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We discuss the class of BP S saturated M –branes that are in one–to–one correspondence with the Freund–Rubin compactifications of M–theory on either AdS 4 × G/H or AdS 7 × G/H, where G/H is one of the seven (or four) dimensional Einstein coset manifolds with Killing spinors classified long ago in the context of Kaluza–Klein supergravity. These G/H M–branes,(More)
One of the most severe and widespread of human diseases is caused by the parasitic schistosome flatworm. The life cycle of this blood fluke involves asexual larval reproduction in an intermediate snail host, giving rise to the infectious free-swimming cercarial form. After penetrating the human tissue, the worms develop into adults that become situated in(More)
Free differential algebras (FDA's) provide an algebraic setting for field theories with antisymmetric tensors. The " presentation " of FDA's generalizes the Cartan-Maurer equations of ordinary Lie algebras, by incorporating p-form potentials. An extended Lie derivative along antisymmetric tensor fields can be defined, and used to recover a Lie algebra dual(More)
We consider noncommutative geometries obtained from a triangular Drinfeld twist and review the formulation of noncommutative gravity. A detailed study of the abelian twist geometry is presented. Inspired by [1, 2], we obtain solutions of noncommutative Einstein equations by considering twists that are compatible with the curved spacetime metric.
A ⋆-product is defined via a set of commuting vector fields X a = e µ a (x)∂ µ , and used in a φ ⋆4 theory coupled to the e µ a (x) fields. The ⋆-product is dy-namical, and the vacuum solution φ = 0, e µ a = δ µ a reproduces the usual Moyal product. The action is invariant under rigid translations and Lorentz rotations , and the conserved energy-momentum(More)
The three-dimensional structure of scallop sarcoplasmic reticulum membranes has been determined from electron micrographs of two classes of stain-filled tubules by helical reconstruction methods. These structures are characterized by dimer ribbons of Ca2+-ATPase molecules running diagonally around the tube wall. Deep right-handed grooves separate the(More)
Scallop sarcoplasmic reticulum (SR), visualized in situ by freeze-fracture and deep-etching, is characterized by long tubes displaying crystalline arrays of Ca2+-ATPase dimer ribbons, resembling those observed in isolated SR vesicles. The orderly arrangement of the Ca2+-ATPase molecules is well preserved in muscle bundles permeabilized with saponin.(More)