Ocean melting has thinned Antarctica's ice shelves at an increasing rate over the past two decades, leading to loss of grounded ice. The Ross Ice Shelf is currently close to steady state but geological records indicate that it can disintegrate rapidly, which would accelerate grounded ice loss from catchments equivalent to 11.6 m of global sea level rise. Here, we use data from the ROSETTA-Ice airborne survey and ocean simulations to identify the principal threats to Ross Ice Shelf stability. We locate the tectonic boundary between East and West Antarctica from magnetic anomalies and use gravity data to generate a new highresolution map of sub-ice-shelf bathymetry. The tectonic imprint on the bathymetry constrains sub-ice-shelf ocean circulation, protecting the ice shelf grounding line from moderate changes in global ocean heat content. In contrast, local, seasonal production of warm upper-ocean water near the ice front drives rapid ice shelf melting east of Ross Island, where thinning would lead to faster grounded ice loss from both the East and West Antarctic ice sheets. We confirm high modelled melt rates in this region using ROSETTA-Ice radar data. Our findings highlight the significance of both the tectonic framework and local oceanatmosphere exchange processes near the ice front in determining the future of the Antarctic Ice Sheet.
Geoengineered groundwater systems within seven large (23 × 104–9 × 106 m2), deep‐seated (40–300 m), previously slow‐creep (2–5 mm/yr.) schist landslides in the Cromwell Gorge responded systematically to 11 large (Mw > 6.2) earthquakes at epicentral distances of 130–630 km between 1990 and 2013. Landslide groundwater is strongly compartmentalized and often overpressured, with permeability of 10−17 to 10−13 m2 and flow occurring primarily through fracture and crush zones, hindered by shears containing clayey gouge. Hydrological monitoring recorded earthquake‐induced meter‐ or centimeter‐scale changes in groundwater levels (at 22 piezometers) and elevated drainage discharge (at 11 V notch weirs). Groundwater level changes exhibited consistent characteristics at all monitoring sites, with time to peak‐pressure changes taking ~1 month and recovery lasting 0.7–1.2 years. Changes in weir flow rate near instantaneous (peaking 0–6 h after earthquakes) and followed by recession lasting ~1 month. Responses at each site were systematic from one earthquake to another in terms of duration, polarity, and amplitude. Consistent patterns in amplitude and duration have been compared between sites and with earthquake parameters (peak ground acceleration (PGA), seismic energy density (e), shaking duration, frequency bandwidth, and site amplitude). Shaking at PGA ~0.27% g and e ~ 0.21 J m−3 induced discernable gorge‐wide hydrological responses at thresholds comparable to other international examples. Groundwater level changes modeled using a damped harmonic oscillator characterize the ability of the system to resist and recover from extrinsic perturbations. The observed character of response reflects spectral characteristics as well as energy. Landslide hydrological systems appear most susceptible to damage and hydraulic changes when earthquakes emit broad‐frequency, long‐duration, high‐amplitude ground motion.
Back Background ground The prevalence of hypertension under different treatment guidelines and peripheral arterial disease are unknown in many low and middle-income populations. Methods Methods A community sample of adults ≥18 years in Léogâne, Haiti, had blood pressure and anklebrachial index (ABI) measurements in the Summers of 2014 and 2015 in addition to surveys to ascertain knowledge related to awareness and consequences of hypertension. Descriptive statistics for prevalence of hypertension and peripheral artery disease were performed. Sensitivity analyses were performed for hypertension prevalence under the Eighth Joint National Committee (JNC) and 2017 guidelines.
Reconstructions of the past relative positions of northern and southern Zealandia provide important constraints on the orientation and amount of strain accumulated between rigid plates within the Australia–Pacific plate tectonic circuit. This configuration of plates ultimately determines how, where and when sedimentary basins formed during and since continental breakup along the eastern margin of Gondwana.
Although the first-order geometry of Zealandia is well established, uncertainty remains regarding plate motions through the latest Cretaceous to Eocene. Recent reconstructions are, in some cases, inconsistent with geological observations at key time intervals, highlighting uncertainties inherent in plate reconstructions for the south-west Pacific.
Building on previous tectonic reconstructions and incorporating published seafloor magnetic interpretations, paleomagnetic observations and geological constraints (e.g. terrane geometry and distribution), we developed a tectonic framework to reconstruct Zealandia back through to the latest Cretaceous.
Using GPlates, we use a simple double-hinge slat concept to describe Neogene deformation within the New Zealand plate boundary zone, while the geometry of northern and southern Zealandia during the Eocene is modified from recently published models based on geologic considerations. This study ultimately highlights the need for integrated studies of the Zealandia plate circuit.
Objective
Screening for social determinants of health (SDH) has been widely adopted to identify child health risks associated with exposure to material hardship. Whereas SDH screening typically addresses a 12-month span, we sought to compare the prevalence of exposure to present (within the past year) as compared to recent (2–4 years ago) hardship among children in the United States.
Methods
We analyzed the 2014 Survey of Income and Program Participation, a nationally representative survey that interviewed participating households annually between 2014 and 2017. We included data from households with children in all waves. As of 2017, households were categorized as (1) experiencing present hardship (within the last year); (2) experiencing recent but not present hardship (any year between 2014 and 2016); and (3) experiencing no hardship over the 4-year period.
Results
Of 2422 households, 27% experienced present hardship and 29% experienced recent but not present hardship. Households presently experiencing hardship were more likely to have Medicaid insurance, less likely to be married, and had more children than families who had experienced recent hardship. However, these groups were similar on caregivers’ educational attainment, race/ethnicity, language spoken in the home, and age of the youngest child.
Conclusions
Our results suggest that clinical screening tools for SDH that use a 12-month time frame risk missing many children who have recently (within the past 4 years) experienced material hardship and may benefit from interventions to improve social support; a longer time frame could provide clinicians with valuable information for understanding social factors that impact child health and development.
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