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Comprehensive exploration of signal to noise in low-field NMR, with a specific application to ODNP demonstrating that sensitivity can be increased by orders of magnitude. 

Modeling L-edge spectra at X-ray wavelengths requires consideration of spin–orbit splitting of the 2p orbitals. We introduce a low-cost tool to compute core-level spectra that combines a spin–orbit mean-field description of the Breit–Pauli Hamiltonian with nonrelativistic excited states computed using the semi-empirical density-functional theory configuration-interaction singles (DFT/CIS) method, within the state-interaction approach. Our version of DFT/CIS was introduced recently for K-edge spectra and includes a semi-empirical correction to the core orbital energies, significantly reducing ad hoc shifts that are typically required when time-dependent (TD-)DFT is applied to core-level excitations. In combination with the core/valence separation approximation and spin–orbit couplings, the DFT/CIS method affords semiquantitative L-edge spectra at CIS cost. Spin–orbit coupling has a qualitative effect on the spectra, as demonstrated for a variety of 3d transition metal systems and main-group compounds. The use of different active orbital spaces helps to facilitate spectral assignments. We find that spin–orbit splitting has a negligible effect on M-edge spectra for 3d transition metal species. 

Voronoi diagrams are widely used to model disperse systems such as foams, powders, polycrystals and atoms in the classical limit. Voronoi tessellations partition the continuous phase into compartments, or cells, that encompass all space closer to the assigning dispersed object than any other in the system. To account for heterogeneity in object size, weights are applied to avoid unphysical partitioning across non-contacting objects. Power and additive weighting are the most common weighting schemes, wherein power is more computationally tractable but additive weighting correlates more directly with size. In general, the two schemes produce distinct spatial decompositions for any non-monodisperse system. To calibrate the divergent volumetric metrics from the two schemes, and to gain physical insight into their divergence, we compared power and additively weighted Voronoi diagrams of polydisperse ensembles representing physically relevant ranges of polydispersity, density, and overlap. When tested against experimental distributions of gas foams, the results related their divergent power and additively weighted decompositions to the polydispersity of their particle size distributions. Geometric analysis of the Voronoi cells implicated the subpopulation of small objects as the primary contributors to the divergence through their preferential assignment of larger, aspherical power cells relative to their additively weighted counterparts. 

High-harmonic generation (HHG) has been established as a powerful tool for studying structure and dynamics of quantum systems in gas and solid phases. To date, only a few studies have extended HHG spectroscopy to liquids, and much remains unresolved concerning the information that can be extracted from HHG spectra about the local liquid environment and the potential of HHG as a nonlinear probe of solvation dynamics. In this work, we investigate HHG in liquid binary solutions consisting of mixtures of aromatic benzene derivatives solvated in methanol. We observe evidence of a localized solvation structure that is imprinted on the harmonic spectra in the form of a strongly suppressed harmonic order, and an overall reduction of the total harmonic yield. We characterize this behavior as a function of laser parameters, concentration, and other halogenated benzene derivatives in methanol solution. Guided by theory, we interpret the results in terms of a localized solvation shell that is formed in specific solutions and acts like a local scattering barrier in the HHG process. This work demonstrates the potential of high-harmonic spectroscopy in liquids to extract detailed information about the structure and dynamics of solvation while expanding our understanding of the fundamental mechanism of HHG in systems with short-range order. 

Abstract There is little understanding of physical activity (PA) and sedentary behavior as preventive health behaviors in autistic adults. Technology has been used as an educational and social intervention tool for autistic individuals, yet it is also associated with low PA and high sedentary time (ST) in the neurotypical population. This study aimed to examine the prevalence of self-reported PA and ST and their relationships with various technology uses in autistic adults. We employed a Qualtrics online survey that consisted of the International Physical Activity Questionnaire-Short Form, Sedentary Behavior Questionnaire, and National Alliance for Mental Illness’s digital technology use survey. 229 responses (74.6% under 35 years of age; 64.1% males) satisfied the response validity criteria and were included in the analyses. The majority of participants (78%) met the recommended PA amount of ≥ 600 metabolic equivalent of task (MET)-minutes/week (median, 1,812 total MET-minutes/week), but they were also overly sedentary on both weekdays (median, 8 h/day) and weekends (median, 7 h/day). Stepwise multiple regression analyses revealed that variance of ST in weekday (45%) and weekend (43%) was largely explained by quality of life (β = -0.31;β = -0.33) and technology use time (β = 0.31;β = 0.26) (allp < .01). While technology can be an effective tool to support social and academic abilities in autistic adults, the use of technology devices needs to be monitored with care as it may put these individuals at risk for sedentary lifestyles and associated chronic diseases. 

Abstract We probe the three-dimensional geometry of the large-scale Galactic magnetic field within 1 kpc of the Sun using the Dominion Radio Astrophysical Observatory Global Magneto-Ionic Medium Survey (GMIMS) of the Northern Sky (DRAGONS). DRAGONS is a new full polarization survey of the northern sky from 350 to 1030 MHz covering decl. of –20° < δ < 90° and a component of GMIMS. The first moment of the Faraday depth (FD) spectra produced from DRAGONS above 500 MHz reveals large-angular-scale FD structures with signs that alternate only once in the southern Galactic hemisphere and twice in the northern hemisphere, patterns shared by other Faraday rotation datasets. DRAGONS is the first survey to achieve high FD resolution while maintaining sensitivity to broad FD structures, enabling the first use of Galactic longitude–FD plots. These plots reveal Faraday-complex structures across the sky, indicating a slablike scenario in which emission and Faraday rotation are mixed. This complexity is overlaid on the same large-scale FD patterns that appear in the first moment map. We model these patterns as a magnetic reversal slicing through the disk on a diagonal and passing above the Sun in Galactic coordinates. We describe this reversal as a plane with a normal vector parallel to the line directed along (ℓ,b) = (168 $\stackrel{\text{°}}{.}$5, −60°) and estimate its distance to be between 0.25 and 0.55 kpc. Our results show that much of the observed Faraday sky may be dominated by the local magnetic field configuration. 

Abstract Evolutionary adaptation can allow a population to persist in the face of a new environmental challenge. With many populations now threatened by environmental change, it is important to understand whether this process of evolutionary rescue is feasible under natural conditions, yet work on this topic has been largely theoretical. We used unique long-term data to parameterize deterministic and stochastic models of the contribution of 1 trait to evolutionary rescue using field estimates for the subalpine plant Ipomopsis aggregata and hybrids with its close relative I. tenuituba. In the absence of evolution or plasticity, the 2 studied populations are projected to go locally extinct due to earlier snowmelt under climate change, which imposes drought conditions. Phenotypic selection on specific leaf area (SLA) was estimated in 12 years and multiple populations. Those data on selection and its environmental sensitivity to annual snowmelt timing in the spring were combined with previous data on heritability of the trait, phenotypic plasticity of the trait, and the impact of snowmelt timing on mean absolute fitness. Selection favored low values of SLA (thicker leaves). The evolutionary response to selection on that single trait was insufficient to allow evolutionary rescue by itself, but in combination with phenotypic plasticity it promoted evolutionary rescue in 1 of the 2 populations. The number of years until population size would stop declining and begin to rise again was heavily dependent upon stochastic environmental changes in snowmelt timing around the trend line. Our study illustrates how field estimates of quantitative genetic parameters can be used to predict the likelihood of evolutionary rescue. Although a complete set of parameter estimates are generally unavailable, it may also be possible to predict the general likelihood of evolutionary rescue based on published ranges for phenotypic selection and heritability and the extent to which early snowmelt impacts fitness.