SINGLE SPECIES VERSUS MULTIPLE SPECIES MODELS: THE ECONOMIC IMPLICATIONS

Ecologists frequently note the importance of modelling entire ecosystems rather than single species, but most bioeconomic models in the current literature focus on a single species. While the mathematical difficulty of multiple species may quickly become overwhelming, sometimes making the single species option necessary, it is important to recognise the significance of the single species assumption to the model results. In this paper, the authors address the economic significance of this assumption through the development of a multiple species model and demonstrate the importance of interrelationships and economic values to the survival of endangered species.Resource /Energy Economics and Policy,

Transferring Your Farm Business to the Next Generation

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Results of the 1976 southern California pismo clam census

A Pismo clam, Tivela stultorum, census was conducted in January 1976 on selected southern California beaches. Effort and catch information was collected through clamer interviews. Estimates for January 17 on beaches sampled were 3,296 clammer-hours, 2,170 clammers, and 10,739 legal clams (4.5 inches or larger) harvested. Clams were collected for age and growth studies. Samples of clams from the Long Beach to Newport Beach pier area demonstrate the fastest growth rates of any Pismo clams reported in the literature. Clams begin to be recruited to the fishery at age 40 months. (14pp.) The 1974 year class was the largest on beaches sampled. Recruitment to the fishery will be poor for the 1976-77 and 1977-78 seasons and clamming will be dependent on large older clams

Administrative Law—Workmen’s Compensation— Accidental Injury as a Question of Fact

Broderick v. Liebmann Breweries, 277 App. Div. 422, 100 N. Y. S. 837 (3d Dept. 1950

Deformation Behavior of Al/a-Si Core-shell Nanostructures

Al/a-Si core-shell nanostructures (CSNs), consisting of a hemispherical Al core surrounded by a hard shell of a-Si, have been shown to display unusual mechanical behavior in response to compression loading. Most notably, these nanostructures exhibit substantial deformation recovery, even when loaded much beyond the elastic limit. Nanoindentation measurements revealed a unique mechanical response characterized by discontinuous signatures in the load-displacement data. In conjunction with the indentation signatures, nearly complete deformation recovery is observed. This behavior is attributed to dislocation nucleation and annihilation events enabled by the 3-dimensional confinement of the Al core. As the core confinement is reduced, either through an increase in confined core volume or a change in the geometrical confinement, the indentation signatures and deformation resistance are significantly reduced. Complimentary molecular dynamics simulations show that a substantial amount of dislocation egression occurs in the core of CSNs during unloading as dislocations annihilate at the core/shell interface. Smaller core diameters correlate with the development of a larger back-stress within the core during unloading, which further correlates with improved dislocation annihilation after unloading. Furthermore, dislocations nucleated in the core of core-shell nanorods are not as effectively removed as compared to CSNs. Nanostructure-textured surfaces (NSTSs) composed of Al/a-Si CSNs have improved tribological properties compared surfaces patterned with Al nanodots and a flat (100) Si surface. NSTSs have a coefficient of friction (COF) as low as 0.015, exhibit low adhesion with adhesion forces on the order of less than 1 μN, and are highly deformation resistant, with no apparent surface deformation after nanoscratch testing, even at contact forces up to 8000 μN. In comparison, (100) Si has substantially higher adhesion and COF (~10 μN and ~0.062, respectively), while the Al nanodots have both higher friction (COF ~0.044) and are deformed when subjected to contact loads as low as 250 μN. This integrated experimental and computational study elucidates the mechanisms that contribute to the novel properties of Al/a-Si CSNs and characterizes the tribological properties of surface composed of these nanostructures, which provides a foundation for the rational design of novel technologies based on CSNs