Detection of hidden model errors by combining single and multi-criteria calibration.

Environmental models aim to reproduce landscape processes with mathematical equations. Observations are used for validation. The performance and uncertainties are quantified either by single or multi-criteria model assessment. In a case-study, we combine both approaches. We use a coupled hydro-biogeochemistry landscape-scale model to simulate 14 target values on discharge, stream nitrate as well as soil moisture, soil temperature and trace gas emissions (N2O, CO2) from different land uses. We reveal typical mistakes that happen during both, single and multi-criteria model assessment. Such as overestimated uncertainty in multi-criteria and ignored wrong model processes in single-criterion calibration. These mistakes can mislead the development of water quality and in general all environmental models. Only the combination of both approaches reveals the five types of posterior probability distributions for model parameters. Each type allocates a specific type of error. We identify and locate mismatched parameter values, obsolete parameters, flawed model structures and wrong process representations. The presented method can guide model users and developers to the so far hidden errors in their models. We emphasize to include observations from physical, chemical, biological and ecological processes in the model assessment, rather than the typical discipline specific assessments.

Accelerated Cognitive Ageing in epilepsy: exploring the effective connectivity between resting-state networks and its relation to cognitive decline.

OBJECTIVE: This study aims at understanding the dynamic functional brain organization in Accelerated Cognitive Ageing (ACA) in epilepsy. We also assess to which extend the (abnormal) effective connectivity between brain networks correlates with the (estimated) decline in IQ scores observed in the ACA patients. MATERIAL AND METHODS: Two multi-echo resting-state fMRI scans of 10 ACA patients and 14 age- and education-matched healthy controls were acquired. A task-based fMRI was acquired in-between those two scans, for possible cognitive fatigue effects on reserve capacity. Granger causality (GC), a measure of effective connectivity between brain regions, was applied on 7 major cognitive networks, and group-wise compared, using permutation testing statistics. This was performed on each of the resting-state sessions independently. We assessed the correlation between the cognitive deterioration scores (representing cognitive decline), and the paired-networks granger causality values. RESULTS: The cingulate cortex appeared to be more engaged in ACA patients. Its dynamics towards the right fronto-parietal cortex, salience network, and the dorsal attention networks (DAN) was stronger than in controls, only in the first resting-state scan session. The Granger causality from the DAN to the default mode network (DMN) and from the ventral attention network (VAN) to the left fronto-parietal network (FPL) was also stronger in ACA patients and again only in the first scans. In the second resting-state scans, only the DMN was more strongly connected with the cingulate cortex in ACA patients. A weaker GC from DMN to FPL, and stronger GC from the salience network to cingulate cortex were associated with more decline in the Full-scale IQ and more GC from DMN to VAN would lead to more decline in the Perceptual Reasoning Index in ACA. CONCLUSION: The results are in line with the hypothesis of over-recruitment at low cognitive load, and exhaustion at higher cognitive load, as shown by the compensation-related utilization of neural circuits hypothesis (CRUNCH) model for ageing. Moreover, the DMN to VAN directed connectivity strongly correlates with the (estimated) decline in the Perceptual Reasoning Index, which is also in line with a recent study on ageing with mild cognitive impairment in elderly, and the posterior-anterior shift in aging (PASA) model. This study therefore supports the idea that the cognitive decline in our patients resembles the decline observed in healthy ageing, but in an accelerated mode. This study also sheds light on the directions of the impaired connectivity between the main networks involved in the deterioration process, which can be helpful for future development of treatment solutions.

Citizen science in hydrological monitoring and ecosystem services management: State of the art and future prospects.

Hydrological monitoring is essential to guide evidence-based decision making necessary for sustainable water resource management and governance. Limited hydrometric datasets and the pressure on long-term hydrological monitoring networks make it paramount to explore alternative methods for data collection. This is particularly the case for low-income countries, where data scarcity is more pronounced, and where conventional monitoring methods are expensive and logistically challenging. Citizen science in hydrological research has recently gained popularity and crowdsourced monitoring is a promising cost-effective approach for data collection. Citizen science also has the potential to enhance knowledge co-creation and science-based evidence that underpins the governance and management of water resources. This paper provides a comprehensive review on citizen science and crowdsourced data collection within the context of hydrology, based on a synthesis of 71 articles from 2001 to 2018. Application of citizen science in hydrology is increasing in number and breadth, generating a plethora of scientific data. Citizen science approaches differ in scale, scope and degree of citizen involvement. Most of the programs are found in North America and Europe. Participation mostly comprises a contributory citizen science model, which engages citizens in data collection. In order to leverage the full potential of citizen science in knowledge co-generation, future citizen science projects in hydrology could benefit from more co-created types of projects that establish strong ties between research and public engagement, thereby enhancing the long-term sustainability of monitoring networks.

Citizen science pioneers in Kenya - A crowdsourced approach for hydrological monitoring.

Although water is involved in many ecosystem services, the absence of monitoring data restricts the development of effective water management strategies especially in remote regions. Traditional monitoring networks can be expensive, with unaffordable costs in many low-income countries. Involving citizens in monitoring through crowdsourcing has the potential to reduce these costs but remains uncommon in hydrology. This study evaluates the quality and quantity of data generated by citizens in a remote Kenyan basin and assesses whether crowdsourcing is a suitable method to overcome data scarcity. We installed thirteen water level gauges equipped with signboards explaining the monitoring process to passers-by. Results were sent via a text-message-based data collection framework that included an immediate feedback to citizens. A public web interface was used to visualize the data. Within the first year, 124 citizens reported 1175 valid measurements. We identified thirteen citizens as active observers providing more than ten measurements, whereas 57% only sent one record. A comparison between the crowdsourced water level data and an automatic gauging station revealed high data quality. The results of this study indicate that citizens can provide water level data of sufficient quality and with high temporal resolution.

[Telemedicine in stroke care]. / Telemedizin in der Schlaganfallversorgung.

Telemedicine is already widely used in many telestroke networks and ensures stroke treatment close to the patient's home in rural and medically underserved areas. This is particularly effective when telemedicine is integrated into a stroke unit concept. While telemedically based thrombolysis therapy has become routine practice for many years, practical implementation of comprehensive mechanical thrombectomy and the related processes remains challenging. The main tasks for the future further include development of a structured stroke aftercare system in neurologically underserved areas and permanent assurance of high-quality stroke care in telemedically connected sites.

[Telemedicine: Comprehensive coverage and quality - Not a contradiction : Practical experience from the stroke network with telemedicine in northern Bavaria (STENO)]. / Telemedizin: Flächendeckung und Qualität ­ kein Widerspruch : Praktische Erfahrungen aus dem Schlaganfallnetzwerk mit Telemedizin in Nordbayern STENO.

Telemedicine is widely used in the field of stroke treatment. Following the pioneering and implementation phase, the quality of the whole stroke treatment process needs to be ensured in telemedically connected hospitals. This is particular important for telestroke hospitals without neurological expertise and can be achieved by integrating telemedicine into the stroke unit concept and stroke networks. The Stroke Network with Telemedicine in Northern Bavaria (STENO) provides an example of how quality management can be practically implemented. The implementation of STENO has established a network-wide quality management system which has been certified according to DIN EN ISO 9001:2008 since 2011.

Cognitive deterioration in adult epilepsy: clinical characteristics of "Accelerated Cognitive Ageing".

OBJECTIVES: "Epileptic dementia" is reported in adults with childhood-onset refractory epilepsy. Cognitive deterioration can also occur in a "second-hit model". MATERIALS AND METHODS: We studied the clinical and neuropsychological characteristics of patients with cognitive deterioration (≥1 SD discrepancy between current IQ and premorbid IQ). Memory function, reaction time and processing speed were also evaluated. Analyses were performed to investigate which clinical characteristics correlated with cognitive deterioration. RESULTS: Twenty-seven patients were included with a mean age of 55.7 years old, an average age at epilepsy onset of 33.9 years and a mean duration of 21.8 years. Over 40% had experienced at least one status epilepticus. About 77.8% had at least one comorbid disease (most of (cardio)vascular origin). Cognitive deterioration scores were significant for both Performance IQ and Full Scale IQ, but not for Verbal IQ. Impairments in fluid functions primarily affected the IQ-scores. Memory was not impaired. Epilepsy factors explained 7% of the variance in deterioration, whereas 38% was explained by relatively low premorbid IQ and educational level, high age at seizure onset and older age. CONCLUSIONS: A subgroup of patients with localization-related epilepsy exhibits cognitive decline characterized by deterioration in PIQ and FSIQ, but with preserved higher order functions (VIQ and memory). Patients typically have epilepsia tarda, comorbid pathology, relatively low educational level and older age. These are factors known to increase the vulnerability of the brain by diminishing cognitive reserve. Cognitive deterioration may develop according to a stepwise "second-hit model", affecting and accelerating the cognitive ageing process.

[Invasive stroke treatment - Study results and clinical routine : Lost in translation?]. / Invasive Schlaganfallbehandlung - Studienergebnisse und klinische Routine : Lost in translation?

OBJECTIVE: How can the overwhelmingly positive results of the five randomized thrombectomy trials published in 2015 be transferred to the clinical routine? MATERIAL AND METHODS: Analysis of trial-specific characteristics with regard to implementation of mechanical thrombectomy into clinical routine. RESULTS: Stroke patients with symptomatic proximal artery occlusion are principally eligible for mechanical thrombectomy; however, the stroke patients included in the thrombectomy trials are not representative of all stroke patients. They were carefully selected according to clinical and imaging criteria as well as to the time window from symptom onset. Furthermore, they were treated in highly selected specialized stroke centers. Analysis of the five trials and the Catalan population-based SONIIA registry revealed that the observed number needed to treat (NNT) of 5 to reach a modified Rankin scale (mRS) score of 0-2 only applies to approximately 1 % of all stroke patients. The NNT for the remaining patients who are principally eligible for thrombectomy requires further study. Currently, centralization seems to be useful to facilitate mechanical thrombectomy in routine care leading to several problems that have to be dealt with in particular regions. Secondary transport to thrombectomy centers plays a major role in this context and has to be provided with highest priority. CONCLUSION: Only careful analysis of study results and the background circumstances will enable adequate organization and successful practical implementation of this highly effective therapy in the clinical routine. Regional conditions have to be considered and will be crucial in this context.

Technical aspects of neurostimulation: Focus on equipment, electric field modeling, and stimulation protocols.

Neuromodulation is a field of science, medicine, and bioengineering that encompasses implantable and non-implantable technologies for the purpose of improving quality of life and functioning of humans. Brain neuromodulation involves different neurostimulation techniques: transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), vagus nerve stimulation (VNS), and deep brain stimulation (DBS), which are being used both to study their effects on cognitive brain functions and to treat neuropsychiatric disorders. The mechanisms of action of neurostimulation remain incompletely understood. Insight into the technical basis of neurostimulation might be a first step towards a more profound understanding of these mechanisms, which might lead to improved clinical outcome and therapeutic potential. This review provides an overview of the technical basis of neurostimulation focusing on the equipment, the present understanding of induced electric fields, and the stimulation protocols. The review is written from a technical perspective aimed at supporting the use of neurostimulation in clinical practice.

Mental slowing in relation to epilepsy and antiepileptic medication.

OBJECTIVES: Slowing of the central information-processing speed (CIPS) is frequently observed in epilepsy as a consequence of epileptic seizures and/or antiepileptic drugs (AEDs). A variety of neuropsychological tests are used to asses this 'mental slowing,' but it is highly questionable whether the different tasks measure the same cognitive process. Also, it remains unspecified to which degree the various tasks are sensitive to seizure- or treatment-related factors, or both. METHODS: We used an open clinical non-comparative study design. The sample consisted of adult patients with cryptogenic localization-related epilepsy who performed different cognitive measures of CIPS and psychomotor speed (PmS). Clinical data about their seizures and antiepileptic drug treatment were collected from an electronic patient database. RESULTS: Eighty patients were included. CIPS tasks mutually correlated significantly, but did not correlate with measures of PmS (finger tapping and reaction time). Also, the CIPS tasks were differently affected by treatment and seizure effects. Processing of complex information is affected by tonic-clonic seizures, while less complex tasks are more sensitive for AED effects. CONCLUSIONS: CIPS tasks are mainly measuring central processing, and the psychomotor component of these tasks is negligible. We propose a psychometric continuum on which PmS and CIPS tasks are ordered with ascending complexity. The model shows that the tasks are affected differently by seizures, treatment, age, and education level. In neuropsychological practice, this continuum can be helpful in the detection of treatment and seizure effects on the CIPS in epilepsy.

A new setup for the investigation of swift heavy ion induced particle emission and surface modifications.

The irradiation with fast ions with kinetic energies of >10 MeV leads to the deposition of a high amount of energy along their trajectory (up to several ten keV/nm). The energy is mainly transferred to the electronic subsystem and induces different secondary processes of excitations, which result in significant material modifications. A new setup to study these ion induced effects on surfaces will be described in this paper. The setup combines a variable irradiation chamber with different techniques of surface characterizations like scanning probe microscopy, time-of-flight secondary ion, and neutral mass spectrometry, as well as low energy electron diffraction under ultra high vacuum conditions, and is mounted at a beamline of the universal linear accelerator (UNILAC) of the GSI facility in Darmstadt, Germany. Here, samples can be irradiated with high-energy ions with a total kinetic energy up to several GeVs under different angles of incidence. Our setup enables the preparation and in situ analysis of different types of sample systems ranging from metals to insulators. Time-of-flight secondary ion mass spectrometry enables us to study the chemical composition of the surface, while scanning probe microscopy allows a detailed view into the local electrical and morphological conditions of the sample surface down to atomic scales. With the new setup, particle emission during irradiation as well as persistent modifications of the surface after irradiation can thus be studied. We present first data obtained with the new setup, including a novel measuring protocol for time-of-flight mass spectrometry with the GSI UNILAC accelerator.

Cognitive deterioration in adult epilepsy: Does accelerated cognitive ageing exist?

A long-standing concern has been whether epilepsy contributes to cognitive decline or so-called 'epileptic dementia'. Although global cognitive decline is generally reported in the context of chronic refractory epilepsy, it is largely unknown what percentage of patients is at risk for decline. This review is focused on the identification of risk factors and characterization of aberrant cognitive trajectories in epilepsy. Evidence is found that the cognitive trajectory of patients with epilepsy over time differs from processes of cognitive ageing in healthy people, especially in adulthood-onset epilepsy. Cognitive deterioration in these patients seems to develop in a 'second hit model' and occurs when epilepsy hits on a brain that is already vulnerable or vice versa when comorbid problems develop in a person with epilepsy. Processes of ageing may be accelerated due to loss of brain plasticity and cognitive reserve capacity for which we coin the term 'accelerated cognitive ageing'. We believe that the concept of accelerated cognitive ageing can be helpful in providing a framework understanding global cognitive deterioration in epilepsy.

Waiting for platelet counts causes unsubstantiated delay of thrombolysis therapy.

BACKGROUND: Platelet counts (PCs) <100,000/µl are considered as a contraindication for intravenous thrombolysis (IVT). While US guidelines recommend IVT initiation before the availability of clotting tests, the guidelines of the European Stroke Organization give no such practical advice. We aimed to assess the incidence of thrombocytopenia in IVT patients, outcome after thrombolysis in affected patients and the time gained by initiating treatment prior to availability of PC results. METHODS: All patients with thrombocytopenia were identified in our prospectively acquired thrombolysis database. Baseline demographic data, intracerebral hemorrhage rates as well as functional outcome were assessed. The median time between initiation of thrombolysis and availability of PCs was calculated. RESULTS: Of 625 IVT patients, 3 (0.5%) had thrombocytopenia at stroke onset. None of them developed intracerebral hemorrhage (ICH) or died during the follow-up. Waiting for PCs would have delayed treatment in 72.4% of the patients, with a median hypothetical delay of 22 min (interquartile range: 11-41 min). CONCLUSIONS: To date, there are no sufficient data to evaluate the ICH risk in thrombocytopenic patients. However, thrombocytopenia is rare in IVT patients. Thus, generally waiting for PC results prior to initiation of IVT is not warranted. Avoiding this significant delay yields shorter door-to-needle times and potentially more effective treatment.

Comparison of conventional CTA and volume perfusion CTA in evaluation of cerebral arterial vasculature in acute stroke.

BACKGROUND AND PURPOSE: CTA-like datasets can be reconstructed from whole-brain VPCTA. The aim of our study was to compare VPCTA with CTA for detection of intracranial stenosis and occlusion in stroke patients. Omitting CTA from stroke CT could reduce radiation dose. MATERIALS AND METHODS: One hundred sixty-three patients were included in this retrospective analysis. Inclusion criterion was suspected stroke within 4.5 hours after onset of symptoms. All examinations were performed on a 128-section multidetector CT scanner. Axial, coronal, and sagittal maximum intensity projections were reconstructed from CTA and from peak arterial phase of VPCTA. Images were scored for quality and presence of intracranial stenosis >50% or occlusion. For statistical analysis, the Wilcoxon signed-rank test and Fisher exact test were used, with a 2-tailed P value of .05 or less for statistical significance. RESULTS: Average image quality was superior in CTA (P < .05). However, image quality dichotomized for diagnostic significance was without difference between CTA and VPCTA (P > .05). Comparative statistical analysis revealed no significant difference for detection of intracranial stenosis and occlusion between CTA and VPCTA (P > .05). Substitution of intracranial CTA by VPCTA would lower radiation dose by 0.5 mSv. CONCLUSIONS: VPCTA is suited to assess the intracranial vasculature in patients with stroke and might have the potential to decrease radiation dose by substituting for intracranial CTA in stroke CT. Additional studies are necessary to further evaluate potential benefits of the dynamic nature of VPCTA.

Off-label thrombolysis for acute ischemic stroke: rate, clinical outcome and safety are influenced by the definition of 'minor stroke'.

BACKGROUND: Several contraindications for intravenous thrombolysis are not based on controlled trials. Specialized stroke centers often apply less restrictive criteria. The aim of our study was to analyze how many patients at our institution receive off-label thrombolysis. In addition, clinical outcome and safety data were compared to those from patients treated on-label, and the influence of different definitions of 'minor stroke' were examined. METHODS: Consecutive thrombolysis patients treated between January 2006 and January 2010 were included. Patients treated off-label were compared to patients given on-label therapy according to the European license. Since no specified definition for 'minor neurological deficit' exists in the license, two distinct definitions were considered off-label, i.e. National Institutes of Health Stroke Scale score (NIHSSS) <1 (definition 1) and NIHSSS ≤4 (definition 2). RESULTS: Of a total of 422 patients, 232 (55%) were treated off-label. The most prevalent off-label criteria (OLCs) were the following: age >80 years (n = 113), minor stroke (definition 1, n = 3; definition 2, n = 84), elevated blood pressure necessitating aggressive treatment (n = 75), time window >3 h (n = 71) and major surgery or trauma within the preceding 3 months (n = 20). In group comparisons, off-label patients had an overall worse outcome using definition 1 for minor stroke, while there was no difference when definition 2 was applied. In multivariate analysis, off-label therapy (definition 1) in general and age >80 years were independent predictors of poor outcome. None of the contraindications were associated with an increased bleeding risk. CONCLUSIONS: Off-label therapy is frequently applied at our center and is not associated with higher complication rates. Overall outcome of off-label treatment largely depends on the definition used for minor stroke. Besides age >80 years, a known poor prognostic factor, no other specific OLC was associated with poor outcome. Our data suggest that the criteria in the European license may be too restrictive.

Intravenous thrombolysis in posterior cerebral artery infarctions.

BACKGROUND: Approximately 5-10% of all acute ischemic strokes (AIS) occur in the territory of the posterior cerebral artery (PCA). Little is known about intravenous thrombolysis (IVT) in this infarct subgroup in terms of outcome and intracerebral hemorrhage rates. The aim of our study was to evaluate differences between supratentorial PCA infarcts and anterior circulation infarcts regarding baseline characteristics, stroke severity, outcome, safety and clinical findings, which would implicate a change in the existing thrombolysis practice in patients with PCA stroke. METHODS: All patients with AIS in the supratentorial PCA territory receiving IVT between 01/2006 and 01/2010 were selected from the Erlangen Thrombolysis Database (group 1, n = 21). They were compared to all IVT patients with strokes in other supratentorial vascular territories over the same period of time (group 2, n = 398). Baseline demographic data, as well as clinical and laboratory findings were analyzed. The outcome was assessed using the modified Rankin Scale at 3 months. RESULTS: Only serum glucose levels at baseline (110.5 ± 36.1 vs. 127.2 ± 48.2 mg/dl; p = 0.036) and the baseline National Institutes of Health Stroke Scale score (median 6.5 vs. 9; p = 0.016) were significantly lower in group 1 compared to group 2. Favorable clinical outcome (57.1 vs. 48.6%; p = 0.445) and intracerebral hemorrhage rates (4.8 vs. 4%; p = 1.000) were comparable in both groups. CONCLUSIONS: No substantial differences were found between supratentorial PCA and anterior circulation infarcts. Our data on safety and efficacy support the present common thrombolysis practice in supratentorial PCA infarct patients, though an indication for IVT should rather be based on the existence of functionally disabling deficit than merely on the National Institutes of Health Stroke Scale.

Characteristics and outcome of patients with early complete neurological recovery after thrombolysis for acute ischemic stroke.

BACKGROUND: Recombinant tissue plasminogen activator (rt-PA) is the only approved specific therapy for acute ischemic stroke. This study analyzes demographic and clinical characteristics of patients with early complete neurological recovery after thrombolysis. METHODS: Data of 320 consecutive patients treated with rt-PA within 3 h of stroke onset at our facility between April 2006 and March 2009 were extracted from our prospective institutional stroke and thrombolysis database. Baseline demographic parameters, risk factors, clinical characteristics as well as neuroradiologic findings of patients with complete recovery 24 h after treatment and at hospital discharge were analyzed. Outcome was evaluated using the modified Rankin Scale at 90 days. RESULTS: Thirty patients (9.4%) were asymptomatic 24 h after thrombolysis and 70 (22%) at hospital discharge. Patients with complete recovery were younger, more often male, had milder stroke symptoms, less often cardioembolic strokes, fewer bleeding complications and more often normal follow-up imaging. In addition, in-hospital time was shorter and these patients retained a better functional outcome at 90 days. Only 1 patient who had completely recovered at hospital discharge died during the follow-up time. In multivariate regression analysis, only the National Institute of Health Stroke Score (NIHSS) on admission was predictive for complete recovery at both examined time points. CONCLUSION: Rapid complete recovery can be achieved in up to a fifth of acute stroke patients treated with thrombolysis. These patients are younger and have milder strokes, less often with cardioembolic origin. Better outcome and lower mortality are sustained at 3 months.

Feasibility and safety of magnetic resonance imaging-based thrombolysis in patients with stroke on awakening: initial single-centre experience.

BACKGROUND: Up to 25% of all acute ischaemic strokes occur during sleep. Because of the unclear time window, patients with stroke on awakening are usually not considered for acute therapy and excluded from most acute treatment trials. AIM: To evaluate the feasibility of magnetic resonance imaging-based intravenous thrombolysis in patients with stroke on awakening in a routine clinical setting. METHODS: Forty-five patients with stroke on awakening clinically qualifying for intravenous thrombolysis and presenting within 6 h after symptom recognition were admitted to our institution between October 2006 and May 2008. Following an institutional protocol, patients received magnetic resonance imaging as a first-line imaging modality and were offered mismatch-based thrombolysis whenever possible. Baseline demographic data, clinical, laboratory and imaging findings were analysed. Outcome was assessed using the modified Rankin Scale score at 3 months. RESULTS: Magnetic resonance imaging screening was feasible in 43/45 patients (96%). After screening, 10 patients (22%) were treated with intravenous thrombolysis. There were no differences between treated and untreated patients regarding cardiovascular risk factors, stroke aetiology, previous prophylactic treatment and symptom recognition to door time or door to imaging time. Outcome was comparable in both groups despite a trend towards more severe strokes in the intravenous thrombolysis group. Only one asymptomatic and no symptomatic haemorrhage were observed. CONCLUSION: Our data demonstrate that magnetic resonance imaging-based thrombolysis is feasible and possibly safe in patients with stroke on awakening (SOA). Randomised clinical trials for patients with stroke on awakening are needed to further test the safety and efficacy of intravenous thrombolysis in this patient group. The results of our study may help to initiate and design such studies.