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1. Mars-Crossing Minor Planet 2018 VL10: a Jupiter-family Comet Discovery via Citizen Science

   https://doi.org/10.3847/2515-5172/ad1682  

   Chandler, Colin Orion; Oldroyd, William J.; Trujillo, Chadwick A.; Hsieh, Henry H.; Burris, William A.; Kueny, Jay K.; DeSpain, Jarod A.; Sedaghat, Nima; Farrell, Kennedy A.; Magbanua, Mark Jesus; et al (December 2023, Research Notes of the AAS)

   Abstract We announce the discovery of cometary activity emitting from minor planet 2018 VL₁₀in Dark Energy Camera images spanning from UT 2018 December 31 to UT 2019 March 3. The activity was identified by volunteers of our NASA Partner programActive Asteroids, aZooniverse-hosted Citizen Science project designed to find previously unknown activity in known minor planets. Notably, 2018 VL₁₀crosses the orbits of Mars and Jupiter, and experiences close approaches of less than 0.5 au with both Earth and Jupiter. We classify 2018 VL₁₀as a member of the Jupiter-family comets, a group of objects especially important to understand because they hold important clues about the solar system volatile distribution, past and present. 

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2. AI-enhanced Citizen Science Discovers Cometary Activity on Near-Earth Object (523822) 2012 DG61

   https://doi.org/10.3847/2515-5172/ada368  

   Chandler, Colin Orion; Sedaghat, Nima; Oldroyd, William J; Frissell, Maxwell K; Trujillo, Chadwick A; Burris, William A; Hsieh, Henry H; Kueny, Jay K; Farrell, Kennedy A; Borisov, Gennady V; et al (January 2025, Research Notes of the AAS)

   Abstract We report the discovery of cometary activity in the form of a pronounced tail emanating from Near-Earth Object (523822) 2012 DG₆₁, identified in UT 2024 April 18 Dark Energy Camera images by our AI assistant TailNet. TailNet is an AI designed to filter out images unlikely to show activity for volunteers of our NASA Partner “Active Asteroids” Citizen Science campaign, from which our AI is trained. Subsequently, our archival investigation revealed 2012 DG61 is recurrently active after we found it displaying a pronounced tail in a UT 2018 April 16 Steward Observatory Bart Bok 2.3 m telescope image and UT 2018 May 14 observations by G. Borisov with the 0.3 m telescope at MARGO Observatory. Our dynamical integrations reveal that 2012 DG61, an Apollo dynamical class member, is likely in 2:1 mean-motion resonance with Jupiter. We encourage additional observations to help characterize the activity morphology of this near-Earth comet. 

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3. Large mitigation potential of smoke PM _2.5 in the US from human-ignited fires

   https://doi.org/10.1088/1748-9326/aca91f  

   Carter, Therese S; Heald, Colette L; Selin, Noelle E (January 2023, Environmental Research Letters)

   Abstract Increasing fire activity and the associated degradation in air quality in the United States has been indirectly linked to human activity via climate change. In addition, direct attribution of fires to human activities may provide opportunities for near term smoke mitigation by focusing policy, management, and funding efforts on particular ignition sources. We analyze how fires associated with human ignitions (agricultural fires and human-initiated wildfires) impact fire particulate matter under 2.5µm (PM_2.5) concentrations in the contiguous United States (CONUS) from 2003 to 2018. We find that these agricultural and human-initiated wildfires dominate fire PM_2.5in both a high fire and human ignition year (2018) and low fire and human ignition year (2003). Smoke from these human levers also makes meaningful contributions to total PM_2.5(∼5%–10% in 2003 and 2018). Across CONUS, these two human ignition processes account for more than 80% of the population-weighted exposure and premature deaths associated with fire PM_2.5. These findings indicate that a large portion of the smoke exposure and impacts in CONUS are from fires ignited by human activities with large mitigation potential that could be the focus of future management choices and policymaking. 

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4. The Scaling of Vortical Electron Acceleration in Thin-current Magnetic Reconnection and Its Implications in Solar Flares

   https://doi.org/10.3847/1538-4357/ad09e6  

   Crawford, C.; Che, H.; Benz, A. O. (January 2024, The Astrophysical Journal)

   Abstract To investigate how magnetic reconnection (MR) accelerates electrons to a power-law energy spectrum in solar flares, we explore the scaling of a kinetic model proposed by Che & Zank (CZ) and compare it to observations. Focusing on thin current sheet MR particle-in-cell (PIC) simulations, we analyze the impact of domain size on the evolution of the electron Kelvin–Helmholtz instability (EKHI). We find that the duration of the growth stage of the EKHI ( $t_G\sim {\mathrm{\Omega }}_e^{-1}$) is short and remains nearly unchanged because the electron gyrofrequency Ω_eis independent of domain size. The quasi-steady stage of the EKHI (t_MR) dominates the electron acceleration process and scales linearly with the size of the simulations asL/v_A0, wherev_A0is the Alfvén speed. We use the analytical results obtained by CZ to calculate the continuous temporal evolution of the electron energy spectra from PIC simulations and linearly scale them to solar flare observational scales. For the first time, an electron acceleration model predicts the sharp two-stage transition observed in typical soft–hard–harder electron energy spectra, implying that the electron acceleration model must be efficient with an acceleration timescale that is a small fraction of the duration of solar flares. Our results suggest that we can use PIC MR simulations to investigate the observational electron energy spectral evolution of solar flares if the ratiot_MR/t_Gis sufficiently small, i.e., ≲10%. 

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5. Conformal Electrodeposition of Antimicrobial Hydrogels Formed by Self‐Assembled Peptide Amphiphiles

   https://doi.org/10.1002/admi.202300046  

   Zaldivar, Gervasio; Feng, Jiachen; Lizarraga, Leonardo; Yu, Yafan; de_Campos, Luana; de_Oliveira, Kelly_Mari_Pires; Piepenbrink, Kurt_H; Conda‐Sheridan, Martin; Tagliazucchi, Mario (April 2023, Advanced Materials Interfaces)

   Abstract The colonization of biomedical surfaces by bacterial biofilms is concerning because these microorganisms display higher antimicrobial resistance in biofilms than in liquid cultures. Developing antimicrobial coatings that can be easily applied to medically‐relevant complex‐shaped objects, such as implants and surgical instruments, is an important and challenging research direction. This work reports the preparation of antibacterial surfaces via the electrodeposition of a conformal hydrogel of self‐assembling cationic peptide‐amphiphiles (PAs). Hydrogels of three PAs are electrodeposited: C₁₆K₂, C₁₆K₃, and C₁₈K₂, where C_nis an alkyl chain ofnmethylene groups and K_mis an oligopeptide ofmlysines. The processing variables (electrodeposition time, potential, pH, salt concentration, agitation) enable fine control of film thickness, demonstrating the flexibility of the method and allowing to unravel the mechanisms underlying electrodeposition. The electrochemically prepared hydrogels inhibit the growth ofStaphylococcus aureus,Escherichia coli, andPseudomonas aeruginosain agar plates, and prevent the formation of biofilms ofAcinetobacter baumanniiandP. aeruginosaand the formation ofA. baumanniicolonies in solid media. C₁₆K₂and C₁₆K₃hydrogels outperform the antimicrobial activity of those of C₁₈K₂while maintaining good compatibility with human cells. 

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