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Viele klinische Schnelltestsysteme benötigen vorpräparierte oder aufgereinigte Analyte mit frisch hergestellten Lösungen. Fernab standardisierter Laborbedingungen wie z.B. in Entwicklungsländern oder Krisengebieten sind solche Voraussetzungen oft nur unter einem hohen Aufwand herstellbar.
Zusätzlich stellt die erforderliche Sensitivität die Entwicklung einfach zu handhabender Testsysteme vor große Herausforderungen.
Autokatalytische Reaktionen, die sich mit Hilfe sehr geringer Initiatorkonzentrationen auslösen lassen, können hier eine Perspektive für Signalverstärkungsprozesse bieten.
Aus diesem Grund wird im ersten Teil der vorliegenden Arbeit das Verhalten der autokatalytischen Arsenit-Jodat-Reaktion in einem mikrofluidischen Kanal untersucht. Dabei werden insbesondere die diffusiven und konvektiven Einflüsse auf die Reaktionskinetik im Vergleich zu makroskopischen Volumenmengen betrachtet.
Im zweiten Teil werden thermoresponsive Hydrogele mit einem kanalstrukturierten Papiernetzwerk zu einem neuartigen, kapillargetriebenen, extern steuerbaren Mikrofluidik-System kombiniert. Das hier vorgestellte Konzept durch Hydrogele ein papierbasiertes LOC-System zu steuern, ermöglicht zukünftig die Herstellung von komplexeren, steuerbaren Point-Of-Care Testsystemen (POCT). Durch z.B. einen thermischen Stimulus, wird das Lösungsverhalten eines Hydrogels so verändert, dass die gespeicherte Flüssigkeit freigesetzt und durch die Kapillarkraft des Papierkanals ins System transportiert wird. Die Eigenschaften dieses Gelnetzwerks können dabei so eingestellt werden, dass eine Freisetzung von Flüssigkeiten sogar bei Körpertemperatur möglich wäre und damit eine Anwendung gänzlich ohne weitere Hilfsmittel denkbar ist. Für die Anwendung notwendige Chemikalien oder Enzyme lassen sich hierbei bequem in getrocknetem Zustand im Papiersubstrat vorlagern und bei Bedarf in Lösung bringen.
Im abschließenden dritten Teil der Arbeit wird ein durch Hydrogele betriebener, Antikörper-basierter Mikroorganismenschnelltest für Escherichia coli präsentiert. Darüber hinaus wird weiterführend eine einfache Methode zur Funktionalisierung eines Hydrogels mit Biomolekülen über EDC/NHS-Kopplung vorgestellt.
Das Thema der Arbeit sind Formen wissenschaftlicher Wissensproduktion in anwendungsbezogenen Forschungsprojekten und ihre Effekte auf Technisierungsprozesse. Diese untersuche ich am Beispiel eines öffentlich geförderten Forschungsprojekts, das ein automatisiertes Videoüberwachungssystem entwickelt. Als anwendungsbezogenes Forschungsprojekt unterliegt die Entwicklung des Videoüberwachungssystems besonderen Rahmenbedingungen: Die Arbeit der Forschergruppe soll erstens auf makrosoziale Kriminalitätsprobleme reagieren, zweitens politische Hoffnungen auf einen erfolgreichen Technologietransfer erfüllen, und drittens dem innerdisziplinären Erkenntnisfortschritt dienen. Daraus ergeben sich alltagspraktische Handlungsprobleme für die Forschergruppe, da sie zwischen heterogenen und möglicherweise widersprüchlichen Erwartungshaltungen vermitteln muss. Diese Vermittlungsstrategien beeinflussen jedoch in die Entscheidungsprozesse, wie und in welchem Ausmaß Überwachungsprozesse technisiert werden.
Das Promotionsprojekt geht der Frage nach, auf welche Weise die Forschergruppe die Integration der verschiedenen Erwartungshaltungen bewältigt, und welche Auswirkungen diese besondere Form des anwendungsbezogenen Forschens auf die Entwicklung der Überwachungstechnologie hat. Auf der Grundlage einer ethnographischen Fallstudie beantworte ich die Frage durch den Nachweis, dass die präferierten Lösungen der Forschergruppe sich eher an disziplinären Fragestellungen ausrichten als an ihrer Praxistauglichkeit. Dies wird besonders darin sichtbar, dass die ursprünglichen Problemstellungen im Verlaufe des Arbeitsprozesses anhand der tatsächlich verfügbaren Instrumente umdefiniert werden. Die daraus resultierenden Konflikte mit den gesellschaftlichen Erwartungshaltungen bewältigt die Forschergruppe, indem sie lernt, die Anwendungsbezogenheit gegenüber der Förderinstitution sorgfältig zu inszenieren.
Anthropogenic activities have transformed the Earth's environment, not only on local level, but on the planetary-scale causing global change. Besides industrialization, agriculture is a major driver of global change. This change in turn impairs the agriculture sector, reducing crop yields namely due to soil degradation, water scarcity, and climate change. However, this is a more complex issue than it appears. Crop yields can be increased by use of agrochemicals and fertilizers which are mainly produced by fossil energy. This is important to meet the increasing food demand driven by global demographic change, which is further accelerated by changes in regional lifestyles. In this dissertation, we attempt to address this complex problem exploring agricultural potential globally but on a local scale. For this, we considered the influence of lifestyle changes (dietary patterns) as well as technological progress and their effects on climate change, mainly greenhouse gas (GHG) emissions. Furthermore, we examined options for optimizing crop yields in the current cultivated land with the current cropping patterns by closing yield gaps. Using this, we investigated in a five-minute resolution the extent to which food demand can be met locally, and/or by regional and/or global trade. Globally, food consumption habits are shifting towards calorie rich diets. Due to dietary shifts combined with population growth, the global food demand is expected to increase by 60-110% between 2005 and 2050. Hence, one of the challenges to global sustainability is to meet the growing food demand, while at the same time, reducing agricultural inputs and environmental consequences. In order to address the above problem, we used several freely available datasets and applied multiple interconnected analytical approaches that include artificial neural network, scenario analysis, data aggregation and harmonization, downscaling algorithm, and cross-scale analysis.
Globally, we identified sixteen dietary patterns between 1961 and 2007 with food intakes ranging from 1,870 to 3,400 kcal/cap/day. These dietary patterns also reflected changing dietary habits to meat rich diets worldwide. Due to the large share of animal products, very high calorie diets that are common in the developed world, exhibit high total per capita emissions of 3.7-6.1 kg CO2eq./day. This is higher than total per capita emissions of 1.4-4.5 kg CO2eq./day associated with low and moderate calorie diets that are common in developing countries. Currently, 40% of the global crop calories are fed to livestock and the feed calorie use is four times the produced animal calories. However, these values vary from less than 1 kcal to greater 10 kcal around the world. On the local and national scale, we found that the local and national food production could meet demand of 1.9 and 4.4 billion people in 2000, respectively. However, 1 billion people from Asia and Africa require intercontinental agricultural trade to meet their food demand. Nevertheless, these regions can become food self-sufficient by closing yield gaps that require location specific inputs and agricultural management strategies. Such strategies include: fertilizers, pesticides, soil and land improvement, management targeted on mitigating climate induced yield variability, and improving market accessibility. However, closing yield gaps in particular requires global N-fertilizer application to increase by 45-73%, P2O5 by 22-46%, and K2O by 2-3 times compare to 2010. Considering population growth, we found that the global agricultural GHG emissions will approach 7 Gt CO2eq./yr by 2050, while the global livestock feed demand will remain similar to 2000. This changes tremendously when diet shifts are also taken into account, resulting in GHG emissions of 20 Gt CO2eq./yr and an increase of 1.3 times in the crop-based feed demand between 2000 and 2050. However, when population growth, diet shifts, and technological progress by 2050 were considered, GHG emissions can be reduced to 14 Gt CO2eq./yr and the feed demand to nearly 1.8 times compare to that in 2000. Additionally, our findings shows that based on the progress made in closing yield gaps, the number of people depending on international trade can vary between 1.5 and 6 billion by 2050. In medium term, this requires additional fossil energy. Furthermore, climate change, affecting crop yields, will increase the need for international agricultural trade by 4% to 16%.
In summary, three general conclusions are drawn from this dissertation. First, changing dietary patterns will significantly increase crop demand, agricultural GHG emissions, and international food trade in the future when compared to population growth only. Second, such increments can be reduced by technology transfer and technological progress that will enhance crop yields, decrease agricultural emission intensities, and increase livestock feed conversion efficiencies. Moreover, international trade dependency can be lowered by consuming local and regional food products, by producing diverse types of food, and by closing yield gaps. Third, location specific inputs and management options are required to close yield gaps. Sustainability of such inputs and management largely depends on which options are chosen and how they are implemented. However, while every cultivated land may not need to attain its potential yields to enable food security, closing yield gaps only may not be enough to achieve food self-sufficiency in some regions. Hence, a combination of sustainable implementations of agricultural intensification, expansion, and trade as well as shifting dietary habits towards a lower share of animal products is required to feed the growing population.
Der klassische Fernsehrundfunk genießt verfassungsrechtlich und einfachgesetzliche eine privilegierte Sonderstellung. Diese setzt sich bei der Kabelbelegung fort, wo er - insbesondere der öffentliche Rundfunk - gegenüber teemedialen Anrufangeboten bevorrechtigt wird. Hintergrund dieser Sonderstellung ist nicht zuletzt die auf den Rundfunk zentrierte Medienordnung. Die Arbeit untersucht, ob diese Medienordnung und damit die Sonderstellung des Rundfunks noch zeitgemäß ist und schlägt Anpassungen vor.
Plant cell walls are complex structures that underpin plant growth and are widely exploited in diverse human activities thus placing them with a central importance in biology. Cell walls have been a prominent area of research for a long time, but the chemical complexity and diversity of cell walls not just between species, but also within plants, between cell-types, and between cell wall micro-domains pose several challenges. Progress accelerated several-fold in cell wall biology owing to advances in sequencing technology, aided soon thereafter by advances in omics and imaging technologies. This development provides additional perspectives of cell walls across a rapidly growing number of species, highlighting a myriad of architectures, compositions, and functions.
Furthermore, rather than the component centric view, integrative analysis of the different cell wall components across system-levels help to gain a more in-depth understanding of the structure and biosynthesis of the cell envelope and its interactions with the environment.
To this end, in this work three case studies are detailed, all pertaining to the integrative analysis of heterogeneous cell wall related data arising from different system-levels and analytical techniques. A detailed account of multiblock methods is provided and in particular canonical correlation and regression methods of data integration are discussed. In the first integrative analysis, by employing canonical correlation analysis - a multivariate statistical technique to study the association between two datasets - novel insight to the relationship between glycans and phenotypic traits is gained. In addition, sparse partial least squares regression approach that adapts Lasso penalization and allows for the selection of a subset of variables was employed. The second case study focuses on an integrative analysis of images obtained from different spectroscopic techniques. By employing yet another multiblock approach - multiple co-inertia analysis, insitu biochemical composition of cell walls from different cell-types is studied thereby highlighting the common and complementary parts of the two hyperspectral imaging techniques. Finally, the third integrative analysis facilitates gene expression analysis of the Arabidopsis root transcriptome and translatome for the identification of cell wall related genes and compare expression patterns of cell wall synthesis genes. The computational analysis considered correlation and variation of expression across cell-types at both system-levels, and also provides insight into the degree of co-regulatory relationships that are preserved between the two processes.
The integrative analysis of glycan data and phenotypic traits in cotton fibers using canonical methods led to the identification of specific polysaccharides which may play a major role during fiber development for the final fiber characteristics. Furthermore, this analysis provides a base for future studies on glycan arrays in case of developing cotton fibers. The integrative analysis of images from infrared and Raman spectroscopic approaches allowed the coupling of different analytical techniques to characterize complex biological material, thereby, representing various facets of their chemical properties. Moreover, the results from the co-inertia analysis demonstrated that the study was well adapted as it is relevant for coupling data tables in a symmetric way. Several indicators are proposed to investigate how the global and block scores are related. In addition, studying the root cells of \textit{Arabidopsis thaliana} allowed positing a novel pipeline to systematically investigate and integrate the different levels of information available at the global and single-cell level. The conducted analysis also confirms that previously identified key transcriptional activators of secondary cell wall development display highly conserved patterns of transcription and translation across the investigated cell-types. Moreover, the biological processes that display conserved and divergent patterns based on the cell-type-specific expression and translation levels are identified.
Die Arbeit befasst sich zunächst mit der Analyse und Einordnung des Begriffs der Daseinsvorsorge und deren Erbringung durch den Staat. Schwerpunkt der Betrachtung bildet dabei die Energieversorgung als klassische Aufgabe staatlicher Daseinsvorsorge.
Weiterhin wird der durch die Liberalisierung der Energieversorgung im Jahr 1998 eingeleitete Wandel von sog. natürlichen Monopolen, hin zu einem wettbewerblichen System betrachtet. Dabei wird aufgezeigt, dass sich durch die Einführung des Wettbewerbs weder die damit erhofften Kostenreduzierungen, noch das von Kritikern befürchtete Sterben der kommunalen Energieversorger bewahrheitet haben. Statt einer freien Preisbildung im Wettbewerb ist es zu einer faktischen Verlagerung der früher staatlich festgesetzten Energiepreisgenehmigung auf die Gerichte gekommen, die hierfür jedoch nicht ausgelegt sind. Kommunale Stadtwerke haben sich in der wettbewerblichen Energieversorgung dagegen so gut behauptet, dass seit einiger Zeit ein Trend zur Rekommunalisierung von Energieversorgung auf kommunaler Ebene zu verzeichnen ist.
Diesem offensichtlichen Wunsch nach einer gesteigerten Einflussnahme der Gemeinden auf die örtliche Energieversorgung läuft der aktuelle Rechtsrahmen der energierechtlichen Konzessionsvergabe in Gestalt des § 46 EnWG und seiner Auslegung durch die Rechtsprechung der Zivilgerichte zuwider. Die Arbeit zeigt auf, dass von Beginn der Liberalisierung der kommunale Einfluss auf die örtliche Konzessionsvergabe schrittweise und stetig beschnitten wurde, so dass gegenwärtig ein Zustand der Aushöhlung erreicht ist, der als unzulässiger Eingriff in den geschützten Kernbereich der kommunalen Selbstverwaltungsgarantie i.S.d. Art. 28 II GG anzusehen ist.
Injection of nanoscale zero-valent iron (nZVI) is an innovative technology for in situ installation of a permeable reactive barrier in the subsurface. Zerovalent iron (ZVI) is highly reactive with chlorinated hydrocarbons (CHCs) and renders them into less harmful substances. Application of nZVI instead of granular ZVI can increase rates of dechlorination of CHCs by orders of magnitude, due to its higher surface area. This approach is still difficult to apply due to fast agglomeration and sedimentation of colloidal suspensions of nZVI, which leads to very short transport distances. To overcome this issue of limited mobility, polyanionic stabilisers are added to increase surface charge and stability of suspensions. In field experiments maximum transport distances of a few metres were achieved. A new approach, which is investigated in this thesis, is enhanced mobility of nZVI by a more mobile carrier colloid. The investigated composite material consists of activated carbon, which is loaded with nZVI.
In this cumulative thesis, transport characteristics of carbon-colloid supported nZVI (c-nZVI) are investigated. Investigations started with column experiments in 40 cm columns filled with various porous media to investigate on physicochemical influences on transport characteristics. The experimental setup was enlarged to a transport experiment in a 1.2-m-sized two-dimensional aquifer tank experiment, which was filled with granular porous media. Further, a field experiment was performed in a natural aquifer system with a targeted transport distance of 5.3 m. Parallel to these investigations, alternative methods for transport observations were investigated by using noninvasive tomographic methods. Experiments using synchrotron radiation and magnetic resonance (MRI) were performed to investigate in situ transport characteristics in a non-destructive way.
Results from column experiments show potentially high mobility under environmental relevant conditions. Addition of mono-and bivalent salts, e.g. more than 0.5 mM/L CaCl2, might decrease mobility. Changes in pH to values below 6 can inhibit mobility at all. Measurements of colloid size show changes in the mean particle size by a factor of ten. Measurements of zeta potential revealed an increase of –62 mV to –82 mV. Results from the 2D-aquifer test system suggest strong particle deposition in the first centimetres and only weak straining in the further travel path and no gravitational influence on particle transport. Straining at the beginning of the travel path in the porous medium was observed with tomographic investigations of transport. MRI experiments revealed similar results to the previous experiments, and observations using synchrotron radiation suggest straining of colloids at pore throats. The potential for high transport distances, which was suggested from laboratory experiments, was confirmed in the field experiment, where the transport distance of 5.3 m was reached by at least 10% of injected nZVI. Altogether, transport distances of the investigated carbon-colloid supported nZVI are higher than published results of traditional nZVI.
This dissertation addresses the question of how linguistic structures can be represented in working memory. We propose a memory-based computational model that derives offline and online complexity profiles in terms of a top-down parser for minimalist grammars (Stabler, 2011). The complexity metric reflects the amount of time an item is stored in memory. The presented architecture links grammatical representations stored in memory directly to the cognitive behavior by deriving predictions about sentence processing difficulty.
Results from five different sentence comprehension experiments were used to evaluate the model's assumptions about memory limitations. The predictions of the complexity metric were compared to the locality (integration and storage) cost metric of Dependency Locality Theory (Gibson, 2000). Both metrics make comparable offline and online predictions for four of the five phenomena. The key difference between the two metrics is that the proposed complexity metric accounts for the structural complexity of intervening material. In contrast, DLT's integration cost metric considers the number of discourse referents, not the syntactic structural complexity.
We conclude that the syntactic analysis plays a significant role in memory requirements of parsing. An incremental top-down parser based on a grammar formalism easily computes offline and online complexity profiles, which can be used to derive predictions about sentence processing difficulty.
The origin of cosmic rays was the subject of several studies for over a century. The investigations done within this dissertation are one small step to shed some more light on this mystery.
Locating the sources of cosmic rays is not trivial due to the interstellar magnetic field. However, the Hillas criterion allows us to arrive at the conclusion that supernova remnants are our main suspect for the origin of galactic cosmic rays. The mechanism by which they are accelerating particles is found within the field of shock physics as diffusive shock acceleration. To allow particles to enter this process also known as Fermi acceleration pre-acceleration processes like shock surfing acceleration and shock drift acceleration are necessary. Investigating the processes happening in the plasma shocks of supernova remnants is possible by utilising a simplified model which can be simulated on a computer using Particle-in-Cell simulations.
We developed a new and clean setup to simulate the formation of a double shock, i.e., consisting of a forward and a reverse shock and a contact discontinuity, by the collision of two counter-streaming plasmas, in which a magnetic field can be woven into. In a previous work, we investigated the processes at unmagnetised and at magnetised parallel shocks, whereas in the current work, we move our investigation on to magnetised perpendicular shocks.
Due to a much stronger confinement of the particles to the collision region the perpendicular shock develops much faster than the parallel shock. On the other hand, this leads to much weaker turbulence. We are able to find indications for shock surfing acceleration and shock drift acceleration happening at the two shocks leading to populations of pre-accelerated particles that are suitable as a seed population to be injected into further diffusive shock acceleration to be accelerated to even higher energies. We observe the development of filamentary structures in the shock ramp of the forward shock, but not at the reverse shock. This leads to the conclusion that the development of such structures in the shock ramp of quasi-perpendicular collisionless shocks might not necessarily be determined by the existence of a critical sonic Mach number but by a critical shock speed.
The results of the investigations done within this dissertation might be useful for further studies of oblique shocks and for studies using hybrid or magnetohydrodynamic simulations. Together with more sophisticated observational methods, these studies will help to bring us closer to an answer as to how particles can be accelerated in supernova remnants and eventually become cosmic rays that can be detected on Earth.
Assumed comparable environmental conditions of early Mars and early Earth in 3.7 Ga ago – at a time when first fossil records of life on Earth could be found – suggest the possibility of life emerging on both planets in parallel. As conditions changed, the hypothetical life on Mars either became extinct or was able to adapt and might still exist in biological niches. The controversial discussed detection of methane on Mars led to the assumption, that it must have a recent origin – either abiotic through active volcanism or chemical processes, or through biogenic production. Spatial and seasonal variations in the detected methane concentrations and correlations between the presence of water vapor and geological features such as subsurface hydrogen, which are occurring together with locally increased detected concentrations of methane, gave fuel to the hypothesis of a possible biological source of the methane on Mars.
Therefore the phylogenetically old methanogenic archaea, which have evolved under early Earth conditions, are often used as model-organisms in astrobiological studies to investigate the potential of life to exist in possible extraterrestrial habitats on our neighboring planet. In this thesis methanogenic archaea originating from two extreme environments on Earth were investigated to test their ability to be active under simulated Mars analog conditions. These extreme environments – the Siberian permafrost-affected soil and the chemoautotrophically based terrestrial ecosystem of Movile cave, Romania – are regarded as analogs for possible Martian (subsurface) habitats. Two novel species of methanogenic archaea isolated from these environments were described within the frame of this thesis.
It could be shown that concentrations up to 1 wt% of Mars regolith analogs added to the growth media had a positive influence on the methane production rates of the tested methanogenic archaea, whereas higher concentrations resulted in decreasing rates. Nevertheless it was possible for the organisms to metabolize when incubated on water-saturated soil matrixes made of Mars regolith analogs without any additional nutrients. Long-term desiccation resistance of more than 400 days was proven with reincubation and indirect counting of viable cells through a combined treatment with propidium monoazide (to inactivate DNA of destroyed cells) and quantitative PCR. Phyllosilicate rich regolith analogs seem to be the best soil mixtures for the tested methanogenic archaea to be active under Mars analog conditions. Furthermore, in a simulation chamber experiment the activity of the permafrost methanogen strain Methanosarcina soligelidi SMA-21 under Mars subsurface analog conditions could be proven. Through real-time wavelength modulation spectroscopy measurements the increase in the methane concentration at temperatures down to -5 °C could be detected.
The results presented in this thesis contribute to the understanding of the activity potential of methanogenic archaea under Mars analog conditions and therefore provide insights to the possible habitability of present-day Mars (near) subsurface environments. Thus, it contributes also to the data interpretation of future life detection missions on that planet. For example the ExoMars mission of the European Space Agency (ESA) and Roscosmos which is planned to be launched in 2018 and is aiming to drill in the Martian subsurface.