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1. Propagation of nutrients and metals after the 2022 Hermit's Peak-Calf Canyon gigafire

   https://doi.org/10.3389/frwa.2025.1636421  

   Kaphle, Asmita; Rodríguez, Lina; Tunby, Paige; Nichols, Justin; Khandelwal, Aashish; Joseph, Eric; Aldred, Jennifer; Van_Horn, David J; González-Pinzón, Ricardo (August 2025, Frontiers in Water)

   The increasing severity and frequency of wildfires in forested watersheds pose significant challenges to water quality management. This study examines the impacts of the 2022 Hermit's Peak-Calf Canyon gigafire, the largest wildfire in New Mexico's history. The wildfire burned over 1,382 km², affecting a key watershed that supplies drinking water to Las Vegas, NM. We conducted a longitudinal assessment of post-fire water quality dynamics across a 170 km fluvial network, analyzing flow, water quality parameters, nutrient and metal concentrations, and mobilization patterns. We found that post-fire nutrient concentrations exceeded pre-fire medians by up to two orders of magnitude. Our analyses revealed solute-specific transport patterns that are difficult to predict with static watershed- or fire-specific characteristics (e.g., burned area and percent severities). ${\text{NH}}_4^{+}$, ${\text{PO}}_3^{-}$, and ${\text{NO}}_2^{-}$were closely and positively associated with discharge and turbidity near the burn perimeter, while ${\text{NO}}_3^{-}$and TON exhibited strong mobilization trends ~170 km downstream. In contrast to nutrients, calcium, magnesium, and manganese levels showed no significant pre- vs. post-fire shifts, while concentrations of trace metals like Cr³⁺, Pb²⁺, Zn²⁺, and Sr²⁺surpassed background levels and public health thresholds. Our findings emphasize the significant propagation of wildfire disturbances over hundreds of kilometers and suggest the need for integrated watershed management strategies, including the management of large-scale flood control mechanisms to mitigate the far-reaching impacts of water quality disturbances post-fire. 

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2. Neutron skins: A perspective from dispersive optical models

   https://doi.org/10.3389/fphy.2024.1487314  

   Atkinson, M C; Dickhoff, W H (October 2024, Frontiers in Physics)

   Moreno, O (Ed.)

   An overview of neutron skin predictions obtained using an empirical nonlocal dispersive optical model (DOM) is presented. The DOM links both scattering and bound-state experimental data through a subtracted dispersion relation which allows for fully consistent, data-informed predictions for nuclei where such data exist. Large skins were predicted for both⁴⁸Ca ( $R_{\text{skin}}^{48}=0.25\pm 0.023$fm in 2017) and²⁰⁸Pb ( $R_{\text{skin}}^{208}=0.25\pm 0.05$fm in 2020). Whereas the DOM prediction in²⁰⁸Pb is within 1 $\sigma$of the subsequent PREX-2 measurement, the DOM prediction in⁴⁸Ca is over 2 $\sigma$larger than the thin neutron skin resulting from CREX. From the moment it was revealed, the thin skin in⁴⁸Ca has puzzled the nuclear-physics community as no adequate theories simultaneously predict both a large skin in²⁰⁸Pb and a small skin in⁴⁸Ca. The DOM is unique in its ability to treat both structure and reaction data on the same footing, providing a unique perspective on this $R_{\text{skin}}$puzzle. It appears vital that more neutron data be measured in both the scattering and bound-state domain for⁴⁸Ca to clarify the situation. 

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3. Calderón–Zygmund theory for strongly coupled linear system of nonlocal equations with Hölder-regular coefficient

   https://doi.org/10.1515/acv-2024-0005  

   Mengesha, Tadele; Schikorra, Armin; Seesanea, Adisak; Yeepo, Sasikarn (November 2024, Advances in Calculus of Variations)

   Abstract We extend the Calderón–Zygmund theory for nonlocal equations tostrongly coupled system of linear nonlocal equations ${\mathcal{ℒ}}_A^{s}u=f${\mathcal{L}^{s}_{A}u=f}, where the operator ${\mathcal{ℒ}}_A^s${\mathcal{L}^{s}_{A}}is formally given by ${\mathcal{ℒ}}_A^{s}u={\int }_{{ℝ}^n}\frac{A(x,y)}{{\left|x-y\right|}^{n+2s}}\frac{\left(x-y\right)\otimes \left(x-y\right)}{{\left|x-y\right|}^2}\left(u\left(x\right)-u\left(y\right)\right)𝑑y.$\mathcal{L}^{s}_{A}u=\int_{\mathbb{R}^{n}}\frac{A(x,y)}{|x-y|^{n+2s}}\frac{(x-%y)\otimes(x-y)}{|x-y|^{2}}(u(x)-u(y))\,dy. For $0<s<1${0<1}and $A:{ℝ}^n\times {ℝ}^n\to ℝ${A:\mathbb{R}^{n}\times\mathbb{R}^{n}\to\mathbb{R}}taken to be symmetric and serving asa variable coefficient for the operator, the system under consideration is the fractional version of the classical Navier–Lamé linearized elasticity system. The study of the coupled system of nonlocal equations is motivated by its appearance in nonlocal mechanics, primarily in peridynamics. Our regularity result states that if $A(\cdot ,y)${A(\,\cdot\,,y)}is uniformly Holder continuous and ${inf}_{x\in {ℝ}^n}A(x,x)>0${\inf_{x\in\mathbb{R}^{n}}A(x,x)>0}, then for $f\in L_{\mathrm{loc}}^p${f\in L^{p}_{\rm loc}}, for $p\ge 2${p\geq 2}, the solution vector $u\in H_{\mathrm{loc}}^{2s-\delta ,p}${u\in H^{2s-\delta,p}_{\rm loc}}for some $\delta \in (0,s)${\delta\in(0,s)}. 

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4. Study the structure of the low-lying states of ²⁰⁶ Po

   https://doi.org/10.1088/1402-4896/ad4521  

   Kocheva, D; Rainovski, G; Jolie, J; Beckers, M; Blazhev, A; Esmaylzadeh, A; Fransen, C; Gladnishki, K A; Pietralla, N; Scheck, M; et al (May 2024, Physica Scripta)

   Abstract The nucleus²⁰⁶Po was studied in the two proton transfer reaction²⁰⁴Pb(¹⁶O,¹⁴C)²⁰⁶Po and the lifetime of the first excited 2⁺state was determined by utilizing the Recoil Distance Doppler Shift method. The experimental results are compared with shell-model calculations based on different effective interactions. The calculations qualitatively reproduced the experimentally observed $B(E2;2_1^{+}\to 0_1^{+})$value, suggesting that the $2_1^{+}$state of²⁰⁶Po exhibits a collective nature. However, the employed effective interactions revealed some limitations, particularly in their description of the $4_{1,2}^{+}$states. These results emphasize the importance of understanding the properties of low-lying states, especially their evolution from single-particle dynamics to collective modes, in evaluating various effective nuclear interactions. 

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5. Keck Planet Imager and Characterizer Emission Spectroscopy of WASP-33b

   https://doi.org/10.3847/1538-3881/acda91  

   Finnerty, Luke; Schofield, Tobias; Sappey, Ben; Xuan, Jerry W.; Ruffio, Jean-Baptiste; Wang, Jason J.; Delorme, Jacques-Robert; Blake, Geoffrey A.; Buzard, Cam; Fitzgerald, Michael P.; et al (June 2023, The Astronomical Journal)

   Abstract We present Keck Planet Imager and Characterizer (KPIC) high-resolution (R∼35,000)K-band thermal emission spectroscopy of the ultrahot Jupiter WASP-33b. The use of KPIC’s single-mode fibers greatly improves both blaze and line-spread stabilities relative to slit spectrographs, enhancing the cross-correlation detection strength. We retrieve the dayside emission spectrum with a nested-sampling pipeline, which fits for orbital parameters, the atmospheric pressure–temperature profile, and the molecular abundances. We strongly detect the thermally inverted dayside and measure mass-mixing ratios for CO ( ${\mathrm{logCO}}_{\mathrm{MMR}}=-{1.1}_{-0.6}^{+0.4}$), H₂O ( ${\mathrm{logH}}_2{\mathrm{O}}_{\mathrm{MMR}}=-{4.1}_{-0.9}^{+0.7}$), and OH ( ${\mathrm{logOH}}_{\mathrm{MMR}}=-{2.1}_{-1.1}^{+0.5}$), suggesting near-complete dayside photodissociation of H₂O. The retrieved abundances suggest a carbon- and possibly metal-enriched atmosphere, with a gas-phase C/O ratio of ${0.8}_{-0.2}^{+0.1}$, consistent with the accretion of high-metallicity gas near the CO₂snow line and post-disk migration or with accretion between the soot and H₂O snow lines. We also find tentative evidence for¹²CO/¹³CO ∼ 50, consistent with values expected in protoplanetary disks, as well as tentative evidence for a metal-enriched atmosphere (2–15 × solar). These observations demonstrate KPIC’s ability to characterize close-in planets and the utility of KPIC’s improved instrumental stability for cross-correlation techniques. 

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