Velocity and acceleration before contact in the tackle during rugby union matches     

S Hendricks  D Karpul  F Nicolls  M Lambert 《Journal of sports sciences》2012,30(12):1215-1224

Abstract The velocity and acceleration at which the ball-carrier or tackler enters the tackle may contribute to winning the contest and prevailing injury free. Velocity and acceleration have been quantified in controlled settings, whereas in match-play it has been subjectively described. The purpose of this study was to determine the velocity and acceleration of the ball-carrier and tackler before contact during match-play in three competitions (Super 14, Varsity Cup, and Under-19 Currie Cup). Using a two-dimensional scaled version of the field, the velocity and acceleration of the ball-carrier and tackler were measured at every 0.1 s to contact for 0.5 s. For front-on tackles, a significant difference (P??0.05) were evident. Also, the ball-carrier's velocity over the 0.5 s was relatively stable compared with that of the tackler. Results suggest that tacklers adjust their velocity to reach a suitable relative velocity before making contact with the ball-carrier.  相似文献   

Buchbesprechungen     

Eva Schulev-Steindl  Bettina Perthold-Stoitzner 《Zeitschrift für Hochschulrecht, Hochschulmanagement und Hochschulpolitik: zfhr》2009,8(4):134-136

  相似文献   

Buchbesprechungen     

Bettina Perthold-Stoitzner 《Zeitschrift für Hochschulrecht, Hochschulmanagement und Hochschulpolitik: zfhr》2010,9(6):178-179

  相似文献   

The ternary system: Silver bromide—potassium bromide—water     

Raymond H. Lambert 《Journal of The Franklin Institute》1926,202(2):244

  相似文献   

Constructing and resisting disability in mathematics classrooms: a case study exploring the impact of different pedagogies     

Rachel Lambert 《Educational Studies in Mathematics》2015,89(1):1-18

  相似文献   

The significance of learning contexts in talent development     

Albert Ziegler  Elena L. Grigorenko  Bettina Harder 《High Ability Studies》2014,25(1):1-3

  相似文献   

The multistage 20 metre shuttle run test for aerobic fitness   总被引：18，自引：2，他引：16  

L A Léger  D Mercier  C Gadoury  J Lambert 《Journal of sports sciences》1988,6(2):93-101

A maximal multistage 20 m shuttle run test was designed to determine the maximal aerobic power of schoolchildren, healthy adults attending fitness class and athletes performing in sports with frequent stops and starts (e.g. basketball, fencing and so on). Subjects run back and forth on a 20 m course and must touch the 20 m line; at the same time a sound signal is emitted from a prerecorded tape. Frequency of the sound signals is increased 0.5 km h-1 each minute from a starting speed of 8.5 km h-1. When the subject can no longer follow the pace, the last stage number announced is used to predict maximal oxygen uptake (VO2max) (Y, ml kg-1 min-1) from the speed (X, km h-1) corresponding to that stage (speed = 8 + 0.5 stage no.) and age (A, year): Y = 31.025 + 3.238 X - 3.248A + 0.1536AX, r = 0.71 with 188 boys and girls aged 8-19 years. To obtain this regression, the test was performed individually. Right upon termination VO2 was measured with four 20 s samples and VO2max was estimated by retroextrapolating the O2 recovery curve at time zero of recovery. For adults, similar measurements indicated that the same equation could be used keeping age constant at 18 (r = 0.90, n = 77 men and women 18-50 years old). Test-retest reliability coefficients were 0.89 for children (139 boys and girls 6-16 years old) and 0.95 for adults (81 men and women, 20-45 years old).(ABSTRACT TRUNCATED AT 250 WORDS)  相似文献   

Upper bound analysis for estimation of the influence of seepage on tunnel face stability in layered soils     

Wei Liu  Bettina Albers  Yu Zhao  Xiao-wu Tang 《浙江大学学报(A卷英文版)》2016,17(11):886-902

Tunnel face stability is important for safe tunneling and the protection of the surrounding environment. Upper bound analysis is a widely applied method to investigate tunnel face stability. In this paper, a tunnel face collapse of Guangzhou metro line 3 is presented. Accordingly, seepage is considered in the upper bound solutions for face stability in layered soils. Steady-state seepage is reached in the first 1200 s of each drilling step. In the crossed layer, the seepage flow is horizontal toward the tunnel face, whereas in the cover layer, the seepage vertically percolates into the crossed layer. By considering the seepage forces on the tunnel face and on the soil particles, the upper bound solution for the support pressure needed for face stability in layered soil with seepage is obtained. Under saturated conditions, the support pressure is influenced by the variation of the depth ratio due to the seepage effect. Moreover, the support pressure depends linearly on the groundwater level. This study provides estimations of the support pressure for face stability in tunnel design.  相似文献   

Supported playgroups in schools: bonding and bridging family knowledge about transition to formal schooling     

Karen McLean  Susan Edwards  Maria Evangelou  Pamela Lambert 《Cambridge Journal of Education》2018,48(2):157-175

Supported Playgroups in Schools (SPinS) are a new initiative in the Australian early childhood education landscape. SPinS are playgroups hosted by a playgroup coordinator co-located on a local school site. Research has identified positive benefits of playgroup participation for children and families. However, little is known about the potential for SPinS to contribute to families’ knowledge about transition to formal schooling. This paper uses the social capital concepts of ‘bonding’ and ‘bridging’ to examine caregivers’ perspectives on their participation in a SPinS with potential to build parental knowledge about their child’s transition to formal schooling. Three main elements of caregivers’ participation in SPinS with such potential are identified, and these elements are mapped into a continuum of low-to-high bonding and bridging relationships to illustrate the potential for SPinS to contribute to the development of increased knowledge about transition to formal schooling by families of young children.  相似文献   

International Testing in Geography: comparing students' achievements within and between countries     

David Lambert  Kenneth N. Purnell 《Assessment in Education: Principles, Policy & Practice》1994,1(2):167-180

Interest in international testing in geography has been growing since the early 1990s. This paper outlines one project in this area, “InterGeo”, and the problems inherent with such testing. The main findings are that instruments used in international testing in geography may lack validity as they are not embedded in the geography curriculum and experiences that they are endeavouring to test. Furthermore, experience in international testing from other, ‘core’ curriculum areas, notably mathematics and science, provide valuable insights to a number of practical and technical issues which cannot be ignored. This paper argues that despite shortcomings and difficulties further development of international assessment in geography may prove worthwhile. However, the purpose and use of InterGeo, in a future manifestation, needs careful definition. The publication of the International Charter on Geographical Education (IGU, 1992) may be of significant help in fulfilling this task as the InterGeo project develops.  相似文献