Dynamics of Individual Specialization and Global Diversification in Communities

We discuss a model of an economic community consisting of $N$ interacting agents. The state of each agent at any time is characterized, in general, by a mixed strategy profile drawn from a space of $s$ pure strategies. The community evolves as agents update their strategy profiles in response to payoffs received from other agents. The evolution equation is a generalization of the replicator equation. We argue that when $N$ is sufficiently large and the payoff matrix elements satisfy suitable inequalities, the community evolves to retain the full diversity of available strategies even as individual agents specialize to pure strategies.Comment: 13 pages, Late

The network structure of city-firm relations

How are economic activities linked to geographic locations? To answer this question, we use a data-driven approach that builds on the information about location, ownership and economic activities of the world's 3,000 largest firms and their almost one million subsidiaries. From this information we generate a bipartite network of cities linked to economic activities. Analysing the structure of this network, we find striking similarities with nested networks observed in ecology, where links represent mutualistic interactions between species. This motivates us to apply ecological indicators to identify the unbalanced deployment of economic activities. Such deployment can lead to an over-representation of specific economic sectors in a given city, and poses a significant thread for the city's future especially in times when the over-represented activities face economic uncertainties. If we compare our analysis with external rankings about the quality of life in a city, we find that the nested structure of the city-firm network also reflects such information about the quality of life, which can usually be assessed only via dedicated survey-based indicators.Comment: 12 pages, 4 figure

Evolution and Biogeography of Haemonchus contortus: Linking Faunal Dynamics in Space and Time

History is the foundation that informs about the nuances of faunal assembly that are essential in understanding the dynamic nature of the host-parasite interface. All of our knowledge begins and ends with evolution, ecology and biogeography, as these interacting facets determine the history of biodiverse systems. These components, relating to Haemonchus, can inform about the complex history of geographical distribution, host association and the intricacies of host-parasite associations that are played out in physiological and behavioural processes that influence the potential for disease and our capacity for effective control in a rapidly changing world. Origins and evolutionary diversification among species of the genus Haemonchus and Hae- monchus contortus occurred in a complex crucible defined by shifts in environmental structure emerging from cycles of climate change and ecological perturbation during the late Tertiary and through the Quaternary. A history of sequential host colonization associated with waves of dispersal bringing assemblages of ungulates from Eurasia into Africa and processes emerging from ecosystems in collision and faunal turnover defined the arena for radiation among 12 recognized species of Haemonchus. Among congeners, the host range for H. contortus is exceptionally broad, including species among artiodactyls of 40 genera representing 5 families (and within 12 tribes of Bovi- dae). Broad host range is dramatically reflected in the degree to which translocation, introduction and invasion with host switching, has characterized an expanding distribution over time in North America, South America, southern Eurasia, Australia and New Zealand, coincidental with agriculture, husbandry and global colonization by human populations driven particularly by European exploration after the 1500s. African origins in xeric to mesic habitats of the African savannah suggest that historical constraints linked to ecological adaptations (tolerances and developmental thresholds defined by temperature and humidity for larval stages) will be substantial determinants in the potential outcomes for widespread geographical and host colonization which are predicted to unfold over the coming century. Insights about deeper evolutionary events, ecology and biogeography are critical as understanding history informs us about the possible range of responses in complex systems under new regimes of environmental forcing, especially, in this case, ecological perturbation linked to climate change. A deeper history of perturbation is relevant in understanding contemporary systems that are now strongly structured by events of invasion and colonization. The relaxation of abiotic and biotic controls on the occurrence of H. contortus, coincidental with inception and dissemination of anthelmintic resistance may be synergistic, serving to exacerbate challenges to control parasites or to limit the socioeconomic impacts of infection that can influence food security and availability. Studies of haemonchine nematodes contribute directly to an expanding model about the nature of diversity and the evolutionary trajectories for faunal assembly among complex hosteparasite systems across considerable spatial and temporal scales

Cultural Diversity, European Integration and the Welfare State

According to the “Neoclassical” approach, stemming from the Tiebout model, the main advantage of federalism lies in the possibility that individuals with similar tastes, including those related to risk-aversion and the provision of public goods, can cluster in the same jurisdictions. The starting point of this paper is a criticism of this approach. While the main advantage of federalism is related to the possibility of clustering heterogeneous individuals, the assumption of costless movement from one State to the other implicitly implies that individuals are homogeneous in some of other important characteristics. For instance, individuals, facing low mobility costs must have very minor cultural and linguistic differences. This hypothesis may approximate the U. S. situation but clashes with the case of European Union. Since Cultural-linguistic standardisation and the social protection can be regarded as two alternative insurance devices (one increasing the probability of alternative employment and the second providing some assistance in case of dismissal from the present employment) a culturally diverse Europe must necessary rely more on the Welfare State than the United States. The comparison with the U. S. clarifies the paradoxical problem of European integration. On the one hand, social protection is more necessary when cultural-linguistic differences make it expensive to cultural standardisation as a substitute for it. On the other hand, social insurance among different regions is more unlikely to be accepted when these cultural differences prevail. We argue that a possible way out of this dilemma is a system of mutual insurance among the European national welfare systems

Managing the KM Trade-Off: Knowledge Centralization versus Distribution

KM is more an archipelago of theories and practices rather than a monolithic approach. We propose a conceptual map that organizes some major approaches to KM according to their assumptions on the nature of knowledge. The paper introduces the two major views on knowledge ­objectivist, subjectivist - and explodes each of them into two major approaches to KM: knowledge as a market, and knowledge as intellectual capital (the objectivistic perspective); knowledge as mental models, and knowledge as practice (the subjectivist perspective). We argue that the dichotomy between objective and subjective approaches is intrinsic to KM within complex organizations, as each side of the dichotomy responds to different, and often conflicting, needs: on the one hand, the need to maximize the value of knowledge through its replication; on the other hand, the need to keep knowledge appropriate to an increasingly complex and changing environment. Moreover, as a proposal for a deeper discussion, such trade-off will be suggested as the origin of other relevant KM related trade-offs that will be listed. Managing these trade-offs will be proposed as a main challenge of KM

Commercialization of Holidays in the Protected Natural Areas - Form of the Sustainable Development in Tourism

Sustainable development of tourism in the protected areas should be regarded as a continuous improvement process in the management quality of the protected natural areas that are included in the tourist circuit as well as of the ecological tourism products, merchandised by the travel agencies. In Romania, the best-represented types of protected natural areas are the biosphere reservations, our country having three of these areas, followed by 13 national parks and 14 natural parks. The total surface of the protected areas in Romania is of approximately 1.9 million hectares, which represents almost 8% from the total surface of the country. Regarding the structure, we notice the typological diversity and the alignment to the international standards and IUCN (International Union for Conservation of Nature) category system. The fieldwork done at the 2009 (March 19th – 22nd) Romanian Tourism Fair has shown the fact that, even if they recognize the benefits of the vacations in protected areas, the travel agencies’ preoccupations of creating specialized packages have been reduced, displaying a poor offer, or a special offer created at the tourists’ request. The research was realized within the project called “Dynamics of the implementation of community policies in the valuing of the Romanian protected areas through tourism and designing architecture of integrated management for them”. Consequently, considering, on the one hand, the advantages of the vacations in protected areas and, on the other hand, the tourists’ increasing interest towards this type of vacation is necessary in the future, a more intense involvement of the travel agencies, but also of the protected natural areas administrations in their promotion, fructification and sustainable development.natural protected areas, management, sustainable development, commercialization of tourist products, tourism agencies

Explaining microbial population genomics through phage predation

The remarkable diversity of genes within the pool of prokaryotic genomes belonging to the same species or pan-genome is difficult to reconcile with the widely accepted paradigm which asserts that periodic selection within bacterial populations would regularly purge genomic diversity by clonal replacement. Recent evidence from metagenomics indicates that even within a single sample a large diversity of genomes can be present for a single species. We have found that much of the differential gene content affects regions that are potential phage recognition targets. We therefore propose the operation of Constant-Diversity dynamics in which the diversity of prokaryotic populations is preserved by phage predation. We provide supporting evidence for this model from metagenomics, mathematical analysis and computer simulations. Periodic selection and phage predation dynamics are not mutually exclusive; we compare their predictions to indicate under which ecological circumstances each dynamics could predominate