A robotic Intelligent Towing Tank for learning complex fluid-structure dynamics.

We describe the development of the Intelligent Towing Tank, an automated experimental facility guided by active learning to conduct a sequence of vortex-induced vibration (VIV) experiments, wherein the parameters of each next experiment are selected by minimizing suitable acquisition functions of quantified uncertainties. This constitutes a potential paradigm shift in conducting experimental research, where robots, computers, and humans collaborate to accelerate discovery and to search expeditiously and effectively large parametric spaces that are impracticable with the traditional approach of sequential hypothesis testing and subsequent train-and-error execution. We describe how our research parallels efforts in other fields, providing an orders-of-magnitude reduction in the number of experiments required to explore and map the complex hydrodynamic mechanisms governing the fluid-elastic instabilities and resulting nonlinear VIV responses. We show the effectiveness of the methodology of "explore-and-exploit" in parametric spaces of high dimensions, which are intractable with traditional approaches of systematic parametric variation in experimentation. We envision that this active learning approach to experimental research can be used across disciplines and potentially lead to physical insights and a new generation of models in multi-input/multi-output nonlinear systems.

Perivascular stromal cells as a potential reservoir of human cytomegalovirus.

Human cytomegalovirus (HCMV) infection is an important cause of morbidity and mortality among both solid organ and hematopoietic stem cell transplant recipients. Identification of cells throughout the body that can potentially serve as a viral reservoir is essential to dissect mechanisms of cell tropism and latency and to develop novel therapies. Here, we tested and compared the permissivity of liver-, brain-, lung (LNG)- and bone marrow (BM)-derived perivascular mesenchymal stromal cells (MSC) to HCMV infection and their ability to propagate and produce infectious virus. Perivascular MSC isolated from the different organs have in common the expression of CD146 and Stro-1. While all these cells were permissive to HCMV infection, the highest rate of HCMV infection was seen with LNG-MSC, as determined by viral copy number and production of viral particles by these cells. In addition, we showed that, although the supernatants from each of the HCMV-infected cultures contained infectious virus, the viral copy number and the quantity and timing of virus production varied among the various organ-specific MSC. Furthermore, using quantitative polymerase chain reaction, we were able to detect HCMV DNA in BM-MSC isolated from 7 out of 19 healthy, HCMV-seropositive adults, suggesting that BM-derived perivascular stromal cells may constitute an unrecognized natural HCMV reservoir.