Radical Constructivism. Ernst von Glasersfeld.     

Ian Stevenson 《Educational Studies in Mathematics》1998,35(1):93-104

Radical Constructivism is currently a very influencial view in mathematics education. This paper examines its philosophical roots through a review of the book Radical Constructivism by Ernst von Glasersfeld. It begins by describing the structure of the book, and then considers a number of philosophical issues raised by the book. The paper concludes with some reflections on the relationship between philosophy and mathematics education which the book provoked.  相似文献   

Antioxidant-rich beetroot juice does not adversely affect acute neuromuscular adaptation following eccentric exercise     

Tom Clifford  Oliver Bell  Daniel J. West  Glyn Howatson  Emma J. Stevenson 《Journal of sports sciences》2017,35(8):812-819

This study examined the effects of beetroot juice on the repeated bout effect (RBE) to eccentric exercise. Twenty-nine recreationally active males performed two bouts of 100-drop jumps, separated by 14–21 days. Using a double-blind, independent groups design, participants consumed either a higher dose beetroot juice (H-BT; 250 ml, n = 10), a lower dose beetroot juice (L-BT; 125 ml, n = 9) or an isocaloric placebo (PLA; 250 ml, n = 10) for 3 days after bout 1; no drinks were consumed after bout 2. Maximal isometric voluntary contraction (MIVC), countermovement jump (CMJ), pressure-pain threshold (PPT) and creatine kinase (CK) were measured pre, post, 24, 48 and 72 h following both bouts. In bout 2, CMJ and MIVC recovered quicker and CK activity was attenuated (versus bout 1) (P < 0.05) in all groups, demonstrating an RBE. At 24 h post bout 1, MIVC was 84.1 ± 16.1, 83.6 ± 11.6, 79.7 ± 15.1% relative to baseline values in the H-BT, L-BT and PLA groups, respectively; at 24 h post bout 2, MIVC recovered to 90.7 ± 13.7, 92.9 ± 6.9, 87.8 ± 6.9, in the H-BT, L-BT and PLA groups, respectively. These findings suggest that supplementation with antioxidant-rich beetroot juice does not adversely affect acute adaptations to a bout of eccentric exercise.  相似文献   

Policy reviews     

David Stevenson 《Cultural Trends》2015,24(3)

  相似文献   

‘Bloomers’ and the British World: Dress Reform in Transatlantic and Antipodean Print Culture, 1851–1950     

Ana Stevenson 《Cultural and Social History》2017,14(5):621-646

The ‘bloomers’ are rarely considered beyond their 1851 origins in the United States and subsequent appearance in Britain. This article expands dress reform scholarship by analysing print culture elsewhere in the British world, specifically Australia and New Zealand. The colonial press manufactured controversy over this fashion – a perceived transgression of gender norms – even though antipodean women rarely sported the outfit. This article focuses on the dress reform lectures and writings of Amelia Bloomer, Caroline Dexter and Dr Mary Walker. While certain continuities resurfaced alongside the bloomer-like rational dress popularised in the bicycling culture of the 1890s, dress reform was largely deemed far less controversial by the turn of the twentieth century.  相似文献   

The effects of an increased calorie breakfast consumed prior to simulated match-play in Academy soccer players     

Marc A. Briggs  Liam D. Harper  Ged McNamee  Emma Cockburn  Penny L.S. Rumbold  Emma J. Stevenson 《European Journal of Sport Science》2017,17(7):858-866

Dietary analysis of Academy soccer players highlights that total energy and carbohydrate intakes are less than optimal, especially, on match-days. As UK Academy matches predominantly kick-off at ～11:00?h, breakfast is likely the last pre-exercise meal and thus may provide an intervention opportunity on match-day. Accordingly, the physiological and performance effects of an increased calorie breakfast consumed ～135-min before soccer-specific exercise was investigated. English Premier League Academy soccer players (n?=?7) repeated a 90-min soccer match simulation on two occasions after consumption of habitual (B_hab; ～1100?kJ) or increased (B_inc; ～2100?kJ) energy breakfasts standardised for macronutrient contributions (～60% carbohydrates, ～15% proteins and ～25% fats). Countermovement jump height, sprint velocities (15-m and 30-m), 30-m repeated sprint maintenance, gut fullness, abdominal discomfort and soccer dribbling performances were measured. Blood samples were taken at rest, pre-exercise, half-time and every 15-min during exercise. Although dribbling precision (P?=?.522; 29.9?±?5.5?cm) and success (P?=?.505; 94?±?8%) were unchanged throughout all time-points, mean dribbling speed was faster (4.3?±?5.7%) in B_inc relative to B_hab (P?=?.023; 2.84 vs 2.75?m?s^?1). Greater feelings of gut fullness (67?±?17%, P?=?.001) were observed in B_inc without changes in abdominal discomfort (P?=?.595). All other physical performance measures and blood lactate and glucose concentrations were comparable between trials (all P?>?.05). Findings demonstrate that Academy soccer players were able to increase pre-match energy intake without experiencing abdominal discomfort; thus, likely contributing to the amelioration of energy deficits on match-days. Furthermore, whilst B_inc produced limited benefits to physical performance, increased dribbling speed was identified, which may be of benefit to match-play.  相似文献   

Quasi-static mechanical behaviour of soils used for natural turf sports surfaces and stud force prediction     

Igor Guisasola  Iain James  Ceri Llewellyn  Victoria Stiles  Sharon Dixon 《Sports Engineering》2009,12(2):99-109

The quasi-static testing of soils used in natural turf pitches yields key parameters in soil modelling, including elastic moduli, Poisson’s ratio and Mohr–Coulomb parameters for shearing resistance and cohesion in soil. The bulk strength of a Sand soil used in the construction of elite sports surfaces was found to increase initially and then decrease with increasing water content due to apparent cohesion effects. For a Clay Loam soil, more common in recreational facilities, shear strength decreased with water content. Reducing density resulted in a reduction of shear strength and elastic moduli in both soils due to reduced packing of particles reducing particle–particle contact surface area. The effect of roots on the shear strength of a Sand soil was not significant but reduced elastic moduli significantly. Horizontal forces measured during running and turning in a biomechanics laboratory were in good agreement with forces predicted using a simple quasi-static soil model for coarse-grained (Sand) soils although this was not the case with the Clay Loam soil.  相似文献   

Curmudgeon or golden-ager?: reported exercise participation influences the perception of older adults     

Greenlees I  Webb H  Hall B  Manley A 《运动与训练心理学杂志》2007,29(3):333-347

  相似文献   

The cosmic ray hodoscope     

Thomas H. Johnson  E.C. Stevenson 《Journal of The Franklin Institute》1933,216(3):329-337

  相似文献   

Action imitation: the early phase of infancy.     

E Abravanel  E Levan-Goldschmidt  M B Stevenson 《Child development》1976,47(4):1032-1044

The early phase of imitation was studied in children between 6 and 18 months by means of the presentations of 22 actions. Comparison groups were used to assess spontaneous production of actions modeled for the treatment samples. Aanalyses yielded 4 clusters of actions, with 1 cluster showing age and treatment versus comparison group effects and others failing to show both these effects. An important factor affecting imitation was the presence of objects. Actions with objects were imitated more than actions without objects. Measures of attention were found to correlate with imitation level, wheras latency was inversely related to imitation. The presence of sound as a variable that potentially influences imitation was studied, but results were inconclusive. Moreover, imitation and object concept performance were unrelated when the factor of age was controlled.  相似文献