Isolated horizons [1], much like Killing horizons [2], were introduced in order to deal with the more practical problems involving black holes. Both formulations are local, in contrast with the global nature of event horizons [3]. However, isolated horizons, unlike Killing horizons, do not require a Killing vector field in their neighbourhood. Thus, isolated horizons are characterized by a weak...

Non-Hermitian Hamiltonians H 6= H possess the real (i.e., observable) spectra inside certain specific, “physical” domains of parameters D = D(H). In general, the determination of their “observability-horizon” boundaries ∂D is difficult. We list the pseudo-Hermitian real N by N matrix Hamiltonians for which the “prototype” horizons ∂D are defined by closed analytic formulae.

Recent studies of soil–landscape relationships in northeastern Patagonia identified fibrous-clay minerals in calcic and petrocalcic horizons developed on old fluvio-glacial plains called “Rodados Patagónicos” (RP). The objectives of this study were: i) to evaluate the occurrence of fibrous-clay minerals in the arid soil environment, and ii) to establish the relationship between the soil propert...

soils of the arid–semiarid karaj basin in north-central iran have formed on alluvium-colluvium derived from mixed calcareous-gypsiferous marls of miocene and basic igneous rocks of holocene age. in order to characterize and classify the soils and to determine the soil-landscape relationship in the area, sixteen pedons located on different physiographic positions have been described, sampled and...

From 1997 through 2007, the Horizons program conducted research to inform the care and support of children who had been orphaned and rendered vulnerable by acquired immunodeficiency syndrome in sub-Saharan Africa. Horizons conducted studies in Kenya, Malawi, Rwanda, South Africa, Uganda, Zambia, and Zimbabwe. Research included both diagnostic studies exploring the circumstances of families and ...

evaluating, and expanding innovative strategies for HIV prevention and care. Horizons developed and tested ways to optimize HIV prevention, care, and treatment programs; worked to reduce stigma and improve gender-biased behaviors; and greatly expanded knowledge about the best ways to support, protect, and treat children affected by HIV and AIDS. In all its projects, Horizons strengthened the ca...