Growing evidence has demonstrated the importance of ice shelf buttressing on the inland grounded ice, especially if it is resting on bedrock below sea level. Much of the Southern Antarctic Peninsula ...satisfies this condition and also possesses a bed slope that deepens inland. Such ice sheet geometry is potentially unstable. We use satellite altimetry and gravity observations to show that a major portion of the region has, since 2009, destabilized. Ice mass loss of the marine-terminating glaciers has rapidly accelerated from close to balance in the 2000s to a sustained rate of –56 ± 8 gigatons per year, constituting a major fraction of Antarctica's contribution to rising sea level. The widespread, simultaneous nature of the acceleration, in the absence of a persistent atmospheric forcing, points to an oceanic driving mechanism.
We present a reassessment of input‐output method ice mass budget estimates for the Abbot and Getz regions of West Antarctica using CryoSat‐2‐derived ice thickness estimates. The mass budget is ...8 ± 6 Gt yr−1 and 5 ± 17 Gt yr−1 for the Abbot and Getz sectors, respectively, for the period 2006–2008. Over the Abbot region, our results resolve a previous discrepancy with elevation rates from altimetry, due to a previous 30% overestimation of ice thickness. For the Getz sector, our results are at the more positive bound of estimates from other techniques. Grounding line velocity increases up to 20% between 2007 and 2014 alongside mean elevation rates of −0.67 ± 0.13 m yr−1 between 2010 and 2013 indicate the onset of a dynamic thinning signal. Mean snowfall trends of −0.33 m yr−1 water equivalent since 2006 indicate recent mass trends are driven by both ice dynamics and surface processes.
Key Points
Reassessment of Abbot sector mass balance using CryoSat‐2‐derived ice thicknesses provides better agreement with other techniques
Discrepancies in input‐output method estimates primarily due to overestimation of ice thickness for these regions in previous products
Velocity increases and negative elevation rates at the Getz grounding line indicate dynamic imbalance and probable grounding line retreat
Plain Language Summary
There are large differences in mass balance estimates (the net loss or gain of ice mass) from independent techniques for glaciers draining into the Abbot and Getz Ice Shelves of West Antarctica. This is believed to be primarily due to previous uncertainties in the knowledge of ice thickness in these regions at the grounding line (the point where the ice sheet detaches from the bedrock and begins to float). We use new higher‐accuracy ice thickness measurements derived from ESA's CryoSat‐2 satellite to reassess the mass balance for these regions for the 2006–2008 period. Our results provide better agreement with other techniques and resolve outstanding discrepancies over the Abbot region in particular. We also find that grounding line retreat, a key indicator of ice sheet imbalance, has likely to have been occurring over the Getz region since this period. Our results demonstrate the ability for the satellite to more accurately calculate the mass loss from these regions and better constrain their subsequent contribution to sea level rise.
This is the first (Paper I) of three companion papers focused respectively, on the estimates of the errors in ice thickness retrieved from pulsed ground-penetrating radar (GPR) data, on how to ...estimate the errors at the grid points of an ice-thickness DEM, and on how the latter errors, plus the boundary delineation errors, affect the ice-volume estimates. We here present a comprehensive analysis of the various errors involved in the computation of ice thickness from pulsed GPR data, assuming they have been properly migrated. We split the ice-thickness error into independent components that can be estimated separately. We consider, among others, the effects of the errors in radio-wave velocity and timing. A novel aspect is the estimate of the error in thickness due to the uncertainty in horizontal positioning of the GPR measurements, based on the local thickness gradient. Another novel contribution is the estimate of the horizontal positioning error of the GPR measurements due to the velocity of the GPR system while profiling, and the periods of GPS refreshing and GPR triggering. Their effects are particularly important for airborne profiling. We illustrate our methodology through a case study of Werenskioldbreen, Svalbard.
This paper is the second (Paper II) in a set of studies concerning the errors involved in the estimate of ice thickness and ice volume. Here we present a detailed analysis of the errors involved in ...the generation of ice-thickness DEMs constructed, most often, from GPR data, complemented by boundary data and sometimes, additional synthetic data arising from estimates based on theoretical considerations supported by independent data. We describe a complete methodology of error analysis that, starting from the errors in the data, propagates them to the grid nodes. In turn, the interpolation error at the grid nodes is calculated using a novel procedure that also provides an estimate of the bias introduced by the interpolation process. Finally, both errors are combined at the grid nodes to produce a gridpoint-dependent error estimate, which is complemented by an overall error estimate providing an assessment of the quality of the DEM. This methodology is illustrated with the case study of Werenskioldbreen, a land-terminating polythermal glacier in Svalbard.
This paper is the third (Paper III) in a set of studies of the errors involved in the estimate of ice thickness and ice volume. Here we present a methodology to estimate the error in the calculation ...of the volume of an ice mass from an ice-thickness DEM. We consider the two main error sources: the ice-thickness error at each DEM grid point and the uncertainty in the boundary delineation. To accurately estimate the volume error due to the error in thickness of the DEM, it is crucial to determine the degree of correlation among the ice-thickness errors at the grid points. We find that the two-dimensional integral range, which represents the equivalent area of influence of each independent value, allows estimation of the equivalent number of independent values of error within the DEM. Hence, it provides an easy way to obtain the volume error resulting from the uncertainty in ice thickness of a DEM. We show that the volume error arising from the uncertainty in boundary delineation, often neglected in the literature, can be of the same order of magnitude as the volume error resulting from ice-thickness errors. We illustrate our methodology through the case study of Werenskioldbreen, Svalbard.
The number of indications for total hip replacement (THR) and total knee replacement (TKR) surgery is increasing. Enhanced recovery after surgery (ERAS) represents the next step in the evolution of ...standardised care. The primary aim of this study is to measure the in-hospital 30-day medical and surgical postoperative complications rate. The study's secondary aims are to determine the length of stay, 30-day mortality rate, 30-day reoperation and readmission rates, the ERAS overall compliance and predefined ERAS individual items compliance.
This multicentre, prospective, observational study will include adult patients (aged >18 years) undergoing elective THR and TKR surgery. Consecutive patients undergoing surgery within the 2-month data collection period will be included. Centres that offer the THR and/or TKR surgery will be eligible to participate. The data collection will be done through an online data collection form via a secure, password-protected platform at each centre with predefined data fields.
Ethical approval for this study has been obtained from the Comité de Ética de la Investigación de la Comunidad Autónoma de Aragón (C.P.-C.I. PI18/135; on 23 May 2018). It was prospectively registered on 27 June 2018, at www.clinicaltrials.gov with identification no. NCT03570944.
The study will be disseminated through the SPARN-RedGERM, SEDAR, GERM and through social media. Peer-reviewed publications will be published under corporate authorship, including POWER.2 Study Group and SPARN-RedGERM.
Despite the effectiveness of plasma exchange (PEX) and immunosuppressants in the treatment of acquired thrombotic thrombocytopenic purpura (aTTP), a number of patients still die as a result of the ...disease. Whether caplacizumab could rescue these patients remains still unsettled. The objective of this study was to characterise mortality patterns and prognostic factors in the first episode of aTTP.
We queried the Spanish TTP Registry for patients with a diagnosis of aTTP in their presenting episode who fulfilled complete clinical and follow-up data (
n
= 102). The patients were diagnosed between 2004 and 2018, and all were treated with daily PEX and corticosteroids. Clinical and laboratory data were analysed at diagnosis and during the treatment course.
Eight patients (7.7%) died between 12 h and 36 days after presentation, and could be classified into three patterns: death before treatment, early death driven by acute cardiac or neurologic events, and late death due to unremitted aTTP. Stupor or coma at diagnosis and platelet count < 20 × 10
9
/L by the 6th treatment day were independently associated with increased risk of death.
Stupor or coma at diagnosis and lack of response to PEX by the 6th day in patients experiencing the first episode of aTTP are strong predictors of mortality. These patients could be rescued by novel agents aimed at halting the microvascular thrombosis until adequate immunosuppression is achieved.
We performed a retrospective multicenter study including 140 patients with relapsed/refractory (R/R) diffuse large B cell lymphoma (DLBCL) who underwent allogeneic hematopoietic stem cell ...transplantation (allo-SCT) from March 1995 to November 2018. Our objective was to analyze long term outcomes. Seventy-four percent had received a previous auto-SCT (ASCT) and the median number of lines pre-allo-SCT was 3 (range 1-9). Three year-event free survival (EFS) and overall survival (OS) were 38% and 44%, respectively. Non-relapse mortality (NRM) at day 100 was 19%. Cumulative incidence of grade III-IV acute graft versus host disease (GVHD) at day 100 was 16% and moderate/severe chronic GVHD at 3 years 34%. Active disease at allo-SCT (HR 1.95, p = 0.039) (HR 2.19, p = 0.019), HCT-CI ≥ 2 (2.45, p = 0.002) (HR 2.33, p = 0.006) and donor age >37 years (HR 2.75, p = 0.014) (HR 1.98, p = 0.043) were the only independent variables both for PFS and OS, respectively. NRM was significantly modified by HCT-CI ≥ 2 (HR 4.8, p = 0.008), previous ASCT (HR 4.4, p = 0.048) and grade III-IV acute GVHD on day 100 (HR 6.13, p = 0.016). Our data confirmed that allo-SCT is a curative option for patients with R/R DLBCL, displaying adequate results for fit patients with chemosensitive disease receiving an allo-SCT from a young donor.
PDF
