Recently we have proposed a monostable reaction-diffusion system to explain the Neolithic transition from hunter-gatherer life to farmer life in Europe. The system is described by a three-component system for the populations of hunter-gatherer (H), sedentary farmer (F1) and migratory one (F2). The conversion between F1 and F2 is specified by such a way that if the total farmers F1 + F2 are overcrowded, F1 actively changes to F2, while if it is less crowded, the situation is vice versa. In order to include this property in the system, the system incorporates a critical parameter (say F0) depending on the development of farming technology in a monotonically increasing way. It determines whether the total farmers are either over crowded (F1 + F2 >F0) or less crowded (F1 + F2 <F0) ( [9, 20]). Previous numerical studies indicate that the structure of travelling wave solutions of the system is qualitatively similar to the one of the Fisher-KPP equation, that the asymptotically expanding velocity of farmers is equal to the minimal velocity (say cm(F0)) of travelling wave solutions, and that cm(F0) is monotonically decreasing as F0 increases. The latter result suggests that the development of farming technology suppresses the expanding velocity of farmers. As a partial analytical result to this property, the purpose of this paper is to consider the two limiting cases where F0 = 0 and F0 → ∞, and to prove cm(0)>cm(∞).

Despite the ongoing problems of undernutrition and infectious disease, obesity and overweight have become a major problem in developing countries, including Bangladesh. This cross-sectional study was undertaken to determine the prevalence of obesity, overweight and underweight among school children aged 6–12 years in Bangladesh. The study was conducted from June 2012 to May 2013 and the study sample comprised 1768 children (980 boys; 788 girls) from eight purposively selected schools in different areas of Dhaka city. Students were interviewed about their diet and physical activity, and anthropometric measurements were made, including height, weight, mid-upper-arm circumference (MUAC), waist circumference, hip circumference and body mass index (BMI). Undernutrition, overweight and obesity were defined using internationally accepted BMI cut-off points. Mean height, weight, BMI, MUAC, waist circumference and hip circumference values were found to be higher in boys than in girls, except at age 12 when these were found to be significantly higher in girls than in boys (p<0.05). The mean prevalence of overweight was 10.0% (boys 10.2%; girls 9.8%), and that of obesity 5.0% (boys 4.3%; girls 5.8%). The prevalence of underweight was 16.3% in boys and 12.7% in girls. The prevalence of underweight was significantly higher in poor than in rich children (22.1% vs 11.2%) and that of obesity was higher in rich than in poor children (9.9% vs 1.3%; p<0.001). A family history of obesity and hypertension emerged as a significant predictor of developing overweight and obesity (p<0.001). The data suggest that underweight and obesity co-exist in urban areas of Bangladesh, posing a challenge for the nutritional health of Bangladeshi children.

This four-year evaluation of the introduction of the System of Rice Intensification (SRI) in northern Myanmar through Farmer Field School (FFS) methods found that these agronomic and pedagogical strategies gave positive results in a complementary way, although their individual contributions to the documented improvement in rice productivity could not be partitioned. The rice production of 612 farmers who had participated in 30 FFSs was tracked, along with that of farmers in the same communities who learned through farmer-to-farmer interaction. Average SRI yields on FFS study-fields in the wet season, without any supplementary irrigation, were 6.4 t ha−1 compared with farmers' prior average yields of 2.1 t ha−1. Three years after one third of the farmers in a community had received FFS training, almost all of its farmers were using SRI methods. This study confirmed many previously reported benefits from SRI practices, particularly important for limited-resource households.