Finite element simulation of the ski–snow interaction of an alpine ski in a carved turn

Skiing manufacturers depend on the development of new skis on trial and error cycles and extensive product testing. Simulation tools, such as the finite element method, might be able to reduce the number of required testing cycles. However, computer programs simulating a ski in the situation of a turn so far lack realistic ski–snow interaction models. The aim of this study was to (a) implement a finite element simulation of a ski in a carved turn with an experimentally validated ski–snow interaction model, and (b) comparison of the simulation results with instantaneous turn radii determined for an actual carved turn. A quasi-static approach was chosen in which the ski–snow interaction was implemented as a boundary condition on the running surface of the ski. A stepwise linear function was used to characterise the snow pressure resisting the penetration of the ski. In a carved turn the rear section of the ski interacts with the groove that forms in the snow. Two effects were incorporated in the simulation to model this situation: (a) the plasticity of the snow deformation, (b) the influence of the ski’s side-cut on the formation and shape of this groove. The simulation results agreed well with experiments characterising snow penetration. Implementation of the groove in the ski–snow interaction model allowed calculation of the instantaneous turn radii measured in actual turns, but also caused significant numerical instability. The simulation contributes to the understanding of the mechanical aspects of the ski–snow interaction in carved turns and can be used to evaluate new ski designs.     

Effects of learning cycle and traditional text on comprehension of science concepts by students at differing reasoning levels

Research has found the learning cycle to be effective for science instruction in hands‐on laboratories and interactive discussions. Can the learning cycle, in which examples precede the introduction of new terms, also be applied effectively to science text? A total of 123 high school students from two suburban schools were tested for reasoning ability, then randomly assigned to read either a learning cycle or traditional text passage. Immediate and delayed posttests provided concept comprehension scores that were analyzed by type of text passage and by reasoning level. Students who read the learning cycle passage earned higher scores on concept comprehension questions than those who read the traditional passage, at all reasoning levels. This result supports the hypothesis that reading comprehension and scientific inquiry involve similar information‐processing strategies and confirms the prediction that science text presented in the learning cycle format is more comprehensible for readers at all reasoning levels. © 1999 John Wiley & Sons, Inc. J Res Sci Teach 36: 23–37, 1999.     

Job involvement in a career transition from university to employment

Job involvement–alienation was studied over three time points with a sample of undergraduate engineers undergoing a career transition from university to paid employment. Data from Newton and Keenan (1991) were re-analyzed under a latent growth curve modelling (LGCM) perspective, in order to provide an alternative analysis of the development of job involvement across that situational change, and to test the hypothesis that job involvement actually changed over that time period. University course satisfaction and anxiety were included as time-invariant predictors of growth, and compared to ascertain whether there would be differential effects of both predictors. The results supported the hypothesized relationships, indicating a significant growth in job involvement–alienation over time, with course satisfaction and course anxiety showing an equivalent impact on its change trajectory.     

Responsiveness of the anterior cruciate ligament – Return to Sports after Injury (ACL-RSI) and Injury – Psychological Readiness to Return to Sport (I-PRRS) scales

ABSTRACT

The ACL-Return to Sport after Injury (ACL-RSI) and Injury-Psychological Readiness to Return to Sport (I-PRRS) scales were developed to assess psychological factors associated with return to sports. Validity and reliability have been determined. The aim of this study was to investigate the responsiveness of the Dutch ACL-RSI and I-PRRS. Seventy patients with ACL reconstruction completed both scales twice 2 months apart, plus a Global Rating of Change (GRC) questionnaire. Distribution and logistic regression-based methods were used to study responsiveness. The Standardized Response Mean (SRM) for the ACL-RSI was 0.3 and for the I-PRRS 0.1, indicating low responsiveness. The minimally important change (MIC) for ACL-RSI was 2.6 and for the I-PRRS 0.9. Since the standard error of measurement (SEM) and smallest detectable change (SDC) were larger than MIC in individual patients, it does not seem possible to distinguish minimally important changes from measurement error in individual patients with either scale. At the group level responsiveness seemed sufficient; hence, both scales can be used to investigate the effectiveness of an intervention at the group level. Both scales can also be used in cross-sectional research and in clinical practice as screening instruments to identify patients at risk of not returning to sports.     

Spot Reduction of Subcutaneous Adipose Tissue

Abstract

This study was designed to determine if the skinfold measurements on an exercised arm would decrease as a result of regular weight training with that arm. Thirty-two subjects completed three sets of 7-RM curls and three sets of 7-RM triceps extensions on either a daily or an alternate day schedule for a period of 6 weeks. The nonexercised arm was measured to establish the specificity of the spot reduction on the exercised arm. The results indicate that hard exercise in a specific area of the arm will result in a reduction of the subcutaneous adipose tissue in that area.     

The Impact of On-campus Student Growth on First-year Student Engagement and Success

During the past two decades institutions of all types have sought to expand and enhance residential facilities. Institutional focus on scale, configuration, amenities, and academic integration has sought to leverage prior research documenting the multiple and often positive impacts of on-campus residence. Although institutional size has been documented to differentially impact student engagement [Kezar, A. J. (2006). NASPA Journal 43(1): 87–114], few studies, however, have directly explored the effect of residential expansion on student engagement. This study, based on a sample of 731 first-time freshmen explores NSSE results before and after the opening of a residential facility that doubled on-campus living at a single, metropolitan institution. Results indicate limited positive differences after opening, and suggest that structure, in the form of size, does not, in and of itself, contribute significantly to shifting engagement. Additionally, these results suggest an alternative method for using NSSE data in institutional analyses.     

Confirmatory factor analysis of word recognition and process measures in the Colorado Reading Project

Measures of word recognition (REC) and two component skills, phonological coding (PHON) and orthographic coding (ORTH), were subjected to multivariate behavioral genetic analysis. Data were obtained from a sample of identical and fraternal twin pairs wherein at least one member of each pair was reading disabled (RD), and from a sample of twins wherein both members of each pair read in the normal range. Confirmatory factor analysis was used to fit the genetic, common environmental, and specific environmental covariance components for REC, PHON, and ORTH within the RD and normal simples. The resulting heritability estimates for REC, PHON, and ORTH were 0.59, 0.41, and 0.05 in the RD sample, and 0.35, 0.52, and 0.20 in the normal sample. After dropping the nonsignificant common environment parameters from the models, the genetic correlations between REC and PHON and between REC and ORTH were respectively 0.81 and 0.45 in the RD sample, and 0.68 and 0.45 in the normal sample. Differences between the genetic correlations were significant in the RD sample (p<0.005), marginally significant in the normal sample (p<0.10), and highly significant in the combined sample (p<0.001), indicating that genetic influences on individual differences in REC are more strongly related to genetic variance in PHON than in ORTH. These results are consistent with previous demonstrations of substantial genetic covariance between the disabled group's deficits in REC and PHON, but not between REC and ORTH (Olson et al., 1989; Olson and Rack, 1990).     

Differential genetic etiology of reading disability as a function of IQ

To test the hypothesis that the genetic etiology of reading disability differs as a function of IQ, composite reading performance data from 223 pairs of identical twins and 169 pairs of same-gender fraternal twins in which at least one member of each pair was classified with reading disability were subjected to multiple regression analysis (DeFries & Fulker, 1985, 1988). In the total sample, heritability of the group deficit in reading performance (h(g)2) was .58 (+/- .08). However, when the basic regression model was fitted separately to data from twin pairs with average Wechsler (1974, 1981) full scale IQ scores below 100 or 100 and above, resulting estimates of h(g)2 were .43 and .72, respectively, a significant difference (p < or = .03, one-tailed). The results of fitting extended regression models to reading performance and continuous IQ data provide evidence that the genetic etiology of reading disability differs as a linear function of IQ (p < or = .007, one-tailed). These results suggest that IQ is relevant for the diagnosis of reading disability and that environmental influences may be more salient as a cause of reading difficulties in children with lower IQ scores.     

Reading disability and chromosome 6p21.3: evaluation of MOG as a candidate gene

Linkage analysis has localized a gene influencing specific reading disability (dyslexia) to 6p21.3. The myelin oligodendrocyte glycoprotein (MOG) gene, which maps to this region, was selected as a candidate. Myelin oligodendrocyte glycoprotein is a membrane protein, a member of the immunoglobin superfamily, that is found on the outermost lamellae of mature myelin. Although the exact function of this protein is unknown, its presence in the central nervous system and the hypothesized relationship between dyslexia and temporal processing rate as well as a suggested relationship with intelligence made this gene a candidate for dyslexia. Analysis of the coding exons and adjacent splice sites in a subset of 22 children with dyslexia from 10 sibships found a missense mutation in exon 4 in 2 of the sibships. This change from the published sequence also occurred in 86 of 96 random controls, making it considerably less frequent in this small sample of individuals with dyslexia. Subsequent typing of this single nucleotide polymorphism (SNP) in 74 nuclear families in which at least one child had reading disability showed no significant difference in frequency from the controls, however. Sib-pair linkage analysis with these families did not show significant linkage with the SNP nor with a separate polymorphic dinucleotide repeat marker in the MOG gene (MOG31/32), but association analysis identified two alleles of MOG31/32 that were associated with reading disability phenotypes with a low level of significance. Thus, although alleles in the MOG gene may be in linkage disequilibrium with a locus that contributes to reading disability, it is unlikely that the MOG gene itself is involved.