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1. Batrachochytrium salamandrivorans is necronotic: carcasses could play a role in Bsal transmission

   https://doi.org/10.3389/famrs.2024.1284608  

   Carter, E Davis; DeMarchi, Joseph A; Wilber, Mark Q; Miller, Debra L; Gray, Matthew J (February 2024, Frontiers in Amphibian and Reptile Science)

   IntroductionBatrachochytrium salamandrivorans(Bsal) poses a major threat to global amphibian biodiversity. It is essential we understandBsaltransmission to develop better-informed management strategies. Infected carcasses are an important source of transmission for several human and wildlife disease systems; however, they have not been examined as sources forBsalexposure. Here, we evaluated whether infected newt carcasses could contribute toBsaltransmission dynamics. MethodsWe cohoused infected carcasses with susceptible newts in two cohousing chamber types (partitioned or non-partitioned) at three timepoints post-mortem ([0,24[, [24,48, [48,72] hrs). The partitioned chamber prevented newt-to-newt contact hence only allowed indirect, waterborne transmission of zoospores. We measured shedding rates of infected carcasses at each post-mortem timepoint and monitored infection status and mortality of susceptible newts which were exposed during cohousing events. ResultsOur results indicate carcasses are capable of transmittingBsalto susceptible newts up to at least 72 hrs post-mortem, even without live newts directly contacting carcasses. All susceptible newts in each chamber type and post-mortem period became infected and >90% experienced disease-induced mortality.Bsalgenomic copies/uL in skin swabs taken from infected carcasses were high, averaging 7.4x10⁵, 8.6x10⁵, and 2.0x10⁶at 24, 48, and 72 hrs post-mortem, respectively. Water samples collected from cohousing chambers averaged 2743Bsalgenomic copies/uL (approximately 1357 zoospores) and did not decline over 72 hrs. DiscussionOur results indicateBsalinfection can occur rapidly between infected carcasses and susceptible aquatic salamanders via indirect and direct transmission pathways, and carcasses may prolong outbreaks by increasing the duration that infected individuals remain infectious. Carcass removal may be a strategy to reduceBsaltransmission and the impacts of outbreaks. 

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2. Study of the ⁴⁴ Ti(α, p) ⁴⁷ V reaction rate using high-precision ⁵⁰ Cr(p, t) ⁴⁸ Cr measurements

   https://doi.org/10.1088/1742-6596/2586/1/012106  

   Binda, S D; Adsley, P; Long, A M; Berg, G; Brümmer, J W; Couder, M; Görres, J; Kamimota, M; Khumalo, N; Köhne, M; et al (September 2023, Journal of Physics: Conference Series)

   Abstract The abundance and distribution of⁴⁴Ti tells us about the nature of the core-collapse supernovae explosions. There is a need to understand the nuclear reaction network creating and destroying⁴⁴Ti in order to use it as a probe for the explosive mechanism. The⁴⁴Ti(α, p)⁴⁷V reaction is a very important reaction and it controls the destruction of⁴⁴Ti. Difficulties with direct measurements have led to an attempt to study this reaction indirectly. Here, the first step of the indirect study which is the identification of levels of the compound nucleus⁴⁸Cr is presented. A 100-MeV proton beam was incident on a⁵⁰Cr target. States in⁴⁸Cr were populated in the⁵⁰Cr(p, t)⁴⁸Cr reaction. The tritons were momentum-analysed in the K600 Q2D magnetic spectrometer at iThemba LABS. 

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3. Constraining decaying very heavy dark matter from galaxy clusters with 14 year Fermi-LAT data

   https://doi.org/10.1088/1475-7516/2024/03/024  

   Song, Deheng; Murase, Kohta; Kheirandish, Ali (March 2024, Journal of Cosmology and Astroparticle Physics)

   Abstract Galaxy clusters are promising targets for indirect detection of dark matter thanks to the large dark matter content. Using 14 years ofFermi-LAT data from seven nearby galaxy clusters, we obtain constraints on the lifetime of decaying very heavy dark matter particles with masses ranging from 10³GeV to 10¹⁶GeV. We consider a variety of decaying channels and calculate prompt gamma rays and electrons/positrons from the dark matter. Furthermore, we take into account electromagnetic cascades induced by the primary gamma rays and electrons/positrons, and search for the resulting gamma-ray signals from the directions of the galaxy clusters. We adopt a Navarro-Frenk-White profile of the dark matter halos, and use the profile likelihood method to set lower limits on the dark matter lifetime at a 95% confidence level. Our results are competitive with those obtained through other gamma-ray observations of galaxy clusters and provide complementary constraints to existing indirect searches for decaying very heavy dark matter. 

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4. Deep learning inference with the Event Horizon Telescope: I. Calibration improvements and a comprehensive synthetic data library

   https://doi.org/10.1051/0004-6361/202553784  

   Janssen, M; Chan, C-k; Davelaar, J; Natarajan, I; Olivares, H; Ripperda, B; Röder, J; Rynge, M; Wielgus, M (June 2025, Astronomy & Astrophysics)

   Context. In a series of publications, we describe a comprehensive comparison of Event Horizon Telescope (EHT) data with theoretical models of the observed Sagittarius A* (Sgr A^*) and Messier 87* (M87^*) horizon-scale sources. Aims. In this article, we report on improvements made to our observational data reduction pipeline and present the generation of observables derived from the EHT models. We make use of ray-traced general relativistic magnetohydrodynamic simulations that are based on different black hole spacetime metrics and accretion physics parameters. These broad classes of models provide a good representation of the primary targets observed by the EHT. Methods. We describe how we combined multiple frequency bands and polarization channels of the observational data to improve our fringe-finding sensitivity and stabilization of atmospheric phase fluctuations. To generate realistic synthetic data from our models, we took the signal path as well as the calibration process, and thereby the aforementioned improvements, into account. We could thus produce synthetic visibilities akin to calibrated EHT data and identify salient features for the discrimination of model parameters. Results. We have produced a library consisting of an unparalleled 962 000 synthetic Sgr A^*and M87^*datasets. In terms of baseline coverage and noise properties, the library encompasses 2017 EHT measurements as well as future observations with an extended telescope array. Conclusions. We differentiate between robust visibility data products related to model features and data products that are strongly affected by data corruption effects. Parameter inference is mostly limited by intrinsic model variability, which highlights the importance of long-term monitoring observations with the EHT. In later papers in this series, we will show how a Bayesian neural network trained on our synthetic data is capable of dealing with the model variability and extracting physical parameters from EHT observations. With our calibration improvements, our newly reduced EHT datasets have a considerably better quality compared to previously analyzed data. 

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5. Influences of Recent Particle Formation on Southern Ocean Aerosol Variability and Low Cloud Properties

   https://doi.org/10.1029/2020JD033529  

   McCoy, Isabel L.; Bretherton, Christopher S.; Wood, Robert; Twohy, Cynthia H.; Gettelman, Andrew; Bardeen, Charles G.; Toohey, Darin W. (April 2021, Journal of Geophysical Research: Atmospheres)

   Abstract Controls on pristine aerosol over the Southern Ocean (SO) are critical for constraining the strength of global aerosol indirect forcing. Observations of summertime SO clouds and aerosols in synoptically varied conditions during the 2018 SOCRATES aircraft campaign reveal novel mechanisms influencing pristine aerosol‐cloud interactions. The SO free troposphere (3–6 km) is characterized by widespread, frequent new particle formation events contributing to much larger concentrations (≥1,000 mg⁻¹) of condensation nuclei (diameters > 0.01 μm) than in typical sub‐tropical regions. Synoptic‐scale uplift in warm conveyor belts and sub‐polar vortices lifts marine biogenic sulfur‐containing gases to free‐tropospheric environments favorable for generating Aitken‐mode aerosol particles (0.01–0.1 μm). Free‐tropospheric Aitken particles subside into the boundary layer, where they grow in size to dominate the sulfur‐based cloud condensation nuclei (CCN) driving SO cloud droplet number concentrations (N_d ∼ 60–100 cm⁻³). Evidence is presented for a hypothesized Aitken‐buffering mechanism which maintains persistently high summertime SON_dagainst precipitation removal through CCN replenishment from activation and growth of boundary layer Aitken particles. Nudged hindcasts from the Community Atmosphere Model (CAM6) are found to underpredict Aitken and accumulation mode aerosols andN_d, impacting summertime cloud brightness and aerosol‐cloud interactions and indicating incomplete representations of aerosol mechanisms associated with ocean biology. 

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