A Amazônia e os desafios de sua ocupação.

bitstream/item/32655/1/AmazoniaDesafiosOcupacao.pdfDisponível também on-line

Sim, ainda temos analfabetos.

bitstream/item/103595/1/7255.pd

Características da agricultura indígena e sua influência na produção familiar da Amazônia.

bitstream/item/63507/1/Oriental-Doc105.PD

Amazônia: laboratório do mundo.

bitstream/item/103588/1/7256.pd

A hora e a vez da mandioca.

bitstream/item/49434/1/SP7254.pdfDisponível também on-line

O sapo e o meio ambiente.

bitstream/item/131997/1/Sapo.pd

Polarons in Carbon Nanotubes

We use ab initio total-energy calculations to predict the existence of polarons in semiconducting carbon nanotubes (CNTs). We find that the CNTs' band edge energies vary linearly and the elastic energy increases quadratically with both radial and with axial distortions, leading to the spontaneous formation of polarons. Using a continuum model parametrized by the ab initio calculations, we estimate electron and hole polaron lengths, energies and effective masses and analyze their complex dependence on CNT geometry. Implications of polaron effects on recently observed electro- and opto-mechanical behavior of CNTs are discussed.Comment: Revtex preprint format, 12 pages, 2 eps figures, source in LaTeX. Accepted for publication in Physical Review Letter