High-resolution economic evaluation of black walnut alley cropping against the maize-soybean rotation in the Midwest, USA

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Safe design of cooled tubular reactors for exothermic, multiple reactions; parallel reactions—II: The design and operation of an ethylene oxide reactor

In part I a model and criteria have been developed for the safe design and operation of cooled tubular reactors for multiple reactions of the parallel type. In this Part II the model is extended to parallel reactions with an arbitrary stoichiometry. The results are applied to the industrial process of the ethylene oxidation with pure oxygen. It is shown that the criteria derived in part I lead to useful guidelines for the design and operation of an ethylene oxide reactor

Safe design of cooled tubular reactors for exothermic, multiple reactions; parallel reactions—I: Development of criteria

Previously reported design criteria for cooled tubular reactors are based on the prevention of reactor temperature run away and were developed for single reactions only. In this paper it is argued that such criteri a should be based on the reactor selectivity, from which eventually a maximum allowable temperature can be derived. To this end and for the pseudo-homogeneous, one dimensional model of a cooled tubular reactor in which two parallel, irreversible first order exothermic reactions are carried out, two criteria are developed for the safe design and operation of the reactor. The criteria enable us to choose tube diameters and operating conditions, which are safe in view of the derived selectivity and of possible runaway as well. The method outlined can be used in the initial design stage and requires kinetic information on both the desired and the undesired reaction

A "Double Dividend", After All?

The consensus view among economists seems to be that a green tax reform is unlikely to be associated with a "double dividend" (Bovenberg 1998). However, the results derived in the present paper suggest that this view needs to be qualified. We demonstrate that a green tax reform is likely to be associated with a significant "double dividend" if the government prior to taking the environmental aspect into account has adopted a proportional tax structure due to the administrative costs involved in differentiating commodity tax rates, and if the green tax reform stimulates the labour supply and has desirable income distributional effects.Optimal taxation, externalities, administrative costs, green tax reform, double dividend

Growth of ICT and ICT for Development: Realities of the Myths of the Indian Experience

ICT, growth, development, India, software exports

Heritability of geographic range sizes revisited : a reply to Hunt et al.

Hunt et al.(2005) revisit the issue of range size heritability following our recent article on this topic (Webb and Gaston 2003). In that article, we showed that the range sizes of closely related species tend to be highly dissimilar and argued that this provided evidence to counter Jablonski’s (1987) claim that range size was a heritable species-level trait. Hunt et al. do not dispute the fact that the species pairs that we examined have highly asymmetric range sizes; however, they claim that the statistical technique that we used to assess the significance of this asymmetry is flawed. They then return to correlation analyses to support their assertion that range size is indeed heritable. While some points of technical interest are raised, we disagree with their conclusions and feel that the analyses that they present provide little insight into the ultimate questions

Business dynamics with scenarios on Dutch agriculture and its instistutional arrangements

This paper investigates the developments in the Dutch Agri-food Innovation System. Main components of the system are agriculture and agribusiness, the promotion of interests in the lobby system and the knowledge system. Each has its own dynamics but they are until now tied together by institutional arrangements. Based on a historical description we formulate a simple business dynamics model. The robustness of the system is investigated by a scenario analysis. Results have been checked by interviews with experts

On the heritability of geographic range sizes

Within taxonomic groups, most species are restricted in their geographic range sizes, with only a few being widespread. The possibility that species-level selection on range sizes contributes to the characteristic form of such speciesrange size distributions has previously been raised. This would require that closely related species have similar range sizes, an indication of "heritability" of range sizes at the species level. Support for this view came from a positive correlation between the range sizes of closely related pairs of fossil mollusc species. We extend this analysis by considering the relationship between the geographic range sizes of 103 pairs of contemporary avian sister species. Range sizes in these sister species show no evidence of being more similar to each other than expected by chance. A reassessment of the mollusc data also suggests that the high correlation was probably overestimated because of the skewed nature of range size data. The fact that sister species tend to have similar life histories and ecologies suggests that any relationship between range sizes and biology is likely to be complicated and will be influenced by historical factors, such as mode of speciation and postspeciation range size transformations

Occupancy, spatial variance, and the abundance of species

A notable and consistent ecological observation known for a long time is that spatial variance in the abundance of a species increases with its mean abundance and that this relationship typically conforms well to a simple power law (Taylor 1961). Indeed, such models can be used at a spectrum of spatial scales to describe spatial variance in the abundance of a single species at different times or in different regions and of different species across the same set of areas (Taylor et al. 1978; Taylor and Woiwod 1982)