Distributed fuzzy decision making for production schedulling

In production systems, input materials (educts) pass through multiple sequential stages until they become a product. The production stages consist of different machines with various dynamic characteristics. The coupling of those machines is a non-linear distributed system. With a distributed control system based on a multi-agent approach, the produc- tion system can achieve (almost) maximum output, where lot size and lot sequence are the most important control variables. In most production processes high throughput and low stock are conflicting goals. In order to compare and compensate between these multiple goals, a fuzzy decision making approach is employed here that decides about the material flow and machine states, based on variables like working load or order queue length

Biophysikalische Untersuchungen von Infektionen mit Acanthamöben: Kontamination von Kontaktlinsen, Adhäsion und intrazelluläre Dynamik

Acanthamoeba castellanii can cause a severe and painful, acanthamoeba keratitis. In this disease, the acanthamoebae reach the eye via contaminated contact lenses. In the eye, they invade cornea cells and kill them. The first step in this process is the formation of a close contact between the acanthamoeba and the target-cell. This contact is mainly mediated by mannose. Subsequently, cytolytic factors move to the contact site and are released leading to the death of the target-cell. The single steps involved in the infection pathway, namely contact lens contamination, carbohydrate-mediated acanthamoeba adhesion, and intracellular transport were investigated in this thesis. As the use of contact lenses is a main risk factor in the infection process, in the first part of this thesis different silicone hydrogel and hydrogel materials were investigated for their potential to be contaminated with A. castellanii. Furthermore, influences of standard contact lens cleaning procedures on the adhesion and proliferation of A. castellanii were evaluated. It was observed that A. castellanii preferentially adhered to lenses with high water content (>60 %). Furthermore, while multipurpose and peroxide solution reduced adhesion of acanthamoeba significantly, only the peroxide solution was able to kill all A. castellanii effectively. If contaminated contact lenses are inserted into the eye, acanthamoebae reach the cornea, move through the epithelial tissue of the cornea and kill target-cells in the underlying cell layers. Thus, in the second part of this thesis interactions of acanthamoebae with proteins in the extracellular matrix, as well as the carbohydrate-mediated adhesion to target-cells were investigated. In order to mimic the extracellular matrix, glass slides were coated with proteins and the number of adhering acanthamoebae was evaluated. Compared to the glass, increased adhesion was observed on matrigel followed by fibronectin. This increase in number of adhering acanthamoeba was presumably mediated by mannose present in the protein coatings. In order to investigate the initial adhesion of acanthamoebae to target-cells, quasi-hexagonally arranged patterns of gold nanodots with different interparticle distances were produced by diblock copolymer micelle nanolithography and functionalized with mannose or glucose, respectively. By passivating the areas between the dots with polyethylene glycol (PEG), unspecific adhesion of the acanthamoebae in the inter-particle space was reduced and therefore only the biofunctionalized gold dots served as anchoring points for the adhesion. The evaluation of the number and the spreading area of A. castellanii showed that already relatively low densities of mannose lead to stable adhesion of the acanthamoebae and that mannose as single ligand is sufficient for adhesion. In order to quantify forces of the binding of A. castellanii to carbohydrate-functionalized surfaces, force spectroscopic measurements were carried out by atomic force microscopy (AFM). The measurements showed that with increasing contact time of acantameobae to mannose coated AFM cantilevers the maximum adhesion force and the adhesion energy increase. After initial adhesion of acanthamoeba to the target-cell, cytolytic factors, move to the contact site, are released and lead to target-cell death. Thus intracellular transport of vesicles was investigated in the last part of this thesis. In order to examine the intracellular dynamics, the transport processes of particles inside acanthamoebae were evaluated and compared after addition of filament depolymerizing substances and molecular-motor inhibiting substances. The intracellular space in A. castellanii is extremely crowded, and most particles were moving actively. This was also the case after the different treatments, which inhibited the motion of the whole amoebae, but not of the intracellular particles.Acanthamoeba castellanii können eine schmerzhafte, das Sehvermögen beeinträchtigende Acanthamöbenkeratitis verursachen. Dabei gelangen die Acanthamöben häufig über kontaminierte Kontaktlinsen oder Kontaktlinsenbehälter in das Auge. Dort dringen sie in die Hornhaut ein und töten Zielzellen ab. Dieser Mechanismus wird über die Ausbildung eines engen Kontakts zur Zielzelle initiiert. Die Kontaktbildung selbst wird hauptsächlich durch das Kohlenhydrat Mannose vermittelt. Nach Kontaktbildung bewegen sich zytolytische Faktoren in der Amöbe zur Kontaktstelle und werden dort freigegeben. Dies führt zum Tod der Zielzelle. In dieser Arbeit wurden drei relevante Phasen der Infektion untersucht: Kontamination von Kontaktlinsen mit Amöben, Kohlenhydrat-basierte Kontaktbildung zwischen Acanthamöbe und Zielzelle, sowie intrazellulärer Transport. Da Kontaktlinsen einen Hauptrisikofaktor in der Infektion darstellen, wurden im ersten Teil dieser Arbeit verschiedene Kontaktlinsenmaterialien (Siliconhydrogele sowie Hydrogele) auf ihr Kontaminationspotential untersucht. Zudem wurde der Einfluss von gängigen Reinigungsmethoden auf die Anhaftung und das Überleben der Acanthamöbe geprüft. Es zeigte sich, dass A. castellanii bevorzugt an Kontaktlinsen mit hohem Wassergehalt haften (> 60 %). Sowohl Pflegelösung als auch Peroxidlösung reduzierten die Adhäsion der Acanthamöben, wobei jedoch nur die Peroxidlösung die Zellen vollständig abtötete. Werden kontaminierte Kontaktlinsen ins Auge eingesetzt, erreichen die Amöben die Hornhaut, durchdringen das Epithelgewebe und töten Zellen in den darunterliegenden Zellschichten ab. Daher wurden im zweiten Teil Wechselwirkungen zwischen Acanthamöben und extrazellulärer Matrix, sowie die durch Kohlenhydrate vermittelte Anhaftung von Acanthamöben an Zielzellen untersucht. Um die extrazelluläre Matrix zu imitieren, wurden Deckgläser mit Proteinen beschichtet und die Anzahl anhaftender Acanthamöben bestimmt. Der Vergleich zur unbeschichteten Kontrolle ergab eine erhöhte Adhäsion von Acanthamöben auf Matrigel gefolgt von Fibronektin. Zur Untersuchung der initialen Anhaftung von Acanthamöben an Zielzellen, wurden Substrate mit quasi-hexagonal angeordneten Goldnanopunkten mit unterschiedlichen Abständen hergestellt und mit Mannose bzw. Glucose funktionalisiert. Unspezifische Anhaftung der Acanthamöben zwischen Goldpunkten wurde durch Passivierung dieser Bereiche mit Polyethylenglykol (PEG) verhindert, sodass ausschließlich funktionalisierte Goldpunkte als Haftstellen für Acanthamöben dienten. Die Analyse von Zellzahl und Zellfläche ergaben, dass bereits geringe Dichten des Kohlehydrats Mannose zu stabiler Adhäsion der Acanthamöben führten, wobei Mannose als einzelner Ligand ausreichte. Das kurzzeitige Anhaftungsverhalten an Kohlenhydrat-beschichtete Oberflächen sowie die Adhäsionskraft von Acanthamöben wurden erstmals mittels kraftspektroskopischer Untersuchungen am Rasterkraftmikroskop (AFM) quantifiziert. Die Messungen ergaben eine deutliche Zunahme von maximaler Adhäsionskraft und Adhäsionsenergie mit ansteigender Kontaktzeit zwischen Acanthamöbe und Mannose-beschichteter Oberfläche. Das initiale Anhaften der Acanthamöbe an die Zielzelle bewirkt eine Migration von in Vesikeln eingeschlossenen zytolytischen Faktoren zur Kontaktstelle. Daher wurde im letzten Teil dieser Arbeit der intrazelluläre Transport von Vesikeln näher untersucht. Dazu wurden Vesikeltrajektorien analysiert und einzelne zelluläre Transportstrukturen gezielt mittels Zugabe von Filament-depolymerisierenden Substanzen sowie Substanzen zur Inaktivierung molekularer Motoren gestört. Es wurden überwiegend aktive Bewegungen von intrazellulären Vesikeln beobachtet. Die verschiedenen Substanzen stoppten zwar nahezu die Bewegung der gesamten Zellen, inhibierten jedoch nicht den Transport der Vesikel in der Acanthamöbe

Adhesion forces and mechanics in mannose-mediated acanthamoeba interactions

The human pathogenic amoeba Acanthamoeba castellanii (A. castellanii) causes severe diseases, including acanthamoeba keratitis and encephalitis. Pathogenicity arises from the killing of target-cells by an extracellular killing mechanism, where the crucial first step is the formation of a close contact between A. castellanii and the target-cell. This process is medi- ated by the glycocalix of the target-cell and mannose has been identified as key mediator. The aim of the present study was to carry out a detailed biophysical investigation of man- nose-mediated adhesion of A. castellanii using force spectroscopy on single trophozoites. In detail, we studied the interaction of a mannose-coated cantilever with an A. castellanii tro- phozoite, as mannose is the decisive part of the cellular glycocalix in mediating pathogenic- ity. We observed a clear increase of the force to initiate cantilever detachment from the trophozoite with increasing contact time. This increase is also associated with an increase in the work of detachment. Furthermore, we also analyzed single rupture events during the detachment process and found that single rupture processes are associated with mem- brane tether formation, suggesting that the cytoskeleton is not involved in mannose binding events during the first few seconds of contact. Our study provides an experimental and conceptual basis for measuring interactions between pathogens and target-cells at different levels of complexity and as a function of interaction time, thus leading to new insights into the biophysical mechanisms of parasite pathogenicity

Global CO2 emissions from dry inland waters share common drivers across ecosystems

Many inland waters exhibit complete or partial desiccation, or have vanished due to global change, exposing sediments to the atmosphere. Yet, data on carbon dioxide (CO2) emissions from these sediments are too scarce to upscale emissions for global estimates or to understand their fundamental drivers. Here, we present the results of a global survey covering 196 dry inland waters across diverse ecosystem types and climate zones. We show that their CO2 emissions share fundamental drivers and constitute a substantial fraction of the carbon cycled by inland waters. CO2 emissions were consistent across ecosystem types and climate zones, with local characteristics explaining much of the variability. Accounting for such emissions increases global estimates of carbon emissions from inland waters by 6% (~0.12 Pg C y−1). Our results indicate that emissions from dry inland waters represent a significant and likely increasing component of the inland waters carbon cycle

Data For: Dry-Wet Cycles of Kettle Hole Sediments Leave a Microbial and Biogeochemical Legacy

Original Research Data: Sediment biogeochemistry (Physicochemical parameters, OM quantity and quality) Gas measurements (net CO2 and CH4 production) Functional gene abundancy and diversit