The Impact of Neighborhood,Family, and Individual Risk Factors on Toddlers’ Disruptive Behavior

Disadvantaged neighborhoods confer risk for behavior problems in school‐aged children but their impact in toddlerhood is unknown. Relations between toddlers’ disruptive behavior and neighborhood disadvantage, family disadvantage, violence or conflict exposure, parent depressive symptoms, and parenting behavior were examined using multilevel, multigroup (girl–boy) models. Participants were 1,204 families (mean child age = 24.7 months). Unique associations between disruptive behavior and all risk factors were observed, but the effect of neighborhood disadvantage was negligible when all of the more proximal factors were accounted for. The results suggest both that children in disadvantaged neighborhoods are at greater risk of behavior problems than children in nondisadvantaged neighborhoods and that optimal prevention/intervention work with these children will attend to proximal risk factors.     

A comparison of methods to determine maximal accumulated oxygen deficit in running

Abstract

The aim of this study was to compare maximal accumulated oxygen deficit (hereafter O₂ deficit) estimated from the methods of Whipp et al. (1986 Whipp, B. J., Ward, S. A. and Wasserman, K. 1986. Respiratory markers of the anaerobic threshold. Advances in Cardiology, 35: 47–64. [Crossref], [PubMed] , [Google Scholar]), Medbo et al. (1988 Medbo, J. I., Mohn, A. C., Tabata, I., Bahr, R., Vaage, O. and Sejersted, O. M. 1988. Anaerobic capacity determined by maximal accumulated O₂ deficit. Journal of Applied Physiology, 64: 50–60. [PubMed], [Web of Science ®] , [Google Scholar]), and Hill et al. (1998 Hill, D. W., Ferguson, C. S. and Ehler, K. L. 1998. An alternative method to determine maximal accumulated O₂ deficit in runners. European Journal of Applied Physiology, 79: 114–117. [Crossref], [Web of Science ®] , [Google Scholar]) to determine whether they agree sufficiently to be used interchangeably. Nineteen moderately to highly trained endurance runners first performed an incremental test to exhaustion for the determination of maximal oxygen uptake ([Vdot]O_2max) and peak treadmill speed, followed by six randomly ordered constant-speed tests at 95, 100, 105, 110, 110, and 120% of peak treadmill speed. All tests were separated by at least 72 h and were performed within 4 weeks. The method of Whipp produced an O₂ deficit estimate that was lower than that derived from the method of Hill or Medbo (bias ± 95% limits of agreement: ?29.6 ± 36.6 and ?26.1 ± 32.8 ml · kg^?1, respectively; P < 0.001). The O₂ deficit did not differ between the methods of Hill and Medbo (bias ± 95% limits of agreement: 3.5 ± 41.6 ml · kg^?1; n.s.). However, poor correlations (0.21 < r < 0.33; n.s.) together with wide limits of agreement between O₂ deficit estimates (70 – 80% of the mean response) clearly question using these methods interchangeably.     

Arm coordination in elite backstroke swimmers

Abstract

In this study, we assessed arm coordination in the backstroke over increasing speeds by adapting the index of coordination originally used in the front crawl. Fourteen elite male backstroke swimmers swam four trials of 25 m at the speeds corresponding to the 400-m, 200-m, 100-m, and 50-m events. The six phases of the arm stroke were identified by video analysis and then used to calculate the index of coordination, which corresponded to the time between the propulsive phases of the two arms. With increases in speed, the elite swimmers increased the stroke rate, the relative duration of their arm pull, and their index of coordination, and decreased the distance per stroke (P < 0.05). Arm coordination was always in catch-up (index of coordination of ?12.9%) because the alternating body-roll and the small shoulder flexibility did not allow the opposition or superposition coordination seen in the front crawl. This new method also quantified the relative duration of the hand's lag time at the thigh, which did not change (～2%) with increasing speed for the elite swimmers. The index of coordination enables coaches to assess mistakes in backstroke coordination, particularly in the hand's lag time at the thigh.     

Changes in blood lactate and pyruvate concentrations and the lactate-to-pyruvate ratio during the lactate minimum speed test

The aim of this study was to assess the responses of blood lactate and pyruvate during the lactate minimum speed test. Ten participants (5 males, 5 females; mean +/- s: age 27.1 +/- 6.7 years, VO 2max 52.0 +/- 7.9 ml kg -1 min -1 ) completed: (1) the lactate minimum speed test, which involved supramaximal sprint exercise to invoke a metabolic acidosis before the completion of an incremental treadmill test (this results in a ‘U-shaped’ blood lactate profile with the lactate minimum speed being defined as the minimum point on the curve); (2) a standard incremental exercise test without prior sprint exercise for determination of the lactate threshold; and (3) the sprint exercise followed by a passive recovery. The lactate minimum speed (12.0 +/- 1.4 km h -1 ) was significantly slower than running speed at the lactate threshold (12.4 +/- 1.7 km h -1 ) (P < 0.05), but there were no significant differences in VO 2 , heart rate or blood lactate concentration between the lactate minimum speed and running speed at the lactate threshold. During the standard incremental test, blood lactate and the lactate-topyruvate ratio increased above baseline values at the same time, with pyruvate increasing above baseline at a higher running speed. The rate of lactate, but not pyruvate, disappearance was increased during exercising recovery (early stages of the lactate minimum speed incremental test) compared with passive recovery. This caused the lactate-to-pyruvate ratio to fall during the early stages of the lactate minimum speed test, to reach a minimum point at a running speed that coincided with the lactate minimum speed and that was similar to the point at which the lactate-to-pyruvate ratio increased above baseline in the standard incremental test. Although these results suggest that the mechanism for blood lactate accumulation at the lactate minimum speed and the lactate threshold may be the same, disruption to normal submaximal exercise metabolism as a result of the preceding sprint exercise, including a three- to five-fold elevation of plasma pyruvate concentration, makes it difficult to interpret the blood lactate response to the lactate minimum speed test. Caution should be exercised in the use of this test for the assessment of endurance capacity.     

Development of an accelerometer-based multivariate model to predict free-living energy expenditure in a large military cohort

Abstract

This study developed a multivariate model to predict free-living energy expenditure (EE) in independent military cohorts. Two hundred and eighty-eight individuals (20.6 ± 3.9 years, 67.9 ± 12.0 kg, 1.71 ± 0.10 m) from 10 cohorts wore accelerometers during observation periods of 7 or 10 days. Accelerometer counts (PAC) were recorded at 1-minute epochs. Total energy expenditure (TEE) and physical activity energy expenditure (PAEE) were derived using the doubly labelled water technique. Data were reduced to n = 155 based on wear-time. Associations between PAC and EE were assessed using allometric modelling. Models were derived using multiple log-linear regression analysis and gender differences assessed using analysis of covariance. In all models PAC, height and body mass were related to TEE (P < 0.01). For models predicting TEE (r ² = 0.65, SE = 462 kcal · d^?1 (13.0%)), PAC explained 4% of the variance. For models predicting PAEE (r ² = 0.41, SE = 490 kcal · d^?1 (32.0%)), PAC accounted for 6% of the variance. Accelerometry increases the accuracy of EE estimation in military populations. However, the unique nature of military life means accurate prediction of individual free-living EE is highly dependent on anthropometric measurements.     

Sexual dimorphism in the physiques of World Championship divers

Abstract

The aim of this study was to evaluate sexual dimorphism in male (n=43) and female (n=39) springboard and platform divers at the 1991 World Diving Championships in Perth, Western Australia. In addition to recording the age, height and body mass of each diver, measurements were taken of 8 skinfolds, 13 girths, 8 breadths and depths, and 11 lengths. The derived variables were somatotype, sum of 6 skinfolds (SUM6) and height-adjusted proportional z-scores. The mean (±s) values for the males were: age, 22.2±4.6 years; height, 171±9 cm; body mass, 66.7±10.2 kg; somatotype, 2.0–5.3–2.4±0.5–1.0–0.8; SUM6, 45.9 + 11.4 mm. For the females, these values were: age, 20.9±3.8 years; height, 161±6 cm; body mass, 53.7±5.5 kg; somatotype, 2.8–3.8–2.8±0.7–1.0–0.9; SUM6, 65.6±17.0 mm. The males were taller, heavier, more mesomorphic, less endo-morphic and had a smaller SUM6 than the females (P<0.01). A series of discriminant function analyses were applied to groups of variables. Wilks' lambda and the overall F-ratio were highly significant (P<0.001), with correct classification of sex reaching 84–99%. The best combinations of variables were as follows: (1) absolute size, 3 girths + SUM6, or body mass + SUM6 + height (Wilks' lambda=0.17–0.35); (2) relative size, 2 girths + SUM6 + body mass. Combinations of breadths and lengths, skinfolds, or somatotype components, were less successful, with 84–87% classified correctly (Wilks' lambda=0.40–0.48). We conclude that, in addition to the expected absolute size differences, sexual dimorphism between male and female divers can be explained by differences in relative size, skinfolds and somatotype, and that these differences may have implications for coaching and selection in diving.     

Uncovering the Potential: The Role of Technologies on Science Learning of Middle School Students

There is, no doubt, untapped potential in using technological tools to enhance the understanding of science concepts. This study examines the potential by observing 7th and 8th grade middle school students’ (n = 23) use of portable data collection devices in a nine-week elective class, Exploring Technologies. Students’ use of the data collection devices and subsequent interactions were traced through audiocassette and videocassette recordings, field notes, and student artifacts. The culminating activity for the course was a scientific investigation that required students to use the technologies to answer student-selected research questions. To illustrate the use of technology as a mediatory tool, an inquiry investigation of three student groups is described. In examining the three groups of middle school students the researchers encountered specific evidence of technology maximizing students’ science learning. The students were able to use the portable data collection devices in their investigations as they discussed scientific ideas related to temperature and heat. The study’s findings indicated that the three student groups were able to use the tools to conduct scientific inquiry and engage in scientific discourse. Further research on instructional approaches that allow students to develop expertise by using technology as tools to construct knowledge about complex phenomena is encouraged.     

The efficiency of universities

The purpose of this article is to explore the nature of the output of a university and of the inputs to it, in order to see how far measures of productivity or efficiency can be devised. It is assumed to be desirable to use the resources of the institution, necessarily limited, as efficiently as possible in the pursuit of its objects. But there are logical difficulties about any overall measure of efficiency: a university is not like a coal mine. However, useful results can be obtained from a partial approach, and a number of suggestions are offered. A central difficulty is the lack of a sufficient understanding of the nature of the work-load which is most likely to make a person of high intellectual ability effective. It is suggested that a variety of tasks is essential: and this has implications for the use of ancillary staff. A number of sub-sections of university activity can be made more productive provided that minimum standards of performance can be specified. This is occasionally easy, but the specification of performance for (e.g.) central administration is a difficult matter. It is suggested that over-enthusiasm for the better use of buildings and equipment may not always be wise, but that common-sense and operational research can nevertheless lead to significant savings in the use of capital resources.

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Résumé Le but de l'article est d'explorer, dans le cas d'une université, la nature de l'output qu'elle produit et des inputs qu'elle reçoit, pour voir jusqu'à quel point on peut procéder à des mesures de productivité ou d'efficacité. On part du principe qu'il importe d'utiliser les ressources de l'institution, qui sont forcément limitées, aussi intensivement que possible pour atteindre ses objectifs. On rencontre évidemment toutes sortes de difficultés logiques dès que l'on veut procéder à une mesure adéquate d'efficacité: une université n'est pas une houillère. Cependant, on peut atteindre à des résultats utiles par une approche partielle du problème. La difficulté principale réside dans l'ignorance relative où nous sommes de la quantité de travail qui est capable de donner son maximum d'efficacité à une personne d'une grande capacité intellectuelle. On suggère que la variété des tâches est une variable essentielle; ce qui a des conséquences dans l'utilisation du personnel technique. On peut rendre plus productifs certains types d'activité universitaire, pourvu qu'on puisse préciser des niveaux minimum d'accomplissement. Si cela peut parfois se faire aisément, la définition de l'accomplissement dans le cas de l'administration centrale est une chose difficile. On suggère aussi que le zèle extrême déployé pour l'optimisation de l'emploi des locaux et des installations n'est pas toujours très sage, mais que le bon sens et la recherche opérationnelle peuvent néanmoins conduire à des économies sensibles dans l'emploi des ressoureces.

     

Prose organization and recall

In two experiments, subjects read prose materials with various organizations of the superordinate and subordinate conceptual structure of the passage. Variables included organizational salience, massed versus distributed repetition of the passage, nature of the cueing at recall, and number of exposures. In Experiment I, distributed repetition resulted in superior recall, extending the generality of that effect to prose materials; and an advance organizer treatment resulted in lower recall for scrambled materials, contrary to Ausubel's (1960) cognitive theory. High ability subjects recalled more categories than low ability subjects, but the same amount of within-category information. In Experiment II, materials which increased the salience of the organizational structure of the passage were better recalled than scrambled materials after three exposures, or on a test which cued the major categories in the passage. Cueing was detrimental to performance for subjects reading the scrambled passage. Results are discussed in terms of implications for educational practice.     

Using valsiner’s zone theory to interpret Teaching practices in mathematics and science Classrooms

This study explores the use of Valsiners zone theory as a way to interpret the zones of proximal development of three secondary teachers in mathematics and science. Specifically, we used classroom discourse to identify what the participating teachers promoted (zone of promoted action) or allowed (zone of free movement) in the classroom as a way to understand better their potential for development. We found that teachers who promoted actions or events that they ultimately did not allow students to experience seemed to be at a point in their development analogous to Vygotskys pseudo-conceptual stage, prior to full concept formation. Moreover, we found that, at this illusionary zone, the teachers capacity to listen actively to students thinking seemed to affect the teachers transition toward more inquiry-based forms of practice. We concluded that understanding the zone of promoted action and the zone of free movement the teacher organizes in the classroom can indicate the existence or absence of an illusionary zone and thereby provide insight into a teachers potential for development.