A5078578099- Nonlinear Dynamics and Pattern Formation
- Neuroscience and Neuropharmacology Research
- Neural dynamics and brain function
- Fluid Dynamics and Turbulent Flows
- Plant Water Relations and Carbon Dynamics
- Air Quality and Health Impacts
- Atmospheric chemistry and aerosols
- Complex Systems and Time Series Analysis
- Receptor Mechanisms and Signaling
- Combustion and flame dynamics
- Numerical methods for differential equations
- Advanced Surface Polishing Techniques
- Chaos control and synchronization
- Advanced machining processes and optimization
- Wind and Air Flow Studies
- COVID-19 epidemiological studies
- Mathematical and Theoretical Epidemiology and Ecology Models
- Viral Infections and Vectors
- Quantum chaos and dynamical systems
- stochastic dynamics and bifurcation
- Air Quality Monitoring and Forecasting
- Probabilistic and Robust Engineering Design
- Ion channel regulation and function
- Molecular Sensors and Ion Detection
- Force Microscopy Techniques and Applications
University of Montana
2012-2024
Washington University in St. Louis
2024
Dalhousie University
2016-2020
Utah State University
1996-2004
Arizona State University
1993-1994
Colorado State University
1992
University of Cambridge
1990-1992
Cornell University
1987-1989
We have modelled the wall region of a turbulent boundary layer by expanding instantaneous field in so-called empirical eigenfunctions, as permitted proper orthogonal decomposition theorem (Lumley 1967, 1981). truncate representation to obtain low-dimensional sets ordinary differential equations, from Navier–Stokes via Galerkin projection. The experimentally determined eigenfunctions Herzog (1986) are used; these form streamwise rolls. Our model equations represent dynamical behaviour show...
Abstract. The Surface PARTiculate mAtter Network (SPARTAN) is a long-term project that includes characterization of chemical and physical attributes aerosols from filter samples collected worldwide. This paper discusses the ongoing efforts SPARTAN to define quantify major ions trace metals found in fine particulate matter (PM2.5). Our methods infer spatial temporal variability PM2.5 cost-effective manner. Gravimetrically weighed filters represent multi-day averages PM2.5, with collocated...
Estimates are derived for the mean recurrence time of orbits in neighborhood an attracting homoclinic orbit or heteroclinic cycle ordinary differential equation, subject to small additive random noise. The theory presented is illustrated with numerical simulations several systems, including ones invariant under symmetry groups, which such attractors structurally stable. physical implications work briefly discussed.
Exposure to ambient fine particulate matter (PM2.5) is a leading risk factor for the global burden of disease. However, uncertainty remains about PM2.5 sources. We use chemical transport model (GEOS-Chem) simulation 2014, constrained by satellite-based estimates interpret globally dispersed mass and composition measurements from ground-based surface network (SPARTAN). Measured site mean varies substantially secondary inorganic aerosols (2.4–19.7 μg/m3), mineral dust (1.9–14.7...
Particularly in rural settings, there has been little research regarding the health impacts of fine particulate matter (PM2.5) during wildfire season smoke exposure period on respiratory diseases, such as influenza, and their associated outbreaks months later. We examined delayed effects PM2.5 concentrations for short-lag (1–4 weeks prior) long-lag (during prior months) following winter influenza Montana, a mountainous state western United States. created gridded maps surface Montana from...
Glutamate transporters have a homotrimeric subunit structure with large central water-filled cavity that extends partially into the plane of lipid bilayer (Yernool et al., 2004). In addition to uptake glutamate, also mediate chloride conductance is increased in presence substrate. Whether channel located pore trimer or within individual subunits has been controversial. We find coexpression wild-type neuronal glutamate transporter EAAT3 mutated at R447, residue governing substrate selectivity...
Global ground-level measurements of elements in ambient particulate matter (PM) can provide valuable information to understand the distribution dust and trace elements, assess health impacts, investigate emission sources. We use X-ray fluorescence spectroscopy characterize elemental composition PM samples collected from 27 globally distributed sites Surface PARTiculate mAtter Network (SPARTAN) over 2019–2023. Consistent protocols are applied collect all analyze them at one central...
Abstract Globally consistent measurements of airborne metal concentrations in fine particulate matter (PM 2.5 ) are important for understanding potential health impacts, prioritizing air pollution mitigation strategies, and enabling global chemical transport model development. PM filter samples (N ~ 800 from 19 locations) collected a globally distributed surface sampling network (SPARTAN) between January 2013 April 2019 were analyzed mass trace metals content. Metal exhibited pronounced...
The influence of small noise on the dynamics heteroclinic networks is studied, with a particular focus noise-induced switching between cycles in network. Three different types are found, depending details underlying deterministic dynamics: random determined by linear near one saddle points, induced stability cycle, and intermittent cycles. All three responses explained examining size stable unstable eigenvalues at equilibria.
We develop a nonlinear model of chatter in drilling that incorporates friction the material on cutting tool and its interaction with axial-torsional mode vibration seen twist drills. Stability criteria are determined for both regenerative non-regenerative chatter, effect parameters law itself results is analysed. Our analysis shows exact form not critical stability calculation, only size coefficient steady cutting, slope at state. However, geometry crucial. In laboratory, vibrational...
Parvalbumin-positive basket cells (PV BCs) of the CA1 hippocampus are active participants in theta (5-12 Hz) and gamma (20-80 oscillations vivo. When PV BCs driven at these frequencies vitro, inhibitory postsynaptic currents (IPSCs) synaptically connected pyramidal exhibit paired-pulse depression (PPD) multiple-pulse (MPD). Moreover, express presynaptic muscarinic acetylcholine receptors (mAChRs) that may be activated by released during learning behaviors Using acute hippocampal slices from...
The dynamics of structurally stable heteroclinic cycles connecting fixed points with one-dimensional unstable manifolds under the influence noise is analyzed. Fokker-Planck equations for evolution probability distribution trajectories near are solved. magnitude and eigenvalues at amplitude added on location shape determined. As a consequence, jumping solution in out invariant subspaces deterministic system can be explained. (c) 1999 American Institute Physics.
Vector-borne diseases represent a threat to human and wildlife populations mathematical models provide means understand control epidemics involved in complex host-vector systems. The disease model studied here is system with relapsing class of host individuals, used investigate tick-borne fever (TBRF). Equilibrium analysis performed for increasing numbers relapses multiple hosts the reproduction number, R0, generalized establish relationships parameters that would result elimination disease....
A prominent aqueous cavity is formed by the junction of three identical subunits in excitatory amino acid transporter (EAAT) family. To investigate effect this structure on interaction ligands with transporter, we recorded currents voltage-clamped Xenopus oocytes expressing EAATs and used concentration jumps to measure binding unbinding rates a high-affinity aspartate analog that competitively blocks transport (β-2-fluorenyl-aspartylamide; 2-FAA). The blocker were approximately one order...
We consider here a model from Stone and Askari [Nonlinear models of chatter in drilling process, Dyn. Syst. 17 (2002), pp. 65–85] for regenerative process. The is nonlinear delay differential equation where the arises fact that cutting tool passes over metal surface repeatedly. For any fixed value delay, large enough increase width chip being cut results Hopf bifurcation steady state, which origin vibration. show zero degenerate small this leads to canard explosion. That is, as increased...
Cellular flames stabilized on a porous plug burner at low pressure form ordered patterns consisting of concentric rings cells. In certain regions the parameter space propane-air mixtures, appear intermittently. these states, persist for varying lengths time, abruptly dissolve into highly irregular structures with no discernible ring pattern, and then reappear as same or slightly different numbers Experimental evidence theoretical arguments show that intermittently states correspond to...