Magnetomyography: A novel modality for non-invasive muscle sensing

bioRxiv preprint 2024.04:15.588623 (2024)

Authors:

Richy Yun, Gabriel Gonzalez, Isabel Gerrard, Richard Csaky, Debadatta Dash, Evan Kittle, Nishita Deka, Dominic Labanowski

Abstract:

The measurement of magnetic fields generated by skeletal muscle activity, called magnetomyography (MMG), has seen renewed interest from the academic community in recent years. Although studies have demonstrated complex models of MMG and experiments classifying between different movements using MMG, there has yet to be time frequency analysis of MMG as well as concurrent recordings of MMG and its electrical counterpart, surface electromyography (sEMG). Here, we aim to better understand MMG in the context of sEMG by simultaneously recording both modalities during various muscle contraction tasks. We found that, similar to sEMG, MMG shows highly linearly correlated power to the degree of muscle contraction, has a unimodal distribution in spectral power, and can detect changes in muscle fatigue via changes in the spectral distribution. One main difference we found was that MMG typically has more high frequency content compared to sEMG, even when accounting for the filtering induced by the size of the sEMG electrodes. We additionally demonstrate empirically the decrease in MMG power due to distance from the arm and show MMG decreases slower than the inverse square law and can be measured up to 50 mm from the surface of the skin. Finally, we were able to capture MMG with non-OPM sensors showing that sensor technology has made great strides towards enabling MMG applications.

Scaling Laws for Galaxy Images

(2024)

Authors:

Mike Walmsley, Micah Bowles, Anna MM Scaife, Jason Shingirai Makechemu, Alexander J Gordon, Annette MN Ferguson, Robert G Mann, James Pearson, J眉rgen J Popp, Jo Bovy, Josh Speagle, Hugh Dickinson, Lucy Fortson, Tobias G茅ron, Sandor Kruk, Chris J Lintott, Kameswara Mantha, Devina Mohan, David O'Ryan, Inigo V Slijepevic

Wavelet Analysis of Differential TEC Measurements Obtained Using LOFAR

Radio Science American Geophysical Union (AGU) 59:4 (2024) e2023RS007871

Authors:

Ben Boyde, Alan Wood, Gareth Dorrian, Frits Sweijen, Francesco de Gasperin, Maaijke Mevius, Kasia Beser, David Themens

Abstract:

Abstract Radio interferometers used to make astronomical observations, such as the LOw Frequency ARray (LOFAR), experience distortions imposed upon the received signal due to the ionosphere as well as those from instrumental errors. Calibration using a well鈥恈haracterized radio source can be used to mitigate these effects and produce more accurate images of astronomical sources, and the calibration process provides measurements of ionospheric conditions over a wide range of length scales. The basic ionospheric measurement this provides is differential Total Electron Content (TEC, the integral of electron density along the line of sight). Differential TEC measurements made using LOFAR have a precision of <1 mTECu and therefore enable investigation of ionospheric disturbances which may be undetectable to many other methods. We demonstrate an approach to identify ionospheric waves from these data using a wavelet transform and a simple plane wave model. The noise spectra are robustly characterized to provide uncertainty estimates for the fitted parameters. An example is shown in which this method identifies a wave with an amplitude an order of magnitude below those reported using Global Navigation Systems Satellite TEC measurements. Artificially generated data are used to test the accuracy of the method and establish the range of wavelengths which can be detected using this method with LOFAR data. This technique will enable the use of a large and mostly unexplored data set to study traveling ionospheric disturbances over Europe.

The Weird and the Wonderful in Our Solar System: Searching for Serendipity in the Legacy Survey of Space and Time

The Astronomical Journal, 167:118 (14pp), 2024 March

Authors:

Brian Rogers, Chris J. Lintott, Steve Croft, Megan E. Schwamb , and James R. A. Davenport

Abstract:

We present a novel method for anomaly detection in solar system object data in preparation for the Legacy Survey of Space and Time. We train a deep autoencoder for anomaly detection and use the learned latent space to search for other interesting objects. We demonstrate the efficacy of the autoencoder approach by finding interesting examples, such as interstellar objects, and show that by using the autoencoder, further examples of interesting classes can be found. We also investigate the limits of classic unsupervised approaches to anomaly detection through the generation of synthetic anomalies and evaluate the feasibility of using a supervised learning approach. Future work should consider expanding the feature space to increase the variety of anomalies that can be uncovered during the survey using an autoencoder.

A new method for short-duration transient detection in radio images: searching for transient sources in MeerKAT data of NGC 5068

Monthly Notices of the Royal Astronomical Society Oxford University Press (OUP) 528:4 (2024) 6985-6996

Authors:

S Fijma, A Rowlinson, RAMJ Wijers, I de Ruiter, WJG de Blok, S Chastain, AJ van der Horst, ZS Meyers, K van der Meulen, R Fender, PA Woudt, A Andersson, A Zijlstra, J Healy, FM Maccagni