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Binder jetting of minimally processed, locally sourced sediments offers a promising route toward sustainable additive manufacturing, but powder spreading of poorly sorted, irregular grains remains underexplored. This study uses high-fidelity Discrete Element Method (DEM) simulations to quantify how process parameters govern layer quality when spreading an unrefined sandy silt from the Gypsum Hills, Kansas, USA, with a counter-rotating roller. Twenty-five multi-sphere particle shapes were reconstructed from morphological measurements and used to simulate up to 300,000 interacting grains while systematically varying roller traverse speed, rotational speed, diameter, and layer thickness. Traverse speed and layer thickness emerged as the dominant controls on powder bed density and uniformity: the slowest traverse speed (20 mm/s) produced the highest density (~ 0.50) and lowest variability (~ 0.08), and layer thicknesses ≥ 120 μm were required to avoid jamming and obtain consistent packing. In contrast, roller diameter and rotational speed had only minor influence over the explored ranges. The simulations also revealed percolation-driven segregation, with fine particles preferentially settling beneath coarser grains. Comparison with an idealized spherical powder showed that the silt is intrinsically harder to spread, achieving lower density (0.51 vs. 0.59) and higher variability. These results demonstrate that binder jet processing of unrefined silt is feasible but favors slower spreading and thicker layers that may reduce throughput and resolution, and they provide process design guidelines and particle-scale insight for deploying raw earth feedstocks in sustainable binder jetting. 

ABSTRACT We present the deepest and highest-resolution radio continuum imaging of the Galactic globular cluster Terzan 5, one of the most crowded locations in the radio sky. In these new 2–4 GHz Karl G. Jansky Very Large Array images, we detect 38 of the 49 confirmed pulsars, including extensive multi-frequency eclipse mapping of the luminous redback Ter5A. Nonetheless, there is still a large amount of diffuse residual flux from pulsars that are fainter than our 2.5 GHz continuum detection limit of $$\sim 11\, \mu$$Jy. Using a range of approaches including image-based simulations, we model the fluxes of the detected pulsars together with the residual flux. We find a minimum total population of $$N\sim 250$$ detectable pulsars in Terzan 5 and perhaps substantially more, though the luminosity function remains very uncertain. Consideration of the $$\gamma$$-ray properties of the cluster, though also not unambiguous to interpret, leads to consistent conclusions. These pulsar population estimates are larger than inferred from previous work and highlight Terzan 5 as a keystone target for next-generation radio facilities. 

Abstract As farmers adapt to changing climate, they modify practices to manage evolving production risk. Understanding farmers' risk attitudes is critical to predicting their decisions about climate change adaptation. This research empirically estimates utility functions to measure the risk preferences of Michigan corn‐soybean farmers. We elicit choices between paired lotteries in both a general and an agricultural domain. We find that farmers are risk‐averse across domains. However, farmer risk preferences are more heterogeneous in the agricultural domain than in the general one. These results are robust across specifications of utility functions, individual versus aggregate estimates, and types of risky outcomes. 

The Caribbean Through-Flow (CTF) is a critical chokepoint for North and South Atlantic waters that form the North Atlantic western boundary current system and the upper ocean limb of the Atlantic Meridional Overturning Circulation. While the circulation and energetics of the CTF have been well studied, its water mass transformations remain poorly constrained. Using over 7700 Argo float profiles from 2014 to 2024, we document a prominent westward modification in water mass structure across the Caribbean Sea. From the eastern to western Caribbean, we observe systematic increases in ocean heat content, a deepening of isopycnals, and a freshening and deepening of the subsurface salinity maximum. These changes result in a net mid-depth (~50–500 m) density reduction of 0.40 ± 0.27 kg m-3. We hypothesize that regional variations in mesoscale eddy activity, complex bathymetry, and meridional wind stress curl gradients drive this transformation. The resulting water mass structure has critical implications for regional climate, weather, ecosystems, and sea level rise, as it modifies the density and stratification of source waters entering the Gulf of Mexico and North Atlantic western boundary current system. Our findings highlight the importance of internal Caribbean processes in shaping upper-ocean heat and salt transport in the Atlantic and underscore the need for sustained in situ observations in the region and targeted modeling analyses of the underlying modification processes. 

Wastewater-based epidemiology (WBE) played a vital role during the COVID-19 pandemic by providing early warnings of outbreaks through SARS-CoV-2 RNA detection in sewage. Many rural communities did not benefit from WBE because limited centralized sewer infrastructure challenged conventional WBE surveillance strategies. We present a multi-agent computer model simulating COVID-19 spread in a U.S. county with both sewered and non-sewered zones to assess the performance of WBE in this setting. We evaluate how the sewage service status of the first SARS-CoV-2 carrier, cross-zone community mobility, and WBE detection thresholds influence outbreak detection timing at the county’s wastewater treatment plant under basic reproduction numbers (R0) of 4 and 8. Our key findings include that (1) a detection threshold of 10 gc/mL can identify outbreaks up to six days earlier than a threshold of 50 gc/mL; (2) outbreaks originating in non-sewered zones are detected 1–2 days later, compared with outbreaks in sewered zones; and (3) cross-zone community mobility impacts detection timing only when outbreaks begin in non-sewered zones. Furthermore, once detected, disease prevalence can increase by five- to eleven-fold within the following week. These results underscore the importance of WBE sensitivity and tailored surveillance strategies in both sewered and non-sewered zones of a community. Strengthening WBE capabilities at local treatment facilities can improve early outbreak detection, thereby supporting timely public health interventions. 

Abstract We present 15 yr of Nançay and Green Bank radio telescope timing observations for PSR J1231−1411. This millisecond pulsar is a primary science target for the Neutron Star Interior Composition Explorer telescope (NICER, which discovered its X-ray pulsations), has accumulated near-continuousγ-ray data since the Fermi-Large Area Telescope’s launch, and has been studied extensively with the Green Bank and Nançay radio telescopes. We have undertaken a campaign with the Green Bank Telescope targeting specific orbital phases designed to improve our constraint on the pulsar’s mass through the detection of a relativistic Shapiro delay. Both frequentist and Bayesian techniques—the latter incorporating priors from white dwarf binary evolution models—are applied to 15 yr of radio observations, yielding relatively weak constraints on the companion and pulsar masses of $0.23_{-0.06}^{+0.09}$M_⊙and $1.87_{-0.67}^{+1.11}$M_⊙, respectively (68.3% CI from Bayesian fits); however, the orbital inclination is measured to better relative precision ( $79.80_{-4.70}^{+3.47}$°). Restricting the maximum allowed pulsar mass to 3M_⊙improves the constraint and lowers the measured mass to $1.71_{-0.56}^{+0.70}$M_⊙. A fully generalized Bayesian fit that simultaneously samples the noise and timing models yields a pulsar mass in close agreement with this value. While our radio-derived inclination result has informed recent NICER X-ray studies of J1231−1411, the lessons learned from this troublesome pulsar will also bolster future high-precision mass measurement campaigns and resulting constraints on the neutron star interior equation of state. 

In the abstract Tile Assembly Model, self-assembling systems consisting of tiles of different colors can form structures on which colored patterns are “painted.” We explore the complexity, in terms of the numbers of unique tile types required, of assembling various patterns. We first demonstrate how to efficiently self-assemble a set of simple patterns, then show tight bounds on the tile type complexity of self-assembling multi-colored patterns on the surfaces of square assemblies. Finally, we demonstrate an exponential gap in tile type complexity of self-assembling an infinite series of patterns between systems restricted to one plane versus those allowed two planes. This paper is an expansion over a version in the proceedings of the 21st International Conference on Unconventional Computation and Natural Computation (UCNC 2024), with several improved results and full details of all proofs. 

Wastewater testing for SARS-CoV-2 provided useful public health information during the COVID-19 pandemic yet was underutilized in rural communities. We addressed this gap by implementing wastewater surveillance and assessing its performance in 10 communities in Eastern Kentucky. We collected wastewater samples 1–2 times weekly at 10 wastewater treatment plants (WWTPs) from May 2021 until April 2023 and measured SARS-CoV-2 RNA concentrations using polymerase chain reaction testing. We calculated time-lagged correlations between wastewater concentrations and county-level reported COVID-19 cases by site. We developed a generalized linear model to estimate COVID-19 incidence from wastewater SARS-CoV-2 concentrations. The 10 participating WWTPs served 2430 to 35,575 customers, and 90% were in rural counties. We cumulatively analyzed 818 wastewater samples. Correlations between wastewater SARS-CoV-2 concentrations and COVID-19 cases were significant at seven of the WWTPs and were strongest during the Delta variant period. The incidence density model predicted more COVID-19 cases during the latter study period (May 2022–April 2023) than were officially reported. Wastewater surveillance data in these rural communities corroborated clinical case data and may have more accurately described community disease levels later in the pandemic. 

Nonlocal density functional theory calculations were utilized to investigate the interactions of four different cyclic N-heterocyclic carbenes with a Pd/Cu(111) single-atom alloy surface. We find that the molecules are chemisorbed to the surface due to relatively large binding energies and significant charge transfer between the surface and the adsorbates. We highlight that modulating the NHC backbone changes the unoccupied states on the adsorbates that participate in back-donation from the surface to the adsorbate. This contrasts with the forward donation (adsorbate HOMO to the surface) that is left relatively unchanged through modifying the backbone.