52,741 research outputs found
"Opere di Origene"
No full textEdizione bilingue greco-latina, con traduzione italiana a fronte, introduzione e commento degli "Opera Omnia" di Origene. La collana, diretta da Manlio Simonetti (Professore emerito, Università di Roma "La Sapienza") e Lorenzo Perrone (Università di Bologna), è espressione del Gruppo italiano di ricerca su Origene e la tradizione alessandrina. Nel 2004 è stato pubblicato il seguente volume: "Commento a Matteo. Series/1", a cura di G. Bendinelli, R. Scognamiglio, M.I. Danieli, pp. 447
Harmonicity of unit vector fields with respect to Riemannian g-natural metrics
No full textAbstractLet (M,g) be a compact Riemannian manifold and T1M its unit tangent sphere bundle. Unit vector fields defining harmonic maps from (M,g) to (T1M,g˜s), g˜s being the Sasaki metric on T1M, have been extensively studied. The Sasaki metric, and other well known Riemannian metrics on T1M, are particular examples of g-natural metrics. We equip T1M with an arbitrary Riemannian g-natural metric G˜, and investigate the harmonicity of a unit vector field V of M, thought as a map from (M,g) to (T1M,G˜). We then apply this study to characterize unit Killing vector fields and to investigate harmonicity properties of the Reeb vector field of a contact metric manifold
«Simmetrie sarcastiche». Esili e migrazioni nella letteratura contemporanea di lingua tedesca degli scrittori di origine romena (C.D.Florescu e C.-F.Banciu)
No full textHarmonic sections of tangent bundles equipped with Riemannian -natural metrics
No full textLet be a Riemannian manifold. When is compact and the tangent bundle is equipped with the Sasaki metric , parallel vector fields are the only harmonic maps from to . The Sasaki metric, and other well-known Riemannian metrics on , are particular examples of -natural metrics. We equip with an arbitrary -natural Riemannian metric , and investigate the harmonicity properties of a vector field of , thought as a map from to . We then apply this study to the Reeb vector field and, in particular, to Hopf vector fields on odd-dimensional spheres
Some examples of harmonic maps for -natural metrics
No full textWe produce new examples of harmonic maps, having as source manifold a space (M,g) of constant sectional curvature and as target manifold its tangent bundle TM, equipped with a suitable Riemannian g-natural metric. In particular, we determine a family of Riemannian g-natural metrics G on TS^2, with respect to which all conformal gradient vector fields define harmonic maps from S^2 into (TS^2,G), where S^2 denotes the unit sphere of dimension two
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