Dromion solutions of noncommutative Davey-Stewartson equations

We consider a noncommutative version of the Davey-Stewartson equations and derive two families of quasideterminant solution via Darboux and binary Darboux transformations. These solutions can be verified by direct substitution. We then calculate the dromion solutions of the equations and obtain computer plots in a noncommutative setting.Comment: 23 pages, 6 figure

Feeding the rural tourism strategy? Food and notions of place and identity

The humble rural cuisine has now been thrust at the forefront of economic development strategies. This conceptual paper is a contribution to a growing critical awareness of the operations of the food industry and helps to foster a critical understanding of how, if at all, local food and its associated culture can help sustain rural tourism particularly and rural communities generally. It is inspired by literature about the international political economy of food and the many experiences of local food development, and is aware of the contrast between the structure of the industry and the hopes associated with its practice on the ground. The paper thus argues that, beyond the glamour and hype, there are those who gain, as well as those who lose, from the current food fad. While it explains the causes of the contemporary craze with food, the paper also interrogates the naı¨ve expectations often placed in food as a motor of rural development, and as the panacea for struggling rural communities. The empirical data on which this chapter is based are drawn from 18 short chapters explaining the history of various “traditional dishes” from the islands of the broad North Atlantic that feature in a recent food publication.peer-reviewe

Structural, physiognomic and above-ground biomass variation in savanna-forest transition zones on three continents - How different are co-occurring savanna and forest formations?

Through interpretations of remote-sensing data and/or theoretical propositions, the idea that forest and savanna represent "alternative stable states" is gaining increasing acceptance. Filling an observational gap, we present detailed stratified floristic and structural analyses for forest and savanna stands located mostly within zones of transition (where both vegetation types occur in close proximity) in Africa, South America and Australia. Woody plant leaf area index variation was related to tree canopy cover in a similar way for both savanna and forest with substantial overlap between the two vegetation types. As total woody plant canopy cover increased, so did the relative contribution of middle and lower strata of woody vegetation. Herbaceous layer cover declined as woody cover increased. This pattern of understorey grasses and herbs progressively replaced by shrubs as the canopy closes over was found for both savanna and forests and on all continents. Thus, once subordinate woody canopy layers are taken into account, a less marked transition in woody plant cover across the savanna-forest-species discontinuum is observed compared to that inferred when trees of a basal diameter > 0.1 m are considered in isolation. This is especially the case for shrub-dominated savannas and in taller savannas approaching canopy closure. An increased contribution of forest species to the total subordinate cover is also observed as savanna stand canopy closure occurs. Despite similarities in canopy-cover characteristics, woody vegetation in Africa and Australia attained greater heights and stored a greater amount of above-ground biomass than in South America. Up to three times as much above-ground biomass is stored in forests compared to savannas under equivalent climatic conditions. Savanna-forest transition zones were also found to typically occur at higher precipitation regimes for South America than for Africa. Nevertheless, consistent across all three continents coexistence was found to be confined to a well-defined edaphic-climate envelope with soil and climate the key determinants of the relative location of forest and savanna stands. Moreover, when considered in conjunction with the appropriate water availability metrics, it emerges that soil exchangeable cations exert considerable control on woody canopy-cover extent as measured in our pan-continental (forest + savanna) data set. Taken together these observations do not lend support to the notion of alternate stable states mediated through fire feedbacks as the prime force shaping the distribution of the two dominant vegetation types of the tropical lands