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Subglacial seismicity presents the opportunity to monitor inaccessible glacial beds at the epicentral location and time. Glaciers can be underlain by rock or till, a first order control on bed mechanics. Velocity-weakening, necessary for unstable slip, has been shown for each bed type, but is much stronger and evolves over more than an order of magnitude longer distances for till beds. Utilizing a de-stiffened double direct shear apparatus, we found conditions for instability at freezing temperatures and high slip rates for both bed types. During stick–slip stress-drops, we recorded acoustic emissions with piezoelectric transducers frozen into the ice. The two populations of event waveforms appear visually similar and overlap in their statistical features. We implemented a suite of supervised machine learning algorithms to classify the bed type of recorded waveforms and spectra, with prediction accuracy between 65–80%. The Random Forest Classifier is interpretable, showing the importance of initial oscillation peaks and higher frequency energy. Till beds have generally higher friction and resulting stress-drops, with more impulsive first arrivals and more high frequency content compared to rock emissions, but rock beds can produce many till-like events. Seismic signatures could enhance interpretation of bed conditions and mechanics from subglacial seismicity.

Abstract Background and Objective The tyrosine kinase inhibitors cabozantinib and axitinib have been widely used in England to treat advanced renal cell carcinoma following prior vascular endothelial growth factor-targeted therapy, but data on real-world usage remain limited. Our objective was to describe the real-world treatment patterns and outcomes of patients with advanced renal cell carcinoma who received second-line or later-line (≥ 2L) cabozantinib or axitinib after vascular endothelial growth factor-targeted therapy in clinical practice in England. Methods This retrospective cohort study used clinical practice data (collected 2011–20) from the English Cancer Analysis System database. Patient characteristics, treatment sequence and duration, and overall survival (time from initiation of cabozantinib/axitinib treatment to death) were evaluated. Results Data from 1485 eligible adults with advanced renal cell carcinoma were analyzed: 440 received ≥ 2L cabozantinib (2L for 88.6% of them); 1045 received ≥ 2L axitinib (2L for 89.5%). The most common first-line treatments were sunitinib (2L cabozantinib subcohort, 48%; 2L axitinib subcohort, 46%) and pazopanib (46% and 54%, respectively); nivolumab was the most common third-line treatment (18% and 19%, respectively). Median (interquartile range) 2L therapy duration was 5.52 (2.73–11.74) months for cabozantinib and 4.60 (1.45–12.36) months for axitinib. Following adjustment for potential confounders using inverse probability weighting, overall survival (median [interquartile range]) was longer for ≥ 2L cabozantinib (11.2 [5.7–28.0] months) than for ≥ 2L axitinib (10.4 [4.7–22.0] months; log-rank p = 0.0034). Conclusions The Cancer Analysis System database is a valuable research resource providing extensive real-world clinical data. Real-world overall survival was longer with ≥ 2L cabozantinib than with axitinib. Clinical Trial Registration ClinicalTrials.gov, NCT04637204; registered November 2020.

Basal slip along glaciers and ice streams can be significantly modified by external time-dependent forcing, although it is not clear why some systems are more sensitive to tidal stresses. We have conducted a series of laboratory experiments to explore the effect of time varying load point velocity on ice-on-rock friction. Varying the load point velocity induces shear stress forcing, making this an analogous simulation of aspects of ice stream tidal modulation. Ambient pressure, double-direct shear experiments were conducted in a cryogenic servo-controlled biaxial deformation apparatus at temperatures between −2°C and −16°C. In addition to a background, median velocity (1 and 10 μm/s), a sinusoidal velocity was applied to the central sliding sample over a range of periods and amplitudes. Normal stress was held constant over each run (0.1, 0.5 or 1 MPa) and the shear stress was measured. Over the range of parameters studied, the full spectrum of slip behavior from creeping to slow-slip to stick-slip was observed, similar to the diversity of sliding styles observed in Antarctic and Greenland ice streams. Under conditions in which the amplitude of oscillation is equal to the median velocity, significant healing occurs as velocity approaches zero, causing a high-amplitude change in friction. The amplitude of the event increases with increasing period (i.e. hold time). At high normal stress, velocity oscillations force an otherwise stable system to behave unstably, with consistently-timed events during every cycle. Rate-state friction parameters determined from velocity steps show that the ice-rock interface is velocity strengthening. A companion paper describes a method of analyzing the oscillatory data directly. Forward modeling of a sinusoidally-driven slider block, using rate-and-state dependent friction formulation and experimentally derived parameters, successfully predicts the experimental output in all but a few cases.

Abstract Rate and state frictional parameters are typically determined using two types of experimental protocols: velocity steps and slide‐hold‐slide events. Here we take a new approach by examining the frictional response to controlled, harmonic oscillations in load point velocity. We present a Matlab graphical user interface software package, called RSFitOSC, that allows users to easily determine frictional parameters by fitting oscillation events using the rate and state friction equations. We apply our new methods to a set of ice‐rock friction experiments conducted over a temperature range of −16.4°C to −2°C, and described in a companion paper: McCarthy et al. (2021, https://doi.org/10.1002/essoar.10509831.110.1002/essoar.10509831.1). Values of the frictional stability parameter (a–b) determined from oscillations reveal dominantly velocity‐weakening behavior across the entire range of experimental conditions. However, values of (a–b) determined from velocity steps in the same experiments yield velocity‐strengthening behavior. We also show that the elastic stiffness of the ice‐rock system depends on the temperature, and is unlikely to be explained by changes in the elastic properties of ice. Load point velocity oscillations induce oscillations in applied shear stress. Many natural fault systems exhibit slip behaviors that depend on harmonic oscillations in applied tidal stresses. Our new method provides a way to study how frictional properties directly depend on parameters relevant to tidal forcing, and how oscillatory loading must be considered when extracting friction parameters.

As an initial step toward in situ exploration of the interiors of Ocean Worlds to search for life using cryobot architectures, we test how various communication tethers behave under potential Europa-like stress conditions. By freezing two types of pretensioned insulated fiber optic cables inside ice blocks, we simulate tethers being refrozen in a probe’s wake as it traverses through an Ocean World’s ice shell. Using a cryogenic biaxial apparatus, we simulate shear motion on preexisting faults at various velocities and temperatures. These shear tests are used to evaluate the mechanical behavior of ice, characterize the behavior of communication tethers, and explore their limitations for deployment by a melt probe. We determine (a) the maximum shear stress tethers can sustain from an ice fault, prior to failure (viable/unviable regimes for deployment), and (b) optical tether performance for communications. We find that these tethers are fairly robust across a range of temperature and velocity conditions expected on Europa ( T = 95–260 K, velocity = 5 × 10 ^−7 m s ^−1 to 3 × 10 ^−4 m s ^−1 ). However, damage to the outer jackets of the tethers and stretching of inner fibers at the coldest temperatures tested both indicate a need for further tether prototype development. Overall, these studies constrain the behavior of optical tethers for use at Ocean Worlds, improve the ability to probe thermomechanical properties of dynamic ice shells likely to be encountered by landed missions, and guide future technology development for accessing the interiors of (potentially habitable ± inhabited) Ocean Worlds.

The evolution of glaciers and ice sheets depends on processes in the subglacial environment. Shear seismicity along the ice–bed interface provides a window into these processes. Such seismicity requires a rapid loss of strength that is typically ascribed to rate-weakening friction, i.e., decreasing friction with sliding or sliding rate. Many friction experiments have investigated glacial materials at the temperate conditions typical of fast flowing glacier beds. To our knowledge, however, these studies have all found rate-strengthening friction. Here, we investigate the possibility that rate-weakening rock-on-rock friction between sediments frozen to the bottom of the glacier and the underlying water-saturated sediments or bedrock may be responsible for subglacial shear seismicity along temperate glacier beds. We test this ‘entrainment-seismicity hypothesis’ using targeted laboratory experiments and simple models of glacier sliding, seismicity and sediment entrainment. These models suggest that sediment entrainment may be a necessary but not sufficient condition for the occurrence of basal shear seismicity. We propose that stagnation at the Whillans Ice Stream, West Antarctica may be caused by the growth of a frozen fringe of entrained sediment in the ice stream margins. Our results suggest that basal shear seismicity may indicate geomorphic activity.

We measured the ultrasonic properties and microstructure of two-phase binary mixtures of the ice−ammonia partial melt system, which was selected based on its importance for numerous planetary bodies. The equilibrium microstructure of ice−ammonia melt was examined using a light microscope within a cold room. The measured median dihedral angle between the solid and melt at 256 K is approximately 63°, with a broad distribution of observed angles between 10° and 130°. P-wave velocities in the partially molten samples were measured as a function of temperature (177 < T(K) < 268) and composition (1−6.4 wt % NH3). Vp decreases approximately linearly with increasing temperature and melt fraction. We compare the results of this study to those of other potential binary systems by normalizing the datasets using a vertical lever (TL−TE) and articulating the potential effects on the mechanical behavior and transport capabilities of partially molten ice in icy satellites.

To commence the thirtieth annual conference of the Society of Architectural Historians, Australia and New Zealand (SAHANZ), held on Australia’s Gold Coast in July 2013, ten delegates were invited with very little warning to take five minutes and one image to offer a provocation on the open matters of architectural history in the present moment. The term “open” was taken as the conference theme—a device used by SAHANZ meetings not so much to define the scope of papers presented as to declare the conference flavour year by year. It was not, therefore, an open conference (anything goes) so much as a conference on open issues (where, indeed, to go). The ten interlocutors were invited after the conference to document their interventions and they are presented here as a record of the preoccupations of a specific moment and institutional geography with all the idiosyncrasies and commonalities it might reveal to a broader audience.

The article discusses the importance of digital collection marketing. It introduces the inlink analysis method which identifies and understands digital collections' current and potential audiences and presents case evidence signifying the significant impact of marketing efforts on the number of users of digital collections at Harvard University's Open Collections Program. The information that academic libraries ought to market is also explored.