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OpenMRF: A Modular, Vendor-Neutral Open-Source Framework for Reproducible Magnetic Resonance Fingerprinting using Pulseq
Authors:
Tom Griesler,
Jannik Stebani,
Sydney Kaplan,
Ivaylo Angelov,
Petra Albert,
Martin Blaimer,
Tobias Wech,
Xiang Wang,
Qingping Chen,
Maxim Zaitsev,
Zhibo Zhu,
Qi Liu,
Peter Martin,
Jon-Fredrik Nielsen,
Jesse I Hamilton,
Peter Nordbeck,
Nicole Seiberlich,
Maximilian Gram
Abstract:
Purpose: Widespread adoption and methodological advancement of Magnetic Resonance Fingerprinting (MRF) are limited by the lack of unified, reproducible implementation frameworks and fragmented open-source tools. To address these barriers, we introduce OpenMRF - a comprehensive Pulseq-based solution - designed to enable consistent, reproducible, and transferable MRF research across vendors, sites,…
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Purpose: Widespread adoption and methodological advancement of Magnetic Resonance Fingerprinting (MRF) are limited by the lack of unified, reproducible implementation frameworks and fragmented open-source tools. To address these barriers, we introduce OpenMRF - a comprehensive Pulseq-based solution - designed to enable consistent, reproducible, and transferable MRF research across vendors, sites, and field strengths.
Methods: OpenMRF integrates modular Pulseq-based sequence design, Bloch-simulation-based dictionary creation directly from .seq files, and iterative low-rank subspace reconstruction. The framework was evaluated through digital phantom simulations, a multi-site ISMRM/NIST phantom study on Siemens MRI systems at 0.55 T, 1.5 T, and 3 T as well as GE and United Imaging 3 T platforms, and representative in vivo acquisitions in the liver (0.55 T), myocardium (1.5 T), and brain (3 T).
Results: Simulations demonstrated high mapping accuracy in an ISMRM/NIST-like digital phantom, with low-rank reconstruction yielding deviations of 0.03+/-0.32 % (T1) and 0.12+/-1.94 % (T2). The multi-site phantom study yielded relaxation times consistent with reference values at all field strengths, with mean deviations of -0.1+/-2.9 % (T1), -1.5+/-8.7 % (T2), and -4.0+/-7.2 % (T1rho). In vivo acquisitions produced high-quality parameter maps across platforms and field strengths.
Conclusion: OpenMRF provides a robust, open-source, end-to-end Pulseq-based solution for MRF that enables reproducible sequence implementation, physics-accurate dictionary simulation, and advanced reconstruction across vendors and field strengths. By providing a unified platform for method development, comparison, and multi-site validation, OpenMRF aims to accelerate reproducible and harmonized quantitative MRI research within the community.
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Submitted 24 April, 2026;
originally announced April 2026.
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Null Results, Real Learning: Geomagnetic Response to an X1.8 Solar Flare with Research-Grade and Smartphone Magnetometers in a Citizen-Science Classroom Activity
Authors:
Roger M. Hart,
Lauren E. Messina,
Eric A. Schenck,
Samantha R. Kaplan,
Diego A. Canté,
Izaiah Figueroa,
Gabriella Sepe,
Zavier Lopez,
Ryan Ward,
Sammy P. Morse,
Melanie V. Ramirez,
Brady J. Gaulin
Abstract:
Introductory college Earth and space science courses offer rich opportunities for citizen science projects. One especially compelling context is Earth's geomagnetic field: a self-excited dynamo in the liquid outer core generates a global field that couples Earth's interior to solar forcing, providing a natural laboratory for space weather education. We tested the viability of smartphone magnetomet…
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Introductory college Earth and space science courses offer rich opportunities for citizen science projects. One especially compelling context is Earth's geomagnetic field: a self-excited dynamo in the liquid outer core generates a global field that couples Earth's interior to solar forcing, providing a natural laboratory for space weather education. We tested the viability of smartphone magnetometers for quantitative monitoring during the 4 November 2025 X1.8 solar flare, linking planetary magnetism, space weather, and authentic undergraduate research. Co-located observations were obtained with a Geometrics G-857 proton-precession magnetometer and tri-axial smartphone sensors logging via Physics Toolbox in a course-based undergraduate research experience (CURE) emphasizing the Nature of Science (NOS). Fourteen one-minute paired averages spanning 17:27-17:40 UT revealed a systematic smartphone bias of about 630 nT (95% confidence interval 550-710 nT) relative to the G-857 and a weak negative correlation (r ~ -0.4). Smartphone magnetometers thus lack the precision and calibration stability needed for nanotesla-scale flare signatures but remain valuable as pedagogical and engagement tools. We frame smartphones within a tiered instrumentation ladder linking research-grade observatories, intermediate-cost community magnetometers (for example, HamSCI Personal Space Weather Stations), and smartphones as high-engagement entry points to geomagnetic and space weather studies. This hierarchy aligns citizen science with open data protocols and NOS pedagogy, transforming low-cost sensing into epistemically grounded inquiry suitable for introductory college laboratories.
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Submitted 26 November, 2025;
originally announced November 2025.
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Superstep wavefield propagation
Authors:
Tamas Nemeth,
Kurt Nihei,
Alex Loddoch,
Anusha Sekar,
Ken Bube,
John Washbourne,
Luke Decker,
Sam Kaplan,
Chunling Wu,
Andrey Shabelansky,
Milad Bader,
Ovidiu Cristea,
Ziyi Yin
Abstract:
This paper describes how to propagate wavefields for arbitrary numbers of traditional time steps in a single step, called a superstep. We show how to construct operators that accomplish this task for finite-difference time domain schemes, including temporal first-order schemes in isotropic, anisotropic and elastic media, as well as temporal second-order schemes for acoustic media. This task is ach…
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This paper describes how to propagate wavefields for arbitrary numbers of traditional time steps in a single step, called a superstep. We show how to construct operators that accomplish this task for finite-difference time domain schemes, including temporal first-order schemes in isotropic, anisotropic and elastic media, as well as temporal second-order schemes for acoustic media. This task is achieved by implementing a computational tradeoff differing from traditional single step wavefield propagators by precomputing propagator matrices for each model location for k timesteps (a superstep) and using these propagator matrices to advance the wavefield k time steps at once. This tradeoff separates the physics of the propagator matrix computation from the computer science of wavefield propagation and allows each discipline to provide their optimal modular solutions.
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Submitted 5 June, 2024;
originally announced June 2024.
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Characterization of the Hamamatsu 8-inch R14688-100 PMT
Authors:
Tanner Kaptanoglu,
Ashley Rincon,
Mackenzie Duce,
Sawyer Kaplan,
Joseph Koplowitz,
Skipper Lynch,
Hong Joo Ryoo,
Gabriel Orebi Gann
Abstract:
Large-scale optical neutrino and dark-matter detectors rely on large-area photomultiplier tubes (PMTs) for cost-effective light detection. The new R14688-100 8-inch PMT developed by Hamamatsu provides state-of-the-art timing resolution of around 1 ns (FWHM), which can help improve vertex reconstruction and enable Cherenkov and scintillation light separation in scintillation-based detectors. This P…
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Large-scale optical neutrino and dark-matter detectors rely on large-area photomultiplier tubes (PMTs) for cost-effective light detection. The new R14688-100 8-inch PMT developed by Hamamatsu provides state-of-the-art timing resolution of around 1 ns (FWHM), which can help improve vertex reconstruction and enable Cherenkov and scintillation light separation in scintillation-based detectors. This PMT also provides excellent charge resolution, allowing for precision photoelectron counting and improved energy reconstruction. The Eos experiment is the first large-scale optical detector to utilize these PMTs. In this manuscript we present a characterization of the R14688-100 single photoelectron response, such as the transit-time spreads, the dark-rates, and the afterpulsing. The single photoelectron response measurements are performed for the 206 PMTs that will be used in Eos.
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Submitted 9 January, 2024; v1 submitted 8 November, 2023;
originally announced November 2023.
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On Circular Orbits in Einstein's Theory of Gravitation
Authors:
S. A. Kaplan
Abstract:
The preprint is an English translation of the paper by famous astrophysicist Samuil Kaplan (1921-1978) "O krugovykh orbitakh v teorii tyagoteniya Einsteina (On circular orbits in Einstein's theory of gravitation)", published in 1949 in the Journal of Experimental and Theoretical Physics (Vol. 19, No. 10, pp. 951-952) in Russian. This important 1 and 1/3 page paper is still inaccessible to a wide r…
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The preprint is an English translation of the paper by famous astrophysicist Samuil Kaplan (1921-1978) "O krugovykh orbitakh v teorii tyagoteniya Einsteina (On circular orbits in Einstein's theory of gravitation)", published in 1949 in the Journal of Experimental and Theoretical Physics (Vol. 19, No. 10, pp. 951-952) in Russian. This important 1 and 1/3 page paper is still inaccessible to a wide range of experts and students due to the lack of such translation. This paper is the first scientific publication of Samuil Kaplan and the pioneering work in this field. The aim of this presentation is to make the article available to a wide range of experts in the field of general relativity, relativistic astrophysics and the history of science, as well as to honor its author on the occasion of the 100th anniversary of his birth.
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Submitted 19 January, 2022;
originally announced January 2022.
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Dynamic Stimulation of Superconductivity With Resonant Terahertz Ultrasonic Waves
Authors:
Alan M. Kadin,
Steven B. Kaplan
Abstract:
An experiment is proposed to stimulate a superconducting thin film with terahertz (THz) acoustic waves, which is a regime not previously tested. For a thin film on a piezoelectric substrate, this can be achieved by coupling the substrate to a tunable coherent THz electromagnetic source. Suggested materials for initial tests are a niobium film on a quartz substrate, with a BSCCO intrinsic Josephson…
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An experiment is proposed to stimulate a superconducting thin film with terahertz (THz) acoustic waves, which is a regime not previously tested. For a thin film on a piezoelectric substrate, this can be achieved by coupling the substrate to a tunable coherent THz electromagnetic source. Suggested materials for initial tests are a niobium film on a quartz substrate, with a BSCCO intrinsic Josephson junction (IJJ) stack. This will create acoustic standing waves on the nm scale in the thin film. A properly tuned standing wave will enable electron diffraction across the Fermi surface, leading to electron localization perpendicular to the substrate. This is expected to reduce the effective dimensionality, and enhance the tendency for superconducting order parallel to the substrate, even well above the superconducting critical temperature. This enhancement can be observed by measuring the in-plane critical current and the perpendicular tunneling gap. A similar experiment may be carried out for a cuprate thin film, although the conduction electrons might be more responsive to spin waves than to acoustic waves. These experiments address a novel regime of large momentum transfer to the electrons, which should be quite distinct from the more traditional regime of large energy transfer obtained from direct electromagnetic stimulation. The experiments are also motivated in part by novel theories of the superconducting state involving dynamic charge-density waves and spin-density waves. Potential device applications are discussed.
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Submitted 24 August, 2016;
originally announced September 2016.
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Synchronization dynamics on the picosecond timescale in coupled Josephson junction neurons
Authors:
Ken Segall,
Matthew LeGro,
Steven Kaplan,
Oleksiy Svitelskiy,
Shreeya Khadka,
Patrick Crotty,
Daniel Schult
Abstract:
Conventional digital computation is rapidly approaching physical limits for speed and energy dissipation. Here we fabricate and test a simple neuromorphic circuit that models neuronal somas, axons and synapses with superconducting Josephson junctions. The circuit models two mutually coupled excitatory neurons. In some regions of parameter space the neurons are desynchronized. In others, the Joseph…
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Conventional digital computation is rapidly approaching physical limits for speed and energy dissipation. Here we fabricate and test a simple neuromorphic circuit that models neuronal somas, axons and synapses with superconducting Josephson junctions. The circuit models two mutually coupled excitatory neurons. In some regions of parameter space the neurons are desynchronized. In others, the Josephson neurons synchronize in one of two states, in-phase or anti-phase. An experimental alteration of the delay and strength of the connecting synapses can toggle the system back and forth in a phase-flip bifurcation. Firing synchronization states are calculated >70,000 times faster than conventional digital approaches. With their speed and low energy dissipation (10-17 Joules/spike), this set of proof-of- concept experiments establishes Josephson junction neurons as a viable approach for improvements in neuronal computation as well as applications in neuromorphic computing.
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Submitted 8 February, 2017; v1 submitted 16 August, 2016;
originally announced August 2016.
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Is a Single Photon Always Circularly Polarized? A Proposed Experiment using a Superconducting Microcalorimeter Photon Detector
Authors:
Alan M. Kadin,
Steven B. Kaplan
Abstract:
A single photon is well known to have spin S = hbar, which would correspond to circular polarization, and all quantum transitions with photon absorption or emission correspond to DeltaS = +/-hbar. However, it is also widely believed that a single photon may be linearly polarized, which would correspond to a state with S = 0. Indeed, linearly polarized single photons are central to most quantum ent…
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A single photon is well known to have spin S = hbar, which would correspond to circular polarization, and all quantum transitions with photon absorption or emission correspond to DeltaS = +/-hbar. However, it is also widely believed that a single photon may be linearly polarized, which would correspond to a state with S = 0. Indeed, linearly polarized single photons are central to most quantum entanglement experiments. On the contrary, it has recently been suggested (based on a realistic spin-quantized wave picture of quantum states) that a linearly polarized photon state must be a superposition of a pair of circularly polarized photons, each with S = +/-hbar. This question cannot be resolved using a conventional photon detector, which generally cannot distinguish one photon from two simultaneous photons. However, it can be addressed using a superconducting microcalorimeter detector with sub-eV energy resolution and high quantum efficiency (QE). A careful experiment demonstrating this photon pairing could place in question some of the paradoxical central foundations of modern quantum theory, including quantum entanglement and nonlocality.
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Submitted 9 July, 2014;
originally announced July 2014.
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Dynamical Structure of a Traditional Amazonian Social Network
Authors:
Paul L. Hooper,
Simon DeDeo,
Ann E. Caldwell Hooper,
Michael Gurven,
Hillard S. Kaplan
Abstract:
Reciprocity is a vital feature of social networks, but relatively little is known about its temporal structure or the mechanisms underlying its persistence in real world behavior. In pursuit of these two questions, we study the stationary and dynamical signals of reciprocity in a network of manioc beer (Spanish: chicha; Tsimane': shocdye') drinking events in a Tsimane' village in lowland Bolivia.…
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Reciprocity is a vital feature of social networks, but relatively little is known about its temporal structure or the mechanisms underlying its persistence in real world behavior. In pursuit of these two questions, we study the stationary and dynamical signals of reciprocity in a network of manioc beer (Spanish: chicha; Tsimane': shocdye') drinking events in a Tsimane' village in lowland Bolivia. At the stationary level, our analysis reveals that social exchange within the community is heterogeneously patterned according to kinship and spatial proximity. A positive relationship between the frequencies at which two families host each other, controlling for kinship and proximity, provides evidence for stationary reciprocity. Our analysis of the dynamical structure of this network presents a novel method for the study of conditional, or non-stationary, reciprocity effects. We find evidence that short-timescale reciprocity (within three days) is present among non- and distant-kin pairs; conversely, we find that levels of cooperation among close kin can be accounted for on the stationary hypothesis alone.
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Submitted 17 November, 2013; v1 submitted 1 July, 2013;
originally announced July 2013.