Refine
Year of publication
Institute
- Fachbereich Medizintechnik und Technomathematik (2077) (remove)
Document Type
- Article (1594)
- Conference Proceeding (243)
- Book (96)
- Part of a Book (62)
- Doctoral Thesis (27)
- Patent (17)
- Report (15)
- Other (9)
- Habilitation (4)
- Lecture (3)
Keywords
- Biosensor (25)
- Finite-Elemente-Methode (16)
- CAD (15)
- civil engineering (14)
- Bauingenieurwesen (13)
- Einspielen <Werkstoff> (13)
- shakedown analysis (9)
- FEM (6)
- Limit analysis (6)
- Shakedown analysis (6)
- limit analysis (6)
- Clusterion (5)
- Air purification (4)
- Einspielanalyse (4)
- Hämoglobin (4)
- LAPS (4)
- Lipopolysaccharide (4)
- Luftreiniger (4)
- Natural language processing (4)
- Plasmacluster ion technology (4)
- Raumluft (4)
- Shakedown (4)
- Technische Mechanik (4)
- Traglast (4)
- Traglastanalyse (4)
- hydrogen peroxide (4)
- impedance spectroscopy (4)
- shakedown (4)
- CellDrum (3)
- Field-effect sensor (3)
- Information extraction (3)
- Kohlenstofffaser (3)
- Label-free detection (3)
- Light-addressable potentiometric sensor (3)
- Paired sample (3)
- Sonde (3)
- biosensor (3)
- biosensors (3)
- lipopolysaccharides (3)
- ratchetting (3)
- Analytischer Zulaessigkeitsnachweis (2)
- Architektur (2)
- Bacillus atrophaeus (2)
- Biocomposites (2)
- Boundary integral equations (2)
- Bruchmechanik (2)
- Capacitive field-effect sensor (2)
- Clustering (2)
- Conductive boundary condition (2)
- Druckbeanspruchung (2)
- Druckbehälter (2)
- Druckbelastung (2)
- Einspiel-Analyse (2)
- Eisschicht (2)
- Empirical process (2)
- Erythrozyt (2)
- Fehlerstellen (2)
- Fibroblast (2)
- Force (2)
- Goodness-of-fit test (2)
- Incomplete data (2)
- Independence test (2)
- Iterative learning control (2)
- Machine learning (2)
- Natural fibres (2)
- Parametric bootstrap (2)
- Pflanzenphysiologie (2)
- Pflanzenscanner (2)
- Polymer-matrix composites (2)
- Potentiometry (2)
- Raman spectroscopy (2)
- Ratcheting (2)
- Rohr (2)
- Rohrbruch (2)
- Simulation (2)
- Stahl (2)
- Stickstoffmonoxid (2)
- Stiffness (2)
- Stress concentrations (2)
- Tobacco mosaic virus (TMV) (2)
- Transmission eigenvalues (2)
- acetoin (2)
- architecture (2)
- biopotential electrodes (2)
- burst pressure (2)
- burst tests (2)
- capacitive field-effect sensors (2)
- carbonized rice husk (2)
- celldrum technology (2)
- constructive alignment (2)
- damage (2)
- examination (2)
- field-effect sensor (2)
- flaw (2)
- frequency mixing magnetic detection (2)
- gas sensor (2)
- likelihood ratio test (2)
- limit load (2)
- load limit (2)
- locomotion (2)
- long-term retention (2)
- multimodal (2)
- muscle fascicle behavior (2)
- nanostructured carbonized plant parts (2)
- nanostrukturierte carbonisierte Pflanzenteile (2)
- nitric oxide gas (2)
- not identically distributed (2)
- pipes (2)
- plant scanner (2)
- practical learning (2)
- sterilisation (2)
- surface modification (2)
- tension–torsion loading (2)
- tobacco mosaic virus (TMV) (2)
- ultrasound (2)
- ultrasound imaging (2)
- vessels (2)
- (Bio)degradation (1)
- 3-nitrofluoranthene (1)
- Acceleration (1)
- Achilles tendon (1)
- Active learning (1)
- Adaptive control (1)
- Adsorption (1)
- Afterload (1)
- Ageing (1)
- Agent-based modeling (1)
- Agent-based simulation (1)
- AlterG (1)
- Alternating plasticity (1)
- Alzheimer's disease (1)
- Analysis (1)
- Analytical models (1)
- Anastomose (1)
- Anastomosis (1)
- Anastomotic leakage (1)
- Anatomy (1)
- Annulus Fibrosus (1)
- Architectural design (1)
- Architectural gear ratio (1)
- Arthosetherapie (1)
- Assistive technology (1)
- Asymptotic efficiency (1)
- Asymptotic relative efficiency (1)
- Aufschlagversuch (1)
- Autofluoreszenzverfahren (1)
- Autolysis (1)
- Automatic control (1)
- Axialbelastung (1)
- Axially cracked pipe (1)
- BTEX compounds (1)
- Bacillus atrophaeus spores (1)
- Bacillus sp (1)
- Bacterial cellulose (1)
- Bakterien (1)
- Balance (1)
- Basis Reduktion (1)
- Basis reduction (1)
- Bein (1)
- Bicharakteristikenverfahren (1)
- Bio-Sensors (1)
- Bioabsorbable (1)
- Biomechanical simulation (1)
- Biomechanics (1)
- Biomechanik (1)
- Biomedizinische Technik (1)
- Biomolecular logic gate (1)
- Biophoton (1)
- Bioreaktor (1)
- Biosensorik (1)
- Biosolubilization (1)
- Bladder (1)
- Blitzschutz (1)
- Blutzellenlagerung (1)
- Bone quality and biomechanics (1)
- Bone sawing (1)
- Booster Station (1)
- Bootstrap (1)
- Bootstrapping (1)
- Boundary integral equations, (1)
- Brennkraftmaschine (1)
- Brennstoffeinspritzsystem (1)
- Brownian Pillow (1)
- CAD ; (1)
- CNOT (1)
- CO (1)
- Calorimetric gas sensor (1)
- Capacitive field-effect (1)
- Capacitive model (1)
- Carbon sources (1)
- Cardiac myocytes (1)
- Cardiac tissue (1)
- Categorial variable (1)
- Cell permeability (1)
- Cellular force (1)
- Cellulose nanostructure (1)
- Cement infiltration (1)
- Cementoblast (1)
- Censored data (1)
- Chance constrained programming (1)
- Chemical images (1)
- Chemical imaging (1)
- Chemical imaging sensor (1)
- Chemical sensor (1)
- Choleratoxin B (1)
- Circular Dichroism (1)
- Cloud Computing (1)
- Cloud Service Broker (1)
- Co-managed care (1)
- Coal (1)
- Coat protein (1)
- Coefficient of ocular rigidity (1)
- Collective risk model (1)
- Comparative simulation (1)
- Competitiveness (1)
- Complex System (1)
- Complex-valued eigenvalues (1)
- Compliance (1)
- Compression (1)
- Computational biomechanics (1)
- Concomitant (1)
- Conducing polymer (1)
- Conductive Boundary Condition (1)
- Conservation laws (1)
- Constitutive model (1)
- Contractile tension (1)
- Contractility (1)
- Convex optimization (1)
- Corneo-scleral shell (1)
- Cost-effectiveness (1)
- Coverage probability (1)
- Cramér-von-Mises statistic (1)
- Cramér-von-Mises test (1)
- Cross border adjustment mechanism (1)
- Crámer–von-Mises distance (1)
- Culture media (1)
- C–V method (1)
- DNA (1)
- DNA biosensor (1)
- DNA hybridization (1)
- DPA (dipicolinic acid) (1)
- Damage mechanics theory (1)
- Database (1)
- Dattel (1)
- Decomposition (1)
- Deep Learning (1)
- Deep learning (1)
- Deformation (1)
- Dehydrogenase (1)
- Dekontamination (1)
- Design-by-analysis (1)
- Diaphorase (1)
- Differential tonometry (1)
- Dimensional splitting (1)
- Disc Degeneration (1)
- Discontinuous fractures (1)
- Discrete Optimization (1)
- Distorsion des oberen Sprunggelenks (1)
- Druckgeräte (1)
- Drug simulation (1)
- Dry surfaces (1)
- E-Mobility (1)
- E. coli detection (1)
- ECT (1)
- EEG (1)
- EIS capacitive sensor (1)
- ELISA (1)
- EPN (1)
- ES-FEM (1)
- Effizienz (1)
- Eigenvalue trajectories (1)
- Einspiel-Kriterium (1)
- Einspielen (1)
- Elastizität (1)
- Elastodynamik (1)
- Elastostatics (1)
- Elderly (1)
- Electrolyte–insulator–semiconductor (1)
- Electromagnetism (1)
- Electromechanical modeling (1)
- Elektrodynamik (1)
- Elektroenzephalographie (1)
- Elektromyographie (1)
- Elektrostimulation (1)
- Elemental (1)
- End-to-end colorectal anastomosis (1)
- Endothelial cells (1)
- Endothelial dysfunction (1)
- Endothelzelle (1)
- Energy dispatch (1)
- Energy market (1)
- Energy market design (1)
- Energy-intensive industry (1)
- Enterprise information systems (1)
- Entropy solution (1)
- Environmental impact (1)
- Enzymatic biosensor (1)
- Enzyme biosensor (1)
- Enzyme coverage (1)
- Enzyme logic gate (1)
- Enzyme nanocarrier (1)
- Enzyme-linked immunosorbent assay (1)
- Epithel (1)
- Equivalence test (1)
- Esophageal Doppler monitor (1)
- Evolution of damage (1)
- Exact Ilyushin yield surface (1)
- Experiment (1)
- Exponential Euler scheme, (1)
- Exponential time differencing (1)
- Extension fracture (1)
- Extension strain criterion (1)
- Extensor (1)
- External knee adduction moments (1)
- Eyeball (1)
- FEM-Programm (1)
- FEM-computation (1)
- FGF23 (1)
- FS-FEM (1)
- Fall prevention (1)
- Fault approximation (1)
- Fault detection (1)
- Festkörper (1)
- Field effect (1)
- Field-effect biosensor (1)
- Field-effect device (1)
- Finite difference methods (1)
- Finite element analysis (1)
- Finite element analysis (FEA) (1)
- Finite element method (1)
- Finite element modelling (1)
- First Order Reliabiblity Method (1)
- First-order reliability method (1)
- Fließgrenze (1)
- Floor prices (1)
- Fluorescence (1)
- Focusing (1)
- Forces (1)
- Fracture configuration (1)
- Fracture simulation (1)
- Freeze–thaw process (1)
- Frequency adaption (1)
- Frequency mixing magnetic detection (1)
- Functional Delta Method (1)
- Fußball (1)
- GaAs hot electron injector (1)
- Gamma distribution (1)
- Gas sensor (1)
- Geriatric (1)
- German (1)
- Glaucoma (1)
- Global and local collapse (1)
- Glucose biosensor (1)
- Glucose oxidase (1)
- Gold nanoparticle (1)
- Gold nanoparticles (1)
- Gonarthrose (1)
- Goodness-of-fit tests for uniformity (1)
- Grenzwertberechnung (1)
- Grid Computing (1)
- Ground-level falls (1)
- Growth modelling (1)
- Gunn diode (1)
- H2 (1)
- Hadamard differentiability (1)
- Haemodialysis (1)
- Handbike (1)
- Harnleiter (1)
- Heart tissue culture (1)
- Heavy metal detection (1)
- Helmholtz equation (1)
- Hemoglobin structure (1)
- Heterostructure (1)
- High throughput experimentation (1)
- Higher-order codes (1)
- Hip fractures (1)
- Hodgkin–Huxley models (1)
- Hoeffding-Blum-Kiefer-Rosenblatt independence test (1)
- Homogenization (1)
- Hotelling’s T² test (1)
- Hotplate (1)
- Human Factors (1)
- Human-Computer interaction (1)
- Hydrodynamik (1)
- Hydrogel (1)
- Hydrogen peroxide (1)
- Hydrogen sensor (1)
- Hydrogenotrophic methanogens (1)
- Hypothesentests (1)
- Hämoglobinstruktur (1)
- I3S 2005 (1)
- ISFET (1)
- Image Reconstruction (1)
- Impedance Spectroscopy (1)
- Impedance spectroscopy (1)
- Implicit methods (1)
- Induced pluripotent stem cells (1)
- Information Extraction (1)
- Information Integration Tools (1)
- Inotropic compounds (1)
- Instruments (1)
- Integrated empirical distribution (survival) function (1)
- Interior Neumann eigenvalues (1)
- Interior transmission eigenvalues (1)
- Interior transmission problem (1)
- International Symposium on Sensor Science (1)
- Intervertebral Disc (1)
- Intradiscal Pressure (1)
- Inverse Scattering (1)
- Inverse dynamic problem (1)
- Inverse kinematic problem (1)
- Inverse scattering (1)
- Inverse scattering problem (1)
- Inverse spectral problem (1)
- Ion channels (1)
- Kinematics (1)
- Kinetic energy (1)
- Kinetics (1)
- Klotho (1)
- Knee (1)
- Kniegelenkarthrose (1)
- Knochen (1)
- Knochenbildung (1)
- Knochenchirugie (1)
- Knochendichte (1)
- Knowledge Management (1)
- Krypton (1)
- Krypton-85 (1)
- Körpertemperatur (1)
- LED chip (1)
- LISA (1)
- LPS (1)
- Lab-on-Chip (1)
- Langevin theory (1)
- Layer-by-layer adsorption (1)
- LbL films (1)
- Level sensor (1)
- Lichtstreuungsbasierte Instrumente (1)
- Light-addressable Potentiometric Sensor (1)
- Liver (1)
- Load modeling (1)
- Long COVID (1)
- MBST (1)
- MCDA (1)
- MEMS (1)
- MOS (1)
- Magnetic nanoparticles (1)
- Main sensitivity (1)
- Manipulated variables (1)
- Marginal homogeneity (1)
- Marginal homogeneity test (1)
- Market modeling (1)
- Master stamp (1)
- Materialermüdung (1)
- Matrix exponential (1)
- Measurement (1)
- Mechanical simulation (1)
- Mechanics (1)
- Mechanische Beanspruchung (1)
- Mechanotransduction (1)
- Medusomyces gisevi (1)
- Metascintillator (1)
- Methane (1)
- Methanogenesis (1)
- Microbial adhesion (1)
- Microcirculation (1)
- Micromagnetic simulation (1)
- Microreactors (1)
- Mild cognitive impairment (1)
- Mobility (1)
- Mobility tests (1)
- Mobility transition (1)
- Model-driven software engineering (1)
- Mohr–Coulomb criterion (1)
- Monotone methods (1)
- Multi-criteria decision analysis (1)
- Multi-dimensional partial differential equations (1)
- Multi-dimensional wave propagation (1)
- Multi-sample problem (1)
- Multianalyte detection (1)
- Multicell (1)
- Multimode failure (1)
- Multiple TOF kernels (1)
- Multiplexing (1)
- Muscle (1)
- Muscle Fascicle (1)
- Muscle Force (1)
- Muscle fibers (1)
- Musculoskeletal model (1)
- Musculoskeletal system (1)
- Myocardial infarction and cardiac death (1)
- NONOate (1)
- Nano Materials (1)
- Nanomaterial (1)
- Nanoparticles (1)
- Nanopartikel (1)
- Nanostructuring (1)
- Nanotechnologie (1)
- Nanotechnology ; Microelectronics ; Biosensors ; Superconductor ; MEMS (1)
- Natriumhypochlorit (1)
- Natural Language Processing (1)
- Natural language understanding (1)
- Negative impedance convertor (1)
- Neural Network (1)
- Neuromuskuläres System (1)
- Niacin (1)
- Nichtlineare Gleichung (1)
- Nichtlineare Optimierung (1)
- Nichtlineare Welle (1)
- Nitric Oxide (1)
- Nitric Oxide Donor (1)
- Non-linear optimization (1)
- Non-parallel fissures (1)
- Nonequilibrium dynamics (1)
- Nonlinear Dynamics (1)
- Nonlinear PDEs (1)
- Nonlinear eigenvalue problems (1)
- Nucleus Pulposus (1)
- Numerical inversion of Laplace transforms (1)
- Numerical linear algebra (1)
- Numerics (1)
- O2 plasma (1)
- Ocular blood flow (1)
- Ontologie <Wissensverarbeitung> (1)
- Ontology Engineering (1)
- Open Data (1)
- Open source (1)
- Organic light-emitting diode display (1)
- Organkultur (1)
- Organophosphorus (1)
- Ostazine Orange (1)
- Osteoporose (1)
- Osteoporosis (1)
- PFM (1)
- PTH (1)
- Parabolic SPDEs (1)
- Paralympic sport (1)
- Passive stretching (1)
- Pelvic floor dysfunction (1)
- Pelvic muscle (1)
- Penicillin (1)
- Permeability (1)
- Permeabilität (1)
- Peroxidase (1)
- Pflanzenstress (1)
- Pharmacology (1)
- Phenylalanine determination (1)
- Phosphate (1)
- Photolithographic mimics (1)
- Physiology (1)
- Plant virus (1)
- Plastizität (1)
- Poly(allylamine hydrochloride) (1)
- Poly(d,l-lacticacid) (1)
- Polyimide (1)
- Polylactide acid (1)
- Post-COVID-19 syndrome (1)
- Potential theory (1)
- Preference assessment (1)
- Pressure loaded crack-face (1)
- Pressure-volume relationship (1)
- Prevention (1)
- Process model (1)
- Product-integration (1)
- Profile Extraction (1)
- Profile extraction (1)
- Progressive plastic deformation (1)
- Prophylaxis (1)
- Proteine (1)
- Proximal humerus fracture (1)
- Pseudomonas putida (1)
- Psychiatrische Biomarker (1)
- Pulsations (1)
- Pump System (1)
- Quartz crystal microbalance (1)
- Quartz crystal nanobalance (QCN) (1)
- Quartz micro balances (1)
- Query learning (1)
- RVA (1)
- Random variable (1)
- Ratchetting (1)
- Raumfahrt (1)
- Reaction-diffusion (1)
- Reaction-diffusion systems (1)
- Real distinct pole (1)
- Real-time monitoring (1)
- Recombinant activated protein C (1)
- Reconstruction (1)
- Red blood cell storage (1)
- Refining (1)
- Regionalization (1)
- Rehabilitation Technology and Prosthetics (1)
- Rehabilitation engineering (1)
- Rehabilitationsmedizin (1)
- Rehabilitatives Training (1)
- Relation classification (1)
- Reliability analysis (1)
- Reliability of structures (1)
- Renewable energy sources (1)
- Reproducible research (1)
- Resampling test (1)
- Resistive temperature detector (1)
- Resolvent Operator (1)
- Resonance-mode measurement (1)
- Retinal vessel analysis (1)
- Retinal vessels (1)
- Riboflavin (1)
- Robotic rehabilitation (1)
- Robotik (1)
- Rotator cuff (1)
- Running (1)
- S-FEM (1)
- Sampling methods (1)
- ScaLAPACK (1)
- Schienbeinschoner (1)
- Schlafspindeldetektion (1)
- Schwammknochen (1)
- Semi-parametric random censorship model (1)
- Sensitivity (1)
- Sepsis (1)
- Septic cardiomyopathy (1)
- Shakedown criterion (1)
- Silk fibroin (1)
- Simultaneous determination (1)
- Skeletal muscle (1)
- Sleep EEG (1)
- Small Aral Sea (1)
- Sn₃O₄ (1)
- Software and systems modeling (1)
- Solid amalgam electrodes (1)
- Source term (1)
- Spleen (1)
- Sprunggelenkorthesen (1)
- Statics (1)
- Steel industry (1)
- Sterilisation process (1)
- Stochastic programming (1)
- Strukturanalyse (1)
- SunRav BookEditor (1)
- Supraleiter (1)
- Surface imprinted polymer (1)
- Surface microorganisms (1)
- Surgical Navigation and Robotics (1)
- Surgical staplers (1)
- Survival analysis (1)
- Swabbing (1)
- TMV adsorption (1)
- TOF PET (1)
- Ta₂O₅ gate (1)
- Technical Operations Research (TOR) (1)
- Temperaturabhängigkeit (1)
- Tendon Rupture (1)
- Tendon properties (1)
- Tendons (1)
- Tension (1)
- Text Mining (1)
- Text mining (1)
- Thiamine (1)
- Time-series (1)
- Tin oxide (1)
- Tinetti test (1)
- Tissue Engineering (1)
- Tobacco mosaic virus (1)
- Torsion (1)
- Torsionsbelastung (1)
- Tragfähigkeit (1)
- Training (1)
- Trainingsgerät (1)
- Transmission Eigenvalues (1)
- Trinkwassersicherheit (1)
- Trustworthy artificial intelligence (1)
- UML (1)
- Ultrasound (1)
- Uniaxial compression test (1)
- Unified Modeling Language (1)
- Ureter (1)
- Vapnik–Čhervonenkis class (1)
- Variable height stapler design (1)
- Vascular response (1)
- Vasomotions (1)
- Velocity (1)
- Vergleich von Experimenten (1)
- Vertebroplastie (1)
- Vertebroplasty (1)
- Viscous flow (1)
- Viskose Strömung (1)
- Viskosität (1)
- Visual field asymmetry (1)
- Vitamin A (1)
- Vitamin B (1)
- Vitamin D (1)
- Volterra integral equation (1)
- Volume of confidence regions (1)
- Volume status (1)
- Volumes of confidence regions (1)
- Wafer (1)
- Wasserbrücke (1)
- Wasserstoffperoxid (1)
- Wellen (1)
- Wolff's Law (1)
- Wolffsches Gesetz (1)
- Workflow (1)
- Workflow Orchestration (1)
- Wundheilung (1)
- XOR (1)
- Xenon (1)
- Zeta potential (1)
- Zug-Druck Belastung (1)
- Zug-Druck-Beanspruchung (1)
- Zug-Druck-Belastung (1)
- acetoin reductase (1)
- achilles tendon (1)
- actin cytoskeleton (1)
- activated nanostructured carbon (1)
- adipose-derived stromal cells (ASCs) (1)
- adsorption (1)
- agility (1)
- aktivierte nanostrukturierte Kohlenstofffaser (1)
- alcoholic beverages (1)
- allocation (1)
- alternierend Verformbarkeit (1)
- ammonia gas sensors (1)
- amperometric biosensors (1)
- amperometric sensor (1)
- anaesthetic complications (1)
- anisotropy (1)
- ankle braces (1)
- ankle sprain (1)
- annealing (1)
- antimony doped tin oxide (1)
- aortic perfusion (1)
- aquaculture (1)
- aromatic amines (1)
- arthrosis therapy (1)
- artificial olfactory image (1)
- asymptotic relative efficiency (1)
- atomic layer deposition (1)
- autofluorescence-based detection system (1)
- barium strontium titanate (1)
- biaxial tensile experiment (1)
- bicharacteristics (1)
- bioburdens (1)
- biocompatible (1)
- biocompatible materials (1)
- biodegradabl (1)
- biodegradable electronic devices (1)
- biomechanics (1)
- bone density (1)
- bone structure (1)
- bootstrap (1)
- calorimetric gas sensor (1)
- calorimetric gas sensor;hydrogen peroxide;wireless sensor system (1)
- cancellous bone (1)
- capacitive electrolyte–insulator–semiconductor sensors (1)
- capacitive field-effect biosensor (1)
- capacitive field-effect sensor (1)
- capillary micro-droplet cell (1)
- carbon electrodes (1)
- carcinogens (1)
- cardiomyocyte biomechanics (1)
- catalytic decomposition (1)
- catalytic metal (1)
- cell aerosolization (1)
- cell atomization (1)
- central symmetry test (1)
- cerebral small vessel disease (1)
- chance constrained programming (1)
- chemical reduction method (1)
- chemical sensor (1)
- chip-based sensor setup (1)
- cholera toxin B (1)
- cognitive impairment (1)
- community dwelling (1)
- complete block symmetry (1)
- computational fluid dynamics analysis (1)
- conditional excess distribution (1)
- conditional expectation principle (1)
- confidence interval (1)
- connective tissue (1)
- constitutive modeling (1)
- contactless conductivity sensor (1)
- contractile tension (1)
- correlation (1)
- coupled Néel–Brownian relaxation dynamics (1)
- covariance principle (1)
- cross sensitivity (1)
- cytosolic water diffusion (1)
- date palm tree (1)
- dental trauma (1)
- design-by-analysis (1)
- dialysis (1)
- difficult airway (1)
- direct method (1)
- distance learning (1)
- distorted element (1)
- doped metal oxide (1)
- doped silicon (1)
- doping (1)
- double-lumen tube intubation (1)
- drinking water safety (1)
- drop jump (1)
- e-books (1)
- e-issues (1)
- ecological structure (1)
- efficiency (1)
- eigensolvers (1)
- elastic scattering (1)
- elastic solids (1)
- electrical capacitance tomography (1)
- electrical conductivity of liquids (1)
- electro-migration (1)
- electrolyte-insulator semiconductor sensor (EIS) (1)
- electromyography (1)
- electronic nose (1)
- electronic noses dendronized polymers inverted mesa technology (1)
- encapsulation materials (1)
- endoluminal (1)
- endospores (1)
- energy absorption (1)
- energy dissipation (1)
- enzymatic (bio)degradation (1)
- enzymatic biosensor (1)
- enzymatic methods (1)
- enzyme cascade (1)
- enzyme immobilisation (1)
- enzyme immobilization (1)
- epithelization (1)
- exchangeability test (1)
- extracorporeal membrane oxygenation (1)
- fatigue analyses (1)
- fenitrothion (1)
- fibroin (1)
- fibulare Bandruptur (1)
- field-effect structure (1)
- finite element analysis (1)
- fluidic (1)
- force generation (1)
- forecast (1)
- forehead EEG (1)
- fortschreitende plastische Deformation (1)
- frequency mixing (1)
- functional data (1)
- gait (1)
- gas sensor array (1)
- glucose (1)
- glucose oxidase (GOx) (1)
- gonarthrosis (1)
- goodness-of-fit test (1)
- graphene oxide (1)
- healthy aging (1)
- heater metallisation (1)
- heavy metals (1)
- hemoglobin (1)
- hemoglobin dynamics (1)
- hiPS cardiomyocytes (1)
- high-intensity exercise (1)
- high-k material (1)
- high-temperature stability (1)
- horseradish peroxidase (HRP) (1)
- huge dimensional data (1)
- human dermal fibroblasts (1)
- humic acid (1)
- humidity (1)
- hydrogel (1)
- hydroxylation (1)
- hyper-gravity (1)
- hyperelastic (1)
- hypo-gravity (1)
- image sensor (1)
- imaging (1)
- immobilization (1)
- in-ear EEG (1)
- in-situ monitoring (1)
- independence test (1)
- intraclass correlation coefficient (1)
- ion-selective electrodes (1)
- key performance indicators (1)
- kontraktile Spannung (1)
- konvexe Optimierung (1)
- krypton xenon hydrate (1)
- lab-on-a-chip (1)
- lab-on-chip (1)
- lable-free detection (1)
- large language models (1)
- layer expansion (1)
- layer-by-layer technique (1)
- lenslet array (1)
- light scattering analysis (1)
- light-addressable potentiometric sensor (1)
- light-addressing technologies (1)
- lightning flash (1)
- lignite (1)
- limit and shakedown analysis (1)
- linear kinematic hardening (1)
- lipopolysaccharide (1)
- load carrying capacity (1)
- lower bound theorem (1)
- magnetic actuation (1)
- magnetic beads (1)
- magnetic biosensing (1)
- magnetic frequency mixing technique (1)
- magnetic nanoparticles (1)
- magnetic particles (1)
- magnetic relaxation (1)
- magnetic sandwich immunoassay (1)
- magnetic sensing (1)
- magnetic separation (1)
- magnetic tweezers (1)
- magnetophoretic velocity (1)
- material shakedown (1)
- matrix method (1)
- mechanical buffer (1)
- mechanical waves (1)
- metagenomics (1)
- metal oxide (1)
- metal-oxide-semiconductor structure (1)
- method of fundamental solutions (1)
- microbial diversity (1)
- microfluidics (1)
- micromagnetic simulation (1)
- microreactor (1)
- microwave generation (1)
- modeling biosensor (1)
- modelling (1)
- modified electrode (1)
- multi-functional material (1)
- multi-interface measurement (1)
- multinomial distribution (1)
- multiparametric immunoassays (1)
- multivariate normal distribution (1)
- muscle mechanics (1)
- nanobelts (1)
- nanomaterials (1)
- naphtols (1)
- nitrogen oxides (1)
- non-simplex S-FEM elements (1)
- nonlinear kinematic hardening (1)
- nonlinear optimization (1)
- nonlinear solids (1)
- nonlinear tensor constitutive equation (1)
- novel photoexcitation method (1)
- optical sensor setup (1)
- optical spore trapping (1)
- optical trapping (1)
- organic PVC membranes (1)
- organosilanes (1)
- overload (1)
- pH sensors (1)
- pH-based biosensing (1)
- parabolic flight (1)
- pattern-size reduction (1)
- penicillin (1)
- penicillinase (1)
- performance analysis (1)
- performance testing (1)
- phenols (1)
- photoelectrochemistry (1)
- physiology (1)
- plant stress (1)
- plant virus detection (1)
- plasma generated ions (1)
- plastic deformation (1)
- plug-based microfluidic device (1)
- poly(d, l-lactic acid) (1)
- polyaniline (1)
- polymer composites (1)
- porous Pt electrode (1)
- portfolio risk (1)
- prevention (1)
- principal component (1)
- probabilistic fracture mechanics (1)
- protein (1)
- psychosocial (1)
- quantum charging (1)
- random effects (1)
- random effects meta-regression model (1)
- rehabilitation (1)
- reliability (1)
- reliability analysis (1)
- reliability of structures (1)
- retinal microvasculature (1)
- retinal vessels (1)
- rhAPC (1)
- running (1)
- rupture of the fibular ligament (1)
- sEMG (1)
- sarcomere operating length (1)
- scanned light pulse technique (1)
- screen-printing (1)
- second-order reliability method (1)
- self-aligned patterning (1)
- semantic role labeling (1)
- sensing properties (1)
- sensors (1)
- separable Hilbert space (1)
- series elastic element behavior (1)
- shakedown analyses (1)
- shotgun sequencing (1)
- shoulder (1)
- silanization (1)
- simulation (1)
- smooth muscle contraction (1)
- softs (1)
- spatial resolution (1)
- speaker attribution (1)
- sprint start (1)
- standard error of measurement (1)
- sterility tests (1)
- sterilization (1)
- sterilization conditions (1)
- sterilization efficacy (1)
- sterilization methods (1)
- stiffness (1)
- stochastic programming (1)
- strain energy function (1)
- stretch reflex (1)
- stretch-shortening cycle (1)
- subsurface ice research (1)
- subsurface probe (1)
- superparamagnetic bead (1)
- superparamagnetic nanoparticles (1)
- surface functionalization (1)
- survival (1)
- swift heavy ions (1)
- temperature (1)
- tendon rupture (1)
- test-retest reliability (1)
- testing hypotheses (1)
- thermal ratcheting (1)
- thermometry (1)
- thick-film technology (1)
- thin-film microsensors (1)
- tilted constant illumination (1)
- titanium dioxide photoanode (1)
- training simulator (1)
- tri-lineage differentiation (1)
- turnip vein clearing virus (TVCV) (1)
- twin-fluid atomizer (1)
- ultrasonography (1)
- ultrathin gate insulators (1)
- uniformly most powerful invariant test (1)
- unloading (1)
- validation methods (1)
- videolaryngoscopy (1)
- virgin passive (1)
- virtual reality (1)
- viscoelasticity (1)
- visualization (1)
- voltammetry (1)
- wafer-level testing (1)
- walking (1)
- walking gait (1)
- water bridge phenomenon (1)
- wound healing (1)
- yield stress (1)
- · Psychiatrische Erkrankungen/Diagnostik (1)
Direct sampling method via Landweber iteration for an absorbing scatterer with a conductive boundary
(2024)
In this paper, we consider the inverse shape problem of recovering isotropic scatterers with a conductive boundary condition. Here, we assume that the measured far-field data is known at a fixed wave number. Motivated by recent work, we study a new direct sampling indicator based on the Landweber iteration and the factorization method. Therefore, we prove the connection between these reconstruction methods. The method studied here falls under the category of qualitative reconstruction methods where an imaging function is used to recover the absorbing scatterer. We prove stability of our new imaging function as well as derive a discrepancy principle for recovering the regularization parameter. The theoretical results are verified with numerical examples to show how the reconstruction performs by the new Landweber direct sampling method.
We consider the numerical approximation of second-order semi-linear parabolic stochastic partial differential equations interpreted in the mild sense which we solve on general two-dimensional domains with a C² boundary with homogeneous Dirichlet boundary conditions. The equations are driven by Gaussian additive noise, and several Lipschitz-like conditions are imposed on the nonlinear function. We discretize in space with a spectral Galerkin method and in time using an explicit Euler-like scheme. For irregular shapes, the necessary Dirichlet eigenvalues and eigenfunctions are obtained from a boundary integral equation method. This yields a nonlinear eigenvalue problem, which is discretized using a boundary element collocation method and is solved with the Beyn contour integral algorithm. We present an error analysis as well as numerical results on an exemplary asymmetric shape, and point out limitations of the approach.
Analysis and computation of the transmission eigenvalues with a conductive boundary condition
(2022)
We provide a new analytical and computational study of the transmission eigenvalues with a conductive boundary condition. These eigenvalues are derived from the scalar inverse scattering problem for an inhomogeneous material with a conductive boundary condition. The goal is to study how these eigenvalues depend on the material parameters in order to estimate the refractive index. The analytical questions we study are: deriving Faber–Krahn type lower bounds, the discreteness and limiting behavior of the transmission eigenvalues as the conductivity tends to infinity for a sign changing contrast. We also provide a numerical study of a new boundary integral equation for computing the eigenvalues. Lastly, using the limiting behavior we will numerically estimate the refractive index from the eigenvalues provided the conductivity is sufficiently large but unknown.
Fields of asymmetric tensors play an important role in many applications such as medical imaging (diffusion tensor magnetic resonance imaging), physics, and civil engineering (for example Cauchy-Green-deformation tensor, strain tensor with local rotations, etc.). However, such asymmetric tensors are usually symmetrized and then further processed. Using this procedure results in a loss of information. A new method for the processing of asymmetric tensor fields is proposed restricting our attention to tensors of second-order given by a 2x2 array or matrix with real entries. This is achieved by a transformation resulting in Hermitian matrices that have an eigendecomposition similar to symmetric matrices. With this new idea numerical results for real-world data arising from a deformation of an object by external forces are given. It is shown that the asymmetric part indeed contains valuable information.
An alternative method is presented to numerically compute interior elastic transmission eigenvalues for various domains in two dimensions. This is achieved by discretizing the resulting system of boundary integral equations in combination with a nonlinear eigenvalue solver. Numerical results are given to show that this new approach can provide better results than the finite element method when dealing with general domains.
The hot spots conjecture is only known to be true for special geometries. This paper shows numerically that the hot spots conjecture can fail to be true for easy to construct bounded domains with one hole. The underlying eigenvalue problem for the Laplace equation with Neumann boundary condition is solved with boundary integral equations yielding a non-linear eigenvalue problem. Its discretization via the boundary element collocation method in combination with the algorithm by Beyn yields highly accurate results both for the first non-zero eigenvalue and its corresponding eigenfunction which is due to superconvergence. Additionally, it can be shown numerically that the ratio between the maximal/minimal value inside the domain and its maximal/minimal value on the boundary can be larger than 1 + 10− 3. Finally, numerical examples for easy to construct domains with up to five holes are provided which fail the hot spots conjecture as well.
There is a very large number of very important situations which can be modeled with nonlinear parabolic partial differential equations (PDEs) in several dimensions. In general, these PDEs can be solved by discretizing in the spatial variables and transforming them into huge systems of ordinary differential equations (ODEs), which are very stiff. Therefore, standard explicit methods require a large number of iterations to solve stiff problems. But implicit schemes are computationally very expensive when solving huge systems of nonlinear ODEs. Several families of Extrapolated Stabilized Explicit Runge-Kutta schemes (ESERK) with different order of accuracy (3 to 6) are derived and analyzed in this work. They are explicit methods, with stability regions extended, along the negative real semi-axis, quadratically with respect to the number of stages s, hence they can be considered to solve stiff problems much faster than traditional explicit schemes. Additionally, they allow the adaptation of the step length easily with a very small cost.
Two new families of ESERK schemes (ESERK3 and ESERK6) are derived, and analyzed, in this work. Each family has more than 50 new schemes, with up to 84.000 stages in the case of ESERK6. For the first time, we also parallelized all these new variable step length and variable number of stages algorithms (ESERK3, ESERK4, ESERK5, and ESERK6). These parallelized strategies allow to decrease times significantly, as it is discussed and also shown numerically in two problems. Thus, the new codes provide very good results compared to other well-known ODE solvers. Finally, a new strategy is proposed to increase the efficiency of these schemes, and it is discussed the idea of combining ESERK families in one code, because typically, stiff problems have different zones and according to them and the requested tolerance the optimum order of convergence is different.
Interior transmission eigenvalue problems for the Helmholtz equation play an important role in inverse wave scattering. Some distribution properties of those eigenvalues in the complex plane are reviewed. Further, a new scattering model for the interior transmission eigenvalue problem with mixed boundary conditions is described and an efficient algorithm for computing the interior transmission eigenvalues is proposed. Finally, extensive numerical results for a variety of two-dimensional scatterers are presented to show the validity of the proposed scheme.
A second-order L-stable exponential time-differencing (ETD) method is developed by combining an ETD scheme with approximating the matrix exponentials by rational functions having real distinct poles (RDP), together with a dimensional splitting integrating factor technique. A variety of non-linear reaction-diffusion equations in two and three dimensions with either Dirichlet, Neumann, or periodic boundary conditions are solved with this scheme and shown to outperform a variety of other second-order implicit-explicit schemes. An additional performance boost is gained through further use of basic parallelization techniques.
In this article, a concept of implicit methods for scalar conservation laws in one or more spatial dimensions allowing also for source terms of various types is presented. This material is a significant extension of previous work of the first author (Breuß SIAM J. Numer. Anal. 43(3), 970–986 2005). Implicit notions are developed that are centered around a monotonicity criterion. We demonstrate a connection between a numerical scheme and a discrete entropy inequality, which is based on a classical approach by Crandall and Majda. Additionally, three implicit methods are investigated using the developed notions. Next, we conduct a convergence proof which is not based on a classical compactness argument. Finally, the theoretical results are confirmed by various numerical tests.
The inverse scattering problem for a conductive boundary condition and transmission eigenvalues
(2018)
In this paper, we consider the inverse scattering problem associated with an inhomogeneous media with a conductive boundary. In particular, we are interested in two problems that arise from this inverse problem: the inverse conductivity problem and the corresponding interior transmission eigenvalue problem. The inverse conductivity problem is to recover the conductive boundary parameter from the measured scattering data. We prove that the measured scatted data uniquely determine the conductivity parameter as well as describe a direct algorithm to recover the conductivity. The interior transmission eigenvalue problem is an eigenvalue problem associated with the inverse scattering of such materials. We investigate the convergence of the eigenvalues as the conductivity parameter tends to zero as well as prove existence and discreteness for the case of an absorbing media. Lastly, several numerical and analytical results support the theory and we show that the inside–outside duality method can be used to reconstruct the interior conductive eigenvalues.
Das Diskussionspapier beschreibt einen Prozess an der FH Aachen zur Entwicklung und Implementierung eines Self-Assessment-Tools für Studiengänge. Dieser Prozess zielte darauf ab, die Relevanz der Themen Digitalisierung, Internationalisierung und Nachhaltigkeit in Studiengängen zu stärken. Durch Workshops und kollaborative Entwicklung mit Studiendekan:innen entstand ein Fragebogen, der zur Reflexion und strategischen Weiterentwicklung der Studiengänge dient.
In this work, we present a compact, bifunctional chip-based sensor setup that measures the temperature and electrical conductivity of water samples, including specimens from rivers and channels, aquaculture, and the Atlantic Ocean. For conductivity measurements, we utilize the impedance amplitude recorded via interdigitated electrode structures at a single triggering frequency. The results are well in line with data obtained using a calibrated reference instrument. The new setup holds for conductivity values spanning almost two orders of magnitude (river versus ocean water) without the need for equivalent circuit modelling. Temperature measurements were performed in four-point geometry with an on-chip platinum RTD (resistance temperature detector) in the temperature range between 2 °C and 40 °C, showing no hysteresis effects between warming and cooling cycles. Although the meander was not shielded against the liquid, the temperature calibration provided equivalent results to low conductive Milli-Q and highly conductive ocean water. The sensor is therefore suitable for inline and online monitoring purposes in recirculating aquaculture systems.
As one class of molecular imprinted polymers (MIPs), surface imprinted polymer (SIP)-based biosensors show great potential in direct whole-bacteria detection. Micro-contact imprinting, that involves stamping the template bacteria immobilized on a substrate into a pre-polymerized polymer matrix, is the most straightforward and prominent method to obtain SIP-based biosensors. However, the major drawbacks of the method arise from the requirement for fresh template bacteria and often non-reproducible bacteria distribution on the stamp substrate. Herein, we developed a positive master stamp containing photolithographic mimics of the template bacteria (E. coli) enabling reproducible fabrication of biomimetic SIP-based biosensors without the need for the “real” bacteria cells. By using atomic force and scanning electron microscopy imaging techniques, respectively, the E. coli-capturing ability of the SIP samples was tested, and compared with non-imprinted polymer (NIP)-based samples and control SIP samples, in which the cavity geometry does not match with E. coli cells. It was revealed that the presence of the biomimetic E. coli imprints with a specifically designed geometry increases the sensor E. coli-capturing ability by an “imprinting factor” of about 3. These findings show the importance of geometry-guided physical recognition in bacterial detection using SIP-based biosensors. In addition, this imprinting strategy was employed to interdigitated electrodes and QCM (quartz crystal microbalance) chips. E. coli detection performance of the sensors was demonstrated with electrochemical impedance spectroscopy (EIS) and QCM measurements with dissipation monitoring technique (QCM-D).
Electrolyte-insulator-semiconductor capacitors (EISCAP) belong to field-effect sensors having an attractive transducer architecture for constructing various biochemical sensors. In this study, a capacitive model of enzyme-modified EISCAPs has been developed and the impact of the surface coverage of immobilized enzymes on its capacitance-voltage and constant-capacitance characteristics was studied theoretically and experimentally. The used multicell arrangement enables a multiplexed electrochemical characterization of up to sixteen EISCAPs. Different enzyme coverages have been achieved by means of parallel electrical connection of bare and enzyme-covered single EISCAPs in diverse combinations. As predicted by the model, with increasing the enzyme coverage, both the shift of capacitance-voltage curves and the amplitude of the constant-capacitance signal increase, resulting in an enhancement of analyte sensitivity of the EISCAP biosensor. In addition, the capability of the multicell arrangement with multi-enzyme covered EISCAPs for sequentially detecting multianalytes (penicillin and urea) utilizing the enzymes penicillinase and urease has been experimentally demonstrated and discussed.
This paper investigates the interior transmission problem for homogeneous media via eigenvalue trajectories parameterized by the magnitude of the refractive index. In the case that the scatterer is the unit disk, we prove that there is a one-to-one correspondence between complex-valued interior transmission eigenvalue trajectories and Dirichlet eigenvalues of the Laplacian which turn out to be exactly the trajectorial limit points as the refractive index tends to infinity. For general simply-connected scatterers in two or three dimensions, a corresponding relation is still open, but further theoretical results and numerical studies indicate a similar connection.
The artificial olfactory image was proposed by Lundström et al. in 1991 as a new strategy for an electronic nose system which generated a two-dimensional mapping to be interpreted as a fingerprint of the detected gas species. The potential distribution generated by the catalytic metals integrated into a semiconductor field-effect structure was read as a photocurrent signal generated by scanning light pulses. The impact of the proposed technology spread beyond gas sensing, inspiring the development of various imaging modalities based on the light addressing of field-effect structures to obtain spatial maps of pH distribution, ions, molecules, and impedance, and these modalities have been applied in both biological and non-biological systems. These light-addressing technologies have been further developed to realize the position control of a faradaic current on the electrode surface for localized electrochemical reactions and amperometric measurements, as well as the actuation of liquids in microfluidic devices.
Many important properties of bacterial cellulose (BC), such as moisture absorption capacity, elasticity and tensile strength, largely depend on its structure. This paper presents a study on the effect of the drying method on BC films produced by Medusomyces gisevii using two different procedures: room temperature drying (RT, (24 ± 2 °C, humidity 65 ± 1%, dried until a constant weight was reached) and freeze-drying (FD, treated at − 75 °C for 48 h). BC was synthesized using one of two different carbon sources—either glucose or sucrose. Structural differences in the obtained BC films were evaluated using atomic force microscopy (AFM), scanning electron microscopy (SEM), and X-ray diffraction. Macroscopically, the RT samples appeared semi-transparent and smooth, whereas the FD group exhibited an opaque white color and sponge-like structure. SEM examination showed denser packing of fibrils in FD samples while RT-samples displayed smaller average fiber diameter, lower surface roughness and less porosity. AFM confirmed the SEM observations and showed that the FD material exhibited a more branched structure and a higher surface roughness. The samples cultivated in a glucose-containing nutrient medium, generally displayed a straight and ordered shape of fibrils compared to the sucrose-derived BC, characterized by a rougher and wavier structure. The BC films dried under different conditions showed distinctly different crystallinity degrees, whereas the carbon source in the culture medium was found to have a relatively small effect on the BC crystallinity.
To gain insight on chemical sterilization processes, the influence of temperature (up to 70 °C), intense green light, and hydrogen peroxide (H₂O₂) concentration (up to 30% in aqueous solution) on microbial spore inactivation is evaluated by in-situ Raman spectroscopy with an optical trap. Bacillus atrophaeus is utilized as a model organism. Individual spores are isolated and their chemical makeup is monitored under dynamically changing conditions (temperature, light, and H₂O₂ concentration) to mimic industrially relevant process parameters for sterilization in the field of aseptic food processing. While isolated spores in water are highly stable, even at elevated temperatures of 70 °C, exposure to H₂O₂ leads to a loss of spore integrity characterized by the release of the key spore biomarker dipicolinic acid (DPA) in a concentration-dependent manner, which indicates damage to the inner membrane of the spore. Intensive light or heat, both of which accelerate the decomposition of H₂O₂ into reactive oxygen species (ROS), drastically shorten the spore lifetime, suggesting the formation of ROS as a rate-limiting step during sterilization. It is concluded that Raman spectroscopy can deliver mechanistic insight into the mode of action of H₂O₂-based sterilization and reveal the individual contributions of different sterilization methods acting in tandem.
The deformation and damage laws of non-homogeneous irregular structural planes in rocks are the basis for studying the stability of rock engineering. To investigate the damage characteristics of rock containing non-parallel fissures, uniaxial compression tests and numerical simulations were conducted on sandstone specimens containing three non-parallel fissures inclined at 0°, 45° and 90° in this study. The characteristics of crack initiation and crack evolution of fissures with different inclinations were analyzed. A constitutive model for the discontinuous fractures of fissured sandstone was proposed. The results show that the fracture behaviors of fissured sandstone specimens are discontinuous. The stress–strain curves are non-smooth and can be divided into nonlinear crack closure stage, linear elastic stage, plastic stage and brittle failure stage, of which the plastic stage contains discontinuous stress drops. During the uniaxial compression test, the middle or ends of 0° fissures were the first to crack compared to 45° and 90° fissures. The end with small distance between 0° and 45° fissures cracked first, and the end with large distance cracked later. After the final failure, 0° fissures in all specimens were fractured, while 45° and 90° fissures were not necessarily fractured. Numerical simulation results show that the concentration of compressive stress at the tips of 0°, 45° and 90° fissures, as well as the concentration of tensile stress on both sides, decreased with the increase of the inclination angle. A constitutive model for the discontinuous fractures of fissured sandstone specimens was derived by combining the logistic model and damage mechanic theory. This model can well describe the discontinuous drops of stress and agrees well with the whole processes of the stress–strain curves of the fissured sandstone specimens.
Frequency mixing magnetic detection (FMMD) is a sensitive and selective technique to detect magnetic nanoparticles (MNPs) serving as probes for binding biological targets. Its principle relies on the nonlinear magnetic relaxation dynamics of a particle ensemble interacting with a dual frequency external magnetic field. In order to increase its sensitivity, lower its limit of detection and overall improve its applicability in biosensing, matching combinations of external field parameters and internal particle properties are being sought to advance FMMD. In this study, we systematically probe the aforementioned interaction with coupled Néel–Brownian dynamic relaxation simulations to examine how key MNP properties as well as applied field parameters affect the frequency mixing signal generation. It is found that the core size of MNPs dominates their nonlinear magnetic response, with the strongest contributions from the largest particles. The drive field amplitude dominates the shape of the field-dependent response, whereas effective anisotropy and hydrodynamic size of the particles only weakly influence the signal generation in FMMD. For tailoring the MNP properties and parameters of the setup towards optimal FMMD signal generation, our findings suggest choosing large particles of core sizes dc > 25 nm nm with narrow size distributions (σ < 0.1) to minimize the required drive field amplitude. This allows potential improvements of FMMD as a stand-alone application, as well as advances in magnetic particle imaging, hyperthermia and magnetic immunoassays.
Analyzing electroencephalographic (EEG) time series can be challenging, especially with deep neural networks, due to the large variability among human subjects and often small datasets. To address these challenges, various strategies, such as self-supervised learning, have been suggested, but they typically rely on extensive empirical datasets. Inspired by recent advances in computer vision, we propose a pretraining task termed "frequency pretraining" to pretrain a neural network for sleep staging by predicting the frequency content of randomly generated synthetic time series. Our experiments demonstrate that our method surpasses fully supervised learning in scenarios with limited data and few subjects, and matches its performance in regimes with many subjects. Furthermore, our results underline the relevance of frequency information for sleep stage scoring, while also demonstrating that deep neural networks utilize information beyond frequencies to enhance sleep staging performance, which is consistent with previous research. We anticipate that our approach will be advantageous across a broad spectrum of applications where EEG data is limited or derived from a small number of subjects, including the domain of brain-computer interfaces.
The growing body of political texts opens up new opportunities for rich insights into political dynamics and ideologies but also increases the workload for manual analysis. Automated speaker attribution, which detects who said what to whom in a speech event and is closely related to semantic role labeling, is an important processing step for computational text analysis. We study the potential of the large language model family Llama 2 to automate speaker attribution in German parliamentary debates from 2017-2021. We fine-tune Llama 2 with QLoRA, an efficient training strategy, and observe our approach to achieve competitive performance in the GermEval 2023 Shared Task On Speaker Attribution in German News Articles and Parliamentary Debates. Our results shed light on the capabilities of large language models in automating speaker attribution, revealing a promising avenue for computational analysis of political discourse and the development of semantic role labeling systems.
Muscle function is compromised by gravitational unloading in space affecting overall musculoskeletal health. Astronauts perform daily exercise programmes to mitigate these effects but knowing which muscles to target would optimise effectiveness. Accurate inflight assessment to inform exercise programmes is critical due to lack of technologies suitable for spaceflight. Changes in mechanical properties indicate muscle health status and can be measured rapidly and non-invasively using novel technology. A hand-held MyotonPRO device enabled monitoring of muscle health for the first time in spaceflight (> 180 days). Greater/maintained stiffness indicated countermeasures were effective. Tissue stiffness was preserved in the majority of muscles (neck, shoulder, back, thigh) but Tibialis Anterior (foot lever muscle) stiffness decreased inflight vs. preflight (p < 0.0001; mean difference 149 N/m) in all 12 crewmembers. The calf muscles showed opposing effects, Gastrocnemius increasing in stiffness Soleus decreasing. Selective stiffness decrements indicate lack of preservation despite daily inflight countermeasures. This calls for more targeted exercises for lower leg muscles with vital roles as ankle joint stabilizers and in gait. Muscle stiffness is a digital biomarker for risk monitoring during future planetary explorations (Moon, Mars), for healthcare management in challenging environments or clinical disorders in people on Earth, to enable effective tailored exercise programmes.
Advances in polymer science have significantly increased polymer applications in life sciences. We report the use of free-standing, ultra-thin polydimethylsiloxane (PDMS) membranes, called CellDrum, as cell culture substrates for an in vitro wound model. Dermal fibroblast monolayers from 28- and 88-year-old donors were cultured on CellDrums. By using stainless steel balls, circular cell-free areas were created in the cell layer (wounding). Sinusoidal strain of 1 Hz, 5% strain, was applied to membranes for 30 min in 4 sessions. The gap circumference and closure rate of un-stretched samples (controls) and stretched samples were monitored over 4 days to investigate the effects of donor age and mechanical strain on wound closure. A significant decrease in gap circumference and an increase in gap closure rate were observed in trained samples from younger donors and control samples from older donors. In contrast, a significant decrease in gap closure rate and an increase in wound circumference were observed in the trained samples from older donors. Through these results, we propose the model of a cell monolayer on stretchable CellDrums as a practical tool for wound healing research. The combination of biomechanical cell loading in conjunction with analyses such as gene/protein expression seems promising beyond the scope published here.
Pulmonary arterial cannulation is a common and effective method for percutaneous mechanical circulatory support for concurrent right heart and respiratory failure [1]. However, limited data exists to what effect the positioning of the cannula has on the oxygen perfusion throughout the pulmonary artery (PA). This study aims to evaluate, using computational fluid dynamics (CFD), the effect of different cannula positions in the PA with respect to the oxygenation of the different branching vessels in order for an optimal cannula position to be determined. The four chosen different positions (see Fig. 1) of the cannulas are, in the lower part of the main pulmonary artery (MPA), in the MPA at the junction between the right pulmonary artery (RPA) and the left pulmonary artery (LPA), in the RPA at the first branch of the RPA and in the LPA at the first branch of the LPA.
Magnetic nanoparticles (MNP) are investigated with great interest for biomedical applications in diagnostics (e.g. imaging: magnetic particle imaging (MPI)), therapeutics (e.g. hyperthermia: magnetic fluid hyperthermia (MFH)) and multi-purpose biosensing (e.g. magnetic immunoassays (MIA)). What all of these applications have in common is that they are based on the unique magnetic relaxation mechanisms of MNP in an alternating magnetic field (AMF). While MFH and MPI are currently the most prominent examples of biomedical applications, here we present results on the relatively new biosensing application of frequency mixing magnetic detection (FMMD) from a simulation perspective. In general, we ask how the key parameters of MNP (core size and magnetic anisotropy) affect the FMMD signal: by varying the core size, we investigate the effect of the magnetic volume per MNP; and by changing the effective magnetic anisotropy, we study the MNPs’ flexibility to leave its preferred magnetization direction. From this, we predict the most effective combination of MNP core size and magnetic anisotropy for maximum signal generation.
Motile cilia are hair-like cell extensions present in multiple organs of the body. How cilia coordinate their regular beat in multiciliated epithelia to move fluids remains insufficiently understood, particularly due to lack of rigorous quantification. We combine here experiments, novel analysis tools, and theory to address this knowledge gap. We investigate collective dynamics of cilia in the zebrafish nose, due to its conserved properties with other ciliated tissues and its superior accessibility for non-invasive imaging. We revealed that cilia are synchronized only locally and that the size of local synchronization domains increases with the viscosity of the surrounding medium. Despite the fact that synchronization is local only, we observed global patterns of traveling metachronal waves across the multiciliated epithelium. Intriguingly, these global wave direction patterns are conserved across individual fish, but different for left and right nose, unveiling a chiral asymmetry of metachronal coordination. To understand the implications of synchronization for fluid pumping, we used a computational model of a regular array of cilia. We found that local metachronal synchronization prevents steric collisions and improves fluid pumping in dense cilia carpets, but hardly affects the direction of fluid flow. In conclusion, we show that local synchronization together with tissue-scale cilia alignment are sufficient to generate metachronal wave patterns in multiciliated epithelia, which enhance their physiological function of fluid pumping.
During rapid deceleration of the body, tendons buffer part of the elongation of the muscle-tendon unit (MTU), enabling safe energy dissipation via eccentric muscle contraction. Yet, the influence of changes in tendon stiffness within the physiological range upon these lengthening contractions is unknown. This study aimed to examine the effect of training-induced stiffening of the Achilles tendon on triceps surae muscle-tendon behavior during a landing task. Twenty-one male subjects were assigned to either a 10-week resistance-training program consisting of single-leg isometric plantarflexion (n = 11) or to a non-training control group (n = 10). Before and after the training period, plantarflexion force, peak Achilles tendon strain and stiffness were measured during isometric contractions, using a combination of dynamometry, ultrasound and kinematics data. Additionally, testing included a step-landing task, during which joint mechanics and lengths of gastrocnemius and soleus fascicles, Achilles tendon, and MTU were determined using synchronized ultrasound, kinematics and kinetics data collection. After training, plantarflexion strength and Achilles tendon stiffness increased (15 and 18%, respectively), and tendon strain during landing remained similar. Likewise, lengthening and negative work produced by the gastrocnemius MTU did not change detectably. However, in the training group, gastrocnemius fascicle length was offset (8%) to a longer length at touch down and, surprisingly, fascicle lengthening and velocity were reduced by 27 and 21%, respectively. These changes were not observed for soleus fascicles when accounting for variation in task execution between tests. These results indicate that a training-induced increase in tendon stiffness does not noticeably affect the buffering action of the tendon when the MTU is rapidly stretched. Reductions in gastrocnemius fascicle lengthening and lengthening velocity during landing occurred independently from tendon strain. Future studies are required to provide insight into the mechanisms underpinning these observations and their influence on energy dissipation.
Comparison of different training algorithms for the leg extension training with an industrial robot
(2018)
In the past, different training scenarios have been developed and implemented on robotic research platforms, but no systematic analysis and comparison have been done so far. This paper deals with the comparison of an isokinematic (motion with constant velocity) and an isotonic (motion against constant weight) training algorithm. Both algorithms are designed for a robotic research platform consisting of a 3D force plate and a high payload industrial robot, which allows leg extension training with arbitrary six-dimensional motion trajectories. In the isokinematic as well as the isotonic training algorithm, individual paths are defined i n C artesian s pace by sufficient s upport p oses. I n t he i sotonic t raining s cenario, the trajectory is adapted to the measured force as the robot should only move along the trajectory as long as the force applied by the user exceeds a minimum threshold. In the isotonic training scenario however, the robot’s acceleration is a function of the force applied by the user. To validate these findings, a simulative experiment with a simple linear trajectory is performed. For this purpose, the same force path is applied in both training scenarios. The results illustrate that the algorithms differ in the force dependent trajectory adaption.
Training-induced increase in Achilles tendon stiffness affects tendon strain pattern during running
(2019)
Background
During the stance phase of running, the elasticity of the Achilles tendon enables the utilisation of elastic energy and allows beneficial contractile conditions for the triceps surae muscles. However, the effect of changes in tendon mechanical properties induced by chronic loading is still poorly understood. We tested the hypothesis that a training-induced increase in Achilles tendon stiffness would result in reduced tendon strain during the stance phase of running, which would reduce fascicle strains in the triceps surae muscles, particularly in the mono-articular soleus.
Methods
Eleven subjects were assigned to a training group performing isometric singleleg plantarflexion contractions three times per week for ten weeks, and another ten subjects formed a control group. Before and after the training period, Achilles tendon stiffness was estimated, and muscle-tendon mechanics were assessed during running at preferred speed using ultrasonography, kinematics and kinetics.
Results
Achilles tendon stiffness increased by 18% (P <0:01) in the training group, but the associated reduction in strain seen during isometric contractions was not statistically significant. Tendon elongation during the stance phase of running was similar after training, but tendon recoil was reduced by 30% (P <0:01), while estimated tendon force remained unchanged. Neither gastrocnemius medialis nor soleus fascicle shortening during stance was affected by training.
Discussion
These results show that a training-induced increase in Achilles tendon
stiffness altered tendon behaviour during running. Despite training-induced changes in tendon mechanical properties and recoil behaviour, the data suggest that fascicle shortening patterns were preserved for the running speed that we examined. The asymmetrical changes in tendon strain patterns supports the notion that simple inseries models do not fully explain the mechanical output of the muscle-tendon unit during a complex task like running.
The MYOTONES experiment is the first to monitor changes in the basic biomechanical properties (tone, elasticity and stiffness) of the resting human myofascial system due to microgravity with a oninvasive, portable device on board the ISS. The MyotonPRO device applies several brief mechanical stimuli to the surface of the skin, and the natural oscillation signals of the tissue beneath are detected and computed by the MyotonPRO. Thus, an objective, quick and easy determination of the state of the underlying tissue is possible.
Two preflight, four inflight and four post flight measurements were performed on a male astronaut using the same 10 measurement points (MP) for each session. MPs were located on the plantar fascia, Achilles tendon, M. soleus, M. gastrocnemius, M. multifidus, M. splenius capitis, M. deltoideus anterior, M. rectus femoris, infrapatellar tendon, M. tibialis anterior. Subcutaneous tissues thickness above the MPs was measured using ultrasound imaging. Magnetic resonance images (MRI) of lower limb muscles and functional tests were also performed pre- and postflight.
Our first measurements on board the ISS confirmed increased tone and stiffness of the lumbar multifidus muscle, an important trunk stabilizer, dysfunction of which is known to be associated with back pain. Furthermore, reduced tone and stiffness of Achilles tendon and plantar fascia were observed inflight vs. preflight, confirming previous findings from terrestrial analog studies and parabolic
flights. Unexpectedly, the deltoid showed negative inflight changes in tone and stiffness, and increased elasticity, suggesting a potential risk of muscle atrophy in longer spaceflight that should be addressed by adequate inflight countermeasure protocols. Most values from limb and back MPS showed deflected patterns (in either directions) from inflight shortly after the re-entry phase on the landing day and one week later. Most parameter values then normalized to baseline after 3 weeks likely due to 1G re-adaptation and possible outcome of the reconditioning protocol. No major changes in subcutaneous tissues thickness above the MPs were found inflight vs preflight, suggesting no bias (i.e., fluid shift, extreme tissue thickening or loss). Pre- and postflight MRI and functional tests showed negligible changes in calf muscle size, power and force, which is likely due to training effects from current inflight exercise protocols.
The MYOTONES experiment is currently ongoing to collect data from further crew members. The potential impact of this research is to better understand the effects of microgravity and countermeasures over the time course of an ISS mission cycle. This will enable exercise countermeasures to be tailored
Effective training requires high muscle forces potentially leading to training-induced injuries. Thus, continuous monitoring and controlling of the loadings applied to the musculoskeletal system along the motion trajectory is required. In this paper, a norm-optimal iterative learning control algorithm for the robot-assisted training is developed. The algorithm aims at minimizing the external knee joint moment, which is commonly used to quantify the loading of the medial compartment. To estimate the external knee joint moment, a musculoskeletal lower extremity model is implemented in OpenSim and coupled with a model of an industrial robot and a force plate mounted at its end-effector. The algorithm is tested in simulation for patients with varus, normal and valgus alignment of the knee. The results show that the algorithm is able to minimize the external knee joint moment in all three cases and converges after less than seven iterations.
Neuromuscular strength training of the leg extensor muscles plays an important role in the rehabilitation and prevention of age and wealth related diseases. In this paper, we focus on the design and implementation of a Cartesian admittance control scheme for isotonic training, i.e. leg extension and flexion against a predefined weight. For preliminary testing and validation of the designed algorithm an experimental research and development platform consisting of an
industrial robot and a force plate mounted at its end-effector has been used. Linear, diagonal and arbitrary two-dimensional motion trajectories with different weights for the leg extension and flexion part are applied. The proposed algorithm is easily adaptable to trajectories consisting of arbitrary six-dimensional poses and allows the implementation of individualized trajectories.
To prevent the reduction of muscle mass and loss of strength coming along with the human aging process, regular training with e.g. a leg press is suitable. However, the risk of training-induced injuries requires the continuous monitoring and controlling of the forces applied to the musculoskeletal system as well as the velocity along the motion trajectory and the range of motion. In this paper, an adaptive norm-optimal iterative learning control algorithm to minimize the knee joint loadings during the leg extension training with an industrial robot is proposed. The response of the algorithm is tested in simulation for patients with varus, normal and valgus alignment of the knee and compared to the results of a higher-order iterative learning control algorithm, a robust iterative learning control and a recently proposed conventional norm-optimal iterative learning control algorithm. Although significant improvements in performance are made compared to the conventional norm-optimal iterative learning control algorithm with a small learning factor, for the developed approach as well as the robust iterative learning control algorithm small steady state errors occur.
Achilles tendon rupture (ATR) patients have persistent functional deficits in the triceps surae muscle–tendon unit (MTU). The complex remodeling of the MTU accompanying these deficits remains poorly understood. The purpose of the present study was to associate in vivo and in silico data to investigate the relations between changes inMTU properties and strength deficits inATR patients. Methods: Elevenmale subjects who had undergone surgical repair of complete unilateral ATR were examined 4.6 ± 2.0 (mean ± SD) yr after rupture. Gastrocnemius medialis (GM) tendon stiffness, morphology, and muscle architecture were determined using ultrasonography. The force–length relation of the plantar flexor muscles was assessed at five ankle joint angles. In addition, simulations (OpenSim) of the GM MTU force–length properties were performed with various iterations of MTU properties found between the unaffected and the affected side. Results: The affected side of the patients displayed a longer, larger, and stiffer GM tendon (13% ± 10%, 105% ± 28%, and 54% ± 24%, respectively) compared with the unaffected side. The GM muscle fascicles of the affected side were shorter (32% ± 12%) and with greater pennation angles (31% ± 26%). A mean deficit in plantarflexion moment of 31% ± 10% was measured. Simulations indicate that pairing an intact muscle with a longer tendon shifts the optimal angular range of peak force outside physiological angular ranges, whereas the shorter muscle fascicles and tendon stiffening seen in the affected side decrease this shift, albeit incompletely. Conclusions: These results suggest that the substantial changes in MTU properties found in ATR patients may partly result from compensatory remodeling, although this process appears insufficient to fully restore muscle function.
Performing tasks, such as running and jumping, requires activation of the agonist and antagonist muscles before (motor unit pre-activation) and during movement performance (Santello and Mcdonagh, 1998). A well-timed and regulated muscle activation elicits a stretch-shortening cycle (SSC) response, naturally occurring in bouncing movements (Ishikawa and Komi, 2004; Taube et al., 2012). By definition, the SSC describes the stretching of a pre-activated muscle-tendon complex immediately followed by a muscle shortening in the concentric push-off phase (Komi, 1984).
Given the importance of SSC actions for human movement, it is not surprising that many studies investigated the biomechanics of this phenomenon; in particular, drop jumps (DJs) represent a good paradigm to study muscle fascicle and tendon behavior in ballistic movements involving the SSC.
Within a DJ, three main phases [pre-activation, braking, and push-off (PO; Komi, 2000)] have been recognized and extensively studied in common and challenging conditions, such as changes in load, falling height, or simulated hypo-gravity (Avela et al., 1994; Arampatzis et al., 2001; Fukashiro et al., 2005; Ishikawa et al., 2005; Sousa et al., 2007; Ritzmann et al., 2016; Helm et al., 2020).
These studies show that the timing and amount of triceps-surae muscle-tendon unit pre-activation in DJs are differentially regulated based on the load applied to the muscle, being optimal in normal “Earth” gravity conditions (Avela et al., 1994), but decreased in simulated hypo-gravity, hyper-gravity (Avela et al., 1994; Ritzmann et al., 2016), or unknown conditions (i.e., unknown falling heights; Helm et al., 2020). Some authors indicated that, when falling from heights different from the optimal one [defined as the drop height giving a maximum DJ performance indicated as peak ground reaction force (GRF) or jump high], electromyographic (EMG) activity of the plantar flexors increases from lower than optimal to higher than optimal heights (Ishikawa and Komi, 2004; Sousa et al., 2007).
These findings highlight the ability of the central nervous system to regulate the timing and amount of pre-activation according to different jumping conditions, thus regulating muscle fascicle length, tendon and joint stiffness as well as position, in order to safely land on the ground and quickly re-bounce.
Similarly, to pre-activation, also in the braking phase, the plantar flexors are differentially regulated. In optimal height (i.e., load) jumping conditions, gastrocnemius medialis (GM) fascicles shorten at early ground contact (possibly due to the intervention of the stretch reflex; Gollhofer et al., 1992) and behave quasi-isometrically in the late braking phase, enabling tendon elongation, and storage of elastic energy (Gollhofer et al., 1992; Fukashiro et al., 2005; Sousa et al., 2007). When increasing the falling height (augmenting the impact GRF), the quasi-isometric behavior of fascicles disappears, and fast fascicle lengthening occurs (Ishikawa et al., 2005; Sousa et al., 2007).
In the third and last PO phase, fascicles shorten and the tendon releases the elastic energy previously stored. Bobbert et al. (1987) reported no influence of jumping height on the work done and on the net vertical impulse assessed during PO; this observation suggests that, despite an optimal DJ performance might be achieved only in specific conditions (falling heights, loads), the central nervous system seems to be able to regulate muscle behavior in order to effectively perform the required task also in challenging situations.
Although the regulation of triceps-surae muscle-tendon unit in DJs has been extensively investigated, very few studies focused on sarcomeres behavior during the performance of this SSC movement (Kurokawa et al., 2003; Fukashiro et al., 2005, 2006). Sarcomeres represent muscle contractile units and are known to express different amounts of force depending on their length (Gordon et al., 1966; Walker and Schrodt, 1974); thus, understanding the time course of their responses during DJs is fundamental to gain further insights into muscle force-generating capacity. In vivo measurement of sarcomere length in humans has been so far been performed only in static positions and under highly controlled experimental conditions (Llewellyn et al., 2008; Sanchez et al., 2015). Instead, human sarcomere length estimation (achieved by dividing GM measured fascicle length for a fixed sarcomere number) in dynamic contractions provided an indirect measure of sarcomere operating range during squat jump, countermovement jump, and DJ (Fukashiro et al., 2005, 2006; Kurokawa et al., 2003). The results of these studies showed that sarcomeres operate in the ascending limb of their length-tension (L-T) relationship in all types of jumps, and particularly so in DJ.
However, most of the available observations on sarcomere and muscle fascicle behavior were made in condition of constant gravity. Thus, in order to understand how sarcomere and muscle fascicle length are regulated in variable gravity conditions, we performed experiments in a parabolic flight, involving variable gravity levels, ranging from about zero-g to about double the Earth’s gravity (1 g; Waldvogel et al., 2021).
Specifically, the aims of the present study were as follows:
1. To investigate the ability of the neuromuscular system in regulating fascicle length in response to conditions of variable gravity.
2. To estimate sarcomere operative length in the different DJ phases, in order to calculate its theoretical force production and its possible modulation in conditions of variable gravity.
We hypothesized that muscle fascicles would be differentially regulated in different gravity conditions compared to 1 g, particularly in anticipation of landing and re-bouncing in unknown gravity levels. In addition, we hypothesized that sarcomeres would operate in the upper part of the ascending limb of their L-T relationship, possibly lengthening during the braking phase (especially in hyper-gravity) while operating quasi-isometrically in 1 g.
The compliant nature of distal limb muscle-tendon units is traditionally considered suboptimal in explosive movements when positive joint work is required. However, during accelerative running, ankle joint net mechanical work is positive. Therefore, this study aims to investigate how plantar flexor muscle-tendon behavior is modulated during fast accelerations. Eleven female sprinters performed maximum sprint accelerations from starting blocks, while gastrocnemius muscle fascicle lengths were estimated using ultrasonography. We combined motion analysis and ground reaction force measurements to assess lower limb joint kinematics and kinetics, and to estimate gastrocnemius muscle-tendon unit length during the first two acceleration steps. Outcome variables were resampled to the stance phase and averaged across three to five trials. Relevant scalars were extracted and analyzed using one-sample and two-sample t-tests, and vector trajectories were compared using statistical parametric mapping. We found that an uncoupling of muscle fascicle behavior from muscle-tendon unit behavior is effectively used to produce net positive mechanical work at the joint during maximum sprint acceleration. Muscle fascicles shortened throughout the first and second steps, while shortening occurred earlier during the first step, where negative joint work was lower compared with the second step. Elastic strain energy may be stored during dorsiflexion after touchdown since fascicles did not lengthen at the same time to dissipate energy. Thus, net positive work generation is accommodated by the reuse of elastic strain energy along with positive gastrocnemius fascicle work. Our results show a mechanism of how muscles with high in-series compliance can contribute to net positive joint work.
The international partnership of space agencies has agreed to proceed forward to the Moon sustainably. Activities on the Lunar surface (0.16 g) will allow crewmembers to advance the exploration skills needed when expanding human presence to Mars (0.38 g). Whilst data from actual hypogravity activities are limited to the Apollo missions, simulation studies have indicated that ground reaction forces, mechanical work, muscle activation, and joint angles decrease with declining gravity level. However, these alterations in locomotion biomechanics do not necessarily scale to the gravity level, the reduction in gastrocnemius medialis activation even appears to level off around 0.2 g, while muscle activation pattern remains similar. Thus, it is difficult to predict whether gastrocnemius medialis contractile behavior during running on Moon will basically be the same as on Mars. Therefore, this study investigated lower limb joint kinematics and gastrocnemius medialis behavior during running at 1 g, simulated Martian gravity, and simulated Lunar gravity on the vertical treadmill facility. The results indicate that hypogravity-induced alterations in joint kinematics and contractile behavior still persist between simulated running on the Moon and Mars. This contrasts with the concept of a ceiling effect and should be carefully considered when evaluating exercise prescriptions and the transferability of locomotion practiced in Lunar gravity to Martian gravity.
This study aims to quantify the kinematics, kinetics and muscular activity of all-out handcycling exercise and examine their alterations during the course of a 15-s sprint test. Twelve able-bodied competitive triathletes performed a 15-s all-out sprint test in a recumbent racing handcycle that was attached to an ergometer. During the sprint test, tangential crank kinetics, 3D joint kinematics and muscular activity of 10 muscles of the upper extremity and trunk were examined using a power metre, motion capturing and surface electromyography (sEMG), respectively. Parameters were compared between revolution one (R1), revolution two (R2), the average of revolution 3 to 13 (R3) and the average of the remaining revolutions (R4). Shoulder abduction and internal-rotation increased, whereas maximal shoulder retroversion decreased during the sprint. Except for the wrist angles, angular velocity increased for every joint of the upper extremity. Several muscles demonstrated an increase in muscular activation, an earlier onset of muscular activation in crank cycle and an increased range of activation. During the course of a 15-s all-out sprint test in handcycling, the shoulder muscles and the muscles associated to the push phase demonstrate indications for short-duration fatigue. These findings are helpful to prevent injuries and improve performance in all-out handcycling.
Rehabilitative body weight supported gait training aims at restoring walking function as a key element in activities of daily living. Studies demonstrated reductions in muscle and joint forces, while kinematic gait patterns appear to be preserved with up to 30% weight support. However, the influence of body weight support on muscle architecture, with respect to fascicle and series elastic element behavior is unknown, despite this having potential clinical implications for gait retraining. Eight males (31.9 ± 4.7 years) walked at 75% of the speed at which they typically transition to running, with 0% and 30% body weight support on a lower-body positive pressure treadmill. Gastrocnemius medialis fascicle lengths and pennation angles were measured via ultrasonography. Additionally, joint kinematics were analyzed to determine gastrocnemius medialis muscle–tendon unit lengths, consisting of the muscle's contractile and series elastic elements. Series elastic element length was assessed using a muscle–tendon unit model. Depending on whether data were normally distributed, a paired t-test or Wilcoxon signed rank test was performed to determine if body weight supported walking had any effects on joint kinematics and fascicle–series elastic element behavior. Walking with 30% body weight support had no statistically significant effect on joint kinematics and peak series elastic element length. Furthermore, at the time when peak series elastic element length was achieved, and on average across the entire stance phase, muscle–tendon unit length, fascicle length, pennation angle, and fascicle velocity were unchanged with respect to body weight support. In accordance with unchanged gait kinematics, preservation of fascicle–series elastic element behavior was observed during walking with 30% body weight support, which suggests transferability of gait patterns to subsequent unsupported walking.
Altered gastrocnemius contractile behavior in former achilles tendon rupture patients during walking
(2022)
Achilles tendon rupture (ATR) remains associated with functional limitations years after injury. Architectural remodeling of the gastrocnemius medialis (GM) muscle is typically observed in the affected leg and may compensate force deficits caused by a longer tendon. Yet patients seem to retain functional limitations during—low-force—walking gait. To explore the potential limits imposed by the remodeled GM muscle-tendon unit (MTU) on walking gait, we examined the contractile behavior of muscle fascicles during the stance phase. In a cross-sectional design, we studied nine former patients (males; age: 45 ± 9 years; height: 180 ± 7 cm; weight: 83 ± 6 kg) with a history of complete unilateral ATR, approximately 4 years post-surgery. Using ultrasonography, GM tendon morphology, muscle architecture at rest, and fascicular behavior were assessed during walking at 1.5 m⋅s–1 on a treadmill. Walking patterns were recorded with a motion capture system. The unaffected leg served as control. Lower limbs kinematics were largely similar between legs during walking. Typical features of ATR-related MTU remodeling were observed during the stance sub-phases corresponding to series elastic element (SEE) lengthening (energy storage) and SEE shortening (energy release), with shorter GM fascicles (36 and 36%, respectively) and greater pennation angles (8° and 12°, respectively). However, relative to the optimal fascicle length for force production, fascicles operated at comparable length in both legs. Similarly, when expressed relative to optimal fascicle length, fascicle contraction velocity was not different between sides, except at the time-point of peak series elastic element (SEE) length, where it was 39 ± 49% lower in the affected leg. Concomitantly, fascicles rotation during contraction was greater in the affected leg during the whole stance-phase, and architectural gear ratios (AGR) was larger during SEE lengthening. Under the present testing conditions, former ATR patients had recovered a relatively symmetrical walking gait pattern. Differences in seen AGR seem to accommodate the profound changes in MTU architecture, limiting the required fascicle shortening velocity. Overall, the contractile behavior of the GM fascicles does not restrict length- or velocity-dependent force potentials during this locomotor task.
Market abstraction of energy markets and policies - application in an agent-based modeling toolbox
(2023)
In light of emerging challenges in energy systems, markets are prone to changing dynamics and market design. Simulation models are commonly used to understand the changing dynamics of future electricity markets. However, existing market models were often created with specific use cases in mind, which limits their flexibility and usability. This can impose challenges for using a single model to compare different market designs. This paper introduces a new method of defining market designs for energy market simulations. The proposed concept makes it easy to incorporate different market designs into electricity market models by using relevant parameters derived from analyzing existing simulation tools, morphological categorization and ontologies. These parameters are then used to derive a market abstraction and integrate it into an agent-based simulation framework, allowing for a unified analysis of diverse market designs. Furthermore, we showcase the usability of integrating new types of long-term contracts and over-the-counter trading. To validate this approach, two case studies are demonstrated: a pay-as-clear market and a pay-as-bid long-term market. These examples demonstrate the capabilities of the proposed framework.