arXiv subjects

Ryan S. Westafer

Publications and source records attributed to Ryan S. Westafer.

4 recordsLinked to original sources

arXiv2026

Calibration of electric fields in low-frequency off-resonant Rydberg receivers

We present results on Rydberg atom-based electric field sensing in the range of 1 kHz - 300 MHz, using a three-photon Rydberg excitation scheme and a transverse electromagnetic (TEM) line waveguide to apply low-frequency rf fields to the cell. Measurements of low-frequency screening in quartz and sapphire vapor cells show excellent agreement with a phenomenological model of the effective vapor cell material properties based on an electrical 2-port measurement of the TEM line. We achieve a best noise-equivalent field of 106(4) $\mathrm{\frac{μV}{m \sqrt{Hz}}}$ at 300 MHz and characterize noise-equivalent fields in the ultra-low to very-low frequency (ULF-VLF) band.

physics.atom-ph↗

arXiv2024

Applying an electrostatic cross-correlation to the CFTR-ATP interaction

The cystic fibrosis transmembrane conductance regulator (CFTR) is an important membrane protein in vertebrates. The function of CFTR is to transport chloride ions across the cell membrane, which is known to require adenosine triphosphate (ATP). Whereas most conventional wisdom suggests that ATP interacts with CFTR purely through random collisions via diffusion, we investigate electrostatic interactions between CFTR and ATP at the mesoscale (10s of Angstroms). We use molecular dynamics to simulate CFTR-ATP interactions in cases where CFTR is bound/unbound from ATP, and we demonstrate an electrostatic potential gradient towards CFTR when ATP is unbound. We additionally compute electrostatic interactions between ATP and the solvent and membrane, which are simulated explicitly.

physics.bio-ph↗

arXiv2021

A factor graph EM algorithm for inference of kinetic microstates from patch clamp measurements

We derive a factor graph EM (FGEM) algorithm, a technique that permits combined parameter estimation and statistical inference, to determine hidden kinetic microstates from patch clamp measurements. Using the cystic fibrosis transmembrane conductance regulator (CFTR) and nicotinic acetylcholine receptor (nAChR) as examples, we perform {\em Monte Carlo} simulations to demonstrate the performance of the algorithm. We show that the performance, measured in terms of the probability of estimation error, approaches the theoretical performance limit of maximum {\em a posteriori} estimation. Moreover, the algorithm provides a reliability score for its estimates, and we demonstrate that the score can be used to further improve the performance of estimation. We use the algorithm to estimate hidden kinetic states in lab-obtained CFTR single channel patch clamp traces.

q-bio.QM↗

arXiv2015

Time turns the universal kaleidoscope

This (withdrawn) creative essay intended to consider the appearance of time's arrow in a fully symmetric universe compatible with "pilot wave" or transactional interpretations (D. Bohm or J.G. Kramer, respectively). The (unstated) hypothesis was that, despite unitary time evolution, the inherent Hilbert transform operator found in the energy operator of the Schrodinger equation and in commutation relations of Fourier observables indicates dissipation and seemingly, entropy increase.

physics.pop-ph↗