Analyzing large scale exchange networks

Exchange theories or their implementations in algorithms have limited utility because they can be applied only to quite small networks. They cannot be applied to larger networks until that size limit is removed. Domain Analysis cuts networks into smaller pieces at the boundaries of strong power domains. Domain Analysis identifies strong power and breaks, and distinguishes domains that function exactly as they would were they free-standing, and components that do not. Support for the finding of breaks and the distinction between domains and components are obtained using both experimental data and simulations based on X-Net. To illustrate the use of Domain Analysis, it is applied to find the incidence of strong power in large exchange networks. The application shows that the incidence of strong power decreases as network density increases, and that strong power occurs only infrequently in dense networks. We conclude by calling for ever more general analytic procedures.     

An avian urban morphotype: how the city environment shapes great tit morphology at different life stages

Urban Ecosystems - Urbanization is a worldwide phenomenon associated with tremendous modifications of natural habitats. Understanding how city dwelling species are affected by those changes is...     

A cross-national study on adolescent substance use: Intentions,peer substance use,and parent-adolescent communication

This longitudinal two-wave cross-national study investigated whether intentions, friends' substance use, and parent-adolescent substance-use specific communication predict adolescent alcohol and cannabis use 1 year later, while estimating reversed links. The temporal order between these two substances was also examined. We used multi-group cross-lagged panel modeling on data from 2 ethnically and socioeconomically diverse samples: Sint Maarten (N = 350; M_age = 14.19) and the Netherlands (N = 602; M_age = 13.50). Results showed that in the Netherlands, cannabis use predicts more subsequent problems (alcohol use, intention to use cannabis, and affiliation with cannabis-using friends). But for Sint Maarten, alcohol use predicts more subsequent problems (cannabis use, intention to use alcohol, and affiliation with alcohol-using friends). These opposing results demonstrate that caution is warranted when generalizing results across countries.     

Precautionary Saving,Credit Constraints,and Irreversible Investment: Theory and Evidence From Serniarid India

This article investigates the extent to which poor households are discouraged from making a non-divisible but profitable investment. Using data on irrigation wells in India, we estimate the parameters of a structural model of irreversible investment. Results show that poor farmers fail to undertake a profitable investment that they could, in principle, self-finance because the nondivisibility of the investment puts it out of their reach. Irreversibility constitutes an additional disincentive to invest. Simulations show that the availability of credit can dramatically increase investment in irrigation and that interest-rate subsidization has little impact.     

Unemployment in a Bankruptcy Constrained Model

This paper proposes a model of labour demand based on a bankruptcy constrained firm. This implies two different regimes for the process generating labour demand: one when this bankruptcy constraint is not binding and one when it is. The same applies to unemployment. This unemployment model is applied to U.S. quarterly data, where account is being taken of the two regimes by dummy variables based on the turning points of the NBER business indicator. It appears that the variables affecting U.S. unemployment in the respective regimes are also the ones predicted by our theoretical model.