Martingale transforms and their projection operators on manifolds
  We prove the boundedness on $L^p$, $1<p<\infty$, of operators on manifolds which arise by taking conditional expectation of transformations of stochastic integrals. These operators include various classical operators such as second order Riesz transforms and operators of Laplace transform-type. 
Rodrigo Ba\~nuelos, Fabrice Baudoin
math.PR math.FA