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1. Quantitative determination of spin–orbit-induced magnetic field in GaMnAs by field-scan planar Hall measurements

   https://doi.org/10.1038/s41598-021-89748-6  

   Park, Seongjoon; Lee, Shinwoo; Lee, Kyung Jae; Park, SeongJin; Chongthanaphisut, Phunvira; Jang, Jiyeong; Lee, Sanghoon; Liu, Xinyu; Dobrowolska, M.; Furdyna, Jacek K. (December 2021, Scientific Reports)

   null (Ed.)

   Abstract Spin–orbit-induced (SOI) effective magnetic field in GaMnAs film with in-plane magnetic anisotropy has been investigated by planar Hall effect measurements. The presence of SOI field was identified by a shift between planar Hall resistance (PHR) hystereses observed with positive and negative currents. The difference of switching fields occurring between the two current polarities, which is determined by the strength of the SOI field, is shown to depend on the external field direction. In this paper we have developed a method for obtaining the magnitude of the SOI fields based on magnetic free energy that includes the effects of magnetic anisotropy and the SOI field. Using this approach, the SOI field for a given current density was accurately obtained by fitting to the observed dependence of the switching fields on the applied field directions. Values of the SOI field obtained with field scan PHR measurements give results that are consistent with those obtained by analyzing the angular dependence of PHR, indicating the reliability of the field scan PHR method for quantifying the SOI-field in GaMnAs films. The magnitude of the SOI field systematically increases with increasing current density, demonstrating the usefulness of SOI fields for manipulation of magnetization by current in GaMnAs films. 

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2. Neural Networks for Conversion of Simulated NMR Spectra from Low-Field to High-Field for Quantitative Metabolomics

   https://doi.org/10.3390/metabo14120666  

   Johnson, Hayden; Tipirneni-Sajja, Aaryani (December 2024, Metabolites)

   Background: The introduction of benchtop NMR instruments has made NMR spectroscopy a more accessible, affordable option for research and industry, but the lower spectral resolution and SNR of a signal acquired on low magnetic field spectrometers may complicate the quantitative analysis of spectra. Methods: In this work, we compare the performance of multiple neural network architectures in the task of converting simulated 100 MHz NMR spectra to 400 MHz with the goal of improving the quality of the low-field spectra for analyte quantification. Multi-layered perceptron networks are also used to directly quantify metabolites in simulated 100 and 400 MHz spectra for comparison. Results: The transformer network was the only architecture in this study capable of reliably converting the low-field NMR spectra to high-field spectra in mixtures of 21 and 87 metabolites. Multi-layered perceptron-based metabolite quantification was slightly more accurate when directly processing the low-field spectra compared to high-field converted spectra, which, at least for the current study, precludes the need for low-to-high-field spectral conversion; however, this comparison of low and high-field quantification necessitates further research, comparison, and experimental validation. Conclusions: The transformer method of NMR data processing was effective in converting low-field simulated spectra to high-field for metabolomic applications and could be further explored to automate processing in other areas of NMR spectroscopy. 

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3. Solar Tachocline Confinement by the Nonaxisymmetric Modes of a Dynamo Magnetic Field

   https://doi.org/10.3847/1538-4357/ad18b2  

   Matilsky, Loren I.; Brummell, Nicholas H.; Hindman, Bradley W.; Toomre, Juri (February 2024, The Astrophysical Journal)

   Abstract We recently presented the first 3D numerical simulation of the solar interior for which tachocline confinement was achieved by a dynamo-generated magnetic field. In this follow-up study, we analyze the degree of confinement as the magnetic field strength changes (controlled by varying the magnetic Prandtl number) in a coupled radiative zone (RZ) and convection zone (CZ) system. We broadly find three solution regimes, corresponding to weak, medium, and strong dynamo magnetic field strengths. In the weak-field regime, the large-scale magnetic field is mostly axisymmetric with regular, periodic polarity reversals (reminiscent of the observed solar cycle) but fails to create a confined tachocline. In the strong-field regime, the large-scale field is mostly nonaxisymmetric with irregular, quasi-periodic polarity reversals and creates a confined tachocline. In the medium-field regime, the large-scale field resembles a strong-field dynamo for extended intervals but intermittently weakens to allow temporary epochs of strong differential rotation. In all regimes, the amplitude of poloidal field strength in the RZ is very well explained by skin-depth arguments, wherein the oscillating field that gives rise to the skin depth (in the medium- and strong-field cases) is a nonaxisymmetric field structure at the base of the CZ that rotates with respect to the RZ. These simulations suggest a new picture of solar tachocline confinement by the dynamo, in which nonaxisymmetric, very long-lived (effectively permanent) field structures rotating with respect to the RZ play the primary role, instead of the regularly reversing axisymmetric field associated with the 22 yr cycle. 

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4. Bending the Trajectory of Field School Teaching and Learning through Active and Advocacy Archaeology

   https://doi.org/10.3390/humans3010002  

   Lambert, Shawn P.; Colaninno, Carol E. (March 2023, Humans)

   Many individuals practicing field-based research are subjected to sexual harassment and assault. This fact holds true for people engaged in archaeological field research and may be true for students who are just learning field methods while enrolled in an archaeological field school. We review some of our current research on the means of reducing and preventing sexual harassment and assault at archaeological field schools, as well as ways to create safer, more inclusive learning spaces. Additionally, we suggest that for the discipline to advance field school teaching and learning, we, as field directors, must situate ourselves as active and advocacy anthropologists: an approach that puts our students as a central focus when developing field-based pedagogy. As the authors of this work, we review our identities and positionality in conducting this research and in making meaning from the data we have collected. 

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5. Mean field games of controls: Propagation of monotonicities

   https://doi.org/10.3934/puqr.2022015  

   Mou, Chenchen; Zhang, Jianfeng (January 2022, Probability, Uncertainty and Quantitative Risk)

   The theory of Mean Field Game of Controls considers a class of mean field games where the interaction is through the joint distribution of the state and control. It is well known that, for standard mean field games, certain monotonicity conditions are crucial to guarantee the uniqueness of mean field equilibria and then the global wellposedness for master equations. In the literature the monotonicity condition could be the Lasry–Lions monotonicity, the displacement monotonicity, or the anti-monotonicity conditions. In this paper, we investigate these three types of monotonicity conditions for Mean Field Games of Controls and show their propagation along the solutions to the master equations with common noises. In particular, we extend the displacement monotonicity to semi-monotonicity, whose propagation result is new even for standard mean field games. This is the first step towards the global wellposedness theory for master equations of Mean Field Games of Controls. 

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