Tidewater-glacier response to supraglacial lake drainage.

The flow speed of the Greenland Ice Sheet changes dramatically in inland regions when surface meltwater drains to the bed. But ice-sheet discharge to the ocean is dominated by fast-flowing outlet glaciers, where the effect of increasing surface melt on annual discharge is unknown. Observations of a supraglacial lake drainage at Helheim Glacier, and a consequent velocity pulse propagating down-glacier, provide a natural experiment for assessing the impact of changes in injected meltwater, and allow us to interrogate the subglacial hydrological system. We find a highly efficient subglacial drainage system, such that summertime lake drainage has little net effect on ice discharge. Our results question the validity of common remote-sensing approaches for inferring subglacial conditions, knowledge of which is needed for improved projections of sea-level rise.

Hydraulic transmissivity inferred from ice-sheet relaxation following Greenland supraglacial lake drainages.

Surface meltwater reaching the base of the Greenland Ice Sheet transits through drainage networks, modulating the flow of the ice sheet. Dye and gas-tracing studies conducted in the western margin sector of the ice sheet have directly observed drainage efficiency to evolve seasonally along the drainage pathway. However, the local evolution of drainage systems further inland, where ice thicknesses exceed 1000 m, remains largely unknown. Here, we infer drainage system transmissivity based on surface uplift relaxation following rapid lake drainage events. Combining field observations of five lake drainage events with a mathematical model and laboratory experiments, we show that the surface uplift decreases exponentially with time, as the water in the blister formed beneath the drained lake permeates through the subglacial drainage system. This deflation obeys a universal relaxation law with a timescale that reveals hydraulic transmissivity and indicates a two-order-of-magnitude increase in subglacial transmissivity (from 0.8 ± 0.3 [Formula: see text] to 215 ± 90.2 [Formula: see text]) as the melt season progresses, suggesting significant changes in basal hydrology beneath the lakes driven by seasonal meltwater input.

Patient-Centered Medical Homes in Community Oncology Practices: Changes in Spending and Care Quality Associated With the COME HOME Experience.

PURPOSE: We examined whether the Community Oncology Medical Home (COME HOME) program, a medical home program implemented in seven community oncology practices, was associated with changes in spending and care quality. PATIENTS AND METHODS: We compared outcomes from elderly fee-for-service Medicare beneficiaries diagnosed between 2011 and 2015 with breast, lung, colorectal, thyroid, or pancreatic cancer, lymphoma, or melanoma and served by COME HOME practices before and after program implementation versus similar beneficiaries served by other geographically proximate oncologists. Difference-in-differences analysis compared changes in outcomes for COME HOME patients versus concurrent controls. Propensity score matching and regression methods were adjusted for clinical and sociodemographic differences. Our primary outcome was 6-month medical spending per beneficiary. Secondary outcomes included 6-month out-of-pocket spending, inpatient and ambulatory care-sensitive hospitalizations, readmissions, length of stay, and emergency department and evaluation and management visits. RESULTS: Before COME HOME, 6-month medical spending was $2,975 higher for the study group compared with controls (95% CI, $1,635 to $4,315; P < .001) and increasing at a similar rate. After intervention, this difference was reduced to $318 (95% CI, -$1,105 to $1,741; P = .661), a significant change of -$2,657 (95% CI, -$4,631 to -$683; P = .008) or 8.1% savings relative to 6-month average spending ($32,866). COME HOME was also associated with significantly reduced (10.2 %) emergency department visits per 1,000 patients per 6-month period ( P = .024). There were no statistically significant differences in other outcomes. CONCLUSION: COME HOME was associated with reduced Medicare spending and improved emergency department use. The patient-centered medical home model holds promise for oncology practices, but improvements were not uniform.

Community Oncology Medical Homes: Physician-Driven Change to Improve Patient Care and Reduce Costs.

Although the patient-centered medical home is a well-established model of care for primary care providers, adoption by specialty providers has been relatively limited. Recently, there has been particular interest in developing specialty medical homes in medical oncology because of practice variation, care fragmentation, and high overall costs of care. In 2012, the Center for Medicare and Medicaid Innovation awarded Innovative Oncology Business Solutions a 3-year grant for their Community Oncology Medical Home (COME HOME) program to implement specialty medical homes in seven oncology practices across the country. We report our early experience and lessons learned.Through September 30, 2014, COME HOME has touched 16,353 unique patients through triage encounters, patient education visits, or application of clinical pathways. We describe the COME HOME model and implementation timeline, profile use of key services, and report patient satisfaction. Using feedback from practice sites, we highlight patient-centered innovations and overall lessons learned.COME HOME incorporates best practices care driven by triage and clinical pathways, team-based care, active disease management, enhanced access and care, as well as financial support for the medical home infrastructure. Information technology plays a central role, supporting both delivery of care and performance monitoring. Volume of service use has grown steadily over time, leveling out in second quarter 2014. The program currently averages 1,265 triage encounters, 440 extended hours visits, and 655 patient education encounters per month.COME HOME offers a patient-centered model of care to improve quality and continuity of care.

Greenland supraglacial lake drainages triggered by hydrologically induced basal slip.

Water-driven fracture propagation beneath supraglacial lakes rapidly transports large volumes of surface meltwater to the base of the Greenland Ice Sheet. These drainage events drive transient ice-sheet acceleration and establish conduits for additional surface-to-bed meltwater transport for the remainder of the melt season. Although it is well established that cracks must remain water-filled to propagate to the bed, the precise mechanisms that initiate hydro-fracture events beneath lakes are unknown. Here we show that, for a lake on the western Greenland Ice Sheet, drainage events are preceded by a 6-12 hour period of ice-sheet uplift and/or enhanced basal slip. Our observations from a dense Global Positioning System (GPS) network allow us to determine the distribution of meltwater at the ice-sheet bed before, during, and after three rapid drainages in 2011-2013, each of which generates tensile stresses that promote hydro-fracture beneath the lake. We hypothesize that these precursors are associated with the introduction of meltwater to the bed through neighbouring moulin systems (vertical conduits connecting the surface and base of the ice sheet). Our results imply that as lakes form in less crevassed, interior regions of the ice sheet, where water at the bed is currently less pervasive, the creation of new surface-to-bed conduits caused by lake-draining hydro-fractures may be limited.