Showing papers by "Queen's University published in 2004"

Functions of a Complex Variable

Abstract: In earlier chapters, complex-valued functions appeared in connection with Fourier series expansions. In this context, while the function assumes complex values, the argument of the function is real-valued. There is a highly developed theory of (complex-valued) functions of a complex-valued argument. This theory contains some remarkably powerful results which are applicable to a variety of problems.

Look away: the anti-saccade task and the voluntary control of eye movement

Abstract: The anti-saccade task has emerged as an important task for investigating the flexible control that we have over behaviour. In this task, participants must suppress the reflexive urge to look at a visual target that appears suddenly in the peripheral visual field and must instead look away from the target in the opposite direction. A crucial step involved in performing this task is the top-down inhibition of a reflexive, automatic saccade. Here, we describe recent neurophysiological evidence demonstrating the presence of this inhibitory function in single-cell activity in the frontal eye fields and superior colliculus. Patients diagnosed with various neurological and/or psychiatric disorders that affect the frontal lobes or basal ganglia find it difficult to suppress the automatic pro-saccade, revealing a deficit in top-down inhibition.

Skeletal Muscle Cutpoints Associated with Elevated Physical Disability Risk in Older Men and Women

Abstract: The purpose of this study was to determine skeletal muscle cutpoints for identifying elevated physical disability risk in older adults. Subjects included 4,449 older (> or = 60 years) participants from the Third National Health and Nutrition Examination Survey during 1988-1994. Physical disability was assessed by questionnaire, and bioimpedance was used to estimate skeletal muscle, which was normalized for height. Receiver operating characteristics were used to develop the skeletal muscle cutpoints associated with a high likelihood of physical disability. Odds for physical disability were compared in subjects whose measures fell above and below these cutpoints. Skeletal muscle cutpoints of 5.76-6.75 and < or =5.75 kg/m2 were selected to denote moderate and high physical disability risk in women. The corresponding values in men were 8.51-10.75 and < or =8.50 kg/m2. Compared with women with low-risk skeletal muscle values, women with moderate- and high-risk skeletal muscle values had odds for physical disability of 1.41 (95% confidence interval (CI): 0.97, 2.04) and 3.31 (95% CI: 1.91, 5.73), respectively. The corresponding odds in men were 3.65 (95% CI: 1.92, 6.94) and 4.71 (95% CI: 2.28, 9.74). This study presents skeletal muscle cutpoints for physical disability risk in older adults. Future applications of these cutpoints include the comparison of morbidity risk in older persons with normal muscle mass and those with sarcopenia, the determination and comparison of sarcopenia prevalences, and the estimation of health-care costs attributable to sarcopenia.

Efficient waveform inversion and imaging: A strategy for selecting temporal frequencies

Abstract: Prestack migration and/or inversion may be implemented in either the time or the frequency domain. In the frequency domain, it is possible to discretize the frequencies with a much larger sampling interval than that dictated by the sampling theorem and still obtain an imaging result that does not suffer from aliasing (wrap around) in the depth domain. The selection of input frequencies can be reduced when a range of offsets is available; this creates a redundancy of information in the wavenumber coverage of the target. In order to optimize the use of this information, we define a new discretization strategy that depends on the maximum effective offset present in the surface seismic survey: the larger the range of offsets, the fewer frequencies are required. The strategy, exact in a homogeneous 1D earth, selects frequencies by making use of the well-known effect of image stretch in normal-moveout (NMO) correction and in migration (usually considered detrimental for the imaging). The strategy is also useful in more general earth models: we apply it to the 2D Marmousi model and recover a continuous range of wavenumbers using only three input frequencies. The Marmousi inversion result accurately predicts all other data frequencies, demonstrating the redundancy of the data.

Optimal feedback control and the neural basis of volitional motor control

Abstract: Skilled motor behaviour, from the graceful leap of a ballerina to a precise pitch by a baseball player, appears effortless but reflects an intimate interaction between the complex mechanical properties of the body and control by a highly distributed circuit in the CNS An important challenge for understanding motor function is to connect these three levels of the motor system — motor behaviour, limb mechanics and neural control Optimal feedback control theory might provide the important link across these levels of the motor system and help to unravel how the primary motor cortex and other regions of the brain plan and control movement

Associations between Overweight and Obesity with Bullying Behaviors in School-Aged Children

Abstract: Objective. The prevalence of overweight and obesity in children is rising. Childhood obesity is associated with many negative social and psychological ramifications such as peer aggression. However, the relationship between overweight and obesity status with different forms of bullying behaviors remains unclear. The purpose of this article is to examine these relationships. Methods. We examined associations between bullying behaviors (physical, verbal, relational, and sexual harassment) with overweight and obesity status in a representative sample of 5749 boys and girls (11–16 years old). The results were based on the Canadian records from the 2001/2002 World Health Organization Health Behaviour in School-Aged Children Survey. Body mass index (BMI) and bullying behaviors were determined from self-reports. Results. With the exception of 15- to 16-year-old boys, relationships were observed between BMI category and peer victimization, such that overweight and obese youth were at greater relative odds of being victims of aggression than normal-weight youth. Strong and significant associations were seen for relational (eg, withdrawing friendship or spreading rumors or lies) and overt (eg, name-calling or teasing or hitting, kicking, or pushing) victimization but not for sexual harassment. Independent of gender, there were no associations between BMI category and bully-perpetrating in 11- to 14-year-olds. However, there were relationships between BMI category and bully-perpetrating in 15- to 16-year-old boys and girls such that the overweight and obese 15- to 16-year-olds were more likely to perpetrate bullying than their normal-weight classmates. Associations were seen for relational (boys only) and overt (both genders) forms of bully-perpetrating but not for sexual harassment. Conclusions. Overweight and obese school-aged children are more likely to be the victims and perpetrators of bullying behaviors than their normal-weight peers. These tendencies may hinder the short- and long-term social and psychological development of overweight and obese youth.

Adversaries of Consumption: Consumer Movements, Activism, and Ideology

Abstract: This article focuses on consumer movements that seek ideological and cultural change. Building from a basis in New Social Movement (NSM) theory, we study these movements among anti‐advertising, anti‐Nike, and anti‐GE food activists. We find activists’ collective identity linked to an evangelical identity related to U.S. activism’s religious roots. Our findings elucidate the value of spiritual and religious identities to gaining commitment, warn of the perils of preaching to the unconverted, and highlight movements that seek to transform the ideology and culture of consumerism. Conceiving mainstream consumers as ideological opponents inverts conventional NSM theories that view them as activists’ clients.

Effects of tiotropium on lung hyperinflation, dyspnoea and exercise tolerance in COPD.

Abstract: The aim of this study was to test the hypothesis that use of tiotropium, a new long-acting anticholinergic bronchodilator, would be associated with sustained reduction in lung hyperinflation and, thereby, would improve exertional dyspnoea and exercise performance in patients with chronic obstructive pulmonary disease. A randomised, double-blind, placebo-controlled, parallel-group study was conducted in 187 patients (forced expiratory volume in one second 44 +/- 13% pred): 96 patients received 18 microg tiotropium and 91 patients received placebo once daily for 42 days. Spirometry, plethysmographic lung volumes, cycle exercise endurance and exertional dyspnoea intensity at 75% of each patient's maximal work capacity were compared. On day 42, the use of tiotropium was associated with the following effects at pre-dose and post-dose measurements as compared to placebo: vital capacity and inspiratory capacity (IC) increased, with inverse decreases in residual volume and functional residual capacity. Tiotropium increased post-dose exercise endurance time by 105 +/- 40 s (21%) as compared to placebo on day 42. At a standardised time near end-exercise (isotime), IC, tidal volume and minute ventilation all increased, whilst dyspnoea decreased by 0.9 +/- 0.3 Borg scale units. In conclusion, the use of tiotropium was associated with sustained reductions of lung hyperinflation at rest and during exercise. Resultant increases in inspiratory capacity permitted greater expansion of tidal volume and contributed to improvements in both exertional dyspnoea and exercise endurance.

Sarcopenic obesity predicts instrumental activities of daily living disability in the elderly.

Abstract: Objective: To determine the association of sarcopenic obesity with the onset of Instrumental Activities of Daily Living (IADL) disability in a cohort of 451 elderly men and women followed for up to 8 years. Research Methods and Procedures: Sarcopenic obesity was defined at study baseline as appendicular skeletal muscle mass divided by stature squared <7.26 kg/m2 in men and 5.45 kg/m2 in women and percentage body fat greater than the 60th percentile of the study sample (28% body fat in men and 40% in women). Incident disability was defined as a loss of two or more points from baseline score on the IADL. Subjects with disability at baseline (scores < 8) were excluded. Cox proportional hazards analysis was used to determine the association of baseline sarcopenic obesity with onset of IADL disability, controlling for potential confounders. Results: Subjects with sarcopenic obesity at baseline were two to three times more likely to report onset of IADL disability during follow-up than lean sarcopenic or nonsarcopenic obese subjects and those with normal body composition. The relative risk for incident disability in sarcopenic obese subjects was 2.63 (95% confidence interval, 1.19 to 5.85), adjusting for age, sex, physical activity level, length of follow-up, and prevalent morbidity. Discussion: This is the first study, to our knowledge, to indicate that sarcopenic obesity is independently associated with and precedes the onset of IADL disability in the community-dwelling elderly. The etiology of sarcopenic obesity is unknown but may include a combination of decreases in anabolic signals and obesity-associated increases in catabolic signals in old age.

A Three-Component Model of Customer to Service Providers

Abstract: Although research into the determinants of service provider switching has grown in recent years, the focus has been predominantly on transactional, not relational, variables. In this research, the authors address the role of consumer commitment on consumers’ intentions to switch. Drawing from the organizational behavior literature, they build on previous service switching research by developing a switching model that includes a three-component conceptualization of customer commitment. Structural equation modeling is used to test the model based on data from a survey of 356 auto repair service customers. The authors’ results support the notion that customer commitment affects intentions to switch service providers and that the psychological states underlying that commitment may differ. As such, future marketing research should consider these different forms of commitment in understanding customer retention. The implications of this model for theory and practice are discussed.

Advanced Cardiac Life Support in Out-of-Hospital Cardiac Arrest

Abstract: background The Ontario Prehospital Advanced Life Support (OPALS) Study tested the incremental effect on the rate of survival after out-of-hospital cardiac arrest of adding a program of advanced life support to a program of rapid defibrillation. methods This multicenter, controlled clinical trial was conducted in 17 cities before and after advanced-life-support programs were instituted and enrolled 5638 patients who had had cardiac arrest outside the hospital. Of those patients, 1391 were enrolled during the rapid-defibrillation phase and 4247 during the subsequent advanced-life-support phase. Paramedics were trained in standard advanced life support, which includes endotracheal intubation and the administration of intravenous drugs. results From the rapid-defibrillation phase to the advanced-life-support phase, the rate of admission to a hospital increased significantly (10.9 percent vs. 14.6 percent, P<0.001), but the rate of survival to hospital discharge did not (5.0 percent vs. 5.1 percent, P=0.83). The multivariate odds ratio for survival after advanced life support was 1.1 (95 percent confidence interval, 0.8 to 1.5); after an arrest witnessed by a bystander, 4.4 (95 percent confidence interval, 3.1 to 6.4); after cardiopulmonary resuscitation administered by a bystander, 3.7 (95 percent confidence interval, 2.5 to 5.4); and after rapid defibrillation, 3.4 (95 percent confidence interval, 1.4 to 8.4). There was no improvement in the rate of survival with the use of advanced life support in any subgroup. conclusions The addition of advanced-life-support interventions did not improve the rate of survival after out-of-hospital cardiac arrest in a previously optimized emergency-medical-services system of rapid defibrillation. In order to save lives, health care planners should make cardiopulmonary resuscitation by citizens and rapid-defibrillation responses a priority for the resources of emergency-medical-services systems.

Toward Contextualized Theories of Trust: The Role of Trust in Global Virtual Teams

Abstract: Although trust has received much attention in many streams of information systems research, there has been little theorizing to explain how trust evokes sentiments and affects task performance in IT-enabled relationships. Many studies unquestionably assume that trust is intrinsically beneficial, and dismiss the possibility that the effects of trust may be dependent on the situation (or conditions) at present. This paper theoretically and empirically examines outcomes of an individual's trust in global virtual teams under differing situations (or conditions). In Study 1, we find that early in a team's existence, a member's trusting beliefs have a direct positive effect on his or her trust in the team and perceptions of team cohesiveness. Later on, however, a member's trust in his team operates as a moderator, indirectly affecting the relationships between team communication and perceptual outcomes. Study 2 similarly suggests that trust effects are sensitive to the particular situation or condition. Combined, the studies find that trust affects virtual teams differently in different situations. Future studies on trust will need to consider situational contingencies. This paper contributes to the literature on IT-enabled relationships by theorizing and empirically testing how trust affects attitudes and behaviors.

Measurement of the total active B-8 solar neutrino flux at the Sudbury Neutrino Observatory with enhanced neutral current sensitivity

Abstract: The Sudbury Neutrino Observatory has precisely determined the total active (nu(x)) B-8 solar neutrino flux without assumptions about the energy dependence of the nu(e) survival probability. The measurements were made with dissolved NaCl in heavy water to enhance the sensitivity and signature for neutral-current interactions. The flux is found to be 5.21+/-0.27(stat)+/-0.38(syst)x10(6) cm(-2) s(-1), in agreement with previous measurements and standard solar models. A global analysis of these and other solar and reactor neutrino results yields Deltam(2)=7.1(-0.6)(+1.2)x10(-5) eV(2) and theta= 32.5(-2.3)(+2.4) degrees. Maximal mixing is rejected at the equivalent of 5.4 standard deviations.

The Economic Costs Associated With Physical Inactivity and Obesity in Canada: An Update

Abstract: The purpose of this analytical review was to estimate the direct and indirect economic costs of physical inactivity and obesity in Canada in 2001. The relative risks of diseases associated with phy...

Tropical winter habitat limits reproductive success on the temperate breeding grounds in a migratory bird.

Abstract: Identifying the factors that control population dynamics in migratory animals has been constrained by our inability to track individuals throughout the annual cycle. Using stable carbon isotopes, w...

Exercise-Induced Reduction in Obesity and Insulin Resistance in Women: a Randomized Controlled Trial

Abstract: Objectives: To determine the effects of equivalent diet- or exercise-induced weight loss and exercise without weight loss on subcutaneous fat, visceral fat, and insulin sensitivity in obese women. Research Methods and Procedures: Fifty-four premenopausal women with abdominal obesity [waist circumference 110.1 ± 5.8 cm (mean ± SD)] (BMI 31.3 ± 2.0 kg/m2) were randomly assigned to one of four groups: diet weight loss (n = 15), exercise weight loss (n = 17), exercise without weight loss (n = 12), and a weight-stable control group (n = 10). All groups underwent a 14-week intervention. Results: Body weight decreased by ∼6.5% within both weight loss groups and was unchanged in the exercise without weight loss and control groups. In comparison with controls, cardiorespiratory fitness improved within the exercise groups only (p 0.05). Visceral fat decreased within all treatment groups (p < 0.008), and these changes were not different from each other. In comparison with the control group, insulin sensitivity improved within the exercise weight loss group alone (p < 0.001). Discussion: Daily exercise without caloric restriction was associated with substantial reductions in total fat, abdominal fat, visceral fat, and insulin resistance in women. Exercise without weight loss was also associated with a substantial reduction in total and abdominal obesity.

Morphological awareness: Just "more phonological"? The roles of morphological and phonological awareness in reading development

Abstract: Given the morphophonemic nature of the English orthography, surprisingly few studies have examined the roles of morphological and phonological awareness in reading. This 4-year longitudinal study (Grades 2–5) compared these two factors in three aspects of reading development: pseudoword reading, reading comprehension, and single word reading. Morphological awareness contributed significantly to pseudoword reading and reading comprehension, after controlling prior measures of reading ability, verbal and nonverbal intelligence, and phonological awareness. This contribution was comparable to that of phonological awareness and remained 3 years after morphological awareness was assessed. In contrast, morphological awareness rarely contributed significantly to single word reading. We argue that these results provide evidence that morphological awareness has a wide-ranging role in reading development, one that extends beyond phonological awareness.

The Institutional Effects on Strategic Alliance Partner Selection in Transition Economies: China vs. Russia

Abstract: China and Russia represent major economies in transition from command economies, yet their paths to the market have differed greatly. Their divergent approaches have helped create distinct institutional environments. This study focuses on a particularly important strategic decision firms face-alliance partner selection. The study's results suggest that China's more stable and supportive institutional environment has helped Chinese firms take a longer-term view of alliance partner selection, focusing more on the potential partner's intangible assets along with technological and managerial capabilities. In contrast, the less stable Russian institutional environment has influenced Russian managers to focus more on the short term, selecting partners that provide access to financial capital and complementary capabilities so as to enhance their firms' ability to weather that nation's turbulent environment. This study contributes to knowledge about the influence of the institutional environment on alliance partner selection decisions for firms domiciled in transition (and emerging) economies.

Beyond Thermodynamic Acidity: A Perspective on the Complex‐Induced Proximity Effect (CIPE) in Deprotonation Reactions

Abstract: The concept of the complex-induced proximity effect (CIPE) in deprotonations is helpful in elucidating the mechanisms involved in carbanion chemistry and in planning organic syntheses. In this Review, the consequences of complexation of organolithium bases to functional groups of the substrates before the proton-transfer step are discussed. Experimental data from kinetic measurements and isotope-labeling experiments as well as the results of calculations in many cases point to a prelithiation complex as a reaction intermediate. Some examples from natural products synthesis illustrate how this concept can be used to obtain intermediates in a regio- or stereoselective manner. Of particular interest is the functionalization of positions that are remote from the coordination group.

Reward-related Reversal Learning after Surgical Excisions in Orbito-frontal or Dorsolateral Prefrontal Cortex in Humans

Abstract: Neurophysiological studies in primates and neuroimaging studies in humans suggest that the orbito-frontal cortex is involved in representing the reward value of stimuli and in the rapid learning and relearning of associations between visual stimuli and rewarding or punishing outcomes. In the present study, we tested patients with circumscribed surgical lesions in different regions of the frontal lobe on a new visual discrimination reversal test, which, in an fMRI study (O'Doherty, Kringelbach, Rolls, Hornak, & Andrews, 2001), produced bilateral orbito-frontal cortex activation in normal subjects. In this task, touching one of two simultaneously presented patterns produced reward or loss of imaginary money delivered on a probabilistic basis to minimize the usefulness of verbal strategies. A number of types of feedback were present on the screen. The main result was that the group of patients with bilateral orbito-frontal cortex lesions were severely impaired at the reversal task, in that they accumulated less money. These patients often failed to switch their choice of stimulus after a large loss and often did switch their choice although they had just received a reward. The investigation showed that bilateral lesions were required for this deficit, since patients with unilateral orbito-frontal cortex (or medial prefrontal cortex) lesions were not impaired in the probabilistic reversal task. The task ruled out a simple motor disinhibition as an explanation of the deficit in the bilateral orbito-frontal cortex patients, in that the patients were required to choose one of two stimuli on each trial. A comparison group of patients with dorsolateral prefrontal cortex lesions was in some cases able to do the task, and in other cases, was impaired. Posttest debriefing showed that all the dorsolateral prefrontal patients who were impaired at the task had failed to pay attention to the crucial feedback provided on the screen after each trial about the amount won or lost on each trial. In contrast, all dorsolateral patients who paid attention to this crucial feedback performed normally on the reversal task. Further, it was confirmed that the bilateral orbito-frontal cortex patients had also paid attention to this crucial feedback, but in contrast had still performed poorly at the task. The results thus show that the orbital prefrontal cortex is required bilaterally for monitoring changes in the reward value of stimuli and using this to guide behavior in the task; whereas the dorsolateral prefrontal cortex, if it produces deficits in the task, does so for reasons related to executive functions, such as the control of attention. Thus, the ability to determine which information is relevant when making a choice of pattern can be disrupted by a dorsolateral lesion on either side, whereas the ability to use this information to guide behavior is not disrupted by a unilateral lesion in either the left or the right orbito-frontal cortex, but is severely impaired by a bilateral lesion in this region. Because both abilities are important in many of the tasks and decisions that arise in the course of daily life, the present results are relevant to understanding the difficulties faced by patients after surgical excisions in different frontal brain regions.

Embodying emotion sensing space: introducing emotional geographies

Abstract: Recent years have witnessed a welling‐up of emotion within geography, a surge of interest reminiscent of the fascination and exploration of embodiment that characterized much social and cultural ge...

2010 International consensus algorithm for the diagnosis, therapy and management of hereditary angioedema

Abstract: C1 inhibitor deficiency (hereditary angioedema [HAE]) is a rare disorder for which there is a lack of consensus concerning diagnosis, therapy, and management, particularly in Canada. European initiatives have driven the approach to managing HAE with 3 C1-INH Deficiency Workshops held every 2 years in Hungary starting in 1999, with the third Workshop having recently been held in May 2003. The European Contact Board has established a European HAE Registry that will hopefully advance our knowledge of this disorder. The Canadian Hereditary Angioedema Society/Societe d'Angioedeme Hereditaire du Canada organized a Canadian International Consensus Conference held in Toronto, Ontario, Canada, on October 24 to 26, 2003, to foster consensus between major European and North American HAE treatment centers. Papers were presented by investigators from Europe and North America, and this consensus algorithm approach was discussed. There is a paucity of double-blind placebo-controlled trials in the treatment of HAE, making levels of evidence to support the algorithm less than optimal. Enclosed is the consensus algorithm approach recommended for the diagnosis, therapy, and management of HAE and agreed to by the authors of this article. This document is only a consensus algorithm approach and requires validation. As such, participants agreed to make this a living 2003 algorithm (ie, a work in progress) and agreed to review its content at future international HAE meetings. The consensus, however, has strength in that it was arrived at by the meeting of patient-care providers along with patient group representatives and individual patients reviewing information available to date and reaching agreement on how to approach the diagnosis, therapy, and management of HAE circa 2003. Hopefully evidence to support approaches to the management of HAE will approach the level of meta-analysis of randomized controlled trials in the near future.