31 results on '"Jan A. Fischer"'
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2. Drawing blanks and winning: Quantifying global catastrophic risk associated with human ingenuity
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John-Oliver Engler and Jan Niklas Fischer
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Anthropic reasoning ,Existential risk ,Global catastrophic risk ,Human extinction ,Sustainability ,Vulnerable world hypothesis ,Environmental sciences ,GE1-350 ,Technology - Abstract
In his Vulnerable World Hypothesis Nick Bostrom recently compared invention to drawing balls out of a giant urn containing at least one black ball (i.e. an invention that would destroy civilization). If this hypothesis is correct, there is a need to assess the global catastrophic risk associated with human ingenuity. Here, drawing on the theory of zero-failure data, we develop two methods capable of addressing this question. The first method uses a Monte Carlo simulation approach, the second method focusses on analytical derivation of the survival function. Taking past global patenting activity as a proxy for human ingenuity, we draw on available patenting data and model different future scenarios for the annual number of technological inventions to provide upper boundaries (method 1) or point estimates (method 2) for the annual probability of pulling out a black ball for the next 1000 years. While there are clear limitations in terms of data and the urn model's conceptual framing, both methods successfully enable first approximations of global catastrophic risk associated with human ingenuity.
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- 2024
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3. Patients’ perspectives on prescription cannabinoid therapies: a cross-sectional, exploratory, anonymous, one-time web-based survey among German patients
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Jan Moritz Fischer, Farid I. Kandil, Ekaterina Katsarova, Laura Sophie Zager, Michael Jeitler, Felix Kugler, Franziska Fitzner, Vijayendra Murthy, Etienne Hanslian, Christoph Wendelmuth, Andreas Michalsen, Matthias Karst, and Christian S. Kessler
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cannabinoids ,cannabis ,survey ,Germany ,patients’ perspective ,pain ,Medicine (General) ,R5-920 - Abstract
IntroductionSince cannabinoids were partially legalized as prescription medicines in Germany in 2017, they are mostly used when conventional therapies do not suffice. Ambiguities remain regarding use, benefits and risks. This web-based survey explored the perspectives of patients whose experiences are not well enough known to date.MethodsIn an anonymous, exploratory, cross-sectional, one-time web-based observational study, participants receiving cannabinoid therapy on prescription documented aspects of their medical history, diagnoses, attitudes toward cannabinoids, physical symptoms, and emotional states. Participants completed the questionnaires twice here: first regarding the time of the survey and then, retrospectively, for the time before their cannabinoid therapy. Participants were recruited in a stratified manner in three German federal states.ResultsN = 216 participants (48.1% female, aged 51.8 ± 14.0) completed the survey, most of which (72%, n = 155) reported pain as their main reason for cannabinoid therapy. When comparing the current state with the retrospectively assessed state, participants reported greater satisfaction with their overall medical therapy (TSQM II: +47.9 ± 36.5, p
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- 2023
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4. A Measurement System for Distributed UWB-based Ranging and Localization in Snow Avalanches.
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Jonas Kuß, Anselm Köhler, Michael Neuhauser, Jan-Thomas Fischer, Rene Neurauter, Johannes Gerstmayr, and Falko Dressler
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- 2023
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5. GIWAXS Characterization of Metal–Organic Framework Thin Films and Heterostructures: Quantifying Structure and Orientation
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Jan C. Fischer, Chun Li, Sebastian Hamer, Lars Heinke, Rainer Herges, Bryce S. Richards, and Ian A. Howard
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crystallite orientation ,depth‐profiling ,GIWAXS ,heterostructures ,oriented metal–organic framework thin films ,Physics ,QC1-999 ,Technology - Abstract
Abstract For optoelectronic applications of metal–organic framework (MOF) thin films, it is important to be able to fabricate films and heterostructures that are highly oriented relative to the substrate's surface normal. However, process optimization to achieve this is difficult without sufficiently detailed structural characterization of the deposited films. It is demonstrated that 2D grazing‐incidence wide‐angle X‐ray scattering (GIWAXS) data from a laboratory system go a long way to providing such characterization and can 1) better test structural models than 1D scans, 2) provide a quantitative estimate—useful for process optimization—of the fraction of the deposited film that has the desired surface‐oriented texture (2D powder), and 3) deliver such information as a function of depth into the film—useful for heterostructure characterization. Herein, GIWAXS data collection and analysis are introduced in the context of understanding MOF thin films, then it is shown how the desired oriented fraction (2D powder fraction) of UiO‐66 fabricated by vapor‐assisted conversion can be increased from 4% to over 95% by minimizing nucleation in solution. Finally, it is demonstrated that heterostructures of UiO‐66 and UiO‐67 can be grown wherein both layers are highly ordered (UiO‐66 83%, UiO‐67 >94%) once synthetic protocols are optimized.
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- 2023
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6. Patient Experiences With Prescription Cannabinoids in Germany: Protocol for a Mixed Methods, Exploratory, and Anonymous Web-Based Survey
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Jan Moritz Fischer, Farid-Ihab Kandil, Matthias Karst, Laura Sophie Zager, Michael Jeitler, Felix Kugler, Franziska Fitzner, Andreas Michalsen, and Christian S Kessler
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Medicine ,Computer applications to medicine. Medical informatics ,R858-859.7 - Abstract
BackgroundMedical cannabinoids are controversial. Their use is comparatively rare, but it is rising. Since 2017, cannabinoids can be prescribed in Germany for a broader range of indications. Patient surveys on these drugs are hampered by the stigmatization of cannabinoids and their (still) low prevalence in medical contexts. Against this background, patients’ willingness to provide information is limited. Moreover, it is logistically challenging to reach them with a survey. A thorough knowledge of currently ongoing therapies and their effects and side effects, however, is important for a more appropriate and effective use of cannabinoids in the future. ObjectiveThis study is an exploratory data collection using a representative sample. The main goal is to provide a detailed picture of the current use of medical cannabinoids in Germany. It is intended to identify subgroups that may benefit particularly well or poorly. MethodsWe are conducting a representative, anonymous, cross-sectional, one-time, web-based survey based on mixed methods in 3 German federal states. Health conditions under cannabinoid therapy and before are documented with validated, symptom-specific questionnaires. This allows an estimation of the effect sizes of these therapies. The selection of parameters and questionnaires was based on the results of independent qualitative interviews in advance. Representative samples of the hard-to-reach study population are obtained by cluster sampling via contracted physicians of the statutory health insurance companies. ResultsRecruitment was ongoing until the end of June 2022, with 256 enrolled participants. Validated questionnaires on pain, spasticity, anorexia or wasting, multiple sclerosis, nausea or vomiting, depression, and attention deficit hyperactivity disorder (ADHD) were selected. Symptom scores are being assessed for both current conditions under cannabinoid therapy and conditions prior to this therapy (in retrospect). Validated questionnaires are also used for treatment satisfaction and general quality of life. These are supplemented by existing diagnoses, a detailed medication history, any previous experiences with cannabis or illegal substances, experiences with the prescription process, and sociodemographic data. Based on the results of the previous qualitative interviews, questions were added regarding prior experience with relaxation methods and psychotherapy, personal opinions about cannabinoids, pre-existing or symptom-related psychological trauma, and different experiences with different cannabis-based therapies. ConclusionsThe exploratory mixed methods approach of this project is expected to provide valid and relevant data as a basis for future clinical research. The study design may be representative for a large proportion of outpatients treated with cannabinoids in the German federal states studied. It may have less bias toward social desirability and may provide valuable information in addition to existing studies. Due to the observational and cross-sectional nature of this study, various limitations apply. Causal relations cannot be drawn. Trial RegistrationGerman Clinical Trials Register DRKS00023344; https://drks.de/search/en/trial/DRKS00023344 International Registered Report Identifier (IRRID)DERR1-10.2196/38814
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- 2023
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7. Diversity of European habitat types is correlated with geography more than climate and human pressure
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Marco Cervellini, Michele Di Musciano, Piero Zannini, Simone Fattorini, Borja Jiménez‐Alfaro, Emiliano Agrillo, Fabio Attorre, Pierangela Angelini, Carl Beierkuhnlein, Laura Casella, Richard Field, Jan‐Christopher Fischer, Piero Genovesi, Samuel Hoffmann, Severin D. H. Irl, Juri Nascimbene, Duccio Rocchini, Manuel Steinbauer, Ole R. Vetaas, and Alessandro Chiarucci
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anthropogenic impact ,biodiversity conservation ,environmental predictors ,European habitat directive ,habitat richness ,terrain ruggedness index ,Ecology ,QH540-549.5 - Abstract
Abstract Habitat richness, that is, the diversity of ecosystem types, is a complex, spatially explicit aspect of biodiversity, which is affected by bioclimatic, geographic, and anthropogenic variables. The distribution of habitat types is a key component for understanding broad‐scale biodiversity and for developing conservation strategies. We used data on the distribution of European Union (EU) habitats to answer the following questions: (i) how do bioclimatic, geographic, and anthropogenic variables affect habitat richness? (ii) Which of those factors is the most important? (iii) How do interactions among these variables influence habitat richness and which combinations produce the strongest interactions? The distribution maps of 222 terrestrial habitat types as defined by the Natura 2000 network were used to calculate habitat richness for the 10 km × 10 km EU grid map. We then investigated how environmental variables affect habitat richness, using generalized linear models, generalized additive models, and boosted regression trees. The main factors associated with habitat richness were geographic variables, with negative relationships observed for both latitude and longitude, and a positive relationship for terrain ruggedness. Bioclimatic variables played a secondary role, with habitat richness increasing slightly with annual mean temperature and overall annual precipitation. We also found an interaction between anthropogenic variables, with the combination of increased landscape fragmentation and increased population density strongly decreasing habitat richness. This is the first attempt to disentangle spatial patterns of habitat richness at the continental scale, as a key tool for protecting biodiversity. The number of European habitats is related to geography more than climate and human pressure, reflecting a major component of biogeographical patterns similar to the drivers observed at the species level. The interaction between anthropogenic variables highlights the need for coordinated, continental‐scale management plans for biodiversity conservation.
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- 2021
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8. To eat or not to eat—an exploratory randomized controlled trial on fasting and plant-based diet in rheumatoid arthritis (NutriFast-Study)
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Anika M. Hartmann, Melanie Dell'Oro, Michaela Spoo, Jan Moritz Fischer, Nico Steckhan, Michael Jeitler, Thomas Häupl, Farid I. Kandil, Andreas Michalsen, Daniela A. Koppold-Liebscher, and Christian S. Kessler
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rheumatoid arthritis ,fasting ,caloric restriction ,plant-based diet ,inflammation ,Nutrition. Foods and food supply ,TX341-641 - Abstract
BackgroundFasting is beneficial in many diseases, including rheumatoid arthritis (RA), with lasting effects for up to 1 year. However, existing data dates back several decades before the introduction of modern therapeutic modalities.ObjectiveThis exploratory RCT compares the effects of a 7-day fast followed by a plant-based diet (PBD) to the effects of the dietary recommendations of the German society for nutrition (Deutsche Gesellschaft für Ernährung, DGE) on RA disease activity, cardiovascular (CV) risk factors, and well-being.MethodsIn this RCT we randomly assigned 53 RA patients to either a 7-day fast followed by an 11-week PBD or a 12-week standard DGE diet. The primary endpoint was the group change from baseline to 12 weeks on the Health Assessment Questionnaire Disability Index (HAQ-DI). Further outcomes included other disease activity scores, body composition, and quality of life.ResultsOf 53 RA patients enrolled, 50 participants (25 per group) completed the trial and were included into the per-protocol analysis. The primary endpoint was not statistically significant. However, HAQ-DI improved rapidly in the fasting group by day 7 and remained stable over 12 weeks (Δ-0.29, p = 0.001), while the DGE group improved later at 6 and 12 weeks (Δ-0.23, p = 0.032). DAS28 ameliorated in both groups by week 12 (Δ-0.97, p < 0.001 and Δ-1.14, p < 0.001; respectively), with 9 patients in the fasting but only 3 in the DGE group achieving ACR50 or higher. CV risk factors including weight improved stronger in the fasting group than in the DGE group (Δ-3.9 kg, p < 0.001 and Δ-0.7 kg, p = 0.146).ConclusionsCompared with a guideline-based anti-inflammatory diet, fasting followed by a plant-based diet showed no benefit in terms of function and disability after 12 weeks. Both dietary approaches had a positive effect on RA disease activity and cardiovascular risk factors in patients with RA.Clinical trial registrationhttps://clinicaltrials.gov/ct2/show/NCT03856190, identifier: NCT03856190.
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- 2022
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9. Medical Cannabinoids as Treatment for Hypophosphatasia-Related Symptoms
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Jan Moritz Fischer, Michael Jeitler, Sarah B. Blakeslee, and Christian Kessler
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Complementary and alternative medicine - Abstract
Background: Hypophosphatasia (HPP) is a rare congenital disease caused by a mutation affecting tissue nonspecific alkaline phosphatase, an enzyme involved in phosphate metabolism. The clinical manifestation usually includes bone mineralization disorders, neurological symptoms, and persistent muscle pain. Case Report: This case involves a woman in her sixties of Central European descent who suffers from lifelong chronic pain and muscle weakness due to HPP and concomitant degenerative changes of the lumbar spine. The patient is physically impaired and limited in her ability to walk as a result. HPP-specific and guideline-based multimodal pain management including enzyme replacement therapy with asfotase alfa, opioids, invasive orthopedic and neurosurgical procedures, long-term physiotherapy, and psychotherapy did not yield sufficient treatment results. The average pain was given as 8.5 on a numerical rating scale (NRS, 0–10) for the last 3 years. Treatment with a cannabidiol-predominant, full-spectrum, prescription cannabis extract led to a clinically meaningful pain reduction to 2.5/10 NRS, a discontinuation of opioids, and a recent resumption of employment as a physician. Conclusion: A more widespread consideration of medical cannabinoids in the treatment of complex chronic pain is proposed. Cannabinoids may pose a particularly potent treatment option for HPP-related symptoms and inflammation due to their known anti-inflammatory properties.
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- 2022
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10. Effects of Prolonged Fasting during Inpatient Multimodal Treatment on Pain and Functional Parameters in Knee and Hip Osteoarthritis: A Prospective Exploratory Observational Study
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Kessler, Daniela A. Koppold, Farid I. Kandil, Oliver Güttler, Anna Müller, Nico Steckhan, Sara Meiß, Carolin Breinlinger, Esther Nelle, Anika M. Hartmann, Michael Jeitler, Etienne Hanslian, Jan Moritz Fischer, Andreas Michalsen, and Christian S.
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fasting ,caloric restriction ,osteoarthritis ,dietary intervention ,fasting-mimicking diet ,integrative medicine ,complementary medicine ,traditional European medicine ,nutrition ,multimodal integrative treatment - Abstract
Preliminary clinical data suggest that pain reduction through fasting may be effective for different diagnoses. This uncontrolled observational clinical study examined the effects of prolonged modified fasting on pain and functional parameters in hip and knee osteoarthritis. Patients admitted to the inpatient department of Internal Medicine and Nature-based Therapies of the Immanuel Hospital Berlin between February 2018 and December 2020 answered questionnaires at the beginning and end of inpatient treatment, as well as at 3, 6, and 12 months after discharge. Additionally, selected blood and anthropometric parameters, as well as subjective pain ratings, were routinely assessed during the inpatient stay. Fasting was the only common intervention for all patients, being performed as part of a multimodal integrative treatment program, with a daily caloric intake of
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- 2023
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11. The biome inventory – Standardizing global biogeographical land units
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Jan‐Christopher Fischer, Anna Walentowitz, Carl Beierkuhnlein, and Thomas Gillespie
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Global and Planetary Change ,Ecology ,Ecology, Evolution, Behavior and Systematics - Published
- 2022
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12. Analysis of snow avalanche simulation results in a thalweg-following coordinate system
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Oscar Dick, Matthias Tonnel, Anna Wirbel, Felix Oesterle, Jan-Thomas Fischer, and Michael Neuhauser
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The thickness integrated dense flow avalanche simulation module com1DFA of the open source framework AvaFrame is used for snow avalanche simulations with application in hazard mapping for different mountainous areas. In order to further increase the information value gained from the avalanche simulation results in a global coordinate system, we introduce a thalweg following coordinate system. It allows us to quantitatively compare simulation scenarios and results of different modelling approaches in a new way. It helps to bridge the gap between the modules operating in three-dimensional terrain (com1DFA) versus two-dimensional along the avalanche path, such as the well-known alpha-beta model implemented in module com2AB. One essential step of the analysis procedures (analysis modules in AvaFrame) is the avalanche thalweg generation itself. The thalweg depends on the main flow direction, a property of the avalanche event which is strongly influenced by the terrain the avalanche flow will encounter. So far, the main flow direction is usually derived from observations or avalanche simulations, and the thalweg is generated manually. However, the reproducibility of this method raises an issue, and manually identifying the avalanche thalweg for every slope is unnecessarily time-consuming. In this work, we use com1DFA simulations in three dimensional terrain. We automatically generate the two-dimensional avalanche thalweg by extracting the centre of mass coordinates at every time step. Projecting the simulation results into this thalweg following coordinate system, we can derive the position of the avalanche front and the local travel angles, from which scalar measures like runout length and runout angle are determined. We combine temporal and spatial information by introducing the thalweg-time and thalweg-altitude diagrams. These offer a different perspective on the simulation results and, at a glance, provide information on the evolution of spatio-temporal flow variables (thickness, velocity) along the avalanche thalweg in a single plot. Additionally, by using a numerical particle-grid method, we can evaluate simulation outputs at a particle level and relate them to the whole avalanche flow. Another advantage of the analysis tools operating in the thalweg coordinate system is the possibility to compare simulation results with field measurements. For example, we present in-flow particle sensors trajectories and corresponding velocities recorded during field experiments to evaluate com1DFA simulation results and thereby help to improve the dense flow module. For different avalanche simulations, we show how these analysis modules provide a new way to summarize the complex spatio-temporal flow variables evolution in three dimensional terrain in a more intuitive two dimensional illustration along the automatically generated thalweg.
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- 2023
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13. Effects of Prolonged Fasting During Inpatient Multimodal Treatment on Pain and Functional Parameters in Knee and Hip Osteoarthritis: A Prospective Exploratory Observational Study
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Daniela Artemis Koppold, Farid I. Kandil, Oliver Güttler, Anna Müller, Nico Steckhan, Sara Meiß, Carolin Breinlinger, Esther Nelle, Anika M. Hartmann, Michael Jeitler, Etienne Hanslian, Jan Moritz Fischer, Andreas Michalsen, and Christian S. Kessler
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Preliminary clinical data suggest pain reduction through fasting in different diagnoses. This uncontrolled observational clinical study examined the effects of prolonged modified fasting on pain and functional parameters in hip and knee osteoarthritis. Patients admitted to the inpatient department of Internal Medicine and Nature-based Therapies of the Immanuel Hospital Berlin between February 2018 and March 2020, answered questionnaires at the beginning and end of inpatient treatment, as well as 3, 6 and 12 months after discharge. Additionally, selected blood and anthropometric parameters were routinely assessed during the inpatient stay. Fasting was performed as part of a multimodal integrative treatment program, with daily caloric intake of
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- 2023
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14. Avaframe com1DFA (version 1.3): a thickness integrated computational avalanche module – Theory, numerics and testing
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Matthias Tonnel, Anna Wirbel, Felix Oesterle, and Jan-Thomas Fischer
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Simulation tools are important to investigate and predict mobility and the destructive potential of gravitational mass flows (e.g. snow avalanches). AvaFrame – the open avalanche framework – offers well established computational modeling approaches, tools for data handling and analysis as well as ready to use modules for evaluation and testing. This paper presents the theoretical background, derivation and model verification for one of AvaFrame’s core modules, the thickness integrated computational model for dense flow avalanches, named com1DFA. Particular emphasis within the description of the utilized numerical particle grid method is given to the computation of spatial gradients and the accurate implementation of driving and resisting forces. The implemented method allows to provide a time-space criterion connecting the numerical particles, grid and time discretization. The convergence and robustness of the numerical implementation is checked with respect to the spatio-temporal evolution of the flow variables using tests with a known analytical solution. In addition we present a new test for verifying the accuracy of the numerical simulation in terms of runout (angle and distance). This test is derived from the total energy balance along the center of mass path of the avalanche. This manuscript, particularly in combination with the code availability (open-source code repository) and detailed online documentation provides a description of an extendable framework for modeling and verification of avalanche simulation tools.
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- 2023
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15. Global biomes and ecozones – Conceptual and spatial communalities and discrepancies
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Carl Beierkuhnlein and Jan-Christopher Fischer
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Ecology ,Geography, Planning and Development ,General Earth and Planetary Sciences - Abstract
Various facets of global changes and related problems and challenges are asking for sound impact assessments and corresponding coping strategies. The human impact on nature is a major driver of biodiversity loss and restricted ecosystem functioning and services. Assessing such global changes is often done by using biomes as benchmarks. However, even if the wording and terminology seem common sense (‘tropical rain forest’, ‘steppe’, ‘boreal forest’) global biome units and maps deviate in many ways. This is well justified by their individual intention, expert opinions, disciplinary background, and methodology of creation. A closer look reveals linkages between spatial accordance and common origin in climate classifications and maps. Their original influence, however, is rarely evident. In consequence, it is difficult if not impossible for users to realize and understand differences in these global maps. Furthermore, it is difficult to accept the fact that there is no common standard for global biomes. Even more surprising is the fact that some approaches are uncritically taken for common sense and are perpetuated over decades. This study aims to review established global biome concepts. Regions that are consistently assigned to comparable types of biomes shall be detected and also regions where ambiguity exists. For this purpose, we shortly review the history of existing concepts and the generic relations between them. Biomes, ecozones and climate classifications are considered. We digitized the most prominent biome classifications. Spatial match and mismatch between concepts were analyzed globally. We detect areas of spatial agreement and regions with ambiguous classifications. A clustering approach including 287 individual biomes originating from 12 established global biome concepts and their classifications/units revealed 12 terrestrial biome clusters among which 8 can be assigned to terrestrial ecological units. One cluster on ice caps adds to this. And finally, 3 clusters represent rather transition zones (ecotones), high mountain plateaus or are of minor areal extent. The spatial arrangement of these emerging clusters is displayed on a global map. Additionally, regions of uncertainty related to class assignment were identified. Those primarily occur in the vicinity of mountainous regions. The findings of this study should be seen as a work in progress and as a basis for further optimization of global biome concepts.
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- 2021
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16. Stress Reduction by Yoga versus Mindfulness Training in Adults Suffering from Distress: A Three-Armed Randomized Controlled Trial including Qualitative Interviews (RELAX Study)
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Jeitler, Jan Moritz Fischer, Farid-Ihab Kandil, Christian S. Kessler, Lucas Nayeri, Laura Sophie Zager, Theresa Rocabado Hennhöfer, Nico Steckhan, Daniela A. Koppold-Liebscher, Holger C. Bringmann, Thomas Schäfer, Andreas Michalsen, and Michael
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yoga ,iyengar yoga ,mindfulness ,meditation ,stress reduction ,mixed methods - Abstract
Distress is a growing public health concern. In this three-armed randomized controlled trial, n = 102 adults with elevated stress levels and stress-related symptoms were randomly assigned to (1) “integrative” yoga classes which combined physical exercises, mindfulness training, and ethical/philosophical aspects of traditional yoga; to (2) Iyengar yoga classes which entailed primarily physical exercises; or to (3) mindfulness training without physical training. We hypothesized the synergistic effects of physical yoga exercises, mindfulness, and ethical/philosophical aspects. The primary outcome was the group difference on Cohen’s Perceived Stress Scale (PSS) after 12 weeks. Secondary outcomes included burnout, quality of life, physical complaints, depression, anxiety, mindfulness, interoceptive awareness, self-regulation, spirituality, mysticism, and posttraumatic stress. All outcomes were evaluated at baseline (V0), after 12 weeks (V1), and after 24 weeks (V2). A subset of participants took part in qualitative interviews. A lasting and clinically relevant stress reduction was observed within all groups (PSS ΔV0–V1Integrative Yoga = −6.69 ± 6.19; ΔV0–V1Iyengar Yoga = −6.00 ± 7.37; ΔV0–V1Mindfulness = −9.74 ± 7.80; all p < 0.00). Effect sizes were also statistically large at the end of the follow-up period (Cohen’s d Integrative Yoga = 1.41; d Iyengar Yoga = 1.37; d Mindfulness = 1.23). There were no significant group differences or evidence of relevant synergistic effects from combining mindfulness and physical yoga exercises. All three interventions were found to be equally effective methods of stress reduction. Their use in practice should be based on availability and patient preference.
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- 2022
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17. Simplicity vs. complexity – a long-standing challenge in the simulation of landslide runout
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Jan-Thomas Fischer and Martin Mergili
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First approaches to analyze the propagation of hazardous, extremely rapid, landslides go back at least to the 1930s, when data-driven approaches such as angles of reach were used to estimate runout distances. Various much more sophisticated tools for the simulation of flow-type landsides including debris flows or rock avalanches, or cascading effects involving more than one type of phenomenon, have been developed since then, particularly throughout the last two decades. They build on increasingly complex physical-mathematical models, starting from comparatively simple and straightforward, depth-averaged Voellmy-type mixture models, moving to still depth-averaged two- and three-phase models able to simulate the interaction of landslides with water bodies, and currently proceeding to highly complex and highly flexible full 3D models. Phenomena such as erosion, entrainment, deposition, phase separation, or non-hydrostatic effects are increasingly well understood and incorporated into operational mass flow simulation tools.However, this trend of increasing model complexity, supported by increasing physical process understanding and enhanced computational capacities, is not necessarily in line with the demand by natural hazard practitioners, who need capable but easy-to-handle simulation tools for their work. Besides the computational costs, it is mainly the multitude of often unknown, rather conceptual model parameters representing a barrier for practitioners towards using the more or even the most advanced approaches. Further, more complex models do not necessarily provide more accurate results than simpler ones, this always depends on the scope, purpose, and phenomenon. If only estimates of runout distances or impact areas are needed, very simple data-driven models may do the work. Even when it comes to flow thicknesses, velocities, or impact pressures, ordinary debris flows may still be better represented by comparatively simple mixture models than by parameter-hungry two- or three-phase models. Yet, more complex models are needed for more complex processes such as landslide-lake interactions or other types of process chains with dynamically changing material composition. Therefore, intelligent approaches have to be found to find an appropriate balance between simplicity and complexity.Mainly based on seven years of experience with the depth-averaged multi-phase mass flow simulation framework r.avaflow, we will discuss the main challenges and ideas to find a useful balance between simplicity and complexity in the simulation of landslide runout.
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- 2022
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18. Laminar wing design: A framework for transition delay using linear stability theory and adjoint optimization
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Jan-Sören Fischer, Venner, Cornelis H., van der Weide, Edwin Theodorus Antonius, and Engineering Fluid Dynamics
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Physics::Fluid Dynamics - Abstract
With the aim to achieve long-term sustainability of the growing aviation sector, a significant amount of research and development is invested in improving the efficiency of future airframe architectures. This requires advancements in all engineering disciplines, from lightweight materials to beyond state-of-the-art aerodynamic technologies. In light of these developments, a key technology concerned with the reduction of airframe drag has been identified: The extension of the laminar flow regime around aircraft surfaces offers large potential for friction drag reduction. The objective of this work therefore is to advance the current analysis and design capabilities to include the effect of laminar-turbulent transition. The goal is to build a framework for laminar wing design based on the extension of Natural Laminar Flow (NLF) and developed from existing first principle methods. First, a literature survey on laminar wing design has been conducted. Information on the physics of laminar-turbulent transition includes the effect of transition on the aircraft level and the different paths to transition in the considered flows. Additionally, different methods for transition prediction in combination with a Reynolds-Averaged Navier-Stokes (RANS) solver are discussed. Finally, optimization methods for the delay of laminar-turbulent transition are summarized. Second, a RANS solver is coupled to a Linear Stability Theory (LST) solver to include a prediction capability for laminar-turbulent transition in the flow simulations. The instabilities taken into account using this approach are of the Tollmien-Schlichting (TS) and the cross-flow (CF) type. A critical amplification factor curve for CF and TS instabilities is used to determine the onset of transition. The boundary layer data used in the LST analyses is directly obtained from the RANS solution. Transition is imposed onto the flow using an intermittency function controlling the applied eddy viscosity predicted by the turbulence model. Third, the implemented coupling is validated by reproducing the results of a variety of significant experimental test cases. These are TU Braunschweig's Sickle Wing, NASA's NLF version of the Common Research Model (CRM-NLF), and the NLF(1)-0416 airfoil. This covers a wide range of test conditions in the sub- and transonic flow regime, featuring separation-induced as well as TS and CF dominated transition for varying levels of geometric complexity. The comparison of numerical and experimental results shows that the methodology is capable to accurately predict transition for a wide range of flow regimes under industrial interest. Furthermore, the results reveal interesting information on the transition mechanisms on three-dimensional wings. Finally, the continuous adjoint formulation for the employed RANS solver was extended by a flow-matching functional. The aim is to drive the geometry to a shape that satisfies a specified target flow field that will reduce the amplification rates of the instabilities. By means of the sensitivities of the transition location predicted by the LST solver with respect to the flow field variables, a target flow is defined. It is shown that using this approach, the amplification rates for an airfoil can be reduced. It is ultimately proposed to use this approach to optimize profiles and wings with extended laminar flow.
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- 2022
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19. Zehn Jahre Mehrbedarf dezentrale Warmwassererzeugung
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Jan Henrik Fischer
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- 2022
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20. Patient Experiences With Prescription Cannabinoids in Germany: Protocol for a Mixed Methods, Exploratory, and Anonymous Web-Based Survey (Preprint)
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Jan Moritz Fischer, Farid-Ihab Kandil, Matthias Karst, Laura Sophie Zager, Michael Jeitler, Felix Kugler, Franziska Fitzner, Andreas Michalsen, and Christian S Kessler
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BACKGROUND Medical cannabinoids are controversial. Their use is comparatively rare, but it is rising. Since 2017, cannabinoids can be prescribed in Germany for a broader range of indications. Patient surveys on these drugs are hampered by the stigmatization of cannabinoids and their (still) low prevalence in medical contexts. Against this background, patients’ willingness to provide information is limited. Moreover, it is logistically challenging to reach them with a survey. A thorough knowledge of currently ongoing therapies and their effects and side effects, however, is important for a more appropriate and effective use of cannabinoids in the future. OBJECTIVE This study is an exploratory data collection using a representative sample. The main goal is to provide a detailed picture of the current use of medical cannabinoids in Germany. It is intended to identify subgroups that may benefit particularly well or poorly. METHODS We are conducting a representative, anonymous, cross-sectional, one-time, web-based survey based on mixed methods in 3 German federal states. Health conditions under cannabinoid therapy and before are documented with validated, symptom-specific questionnaires. This allows an estimation of the effect sizes of these therapies. The selection of parameters and questionnaires was based on the results of independent qualitative interviews in advance. Representative samples of the hard-to-reach study population are obtained by cluster sampling via contracted physicians of the statutory health insurance companies. RESULTS Recruitment was ongoing until the end of June 2022, with 256 enrolled participants. Validated questionnaires on pain, spasticity, anorexia or wasting, multiple sclerosis, nausea or vomiting, depression, and attention deficit hyperactivity disorder (ADHD) were selected. Symptom scores are being assessed for both current conditions under cannabinoid therapy and conditions prior to this therapy (in retrospect). Validated questionnaires are also used for treatment satisfaction and general quality of life. These are supplemented by existing diagnoses, a detailed medication history, any previous experiences with cannabis or illegal substances, experiences with the prescription process, and sociodemographic data. Based on the results of the previous qualitative interviews, questions were added regarding prior experience with relaxation methods and psychotherapy, personal opinions about cannabinoids, pre-existing or symptom-related psychological trauma, and different experiences with different cannabis-based therapies. CONCLUSIONS The exploratory mixed methods approach of this project is expected to provide valid and relevant data as a basis for future clinical research. The study design may be representative for a large proportion of outpatients treated with cannabinoids in the German federal states studied. It may have less bias toward social desirability and may provide valuable information in addition to existing studies. Due to the observational and cross-sectional nature of this study, various limitations apply. Causal relations cannot be drawn. CLINICALTRIAL German Clinical Trials Register DRKS00023344; https://drks.de/search/en/trial/DRKS00023344 INTERNATIONAL REGISTERED REPORT DERR1-10.2196/38814
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- 2022
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21. Are avalanche models correct? An uncertain view on convergence
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Matthias Tonnel, Anna Wirbel, Felix Oesterle, and Jan-Thomas Fischer
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At the core of many avalanche simulation tools, numerical kernels are utilized to solve flow model equations. Aside from trying to fit the models as best as possible to the current understanding of actual flow mechanisms, these kernels have to fulfill general mathematical requirements, such as convergence, stability and consistency. The precision of numerical solutions is limited and needs to be determined by appropriate uncertainty quantification approaches. It is also necessary to assess the impact of input variability propagating through the numerical kernel.To allow kernel testing and uncertainty quantification, the AvaFrame framework provides a suite of test cases as well as analysis tools. This includes tests with known solutions usable to determine the kernel errors (ana1Tests) and idealized/real world topographies to estimate effects of varying simulation setups. By changing numerical settings, flow model setup or input data it is possible to show their effects on simulation results in a quantitative manner. It therefore allows us to relate input variations to the uncertainty in simulation results. Error and uncertainty quantification is done using modules for computing statistical measures (ana4Stats), indicators along an avalanche path (ana3AIMEC) and various visualization routines.We showcase this for our com1DFA dynamical dense flow avalanche (DFA) module. The kernel of com1DFA is based on depth integrated governing equations (shallow water) and solved numerically using the smoothed particle hydrodynamics (SPH) method. Applying our analysis tools, we evaluate the convergence of the DFA kernel with regard to the numerical parameters time step, SPH kernel size and particles size. We investigate the accuracy and precision of the numerical solution using the similarity solution test, a test with a semi-analytic solution for depth integrated equations. It allows us to establish a suitable relation between time step, SPH kernel size and particles size for the com1DFA kernel.Using the same approach for an avalanche setup, we can also vary selected input parameters like friction coefficients and/or release thickness and quantify the resulting uncertainties on simulation results, e.g. runout and peak flow variables.
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- 2022
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22. An in-flow sensor system for data acquisition in snow avalanches
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Rene Neurauter, Michael Neuhauser, Johannes Blobel, Robert Winkler, Falko Dressler, Jan-Thomas Fischer, and Johannes Gerstmayr
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The dynamics of snow avalanches and in particular their rheology is of big importance to develop improved avalanche models and thus increase safety in mountainous areas. Existing measurement systems only allow a limited in situ view of the dynamics of snow avalanches and therefore demand the development of innovative measurement systems. Furthermore, due to the limited measurement capability of existing systems, comprehensible motion reconstruction is currently not possible. Therefore, the aim of this work is to present a measurement system that enables accurate in flow observations of snow avalanches and has the mechanical properties of a typical snow granule. A main objective of the measurement system is to allow a full motion reconstruction regarding translations and rotations with a high sampling rate and without exceeding sensor ranges.The newly developed system, denoted as AvaNode, has the shape of a concave cube with a variable density to fit typical snow granules in flowing avalanches and their deposits. The AvaNode contains a strapdown inertial navigation sensor capable of measuring accelerations, angular velocities, and magnetic flux densities with up to 400Hz and allows for an estimation of the orientations, velocities, and positions of the AvaNode using state of the art motion reconstruction algorithms. The reconstruction is significantly improved due to precise calibration of all sensors using reference measurements with a 6R robot and onsite magnetic field calibration. In order to get a refined motion trajectory, the AvaNodes are also equipped with radio ranging modules. These modules allow performing time of flight (TOF) measurements, determining the distance between several nodes. A Global Navigation Satellite System (GNSS) module determines longitude, latitude, and altitude, as well as world time, however, with low frequency resolution and larger errors due to snow coverage. To measure the temperature evolution in avalanches, an infrared temperature sensor is attached. Multiple recovery systems like Recco rescue reflector (passive), Pieps TX600 (active), and Lambda4 Smilla (active) are integrated to allow fast retrieval of the sensors.As first results, we present the employed sensor calibration approaches for the inertial navigation with corresponding laboratory data signatures. The sensor calibration allows in-depth analysis of motion data, identifying typical data signatures observed in avalanches. Furthermore, we show first data acquired from in-flow snow avalanche measurements, which prove the functionality of the system and allow the first insights into trajectories of snow granules, regarding accelerations, angular velocities, rotations, and position.
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- 2022
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23. Modelling forest effects on snow avalanche runout with the Flow-Py simulation tool
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Christopher D'Amboise, Michael Neuhauser, Anne Hormes, Matthias Ploerer, Jan-Thomas Fischer, and Michaela Teich
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Forests cover large parts of mountain areas. It is therefore necessary to include their effects in simulations at the regional scale to understand the key role forests have for risk mitigation. Process-based physical models can be used for such simulations, but they often require larger computational resources than statistical models. Flow-Py is a customizable, open-source simulation tool to predict the runout and intensity of gravitational mass flows (GMF). Flow-Py is based on data-driven empirical modeling ideas with automated path identification to solve the routing and stopping of GMFs in three-dimensional terrain, requiring fewer parameters than physical GMF runout models. Here we present the custom-built forest plug-in to the Flow-Py simulation tool which accounts for forest effects in the transit and runout zones of snow avalanches. Flow-Py employs the well-known runout angle (α) concept to determine the stopping of a GMF, and routing algorithm consisting of a terrain contribution and persistence contribution. The interaction between forest and avalanches, which can reduce their runout and decrease their intensity can be broken down into two main processes, 1) adding friction and 2) reducing flowing mass or the detrainment of snow. The forest plug-in has the capability to mimic these physical interactions by increasing the runout angle and adjusting the routing flux in forested areas. We present the framework of the forest plug-in for a test case and the results of a sensitivity study on parameters controlling the forest-avalanche interaction. The forest plug-in requires the spatial extent of the forest and an estimate of the kinetic energy of the avalanche to compute the forest’s effect on the avalanche movement. Additional information on the structure of the forest (e.g., forest type, stem density, canopy cover, basal area) can be used to amplify or dampen these effects. The forest information is summarized in the forest structure index (FSI), which indicates how developed a forest is with regards to its optimal protective effect against snow avalanches and ranges between 0 (no protection) and 1 (optimal protection), considering, e.g., dominant forest type, elevation band, or the forest development stage. Forests located in the starting zones of avalanches have long been used as an efficient mitigation measure to reduce avalanche risk. However, forests located in the transit and runout zones of avalanches also have mitigating properties, but the degree of protection is difficult to quantify without simulation tools and their integrated models. Including forest-avalanche interactions in regional-scale simulations with Flow-Py and its forest plug-in allows to estimate the degree to which forest protects human activity and infrastructure against potential avalanches. That is, by combining simulation results with and without forest it is possible to estimate the forest impact, i.e., how much the forest reduces the magnitude (runout and intensity) of the avalanche. Such regional overviews can be calculated fast with large-scale input data, which is important to, e.g., quantify changes in the protective effect of a forest area caused by disturbance agents such as wind, bark beetles or fire.
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- 2022
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24. Investigating the potential of GNSS-modules for inflow avalanche measurements
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Michael Neuhauser, Rene Neurauter, Steffen Tuermer, Johannes Gerstmayr, Marc Adams, Anselm Koehler, and Jan-Thomas Fischer
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A detailed knowledge of avalanche dynamics is crucial to optimize flow models that allow avalanche simulation tools to be effectively used for dimensioning mitigation measures or identifying endangered terrain. There are different ways to observe the dynamics in an avalanche during the flow. It can be achieved with remote sensing approaches or fixed sensor systems that interact with the flow. In this Abstract we introduce an inflow sensor system, the so called AvaNodes that are equipped with a variety of sensors, investigating the potential of Global Navigation Satellite System (GNSS) modules.The AvaNode is a cube with 16 cm side length. It is designed to flow in the avalanche and obtain GNSS position and velocity, inertial measurement unit (IMU) based accelerations, angular velocities and the magnetic flux densities, and temperature by means of an infrared thermometer.The utilized GNSS modules are from the ublox CAM-M8 series, that have a position accuracy of 2 m and velocity accuracy of 0.05 m/s, according to the datasheet.To estimate the position accuracy of the AvaNode while covered with snow, experiments were performed with the AvaNode buried in snow at different depths at a known location. Results show that the position accuracy is highly dependent on the number of satellites that the module currently tracks, ranging between 2 and 10 meters. To estimate the GNSS velocity accuracy while the AvaNode is covered with snow, a dynamic experiment with moving sensors was performed. The AvaNode was transported on a sledge while it was buried in 10 and 20 cm of snow. An accuracy in the range of 0.5 m/s was observed, allowing to potentially investigate the dynamics in real avalanches. The influence of burial or snow cover depth did not show conclusive influence on the results and requires further investigation. In 2021 this inflow sensor system was used in two avalanche experiments, on March 15 and 16, obtaining start and end positions, as well as promising GNSS velocities. On March 15 one AvaNode was transported by an avalanche, where the GNSS velocity shows a maximum of 15 m/s and a duration of 50 seconds of the avalanche. On March 16 two AvaNodes were picked up by an avalanche, both showing similar velocity distributions, with a maximum velocity of 17 and 13 m/s.
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- 2022
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25. Simulation of slow geomorphic flows with r.avaflow
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Martin Mergili, Andreas Kellerer-Pirklbauer-Eulenstein, Christian Bauer, and Jan-Thomas Fischer
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GIS-based open-source simulation tools for extremely rapid mass flow processes such as snow avalanches, rock avalanches, or debris flows are readily available, covering a broad range of complexity levels – e.g., from single-phase to multi-phase. However, these tools are not suitable for slower types of mass flows characterized by high viscosities. The conventionally used momentum balance equations for rapid flows often appear numerically unstable for high viscosities, leading to the immediate reversion of flow direction or stopping, without appropriate numerical treatment. GIS-based simulation efforts of slow geomorphic flows are reported in the literature, and open source tools are available for specific phenomena such as glaciers, but no comprehensive and readily usable simulation tools have been proposed yet.We present a simple depth-averaged model implementation for the simulation of slow geomorphic flows, including glaciers, rock glaciers, highly viscous lava flows, and those flow-type landslides not classified as extremely or very rapid. Thereby, we use an equilibrium-of-motion concept. For each time step, flow momentum and velocity are computed as the equilibrium between accelerating gravitational forces and decelerating viscous forces, also including a simple law for basal sliding. Momentum balances are not carried over from one time step to the next, meaning that inertial forces, which are not important for slow-moving mass flows, are neglected. Whereas these basic principles are applied to all relevant processes, there is flexibility with regard to the details of model formulation and parameterization: e.g., the well-established shallow-ice approximation can be used to simulate glacier flow.The model is implemented with the GRASS GIS-based open-source mass flow simulation framework r.avaflow and demonstrated on four case studies: an earth flow, the growth of a lava dome, a rock glacier, and a glacier (considering accumulation and ablation). All four processes were reproduced in a plausible way. However, parameterization remains a challenge due to spatio-temporal changes and temperature dependency of viscosity and basal sliding. Our model and its implementation open up new possibilities for climate change impact studies, natural hazard analysis, and environmental education.
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- 2022
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26. Neue Wege in der Pflege – Digitale Pflegeanwendungen
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Petra Knorr and Jan Henrik Fischer
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- 2022
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27. A neural network for tics: insights from causal brain lesions and deep brain stimulation
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Christos Ganos, Bassam Al-Fatly, Jan-Frederik Fischer, Juan-Carlos Baldermann, Christina Hennen, Veerle Visser-Vandewalle, Clemens Neudorfer, Davide Martino, Jing Li, Tim Bouwens, Linda Ackermanns, Albert F G Leentjens, Nadya Pyatigorskaya, Yulia Worbe, Michael D Fox, Andrea A Kühn, Andreas Horn, Neurochirurgie, MUMC+: MA AIOS Neurochirurgie (9), RS: MHeNs - R3 - Neuroscience, Psychiatrie & Neuropsychologie, MUMC+: MA Med Staf Spec Psychiatrie (9), and RS: MHeNs - R1 - Cognitive Neuropsychiatry and Clinical Neuroscience
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mental disorders ,Original Article ,Neurology (clinical) ,nervous system diseases - Abstract
Brain lesions are a rare cause of tic disorders. However, they can provide uniquely causal insights into tic pathophysiology and can also inform on possible neuromodulatory therapeutic targets. Based on a systematic literature review, we identified 22 cases of tics causally attributed to brain lesions and employed ‘lesion network mapping’ to interrogate whether tic-inducing lesions would be associated with a common network in the average human brain. We probed this using a normative functional connectome acquired in 1000 healthy participants. We then examined the specificity of the identified network by contrasting tic-lesion connectivity maps to those seeding from 717 lesions associated with a wide array of neurological and/or psychiatric symptoms within the Harvard Lesion Repository. Finally, we determined the predictive utility of the tic-inducing lesion network as a therapeutic target for neuromodulation. Specifically, we collected retrospective data of 30 individuals with Tourette disorder, who underwent either thalamic (n = 15; centromedian/ventrooralis internus) or pallidal (n = 15; anterior segment of globus pallidus internus) deep brain stimulation and calculated whether connectivity between deep brain stimulation sites and the lesion network map could predict clinical improvements. Despite spatial heterogeneity, tic-inducing lesions mapped to a common network map, which comprised the insular cortices, cingulate gyrus, striatum, globus pallidus internus, thalami and cerebellum. Connectivity to a region within the anterior striatum (putamen) was specific to tic-inducing lesions when compared with control lesions. Connectivity between deep brain stimulation electrodes and the lesion network map was predictive of tic improvement, regardless of the deep brain stimulation target. Taken together, our results reveal a common brain network involved in tic generation, which shows potential as a therapeutic target for neuromodulation.
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- 2022
28. Stress Reduction by Yoga versus Mindfulness Training in Adults Suffering from Distress: A Three-Armed Randomized Controlled Trial including Qualitative Interviews (RELAX Study)
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Jan Moritz, Fischer, Farid-Ihab, Kandil, Christian S, Kessler, Lucas, Nayeri, Laura Sophie, Zager, Theresa, Rocabado Hennhöfer, Nico, Steckhan, Daniela A, Koppold-Liebscher, Holger C, Bringmann, Thomas, Schäfer, Andreas, Michalsen, and Michael, Jeitler
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mindfulness ,yoga ,mixed methods ,meditation ,stress reduction ,iyengar yoga ,600 Technik, Medizin, angewandte Wissenschaften::610 Medizin und Gesundheit::610 Medizin und Gesundheit - Abstract
Distress is a growing public health concern. In this three-armed randomized controlled trial, n = 102 adults with elevated stress levels and stress-related symptoms were randomly assigned to (1) "integrative" yoga classes which combined physical exercises, mindfulness training, and ethical/philosophical aspects of traditional yoga; to (2) Iyengar yoga classes which entailed primarily physical exercises; or to (3) mindfulness training without physical training. We hypothesized the synergistic effects of physical yoga exercises, mindfulness, and ethical/philosophical aspects. The primary outcome was the group difference on Cohen's Perceived Stress Scale (PSS) after 12 weeks. Secondary outcomes included burnout, quality of life, physical complaints, depression, anxiety, mindfulness, interoceptive awareness, self-regulation, spirituality, mysticism, and posttraumatic stress. All outcomes were evaluated at baseline (V0), after 12 weeks (V1), and after 24 weeks (V2). A subset of participants took part in qualitative interviews. A lasting and clinically relevant stress reduction was observed within all groups (PSS Delta V0-V1(Integrative Yoga) = -6.69 +/- 6.19; Delta V0-V1(Iyengar Yoga) = -6.00 +/- 7.37; Delta V0-V1(Mindfulness) = -9.74 +/- 7.80; all p < 0.00). Effect sizes were also statistically large at the end of the follow-up period (Cohen's d (Integrative Yoga) = 1.41; d (Iyengar Yoga) = 1.37; d (Mindfulness) = 1.23). There were no significant group differences or evidence of relevant synergistic effects from combining mindfulness and physical yoga exercises. All three interventions were found to be equally effective methods of stress reduction. Their use in practice should be based on availability and patient preference.
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- 2022
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29. Ground-based Radar Observations of Snow Cover Evolution and Flowing Avalanches
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Lai Bun Lok, Jan-Thomas Fischer, and Anselm Köhler
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Scale (ratio) ,Environmental science ,Satellite ,Astrophysics::Earth and Planetary Astrophysics ,Radar measurement ,Ground based radar ,Physics::Atmospheric and Oceanic Physics ,Snow cover ,Remote sensing - Abstract
Satellite-based radar measurement are increasingly important for the detection of avalanche activity and the characterization of the snow cover properties on a regional scale. However, they operate...
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- 2021
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30. Lasing from Laminated Quasi‐2D/3D Perovskite Planar Heterostructures
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Yang Li, Julie Roger, Isabel Allegro, Jan C. Fischer, Qihao Jin, Uli Lemmer, Ian A. Howard, and Ulrich W. Paetzold
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Biomaterials ,Electrochemistry ,ddc:620 ,Condensed Matter Physics ,Engineering & allied operations ,Electronic, Optical and Magnetic Materials - Published
- 2022
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31. Deposition morphology in large-scale laboratory stony debris flows
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Shiva P. Pudasaini, Gustavo Queiroz de Oliveira, Jan-Thomas Fischer, and Ivo Baselt
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Flume ,symbols.namesake ,Flow velocity ,Flow (psychology) ,Froude number ,symbols ,Elevation ,Geotechnical engineering ,Debris ,Geology ,Deposition (geology) ,Earth-Surface Processes ,Debris flow - Abstract
Debris flows affect vulnerable areas by unloading their destructive impact and depositing sediments in debris-flow lobes in the runout area. The debris flow deposition morphology characteristically displays a complex process and is of particular interest for hazard mapping, economic activities planning, construction of civil structures, and settlements in vulnerable areas. This laboratory study is based on large-scale stony debris flow experiments, focusing on the runout distance, mobility, and inundated area. The experiments were conducted under different initial and boundary conditions like particle size, solid volume fraction, and basal roughness. Our experimental results reveal that runout distance and lobe shape change dramatically under different solid volume fractions and are highly dependent on basal roughness. On the contrary, the particle size has a marginal effect on deposit morphology. The newly introduced dimensionless runout capacity allows the evaluation of the momentum transfer of the debris flows to the end of the flume into a runout distance. The experimental results show that the runout capacity is inversely proportional to the Froude number of the stony debris flow. We deduce a relationship for the runout distance from this concept, which reveals that flow velocity contributed to the runout distance on a par with the flow depth. A weak velocity can be counterbalanced by an increased front depth to achieve a similar runout distance. Furthermore, we evaluate flow mobility, deposited volume, as well as the inundated area, and compare our results with other experimental and field data. The presented data match existing hypermobility models in-between small-scale laboratory and field-scale events. Consequently, this study complements missing data to the previous dataset of runout distance, elevation difference, mobility, and inundated area, contributing to better understand debris flow dynamics.
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- 2022
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