population pressure
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This lecture covers resistive forces such as air drag. It includes the viscous (linear in velocity) and pressure (quadratic in velocity) terms. Quantitative demonstrations with balloons and with ball bearings dropped in syrup are shown. He concludes with numerical calculations of air drag examples, also discussing the contribution of air drag to the quantitative experiments down earlier in the course with falling apples.
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In addition to cultural controls acting to maximize fertility, there are important, and often competing, interests of individual families to limit fertility. Unwanted births are dealt with by infanticide in many cultures. Additionally, fertility is regularly controlled by limiting marriage within a culture. Another very important factor in population growth, especially in the tropics, is food availability. Heavy rains in the tropics wash n...more
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Until recently, the world population has been growing faster than exponentially. Although the growth rate has slowed somewhat, there are about 80 million more people each year and about 3 billion more will be added by 2050 (a 50% increase). Population will probably increase more beyond that. Such growth is unprecedented and we cannot predict its long-term effects. The environmental impact of this population increase is bound to be astronom...more
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World population will continue to rise until at least 2050. Environmental impact is the product of the number of people and how much of their income and technology is devoted to either consumption or conservation. So far, the balance is far at the consumption end and, globally, environmental problems are increasing. Environmentalism has not come close to counteracting the footprint of a billion extra people every dozen years. The only mass...more
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The nineteenth century witnessed an unprecedented degree of urbanization, an increase in urban population growth relative to population growth generally. One of the chief consequences of this growth was class segregation, as the bourgeoisie and upper classes were forced to inhabit the same confined space as workers. Significantly, this had opposed effects in Europe, where the working classes typically inhabit the periphery of cities, and t...more
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In this lecture, Professor Diamond continues a review of the nervous system and covers the eye and the ear. She begins by diagramming the eye, and she differentiates between the eye itself and its accessory structures, including the bony orbit, the eyebrow and eyelids, and the conjunctiva. She describes how tarsal glands in the eyes function. Then, Professor Diamond moves on to the subject of the ear. She touches on the three divisions...more
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1) Population in China: Until recently, Chinese families did not much alter their fertility depending on life events such as deaths of children. However, under government prodding and eventually coercion, fertility dropped drastically in China in the 1970s, but to counteract momentum, the One-Child Policy started in 1979-80. 2) Population Growth and Economic Development: In Asia, rapid fertility drops have preceded economic booms by approx...more
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While Nazi Germany's crimes were unprecedented, Adolf Hitler himself was in many respects a typical figure. An idle youth, of seemingly mediocre talents, his political career and passionate hatreds were formed by the experience of World War I. The rise of fascism in Germany, as elsewhere, must be understood in the context of a postwar climate of resentment and instability. Germany's economic crisis, in particular, led the middle classes to...more
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Originally, altruism and self-sacrifice were thought to be incompatible with natural selection, even by Darwin. Now we have several explanations for how altruism can increase an individual's fitness. One is kin selection, or the idea that helping relatives can help increase one's genes in the population. Another involves ecological constraints and punishments. Here, individuals contribute to the group and wait their turn to reproduce.
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Systems consisting of pendulums and springs can freely oscillate at their natural frequencies (also called normal modes). When we expose a system to a wide spectrum of frequencies, the response will be very large at the normal mode frequencies (resonances) of that system. Examples include musical instruments (standing waves on violin strings and pressure waves in wind instruments), and torsional standing waves on a bridge driven by strong winds.
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Concerns about low fertility have been present in many countries for at least 100 years. A large population was considered essential to national power. But the issue is never simply a shortage of warm bodies: overall the world population has increased dramatically over this period and untold numbers would immigrate, if allowed. The issue is the number of the 'right sort' of people, defined as those having preferred national, religious, rac...more
