Entwicklung und Validierung einer neuen Messmethode zur Bestimmung luftgetragener aliphatischer Aldehyde

Ziel dieser Arbeit war es, ein neues Derivatisierungsreagenz für die Derivatisierung aliphatischer Aldehyde einzusetzen und eine Messmethode zur quantitativen Erfassung von insgesamt 7 Aldehyden (Acetaldehyd, Isovaleraldehyd, 2-Ethylhexanal, Propionaldehyd, Butyraldehyd, Isobutyraldehyd und Capronaldehyd) zu entwickeln und zu validieren. Das neue Reagenz 4-Methoxy-6-(4-methoxy-1-naphthyl)-1,3,5,-triazin-2-hydrazin (MMNTH) trägt an einem zentralen Triazinring eine reaktive Hydrazingruppe, eine detektierbare Methoxynaphthylgruppe und eine die Löslichkeit und die chromatographischen Eigenschaften beeinflussende Methoxygruppe. Mit der MMNTH-Methode steht ein neues sensitives, spezifisches und reproduzierbares Verfahren zur Bestimmung aliphatischer Aldehyde in der Luft zur Verfügung, das alle Anforderungen an ein Analysenverfahren zur Überwachung arbeits- und umweltbedingter Expositionen erfüllt

Seismotectonic setting at the North Anatolian Fault Zone after the 1999 Mw=7.4 Izmit earthquake based on high-resolution aftershock locations

International audienceThe most recent devastating earthquakes that occurred along the North Anatolian Fault Zone (NAFZ) in northwestern Turkey were the 1999 Izmit (Mw=7.4) and Düzce (Mw=7.1) events. In this study we present a catalog of Izmit aftershock hypocenters that was deduced from a network covering the entire 140 km long rupture of the mainshock. 7348 events with a location accuracy better than 5 km are analysed. Aftershocks were observed along the entire ruptured segment along a 20 km wide band of activity. Events are clustered in distinct regions and dominantly occur at 5 to 15 km depth. The eastern termination of the Izmit rupture is characterized by a sharp and steeply dipping boundary exactly where the Düzce mainshock initiated 87 days after the Izmit event. Relocation of the events using double-difference technology results in 4696 high-resolution hypocenters that allow resolving the internal structure of the seismically active areas with a resolution of 300 m (horizontal) and 400m (vertical). Below the Akyazi Plain, representing a small pull-apart structure at a triple junction of the NAFZ, we identify planes of activity that can be correlated with nodal planes of EW extensional normal faulting aftershocks. Along the easternmost Karadere-Düzce segment we identify the down-dip extension of the Karadere fault that hosted about 1 m of right-lateral coseismic slip. At the easternmost rupture we correlate a cloud-type distribution of seismic activity with the largest aftershocks in this area, a subevent of the Izmit mainshock and the Düzce mainshock that all have an almost identical focal mechanism. This part of the NAFZ is interpreted as a classical example of a seismic barrier along the fault

Beneficial and limiting factors in return to work after primary total knee replacement:Patients' perspective

Return to work (RTW) is an important outcome in Total Knee Arthroplasty (TKA). At present, 70-80%of TKA patients return to work within three to six months. What are patients' perspectives regarding beneficial and limiting factors in RTW after TKA? METHODS: Focus groups were formed in accordance with the Consolidated Criteria for Reporting Qualitative Research (COREQ) checklist. Three major topics were explored: 1. What was beneficial for RTW after TKA; 2. What was limiting for RTW after TKA; and 3. What additional care would benefit RTW after TKA? RESULTS: Data saturation was reached after four focus groups, comprising 17 participants - nine men and eight women (median age 58, range 52-65). The focus group study identified four main themes that contributed to a successful RTW namely rehabilitation (medical) like post-operative physical therapy, patient characteristics (personal), like motivation to RTW, occupational characteristics (work-related) like build-up in work tasks and medical support (medical) like availability of a walker or crutches. CONCLUSION: According to participants, factors within the following four themes can contribute to a successful return to work: occupational, patient, rehabilitation and medical care. Incorporating these factors into the integrated care pathway for the 'young' TKA patients may increase the chances of a successful RTW

Return-to-work intervention for cancer survivors: budget impact and allocation of costs and returns in the Netherlands and six major EU-countries

Background Return-to-work (RTW)-interventions support cancer survivors in resuming work, but come at additional healthcare costs. The objective of this study was to assess the budget impact of a RTW-intervention, consisting of counselling sessions with an occupational physician and an exercise-programme. The secondary objective was to explore how the costs of RTW-interventions and its financial revenues are allocated among the involved stakeholders in several EU-countries. Methods The budget impact (BI) of a RTW-intervention versus usual care was analysed yearly for 2015–2020 from a Dutch societal- and from the perspective of a large cancer centre. The allocation of the expected costs and financial benefits for each of the stakeholders involved was compared between the Netherlands, Belgium, England, France, Germany, Italy, and Sweden. Results The average intervention costs in this case were €1,519/patient. The BI for the Netherlands was €-14.7 m in 2015, rising to €-71.1 m in 2020, thus the intervention is cost-saving as the productivity benefits outweigh the intervention costs. For cancer centres the BI amounts to €293 k in 2015, increasing to €1.1 m in 2020. Across European countries, we observed differences regarding the extent to which stakeholders either invest or receive a share of the benefits from offering a RTW-intervention. Conclusion The RTW-intervention is cost-saving from a societal perspective. Yet, the total intervention costs are considerable and, in many European countries, mainly covered by care providers that are not sufficiently reimbursed

Explainable machine learning for labquake prediction using catalog-driven features

Recently, Machine learning (ML) has been widely utilized for laboratory earthquake (labquake) prediction using various types of data. This study pioneers in time to failure (TTF) prediction based on ML using acoustic emission (AE) records from three laboratory stick-slip experiments performed on Westerly granite samples with naturally fractured rough faults, more similar to the heterogeneous fault structures in the nature. 47 catalog-driven seismo-mechanical and statistical features are extracted introducing some new features based on focal mechanism. A regression voting ensemble of Long-Short Term Memory (LSTM) networks predicts TTF with a coefficient of determination (R2) of 70% on the test dataset. Feature importance analysis revealed that AE rate, correlation integral, event proximity, and focal mechanism-based features are the most important features for TTF prediction. Results reveal that the network uses all information among the features for prediction, including general trends in high correlated features as well as fine details about local variations and fault evolution involved in low correlated features. Therefore, some highly correlated and physically meaningful features may be considered less important for TTF prediction due to their correlation with other important features. Our study provides a ground for applying catalog-driven to constrain TTF of complex heterogeneous rough faults, which is capable to be developed for real application

The interpretation of change score of the pain disability index after vocational rehabilitation is baseline dependent

Background: The Pain Disability Index (PDI) is a widely-used instrument to measure pain-related disability. The aim of this study was to assess the responsiveness and interpretation of change score of the PDI in patients with chronic musculoskeletal pain (CMP) at discharge of vocational rehabilitation. Methods: Retrospective data of patients with CMP who attended vocational rehabilitation between 2014 and 2017 was used. The anchor-based method was used to assess the responsiveness of the total sample and of PDI baseline quartile groups. A receiver operating characteristic curve was performed, including Area Under the Curve (AUC) and Minimal Important Change (MIC). Results: The PDI showed responsive to detect clinically relevant changes in pain-related disability at discharge of vocational rehabilitation (AUC 0.79). A PDI change score of 13 points (MIC 12.5) can be considered as a real change in pain-related disability for the total study sample, and a PDI change score of 7-20 points can be considered as a real change in pain-related disability for PDI lowest and highest baseline quartile scores. Conclusion: The PDI is responsive in patients with CMP at discharge of vocational rehabilitation. The interpretation of change score depends on PDI baseline score. Patients with a PDI baseline score of ≤27 should decrease minimal 7 points, patients with a baseline score between 28 and 42 should decrease minimal 15 points, and patients with a baseline score ≥ 43 should decrease minimal 20 points

Off-fault damage and acoustic emission distributions during the evolution of structurally complex faults over series of stick-slip events

Variations in fault structure, for example, surface roughness and deformation zone width, influence the location and dynamics of large earthquakes as well as the distribution of small seismic events. In nature, changes in fault roughness and seismicity characteristics can rarely be studied simultaneously, so that little is known about their interaction and evolution. Here, we investigate the connection between fault structure and near-fault distributions of seismic events over series of stick-slip cycles in the laboratory. We conducted a set of experiments on rough faults that developed from incipient fracture surfaces. We monitored stress and seismic activity which occurred in the form of acoustic emissions (AEs). We determined AE density distributions as a function of fault normal distance based on high-accuracy hypocentre locations during subsequent interslip periods. The characteristics of these distributions were closely connected to different structural units of the faults, that is, the fault core, off-fault and background damage zone. The core deformation zone was characterized by consistently high seismic activity, whereas the off-fault damage zone displayed a power-law decay of seismic activity with increasing distance from the fault core. The exponents of the power-law-distributed off-fault activity increased with successive stick-slip events so that later interslip periods showed a more rapid spatial decay of seismic activity from the fault. The increase in exponents was strongest during the first one to three interslip periods and reached approximately constant values thereafter. The relatively rapid spatial decay of AE events during later interslip periods is likely an expression of decreasing fault zone complexity and roughness. Our results indicate a close relationship between fault structure, stress and seismic off-fault activity. A more extensive mapping of seismic off-fault activity-decay has the potential to significantly advance the understanding of fault zone properties including variations in fault roughness and stress