the fundamental questions can be answered.

Pain in the preterm neonate: behavioural and physiological indices.

Abstract: The impact of invasive procedures on preterm neonates has received little systematic attention. We examined facial activity, body movements, and physiological measures in 56 preterm and full-term newborns in response to heel lancing, along with comparison preparatory and recovery intervals. The measures were recorded in special care and full-term nurseries during routine blood sampling. Data analyses indicated that in all measurement categories reactions of greatest magnitude were to the lancing procedure. Neonates with gestational ages as short as 25–27 weeks displayed physiological responsivity to the heel lance, but only in the heart rate measure did this vary with gestational age. Bodily activity was diminished in preterm neonates in general, relative to full-term newborns. Facial activity increased with the gestational age of the infant. Specificity of the response to the heel lance was greatest on the facial activity measure. Identification of pain requires attention to gestational age in the preterm neonate.

The lateral preference inventory for measurement of handedness, footedness, eyedness, and earedness: Norms for young adults

Abstract: The Lateral Preference Inventory is a brief, 16-item questionnaire, which validly measures hand, foot, eye, and ear preference. Normative data is presented for 3,307 subjects, ranging in age from 17 to 35 years. Data is separated by sex, since females are found to be more right-sided than are males for hand, foot, and ear. Data are presented in a format that should allow various scoring and coding criteria to be applied. These norms could serve as a reference or control comparison for measures of laterality taken on clinical or other targeted groups. A copy of the inventory appears in the Appendix.