Showing papers by "University of Alberta published in 1993"

The Age of Migration: International Population Movements in the Modern World

Abstract: International migration is a central feature of the contemporary world. The fifth edition of this leading text has been substantially revised to provide an up-to-date and comprehensive assessment of the nature, extent and dimensions of international population movements, as well as of their consequences. Taking full account of the latest developments, including the impact of the global economic crisis and the relationship of globalization to migration, this text firmly contextualizes the main issues, theories and history that contribute to the field. This latest edition has extensive coverage of regional case studies, as well as additional material that examines the effect of climate change on migration. The book's companion website helps to consolidate learning by providing additional resources, including further case studies, links to external web-pages and a web-only chapter.

Micromachining a Miniaturized Capillary Electrophoresis-Based Chemical Analysis System on a Chip

Abstract: Micromachining technology was used to prepare chemical analysis systems on glass chips (1 centimeter by 2 centimeters or larger) that utilize electroosmotic pumping to drive fluid flow and electrophoretic separation to distinguish sample components. Capillaries 1 to 10 centimeters long etched in the glass (cross section, 10 micrometers by 30 micrometers) allow for capillary electrophoresis-based separations of amino acids with up to 75,000 theoretical plates in about 15 seconds, and separations of about 600 plates can be effected within 4 seconds. Sample treatment steps within a manifold of intersecting capillaries were demonstrated for a simple sample dilution process. Manipulation of the applied voltages controlled the directions of fluid flow within the manifold. The principles demonstrated in this study can be used to develop a miniaturized system for sample handling and separation with no moving parts.

Configurational approaches to organizational analysis

Abstract: The 1993 Special Research Forum on Configurations is dedicated to the proposition that configurational theory and research can significantly advance understanding of people, groups, and organizations. In this introductory essay, we define configurational approaches to organizational analysis, trace the history of configurational thinking, distinguish the contingency approach from the configurational approach, and highlight key contributions of the five empirical articles that make up the special research forum. Most of these articles report research conducted at the organizational level of analysis, but we argue that the configurational perspective has unrealized potential at other levels as well and suggest some configurational approaches to revitalizing theory and research at the individual and group levels.

Average entropy of a subsystem

Abstract: If a quantum system of Hilbert space dimension mn is in a random pure state, the average entropy of a subsystem of dimension m\ensuremath{\le}n is conjectured to be ${\mathit{S}}_{\mathit{m},\mathit{n}}$= ${\mathit{S}}_{\mathit{k}=\mathit{n}+1}^{\mathit{mn}}$ 1/k-m-1/2n and is shown to be \ensuremath{\simeq}lnm-m/2n for 1\ensuremath{\ll}m\ensuremath{\le}n. Thus there is less than one-half unit of information, on average, in the smaller subsystem of a total system in a random pure state.

Information in black hole radiation.

Abstract: If black hole formation evaporation can be described by an S matrix, information would be expected to come out in black hole radiation. An estimate shows that it may come out initially so slowly, or else be so spread out, that it would never show up in an analysis perturbative in ${\mathit{M}}_{\mathrm{Planck}}$/M, or in 1/N for two-dimensional dilatonic black holes with a large number N of minimally coupled scalar fields.

Synthesis of T helper 2-type cytokines at the maternal-fetal interface.

Abstract: Clinical and experimental evidence has indicated that the maternal immune response is biased toward antibody production and away from cell-mediated immunity during pregnancy, especially in the vicinity of the fetoplacental unit. Because antibody responses are often associated with the Th2 cytokine pattern, this suggests that Th2-type cytokines might predominate locally in the regulation of the maternal immune response. In order to test this hypothesis, we examined the local and distal release of cytokines during murine pregnancy using ELISA assays. We report here that the Th2-specific cytokines IL-4, IL-5, and IL-10 were readily detectable in cell supernatants derived from fetal-placental units in all three trimesters of gestation. IL-3 was also present. These cytokines were detected in lysates of freshly isolated, day 12 decidual and placental cells, and in supernatants as early as 15 min after the beginning of culture. The presence of functional IL-10 was confirmed by specific bioassay. IL-10 mRNA was localized to the decidua at day 6 of gestation by in situ hybridization. IFN-gamma was also found in the supernatants from the first trimester of pregnancy, but was barely detectable in the second, and undetectable in the third trimester. Cytokine expression was consistently detected in samples from individual mice. None of these cytokines was produced by unstimulated spleen or mesenteric lymph nodes from pregnant mice. IL-4, IL-10, and IFN-gamma were produced by Con A-stimulated spleen cells from virgin mice, but in ratios opposite to those found in the placenta. These observations indicate that Th2-specific cytokines are normally produced at the maternal-fetal interface. The continuous presence of IL-4, IL-5, and IL-10, with early and transient expression of IFN-gamma, can provide a molecular basis for the antibody/Th2-like bias of the maternal immune response during pregnancy.

Understanding strategic change: The contribution of archetypes

Abstract: We examined the concept of archetype, implicit in a number of contemporary approaches to the study of organizational design and change. Despite an emerging interest in archetypes, the concept has r...

Relaxation Of Imprinted Genes In Human Cancer

Abstract: GENOMIC imprinting, or parental allele-specific expression of genes, has been demonstrated at the molecular level in insects and mice1,2 but not in man. Imprinting as a potential mechanism of human disease is suggested by paternal uniparental disomy of 11 p15 in Beckwith–Wiedemann syndrome3 and by maternal uniparental disomy of 15ql1–12 in Prader–Willi syndrome4. Beckwith–Wiedemann syndrome is characterized by multiorgan overgrowth and predisposition to embryonal tumours such as Wilms9 tumour of the kidney5. A loss of heterozygosity of 11 p15 is also frequently found in a wide variety of tumours, including Wilms' tumour and lung, bladder, ovarian, liver and breast cancers6–11; 11pl5 also directly suppresses tumour growth in vitro12. Two genes in this band, H19 and insulin-like growth factor-II (IGF2) undergo reciprocal imprinting in the mouse, with maternal expression of H19 (ref. 13) and paternal expression of IGF2 (ref. 14). Here we find that both of these genes show monoallelic expression in human tissues and, as in mouse, H19 is expressed from the maternal allele and IGF2 from the paternal allele. In contrast, 69% of Wilms' tumours not undergoing loss of heterozygosity at lip showed biallelic expression of one or both genes, suggesting that relaxation or loss of imprinting could represent a new epigenetic mutational mechanism in carcinogenesis.

Foucault, power/knowledge, and its relevance for human resource management

Abstract: Drawing on the work of Michel Foucault. I argue that human resource management (HRM) may be best understood as a discourse and set of practices that attempt to reduce the indeterminacy involved in the employment contract. Here I reread HRM practices from a Foucauldian power-knowledge perspective and suggest that this provides an avenue to reorient contemporary, historical, and comparative analyses of the area.

Negotiation of leisure constraints

Abstract: Virtually all past leisure constraints research has been based on a conception of constraints as insurmountable obstacles to leisure participation. Thus, it has typically been assumed that if an individual encounters a constraint, the outcome will be nonparticipation. This article elaborates an alternative view of constraints that has recently begun to appear in the literature, summarized in the central proposition that leisure participation is dependent not on the absence of constraints but on negotiation through them. Such negotiation may modify participation rather than foreclosing it. Evidence from the existing literature for the negotiation proposition is examined, and five additional propositions are defined concerning relative success in negotiating constraints, interactions between different types of constraints, and balance between constraints and motivations.

Anxiogenic stimuli in the elevated plus-maze

Abstract: Untreated rats normally avoid the open arms of the "elevated plus-maze," preferring instead the closed arms, whereas rats treated with antianxiety drugs (e.g., diazepam) show far less open-arm avoidance. Although it has often been assumed that rats avoid the open arms because of novelty, height, or open space, the anxiogenic role of these stimuli in the plus-maze has not been systematically examined. In Experiment 1, rats were repeatedly exposed to the elevated plus-maze with the expectation that their "fear" of the open arms would habituate over trials. Instead, open-arm avoidance actually increased on the second trial and showed no evidence of habituating after 18 trials. In Experiment 2, three 30-min sessions of confinement to the open arms ("flooding") failed to decrease rats' open-arm avoidance. Instead, rats that had received flooding avoided the open arms significantly more than control rats during the first test. Experiment 3 showed that although diazepam-treated rats avoided the open arms less than vehicle-controls on the first test this difference dissipated across test trials. Further, diazepam had no carryover effect on rats' subsequent avoidance of the open arms in a nondrugged state. In Experiment 4, plus-maze height was varied from 50 to 6 cm, but rats did not display more open-arm activity as maze height decreased. In Experiment 5, height cues were manipulated by placing a "floor" 8 cm beneath one open arm while leaving the floor of the other open arm at 50 cm. Rats did not avoid the "low" open arm less than the "high" open arm.(ABSTRACT TRUNCATED AT 250 WORDS)

Common Principles of Motor Control in Vertebrates and Invertebrates

Abstract: Comparative neurobiology has proven to be a powerful discipline for elucidating the principles that describe the evolution, development, and functioning of the nervous system (Arb as et a11991; Cohen & Strumwasser 1985; Heiligenberg 1991). Studies on invertebrates have contributed sub­ stantially to establishing many of these principles. Some noteworthy ex­ amples are the mechanisms that establish the diversity of potassium chan­ nels (Jan & Jan 1990; MacKinnon 1991), the ionic mechanisms that generate action potentials (Hodgkin & Huxley 1952), and the cellular and molecular events that underlie learning and memory (Carew & Sahley 1986; Hawkins & Kandel 1990). The analysis of more complex integrative processes has also benefited from studies of invertebrate nervous systems. One example is the influence that the finding of lateral inhibition in the eye of Limulus (Hartline et al 1956) had on our understanding of sensory processing in more complex systems. Another is the profound effect that the analysis of rhythmic motor systems in invertebrates has had on inves­ tigations on rhythmic pattern generating networks in vertebrates (Getting 1988; Grillner 1981; Grillner & Wallen 1985). More recently, the utility of analyzing the action of neuromodulator� on the functioning of neuronal

The textual approach: Risk and blame in disaster sensemaking

Abstract: This article presents and illustrates the textual approach to qualitative research. In this approach, ethnography is used to observe organizational events and to gain access to related textual or d...

Box Splines

Abstract: This chapter provides a brief introduction to box and half-box splines with particular focus on triangular splines and surface design. A particular example of box splines are the B-splines with equidistant knots. In general, box splines consist of regularly arranged polynomial pieces and they have a useful geometric interpretation. Namely they can be viewed as density functions of the shadows of higher dimensional boxes and half-boxes. Of particular interest for Geometric Design are box spline surfaces that consist of triangular polynomial pieces. These box spline surfaces have planar domains, but it is quite simple to construct arbitrary two-dimensional surfaces, i.e., manifolds, with these box splines.

Quality of life: a concept analysis

Abstract: Quality of life (QOL) is a phrase which was first used shortly after the Second World War and has, since then, been overused and infrequently defined. A concept analysis of QOL is presented to clarify the concept for further use. The process for concept analysis developed by Walker & Avant is employed. Quality of life is found to be very complex, and it is hoped that this analysis will stimulate thought and further nursing research into what QOL means in the health care context.

Reversal of the influence of group Ib afferents from plantaris on activity in medial gastrocnemius muscle during locomotor activity

Abstract: 1. Rhythmic locomotor activity was evoked in clonidine-treated acute and chronic spinal cats, and the effect of stimulating group I afferents from the plantaris muscle on the timing and magnitude of bursts in medial gastrocnemius (MG) motoneurons was examined. 2. The locomotor rhythm was entrained when group I afferents in the plantaris nerve were electrically stimulated with trains of stimuli presented at rates above and below the intrinsic frequency of the rhythmic activity. During entrainment at rates higher than the intrinsic frequency, a burst of activity in ipsilateral MG motoneurons was initiated approximately 40 ms after the onset of each stimulus train. At lower rates of entrainment the onset of MG bursts preceded the onset of the stimulus trains, and each stimulus train had an excitatory effect on the MG burst with a latency in the range of 30-50 ms. A similar excitatory effect was observed when the stimulus trains were triggered at a preset delay after the endogenous generation of the MG bursts. 3. The excitatory action of plantaris group I afferents on the MG motoneurons was only seen during periods of locomotor activity. In the absence of rhythmic activity, the same stimulus trains reduced any ongoing tonic activity in MG motoneurons. 4. Vibration of the plantaris muscle to preferentially activate group Ia afferents neither entrained the locomotor rhythm nor increased the magnitude of the MG bursts. 5. We conclude that during locomotor activity, input from group Ib afferents of the plantaris muscle has an excitatory action on the system of interneurons generating the extensor bursts, i.e., on the extensor half-center of the central rhythm generator.(ABSTRACT TRUNCATED AT 400 WORDS)

Collective robotics: from social insects to robots

Abstract: Achieving tasks with multiple robots will require a control system that is both simple and scalable as the number of robots increases. Collective behavior as demonstrated by social insects is a form of decentralized control that may prove useful in controlling multiple robots. Nature's several examples of collective behavior have motivated our approach to controlling a multiple robot system using a group behavior. Our mechanisms, used to invoke the group behavior, allow the system of robots to perform tasks without centralized control or explicit communication. We have constructed a system of five mobile robots capable of achieving simple collective tasks to verify the results obtained in simulation. The results suggest that decentralized control without explicit communication can be used to perform cooperative tasks requiring a collective behavior.

Performance of subcutaneously implanted needle-type glucose sensors employing a novel trilayer coating

Abstract: A miniature, needle-type glucose sensor based on a new trilayer membrane configuration has been prepared and evaluated both in vitro and in vivo. The perfluorinated ionomer, Nafion, was used as a protective, biocompatible, outer coating, and poly(o-phenylenediamine) as an inner coating to reduce interference by small, electroactive compounds. Glucose oxidase immobilized in a bovine serum albumin matrix was sandwiched between these coatings. The entire sensor assembly of Pt working electrode and Ag/AgCl reference electrode was 0.5 mm in diameter and could be inserted subcutaneously through an 18-gauge needle. The sensor current closely followed the plasma glucose level during a glucose tolerance test in active dogs, with a delay of 3 min, corresponding to the known lag time for subcutaneous glucose levels. The sensor remained functional after 1 week of implantation, but failed after 2 weeks due to degradation of the reference electrode. In vitro tests in pH 7.4 buffer or whole blood show the sensors have good selectivity, sensitivity of about 25 nA/mM, precision of 2-5%, and a 90% response time of 33 s. Stabilization following polarization requires 10-30 min in vitro and 30-40 min in vivo.

Differential scanning calorimetric study of the effect of cholesterol on the thermotropic phase behavior of a homologous series of linear saturated phosphatidylcholines.

Abstract: We have studied the effects of cholesterol on the thermotropic phase behavior of aqueous dispersions of a homologous series of linear saturated phosphatidylcholines, using high-sensitivity differential scanning calorimetry and an experimental protocol which ensures that broad, low-enthalpy phase transitions are accurately monitored. We find that the incorporation of small amounts of cholesterol progressively decreases the temperature and the enthalpy, but not the cooperativity, of the pretransition of all phosphatidylcholines exhibiting such a pretransition and that the pretransition is completely abolished at cholesterol concentrations above 5 mol % in all cases. The incorporation of increasing quantities of cholesterol also alters the main or chain-melting phase transition of these phospholipid bilayers in both hydrocarbon chain length-dependent and hydrocarbon chain length-independent ways. At cholesterol concentrations of from 1 to 20-25 mol %, the DSC endotherms of all phosphatidylcholines studied consist of a superimposed sharp and broad component, the former ascribed to the melting of cholesterol-poor and the latter to the melting of the cholesterol-rich phosphatidylcholine domains. The temperature and cooperativity of the sharp component are reduced only slightly and in a chain length-independent manner with increasing cholesterol concentration, an effect we ascribe to the colligative effect of the presence of small quantities of cholesterol at the domain boundaries. Moreover, the enthalpy of the sharp component decreases and becomes zero at 20-25 mol % cholesterol for all of the phosphatidylcholines examined.(ABSTRACT TRUNCATED AT 250 WORDS)

A review of factors that regulate carotenoid and chlorophyll deposition and fossil pigment abundance

Abstract: Limnological surveys show that fossil pigment concentration is an accurate predictor of algal production. However, experimental and mass flux studies indicate that >90% of pigment is degraded to colourless compounds before permanent burial. To reconcile these views, this paper reviews current literature on pigment degradation and proposes a hierarchical control model for pigment deposition and fossil abundance. Over the widest range of production, pigment deposition and fossil concentration are proportional to algal standing crop. However, within a narrower range, the actual concentration of pigment in sediments is regulated by photo- and chemical oxidation. Three phases of loss exist: rapid oxidation in the water column (T1/2=days); slower post-depositional loss in surface sediments (T1/2=years); and very slow loss of double bonds in deep sediments (T1/2=centuries). Despite losses during deposition, fossil and algal abundance remain correlated through time, so long as there is no change in basin morphometry, light penetration, stratification or deepwater oxygen content. At the finest scale, food-web processes can increase the preservation of pigments from edible algae by incorporating pigments into feces that sink rapidly and bypass water column losses. As a consequence of selective loss during deposition and initial burial, carotenoid relative abundance is an unreliable measure of phytoplankton community composition. Instead, absolute concentration — scaled to the historical maximum — should be used for fossil interpretations.

Cloning and nucleotide sequence of the Campylobacter jejuni gyrA gene and characterization of quinolone resistance mutations.

Abstract: The gyrA gene of Campylobacter jejuni UA580, which encodes the A subunit of DNA gyrase, was cloned and its nucleotide sequence was determined. An open reading frame of 2,589 nucleotides was identified, which could code for a polypeptide of 863 amino acids with a M(r) of 97 kDa. Both the nucleotide sequence and the putative amino acid sequence show ca. 50% identity with those of other gyrA genes from gram-positive and gram-negative bacteria. The locations of the gyrA gene on genome maps of both C. jejuni UA580 and Campylobacter coli UA417 were determined. Six nalidixic acid-resistant isolates of C. jejuni were shown to carry mutations in gyrA. Three clinical isolates had Thr-86-to-Ile substitutions. Three laboratory mutants had substitutions of Thr-86 to Ile, Asp-90 to Ala, and Ala-70 to Thr, respectively. The mutation at Thr-86, which is homologous to Ser-83 in Escherichia coli, was associated with high-level resistance to ciprofloxacin in C. jejuni.