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| − | + | Methods: The children were examined three times at their birthdays and at two cross-sectional surveys. Effects of the season of birth were checked by fitting the cosine [http://www.selleckchem.com/products/ldk378.html LDK378] function to empirical values and by comparison between two groups born in different periods of the year. Results: Data gathered at three examinations led to the same results: season-of-birth effect occurred only in boys and only in those relatively shortly breastfed and/or descended from the families of low-socioeconomic status. Specifically, the individuals born in October�CApril were taller (by 2�C3 cm), heavier (by 2�C3 kg), and fatter than those born in May�CSeptember. Conclusions: The following explanatory mechanism has been formulated: insolation in Poland is minimal in November�CFebruary (winter period), and so ultraviolet absorption and vitamin D production is then the lowest. Vitamin D regulates embryo's cellular differentiation, and its deficiency triggers permanent developmental changes. Therefore, individuals conceived in autumn (i) are at the greatest risk of early vitamin D deficiency, (ii) are born in summer, and (iii) are relatively small in their further lives. The contribution of low-socioeconomic status, short breastfeeding, and being a male to the occurrence [http://www.selleckchem.com/products/AG-014699.html AG-014699 cost] of the season-of-birth effect is also discussed. Am. J. Hum. Biol., 2010. ? 2010 Wiley-Liss, Inc. ""2102" "The mechanisms involved in brain thermoregulation are still poorly known, and many disagreements still exist concerning the selective cooling capacity of the brain volume. This issue has also been discussed in human evolution and paleoneurology, speculating on possible changes associated with hominid encephalization. Although the vascular system is supposed to be the main component responsible for thermoregulation, brain geometry also plays an important role in the pattern of heat distribution. In fossils, the only neuroanatomical evidence available for quantitative analyses is the endocranial form, molded by the brain morphology. Here, we present a quantitative method based on numerical simulations to quantify and localize variation in [https://en.wikipedia.org/wiki/Quetiapine Quetiapine] heat dissipation patterns associated with endocranial morphological changes, presenting a case-study on modern humans and chimpanzees. Thermic maps provide a graphic tool to visualize heat loading on the endocranial surface. The distribution of the values (thermic spectrum) supplies a quantification which can help describe and compare the patterns of heat distribution within and between groups. Absolute values are largely influenced by size differences. Normalized values suggest further differences associated with brain shape. Simulation and numerical modeling are useful to provide a descriptive and quantitative approach to endocranial thermoregulation, supplying a quantitative tool to investigate ontogenic and phylogenetic changes. | |
Version du 25 novembre 2016 à 06:55
Methods: The children were examined three times at their birthdays and at two cross-sectional surveys. Effects of the season of birth were checked by fitting the cosine LDK378 function to empirical values and by comparison between two groups born in different periods of the year. Results: Data gathered at three examinations led to the same results: season-of-birth effect occurred only in boys and only in those relatively shortly breastfed and/or descended from the families of low-socioeconomic status. Specifically, the individuals born in October�CApril were taller (by 2�C3 cm), heavier (by 2�C3 kg), and fatter than those born in May�CSeptember. Conclusions: The following explanatory mechanism has been formulated: insolation in Poland is minimal in November�CFebruary (winter period), and so ultraviolet absorption and vitamin D production is then the lowest. Vitamin D regulates embryo's cellular differentiation, and its deficiency triggers permanent developmental changes. Therefore, individuals conceived in autumn (i) are at the greatest risk of early vitamin D deficiency, (ii) are born in summer, and (iii) are relatively small in their further lives. The contribution of low-socioeconomic status, short breastfeeding, and being a male to the occurrence AG-014699 cost of the season-of-birth effect is also discussed. Am. J. Hum. Biol., 2010. ? 2010 Wiley-Liss, Inc. ""2102" "The mechanisms involved in brain thermoregulation are still poorly known, and many disagreements still exist concerning the selective cooling capacity of the brain volume. This issue has also been discussed in human evolution and paleoneurology, speculating on possible changes associated with hominid encephalization. Although the vascular system is supposed to be the main component responsible for thermoregulation, brain geometry also plays an important role in the pattern of heat distribution. In fossils, the only neuroanatomical evidence available for quantitative analyses is the endocranial form, molded by the brain morphology. Here, we present a quantitative method based on numerical simulations to quantify and localize variation in Quetiapine heat dissipation patterns associated with endocranial morphological changes, presenting a case-study on modern humans and chimpanzees. Thermic maps provide a graphic tool to visualize heat loading on the endocranial surface. The distribution of the values (thermic spectrum) supplies a quantification which can help describe and compare the patterns of heat distribution within and between groups. Absolute values are largely influenced by size differences. Normalized values suggest further differences associated with brain shape. Simulation and numerical modeling are useful to provide a descriptive and quantitative approach to endocranial thermoregulation, supplying a quantitative tool to investigate ontogenic and phylogenetic changes.
