Results 1  10
of
141,209
Brain magnetic resonance imaging with contrast dependent on blood oxygenation.
 Proc. Natl. Acad. Sci. USA
, 1990
"... ABSTRACT Paramagnetic deoxyhemoglobin in venous blood is a naturally occurring contrast agent for magnetic resonance imaging (MRI). By accentuating the effects of this agent through the use of gradientecho techniques in high fields, we demonstrate in vivo images of brain microvasculature with imag ..."
Abstract

Cited by 648 (1 self)
 Add to MetaCart
ABSTRACT Paramagnetic deoxyhemoglobin in venous blood is a naturally occurring contrast agent for magnetic resonance imaging (MRI). By accentuating the effects of this agent through the use of gradientecho techniques in high fields, we demonstrate in vivo images of brain microvasculature
Magnetic flows on homogeneous spaces
, 2008
"... We consider magnetic geodesic flows of the normal metrics on a class of homogeneous spaces, in particular (co)adjoint orbits of compact Lie groups. We give the proof of the noncommutative integrability of flows and show, in addition, for the case of (co)adjoint orbits, the usual Liouville integrabi ..."
Abstract

Cited by 6 (2 self)
 Add to MetaCart
We consider magnetic geodesic flows of the normal metrics on a class of homogeneous spaces, in particular (co)adjoint orbits of compact Lie groups. We give the proof of the noncommutative integrability of flows and show, in addition, for the case of (co)adjoint orbits, the usual Liouville
POSITIVE TOPOLOGICAL ENTROPY FOR MAGNETIC FLOWS ON SURFACES.
, 2006
"... Abstract. We study the topological entropy of the magnetic flow on closed riemannian surface. We prove that if the magnetic flow has a nonhyperbolic closed orbit in some energy set T c M = E −1 (c), then there exists an exact C ∞perturbation of the 2form Ω such that the new magnetic flow has posi ..."
Abstract

Cited by 1 (0 self)
 Add to MetaCart
Abstract. We study the topological entropy of the magnetic flow on closed riemannian surface. We prove that if the magnetic flow has a nonhyperbolic closed orbit in some energy set T c M = E −1 (c), then there exists an exact C ∞perturbation of the 2form Ω such that the new magnetic flow has
Periodic orbits for exact magnetic flows on surfaces
"... Abstract. We show that any exact magnetic flow on a closed surface has periodic orbits in all energy levels. Moreover, we give homological and homotopical properties of these periodic orbits in terms of the Mañé’s critical values of the corresponding Lagrangian. We also prove that if M is not th ..."
Abstract

Cited by 36 (10 self)
 Add to MetaCart
Abstract. We show that any exact magnetic flow on a closed surface has periodic orbits in all energy levels. Moreover, we give homological and homotopical properties of these periodic orbits in terms of the Mañé’s critical values of the corresponding Lagrangian. We also prove that if M
The longitudinal KAMcocycle of a magnetic flow
 Math. Proc. Cambridge Philos. Soc
, 2005
"... Abstract. Let M be a closed oriented surface of negative Gaussian curvature and let Ω be a nonexact 2form. Let λ be a small positive real number. We show that the longitudinal KAMcocycle of the magnetic flow given by λΩ is a coboundary if and only if the Gaussian curvature is constant and Ω is a ..."
Abstract

Cited by 8 (1 self)
 Add to MetaCart
Abstract. Let M be a closed oriented surface of negative Gaussian curvature and let Ω be a nonexact 2form. Let λ be a small positive real number. We show that the longitudinal KAMcocycle of the magnetic flow given by λΩ is a coboundary if and only if the Gaussian curvature is constant and Ω is a
MAGNETIC FLOWS ON SolMANIFOLDS: DYNAMICAL AND SYMPLECTIC ASPECTS
, 708
"... Abstract. We consider magnetic flows on compact quotients of the 3dimensional solvable geometry Sol determined by the usual leftinvariant metric and the distinguished monopole. We show that these flows have positive Liouville entropy and therefore are never completely integrable. This should be co ..."
Abstract

Cited by 3 (0 self)
 Add to MetaCart
Abstract. We consider magnetic flows on compact quotients of the 3dimensional solvable geometry Sol determined by the usual leftinvariant metric and the distinguished monopole. We show that these flows have positive Liouville entropy and therefore are never completely integrable. This should
Longitudinal KAMcocycles and action spectra of magnetic flows
"... Abstract. Let M be a closed oriented surface and let Ω be a nonexact 2form. Suppose that the magnetic flow φ of the pair (g, Ω) is Anosov. We show that the longitudinal KAMcocycle of φ is a coboundary if and only the Gaussian curvature is constant and Ω is a constant multiple of the area form thu ..."
Abstract

Cited by 10 (4 self)
 Add to MetaCart
Abstract. Let M be a closed oriented surface and let Ω be a nonexact 2form. Suppose that the magnetic flow φ of the pair (g, Ω) is Anosov. We show that the longitudinal KAMcocycle of φ is a coboundary if and only the Gaussian curvature is constant and Ω is a constant multiple of the area form
Anosov Magnetic Flows, Critical Values And Topological Entropy
, 2000
"... We study the magnetic ow determined by a smooth Riemannian metric g and a closed 2form on a closed manifold M . If the lift of to the universal cover f M is exact, we can define a critical value c(g; in the sense of Mañé [28] for the lift of the ow to f M . We have c(g; < 1 if and only ..."
Abstract

Cited by 30 (7 self)
 Add to MetaCart
We study the magnetic ow determined by a smooth Riemannian metric g and a closed 2form on a closed manifold M . If the lift of to the universal cover f M is exact, we can define a critical value c(g; in the sense of Mañé [28] for the lift of the ow to f M . We have c(g; < 1 if and only
Results 1  10
of
141,209