Improvement of Wind Power Assessment in Complex Terrain: The Case of COSMO-1 in the Swiss Alps

This work contains a series of calculations that explore the wind power potential in Switzerland using the Numerical Weather Prediction model COSMO-1. The model's performance was validated in complex terrain by comparing the modeled hourly wind speed to weather stations across Switzerland's mountains during a 2 year period. For wind-exposed stations, mean RMSE was found to be 2.87 m/s, mean MBE 0.03 m/s and mean correlation 0.51. For the wind-sheltered stations, model performance is slightly worse. We use the modeled wind speeds to calculate potential power production, and find capacity factors up to 0.42. With the modeled power time series, we show that in a hypothetical fully renewable Swiss power system, turbine siting can have a significant effect on imports, which may attain values from6 TWh/a to 13.3 TWh/a. Most importantly, the lowest import values are found for high wind power scenarios. When selecting locations with high capacity factors only (from random subsets of available locations), influence on import becomes small. An annual wind energy target of 6 TWh can be reached with as little as 1914 MW of turbine capacity, but this requires turbines to be built at relatively high elevations (mean turbine elevation 2967 above sea level). The lower the mean elevation of the wind turbines, the more capacity is required to reach the same production target. Furthermore, when restricting potential installations to locations deemed suited by the Swiss federal government (as laid out in the policy document “Konzept Windenergie Schweiz”), the capacity required to produce 6 TWh annually was found to be 2508 MW

Acute cholecystitis in high risk surgical patients: percutaneous cholecystostomy versus laparoscopic cholecystectomy (CHOCOLATE trial): Study protocol for a randomized controlled trial

<p>Abstract</p> <p>Background</p> <p>Laparoscopic cholecystectomy in acute calculous cholecystitis in high risk patients can lead to significant morbidity and mortality. Percutaneous cholecystostomy may be an alternative treatment option but the current literature does not provide the surgical community with evidence based advice.</p> <p>Methods/Design</p> <p>The CHOCOLATE trial is a randomised controlled, parallel-group, superiority multicenter trial. High risk patients, defined as APACHE-II score 7-14, with acute calculous cholecystitis will be randomised to laparoscopic cholecystectomy or percutaneous cholecystostomy. During a two year period 284 patients will be enrolled from 30 high volume teaching hospitals. The primary endpoint is a composite endpoint of major complications within three months following randomization and need for re-intervention and mortality during the follow-up period of one year. Secondary endpoints include all other complications, duration of hospital admission, difficulty of procedures and total costs.</p> <p>Discussion</p> <p>The CHOCOLATE trial is designed to provide the surgical community with an evidence based guideline in the treatment of acute calculous cholecystitis in high risk patients.</p> <p>Trial Registration</p> <p>Netherlands Trial Register (NTR): <a href="http://www.trialregister.nl/trialreg/admin/rctview.asp?TC=2666">NTR2666</a></p

Ultra-Early and Short-Term Tranexamic Acid Treatment in Patients With Good- and Poor-Grade Aneurysmal Subarachnoid Hemorrhage

The results of the ULTRA trial showed that ultra-early and short-term treatment with tranexamic acid (TXA) does not improve clinical outcome after aneurysmal subarachnoid hemorrhage (aSAH). Possibly, the lack of a beneficial effect in all patients with aSAH is masked by antagonistic effects of TXA in certain subgroups. In this post hoc subgroup analysis, we investigated the effect of TXA on clinical outcome in patients with good-grade and poor-grade aSAH

Rethinking energy, climate and security: a critical analysis of energy security in the US

Understanding the complicated relationship between energy, climate and security is vital both to the study of international relations and to ensure the continued survival of a world increasingly threatened by environmental change. Climate change is largely caused by burning fossil fuels for energy, but while discussions on the climate consider the role of energy, energy security debates largely overlook climate concerns. This article traces the separation between energy and climate through an analysis of US energy security discourse and policy. It shows that energy security is continually constructed as national security, which enables very particular policy choices and prioritises it above climate concerns. Thus, in many cases, policies undertaken in the name of energy security contribute directly to climate insecurity. The article argues that the failure to consider securing the climate as inherently linked to energy security is not just problematic, but, given global warming, potentially harmful. Consequently, any approach to dealing with climate change has to begin by rethinking energy security and security more broadly, as national (energy) security politics no longer provides security in any meaningful sense

Ultra-Early and Short-Term Tranexamic Acid Treatment in Patients With Good- and Poor-Grade Aneurysmal Subarachnoid Hemorrhage

BACKGROUND AND OBJECTIVES: The results of the ULTRA trial showed that ultra-early and short-term treatment with tranexamic acid (TXA) does not improve clinical outcome after aneurysmal subarachnoid hemorrhage (aSAH). Possibly, the lack of a beneficial effect in all patients with aSAH is masked by antagonistic effects of TXA in certain subgroups. In this post hoc subgroup analysis, we investigated the effect of TXA on clinical outcome in patients with good-grade and poor-grade aSAH. METHODS: The ULTRA trial was a multicenter, prospective, randomized, controlled, open-label trial with blinded outcome assessment. Participants received ultra-early and short-term TXA in addition to usual care or usual care only. This post hoc subgroup analysis included only ULTRA participants with confirmed aSAH and available World Federation of Neurosurgical Societies (WFNS) grade on admission. Patients were categorized into those with good-grade (WFNS 1-3) and poor-grade (WFNS 4-5) aSAH. The primary outcome was clinical outcome assessed by the modified Rankin scale (mRS). Odds ratios (ORs) and adjusted ORs (aORs) with 95% CIs were calculated using ordinal regression analyses. Analyses were performed using the as-treated principle. In all patients with aSAH, no significant effect modification of TXA on clinical outcome was observed for admission WFNS grade (p = 0.10). RESULTS: Of the 812 ULTRA participants, 473 patients had (58%; N = 232 TXA, N = 241 usual care) good-grade and 339 (42%; N = 162 TXA, N = 176 usual care) patients had poor-grade aSAH. In patients with good-grade aSAH, the TXA group had worse clinical outcomes (OR: 0.67, 95% CI 0.48-0.94, aOR 0.68, 95% CI 0.48-0.94) compared with the usual care group. In patients with poor-grade aSAH, clinical outcomes were comparable between treatment groups (OR: 1.04, 95% CI 0.70-1.55, aOR 1.05, 95% CI 0.70-1.56). DISCUSSION: This post hoc subgroup analysis provides another important argument against the use of TXA treatment in patients with aSAH, by showing worse clinical outcomes in patients with good-grade aSAH treated with TXA and no clinical benefit of TXA in patients with poor-grade aSAH, compared with patients treated with usual care. TRIAL REGISTRATION INFORMATION: ClinicalTrials.gov (NCT02684812; submission date February 18, 2016, first patient enrollment on July 24, 2013). CLASSIFICATION OF EVIDENCE: This study provides Class II evidence that tranexamic acid, given for <24 hours within the first 24 hours, does not improve the 6-month outcome in good-grade or poor initial-grade aneurysmal SAH

NUMERICAL WEATHER MODELS FOR RESOURCE ASSESSMENT OF ALPINE WIND POWER

Introduction With the decision to move away from nuclear-based power generation, Switzerland has committed itself to an ambitious energy transition. Wind power appears a suitable candidate to partially fill the gap left behind by nuclear. It has a favorable seasonal profile, which is highly compatible with Switzerland’s hydropower (Dujardin et al. 2017) and due to its low associated emissions, aligns well with climate targets. Much uncertainty surrounds the potential for wind power development in Switzerland however. Based on course resolution assessments, potential appears small. However on closer inspection, local terrain effects appear to lead to favorable wind conditions, especially in the alpine (Kruyt et al. 2017). Model based resource assessment Using output from the COSMO-1 model, we calculate how much capacity is required to produce an annual wind power target of 4, 6 or even 12 TWh. We find that allowing for turbines at high elevations reduces the capacity that is required to meet each target. Terrain induced flows Building on the results obtained with the COSMO model, simulations with the Weather Research and Forecasting (WRF) model are conducted (Figure 2). Here we aim to explore if the increased spatial and temporal resolution can help identify areas where terrain induced flows lead to favorable conditions for wind power development. Data from weather stations, as well as existing turbines in the Swiss Alps is used to validate the model performance

Reliable Averages and Risky Extremes – Analysis of spatiotemporal variability in solar irradiance and persistent cloud cover patterns over Switzerland

With the perspective of Switzerland’s phase-out from nuclear energy, solar energy potential may take an important role for the country’s future in renewable energy. Based on 12 years of satellite-derived, spatially distributed data of daily average cloud factor, this work analyses cloud cover persistence over all of Switzerland. We used extreme value analysis to study spatial variation of extremal behaviour and to estimate return levels of weeklong cloud cover events throughout Switzerland. Extreme events show different patterns in winter and summer, but overall they occur more frequently and more severely in the northern part of the country and in Ticino