Spatial heterogeneity and lake morphology affect diffusive greenhouse gas emission estimates of lakes

Most estimates of diffusive flux (F) of methane (CH4) and carbon dioxide (CO2) from lakes are based on single-point flux chamber measurements or on piston velocity (k) modeled from wind speed and single-point measurements of surface water gas concentrations (C-aq). We analyzed spatial variability of F of CH4 and CO2, as well as C-aq and k in 22 European lakes during late summer. F and k were higher in the lake centers, leading to considerable bias when extrapolating single-point chamber measurements to whole-lake estimates. The ratio of our empirical k estimates to wind speed-modeled k was related to lake size and shape, suggesting a lake morphology effect on the relationship between wind speed and k. This indicates that the error inherent to established wind speed models can be reduced by determining k and C-aq at multiple sites on lakes to calibrate wind speed-modeled k to the local system.

Kernels and Designs for Modelling Invariant Functions: From Group Invariance to Additivity

We focus on kernels incorporating different kinds of prior knowledge on functions to be approximated by Kriging. A recent result on random fields with paths invariant under a group action is generalised to combinations of composition operators, and a characterisation of kernels leading to random fields with additive paths is obtained as a corollary. A discussion follows on some implications on design of experiments, and it is shown in the case of additive kernels that the so-called class of “axis designs” outperforms Latin hypercubes in terms of the IMSE criterion.

Health-related quality of life in rural children living in four European countries: the GABRIEL study

OBJECTIVE Measuring children's health-related quality of life (HRQOL) is of growing importance given increasing chronic diseases. By integrating HRQOL questions into the European GABRIEL study, we assessed differences in HRQOL between rural farm and non-farm children from Germany, Austria, Switzerland and Poland to relate it to common childhood health problems and to compare it to a representative, mostly urban German population sample (KIGGS). METHODS The parents of 10,400 school-aged children answered comprehensive questionnaires including health-related questions and the KINDL-R questions assessing HRQOL. RESULTS Austrian children reported highest KINDL-R scores (mean: 80.9; 95 % CI [80.4, 81.4]) and Polish children the lowest (74.5; [73.9, 75.0]). Farm children reported higher KINDL-R scores than non-farm children (p = 0.002). Significantly lower scores were observed in children with allergic diseases (p < 0.001), with sleeping difficulties (p < 0.001) and in overweight children (p = 0.04). The German GABRIEL sample reported higher mean scores (age 7-10 years: 80.1, [79.9, 80.4]; age 11-13 years: 77.1, [74.9, 79.2]) compared to the urban KIGGS study (age 7-10 years: 79.0, [78.7-79.3]; age 11-13 years: 75.1 [74.6-75.6]). Socio-demographic or health-related factors could not explain differences in HRQOL between countries. CONCLUSIONS Future increases in chronic diseases may negatively impact children's HRQOL.