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1. Classification of metric measure spaces and their ends using p-harmonic functions

   https://doi.org/10.54330/afm.120618  

   Björn, Anders; Björn, Jana; Shanmugalingam, Nageswari (March 2022, Annales Fennici Mathematici)

   By seeing whether a Liouville type theorem holds for positive, bounded, and/or finite \(p\)-energy \(p\)-harmonic and \(p\)-quasiharmonic functions, we classify proper metric spaces equipped with a locally doubling measure supporting a local \(p\)-Poincaré inequality. Similar classifications have earlier been obtained for Riemann surfaces and Riemannian manifolds. We study the inclusions between these classes of metric measure spaces, and their relationship to the \(p\)-hyperbolicity of the metric space and its ends. In particular, we characterize spaces that carry nonconstant \(p\)-harmonic functions with finite \(p\)-energy as spaces having at least two well-separated \(p\)-hyperbolic sequences of sets towards infinity. We also show that every such space \(X\) has a function \(f \notin L^p(X) + \mathbf{R}\) with finite \(p\)-energy. 

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2. Abundances of P, S, and K in 58 bulge spheroid stars from APOGEE

   https://doi.org/10.1051/0004-6361/202555713  

   Barbuy, B; Ernandes, H; Friaça, A_C S; Camargo, M S; da_Silva, P; Souza, S O; Masseron, T; Brauner, M; García-Hernández, D A; Fernández-Trincado, J G; et al (August 2025, Astronomy & Astrophysics)

   Context. We have previously studied several elements in 58 selected bulge spheroid stars, based on spectral lines in theHband. We now derive the abundances of the less studied elements phosphorus (P; Z=15), sulphur (S; Z=16), and potassium (K; Z=19). Aims. The abundances of P, S, and K in 58 bulge spheroid stars are compared both with the results of a previous analysis of the data from the Apache Point Observatory Galactic Evolution Experiment (APOGEE), and with a few available studies of these elements. Methods. We derived the individual abundances through spectral synthesis, using the stellar physical parameters available for our sample from the DR17 release of the APOGEE project. We provide recommendations for the best lines to be used for the studied elements among those in theH-band. We also compare the present results, together with literature data, with chemical-evolution models. Finally, the neutrino-process was taken into account for the suitable fit to the odd-Z elements P and K. Results. We confirm that theH-band has useful lines for the derivation of the elements P, S, and K in moderately metal-poor stars. The abundances, plotted together with literature results from high-resolution spectroscopy, indicate that moderately enhanced phosphorus stars are found, reminiscent of results obtained for thick disc and halo stars of metallicity [Fe/H]≈−1.0. Therefore, for the first time, we identify that this effect occurs in the old stars from the bulge spheroid. Sulphur is anα-element and behaves as such. Potassium and sulphur both exhibit some star-to-star scatter, but fit within the expectations of chemical evolution models. 

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3. Thermal convection over fractal surfaces

   https://doi.org/10.1017/jfm.2020.826  

   Toppaladoddi, Srikanth; Wells, Andrew J.; Doering, Charles R.; Wettlaufer, John S. (January 2021, Journal of Fluid Mechanics)

   null (Ed.)

   We use well resolved numerical simulations with the lattice Boltzmann method to study Rayleigh–Bénard convection in cells with a fractal boundary in two dimensions for $Pr = 1$ and $$Ra \in \left [10^7, 10^{10}\right ]$$ , where Pr and Ra are the Prandtl and Rayleigh numbers. The fractal boundaries are functions characterized by power spectral densities $S(k)$ that decay with wavenumber, $$k$$ , as $$S(k) \sim k^{p}$$ ( $p < 0$ ). The degree of roughness is quantified by the exponent $$p$$ with $p < -3$ for smooth (differentiable) surfaces and $$-3 \le p < -1$$ for rough surfaces with Hausdorff dimension $$D_f=\frac {1}{2}(p+5)$$ . By computing the exponent $$\beta$$ using power law fits of $$Nu \sim Ra^{\beta }$$ , where $Nu$ is the Nusselt number, we find that the heat transport scaling increases with roughness through the top two decades of $$Ra \in \left [10^8, 10^{10}\right ]$$ . For $$p$$ $= -3.0$ , $-2.0$ and $-1.5$ we find $$\beta = 0.288 \pm 0.005, 0.329 \pm 0.006$$ and $$0.352 \pm 0.011$$ , respectively. We also find that the Reynolds number, $Re$ , scales as $$Re \sim Ra^{\xi }$$ , where $$\xi \approx 0.57$$ over $$Ra \in \left [10^7, 10^{10}\right ]$$ , for all $$p$$ used in the study. For a given value of $$p$$ , the averaged $Nu$ and $Re$ are insensitive to the specific realization of the roughness. 

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4. Chaos, dynamic trapping, and transport of swimming microbes in a vortex chain flow

   https://doi.org/10.1063/5.0270869  

   Le, Nghia; Solomon, Thomas_H (June 2025, Chaos: An Interdisciplinary Journal of Nonlinear Science)

   We present experiments on chaotic motion of self-propelled (active) particles in a time-independent, two-dimensional vortex chain flow. We track Tetraselmis microbes and calculate the variance of a spreading distribution of these microbes in the flow. For small non-dimensional swimming speed v0, we find subdiffusion with variance ⟨x2⟩∼tγ with γ<1; transport is diffusive (γ=1) for larger v0. Subdiffusion for small v0 is due to dynamic trapping of microbes to islands of ordered trajectories surrounded by a sea of chaotic motion; these islands disappear for larger v0. We calculate Lagrangian-averaged trajectories (LATs) from the experimental data and use the LATs to measure trapping time probability distributions P(t). We find regimes with P(t)∼t−ν with ν<2 for small v0, consistent with the measured subdiffusion. 

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5. Methodological factors affecting capture of juvenile salmon in baited “minnow” traps

   https://doi.org/10.1002/nafm.11004  

   Peltola, Eugene R; Rinella, Daniel J; Benson, Anna-Marie; Gerken, Jonathon (June 2024, North American Journal of Fisheries Management)

   Abstract ObjectiveIn a southcentral Alaska stream system, we conducted a study to evaluate the effect of trap type (galvanized and nylon coated), bait type (salmon roe cured with and without sodium sulfite), and soak times (1 h and 24 h) on captures of juvenile salmon using Gee-style minnow traps. This was undertaken due to the limited research on this topic, aiming to determine how variations in methodology affected captures in juvenile salmon. MethodsWe employed a three-way fixed factorial design to sample 176 stream reaches (with a single trap in each each) from June 2021 to September 2021, capturing 296 Coho Salmon Oncorhynchus kisutch and 105 Chinook Salmon O. tshawytscha. ResultWe found an estimated 78% decrease in captures of Coho Salmon when nylon-coated traps were used instead of galvanized traps, and we found that trap type showed no effect on number of captures for Chinook Salmon. Additionally, we did not detect effects of bait type and soak time on the number of captures for either species. Not surprisingly, there was a positive relationship between Julian date and temperature with captures for both species. Additionally, for Coho Salmon, we found a quadratic relationship between water velocity and captures. ConclusionUnderstanding and accounting for these factors will help researchers to maximize trapping efficiency, standardize protocols, and determine the extent to which results are comparable across studies employing different methods. 

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