Evidence of Isotopic Fractionation During Vapor Exchange Between the Atmosphere and the Snow Surface in Greenland

Several recent studies from both Greenland and Antarctica have reported significant changes in the water isotopic composition of near-surface snow between precipitation events. These changes have been linked to isotopic exchange with atmospheric water vapor and sublimation-induced fractionation, but the processes are poorly constrained by observations. Understanding and quantifying these processes are crucial to both the interpretation of ice core climate proxies and the formulation of isotope-enabled general circulation models. Here, we present continuous measurements of the water isotopic composition in surface snow and atmospheric vapor together with near-surface atmospheric turbulence and snow-air latent and sensible heat fluxes, obtained at the East Greenland Ice-Core Project drilling site in summer 2016. For two 4-day-long time periods, significant diurnal variations in atmospheric water isotopologues are observed. A model is developed to explore the impact of this variability on the surface snow isotopic composition. Our model suggests that the snow isotopic composition in the upper subcentimeter of the snow exhibits a diurnal variation with amplitudes in δ18O and δD of ~2.5‰ and ~13‰, respectively. As comparison, such changes correspond to 10-20% of the magnitude of seasonal changes in interior Greenland snow pack isotopes and of the change across a glacial-interglacial transition. Importantly, our observation and model results suggest, that sublimation-induced fractionation needs to be included in simulations of exchanges between the vapor and the snow surface on diurnal timescales during summer cloud-free conditions in northeast Greenland.

Validation of subjective rating scales for assessment of surgical workspace during laparoscopy

BACKGROUND

Recently, studies have focused on how to optimize laparoscopic surgical workspace by changes in intra-abdominal pressure, level of muscle relaxation or body position, typically evaluated by surgeons using subjective rating scales. We aimed to validate two rating scales by having surgeons assess surgical workspace in video sequences recorded during laparoscopic surgery.

METHOD

Video sequences were obtained from laparoscopic procedures. Eight experienced surgeons assessed the video sequences on a categorical 5-point scale and a numerical 10-point rating scale. Intraclass correlations coefficients (ICC) and 95% confidence intervals (CI) were calculated for intra- and inter-rater reliability.

RESULTS

The 5-point rating scale had an intra-rater ICC of 0.76 (0.69; 0.83) and an inter-rater ICC of 0.57 (0.45; 0.68), corresponding to excellent and fair reliability, respectively. The 10-point scale had an intra-rater ICC of 0.86 (0.82; 0.89) and an inter-rater ICC of 0.54 (0.39; 0.68), corresponding to excellent and fair as well. All surgeons used the full range of the 5-point scale, but only one surgeon used the full range of the 10-point scale.

CONCLUSION

In conclusion, both scales showed excellent intra-rater and fair inter-rater reliability for assessing surgical workspace in laparoscopy. The 5-point surgical rating scale had all categories employed by all surgeons.

Is deep neuromuscular blockade beneficial in laparoscopic surgery? Yes, probably

BACKGROUND

Deep neuromuscular blockade during laparoscopic surgery may provide some clinical benefit. We present the 'Pro-' argument in this paired position paper.

METHODS

We reviewed recent evidence from a basic database of references which we agreed on with the 'Con-' side, and present this in narrative form. We have shared our analysis and text with the authors of the 'Con-' side of these paired position papers during the preparation of the manuscripts.

RESULTS

There are a few low risk of bias studies indicating that use of deep neuromuscular blockade improve surgical conditions and improve patient outcomes such as post-operative pain in laparoscopic surgery.

CONCLUSION

Our interpretation of recent findings is that there is reason to believe that there may be some patient benefit of deep neuromuscular blockade in this context, and more detailed study is needed.