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301.
E C Scott 《American journal of physical anthropology》1984,64(1):83-87
Mellits and Cheek have provided a regression equation which predicts total water, and by extension, fat, from weight and height of women. The equation has been used by many researchers as a convenient means to estimate fat when more complicated body composition estimation techniques are not possible. It is an essential component of evidence provide by Frisch for the critical fat hypothesis. The equation has not been validated on another sample, however, and has a large standard error. I test the Mellits and Cheek equation on five samples of young women, two of which show a normal range of heights and weights. The other three are athletic samples composed of lean women. In the normal samples mean fat percent determined by density (from underwater weighing) is closely approximated by the weight and height equation but not in the lean samples. When measured fat is regressed on estimated fat, correlations are low, and standard errors are high, suggesting that the Mellits and Cheek equation predicts poorly the body fat percentage of individual females. In summary, the Mellits and Cheek equation is moderately useful for the prediction of group means for body composition on samples with normal ranges of height and weight. It does not produce acceptable results on groups selected for extreme leanness or obesity. It is not recommended for fat prediction of individuals. 相似文献
302.
303.
304.
Syunro Utida 《Population Ecology》1953,2(1):22-46
Contributions from the Entomological Laboratory, Kyoto University, No. 226. 相似文献
305.
Antagonist coactivation is the simultaneous activation of agonist and antagonist muscles during a motor task. Age-related changes in coactivation may contribute to observed differences in muscle performance between children and adults. Our aim was to systematically summarize age-related differences in antagonist muscle coactivation during multi-joint dynamic and single-joint isometric and isokinetic contractions. Electronic databases were searched for peer-reviewed studies comparing coactivation in upper or lower extremity muscles between healthy children and adolescents/young adults. Of the 1083 studies initially identified, 25 met eligibility criteria. Thirteen studies examined multi-joint dynamic movements, 10 single-joint isometric contractions, and 2 single-joint isokinetic contractions. Of the studies investigating multi-joint dynamic contractions, 83% (11/13 studies) reported at least one significant age-related difference: In 84% (9/11 studies) coactivation was higher in children, whereas 16% (2/11 studies) reported higher coactivation in adults. Among single-joint contractions, only 25% (3/12 studies) reported significantly higher coactivation in children. Fifty six percent of studies examined females, with no clear sex-related differences. Child-adult differences in coactivation appear to be more prevalent during multi-joint dynamic contractions, where generally, coactivation is higher in children. When examining child–adult differences in muscle function, it is important to consider potential age-related differences in coactivation, specifically during multi-joint dynamic contractions. 相似文献
306.
Bhalla A. K. 《International Journal of Anthropology》2003,18(3):113-125
Distance and velocity pattern of growth for body weight and height of 134 well-off Chandigarh boys aged 9–17 years, and 109
girls aged 9 to 16 years were studied following a mixedlongitudinal growth study design. For both body weight and height pattern-wise,
Chandigarh boys showed close similarity with their American counterparts up to about 13 years of age, while girls did so till
12 years. Where after, Chandigarh children remained lighter and shorter than those of American origin and this differential
may be explained on racial grounds rather than nutritional ones since all children included in this study remained free from
dietary and other health related constraints. Marginally, higher height growth attainments noticed in Chandigarh children
in contrast to their other Indian counterparts during initial years of adolescence shows that Chandigarh children are in process
of expressing their genetic growth potential to its full which has not yet been fully achieved.
The rate (velocity) of weight and height growth in Chandigarh children remained substatially lower than their sex-matched
British counterparts throught the period of study. PHV in boys measured 6.4 cm/yr. and 5.4 cm/yr. in girls. It was attained
at the age of 11.5 years in girls and 12.5 years in boys. Peak weight velocity in boys averaged 3.7 kg/yr., while it measured
4.6 kg/yr. in girls. In girls (11.5 yr.), PWV too was attained earlier than boys (13.5 yr.) by two years. The shorter height
and lighter weight growth attainments noticed in Chandigarh children in contrast to their Western counterparts may be attributed
to slower and lesser magnitude peak growth velocities recorded in Chandigarh children. The use of values presented has been
recommended to monitor and assess growth attainments of Indian children residing in the Union Territory of Chandigarh. 相似文献
307.
Rats either received a single vertical impact (15 km/h) of mechanical energy to their right dorsal skulls over the parietal
region or served as handled controls. About 50% of the rats appeared normal after the impact. Thirty days later there were
conspicuous areas containing neurons with shrunken and darkly stained somas within the cortices beneath the impact site and
within the amygdala and entorhinal cortices. These neurons, occupying an average total area that ranged from 0.50 mm2 to 5 mm2, were evident even in rats that showed no stunning following the impact. These neurons were not seen in control rats. Subsequent
decreases in body weight for rats that received the impact (even with no obvious stunning) were attenuated by oral access
to 10% glucose but not by treatment with acetaminophen or ketamine. The rats that sustained the impact also displayed increased
immobility within settings with which an aversive stimulus had been associated. Post-impact injection with ketamine did not
normalize this behaviour. These results show that quantitative changes in some neuronal soma remain weeks after a single impact
of mechanical energy that is not associated with immediate changes in behaviour. Concomitant with these neuronal alterations
was increased emotional responsiveness to contexts associated with a single aversive episode and transient decreases in body
weights. 相似文献
308.
Determinants of malnutrition in Senegal: Individual, household, community variables, and their interaction 总被引:1,自引:0,他引:1
The relationship between poverty and nutrition is a two-sided one: on the one hand, economic growth (which is generally associated with an eradication of poverty) leads to reduced malnutrition. On the other hand, nutrition is one of the key ingredients for human capital formation, which in turn represents one of the fundamental factors of growth. There are numerous studies that show the correlates of malnutrition using both household- and community-level variables. However, few of these studies allow for the potential endogeneity of community infrastructure or indicate their interplay with characteristics of the mother. The current study considers the socio-economic determinants of child malnutrition and investigates how programs compensate for the increased risks facing young mothers and their children or substitute for a low social status of the mother in the household. The empirical results show that children of mothers giving birth at a young age are disadvantaged in terms of their anthropometric status. Interaction effects of the presence of a non-governmental organization (NGO) or a health post in the village with characteristics of the mother stress the important role played by these institutions in helping disadvantaged mothers overcome their difficulties. These findings have implications for efficient program design and represent a further step towards gaining an improved understanding of the complex determinants of child (mal)nutrition. 相似文献
309.
本文在一定条件下讨论了-混合误差下非参数回归权函数估计的渐近正态性,并且减弱了文献[3]的条件,证明方法大大简化了。 相似文献
310.
《Saudi Journal of Biological Sciences》2023,30(7):103701
Our aim was to compare the health and performance of ad libitum (ADLIB) and restrictedly fed Holstein Friesian heifer calves. Calves were selected to ADLIB (n = 13) and control (n = 13) groups randomly. The period of ADLIB feeding lasted for 3 weeks after colostrum supplementation. The calves in the control group received the same milk replacer, which was supplied according to the restrained feeding schedule of the farm. There was no difference between the two groups in weight, weight gain or movement activity, furthermore in the values of glucose, albumin, total protein, BHB, AST, oxidant and antioxidant status incl. dROM, PAT and OSI. The IL8 gene had higher levels (non significant, p > 0.05) of expression in the ADLIB group during the first 20 days of life, which indicates that ADLIB feeding might potentiate a stronger immune response to environmental stress. The IGF1 gene showed increased expression in the ADLIB fed group at almost all time points, however the difference was already detected on the first day of the study, indicating the importance of individual differences even within the same breed. During the first 10 days INS expression was higher in the restricted group, followed by a shift by day 20 and after, when the ADLIB group showed a higher relative expression level. The observed values describe a trend that, although not significant (p > 0.05), would seem to indicate that ADLIB feeding might potentiate a stronger immune response to environmental stress. 相似文献