Expanding schooling opportunities for 4-year-olds

We use a novel quasi-experimental strategy to estimate the effect of expanding early schooling enrollment possibilities on early achievement. It exploits two features of the school system in The Netherlands. The first is rolling admissions; children are allowed to start school immediately after their 4th birthday instead of at the beginning of the school year. The second is that children having their birthday before, during and after the summer holiday are placed in the same class. These features generate sufficient exogenous variation in children’s enrollment opportunities to identify its effects on test scores. Making available one additional month of time in school increases language scores of disadvantaged pupils by 6 percent of a standard deviation and their math scores by 5 percent of a standard deviation. For non-disadvantaged pupils we find no effect.     

Neuromuscular characteristics of endurance- and power-trained athletes

In response to chronic physical training, the human neuromuscular system undergoes significant and specific adaptations. More importantly, these influences are the result of the type and quantity of physical activity. One of the simplest neuromuscular mechanisms is the spinal stretch reflex. The reflex system was previously viewed as inflexible, with a relatively fixed response that could vary only slightly. However, more recent data have identified an adaptive plasticity in the reflex system. In this respect, the reflex system can be used to assess training and aging adaptations of the human neuromuscular system. Due to their methodological simplicity, both the tendon-tap reflex and the electrically evoked Hoffmann reflex (H-reflex) can be used to assess training adaptations of the human neuromuscular system. The purpose of this paper is to review briefly the tendon-tap and H-reflex paradigms and delineate the research findings pertaining to changes in the reflex system with physical training. For purposes of clarity, this discussion will be divided into the following: (a) differences observed in the tendon-tap reflex, (b) differences observed in the H-reflex, and (c) role of interneurons in mediating these changes.