Developmental behaviors: delayed appearance in monkeys asphyxiated at birth

In "Developmental behaviors: delayed appearance in monkeys asphyxiated at birth" by J. A. Sechzer et al. (19 Mar., p. 1173), the last two lines of column 1 and the first five lines of column 2, page 1175, should read "Deficits in learning and memory (10, 11) when compared with the establishment of these developmental behaviors (although significantly delayed) suggest that brain damage by neonatal asphyxia can result in a degree of dissociation..."     

Water transfer from agriculture to urban uses: lessons learned, with policy considerations

This paper sets forth the accomplishments to date of the international collaborative study program on efficient and equitable transfer of water from agriculture to other uses. The research consists of several components. First a bibliographical review was prepared of literature available on the practice of inter-sector water transfer. Second, nine case studies have been prepared that illustrate inter-sector water transfer under a variety of physical and economic and political environments. Third, a framework has been developed for characterizing and comparing water transfer options and compensation among case studies. We discuss the pricing of irrigation water in determining compensation. We develop a decision tree that traces the paths to the various sector water transfer options. Finally, we discuss water transfer policy options with specific reference to Taiwan, though they have more general relevance. Three options are identified which reflect different objectives for government intervention.     

Observations on the structure and osmotic potentials of parenchyma associated with the internal phloem of potato tubers

The structure and osmotic potentials of parenchyma cells associated with internal phloem of growing, dormant, and sprouting potato tubers (Solanum tuberosum L. cv. Irish Cobbler) were studied. Companion cells, specialized parenchyma cells, and storage parenchyma cells were recognizable by differences in structural characteristics. Companion cells were usually densely cytoplasmic with numerous large mitochondria and plastids with little or no starch. The specialized parenchyma cells which surrounded groups of sieve tubes and companion cells had numerous vacuoles of various size, small mitochondria, plastids with very little or no starch, and protein inclusions. Storage parenchyma cells had amyloplasts with very large starch grains, a large central vacuole with osmiophilic inclusions, and few organelles in a peripheral cytoplasm. The osmotic potentials of specialized parenchyma cells and storage parenchyma cells were similar and did not vary regardless of whether the tubers were growing, dormant, or sprouting.     

A unified capture-recapture framework

This article develops a hierarchical framework for capture-recapture data that separates the capture process from the demographic processes of interest, such as birth and survival. This allows users to parameterize in terms of meaningful demographic parameters. The framework is very flexible with many of the current capture-recapture models included as special cases. The hierarchical nature of the model allows natural expression of relationships, both between parameters and between parameters and the realization of random variables, such as population size. Previously, many of these relationships, such as density dependence have been unable to be explored using capture-recapture data. Density dependence, where survival and birth rates depend on the population size, is an interesting special case. We fit a density-dependent model to male Gonodontis bidentata data and report evidence of negative density dependence in percapita birth rates and weak evidence of negative density dependence in survival.