Analysis of fatigue failure in D-shaped karabiners     

K. B. Blair Ph D  D. R. Custer  J. M. Graham  M. H. Okal 《Sports Engineering》2005,8(2):107-113

In order to determine the response of aluminum karabiners to cyclic loading, a single type of karabiner (cold forged, D shape, weight 50 g, 7075 aluminum) was cycled to failure under a range of conditions. Deformations were recorded continuously by the testing machine and verified by manual measurement of the karabiner and an uncalibrated strain gauge affixed to the karabiner spine. Internal crack growth was monitored by taking long-exposure X-ray photos of the karabiners near the end of their lifetimes; after failure, the crack surface area was recorded. The load/life (L/N) curve isL _C =85.4 (N _C)^−0.25 for the closed-gate condition andL _O = 39.3 (N _O)^−0.25for the open-gate condition. Deformation occurs only at loads above 12 kN and all measurable deformation occurs in the first three cycles of loading. Crack growth was never observed before failure; crack size is consistent with expectations but the asymmetrical karabiner geometry makes it difficult to compare this data to standards. These results suggest anL/N curve can be used to characterise karabiner lifetime.  相似文献   

The consolidation of mud-silk: A Southeast Asian textile     

Kate Blair  Karen Thompson 《文物保护研究》2014,59(5):S1-S4

  相似文献   

Early Communicative Gestures Prospectively Predict Language Development and Executive Function in Early Childhood     

Laura J. Kuhn  Michael T. Willoughby  Makeba Parramore Wilbourn  Lynne Vernon‐Feagans  Clancy B. Blair  The Family Life Project Key Investigators 《Child development》2014,85(5):1898-1914

Using an epidemiological sample (N = 1,117) and a prospective longitudinal design, this study tested the direct and indirect effects of preverbal and verbal communication (15 months to 3 years) on executive function (EF) at age 4 years. Results indicated that whereas gestures (15 months), as well as language (2 and 3 years), were correlated with later EF (φ_s ≥ .44), the effect was entirely mediated through later language. In contrast, language had significant direct and indirect effects on later EF. Exploratory analyses indicated that the pattern of results was comparable for low‐ and not‐low‐income families. The results were consistent with theoretical accounts of language as a precursor of EF ability, and highlighted gesture as an early indicator of EF.  相似文献   

The persistence of clinical questions across shifts on an intensive care unit: an observational pilot study     

Blair Anton  Sue M. Woodson  Claire Twose  Nancy K. Roderer 《Journal of the Medical Library Association》2014,102(3):201-205

How do clinical questions emerge and move toward resolution in the intensive care setting over the course of 24 hours? In a 20-bed surgical intensive care unit in a large, tertiary-care teaching hospital, informationists shadowed clinicians for 2 48-hour periods to record questions, noting when they were asked and whether they were answered. Thirty-eight percent of 112 recorded questions remained unanswered. Some unanswered questions persisted across shifts, and clinicians'' information-seeking behaviors changed over time. Clinical information services can be improved and integrated more fully into clinical workflows based on a fuller understanding of the life cycle of clinical inquiry.  相似文献   

Enhancing Adherence in Clinical Exercise Trials     

Heather A. O'Neal  Steven N. Blair 《Quest (Human Kinetics)》2013,65(3):310-317

Despite advancements in exercise science research and the development of techniques to promote adherence, exercise adherence is often viewed pessimistically by those in the field of puhlic health and exercise science. It is me that exercise rates in the general population have not changed appreciably over the past two or three decades, and from this perspective, there has been little improvement in exercise adherence. However, recent clinical trials have demonstrated good adherence to both the exercise intervention and measurement protocols in controlled studies. Most methods recommended to improve adherence rates can be easily incorporated into standard research practices and require minimal time. effort, or expense. By considering adherence issues during study design and implementation. investigators can substantially enhance treatment and measurement adherence.  相似文献   

Student enrollment decisions and academic success: evaluating the impact of classroom space design     

Ralph  Michael  Schneider  Blair  Benson  David R.  Ward  Douglas  Vartia  Anthony 《Learning Environments Research》2022,25(2):523-547

Learning Environments Research - Instruction based on active learning is being promoted in higher education by the creation of new collaborative teaching and learning spaces, but capacity does not...  相似文献   

A comparison of ratio and allometric scaling methods for normalizing power and strength in elite rugby union players     

Blair T. Crewther  Nicholas Gill  Robert P. Weatherby  Tim Lowe 《Journal of sports sciences》2013,31(14):1575-1580

Abstract

In this study, we compared the effectiveness of ratio and allometric scaling for normalizing power and strength in elite male rugby union players. Rugby union forwards (n = 18) and backs (n = 20) were assessed for squat jump and bench throw peak power, and box squat and bench press one-repetition maximum strength. The performance data for the forwards and backs were compared using ratio (P/BM) and allometric scaling (P/BM^b ), where P represents performance, BM is body mass in kilograms, and b is a power exponent. A proposed allometric exponent (0.67) and exponents (±95% confidence intervals) derived for the box squat (0.33 ± 0.31), bench press (0.45 ± 0.30), bench throw (0.46 ± 0.36), and squat jump (0.64 ± 0.31) exercises were used. In general, the absolute expression of power and strength was superior for the heavier forwards, but after ratio scaling these performance measures then favoured the lighter backs. There were no performance differences between the forwards and backs after allometric scaling using either the proposed or the derived exponents. Thus, allometric scaling may provide a more effective method for normalizing power and strength in elite athletes when body size is a confounding variable.  相似文献   

Obesity paradoxes     

Paul A. McAuley  Steven N. Blair 《Journal of sports sciences》2013,31(8):773-782

Abstract

In this review, we examine the original obesity paradox phenomenon (i.e. in cardiovascular disease populations, obese patients survive better), as well as three other related paradoxes (pre-obesity, “fat but fit” theory, and “healthy” obesity). An obesity paradox has been reported in a range of cardiovascular and non-cardiovascular conditions. Pre-obesity (defined as a body mass index of 25.0–29.9 kg · m^?2) presents another paradox. Whereas “overweight” implies increased risk, it is in fact associated with decreased mortality risk compared with normal weight. Another paradox concerns the observation than when fitness is taken into account, the mortality risk associated with obesity is offset. The final paradox under consideration is the presence of a sizeable subset of obese individuals who are otherwise healthy. Consequently, a large segment of the overweight and obese population is not at increased risk for premature death. It appears therefore that low cardiorespiratory fitness and inactivity are a greater health threat than obesity, suggesting that more emphasis should be placed on increasing leisure time physical activity and cardiorespiratory fitness as the main strategy for reducing mortality risk in the broad population of overweight and obese adults.  相似文献   

The motivation to study: an analysis of undergraduate engineering students at a Caribbean university     

Chris Maharaj  Erik Blair  Sarah Chin Yuen Kee 《Journal of Further & Higher Education》2018,42(1):24-35

The link between motivation and success is well documented; however, there is still room to problematise motivation in regards to the individual and contextual levels. This study looks at motivation in relation to students studying undergraduate engineering courses at a Caribbean university and seeks to discover the factors that motivate them to study and the factors that keep them motivated. An online questionnaire was constructed using 19 Likert-type questions and 5 questions that allowed for open-ended qualitative responses. The findings reveal that participants tended to be motivated by the increased possibility of desired future careers and tended to stay motivated by a combination of goal-orientation and family support. It is recommended that departments, faculties and institutions deliberate on shared and contextually constructed understandings of why students choose to enrol in particular university courses.  相似文献   

The development of a content analysis model for assessing students’ cognitive learning in asynchronous online discussions     

Dazhi Yang  Jennifer C. Richardson  Brian F. French  James D. Lehman 《Educational technology research and development : ETR & D》2011,59(1):43-70

The purpose of this study was to develop and validate a content analysis model for assessing students’ cognitive learning in asynchronous online discussions. It adopted a fully mixed methods design, in which qualitative and quantitative methods were employed sequentially for data analysis and interpretation. Specifically, the design was a “sequential exploratory” (QUAL → quan) design with priority given to qualitative data and methods. Qualitative data were 800 online postings collected in two online courses. Quantitative data were 803 online postings from the same two courses but from different discussion topics and different weeks. During the qualitative process, a grounded theory approach was adopted to construct a content analysis model based on qualitative data. During the quantitative process, χ² tests and confirmative factor analysis (CFA) which used online postings as cases or observations and was the first of its kind were performed to test if the new model fit the quantitative data.  相似文献