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Single-frequency emission from an accretion disk around a black hole is broadened into a line profile due to gravitational redshift and the motion of the disk's particles relative to the observer. The ensemble of relativistically broadened emission frequencies from the disk elements forms the spectrum viewed by an observer. Over the past decades, the broadened spectra of accreting systems have been used to constrain the spin of the black hole, the observer's inclination, and the astrophysical model parameters of the system. These inferences are usually made under the assumption that the accretion disk consists of particles orbiting around the black hole on stable circular orbits in the equatorial plane. Under this Standard disk model, in this work, we revisit line profile morphology, i.e., its extent, kinks, and fall-off. We provide a unified analytical explanation for these line profile morphological features, which encode the black hole spin, viewing inclination, and locations of the disk's inner and outer edges. We then show that these features, however, are model-dependent, by parametrically relaxing some of the astrophysical assumptions. In particular, we explore how allowing the disk particles to deviate from stable circular orbits rapidly degenerates the characteristic features of the line profile under the Standard disk model. Our results further demonstrate how sensitive our understanding of black hole and system properties can be to assumptions we make when interpreting these types of measurements., Comment: 27 pages, 11 figures

The standardization of an interface for dense linear algebra operations in the BLAS standard has enabled interoperability between different linear algebra libraries, thereby boosting the success of scientific computing, in particular in scientific HPC. Despite numerous efforts in the past, the community has not yet agreed on a standardization for sparse linear algebra operations due to numerous reasons. One is the fact that sparse linear algebra objects allow for many different storage formats, and different hardware may favor different storage formats. This makes the definition of a FORTRAN-style all-circumventing interface extremely challenging. Another reason is that opposed to dense linear algebra functionality, in sparse linear algebra, the size of the sparse data structure for the operation result is not always known prior to the information. Furthermore, as opposed to the standardization effort for dense linear algebra, we are late in the technology readiness cycle, and many production-ready software libraries using sparse linear algebra routines have implemented and committed to their own sparse BLAS interface. At the same time, there exists a demand for standardization that would improve interoperability, and sustainability, and allow for easier integration of building blocks. In an inclusive, cross-institutional effort involving numerous academic institutions, US National Labs, and industry, we spent two years designing a hardware-portable interface for basic sparse linear algebra functionality that serves the user needs and is compatible with the different interfaces currently used by different vendors. In this paper, we present a C++ API for sparse linear algebra functionality, discuss the design choices, and detail how software developers preserve a lot of freedom in terms of how to implement functionality behind this API., Comment: 43 pages

We survey the combinatorics of the Adinkra, a graphical device for solving differential equations in supersymmetry. These graphs represent an exceptional class of 1-factorizations with further augmentations. As a new feature, we characterize Adinkras using Latin rectangles., Comment: 19 pages, 11 figures

Materials that possess a porous and defected structure can have a range of useful properties that are sought after, which include their tolerance to nuclear radiation, ability to efficiently store and release isotopes, to immobilize nuclear waste, and to exhibit phase stability even at elevated temperatures. Since nanoscale pores and surface structures can serve as sinks for radiation-induced amorphization, one dimensional (1D) porous nanorods due to their high surface-to-volume ratio have the potential for use as advanced materials in nuclear science applications. In this study, we demonstrate a synthesis and a detailed analysis of microporous 1D octahedral molecular sieves of disodium diniobate hydrate (Na2Nb2O6 H2O) or Sandia Octahedral Molecular Sieves (SOMS). In addition, the stability of these SOMS is evaluated following their exposure to elevated temperatures and neutron irradiation. A surfactant-assisted solvothermal method is used to prepare these SOMS-based nanorods. This relatively low temperature, solution-phase approach can form crystalline nanorods of microporous Na2Nb2O6 H2O. These 1D structures had an average diameter of approximately 50 nm and lengths greater than 1 micrometer. The nanorods adopted a defected microporous phase, which also exhibited a resistance to radiation induced amorphization. The dimensions, phase, and crystallinity of the SOMS-based nanorods after exposure to a high incident flux of neutrons were comparable to those of the as-synthesized products. The radiation tolerance of these microporous SOMS could be useful in the design of materials for nuclear reactors, resilient nuclear fuels, thermally resilient materials, high temperature catalysts, and durable materials for the handling and storage of radioactive waste., Comment: 38 pages, 17 figures

The spin structure functions of the proton and the deuteron were measured during the EG4 experiment at Jefferson Lab in 2006. Data were collected for longitudinally polarized electron scattering off longitudinally polarized NH$_3$ and ND$_3$ targets, for $Q^2$ values as small as 0.012 and 0.02 GeV$^2$, respectively, using the CEBAF Large Acceptance Spectrometer (CLAS). This is the archival paper of the EG4 experiment that summaries the previously reported results of the polarized structure functions $g_1$, $A_1F_1$, and their moments $\overline \Gamma_1$, $\overline \gamma_0$, and $\overline I_{TT}$, for both the proton and the deuteron. In addition, we report on new results on the neutron $g_1$ extracted by combining proton and deuteron data and correcting for Fermi smearing, and on the neutron moments $\overline \Gamma_1$, $\overline \gamma_0$, and $\overline I_{TT}$ formed directly from those of the proton and the deuteron. Our data are in good agreement with the Gerasimov-Drell-Hearn sum rule for the proton, deuteron, and neutron. Furthermore, the isovector combination was formed for $g_1$ and the Bjorken integral $\overline \Gamma_1^{p-n}$, and compared to available theoretical predictions. All of our results provide for the first time extensive tests of spin observable predictions from chiral effective field theory ($\chi$EFT) in a $Q^2$ range commensurate with the pion mass. They motivate further improvement in $\chi$EFT calculations from other approaches such as the lattice gauge method., Comment: 33 pages. 26 figures. Data table provided in supplementary material (30 pages)

Nonlinear optics at the nanoscale has emerged as a sought-after platform for sensing and imaging applications. The development of these materials is having an impact on fields that include advanced information technology, signal processing circuits, and cryptography. Lithium tantalate (LiTaO3) is an attractive nonlinear optical material due to its high optical damage threshold (e.g., tolerance to greater than 500 MW per cm^2 from a nanosecond pulsed laser) and broad range of ultraviolet-visible (UV-Vis) transparency relative to many other nonlinear optical materials. Despite many synthetic reports on metal oxides, very little is known about the preparation of uniform, crystalline LiTaO3 nanoparticles (NPs) of a pure phase, as well as details on their mechanism of nucleation and growth. In this article, we introduce a solution-phase method for the preparation of LiTaO3 NPs with tunable dimensions. This solution-phase process results in the formation of crystalline, uniform NPs of LiTaO3 of a pure phase when carried out at 220 C. This method can prepare crystalline LiTaO3 NPs without the need for further heat treatment or the use of an inert atmosphere. Results presented herein also provide insights into the growth mechanism of these NPs. The reaction included the processes of oriented attachment and Ostwald ripening. The results of our study also indicate that the growth of the LiTaO3 NPs was a result of a size focusing effect, which enables the ability to tune their diameters from 200 to 500 nm. The crystalline NPs were optically active towards second harmonic generation. These studies deepen our understanding of the methods by which NPs can be prepared from metal oxides. These studies specifically demonstrate the preparation of optically active LiTaO3 NPs of uniform and controllable dimensions that could be used in a broad range of fundamental studies and applications in nanophotonics., Comment: 36 pages, 13 figures

Adinkras are graphical representations of the gauge invariant field components in supersymmetric theories and their orbits under the action of supersymmetry (SUSY) generators in the context of supermultiplets. A discussion is given that provides a thorough review of the concepts of holoraumy, permutahedra, and gadgets. One consequence of these concepts, the additional concept of hopper operators, is discussed. These play a particularly important role that ignites the processes needed for the study of adinkras related to minimal 4D, $\cal N$ = 1 supermultiplets (chiral, vector, tensor and complex linear supermultiplets) through the prism of very simple cellular automata following Wolfram's `New Kind of Science' paradigm., Comment: 54 pages, 18 figures

The $^{244}$Pu($^{50}$Ti,$xn$)$^{294-x}$Lv reaction was investigated at Lawrence Berkeley National Laboratory's 88-Inch Cyclotron facility. The experiment was aimed at the production of a superheavy element with $Z\ge 114$ by irradiating an actinide target with a beam heavier than $^{48}$Ca. Produced Lv ions were separated from the unwanted beam and nuclear reaction products using the Berkeley Gas-filled Separator and implanted into a newly commissioned focal plane detector system. Two decay chains were observed and assigned to the decay of $^{290}$Lv. The production cross section was measured to be $\sigma_{\rm prod}=0.44(^{+58}_{-28})$~pb at a center-of-target center-of-mass energy of 220(3)~MeV. This represents the first published measurement of the production of a superheavy element near the `Island-of-Stability', with a beam of $^{50}$Ti and is an essential precursor in the pursuit of searching for new elements beyond $Z=118$., Comment: Submitted to Physical Review Letters

A re-imagining of the supergravity prepotential formulation of 4D, $\cal N$ = 1 supergravity and its Salam-Strathdee superfield superconformal gauge group is presented.

Measuring Deeply Virtual Compton Scattering on the neutron is one of the necessary steps to understand the structure of the nucleon in terms of Generalized Parton Distributions (GPDs). Neutron targets play a complementary role to transversely polarized proton targets in the determination of the GPD $E$. This poorly known and poorly constrained GPD is essential to obtain the contribution of the quarks' angular momentum to the spin of the nucleon. DVCS on the neutron was measured for the first time selecting the exclusive final state by detecting the neutron, using the Jefferson Lab longitudinally polarized electron beam, with energies up to 10.6 GeV, and the CLAS12 detector. The extracted beam-spin asymmetries, combined with DVCS observables measured on the proton, allow a clean quark-flavor separation of the imaginary parts of the GPDs $H$ and $E$., Comment: 7 pages, 6 figures

We demonstrate a sapphire machining process integrated with intermediate-scale quantum processors. The process allows through-substrate electrical connections, necessary for low-frequency mode-mitigation, as well as signal-routing, which are vital as quantum computers scale in qubit number, and thus dimension. High-coherence qubits are required to build fault-tolerant quantum computers and so material choices are an important consideration when developing a qubit technology platform. Sapphire, as a low-loss dielectric substrate, has shown to support high-coherence qubits. In addition, recent advances in material choices such as tantalum and titanium-nitride, both deposited on a sapphire substrate, have demonstrated qubit lifetimes exceeding 0.3 ms. However, the lack of any process equivalent of deep-silicon etching to create through-substrate-vias in sapphire, or to inductively shunt large dies, has limited sapphire to small-scale processors, or necessitates the use of chiplet architecture. Here, we present a sapphire machining process that is compatible with high-coherence qubits. This technique immediately provides a means to scale QPUs with integrated mode-mitigation, and provides a route toward the development of through-sapphire-vias, both of which allow the advantages of sapphire to be leveraged as well as facilitating the use of sapphire-compatible materials for large-scale QPUs., Comment: 9 pages, 6 figures

Amid growing concerns over AI's societal risks--ranging from civilizational collapse to misinformation and systemic bias--this study explores the perceptions of AI experts and the general US registered voters on the likelihood and impact of 18 specific AI risks, alongside their policy preferences for managing these risks. While both groups favor international oversight over national or corporate governance, our survey reveals a discrepancy: voters perceive AI risks as both more likely and more impactful than experts, and also advocate for slower AI development. Specifically, our findings indicate that policy interventions may best assuage collective concerns if they attempt to more carefully balance mitigation efforts across all classes of societal-scale risks, effectively nullifying the near-vs-long-term debate over AI risks. More broadly, our results will serve not only to enable more substantive policy discussions for preventing and mitigating AI risks, but also to underscore the challenge of consensus building for effective policy implementation., Comment: 9 pages, 18 page supplementary materials

The global scientific landscape emerges from a complex interplay of collaboration and competition, where nations vie for dominance while simultaneously fostering the diffusion of knowledge on a global scale. This raises crucial questions: What underlying patterns govern international scientific recognition and influence? How does this structure impact knowledge dissemination? Traditional models view the global scientific ecosystem through a core-periphery lens, with Western nations dominating knowledge production. Here, we investigate the dynamics of international scientific recognition through the lens of national preferences, introducing a novel signed measure to characterize national citation preferences and enabling a network analysis of international scientific recognition. We find that scientific recognition is related to cultural and political factors in addition to economic strength and scientific quality. Our analysis challenges the conventional core-periphery narrative, uncovering instead several communities of international knowledge production that are rapidly fragmenting the scientific recognition ecosystem. Moreover, we provide compelling evidence that this network significantly constrains the diffusion of ideas across international borders. The resulting network framework for global scientific recognition sheds light on the barriers and opportunities for collaboration, innovation, and the equitable recognition of scientific advancements, with significant consequences for policymakers seeking to foster inclusive and impactful international scientific endeavors., Comment: 30 pages (main text), 3 figures (main text), 1 table (main text), 20 SI pages