Two-dimensional spectroscopy for the study of ion coulomb crystals.

Ion Coulomb crystals are currently establishing themselves as a highly controllable test bed for mesoscopic systems of statistical mechanics. The detailed experimental interrogation of the dynamics of these crystals, however, remains an experimental challenge. In this work, we show how to extend the concepts of multidimensional nonlinear spectroscopy to the study of the dynamics of ion Coulomb crystals. The scheme we present can be realized with state-of-the-art technology and gives direct access to the dynamics, revealing nonlinear couplings even in the presence of thermal excitations. We illustrate the advantages of our proposal showing how two-dimensional spectroscopy can be used to detect signatures of a structural phase transition of the ion crystal, as well as resonant energy exchange between modes. Furthermore, we demonstrate in these examples how different decoherence mechanisms can be identified

Distinct patterns of hematopoietic stem cell involvement in acute lymphoblastic leukemia.

The cellular targets of primary mutations and malignant transformation remain elusive in most cancers. Here, we show that clinically and genetically different subtypes of acute lymphoblastic leukemia ( ALL) originate and transform at distinct stages of hematopoietic development. Primary ETV6-RUNX1 ( also known as TEL-AML1) fusions and subsequent leukemic transformations were targeted to committed B-cell progenitors. Major breakpoint BCR-ABL1 fusions ( encoding P210 BCR-ABL1) originated in hematopoietic stem cells (HSCs), whereas minor BCR-ABL1 fusions ( encoding P190 BCR-ABL1) had a B-cell progenitor origin, suggesting that P190 and P210 BCR-ABL1 ALLs represent largely distinct tumor biological and clinical entities. The transformed leukemia-initiating stem cells in both P190 and P210 BCR-ABL1 ALLs had, as in ETV6-RUNX1 ALLs, a committed B progenitor phenotype. In all patients, normal and leukemic repopulating stem cells could successfully be separated prospectively, and notably, the size of the normal HSC compartment in ETV6-RUNX1 and P190 BCR-ABL1 ALLs was found to be unaffected by the expansive leukemic stem cell population