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D Ullmo

Publications and source records attributed to D Ullmo.

9 recordsLinked to original sources
PubMed2001

Resonance-assisted tunneling in near-integrable systems.

Dynamical tunneling between symmetry related invariant tori is studied in the near-integrable regime. Using the kicked Harper model as an illustration, we show that the exponential decay of the wave functions in the classically forbidden region is modified due to coupling processes that are mediated by classical resonances. This mechanism leads to a substantial deviation of the splitting between quasidegenerate eigenvalues from the purely exponential decrease with 1/Planck's over 2pi obtained for the integrable system. A simple semiclassical framework, which takes into account the effect of the resonance substructure on the invariant tori, allows one to quantitatively reproduce the behavior of the eigenvalue splittings.

Journal Article↗
PubMed1978

[Cerebral trauma - psychological trauma? Study of 47 children with medulloblastoma and their follow-up].

47 Children with medulloblastoma who were treated between 1954 and 1974 were studied. The parents and children were interviewed regularly with their medical attendants to estimate the contribution of the organic disease, the psychological factors and the environment on their intellectual performance and their personalities. In the assessment, allowance was made for their age, clinical history, and social and scholastic background. The analysis helped in the choice of the most appropriate psychological support. The difficulties of social re-adjustment cannot be solely due to the brain tumour or its sequelae. The parents have to forget their idealised image of their child, who never existed and who never will, so that they can give the child a new start and enjoy life without fear of death. In this distressing exercise, the extent of the emotional trauma becomes obvious.

Adolescent↗