Using the theory of Weyl structures, we give a natural generalization of the notion of essential conformal structures and conformal Killing fields to arbitrary parabolic geometries. We show that a parabolic structure is inessential whenever the automorphism group acts properly on the base space. As a corollary of the generalized Ferrand–Obata theorem proved by C. Frances, this proves a generali...

The map named Carta Geographica de Projecçaõ Espherica Orthogonal da Nova Lusitania ou America Portugueza e Estado do Brazil from 1798, together with its 1795 (?), 1797 and 1803 versions, is undoubtedly one of the cartographic monuments developed by Portuguese cartography late eighteenth century. Its organizer was geographer, astronomer, frigate captain Antonio Pires Silva Pontes Leme, who reli...

ABS’I’RACI’. Pseudo-Sasakian manifolds M(U,E,,,g) endowed wlth a contact conformal connection are defined. It is proved tlat sucl manifolds are space forms M(K),K < O, and somo remarkable properttos of the 1,ie algebra of infinitesimal transformatton. of the principal vector feld U on M are discussed. Properties of tle leaves of a co-tsotroptc foliation on I’! and properties of the tangent bund...

Infinitesimal conformal transformations of IRn are always polynomial and finitely generated when n > 2. Here we prove that the Lie algebra of infinitesimal conformal polynomial transformations over IRn, n ≥ 2, is maximal in the Lie algebra of polynomial vector fields. When n is greater than 2 and p, q are such that p+ q = n, this implies the maximality of an embedding of so(p + 1, q + 1, IR) in...

conclusion despite multiple exposures, ed control is more effective if wss is performed using apmdr in the aec mode. results using apmdr, the mean number of exposures was 6.1 for ap and 6.5 for lat projections. lat projections required more exposures (6.55%) than ap projections. the mean ed was 0.6276 msv (ap) and 0.6716 msv (lat). the mean ed for lat projections was 0.6061 msv in automatic exp...