Natural radiation is the major source of human exposure to ionising radiation, and its largest contributing component to effective dose arises from inhalation of (222)Rn and its radioactive progeny. However, despite extensive knowledge of radiation risks gained through epidemiologic investigations and mechanistic considerations, the health effects of chronic low-level radiation exposure are still poorly understood. The present paper reviews the possible contribution of studies of populations living in high natural background radiation (HNBR) areas (Guarapari, Brazil; Kerala, India; Ramsar, Iran; Yangjiang, China), including radon-prone areas, to low dose risk estimation. Much of the direct information about risk related to HNBR comes from case-control studies of radon and lung cancer, which provide convincing evidence of an association between long-term protracted radiation exposures in the general population and disease incidence. The success of these studies is mainly due to the careful organ dose reconstruction (with relatively high doses to the lung), and to the fact that large-scale collaborative studies have been conducted to maximise the statistical power and to ensure the systematic collection of information on potential confounding factors. In contrast, studies in other (non-radon) HNBR areas have provided little information, relying mainly on ecological designs and very rough effective dose categorisations. Recent steps taken in China and India to establish cohorts for follow-up and to conduct nested case-control studies may provide useful information about risks in the future, provided that careful organ dose reconstruction is possible and information is collected on potential confounding factors.

Genetic diversity is prerequisite for any crop improvement program as it helps in the development of superior recombinants. Fifty Malaysian upland rice accessions were evaluated for 12 growth traits, yield and yield components. All of the traits were significant and highly significant among the accessions. The higher magnitudes of genotypic and phenotypic coefficients of variation were recorded for flag leaf length-to-width ratio, spikelet fertility, and days to flowering. High heritability along with high genetic advance was registered for yield of plant, days to flowering, and flag leaf length-to-width ratio suggesting preponderance of additive gene action in the gene expression of these characters. Plant height showed highly significant positive correlation with most of the traits. According to UPGMA cluster analysis all accessions were clustered into six groups. Twelve morphological traits provided around 77% of total variation among the accessions.

This study examined the effect of a motor intervention based on the attention, balance, and coordination (ABC) learning approach on motor proficiency and executive functions in children with learning disabilities (LD). Forty-five male elementary school students with LD aged 7-9 years were recruited and randomly assigned into one of three groups: two experimental groups and one control group. Experimental Group A received only the motor intervention. Experimental Group B simultaneously received both motor intervention and regular educational services. The control group received only regular educational services. The motor intervention involved sequential station exercises based on ABC; this training took place in 24 sessions, scheduled three times a week for eight weeks. We obtained children’s scores on the Bruininks-Oseretsky Tests of Motor Proficiency, N-Back Test, Tower of London, and Continuous Performance Tests at pretest, posttest, and follow-up testing. Our results showed that both experimental groups significantly improved their motor skills and most measures of executive functions, relative to no significant improvement for the control group. The improvements on some measures of executive functions in Experimental Group B were just slightly better than in Experimental Group A. This study supported Blythe’s ABC learning approach emphasizing ABC, and it extended earlier findings of benefits of this approach to populations of children with LD.