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We study finite-volume (FV) corrections to determinations of $g_A$ via lattice quantum chromodynamics (QCD) using analytic results and numerical analysis. We observe that $SU\left(2\right)$ heavy Baryon chiral perturbation theory does not provide an unambiguous prediction for the sign of the FV correction, which is not surprising when one also considers large- $N_c$ constraints on the axial couplings. We further show that nonmonotonic FV corrections are naturally allowed when one considers either including explicit $\mathrm{\Delta }$ -resonance degrees of freedom or one works to higher orders in the chiral expansion. We investigate the potential impact of these FV corrections with a precision study of $g_A$ using models of FV corrections that are monotonic and nonmonotonic. Using lattice QCD data that is approximately at the 1% level of precision, we do not see significant evidence of nonmonotonic corrections. Looking forward to the next phase of lattice QCD calculations, we estimate that calculations that are between the 0.1% and 1% level of precision may be sensitive to these FV artifacts. Finally, we present an update of the CalLat prediction of $g_A$ in the isospin limit with subpercent precision, $g_A^{\mathrm{QCD}}=1.2674\left(96\right)$ . 

Redox-sensitive elements figure prominently in studies of the evolution of Earth’s surface redox state, including the first major rise in atmospheric O₂, the Paleoproterozoic Great Oxidation Event. Most Precambrian rocks endured multistage tectonothermal histories, however, adding ambiguity to interpretation of their chemistry. Here, we apply U-Th-Pb isotope geochronology to the highly oxidized ~2.06 Ga Kuetsjärvi Volcanic Formation, Pechenga Greenstone Belt, Russia, to constrain the age and extent of U oxidation. By contrasting the relative mobility of U and Th using Pb isotopes, we find that complete to near-complete oxidation and removal of U occurred shortly after eruption. We argue that this likely indicates relatively high atmospheric O₂, where oxidative weathering and alteration produced a global pulse of U to the oceans. Such a pulse could explain widespread shifts in the U-Th-Pb isotope character of mantle reservoirs at ~2 Ga, including a decrease in the²³²Th/²³⁸U ratio of the mid-ocean ridge basalt source and inception of the high-²³⁸U/²⁰⁴Pb (HIMU) source to ocean island basalts, underscoring the connections between the redox character of the Paleoproterozoic surface and deep Earth. Using²⁰⁷Pb-²⁰⁶Pb,²³⁸U-²⁰⁶Pb,²³⁵U-²⁰⁷Pb, and²³²Th-²⁰⁸Pb geochronology, ~2.06 Ga oxidative loss of U may be distinguished from reintroduction of U at ~1.8 Ga during regional metamorphism, as well as Pb loss during a Phanerozoic tectonothermal event. Our results therefore establish the complex history of redox-sensitive element behavior in the rocks, highlighting the fact that elemental abundances, by themselves, are unlikely to capture straightforward proxy information in rocks that have seen multistage geologic histories. 

Abstract Young pre-main sequence stars exhibit elevated X-ray levels due to their strong magnetic activity. Understanding young stars’ X-ray activity is essential for contextualizing the forming planets that they host. Binary stars present a unique environment that may influence planet formation and evolution. In this work, we assembled a sample of 65 systems with stellar characterization from the literature and X-ray fluxes from the XMM-Newton Extended Survey of the Taurus Molecular Cloud to investigate the potential relationship between binary separation and X-ray flux. We found that binary stars with separations smaller than the sample median may exhibit elevated X-ray flux compared to single stars. This suggests that binary companions could influence stellar and planetary evolution and warrants further investigation. 

We perform a high-statistics lattice QCD calculation of the low-energy two-nucleon scattering amplitudes. To address discrepancies in the literature, the calculation is performed at a heavy pion mass in the limit that the light quark masses are equal to the physical strange quark mass, $m_{\pi }=m_K\simeq 714\mathrm{MeV}$ . Using a state-of-the-art momentum space method, we rule out the presence of a bound di-nucleon in both the isospin 0 (deuteron) and 1 (di-neutron) channels, in contrast with many previous results that made use of compact hexaquark creation operators. To diagnose the discrepancy, we add such hexaquark interpolating operators to our basis and find that they do not affect the determination of the two-nucleon finite-volume spectrum, and thus they do not couple to deeply bound di-nucleons that are missed by the momentum-space operators. Furthermore, we perform a high-statistics calculation of the HAL QCD potential on the same gauge ensembles and find qualitative agreement with our main results. We conclude that di-nucleons do not form bound states at heavy pion masses and that previous identification of deeply bound di-nucleons must have arisen from a misidentification of the spectrum from off-diagonal elements of a correlation function. 

Interpreters who are skilled in interpreting science, technology, engineering, and mathematics (STEM) content fluently and accurately are few and far between. This issue is particularly true at the post-secondary level. Those interpreters who are available often do not have command of the vocabulary needed to interpret more specialized content and rely heavily on letter-for-letter fingerspelling and word-for-word transliteration. This project looked at the knowledge of the principles of fingerspelling on undergraduate student interpreters’ ability to interpret typical introductory biology lecture material accurately and fluently. Research involved modifying a signing bioscience dictionary (SBD), developing life science content summaries, creating videos of fingerspelling principles, and conducting an evaluation. Key findings showed participants’ knowledge of bioscience vocabulary was significantly improved with use of the SBD and that their ability to interpret typical biology lecture material fluently and accurately improved. After watching the videos and learning to apply the principles of fingerspelling, their fingerspelling scores also improved significantly. However, there was no significant improvement in biology content knowledge.