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Abstract
The heaviest chemical elements are naturally produced by the rapid neutron-capture process (r-process) during neutron star mergers or supernovae. The r-process production of elements heavier than uranium (transuranic nuclei) is poorly understood and inaccessible to experiments so must be extrapolated by using nucleosynthesis models. We examined element abundances in a sample of stars that are enhanced in r-process elements. The abundances of elements ruthenium, rhodium, palladium, and silver (atomic numbers Z = 44 to 47; mass numbers A = 99 to 110) correlate with those of heavier elements (63 <= Z <= 78, A > 150). There is no correlation for neighboring elements (34 <= Z <= 42 and 48 <= Z <= 62). We interpret this as evidence that fission fragments of transuranic nuclei contribute to the abundances. Our results indicate that neutron-rich nuclei with mass numbers >260 are produced in r-process events.
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Abstract
The detection of the merger of a neutron star binary in both gravitational waves and a broad spectrum of electromagnetic waves (GW170817) provided the most compelling evidence to date that such mergers produce heavy r-process elements. The inferred rate of these mergers coupled to the estimated r-process production suggests that these mergers could produce nearly all of the r-process elements in the universe. However, uncertainties in the merger rate and the amount of r-process production per merger means that scientists can not constrain the fraction of the merger r-process contribution to better than 1-100% of the total amount in the universe. The total r-process mass synthesized is best constrained by the observations themselves and uncertainties in the inferred production quantity follows from the uncertainties in modeling the emission from the NSM ejecta. In this paper, we review these modeling uncertainties.
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Abstract
We present a detailed chemical-abundance analysis of a highly r-process-enhanced (RPE) star, 2MASS J00512646-1053170, using high-resolution spectroscopic observations with Hubble Space Telescope/STIS in the UV and Magellan/MIKE in the optical. We determined abundances for 41 elements in total, including 23 r-process elements and rarely probed species such as Al ii, Ge i, Mo ii, Cd i, Os ii, Pt i, and Au i. We find that [Ge/Fe] = +0.10, which is an unusually high Ge enhancement for such a metal-poor star and indicates contribution from a production mechanism decoupled from that of Fe. We also find that this star has the highest Cd abundance observed for a metal-poor star to date. We find that the dispersion in the Cd abundances of metal-poor stars can be explained by the correlation of Cd i abundances with the stellar parameters of the stars, indicating the presence of NLTE effects. We also report that this star is now only the sixth star with Au abundance determined. This result, along with abundances of Pt and Os, uphold the case for the extension of the universal r-process pattern to the third r-process peak and to Au. This study adds to the sparse but growing number of RPE stars with extensive chemical-abundance inventories and highlights the need for not only more abundance determinations of these rarely probed species, but also advances in theoretical NLTE and astrophysical studies to reliably understand the origin of r-process elements.
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Abstract
Insulin antibody syndrome (IAS), also known as Hirata disease, is a rare condition characterized by spontaneous hypoglycemic episodes unrelated to exogenous insulin exposure. It is caused by elevated serum levels of insulin autoantibodies (IAA). IAS typically occurs when a triggering factor, such as medication or viral infection, interacts with a predisposing genetic background. Diagnosing IAS is challenging due to its rarity and the presence of multiple potential causes for hyperinsulinemic hypoglycemia. The presence of Whipple triad-symptoms of hypoglycemia, low plasma glucose concentration, and relief of symptoms after raising plasma glucose-strongly supports the diagnosis of IAS. However, the detection of IAA is considered the most reliable test. Timely diagnosis can facilitate appropriate treatment and prevent unnecessary imaging studies and invasive procedures, thereby reducing costs. Currently, no definitive guidelines exist for managing IAS. Most management strategies involve supportive measures due to the high rate of spontaneous remission, with hypoglycemia often managed through dietary interventions. However, a few medications have shown benefit. Although predominantly observed in the Japanese population, IAS cases have been reported in other ethnicities, including Caucasians. This report presents a unique case of IAS in an African American male.
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Abstract
A stylized macro-scale energy model of least-cost electricity systems relying only on wind and solar generation was used to assess the value of different storage technologies, individually and combined, for the contiguous U.S. as well as for four geographically diverse U.S. load-balancing regions. For the contiguous U.S. system, at current costs, when only one storage technology was deployed, hydrogen energy storage produced the lowest system costs, due to its energy-capacity costs being the lowest of all storage technologies modeled. Additional hypothetical storage technologies were more cost-competitive than hydrogen (long-duration storage) only at very low energy-capacity costs, but they were more cost-competitive than Li-ion batteries (short-duration storage) at relatively high energy- and power-capacity costs. In all load-balancing regions investigated, the least-cost systems that included long-duration storage had sufficient energy and power capacity to also meet short-duration energy and power storage needs, so that the addition of short-duration storage as a second storage technology did not markedly reduce total system costs. Thus, in electricity systems that rely on wind and solar generation, contingent on social and geographic constraints, long-duration storage may cost-effectively provide the services that would otherwise be provided by shorter-duration storage technologies.
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Abstract
Plants often adapt to adverse or stress conditions via differential growth. The trans-Golgi network (TGN) has been implicated in stress responses, but it is not clear in what capacity it mediates adaptive growth decisions. In this study, we assess the role of the TGN in stress responses by exploring the previously identified interactome of the Transport Protein Particle II (TRAPPII) complex required for TGN structure and function. We identified physical and genetic interactions between AtTRAPPII and shaggy-like kinases (GSK3/AtSKs) and provided in vitro and in vivo evidence that the TRAPPII phosphostatus mediates adaptive responses to abiotic cues. AtSKs are multifunctional kinases that integrate a broad range of signals. Similarly, the AtTRAPPII interactome is vast and considerably enriched in signaling components. An AtSK-TRAPPII interaction would integrate all levels of cellular organization and instruct the TGN, a central and highly discriminate cellular hub, as to how to mobilize and allocate resources to optimize growth and survival under limiting or adverse conditions.
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Abstract
Throughout history, humans have relied on plants as a source of medication, flavoring, and food. Plants synthesize large chemical libraries and release many of these compounds into the rhizosphere and atmosphere where they affect animal and microbe behavior. To survive, nematodes must have evolved the sensory capacity to distinguish plant-made small molecules (SMs) that are harmful and must be avoided from those that are beneficial and should be sought. This ability to classify chemical cues as a function of their value is fundamental to olfaction and represents a capacity shared by many animals, including humans. Here, we present an efficient platform based on multiwell plates, liquid handling instrumentation, inexpensive optical scanners, and bespoke software that can efficiently determine the valence (attraction or repulsion) of single SMs in the model nematode, Caenorhabditis elegans. Using this integrated hardware-wetware-software platform, we screened 90 plant SMs and identified 37 that attracted or repelled wild-type animals but had no effect on mutants defective in chemosensory transduction. Genetic dissection indicates that for at least 10 of these SMs, response valence emerges from the integration of opposing signals, arguing that olfactory valence is often determined by integrating chemosensory signals over multiple lines of information. This study establishes that C. elegans is an effective discovery engine for determining chemotaxis valence and for identifying natural products detected by the chemosensory nervous system.
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Abstract
Cellular mechanisms responsible for the regulation of nutrient exchange, immune responses, and symbiont population growth in the cnidarian-dinoflagellate symbiosis are poorly resolved, particularly with respect to the dinoflagellate symbiont. Here, we characterised proteomic changes in the native symbiont Breviolum minutum during colonisation of its host sea anemone Exaiptasia diaphana ("Aiptasia"). We also compared the proteome of this native symbiont in the established symbiotic state with that of a non-native symbiont, Durusdinium trenchii. The onset of symbiosis between Aiptasia and Branchioglossum minutum increased accumulation of symbiont proteins associated with acquisition of inorganic carbon and photosynthesis, nitrogen metabolism, micro- and macronutrient starvation, suppression of host immune responses, tolerance to low pH, and management of oxidative stress. Such responses are consistent with a functional, persistent symbiosis. In contrast, D. trenchii predominantly showed elevated levels of immunosuppressive proteins, consistent with the view that this symbiont is an opportunist that forms a less beneficial, less well-integrated symbiosis with this model anemone. By adding symbiont analysis to the already known responses of the host proteome, our results provide a more holistic view of cellular processes that determine host-symbiont specificity and how differences in symbiont partners (i.e., native versus non-native symbionts) may impact the fitness of the cnidarian-dinoflagellate symbiosis.
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Abstract
The influential concept of the rare biosphere in microbial ecology has underscored the importance of taxa occurring at low abundances yet potentially playing key roles in communities and ecosystems. Here, we refocus the concept of rare biosphere through a functional trait-based lens and provide a framework to characterize microbial functional rarity, a combination of numerical scarcity across space or time and trait distinctiveness. We demonstrate how this novel interpretation of the rare biosphere, rooted in microbial functions, can enhance our mechanistic understanding of microbial community structure. It also sheds light on functionally distinct microbes, directing conservation efforts towards taxa harboring rare yet ecologically crucial functions.
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Abstract
This study presents a comprehensive analysis of a two-patch, two-life stage SI model without recovery from infection, focusing on the dynamics of disease spread and host population viability in natural populations. The model, inspired by real-world ecological crises like the decline of amphibian populations due to chytridiomycosis and sea star populations due to Sea Star Wasting Disease, aims to understand the conditions under which a sink host population can present ecological rescue from a healthier, source population. Mathematical and numerical analyses reveal the critical roles of the basic reproductive numbers of the source and sink populations, the maturation rate, and the dispersal rate of juveniles in determining population outcomes. The study identifies basic reproduction numbers R0\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$R_0$$\end{document} for each of the patches, and conditions for the basic reproduction numbers to produce a receiving patch under which its population. These findings provide insights into managing natural populations affected by disease, with implications for conservation strategies, such as the importance of maintaining reproductively viable refuge populations and considering the effects of dispersal and maturation rates on population recovery. The research underscores the complexity of host-pathogen dynamics in spatially structured environments and highlights the need for multi-faceted approaches to biodiversity conservation in the face of emerging diseases.
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