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ABSTRACT ObjectiveEstuarine fishes experience significant diel and seasonal variations in their environments, with climate change introducing additional stressors, including altered salinity, temperatures, and water levels. American Eels Anguilla rostrata are present in Atlantic estuaries from Venezuela to Greenland. Despite their wide distribution and shrinking population, American Eels are understudied, in part because of the research challenges posed by their unusual catadromous life history. This study examines the spatial effects of changing estuarine water quality variables (water temperature, dissolved oxygen, and salinity) on the American Eel population in the Hudson River estuary (HRE). MethodsThe Hudson River Biological Monitoring Program, conducted from 1974 to 2017, consists of a suite of surveys recording fish abundance data and water quality variables. As the largest component of the Hudson River Biological Monitoring Program, the Long River Ichthyoplankton Survey contains 44 years of data on American Eels in the HRE. Using LRS catch data and Hudson River Biological Monitoring Program water quality measurements, we developed statistical models of American Eel population centers in the HRE. ResultsThe young-of-year and yearling-or-older population centers shifted downstream over the course of the Long River Ichthyoplankton Survey at average rates of approximately 1.1 and 0.41 km per year, respectively, despite higher temperatures and lower dissolved oxygen conditions closer to the estuary’s mouth. Mean water temperature and dissolved oxygen for the entire estuary have significant relationships with the population centers of both age-classes, although the eels were not apparently tracking stable conductivity or water temperature conditions; nor were the young of year tracking stable dissolved oxygen levels. ConclusionsThe downstream shift in HRE American Eel population centers over several decades and the relationship between this shift and changing environmental conditions indicate the need for improved understanding of the population dynamics of the globally distributed and declining species of the genus Anguilla. This knowledge is critical in the face of rapidly changing ecosystems. 

Abstract Understanding how extreme weather, such as tropical cyclones, will change with future climate warming is an interesting computational challenge. Here, the hindcast approach is used to create different storylines of a particular tropical cyclone, Hurricane Irma (2017). Using the community atmosphere model, we explore how Irma’s precipitation would change under various levels of climate warming. Analysis is focused on a 48 h period where the simulated hurricane tracks reasonably represent Irma’s observed track. Under future scenarios of 2 K, 3 K, and 4 K global average surface temperature increase above pre-industrial levels, the mean 3-hourly rainfall rates in the simulated storms increase by 3–7% K⁻¹compared to present. This change increases in magnitude for the 95th and 99th percentile 3-hourly rates, which intensify by 10–13% K⁻¹and 17–21% K⁻¹, respectively. Over Florida, the simulated mean rainfall accumulations increase by 16–26% K⁻¹, with local maxima increasing by 18–43% K⁻¹. All percent changes increase monotonically with warming level. 

Abstract The dimmest and most numerous outlier of the Type Ia supernova population, the Type Iax event, is increasingly being found in the results of observational campaigns. There is currently no single accepted model to describe these events. This 2D study explores the viability of modeling Type Iax events as a hybrid C/O/Ne white dwarf progenitor undergoing a deflagration using the multiphysics software FLASH. This hybrid was created using the stellar evolution code MESA, and its C-depleted core and mixed structure have demonstrated lower yields than traditional C/O progenitors in previous deflagration-to-detonation studies. To generate a sample, 30 “realizations” of this simulation were performed, the only difference being the shape of the initial match head used to start the deflagration. Consistent with earlier work, these realizations produce the familiar hot dense bound remnant surrounded by sparse ejecta. Our results indicate that the majority of the star remains unburned (∼70%) and bound (>90%). Our realizations produce total ejecta yields on the order of 10⁻²–10⁻¹M_☉, ejected⁵⁶Ni yields on the order of 10⁻⁴–10⁻²M_☉, and ejecta kinetic energies on the order of 10⁴⁸–10⁴⁹erg. Compared to yields inferred from recent observations of the dimmest Type Iax events—SN 2007qd, SN 2008ha, SN 2010ae, SN 2019gsc, SN 2019muj, SN 2020kyg, and SN 2021fcg—our simulation produces comparable⁵⁶Ni yields but too-small total yields and kinetic energies. Reignition of the remnant is also seen in some realizations. 

Identity Activism is a new phenomenon afforded by the massive popularity of social media. It consists of the prominent display of a social movement symbol within a space reserved for description of the self. The 2022 Russian invasion of Ukraine provides a contemporary (yet unfortunate) opportunity to observe this phenomenon. Here, we introduce and explore this concept in the context of the recent Twitter trend of displaying the Ukraine flag emoji in bios and names to signal support of Ukraine. We explore several questions, including: how has the popularity of this trend changed over time, are users who display the flag more likely to be connected to others who do, and what types of users are and are not participating. We find that Ukraine flag emoji prevalence in both names and bios increased many-fold in late February 2022, with it becoming the 11th most prevalent emoji in bios and the 3rd most prevalent emoji in names during March. We also find evidence that users who display the flag in their bio or name are more likely to follow and be followed by others who also do so, as compared to users who do not. Finally, we observe that users who share politically left-leaning messages were most likely to display the emoji. Those who share account information from alternative social media sites and non-personal accounts appear least likely. These findings give us insight into how users participate in Identity Activism, what connections exist between participating users, and, in this particular case, what types of users participate.