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Medium-range structure at a length scale between ~0.5 and 3 nm strongly influences the properties and phase transformations of metallic glass alloys. Electron diffraction methods based on four-dimensional scanning transmission electron microscopy are well suited for characterizing such structure using nanodiffraction with beams matched in size to the length scale of interest. Structural characterization using techniques including fluctuation electron microscopy, Ångström-beam electron diffraction, and angular correlation mapping have revealed widespread competition between crystalline and noncrystalline order, structural motifs responsible for crystallization and glass formation, and length scales controlling plasticity. Time-resolved, in situ electron correlation microscopy has demonstrated spatially heterogeneous dynamics in supercooled liquids and glasses and has hinted at connections between structure and atomic motions. Continued advances in techniques, sources, and detectors offer prospects for more discoveries to come. 

A high-resolution polarimetric spectroscopy diagnostic is developed to provide a quantitative characterization of the plasma density and magnetic field structures of magnetically driven plasma jets generated in Caltech magnetohydrodynamic jet experiments. The diagnostic distinguishes elliptically polarized emission components by the Zeeman effect and measures the Stark broadening of the Ar II 480.602 nm spectral line [3s23p4(3P)4s 4P5/2–3s23p4(3P)4p 4P5/2°] with sub-millimeter and sub-microsecond resolution, enabling reconstruction of radial profiles of plasma density and vector magnetic fields across the axially uniform jet column. A model incorporating spectroscopic effects, line integration, and a multi-parameter plasma description reconstructs the spectra collected by 128 channels of an optical fiber system. A Markov chain Monte Carlo method inferred model parameters of plasma density, poloidal magnetic flux, and poloidal electric current by minimizing the difference between synthetic and measured data. A comparison with a non-linear regression analysis without model constraints confirmed that the densities obtained directly from line-integrated spectra underestimate the actual local density. The splitting of wavelengths in a polarimetric system is in accordance with the Zeeman effect. The observations show that the classic pinch force is inadequate to balance the radial pressure gradient force. Instead, the pressure gradient force is balanced by a Bernoulli-like inward radial force associated with a stagnating inward radial E×B velocity. 

This study examines how experts who use advanced artificial intelligence (AI) technologies that generate highly detailed and realistic representations can create what we term “artificial certainty,” which we define as the illusion that complex future outcomes are definitively knowable, even though they are inherently uncertain. Through a comparative study of two urban planning organizations using the same AI simulation tool, we show how this artificial certainty emerges from the ways process experts create and deploy AI-generated representations. The findings reveal three interconnected representational practices that shape how laypeople perceive the certainty of a representation: controlling the level of detail, shaping stakeholder engagement, and constructing the model’s meaning. We find that when process experts emphasize enhancement—amplifying technological capabilities within these practices—stakeholders mistake representations for reality, undermining expert authority. Conversely, when process experts engage in modulation—tempering how AI outputs are presented and integrated into decision making—they preserve the authority necessary to keep uncertainty alive. These findings reconceptualize process expertise as a distinct form of interpretive work that helps maintain useful levels of uncertainty in the face of growing pressures toward artificial certainty. Based on these insights, we develop a critical distinction between representations of the future versus representations for the future, offering new ways to theorize decision making under uncertainty as organizations increasingly deploy sophisticated AI systems. Funding: This work was supported by the National Science Foundation [Grants SES-1057148 and SES-2051896]. 

ABSTRACT Slide‐ring network (SRN) hydrogels derived from ring‐crosslinked polyrotaxanes exhibit exceptional mechanical properties attributable to a pulley effect, whereby mobile‐ring crosslinks redistribute tension under deformation through a slip‐link mechanism. However, SRN hydrogels weaken severely upon swelling in water, limiting their utility at high water content (90 wt.%). Here, two distinct physical slip‐link mechanisms are combined in a highly entangled slide‐ring double network (HESRDN) hydrogel: the pulley effect of a polyrotaxane slide‐ring network and the entangled chains of a sparsely cross‐linked polyacrylamide network. HESRDN is prepared by photopolymerization of acrylamide/N,N'‐methylenebis(acrylamide) within a partially swollen slide‐ring hydrogel. The dual slip‐link architecture synergistically strengthens and toughens the hydrogel far beyond the sum of the component networks, yielding high work of fracture (1275 kJm⁻³), toughness (2020 Jm⁻²), and near‐complete reversibility (99.7%) at 91 wt.% water. HESRDN withstands continuous friction for over 12 h without rupture, compared to minutes for the SRN and 5 h for the HEN component networks, reflecting the unique capacity of the dual slip‐link architecture to delocalize and redistribute stress under sustained mechanical loading. 

The coupled equations governing whistler waves propagating along a duct with cylindrical cross section are derived and then solved numerically. These equations are expressed in terms of magnetic and current flux functions and show that it is possible to have a solution where the waves are finite in the duct and decay exponentially outside the duct. This solution has the property of having zero radial Poynting flux everywhere, so, as required for whistler waves to bounce back and forth losslessly between magnetically conjugate terrestrial hemispheres, no wave power leaks from the duct. The coupled equations are solved numerically for a tangible realistic situation by dividing the radial domain into an inner and an outer region, where the interface between these regions is at a mode conversion location, where fast and slow modes inside the duct merge and effectively reflect. The result of this effective reflection is that there are fast and slow standing waves in the duct. In the region external to the duct, the wave solutions are also a form of standing waves, but with a strong exponential decay and a radial wavelength that is intermediate between that of the fast and slow waves in the duct. The numerical solution is shown to be in good quantitative agreement with estimates made from analytic models. Detailed examination of the solutions in the vicinity of the mode conversion location shows that the classic plane wave assumption fails to describe the true nature of the modes. 

Abstract. Landslides can dam rivers and require rapid response to mitigate catastrophic outburst floods. Here, we present a workflow to map landslide dam formation susceptibility at a regional scale. We define a probabilistic function that combines river valley width and landslide volume to efficiently determine the likelihood of a landslide dam or “damability”. We combine damability values with landslide susceptibility to estimate landslide dam susceptibility. The valley width measurements are automated using a new elevation threshold-based algorithm. Landslide volume is represented as a statistical distribution from mapped landslides. We validate and apply our approach to the Oregon Coast Range, USA and find that 36 % of river stretches exceed a dam potential threshold; these are in river headwaters and steeper terrain, which in this case correlate with more resistant lithologies. We also estimate volumes of the potential dammed lakes and find that most rivers with high dam susceptibility are less likely to impound large lakes because they have low drainage areas. However, widespread susceptibility, and the potential impacts from exceptionally large landslides, suggest that this hazard should be considered in the Pacific Northwest. The damability function workflow can ingest new data and be applied more broadly to assess future landslide dam hazards. 

Abstract Biotic dispersal between regions is mediated by a suite of geographical, environmental, and biotic factors. Australia and Melanesia—with the latter centred on New Guinea—are geographically proximate regions that show differing abiotic environments and geological histories, providing an opportunity to document how environmental variation may interact with geographical proximity in shaping dispersal and evolution. Here, we present a phylogenomic framework and analysis of dispersal history for geckos in the genus Gehyra, a radiation of ∼70 species that occur across Australia, Melanesia, and nearby regions. Despite an evident history of numerous overwater dispersals in species groups occurring in Melanesia, we find very low rates of historical dispersal between Australia and Melanesia and no evidence of an increase in dispersal rate as land bridges formed between Australia and New Guinea from the late Miocene onwards. Analyses of body-size evolution suggest that ‘giant’ large-bodied forms have evolved on islands, but rather than evolving repeatedly on different islands, these are mostly members of a single old clade that dispersed across multiple islands. In contrast to some other Australasian vertebrate radiations, for Gehyra geckos, environmental differences appear to have strongly impeded dispersal between Australia and Melanesia, while also favouring differing trajectories of body size evolution. 

A new generation of standard reference diets (SRDs) is essential to enhance the integrity of research associated with the use of laboratory animal models in the study of human disease. Support for the value of this fundamental facet of experimental methodology is provided via a historical overview, an assessment of current status, and the advancements and opportunities that will be realized through further development and routine use. An outline of the extensive investment in animal nutrition research by National Institutes of Health during the past 30 y is presented with specific reference to rodent animal models and standardization in dietary methodology. Timely recommendations for renewed action that revitalize and expand the use of SRDs in rodents and other models, such as zebrafish, are provided with the aim of achieving more rigor, transparency, replicability, interpretability, and integrity in preclinical and translational animal model-based research. Ultimately, the benefits of these efforts will be fulfilled through expeditious development of prophylactic and therapeutic approaches for human diseases.