14CO2-in-air sampling with passive diffusion samplers.

Passive diffusion samplers designed for measuring HTO-in-air have been evaluated for measuring 14CO2-in-air. Controlled exposures to HTO-in-air, 14CO2-in-air, and a combination of the two gases were carried out. The sampling rate of the 14CO2-in-air was found to be approximately 0.7 that of HTO-in-air. This value is consistent with the calculated relative sampling rates based on the diffusion coefficients of the gases. Passive diffusion samplers currently used for sampling HTO-in-air at CANDU facilities have been shown to be suitable for also measuring 14CO2-in-air and HTO-in-air simultaneously when prepared with the appropriate sampling solution.

Ventilation parallels plasma potassium during incremental and continuous variable intensity exercise.

The aim of the present investigation was to examine the relationship between plasma potassium (K+) and ventilation (VE) during incremental and prolonged continuous exercise which varied between low and moderate intensity. Seven well-trained male cyclists who had a mean maximal aerobic power (VO2max) of 69.4 +/- 2.9 ml/kg/min were recruited to participate as subjects. The graded incremental exercise bout was composed of 3 min stages set to elicit 40, 50, 60, 70, 80 and 90% VO2max. The continuous variable intensity exercise consisted of 30 min of cycling at 45% VO2max and then 6 x 16 min periods which consisted of cycling for 8 min at 75% VO2max and 8 min at 45% VO2max. During prolonged continuous exercise, VE and plasma K+ changed in a coordinated manner between the low and moderate intensity exercise bouts with the responses during the moderate intensity intervals being significantly greater (p < 0.05) than the responses during the low intensity intervals. During the incremental exercise test, a strong positive relationship between VE and plasma K+ concentration was found for each subject. However, a positive relationship and slope was also found when the VE/K+ ratio was correlated with exercise intensity (r = 0.90-0.99). This indicates that with increasing exercise intensity, the rise in VE becomes increasingly greater than the rise in plasma K+. These findings suggest that the plasma K+ concentration contributes to but may not be the sole determinant of ventilatory regulation during exercise.

Dietary supplements affect the anabolic hormones after weight-training exercise.

To examine the effect of carbohydrate and/or protein supplements on the hormonal state of the body after weight-training exercise, nine experienced male weight lifters were given water (Control) or an isocaloric carbohydrate (CHO; 1.5 g/kg body wt), protein (PRO; 1.38 g/kg body wt), or carbohydrate-protein (CHO/PRO; 1.06 g carbohydrate/kg body wt and 0.41 g protein/kg) supplement immediately and 2 h after a standardized weight-training workout. Venous blood samples were drawn before and immediately after exercise and during 8 h of recovery. Exercise induced elevations in lactate, glucose, testosterone, and growth hormone. CHO and CHO/PRO stimulated higher insulin concentrations than PRO and Control. CHO/PRO led to an increase in growth hormone 6 h postexercise that was greater than PRO and Control. Supplements had no effect on insulin-like growth factor I but caused a significant decline in testosterone. The decline in testosterone, however, was not associated with a decline in luteinizing hormone, suggesting an increased clearance of testosterone after supplementation. The results suggest that nutritive supplements after weight-training exercise can produce a hormonal environment during recovery that may be favorable to muscle growth by stimulating insulin and growth hormone elevations.

Carbohydrate supplementation spares muscle glycogen during variable-intensity exercise.

Effects of carbohydrate (CHO) supplementation on muscle glycogen utilization and endurance were evaluated in seven well-trained male cyclists during continuous cycling exercise that varied between low [45% maximal O2 uptake (VO2 max)] and moderate intensity (75% VO2 max). During each exercise bout the subjects received either artificially flavored placebo (P), 10% liquid CHO supplement (L; 3 x 18 g CHO/h), or solid CHO supplement (S; 2 x 25 g CHO/h). Muscle biopsies were taken from vastus lateralis during P and L trials immediately before exercise and after first (124 min) and second set (190 min) of intervals. Subjects then rode to fatigue at 80% VO2 max. Plasma glucose and insulin responses during L treatment reached levels of 6.7 +/- 0.7 mM and 70.6 +/- 17.2 microU/ml, respectively, and were significantly greater than those of P treatment (4.4 +/- 0.1 mM and 17.7 +/- 1.6 microU/ml) throughout the exercise bout. Plasma glucose and insulin responses of S treatment were intermediate to those of L and P treatments. Times to fatigue for S (223.9 +/- 3.5 min) and L (233.4 +/- 7.5 min) treatments did not differ but were significantly greater than that of P treatment (202.4 +/- 9.8 min). After the first 190 min of exercise, muscle glycogen was significantly greater during L (79 +/- 3.5 mumol/g wet wt) than during P treatment (58.5 +/- 7.2 mumol/g wet wt). Furthermore, differences in muscle glycogen concentrations between L and P treatments after 190 min of exercise and in time to fatigue for these treatments were positively related (r = 0.76, P < 0.05). These results suggest that CHO supplementation can enhance prolonged continuous variable-intensity exercise by reducing dependency on muscle glycogen as a fuel source.

Population and poverty in dependent states: Latin America considered.

"Malthusians maintain that rapid population growth aggravates poverty, while Marxists contend that social formations determine its nature and extent. Each perspective is incomplete, however, since it ignores the insights of the other. Latin American states, characterized by dependent capitalism formations and dominated by ruling elites, are generally incapable of solving the problems of population and poverty. Since population growth under dependent capitalism weakens labor's bargaining position against capital, reduced population growth is emphasized as a labor empowerment strategy the poor can implement on their own to improve their socioeconomic conditions."

Population growth and development in the Third World: the neocolonial context.

PIP: Less developed countries (LDCs) that were colonies of other nations continued operating under the same social and political structures set up by the former ruling nations. The small minority of elites in the LDCs held on to the power acquired during colonial times. In order to preserve their political and financial status after independence, they maintained their close linkages to the capitalist nations and their multinational corporations (MNCs). The elites did not generally have popular support, however. These capitalist nations and their commercial interests continue to dictate most LDCs development process which supports the financial interests of the MNCs and the local elites and not those of the majority, the poor. The poor realize that they are trapped and unable to break away from the economic and political structures, therefore, to assure some form of security, they have many children which exacerbates their poverty. Yet population control policies based on Malthusian theory and those that rely on such undimensional, technical approaches as family planning alone cannot cure the multidimensional social problems of high population growth and poverty. Neither the Malthusian nor Marxist theories totally explain the situation in the LDCs or even provide workable solutions. Research on population and development in LDCs needs to address both the Malthusian concern for the problems posed by high growth rates and the Marxist critique of class struggle in development trends. To eliminate the trap of poverty and dependent economies, each country must design its own remedies based on its history, culture, and geography and alter the prevailing social, economic, and political power structures in favor of the poor. 6 propositions that must be modified to each nation's particular problems and needs are presented to guide LDCs in formulating or reformulating policies to alleviate the problems of population and poverty.^ieng

Use of a ready signal in accommodation assessment.

The usual procedure in making laser optometer measurements of accommodation is to precede each trial with a ready signal. Given previous findings that stress, arousal, attention, etc., can influence accommodation and related phenomena, the question arises as to whether such a ready signal might induce some form of orientation response reflected in alterations of accommodation. Dark focus (DF) accommodation (accommodation in total darkness) was assessed in 26 young adults (13 males and 13 females) under two conditions, one of which involved the use of a ready signal and the other did not. Analyses showed that the presence or absence of the ready signal had no differential impact on accommodation.