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Cannabis legalization and consumption in the United States have accelerated over the past decade, resulting in a rapidly diversifying marketplace of medical and adult-use products. As of 2025, medical cannabis is permitted in 47 states, while adult-use markets are authorized in 24 states and the District of Columbia. This expansion underscores the urgent need for robust and consistent safety testing to ensure consumer protection. Despite federal prohibition, states have independently developed their own regulatory frameworks for contaminant testing, leading to wide variability in allowable limits, analyte lists, and method validation requirements. Method:This review critically compares contaminant regulations across U.S. adult-use jurisdictions and evaluates analytical methodologies published between 2020 and 2025 for four major hazard categories: heavy metals, pesticides, mycotoxins, and residual solvents. Emphasis is placed on sample preparation strategies, analytical instrumentation, and method performance parameters relevant to complex cannabis matrices such as flower, concentrates, and infused products. Results:Sample preparation approaches are tailored to matrix complexity and frequently utilize Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) extraction followed by dispersive solid-phase extraction (dSPE). Cartridge SPE is commonly applied for enhanced cleanup, and immunoaffinity columns is used for selective isolation of aflatoxins and ochratoxin A. Instrumental analysis typically relies on Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) for trace metals, liquid chromatography-tandem mass spectrometry and gas chromatography-tandem mass spectrometry (GC-MS/MS) for pesticide and mycotoxin detection, and headspace GC with flame ionization detection or GC-MS for residual solvent quantification. Discussion:Although current methodologies provide sensitive and reliable detection, inconsistencies in regulatory oversight across jurisdictions limit data comparability and complicate interstate commerce. Establishing harmonized performance criteria, standardized reporting units, and national proficiency testing programs would improve method reliability and consumer confidence. Continued innovation in sample preparation and validated multi-residue methods will be critical as product diversity and testing demands continue to expand. 

Abstract Isolated star-forming galaxies require inflows of fresh gas from the surrounding medium to sustain episodes of star formation over time. However, there are very few direct detections of accretion onto external galaxies. Studies in absorption can only observe along limited sightlines, while those in emission can have difficulty distinguishing inflowing gas in the foreground of the galactic disk from similarly Doppler-shifted outflowing gas in the background. We explore the possibility of using the Balmer decrement (Hα/Hβ) in low-inclination systems as a diagnostic for disentangling the flow geometry in disk-like galaxies. We leverage mock spatial–spectral observations of an isolated Milky Way–mass galaxy simulated using the radiation-hydrodynamics code AREPO-RT and post-processed with the Monte Carlo radiative transfer code COLT. We find that gas components located in front of the disk exhibit systematically lower Balmer decrements than gas embedded in or behind the disk, with a mean front–back offset of Δ(Hα/Hβ) ≈ –0.14. The ability to differentiate between the disk and far-side components is limited by the extremely clumpy, multiphase dust distribution along the line of sight introducing substantial scatter. Overall, the results provide a useful observational diagnostic of inflow and outflow in dusty face-on galaxies. 

Solar flares are among the most dramatic events in the solar system, releasing substantial magnetic energy and accelerating a large number of electrons to high energies. Notably, in certain events, the above-the-looptop region may contain a significant population of nonthermal electrons, both in number and energy. For the first time, we adopt a novel numerical method that combines magnetohydrodynamics with energetic particles incorporating feedback from nonthermal electrons to investigate electron acceleration and transport in solar flares. We find that a large fraction of energetic electrons are accelerated via the current sheet and termination shock regions. Most energetic electrons are concentrated in the above-the-looptop region, carrying a sizable amount of the released energy. We observe that greater feedback of nonthermal electrons leads to steeper energy spectra. The energy density of the nonthermal electrons oscillates due to the periodic impact of magnetic islands into the above-the-looptop region, which may help explain the observed quasiperiodic pulsations. Our simulations provide new insights into the origin of nonthermal electrons and associated emissions in the above-the-looptop region. 

Ultracold elastic collisions of⁸⁷Rb with⁴⁰K⁸⁷Rb in its ground vibrational and rotational state are investigated using a first principles based theoretical methodology. 

Abstract The dynamics of star-forming gas can be affected by many physical processes, such as turbulence, gravity, supernova explosions, and magnetic fields. In this paper, we investigate several nearby star-forming regions (Orion, Upper Sco, Taurus, and Perseus) for kinematic imprints of these influences on the newly formed stars. Using Gaia DR3 astrometry and APOGEE DR17 radial velocities, we compute first-order velocity structure functions (VSFs) of young stars in galactic Cartesian coordinates in both 6D (3D positions and 3D velocities) and 4D (3D positions and each 1D velocity) to identify signatures of turbulence and anisotropic motion. We also construct 3D and 1D radial velocity profiles to identify coherent expansion trends, and compare stellar proper motions to plane-of-sky magnetic field orientations in Taurus and Perseus. We find that the VSFs are mildly anisotropic, with slightly different amplitudes, slopes, or features in different directions in several groups, but in general, they are all consistent with Larson’s Relation at intermediate length scales, especially in less compact groups. In several cases, the VSFs exhibit features suggestive of local energy injection from supernovae. Radial velocity profiles reveal clear anisotropic expansion in multiple groups, with the most extreme cases corresponding to those with the most anisotropic VSFs. In Perseus, we find that the motions of young stars are preferentially perpendicular to the local magnetic field. We find multiple, overlapping causes in each group for the observed kinematics. Our findings support that young stars remember more than just the turbulent state of their natal clouds. 

Abstract We study spin dynamics and quantum magnetism with ultracold highly-magnetic atoms. In particular, we focus on the interactions among rare-earth atoms localized in a site of an optical-lattice potential, modeled as a cylindrically symmetric harmonic oscillator in the presence of a weak external magnetic field. The interactions between the atoms are modeled using a multi-channel Hamiltonian containing multiple spin–spin and anisotropic spin–orbit interactions with strengths that depend on the separation between the atoms. We studied the eigenenergies of the atom pair in a site for different lattice geometries and magnetic field strengths. In parallel, we compared these energies to those found from a simplified approach, where the complex-collisional physics is replaced by a two-length-scale pseudopotential containing the contact and magnetic dipole–dipole interactions. The eigenenergies of this model can be computed analytically within the Born approximation as well as non-perturbatively for strong contact interactions. We have shown that the pseudopotential model can accurately represent the multi-channel Hamiltonian in certain parameter regimes of the shape of the site of an optical lattice. The pseudopotential forms the starting point for many-body, condensed matter simulations involving many atom pairs in different sites of an optical lattice.