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This investigation recruited 24 participants from both the Canadian Armed Forces (CAF) and civilian populations to complete 4 separate trials at 'best effort' of each of the 4 components in the CAF Physical Employment Standard named the FORCE Evaluation: Fitness for Operational Requirements of CAF Employment. Analyses were performed to examine the level of variability and reliability within each component. The results demonstrate that candidates should be provided with at least 1 retest if they have recently completed at least 2 previous best effort attempts as per the protocol. In addition, the minimal detectable difference is given for each of the 4 components in seconds which identifies the threshold for subsequent action, either retest or remedial training, for those unable to meet the minimum standard. These results will educate the delivery of this employment standard, function as a method of accommodation, in addition to providing direction for physical training programs. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The purpose of this study was to evaluate the accuracy of 2 newly developed physical activity questionnaires: the Canadian Society for Exercise Physiology (CSEP) Physical Activity and Sedentary Behaviour Questionnaire (PASB-Q) and a newly modified Leisure-Time Physical Activity Questionnaire (mLTPA-Q). These questionnaires were compared with objective measurements of physical activity and fitness (accelerometry and physiological assessments) in 35 adults, before and after a week of daily living activity. Objectively measured moderate- to vigorous-intensity aerobic physical activity (MVPA) was moderately correlated with the PASB-Q's physical activity vital sign (PAVS) ( r = 0.50, p = 0.004) and the mLTPA-Q ( r = 0.56, p = 0.001). Bland−Altman plots suggest minimal bias from self-reported to objective measures of MVPA. The ability of PAVS to accurately distinguish who does and does not achieve Canadian physical activity guidelines was 83% and 60%, respectively, compared with 82% and 73% of the mLTPA-Q. Self-reported sedentary time was greatly underestimated in the PASB-Q compared with the objective measure (6.4 ± 3.5 vs 12.2 ± 1.2 h/day). The results of this study suggest the PASB-Q and mLTPA-Q are valid and reliable measures of adult physical activity and provide reasonable indication of those individuals who meet physical activity guidelines. Future questionnaire development should take into account the underestimation of time spent engaging in sedentary activities. [ABSTRACT FROM AUTHOR]

This paper presents a framework for the optimal design of a storm sewer network in flat areas where there is insufficient energy from gravity for runoff drainage. A reliability index based on nodal partial flooding is introduced as a performance criterion and utilizes the intrinsic storage capacity of the sewer network. The Storm Water Management Model is used for hydraulic simulation of the sewer system. This model is coupled with an adaptive genetic algorithm to obtain the least-cost design of the network. The model offers numerous design alternatives with various levels of reliability. The model was successfully applied to the Kianpars storm sewer network, a flat district of the city of Ahvaz in Iran. The proposed model is useful for managing the budget and technical limitations of sewer system design in flat areas as well as efficiently deriving an optimum trade-off between design cost and reliability. [ABSTRACT FROM AUTHOR]

While the scope of the term physical employment standards is wide, the principal focus of this paper is on standards related to physiological evaluation of readiness for work. Common applications of such employment standards for work are in public safety and emergency response occupations (e.g., police, firefighting, military), and there is an ever-present need to maximize the scientific quality of this research. Historically, most of these occupations are male-dominated, which leads to potential sex bias during physical demands analysis and determining performance thresholds. It is often assumed that older workers advance to positions with lower physical demand. However, this is not always true, which raises concerns about the long-term maintenance of physiological readiness. Traditionally, little attention has been paid to the inevitable margin of uncertainty that exists around cut-scores. Establishing confidence intervals around the cut-score can reduce for this uncertainty. It may also be necessary to consider the effects of practise and biological variability on test scores. Most tests of readiness for work are conducted under near perfect conditions, while many emergency responses take place under far more demanding and unpredictable conditions. The potential impact of protective clothing, respiratory protection, load carriage, environmental conditions, nutrition, fatigue, sensory deprivation, and stress should also be considered when evaluating readiness for work. In this paper, we seek to establish uniformity in terminology in this field, identify key areas of concern, provide recommendations to improve both scientific and professional practice, and identify priorities for future research. [ABSTRACT FROM AUTHOR]

Indirect calorimetry is a common and noninvasive method to estimate rate of fat oxidation (FatOx) during exercise, and test-retest reliability should be considered when interpreting results. Diet also has an impact on FatOx. The aim of the present study was to investigate day to day variations in FatOx during moderate exercise given the same diet and 2 different isoenergetic diets. Nine healthy, moderately-trained females participated in the study. They performed 1 maximal oxygen uptake test and 4 FatOx tests. Habitual diets were recorded and repeated to assess day to day variability in FatOx. FatOx was also measured after 1 day of fat-rich (26.8% carbohydrates (CHO), 23.2% protein, 47.1% fat) and 1 day of CHO-rich diet (62.6% CHO, 20.1% protein, 12.4% fat). The reliability test revealed no differences in FatOx, respiratory exchange ratio (RER), oxygen uptake, carbon dioxide production, heart rate, blood lactate concentration, or blood glucose between the 2 habitual diet days. FatOx decreased after the CHO-rich diet compared with the habitual day 2 (from 0.42 ± 0.15 to 0.29 ± 0.13 g·min−1, p < 0.05). No difference was found in FatOx between fat-rich diet and the 2 habitual diet days. FatOx was 31% lower (from 0.42 ± 0.14 to 0.29 ± 0.13 g·min−1, p < 0.01) after the CHO-rich diet compared with the fat-rich diet. Using RER data to measure FatOx is a reliable method as long as the diet is strictly controlled. However, even a 1-day change in macronutrient composition will likely affect the FatOx results. [ABSTRACT FROM AUTHOR]

Experimental results of the truck-induced wind gust pressure were used as the basis to develop the equivalent static truck-induced wind pressure for fatigue design in the American Association of State Highway and Transportation Officials (AASHTO). The development does not explicitly quantify the stress range distribution, nor does the development discuss the implied reliability. No recommendation is given to consider truck-induced pressure for fatigue design in the Canadian Highway Bridge Design Code (CHBDC). This study quantifies the stress range due to truck traffic, and calibrates the equivalent static truck-induced wind pressure for fatigue design of overhead steel sign support structures. The reliability-based calibration is focused on the CHBDC. For the vertical excitations, the calibrated pressure is less than 50% of that suggested in the AASHTO. For the horizontal excitations, the calibrated pressure can be greater or smaller than that for the site-dependent natural wind gusts. Therefore, the truck-induced horizontal wind pressure could govern the fatigue design for some sites. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Designing stiffened panels requires evaluating reliability of these structures with regards to the collapse limit state as it could be affected by the presence of general localized defects. Considering the case of a small square depression located on the surface panel, the buckling strength under in-plane uniform axial compression was evaluated through nonlinear finite element modelling. Artificial neural networks were introduced for representing the collapse load as function of the key intervening design variables. A full factorial design of experiment table constructed on these variables provided samples for the training phase, and complementary samples were used to test and validate the obtained models. Separating the various sources contributing to variability of the buckling strength, Monte Carlo method was used to evaluate the probability of failure as function of the applied compression load acting on the stiffened panel system. It was found that localized defects have a drastic effect on the reliability probability. For the considered geometric parameters and boundary conditions, the localized defect present on the central segment of the stiffened panel was recognized to be the most severe one. [ABSTRACT FROM AUTHOR]

Nutrition is vital for optimal growth and development of young children. Nutrition risk screening can facilitate early intervention when followed by nutritional assessment and treatment. NutriSTEP ( Nutrition Screening Tool for Every Preschooler) is a valid and reliable nutrition risk screening questionnaire for preschoolers (aged 3-5 years). A need was identified for a similar questionnaire for toddlers (aged 18-35 months). The purpose was to develop a reliable and valid Toddler NutriSTEP. Toddler NutriSTEP was developed in 4 phases. Content and face validity were determined with a literature review, parent focus groups ( n = 6; 48 participants), and experts ( n = 13) (phase A). A draft questionnaire was refined with key intercept interviews of 107 parents/caregivers (phase B). Test-retest reliability (phase C), based on intra-class correlations (ICC), Kappa (κ) statistics, and Wilcoxon tests was assessed with 133 parents/caregivers. Criterion validity (phase D) was assessed using Receiver Operating Characteristic (ROC) curves by comparing scores on the Toddler NutriSTEP to a comprehensive nutritional assessment of 200 toddlers with a registered dietitian (RD). The Toddler NutriSTEP was reliable between 2 administrations (ICC = 0.951, F = 20.53, p < 0.001); most questions had moderate (κ ≥ 0.6) or excellent (κ ≥ 0.8) agreement. Scores on the RD nutrition risk rating and the Toddler NutriSTEP were correlated ( r = 0.67, p < 0.000). The area under the ROC curve for moderate and high RD risk ratings were 84.6% and 82.7%, respectively. Cut-points of ≥21 (sensitivity 86%; specificity 61%) (moderate risk) and ≥26 (sensitivity 95%; specificity 63%) (high risk) were determined. The Toddler NutriSTEP questionnaire is both reliable and valid for screening for nutritional risk in toddlers. [ABSTRACT FROM AUTHOR]

The Canadian Forces Firefighter Physical Fitness Maintenance Evaluation (FF PFME) requires firefighters in full fire-protective ensemble, including self-contained breathing apparatus, to correctly complete 10 work-related tasks on a measured and calibrated course. Fitness for duty is inferred from completion time of the course. We hypothesized that completion time may be dependent on pacing strategy and day-to-day fluctuations in biological function. To examine variability in performance, 20 females and 31 males (mean ± SD; age, 27.6 ± 10.5 years; height, 176.7 ± 8.3 cm; mass, 77.3 ± 13.4 kg) were familiarized with the FF PFME and then completed the test on 6 separate days. Pre-test behaviours (e.g., sleep, diet) and test conditions (e.g., calibration, time of day) were consistent. Repeated-measures ANOVA revealed a significant decrease in completion time between tests 1 and 6 (18.7%) and between all sequential pairs (e.g., tests 1 and 2). There was also a small but significant increase in the fraction of total test time for task completion and a corresponding decrease in the time to transition between tasks. The performance improvements cannot be explained by differences in effort (heart rate and perceived exertion). Coefficient of variation for tests 1, 2, and 3 was 7% and for tests 4, 5, and 6 was 2.6%. The results indicate the importance of practice on performance and the potential for false-positive or false-negative decision errors if biological variability is not taken into account. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The PLAYself is a commonly utilized tool to assess physical literacy in child and adolescent populations. Currently, there are no measurement tools designed to examine physical literacy among adults. The purpose of this cross-sectional study was to examine the psychometric properties of PLAYself subsections in a sample of young adults. Two hundred forty-five young adults (ages 18-25) from the United States completed the PLAYself questionnaire. Multiple principal component analyses using promax rotation were utilized to assess the current factor structure of the PLAYself subsections. Each subsection was analyzed independently to explore individual summary components. PLAYself subsections were assessed for reliability using Cronbach's  α , inter-item correlations, and item-total correlations. A multi-factor structure was identified for each PLAYself subsection. A 2-factor structure was identified for the Environment subsection accounting for 55.2% of the variance. A 2-factor structure was identified for the Physical Literacy Self-Description subsection accounting for 57.1% of the variance. A 3-factor structure was identified for the Relative Ranking of Literacies subsection accounting for 70.3% of the variance. The Environment, Physical Literacy Self-Description, and Relative Ranking of Literacies subsections demonstrated poor ( α  = 0.577), good ( α  = 0.89), and acceptable ( α  = 0.79) internal consistencies, respectively. The Physical Literacy Self-Description subsection demonstrated the best psychometric properties in our sample, and thus may be an appropriate tool to assess physical literacy in a young adult population until additional measurement tools are developed.

In this study the concepts of reliability are used to derive blast load factors. First, some objective criteria are proposed for the proper interpretation of pressure data gathered in arena tests. These criteria are applied to the pressure-time histories recorded during field tests involving live explosive detonated in contact with the ground. Three major shock wavefront parameters, including peak pressure, impulse, and positive phase duration are calculated. Next, statistical analysis is performed on these metrics to estimate their probability density functions and goodness-of-fit tests are carried out to gauge the appropriateness of each estimate. Using the best-fitting distribution for each wavefront metric, load factors are derived on the basis of two approaches. The first approach employs the percentiles of the three load metrics, each estimated using the pertinent probability distribution. The second approach uses concepts of reliability and presents load factors for low, medium, and high level of protection. The two sets of load factors are compared and the limitations of each approach are discussed. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Journal of Civil Engineering is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A reliability-based structural evaluation for the Red Deer River Bridge was conducted based on collected strain gauge data and compared to theoretical results using the conventional methods outlined in CAN/CSA-S6-06. Live load capacities for flexure were calculated in accordance with both the load and resistance factor and mean load code-based methods, suggesting that the bridge is adequate for the proposed increased live load level. The structural evaluation based upon the results of the field measurements, though, indicated reliability indices for flexure that exceeded those calculated based on code methods for all but the one instrumented location; furthermore, anomalously high strain readings at this one apparently deficient location cast doubt on the measured result. The transverse distribution of live loads varied considerably along the instrumented span and indicated that the bridge diaphragms are not fully effective. Measured dynamic effects were lower than those prescribed by CAN/CSA-S6-06. [ABSTRACT FROM AUTHOR]

Proper bridge design is based on joint consideration of structural, hydraulic, and geotechnical conformities. An optimization-based methodology has been developed to obtain appropriate dimensions of a river bridge to meet these aspects. Structural and geotechnical design parts use a statistically-based artificial neural network (ANN) model. Therefore, relevant data were collected from many bridge projects and analyzed to form a matrix. Artificial neural network architectures are used in the objective function of the optimization problem, which is modeled using genetic algorithms (GA) with penalty functions. Bridge scouring reliability is performed using Monte-Carlo simulations. All the techniques are assembled in a software framework. Finally, an application is presented to assess the outputs of the software by focusing on the evaluations of hydraulic-structure interactions. [ABSTRACT FROM AUTHOR]

The determination of power using isokinetic testing has been shown to be highly reliable. However, isotonic and isokinetic testing involve specific mechanical constraints that likely necessitate different neuromuscular strategies. Therefore, the purpose here was to establish test-retest intrarater reliability (separated by 7 days) of loaded maximal shortening velocity and velocity-dependent power of the ankle dorsiflexors using the isotonic mode of the Biodex dynamometer ( i) at baseline and ( ii) throughout recovery following 150 high-intensity lengthening contractions. Intraclass correlation coefficients (ICC)2,1 with 95% CIs were used to determine relative reliability, whereas absolute reliability included typical error (TEM) and typical error expressed as a coefficient of variation (TEMCV). Twenty-four young men and women volunteered for the study. Maximal shortening velocity and power were determined with a fixed resistance set at 20% of maximal voluntary isometric contraction across 2 testing sessions separated by 7 days. ICCs were 0.93 and 0.98 for maximal shortening velocity and peak power, respectively. Following the lengthening contractions, ICCs indicated high reliability for maximal shortening velocity and peak power, 0.86 and 0.94, respectively, suggesting that a similar amount of fatigue was incurred on both days. Measures of absolute reliability for maximal shortening velocity and peak power also yielded high reliability. The isotonic mode is highly reliable when testing velocity-dependent power of the ankle dorsiflexors at baseline and following fatiguing lengthening contractions. The high reliability of this measure is encouraging and suggests that the isotonic mode can be used in various settings to track group changes before and after training and following fatigue and lengthening contractions. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Surface water rights in Texas are developed based on 'Prior Appropriation Doctrine'. The Texas Water Availability Model, a computer-based simulation model based on water rights priority order, has been used for computing the amount of water supply and determining the amount of water available for a newly requested water right for the past several years. This study compares the water rights priority and natural priority orders by applying it to the largest sixteen reservoirs in the Brazos River Basin, Texas. The water supply reliability, reservoir storage frequency, and stream flows are analyzed corresponding to each priority orders. The natural priority order increases water supply reliability for most reservoirs about 1 to 2% and mean reservoir storage volume located in the upper basin than water rights priority order. The stream flows based on water rights priority order are more regulated than natural priority order by 3 and 5%. The composite priority order is more effective than each priority order in increasing the water supply reliability. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

This work forms part of a general research effort into developing a methodology for reliability estimates of results obtained in numerical hydrodynamic computations. We consider the possibility of overtopping at the crest of a dyke of height h0 positioned on a river with several uncertain parameters, such as discharge, Manning coefficient, bathymetry, etc. The estimation model is based either on the first-order reliability method (FORM), on the multi-form method, or on the importance sampling methods and is coupled with algorithms for the resolution of an adjoint optimization problem. Numerical tests are carried out on flows over a channel with a bump and on a river. The results obtained with our algorithms are compared with those obtained with the commercial software Nessus® and with the Monte Carlo method. The proposed multi-form approach combined with a robust optimization algorithm provides reliable results within reasonable computation times. Ce travail fait partie d’un effort général de recherche pour le développement d’une méthode d’estimation de la fiabilité des résultats obtenus lors de calculs hydrodynamiques numériques. Nous avons considéré la possibilité de débordement à la crête d’une digue d’une hauteur de h0 placée dans une rivière comportant plusieurs paramètres incertains, tels que le débit, le coefficient de Manning, la bathymétrie, etc. Le modèle d’estimation est basé soit sur la méthode de fiabilité du premier ordre (FORM), la méthode « multi-FORM » ou les méthodes d’échantillonnage par importance, et elle est associée à des algorithmes afin de résoudre un problème adjoint d’optimisation. Des essais numériques ont été réalisés sur des débits dans un canal muni d’une bosse et dans une rivière. Les résultats obtenus avec nos algorithmes sont comparés à ceux obtenus par le logiciel commercial Nessus® et par la méthode de Monte Carlo. La méthode multiforme proposée, combinée à un algorithme d’optimisation robuste, fournit des résultats fiables en des temps de calcul raisonnables. [ABSTRACT FROM AUTHOR]

In this qualitative paper, a method for technical and operational hazard identification of a water treatment plant is described. Here, fault tree analysis is applied to a physicochemical ultrafiltration (UF) membrane train, with the objectives of developing a systematic approach for organizing and improving our understanding of the hazards at the treatment plant operational level that affect the risk of infection from the pathogen Cryptosporidium parvum. The approach was successful in identifying many technical and operational hazards. The fault tree shows that water treatment plant operation is a complex task where many factors must be taken into account. Regarding the removal of C. parvum oocysts, most initiating events relate to the filtration step in the UF system. In the future, quantification of the probability of fault events may help to prioritize interventions at the operational level. Cet article qualitatif décrit une méthode d’identification des risques techniques et opérationnels d’une usine de traitement des eaux. L’analyse par arbre des causes est utilisée pour un train de membranes d’ultrafiltration physicochimique avec, comme objectifs, le développement d’une approche systématique pour l’organisation et l’amélioration de notre compréhension des dangers au niveau opérationnel de l’usine de traitement qui affectent le risque d’infection par l’agent pathogène Cryptosporidium parvum. L’approche a réussi à identifier plusieurs dangers techniques et opérationnels. L’arbre des causes montre que le fonctionnement d’une usine de traitement des eaux est une tâche complexe dans laquelle il faut tenir compte de plusieurs facteurs. Quant à l’élimination des oocystes C. parvum, la plupart des événements déclencheurs ont trait à l’étape de filtration du système d’ultrafiltration. À l’avenir, la quantification de la probabilité des causes pourrait aider à déterminer la priorité des interventions opérationnelles. [ABSTRACT FROM AUTHOR]

As part of a study to develop load and resistance factor design (LRFD) codes for foundation structures in South Korea, resistance factors for the static bearing capacity of driven steel pipe piles were calibrated in the framework of the reliability theory. A database of 52 static load test results was compiled, and the data from these load test piles were sorted into two cases: a standard penetration test (SPT) N-value at pile tip (i) less than 50 and (ii) equal to or more than 50. Reliability analyses and resistance factor calibration for the two static bearing capacity analysis methods adopted in the Korean Design standards for foundation structures were performed using the first-order reliability method (FORM) and the Monte Carlo simulation (MCS). Reliability indices and resistance factors computed by the MCS are statistically identical to those computed by FORM. Target reliability indices were selected as 2.0 and 2.33 for the group pile case and 2.5 for the single pile case. The resistance factors recommended from this study are specific for the pile foundation design and construction practice and the subsurface conditions in South Korea. Des facteurs de résistance pour la capacité portante de pieux faits de tuyaux d’acier ont été calibrés dans le cadre de la théorie de fiabilité, ceci en tant que partie d’une étude sur le développement de codes de facteurs de chargement et de résistance pour des fondations de structures en Corée du Sud. Une base de donnée de 52 essais de chargement statique a été compilée, et les données de ces pieux d’essais ont été classés en deux catégories : essai de pénétration standard (SPT) N à la pointe du pieu (i) de moins de 50 et (ii) égal ou supérieur à 50. Les analyses de fiabilité et le calibrage des facteurs de résistance pour les deux méthodes d’analyse de la capacité portante adoptées par les normes Design standards for foundation structures de la Corée ont été effectuées à l’aide de la méthode de fiabilité de premier ordre (FORM) et la simulation Monte Carlo (MCS). Les indices de fiabilité et les facteurs de résistance obtenus avec la MCS sont statistiquement identiques à ceux obtenus par FORM. Les indices de fiabilité visés ont été choisis comme 2,0 et 2,33 pour le cas de groupement de pieux, et de 2,5 pour le cas de pieux uniques. Les facteurs de résistance recommandés suite à cette étude sont spécifiques à la conception et à la construction de pieux dans les conditions de la Corée du Sud. [ABSTRACT FROM AUTHOR]

An experimental and analytical research program was conducted with the objective of investigating the response of welded joints loaded under combined out-of-plane bending and shear. A database of test results, including 60 tests from the University of California in Davis, eight tests from an early research program at the University of Alberta in Edmonton, and 24 tests from Université Laval in Ste.-Foy, was used to evaluate several strength prediction models and the current North American design approaches. This work was complemented by a reliability analysis to assess the level of safety provided by these design approaches. It was determined that both the Canadian Institute of Steel Construction (CISC) and the American Institute of Steel Construction (AISC) approaches provide remarkably conservative predictions of the test results, especially for cases where the welded plate thickness is large. Although a modified version of an approach proposed by earlier investigators in 1972 and based on the method of instantaneous centre of rotation provides an accurate prediction of test results, a simpler strength calculation model that does not require an iterative approach is proposed as a substitute for the current design approaches. The proposed approach provides the desired level of safety for the design of welded joints loaded in shear and out-of-plane bending. [ABSTRACT FROM AUTHOR]

The development of highway standard design models involves various assumptions regarding design inputs and the road environment. This paper suggests an improvement to the treatment of uncertainty in design inputs by replacing the current deterministic approach with a reliability-based framework. Reliability theory deals with the propagation of quantified variability in design inputs throughout the design process. In such a framework, each design output corresponds to a theoretical probability of noncompliance to design requirements. These probabilities can be used to assess and compare the a priori safety level associated with various design scenarios. This paper proposes that such a priori safety level of standard design outputs should be consistent and close to a prespecified target level. A set of methods is proposed to determine a target value for design safety. A general framework for calibrating standard design models is presented. To demonstrate the concept, the paper presents an application of the calibration framework to the standard design model of crest vertical curves. Calibrated design charts are constructed to yield a consistent design safety level. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

There is a growing tendency to assess safety levels of existing dams and to design new dams using probabilistic approaches according to project characteristics and site-specific conditions. This study is a probabilistic assessment of the overtopping reliability of a dam, which will be designed for flood detention purpose, and will compute the benefits that can be gained as a result of the implementation of this dam. In a case study, a bivariate flood frequency analysis was carried out using a five-parameter bivariate gamma distribution. A family of joint return period curves relating the runoff peak discharges to the runoff volumes at the dam site was derived. A number of hydrographs were also obtained under a joint return period of 100 years to observe the variation of overtopping tendency. The maximum reservoir elevation and overtopping reliability were determined by performing a probabilistic reservoir routing based on Monte Carlo simulations. Il existe une tendance croissante à évaluer les niveaux de sécurité des barrages existants et de concevoir de nouveaux barrages en utilisant des approches probabilistes selon les caractéristiques du projet et les conditions de site spécifiques. Cette étude a produit une évaluation probabiliste de la fiabilité de débordement par-dessus un barrage, lequel sera conçu de manière à contenir les crues, et de calculer les avantages possibles grâce à l’implantation de ce barrage. Dans une étude de cas, une analyse bivariée de la fréquence des crues a été réalisée en utilisant une distribution gamma bivariée à cinq paramètres. Une gamme de courbes des périodicités conjointes reliant les débits d’écoulement de pointe aux volumes d’écoulement au site du barrage a été dérivée. Plusieurs hydrogrammes ont également été obtenus pour une périodicité conjointe de 100 ans afin d’observer la variation dans la tendance au débordement. L’élévation maximale du réservoir et la fiabilité de débordement ont été déterminées en réalisant un calcul probabiliste de la propagation des crues basé sur la méthode de Monte Carlo. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Efforts have been made in this paper to backcalculate the in situ elastic moduli of asphalt pavement from synthetically derived falling weight deflectometer (FWD) deflections at seven equidistant points. An artificial neural network (ANN) is used as a tool for backcalculation in this work. The ANN is observed to backcalculate layer moduli, both from normal as well as noisy deflection basins, with better accuracy compared with other software, namely, EVERCALC and ExPaS. EVERCALC is a backcalculation software downloaded from the Internet and ExPaS is a backcalculation algorithm developed in-house, based on a “search and expand” approach. Work have been extended further to develop ANN models that can predict a possible rigid layer at the bottom of the pavement and can directly predict the remaining life of the pavement without backcalculating the layer moduli. Finally, a reliability analysis is performed to quantify the performance of backcalculation using an ANN. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Probabilistic assessments of the ductility demand and reliability analysis were carried out for hysteretic bilinear single-degree-of-freedom (SDOF) systems. The assessment considered a set of strong ground motion records, and focused on evaluating the mean and coefficient of variation of the ductility demand for a given normalized yield strength. Results indicated that the ductility demand could be modeled as a Frechet (extreme value type II) variate. Based on the obtained results, empirical equations were provided to predict the mean ductility demand for hysteretic bilinear SDOF systems considering different natural vibration periods, damping ratios, and post-yield stiffness to initial stiffness ratios. Numerical results showed that the coefficient of variation of the ductility demand can go as high as one, depending on the characteristics of the structure. Also, a simple approach was given to estimate the probabilities of incipient damage and incipient collapse using the developed probabilistic characterization of the ductility demand. This approach, which could be suitable for design code calibration analysis, is illustrated numerically in this study. [ABSTRACT FROM AUTHOR]

The mean load method of the Canadian Highway Bridge Design Code is used to evaluate the shear and bending moment reliability of existing precast "type G" stringer bridges in Alberta that date from the late 1950s. The overall stringer population is categorized into distinct subpopulations using bridge-specific factors, including the degree of deterioration and approach span condition, which are readily identified during a brief field visit or from inspection reports. Critical sections to be investigated for reliability resisting shear forces or bending moments are determined. The reliability indices decrease if the reinforcement is corroded or the bridge approach is not smooth, and the reduction of the maximum axle loads permitted by legislation due to these factors is quantified. For bridge subpopulations where the actual reliability index is less than the target value for current legal axle loads, the critical axle load for moment is less than that for shear. Therefore, if flexural distress is not noted during inspection of such structures, they are likely adequate for the actual loading they are subjected to. [ABSTRACT FROM AUTHOR]

Statistical parameters for the load effects and resistances of precast "type G" stringer bridges erected in Alberta since the late 1950s are presented to assist practicing engineers assessing similar bridges using the mean load method. The load effect data include unit weight data for normal weight and two lightweight concretes; traffic volumes, gross vehicle weights, and single, tandem, and tridem axle weights observed on primary, secondary, and local roads; and dynamic load allowances for shear and bending moment on short span bridges. Extreme annual traffic loads are derived. The resistance data include compressive and tensile strengths of normal weight and two lightweight concretes and yield strengths for corroded and uncorroded reinforcing steel. Additional statistical parameters are presented to account for other readily discerned bridge-specific idealization factors that affect the reliability indices. Professional factors for flexural and shear resistance are derived using experimental data reported from past investigations of type G stringers by others. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A comparative study was undertaken of selected computational methods for predicting the strength determined from more than 500 physical tests of rectangular, tied structural concrete columns available in the literature. The study included 354 reinforced concrete and 150 composite steel–concrete columns. The computational methods compared were those of CSA A23.3-94 and Eurocode 2 for reinforced concrete and those of CSA A23.3-94 and Eurocode 4 for composite columns. The physical tests used for comparison were conducted on columns that were braced, pinned at both ends, subjected to short-term loads, and constructed using normal-density concrete with a compressive strength between approximately 17 and 57 MPa. Major variables included the concrete strength, the end eccentricity ratio, the slenderness ratio, the longitudinal reinforcing steel index for reinforced concrete or the structural steel index for composite columns, and the transverse reinforcement (tie/hoop) volumetric ratio. The study provided insights into the reliability of the computational methods examined. Recommendations for improving the CSA A23.3-94 procedure for the design of reinforced concrete and composite steel–concrete columns are also presented. [ABSTRACT FROM AUTHOR]

Despite the large database of test results for tension and shear block failure in gusset plates, the exact progression of the failure mechanism is not clear. Although current design equations predict the capacity of gusset plates fairly well, it is important for a design equation to not only predict the capacity reliably but also reflect the failure mode accurately. Recent experimental and numerical research has indicated that current design equations do not always predict the failure behaviour accurately. A finite element model was therefore developed to predict the sequence of events that leads to the tear-out of a block of material from a bolted gusset plate in tension. The model was developed to provide a useful tool for studying tension and shear block failure in gusset plates and other structural elements. This paper presents the development of the finite element model and procedure for prediction of tension and shear block failure in gusset plates. Making use of the finite element model, the database of test results is also expanded to include gusset plates with a larger number of transverse lines of bolts than what has been obtained experimentally. A reliability analysis is used to assess several design equations, including the equation adopted in CAN/CSA-S16-01 and a unified equation proposed recently for several types of bolted connections. From this work, a limit states design equation is proposed for gusset plates. [ABSTRACT FROM AUTHOR]

Horizontal curves on road are commonly analyzed under design speed point of view, where it is assumed that the maximum speed of a vehicle in a curve is the design speed. The empirical evidence has demonstrated that when the design speed is low, the operating speed tends to be higher. This happens because of an available remaining lateral (or transverse) friction for speeds over design speed. This condition is determined by a speed limit, obtained from the demand and supply equilibrium of friction of a pavement. The difference between operating and design speeds is usually considered as the margin of safety of a horizontal curve on a road. In this study, a methodology to determine the margin of safety of an existing curve is proposed. The methodology is based on the reliability theory by which reliability of operational conditions can be analyzed by using a reliability index as a margin of safety. A case study for light vehicles is evaluated to determine high impact variables over reliability, such as, macrotexture, skid resistance, curve radius, and superelevation. The results obtained in this study demonstrated that curve radius, skid resistance, and macrotexture are variables with high impact over failure probability. In constrast, superelevation has little effect on the failure probability. [ABSTRACT FROM AUTHOR]

The Canadian Highway Bridge Design Code (CHBDC) provides two alternative methods for evaluating the strength of existing bridges. The load and resistance factor method provides a general approach and covers the most extreme load situations that can occur in a general bridge population. The mean load method considers the uncertainties of loads acting on a specific bridge, the method of analysis, and resistance of the structure involved, and thus can provide a more accurate evaluation of individual bridges. Since traffic load represents a major portion of bridge loads, a better evaluation of specific bridges is obtained by using the statistical parameters of traffic loads observed on the structure. However, the overall accuracy depends heavily on capturing the most critical loading conditions during the survey periods. The mean load method is particularly valuable where actual traffic loads are expected to be significantly lower than those used in code calibration and when the potential economic benefits arising from a more realistic evaluation outweigh the extra costs of live load data collection and analysis. This paper demonstrates that the mean load method using site-specific traffic loading information can lead to a significantly higher live load-carrying capacity of a bridge. [ABSTRACT FROM AUTHOR]

In designing and assessing pavement performance, the uncertainty in material properties and geometrical variables of pavement and in traffic and environmental actions should be considered. A single factor is employed to deal with these uncertainties in the current American Association of State Highway and Transportation Officials (AASHTO) guide for design of pavements. However, use of this single factor may not ensure reliability-consistent pavement design and assessment because different random variables that may have different degrees of uncertainty affect the safety and performance of pavement differently. Similar problems associated with structural design have been recognized by code writers and dealt with using partial safety factors or load resistance factors. The present study is focused on evaluating a set of partial safety factors to be used in conjunction with the flexible pavement deterioration model in the Ontario pavement analysis of cost and the model in the AASHTO guide for evaluating the flexible pavement performance or serviceability. Evaluation and probabilistic analyses are carried out using the first-order reliability method and simple simulation technique. The results of the analysis were used to suggest factors that could be used, in a partial safety factor format, for designing or assessing flexible pavement conditions to achieve a specified target safety level. [ABSTRACT FROM AUTHOR]

Copyright of Canadian Geotechnical Journal is the property of Canadian Science Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The current practice of highway bridge design in Canada is based on limit states design. Ideally, by means of the properly calibrated load and resistance factors specified in the applicable design code, limit states design will yield a consistent and uniform safety level for all designed bridge structures. Some factors neglected in the standard design procedures, however, may have unexpected effects on the reliability of a particular design. In this case, to follow a design code exactly may still lead to a certain degree of underdesign or overdesign. Therefore, the reliability assessment is recommended for each particular design, and a simulation-based approach for this assessment is proposed in this study. Examples are presented to support the afore-mentioned recommendation.Key words: highway bridges, reliability, design code, simulation, finite strip method.La pratique courante pour la conception des ponts d'autoroute au Canada est basée sur la conception aux états limites. Idéalement, en utilisant des charges correctement calibrées et des facteurs de résistance spécifiés dans les codes de conception applicables, la conception aux états limites donnera un niveau de sécurité constant et uniforme pour toutes les structures de pont conçues. Cependant, quelques facteurs négligés dans les procédures de conception normales peuvent avoir des effets inattendus sur la fiabilité d'un concept en particulier. Dans ce cas, suivre un code de conception à la lettre peut mener, jusqu'à un certain degré, à une sous-conception ou à une sur-conception. Par conséquent, une évaluation de la fiabilité est recommandée pour chaque concept particulier et une approche basée sur la simulation pour cette évaluation est proposée dans cette étude. Des exemples sont présentés afin de supporter les recommandations mentionnées plus haut.Mots clés : ponts d'autoroute, fiabilité, code de conception, simulation, méthode de bandes finies.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Pavements are subjected to repeated traffic and environmental actions. These actions lead to the degradation of pavement and affect the pavement performance. The assessment of pavement performance is important not only for selecting pavement design parameters but also for choosing pavement maintenance and rehabilitation strategies. The traffic loads, the environmental actions, and the properties of pavement material are uncertain. These uncertainties must be taken into account when predicting the pavement performance. Since the traffic and environmental actions vary with time, they should be modeled as stochastic processes. In this study, stochastic models of the net traffic load growth and environmental actions are proposed based on the rectangular pulse processes. These models can be used in conjunction with the Ontario Pavement Analysis of Cost (OPAC) model to predict flexible pavement performance in a probabilistic framework. The prediction of pavement performance for a typical pavement was carried out by using the simple simulation technique and the first-order reliability method. The analysis results suggest that the predicted pavement serviceability measured in terms of the riding comfort index depends on the correlation between traffic effects in each year and the correlation between the environmental actions in each year. The results also suggest that the uncertainty in the riding comfort index is controlled by the uncertainty in traffic and environmental actions in the early stage of service, while it is dominated by the material property of the subgrade in the later stage of service.Key words: deterioration, reliability, pavement, serviceability, stochastic process.Les pavés sont sujets aux effets répétés de la circulation et de l'environnement. Ces effets conduisent à la dégradation du pavé et affectent sa performance. L'évaluation de la performance du pavé est importante non seulement pour la sélection des paramètres de conception du pavé mais aussi pour le choix des stratégies de maintenance et de réhabilitation. Les charges de la circulation, les effets environnementaux et les propriétés des matériaux du pavé sont incertains. Ces incertitudes doivent être prises en considération lors de la prédiction de la performance du pavé. Puisque les effets de la circulation et de l'environnement varient en fonction du temps, ils doivent être modélisés en tant que processus stochastiques. Dans cette étude, des modèles stochastiques des effets de l'accroissement de la charge de la circulation nette et de l'environnement sont proposés et basés sur des processus d'impulsions rectangulaires. Ces modèles peuvent être employés en conjonction avec le modèle d'Analyse de coûts pour pavés de l'Ontario (« Ontario Pavement Analysis of Cost : OPAC ») afin de prédire la performance d'un pavé flexible dans un cadre stochastique. La prédiction de la performance pour un pavé typique a été entreprise en utilisant une technique de simulation simple et la methode de fiabilité du premier ordre. L'analyse des résultats suggère que l'état de service du pavé, tel que mesuré en terme de l'indice de confort de la conduite (« riding comfort index : RCI »), dépend de la corrélation entre les effets de la circulation pour chaque année et de la correlation entre les effets environnementaux pour chaque année. Les résultats suggèrent aussi que l'incertitude sur le RCI est contrôlée par l'incertitude des effets de la circulation et de l'environnement dans les premiers moments suivant la mise en service, alors qu'elle est dominée par la propriété des matériaux de la fondation dans les moments subséquents de la période de service.Mots clés : détérioration, fiabilité, pavé, état de service, processus stochastique.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Tubular joints of offshore structures are prone to fatigue damage. Because of uncertainties involved in quantifying the fatigue process in this type of structure, a reliability approach may be adopted to assess the risks of failure. In-service inspections of structures produce additional information, which may be taken into consideration in order to update the reliability. The paper reviews the methods for carrying out such reliability analyses based on principles of linear elastic fracture mechanics and applies them to a sample tubular joint. The results of this type of analyses may be used for inspection, planning, and (or) decision making regarding repairs or modification of the service life of a structure.Key words: fatigue, reliability, tubular joints, offshore structures, condition assessment.Les joints tubulaires de structures maritimes sont sujets aux dommages dus à la fatigue. À cause des incertitudes inhérentes à la quantification du processus de fatigue dans ce type de structures, une approche de fiabilité peut être adoptée afin d'évaluer les risques de défaillance. Les inspections de structures en service fournissent des informations additionnelles qui peuvent être prise en considération afin de mettre à jour la fiabilité. Cet article revoit les méthodes afin d'entreprendre des analyses de fiabilité basée sur les principes de la mécanique des fractures élastiques linéaires, et les applique sur un exemple de joint tubulaire. Les résultats de ce genre d'analyses peuvent être utilisés pour l'inspection, la planification et/ou le processus de prise de décision touchant les réparations ou la modification de la durée de service de la structure.Mots clés : fatigue, fiabilité, joints tubulaires, structures maritimes, évaluation des conditions.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

Bridge scour is an extremely complex phenomenon because of the random characteristics of sediment laden flow in close proximity to piers and abutments. This occurrence leads to high uncertainties and unavoidable risk in bridge pier and abutment design. In this study, a composite reliability model is developed for the reliability assessment of bridge pier scour using static resistance – loading interference. Based on the physical interpretation of the phenomenon and a statistical analysis of the available information, the relative maximum scour depth (corresponding to the minimum required relative pier footing elevation) and the linear combination of the relative approach flow depth and flow Froude number are defined as the system resistance and external loading, respectively. By examining a set of laboratory and field data, a two-parameter bivariate lognormal distribution is found to represent the joint probability density function of resistance and loading. Reliability expressions are developed in terms of resistance. Use of the model is illustrated in a practical application in which a relationship is obtained between the reliability and safety factors under various return periods. This information is of importance in decision making.Key words: reliability, bridge pier, scour, resistance, loading, safety factor, return period.L'érosion de ponts est un phénomène extrêmement complexe à cause des caractéristiques aléatoires du courant chargé de sédiments à proximité des piliers et des butées. Cet événement amène de grandes incertitudes et des risques incontournables dans la conception de piliers et de butées de ponts. En cela, un modèle de fiabilité mixte a été développé afin d'évaluer la fiabilité contre l'érosion des piliers de ponts en utilisant une résistance statique – interférence de charge. Basé sur l'interprétation physique du phénomène et une analyse statistique de l'information disponible, la profondeur d'érosion maximale relative (correspondant à l'élévation minimale requise des fondations de piliers) et la combinaison linéaire de la profondeur relative du courant suivant le nombre de Froude sont définis comme la résistance du système et la charge externe, respectivement. En examinant une série de données obtenues en laboratoire et sur le terrain, une distribution lognormale bivariée à deux paramètres a été trouvée pour représenter la fonction de densité de probabilité conjointe de la résistance et de la charge. Des expressions de fiabilité ont été développées en termes de résistance. L'utilisation du modèle est illustrée dans une application pratique où une relation est obtenue entre la fiabilité et les facteurs de sécurité pour différentes périodes de retour. Cette information est d'importance dans le processus de décision.Mots clés : fiabilité, pilier de pont, érosion, résistance, chargement, facteur de sécurité, période de retour.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

The bone vascular system is important, yet evaluation of bone hemodynamics is difficult and expensive. This study evaluated the utility and reliability of near-infrared spectroscopy (NIRS), a portable and relatively inexpensive device, in measuring tibial hemodynamics and metabolic rate. Eleven participants were tested twice using post-occlusive reactive hyperemia technique with the NIRS probes placed on the tibia and the medial gastrocnemius (MG) muscle. Measurements were made at rest and after 2 levels of plantarflexion exercise. The difference between oxygenated and deoxygenated hemoglobin signal could be reliably measured with small coefficients of variation (CV; range 5.7-9.8%) and high intraclass correlation coefficients (ICC; range 0.73-0.91). Deoxygenated hemoglobin rate of change, a potential marker for bone metabolism, also showed good reliability (CV range 7.5-9.8%, ICC range 0.90-0.93). The tibia was characterized with a much slower metabolic rate compared with MG ( p  < 0.001). While exercise significantly increased MG metabolic rate in a dose-dependent manner (all p  < 0.05), no changes were observed for the tibia after exercise compared with rest (all p  > 0.05). NIRS is a suitable tool for monitoring hemodynamics and metabolism in the tibia. However, the local muscle exercise protocol utilized in the current study did not influence bone hemodynamics or metabolic rate. Novelty: NIRS can be used to monitor tibial hemodynamics and metabolism with good reliability. Short-duration local muscle exercise increased metabolic rate in muscle but not in bone. High level of loading and exercise volume may be needed to elicit measurable metabolic changes in bone.

The Physical Literacy Assessment for Youth (PLAY) Tools are a suite of tools to assess an individual's physical literacy. The purpose of this study is to examine the psychometric properties of the PLAY Tools, including inter-rater reliability, internal consistency, validity and the associations between the tools. In this study, 218 children and youth (aged 8.4 to 13.7 years) and a parent/guardian completed the appropriate physical literacy assessments (i.e., PLAYbasic, PLAYfun, PLAYparent and PLAYself) and the Bruiniks-Oseretsky Test of Motor Proficiency (BOT-2). Inter-rater reliability for PLAYfun was excellent (intraclass correlation coefficient = 0.94). The PLAYbasic, PLAYfun total, running and object control scores, and PLAYparent motor competence domain were higher in males than females, and PLAYfun locomotor skills were lower in males than females ( p < 0.05). Age was positively correlated with PLAYbasic and PLAYfun ( r = 0.14-0.32, p < 0.05). BOT-2 was positively correlated with PLAYfun and PLAYbasic ( r = 0.19-0.59, p < 0.05). PLAYbasic is a significant predictor of PLAYfun ( r 2 = 0.742, p < 0.001). PLAYfun, PLAYparent and PLAYself were moderately correlated with one another. PLAYfun, PLAYparent and PLAYself demonstrated acceptable internal consistency (α = 0.74-0.87, ω = 0.73-0.87). The PLAY Tools demonstrated moderate associations between one another, strong inter-rater reliability and good construct and convergent validity. Continued evaluation of these tools with other populations, such as adolescents, is necessary. Novelty: In school-age children, the PLAY Tools demonstrated strong inter-rater reliability, moderate associations with one another, acceptable internal consistency and good construct and convergent validity. The results suggest that that PLAY Tools are an acceptable method of evaluation for physical literacy in school-age children.

Voluntary activation can be used to assess central fatigue of the diaphragm after tasks such as exercise or inspiratory muscle loading. Cervical magnetic stimulation (CMS) of the phrenic nerves elicits an involuntary contraction, or twitch, of the diaphragm. This twitch is quantified based on a measure of transdiaphragmatic pressure and can be used to evaluate diaphragm contractile function and diaphragm voluntary activation (diaphragm-VA). The test-retest reliability of diaphragm-VA using CMS is currently unknown. Thirteen participants (4 male, 9 female; aged 25 ± 3 years) performed a series of interpolated twitch manoeuvres, which included a maximal inspiratory effort against a semi-occluded mouthpiece and 2 CMS-stimuli, 1 during the inspiratory manoeuvre and 1 after when the participant returned to functional residual capacity to quantify diaphragm-VA. Intraclass correlation coefficients (ICCs) and standard error of measurement (SEM) measured between-day and within-session reliability of diaphragm-VA, respectively. Maximal diaphragm-VA values were 91% (SD: 6; SEM: 3.9) and 92% (SD: 5; SEM: 2.2) during visits 1 and 2 ( p = 0.68), respectively, and displayed "good" between-day reliability (ICC: 0.88; 95% confidence interval: 0.67-0.95; SEM: 2.7). Our results suggest that assessing diaphragm-VA using CMS is reliable in young healthy adults. Measuring diaphragm-VA may provide additional insight into the consequences and mechanisms of diaphragm fatigue. Novelty: Magnetic stimulation of the phrenic nerves can reliably measure voluntary activation of the diaphragm. Diaphragm voluntary activation can be used to provide additional insight into fatigability of the diaphragm.

Ultrasonography-derived cross-sectional area (CSA) and echo intensity (EI) are increasingly utilized by investigators to study muscle size and quality, respectively. We sought to examine age, sex, and region (proximal, middle, distal) differences in vastus lateralis and rectus femoris CSA and EI, and determine whether correction for subcutaneous fat thickness influences the magnitude of EI differences. Fifteen younger men (mean age = 23 years), 15 younger women (aged 21 years), 11 older men (aged 74 years), and 15 older women (aged 70 years) participated. Clear differences were observed among age, sex, and region for vastus lateralis CSA ( p ≤ 0.013, d = 0.38-0.73), whereas rectus femoris CSA was only different between younger and older participants at the proximal region ( p = 0.017, d = 0.65). Uncorrected EI was greatest at the distal region of both muscles ( p < 0.001, d = 0.59-1.38), with only the younger men having significantly lower EI values than the other groups ( p ≤ 0.043, d = 0.37-0.63). Subcutaneous fat correction resulted in a marked increase in the magnitude of sex-specific EI differences ( p ≤ 0.032, d ≥ 0.42). Additionally, subcutaneous fat correction increased the uniformity of EI throughout the thigh. These findings highlight considerable region-specific differences in muscle size and quality among younger and older men and women and highlight the need to correct for subcutaneous fat thickness when examining EI. Novelty Rectus femoris CSA is similar between younger and older adults except at the most proximal site evaluated. Age- and sex-specific differences in uncorrected EI are nonuniform across the thigh. Correction for subcutaneous fat thickness substantially increased EI in women, resulting in greater sex differences.