Sizeable net export of base cations from a Carpathian flysch catchment indicates their geogenic origin while the 26Mg/24Mg, 44Ca/40Ca and 87Sr/86Sr isotope ratios in runoff are indistinguishable from atmospheric input.

Nutrient imbalances may negatively affect the health status of forests exposed to multiple stress factors, including drought and bark beetle calamities. We studied the origin of base cations in runoff from a small Carpathian catchment underlain by base-poor flysch turbidites using magnesium (Mg), calcium (Ca) and strontium (Sr) isotope composition of 10 ecosystem compartments. Our objective was to constrain conclusions drawn from long-term hydrochemical monitoring of inputs and outputs. Annual export of Mg, Ca and Sr exceeds 5-to-15 times their atmospheric input. Mass budgets per se thus indicate sizeable net leaching of Mg, Ca and Sr from bedrock sandstones and claystones. Surprisingly, δ26Mg, δ44Ca and 87Sr/86Sr isotope ratios of runoff were practically identical to those of atmospheric deposition and soil water but significantly different from bedrock isotope ratios. We did not find any carbonates in the studied area as a hypothetical, easily dissolvable source of base cations whose isotope composition might corroborate the predominance of geogenic base cations in the runoff. Marine carbonates typically have lower δ26 Mg and 87Sr/86Sr ratios, and silicate sediments often have higher δ26Mg and 87Sr/86Sr ratios than runoff at the study site. Mixing of these two sources, if confirmed, could reconcile the flux and isotope data.

Survival and Freedom From Reinterventions in Patients With Repaired Tetralogy of Fallot: Up to 42-Year Follow-Up of 917 Patients.

Background To evaluate long-term outcome of tetralogy of Fallot repair analyzing an unbiased country-wide surgically treated population with tetralogy of Fallot. Methods and Results Retrospective analysis of consecutive patients aged <18 years who underwent tetralogy of Fallot repair at a single nationwide pediatric cardiac center. Death from any cause and need for surgical or catheter reintervention were the study end points. Cox regression analysis was used to identify related risk factors. A total of 917 patients (male, 56.3%) were analyzed. Staged repair was performed in 16.9%. Early mortality (24/917, 2.62% patients) was confined to the early surgical eras. Late mortality was 4.5% (40/893 patients). Survival probability was 95.1%, 93.8% and 91.9% at 10, 20 and 30 years after repair, respectively. Early surgical era (P=0.013) and surgical/catheter reinterventions (P<0.001) were multivariable predictors of late death. A total of 487 reinterventions were performed after initial repair in 253/917 patients (27.6%), with pulmonary artery revalvulation (196/917 patients, 21.4%) being most frequent. Probability of freedom from first reintervention was 89.0%, 73.3%, and 55.1% at 10, 20, and 30 years after primary repair, respectively. Transannular repair was associated with the need for pulmonary artery revalvulation (P<0.001). Patients who underwent staged repair were more likely to need reinterventions on pulmonary arteries (P<0.001). Conclusions In an unbiased nationwide cohort, tetralogy of Fallot repair carried a favorable survival of >90% at 30 years. Each reintervention significantly incrementally increased the risk of mortality. Type of initial repair predicted the need for specific surgical or catheter reinterventions.

Baseline reticular basement membrane morphology is related to subsequent spirometry deterioration in pediatric chronic airway inflammation: a follow-up study.

Reticular basement membrane (RBM) thickening may occur in children with allergic bronchial asthma (BA), cystic fibrosis (CF), and primary ciliary dyskinesia (PCD). Its functional consequences remain unknown. We investigated the relationship between baseline RBM thickness and subsequent spirometry. In our cohort follow-up study, patients aged 3-18 yr with BA, CF, and PCD and controls underwent baseline lung clearance index (LCI) measurement, spirometry, and endobronchial biopsy sampling. Total RBM and collagen IV-positive layer thickness were measured. Trends in forced vital capacity (FVC), forced expired volume in 1 s (FEV1), and FEV1/FVC were analyzed during follow-up, and their relationship to baseline characteristics was studied using univariate analysis and multiple regression models. Complete baseline data were available in 19 patients with BA, 30 patients with CF, 25 patients with PCD, and 19 controls. The RBM was thicker in patients with BA (6.33 ± 1.22 µm), CF (5.60 ± 1.39 µm), and PCD (6.50 ± 1.87 µm) than in controls (3.29 ± 0.55 µm) (all P < 0.001). The LCI was higher in patients with CF (15.32 ± 4.58, P < 0.001) and PCD (10.97 ± 2.46, P = 0.002) than in controls (7.44 ± 0.43). The median follow-up times were 3.6, 4.8, 5.7, and 1.9 years in patients with BA, CF, PCD, and controls, respectively. The z-scores of FEV1 and FEV1/FVC deteriorated significantly in all groups except in controls. In patients with CF and PCD, trends in FEV1 z-scores correlated with baseline LCI and RBM; in BA, it correlated with collagen IV. In multiple regression models, RBM morphology and ventilation inhomogeneity could predict up to 84.4% of variability in spirometry trends. In conclusion, baseline LCI value and RBM morphology may predict trends in subsequent spirometry.NEW & NOTEWORTHY This paper deals with the relationship between reticular basement membrane (RBM) morphology at baseline and follow-up spirometry in children with asthma, cystic fibrosis, and primary ciliary dyskinesia. For the first time, to our knowledge, the possibility to predict subsequent lung function development using selected baseline characteristics (reticular basement membrane morphology from endobronchial biopsy and ventilation inhomogeneity from nitrogen multiple breath washout test) is proposed. Corresponding predictive models are presented.

Comparison of vertical and horizontal atmospheric deposition of nitrate at Central European mountain-top sites during three consecutive winters.

Nitrogen (N) deposition, a key process of atmospheric self-cleaning, represents an important pathway for nutrients and pollutants to ecosystems. Enhanced N deposition flux contributes to acidification, eutrophication and loss of biodiversity. N-NO3- concentrations in rime and snow were measured at 10 Czech plots situated in borderline mountains in 2009-2011 winters. The results were put in context with data-driven geostatistical modelling results of annual wet vertical and horizontal deposition. Our hypotheses were that: (i) rime and snow would be more polluted in the highly industrialized north than in the south, (ii) the N-NO3- concentrations would differ in the three winters studied, and (iii), that N-NO3- rime deposition is not negligible in Central European mountain ranges. Our results indicated that winter N-NO3- concentrations were significantly higher in rime than in snow and that there were much larger between-site differences in N-NO3- concentrations for rime than for snow. Relatively large differences were found between individual years. Atmospheric input of N-NO3- in winter was dominated by vertical deposition, i.e., snow. Modelled results showed that mean winter rime deposition corresponded to about 6-25 %, and mean winter snow deposition made up 25-72.5 % of mean annual N-NO3- wet-only deposition. Model N-NO3-occult deposition estimated from throughfall and total (wet and dry) deposition is highly uncertain, however: N throughfall is not a relevant proxy for estimation of realistic total N deposition due to N exchange between the tree canopy and atmosphere.

Implementation of Client-Centered Care Coordination for HIV Prevention with Black Men Who Have Sex with Men: Activities, Personnel Costs, and Outcomes-HPTN 073.

BACKGROUND: Black men who have sex with men (MSM) experience disproportionate rates of HIV infection in the USA, despite being no more likely to engage in sexual risk behaviors than other MSM racial/ethnic groups. HIV pre-exposure prophylaxis (PrEP) has been shown to reduce risk of HIV acquisition; however, rates of PrEP use among Black MSM remain low. Clinical, psychosocial, and structural factors have been shown to impact PrEP use and adherence among Black MSM. Care coordination of HIV prevention services has the potential to improve PrEP use and adherence for Black MSM, as it has been shown to improve HIV-related care outcomes among people living with HIV. METHODS: Client-centered care coordination (C4) is a multi-level intervention designed to address clinical, psychosocial, and structural barriers to HIV prevention services for Black MSM within HPTN 073, a PrEP demonstration project among Black MSM in three cities in the USA. The current study examined the implementation process of C4, specifically investigating the activities, cost, time, and outcomes associated with the C4 intervention. RESULTS: On average, participants engaged in five care coordination encounters. The vast majority of care coordination activities were conducted by counselors, averaging 30 min per encounter. The cost of care coordination was relatively low with a mean cost of $8.70 per client encounter. CONCLUSION: Although client-centered care coordination was initially implemented in well-resourced communities with robust HIV research and service infrastructure, our findings suggest that C4 can be successfully implemented in resource constrained communities.

Extracorporeal versus conventional cardiopulmonary resuscitation for refractory out-of-hospital cardiac arrest: a secondary analysis of the Prague OHCA trial.

BACKGROUND: Survival rates in refractory out-of-hospital cardiac arrest (OHCA) remain low with conventional advanced cardiac life support (ACLS). Extracorporeal life support (ECLS) implantation during ongoing resuscitation, a method called extracorporeal cardiopulmonary resuscitation (ECPR), may increase survival. This study examined whether ECPR is associated with improved outcomes. METHODS: Prague OHCA trial enrolled adults with a witnessed refractory OHCA of presumed cardiac origin. In this secondary analysis, the effect of ECPR on 180-day survival using Kaplan-Meier estimates and Cox proportional hazard model was examined. RESULTS: Among 256 patients (median age 58 years, 83% male) with median duration of resuscitation 52.5 min (36.5-68), 83 (32%) patients achieved prehospital ROSC during ongoing conventional ACLS prehospitally, 81 (32%) patients did not achieve prehospital ROSC with prolonged conventional ACLS, and 92 (36%) patients did not achieve prehospital ROSC and received ECPR. The overall 180-day survival was 51/83 (61.5%) in patients with prehospital ROSC, 1/81 (1.2%) in patients without prehospital ROSC treated with conventional ACLS and 22/92 (23.9%) in patients without prehospital ROSC treated with ECPR (log-rank p < 0.001). After adjustment for covariates (age, sex, initial rhythm, prehospital ROSC status, time of emergency medical service arrival, resuscitation time, place of cardiac arrest, percutaneous coronary intervention status), ECPR was associated with a lower risk of 180-day death (HR 0.21, 95% CI 0.14-0.31; P < 0.001). CONCLUSIONS: In this secondary analysis of the randomized refractory OHCA trial, ECPR was associated with improved 180-day survival in patients without prehospital ROSC. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT01511666, Registered 19 January 2012.

Structural Integrity and Cellular Viability of Cryopreserved Allograft Heart Valves in Right Ventricular Outflow Tract Reconstruction: Correlation of Histopathological Changes with Donor Characteristics and Preservation Times

Abstract Introduction: Cryopreserved allograft heart valves (CAHV) show longer event-free survival compared to other types of protheses. However, all patients develop early and/or late allograft failure. Negative predictors are clinical, and there is a lack of evidence whether they correspond with the microscopic structure of CAHV. We assessed histopathological signs of structural degeneration, degree of cellular preservation, and presence of antigen-presenting cells (APC) in CAHV and correlated the changes with donor clinical characteristics, cryopreservation times, and CAHV types and diameters. Methods: Fifty-seven CAHV (48 pulmonary, nine aortic) used for transplantation between November/2017 and May/2019 were included. Donor variables were age, gender, blood group, height, weight, and body surface area (BSA). Types and diameters of CAHV, cold ischemia time, period from decontamination to cryopreservation, and cryopreservation time were recorded. During surgery, arterial wall (n=56) and valvar cusp (n=20) samples were obtained from the CAHV and subjected to microscopy. Microscopic structure was assessed using basic staining methods and immunohistochemistry (IHC). Results: Most of the samples showed signs of degeneration, usually of mild degree, and markedly reduced cellular preservation, more pronounced in aortic CAHV, correlating with arterial APC counts in both basic staining and IHC. There was also a correlation between the degree of degeneration of arterial samples and age, height, weight, and BSA of the donors. These findings were independent of preservation times. Conclusion: CAHV show markedly reduced cellular preservation negatively correlating with the numbers of APC. More preserved CAHV may be therefore prone to stronger immune rejection.

Repeatability of lung clearance index in infants with cystic fibrosis and recurrent wheeze.

OBJECTIVES: To describe the short- and medium-term repeatability of lung clearance index at 2.5% (LCI2.5 ) in infants and calculate the number of patients needed to enroll in a study (N) using LCI2.5 as a primary outcome. METHODS: An 8-month follow-up observational study was employed for assessing short-term [coefficient of repeatability (CR) and intraclass correlation (ICC)] and medium-term repeatability (Bland-Altman method) of LCI2.5 in infants with cystic fibrosis (CF) or recurrent wheeze (RW) measured by the nitrogen multiple-breath washout test (N2 -MBW). Using these variability data, the N to reach 90% test power at the level of statistical significance (0.05) was calculated. RESULTS: Forty infants with CF and 21 with RW were enrolled. Initial N2 -MBW testing was successful in 33 and 17 patients, respectively. Follow-up data were available for 23 and 11 infants, respectively. Short-term repeatability of LCI2.5 was high (CR = 1.10 and 1.04 in CF and RW patients, respectively; ICC = 0.88 and 0.83 in CF and RW patients, respectively). The between-subject standard deviation was <13% of the actual LCI2.5 value. In clinically stable patients, LCI2.5 did not significantly change during the 8-month follow-up. Mean LCI2.5 change was -0.08 (1% of baseline) in CF and -0.05 (0.6%) in RW, with 95% limits of agreement being (-1.70; 1.53) in CF and (-1.51; 1.40) in RW patients. N = 23 infants if both intragroup differences of LCI2.5 and minimal difference to be detected would be 2.0. CONCLUSION: N2 -MBW may be a reproducible tool with reasonable test power to detect differences in infant studies.

Gender differences and survival after out of hospital cardiac arrest.

BACKGROUND: Published evidence regarding the effect of gender on outcome after out of hospital cardiac arrest (OHCA) is inconsistent. We aimed to investigate the association of gender to outcome and resuscitation characteristics in OHCA patients admitted to the cardiac arrest center. METHODS: In this retrospective analysis of prospective registry data, all patients admitted for OHCA were included. The influence of gender on 30-day survival and good neurological outcome (cerebral performance category of 1 or 2) were examined using Kaplan-Meier estimates and multivariable logistic regression. RESULTS: In total, 932 patients were analysed (239 women, 26%). Women were older (64 vs 60 years, p < 0.001) and less commonly had a shockable rhythm (47% vs 65%, P < 0.001) compared to men. Women were less likely to have a cardiac cause of arrest (54% vs. 75%, p < 0.001), received less therapeutic hypothermia (74% vs 86%, p < 0.001) and coronary angiography (63% vs. 79%, p < 0.001). The overall 30-day survival was lower for women (45% vs. 53%, log-rank p = 0.005) as well as good neurological outcome (37% vs. 46%, p = 0.008). However, according to the multivariate logistic regression, gender was not associated with survival (OR 0.98, 95% CI 0.65-1.50, p = 0.94) nor with good neurological outcome (OR 0.91, 95% CI 0.59-1.40, p = 0.67). CONCLUSION: Women admitted for OHCA to a cardiac center had a different cause of arrest that had a different treatment and outcome compared to men. Survival and good neurological outcome were lower in women, however, after adjusting for baseline characteristics, gender was not associated with survival nor neurological outcome.

Effect of Intra-arrest Transport, Extracorporeal Cardiopulmonary Resuscitation, and Immediate Invasive Assessment and Treatment on Functional Neurologic Outcome in Refractory Out-of-Hospital Cardiac Arrest: A Randomized Clinical Trial.

Importance: Out-of-hospital cardiac arrest (OHCA) has poor outcome. Whether intra-arrest transport, extracorporeal cardiopulmonary resuscitation (ECPR), and immediate invasive assessment and treatment (invasive strategy) is beneficial in this setting remains uncertain. Objective: To determine whether an early invasive approach in adults with refractory OHCA improves neurologically favorable survival. Design, Setting, and Participants: Single-center, randomized clinical trial in Prague, Czech Republic, of adults with a witnessed OHCA of presumed cardiac origin without return of spontaneous circulation. A total of 256 participants, of a planned sample size of 285, were enrolled between March 2013 and October 2020. Patients were observed until death or day 180 (last patient follow-up ended on March 30, 2021). Interventions: In the invasive strategy group (n = 124), mechanical compression was initiated, followed by intra-arrest transport to a cardiac center for ECPR and immediate invasive assessment and treatment. Regular advanced cardiac life support was continued on-site in the standard strategy group (n = 132). Main Outcomes and Measures: The primary outcome was survival with a good neurologic outcome (defined as Cerebral Performance Category [CPC] 1-2) at 180 days after randomization. Secondary outcomes included neurologic recovery at 30 days (defined as CPC 1-2 at any time within the first 30 days) and cardiac recovery at 30 days (defined as no need for pharmacological or mechanical cardiac support for at least 24 hours). Results: The trial was stopped at the recommendation of the data and safety monitoring board when prespecified criteria for futility were met. Among 256 patients (median age, 58 years; 44 [17%] women), 256 (100%) completed the trial. In the main analysis, 39 patients (31.5%) in the invasive strategy group and 29 (22.0%) in the standard strategy group survived to 180 days with good neurologic outcome (odds ratio [OR], 1.63 [95% CI, 0.93 to 2.85]; difference, 9.5% [95% CI, -1.3% to 20.1%]; P = .09). At 30 days, neurologic recovery had occurred in 38 patients (30.6%) in the invasive strategy group and in 24 (18.2%) in the standard strategy group (OR, 1.99 [95% CI, 1.11 to 3.57]; difference, 12.4% [95% CI, 1.9% to 22.7%]; P = .02), and cardiac recovery had occurred in 54 (43.5%) and 45 (34.1%) patients, respectively (OR, 1.49 [95% CI, 0.91 to 2.47]; difference, 9.4% [95% CI, -2.5% to 21%]; P = .12). Bleeding occurred more frequently in the invasive strategy vs standard strategy group (31% vs 15%, respectively). Conclusions and Relevance: Among patients with refractory out-of-hospital cardiac arrest, the bundle of early intra-arrest transport, ECPR, and invasive assessment and treatment did not significantly improve survival with neurologically favorable outcome at 180 days compared with standard resuscitation. However, the trial was possibly underpowered to detect a clinically relevant difference. Trial Registration: ClinicalTrials.gov Identifier: NCT01511666.

Structural Integrity and Cellular Viability of Cryopreserved Allograft Heart Valves in Right Ventricular Outflow Tract Reconstruction: Correlation of Histopathological Changes with Donor Characteristics and Preservation Times.

INTRODUCTION: Cryopreserved allograft heart valves (CAHV) show longer event-free survival compared to other types of protheses. However, all patients develop early and/or late allograft failure. Negative predictors are clinical, and there is a lack of evidence whether they correspond with the microscopic structure of CAHV. We assessed histopathological signs of structural degeneration, degree of cellular preservation, and presence of antigen-presenting cells (APC) in CAHV and correlated the changes with donor clinical characteristics, cryopreservation times, and CAHV types and diameters. METHODS: Fifty-seven CAHV (48 pulmonary, nine aortic) used for transplantation between November/2017 and May/2019 were included. Donor variables were age, gender, blood group, height, weight, and body surface area (BSA). Types and diameters of CAHV, cold ischemia time, period from decontamination to cryopreservation, and cryopreservation time were recorded. During surgery, arterial wall (n=56) and valvar cusp (n=20) samples were obtained from the CAHV and subjected to microscopy. Microscopic structure was assessed using basic staining methods and immunohistochemistry (IHC). RESULTS: Most of the samples showed signs of degeneration, usually of mild degree, and markedly reduced cellular preservation, more pronounced in aortic CAHV, correlating with arterial APC counts in both basic staining and IHC. There was also a correlation between the degree of degeneration of arterial samples and age, height, weight, and BSA of the donors. These findings were independent of preservation times. CONCLUSION: CAHV show markedly reduced cellular preservation negatively correlating with the numbers of APC. More preserved CAHV may be therefore prone to stronger immune rejection.

What is the immunity of high school students to coronavirus?

Children and young people are at the least risk of coronavirus infection and the consequences of COVID-19. However, COVID-19 has dramatically affected their lives due to many months of school closures intended to prevent the spread of the infection. In the Czech Republic, secondary schools were closed from 14 October 2020 to 24 May 2021 with a short break before Christmas. However, the students were most often infected by their parents, who usually became infected at work. The aim of this study was to find out by means of antibody testing how many high school students in Havlíčkův Brod have undergone the infection. We used questionnaires to find out how many students were in quarantine. The group included 196 students aged 15-19. Examination of IgG antibodies against the S antigen (Abbott, Architect) was performed in June 2021. Antibodies were detected in 90 of 196 students (45.9%). Coronavirus infection was reported in 88 families. Antibodies were detected in 61 quarantined students (69.3%), while the remaining 27 students had neither antibodies, nor clinical signs, nor positive PCR test. Thus, these students are considered unsusceptible to the infection at the time of quarantine. Despite the interruption of teaching in schools and the associated reduction of contacts, a significant share of students met with the coronavirus. About half of the students in the sample are already largely resistant to the disease (have antibodies). Another part of the students was unsusceptible to the disease, because they did not fall sick despite having been in contact with an infected family member.

Evaluation of marginal gap of teeth restored with crowns using six different CAD/CAM materials milled with two different milling units.

AIM: The aim of the present study was to compare the marginal gap of teeth restored with crowns using six different CAD/CAM materials with two different milling units. MATERIALS AND METHODS: Ten mandibular molar teeth were collected after surgical extractions and prepared with two different diamond-coated instruments to receive full veneer crowns. The teeth were optically scanned, designed in CAD/CAM software, and milled in two different milling units. The marginal gap was measured using an optical microscope at 200x magnification. The restricted maximum likelihood (REML) method was used to estimate unknown parameters, and the statistical calculation was performed using R software. RESULTS: The model used to answer the primary study question involved a significant (P < 0.001) instrument versus material interaction. No other interaction was statistically significant (P = 0.146). Finally, significant within-crown heteroscedasticity was found (P < 0.001) for the two different diamond-coated instruments and was taken into account in the model used. CONCLUSIONS: The marginal gaps achieved by the crowns across all groups were within a clinically acceptable range.

Catchment Runoff in Industrial Areas Exports Legacy Pollutant Zinc from the Topsoil Rather than Geogenic Zn.

In highly industrialized, densely populated parts of Central Europe, mobilization of legacy Zn pollution from forest ecosystems may negatively affect the quality of water resources. To test this hypothesis, we determined the 66Zn/64Zn isotope ratios of 15 Zn reservoirs and fluxes in an acidified, spruce die-back affected mountain-slope catchment in northern Czech Republic. The δ66Zn values of precipitation, organic horizon, and runoff were statistically indistinguishable. In contrast, δ66Zn values of bedrock orthogneiss and mineral soil were significantly different from δ66Zn values of runoff. The magnitude of within-site Zn isotope fractionations appeared to be relatively small. Despite the large potential source of Zn in bedrock, runoff exported mostly young pollutant Zn that had been temporarily stored in the organic horizon. This conclusion was corroborated by comparing Zn input-output mass balances in the polluted northern catchment and in a relatively unpolluted catchment situated 250 km to the south. Seven-times higher Zn export via runoff at the northern site was controlled by a combination of 10-times higher atmospheric Zn input and five-times higher DOC leaching, compared to the southern site. In industrial areas, atmospherically deposited Zn is leached from headwater catchments in a direct analogy to leaching of highly toxic pollutant Pb.

Demographic and public health characteristics explain large part of variability in COVID-19 mortality across countries.

BACKGROUND: The numbers of coronavirus disease 2019 (COVID-19) deaths per million people differ widely across countries. Often, the causal effects of interventions taken by authorities are unjustifiably concluded based on the comparison of pure mortalities in countries where interventions consisting different strategies have been taken. Moreover, the possible effects of other factors are only rarely considered. METHODS: We used data from open databases (European Centre for Disease Prevention and Control, World Bank Open Data, The BCG World Atlas) and publications to develop a model that could largely explain the differences in cumulative mortality between countries using non-interventional (mostly socio-demographic) factors. RESULTS: Statistically significant associations with the logarithmic COVID-19 mortality were found with the following: proportion of people aged 80 years and above, population density, proportion of urban population, gross domestic product, number of hospital beds per population, average temperature in March and incidence of tuberculosis. The final model could explain 67% of the variability. This finding could also be interpreted as follows: less than a third of the variability in logarithmic mortality differences could be modified by diverse non-pharmaceutical interventions ranging from case isolation to comprehensive measures, constituting case isolation, social distancing of the entire population and closure of schools and borders. CONCLUSIONS: In particular countries, the number of people who will die from COVID-19 is largely given by factors that cannot be drastically changed as an immediate reaction to the pandemic and authorities should focus on modifiable variables, e.g. the number of hospital beds.

Identifying influential observations in a Bayesian multi-level mediation model.

Increasingly complex models are being fit to data these days. This is especially the case for Bayesian modelling making use of Markov chain Monte Carlo methods. Tailored model diagnostics are usually lacking behind. This is also the case for Bayesian mediation models. In this paper, we developed a method for the detection of influential observations for a popular mediation model and its extensions in a Bayesian context. Detection of influential observations is based on the case-deletion principle. Importance sampling with weights which take advantage of the dependence structure in hierarchical models is utilized in order to identify the part of the model which is influenced most. We make use of the variance of log importance sampling weights as the measure of influence. It is demonstrated that this approach is useful when interest lies in the impact of individual observations on a subset of model parameters. The method is illustrated on a three-level data set from the field of nursing research, which was previously used to fit a mediation model of patient satisfaction with care. We focused on influential cases on both the second and the third level of the data.

Winter arsenic pollution in 10 forest ecosystems in the mountainous border regions of the Czech Republic.

Arsenic (As) concentrations and deposition fluxes were measured in snow and rime at 10 mountain-top sites near the borders between the Czech Republic and Austria, Germany, Poland, and Slovakia during three consecutive winter seasons (2009-2011). Our study was performed at a time following several decades of sharply decreasing regional atmospheric pollution and following the 2006 implementation of stricter air quality standards across Europe. Our objective was to compare vertical and horizontal depositions of soluble and insoluble As forms throughout the Czech Republic and define a recent Central European As pollution gradient. Arsenic soluble in weak nitric acid contributed 83 to 85% to the total As deposition, with the remaining 17-15% bound to stable particulate forms. The highest As deposition rates were recorded in the eastern Czech Republic near the borders with Poland and Slovakia. Complementary hydrochemical monitoring in four mountain-slope catchments situated near selected main study sites revealed a further decrease in open-area As deposition by the end of 2018 in the east of the country. In contrast, spruce canopy throughfall flux did not change significantly between 2009-2011 and 2016-2018. The site-specific relative roles of coal-burning-derived and ore-smelting-derived atmospheric As are discussed.