The Antarctic mantle, bounded between the core and the Mohorovicǐćdiscontinuity, is one of the most difficult targets of study on Earth because of ice cover and rare outcrops. A multidisciplinary approach is adopted in this volume, using petrology, geochemistry, remote-sensed data and geodesy to characterize the Antarctic mantle. This characterization has application to rates of glacial isostatic adjustment, heat flow, sea-level rise and tectonics. It places the Antarctic mantle domain in a global framework on a scale not attempted before. In this chapter we review the historical development of mantle studies in Antarctica, outline current research directions, introduce the volume chapters and pro-vide a summary and outlook.

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Numerous unresolved issues exist regarding the Antarctic lithosphere, especially in terms of density, temperature, and compositional structure. For example, contemporary estimates of the Moho depth from different geophysical methods show significant discrepancies of 10-20 km in large areas of the continent. While seismological methods suffer from a limited station coverage and ice reverberation, potential field methods, such as gravity studies, are inherently non-unique. By modelling densities and seismic velocities in a consistent way and accounting for thermodynamically stable mineral phases of rocks under in-situ pressure and temperature conditions, we are able to compensate for the sparseness of data in Antarctica and reduce inconsistencies and ambiguities of separate geophysical methods to a large extent. Gravity gradient data from ESA’ s satellite mission ‘GOCE’ are used to constrain the density distribution within the lithosphere in an integrated 3D model of the Antarctic continent, whereas independent seismic estimates serve as a benchmark for the robustness of the results. Intra-crustal density variations are inverted from airborne gravity data and evaluated against thermodynamic modelling results of potential upper crustal rock compositions. As a main outcome, we present a new crustal thickness map of Antarctica. It includes varying density contrast at the Moho and exhibits detailed thickness changes in East Antarctica, also in regions with sparse or absent seismic station coverage. At locations where compositions of xenoliths from deeper sources are available, we analyse the model’s sensitivity to introduction of such regional information. As an example of the applicability of our model for further studies, we demonstrate how its deep thermal field is used to derive upper mantle viscosities for glacial isostatic adjustment (GIA) modelling. @en

Despite increasing recognition of the efficacy, safety, and cost-effectiveness of bariatric/metabolic surgery in the treatment of type 2 diabetes, few patients who may be appropriate candidates and may benefit from this type of surgery avail themselves of this treatment option. To identify conceptual and practical barriers to appropriate use of surgical procedures, a Policy Lab was hosted at the 3rd World Congress on Interventional Therapies for Type 2 Diabetes on 29 September 2015. Twenty-six stakeholders participated in the Policy Lab, including academics, clinicians, policy-makers, industry leaders, and patient representatives. Participants were provided with a summary of available evidence about the cost-effectiveness of bariatric/metabolic surgery and the costs of increasing the use of bariatric/metabolic surgery, using U.K. and U.S. scenarios as examples of distinct health care systems. There was widespread agreement among this group of stakeholders that bariatric/ metabolic surgery is a legitimate and cost-effective approach to the treatment of type 2 diabetes in obese patients. The following four building blocks were identified to facilitate policy changes: 1) communicating the scale of the costs and harms associated with rising prevalence of type 2 diabetes; 2) properly articulating the role of bariatric/metabolic surgery for certain population groups; 3) identifying new funding sources for bariatric/metabolic surgery; and 4) incorporating bariatric/ metabolic surgery into the appropriate clinical pathways. Although more research is needed to identify specific clinical scenarios for the prioritization of bariatric/ metabolic surgery, the case appears to be strong enough to engage relevant policymakers and practitioners in a concerted discussion of how to better use metabolic surgical resources in conjunction with other interventions in good diabetes practice.

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