Opportunities
The Lab is currently seeking motivated students and postdocs to work on a number of projects including the ones listed below
For Background on smoke aerosols, click here and here
Fire Influence on Regional to Global Environments and Air Quality (FIREX-AQ) is a field study designed to comprehensively study wildfires across the western and southeastern United States by combining aircraft observations with surface measurements and satellite remote sensing data. The overarching goal of FIREX-AQ is to provide measurements of trace gas and aerosol emissions for wildfires and prescribed fires in great detail, and relating them to fuel and fire conditions at the point of emission. Dr. Chakrabarty's group is focused on performing ground-based measurements as part of FIREX-AQ using state-of-the-art optical instrumentation, in conjunction with a suite of instruments for understanding complex physical and chemical processes, to accurately characterize the spectral dependencies of fresh and atmospherically-processed aerosol optical and physico-chemical properties from wildfires and prescribed burns in the northwestern United States. It builds on a series of successful laboratory chamber experiments in Dr. Chakrabarty's lab that investigated these properties for smoke aerosol emitted from combustion of different North American wildland fuels. Thus, this project provides a unique opportunity to compare measured aerosol properties to laboratory data and close the knowledge gap between laboratory and ambient studies.
BD transiton.mp4Lagrangian dynamics: Ballistic-to-Diffusive Transition in 3-d
Background information: cover article in Cosmos Magazine
The kinetics of ballistic-to-diffusive (BD) transition is fundamental to predicting the onset of diffusion in stochastic systems (e.g., aerosol), yet there exists no generalized theoretical formulation of this process. The difficulty arises from the wide diversity of driving mechanisms in stochastic systems, as well as order-of-magnitude variances in their geometric length-scales. The fluctuation-dissipation (FD) theorem formulated by Langevin in 1908 predicts the BD transition in Brownian systems using an exponentially decaying velocity autocorrelation function. The FD theorem, however, cannot be applied to describing stochastic motion driven by non-Brownian mechanisms that do not correlate with velocity. Dr. Chakrabarty’s group established the first generalized parameterization of the BD transition in 2-dimensional systems applicable to any stochastic system irrespective of its driving mechanism and scale. They introduced a directional statistics formulation of the BD transition kinetics using a wrapped Cauchy distribution (WCD) function that governs the probability distribution of the relative angle between successive velocity vectors of motion. Owing to the universality of directional statistics and robustness of WCD in modeling stochastic motion, these results are expected to find applicability in a wide range of systems. Research is currently ongoing for determining the BD transition in 3-dimensional systems and non-physical systems.
Light_scattering_Yuli_Heinson.mp4Aerosol Instrumentation Development (click here for details)
Data-Driven Model for Real-Time Detection, Forecasting, and Suppression of Tics in Tourette Syndrome
Tics and Tourette Syndrome. Tics are brief, purposeless, and involuntary behaviors appearing through the movements of skeletal and vocal musculature in adolescents diagnosed with Tourette syndrome (TS). Tics affect more than 20% of all children among which about one-tenth has been observed to develop into severe chronical TS. Epidemiologic studies have shown that tics, which often entangle with other obsessive-compulsive symptoms, have considerable negative impacts on the self-esteems of the affected adolescents, damage their family-and-peer relationships, and lead to potential periods of depression. In severe cases of TS, motor and phonic tics evolve to uncontrolled extreme behaviors such as self-injury and offensive utterance, respectively. Despite decades of active scientific research, no consensus has been reached on the causes of tics, nor the pathophysiological foundations of them.
Characterizing the dynamics of tics. Accurate characterization of the temporal dynamics of tics plays a central role in the efficacy of TS treatment. Knowledge of the patterns in the temporal sequence of tic onsets informs doctors about the best timing to initiate interventions. Insights to the statistical characterization of tics can be gained by recognizing the fractal-like patterns in their temporal sequences–tics tend to arise in clusters (bouts of tic, see Fig. on left), waxing and waning in severity. Bouts of tics, lasting several seconds, recur in grouped episodes over the courses of hours, and such a recursive behavior in turn extends to longer timespan (days, weeks, and months) demonstrating self-similarity.
The objectives of this project are to: (1) obtain data toward establishing a temporal scaling relationship for the chaotic onset dynamics of tics in patients with Tourette syndrome (TS), facilitating a quantitative evaluation of TS severity and treatment effectiveness over changing timescales, and (2) develop an artificial intelligence (AI) system prototype that automatically detects and forecasts tic onsets, facilitating a suppression treatment informed by a proactive mechanism, and alleviating the unavailability of TS treatment due to the shortage of behavioral therapists. The student will work a team of interdisciplinary researchers from Washington University’s McKelvey School of Engineering and School of Medicine.
Granular-level Simulation to Probe the Sol-to-Gel Kinetics
Background information: Click here
DLCA_Sol-to_Gel.MOV