30 research outputs found
Mean ergodicity of weighted composition operators on spaces of holomorphic functions
[EN] Let phi be a self-map of the unit disc D of the complex plane C and let psi be a holomorphic function on D. We investigate the mean ergodicity and power boundedness of the weighted composition operator C-phi,C-psi(f) = psi(f o phi) with symbol phi and multiplier psi on the space H(D). We obtain necessary and sufficient conditions on the symbol phi and on the multiplier psi which characterize when the weighted composition operator is power bounded and (uniformly) mean ergodic. One necessary condition is that the symbol phi has a fixed point in D. If phi is not a rational rotation, the sufficient conditions are related to the modulus of the multiplier on the fixed point of phi. Some of our results are valid in an open connected set U of the complex plane.This research was partially supported by MINECO, Project MTM2013-43540-P. The second and third authors were partially supported by GVA, Project AICO/2016/054.Beltrán Meneu, MJ.; Gómez Collado, MDC.; Jorda Mora, E.; Jornet Casanova, D. (2016). Mean ergodicity of weighted composition operators on spaces of holomorphic functions. Journal of Mathematical Analysis and Applications. 444(2):1640-1651. https://doi.org/10.1016/j.jmaa.2016.07.039S16401651444
Serum Antibody Response to Polysaccharides in Children with Recurrent Respiratory Tract Infections
We evaluated children (15-months old and older) with recurrent upper respiratory tract infections and normal levels of immunoglobulins in serum for specific polysaccharide immunodeficiency using an enzyme-linked immunosorbent assay method. Results showed that of 12 patients vaccinated with Act-HIB vaccine, one did not develop specific antibodies to Haemophilus influenzae type b, demonstrating that such immunodeficiency is present in Costa Rican children