Description: Predictions of marine ice-sheet behaviour require models able to simulate grounding-line migration. We present results of an intercomparison experiment for plan-view marine ice-sheet models. Verification is effected by comparison with approximate analytical solutions for flux across the grounding line using simplified geometrical configurations (no lateral variations, no buttressing effects from lateral drag). Perturbation experiments specifying spatial variation in basal sliding parameters permitted the evolution of curved grounding lines, generating buttressing effects. The experiments showed regions of compression and extensional flow across the grounding line, thereby invalidating the boundary layer theory. Steady-state grounding-line positions were found to be dependent on the level of physical model approximation. Resolving grounding lines requires inclusion of membrane stresses, a sufficiently small grid size (〈500m), or subgrid interpolation of the grounding line. The latter still requires nominal grid sizes of 〈5 km. For larger grid spacings, appropriate parameterizations for ice flux may be imposed at the grounding line, but the short-time transient behaviour is then incorrect and different from models that do not incorporate grounding-line parameterizations. The numerical error associated with predicting grounding-line motion can be reduced significantly below the errors associated with parameter ignorance and uncertainties in future scenarios.

Description: Ice-shelf channels are long curvilinear tracts of thin ice found on Antarctic ice shelves. Many of them originate near the grounding line, but their formation mechanisms remain poorly understood. Here we use ice-penetrating radar data from Roi Baudouin Ice Shelf, East Antarctica, to infer that the morphology of several ice-shelf channels is seeded upstream of the grounding line by large basal obstacles indenting the ice from below. We interpret each obstacle as an esker ridge formed from sediments deposited by subglacial water conduits, and calculate that the eskers’ size grows towards the grounding line where deposition rates are maximum. Relict features on the shelf indicate that these linked systems of subglacial conduits and ice-shelf channels have been changing over the past few centuries. Because ice-shelf channels are loci where intense melting occurs to thin an ice shelf, these findings expose a novel link between subglacial drainage, sedimentation and ice-shelf stability.

Description: Background Lenalidomide has dual antiangiogenic and immunomodulatory properties and confirmed antitumor activity in hematologic malignancies. A phase II study investigating the safety and efficacy of continuous lenalidomide in recurrent ovarian cancer patients was initiated. Patients and methods Patients with histologically confirmed epithelial ovarian, fallopian tube or primary peritoneal carcinoma, with asymptomatic recurrence 6 months after prior therapy were treated with continuous oral lenalidomide (20 mg/day). The primary end point was to evaluate efficacy according to the rate of disease control at 4 months. Secondary objectives were progression-free survival (PFS) and safety. Results Most of the 45 patients enrolled and treated had serous histology (78%) and a single line of prior chemotherapy (73%). Median platinum-free interval (PFI) was 11.3 months (range 6.9–56.8). Clinical benefit at 4 months was 38% [95% confidence interval (CI) 23% to 53%]. A 59% disease control rate was reported in patients with a PFI 〉12 months versus 24% with PFI of 6–12 months ( P = 0.023). Four patients had RECIST partial responses and 21 had stable disease. CA125 responses were reported in eight patients, including one complete response. Median PFS was 3.4 months (95% CI 2.4–4.4). Most frequent toxicity was hematologic, notably grade 3–4 neutropenia in 29% of patients, along with fatigue (69%), gastrointestinal toxicity (constipation 53%, abdominal pain 49%, diarrhea 38%, nausea/vomiting 36%) and thrombosis (11%). Eight patients withdrew due to related toxicity. Conclusions Lenalidomide shows interesting efficacy in late recurrent ovarian cancer patients. Toxicity was mainly hematologic, gastrointestinal and venous thrombosis. Future studies will evaluate combination of lenalidomide with chemotherapy agents. Clinicaltrials.gov NCT01111903.