David Hartley's psychobiological associationism and the legacy of Aristotle

The idea that there are certain "laws" of learning (similarity, contrast, contiguity) can be traced to Aristotle. He maintained that external stimuli cause small movements in the vessels to the dominant heart, the vestiges of which can be linked to one another. Aristotle's laws of learning were incorporated into the writings of Hobbes, Locke, and Berkeley, men who said nothing about the physiological correlates of mental associations. This left the door open for David Hartley to combine mental associationism with the Newtonian idea that sensations can cause minute particle vibrations in the nerves. Hartley's amalgam of psychology, philosophy, and neurology was first presented in 1746, as a "trial balloon" at the end a little-known monograph on a treatment for kidney stones. It was repeated three years later in his better-known Observations on Man. In many ways, modern psychobiological connectionism can be traced back to Hartley's Conjectures of 1746, in which Aristotle's original thoughts were modified with then current ideas about functions of the mind and the nervous system.     

Alternative explanations of the dependence of the density of centers on the density of population

ABSTRACT. The paper is devoted to modeling the relationship between the density of service centers and the density of population (or on the density of demand). Several models lead to an exponential function with the exponent equal to ⅔. For a number of real systems of centers, the power is considerably different from ⅔ (more often it is nearer to 1). I describe a series of models that explain this difference.     

Peace Protest and Policy

The tremendous fluctuations in public mobilization against United States nuclear weapons policy, a relatively stable policy over four decades, present a difficult riddle to social scientists. Since the dawn of the nuclear age small groups of activists have consistently protested both the content of United States national security policy and the process by which it is made. Only occasionally, however, has this protest spread beyond a handful of relatively marginal groups, generated substantial public support, and reached mainstream political institutions. This article examines the political cycles of peace movement engagement and quiescence, and their relation to external political context, particularly public policy. I begin with a brief review of the relevant literature on the origins of the movements, noting parallels in the study of interest groups. Building on recent literature on political opportunity structure. I suggest a theoretical framework which emphasizes the interaction between activists choices and political context. I then describe the cycles of peace movement activism and quiescence on nuclear weapons issues in the United States using mass media sources to delineate periods of mobilization. I outline a number of policy variables which may help explain protest mobilization. My conclusions address the importance of policy and political context in explaining movement cycles and the potential influence of protest movements on policy.     

Revegetated Sand Mining Areas,Swamp Wallabies and Remote Sensing: North Stradbroke Island,Queensland

Mining of mineral sands has taken place on North Stradbroke Island for over 40 years. Revegetation of mined areas creates a mosaic of seral classes. For a mine site in the northwest of the island, Landsat Thematic Mapper data were used successfully to map the distribution of seven seral classes resulting from mining rehabilitation. Faecal pellet counts were used to assess usage of these areas and surrounding natural forest by swamp wallabies, Wallabia bicolor. Results indicated that revegetated sites from 2 to 4 years in age were heavily used by wallabies. Older revegetated sites, dominated by senile Acacia cunninghamii, and offering little or no forage, were avoided. Swamp wallabies used revegetated sites for night-time feeding sessions and rested, during the day, in surrounding eucalypt forest.     

The Sky Canopy Gap Irradiance (SCANGIR) Model: a technique for the estimation of ‘effective gap’ solar radiation regimes in closed-canopy forests

There is now widespread consensus among researchers that treefall gaps play a key role in the structure and function of closed-canopy forests, such as rain forests, with virtually all canopy tree species requiring growth in a gap to reach maturity. Until recently many believed that latitude and the size of treefall gaps were the main factors determining the availability of solar radiation in gaps and associated microclimates and vegetation dynamics. However, if solar radiation availability is the main limiting resource in such forests, then studies of gap dynamics need to take into account the other factors affecting the penetration and distribution of direct and diffuse irradiance within gaps. As a consequence, this is the first attempt to develop a universal model for the estimation of ‘effective gap’ solar radiation regimes that, along with latitude and gap size, incorporates factors such as slope angle, slope aspect, height of surrounding vegetation, sky conditions and daily and seasonal variation in the position of the sun. Results of three computer simulations are presented to demonstrate how latitude, topography and sky conditions affect solar radiation availability beneath circular canopy gaps of various configurations. Finally, the implications of these simulations for forest regeneration, reforestation and forest management are discussed.     

COPPER AND BARIUM AS DIETARY DISCRIMINANTS: THE EFFECTS OF DIAGENESIS

In skeletons excavated from Woodland sites, copper and barium levels are found to have been contaminated by influx from the soil environment. Electron microprobe scans for both elements show build-up along the outer surface of femur cross sections. Elemental levels for Cu and Ba are lower in the femur or fibula than in the more porous rib. The distribution of Cu in the immediately surrounding soil is highly anisotropic. These observations indicate that Cu and Ba should not be used for dietary inferences about ancient populations without independent evidence that diagenesis is not important.     

The direction of migration: a dynamic general equilibrium model

A two-sector dynamic general equilibrium model is developed "to investigate the direction of migration in response to differing demographic and consumption demand behavior, as well as variations in production conditions." The model, which involves a rural sector and an urban sector, incorporates "returns to scale and the natural rate of sectoral population growth as important determinants of the direction of migration, in addition to price and income elasticities, and the sectoral technical change rate with which...previous studies dealt."