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First-principles methods are used to investigate the self-interstitial and its aggregates in diamond. The experimental assignment of the spin-one R2 EPR center to the single interstitial has been questioned because of the small fine structure term observed. We calculate the spin-spin interaction tensor for the three interstitial defects, I 001 1 , I NN 2 and I 3 and compare with the experimental D-tensors. The results give support for the assignments of the single and di-interstitial to microscopic models and allow us to conclusively identify a recently observed EPR center, O3, with I 3. This identification, in turn, suggests a low energy structure for I 4 and a generic model for an extended defect called the platelet. We also determine the optical properties of I 001 1 as well as its piezospectroscopic or stress tensor and find these to be in agreement with experiment. Several multi-interstitial defects are found to possess different structural forms which may coexist. We propose that a different form of the charged I 2 defect gives rise to the 3H optical peak. Several structures of the platelet are considered and we find that the lowest energy model is consistent with microscopic and infra-red studies.

"This article applies the theory of structuration to international labor migration using case study material from the Philippines. It first provides a brief review of the functional and structural approaches to understanding labor migration and the theoretical impasse that has been created between them. It then reviews several attempts to resolve this impasse, including systems and networks approaches; these solutions are rejected on theoretical and empirical grounds. We suggest that migrant institutions may be a more appropriate mid-level concept than households or social networks to articulate various levels of analysis. We develop this concept in the context of the structuration theory of Anthony Giddens and attempt to apply this to the Philippines, concluding that this framework is eminently suited for further research on international labor migration."

We distinguish three mechanisms of doping graphene. Density functional theory is used to show that electronegative molecule like F4-TCNQ and electropositive metals like K dope graphene p-and n-type respectively. These dopants are expected to lead to a decrease in carrier mobility arising from Coulomb scattering but without any hysteresis effects. Secondly, a novel doping mechanism is exhibited by Au which dopes bilayer graphene but not single layer. Thirdly, electrochemical doping is effected by redox reactions and can result in p-doping by humid atmospheres and n-doping by NH 3 and toluene.