Global climate change has resulted in a warmer Arctic, with projections indicating accelerated modifications to permafrost in the near future. The thermal, hydrological, and mechanical physics of permafrost thaw have been hypothesized to couple in a complex fashion but data collection efforts to study these feedbacks in the field have been limited. As a result, laboratory and numerical models have largely outpaced field calibration datasets. We present the design, execution, and initial results from the first decameter-scale controlled thawing experiment, targeting coupled thermal/mechanical response, particularly the temporal sequence of surface subsidence relative to permafrost degradation at depth. The warming test was conducted in Fairbanks, AK, and utilized an array of in-ground heaters to induce thaw of a ~11 × 13 × 1.5 m soil volume over 63 days. The 4-D temperature evolution demonstrated that the depth to permafrost lowered 1 m during the experiment. The resulting thaw-induced surface deformation was ~10 cm as observed using a combination of measurement techniques. Surface deformation occurred over a smaller spatial domain than the full thawed volume, suggesting that gradients in cryotexture and ice content were significant. Our experiment provides the first large field calibration dataset for multiphysics thaw models.

Ambient-noise-based seismic monitoring of the near surface often has limited spatiotemporal resolutions because dense seismic arrays are rarely sufficiently affordable for such applications. In recent years, however, distributed acoustic sensing (DAS) techniques have emerged to transform telecommunication fiber-optic cables into dense seismic arrays that are cost effective. With DAS enabling both high sensor counts ("large N") and long-term operations ("large T"), time-lapse imaging of shear-wave velocity (V _S ) structures is now possible by combining ambient noise interferometry and multichannel analysis of surface waves (MASW). Here we report the first end-to-end study of time-lapse V _S imaging that uses traffic noise continuously recorded on linear DAS arrays over a three-week period. Our results illustrate that for the top 20 meters the V _S models that is well constrained by the data, we obtain time-lapse repeatability of about 2% in the model domain-a threshold that is low enough for observing subtle near-surface changes such as water content variations and permafrost alteration. This study demonstrates the efficacy of near-surface seismic monitoring using DAS-recorded ambient noise.

OBJECTIVES: Female physicians in medicine are increasing, but disparities in female authorship exist. The aim of this study was to characterise factors associated with female first (FF) and female senior (SF) authorship in later phase systemic oncological clinical trials in biliary tract cancer (BTC) and identify any changes over time. SETTING: Embase/Medline identified trial publications in BTC (2000-2020) were included. χ2 tests and log regression were used (assessed factors associated with FF and SF authorship, including changes over time (STATA V.16)). PRIMARY OUTCOME MEASURE: FF and SF authorship in later phase systemic oncological clinical trials in BTC. SECONDARY OUTCOME MEASURE: Any changes over time? RESULTS: Of 501 publications, 163 met inclusion criteria. The median percentage of female author representation in publications was 25%; there were no female authors in 13% of publications. Geographic location of the home institution of the first and senior authors was Asia (42%/42%), Europe (29%/29%), USA (24%/22%) and other (4%/6%), respectively. Overall, FF and SF author representation was 20% and 10%, respectively. The median position of the first female author was second in all the publication author lists. The phase of trial, journal-impact factor, industry funding or whether the study met its primary endpoint did not impact FF/SF author representation. More SF authors had home institutions in other geographic locations (40% in 10 trials) (p=0.02) versus Asia (6%), Europe (8%) and USA (14%). There were no significant changes in FF/SF representation over time (p=0.61 and p=0.33 respectively). CONCLUSIONS: FF and SF author representation in later phase systemic clinical trial publications in BTC is low and has not changed significantly over time. The underlying reasons for this imbalance need to be better understood and addressed.