The Role of Teachers' Expectations in the Association between Children's SES and Performance in Kindergarten: A Moderated Mediation Analysis

This study examines the role of teachers' expectations in the association between children's socio-economic background and achievement outcomes. Furthermore, the role of children's ethnicity in moderating this mediated relation is investigated. In the present study, 3,948 children from kindergarten are examined. Data are analysed by means of structural equation modeling. First, results show that teachers' expectations mediate the relation between children's SES and their later language and math achievement, after controlling for children's ethnicity, prior achievement and gender. This result indicates that teachers may exacerbate individual differences between children. Second, children's ethnicity moderates the mediation effect of teachers' expectations with respect to math outcomes. The role of teachers' expectations in mediating the relation between SES and math outcomes is stronger for majority children than for minority children

Erosión y desertificación.-Pinhole test for identifying susceptibility of soils to piping erosion: effect of water quality and hydraulic head

ABSTRACT Piping has been observed in both natural and anthropogenic landscapes, in different climates, lithologies and soils, as well as under different types of land uses and vegetation covers. Despite its importance, no standard widely-applied methodology exists to assess susceptibility of soils to piping. This study aims at evaluating the pinhole test for assessing the susceptibility of soils to piping under different conditions. More precisely, the effects of hydraulic head and water quality are being assessed. Topsoil samples (remoulded specimens) with a small range of water contents were taken in Central Belgium (Heverlee) and the susceptibility of these soil samples are investigated under standardized laboratory conditions with a pinhole test device. Three hydraulic heads (50, 180 and 380 mm) and two water qualities (tap and distilled water) were used, reflecting dominant field conditions. The results indicate significant differences between different hydraulic heads and water qualities. Maximum flow discharge was recorded at 380 mm, showing small differences between tap and distilled water. Maximum sediment discharges were recorded at 380 mm and significant higher sediment discharges were observed for distilled water compared to tap water. The tests indicate that the tested soil has an intermediate susceptibility to piping

Pinhole test for identifying susceptibility of different horizons in less - derived soils to piping erosion

The pinhole test is an empirical test based on the qualitative evaluation of the dispersivity (colloidal erodibility) of compacted fined-grained soils. This study evaluates the pinhole test device for the quantitative assessment of the susceptibility of soil horizons to piping. The experiments performed on different loess-derived soil horizons, with different hydraulic head and using distilled water show that the clay-enriched horizon (Bt horizon) is less susceptible to piping than the decalcified (C1) and the calcareous horizon (C2). This study demonstrates that the pinhole test is suitable for assessing the susceptibility of soil horizons to piping in a quantitative way

Impact of land use and soil properties on piping in Belgium

Field observations and literature reveal that land use and soil characteristics play an important role in the development of piping. In this study, the hypothesis is tested that discontinuities in the soil profile favour piping erosion in loess-derived soils in a temperate humid climate. Abiotic characteristics (clay content, bulk density, Ksat, penetration resistance) and the biological activity in the soil were measured for each soil horizon until a depth of at least 40 cm below the pipes (ca. 1.30 m) for 12 representative soil profiles with different land use (pasture with and without collapsed pipes, arable land and forest). No clear discontinuities in abiotic characteristics were observed at soil depths where subsurface pipes occurred, but pastures with piping had significantly more earthworm channels and mole burrows at larger depths than pastures without piping, arable land or forest