Kevin Mitchell
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View article: Probabilistic Emissivity Retrieval from Hyperspectral Data via Physics-Guided Variational Inference
Probabilistic Emissivity Retrieval from Hyperspectral Data via Physics-Guided Variational Inference Open
Recent research has proven neural networks to be a powerful tool for performing hyperspectral imaging (HSI) target identification. However, many deep learning frameworks deliver a single material class prediction and operate on a per-pixel…
View article: Modeling active nematics via the nematic locking principle
Modeling active nematics via the nematic locking principle Open
Active nematic systems consist of rod-like internally driven subunits that interact with one another to form large-scale coherent flows. They are important examples of far-from-equilibrium fluids, which exhibit a wealth of nonlinear behavi…
View article: Computing Classical Escape Rates from Periodic Orbits in Chaotic Hydrogen
Computing Classical Escape Rates from Periodic Orbits in Chaotic Hydrogen Open
When placed in parallel magnetic and electric fields, the electron trajectories of a classical hydrogen atom are chaotic. The classical escape rate of such a system can be computed with classical trajectory Monte Carlo techniques, but thes…
View article: Spontaneous Optimal Mixing via Defect-Vortex Coupling in Confined Active Nematics
Spontaneous Optimal Mixing via Defect-Vortex Coupling in Confined Active Nematics Open
Active nematic flows in two dimensions, largely driven by motile $+1/2$ disclinations, mix themselves efficiently and exhibit chaos in the bulk steady state. Motivated by recent experimental findings for three-defect braiding in cardioid-s…
View article: A general approach to the statistics of microbial orientation: Lévy walks, noise, and deterministic motion
A general approach to the statistics of microbial orientation: Lévy walks, noise, and deterministic motion Open
Microbial motion is typically analyzed by simplified models in which trajectories exhibit straight runs (perhaps with added Gaussian noise) followed by random, discrete tumbling events. We present the results of a statistical analysis of t…
View article: Serinophospholipids: A third type of natural phospholipid discovered in a thermophilic bacterium
Serinophospholipids: A third type of natural phospholipid discovered in a thermophilic bacterium Open
Phospholipids are an essential constituent of cells with all life thought to produce phospholipids with either a glycerol or sphingoid moiety at their core. For the first time, we demonstrate that a thermophilic bacterium, Limisphaera ngat…
View article: Controlling chaos: Periodic defect braiding in active nematics confined to a cardioid
Controlling chaos: Periodic defect braiding in active nematics confined to a cardioid Open
This work examines self-mixing in active nematics, a class of fluids in which mobile topological defects drive chaotic flows in a system comprised of biological filaments and molecular motors. We present experiments that demonstrate how ge…
View article: Maximally mixing active nematics
Maximally mixing active nematics Open
Active nematics are an important new paradigm in soft condensed matter systems. They consist of rod-like components with an internal driving force pushing them out of equilibrium. The resulting fluid motion exhibits chaotic advection, in w…
View article: Identification and characterization of protein interactions with the major Niemann–Pick type C disease protein in yeast reveals pathways of therapeutic potential
Identification and characterization of protein interactions with the major Niemann–Pick type C disease protein in yeast reveals pathways of therapeutic potential Open
Niemann–Pick type C (NP-C) disease is a rare lysosomal storage disease caused by mutations in NPC1 (95% cases) or NPC2 (5% cases). These proteins function together in cholesterol egress from the lysosome, whereby upon mutation, cholesterol…
View article: mmSense: Detecting Concealed Weapons with a Miniature Radar Sensor
mmSense: Detecting Concealed Weapons with a Miniature Radar Sensor Open
For widespread adoption, public security and surveillance systems must be accurate, portable, compact, and real-time, without impeding the privacy of the individuals being observed. Current systems broadly fall into two categories -- image…
View article: Effect of a Biopsychosocial Intervention or Postural Therapy on Disability and Health Care Spending Among Patients With Acute and Subacute Spine Pain
Effect of a Biopsychosocial Intervention or Postural Therapy on Disability and Health Care Spending Among Patients With Acute and Subacute Spine Pain Open
Importance Low back and neck pain are often self-limited, but health care spending remains high. Objective To evaluate the effects of 2 interventions that emphasize noninvasive care for spine pain. Design, Setting, and Participants Pragmat…
View article: Barriers Impeding Active Mixing of Swimming Microbes in a Hyperbolic Flow
Barriers Impeding Active Mixing of Swimming Microbes in a Hyperbolic Flow Open
We present experiments on the motion of swimming microbes in a laminar, hyperbolic flow. We test a theory that predicts the existence of swimming invariant manifolds (SwIMs) that act as invisible, one-way barriers that block the motion of …
View article: Noise-Induced Aggregation of Swimmers in the Kolmogorov Flow
Noise-Induced Aggregation of Swimmers in the Kolmogorov Flow Open
We investigate a model for the dynamics of ellipsoidal microswimmers in an externally imposed, laminar Kolmogorov flow. Through a phase-space analysis of the dynamics without noise, we find that swimmers favor either cross-stream or rotati…
View article: Swimmer dynamics in externally driven fluid flows: The role of noise
Swimmer dynamics in externally driven fluid flows: The role of noise Open
We theoretically investigate the effect of random fluctuations on the motion\nof elongated microswimmers near hydrodynamic transport barriers in\nexternally-driven fluid flows. Focusing on the two-dimensional hyperbolic flow,\nwe consider …
View article: Reference intervals and values for fecal cortisol, aldosterone, and the ratio of cortisol to dehydroepiandrosterone metabolites in four species of cetaceans
Reference intervals and values for fecal cortisol, aldosterone, and the ratio of cortisol to dehydroepiandrosterone metabolites in four species of cetaceans Open
The goal of the current study was to create reference intervals and values for several common and one potential novel physiological indicators of animal welfare for four species of cetaceans. The subjects included 189 bottlenose dolphins (…
View article: Health reference intervals and values for common bottlenose dolphins (Tursiops truncatus), Indo-Pacific bottlenose dolphins (Tursiops aduncus), Pacific white-sided dolphins (Lagenorhynchus obliquidens), and beluga whales (Delphinapterus leucas)
Health reference intervals and values for common bottlenose dolphins (Tursiops truncatus), Indo-Pacific bottlenose dolphins (Tursiops aduncus), Pacific white-sided dolphins (Lagenorhynchus obliquidens), and beluga whales (Delphinapterus leucas) Open
This study reports comprehensive clinical pathology data for hematology, serum, and plasma biochemistry reference intervals for 174 apparently healthy common bottlenose dolphins ( Tursiops truncatus ) and reference values for 27 Indo-Pacif…
View article: Swimmer dynamics in externally-driven fluid flows: The role of noise
Swimmer dynamics in externally-driven fluid flows: The role of noise Open
We theoretically investigate the effect of random fluctuations on the motion of elongated microswimmers near hydrodynamic transport barriers in externally-driven fluid flows. Focusing on the two-dimensional hyperbolic flow, we consider the…
View article: Inonotus obliquus attenuates histamine-induced microvascular inflammation
Inonotus obliquus attenuates histamine-induced microvascular inflammation Open
Cell-to-cell communication is a key element of microvascular blood flow control, including rapidly carrying signals through the vascular endothelium in response to local stimuli. This cell-to-cell communication is negatively impacted durin…
View article: Graph Duality in Surface Dynamics
Graph Duality in Surface Dynamics Open
We compare one-dimensional representations for the isotopy stable dynamics of homeomorphisms in two dimensions. We consider the skeleton graph representative, which captures periodic behaviour, and the homotopy graph representative which c…
View article: A Surface of Section for Hydrogen in Crossed Electric and Magnetic Fields
A Surface of Section for Hydrogen in Crossed Electric and Magnetic Fields Open
A well defined global surface of section (SOS) is a necessary first step in many studies of various dynamical systems. Starting with a surface of section, one is able to more easily find periodic orbits as well as other geometric structure…
View article: Mode-locking in advection-reaction-diffusion systems: An invariant manifold perspective
Mode-locking in advection-reaction-diffusion systems: An invariant manifold perspective Open
Fronts propagating in two-dimensional advection-reaction-diffusion systems exhibit a rich topological structure. When the underlying fluid flow is periodic in space and time, the reaction front can lock to the driving frequency. We explain…
View article: Topological chaos in a three-dimensional spherical fluid vortex
Topological chaos in a three-dimensional spherical fluid vortex Open
In chaotic deterministic systems, seemingly stochastic behavior is generated\nby relatively simple, though hidden, organizing rules and structures. Prominent\namong the tools used to characterize this complexity in 1D and 2D systems are\nt…
View article: Using Invariant Manifolds to Construct Symbolic Dynamics for Three-Dimensional Volume-Preserving Maps
Using Invariant Manifolds to Construct Symbolic Dynamics for Three-Dimensional Volume-Preserving Maps Open
Topological techniques are powerful tools for characterizing the complexity of many dynamical systems, including the commonly studied area-preserving maps of the plane. However, the extension of many topological techniques to higher dimens…
View article: Frozen reaction fronts in steady flows: A burning-invariant-manifold perspective
Frozen reaction fronts in steady flows: A burning-invariant-manifold perspective Open
The dynamics of fronts, such as chemical reaction fronts, propagating in two-dimensional fluid flows can be remarkably rich and varied. For time-invariant flows, the front dynamics may simplify, settling in to a steady state in which the r…
View article: Thermorudis pharmacophila sp. nov., a novel member of the class Thermomicrobia isolated from geothermal soil, and emended descriptions of Thermomicrobium roseum, Thermomicrobium carboxidum, Thermorudis peleae and Sphaerobacter thermophilus
Thermorudis pharmacophila sp. nov., a novel member of the class Thermomicrobia isolated from geothermal soil, and emended descriptions of Thermomicrobium roseum, Thermomicrobium carboxidum, Thermorudis peleae and Sphaerobacter thermophilus Open
An aerobic, thermophilic and cellulolytic bacterium, designated strain WKT50.2 T , was isolated from geothermal soil at Waikite, New Zealand. Strain WKT50.2 T grew at 53–76 °C and at pH 5.9–8.2. The DNA G+C content was 58.4 mol%. The major…
View article: Finite-time barriers to front propagation in two-dimensional fluid flows
Finite-time barriers to front propagation in two-dimensional fluid flows Open
Recent theoretical and experimental investigations have demonstrated the role of certain invariant manifolds, termed burning invariant manifolds (BIMs), as one-way dynamical barriers to reaction fronts propagating within a flowing fluid. T…