Force transducer system for measurement of ice hockey skating force     

Tyler J. Stidwill  Rene Albert Turcotte  Phil Dixon  David J. Pearsall 《Sports Engineering》2009,12(2):63-68

The purpose of this study was to develop a portable force measurement system for ice hockey skating. The system consisted of three strain gauge pairs affixed to an ice hockey skate’s blade holder with wire leads connected to a microprocessor controlled data acquisition device carried in a backpack worn by the skater. The configuration of the strain gauges simultaneously determined the vertical and medial–lateral force components experienced by the blade holder with a resolution accuracy of 1.9 N and a coefficient of variation of 9.2%. On-ice testing of this system with subjects performing forward start, acceleration, and constant velocity skating permitted unencumbered, natural movement and demonstrated clear, unambiguous signal responses, high trial-to-trial repeatability, and easy data retrieval. The practicality and accuracy of this testing approach have many applications, such as a quantitative tool for skating force assessment to aid athletes and coaches, as well as providing the means to examine other skill-specific dynamics.  相似文献   

Teacher self-efficacy moderates the relations between imposed pressure from imposed curriculum changes and teacher stress     

David W. Putwain  Nathaniel P. von der Embse 《教育心理学》2019,39(1):51-64

Based on the Job Demands-resources (RD-R) model, the aim of the current study was to examine how pressure arising from imposed curriculum changes and teacher self-efficacy relate to perceived stress in teachers. Participants (839 teachers working in English schools) completed an online survey that contained questions about demographics, self-reported pressure from imposed curriculum changes, teacher self-efficacy, and perceived stress. Pressure from imposed curriculum changes was positively, and teacher self-efficacy negatively, related to perceived stress. Teacher-self efficacy moderated relations between pressure from imposed curriculum changes and perceived stress. High teacher self-efficacy was associated with lower perceived stress, relative to low teacher self-efficacy, when pressure from imposed curriculum changes was low. The differential advantage offered by high self-efficacy declined as pressure from imposed curriculum changes increased.  相似文献   

Insecticidal activity of the medicinal plant, <Emphasis Type="Italic">Alstonia boonei</Emphasis> De Wild,against <Emphasis Type="Italic">Sesamia calamistis</Emphasis> Hampson     

Oigiangbe ON  Igbinosa IB  Tamo M 《Journal of Zhejiang University. Science. B》2007,8(10):752-755

The bioactivity of the aqueous extracts of the leaf and stem bark of the medicinal plant, Alstonia boonei De Wild (Apocyanaceae), against the pink stalk borer, Sesamia calamistis Hampson (Lepidoptera: Noctuidae) was studied in a laboratory bioassay. The extracts were incorporated into artificial diet at a rate of 0.0% (control), 1.0%, 2.5%, 5.0%, and 10.0% (w/w). Both extracts significantly (P<0.01) reduced larval survival and weight in a dose dependent manner. The concentrations that killed 50% of the larvae (LC50) for the stem bark extract were 2.8% and 2.1% at 10 and 20 DAI (days after introduction), respectively, while those for the leaves extract were 5.6% and 3.5%. The weights of the larvae also varied significantly (P<0.05) between the treatments in a dose dependent manner. We conclude that both leaf and stem bark extracts of A. boonei are toxic, used as growth inhibitors to S. calamistis larvae, and hold good promise for use as alternative crop protectants against S. calamistis.  相似文献   

Skating start propulsion: three-dimensional kinematic analysis of elite male and female ice hockey players     

Jaymee R. Shell  Shawn M. K. Robbins  Philippe C. Dixon  Philippe J. Renaud  René A. Turcotte  Tom Wu 《Sports biomechanics / International Society of Biomechanics in Sports》2017,16(3):313-324

The forward skating start is a fundamental skill for male and female ice hockey players. However, performance differences by athlete’s sex cannot be fully explained by physiological variables; hence, other factors such as skating technique warrant examination. Therefore, the purpose of this study was to evaluate the body movement kinematics of ice hockey skating starts between elite male and female ice hockey participants. Male (n = 9) and female (n = 10) elite ice hockey players performed five forward skating start accelerations. An 18-camera motion capture system placed on the arena ice surface captured full-body kinematics during the first seven skating start steps within 15 meters. Males’ maximum skating speeds were greater than females. Skating technique sex differences were noted: in particular, females presented ~10° lower hip abduction throughout skating stance as well as ~10° greater knee extension at initial ice stance contact, conspicuously followed by a brief cessation in knee extension at the moment of ice contact, not evident in male skaters. Further study is warranted to explain why these skating technique differences exist in relation to factors such as differences in training, equipment, performance level, and anthropometrics.  相似文献   

Skating mechanics of change-of-direction manoeuvres in ice hockey players     

Antoine Fortier  René A. Turcotte 《Sports biomechanics / International Society of Biomechanics in Sports》2014,13(4):341-350

Ice hockey requires rapid transitions between skating trajectories to effectively navigate about the ice surface. Player performance relates in large part to effective change-of-direction manoeuvres, but little is known about how those skills are performed mechanically and the effect of equipment design on them. The purpose of this study was to observe the kinetics involved in those manoeuvres as well as to compare whether kinetic differences may result between two skate models of varying ankle mobility. Eight subjects with competitive ice hockey playing experience performed rapid lateral (90°) left and right change-of-direction manoeuvres. Kinetic data were collected using force strain gauge transducers on the blade holders of the skates. Significantly greater forces were applied by the outside skate (50–70% body weight, %BW) in comparison to the inside skate (12–24%BW, p < 0.05). Skate model and turn direction had no main effect, though significant mixed interactions between leg side (inside/outside) with skate model or turn direction (p < 0.05) were observed, with a trend for left-turn dominance. This study demonstrates the asymmetric dynamic behaviour inherent in skating change-of-direction tasks.  相似文献   

Towards a Culture of Application: Science and Decision Making at the National Institute of Standards &; Technology     

Nathaniel Logar 《Minerva》2009,47(4):345-366

How does the research performed by a government mission agency contribute to useable technologies for its constituents? Is it possible to incorporate science policy mechanisms for increasing benefits to users in the decision process? The United States National Institute of Standards &; Technology (NIST) promises research directed towards industrial application. This paper considers the processes that produce science and technology at NIST. The institute’s policies for science provide robust examples for how effective science policies can contribute to the emergence of useful technologies. To progress towards technologies that can be years away, the agency uses several means for integrating the needs of eventual information users into the prioritization process. To accomplish this, NIST units, such as the Materials Science and Engineering Laboratory, incorporate mechanisms for considering user need and project impact into different stages of its scientific decision processes. This, and other specific strategies that the agency utilizes for connecting the supply of science to information demand, provide lessons for generating useable science.  相似文献   

Whole-body predictors of wrist shot accuracy in ice hockey: a kinematic analysis     

Michaud-Paquette Y  Magee P  Pearsall D  Turcotte R 《Sports biomechanics / International Society of Biomechanics in Sports》2011,10(1):12-21

The purpose of this study was to identify joint angular kinematics that corresponds to shooting accuracy in the stationary ice hockey wrist shot. Twenty-four subjects participated in this study, each performing 10 successful shots on four shooting targets. An eight-camera infra-red motion capture system (240 Hz), along with passive reflective markers, was used to record motion of the joints, hockey stick, and puck throughout the performance of the wrist shot. A multiple regression analysis was carried out to examine whole-body kinematic variables with accuracy scores as the dependent variable. Significant accuracy predictors were identified in the lower limbs, torso and upper limbs. Interpretation of the kinematics suggests that characteristics such as a better stability of the base of support, momentum cancellation, proper trunk orientation and a more dynamic control of the lead arm throughout the wrist shot movement are presented as predictors for the accuracy outcome. These findings are substantial as they not only provide a framework for further analysis of motor control strategies using tools for accurate projection of objects, but more tangibly they may provide a comprehensive evidence-based guide to coaches and athletes for planned training to improve performance.  相似文献   

Implementing VuFind: A Public Library Improves Electronic Search Quality and Saves Searcher Time     

Maria K. Burchill  Nathaniel Rasmussen 《Public Library Quarterly》2014,33(1):76-82

Web-scale discovery services (WSDs) are a widespread phenomenon sweeping university libraries across the world. In this article the authors discuss this trend and their experience working on a test server with the open source discovery layer VuFind. Developed by Demian Katz of Villanova University, VuFind’s potential to index not only the library’s catalog but also proprietary databases through the integration of application program interfaces (APIs) offers public libraries the opportunity to develop a seamless website-to-catalog experience, thereby building a true virtual branch for their patrons.  相似文献   

‘Playing with or like the girls’: advancing the performance of ‘multiple masculinities in Black boys’ childhood play’ in U.S. early childhood classrooms     

Nathaniel Bryan 《Gender and education》2019,31(3):309-326

Play is a gendered activity among young children, especially boys. Boys often tend to be more actively engaged in the (re)production of gendered play. However, most research studies and conceptual papers have misread, ignored, devalued, or scrutinized the gendered ways Black boys engage in play. This idea is particularly true for Black boys who may not play within the monolithic gendered expectations of childhood play. Drawing from [Connell, R. W. (1995). Masculinities. Berkeley: University of California Press] notion of multiple masculinities, I propose what I call the performance of ‘multiple masculinities of Black boys’ childhood play’ to embrace the ways some Black boys engage in play activities, which may not fit within the performance of hegemonic and Black masculine norms and expectations. In so doing, I call for educators to broaden how we view Black boys, and our definition of Black masculinity so that embracing what might be traditionally called ‘less masculine’ and/or stereotypically feminine could be valued male traits. Recommendations are provided for early childhood educators to support the confluence of ways Black boys engage in play experiences.  相似文献   

Psychometric defensibility of the Intervention Selection Profile‐Social Skills (ISP‐SS) with students at risk for behavioral concerns     

Stephen P. Kilgus  Katie Eklund  Nathaniel P. von der Embse 《Psychology in the schools》2019,56(4):526-538

The purpose of the current study was to examine the validity and diagnostic accuracy of the Intervention Selection Profile—Social Skills (ISP‐SS), a brief social skills assessment tool intended for use with students in need of Tier 2 intervention. Participants included 160 elementary and middle school students who had been identified through universal screening as at risk for behavioral concerns. Teacher participants ( n = 71) rated each of these students using both the ISP‐SS and the Social Skills Improvement System—Rating Scales (SSiS‐RS), with the latter measure serving as the criterion within validity and diagnostic accuracy analyses. Confirmatory factor analysis supported ISP‐SS structural validity, indicating ISP‐SS items broadly conformed to a single “Social Skills” factor. Follow‐up analyses suggested ISP‐SS broad scale scores demonstrated adequate internal consistency reliability, with hierarchical omega coefficient equal to 0.86. Correlational analyses supported the concurrent validity of ISP‐SS items, finding each ISP‐SS item to be moderately or highly related to its corresponding SSiS‐RS subscale. Finally, analyses indicated three of the seven ISP‐SS items that demonstrated sufficient diagnostic accuracy; however, findings suggest additional revisions are needed if the ISP‐SS is to be appropriate for use in schools. Implications for practice and future research are discussed.  相似文献