M. Aldaz, J. et L. Varona, Juan, Singular Measures and Convolution Operators, Acta mathematica Sinica. English series (Print) , 23(3), 2007, pp. 487-490
We show that in the study of certain convolution operators, functions can be replaced by measures without changing the size of the constants appearing in weak type (1, 1) inequalities. As an application, we prove that the best constants for the centered Hardy.Littlewood maximal operator associated with parallelotopes do not decrease with the dimension.