Ice shelves affect the stability of ice sheets by supporting the mass balance of ice upstream of the grounding line. Marine ice, formed from supercooled water freezing at the base of ice shelves, contributes to mass gain and affects ice dynamics. Direct measurements of marine ice thickness are rare due to the challenges of borehole drilling. Here we assume hydrostatic equilibrium to estimate marine ice distribution beneath the Amery Ice Shelf (AIS) using meteoric ice-thickness data obtained from radio-echo sounding collected during the Chinese National Antarctic Research Expedition between 2015 and 2019. This is the first mapping of marine ice beneath the AIS in nearly 20 years. Our new estimates of marine ice along two longitudinal bands beneath the northwest AIS are spatially consistent with earlier work but thicker. We also find a marine ice layer exceeding 30 m of thickness in the central ice shelf and patchy refreezing downstream of the grounding line. Thickness differences from prior results may indicate time-variation in basal melting and freezing patterns driven by polynya activity and coastal water intrusions masses under the ice shelf, highlighting that those changes in ice–ocean interaction are impacting ice-shelf stability.

A major subglacial lake, Lake Snow Eagle (LSE), was identified in East Antarctica by airborne geophysical surveys. LSE, contained within a subglacial canyon, likely hosts a valuable sediment record of the geological and glaciological changes of interior East Antarctica. Understanding past lake activity is crucial for interpreting this record. Here, we present the englacial radiostratigraphy in the LSE area mapped by airborne ice-penetrating radar, which reveals a localized high-amplitude variation in ice unit thickness that is estimated to be ∼12 ka old. Using an ice-flow model that simulates englacial stratigraphy, we investigate the origin of this feature and its relationship to changes in ice dynamical boundary conditions. Our results reveal that local snowfall redistribution initiated around the early Holocene is likely the primary cause, resulting from a short-wavelength (∼10 km) high-amplitude (∼20 m) ice surface slope variation caused by basal lubrication over a large subglacial lake. This finding indicates an increase in LSE water volume during the Holocene, illustrating the sensitivity in volume of a major topographically constrained subglacial lake across a single glacial cycle. This study demonstrates how englacial stratigraphy can provide valuable insight into subglacial hydrological changes before modern satellite observations, both for LSE and potentially at other locations.

This case study presents an analysis of community-driven partnerships, focusing on the nonprofit Baltimore CONNECT (BC) network and its collaborative efforts with a Community-Engaged Research (CEnR) team of the Johns Hopkins Institute for Clinical and Translational Research (ICTR). BC has built a network of over 30 community-based organizations to provide health and social services in Baltimore City. The study emphasizes the role of CEnR in supporting community-led decision-making, specifically in the planning and implementation of community health resource fairs. These fairs address social determinants of health by offering a variety of services, including health education, screenings, vaccinations, and resource distribution. The paper details the methods, resource mobilization, and collaborative framing processes in the execution of these fairs in a community-academic collaboration with the ICTR. Results from a 2.5-year period show the positive impact of the fairs on individuals, families, and the community at large in East Baltimore. The findings underscore the importance of community-led collaborations in addressing health disparities and improving overall community well-being. It concludes by reflecting on the sustained engagement, trust-building, and shared learning that emerges from such partnerships, suggesting a model for future community-academic health initiatives.

OBJECTIVES/GOALS: Cognitive Processing Therapy (CPT) is a cognitive behavioral treatment for posttraumatic stress disorder (PTSD). CPT is effective in treating combat-related PTSD among Veterans and active duty service members. It is unknown whether improvement in PTSD is related to accommodation of patient preference of the modality of therapy, such as in-office, telehealth, and in-home settings. An equipoise-stratified randomization design allows for complete randomization of participants who are interested and eligible for all three treatment arms. It also allows participants to reject one treatment arm if they are not interested or eligible. Participants who elect to opt out of one arm are randomized to one of the two remaining treatment arms. The primary aim of this study was to evaluate differences in patient satisfaction, treatment stigma beliefs, and credibility beliefs based on patient treatment modality preference. The second aim of this study was to examine if baseline satisfaction, stigma beliefs, and credibility beliefs predicted PTSD treatment outcomes. METHODS/STUDY POPULATION: Active duty service members and veterans with PTSD (N = 123) were randomized to one of three arms using an equipoise stratified randomization. Participants underwent diagnostic interviews for PTSD at baseline and post-treatment and completed self-report measures of satisfaction, stigma, credibility and expectancies of therapy. RESULTS/ANTICIPATED RESULTS: A series of ANOVAs indicated that there were group differences on patient stigma beliefs regarding mental health, F = 5.61, p = .001, and therapist credibility, F = 5.11, p = .002. Post hoc analyses revealed that participants who did not opt of any treatment arm demonstrated lower levels of stigma beliefs compared to participants who opted-out of in-office, p = .001. Participants who opted out of in-home viewed the therapist as less credible compared to participants who did not opt of any arm, p = .004. Multiple regression analysis found that baseline patient satisfaction, stigma beliefs, and credibility beliefs were not predictive of PTSD treatment outcomes, p > .05. DISCUSSION/SIGNIFICANCE OF IMPACT: Combat PTSD patients may opt out of in-office therapy due to mental health stigma beliefs, and visibility in mental health clinics may be a concern. For patients who opted out of in-home therapy, lack of credibility may have decreased participants’ desire for therapists to enter their home. Despite concerns of mental health stigma and the credibility of the therapy in certain treatment arms, patients in each treatment arm significantly improved in PTSD symptomotology. Moreover, patient characteristics, including satisfaction, stigma, and credibility of the therapy, did not significantly predict treatment outcomes, which demonstrates the robustness of Cognitive Processing Therapy.

The interpretations of relevant interfaces (i.e. the surface and bed) in radar sounding datasets over glaciers and ice sheets are primary boundary conditions in a variety of climate studies and particularly subglacial water routing models. It is therefore necessary to ensure these interpretations are consistent and not affected by cross-track clutter. For the surface interface, interferometry and a family of methods relying on digital elevation models have been used to successfully discriminate cross-track surface clutter. Here we present how interferometry can be applied to the problem of basal clutter from cross-track bed topography. Our approach is based on a comparison of the differential phases of ambiguous reflectors that may represent bed clutter and the differential phase of a reflector in an adjacent area that appears unaffected by basal clutter. The reflector yielding the smallest interferometric phase difference relative to the unambiguous bed reflector is considered to represent its consistent continuation. We successfully demonstrate our approach using 60 MHz center frequency MARFA data collected over Devon Ice Cap in the Canadian Arctic. Finally, we investigate the effects of clutter-affected and interferometry-corrected bed interpretations on ice layer thickness estimates, basal hydraulic head gradients and the potential extent of inferred subglacial water bodies.

Radio-echo sounding (RES) can be used to understand ice-sheet processes, englacial flow structures and bed properties, making it one of the most popular tools in glaciological exploration. However, RES data are often subject to ‘strip noise’, caused by internal instrument noise and interference, and/or external environmental interference, which can hamper measurement and interpretation. For example, strip noise can result in reduced power from the bed, affecting the quality of ice thickness measurements and the characterization of subglacial conditions. Here, we present a method for removing strip noise based on combined wavelet and two-dimensional (2-D) Fourier filtering. First, we implement discrete wavelet decomposition on RES data to obtain multi-scale wavelet components. Then, 2-D discrete Fourier transform (DFT) spectral analysis is performed on components containing the noise. In the Fourier domain, the 2-D DFT spectrum of strip noise keeps its linear features and can be removed with a ‘targeted masking’ operation. Finally, inverse wavelet transforms are performed on all wavelet components, including strip-removed components, to restore the data with enhanced fidelity. Model tests and field-data processing demonstrate the method removes strip noise well and, incidentally, can remove the strong first reflector from the ice surface, thus improving the general quality of radar data.

The Darwin–Hatherton Glacial system (DHGS) connects the East Antarctic Ice Sheet (EAIS) with the Ross Ice Shelf and is a key area for understanding past variations in ice thickness of surrounding ice masses. Here we present the first detailed measurements of ice thickness and grounding zone characteristics of the DHGS as well as new measurements of ice velocity. The results illustrate the changes that occur in glacier geometry and ice flux as ice flows from the polar plateau and into the Ross Ice Shelf. The ice discharge and the mean basal ice shelf melt for the first 8.5 km downstream of the grounding line amount to 0.24 ± 0.05 km3 a−1 and 0.3 ± 0.1 m a−1, respectively. As the ice begins to float, ice thickness decreases rapidly and basal terraces develop. Constructed maps of glacier geometry suggest that ice drainage from the EAIS into the Darwin Glacier occurs primarily through a deep subglacial canyon. By contrast, ice thins to <200 m at the head of the much slower flowing Hatherton Glacier. The glaciological field study establishes an improved basis for the interpretation of glacial drift sheets at the link between the EAIS and the Ross Ice Sheet.

Basal radar reflectivity is the most important measurement for the detection of subglacial water. However, dielectric loss in the overlying ice column complicates the determination of basal reflectivity. Dielectric attenuation is a function of ice temperature and impurity concentration. Temperature distribution is a function of climate history, basal heat flow and vertical strain rate, all of which can be partially inferred from the structure of dated internal layers. Using 11 dated layers, isotope records from Dome C, East Antarctica, and a model of the spatial variation of geothermal flux, we calculate the vertical strain rate and accumulation-rate history, allowing identification of areas where the basal melt rate exceeds 1.5 mm a−1. The accumulation-rate history and vertical strain rates are then used as inputs for a transient temperature model. The model outputs for the present-day temperature distribution are then combined with depth-dependent ionic concentrations to model dielectric loss and infer basal reflectivity. The resulting reflection coefficients are consistent (∼−5 dB) across a variety of subglacial water bodies. We also identify a high reflectivity >−15 dB in Concordia Trench and along suspected subglacial water-flow routes in Vincennes Basin. Highland areas tend to have highly variable reflection coefficients near −30 dB, consistent with an ice–bedrock interface. This combined model also identifies three areas of enhanced basal melting along Concordia Ridge, Concordia Subglacial Lake and Vincennes Basin. Melt at Concordia Subglacial Lake exceeds 5 mm a−1. The inferred basal melt at these locations is not possible without enhanced geothermal flux. We demonstrate how radar-sounding data can provide both input and verification for a self-consistent model of vertical strain, vertical temperature distribution and meltwater distribution.

Subglacial lakes beneath Antarctica’s fast-moving ice streams are known to undergo ∼1 km3 volume changes on annual timescales. Focusing on the MacAyeal Ice Stream (MacIS) lake system, we create a simple model for the response of subglacial water distribution to lake discharge events through assimilation of lake volume changes estimated from Ice, Cloud and land Elevation Satellite (ICESat) laser altimetry. We construct a steady-state water transport model in which known subglacial lakes are treated as either sinks or sources depending on the ICESat-derived filling or draining rates. The modeled volume change rates of five large subglacial lakes in the downstream portion of MacIS are shown to be consistent with observed filling rates if the dynamics of all upstream lakes are considered. However, the variable filling rate of the northernmost lake suggests the presence of an undetected lake of similar size upstream. Overall, we show that, for this fast-flowing ice stream, most subglacial lakes receive >90% of their water from distant distributed sources throughout the catchment, and we confirm that water is transported from regions of net basal melt to regions of net basal freezing. Our study provides a geophysically based means of validating subglacial water models in Antarctica and is a potential way to parameterize subglacial lake discharge events in large-scale ice-sheet models where adequate data are available.

P-band interferometric synthetic aperture radar (InSAR) data at 5 m resolution from Kahiltna Glacier, the largest glacier in the Alaska Range, Alaska, USA, show pronounced spatial variation in penetration depth, δP. We obtained δP by differencing X- and P-band digital elevation models. δP varied significantly over the glacier, but it was possible to distinguish representative zones. In the accumulation area, δP decreased with decreasing elevation from 18 ± 3 m in the percolation zone to 10 ± 4 m in the wet snow zone. In the central portion of the ablation area, a location free of debris and crevasses, we identified a zone of very high δP (34 ± 4 m) which decreased at lower elevations (23 ± 3 m in bare ice and 5-10m in debris-covered ice). We observe that the spatial configuration of δP is consistent with the expected thermal regime of each zone: δP is high in areas where cold firn/ice likely occurs (i.e. percolation zone and upper ablation area) and low in areas where temperate surface firn/ice likely exists (wet snow zone and lower ablation area). We suggest that the very high δP observed in the upper ablation area is due to the presence of a cold surface layer.

Recent acceleration and thinning of Thwaites Glacier, West Antarctica, motivates investigation of the controls upon, and stability of, its present ice-flow pattern. Its eastern shear margin separates Thwaites Glacier from slower-flowing ice and the southern tributaries of Pine Island Glacier. Troughs in Thwaites Glacier’s bed topography bound nearly all of its tributaries, except along this eastern shear margin, which has no clear relationship with regional bed topography along most of its length. Here we use airborne ice-penetrating radar data from the Airborne Geophysical Survey of the Amundsen Sea Embayment, Antarctica (AGASEA) to investigate the nature of the bed across this margin. Radar data reveal slightly higher and rougher bed topography on the slower-flowing side of the margin, along with lower bed reflectivity. However, the change in bed reflectivity across the margin is partially explained by a change in bed roughness. From these observations, we infer that the position of the eastern shear margin is not strongly controlled by local bed topography or other bed properties. Given the potential for future increases in ice flux farther downstream, the eastern shear margin may be vulnerable to migration. However, there is no evidence that this margin is migrating presently, despite ongoing changes farther downstream.

Satellite altimetric time series allow high-precision monitoring of ice-sheet mass balance. Understanding elevation changes in these regions is important because outlet glaciers along ice-sheet margins are critical in controlling flow of inland ice. Here we discuss a new airborne altimetry dataset collected as part of the ICECAP (International Collaborative Exploration of the Cryosphere by Airborne Profiling) project over East Antarctica. Using the ALAMO (Airborne Laser Altimeter with Mapping Optics) system of a scanning photon-counting lidar combined with a laser altimeter, we extend the 2003–09 surface elevation record of NASA’s ICESat satellite, by determining cross-track slope and thus independently correcting for ICESat’s cross-track pointing errors. In areas of high slope, cross-track errors result in measured elevation change that combines surface slope and the actual Δz/Δt signal. Slope corrections are particularly important in coastal ice streams, which often exhibit both rapidly changing elevations and high surface slopes. As a test case (assuming that surface slopes do not change significantly) we observe a lack of ice dynamic change at Cook Ice Shelf, while significant thinning occurred at Totten and Denman Glaciers during 2003–09.

Thwaites Glacier, Antarctica, is experiencing rapid change and its mass could, if disgorged into the ocean, lead to ∼1 m of global sea-level rise. Efforts to model flow for Thwaites Glacier are strongly dependent on an accurate model of bed topography. Airborne radar data collected in 2004/05 provide 35 000 line km of bed topography measurements sampled every 20 m along track. At ∼15 km track spacing, this extensive dataset nevertheless misses considerable important detail, particularly: (1) resolution of mesoscale channelized morphology that can guide glacier flow; and (2) resolution of small-scale roughness between the track lines that is critical for determining topographic resistance to flow. Both issues are addressed using a conditional simulation that merges a stochastic realization (an unconditional simulation) with a deterministic surface. A conditional simulation is a non-unique interpolation that reproduces observed statistical behavior without affecting data values. Channels are resolved in the deterministic surface using an interpolation algorithm designed for sinuous channels. Small-scale roughness is resolved using a statistical analysis that accounts for heterogeneity, including an abrupt transition between ‘lowland’ and ‘highland’ morphology. Multiple realizations of the unconditional simulation can be generated to sample the probability space and allow error characterization in flow modeling.

The effect of Jerusalem artichoke (Helianthus tuberosus L. # HELTU) density and duration of interference in soybeans [Glycine max (L.) Merr. ‘Hodgson 78’] was investigated in two studies. Jerusalem artichoke densities of 1, 2, and 4 tubers/m of row reduced soybean seed yield by 31, 59, and 71%, respectively. Soybean height, branches/plant, pods/plant, and seed weight were usually reduced by all three weed densities. Soybean leaf area and relative growth rates were reduced by densities of 2 and 4 tubers/m of crop row, and net assimilation rate (NAR) was reduced by 4 tubers/m of crop row. Jerusalem artichoke interference at 4 tubers/m of row for 4, 6, 8, and 20 weeks (full season) reduced soybean yields 9, 10, 38, and 82%, respectively. Branches/plant, pods/plant, and seeds/plant were reduced after 8 weeks of interference. These results suggest that Jerusalem artichoke is highly competitive with soybean and should be controlled within 6 weeks after planting.

The effect of quackgrass [Agropyron repens (L.) Beauv.] density and duration of interference on soybeans [Glycine max (L.) Merr.] was investigated in two studies. In the density study, the average reduction in soybean yield by quackgrass densities of 520 and 910 shoots/m2 was 19 and 55%, respectively. Quackgrass densities of 95 and 160 shoots/m2 did not significantly reduce soybean yields. The number of branches that produced pods, the number of pods and seeds per plant, and soybean height were reduced by the two highest densities. In 1980, quackgrass densities of 265 and 595 shoots/m2 reduced soybean leaf area and plant dry weight. Leaf area partitioning (LAP), leaf weight partitioning (LWP), and net assimilation rate (NAR) of soybeans were reduced by a quackgrass density of 595 shoots/m2. In the duration study, interference by a natural stand of quackgrass for 6 weeks, 8 weeks, and full-season decreased soybean yield an average of 11, 23, and 33%, respectively. Results from the duration study suggest that a selective postemergence herbicide for the control of quackgrass in soybeans would be beneficial if available.

A seed remover using a modified water-spray system was constructed to separate weed seeds rapidly and effectively from a silt loam soil A 1-kg soil sample can be washed through the seed remover in 6 min. Using a 500-μ mesh sieve, only 70% of small shepherdspurse seeds were recovered, while 100% of larger seeds of henbit, curly dock, wild oats, and downy brome were recovered. The modified seed remover system reduced the required man-hours by more than 50% compared to previous systems.

The effects of five soil fungi, endemic to the western United States, were evaluated for disease reaction, root dry weights and shoot dry weights on five grass species. The undesired grass, downy brome or medusahead, the perennial forage species, squirreltail or western wheatgrass, and winter wheat were susceptible to take-all. Downy brome, medusahead, squirreltail, and winter wheat were susceptible to crown rot. The desired grasses, squirreltail, western wheatgrass, and winter wheat, were susceptible to barepatch. Crown rot is adapted to dry soils and may be a potential biological control on downy brome and medusahead in the arid environment of the western U.S.