The ecological validity of laboratory cycling: Does body size explain the difference between laboratory- and field-based cycling performance?     

Jobson SA  Nevill AM  Palmer GS  Jeukendrup AE  Doherty M  Atkinson G 《Journal of sports sciences》2007,25(1):3-9

Previous researchers have identified significant differences between laboratory and road cycling performances. To establish the ecological validity of laboratory time-trial cycling performances, the causes of such differences should be understood. Hence, the purpose of the present study was to quantify differences between laboratory- and road-based time-trial cycling and to establish to what extent body size [mass (m) and height (h)] may help to explain such differences. Twenty-three male competitive, but non-elite, cyclists completed two 25 mile time-trials, one in the laboratory using an air-braked ergometer (Kingcycle) and the other outdoors on a local road course over relatively flat terrain. Although laboratory speed was a reasonably strong predictor of road speed (R2 = 69.3%), a significant 4% difference (P < 0.001) in cycling speed was identified (laboratory vs. road speed: 40.4 +/- 3.02 vs. 38.7 +/- 3.55 km x h(-1); mean +/- s). When linear regression was used to predict these differences (Diff) in cycling speeds, the following equation was obtained: Diff (km x h(-1)) = 24.9 - 0.0969 x m - 10.7 x h, R2 = 52.1% and the standard deviation of residuals about the fitted regression line = 1.428 (km . h-1). The difference between road and laboratory cycling speeds (km x h(-1)) was found to be minimal for small individuals (mass = 65 kg and height = 1.738 m) but larger riders would appear to benefit from the fixed resistance in the laboratory compared with the progressively increasing drag due to increased body size that would be experienced in the field. This difference was found to be proportional to the cyclists' body surface area that we speculate might be associated with the cyclists' frontal surface area.  相似文献   

The effectiveness of a mass screening procedure in an early intervention program     

Daniel S. Kirschenbaum  Marion E. Marsh  Joyce B. Devoge 《Psychology in the schools》1977,14(4):400-406

The effectiveness of a mass screening procedure was examined within the context of a preventively oriented school-based treatment program. Mass screening consisted primarily of teachers rating the frequency of all primary grade children's acting-out, moody-withdrawn, and learning problem behaviors. While teachers directly referred 6.9% (n = 48) of the primary grade population of three inner-city schools (n = 698), mass screening subsequently identified an additional 9.7% (n = 68) of this population. Furthermore, both referred and screened-in groups were rated by teachers on the Child Activity Rating Scale (CARS) as behaving much less adaptively relative to a normative group (n = 285; ps < .001). As expected, the referred children evidenced greatest overall dysfunctioning with most pronounced acting-out and learning problems according to ratings by teachers. In addition, further evidence of the validity of the CARS rating form was demonstrated by the agreement between staff predictions of CARS scores and actual ratings by teachers. The mass screening procedure employed is discussed as an effective procedure and suggestions are offered which could increase its utility.  相似文献   

The relationships among sex,sociometric, self,and test anxiety factors and the academic achievement of elementary school children     

Sheldon Cotler  Richard J. Palmer 《Psychology in the schools》1970,7(3):211-216

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Assay validity of point-of-care platelet function tests in thrombocytopenic blood samples     

Conrad Lacom  Alexander Tolios  Markus W. Lffler  Beate Eichelberger  Peter Quehenberger  Eva Schaden  Marion Wiegele 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2022,32(2)

IntroductionPoint-of-care (POC) platelet function tests are faster and easier to perform than in-depth assessment by flow cytometry. At low platelet counts, however, POC tests are prone to assess platelet function incorrectly. Lower limits of platelet count required to obtain valid test results were defined and a testing method to facilitate comparability between different tests was established.Materials and methodsWe assessed platelet function in whole blood samples of healthy volunteers at decreasing platelet counts (> 100, 80-100, 50-80, 30-50 and < 30 x10⁹/L) using two POC tests: impedance aggregometry and in-vitro bleeding time. Flow cytometry served as the gold standard. The number of platelets needed to reach 50% of the maximum function (ED₅₀) and the lower reference limit (ED_ref) were calculated to define limits of test validity.ResultsThe minimal platelet count required for reliable test results was 100 x10⁹/L for impedance aggregometry and in-vitro bleeding time but only 30 x10⁹/L for flow cytometry. Comparison of ED₅₀ and ED_ref showed significantly lower values for flow cytometry than either POC test (P value < 0.05) but no difference between POC tests nor between the used platelet agonists within a test method.ConclusionCalculating the ED₅₀ and ED_ref provides an effective way to compare values from different platelet function assays. Flow cytometry enables correct platelet function testing as long as platelet count is > 30 x10⁹/L whereas impedance aggregometry and in-vitro bleeding time are inconsistent unless platelet count is > 100 x10⁹/L.  相似文献   

Conflict in the Dyadic Play of 3-Year-Old Children     

Marion O'Brien  Carolyn Roy  Anne Jacobs  Mery Macaluso  Vicki Peyton 《Early education and development》1999,10(3):289-313

Episodes of conflict provide a rich source of information about children's development of interactive skills. In the present study, 184 3-year-old children were observed in dyadic play and the 287 conflicts that occurred during their play were transcribed and coded. In general, children's conflicts arose in the context of ongoing play and were brief, lasting less than 15 seconds. Most disputes concerned toy possession, and almost 80% were ended by the simple withdrawal of one or the other children from the conflict. When children responded with emotional intensity to conflict, their conflicts lasted longer and were more likely to be followed by continued negative interaction. Individual difference data were available for one member of each dyad observed in play. Children rated in infancy as having difficult temperaments were found to be more intense during conflict, to spend more time in conflict, and to score higher on an index of conflict resolution competence, whereas concurrent social behavior was not related to conflict variables. Girls scored higher than boys on competence at conflict resolution, and children with better language skills spent less time in conflict. The more time children spent in nonmaternal child care up to age 3, the less likely they were to initiate conflict.  相似文献   

Effect of bike-fit in the perception of comfort,fatigue and pain     

Jose Ignacio Priego Quesada  Pedro Pérez-Soriano  Angel Gabriel Lucas-Cuevas  Rosario Salvador Palmer  Rosa Mª Cibrián Ortiz de Anda 《Journal of sports sciences》2017,35(14):1459-1465

ABSTRACT

The aim of this study was to assess the influence of different bike positions on the perception of fatigue, pain and comfort. Twenty cyclists underwent three tests that involved cycling for 45 min at their individual 50% peak aerobic power output while adopting different positions on the bike. Participants performed the cycling tests adopting three positions defined by two parameters (knee flexion angle [20°, 30°, 40°] and trunk flexion angle [35°, 45°, 55°]) in random order. Angles were measured using a 2D motion analysis system during cycling and applying Fonda’s correction factor. Perceptions of comfort, fatigue and pain were reported before the end of each test. The combination of 40° knee flexion and 35° trunk flexion was perceived as the most uncomfortable position. Moreover, greater knee flexion had a negative effect on trunk comfort, accompanied by greater levels of fatigue and pain perception in the anterior part of the thigh and knee. In conclusion, cyclists perceived the most comfortable position to be when the saddle height was within the recommended knee angle (30° calculated from the offset position or 40 ± 4.0° of absolute value). Upright trunk was found to be the most comfortable position for recreational cyclists, where aerodynamics is not so important. Cyclists’ bike perceptions should be taken into account when it comes to choosing the most beneficial position, since this can play a role in injury prevention and enhance cycling performance.  相似文献   

Description of the suspension gates,erected at the London Docks     

H.R. Palmer 《Journal of The Franklin Institute》1828,5(4):264-266

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An Overview of Significant Influences and Formative Experiences on the Development of Adults’ Environmental Awareness in Nine Countries     

Joy A. Palmer  Jennifer Suggate  Barbara Bajd  Paul Hart K.P.  Roger K.P. Ho  J.K.W. Ofwono‐Orecho 《Environmental Education Research》1998,4(4):445-464

This article, like the preceding one in this special issue of the journal, examines the relative importance of various categories of influence and formative life experiences on the development of environmental educators’ knowledge of and concern for the environment. It provides an overview of data deriving from nine countries (Australia, Canada, Greece, Hong Kong, Slovenia, South Africa, Sri Lanka, Uganda, UK) and highlights global similarities and differences.  相似文献   

Residual force enhancement due to active muscle lengthening allows similar reductions in neuromuscular activation during position- and force-control tasks     

Rhiannon Marion  Geoffrey A. Power 《运动与健康科学(英文)》2020,9(6):670-676

BackgroundResidual torque enhancement (rTE) is the increase in torque observed during the isometric steady state following active muscle lengthening when compared with a fixed-end isometric contraction at the same muscle length and level of neuromuscular activation. In the rTE state, owing to an elevated contribution of passive force to total force production, less active force is required, and there is a subsequent reduction in activation. In vivo studies of rTE reporting an activation reduction are often performed using a dynamometer, where participants contract against a rigid restraint, resisting a torque motor. rTE has yet to be investigated during a position task, which involves the displacement of an inertial load with positional control.MethodsA total of 12 participants (6 males, 6 females; age = 22.8 ± 1.1 years, height = 174.7 ± 8.6 cm, mass = 82.1 ± 37.7 kg; mean ± SD) completed torque- and position-matching tasks at 60% maximum voluntary contraction for a fixed-end isometric contraction and an isometric contraction following active lengthening of the ankle dorsiflexors.ResultsThere were no significant differences in activation between torque- and position-matching tasks (p = 0.743), with ∼27% activation reduction following active lengthening for both task types (p < 0.001).ConclusionThese results indicate that rTE is a feature of voluntary, position-controlled contractions. These findings support and extend previous findings of isometric torque-control conditions to position-controlled contractions that represent different tasks of daily living.  相似文献   

The Development and Implementation of a Prenatal Education Program for Expectant Parents of Multiples     

Joan Esper Kuhnly  Marion Juliano  Patricia Swider McLarney 《The Journal of perinatal education》2015,24(2):110-118

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