11615 research outputs found
Sort by
The phenology of Epilobium hirsutum L.: assessing marker compounds variability of a pharmaceutically important plant remedy
Full text linkBackground Epilobium hirsutum L. (Onagraceae), a perennial medicinal plant, has considerable pharmaceutical value due to its phenolic acids, flavonoids, and ellagitannins, including oenothein A and B. The plant is reported to have therapeutic benefits for several conditions, such as prostate gland, bladder, and hormonal disorders. This study aimed to provide evidence-based data on the chemical composition of the species over a 1-year cycle and define the optimal harvesting period, which is essential to ensure consistency and efficacy in plant-derived products.. Using HPLC and HPTLC methods, 11 pharmacologically active marker compounds were quantified in 78 samples collected every 2 weeks during 2023.Among the hydroxycinnamic acids, chlorogenic acid was dominant in samples from shaded habitats, with maximum accumulation in samples from leaves during the vegetative phase (up to 2.25 mg/g DW). Flavonoids such as isoquercitrin and hyperoside peaked in leaves from the lake shore and wet grassland habitats during flowering. Oenothein B, a major ellagitannin, showed the highest concentrations in wet grassland leaves during flowering (73.97 mg/g DW).This study is the first to integrate habitat, phenology, and plant part data to characterise seasonal dynamics of key marker compounds in E. hirsutum under natural east-part of the United Kingdom conditions. Shaded, moist habitats were found to promote higher biosynthesis of secondary metabolites, whereas open, dry conditions favoured biomass yield. Distinct seasonal patterns in the accumulation of β-hydroxycinnamic acids and ellagitannins provide insight into their physiological functions and potential pharmacological significance. By identifying the dynamics of marker compounds and optimal harvesting periods, the study provides a framework for sustainable industrial practices for pharmaceutical raw material production and supports standardisation in herbal production
In memoriam Prof. Dr. Jarich Hoekstra (1956–2024)
Full text linkNachruf auf Jarich Hoekstra, ehemaliger Professor für Friesisch und Leiter der Nordfriesischen Wörterbuchstelle am Institut für Skandinavistik, Frisistik und Allgemeine Sprachwissenschaft der Christian-Albrechts-Universität zu Kiel.Obituary for Jarich Hoekstra, former professor of Frisian and head of the North Frisian Dictionary Office at the Institute for Scandinavian Studies, Frisian Studies, and General Linguistics at Kiel University
»Ein zum Leben erwecktes Fossil«: Der Urweltmammutbaum im Alten Botanischen Garten zu Kiel
Full text linkDer Urweltmammutbaum (Metasequoia glyptostroboides) im Alten Botanischen Garten zu Kiel ist eines der ältesten Exemplare seiner Art in Europa. 1948 erhielt der Kieler Botaniker Hermann Jacobsen einen Setzling von Kronprinzessin Elizabeth als Geschenk, das bis heute fast dreißig Meter Höhe erreicht hat. Der Text zeichnet die botanische Entdeckungsgeschichte nach – von fossilen Funden über die Wiederentdeckung in China bis zur Verbreitung durch Stecklinge in Europa und Amerika. Der Kieler Baum steht zugleich für die kulturelle Bedeutung botanischer Gärten als inszenierte Landschaftsräume zwischen Wissenschaft, Bildung und ästhetischer Erfahrung. In dieser Wechselwirkung von historischer Pflanze, kuratorischem Kontext und individueller Wahrnehmung wird der Metasequoia als »zum Leben erwecktes Fossil« zum Bindeglied zwischen Naturgeschichte und Gegenwart. So fungiert er nicht nur als lebendiges Naturdenkmal, sondern auch als Träger von Zeit- und Kulturgeschichte der Christian-Albrechts-Universität zu Kiel.The dawn redwood (Metasequoia glyptostroboides) in Kiel’s Old Botanical Garden is among the oldest of its kind in Europe. In 1948, botanist Hermann Jacobsen received the seedling as a gift from Crown Princess Elizabeth, and today the tree has reached almost thirty meters in height. The article traces the history of its rediscovery – from fossil findings and the 1940s reappearance in China to its propagation and global distribution. The Kiel specimen also highlights the cultural role of botanical gardens as staged landscapes between science, education, and aesthetic experience. Within this interplay of historical plant, curatorial setting, and individual perception, the Metasequoia emerges as a »revived fossil« and a link between natural history and present time. Thus, it functions not only as a living natural monument but also as a bearer of temporal and cultural history at Kiel University
In memoriam Prof. Dr. Wolfgang Kersting (1946–2025)
Full text linkNachruf auf Wolfgang Kersting, ehemaliger Professor für Praktische Philosophie an der CAU.Obituary for Wolfgang Kersting, former professor of practical philosophy at Kiel University
Die Schwierigkeit und Möglichkeit von Toleranz: Unterschiedliche disziplinäre Perspektiven
Full text linkIn dem Sammelband werden erste Ergebnisse von Forschungsprojekten der von der Deutschen Forschungsgemeinschaft geförderten ›Forschungsgruppe Toleranz‹ einem größeren Publikum vorgestellt. Im Mittelpunkt steht das von Bernd Simon entwickelte ›Ablehnung-Respekt-Modell der Toleranz‹. Im Sinne dieses Modells wird Toleranz als durch Respekt gezähmte Ablehnung verstanden, bzw. als durch Ablehnung belasteter Respekt. Respekt bedeutet Gleichheitsanerkennung, d. h. abgelehnte Andere sind als andersartige Gleiche anzuerkennen. Was in der Theorie womöglich sehr abstrakt klingt, wird in den einzelnen Beiträgen dieses Sammelbandes konkreter, denn die beteiligten Wissenschaftler*innen überprüfen in ihren jeweiligen Projekten das Modell auf seine Tauglichkeit für oder Übertragbarkeit auf ihr jeweiliges Forschungsgebiet in den Fachgebieten Sozial- und Organisationspsychologie, Protestantische Theologie, Neuere Deutsche Literaturwissenschaft, Philosophie, Geschichte und Islamwissenschaft/Iranistik.This anthology presents the initial findings of research projects conducted by the ›Tolerance Research Unit‹, which is funded by the German Research Foundation (DFG), to a wider audience. The focus is on the ›Disapproval-Respect Model of Tolerance‹ developed by Bernd Simon. According to this model, tolerance is understood as disapproval tamed by respect, or as respect burdened by disapproval. Respect means recognition of equality – i.e., disapproved others are to be recognised as different but equal. What may sound very abstract in theory becomes more concrete in the individual contributions to this anthology, as the participating scholars examine the model in their respective projects for its suitability or transferability to their respective fields of research in Social and Organisational Psychology, Protestant Theology, Modern German Literature, Philosophy, History, and Islamic/Iranian Studies
Population Genomic Inference with the Ancestral Recombination Graph (ARG): Recombination Landscape and Ancestral State Reconstruction
Full text linkUnderstanding genetic variation within and among populations is a fundamental goal of population genetics, which aims to reconstruct evolutionary history shaped by mutation, selection, genetic drift and recombination. The ancestral recombination graph (ARG) connects the DNA sequences in a sample through historical coalescence and recombination events and contains the complex genealogical relationships between sampled individuals. By capturing these historical relationships, the ARG provides a robust framework for obtaining rich information to answer key population genetics questions, making it an increasingly influential tool in the field. In this thesis, we develop methods that utilize ARG for two applications: to (1) infer recombination map, (2) infer ancestral states, and estimate the unfolded site frequency spectrum (uSFS), demonstrating the applications of ARG in population genetic analysis. To infer the recombination map, we introduce a new framework tailored for small sample sizes, utilizing transitions of genealogies along the genome. Our approach is faster than the existing iSMC method for single diploid genomes but comes at some cost of accuracy. We develop the first outgroup-free method for ancestral state inference and uSFS estimation. We theoretically characterize when local genealogies contain—or fail to contain—ancestral state information. We evaluate how accurately the ancestral allele and uSFS are inferred when the ARGs are known and when different methods reconstruct ARGs. We apply our new method to simulated data under various scenarios and a human dataset to compare it to the outgroup-based method. Our method provides a powerful alternative or complementary method for polarization. Overall, this thesis explores the challenges and potential of using genome-wide genealogy information for population genetics analyses and contributes to advancing ARG-based inference methods
Reconstruction of the provenance of detrital sediments in the Skagerrak region over the past 150 years
Full text linkThe Skagerrak basin represents the main sink area for fine-grained sediments transported through the North Sea region. To trace the provenance of Skagerrak sediments and reconstruct the main sedimentary processes in the North Sea, radiogenic Sr, Nd, and Hf isotope signatures, as well as clay mineral compositions of the detrital clay fraction of surface sediment samples from the North Sea, the Scandinavian fjords, and the Baltic Sea, were measured. Additionally, to investigate the temporal variability in sediment supply from the predominant source areas and the changes in sedimentation over the past 150 years, Skagerrak sediment cores were analyzed using a time series of radiogenic isotopes, clay mineral compositions, grain-size distributions, and X-ray fluorescence (XRF) core scans. The spatial distribution of the geochemical characterization identifies the northern North Sea, southern North Sea, and Scandinavian fjords as the main sources of fine-grained sediments deposited in the central part of the Skagerrak. Seabed erosion at the Fladen Ground, located in the northern North Sea, supplies the Skagerrak with large amounts of clay-sized sediments, primarily controlled by the inflow of the Atlantic Current into this region. Contributions from mid-European rivers, such as the Elbe, Weser, and Ems, as well as the Baltic Sea, are only minor. Radiogenic isotope ratios and XRF data from Skagerrak sediment records indicate a shift since the second half of the 20th century, with reduced sediment supply from the southern North Sea and increased contributions from the northern North Sea. This shift is caused by an increase in storm frequency and intensity in the 1980s and 1990s, which amplified hydrodynamic conditions in the North Sea region. Strong westerly winds intensified the Atlantic inflow into the northern North Sea and Skagerrak Basin, enhancing seabed erosion in the Fladen Ground and increasing sediment supply from the northern North Sea
Nutrients in Kenya's Coastal Waters: Analyzing Sources, Pathways, and Ecological Implications
Full text linkCoastal ecosystems face increasing nutrient enrichment from human activities, threatening ecological health globally. This PhD study assessed anthropogenic nutrient dynamics in Kenya’s coastal waters, focusing on their influence on phytoplankton shifts and harmful algal bloom (HAB) risks. Combining field surveys, lab analyses, and literature reviews (August 2021–July 2022), the research revealed elevated nutrient levels in urban-adjacent estuaries like Tudor Creek, with seasonal peaks linked to freshwater influx. A shift from nitrogen-limited to dissolved inorganic nitrogen (DIN)-enriched conditions was observed, with phosphorus/silica becoming limiting. Nutrient sources included sewage, agriculture, industry, submarine groundwater, and atmospheric deposition. Despite identifying 59 harmful microalgae taxa (47% toxin-producing), no phytotoxins were detected. Findings confirm nutrient enrichment drives phytoplankton community changes, favoring HAB species. The study underscores the urgent need for integrated nutrient management to safeguard Kenya’s coral reefs, seagrass, and marine biodiversity
Einfluss von Chlorid auf den transepithelialen Transport im kortikalen Sammelrohr der Niere
Full text linkDas kortikale Sammelrohr (CCD) der Nieren beeinflusst Elektrolyt-, Säure-Base- und Volumenhaushalt. Hauptzellen erzeugen durch Natriumfluss über den luminalen ENaC ein negatives transepitheliales Potenzial (Vte), was Kalium aus Hauptzellen oder Chlorid parazellulär ins Interstitium strömen lässt. Die Zwischenzellen sezernieren je Säure- oder Basenäquivalente und haben auch Anteil am Natrium- und Chloridtransport. Luminal und basolateral werden parazellulär durch Tight Junctions (TJ) separiert. Claudine in den TJ werden für die Selektivität verantwortlich gemacht. Allgemein wird dem CCD eine Anionenselektivität zugesprochen. Wir haben den zeit- und konzentrationsabhängigen Einfluss von Chlorid auf transepitheliale Eigenschaften des CCD von C57/Bl6-Mäusen im Perfusionssystem untersucht. CCD in Kontrolllösung (145 mmol/l NaCl) ohne Inkubation zeigten überwiegend die bekannten Eigenschaften. Teilweise fand sich parazellulär eine Kationenselektivität. 15 Minuten Inkubation verstärkte den elektrogenen Transport, was auf eine erhöhte Aktivität von ENaC schließen ließ. Die Permeabilität von Chlorid im Vergleich zu Natrium (PCl/PNa) blieb gleich. Die vorher zum Teil beobachtete Kationenselektivität trat nicht auf. Inkubation mit auf 90 bzw. 5 mmol/l verminderter Chloridkonzentration zeigte im Vergleich weniger Aktivität von ENaC mit geringer ausgeprägtem (90Cl) bzw. aufgehobenem (5Cl) Effekt von Amilorid auf den Transport. 5Cl verstärkte parazellulär selektiv die Chloridpermeabilität und Anionenselektivität im Vergleich zur Kontrolle. Die Ergebnisse zeigen, dass der parazelluläre Weg im CCD nicht starr ist, sondern sehr variabel sein kann. Chloridmangel bei normwertigem Natrium führt über fein regulierte Mechanismen zur Wiedererlangung der Homöostase
Messung von Elektronenhaftkoeffizienten mittels Staub im Plasma
Full text linkThe subject of this thesis is a novel method for the determination of electron sticking coefficients of different materials at very low energies (< 10 eV). Previously, conventional measurements of electron sticking coefficients were limited to either metallic surfaces, or higher energies in the case of dielectric materials. Using single, micrometer-sized particles of the respective material confined in a laboratory low-pressure plasma sheath (dust-in-plasma situation), low-energy electron sticking coefficients of several materials could now be determined. Especially the electron sticking coefficients of dielectric materials at low energies are now accessible with the experimental approach termed "Sticking Machine". This presents an application of dusty plasma physics for the investigation of surface processes. At the core of the method lies a relative measurement scheme comparing a particle of a material with known sticking coefficient to one of which the sticking coefficient is to be determined. In a first step, an improved measurement technique for the particle charge-to-mass ratio is developed, as the charge of a particle is an indicator for its sticking coefficient. To allow for the relative measurement scheme, models for the charge collection currents of ions and electrons onto the particle are chosen and applied, leading to results for the low-energy electron sticking coefficients of silica, polymethyl methacrylate (PMMA) and melamin formaldehyde (MF) using spherical particles. To extend the method to a wider range of materials, a generalization to non-spherical particles is needed, which is detailed in the last portion of the work. Using the results of this work, the Sticking Machine setup now allows for the determination of low-energy electron sticking coefficients of a wide range of technologically interesting materials, without requiring conductivity of the material or spherical particles