Rayleigh-Taylor Instability in a Relativistic Shock

The quantum dimer magnet, with antiferromagnetic intradimer and interdimer Heisenberg exchange between spin-1/2 moments, is known to host an $$(\left|\uparrow \downarrow \right\rangle -\left|\downarrow \uparrow \right\rangle )/\sqrt{2}$$singlet ground state when the intradimer exchange is dominant. Rare-earth-based quantum dimer systems with strong spin-orbit coupling offer the opportunity for tuning their magnetic properties by using magnetic anisotropy as a control knob. Here, we present bulk characterization and neutron scattering measurements of the quantum dimer magnet Yb2Be2SiO7. We find that the Yb3+ ions can be described by an effective spin-1/2 model at low temperatures and the system does not show signs of magnetic order down to 50 mK. The magnetization, heat capacity, and neutron spectroscopy data can be well-described by an isolated dimer model with highly anisotropic exchange that stabilizes a singlet ground state with a wavefunction $$(\left|\uparrow \uparrow \right\rangle -\left|\downarrow \downarrow \right\rangle )/\sqrt{2}$$or $$(\left|\uparrow \uparrow \right\rangle+\left|\downarrow \downarrow \right\rangle )/\sqrt{2}$$. Our results show that strong spin-orbit coupling can induce unusual entangled states of matter in quantum dimer magnets.

This paper presents ambient | global, an ambient soundscape model developed to predict global ambient sound levels from all anthropogenic, biological, and geophysical sources. The soundscape model adopts a geospatial approach by modeling the ambient sound level as a function of geospatial features at a location. The soundscape model consists of an ensemble of four machine learning regression models fitted at acoustic measurement sites where both the geospatial features and ambient sound levels are known. The fitted model is then applied to predict ambient sound levels at any location where the geospatial features are known. The results quantify the spatial, temporal, and spectral patterns of ambient sound levels across the world under various scenarios. This paper presents maps of the existing ambient sound levels across the world in terms of the daytime overall A-weighted L50, or median sound level, and partitions the existing sound levels into their natural and anthropogenic constituents. Ultimately, the soundscape model will enable research into the impacts of humans and nature on the ambient soundscape and the impacts of ambient sound levels on humans and nature across the world.

This study describes a carrier having submicron, uniform and non-aggregated poly lactic acid (PLA) spheres loaded with the anticancer drug 5-fluorouracil (5FU) and with 9 nm superparamagnetic iron oxide nanoparticles (SPIONs) for magnetically guided drug delivery and local controlled release. Using a water/organic/water (w/o/w) doubleemulsion process, we produced uniformly spherical microparticles smaller than 2 µm in diameter with well-dispersed SPIONs that retained superparamagnetic behavior after encapsulation. 5FU loading efficiency was determined to be 94%. Biological activity and chemical integrity was confirmed for the 5FU released from the product. Drug release kinetics showed faster release within the first day followed by sustained, slower release over 63 days with a cumulative release reaching 70% of loaded drug. Drug release was faster at 37°C compared to 21°C. PBS at pH 7.4 and 5.4 promoted faster release than did distilled water at pH 7.0. Release was prolonged from these PLA systems compared to other systems employing PLGA. This research introduces a rigorously optimized microcarrier system distinguished by sub-2-µm superparamagnetic PLA or PLGA microspheres of uniform morphology containing phase-dispersed SPIONs and exhibiting long-term controlled release, offering a transformative framework for magnetically directed drug delivery using high-gradient systems such as Halbach arrays.

This study presents a comparative analysis of far-field acoustic measurements from twelve SpaceX Falcon 9 launches conducted near Vandenberg Space Force Base. Acoustic data were collected at a fixed location 8.45 km from the launch pad as part of an ongoing ecology-motivated effort to characterize the launch noise environment. Maximum overall sound pressure levels (OASPL), one-third-octave spectra, pressure-time waveforms, and running pressure-derivative skewness were examined to assess launch-to-launch variability. Results show a spread of approximately 4.7 dB in maximum flat-weighted OASPL and over 10 dBA across the dataset, despite consistent vehicle configuration and similar ascent trajectories. Detailed comparisons of three representative launches reveal substantial differences in waveform structure, dominant spectral content, and crackle-related metrics. The period of maximum OASPL does not coincide with the period of maximum derivative skewness, and the launch with the greatest OASPL contains the least amount of crackle content. Understanding of this launch-to-launch variability, likely driven by local meteorology, is critical for accurate rocket noise modeling and environmental impact assessment.

Mutual events of trans-Neptunian binaries (TNBs) provide rare opportunities to measure the physical and orbital properties of small bodies in the outer solar system. However, successful observations of these events have been limited by uncertain predictions. Here, we present probabilistic predictions of TNB mutual events occurring through the 2030s, using high-precision non-Keplerian orbit solutions from the Beyond Point Masses project combined with a Bayesian framework that propagates orbital and size uncertainties. Our methods generate distributions of event timing, duration, depth, and probability of occurrence, enabling direct assessment of observability. We provide predictions for five systems with ongoing or imminent mutual event seasons, including (38628) Huya, (58534) Logos–Zoe, (148780) Altjira, (469705) ǂKá̧gára-!Hãunu, and (524366) 2001 XR254. Preparing for upcoming events with long-baseline light-curve monitoring is vital, as events may be difficult to distinguish from a regular rotational light curve. Rapid dissemination of event detections will benefit the entire community, allowing predictions to be updated, ensuring that these rare mutual event opportunities can be fully exploited.