Showing papers by "University of Waterloo published in 1999"
TL;DR: This article found that when the test was described as producing gender differences and stereotype threat was high, women performed substantially worse than equally qualified men did on difficult (but not easy) math tests among a highly selected sample of men and women.
3,093 citations
TL;DR: This review attempts to delineate common themes on the physiological and metabolic roles of cortisol in teleost fishes and to suggest new approaches that might overcome some of the inconsistencies on the role of this multifaceted hormone.
Abstract: Cortisol is the principal corticosteriod in teleost fishes and its plasma concentrations rise dramatically during stress. The relationship between this cortisol increase and its metabolic consequences are subject to extensive debate. Much of this debate arises from the different responses of the many species used, the diversity of approaches to manipulate cortisol levels, and the sampling techniques and duration. Given the extreme differences in experimental approach, it is not surprising that inconsistencies exist within the literature. This review attempts to delineate common themes on the physiological and metabolic roles of cortisol in teleost fishes and to suggest new approaches that might overcome some of the inconsistencies on the role of this multifaceted hormone. We detail the dynamics of cortisol, especially the exogenous and endogenous factors modulating production, clearance and tissue availability of the hormone. We focus on the mechanisms of action, the biochemical and physiological impact, and the interaction with other hormones so as to provide a conceptual framework for cortisol under resting and/or stressed states. Interpretation of interactions between cortisol and other glucoregulatory hormones is hampered by the absence of adequate hormone quantification, resulting in correlative rather than causal relationships.
2,139 citations
TL;DR: In this paper, a psychometrically sound scale was developed to measure the construct of commitment, and the scale was then used in a mediating effects model (M-E-M) to test the commitment-loyalty link.
Abstract: This study addressed the ill-understood issue of how loyalty develops in service patrons. Although many theorists hold commitment to be an essential part of this process, the link between commitment and loyalty has received little empirical attention. To address this void, the study first portrayed commitment’s root tendency to resist changing preference as a function of three antecedent processes. Second, this portrayal formed the basis for developing a psychometrically sound scale to measure the construct of commitment. Third, the scale was then used in a mediating effects model (M-E-M) to test the commitment-loyalty link. Path analyses found this parsimonious structure to be a significant improvement over rival direct effects models (D-E-Ms). Results found the tendency to resist changing preference to be a key precursor to loyalty, largely explained by a patron’s willingness to identify with a brand. Implications of these findings for loyalty’s development and research are explored.
1,068 citations
TL;DR: Healthy young men and women possess different endurance profiles for the spine stabilizing musculature, and data of endurance times and their ratios between extensor, flexor, and lateral flexor groups in healthy normal subjects are useful for patient evaluation and for providing clinical training targets.
654 citations
TL;DR: In this paper, a multiresolution signal decomposition technique is used to detect and localize transient events and furthermore classify different power quality disturbances, which can also be used to distinguish among similar disturbances.
Abstract: The wavelet transform is introduced as a powerful tool for monitoring power quality problems generated due to the dynamic performance of industrial plants. The paper presents a multiresolution signal decomposition technique as an efficient method in analyzing transient events. The multiresolution signal decomposition has the ability to detect and localize transient events and furthermore classify different power quality disturbances. It can also be used to distinguish among similar disturbances.
603 citations
12 Aug 1999
TL;DR: The improved method possesses many desirable features for implementing elliptic curves in restricted environments and requires less memory than projective schemes and the amount of computation needed for a scalar multiplication is fixed for all multipliers of the same binary length.
Abstract: This paper describes an algorithm for computing elliptic scalar multiplications on non-supersingular elliptic curves defined over GF(2m). The algorithm is an optimized version of a method described in [1], which is based on Montgomery's method [8]. Our algorithm is easy to implement in both hardware and software, works for any elliptic curve over GF(2m), requires no precomputed multiples of a point, and is faster on average than the addition-subtraction method described in draft standard IEEE P1363. In addition, the method requires less memory than projective schemes and the amount of computation needed for a scalar multiplication is fixed for all multipliers of the same binary length. Therefore, the improved method possesses many desirable features for implementing elliptic curves in restricted environments.
567 citations
TL;DR: This work portrays these systems as Self-Organizing Holarchic Open (SOHO) systems and interpret their behaviours and structures with reference to non-equilibrium thermodynamics: holons, propensities and canons; and information and attractors.
491 citations
TL;DR: A review of Wegner's seminal investigations of effects of thought suppression on later thought frequency, including the findings and their relevance for existing models of specific disorders is provided.
447 citations
01 Jan 1999
TL;DR: The Prouhet-Thue-Morse sequence appears to be somewhat ubiquitous, and it is described many of its apparently unrelated occurrences.
Abstract: We discuss a well-known binary sequence called the Thue-Morse sequence, or the Prouhet-Thue-Morse sequence This sequence was introduced by Thue in 1906 and rediscovered by Morse in 1921 However, it was already implicit in an 1851 paper of Prouhet The Prouhet-Thue-Morse sequence appears to be somewhat ubiquitous, and we describe many of its apparently unrelated occurrences
444 citations
TL;DR: In this paper, the gap between ecotourism theory and practice as indicated by its on-site application is examined and a framework is suggested which, if implemented through appropriate management, can help to achieve a balance between conservation and development through the promotion of synergistic relationships between natural areas, local populations and tourism.
441 citations
TL;DR: The studies reinforce the conclusion that lens hardening must be considered as an important factor in the development of presbyopia, that age changes in the human lens are not limited to the loss of accommodation that characterizes Presbyopia but that the lens optical and physical properties change substantially with age in a complex manner.
TL;DR: In this article, the Revised Universal Soil Loss Equation (RUSLE) was integrated with a Geographic Information System (GIS) to model erosion potential for soil conservation planning within the Sierra de Manantlan Biosphere Reserve (SMBR), Mexico.
Abstract: This research integrates the Revised Universal Soil Loss Equation (RUSLE) with a Geographic Information System (GIS) to model erosion potential for soil conservation planning within the Sierra de Manantlan Biosphere Reserve (SMBR), Mexico. Mountainous topography and a tropical uni-modal precipitation regime characterize this region. These unique climatic and topographic characteristics required a modification of the standard RUSLE factors and their derivation. The resulting RUSLE–GIS model provides a robust soil conservation planning tool readily transferable and accessible to other land managers in similar environments. Future pressure to expand agriculture and grazing operations within the SMBR will unquestionably accentuate the already high rate of soil erosion and resultant sediment loading of watercourses occurring in this region. Until recently there did not exist a reliable or financially viable means to model and map soil erosion within large remote areas. An increase in the reliability and resolution of remote sensing techniques, modifications and advancements in watershed scale soil erosion modelling techniques, and advances in GIS, represent significantly improved tools that can be applied to both monitoring and modelling the effects of land use on soil erosion potential. Data used in this study to generate the RUSLE variables include a Landsat Thematic Mapper image (land cover), digitized topographic and soil maps, and tabular precipitation data. Soil erosion potential was modelled within Zenzontla, a sub-catchment of the Rio Ayuquila, located in the SMBR, and the results are presented as geo-referenced maps for each of the wet and dry precipitation seasons. These maps confirm that high and extreme areas of soil loss occur within the Zenzontla sub-catchment, and that erosion potential differs significantly between wet and dry seasons.
TL;DR: It is concluded that calcium supplementation leads to a small reduction in systolic and diastolic blood pressure and the effect of supplemental calcium in the diet is at least as great as nondietary supplementation.
TL;DR: In this article, a pyrochlore antiferromagnet in which the moments reside on a network of corner-sharing tetrahedra was studied. But unlike other geometrically frustrated systems, this system remains paramagnetic down to 0.07 K, rather than ordering into a conventional N\'eel or spin-glass-like state.
Abstract: Neutron scattering, muon spin relaxation, and dc susceptibility studies have been carried out on polycrystalline ${\mathrm{Tb}}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$, a pyrochlore antiferromagnet in which the ${\mathrm{Tb}}^{3+}$ moments reside on a network of corner-sharing tetrahedra. Unlike other geometrically frustrated systems, ${\mathrm{Tb}}_{2}{\mathrm{Ti}}_{2}{\mathrm{O}}_{7}$ remains paramagnetic down to $\ensuremath{\sim}0.07\mathrm{K}$, rather than ordering into a conventional N\'eel or spin-glass-like state, despite the fact that short-range antiferromagnetic correlations (AFC) develop at $\ensuremath{\sim}50\mathrm{K}$. At the first AFC wave vector, its low-lying, relatively flat magnetic excitation spectrum softens partially below 30 K.
TL;DR: In this article, the first nontrivial approximation algorithms for the Steiner tree problem and the generalized Steiner network problem on general directed graphs were given, achieving an approximation ratio of O(i?1)k1/i in time O(nik2i) where k is the number of terminals.
TL;DR: The study documented, in vivo, the role of CD36 to facilitate cellular FA uptake and illustrated importance of the uptake process in muscle to overall FA metabolism and glucose utilization.
TL;DR: The results show the CNS uses two mechanisms, foot placement and trunk roll motion (piking action about the hip joint in the frontal plane), to move the center of mass towards the new direction of travel in the transition stride, preferring to use the first option when planning can be done early.
Abstract: Steering is an integral component of adaptive locomotor behavior. Along with reorientation of gaze and body in the direction of intended travel, body center of mass must be controlled in the mediolateral plane. In this study we examine how these subtasks are sequenced when steering is planned early or initiated under time constraints. Whole body kinematics were monitored as individuals were required to change their direction of travel by varying amounts when visually cued either at the beginning of the walk or one stride before. The analyses focused on the transition stride from one travel direction to another. Timing of changes (with respect to first right foot contact) in trunk roll angle, head and trunk yaw angle, and right foot displacement in the mediolateral plane were analyzed. The magnitude of these measures along with right and left foot placement at the beginning and right foot placement at the end of the transition stride were also analyzed. The results show the CNS uses two mechanisms, foot placement and trunk roll motion (piking action about the hip joint in the frontal plane), to move the center of mass towards the new direction of travel in the transition stride, preferring to use the first option when planning can be done early. Control of body center of mass precedes all other changes and is followed by initiation of head reorientation. Only then is the rest of the body reorientation initiated.
TL;DR: In this article, the authors used NO3−/Cl− ratios, natural abundances of 15N and 18O in NO3+ and an in situ 15NO3− tracer experiment to evaluate NO3 − reducing processes occurring in ground water within a narrow grassed buffer strip bordering a stream in an agricultural watershed.
Abstract: During the last 40 years, nitrate (NO3−) has become one of the most common ground water contaminants. Stream riparian zones are considered important ecological ecotones that decrease the NO3− load of ground water discharging into streams. This study uses NO3−/Cl− ratios, natural abundances of15N and18O in NO3−, and an in situ15NO3− tracer experiment to evaluate NO3− reducing processes occurring in ground water within a narrow grassed buffer strip bordering a stream in an agricultural watershed. The NO3−/Cl− ratios (1.9-0.0 [M/M]) indicate that both NO3− consuming processes and mixing of two ground water flow regimes with different NO3− loads contribute to the drop observed in ground water NO3− concentrations within the riparian zone. δ15N and δ18O of the ground water NO3− within the riparian zone (δ15N = 5.1 to 48.8 %c; δ18O = 1.1 to 17.8 %c) were enriched compared to the ground water below the adjacent cultivated field (δ15N = 3.8 to 10.1 %0; δ18O = 0.5 to 6.2 %c). A significant linear relationship (r2=0.97) between ground water δ15N and δ18O in NO3− was found, which is consistent with NO3− consumption by microbial denitrification. The estimated enrichment factors for15N are a factor of 1.5 higher than for18O. The in situ15NO3− tracer experiment conclusively confirmed that denitrification is occurring within the ground water of the riparian zone and demonstrates that denitrification rates can be directly measured in situ.
TL;DR: In this paper, the occurrence of carbon isotope fractionation during dechlorination of tetrachloroethene (PCE) to ethene was evaluated in a PCE-contaminated aquifer and in a microcosm that was based on aquifer material from the site.
Abstract: The determination of compound-specific stable isotope ratios is a promising new tool to assess biodegradation of organic compounds in groundwater. In this study, the occurrence of carbon isotope fractionation during dechlorination of tetrachloroethene (PCE) to ethene was evaluated in a PCE-contaminated aquifer and in a microcosm that was based on aquifer material from the site. In the microcosm, all dechlorination steps were accompanied by carbon isotope fractionation. The largest fractionation occurred during dechlorination of cis-1,2-dichloroethene (cDCE) and vinyl chloride (VC), resulting in a large enrichment of 13C in the remaining cDCE and VC. Stable carbon isotope ratios (δ13C) of cDCE and VC increased from −25.7 to −1.5‰ and −37.0 to −2.5‰, respectively. The δ13C of ethene was initially −60.2‰ and approached the δ13C of the added PCE (−27.3‰) as dechlorination came to completion. A similar carbon isotope pattern was observed for PCE dechlorination at the field site. Strong enrichment of 13C in cDC...
TL;DR: In this paper, Watershed water flow and geochemical measurements were taken along a transect of monitoring wells extending across the riparian area into an agricultural field, and a sharp decline in both nitrate and chloride concentrations was observed near the field-riparian zone boundary.
TL;DR: The IAP mechanism for stabilizing the lumbar spine appears preferable in tasks that demand trunk extensor moment such as lifting or jumping because it can increase spine stability without the additional coactivation of erector spinae muscles.
TL;DR: The data support the hypothesis that PCA60 plays a role in preventing denaturation of proteins exposed to dehvdrative stresses, and the first time antifreeze activity has been demonstrated for dehydrins.
Abstract: Dehydrins are glycine-rich, hydrophilic, heat-stable proteins and are generally induced in response to a wide array of environmental stresses. In previous research (Artlip et al. 1997, Plant Molecular Biology 33: 61-70), a full-length dehydrin gene, ppdhn1, was isolated from peach, and its expression was associated with qualitative and quantitative differences in cold hardiness in sibling genotypes of evergreen and deciduous peach. Similar results were obtained for levels of the corresponding 60 kDa peach dehydrin protein (PCA60). The objective of the present study was to purify the PCA60, test the purified protein for cryoprotective and/or antifreeze activity, and to determine the cellular localization of PCA60 using immunomicroscopy. PCA60 was extracted from winter bark tissues of peach (Prunus persica [L.] Batsch) and purified in a two-step process. Separation was based on free-solution isoelectric focusing followed by size exclusion. Purified PCA60, as well as crude protein extract, preserved the in vitro enzymatic activity of lactate dehydrogenase after several freeze-thaw cycles in liquid nitrogen. PCA also exhibited distinct antifreeze activity as evidenced by ice crystal morphology and thermal hysteresis. This is the first time antifreeze activity has been demonstrated for dehydrins. Immunomicroscopy, utilizing an affinity-purified, polyclonal antibody developed against a synthetic peptide of the lysine-rich consensus portion of dehydrins, indicated that PCA60 was freely distributed in the cytoplasm, plastids, and nucleus of bark cells and xylem parenchyma cells. Although the functional role of dehydrins remains speculative, the data support the hypothesis that it plays a role in preventing denaturation of proteins exposed to dehvdrative stresses.
TL;DR: In this article, the authors present detailed steady-state models with controls of two flexible AC transmission system controllers, namely, static VAr compensators (SVCs) and thyristor controlled series capacitors (TCSCs), to study their effect on voltage collapse phenomena in power systems.
Abstract: This paper presents detailed steady-state models with controls of two flexible AC transmission system (FACTS) controllers, namely, static VAr compensators (SVCs) and thyristor controlled series capacitors (TCSCs), to study their effect on voltage collapse phenomena in power systems. Based on results at the point of collapse, design strategies are proposed for these two controllers, so that their location, dimensions and controls can be optimally defined to increase system loadability. A European system is used to illustrate the application of all proposed models and techniques.
TL;DR: A primal-dual interior-point algorithm is introduced that solves an equivalent (quadratic objective function) semidefinite programming problem (SDP) and demonstrates the efficiency and robustness of this approach.
Abstract: Given a partial symmetric matrix A with only certain elements specified, the Euclidean distance matrix completion problem (EDMCP) is to find the unspecified elements of A that make A a Euclidean distance matrix (EDM). In this paper, we follow the successful approach in [20] and solve the EDMCP by generalizing the completion problem to allow for approximate completions. In particular, we introduce a primal-dual interior-point algorithm that solves an equivalent (quadratic objective function) semidefinite programming problem (SDP). Numerical results are included which illustrate the efficiency and robustness of our approach. Our randomly generated problems consistently resulted in low dimensional solutions when no completion existed.
TL;DR: The root mean square in the medial-lateral direction was reliable and sensitive enough to measure an increase in postural sway of chronic low back pain patients as a group compared to healthy controls when the task involved increased complexity and removal of visual information.
TL;DR: Improved comfort and relief of dryness were the primary factors that would improve contact lens wear for the group that had discontinued, and Practitioners may be able to target specific patient groups with remedial measures to improve contact Lens-wearing success.
TL;DR: A review of biochemical evidence suggests that a given respiratory rate is a function of the net drive of phosphorylation potential and redox potential and cellular mitochondrial PO2 (PmitoO2), which appears to be within a range capable of modulating muscle metabolism.
Abstract: Considerable debate surrounds the issue of whether the rate of adaptation of skeletal muscle O2 consumption (Q˙o 2) at the onset of exercise is limited by1) the inertia of intrinsic cellular metabo...
TL;DR: In this paper, the authors present a review of existing knowledge of conceptual and measurement issues related to leisure involvement, and present a three-category classification scheme for analyzing the propositions, which are indexed using their original Roman numeral designations.
Abstract: Introduction . . past territorial piss-posts, past whispers in the closets, past screamin' from the rooftops, we live to survive our paradoxes. . . -Springtime in Vienna (The Tragically Hip, 1996) Given that propositions papers are developed for the expressed purpose of guiding future research efforts, it is appropriate to occasionally examine the extent to which stated propositions have withstood further scrutiny. Building on our recent review piece which critiqued current knowledge of conceptual and measurement issues related to leisure involvement (Havitz & Dimanche, 1997) this paper will critique and extend existing involvement research by synthesizing knowledge within the framework of the Havitz and Dimanche (1990) propositions paper. The present focus is on the consequences of involvement. Thirteen propositions focusing on relationships between leisure involvement and promotion, purchase decisions, and participation patterns are examined. Temporal stability, the study of leisure involvement over time, and attempts to link leisure involvement with sociodemographic characteristics are also critiqued. A summary of key issues for improving future research is provided at the end of each section and general conclusions are drawn at the end of the paper. We developed a three-category classification scheme for analyzing the propositions, which are indexed using their original Roman numeral designations. Those which have received consistent to unqualified support from multiple data sets were categorized as having received strong support. Propositions which have received support from some data sets, but nearly equal levels of non-support from others were described as attaining moderate support. Those receiving support from few studies and/or when non-support is more common were characterized as receiving limited support. The distinctions between categories are not absolute. Because placement of research related to each proposition into the classification scheme is based upon our subjective judgement, it is intended only as a heuristic guide. We define involvement as an unobservable state of motivation, arousal or interest toward a recreational activity or associated product. It is evoked by a particular stimulus or situation and has drive properties (adapted from Rothschild, 1984). In other words, involvement refers to how we think about our leisure and recreation, and it affects our behavior as well. Leisure involvement has usually been treated as a multifaceted construct including attraction, sign, centrality, and risk. Inconsistent use of these and other lesser reported facets and antecedents by various researchers has complicated interpretation of leisure involvement research. To date, facet-related debate and measurement issues remain contentious and unresolved (Havitz & Dimanche, 1997; Ragheb, 1996). Does Involvement Mediate Purchase, Use and Participation Patterns? Our original propositions VI through XII speak to a central tenet of social judgement theory: latitude of acceptance and rejection. As such, we chose to examine them first in this review. Sherif, Sherif, & Nebergall (1965) posited that persons with higher levels of ego involvement will have relatively narrow ranges of acceptance and relatively broad ranges of rejection relative to persons with lower levels of ego involvement. Early involvement research was conducted primarily in the contexts of compelling social and political issues. By the mid-1960s, consumer researchers had broadened the scope of investigation with mixed success. Reviewing those efforts, Kassarjian & Kassarjian (1977) wryly noted that, "Theoretical positions based on the influence of anti-Semitic attitudes on the selection of a political candidate, antiRussian fears in the support of a defense establishment, or the influence on attitudes of emotional concerns about getting killed in war have been wholly borrowed and applied to the selection of instant coffee, toothpaste, and canned peas" (p. …
TL;DR: In this article, a table of gas-phase Na+ affinities for organic and small biological molecules with a wide variety of functional groups is presented, with an accuracy of ca. 1 kcal·mol-1.
Abstract: High-pressure mass spectrometric experiments and ab initio calculations have been carried out in order to establish a series of accurate gas-phase sodium ion affinities of organic molecules with a wide variety of functional groups. Ab initio calculations have also been performed on the sodium complexes of three amino acids: serine, cysteine, and proline. A systematic critical evaluation of experimental and computational literature results shows that a significant number require revision. Based on comparisons with accurate experimental measurements, the ab initio procedure used is shown to yield sodium ion affinities with an accuracy of ca. 1 kcal·mol-1. This enables the construction of the first reliable table of gas-phase Na+ affinities for organic and small biological molecules.
TL;DR: In this article, the authors apply a framework for the development and evaluation of ecotourism to three protected areas in North Sulawesi, and evaluate the status of tourism in these areas.