An Exactly Solvable Model for the Integrability-Chaos Transition in Rough Quantum Billiards

A central question of dynamics, largely open in the quantum case, is to what extent it erases a system's memory of its initial properties. Here we present a simple statistically solvable quantum model describing this memory loss across an integrability-chaos transition under a perturbation obeying no selection rules. From the perspective of quantum localization-delocalization on the lattice of quantum numbers, we are dealing with a situation where every lattice site is coupled to every other site with the same strength, on average. The model also rigorously justifies a similar set of relationships recently proposed in the context of two short-range-interacting ultracold atoms in a harmonic waveguide. Application of our model to an ensemble of uncorrelated impurities on a rectangular lattice gives good agreement with ab initio numerics.Comment: 29 pages, 5 figure

T-cell repertoire in the blood and lungs of atopic asthmatics before and after ragweed challenge

T cells play a pivotal role in initiating and orchestrating allergic responses in asthma. The goal of this work was to learn whether ragweed challenge in the lungs alters the T-cell repertoire expressed in the blood and lungs of atopic asthmatics. Analyses of cell numbers, differentials, and T-cell subsets in bronchoalveolar lavage (BAL) fluids showed that ragweed challenge was associated with preferential recruitment of CD4+ T cells into the lungs. A reverse transcriptase-polymerase chain reaction (RT-PCR) was used to amplify T-cell receptor (TCR) gene transcripts from unfractionated, CD4(+) and CD8(+) T cells in blood and BAL fluids. As judged by RT-PCR, the usage of TCR Vol and VP gene families in BAL fluids was similar to that in blood. Ragweed challenge did not change the levels of expression of these V gene families, The clonality of T cells was estimated by analyzing the diversity of TCR V-(D)-J junctional region nucleotide lengths associated with each Vol and VP gene family, using sequencing gel electrophoresis. Most V gene families in blood and BAL fluids were associated with multiple junctional region lengths before and after ragweed challenge, indicating polyclonal expression. Some V gene families were expressed in an oligoclonal manner in unfractionated, CD4(+), and CD8(+) T cells in BAL fluids before ragweed challenge, as indicated by a few predominant junctional region lengths. The majority of these V gene families became polyclonal after challenge, compatible with polyclonal T-cell influx during inflammation immediately after ragweed challenge, However, some V gene families became oligoclonal or developed a new oligoclonal pattern of junctional region lengths in BAL T cells after ragweed challenge. Surprisingly, this occurred in both CD4(+) and CD8(+) T cells. In one of these instances. DNA sequencing of V beta 21 junctional regions in CD8(+) T cells confirmed a change from polyclonal to oligoclonal expression after ragweed challenge. These findings show that ragweed challenge is associated with polyclonal influx and oligoclonal activation of both CD4(+) and CD8(+) T cells in the lungs

Peripheral T lymphocytes from patients with early systemic sclerosis co-cultured with autologous fibroblasts undergo an oligoclonal expansion similar to that occurring in the skin

In recent years several reports have suggested that T cells may have a role in systemic sclerosis (SSc). The aim of our study was to investigate the dynamics of T cell repertoire in early SSc disease analysing a target organ, the skin, and the peripheral blood. To date, indeed, it is not clear if T cell expansions found in SSc reflect a general activation or result from specific antigen stimulation in the target organs. This is an important point to assess in order to characterize the role of T cells in the development of SSc. To address these questions we studied T cell repertoire by CDR3 length analysis in skin biopsies and peripheral blood obtained from patients affected by SSc and we found that a skewed T cell repertoire was present only in the biopsies. In order to characterize more effectively the meaning of these data, we performed co-cultures using fibroblasts and peripheral blood mononuclear cells (PBMCs) obtained from SSc patients. These experiments showed that same T cell expansions were detectable in the skin of SSc patients and in the cultures of PBMCs and autologous fibroblasts of the patients but not in their peripheral blood. Taken together, these data suggest that fibroblasts trigger specific T cell expansions in the early phase of SSc