Long- and Short-Term Portfolio Choices of Paintings

In their paper on price comovements of paintings, Ginsburgh and Jeanfils show that in three important markets (London, Paris and New York), prices of well-known and lesser known painters 'move together' (are cointegrated). They conclude that therefore, an investor may be indifferent between the two groups of painters. We show that this is not the case, since well-known painters are less risky, and that though returns may be comparable, the share of well-known painters in a portfolio of paintings might be as high as 90%. We also construct long-run and short-run portfolios and show that these may be very different. These short-term portfolios give interesting insights which help in characterizing each of the three markets.     

Exerted effort and performance in climbing among boys: the influence of achievement goals,perceived ability,and task difficulty

In achievement contexts such as sport, achievement goal theory assumes that an individual's major concern is to demonstrate competence. However, competence may be expressed in two ways: as task and ego involvement (Nicholls, 1989). Seventy-eight boys (M age = 13.6 years) performed five climbing courses, and the influence of achievement goals, perceived ability, and task difficulty on effort and performance was studied. According to the achievement goal theory: (a) task-involved boys exerted more effort and performed better than ego-involved boys; and (b) exerted effort was determined by an interaction of one's achievement goal, perceived ability (PA), and task difficulty. Ego-high PA boys and task-low PA boys exerted the most effort on the moderate course; ego-low PA boys exerted least effort on the moderate and very difficult courses. Finally, task-high PA boys exerted more effort on the most difficult courses. The motivational processes underlying these findings are discussed.     

Astronomical broadsheets and their scientific significance

For more than three centuries broadsheets were an important means of quickly disseminating and commenting on the news of the day. They depicted a wide range of events of historical significance, including some of the more striking celestial phenomena such as the appearance of comets. Those that survive often do no more than repeat knowledge that can readily be gained from conventional sources but some have proved of direct value in making astronomical computations and deductions.     

Can the Arts Get Under the Skin? Arts and Cortisol for Economically Disadvantaged Children

This within‐subjects experimental study investigated the influence of the arts on cortisol for economically disadvantaged children. Participants were 310 children, ages 3–5 years, who attended a Head Start preschool and were randomly assigned to participate in different schedules of arts and homeroom classes on different days of the week. Cortisol was sampled at morning baseline and after arts and homeroom classes on two different days at start, middle, and end of the year. For music, dance, and visual arts, grouped and separately, results of piecewise hierarchical linear modeling with time‐varying predictors suggested cortisol was lower after an arts versus homeroom class at middle and end of the year but not start of the year. Implications concern the impact of arts on cortisol for children facing poverty risks.     

Neural Differences in Bilingual Children's Arithmetic Processing Depending on Language of Instruction

Many children in bilingual regions follow lessons in a language at school (school‐language) that they hardly ever speak at home or in other informal settings. What are the neural effects of this phenomenon? This functional magnetic resonance imaging (fMRI) study investigates the effects of using school‐language on brain activity during a high cognitive task in two groups of French/Dutch bilingual children. Participants were asked to assess the correctness of 3‐operand (e.g., 5 ? 2 = 3) and 4‐operand (e.g., 3 ? 2 = 1 + 4) equations, respectively. Instructions about the task were given either in the children's school‐language or in another language that they only used at home. It was found that although both groups recruited a visuomotor occipitofrontal network in the left hemisphere, the children who performed the task in their school‐language showed less activation than the children who did not, indicating the importance of language of instruction for bilingual children's arithmetic processing.     

Running speed-induced changes in foot contact pattern influence impact loading rate

Purpose. We aimed to determine the effect of speed-induced changes in foot contact patterns on the vertical instantaneous loading rate (VILR). We hypothesized that transition runners, i.e. runners that shift towards a mid- (MF) or forefoot contact pattern (FF) when running speed increases, show smaller increases in VILR than non-transition runners, i.e. runners that remain with a rearfoot contact pattern (RF).

Methods. Fifty-two male and female runners ran overground at 3.2, 4.1, 5.1 and 6.2?m?s^?1. Ground reaction forces, lower limb sagittal plane knee and ankle kinematics and plantar pressures were recorded. Multi-level linear regression models were used to assess differences between transition and non-transition runners.

Results. Non-transition runners experienced larger speed-induced increases in VILR (48.6?±?2.6?BW?s^?1 per m?s^?1) than transition runners (–1.4?±?7.6?BW?s^?1 per m?s^?1). Transition runners showed higher VILRs and a more flat foot touch down at the same pre-transition speed than non-transition runners.

Conclusion. When running speed increases, some runners transition towards more anterior foot contact patterns. This reduces or even eliminates the speed-induced increase in VILR. This result is especially the case for those RF runners who already have relatively high VILRs and flat foot positioning at slower running speeds.     

应用RAPD技术研究阿尔卑斯山黄花茅居群内的遗传分化

应用RAPD技术,沿一个海拔梯度研究了阿尔卑斯山黄花茅自然居群的遗传变异和分化。实验 表明,虽然在亚居群间有很少的亚居群独有遗传标记的存在,但通过RAPD资料的聚类分析、主因子分  析以及相关分析观察到遗传分化沿海拔梯度发生,而且亚居群间的遗传分化和它们的海拔高度(地理距  离)呈有意义的正相关。研究结果暗示,在阿尔卑斯山的高山-亚高山过渡区,亚居群间的海拔高度差别  可能导致黄花茅开花和生长物候期的变化,而后者限制了亚居群间的基因流,从而引起居群内的遗传分化。     

Assessing the limitations of the Banister model in monitoring training

The aim of this study was to carry out a statistical analysis of the Banister model to verify how useful it is in monitoring the training programmes of elite swimmers. The accuracy, the ill-conditioning and the stability of this model were thus investigated. The training loads of nine elite swimmers, measured over one season, were related to performances with the Banister model. First, to assess accuracy, the 95% bootstrap confidence interval (95% CI) of parameter estimates and modelled performances were calculated. Second, to study ill-conditioning, the correlation matrix of parameter estimates was computed. Finally, to analyse stability, iterative computation was performed with the same data but minus one performance, chosen at random. Performances were related to training loads for all participants (R(2) = 0.79 +/- 0.13, P < 0.05) and the estimation procedure seemed to be stable. Nevertheless, the range of 95% CI values of the most useful parameters for monitoring training was wide: t(a) = 38 (17, 59), t(f) = 19 (6, 32), t(n) = 19 (7, 35), t(g) = 43 (25, 61). Furthermore, some parameters were highly correlated, making their interpretation worthless. We suggest possible ways to deal with these problems and review alternative methods to model the training-performance relationships.