Showing papers by "Queen's University published in 2000"
TL;DR: In this paper, the authors describe the steps involved in VBM, with particular emphasis on segmenting gray matter from MR images with non-uniformity artifact and provide evaluations of the assumptions that underpin the method, including the accuracy of the segmentation and the assumptions made about the statistical distribution of the data.
8,049 citations
TL;DR: It is indicated that men have more SM than women and that these gender differences are greater in the upper body.
Abstract: We employed a whole body magnetic resonance imaging protocol to examine the influence of age, gender, body weight, and height on skeletal muscle (SM) mass and distribution in a large and heterogene...
2,361 citations
TL;DR: A randomized, controlled trial to determine the independent effect of diet-induced or exercise-induced weight loss on obesity and insulin resistance in moderately obese men found that exercise had no independent effect on insulin sensitivity.
Abstract: Background The independent effects of diet- or exercise-induced weight loss on the reduction of obesity and related comorbid conditions are not known. The effects of exercise without weight loss on fat distribution and other risk factors are also unclear. Objective To determine the effects of equivalent diet- or exercise-induced weight loss and exercise without weight loss on subcutaneous fat, visceral fat skeletal muscle mass, and insulin sensitivity in obese men. Design Randomized, controlled trial. Setting University research center. Participants 52 obese men (mean body mass index [+/-SD], 31.3 +/- 2.0 kg/m2) with a mean waist circumference of 110.1 +/- 5.8 cm. Intervention Participants were randomly assigned to one of four study groups (diet-induced weight loss, exercise-induced weight loss, exercise without weight loss, and control) and were observed for 3 months. Measurements Change in total, subcutaneous, and visceral fat; skeletal muscle mass; cardiovascular fitness; glucose tolerance and insulin sensitivity. Results Body weight decreased by 7.5 kg (8%) in both weight loss groups and did not change in the exercise without weight loss and control groups. Compared with controls, cardiovascular fitness (peak oxygen uptake) in the exercise groups improved by approximately 16% (P 0.2). However, these values were significantly greater than those in the control and exercise without weight loss groups (P Conclusions Weight loss induced by increased daily physical activity without caloric restriction substantially reduces obesity (particularly abdominal obesity) and insulin resistance in men. Exercise without weight loss reduces abdominal fat and prevents further weight gain.
1,473 citations
TL;DR: The results suggest that the BIA equation provides valid estimates of SM mass in healthy adults varying in age and adiposity.
Abstract: The purpose of this study was to develop and cross-validate predictive equations for estimating skeletal muscle (SM) mass using bioelectrical impedance analysis (BIA). Whole body SM mass, determine...
1,174 citations
TL;DR: The full hemodynamic model is presented, how its associated Volterra kernels can be derived, and the model's validity in relation to empirical nonlinear characterizations of evoked responses in fMRI and other neurophysiological constraints are addressed.
1,115 citations
TL;DR: There is strong and confirmatory evidence from two large randomized phase III trials to support paclitaxel-cisplatin as the new standard regimen for treatment of patients with advanced ovarian cancer.
Abstract: BACKGROUND: A randomized trial conducted by the Gynecologic Oncology Group (GOG, study #111) in the United States showed a better outcome for patients with advanced ovarian cancer on the paclitaxel-cisplatin regimen than for those on a standard cyclophosphamide-cisplatin regimen. Before considering the paclitaxel-cisplatin regimen as the new "standard," a group of European and Canadian investigators planned a confirmatory phase III trial. METHODS: This intergroup trial recruited 680 patients with broader selection criteria than the GOG #111 study and administered paclitaxel as a 3-hour instead of a 24-hour infusion; progression-free survival was the primary end point. Patient survival was analyzed by use of the Kaplan-Meier technique. Treatment effects on patient survival were estimated by Cox proportional hazards regression models. All statistical tests were two-sided. RESULTS: The overall clinical response rate was 59% in the paclitaxel group and 45% in the cyclophosphamide group; the complete clinical remission rates were 41% and 27%, respectively; both differences were statistically significant (P =.01 for both). At a median follow-up of 38.5 months and despite a high rate of crossover (48%) from the cyclophosphamide arm to the paclitaxel arm at first detection of progression of disease, a longer progression-free survival (log-rank P =.0005; median of 15.5 months versus 11.5 months) and a longer overall survival (log-rank P =. 0016; median of 35.6 months versus 25.8 months) were seen in the paclitaxel regimen compared with the cyclophosphamide regimen. CONCLUSIONS: There is strong and confirmatory evidence from two large randomized phase III trials to support paclitaxel-cisplatin as the new standard regimen for treatment of patients with advanced ovarian cancer.
980 citations
TL;DR: Genome-wide transcript profiling was used to monitor signal transduction during yeast pheromone response and global transcript analysis reflects biological responses associated with the activation and perturbation of signalTransduction pathways.
Abstract: Genome-wide transcript profiling was used to monitor signal transduction during yeast pheromone response. Genetic manipulations allowed analysis of changes in gene expression underlying pheromone signaling, cell cycle control, and polarized morphogenesis. A two-dimensional hierarchical clustered matrix, covering 383 of the most highly regulated genes, was constructed from 46 diverse experimental conditions. Diagnostic subsets of coexpressed genes reflected signaling activity, cross talk, and overlap of multiple mitogen-activated protein kinase (MAPK) pathways. Analysis of the profiles specified by two different MAPKs-Fus3p and Kss1p-revealed functional overlap of the filamentous growth and mating responses. Global transcript analysis reflects biological responses associated with the activation and perturbation of signal transduction pathways.
916 citations
Book•
04 Jun 2000
TL;DR: The results of these studies provide the basis for a revision of the CCC theory that specifies more clearly the circumstances in which children will have difficulty using rules at various levels of complexity, provides a more detailed account of how to determine the complexity of rules required in a task, takes account of both the activation and inhibition of rules as a function of experience, and highlights the importance of taking intentionality seriously in the study of executive function.
Abstract: According to the Cognitive Complexity and Control (CCC) theory, the development of executive function can be understood in terms of age-related increases in the maximum complexity of the rules children can formulate and use when solving problems. This Monograph describes four studies (9 experiments) designed to test hypotheses derived from the CCC theory and from alternative theoretical perspectives on the development of executive function (memory accounts, inhibition accounts, and redescription accounts). Each study employed a version of the Dimensional Change Card Sort (DCCS), in which children are required first to sort cards by one pair of rules (e.g., color rules: "If red then here, if blue then there"), and then sort the same cards by another, incompatible pair of rules (e.g., shape rules). Study 1 found that although most 3- to 4-year-olds failed the standard version of this task (i.e., they perseverated on the preswitch rules during the postswitch phase), they usually performed well when they were required to use four rules (including bidimensional rules) and those rules were not in conflict (i.e., they did not require children to respond in two different ways to the same test card). These findings indicate that children's perseveration cannot be attributed in a straightforward fashion to limitations in children's memory capacity. Study 2 examined the circumstances in which children can use conflicting rules. Three experiments demonstrated effects of rule dimensionality (uni- vs. bidimensional rules) but no effects of stimulus characteristics (1 vs. 2 test cards; spatially integrated vs. separated stimuli). Taken together, these studies suggest that conflict among rules is a key determinant of difficulty, but that conflict interacts with dimensionality. Study 3 examined what types of conflict pose problems for 3- to 4-year-olds by comparing performance on standard, Partial Change, and Total Change versions of the DCCS. Results revealed effects of conflict at the level of specific rules (e.g., "If red, then there"), rather than specific stimulus configurations or dimensions per se, indicating that activation of the preswitch rules persists into the postswitch phase. Study 4 examined whether negative priming also contributes to difficulty on the DCCS. Two experiments suggested that the active selection of preswitch rules against a competing alternative results in the lasting suppression of the alternative. Taken together, the results of these studies provide the basis for a revision of the CCC theory (CCC-r) that specifies more clearly the circumstances in which children will have difficulty using rules at various levels of complexity, provides a more detailed account of how to determine the complexity of rules required in a task, takes account of both the activation and inhibition of rules as a function of experience, and highlights the importance of taking intentionality seriously in the study of executive function.
851 citations
TL;DR: The performances of several signal-to noise ratio (SNR) estimation techniques reported in the literature are compared to identify the "best" estimator and some known estimator structures are modified to perform better on the channel of interest.
Abstract: The performances of several signal-to noise ratio (SNR) estimation techniques reported in the literature are compared to identify the "best" estimator. The SNR estimators are investigated by the computer simulation of baseband binary phase-shift keying (PSK) signals in real additive white Gaussian noise (AWGN) and baseband 8-PSK signals in complex AWGN. The mean square error is used as a measure of performance. In addition to comparing the relative performances, the absolute levels of performance are also established; the simulated performances are compared to a published Cramer-Rao bound (CRB) for real AWGN and a CRB for complex AWGN that is derived here. Some known estimator structures are modified to perform better on the channel of interest. Estimator structures for both real and complex channels are examined.
848 citations
TL;DR: It is concluded that the attenuation of skeletal muscle in vivo determined by CT is related to its lipid content and that this noninvasive method may provide additional information regarding the association between muscle composition and muscle function.
Abstract: The purpose of this investigation was to validate that in vivo measurement of skeletal muscle attenuation (MA) with computed tomography (CT) is associated with muscle lipid content. Single-slice CT...
744 citations
Journal Article•
TL;DR: Canadian men scored substantially higher than women on all 8 domains and the 2 summary component scales of the SF-36 and scored higher than their UK counterparts on 4 domains, although many of the differences are not large.
Abstract: Background: The Medical Outcomes Study 36-item Short Form (SF-36) is a widely used measure of health-related quality of life. Normative data are the key to determining whether a group or an individual scores above or below the average for their country, age or sex. Published norms for the SF-36 exist for other countries but have not been previously published for Canada. Methods: The Canadian Multicentre Osteoporosis Study is a prospective cohort study involving 9423 randomly selected Canadian men and women aged 25 years or more living in the community. The sample was drawn within a 50-km radius of 9 Canadian cities, and the information collected included the SF-36 as a measure of health-related quality of life. This provided a unique opportunity to develop age- and sex-adjusted normative data for the Canadian population. Results: Canadian men scored substantially higher than women on all 8 domains and the 2 summary component scales of the SF-36. Canadians scored higher than their US counterparts on all SF-36 domains and both summary component scales and scored higher than their UK counterparts on 4 domains, although many of the differences are not large. Interpretation: The differences in the SF-36 scores between age groups, sexes and countries confirm that these Canadian norms are necessary for comparative purposes. The data will be useful for assessing the health status of the general population and of patient populations, and the effect of interventions on health-related quality of life.
TL;DR: It was found that task characteristics, perceived information usefulness and the user's computer comfort were most strongly associated with the person's use of collaborative media, and views of information ownership and propensity to share were significantly related to use.
Abstract: This article reports an exploratory investigation of individual perceptions of factors that underlie the use of collaborative electronic media (electronic mail, World Wide Web, list serves, and other collaborative systems) for sharing information in a large state university in Australia. The model builds on the Constant et al.'s theory of information sharing. We propose that perceptions of information culture, attitudes regarding information ownership and propensity to share, as well as task and personal factors influence people's use of collaborative media. We found that task characteristics (task interdependence), perceived information usefulness and the user's computer comfort were most strongly associated with the person's use of collaborative media. Consistent with Constant et al.'s earlier findings, views of information ownership and propensity to share were significantly related to use. Interestingly, use of electronic media for sharing information and contacting people was weakly associated with a more structured, closed information culture. This implies that heavy users and sharers want more structured information flow in place, possibly due to their need to have reliable access to other individual's knowledge and information. Contrary to suggestions in the literature, a fully open, organic information culture may not always be most desirable. Implications for knowledge managers, practitioners and researchers are suggested.
TL;DR: The authors derived the asymptotic sampling distribution of various estimators frequently used to order distributions in terms of poverty, welfare, and inequality, including estimators of most of the poverty indices currently in use, as well as estimators used to infer stochastic dominance of any order.
Abstract: We derive the asymptotic sampling distribution of various estimators frequently used to order distributions in terms of poverty, welfare, and inequality. This includes estimators of most of the poverty indices currently in use, as well as estimators of the curves used to infer stochastic dominance of any order. These curves can be used to determine whether poverty, inequality, or social welfare is greater in one distribution than in another for general classes of indices and for ranges of possible poverty lines. We also derive the sampling distribution of the maximal poverty lines up to which we may confidently assert that poverty is greater in one distribution than in another. The sampling distribution of convenient dual estimators for the measurement of poverty is also established. The statistical results are established for deterministic or stochastic poverty lines as well as for paired or independent samples of incomes. Our results are briefly illustrated using data for four countries drawn from the Luxembourg Income Study data bases.
TL;DR: A decade-scale reconstruction of rainfall and drought in equatorial east Africa over the past 1,100 years is presented, based on lake-level and salinity fluctuations of Lake Naivasha inferred from three different palaeolimnological proxies: sediment stratigraphy and the species compositions of fossil diatom and midge assemblages.
Abstract: Knowledge of natural long-term rainfall variability is essential for water-resource and land-use management in sub-humid regions of the world In tropical Africa, data relevant to determining this variability are scarce because of the lack of long instrumental climate records and the limited potential of standard high-resolution proxy records such as tree rings and ice cores Here we present a decade-scale reconstruction of rainfall and drought in equatorial east Africa over the past 1,100 years, based on lake-level and salinity fluctuations of Lake Naivasha (Kenya) inferred from three different palaeolimnological proxies: sediment stratigraphy and the species compositions of fossil diatom and midge assemblages Our data indicate that, over the past millennium, equatorial east Africa has alternated between contrasting climate conditions, with significantly drier climate than today during the 'Medieval Warm Period' (approximately AD 1000-1270) and a relatively wet climate during the 'Little Ice Age' (approximately AD 1270-1850) which was interrupted by three prolonged dry episodes We also find strong chronological links between the reconstructed history of natural long-term rainfall variation and the pre-colonial cultural history of east Africa, highlighting the importance of a detailed knowledge of natural long-term rainfall fluctuations for sustainable socio-economic development
TL;DR: In this article, the authors investigated whether emotional intelligence is associated with the use of transformational leadership in 49 managers and found no multivariate effects emerged for transactional leadership (i.e., laissez faire or management by exception).
Abstract: Investigated whether emotional intelligence (EQ) is associated with the use of transformational leadership in 49 managers. Managers completed questionnaires assessing their own emotional intelligence and attributional style; their subordinates (n = 187) provided ratings of their transformational leadership. Controlling for attributional style, multivariate analyses of covariance showed that three aspects of transformational leadership (i.e. idealized influence, inspirational motivation, and individualized consideration) and constructive transactions differed according to level of emotional intelligence. In contrast, no multivariate effects emerged for transactional leadership (i.e. laissez faire or management‐by‐exception). Some suggestions for future research are offered.
TL;DR: A survey that assessed the form of the practice function for individual learners and learning conditions in paradigms that have shaped theories of skill acquisition concluded that the best candidate for the law of practice is the exponential or APEX function, not the generally accepted power function.
Abstract: The power function is treated as the law relating response time to practice trials. However, the evidence for a power law is flawed, because it is based on averaged data. We report a survey that assessed the form of the practice function for individual learners and learning conditions in paradigms that have shaped theories of skill acquisition. We fit power and exponential functions to 40 sets of data representing 7,910 learning series from 475 subjects in 24 experiments. The exponential function fit better than the power function in all the unaveraged data sets. Averaging produced a bias in favor of the power function. A new practice function based on the exponential, the APEX function, fit better than a power function with an extra, preexperimental practice parameter. Clearly, the best candidate for the law of practice is the exponential or APEX function, not the generally accepted power function. The theoretical implications are discussed.
TL;DR: In this article, the authors employed naturalistic observations to compare bullying and victimization in the playground and in the classroom, and found that there were more opportunities to observe aggression and receive and initiate aggression in the play area than the classroom.
Abstract: The present study employed naturalistic observations to compare bullying and victimization in the playground and in the classroom. The results indicated that there were more opportunities to observe aggression and receive and initiate aggression in the playground than in the classroom. The frequency of bullying was higher in the playground (4.5 episodes per hour) than in the classroom (2.4 episodes per hour). The nature of bullying reflected the constraints of the context (i.e. direct bullying was more prevalent in the playground and indirect bullying was more prevalent in the classroom). Being at the receiving end of aggression was more likely to occur in the playground as compared to the classroom. Nonaggressive children were more likely to bully in the playground, whereas aggressive children were more likely to bully in the classroom. There was no difference across context in the proportion of episodes of reinforcement with peers present or in the rate of peer and teacher intervention. The results high...
TL;DR: Evidence for set-related activity for saccadic eye movements in single neurons in the frontal eye field in monkeys trained on a task in which they either had to look toward a visual stimulus or away from the stimulus depending on a previous instruction is reported.
Abstract: Diversity in behavioral responses to sensory stimuli has been attributed to variations in preparatory set. Variability in oculomotor responses toward identical visual stimuli has been well documented, but the neuronal processes underlying this variability are poorly understood. Here, we report evidence for set-related activity for saccadic eye movements in single neurons in the frontal eye field (FEF) in monkeys trained on a task in which they either had to look toward a visual stimulus (pro-saccade) or away from the stimulus (anti-saccade) depending on a previous instruction. A portion of FEF neurons were identified as neurons projecting directly to the superior colliculus (SC) with antidromic activation techniques. Saccade-related neurons in the FEF had lower prestimulus and stimulus-related activity on anti-saccade trials compared with pro-saccade trials. The level of prestimulus activity correlated with saccadic reaction times, express saccade occurrence, and errors in the anti-saccade task. In addition, saccade-related activity in the FEF was higher for pro-saccades than for anti-saccades. These results demonstrate that the direct descending pathway from the FEF to the SC carries preparatory set-related activity for pro-saccades and anti-saccades. The results also provide insights into the neuronal basis of variations in saccadic reaction times and in the control of the prepotent response to glance to a flashed stimulus.
TL;DR: This paper considered conditions under which government bureaucracy can better obtain PSM motivated effort from employees than a standard profit maximizing firm and provided an efficiency rationale for low-powered incentives in both bureaucracies and other organizations producing social services.
TL;DR: It is suggested that an ‘encoding bottleneck’ for configural information may be responsible for the face-inversion effect in particular, and memory for faces in general.
Abstract: We report four experiments leading to conclusions that: (i) the face-inversion effect is mainly due to the deficits in processing of configural information from inverted faces; and (ii) this effect occurs primarily at the encoding stage of face processing, rather than at the storage stage. In experiment 1, participants discriminated upright faces differing primarily in configuration with 81% accuracy. Participants viewing the same faces presented upside down scored only 55%. In experiment 2, the corresponding discrimination rates for faces differing mainly in featural information were 91% (upright) and 90% (inverted). In experiments 3 and 4, the same faces were used in a memory paradigm. In experiment 3, a delayed matching-to-sample task was used, in which upright-face pairs differed either in configuration or features. Recognition rates were comparable to those for the corresponding upright faces in the discrimination tasks in experiments 1 and 2. However, there was no effect of delay (1 s, 5 s, or 10 s)...
TL;DR: The need for provision of better information and education to patients and possibly general practitioners regarding the safety, potency and appropriate use of topical corticosteroids is highlighted.
Abstract: Topical corticosteroids are widely prescribed by dermatologists caring for patients with atopic eczema. Patients' fears about using topical corticosteroids may have important implications for compliance with treatment. We carried out a questionnaire-based study of 200 dermatology outpatients with atopic eczema (age range 4 months-67.8 years) to assess the prevalence and source of topical corticosteroid phobia. We also questioned patients on their knowledge of the potencies of different topical corticosteroids. Overall, 72.5% of people worried about using topical corticosteroids on their own or their child's skin. Twenty-four per cent of people admitted to having been non-compliant with topical corticosteroid treatment because of these worries. The most frequent cause for concern was the perceived risk of skin thinning (34.5%). In addition, 9.5% of patients worried about systemic absorption leading to effects on growth and development. The most commonly used topical corticosteroid was hydrocortisone, yet 31% of patients who used this preparation classified it as either strong, very strong or did not know the potency. Only 62.5% of the 48 patients who had used both Dermovate® (Glaxo) and hydrocortisone in the past were able to correctly grade Dermovate® as being more potent than hydrocortisone. The most common source of patient information regarding topical corticosteroid safety was the general practitioner. Although skin thinning and systemic effects can develop very occasionally in people using topical corticosteroids, the concern expressed by people using them seems out of proportion in relation to the evidence of harm. This study highlights the need for provision of better information and education to patients and possibly general practitioners regarding the safety, potency and appropriate use of topical corticosteroids.
TL;DR: This pattern of hormonal change in men and other paternal mammals, and its absence in nonpaternal species, suggests that hormones may play a role in priming males to provide care for young.
TL;DR: The authors discuss racism out of place: Thoughts on Whiteness and an Antiracist Geography in the New Millennium, and present a collection of essays about racism in the new millennium.
Abstract: (2000). Racism out of Place: Thoughts on Whiteness and an Antiracist Geography in the New Millennium. Annals of the Association of American Geographers: Vol. 90, No. 2, pp. 392-403.
TL;DR: In this article, it is shown that a variable t σ that depends only on local values of the noninteracting kinetic energy density and of the charge density is highly indicative of details of atomic and molecular electronic structure, and reflects common chemical concepts such as atomic shells, molecular bonds and lone-pair regions.
Abstract: A recent concept for the simulation of delocalized exact exchange [A.D. Becke, J. Chem. Phys. 112 (2000) 4020] involves a variable t σ that depends only on local values of the non-interacting kinetic energy density and of the charge density. Here, we show that this variable is highly indicative of details of atomic and molecular electronic structure, and reflects common chemical concepts such as atomic shells, molecular bonds and lone-pair regions, in a clear and intuitive manner. Explanations for this behavior are given in terms of localized orbitals, as well as on kinematic grounds. On the example of a few simple chemical reactions, it is demonstrated that bond formation and bond breaking are reflected in this variable, allowing a simple “sectioning” of the potential energy surface in terms of species involved.
TL;DR: The findings suggest that distinct brain areas are involved in redirecting attention based upon sensory events (bottom-up, exogenous shifts) and based upon cognitive expectations (top-down, endogenous shifts).
TL;DR: It is demonstrated that in normal human subjects the excitability of the cortical projection to hand muscles can be altered in a manner determined by the peripheral stimulus applied.
Abstract: The aim of this study was to determine whether prolonged, repetitive mixed nerve stimulation (duty cycle 1 s, 500 ms on-500 ms off, 10 Hz) of the ulnar nerve leads to a change in excitability of primary motor cortex in normal human subjects. Motor-evoked potentials (MEPs) generated in three intrinsic hand muscles [abductor digiti minimi (ADM), first dorsal interosseous (FDI) and abductor pollicis brevis (APB)] by focal transcranial magnetic stimulation were recorded during complete relaxation before and after a period of prolonged repetitive ulnar nerve stimulation at the wrist. Transcranial magnetic stimuli were applied at seven scalp sites separated by 1 cm: the optimal scalp site for eliciting MEPs in the target muscle (FDI), three sites medial to the optimal site and three sites lateral to the optimal stimulation site. The area of the MEPs evoked in the ulnar-(FDI, ADM) but not the median-innervated (APB) muscles was increased after prolonged ulnar nerve stimulation. Centre of gravity measures demonstrated that there was no significant difference in the distribution of cortical excitability after the peripheral stimulation. F-wave responses in the intrinsic hand muscles were not altered after prolonged ulnar nerve stimulation, suggesting that the changes in MEP areas were not the result of stimulus-induced increases in the excitability of spinal motoneurones. Control experiments employing transcranial electric stimulation provided no evidence for a spinal origin for the excitability changes. These results demonstrate that in normal human subjects the excitability of the cortical projection to hand muscles can be altered in a manner determined by the peripheral stimulus applied.
TL;DR: It is shown that: (i) Whitening strategies can result in profound bias and are therefore probably precluded in parametric fMRI data analyses and (ii) Band-pass filtering, and implicitly smoothing, has an important role in protecting against inferential bias.
TL;DR: In this article, a prospective cohort study of U.S. thyroid carcinoma cases treated in 1996 was conducted and the most frequently used diagnostic modalities were fine needle aspiration of the thyroid gland (53%), thyroid lymph node (7%), thyroid nuclear scan (39%), and ultrasound (38%).
Abstract: BACKGROUND
The American College of Surgeons Commission on Cancer (CoC) has conducted national Patient Care Evaluation (PCE) studies since 1976.
METHODS
Over 1500 hospitals with CoC-approved cancer programs were invited to participate in this prospective cohort study of U.S. thyroid carcinoma cases treated in 1996. Follow-up will be conducted through the National Cancer Data Base.
RESULTS
Of the 5584 cases of thyroid carcinoma, 81% were papillary, 10% follicular, 3.6% Hurthle cell, 0.5% familial medullary, 2.7% sporadic medullary, and 1.7% undifferentiated/anaplastic. Demographics and suspected risk factors were analyzed. Fine-needle aspiration of the thyroid gland (53%) or a neck lymph node (7%), thyroid nuclear scan (39%), and ultrasound (38%) constituted the most frequently utilized diagnostic modalities. The vast majority of patients with differentiated thyroid carcinoma presented with American Joint Committee on Cancer Stage I and II disease and relatively small tumors. For all histologies, near-total or total thyroidectomy constituted the dominant surgical treatment. No lymph nodes were examined in a substantial proportion of cases. Residual tumor after the surgical event could be documented in 11% of cases, hypocalcemia in 10% of cases, and recurrent laryngeal nerve injury in 1.3% of cases. Complications were most frequently associated with total thyroidectomy combined with lymph node dissection. Thirty-day mortality was 0.3%; when undifferentiated/anaplastic cancer cases were eliminated, it decreased to 0.2%. Adjuvant treatment, probably underreported in this study, consisted of hormonal suppression (50% overall) and radioiodine (50% overall).
CONCLUSIONS
In addition to offering information concerning risk factors and symptoms, the current PCE study compliments the survival information from previous NCDB reports and offers a surveillance snapshot of current management of thyroid carcinoma in the U.S. Identified opportunities for improvement of care include 1) more frequent use of fine-needle aspiration cytology in making a diagnosis; 2) more frequent use of laryngoscopy in evaluating patients preoperatively, especially those with voice change; and 3) improved lymph node resection and analysis to improve staging and, in some situations, outcomes. [See commentary on pages 1–4, this issue and communication on pages 192–201, this issue.] Cancer 2000;89:202–17. © 2000 American Cancer Society.
TL;DR: In this paper, a simple pretest procedure for choosing the number of bootstrap samples so as to minimize experimental randomness is proposed, which has been shown to work well in practice.
Abstract: In practice, bootstrap tests must use a finite number of bootstrap samples. This means that the outcome of the test will depend on the sequence of random numbers used to generate the bootstrap samples, and it necessarily results in some loss of power. We examine the extent of this power loss and propose a simple pretest procedure for choosing the number of bootstrap samples so as to minimize experimental randomness. Simulation experiments suggest that this procedure will work very well in practice.
TL;DR: Risk is dose dependent and is lower with ibuprofen at low doses than with other NSAIDs, and it is unlikely that Helicobacter pylori increases the risk, and under some circumstances it may be protective.