The present study was carried out to assess the influence of socioeconomic status on lung functions and to suggest prediction equations for Indian children. For this purpose, 2,616 normal, healthy schoolchildren aged between 5-15 years were recruited. Boys were classified into three groups, i.e., high-income (HIG), middle-income (MIG), and low-income (LIG), while girls were classified into HIG and LIG groups, based on socioeconomic status (SES). Height, weight, chest circumference, body surface area (BSA), fat-free mass (FFM), and body fat were assessed. Forced expiratory volume in 1 sec (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, and peak expiratory flow rate (PEFR) were measured. The results, before and after adjustment of physical characteristics, showed that anthropometry, body composition, and lung functions were significantly higher in HIG compared to MIG and LIG children, while in girls, no differences were observed in physical characteristics after adjustments. Multiple linear regression equations were developed to predict FEV1, FVC, and PEFR, using independent variables like age, height, fat-free mass, and SES. It is opined that these equations could be used as Indian reference equations for healthy children based on the SES.

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Six sedentary to moderately active men with biochemical signs of riboflavin deficiency were studied under metabolic ward conditions to examine the effects of physical activity on riboflavin status. All participants were subjected to additional exercise (EXER) for an 18 d period between two maintenance (M1 and M2) periods (16 and 13 d respectively) of habitual physical activity. Energy balance and riboflavin intake were maintained throughout the study. Riboflavin status, as judged by a significant reduction in erythrocyte glutathione reductase (EC 1.6.4.2) activation coefficient (EGR-AC), improved on changing from home (1.53 (SD 0.14)) to period M1 (1.36 (SD 0.21)) diets. The exercise period, however, resulted in a significant deterioration in riboflavin status (1.57 (SD 0.31)) which persisted in the subsequent period M2 (154 (SD 0.15)). There was a concomitant fall in the urinary excretion of riboflavin only in the EXER period, when results were expressed as a percentage of the dietary intake of riboflavin. These results suggest an increased demand for the vitamin for selective biochemical functions during exercise. However, the energy cost of walking (treadmill 4 km/h), 50 W and 100 W work-loads (bicycle ergometer) as well as delta mechanical efficiency (DME) did not change during the three metabolic periods. The urinary excretion of riboflavin was inversely related to DME (P -0.49; P < 0.05) and directly correlated with haemoglobin levels (u 0.63; P < 0.005). The present study suggests that riboflavin status further deteriorates during a short period of increased physical activity in individuals whose riboflavin status is marginal.Riboflavin : Glutathione reductase: Physical activity: Mechanical efficiency . ___Studies confined to clinical cases of malnutrition fail to assess the situation in its entirety since they only address the proverbial tip of the iceberg. Investigations on subclinical or biochemical malnutrition, which are major problems in India, are important to rule out any functional consequences on the health and productivity of the population. In India riboflavin deficiency is very common (National Nutrition Monitoring Bureau, 1980), being possibly modulated by dietary as well as non-dietary factors (infection, physical activity etc.; Belko e t Bamji et al. 1987). The basis of the present study was the observed seasonal variations in the riboflavin status of rural Indian women, as assessed by erythrocyte glutathione reductase (NADPH glutathione oxidoreductase; EC 1 . 6 . 4 . 2 ; EGR) activation coefficients (EGR-AC) (National Institute of Nutrition, 1988). Although a majority of women had marked biochemical riboflavin deficiency throughout the year, there was a significant deterioration in riboflavin status during the monsoon season compared with the summer or winter seasons. This change could not be attributed to changes in diet or morbidity. Since during the rains there was augmented physical activity * Present address:

Published and unpublished data on attenuation and internal friction in rocks are calculated and plotted against frequency in the range [Formula: see text] to [Formula: see text] cps. It is shown that for [Formula: see text] [Formula: see text] [Formula: see text] [Formula: see text] The assumptions and limitations in the data analysis are outlined in the text.

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