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1. A multilayer network model of the coevolution of the spread of a disease and competing opinions

   https://doi.org/10.1142/S0218202521500536  

   Peng, Kaiyan; Lu, Zheng; Lin, Vanessa; Lindstrom, Michael R.; Parkinson, Christian; Wang, Chuntian; Bertozzi, Andrea L.; Porter, Mason A. (November 2021, Mathematical Models and Methods in Applied Sciences)

   During the COVID-19 pandemic, conflicting opinions on physical distancing swept across social media, affecting both human behavior and the spread of COVID-19. Inspired by such phenomena, we construct a two-layer multiplex network for the coupled spread of a disease and conflicting opinions. We model each process as a contagion. On one layer, we consider the concurrent evolution of two opinions — pro-physical-distancing and anti-physical-distancing — that compete with each other and have mutual immunity to each other. The disease evolves on the other layer, and individuals are less likely (respectively, more likely) to become infected when they adopt the pro-physical-distancing (respectively, anti-physical-distancing) opinion. We develop approximations of mean-field type by generalizing monolayer pair approximations to multilayer networks; these approximations agree well with Monte Carlo simulations for a broad range of parameters and several network structures. Through numerical simulations, we illustrate the influence of opinion dynamics on the spread of the disease from complex interactions both between the two conflicting opinions and between the opinions and the disease. We find that lengthening the duration that individuals hold an opinion may help suppress disease transmission, and we demonstrate that increasing the cross-layer correlations or intra-layer correlations of node degrees may lead to fewer individuals becoming infected with the disease. 

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2. A critique of the Spite Plateau and the astration of primordial lithium

   https://doi.org/10.1093/mnras/stad936  

   Norris, J. E.; Yong, D.; Frebel, A.; Ryan, S. G. (March 2023, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We investigate the distribution of the lithium abundances, A(Li), of metal-poor dwarf and subgiant stars within the limits 5500 K < Teff < 6700 K, −6.0 < [Fe/H] < −1.5, and log  g ≳ 3.5 (a superset of parameters first adopted by Spite and Spite), using literature data for some 200 stars. We address the problem of the several methods that yield Teff differences up to 350 K, and hence uncertainties of 0.3 dex in [Fe/H] and A(Li), by anchoring Teff to the infrared flux method. We seek to understand the behaviour of A(Li) as a function of [Fe/H] – small dispersion at highest [Fe/H], ‘meltdown’ at intermediate values (i.e. large spread in Li below the Spite Plateau), and extreme variations at lowest [Fe/H]. Decreasing A(Li) is accompanied by increasing dispersion. Insofar as [Fe/H] increases as the Universe ages, the behaviour of A(Li) reflects chaotic star formation involving destruction of primordial Li, which settles to the classic Spite Plateau, with A(Li) ∼ 2.3, by the time the Galactic halo reaches [Fe/H] ∼ −3.0. We consider three phases: (1) first star formation in C-rich environments ([C/Fe] > 2.3), with depleted Li; (2) silicates-dominated star formation and destruction of primordial Li during pre-main-sequence evolution; and (3) materials from these two phases co-existing and coalescing to form C-rich stars with A(Li) below the Spite Plateau, leading to a toy model with the potential to explain the ‘meltdown’. We comment on the results of Mucciarelli et al. on the Lower RGB, and the suggestion of Aguado et al. favouring a lower primordial lithium abundance than generally accepted. 

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3. Firefly: The Case for a Holistic Understanding of the Global Structure and Dynamics of the Sun and the Heliosphere

   https://doi.org/10.3847/25c2cfeb.c647a83d  

   Raouafi, Nour E.; Hoeksema, J. Todd; Newmark, Jeffrey S.; Gibson, Sarah; Berger, Thomas E.; Upton, Lisa A.; Vourlidas, Angelos; Hassler, Donald M.; Kinnison, James; Ho, George C.; et al (August 2023, Bulletin of the AAS)

   This white paper is on the HMCS Firefly mission concept study. Firefly focuses on the global structure and dynamics of the Sun's interior, the generation of solar magnetic fields, the deciphering of the solar cycle, the conditions leading to the explosive activity, and the structure and dynamics of the corona as it drives the heliosphere. 

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4. The propagation and decay of a coastal vortex on a shelf

   https://doi.org/10.1017/jfm.2021.790  

   Crowe, Matthew N.; Johnson, Edward R. (November 2021, Journal of Fluid Mechanics)

   A coastal eddy is modelled as a barotropic vortex propagating along a coastal shelf. If the vortex speed matches the phase speed of any coastal trapped shelf wave modes, a shelf wave wake is generated leading to a flux of energy from the vortex into the wave field. Using a simple shelf geometry, we determine analytic expressions for the wave wake and the leading-order flux of wave energy. By considering the balance of energy between the vortex and wave field, this energy flux is then used to make analytic predictions for the evolution of the vortex speed and radius under the assumption that the vortex structure remains self-similar. These predictions are examined in the asymptotic limit of small rotation rate and shelf slope and tested against numerical simulations. If the vortex speed does not match the phase speed of any shelf wave, steady vortex solutions are expected to exist. We present a numerical approach for finding these nonlinear solutions and examine the parameter dependence of their structure. 

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5. A note on band surgery and the signature of a knot

   https://doi.org/10.1112/blms.12397  

   Moore, Allison H.; Vazquez, Mariel (July 2020, Bulletin of the London Mathematical Society)