Conformations of poly{G}-poly{C} π stacks with high hole mobility

Charge transfer properties of DNA depend strongly on the π stack conformation. In the present paper, we identify conformations of homogeneous poly-{G}-poly-{C} stacks that should exhibit high charge mobility. Two different computational approaches were applied. First, we calculated the electronic coupling squared, V2, between adjacent base pairs for all 1 ps snapshots extracted from 15 ns molecular dynamics trajectory of the duplex G15. The average value of the coupling squared 〈 V2 〉 is found to be 0.0065 eV2. Then we analyze the base-pair and step parameters of the configurations in which V2 is at least an order of magnitude larger than 〈 V2 〉. To obtain more consistent data, ∼65 000 configurations of the (G:C)2 stack were built using systematic screening of the step parameters shift, slide, and twist. We show that undertwisted structures (twist<20°) are of special interest, because the π stack conformations with strong electronic couplings are found for a wide range of slide and shift. Although effective hole transfer can also occur in configurations with twist=30° and 35°, large mutual displacements of neighboring base pairs are required for that. Overtwisted conformation (twist38°) seems to be of limited interest in the context of effective hole transfer. The results may be helpful in the search for DNA based elements for nanoelectronics

Castes, Social Mobility and Politics in Goa

While the colonial policies and the missionary activities dented the caste system by playing upon the caste rivalries to divide and rule, the post-independence Indian democracy transformed the traditional castes into valuable vote-banks that have permitted non-brahmin castes to achieve political leadership in several States, particularly following the politics of reservation recommended by the Mandal Commission in 1980s.

spotlight europe #2012/04, June 2012: Can mobility offset unemployment?

Almost a quarter of the young people in the EU are unemployed. And once again it is the crisis-ridden states that have been hit hardest. But in other countries such as France, Sweden, and Luxembourg, younger members of the workforce, far more than their older counterparts, are also finding it difficult to get a job. Freedom of movement within the EU could help to provide them with new opportunities. All that is needed is the right kind of support.

spotlight europe #2012/04, Juni 2012: Mobil statt arbeitslos? = Can mobility offset unemployment?

No abstract.