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Incidence of stent thrombosis (ST) in comatose survivors of out-of-hospital cardiac arrest (OHCA) undergoing immediate percutaneous coronary intervention (PCI) and therapeutic hypothermia (TH) varies considerably, from 2.7% to 31.2%, in retrospective studies.We aimed to investigate occurrence, timing and predictors of definite ST.We prospectively investigated consecutive comatose survivors of OHCA with presumed cardiac aetiology undergoing immediate PCI with drug-eluting stents (DES) and TH targeted at 32-34°C admitted between August 2016 and July 2021. Repeat coronary angiography (CAG) was performed if ST was suspected and systematically between day 8-12 in the absence of clinical signs. All deceased patients underwent autopsy and histopathological analysis. Results: Among 362 comatose survivors of OHCA, immediate PCI with stenting was performed in 169 patients (47%). Since 18 patients did not complete follow-up, 151 patients were ultimately enrolled in ST analysis. Definite ST was confirmed in 29 patients (19.2%; 95% confidence interval [CI]: 12.9%-25.6%) either by CAG (n=18) or autopsy (n=11). ST occurred within 3 days in 62% and presented with at least one clinical sign in 79%. Survival with good neurological recovery was observed in 17% of patients with ST and in 60% of patients without ST (p0.001). Independent predictors of ST were longer prehospital resuscitation, lower arterial pH and increased creatinine on admission.The incidence of definite ST in comatose survivors of OHCA undergoing immediate PCI and TH targeted at 32-34°C is substantial (19.2%) and significantly higher than in other PCI subsets despite systematic use of contemporary DES and anticoagulation/antiplatelet treatment.

Our current understanding of Arctic carbonaceous aerosol (CA) is rudimentary and there is a lack of long-term observations for many components, such as organic aerosol (OA), exceptions to this include equivalent black carbon (eBC) and methane sulfonic acid (MSA). To address this, we analyzed long-term measurements of organic carbon (OC), elemental carbon (EC), and source-specific organic tracers from 2017 to 2020 to constrain CA sources in the rapidly changing Arctic. We also used absorption photometer (aethalometer) measurements to constrain equivalent BC from biomass burning (eBCBB) and fossil fuel combustion (eBCFF) using Positive Matrix Factorization (PMF). Our analysis showed that organic tracers are essential to understand Arctic CA sources. For 2017 to 2020, levoglucosan had a bimodal seasonality, with a signal from residential wood combustion (RWC) in the heating season (H-season; November to May) and from wildfires (WF) in the non-heating season (NH-season; June to October), demonstrating a pronounced inter-annual variability in the WF influence. Biogenic secondary organic aerosol (BSOA) species (2-methyltetrols) from isoprene oxidation appeared only in the NH-season, peaking in July to August. Intrusions of warm air masses from Siberia in summer caused three- and ninefold increases in 2-methyltetrols compared to 2017 to 2018, in 2019 and 2020, respectively, warranting investigation of the local vs. the long-range atmospheric transport (LRT) contribution, as certain Arctic vegetation has highly temperature sensitive biogenic volatile organic compounds (BVOC) emission rates. Primary biological aerosol particles (PBAP) tracers (various sugars and sugar-alcohols) were elevated in the NH-season but evolved differently, whereas cellulose was completely decoupled from the other PBAP tracers. Peak levels of most PBAP tracers and of 2-methyltetrols were associated with WF emissions, demonstrating the importance of measuring a broad spectrum of source specific tracers to understand sources and dynamics of CA. Finally, CA seasonality is heavily influenced by long-range atmospheric transport (LRT) episodes, since background levels are extremely low. E.g., we find the OA peak in the NH-season is as strongly influenced by LRT as is EC during Arctic Haze (AH). Source apportionment of CA by Latin Hypercube Sampling (LHS) showed a mixed contribution from RWC (46 %), fossil fuel (FF) sources (27 %), and BSOA (25 %) in the H-season, whereas BSOA (56 %) prevailed over WF (26 %) and FF (15 %) in the NH-season. Source apportionment of eBC by PMF showed that FF combustion dominated eBC (70 ± 2.7 %), whereas RWC (22 ± 2.7 %) was more abundant than WF (8.0 ± 2.9 %). Modeled BC concentrations from FLEXPART attributed an almost equal share to FF (51 ± 3.1 %) and BB. Both FLEXPART and the PMF analysis concluded that RWC is a more important source than WF. However, with a modeled RWC of 30 ± 4.1 % and WF of 19 ± 2.8 %, FLEXPART suggests relatively higher contributions to eBC from these sources. We find that OA (281 ± 106 ng m−3) is a significant fraction of the Arctic PM10 aerosol particle mass, though less than sea salt aerosol (SSA) (682 ± 46.9 ng m−3) and mineral dust (MD) (613 ± 368 ng m−3) as well as typically non-sea-salt sulfate (nssSO42−) (314 ± 62.6 ng m−3), originating mainly from anthropogenic sources in winter and from natural sources in summer. FF combustion was the prevailing source of eBC, whereas RWC made a larger contribution to eBCBB than WF.

Radiocarbon (14C) analysis of carbonaceous aerosols is used for source apportionment, separating the carbon content into fossil vs. non-fossil origin, and is particularly useful when applied to subfractions of total carbon (TC), i.e. elemental carbon (EC), organic carbon (OC), water-soluble OC (WSOC), and water-insoluble OC (WINSOC). However, this requires an unbiased physical separation of these fractions, which is difficult to achieve. Separation of EC from OC using thermal–optical analysis (TOA) can cause EC loss during the OC removal step and form artificial EC from pyrolysis of OC (i.e. so-called charring), both distorting the 14C analysis of EC. Previous work has shown that water extraction reduces charring. Here, we apply a new combination of a WSOC extraction and 14C analysis method with an optimised OC/EC separation that is coupled with a novel approach of thermal-desorption modelling for compensation of EC losses. As water-soluble components promote the formation of pyrolytic carbon, water extraction was used to minimise the charring artefact of EC and the eluate subjected to chemical wet oxidation to CO2 before direct 14C analysis in a gas-accepting accelerator mass spectrometer (AMS). This approach was applied to 13 aerosol filter samples collected at the Arctic Zeppelin Observatory (Svalbard) in 2017 and 2018, covering all seasons, which bear challenges for a simplified 14C source apportionment due to their low loading and the large portion of pyrolysable species. Our approach provided a mean EC yield of 0.87±0.07 and reduced the charring to 6.5 % of the recovered EC amounts. The mean fraction modern (F14C) over all seasons was 0.85±0.17 for TC; 0.61±0.17 and 0.66±0.16 for EC before and after correction with the thermal-desorption model, respectively; and 0.81±0.20 for WSOC.

Radiocarbon (14C) analysis of carbonaceous aerosols is used for source apportionment, separating the carbon content into fossil vs. non-fossil origin, and is particularly useful when applied to subfractions of total carbon (TC), i.e. elemental carbon (EC), organic carbon (OC), water-soluble OC (WSOC), and water-insoluble OC (WINSOC). However, this requires an unbiased physical separation of these fractions, which is difficult to achieve. Separation of EC from OC using thermal–optical analysis (TOA) can cause EC loss during the OC removal step and form artificial EC from pyrolysis of OC (i.e. so-called charring), both distorting the 14C analysis of EC. Previous work has shown that water extraction reduces charring. Here, we apply a new combination of a WSOC extraction and 14C analysis method with an optimised OC/EC separation that is coupled with a novel approach of thermal-desorption modelling for compensation of EC losses. As water-soluble components promote the formation of pyrolytic carbon, water extraction was used to minimise the charring artefact of EC and the eluate subjected to chemical wet oxidation to CO2 before direct 14C analysis in a gas-accepting accelerator mass spectrometer (AMS). This approach was applied to 13 aerosol filter samples collected at the Arctic Zeppelin Observatory (Svalbard) in 2017 and 2018, covering all seasons, which bear challenges for a simplified 14C source apportionment due to their low loading and the large portion of pyrolysable species. Our approach provided a mean EC yield of 0.87±0.07 and reduced the charring to 6.5 % of the recovered EC amounts. The mean fraction modern (F14C) over all seasons was 0.85±0.17 for TC; 0.61±0.17 and 0.66±0.16 for EC before and after correction with the thermal-desorption model, respectively; and 0.81±0.20 for WSOC.

The response of terrestrial ecosystems to anthropogenic climate change remains poorly understood and constitutes a major source of uncertainty in future climate projections. Stalagmites are a well-established terrestrial climate archive (Wong and Breecker, 2015), and may also serve as a sensitive recorder of surface ecosystem processes, as they are fed by dripping water that percolates through the soil zone. Coupled climate-ecosystem paleorecords from stalagmites could prove invaluable sources of information on the response of terrestrial ecosystems to past climatic shifts and their sensitivity to climate variability exceeding the instrumental range.Here we present results from a method development study carried out at the Laboratory for the Analysis of Radiocarbon with AMS (LARA) at the University of Bern. Our results are based on a previous protocol by Lechleitner et al. (2019), which describes a rapid, low contamination method for carbon isotope analysis (δ13C and 14C) of the speleothem non-purgeable organic carbon (NPOC) fraction for small samples (3). Decarbonation of acid digested carbonate samples is followed by wet chemical oxidation of the NPOC and analysis of the resulting headspace CO2 via mass spectrometry to determine its isotopic composition.We have made significant progress in resolving the main issues that precluded the routine application of the method as presented in Lechleitner et al. (2019), namely incomplete removal of inorganic carbon from the sample solutions, and contamination from extraneous carbon at different method stages. Apart from an updated pre-cleaning protocol for stalagmite samples and extensive blank assessment, a new needle setup was installed, allowing reduction of the sample amount needed, and the CO2 flow is now being monitored during decarbonation to ensure complete removal of inorganic carbon prior to the oxidation step.These results reiterate the great promise of this method to provide accurate, ecosystem-level information on past terrestrial environments at comparatively high temporal resolution. References:Lechleitner, F.A., Lang, S.Q., Haghipour, N., McIntyre, C., Baldini, J.U.L., Prufer, K.M., Eglinton, T.I., 2019. Towards organic carbon isotope records from stalagmites: coupled d13C and 14C analysis using wet chemical oxidation. Radiocarbon 61, 749–764. doi:10.1017/RDC.2019.35Wong, C.I., Breecker, D.O., 2015. Advancements in the use of speleothems as climate archives. Quat. Sci. Rev. 127, 1–18. doi:10.1016/j.quascirev.2015.07.019

Background Conventional fluoroscopy guided catheter ablation (CA) is an established treatment option for ventricular arrhythmias (VAs). However, with the complex nature of most procedures, patients and staff bare an increased radiation exposure. Near-zero or zero-fluoroscopy CA is an alternative method which could substantially reduce or even eliminate the radiation dose. Our aim was to analyse procedural outcomes with fluoroscopy minimising approach for treatment of VAs in patients with structurally normal hearts (SNH) and structural heart disease (SHD). Methods Fifty-two (age 53.4 ± 17.8 years, 38 male, 14 female) consecutive patients who underwent CA of VAs in our institution between May 2018 and December 2019 were included. Procedures were performed primarily with the aid of the three-dimensional electro-anatomical mapping system and intra-cardiac echocardiography. Fluoroscopy was considered only in left ventricular (LV) summit mapping for coronary angiography and when epicardial approach was planned. Acute and long-term procedural outcomes were analysed. Results Sixty CA procedures were performed. Twenty-five patients had SHD-related VAs (Group 1) and 27 patients had SNH (Group 2). While Group 1 had significantly higher total procedural time (256.9 ± 71.7 vs 123.6 ± 42.2 min; p p = 0.20)] and recurrence rate after the first procedure [8/25, (32%) vs 8/27, (29.6%); p = 0.85] were similar in both groups. Fluoroscopy was used in 3 procedures in Group 1 where epicardial approach was needed and in 4 procedures in Group 2 where LV summit VAs were ablated. Overall procedure-related major complication rate was 5%. Conclusions Fluoroscopy minimising approach for CA of VAs is feasible and safe in patients with SHD and SNH. Fluoroscopy could not be completely abolished in VAs with epicardial and LV summit substrate location.

Only up to 20% of patients with out-of-hospital cardiac arrest (OHCA) receive immediate and optimal initial cardiac resuscitation and consequently regain consciousness soon after return of spontaneous circulation (ROSC). In the present study, we compared the outcome of conscious survivors of OHCA presenting with ST-elevation myocardial infarction (STEMI) in post-resuscitation electrocardiogram undergoing immediate invasive coronary strategy with randomly selected STEMI patients without preceding OHCA undergoing primary PCI.We conducted a single-centre registry-based analysis of all conscious OHCA survivors with STEMI over the last 10 year period. We gathered clinical and angiographic data and compared them with a randomly selected cohort of non-OHCA patients with STEMI within the same period. Patients were matched by sex, age and STEMI location.86 conscious survivors of OHCA were admitted between 2006 and 2016. OHCA was witnessed in all patients (85% EMS witnessed), and all patients presented with initial shockable rhythm. Clinical and angiographic features were well matched with randomly selected STEMI patients without OHCA presenting to our department within the same study period. Delay from symptoms to EMS arrival but not delay from EMS to PCI was significantly shorter in conscious OHCA survivors (1.2 ± 1.3 h vs 3.1 ± 3.8 h, p 0.001), yielding decreased total myocardial ischemic time (2.6 ± 1.3 h vs 4.6 ± 4.0 h, p 0.001). Hospital and 1-year survival with normal neurological condition in conscious survivors of OHCA (cerebral performance category 1) was excellent and numerically even better than survival of STEMI patients without OHCA.Conscious survivors of OHCA with STEMI have excellent survival if they undergo immediate invasive coronary strategy. Since there is no obvious post-resuscitation brain injury in this subgroup of OHCA patients, it is probably shorter duration of myocardial ischemia driven by shorter delay from symptoms to EMS arrival that contributes to the good outcome, which is at least similar to STEMI patients without OHCA.

BackgroundConventional fluoroscopy (CF) guided catheter ablation (CA) is an established treatment option for ventricular arrhythmias (VAs). However, with the complex nature of most procedures, patients and staff bare an increased radiation exposure. Near-zero or zero-fluoroscopy CA is an alternative method which could substantially reduce or even eliminate the radiation dose. Our aim was to analyse procedural outcomes with fluoroscopy minimising approach for treatment of VAs in patients with structurally normal hearts (SNH) and structural heart disease (SHD).MethodsFifty-two (age 53.4±17.8 years, 38 male, 14 female) consecutive patients who underwent CA of VAs in our institution between May 2018 and December 2019 were included. Procedures were performed primarily with the aid of the three-dimensional (3D) electro-anatomical mapping (EAM) system and intra-cardiac echocardiography (ICE). Fluoroscopy was considered only in left ventricular (LV) summit mapping for coronary angiography and when epicardial approach was planned. Acute and long-term procedural outcomes were analysed.ResultsSixty CA procedures were performed. Twenty-five patients had SHD-related VAs (Group 1) and 27 patients had SNH (Group 2). While Group 1 had significantly higher total procedural time (256.9±71.7 vs 123.6±42.2 minutes; p < 0.001) compared to Group 2, overall procedural success rate [77.4% (24/31) vs 89.7% (26/29); p= 0.20)] and recurrence rate after the first procedure [8/25, (32%) vs 8/27, (29.6%); p= 0.85] were similar in both groups. Fluoroscopy was used in 3 procedures in Group 1 where epicardial approach was needed and in 4 procedures in Group 2 where LV summit VAs were ablated. Overall procedure-related major complications were low (3/60, 5%).ConclusionsFluoroscopy minimising approach for CA of VAs is feasible and safe in patients with SHD and SNH. Fluoroscopy could not be completely abolished in VAs with epicardial and LV summit substrate location.

In this study, the temporal variations of sources of black carbon (BC) concentrations were evaluated in the metropolitan area of Milan, Italy, during three distinct seasons over 2017–2018. We measured BC concentrations using Aethalometers at two sampling sites, one in the city center of Milan, and one in the less densely populated suburb of Bareggio, approximately 14 km to the west of Milan's urban center. PM samples were also collected for elemental carbon (EC) and 14C analyses. The Aethalometer model was used to apportion BC concentrations to the fossil fuel combustion (BCff) and biomass burning (BCbb) originated BC. Additionally, radiocarbon 14C analysis was performed on the PM samples, allowing us to refine our estimates of the contributions of both BCff and BCbb to total BC concentrations and assess the dependence of the mass absorption cross section (MAC) of BC on its source. Overall, our results indicated that the annually averaged BC concentrations were higher at the Bareggio site (2763 ± 1050 ng m−3) than at the Milan site (1921 ± 876 ng m−3). The Aethalometer model results demonstrated that in all of the sampling seasons, fossil-fuel-originated BC (BCff) concentrations were slightly higher in Milan (e.g., a summertime average of 1045 ± 150 ng/m3) than in Bareggio (e.g., a summertime average of 940 ± 89 ng/m3); however, black carbon (BCbb) concentrations from biomass burning were considerably higher at Bareggio (e.g., a wintertime average of 3284 ± 713 ng/m3) than in Milan (e.g., a wintertime average of 1154 ± 103 ng/m3). Diurnal variation plots indicated that both in Milan and Bareggio, BCff peaked during the morning and, to a lesser extent, afternoon traffic rush hours, while BCbb peaked during nighttime when residential wood burning for heating purposes is prominent. Our results also highlight the significant impact of residential wood burning on ambient BC concentrations in the Milan metropolitan area.

Background: Immediate percutaneous coronary intervention (PCI) is increasingly performed in comatose survivors of out-of-hospital cardiac arrest (OHCA) undergoing therapeutic hypothermia (TH). Since reported incidence of stent thrombosis (ST) varies significantly from 2.5% to 31%, we investigated definite ST using systematic coronary angiography (CAG) and autopsy. Methods: Consecutive comatose survivors of OHCA undergoing immediate PCI and TH admitted between August 2016 and May 2018 were investigated. CAG was performed if ST was suspected and systematically between day 10-14. Patients who died underwent autopsy with analysis of stented segments. Results: Among 147 consecutive patients, immediate CAG was performed 103 (70%) and 52 (50%) underwent PCI. Since 5 patients refused to participate or had no follow-up, 47 patients were included. Definite ST, which was confirmed 8 patients (17%), was diagnosed either by clinically-driven CAG (n = 6), routine CAG (n = 1) or autopsy (n = 1). Patients with ST had more often diabetes (38% vs. 5%; p = 0.008), longer interval of prehospital resuscitation (12.6 ± 10.7 minutes vs. 25.0 ± 10.6 minutes; p = 0.005), higher admission lactate (6.8 ± 6.3 mmol/L vs. 3.2 ± 2.9 mmol/L; p = 0.013), lower arterial pH (7.13 + 0.19 vs. 7.27 ± 0.11; p = 0.005) and less favorable survival with good neurological outcome - Cerebral Performance Category score 1 - 2 (13% vs. 62%; p = 0.03). There was no difference in left ventricular ejection fraction (40 ± 12% vs. 39 ± 13%; p = 0.85), periprocedural dose of unfractioned heparin (8944 ± 2504 IU/kg vs. 8188 ± 2764 IU/kg; p = 0.45), use of GP llb/llla (16 % vs. 25 %; p = 0.59) and of novel P2Y12 inhibitor ticagrelor (79% vs. 63%; p = 0.33). There was no significant difference in total length of stented segment (32.7 ± 24.4 mm vs. 36.6 ± 20.7 mm; p = 0.68) nor in average stent diameter (3.1 ± 0.5 mm vs. 3.2 ± 0.4 mm; p = 0.62). Conclusions: Incidence of definite ST in comatose survivors of OHCA undergoing immediate PCI and TH is significant (17%) and is associated with worse outcome. Prolonged prehospital resuscitation and diabetes rather than PCI characteristics represent the risk factors for development of ST.

In the northwestern area of Basel, Switzerland, a tunnel highway connects the French highway A35 (Mulhouse–Basel) with the Swiss A2 (Basel–Gotthard–Milano). The subsurface highway construction was associated with significant impacts on the urban groundwater system. Parts of this area were formerly contaminated by industrial wastes, and groundwater resources are extensively used by industry. During some construction phases, considerable groundwater drawdown was necessary, leading to major changes in the groundwater flow regime. Sufficient groundwater supply for industrial users and possible groundwater pollution due to interactions with contaminated areas had to be taken into account. A groundwater management system is presented, comprising extensive groundwater monitoring, high-resolution numerical groundwater modeling, and the development and evaluation of different scenarios. This integrated approach facilitated the evaluation of the sum of impacts, and their interaction in time and space with changing hydrological boundary conditions. For all project phases, changes of the groundwater system had to be evaluated in terms of the various goals and requirements. Although the results of this study are case-specific, the overall conceptual approach and methodologies applied may be directly transferred to other urban areas.

Out of hospital cardiac arrest (OHCA) has a high mortality despite modern treatment. Reliable early prognosis in OHCA could significantly improve clinical decision making. We explored prognostic utility of advanced ECG parameters, obtained from high-resolution ECG, in combination with clinical and OHCA-related parameters during treatment with mild induced hypothermia (MIH) and after rewarming in unconscious survivors of OHCA. Ninety-two patients during MIH and 66 after rewarming were included. During MIH, a score based on initial rhythm, QRS-upslope and systolic pressure resulted in an area under curve (AUC) of 0.82 and accuracy of 80% for survival. After rewarming, a score based on admission rhythm, sum of 12 lead QRS voltages, and mean lateral ST segment level in leads I and V6 resulted in an AUC of 0.88 and accuracy of 85% for survival. ECG can assist with early prognostication in unconscious survivors of OHCA during MIH and after rewarming.

Aim: We synthesized ultra-small iron oxide nanoparticles (USPIONs) with tripod morphology and studied the effect of the aspect ratio (AR) of the tripod arms on mass magnetization, T2 relaxation and cytocompatibility in human cell lines. Materials & methods: Tripods were prepared by controlling the temperature during the thermal decomposition of Fe(CO)5, and their magnetic properties were characterized by superconducting quantum interference device, and NMR. Citric acid stabilized USPIONs were used to assess cytocompatibility. Results: T2 relaxivity of tripods showed dependency on AR of the tripod arm. Liver enzyme levels in presence of tripods were comparable to spherical USPIONs, and surprisingly tripods induced lower levels of reactive oxygen species. Conclusion: Tripod USPIONs with high AR arms possess excellent magnetic properties and cytocompatibility for further exploration as MRI contrast agents.

Brief description of the article: This article considers heart rate variability as a measurable parameter of stress reaction and present recent studies that examined the impact of occupational stress on heart rate variability and thus autonomic nervous system.ABSTRACT Stress is a complex psychoneuroendocrinological and immune response of an individual to stressogenic factor. The most important contemporary stressogenic factors are mental, psycho-social and socio-economic stressors. This especially holds true for occupational stress. Many symptoms and signs of disease are associated with chronic occupational stress. Among those are cardiovascular diseases, metabolic and psychiatric disorders.This article describes different stressogenic factors that lead to occupational stress and two conceptual models of occupational stress (Karasek’s Demand/Control Model and Siegrist’s Effort-Reward Imbalance Model). Reaction to stress can be measured in various ways. This article summarizes the physiology of heart beat regulation and presents heart rate variability as a measurable parameter of stress reaction. Heart rate variability gives us an insight into autonomic modulation of the heart and functioning of the entire autonomic nervous system. This article presents the latest results of larger studies that examined the impact of occupational stress on heart rate variability and various mechanisms that lead to end-organ damage due to changes in autonomic nervous system as a result of work stress. Subjects exposed to chronic stress have significantly lower heart rate variability compared with subjects unaffected by stress. Researches have shown that reduced heart rate variability reliably predicts mortality among health adults, as well as morbidity and mortality in patients after acute myocardial infarction, in patients with chronic heart failure and mortality in patients with chronic kidney disease.

This paper describes two groundwater models simulating a well capture zone in a heterogeneous aquifer located near an infiltrating river. A deterministic, large-scaled groundwater model (1.8 × 1.2 km) is used to simulate the average behavior of groundwater flow and advective transport. It is also used to assign the boundary conditions for a small-scaled groundwater model (550 × 400 m) which relies on stochastically generated aquifer properties based on site-specific drill core and georadar data. The small-scaled groundwater model is used to include the large subsurface heterogeneity at the location of interest. The stochastic approach in the small-scaled groundwater model does not lead to a clearly defined well capture zone, but to a plane representation of the probability of a certain surface location belonging to the well capture zone. The models were applied to a study site, which is located in an area of artificial groundwater recharge and production, in Lange Erlen near Basel, Northwestern Switzerland. The groundwater at this site contributes to the city’s drinking water supply, and the site serves as a recreational area to the population of Basel. The river is channelized, but there are initiatives to restore the riverbank to more natural conditions. However, they conflict with the requirements of groundwater protection, especially during flood events. Therefore, a river section of 600 m in the vicinity of an unused and disconnected drinking water well was restored to study changes in the groundwater flow regime depending on hydrologic variations, water supply operation data, progress of river restoration, and subsurface heterogeneity. The results of the groundwater models are compared with data from two tracer experiments using Uranine and the natural Radon isotope Rn-222, and with physical, chemical, and microbiological data sampled in monitoring wells between the river and the drinking water well. The groundwater models document significant variations regarding the dimension of the well capture zone depending on changing boundary conditions and the variability of the hydraulic aquifer properties. The knowledge of the subsurface heterogeneity is important to evaluate transport times and distances of microorganisms from the infiltrating river or the riverbank to the drinking water well. The data from the monitoring wells show that chemical and microbiological processes predominantly occur in the hyporheic interstitial zone and the riverbank within a range of a few meters up to a few 10s of meters from the river. The methods presented here can be used to define and evaluate groundwater protection zones in heterogeneous aquifers associated with infiltration from rivers under changing boundary conditions, and under the uncertainty of subsurface heterogeneity. Furthermore, they allow one to study the site-specific operational alternatives associated with river restoration.

Pollution in the shallow subsurface has led to an increasing need of understanding how to quantitatively characterize both the heterogeneity of gravel aquifers and the influence of heterogeneity on groundwater flow and solute transport. Models play an important role in decision-making processes, especially in the context of better characterizing and in forecasting the behavior of a given geological system. The objective of the present paper is the derivation of a gradual lithofacies-based interpretation of outcrop, drill core, and ground penetrating radar (GPR or georadar) data of different quality. The presented method allows a probability estimation of drill core layer descriptions and radarfacies types representing defined sedimentary structure types. The method includes a determination of ‘initial structure type probabilities’ for grain-size categories and combinations thereof described in drill core layer descriptions as well as a subsequent differentiation of these structure type probabilities in an iterative process considering ‘additional information’ like main constituent, quantity, fraction, and sorting of single grain-size categories, color, chemical precipitation, layer thickness, and adjacent layer. The radarfacies types are calibrated with drill cores located in the vicinity of georadar sections. The calibration process consists of the assignment of the calculated structure type probabilities from the drill core layer descriptions to the corresponding radarfacies types considering the proportion in thickness between drill core layers and georadar structures. The structure type probabilities can be given for points along boreholes and a grid with arbitrary mesh size along georadar sections. The method is applied to field examples from the Rhine/Wiese aquifer near Basel in Switzerland. The resulting structure type probabilities can be used for conditioning stochastic simulations of geological models. However, the conditioned stochastic simulation of the Rhine/Wiese aquifer is the topic of another paper. The results show the importance of a detailed sedimentological analysis of outcrops and drill cores as well as its significance on the distinction of sedimentary structure types.

Statistical information on sedimentary structures determined from natural gravel deposits in north-eastern Switzerland is used to characterize transport phenomena of aquifers. These aquifers essentially consist of a background gravel matrix with embedded lenses of different hydraulic properties and internal structure. One of the embedded materials is highly conductive open framework gravel which leads to a bimodal probability density function of the hydraulic conductivity of the overall gravel material. Based on an analysis of this information three approaches to modeling macrodispersion are suggested. In the first one distinct unconditioned realizations of synthetic block shaped facies type aquifers are generated numerically such that they exhibit the same statistical properties with respect to facies geometry and hydraulic properties as the deposits themselves. Numerical experiments simulating saturated flow and transport were subsequently performed with the help of a three-dimensional finite element fl...

In this study a three-dimensional stochastic facies-based aquifer model was developed. The model can be used to numerically simulate flow and solute transport in heterogeneous groundwater aquifers. The stochastic generation process can be conditioned by using available facies information in one vertical plane or two orthogonal vertical ones. In this study the information was obtained from a facies interpretation of a vertical georadar profile in a natural gravel formation in Switzerland. In the domain outside the known profile, unconditioned lenses and layers were generated at random according to statistical information on coherent sedimentary structures based on observations in adjacent gravel pits [Jussel et al., 1994a]. The method was applied to a single extraction well designed to capture an initially block-shaped contaminant plume. A total of 80 conditioned and unconditioned synthetic aquifers was generated. The flow and transport simulations were performed using a finite element flow model and a random walk transport model. The results are presented as the ensemble of integral solute mass recovery curves of single realizations. One would expect conditioning to reduce the bandwidth of the recovery curves representing the uncertainty, but the results show that the bandwidth even increased. This effect was attributed to a discrepancy in the mean volumetric fraction of the different facies types in the conditioned and the unconditioned cases. Moreover, a simulation using a homogeneous model with constant equivalent flow and transport parameters overestimated the remediation efficiency. The influence of a linear, reversible equilibrium sorption on the remediation well efficiency was taken into account by an uncorrelated random field of the retardation factor based on values from the literature. However, the impact of the variability in hydraulic conductivity clearly exceeded the effect of the variability in the retardation factor.

The scleral pocket technique has dramatically changed wound closure after phacoemulsification with implantation of a posterior chamber lens. The use of single-stitch technique and wound closure by fibrin adhesive is now possible. We conducted a comparative study of 385 consecutive patients; 167 received only fibrin glue for wound closure and 218 had the single-stitch procedure. No complications were observed in either group. Surgically induced astigmatism was smaller in the fibrin group (vector analysis: 0.80 diopters [D]) than in the single-stitch group (vector analysis: 0.99 D). Minimal, statistically insignificant different against-the-rule astigmatism developed: single-stitch group: -0.07 D (Cravy), -0.09 D (Naeser); fibrin adhesive group: -0.13 D (Cravy), -0.17 D (Naeser). These results suggest that postoperative against-the-rule astigmatism can be prevented with fibrin glue.