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This chapter discusses four distinct processes of economic growth: a) Solovian growth, in honor of Robert Solow; b) Smithian growth, Adam Smith's mechanism of growth; c) scale or size effects, which maintained that population growth itself can lead to per capita income growth; and Schumpeterian growth, by Joseph A. Schumpeter. It focuses on the Schumpeterian form of economic growth, which usually accompanies technological change. The chapter discusses technological change dealing with other forms of economic growth only insofar as they touch upon technological change directly. It points out that technological creativity is analyzed largely as a social, rather than an individual, phenomenon. The chapter focuses on why there were, and whether there still are, societies that have more creative individuals in them than others, and discusses the question that lies at the foundation of the issue of issues: Why does economic growth (at least of the Schumpeterian type) occur in some societies and not others?

This chapter examines two important developments in endogenous growth theory: the scale effect of human capital on economic growth and two models that were developed to assess the impact of growth on inequality and vice versa. It discusses the problem from the point of view of political economy, describes an overlapping generation model where agents are endowed with bequest motives to derive the long-run implications for income distribution, and considers private economy vs. command economy. It also analyses the link between tax rate and growth rate.

Current approaches of measuring segregation are constrained by data derived from census enumeration units of pre-defined boundaries, and the fact that the measures cannot reflect individual experience in the neighbourhood. This chapter suggests an approach to derive neighbourhoods for each individual. A program EquiPop was developed to construct neighbourhoods for each individual at various geographical scales in terms of k-nearest neighbour. Then traditional segregation indices (entropy and isolation) can use these population counts derived from individualised neighbourhoods to evaluate segregation. The approach was demonstrated using the register data of several Swedish cities.

The potential for human activities to adversely affect the environment has become of increasing concern during the past three decades. As a result, the transport and fate of contaminants in subsurface systems has become one of the major research areas in the environmental/hydrological/earth sciences. An understanding of how contaminants move in the subsurface is required to address problems of characterizing and remediating soil and groundwater contaminated by chemicals associated with industrial and commercial operations, waste-disposal facilities, and agricultural production. Furthermore, such knowledge is needed for accurate risk assessments; for example, to evaluate the probability that contaminants associated with a chemical spill will reach an aquifer. Just as importantly, knowledge of contaminant transport and fate is necessary to design “pollution-prevention” strategies. A tremendous amount of research on the transport of solutes in porous media has been generated by several disciplines, including analytical chemistry (chromatography), chemical engineering, civil/environmental engineering, geology, hydrology, petroleum engineering, and soil science. This research includes the results of theoretical studies designed to pose and evaluate hypotheses, the results of experiments designed to test hypotheses and investigate processes, and the development and application of mathematical models useful for integrating theoretical and experimental results and for evaluating complex systems. While much of the previous research has focused on transport of nonreactive solutes, it is the transport of “reactive” solutes that is currently receiving increased attention. Reactive solutes are those subject to phase-transfer processes (e.g., sorption, precipitation/dissolution) and transformation reactions (e.g., biodegradalion). Of special interest in the field of contaminant transport is so-called nonideal transport. In the most general sense, nonideal transport can be described as transport behavior that deviates from the behavior that is predicted using a given set of assumptions. A homogeneous porous medium and linear, instantaneous phase transfers and transformation reactions are the most basic set of assumptions for ideal solute transport in porous media. As discussed in a recent review, transport of reactive contaminants is often nonideal (Brusseau, 1994). The potential causes of nonideal transport include rate-limited and nonlinear mass transfer and transformation reactions, as well as spatial (and temporal) variability of material properties.

This chapter reviews the current in-situ and remote-sensing instrumentation, and discusses some problems and limitations such as instrument calibrations, expected accuracy, software analysis problems, and scale effects. It also discusses the vertical and geographical variations in aerosol and cloud microphysical properties.

In the real world—beyond pedagogy, beyond hypocrisy—language has two purposes: to facilitate thought, and to prevent it. Seldom does a writer skilled in the arts of persuasion call attention to the second purpose because to do so would be to arouse suspicions of his own verbalizations. Rhetoric—ambiguous, deceptive, delusive rhetoric—stands ever ready to help writers of all persuasions to "throw dust in the jurymen's eyes." Population pundits use this tactic when they entitle an article or book "Standing Room Only." In getting the reader's attention those three words substitute trivia for fundamentals. Before another work with that title is published let's see why "Standing Room Only" is so silly. How much of the earth's land area would now be occupied if the present five billion inhabitants were crowded together on a "standing room only" basis? Taking the space occupied by the average human being, standing up, as three square feet (a rectangle 3 X 1 feet), a square mile could accommodate just a little more than 9 million standees. Five billion people (the population of the earth in 1987) could be accommodated on a mere 556 square miles, just 46 percent of the area of Rhode Island, our smallest state. A perfect square, 24 miles on a side, could accommodate the world's entire population, standing up. Alaska, with an SRO capacity of 5 trillion, could accommodate a thousand times the present world population. Let's look at some more absurd statistics. If all the land area of the earth were covered by SRO patrons, what would be the total population? And how long would it take the present population to reach that figure, if the recent rate of world population increase (1.7 percent per year) could be maintained? The earth's land area (1.48 X 1014 square meters) divided by the area occupied by one person (0.28 square meters) = 5.29 X 1014, or 529 trillion human beings. It would take 5 billion people, increasing at 1.7 percent per year, just 686 years to swell to that number. That time lapse is only 34 percent as great as the total Christian era to date.

This chapter examines the models of endogenous growth, in which the rate of growth is sensitive to the rate of factor accumulation, and technical progress is an economic activity that results from rational decisions by households and firms. It evaluates the simplest model of endogenous growth with maximizing consumers. This model is called the AK model. It also studies a seminal model called the Romer model, in which technical progress occurs through returns to diversification among horizontally differentiated products. In addition, it analyzes a different model, wherein the main mechanism is that the productivity of each production process can be improved via research. The chapter then assesses the issue of the scale effects.

Were we able to talk with other animals, it is extremely unlikely that we should hear them debating the problem of population control. They don't need to debate: nature solves the problem for them. And what is the problem? Simply this: to keep a successful species from being too successful. To keep it from eating itself out of house and home. And the solution? Simply predation and disease, which play the role that human beings might label "providence." As far as the written record reveals, no one recognized the self-elimination of a species as a potential problem for animals until the danger had become suspected among human beings. One of the earliest descriptions of this population problem for other animals was given by the Reverend Joseph Townsend, an English geologist. His key contribution was published in 1786, twelve years before Malthus's celebrated essay (Box 25-1). Townsend was dependent upon others for the outline of his story, and there is some question as to whether the details are historically correct. But the thrust of the story must be true: a single species (goats, in this case) exploiting a resource (plants) cannot, by itself, maintain a stable equilibrium at a comfortable level of living. The animals will either die after eating up all the food, or their numbers will fluctuate painfully. (Details differ, depending on the species and the environment.) Stability and prosperity require that the gift of exponential growth be opposed by some sort of countervailing force (predatory dogs, in Townsend's example). However deplorable predators may be for individuals who happen to be captured and eaten, for the prey population as a whole predators are (over time) a blessing. With millions of different species of animals there are many different particular explanations of how they manage to persist for thousands or millions of years. The species we are most interested in is, of course, Homo sapiens. A meditation on Townsend's account led to a challenging set of questions. "If all this great earth be no more than the Island of Juan Fernandes, and if we are the goats, how can we live "the good life" without a functional equivalent of the dogs? Must we create and sustain our own dogs? Can we do so, consciously? And if we can, what manner of beast will they be?"

The Malthusian theory hypothesizes that the natural environment imposes various capacity constraints on human population growth and that population size has been and will be checked by these constraints. In such a classical theory, which was presumably motivated by observations of the ancient world, population might be the most important dynamic variable, although its role is rather passive: population is a variable that would be affected by, but would not affect, the environment. Boserup (1981), however, sees the role of population in the development of human economy as more consequential. She gave many persuasive examples that showed that, at least for the period up to the mid-twentieth century, population size might be a variable which actively spurred technological progress. This is also the viewpoint held by Lee (1986) and Pryor and Maurer (1982). After the Industrial Revolution, the role of population in economic dynamics, along with the reduction of mortality fluctuations and the increasing control of female fertility, evidently became secondary. The key variable that dominates the analysis of economic dynamics in the neoclassical growth theory along the lines of Solow (1956) is capital (or per capita capital). In Solow’s growth model, the role of population is minimal in the steady state: neither the level nor the growth rate of the steady-state per capita consumption has anything to do with the size of a population; only the steady-state per capita income level will be affected by the population growth rate. The growth pattern in the latter half of the twentieth century is markedly different. A key feature of our recent growth experience is the rapid innovation of new technologies. Modern growth theory has embraced the concept of increasing returns to explain such a unique growth pattern. However, various versions of the theory of increasing returns turn out to be necessarily linked to population. The hypothesis of learning by doing implies that growth in productivity is an increasing function of aggregate production, which is itself positively related to the size of population.