Refine
Year of publication
- 2018 (154) (remove)
Document Type
- Doctoral Thesis (154) (remove)
Language
- English (154) (remove)
Keywords
- Fernerkundung (3)
- Magnetismus (3)
- climate change (3)
- magnetism (3)
- remote sensing (3)
- uncertainty (3)
- Angriffserkennung (2)
- Bakterien (2)
- Big Data (2)
- Biodiversität (2)
- Biomarker (2)
- DNA Origami (2)
- DNA origami (2)
- Ferroelektrika (2)
- Himalaya (2)
- IDS (2)
- Katalyse (2)
- Klimawandel (2)
- Nanopartikel (2)
- Naturgefahren (2)
- Photokatalyse (2)
- SIEM (2)
- Schadensmodellierung (2)
- Stoffwechsel (2)
- Unsicherheit (2)
- Unsicherheiten (2)
- bacteria (2)
- biodiversity (2)
- biomarker (2)
- block copolymer (2)
- catalysis (2)
- classification (2)
- climate impacts (2)
- damage modeling (2)
- economic impacts (2)
- event synchronization (2)
- executive function (2)
- eye-tracking (2)
- ferroelectrics (2)
- intrusion detection (2)
- komplexes Netzwerk (2)
- machine learning (2)
- magnetic nanoparticles (2)
- magnetische Nanopartikel (2)
- metabolism (2)
- metabolomics (2)
- microplastics (2)
- middle childhood (2)
- mode stability (2)
- photocatalysis (2)
- simulation (2)
- virtuelle Realität (2)
- 3D city model (1)
- 3D geovisualization (1)
- 3D point clouds (1)
- 3D portrayal (1)
- 3D printing (1)
- 3D visualization (1)
- 3D-Druck (1)
- 3D-Geovisualisierung (1)
- 3D-Punktwolken (1)
- 3D-Rendering (1)
- 3D-Stadtmodell (1)
- 3D-Visualisierung (1)
- 40Ar/39Ar (1)
- ACC (1)
- ACD6 (1)
- ADMET (1)
- ASP (Answer Set Programming) (1)
- ATRP (1)
- Affekt (1)
- Affektökonomie, Affektökonomien (1)
- Agrarlandschaft (1)
- Akkermansia muciniphila (1)
- Aktuator (1)
- Alkylpyridinium salts (1)
- Alkylpyridinium-Salze (1)
- Altern (1)
- Alternatividentitäten (1)
- Alternativvarietäten (1)
- Altersdatierung mit kosmogenen Nukliden (1)
- Aluminiumoberfläche (1)
- Aminosäuren (1)
- Analyse von Abflussganglinien (1)
- Anaphern (1)
- Anisotrope Kolloide (1)
- Anomalieerkennung (1)
- Anpassung (1)
- Antarctica (1)
- Antarktis (1)
- Antwortmengenprogrammierung (1)
- Aphasie (1)
- Arabidopsis (1)
- Arbeitsgedächtnis (1)
- Arktis (1)
- Assemblierung (1)
- Astronomie (1)
- Astroteilchen (1)
- Astroteilchenphysik (1)
- Auenbereich (1)
- Augenbewegungen (1)
- Augenblickmessung (1)
- Basalt-Vulkane (1)
- Batch-Aktivität (1)
- Bayes (1)
- Bayes'sches Lernen (1)
- Bayesian learning (1)
- Bayesische Statistik (1)
- Belastung (1)
- Beschleunigung (1)
- Bewegung (1)
- Bewegungsökologie (1)
- Big data mining zu Hochwasserrisiken (1)
- Bilingualismus (1)
- Biofilm (1)
- Biokatalyse (1)
- Biomineralisierung (1)
- Biophysik (1)
- Biosensor (1)
- Blazar (1)
- Blickbewegungsmessung (1)
- Blickspuren (1)
- Block-Copolymere (1)
- Block-copolymer (1)
- Blockcopolymer (1)
- Blockgletscher (1)
- Bodenbewegungsmodelle (1)
- Bodenunruhe (1)
- Boutet de Monvel's calculus (1)
- Boutet de Monvels Kalkül (1)
- Braunsbach Sturzflut (1)
- Braunsbach flash flood (1)
- CASP (Constraint Answer Set Programming) (1)
- CN materials (1)
- CN-Materialien (1)
- Cenral Andes (1)
- Chaos Theory (1)
- Chaostheorie (1)
- Charnockit (1)
- Chemotaxis (1)
- Chlamydomonas (1)
- CityGML (1)
- Clifford semigroup (1)
- Clifford-Halbgruppen (1)
- Clusteranalyse (1)
- Cobalt Nanopartikeln (1)
- Collision cross-section (1)
- Competitive Negotiation Tactics (1)
- Computationale Modellierung (1)
- Computergrafik (1)
- Cylindrospermopsis raciborskii (1)
- DNA (1)
- DNA assembly (1)
- DNS (1)
- Data Profiling (1)
- Datenbearbeitung (1)
- Dehnung (1)
- Deutsch (1)
- Dialel (1)
- Diamondoide (1)
- Diathese (1)
- Dielektrische Nichtlinearitäten (1)
- Diffusioosmose (1)
- Diffusioosmosis (1)
- Dissoziative Elektronenanlagerung (1)
- Disulfide (1)
- Dominante Verhandlungstaktiken (1)
- Domänenspezifische Modellierung (1)
- Dronning Maud Land (1)
- Dynamik (1)
- Dynamische Systeme (1)
- Dysprosium (1)
- EFRAG (1)
- East Africa (1)
- Eastern Karoo Basin (1)
- Echtzeit-Rendering (1)
- Einzugsgebietshydrologie (1)
- Eisbohrkern (1)
- Eisen-Kohlenstoff-Nanoröhrchen-Katalysatoren (1)
- El Nino Southern Oscillation (1)
- El Niño/Southern Oscillation-Phänomen (1)
- Elbe (1)
- Emotion (1)
- Energieschätzung (1)
- Energiespeicher (1)
- Entitätsverknüpfung (1)
- Entrepreneurship (1)
- Entscheidungsfindung (1)
- Entscheidungsmanagement (1)
- Entscheidungsmodelle (1)
- Entwurfsprinzipien (1)
- Enzym (1)
- Enzyme (1)
- Erbe (1)
- Ereignisnormalisierung (1)
- Ereignissynchronisation (1)
- Erosion (1)
- Erwerb (1)
- Erwerb des Tagalog (1)
- Eta Carinae (1)
- Eukaryoten (1)
- European hare (1)
- Evangelikalismus (1)
- Event Koinzidenz Analyse (1)
- Evolution (1)
- Experiment (1)
- Eye-Tracking (1)
- Fabrikation (1)
- Feldhase (1)
- Feldspat (1)
- Ferroelektrische Polymere (1)
- Fingerzählen (1)
- Fischer-Tropsch Synthesis (1)
- Fischer-Tropsch-Synthese (1)
- Fiskalpolitik (1)
- Flood Change (1)
- Flood Risk Big Data Mining (1)
- Flussprozesse (1)
- Flussterrassen (1)
- Flüssigkeitszerstäubung (1)
- Flüssigphasenkatalyse (1)
- Formgedächtnispolymer (1)
- Freiheit (1)
- Friedenssicherung (1)
- Funktionalisierung von Katalysatoren (1)
- Förster resonance energy transfer (1)
- Förster-Resonanzenergietransfer (1)
- GMPE adjustment (1)
- GPS (1)
- GPU (1)
- Gadolinium (1)
- Gamma-Strahlen (1)
- Gammaastronomie (1)
- Gammastrahlung (1)
- Genetisches Programmieren (1)
- Geologie (1)
- Geomorphologie (1)
- Gerinnemorphologie (1)
- German (1)
- Geschäftsprozess (1)
- Geschäftsprozessmanagement (1)
- Gletscher (1)
- Glukoseoxidation (1)
- Gold-Kohlenstoff-Katalysatoren (1)
- Growth signaling (1)
- Gruppenfeldtheorie (1)
- H.E.S.S. (1)
- Haiti (1)
- Halbgruppentheorie (1)
- Halophile (1)
- Hanghydrologie (1)
- Hangrutschungen (1)
- Helicen (1)
- Heteroatom-Modifikation (1)
- Himalaja (1)
- Hochdurchsatzsequenzierung (1)
- Holocene (1)
- Holozän (1)
- Hybridzerfall (1)
- Hydrogelen (1)
- Hydrogenolyse (1)
- Hydrograph Analysis (1)
- Hyena (1)
- Hyäne (1)
- IASB (1)
- IGM (1)
- IR-MALDI (1)
- Identifikation (1)
- In-Memory (1)
- Inklusionsabhängigkeiten (1)
- Instabiltät (1)
- Institutionelle Komplexität (1)
- Ion mobility spectrometry (1)
- Ionenmobilitätsspektrometrie (1)
- Ionisationspotential (1)
- Ionische Flüssigkeiten (1)
- Ionisierungsenergie (1)
- Janus Partikel (1)
- Janus particle (1)
- Kalahari (1)
- Kanten-Randwertprobleme (1)
- Kette von Halbgruppen (1)
- Kinder (1)
- Klassifikation (1)
- Klassifizierung (1)
- Klimaphysik (1)
- Klimapolitik (1)
- Klimarekonstruktion (1)
- Klimavariabilität (1)
- Klimaänderung (1)
- Koexistenz von Arten (1)
- Kohlenstoffmaterial (1)
- Kohlenstoffträger (1)
- Kohnen (1)
- Kommunikation (1)
- Korrelationsfunktion (1)
- Kraft lignin hydrogenolysis (1)
- Kraftlignin (1)
- Kreativität (1)
- Kumamoto Erdbeben (1)
- Kumamoto earthquake (1)
- Lake Van (1)
- Landnutzungsänderung (1)
- Landung (1)
- Laserscanning (1)
- Laufzeitmodelle (1)
- Lavafontänen (1)
- LiDAR (1)
- Lichenometrie (1)
- Ligation (1)
- Lignin (1)
- Liquid dispersion (1)
- Lobbying (1)
- Lösungsmittel-thermisches Tempern (1)
- MASC (1)
- Machinelles Lernen (1)
- Magnetohydrodynamik (1)
- Magnetostriktion (1)
- Magnetotellurik (1)
- Mahalanobis distance (1)
- Mahalanobis-Distanz (1)
- Makrozyklen (1)
- Mannigfaltigkeiten mit Kante (1)
- Mannigfaltigkeiten mit Singularitäten (1)
- Maschinelles-Lernen (1)
- Metabolite (1)
- Metabolomics (1)
- Metabolomik (1)
- Metacrate (1)
- Metadaten (1)
- Metal Chalcogenides (1)
- Metallchalkogenide (1)
- Metalle der seltenen Erden (1)
- Metamaterialien (1)
- Microschwimmer (1)
- Migrantensport (1)
- Migration (1)
- Mikrokontaktdruck (1)
- Mikroorganismen (1)
- Mikroplastik (1)
- Mikroplastikpartikel (1)
- Mikroschwimmer (1)
- Mineralverwitterungsreaktionen (1)
- Mixmodelle (1)
- Mobile-Mapping (1)
- Model of Analogue and Symbolic Codes (1)
- Modellanpassung (1)
- Modellierung (1)
- Moden Stabilität (1)
- Modenstabilität (1)
- Molecular dynamics (1)
- Molekulardynamik (1)
- Morawetz estimate (1)
- Morawetz-Schätzung (1)
- Morphologie (1)
- Motilität (1)
- Multi-Botenteilchen Astronomie (1)
- Multiple-Sklerose (1)
- Multiskalen Netzwerk (1)
- NHC (1)
- Nachhaltigkeitstransformationen (1)
- Nanokomposite (1)
- Nanoparticles (1)
- Nanoparticles, Adhesion, Interfaces, Bubble, Imaging (1)
- Natürliche Staudämme (1)
- Negotiation Management (1)
- Negotiation Performance (1)
- Negotiation Performance-Related Pay (1)
- Negotiation Phases (1)
- Negotiation Satisfaction (1)
- Negotiation Styles (1)
- Neigungswinkel (1)
- Nekrose (1)
- Neo-normative Kontrolle (1)
- Netzwerksicherheit (1)
- Neutronreflektometrie (1)
- Next generation sequencing (1)
- Nichtgleichgewicht (1)
- Nickel-Kohlenstoff-Katalysatoren (1)
- Non-linear Geoscience (1)
- Non-stationary Flood Risk (1)
- Nudging (1)
- Nährstoffe (1)
- Nährstoffretention (1)
- Oberfläche (1)
- Oberflächenchemie (1)
- Oberflächenfluss (1)
- OpenStreetMap (1)
- Organic photovoltaic Cell (1)
- Organisationen (1)
- Organische Photovoltaikzelle (1)
- Orthogruppen (1)
- Ostafrika (1)
- P(VDF-TrFE) (1)
- PBPK (1)
- PIC simulation (1)
- PUFA (1)
- Paläoklima (1)
- Paläovegetation (1)
- Parkinson's disease (1)
- Parkinson-Krankheit (1)
- Particle-in-Cell Simulationen (1)
- Partikel (1)
- Passive (1)
- Patchy Partikel (1)
- Peptiden (1)
- Peptides (1)
- Perceived Authenticity (1)
- Perylen (1)
- Pflanzengemeinschaften (1)
- Phase transitions (1)
- Phasenraum des Time Delay Embedding (1)
- Phasenübergänge (1)
- Phosphoproteomik (1)
- Photochemie (1)
- Photoelektrchemischer Sensor (1)
- Photoelektronenmikroskopie (PEEM) (1)
- Photoelektronenspektroskopie (1)
- Photoionisation (1)
- Physik der weichen Materie (1)
- Pilze (1)
- Plasma instability (1)
- Plasmainstabilität (1)
- Plasmonik (1)
- Polyelektrolyte (1)
- Polymer (1)
- Polymerchemie (1)
- Polymere (1)
- Polymerphysik (1)
- Polyzwitterion (1)
- Post-Modifikationen (1)
- Priming (1)
- Privathaushalte (1)
- Probabilistic Seismic Hazard and Risk Assessment (1)
- Produktion (1)
- Pronomen (1)
- Propeller (1)
- Proxyunsicherheit (1)
- Proxyverständnis (1)
- Prozessanalyse (1)
- Prozessausführung (1)
- Prozessmodelle (1)
- Prozessmodellierung (1)
- Quantenfeldtheorie (1)
- Quantengravitation (1)
- Quantum Dots (1)
- ROMP (1)
- Radiokarbondatierung (1)
- Radiosensibilisator (1)
- Randwertprobleme (1)
- Rare and Unseasonal Flood (1)
- Recurrence Plots (1)
- Reflexionsseismik (1)
- Reflexivpronomen (1)
- Regelung (1)
- Rekurrenzplot (1)
- Requisit (1)
- Resonanz-Raman-Spektroskopie (1)
- Risiko (1)
- Rumpfmuskulatur (1)
- Russian (1)
- Russisch (1)
- Röntgenbeugung (1)
- SAR (1)
- SFA (1)
- SMT (SAT Modulo Theories) (1)
- SWIM (1)
- Saccharomyces cerevisiae (1)
- Saprolit (1)
- Satzverarbeitung (1)
- Schatten eines Schwarzen Lochs (1)
- Schnee (1)
- Schulmaterial (1)
- Schwarzes Loch (1)
- Schwingungsaufgelöste UV/VIS-Spektroskopie (1)
- Sedimenttransportsystem (1)
- Seespiegelschwankungen (1)
- Selbst-Adaptive Software (1)
- Selbstorganisation (1)
- Sequenzierung (1)
- Sequenzierung der nächsten Generation (1)
- Shadowgraphie (1)
- Shadowgraphy (1)
- Sicherheit (1)
- Signalweiterleitung (1)
- Silika Partikel (1)
- Simulationen (1)
- Simulationsmodelle (1)
- Software-Evolution (1)
- Sonnenaktivität (1)
- Sonnenkorona (1)
- South America (1)
- Spalteneruption (1)
- Speicheranwendungen (1)
- Sprachverarbeitung (1)
- Sprachwissenschaft (1)
- Sri Lanka (1)
- Stakeholdereinbindung (1)
- Standardsetzungsverfahren (1)
- Stapelverarbeitung (1)
- Starkregen (1)
- Stoßquerschnitt (1)
- Structure elucidation (1)
- Strukturaufklärung (1)
- Strukturdynamik (1)
- Supramolekular (1)
- Symbolische Regression (1)
- Synchronisation von Ereignissen (1)
- Syngas Hydrogenation (1)
- Syngashydrierung (1)
- Syntax (1)
- Systembiologie (1)
- Szenenbetrachtung (1)
- Südamerika (1)
- Tagalog acquisition (1)
- Taifune (1)
- Tandemmassenspektrometrie (1)
- Target of Rapamycin kinase (1)
- Telemetrie (1)
- Temperaturproxy (1)
- Teukolsky Gleichung (1)
- Teukolsky equations (1)
- Teukolsky master equation (1)
- Teukolsky-Gleichungen (1)
- Theory of Mind (1)
- Therapie (1)
- Thermochronologie (1)
- Time Embedded Phase Space (1)
- Turkish migrant organisations (1)
- Türkische Vereine (1)
- Ultrafast X-ray diffraction (1)
- Ultraschnelle Röntgenbeugung (1)
- Umweltreaktion (1)
- United Nations (1)
- Unterrichtswerkzeuge (1)
- Vansee (1)
- Variation (1)
- Vegetation (1)
- Vegetationsmodellierung (1)
- Vereinte Nationen (1)
- Verhaltensprobleme (1)
- Verhandlungen (1)
- Verhandlungsmanagement (1)
- Verhandlungsperformance (1)
- Verhandlungsperformancebasierte Vergütung (1)
- Verhandlungsphasen (1)
- Verhandlungsstile (1)
- Verhandlungszufriedenheit (1)
- Verständnis (1)
- Verteidigung (1)
- Verwitterungsfeedback (1)
- Veränderungsanalyse (1)
- Videoanalyse (1)
- Virtual Reality (1)
- Visual Analytics (1)
- Visual World (1)
- Visualisierung (1)
- Visuelle Aufmerksamkeit (1)
- Vorhersage (1)
- Vulkaniklastika (1)
- Vulkanologie (1)
- Wachstumssignale (1)
- Wahrgenommene Authentizität (1)
- Warnung (1)
- Wasser auf Aluminiumoxid (1)
- Wassergütemodellierung (1)
- Wavelet (1)
- Wearable (1)
- Wirbelsäule (1)
- Wirtschaftsnetzwerk (1)
- Worterkennung (1)
- Wortstellung (1)
- Wärmetransport (1)
- X-ray diffraction (1)
- X-ray magnetic circular dichroism (XMCD) (1)
- Zeitabhängige Dichtefunktionaltheorie (1)
- Zentralanden (1)
- Zuweisung thematischer Rollen (1)
- acceleration (1)
- acoustic waves (1)
- acquisition (1)
- active source data (1)
- actuator (1)
- adaptation (1)
- adipose tissue (1)
- affect (1)
- ageing (1)
- agricultural landscapes (1)
- aktive Quelldaten (1)
- akustische Wellen (1)
- all-optical helicity dependent switching (1)
- alluvial channel morphology (1)
- altered shoot branching (1)
- alternative variety (1)
- alumina (1)
- ambiguity (1)
- amino acids (1)
- amorphes Calciumcarbonat (1)
- anaphors (1)
- anisotropic colloids (1)
- anomaly detection (1)
- aphasia (1)
- aquatic ecosystem (1)
- aquatische Ökosysteme (1)
- arabidopsis (1)
- arctic (1)
- artificial transcription factor (1)
- artifizielle Transkriptionsfaktoren (1)
- assembly (1)
- astro-particle physics (1)
- astronomy (1)
- astroparticle (1)
- asymmetric (1)
- asymmetrisch (1)
- azobenzene surfactant (1)
- azobenzolhaltige Tenside (1)
- basaltic volcanoes (1)
- batch activity (1)
- batch processing (1)
- begrenzte Polymerisation (1)
- bilingual (1)
- bilingualism (1)
- biocatalysis (1)
- biofilm (1)
- biophysics (1)
- biosensor (1)
- black hole (1)
- black hole shadows (1)
- block copolymers (1)
- boundary value problems (1)
- business process (1)
- business process management (1)
- cancer cachexia (1)
- carbon material (1)
- carbon supports (1)
- catalyst functionalization (1)
- catchment hydrology (1)
- chain of semigroups (1)
- change detection (1)
- charnockite (1)
- chemical weathering (1)
- chemische Verwitterung (1)
- chemokines (1)
- chemotaxis (1)
- children (1)
- classroom material (1)
- climate (1)
- climate extreme events (1)
- climate global and local patterns (1)
- climate physics (1)
- climate policy (1)
- climate reconstruction (1)
- clustering (1)
- cobalt nanoparticles (1)
- colloid chemistry (1)
- combinatorial optimization (1)
- communication (1)
- complex network (1)
- complex networks (1)
- comprehension (1)
- computational design (1)
- computational modeling (1)
- computer graphics (1)
- computergestützte Gestaltung (1)
- conduct problems (1)
- confined polymerization (1)
- constraints (1)
- control (1)
- controlled polymerization (1)
- coordination problems (1)
- correlation function (1)
- cosmogenic nuclide dating (1)
- cosmogenic nuclides (1)
- creativity (1)
- critical exponent (1)
- critical zone (1)
- cross-linguistic (1)
- cross-linguistisch (1)
- cyanobacteria (1)
- cycle-averaged tilt angle (1)
- cytokines (1)
- data processing (1)
- data profiling (1)
- decision management (1)
- decision mining (1)
- decision models (1)
- defense (1)
- design principles (1)
- diallel (1)
- diamondoid (1)
- didaktische Rekonstruktion (1)
- dielectric non-linearities (1)
- disjunction of identities (1)
- dissociative electron attachment (1)
- distributed computation (1)
- disulfide (1)
- domain-specific modeling (1)
- dynamical systems (1)
- dynamics (1)
- dysprosium (1)
- dünne Filme (1)
- early adolescence (1)
- economic network (1)
- economies of affect (1)
- edge boundary value problems (1)
- educational reconstruction (1)
- eingebettete Systeme (1)
- electrical muscle stimulation (1)
- elektrische Muskelstimulation (1)
- embedded systems (1)
- emotion (1)
- emperical potential structure refinement (1)
- energy estimate (1)
- energy storage (1)
- entity linking (1)
- entrepreneurship (1)
- environmental response (1)
- enzyme (1)
- enzymes (1)
- erosion (1)
- eukaryotes (1)
- evangelicalism (1)
- event coincidence analysis (1)
- event normalization (1)
- exekutive Funktionen (1)
- experiment (1)
- extreme Ereignisse (1)
- extreme Klimaereignisse (1)
- extreme events (1)
- eye movements (1)
- eye-tracing (1)
- fabrication (1)
- feldspar (1)
- ferroelectric polymers (1)
- fest-flüssig Grenzfläche (1)
- financial integration (1)
- finanzielle Integration (1)
- finger counting (1)
- firn (1)
- fiscal policy (1)
- fissure eruption (1)
- fluvial fill terraces (1)
- freedom (1)
- frühe Adoleszenz (1)
- functional dependencies (1)
- functional ecology (1)
- fungi (1)
- funktionale Abhängigkeiten (1)
- funktionelle Ökologie (1)
- gadolinium (1)
- gamma rays (1)
- gamma-rays (1)
- gefangene lichtartige Kurven (1)
- genetic programming (1)
- geohazards (1)
- geology (1)
- geometry (1)
- geomorphology (1)
- glaciers (1)
- globale und lokale Muster des Klimas (1)
- glucose oxidation (1)
- gold-carbon catalysts (1)
- green growth (1)
- green investment (1)
- ground-motion models (1)
- ground-motion variability (1)
- group field theory (1)
- grüne Investitionen (1)
- grünes Wachstum (1)
- gut microbiota (1)
- halophiles (1)
- haptic feedback (1)
- haptisches Feedback (1)
- heat transport (1)
- helicene (1)
- heteroatom modification (1)
- heterogene Agenten (1)
- heterogeneous agents (1)
- hierarchical porosity (1)
- hierarchische Porosität (1)
- higher-order effects (1)
- hillslope hydrology (1)
- history and philosophy of astronomy (1)
- hollow microfibers (1)
- horizontal gene transfer (1)
- horizontaler Gentransfer (1)
- hybrid (1)
- hybrid breakdown (1)
- hybrid incompatibility (1)
- hybride Inkompatibilität (1)
- hybrides Problemlösen (1)
- hydro-meteorological risk (1)
- hydro-meteorologische Risiken (1)
- hydrogels (1)
- hyporheic zone (1)
- hyporheische Zone (1)
- ice core (1)
- identification (1)
- in-memory (1)
- in-stream processes (1)
- inclusion dependencies (1)
- incomplete information (1)
- incomplete markets (1)
- inflammation (1)
- informatische Bildung im Sekundarbereich (1)
- inheritance (1)
- instability (1)
- institutional complexity (1)
- intergalaktisches Medium (IGM) (1)
- international organizations; food security governance; inter-organizational relations; overlap; perception (1)
- intestinal inflammation (1)
- invasion (1)
- ionic liquids (1)
- ionization energy (1)
- ionization potential (1)
- iron-carbon nanotube catalysts (1)
- isotope variations (1)
- kolloidchemie (1)
- kombinatorische Optimierung (1)
- kontrollierte Polymerisation (1)
- kosmogene Nuklide (1)
- kritische Zone (1)
- kritischer Exponent (1)
- lacustrine record (1)
- lake-level change (1)
- lakustrine Abfolge (1)
- land use change (1)
- landing (1)
- landslides (1)
- langsam rotierende Kerr-Raumzeiten (1)
- language processing (1)
- laserscanning (1)
- lava fountains (1)
- lichenometry (1)
- licht-getrieben (1)
- light-driven (1)
- lignin (1)
- linguistics (1)
- liquid-phase catalysis (1)
- load (1)
- lobbying (1)
- machine-learning (1)
- macrocycles (1)
- magnetic and phononic system (1)
- magnetic polarisation direction (1)
- magnetische Polarisationsrichtung (1)
- magnetischem Röntgendichroismus (XMCD) (1)
- magnetisches und phononisches System (1)
- magnetohydrodynamic (1)
- magnetostriction (1)
- magnetotellurics (1)
- manifolds with edge (1)
- manifolds with singularities (1)
- materials science (1)
- mehrstufiger Angriff (1)
- memory applications (1)
- mental number representations (1)
- mentale Zahlenrepräsentation (1)
- metabolites (1)
- metacrate (1)
- metadata (1)
- metal organic framework (1)
- metallorganischen Gerüstverbindungen (1)
- metamaterials (1)
- micro swimmer (1)
- microbial carbon turnover (1)
- microbial interactions (1)
- microcontact printing (1)
- microorganisms (1)
- microparticles (1)
- microswimmers (1)
- migrant sport clubs (1)
- migration (1)
- mikrobielle Interaktionen (1)
- mikrobieller Kohlenstoffkreislauf (1)
- mineral weathering reactions (1)
- mittlere Kindheit (1)
- mixed-effect analysis (1)
- mixture models (1)
- mobile mapping (1)
- model-driven engineering (1)
- modellgetriebene Entwicklung (1)
- modelling (1)
- monoclonal antibodies (1)
- monoklonale Antikörper (1)
- morphology (1)
- motility (1)
- motion and force (1)
- movemen ecology (1)
- multi-messenger astronomy (1)
- multi-step attack (1)
- multiferroic heterostructure (1)
- multiferroischen Heterostruktur (1)
- multiple sclerosis (1)
- multiscale network (1)
- nachhaltige Energiespeichermaterialien (1)
- nanocomposite (1)
- nanoparticles (1)
- natural dams (1)
- natural hazard (1)
- necrosis (1)
- neo-normative control (1)
- network security (1)
- neurodegeneration (1)
- neuroinflammation (1)
- neutron reflectometry (1)
- next generation sequencing (1)
- nicht additiv (1)
- nichtlineare Geowissenschaften (1)
- nichtstationäres Hochwasserrisiko (1)
- nickel-carbon catalysts (1)
- noise (1)
- non-equilibrium (1)
- nonadditive (1)
- novelty detection (1)
- nudging (1)
- numerical cognition (1)
- numerische Kognition (1)
- nutrient retention (1)
- nutrients (1)
- nutzergenerierte Inhalte (1)
- obere kritische Lösetemperatur (1)
- organic matter (1)
- organisches Material (1)
- organization (1)
- orthogroup (1)
- outlier detection (1)
- overweight (1)
- paleoclimate (1)
- paleovegetation (1)
- particles (1)
- passive voice (1)
- patchy particles (1)
- pathway engineering (1)
- peacekeeping (1)
- perylene (1)
- phosphoproteomics (1)
- photo ionization (1)
- photo-emission electron microscopy (PEEM) (1)
- photochemistry (1)
- photoelectrochemical sensor (1)
- photoelectron spectroscopy (1)
- physical Computing (1)
- physical computing (1)
- plant community (1)
- plasmonics (1)
- pluvial flooding (1)
- polyelectrolytes (1)
- polymer (1)
- polymer chemistry (1)
- polymer physics (1)
- polymers (1)
- polyzwitterion (1)
- population (1)
- post-depositional (1)
- post-modification (1)
- prediction (1)
- predictive modeling (1)
- priming (1)
- private households (1)
- probabilistic (1)
- probabilistic approach (1)
- probabilistischer Ansatz (1)
- process execution (1)
- process modeling (1)
- process models (1)
- process tracing (1)
- processing (1)
- production (1)
- programmable matter (1)
- programmierbare Materie (1)
- pronouns (1)
- propellers (1)
- props (1)
- proxy uncertainty (1)
- proxy understanding (1)
- pseudo-differential equation (1)
- pseudo-differentielle Gleichungen (1)
- quantum dots (1)
- quantum field theory (1)
- quantum gravity (1)
- radiocarbon age dating (1)
- radiosensitizer (1)
- rare-earth metals (1)
- real-time rendering (1)
- reflection seismics (1)
- reflexives (1)
- rein optisches helizitätsabhängiges Schalten (AO-HDS) (1)
- resonance Raman spectroscopy (1)
- resonant soft x-ray diffraction (1)
- resonante weiche Röntgenbeugung (1)
- ring-opening polymerization (1)
- ringöffnende Polymerisation (1)
- riparian zone (1)
- risk (1)
- river floods (1)
- rock glaciers (1)
- runtime models (1)
- saprolite (1)
- scanpaths (1)
- scene viewing (1)
- secondary computer science education (1)
- security (1)
- sediment-routing system (1)
- seismic attenuation (1)
- seismic noise (1)
- seismic tomography (1)
- seismische Dämpfung (1)
- seismische Tomographie (1)
- seismogene Kopplungszone (1)
- seismogenic coupling zone (1)
- selbst-getriebene Partikel (1)
- self-adaptive software (1)
- self-assembly (1)
- self-propelled particle (1)
- self-regulation (1)
- seltenes und saisonunübliches Hochwasser (1)
- semigroup theory (1)
- sentence processing (1)
- sequencing (1)
- serverseitiges 3D-Rendering (1)
- serverside 3D rendering (1)
- service-oriented architectures (1)
- serviceorientierte Architekturen (1)
- shape-memory effect (1)
- shape-memory polymer (1)
- sichtbares Licht Photokatalyse (1)
- signal propagation (1)
- silica particles (1)
- slowly rotating Kerr spacetimes (1)
- snow (1)
- soft matter physics (1)
- software evolution (1)
- solar activity (1)
- solar corona (1)
- solar eruption (1)
- solare Eruption (1)
- solid-liquid interface (1)
- solvo-thermal annealing (1)
- sortase-mediated ligation (1)
- species coexistence (1)
- spine (1)
- stabile Isotope (1)
- stabile Isotope Tracer (1)
- stable isotope tracer (1)
- stable isotopes (1)
- stakeholder involvement (1)
- standard-setting (1)
- starker Halbverband von Halbgruppen (1)
- strain (1)
- strong semilattice of semigroups (1)
- structural dynamics (1)
- sunspot group tilt angle (1)
- supramolecular (1)
- surface (1)
- surface flow (1)
- surface science (1)
- sustainability transitions (1)
- sustainable energy storage materials (1)
- symbolic regression (1)
- syntax (1)
- synthetic biology (1)
- synthetic seismograms (1)
- synthetische Biologie (1)
- synthetische Seismogramme (1)
- systems biology (1)
- tandem mass spectrometry (1)
- telemetry (1)
- temperature proxy (1)
- temperature variability (1)
- text mining (1)
- thematic role assignment (1)
- theoretical chemistry (1)
- theoretische Chemie (1)
- thermochronology (1)
- thermoresponsiv (1)
- thermoresponsive (1)
- thin films (1)
- time-dependent density functional theory (1)
- time-resolved x-ray diffraction (1)
- tools for teaching (1)
- trapping (1)
- treatment (1)
- trunk muscles (1)
- two-dimensional (1)
- typhoons (1)
- unvollständige Information (1)
- unvollständige Märkte (1)
- upper critical solution temperature (1)
- user-generated content (1)
- variation (1)
- varved lake sediments (1)
- vegetation (1)
- vegetation modeling (1)
- verteilte Berechnung (1)
- veränderte Triebverzweigung (1)
- vibrationally resolved electronic spectroscopy (1)
- video analysis (1)
- virtual reality (1)
- visible light photocatalysis (1)
- visual analytics (1)
- visual attention (1)
- visual world (1)
- visualization (1)
- voice (1)
- volcaniclastics (1)
- volcanology (1)
- warning (1)
- warvierte Seesedimente (1)
- water at alumina (1)
- water quality modelling (1)
- wavelet (1)
- wearables (1)
- weathering feedback (1)
- word order (1)
- working memory (1)
- zeitaufgelöste Röntgenbeugung (1)
- Änderungen des Hochwassers (1)
- Östliches Karoo-Becken (1)
- Überschwemmungen (1)
- ökonomische Auswirkungen (1)
Institute
- Institut für Physik und Astronomie (28)
- Institut für Biochemie und Biologie (27)
- Institut für Chemie (24)
- Institut für Geowissenschaften (23)
- Extern (14)
- Hasso-Plattner-Institut für Digital Engineering GmbH (14)
- Wirtschaftswissenschaften (8)
- Department Psychologie (6)
- Department Linguistik (5)
- Institut für Ernährungswissenschaft (5)
Be Creative, Now!
(2018)
Purpose – This thesis set out to explore, describe, and evaluate the reality behind the rhetoric of freedom and control in the context of creativity. The overarching subject is concerned with the relationship between creativity, freedom, and control, considering freedom is also seen as an element of control to manage creativity.
Design/methodology/approach – In-depth qualitative data gathered from at two innovative start-ups. Two ethnographic studies were conducted. The data are based on participatory observations, interviews, and secondary sources, each of which included a three months field study and a total of 41 interviews from both organizations.
Findings – The thesis provides explanations for the practice of freedom and the control of creativity within organizations and expands the existing theory of neo-normative control. The findings indicate that organizations use complex control systems that allow a high degree of freedom that paradoxically leads to more control. Freedom is a cover of control, which in turn leads to creativity. Covert control even results in the responsibility to be creative outside working hours.
Practical implications – Organizations, which rely on creativity might use the results of this thesis. Positive workplace control of creativity provides both freedom and structure for creative work. While freedom leads to organizational members being more motivated and committing themselves more strongly to their and the organization’s goals, and a specific structure also helps to provide the requirements for creativity.
Originality/value – The thesis provides an insight into an approach to workplace control, which has mostly neglected in creativity research and proposes a modified concept of neo-normative control. It serves to provide a further understanding of freedom for creativity and to challenge the liberal claims of new control forms.
The aim of this doctoral thesis was to establish a technique for the analysis of biomolecules with infrared matrix-assisted laser dispersion (IR-MALDI) ion mobility (IM) spectrometry. The main components of the work were the characterization of the IR-MALDI process, the development and characterization of different ion mobility spectrometers, the use of IR-MALDI-IM spectrometry as a robust, standalone spectrometer and the development of a collision cross-section estimation approach for peptides based on molecular dynamics and thermodynamic reweighting.
First, the IR-MALDI source was studied with atmospheric pressure ion mobility spectrometry and shadowgraphy. It consisted of a metal capillary, at the tip of which a self-renewing droplet of analyte solution was met by an IR laser beam. A relationship between peak shape, ion desolvation, diffusion and extraction pulse delay time (pulse delay) was established. First order desolvation kinetics were observed and related to peak broadening by diffusion, both influenced by the pulse delay. The transport mechanisms in IR-MALDI were then studied by relating different laser impact positions on the droplet surface to the corresponding ion mobility spectra. Two different transport mechanisms were determined: phase explosion due to the laser pulse and electrical transport due to delayed ion extraction. The velocity of the ions stemming from the phase explosion was then measured by ion mobility and shadowgraphy at different time scales and distances from the source capillary, showing an initially very high but rapidly decaying velocity. Finally, the anatomy of the dispersion plume was observed in detail with shadowgraphy and general conclusions over the process were drawn.
Understanding the IR-MALDI process enabled the optimization of the different IM spectrometers at atmospheric and reduced pressure (AP and RP, respectively). At reduced pressure, both an AP and an RP IR-MALDI source were used. The influence of the pulsed ion extraction parameters (pulse delay, width and amplitude) on peak shape, resolution and area was systematically studied in both AP and RP IM spectrometers and discussed in the context of the IR-MALDI process. Under RP conditions, the influence of the closing field and of the pressure was also examined for both AP and RP sources. For the AP ionization RP IM spectrometer, the influence of the inlet field (IF) in the source region was also examined. All of these studies led to the determination of the optimal analytical parameters as well as to a better understanding of the initial ion cloud anatomy.
The analytical performance of the spectrometer was then studied. Limits of detection (LOD) and linear ranges were determined under static and pulsed ion injection conditions and interpreted in the context of the IR-MALDI mechanism. Applications in the separation of simple mixtures were also illustrated, demonstrating good isomer separation capabilities and the advantages of singly charged peaks. The possibility to couple high performance liquid chromatography (HPLC) to IR-MALDI-IM spectrometry was also demonstrated. Finally, the reduced pressure spectrometer was used to study the effect of high reduced field strength on the mobility of polyatomic ions in polyatomic gases.
The last focus point was on the study of peptide ions. A dataset obtained with electrospray IM spectrometry was characterized and used for the calibration of a collision cross-section (CCS) determination method based on molecular dynamics (MD) simulations at high temperature. Instead of producing candidate structures which are evaluated one by one, this semi-automated method uses the simulation as a whole to determine a single average collision cross-section value by reweighting the CCS of a few representative structures. The method was compared to the intrinsic size parameter (ISP) method and to experimental results. Additional MD data obtained from the simulations was also used to further analyze the peptides and understand the experimental results, an advantage with regard to the ISP method. Finally, the CCS of peptide ions analyzed by IR-MALDI were also evaluated with both ISP and MD methods and the results compared to experiment, resulting in a first validation of the MD method. Thus, this thesis brings together the soft ionization technique that is IR-MALDI, which produces mostly singly charged peaks, with ion mobility spectrometry, which can distinguish between isomers, and a collision cross-section determination method which also provides structural information on the analyte at hand.
Systemic inflammation is a hallmark of cancer cachexia. Among tumor-host interactions, the white adipose tissue (WAT) is an important contributor to inflammation as it suffers morphological reorganization and lipolysis, releasing free fatty acids (FA), bioactive lipid mediators (LM) and pro-inflammatory cytokines, which accentuate the activation of pro-inflammatory signaling pathways and the recruitment of immune cells to the tissue. This project aimed to investigate which inflammatory factors are involved in the local adipose tissue inflammation and what is the influence of such factors upon enzymes involved in FA or LM metabolism in healthy individuals (Control), weight stable gastro-intestinal cancer patients (WSC) and cachectic cancer patients (CC). The results demonstrated that the inflammatory signature of systemic inflammation is different from local adipose tissue inflammation. The systemic inflammation of the cachectic cancer patients was characterized by higher levels of circulating saturated fatty acids (SFA), tumor-necrosis-factor-α (TNF-α), interleukins IL-6, IL-8 and CRP while levels of polyunsaturated fatty acids (PUFAs), especially n3-PUFAs, were lower in CC than in the other groups. In vitro and in adipose tissue explants, pro-inflammatory cytokines and SFAs were shown to increase the chemokines IL-8 and CXCL10 that were found to be augmented in adipose tissue inflammation in CC which was more profound in the visceral adipose tissue (VAT) than in subcutaneous adipose tissue (SAT). Systemic inflammation was negatively associated with the expression of PUFA synthesizing enzymes, though gene and protein expression did hardly differ between groups. The effects of inflammatory factors on enzymes in the whole tissue could have been masked by differentiated modulation of the diverse cell types in the same tissue. In vitro experiments showed that the expression of FA-modifying enzymes such as desaturases and elongases in adipocytes and macrophages was regulated into opposing directions by TNF-α, IL-6, LPS or palmitate. The higher plasma concentration of the pro-resolving LM resolvin D1 in CC cannot compensate the overall inflammatory status and the results indicate that inflammatory cytokines interfere with synthesis pathways of pro-resolving LM. In summary, the data revealed a complex inter-tissue and inter-cellular crosstalk mediated by pro-inflammatory cytokines and lipid compounds enhancing inflammation in cancer cachexia by feed-forward mechanisms.
The solar activity and its consequences affect space weather and Earth’s climate. The solar activity exhibits a cyclic behaviour with a period of about 11 years. The solar cycle properties are governed by the dynamo taking place in the interior of the Sun, and they are distinctive. Extending the knowledge about solar cycle properties into the past is essential for understanding the solar dynamo and forecasting space weather. It can be acquired through the analysis of historical sunspot drawings. Sunspots are the dark areas, which are associated with strong magnetic fields, on the solar surface. Sunspots are the oldest and longest available observed features of solar activity.
One of the longest available records of sunspot drawings is the collection by Samuel Heinrich Schwabe during 1825–1867. The sunspot sizes measured from digitized Schwabe drawings are not to scale and need to be converted into physical sunspot areas. We employed a statistical approach assuming that the area distribution of sunspots was the same in the 19th century as it was in the 20th century. Umbral areas for about 130 000 sunspots observed by Schwabe were obtained. The annually averaged sunspot areas correlate reasonably well with the sunspot number. Tilt angles and polarity separations of sunspot groups were calculated assuming them to be bipolar. There is, of course, no polarity information in the observations. We derived an average tilt angle by attempting to exclude unipolar groups with a minimum separation of the two surmised polarities and an outlier rejection method, which follows the evolution of each group and detects the moment, when it turns unipolar as it decays. As a result, the tilt angles, although displaying considerable natural scatter, are on average 5.85° ± 0.25°, with the leading
polarity located closer to the equator, in good agreement with tilt angles obtained from 20th century data sets. Sources of uncertainties in the tilt angle determination are discussed and need to be addressed whenever different data sets are combined.
Digital images of observations printed in the books Rosa Ursina and Prodromus pro sole mobili by Christoph Scheiner, as well as the drawings from Scheiner’s letters to Marcus Welser, are analyzed to obtain information on the positions and sizes of sunspots that appeared before the Maunder minimum. In most cases, the given orientation of the ecliptic is used to set up the heliographic coordinate system for the drawings. Positions and sizes are measured manually displaying the drawings on a computer screen. Very early drawings have no indication of the solar orientation. A rotational matching using common spots of adjacent days is used in some cases, while in other cases, the assumption that images were aligned with a zenith–horizon coordinate system appeared to be the most likely. In total, 8167 sunspots were measured. A distribution of sunspot latitudes versus time (butterfly diagram) is obtained for Scheiner’s observations. The observations of 1611 are very inaccurate, but the drawings of 1612 have at least an indication of the solar orientation, while the remaining part of the spot positions from 1618–1631 have good to very good accuracy. We also computed 697 tilt angles of apparent bipolar sunspot groups, which were observed in the period 1618–1631. We find that the average tilt angle of nearly 4° does not significantly differ from the 20th century values.
The solar cycle properties seem to be related to the tilt angles of sunspot groups, and it is an important parameter in the surface flux transport models. The tilt angles of bipolar sunspot groups from various historical sets of solar drawings including from Schwabe and Scheiner are analyzed. Data by Scheiner, Hevelius, Staudacher, Zucconi, Schwabe, and Spörer deliver a series of average tilt angles spanning a period of 270 years, in addition to previously found values for 20th-century data obtained by other authors. We find that the average tilt angles before the Maunder minimum were not significantly different from modern values. However, the average tilt angles of a period 50 years after the Maunder minimum, namely for cycles 0 and 1, were much lower and near zero. The typical tilt angles before the Maunder minimum suggest that abnormally low tilt angles were not responsible for driving the solar cycle into a grand minimum.
With the Schwabe (1826–1867) and Spörer (1866–1880) sunspot data, the butterfly diagram of sunspot groups extends back till 1826. A recently developed method, which separates the wings of the butterfly diagram based on the long gaps present in sunspot group occurrences at different latitudinal bands, is used to separate the wings of the butterfly diagram. The cycle-to-cycle variation in the start (F), end (L), and highest (H) latitudes of the wings with respect to the strength of the wings are analyzed. On the whole, the wings of the stronger cycles tend to start at higher latitudes and have a greater extent. The time spans of the wings and the time difference between the wings in the northern hemisphere display a quasi-periodicity of 5–6 cycles. The average wing overlap is zero in the southern hemisphere, whereas it is 2–3 months in the north. A marginally significant oscillation of about 10 solar cycles is found in the asymmetry of the L latitudes. This latest, extended database of butterfly wings provides new observational constraints, regarding the spatio-temporal distribution of sunspot occurrences over the solar cycle, to solar dynamo models.
This thesis investigates the comprehension of the passive voice in three distinct populations. First, the comprehension of passives by adult German speakers was studied, followed by an examination of how German-speaking children comprehend the structure. Finally, bilingual Mandarin-English speakers were tested on their comprehension of the passive voice in English, which is their L2. An integral part of testing the comprehension in all three populations is the use of structural priming. In each of the three distinct parts of the research, structural priming was used for a specific reason. In the study involving adult German speakers, productive and receptive structural priming was directly compared. The goal was to see the effect the two priming modalities have on language comprehension. In the study on German-acquiring children, structural priming was an important tool in answering the question regarding the delayed acquisition of the passive voice. Finally, in the study on the bilingual population, cross-linguistic priming was used to investigate the importance of word order in the priming effect, since Mandarin and English have different word orders in passive voice sentences.
Modeling and data analysis of large-scale atmosphere dynamics associated with extreme weather
(2018)
In the last decades the frequency and intensity of extreme weather events like heat waves and heavy rainfall have increased and are at least partly linked to global warming. These events can have a strong impact on agricultural and economic production and, thereby, on society. Thus, it is important to improve our understanding of the physical processes leading to those extreme events in order to provide accurate near-term and long-term forecasts. Thermodynamic drivers associated with global warming are well understood, but dynamical aspects of the atmosphere much less so. The dynamical aspects, while less important than the thermodynamic drivers in regards to large-scale and long-time averaged effects, play a critical role in the formation of extremes.
The overall aim of this thesis is to improve our understanding of patterns, variability and trends in the global atmospheric circulation under a changing climate. In particular, in this dissertation I developed two new data-driven methods to quantitatively describe the dynamics of jet streams, Hadley cells and storm tracks. In addition, I introduce and validate a new statistical-dynamical atmosphere model that can be used to efficiently model the large-scale circulation.
First, I developed a scheme based on the Dijkstra ‘shortest-path’ algorithm to identify jet stream cores. Using reanalysis data, I found a significant change in jet stream strength and position over the last decades: Specifically, a decrease in wind speeds and a spatial shift toward the poles. This work also shows that the splitting or merging of the polar front jet stream and the subtropical jet stream depends on the season and longitudinal position. In a follow-up study, I analyzed trends in the latitudinal position of the poleward edge of the Hadley cell and subtropical jet stream core for all longitudes. These trends depend strongly on longitude and thus the impacts of tropical expansion might be pronounced in some regions and absent in others.
The second approach was to develop an empirical forecast method for European and Mediterranean winter precipitation. This prediction algorithm innovatively incorporates the spatial patterns of predictors in autumn using clustering analyses. I identified the most important precursors (snow cover in Eurasia, Barents and Kara sea ice concentrations as well as sea surface temperature in the Atlantic and Mediterranean region) for the precipitation prediction. This forecast algorithm had higher forecast skills than conventionally employed methods such as Canonical Correlation Analysis or operational systems using climate models.
The last approach was to examine the atmospheric circulation using the novel statisticaldynamical atmosphere model Aeolus. First, I validated the model’s depiction of the largescale circulation in terms of Hadley circulation, jet streams, storm tracks and planetary waves. To do so, I performed a parameter optimization using simulated annealing. Next, I investigated the sensitivity of the large-scale circulation to three different temperature components: global mean temperature, meridional temperature gradient and zonal temperature gradient. The model experiment showed that the strength of the Hadley cell, storm tracks and jet streams depend almost linearly on both the global mean temperature and the meridional temperature gradient, whereas the zonal temperature gradient is shown to have little or no influence. The magnitude of planetary waves is clearly affected by all three temperature components. Finally, the width of the Hadley cell behaves nonlinearly with respect to all three temperature components.
These findings might have profound consequences for climate modeling of the Mediterranean region. The latitudinal poleward trend of the Hadley cell edge position might become stronger under climate change according to the results with Aeolus. These changes would lead to a substantial reduction of the winter precipitation in the Mediterranean region. In this case seasonal empirical forecast methods, like the clustering-based prediction scheme, will play an important role for forecasting seasonal droughts in advance such that water managers and politicians can mitigate impacts.
The ongoing trend of miniaturizing multifunctional devices, especially for minimally-invasive medical or sensor applications demands new strategies for designing the required functional polymeric micro-components or micro-devices. Here, polymers, which are capable of active movement, when an external stimulus is applied (e.g. shape-memory polymers), are intensively discussed as promising material candidates for realization of multifunctional micro-components. In this context further research activities are needed to gain a better knowledge about the underlying working principles for functionalization of polymeric micro-scale objects with a shape-memory effect. First reports about electrospun solid microfiber scaffolds, demonstrated a much more pronounced shape-memory effect than their bulk counterparts, indicating the high potential of electrospun micro-objects.
Based on these initial findings this thesis was aimed at exploring whether the alteration of the geometry of micro-scale electrospun polymeric objects can serve as suitable parameter to tailor their shape-memory properties. The central hypothesis was that different geometries should result in different degrees of macromolecular chain orientation in the polymeric micro-scale objects, which will influence their mechanical properties as well as thermally-induced shape-memory function. As electrospun micro-scale objects, microfiber scaffolds composed of hollow microfibers with different wall thickness and electrosprayed microparticles as well as their magneto-sensitive nanocomposites all prepared from the same polymer exhibiting pronounced bulk shape-memory properties were investigated. For this work a thermoplastic multiblock copolymer, named PDC, with excellent bulk shape-memory properties, associated with crystallizable oligo(ε-caprolactone) (OCL) switching domains, was chosen for the preparation of electrospun micro-scale objects, while crystallizable oligo(p-dioxanone) (OPDO) segments serve as hard domains in PDC.
In the first part of the thesis microfiber scaffolds with different microfiber geometries (solid or hollow with different wall thickness) were discussed. Hollow microfiber based PDC scaffolds were prepared by coaxial electrospinning from a 1, 1, 1, 3, 3, 3 hexafluoro-2-propanol (HFP) solution with a polymer concentration of 13% w·v-1. Here as a first step core-shell fiber scaffolds consisting of microfibers with a PDC shell and sacrificial poly(ethylene glycol) (PEG) core are generated. The hollow PDC microfibers were achieved after dissolving the PEG core with water. The utilization of a fixed electrospinning setup and the same polymer concentration of the PDC spinning solution could ensure the fabrication of microfibers with almost identical outer diameters of 1.4 ± 0.3 µm as determined by scanning electron microscopy (SEM). Different hollow microfiber wall thicknesses of 0.5 ± 0.2 and 0.3 ± 0.2 µm (analyzed by SEM) have been realized by variation of the mass flow rate, while solid microfibers were obtained by coaxial electrospinning without supplying any core solution. Differential scanning calorimetry experiments and tensile tests at ambient temperature revealed an increase in degree of OCL crystallinity form χc,OCL = 34 ± 1% to 43 ± 1% and a decrease in elongation of break from 800 ± 40% to 200 ± 50% associated with an increase in Young´s modulus and failture stress for PDC hollow microfiber scaffolds when compared with soild fibers. The observed effects were enhanced with decreasing wall thickness of the single hollow fibers. The shape-memory properties of the electrospun PDC scaffolds were quantified by cyclic, thermomechanical tensile tests. Here, scaffolds comprising hollow microfibers exhibited lower shape fixity ratios around Rf = 82 ± 1% and higher shape recovery ratios of Rr = 67 ± 1% associated to more pronounced relaxation at constant strain during the first test cycle and a lower switching temperature of Tsw = 33 ± 1 °C than the fibrous meshes consisting of solid microfibers. These findings strongly support the central hypothesis that different fiber geometries (solid or hollow with different wall thickness) in electrospun scaffolds result in different degrees of macromolecular chain orientation in the polymeric micro-scale objects, which can be applied as design parameter for tailoring their mechanical and shape-memory properties.
The second part of the thesis deals with electrosprayed particulate PDC micro-scale objects. Almost spherical PDC microparticles with diameters of 3.9 ± 0.9 μm (as determined by SEM) were achieved by electrospraying of HFP solution with a polymer concentration of 2% w·v-1. In contrast, smaller particles with sizes of 400 ± 100 nm or 1.2 ± 0.3 μm were obtained for the magneto-sensitive composite PDC microparticles containing 23 ± 0.5 wt% superparamagnetic magnetite nanoparticles (mNPs). All prepared PDC microparticles exhibited a similar overall crystallinity like the PDC bulk material as analyzed by DSC. AFM nanoindentation results revealed no influence of the nanofiller incorporation on the local mechanical properties represented by the reduced modulus determined for pure PDC microparticles and magneto-sensitive composite PDC microparticles with similar diameters around 1.3 µm. It was found that the reduced modulus of the nanocomposite microparticles increased substantially with decreasing particles size from 2.4 ± 0.9 GPa (1.2 µm) to 11.9 ± 3.1 GPa (0.4 µm), which can be related to a higher orientation of the macromolecules at the surface of smaller sized microparticles. The magneto-sensitivity of such nanocomposite microparticles could be demonstrated in two aspects. One was by attracting/collecting the composite micro-objects with an external permanent magnet. The other one was by a inductive heating to 44 ± 1 °C, which is well above the melting transition of the OCL switching domains, when compacted to a 10 x 10 mm2 film with a thickness of 10 µm and exposed to an alternating magnet field with an magnetic field strength of 30 kA·m-1. Both functions are of great relevance for designing next generation drug delivery systems combining targeting and on demand release.
By a compression approach shape-memory functionalization of individual microparticles could be realized. Here different programming pressures and compression temperatures were applied. The shape-recovery capability of the programmed PDC microparticles was quantified by online and off-line heating experiments analyzed via microscopy measurement. The obtained shape-memory properties were found to be strongly depending on the applied programming pressure and temperature. The best shape-memory performance with a high shape recovery rate of about Rr = 80±1% was obtained when a low pressure of 0.2 MPa was applied at 55 °C. Finally, it was demonstrated that PDC microparticles can be utilized as micro building parts for preparation of a macroscopic film with temporary stability by compression of a densely packed array of PDC microparticles at 60 °C followed by subsequent cooling to ambient temperature. This film disintegrates into individual microparticles upon heating to 60 °C. Based on this technology the design of stable macroscopic release systems can be envisioned, which can be easily fixed at the site of treatment (i.e. by suturing) and disintegrate on demand to microparticles facilitating the drug release.
In summary, the results of this thesis could confirm the central hypothesis that the variation of the geometry of polymeric micro-objects is a suitable parameter to adjust their shape-memory performance by changing the degree of macromolecular chain orientation in the specimens or by enabling new functions like on demand disintegration. These fundamental findings might be relevant for designing novel miniaturized multifunctional polymer-based devices.
Synchrotron-based angle-resolved time-of-flight electron spectroscopy for dynamics in dichalogenides
(2018)
Samarium hexaboride
(2018)
On a small scale
(2018)
This study argues that micro relations matter in peacekeeping. Asking what makes the implementation of peacekeeping interventions complex and how complexity is resolved, I find that formal, contractual mechanisms only rarely effectively reduce complexity – and that micro relations fill this gap. Micro relations are personal relationships resulting from frequent face-to-face interaction in professional and – equally importantly – social contexts.
This study offers an explanation as to why micro relations are important for coping with complexity, in the form of a causal mechanism. For this purpose, I bring together theoretical and empirical knowledge: I draw upon the current debate on ‘institutional complexity’ (Greenwood et al. 2011) in organizational institutionalism as well as original empirical evidence from a within-case study of the peacekeeping intervention in Haiti, gained in ten weeks of field research. In this study, scholarship on institutional complexity serves to identify theoretical causal channels which guide empirical analysis. An additional, secondary aim is pursued with this mechanism-centered approach: testing the utility of Beach and Pedersen’s (2013) theory-testing process tracing.
Regarding the first research question – what makes the implementation of peacekeeping interventions complex –, the central finding is that complexity manifests itself in the dual role of organizations as cooperation partners and competitors for (scarce) resources, turf and influence. UN organizations, donor agencies and international NGOs implementing peacekeeping activities in post-conflict environments have chronic difficulty mastering both roles because they entail contradictory demands: effective cooperation requires information exchange, resource and responsibility-sharing as well as external scrutiny, whereas prevailing over competitors demands that organizations conceal information, guard resources, increase relative turf and influence, as well as shield themselves from scrutiny. Competition fuels organizational distrust and friction – and impedes cooperation.
How is this complexity resolved? The answer to this second research question is that deep-seated organizational competition is routinely mediated – and cooperation motivated – in micro relations and micro interaction. Regular, frequent face-to-face interaction between individual organizational members generates social resources that help to transcend organizational distrust and conflict, most importantly familiarity with each other, personal trust and belief in reciprocity. Furthermore, informal conflict mediation and control mechanisms – namely, open discussion, mutual monitoring in direct interaction and social exclusion – enhance solidarity and mutual support.