Data-Driven Discovery of Active Nematic Hydrodynamics.

Active nematics can be modeled using phenomenological continuum theories that account for the dynamics of the nematic director and fluid velocity through partial differential equations (PDEs). While these models provide a statistical description of the experiments, the relevant terms in the PDEs and their parameters are usually identified indirectly. We adapt a recently developed method to automatically identify optimal continuum models for active nematics directly from spatiotemporal data, via sparse regression of the coarse-grained fields onto generic low order PDEs. After extensive benchmarking, we apply the method to experiments with microtubule-based active nematics, finding a surprisingly minimal description of the system. Our approach can be generalized to gain insights into active gels, microswimmers, and diverse other experimental active matter systems.

Trimming of silicon-on-insulator ring-resonators via localized laser annealing.

We propose a post-fabrication trimming method for the silicon-on-insulator photonic platform based on localised laser annealing of hydrogen silsesquioxane (HSQ) cladding. The technique is fast, does not degrade the device performance, does not require additional fabrication steps, and can therefore be implemented at minimal cost. Here we experimentally demonstrated how the spectrum of a ring resonator can be shifted by over 1 nm by annealing a section of the device as short as 30 µm, corresponding to a change in the effective refractive index of ∼10-2. Modifications of both the HSQ refractive index and its chemical structure as a function of the annealing temperature are also discussed. Trimming of multi-ring resonators indicate that this technique can be effectively used for post-fabrication reconfiguration of complex photonic circuits or to compensate for the fabrication tolerances of a typical CMOS process.

Autologous transplantation for aggressive non-Hodgkin's lymphoma: results of a randomized trial evaluating graft source and minimal residual disease.

PURPOSE: To determine whether the source of autologous hematopoietic stem cells altered the clinical outcomes of patients undergoing high-dose chemotherapy and hematopoietic stem-cell transplantation (HSCT) for aggressive non-Hodgkin's lymphoma (NHL). PATIENTS AND METHODS: Of 105 high-risk, persistent, or relapsed NHL patients slated for an autologous HSCT entered onto this trial, 93 eligible patients were randomized to receive cytokine-naive autologous bone marrow transplantation (ABMT) (n = 46) or mobilized peripheral-blood stem-cell transplantation (PBSCT) (n = 47). All patients received carmustine, etoposide, cytarabine, and cyclophosphamide as the conditioning regimen. PBSCT patients also received identical mobilization with granulocyte colony-stimulating factor (G-CSF) 10 microg/kg/d, and both groups received G-CSF 5 microg/kg/d after the infusion of the stem-cell product until neutrophil engraftment. RESULTS: PBSCT patients had significantly faster engraftment of all cell lineages: median time to absolute neutrophil count > or = 500/microL, 10 days versus 13 days on the ABMT arm; median time to platelet count greater than 20,000/microL untransfused, 11 days versus 15 days on the ABMT arm; and median time to RBC transfusion independence, 8 days versus 16 days on the ABMT arm. The complete response rate was 72% for PBSCT and 54% for ABMT. The death rate before posttransplant day 100 was 2% on the ABMT arm and 6% on PBSCT arm. Event-free survival was 37% for PBSCT and 37% for ABMT. However, overall survival for PBSCT was 61% compared with 43% for ABMT. CONCLUSION: Patients with aggressive NHL receiving HSCT randomized to PBSCT demonstrated improved neutrophil engraftment and platelet and RBC transfusion independence. The complete response rate and EFS were not statistically different by randomization arm. Patients whose harvests were positive for minimal residual disease by molecular analysis had poorer EFS.