Gap‐filling algorithm for ground surface temperature data measured in permafrost and periglacial environments

Ground surface temperatures (GST) are widely measured in mountain permafrost areas, but their time series data can be interrupted by gaps. Gaps complicate the calculation of aggregates and indices required for analysing temporal and spatial variability between loggers and sites. We present an algorithm to estimate daily mean GST and the resulting uncertainty. The algorithm is designed to automatically fill data gaps in a database of several tens to hundreds of time series, for example, the Swiss Permafrost Monitoring Network (PERMOS). Using numerous randomly generated artificial gaps, we validated the performance of the gap-filling routine in terms of (1) the bias resulting on annual means, (2) thawing and freezing degree-days, and (3) the accuracy of the uncertainty estimation. Although quantile mapping provided the most reliable gap-filling approach overall, linear interpolation between neighbouring values performed equally well for gap durations of up to 3–5 days. Finding the most similar regressors is crucial and also the main source of errors, particularly because of the large spatial and temporal variability of ground and snow properties in high-mountain terrains. Applying the gap-filling technique to the PERMOS GST data increased the total number of complete hydrological years available for analysis by 70 per cent (>450-filled gaps), likely without exceeding a maximal uncertainty of ± 0.25 °C in calculated annual mean value

GIS-based modelling of rock-ice avalanches from Alpine permafrost areas

Changing permafrost conditions caused by present atmospheric warming are expected to affect the stability of steep rock walls in high mountain areas. The possible increase in periglacial slope instabilities and the especially long potential run-out distances in glacial environments require more awareness about the kind of events as well as robust models to foresee areas affected and distances reached. A geographic information system-based flow-routing model is introduced for modelling rock-ice avalanches on a regional scale. The model application to three major historical events in the European Alps shows the basic use for simulating such events for first-order assessments. By designating the path of steepest descent while allowing lateral spreading from the fall track up to 45°, general flow patterns as well as changes in the direction of progression are well reproduced. The run-out distances are determined using empirically based models and suit well the case studies presente

Technische Begleitung von Online-Lehrveranstaltungen. Lessons learned und Praxistipps

Der vorliegende Text ist ein Bericht aus der Perspektive des technischen Betreuers der Online-Lehrveranstaltungen im Fachbereich Pädagogische Psychologie II (Kurt Reusser) des Pädagogischen Instituts der Universität Zürich. Er beschreibt Arbeitsschritte und Erfahrungen bei Planung, Aufbau und Betrieb einer webbasierten Lehr-/Lernplattform und fasst die dabei gewonnenen Erkenntnisse in Form von Praxistipps zusammen

The medial malleolar network: A constant vascular base of the distally based saphenous neurocutaneous island flap

Summary: Based on 30 fresh cadaver dissections a detailed anatomic study of the medial malleolar network is presented with particular attention to the anastomoses between the latter and the vascular axis that follows the saphenous nerve. The medial malleolar network is formed by the anterior medial malleolar artery, branches from the medial tarsal arteries, the posterior medial malleolar artery and branches from the medial plantar artery. A distinct anterior medial malleolar artery and posterior medial malleolar artery could be identified in 80 and 20%, respectively, as well as constant additional small branches arising from the anterior tibial or posterior tibial artery. A constant anastomosis was found between the arcade formed by the medial tarsal arteries and the medial plantar a. in 60%, and the medial branch of the medial plantar artery in 40%, respectively. This anastomosis always gave rise to branches to the medial malleolar network. In the perimalleolar area and with regard to the great saphenous v. a larger anterior and a smaller posterior branch of the saphenous nerve was found in 100 and 90%, respectively. In all dissections, for both branches of the saphenous nerve two to four small, but distinct anastomoses between the medial malleolar network and the perineural vascular axis were identified. These constant anastomoses represent a new and reliable vascular base for the distally-based saphenous neurocutaneous island flap. Thus, the pivotal point of the flap can be chosen in the area of the medial malleolus without respecting the most distal septocutaneous anastomosis between the perineural vascular axis and the posterior tibial artery. Additionally, an illustrative clinical case is presente

Attributing observed permafrost warming in the northern hemisphere to anthropogenic climate change

Permafrost temperatures are increasing globally with the potential of adverse environmental and socio-economic impacts. Nonetheless, the attribution of observed permafrost warming to anthropogenic climate change has relied mostly on qualitative evidence. Here, we compare long permafrost temperature records from 15 boreholes in the northern hemisphere to simulated ground temperatures from Earth system models contributing to CMIP6 using a climate change detection and attribution approach. We show that neither pre-industrial climate variability nor natural drivers of climate change suffice to explain the observed warming in permafrost temperature averaged over all boreholes. However, simulations are consistent with observations if the effects of human emissions on the global climate system are considered. Moreover, our analysis reveals that the effect of anthropogenic climate change on permafrost temperature is detectable at some of the boreholes. Thus, the presented evidence supports the conclusion that anthropogenic climate change is the key driver of northern hemisphere permafrost warming.Bundesministerium für Bildung und Forschunghttp://dx.doi.org/10.13039/501100002347Peer Reviewe

Partitioning Strategies for Distributed SMT Solving

For many users of Satisfiability Modulo Theories (SMT) solvers, the solver's performance is the main bottleneck in their application. One promising approach for improving performance is to leverage the increasing availability of parallel and cloud computing. However, despite many efforts, the best parallel approach to date consists of running a portfolio of solvers, meaning that performance is still limited by the best possible sequential performance. In this paper, we revisit divide-and-conquer approaches to parallel SMT, in which a challenging problem is partitioned into several subproblems. We introduce several new partitioning strategies and evaluate their performance, both alone as well as within portfolios, on a large set of difficult SMT benchmarks. We show that hybrid portfolios that include our new strategies can significantly outperform traditional portfolios for parallel SMT.Comment: Submitted to FMCAD 202

Attributing observed permafrost warming in the northern hemisphere to anthropogenic climate change

Permafrost temperatures are increasing globally with the potential of adverse environmental and socio-economic impacts. Nonetheless, the attribution of observed permafrost warming to anthropogenic climate change has relied mostly on qualitative evidence. Here, we compare long permafrost temperature records from 15 boreholes in the northern hemisphere to simulated ground temperatures from Earth system models contributing to CMIP6 using a climate change detection and attribution approach. We show that neither pre-industrial climate variability nor natural drivers of climate change suffice to explain the observed warming in permafrost temperature averaged over all boreholes. However, simulations are consistent with observations if the effects of human emissions on the global climate system are considered. Moreover, our analysis reveals that the effect of anthropogenic climate change on permafrost temperature is detectable at some of the boreholes. Thus, the presented evidence supports the conclusion that anthropogenic climate change is the key driver of northern hemisphere permafrost warming

Prolonged antibiotic prophylaxis use in elective orthopaedic surgery - a cross-sectional analysis.

PURPOSE Surgical antibiotic prophylaxis (SAP) prevents surgical site infections (SSI). In orthopaedic surgery, the use of prolonged SAP (PSAP) has been reported in daily routine, despite guidelines advising against it. Therefore, we asked: What is the proportion of PSAP use, defined as administration of SAP ≥24 h after elective orthopaedic surgery? Are there patient- and surgery-related predictors of PSAP use? METHODS This cross-sectional analysis investigated 1292 patients who underwent elective orthopaedic surgery including total joint arthroplasties at one Swiss centre between 2015 and 2017. Patient comorbidities, surgical characteristics and occurrence of SSI at 90 days in PSAP group were compared to the SAP group (< 24 h post-operative). RESULTS PSAP use was 12% (155 of 1292). Patient-related factors associated with PSAP compared to the SAP group included older age (63 vs. 58y; p < 0.001), higher BMI (29 vs. 27 kg/m2; p < 0.001), ASA classification ≥3 (31% vs. 17%; p < 0.001) and lung disease (17% vs. 9%; p = 0.002). Surgery-related factors associated with PSAP were use of prosthetics (62% vs. 45%; p < 0.001), surgery of the knee (65% vs. 25%; p < 0.001), longer surgery duration (87 vs. 68 min; p < 0.001) and presence of drains (90% vs. 65%; p < 0.001). All four SSI occurred in the SAP group (0 vs. 4; p = 1.0). Surgeons administered PSAP with varying frequencies; proportions ranged from 0 to 33%. CONCLUSION PSAP use and SSI proportions were lower than reported in the literature. Several patient- and surgery-related factors associated with PSAP use were identified and some were potentially modifiable. Also, experienced surgeons seemed to implement differing approaches regarding the duration of SAP administration

Sustaining permafrost observations: priorities and needs of the Global Terrestrial Network for Permafrost (GTN-P)

The Global Terrestrial Network for Permafrost (GTN-P) is the primary international programme concerned with sustained long-term monitoring of permafrost. GTN-P was developed in the 1990s by the International Permafrost Association (IPA) under the Global Terrestrial Observing System (GTOS) as part of the Global Climate Observing System (GCOS). The two major components of GTN-P (Essential Climate Variables) are: (a) long-term monitoring of the thermal state of permafrost in an extensive borehole network, the Thermal State of Permafrost - TSP; and (b) monitoring of the Active-layer thickness - ALT. Long-term monitoring of permafrost generates essential baseline information for the assessment of climate change impacts in polar and high mountain regions