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1. Disagreements in Geodetically Inferred Strain Rates in the Western US With Stress Orientations and Geologic Moment Rates

   https://doi.org/10.1029/2023JB027472  

   Johnson, Kaj M. (April 2024, Journal of Geophysical Research: Solid Earth)

   Abstract I employ an elasticity‐based method to invert a geodetically derived surface velocity field in the western US using for present‐day surface strain rate fields with uncertainties. The method uses distributed body forces in a thin elastic sheet and allows for discontinuities in velocity across creeping faults using the solution for dislocations in a thin elastic plate. I compare the strain rate fields with previously published stress orientations and moment rates from geological slip rate data and previous geodetic studies. Geologic and geodetic moment rates are calculated using slip rate and off‐fault strain rates from the 2023 US National Seismic Hazard Model (NSHM) deformation models. I find that computed total geodetic moment rates are higher than NSHM summed moment rates on faults for all regions of the western US except the highest deforming rate regions including the Western Transverse Ranges and the northern and southern San Andreas Fault (SAF) system in California. Computed geodetic moment rates are comparable to the moment rates derived from the geodetically based NSHM deformation models in all regions. I find systematic differences in orientations of maximum horizontal shortening rate and maximum horizontal compressive stress in the Pacific Northwest region and along much of the SAF system. In the Pacific Northwest, the maximum horizontal stress orientations are rotated counterclockwise 40–90° relative to the maximum horizontal strain rate directions. Along the SAF system, the maximum horizontal stresses are rotated systematically 25–40° clockwise (closer to fault normal) relative to the strain rates. 

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2. Phospholipid turnover rates suggest that bacterial community growth rates in the open ocean are systematically underestimated

   https://doi.org/10.1002/lno.11424  

   Popendorf, Kimberly J.; Koblížek, Michal; Van Mooy, Benjamin A. S. (March 2020, Limnology and Oceanography)

   Abstract Heterotrophic bacteria in the surface ocean play a critical role in the global carbon cycle and the magnitude of this role depends on their growth rates. Although methods for determining bacterial community growth rates based on incorporation of radiolabeled thymidine and leucine are widely accepted, they are based on a number of assumptions and simplifications. We sought to independently assess these methods by comparing bacterial growth rates to turnover rates of bacterial membranes using previously published methods in a range of open‐ocean settings. We found that turnover rates for heterotrophic bacterial phospholipids averaged 0.80 ± 0.35 d⁻¹. This was supported by independent measurements of turnover rates of a membrane‐bound pigment in photoheterotrophic bacteria, bacteriochlorophyll a(0.85 ± 0.09 d⁻¹). By contrast, bacterial growth rates measured by uptake of radiolabeled thymidine and leucine were 0.12 ± 0.08 d⁻¹, well within the range expected from the literature. We explored whether the discrepancies between phospholipid turnover rates and bacterial growth rate could be explained by membrane recycling/remodeling and other factors, but were left to conclude that the radiolabeled thymidine and leucine incorporation methods substantially underestimated actual bacterial growth rates. We use a simple model to show that the faster bacterial growth rates we observed can be accommodated within the constraints of the microbial carbon budget if bacteria are smaller than currently thought, grow with greater efficiency, or some combination of these two factors. 

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3. Changes in Crime Rates during the COVID-19 Pandemic

   https://doi.org/10.1080/2330443X.2022.2071369  

   Meyer, Mikaela; Hassafy, Ahmed; Lewis, Gina; Shrestha, Prasun; Haviland, Amelia M.; Nagin, Daniel S. (December 2022, Statistics and Public Policy)
4. 2D and Slab Turbulent Cascade Rates in the Inner Heliosphere

   https://doi.org/10.3847/1538-4357/ac9234  

   Adhikari, L.; Zank, G. P.; Zhao, L.-L.; Telloni, D. (October 2022, The Astrophysical Journal)

   Abstract We present a theoretical and observational study of 2D and slab turbulence cascade (or heating) rates of transverse total turbulence energies, transverse cross helicity, transverse outward and inward Elsässer energy, transverse fluctuating magnetic energy density, and transverse fluctuating kinetic energy from the perihelion of the first Parker Solar Probe (PSP) orbit at ∼36.6 R ⊙ to Solar Orbiter (SolO) at ∼177 R ⊙ . We use the Adhikari et al. (2021a) approach to calculate the observed transverse turbulence heating rate, and the nearly incompressible magnetohydrodynamic (NI MHD) turbulence transport theory to calculate the theoretical turbulence cascade rate. We find from the 1 day long PSP measurements at 66.5 R ⊙ , and the SolO measurements at 176.3 R ⊙ that various transverse turbulent cascade rates increase with increasing angle, from 10° to 98°, between the mean solar wind speed and mean magnetic field ( θ UB ), indicating that the 2D heating rate is largest in the inner heliosphere. Similarly, we find from the theoretical and observed results that the 2D heating rate is larger than the slab heating rate as a function of heliocentric distance. We present a comparison between the theoretical and observed 2D and slab turbulence cascade rates as a function of heliocentric distance. 

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5. Pre-agricultural soil erosion rates in the midwestern United States

   https://doi.org/10.1130/G50667.1  

   Quarrier, Caroline L; Kwang, Jeffrey S; Quirk, Brendon J; Thaler, Evan A; Larsen, Isaac J (December 2022, Geology)

   Abstract Erosion degrades soils and undermines agricultural productivity. For agriculture to be sustainable, soil erosion rates must be low enough to maintain fertile soil. Hence, quantifying both pre-agricultural and agricultural erosion rates is vital for determining whether farming practices are sustainable. However, there have been few measurements of pre-agricultural erosion rates in major farming areas where soils form from Pleistocene deposits. We quantified pre-agricultural erosion rates in the midwestern United States, one of the world's most productive agricultural regions. We sampled soil profiles from 14 native prairies and used in situ–produced 10Be and geochemical mass balance to calculate physical erosion rates. The median pre-agricultural erosion rate of 0.04 mm yr–1 is orders of magnitude lower than agricultural values previously measured in adjacent fields, as is a site-averaged diffusion coefficient (0.005 m2 yr–1) calculated from erosion rate and topographic curvature data. The long-term erosion rates are also one to four orders of magnitude lower than the assumed 1 mm yr–1 soil loss tolerance value assigned to these locations by the U.S. Department of Agriculture. Hence, quantifying long-term erosion rates using cosmogenic nuclides provides a means for more robustly defining rates of tolerable erosion and for developing management guidelines that promote soil sustainability. 

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