Folk Cultures A folk culture is a small isolated, cohesive, conservative, nearly self-sufficient group that is homogeneous in custom and race with a strong family or clan structure and highly developed rituals. Order is maintained through sanctions b...
Evolution of Sleep Sleep is very ancient. In the electroencephalographic sense we share it with all the primates and almost all the other mammals and birds: it may extend back as far as the reptiles. There is some evidence that the two types of sleep...
进化与轮子 从前，研究自然界没有轮子的进化论生物学家都同意不能用无此需要来解释这种现象：轮子对于动物会像对于我们人类一样有好处。 生物学家们推论，动物没有进化出轮子是由下述...
Electricity The modern age is an age of electricity. People are so used to electric lights, radio, televisions, and telephones that it is hard to imagine what life would be like without them. When there is a power failure, people grope about in flick...
Creating Colors There are two ways to create colors in a photograph. One method, called additive, starts with three basic colors and adds them together to produce some other colors. The second method, called subtractive, starts with white light (a mi...
Collectibles Collectibles have been a part of almost every culture since ancient times. Whereas some objects have been collected for their usefulness, others have been selected for their aesthetic beauty alone. In the United States, the kinds of coll...
Colds and Age A critical factor that plays a part in susceptibility to colds is age. A study done by the University of ichigan School of Public Health revealed particulars that seem to hold true for the general population. Infants are the most cold r...
Cohesion-tension Theory Atmospheric pressure can support a column of water up to 10 meters high. But plants can move water much higher; the sequoia tree can pump water to its very top more than 100 meters above the ground. Until the end of the ninete...
Coal-fired Power Plants The invention of the incandescent light bulb by Thomas A. Edison in 1879 created a demand for a cheap, readily available fuel with which to generate large amounts of electric power. Coal seemed to fit the bill, and it fueled t...
Chimpanzee The most striking single fact about chimpanzees is the flexibility of their social life, the lack of any rigid form of organization. It represents about as far a departure from the baboon type of organization as one can find among the high...
Children's Numerical Skills People appear to be born to compute. The numerical skills of children develop so early and so inexorably that it is easy to imagine an internal clock of mathematical maturity guiding their growth. Not long after learning t...
Changing Roles of Public Education One of the most important social developments that helped to make possible a shift in thinking about the role of public education was the effect of the baby boom of the 1950's and 1960's on the schools. In the 1920'...
Cells and Temperature Cells cannot remain alive outside certain limits of temperature, and much narrower limits mark the boundaries of effective functioning. Enzyme systems of mammals and birds are most efficient only within a narrow range around 37 ℃...
British Columbia British Columbia is the third largest Canadian province, both in area and population. It is nearly 1.5 times as large as Texas, and extends 800 miles (1,280km) north from the United States border. It includes Canada's entire west coa...
Botany Botany, the study of plants, occupies a peculiar position in the history of human knowledge.For many thousands of years it was the one field of awareness about which humans had anything more than the vaguest of insights. It is impossible to kn...
