Surface constraints on the depth of the Atlantic meridional overturning circulation: Southern Ocean versus North Atlantic

Paleoclimate proxy evidence suggests that the Atlantic meridional overturning circulation (AMOC) was about 1000 m shallower at the Last Glacial Maximum (LGM) compared to the present. Yet it remains unresolved what caused this glacial shoaling of the AMOC, and many climate models instead simulate a deeper AMOC under LGM forcing. While some studies suggest that Southern Ocean surface buoyancy forcing controls the AMOC depth, others have suggested alternatively that North Atlantic surface forcing or interior diabatic mixing plays the dominant role. To investigate the key processes that set the AMOC depth, here we carry out a number of MITgcm ocean-only simulations with surface forcing fields specified from the simulation results of three coupled climate models that span much of the range of glacial AMOC depth changes in phase 3 of the Paleoclimate Model Intercomparison Project (PMIP3). We find that the MITgcm simulations successfully reproduce the changes in AMOC depth between glacial and modern conditions simulated in these three PMIP3 models. By varying the restoring time scale in the surface forcing, we show that the AMOC depth is more strongly constrained by the surface density field than the surface buoyancy flux field. Based on these results, we propose a mechanism by which the surface density fields in the high latitudes of both hemispheres are connected to the AMOC depth. We illustrate the mechanism using MITgcm simulations with idealized surface forcing perturbations as well as an idealized conceptual geometric model. These results suggest that the AMOC depth is largely determined by the surface density fields in both the North Atlantic and the Southern Ocean

Senescent cancer-associated fibroblasts in pancreatic adenocarcinoma restrict CD8+ T cell activation and limit responsiveness to immunotherapy in mice

Senescent cells within tumors and their stroma exert complex pro- and anti-tumorigenic functions. However, the identities and traits of these cells, and the potential for improving cancer therapy through their targeting, remain poorly characterized. Here, we identify a senescent subset within previously-defined cancer-associated fibroblasts (CAFs) in pancreatic ductal adenocarcinomas (PDAC) and in premalignant lesions in mice and humans. Senescent CAFs isolated from mouse and humans expressed elevated levels of immune-regulatory genes. Depletion of senescent CAFs, either genetically or using the Bcl-2 inhibitor ABT-199 (venetoclax), increased the proportion of activated CD

Wear of composite ceramics in mixed-material combinations in total hip replacement under adverse edge loading conditions

Further development of ceramic materials for total hip replacement aim to increase fracture toughness and further reduce the incidence of bearing fracture. Edge loading due to translational mal positioning (microseparation) has replicated stripe wear, wear rates, and bimodal wear debris observed on retrievals. This method has replicated the fracture of early zirconia ceramic-on-ceramic bearings. This has shown the necessity of introducing microseparation conditions to the gait cycle when assessing the tribological performance of new hip replacement bearings. Two novel ceramic matrix composite materials, zirconia-toughened alumina (ZTA) and alumina-toughened zirconia (ATZ), were developed by Mathys Orthop€adie GmbH. In this study, ATZon- ATZ and ZTA-on-ZTA bearing combinations were tested and compared with alumina-on-alumina (Al2O3-on-Al2O3) bearings under adverse microseparation and edge loading conditions using the Leeds II physiological anatomical hip joint simulator. The wear rate (695% confidence limit) of ZTA-on-ZTA was 0.1460.10 mm3/million cycles and that of ATZ-on-ATZ was 0.0660.004 mm3/million cycles compared with a wear rate of 0.7461.73 mm3/million cycles for Al2O3- on-Al2O3 bearings. Stripe wear was evident on all bearing combinations; however, the stripe formed on the ATZ and ZTA femoral heads was thinner and shallower that that formed on the Al2O3 heads. Posttest phase composition measurements for both ATZ and ZTA materials showed no significant change in the monoclinic zirconia content. ATZon- ATZ and ZTA-on-ZTA showed superior wear resistance properties when compared with Al2O3-on-Al2O3 under adverse edge loading conditions. VC 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 00B: 000–000, 2013

Report of the National Science Foundation-Sponsored GeoEngineering Extreme Events Reconnaissance (GEER) Team

The L’Aquila earthquake occurred on April 6 2009 at 03:32:39 local time. The earthquake was located in the central Italy region of Abruzzo. Much of the damage occurred in the capital city of L’Aquila, a city of approximate population 73000, although many small villages in the surrounding regions were significantly damaged including Paganica, Castelnuovo, and Onna. Collapsed and damaged structures in L’Aquila included both older masonry buildings and relatively modern reinforced concrete structures. At the time of this writing, 307 people are known to have died from the earthquake, most in collapsed structures, making this the deadliest earthquake to strike Italy since the 1980 Irpinia earthquake. A number of reconnaissance teams were mobilized to the affected region in the weeks following the earthquake. The national institute of geophysics and volcanology (Istituto Nazionale di Geofisica e Vulcanologia, INGV) mobilized a team of geologists (EMERGEO Working Group) to look for evidence of surface rupture and other effects; some of their findings are discussed in this report. The GEER team was assembled to investigate geological, seismological, and geotechnical engineering aspects of the event. The international GEER team is comprised of members from Italy, Austria, Switzerland, Greece, and the United states. Team members were selected to provide needed expertise in geology, engineering geology, GIS applications, earthquake ground motions, and geotechnical earthquake engineering. The team includes individuals highly experienced in post-earthquake reconnaissance and relatively young professionals investigating their first earthquake. The GEER team did not focus on structural engineering or lifeline aspects of the event, which were investigated by an EERI team. The GEER and EERI activities were closely coordinated to optimize resources in the documentation of the valuable, perishable data associated with the earthquake effects. The GEER team employed a number of innovative technologies to facilitate effective reconnaissance. All teams mobilized for field work had a common GPS unit and laptop with a Google Earth (GE) GIS database activity maintained over the course of the work. The GE database was used to keep track of visited locations, but also contained maps of surface geology, locations of aftershocks, strong motion stations, and other information relevant to investigators in the field. Another valuable use of technology involved LIDAR mapping of a site having significant incidents of ground failure (Lake Sinizzo). This report presents the GEER findings. Following this introduction, Chapter 2 describes the geologic and tectonic setting, moment tensor solutions for the mainshock and several triggered events, analysis of aftershock patterns, and analysis of GPS and InSAR data. Included in Chapter 2 is a preliminary model of the ruptured fault. Chapter 3 describes the ground motions recorded during the mainshock by a digital instrument array. Metadata associated with the recordings is presented, trends in the recorded ground motions are presented, and preliminary comparisons to ground motion prediction equations are made. Chapter 4 presents damage patterns, both within L’Aquila and through comparisons of damage intensities in adjacent villages with similar construction. The results provide valuable insights into possible site effects on ground motion in regions where recordings are not available. Chapter 5 presents our findings on ground failure, defined as permanent ground deformations induced by the earthquake. Observed ground failure included several rockfalls, seismic compression of fill materials, and apparent strength loss of soil materials leading to inward movement of the banks of a lake. Chapter 6 reviews the performance of earth dams and earth retaining structures, both of which generally performed well