Refine
Has Fulltext
- yes (2537) (remove)
Year of publication
Document Type
- Doctoral Thesis (2537) (remove)
Language
Keywords
- climate change (53)
- Klimawandel (51)
- Modellierung (34)
- Nanopartikel (28)
- machine learning (22)
- Fernerkundung (20)
- Synchronisation (19)
- remote sensing (18)
- Spracherwerb (17)
- Blickbewegungen (16)
Institute
- Institut für Physik und Astronomie (406)
- Institut für Biochemie und Biologie (386)
- Institut für Geowissenschaften (328)
- Institut für Chemie (304)
- Extern (151)
- Institut für Umweltwissenschaften und Geographie (122)
- Institut für Ernährungswissenschaft (102)
- Wirtschaftswissenschaften (97)
- Hasso-Plattner-Institut für Digital Engineering GmbH (92)
- Department Psychologie (89)
MHC genes encode proteins that are responsible for the recognition of foreign antigens and the triggering of a subsequent, adequate immune response of the organism. Thus they hold a key position in the immune system of vertebrates. It is believed that the extraordinary genetic diversity of MHC genes is shaped by adaptive selectional processes in response to the reoccurring adaptations of parasites and pathogens. A large number of MHC studies were performed in a wide range of wildlife species aiming to understand the role of immune gene diversity in parasite resistance under natural selection conditions. Methodically, most of this work with very few exceptions has focussed only upon the structural, i.e. sequence diversity of regions responsible for antigen binding and presentation. Most of these studies found evidence that MHC gene variation did indeed underlie adaptive processes and that an individual’s allelic diversity explains parasite and pathogen resistance to a large extent. Nevertheless, our understanding of the effective mechanisms is incomplete. A neglected, but potentially highly relevant component concerns the transcriptional differences of MHC alleles. Indeed, differences in the expression levels MHC alleles and their potential functional importance have remained unstudied. The idea that also transcriptional differences might play an important role relies on the fact that lower MHC gene expression is tantamount with reduced induction of CD4+ T helper cells and thus with a reduced immune response. Hence, I studied the expression of MHC genes and of immune regulative cytokines as additional factors to reveal the functional importance of MHC diversity in two free-ranging rodent species (Delomys sublineatus, Apodemus flavicollis) in association with their gastrointestinal helminths under natural selection conditions. I established the method of relative quantification of mRNA on liver and spleen samples of both species in our laboratory. As there was no available information on nucleic sequences of potential reference genes in both species, PCR primer systems that were established in laboratory mice have to be tested and adapted for both non-model organisms. In the due course, sets of stable reference genes for both species were found and thus the preconditions for reliable measurements of mRNA levels established. For D. sublineatus it could be demonstrated that helminth infection elicits aspects of a typical Th2 immune response. Whereas mRNA levels of the cytokine interleukin Il4 increased with infection intensity by strongyle nematodes neither MHC nor cytokine expression played a significant role in D. sublineatus. For A. flavicollis I found a negative association between the parasitic nematode Heligmosomoides polygyrus and hepatic MHC mRNA levels. As a lower MHC expression entails a lower immune response, this could be evidence for an immune evasive strategy of the nematode, as it has been suggested for many micro-parasites. This implies that H. polygyrus is capable to interfere actively with the MHC transcription. Indeed, this parasite species has long been suspected to be immunosuppressive, e.g. by induction of regulatory T-helper cells that respond with a higher interleukin Il10 and tumor necrosis factor Tgfb production. Both cytokines in turn cause an abated MHC expression. By disabling recognition by the MHC molecule H. polygyrus might be able to prevent an activation of the immune system. Indeed, I found a strong tendency in animals carrying the allele Apfl-DRB*23 to have an increased infection intensity with H. polygyrus. Furthermore, I found positive and negative associations between specific MHC alleles and other helminth species, as well as typical signs of positive selection acting on the nucleic sequences of the MHC. The latter was evident by an elevated rate of non-synonymous to synonymous substitutions in the MHC sequences of exon 2 encoding the functionally important antigen binding sites whereas the first and third exons of the MHC DRB gene were highly conserved. In conclusion, the studies in this thesis demonstrate that valid procedures to quantify expression of immune relevant genes are also feasible in non-model wildlife organisms. In addition to structural MHC diversity, also MHC gene expression should be considered to obtain a more complete picture on host-pathogen coevolutionary selection processes. This is especially true if parasites are able to interfere with systemic MHC expression. In this case advantageous or disadvantageous effects of allelic binding motifs are abated. The studies could not define the role of MHC gene expression in antagonistic coevolution as such but the results suggest that it depends strongly on the specific parasite species that is involved.
Companies develop process models to explicitly describe their business operations. In the same time, business operations, business processes, must adhere to various types of compliance requirements. Regulations, e.g., Sarbanes Oxley Act of 2002, internal policies, best practices are just a few sources of compliance requirements. In some cases, non-adherence to compliance requirements makes the organization subject to legal punishment. In other cases, non-adherence to compliance leads to loss of competitive advantage and thus loss of market share. Unlike the classical domain-independent behavioral correctness of business processes, compliance requirements are domain-specific. Moreover, compliance requirements change over time. New requirements might appear due to change in laws and adoption of new policies. Compliance requirements are offered or enforced by different entities that have different objectives behind these requirements. Finally, compliance requirements might affect different aspects of business processes, e.g., control flow and data flow. As a result, it is infeasible to hard-code compliance checks in tools. Rather, a repeatable process of modeling compliance rules and checking them against business processes automatically is needed. This thesis provides a formal approach to support process design-time compliance checking. Using visual patterns, it is possible to model compliance requirements concerning control flow, data flow and conditional flow rules. Each pattern is mapped into a temporal logic formula. The thesis addresses the problem of consistency checking among various compliance requirements, as they might stem from divergent sources. Also, the thesis contributes to automatically check compliance requirements against process models using model checking. We show that extra domain knowledge, other than expressed in compliance rules, is needed to reach correct decisions. In case of violations, we are able to provide a useful feedback to the user. The feedback is in the form of parts of the process model whose execution causes the violation. In some cases, our approach is capable of providing automated remedy of the violation.
Corvino, Corvino and Schoen, Chruściel and Delay have shown the existence of a large class of asymptotically flat vacuum initial data for Einstein's field equations which are static or stationary in a neighborhood of space-like infinity, yet quite general in the interior. The proof relies on some abstract, non-constructive arguments which makes it difficult to calculate such data numerically by using similar arguments. A quasilinear elliptic system of equations is presented of which we expect that it can be used to construct vacuum initial data which are asymptotically flat, time-reflection symmetric, and asymptotic to static data up to a prescribed order at space-like infinity. A perturbation argument is used to show the existence of solutions. It is valid when the order at which the solutions approach staticity is restricted to a certain range. Difficulties appear when trying to improve this result to show the existence of solutions that are asymptotically static at higher order. The problems arise from the lack of surjectivity of a certain operator. Some tensor decompositions in asymptotically flat manifolds exhibit some of the difficulties encountered above. The Helmholtz decomposition, which plays a role in the preparation of initial data for the Maxwell equations, is discussed as a model problem. A method to circumvent the difficulties that arise when fast decay rates are required is discussed. This is done in a way that opens the possibility to perform numerical computations. The insights from the analysis of the Helmholtz decomposition are applied to the York decomposition, which is related to that part of the quasilinear system which gives rise to the difficulties. For this decomposition analogous results are obtained. It turns out, however, that in this case the presence of symmetries of the underlying metric leads to certain complications. The question, whether the results obtained so far can be used again to show by a perturbation argument the existence of vacuum initial data which approach static solutions at infinity at any given order, thus remains open. The answer requires further analysis and perhaps new methods.
The Arctic is the hot spot of the ongoing, global climate change. Over the last decades, near-surface temperatures in the Arctic have been rising almost four times faster than on global average. This amplified warming of the Arctic and the associated rapid changes of its environment are largely influenced by interactions between individual components of the Arctic climate system. On daily to weekly time scales, storms can have major impacts on the Arctic sea-ice cover and are thus an important part of these interactions within the Arctic climate. The sea-ice impacts of storms are related to high wind speeds, which enhance the drift and deformation of sea ice, as well as to changes in the surface energy budget in association with air mass advection, which impact the seasonal sea-ice growth and melt.
The occurrence of storms in the Arctic is typically associated with the passage of transient cyclones. Even though the above described mechanisms how storms/cyclones impact the Arctic sea ice are in principal known, there is a lack of statistical quantification of these effects. In accordance with that, the overarching objective of this thesis is to statistically quantify cyclone impacts on sea-ice concentration (SIC) in the Atlantic Arctic Ocean over the last four decades. In order to further advance the understanding of the related mechanisms, an additional objective is to separate dynamic and thermodynamic cyclone impacts on sea ice and assess their relative importance. Finally, this thesis aims to quantify recent changes in cyclone impacts on SIC. These research objectives are tackled utilizing various data sets, including atmospheric and oceanic reanalysis data as well as a coupled model simulation and a cyclone tracking algorithm.
Results from this thesis demonstrate that cyclones are significantly impacting SIC in the Atlantic Arctic Ocean from autumn to spring, while there are mostly no significant impacts in summer. The strength and the sign (SIC decreasing or SIC increasing) of the cyclone impacts strongly depends on the considered daily time scale and the region of the Atlantic Arctic Ocean. Specifically, an initial decrease in SIC (day -3 to day 0 relative to the cyclone) is found in the Greenland, Barents and Kara Seas, while SIC increases following cyclones (day 0 to day 5 relative to the cyclone) are mostly limited to the Barents and Kara Seas.
For the cold season, this results in a pronounced regional difference between overall (day -3 to day 5 relative to the cyclone) SIC-decreasing cyclone impacts in the Greenland Sea and overall SIC-increasing cyclone impacts in the Barents and Kara Seas. A cyclone case study based on a coupled model simulation indicates that both dynamic and thermodynamic mechanisms contribute to cyclone impacts on sea ice in winter. A typical pattern consisting of an initial dominance of dynamic sea-ice changes followed by enhanced thermodynamic ice growth after the cyclone passage was found. This enhanced ice growth after the cyclone passage most likely also explains the (statistical) overall SIC-increasing effects of cyclones in the Barents and Kara Seas in the cold season.
Significant changes in cyclone impacts on SIC over the last four decades have emerged throughout the year. These recent changes are strongly varying from region to region and month to month. The strongest trends in cyclone impacts on SIC are found in autumn in the Barents and Kara Seas. Here, the magnitude of destructive cyclone impacts on SIC has approximately doubled over the last four decades. The SIC-increasing effects following the cyclone passage have particularly weakened in the Barents Sea in autumn. As a consequence, previously existing overall SIC-increasing cyclone impacts in this region in autumn have recently disappeared. Generally, results from this thesis show that changes in the state of the sea-ice cover (decrease in mean sea-ice concentration and thickness) and near-surface air temperature are most important for changed cyclone impacts on SIC, while changes in cyclone properties (i.e. intensity) do not play a significant role.
Z,E-Diene sind ein häufig auftretendes Strukturmerkmal in Naturstoffen. Aus diesem Grund ist die einfache Darstellung dieser Struktureinheit von großen Interesse in der organischen Chemie.
Das erste Ziel der vorliegenden Arbeit war daher die Weiterentwicklung der Ringschlussmetathese-/ baseninduzierten Ringöffnungs-/ Veresterungssequenz (RBRV-Sequenz) zur Synthese von (2Z,4E)-Diencarbonsäureethylestern ausgehend von Butenoaten. Dazu wurde zunächst die RBRV-Sequenz optimiert. Diese aus drei Schritten bestehende Sequenz konnte in einem Eintopf-Verfahren angewendet werden. Die Ringschlussmetathese gelang mit einer Katalysatorbeladung von 1 mol% des GRUBBS-Katalysators der zweiten Generation in Dichlormethan. Für die baseninduzierte Ringöffnung des β,γ-ungesättigten δ Valerolactons wurde NaHMDS verwendet. Die Alkylierung der Carboxylatspezies gelang mit dem MEERWEIN-Reagenz. Die Anwendbarkeit der Sequenz wurde für verschiedene Substrate demonstriert.
Die Erweiterung der Methode auf α-substituierte Butenoate unterlag starken Einschränkungen. So konnte der Zugang für α Hydroxyderivate realisiert werden. Bei der Anwendung der RBRV-Sequenz auf die α-substituierten Butenoate wurde festgestellt, dass diese sich nur in moderaten Ausbeuten umsetzen ließen und zudem nicht selektiv zu den (2E,4E)-konfigurierten α-substituierten-Dienestern reagierten.
Der Einsatz von Eninen unter den Standardbedingungen der RBRV-Sequenz gelang nicht. Erst nach Modifizierung der Sequenz (höhere Katalysatorbeladung, Wechsel des Lösungsmittels) konnten die [3]Dendralen-Produkte in geringen Ausbeuten erhalten werden.
Im zweiten Teil der Arbeit wurde der Einsatz von (2Z,4E)-Diencarbonsäureethylestern in der Totalsynthese von Naturstoffen untersucht. Dazu wurden zunächst die Transformationsmöglichkeiten der Ester geprüft. Es konnte gezeigt werden, dass sich (2Z,4E)-Diencarbonsäureethylester insbesondere zur Synthese von (2Z,4E)-Aldehyden sowie zum Aufbau der (3Z,5E)-Dien-1-in-Struktur eignen.
Anhand dieser Ergebnisse wurde im Anschluss die RBRV-Sequenz in der Totalsynthese eingesetzt. Dazu wurde zunächst der (2Z,4E)-Dienester Microsphaerodiolin in seiner ersten Totalsynthese auf drei verschiedene Routen hergestellt. Im Anschluss wurden sechs verschiedene Polyacetylene mit einer (3Z,5E)-Dien-1-in-Einheit hergestellt. Schlüsselschritte in ihrer Synthese waren immer die RBRV-Sequenz zum Aufbau der Z,E-Dien-Einheit, die Transformation des Esters in ein terminales Alkin sowie die CADIOT-CHODKIEWICZ-Kupplung zum Aufbau unsymmetrischer Polyine. Alle sechs Polyacetylene wurden zum ersten Mal in einer Totalsynthese synthetisiert. Drei Polyacetylene wurden ausgehend von (S)-Butantriol enantiomerenrein dargestellt. Anhand ihrer Drehwerte konnte eine Revision der von YAO und Mitarbeitern vorgenommen Zuordnung der Absolutkonfiguration der Naturstoffe vorgenommen werden.
Ghana ist ein Musterbeispiel dafür, dass ein Entwicklungsland den Weg zu Good Governance schaffen kann. In vielen Studien wird dem Land im afrikanischen Vergleich heute bescheinigt, hier ein Vorreiter zu sein. Dies ist Ausgangslage der vorliegenden Studie, die der Frage nachgeht „Welche Gründe, Muster und Bedingungen führen zur Entstehung von Good Governance?“. Im Zentrum der vorliegenden Studie steht, wie aus der erkenntnisleitenden Fragestellung hervorgeht, eine empirische Untersuchung zur Entstehung von Good Governance und damit ein Transformationsprozess. Dieser wird bewusst über einen sehr langen Zeitraum (über ein halbes Jahrhundert) untersucht, um auch langfristige Entwicklungen einbeziehen zu können. Die Studie wird mit Hilfe eines „Mixed-Methods-Ansatzes“ sowohl unter Rückgriff auf quantitative als auch auf qualitative Methoden durchgeführt, was sich im Rückblick als sehr ertragreich erwiesen hat. Zunächst wird die Qualität der Governance über den gesamten Zeitraum anhand von sechs Indikatoren gemessen. Danach werden qualitativ die Gründe für die Fort- und Rückschritte analysiert. Dabei lassen sich immer wieder Systematiken herausarbeiten, wie zum Beispiel zirkuläre Entwicklungen, die über viele Jahre den Weg hin zu Good Governance verhinderten, bis jeweils Ausbrüche aus den Kreisläufen geschafft werden konnten. Sowohl in der demokratischen und rechtsstaatlichen Entwicklung als auch bezogen auf die Versorgung der Bevölkerung mit öffentlichen Gütern und die wirtschaftliche Entwicklung. Auch wenn die verschiedenen Bereiche von Good Governance zunächst einzeln untersucht werden, so zeigen sich gleichzeitig deutlich die Wechselwirkungen der Komponenten. Zum Beispiel kristallisiert sich klar heraus, dass Rechtsstaatlichkeit sowohl auf die Stabilität politischer Systeme wirkt, als auch auf die wirtschaftliche Entwicklung. Ebenso beeinflussen diese wiederum die Korruption. Ähnliche Verknüpfungen lassen sich auch bei allen anderen Bereichen nachvollziehen. Die Entwicklung eines Landes kann also nur unter Berücksichtigung eines komplexen Governance-Systems verstanden und erklärt werden. Dabei können die Wechselwirkungen entweder konstruktiv oder destruktiv sein. Die Verflechtungen der einzelnen Bereiche werden in einem Negativ- und dann in einem Positiv-Szenario festgehalten. Diese Idealtypen-Bildung spitzt die Erkenntnisse der vorliegenden Arbeit zu und dient dem analytischen Verständnis der untersuchten Prozesse. Die Untersuchung zeigt, wie Good Governance über das Zusammenspiel verschiedener Faktoren entstehen kann und dass es wissenschaftlich sehr ertragreich ist, Transformationsforschung auf ein komplexes Governance-System auszuweiten. Hierbei werden die vielen empirisch erarbeiteten Ergebnisse zu den einzelnen Transformationen zu komplexen, in sich greifenden Gesamtszenarien zusammengeführt. Da es bisher keine explizite Good Governance-Transformationsforschung gab, wurde hiermit ein erster Schritt in diese Richtung getan. Es wird darüber hinaus deutlich, dass eine Transformation zu Good Governance nicht durch eine kurzfristige Veränderung der Rahmenbedingungen zu erreichen ist. Es geht um kulturelle Veränderungen, um Lernprozesse, um langfristige Entwicklungen, die in der Studie am Beispiel Ghana analysiert werden. In vielen vorangegangenen Transformationsstudien wurde diese zeitliche Komponente vernachlässigt. Ghana hat bereits viele Schritte getan, um einen Weg in die Zukunft und zu Good Governance zu finden. Die Untersuchung dieser Schritte ist Kern der vorliegenden Arbeit. Der Weg Ghanas ist jedoch noch nicht abgeschlossen.
The main goal of this dissertation is to experimentally investigate how focus is realised, perceived, and processed by native Turkish speakers, independent of preconceived notions of positional restrictions. Crucially, there are various issues and scientific debates surrounding focus in the Turkish language in the existing literature (chapter 1). It is argued in this dissertation that two factors led to the stagnant literature on focus in Turkish: the lack of clearly defined, modern understandings of information structure and its fundamental notion of focus, and the ongoing and ill-defined debate surrounding the question of whether there is an immediately preverbal focus position in Turkish. These issues gave rise to specific research questions addressed across this dissertation. Specifically, we were interested in how the focus dimensions such as focus size (comparing narrow constituent and broad sentence focus), focus target (comparing narrow subject and narrow object focus), and focus type (comparing new-information and contrastive focus) affect Turkish focus realisation and, in turn, focus comprehension when speakers are provided syntactic freedom to position focus as they see fit.
To provide data on these core goals, we presented three behavioural experiments based on a systematic framework of information structure and its notions (chapter 2): (i) a production task with trigger wh-questions and contextual animations manipulated to elicit the focus dimensions of interest (chapter 3), (ii) a timed acceptability judgment task in listening to the recorded answers in our production task (chapter 4), and (iii) a self-paced reading task to gather on-line processing data (chapter 5).
Based on the results of the conducted experiments, multiple conclusions are made in this dissertation (chapter 6). Firstly, this dissertation demonstrated empirically that there is no focus position in Turkish, neither in the sense of a strict focus position language nor as a focally loaded position facilitating focus perception and/or processing. While focus is, in fact, syntactically variable in the Turkish preverbal area, this is a consequence of movement triggered by other IS aspects like topicalisation and backgrounding, and the observational markedness of narrow subject focus compared to narrow object focus. As for focus type in Turkish, this dimension is not associated with word order in production, perception, or processing. Significant acoustic correlates of focus size (broad sentence focus vs narrow constituent focus) and focus target (narrow subject focus vs narrow object focus) were observed in fundamental frequency and intensity, representing focal boost, (postfocal) deaccentuation, and the presence or absence of a phrase-final rise in the prenucleus, while the perceivability of these effects remains to be investigated. In contrast, no acoustic correlates of focus type in simple, three-word transitive structures were observed, with focus types being interchangeable in mismatched question-answer pairs. Overall, the findings of this dissertation highlight the need for experimental investigations regarding focus in Turkish, as theoretical predictions do not necessarily align with experimental data. As such, the fallacy of implying causation from correlation should be strictly kept in mind, especially when constructions coincide with canonical structures, such as the immediately preverbal position in narrow object foci. Finally, numerous open questions remain to be explored, especially as focus and word order in Turkish are multifaceted. As shown, givenness is a confounding factor when investigating focus types, while thematic role assignment potentially confounds word order preferences. Further research based on established, modern information structure frameworks is needed, with chapter 5 concluding with specific recommendations for such future research.
In the current paradigm of cosmology, the formation of large-scale structures is mainly driven by non-radiating dark matter, making up the dominant part of the matter budget of the Universe. Cosmological observations however, rely on the detection of luminous galaxies, which are biased tracers of the underlying dark matter. In this thesis I present cosmological reconstructions of both, the dark matter density field that forms the cosmic web, and cosmic velocities, for which both aspects of my work are delved into, the theoretical formalism and the results of its applications to cosmological simulations and also to a galaxy redshift survey.The foundation of our method is relying on a statistical approach, in which a given galaxy catalogue is interpreted as a biased realization of the underlying dark matter density field. The inference is computationally performed on a mesh grid by sampling from a probability density function, which describes the joint posterior distribution of matter density and the three dimensional velocity field. The statistical background of our method is described in Chapter ”Implementation of argo”, where the introduction in sampling methods is given, paying special attention to Markov Chain Monte-Carlo techniques. In Chapter ”Phase-Space Reconstructions with N-body Simulations”, I introduce and implement a novel biasing scheme to relate the galaxy number density to the underlying dark matter, which I decompose into a deterministic part, described by a non-linear and scale-dependent analytic expression, and a stochastic part, by presenting a negative binomial (NB) likelihood function that models deviations from Poissonity. Both bias components had already been studied theoretically, but were so far never tested in a reconstruction algorithm. I test these new contributions againstN-body simulations to quantify improvements and show that, compared to state-of-the-art methods, the stochastic bias is inevitable at wave numbers of k≥0.15h Mpc^−1 in the power spectrum in order to obtain unbiased results from the reconstructions. In the second part of Chapter ”Phase-Space Reconstructions with N-body Simulations” I describe and validate our approach to infer the three dimensional cosmic velocity field jointly with the dark matter density. I use linear perturbation theory for the large-scale bulk flows and a dispersion term to model virialized galaxy motions, showing that our method is accurately recovering the real-space positions of the redshift-space distorted galaxies. I analyze the results with the isotropic and also the two-dimensional power spectrum.Finally, in Chapter ”Phase-space Reconstructions with Galaxy Redshift Surveys”, I show how I combine all findings and results and apply the method to the CMASS (for Constant (stellar) Mass) galaxy catalogue of the Baryon Oscillation Spectroscopic Survey (BOSS). I describe how our method is accounting for the observational selection effects inside our reconstruction algorithm. Also, I demonstrate that the renormalization of the prior distribution function is mandatory to account for higher order contributions in the structure formation model, and finally a redshift-dependent bias factor is theoretically motivated and implemented into our method. The various refinements yield unbiased results of the dark matter until scales of k≤0.2 h Mpc^−1in the power spectrum and isotropize the galaxy catalogue down to distances of r∼20h^−1 Mpc in the correlation function. We further test the results of our cosmic velocity field reconstruction by comparing them to a synthetic mock galaxy catalogue, finding a strong correlation between the mock and the reconstructed velocities. The applications of both, the density field without redshift-space distortions, and the velocity reconstructions, are very broad and can be used for improved analyses of the baryonic acoustic oscillations, environmental studies of the cosmic web, the kinematic Sunyaev-Zel’dovic or integrated Sachs-Wolfe effect.
The Earth's inner magnetosphere is a very dynamic system, mostly driven by the external solar wind forcing exerted upon the magnetic field of our planet. Disturbances in the solar wind, such as coronal mass ejections and co-rotating interaction regions, cause geomagnetic storms, which lead to prominent changes in charged particle populations of the inner magnetosphere - the plasmasphere, ring current, and radiation belts. Satellites operating in the regions of elevated energetic and relativistic electron fluxes can be damaged by deep dielectric or surface charging during severe space weather events. Predicting the dynamics of the charged particles and mitigating their effects on the infrastructure is of particular importance, due to our increasing reliance on space technologies.
The dynamics of particles in the plasmasphere, ring current, and radiation belts are strongly coupled by means of collisions and collisionless interactions with electromagnetic fields induced by the motion of charged particles. Multidimensional numerical models simplify the treatment of transport, acceleration, and loss processes of these particles, and allow us to predict how the near-Earth space environment responds to solar storms. The models inevitably rely on a number of simplifications and assumptions that affect model accuracy and complicate the interpretation of the results. In this dissertation, we quantify the processes that control electron dynamics in the inner magnetosphere, paying particular attention to the uncertainties of the employed numerical codes and tools.
We use a set of convenient analytical solutions for advection and diffusion equations to test the accuracy and stability of the four-dimensional Versatile Electron Radiation Belt (VERB-4D) code. We show that numerical schemes implemented in the code converge to the analytical solutions and that the VERB-4D code demonstrates stable behavior independent of the assumed time step. The order of the numerical scheme for the convection equation is demonstrated to affect results of ring current and radiation belt simulations, and it is crucially important to use high-order numerical schemes to decrease numerical errors in the model.
Using the thoroughly tested VERB-4D code, we model the dynamics of the ring current electrons during the 17 March 2013 storm. The discrepancies between the model and observations above 4.5 Earth's radii can be explained by uncertainties in the outer boundary conditions. Simulation results indicate that the electrons were transported from the geostationary orbit towards the Earth by the global-scale electric and magnetic fields.
We investigate how simulation results depend on the input models and parameters. The model is shown to be particularly sensitive to the global electric field and electron lifetimes below 4.5 Earth's radii. The effects of radial diffusion and subauroral polarization streams are also quantified.
We developed a data-assimilative code that blends together a convection model of energetic electron transport and loss and Van Allen Probes satellite data by means of the Kalman filter. We show that the Kalman filter can correct model uncertainties in the convection electric field, electron lifetimes, and boundary conditions. It is also demonstrated how the innovation vector - the difference between observations and model prediction - can be used to identify physical processes missing in the model of energetic electron dynamics.
We computed radial profiles of phase space density of ultrarelativistic electrons, using Van Allen Probes measurements. We analyze the shape of the profiles during geomagnetically quiet and disturbed times and show that the formation of new local minimums in the radial profiles coincides with the ground observations of electromagnetic ion-cyclotron (EMIC) waves. This correlation indicates that EMIC waves are responsible for the loss of ultrarelativistic electrons from the heart of the outer radiation belt into the Earth's atmosphere.
In this dissertation we introduce a concept of light driven active and passive manipulation of colloids trapped at solid/liquid interface. The motion is induced due to generation of light driven diffusioosmotic flow (LDDO) upon irradiation with light of appropriate wavelength. The origin of the flow is due to osmotic pressure gradient resulting from a concentration gradient at the solid/liquid interface of the photosensitive surfactant present in colloidal dispersion. The photosensitive surfactant consists of a cationic head group and a hydrophobic tail in which azobenzene group is integrated in. The azobenzene is known to undergo reversible photo-isomerization from a stable trans to a meta stable cis state under irradiation with UV light. Exposure to light of larger wavelength results in back photo-isomerization from cis to trans state. The two isomers have different molecular properties, for instance, trans isomer has a rod like structure and low polarity (0 dipole moment), whereas cis one is bent and has a dipole moment of ~3 Debye. Being integrated in the hydrophobic tail of the surfactant molecule, the azobenzene state determines the hydrophobicity of the whole molecule: in the trans state the surfactant is more hydrophobic than in the cis-state. In this way many properties of the surfactant such as the CMC, solubility and the interaction potential with a solid surface can be altered by light. When the solution containing such a surfactant is irradiated with focused light, a concentration gradient of different isomers is formed near the boundary of the irradiated area near the solid surface resulting in osmotic pressure gradient. The generated diffusioosmotic (DO) flow carries the particles passively along.
The local-LDDO flow can be generated around and by each particle when mesoporous silica colloids are dispersed in the surfactant solution. This is because porous particles act as a sink/source which absorbs azobenzene molecule in trans state and expels it when it is in the cis state. The DO flows generated at each particle interact resulting in aggregation or separation depending upon the initial state of surfactant molecules. The kinetic of aggregation and separation can be controlled and manipulated by altering the parameters such as the wavelength and intensity of the applied light, as well as surfactant and particle concentration. Using two wavelengths simultaneously allows for dynamic gathering and separation creating fascinating patterns such as 2D disk of well separated particles or establishing collective complex behaviour of particle ensemble as described in this thesis.
The mechanism of l-LDDO is also used to generate self-propelled motion. This is possible when half of the porous particle is covered by metal layer, basically blocking the pores on one side. The LDDO flow generated on uncapped side pushes the particle forward resulting in a super diffusive motion. The system of porous particle and azobenzene containing surfactant molecule can be utilized for various application such as drug delivery, cargo transportation, self-assembling, micro motors/ machines or micro patterning.
Polymeric semiconductors are strong contenders for replacing traditional inorganic semiconductors in electronic applications requiring low power, low cost and flexibility, such as biosensors, flexible solar cells and electronic displays. Molecular doping has the potential to enable this revolution by improving the conductivity and charge transport properties of this class of materials. Despite decades of research in this field, gaps in our understanding of the nature of dopant–polymer interactions has resulted in limited commercialization of this technology. This work aims at providing a deeper insight into the underlying mechanisms of molecular p-doping of semiconducting polymers in the solution and solid-state, and thereby bring the scientific community closer to realizing the dream of making organic semiconductors commonplace in the electronics industry. The role of 1) dopant size/shape, 2) polymer chain aggregation and 3) charge delocalization on the doping mechanism and efficiency is addressed using optical (UV-Vis-NIR) and electron paramagnetic resonance (EPR) spectroscopies. By conducting a comprehensive study of the nature and concentration of the doping-induced species in solutions of the polymer poly(3-hexylthiophene) (P3HT) with 3 different dopants, we identify the unique optical signatures of the delocalized polaron, localized polaron and charge-transfer complex, and report their extinction coefficient values. Furthermore, with X-ray diffraction, atomic force microscopy and electrical conductivity measurements, we study the impact of processing technique and doping mechanism on the morphology and thereby, charge transport through the doped films.
This work demonstrates that the doping mechanism and type of doping-induced species formed are strongly influenced by the polymer backbone arrangement rather than dopant shape/size. The ability of the polymer chain to aggregate is found to be crucial for efficient charge transfer (ionization) and polaron delocalization. At the same time, our results suggest that the high ionization efficiency of a dopant–polymer system in solution may subsequently hinder efficient charge transport in the solid-state due to the reduction in the fraction of tie chains, which enable charges to move efficiently between aggregated domains in the films. This study demonstrates the complex multifaceted nature of polymer doping while providing important hints for the future design of dopant-host systems and film fabrication techniques.
In a very simplified view, the plant leaf growth can be reduced to two processes, cell division and cell expansion, accompanied by expansion of their surrounding cell walls. The vacuole, as being the largest compartment of the plant cell, plays a major role in controlling the water balance of the plant. This is achieved by regulating the osmotic pressure, through import and export of solutes over the vacuolar membrane (the tonoplast) and by controlling the water channels, the aquaporins. Together with the control of cell wall relaxation, vacuolar osmotic pressure regulation is thought to play an important role in cell expansion, directly by providing cell volume and indirectly by providing ion and pH homestasis for the cytosoplasm. In this thesis the role of tonoplast protein coding genes in cell expansion in the model plant Arabidopsis thaliana is studied and genes which play a putative role in growth are identified. Since there is, to date, no clearly identified protein localization signal for the tonoplast, there is no possibility to perform genome-wide prediction of proteins localized to this compartment. Thus, a series of recent proteomic studies of the tonoplast were used to compile a list of cross-membrane tonoplast protein coding genes (117 genes), and other growth-related genes from notably the growth regulating factor (GRF) and expansin families were included (26 genes). For these genes a platform for high-throughput reverse transcription quantitative real time polymerase chain reaction (RT-qPCR) was developed by selecting specific primer pairs. To this end, a software tool (called QuantPrime, see http://www.quantprime.de) was developed that automatically designs such primers and tests their specificity in silico against whole transcriptomes and genomes, to avoid cross-hybridizations causing unspecific amplification. The RT-qPCR platform was used in an expression study in order to identify candidate growth related genes. Here, a growth-associative spatio-temporal leaf sampling strategy was used, targeting growing regions at high expansion developmental stages and comparing them to samples taken from non-expanding regions or stages of low expansion. Candidate growth related genes were identified after applying a template-based scoring analysis on the expression data, ranking the genes according to their association with leaf expansion. To analyze the functional involvement of these genes in leaf growth on a macroscopic scale, knockout mutants of the candidate growth related genes were screened for growth phenotypes. To this end, a system for non-invasive automated leaf growth phenotyping was established, based on a commercially available image capture and analysis system. A software package was developed for detailed developmental stage annotation of the images captured with the system, and an analysis pipeline was constructed for automated data pre-processing and statistical testing, including modeling and graph generation, for various growth-related phenotypes. Using this system, 24 knockout mutant lines were analyzed, and significant growth phenotypes were found for five different genes.
Future magnetic recording industry needs a high-density data storage technology. However, switching the magnetization of small bits requires high magnetic fields that cause excessive heat dissipation. Therefore, controlling magnetism without applying external magnetic field is an important research topic for potential applications in data storage devices with low power consumption. Among the different approaches being investigated, two of them stand out, namely i) all-optical helicity dependent switching (AO-HDS) and ii) ferroelectric control of magnetism. This thesis aims to contribute towards a better understanding of the physical processes behinds these effects as well as reporting new and exciting possibility for the optical and/or electric control of magnetic properties. Hence, the thesis contains two differentiated chapters of results; the first devoted to AO-HDS on TbFe alloys and the second to the electric field control of magnetism in an archetypal Fe/BaTiO3 system.
In the first part, the scalability of the AO-HDS to small laser spot-sizes of few microns in the ferrimagnetic TbFe alloy is investigated by spatially resolving the magnetic contrast with photo-emission electron microscopy (PEEM) and X-ray magnetic circular dichroism (XMCD). The results show that the AO-HDS is a local effect within the laser spot size that occurs in the ring-shaped region in the vicinity of thermal demagnetization. Within the ring region, the helicity dependent switching occurs via thermally activated domain wall motion. Further, the thesis reports on a novel effect of thickness dependent inversion of the switching orientation. It addresses some of the important questions like the role of laser heating and the microscopic mechanism driving AO-HDS.
The second part of the thesis focuses on the electric field control of magnetism in an artificial multiferroic heterostructure. The sample consists of an Fe wedge with thickness varying between 0:5 nm and 3 nm, deposited on top of a ferroelectric and ferroelastic BaTiO3 [001]-oriented single crystal substrate. Here, the magnetic contrast is imaged via PEEM and XMCD as a function of out-of-plane voltage. The results show the evidence of the electric field control of superparamagnetism mediated by a ferroelastic modification of the magnetic anisotropy. The changes in the magnetoelastic anisotropy drive the transition from the superparamagnetic to superferromagnetic state at localized sample positions.
Background: Physical fitness is a key aspect of children’s ability to perform activities of daily living, engage in leisure activities, and is associated with important health characteristics. As such, it shows multi-directional associations with weight status as well as executive functions, and varies according to a variety of moderating factors, such as the child’s gender, age, geographical location, and socioeconomic conditions and context. The assessment and monitoring of children’s physical fitness has gained attention in recent decades, as has the question of how to promote physical fitness through the implementation of a variety of programs and interventions. However, these programs and interventions rarely focus on children with deficits in their physical fitness. Due to their deficits, these children are at the highest risk of suffering health impairments compared to their more average fit peers. In efforts to promote physical fitness, schools could offer promising and viable approaches to interventions, as they provide access to large youth populations while providing useful infrastructure. Evidence suggests that school-based physical fitness interventions, particularly those that include supplementary physical education, are useful for promoting and improving physical fitness in children with normal fitness. However, there is little evidence on whether these interventions have similar or even greater effects on children with deficits in their physical fitness. Furthermore, the question arises whether these measures help to sustainably improve the development/trajectories of physical fitness in these children.
The present thesis aims to elucidate the following four objectives: (1) to evaluate the effects of a 14 week intervention with 2 x 45 minutes per week additional remedial physical education on physical fitness and executive function in children with deficits in their physical fitness; (2) to assess moderating effects of body height and body mass on physical fitness components in children with physical fitness deficits; (3) to assess moderating effects of age and skeletal growth on physical fitness in children with physical fitness deficits; and (4) to analyse moderating effects of different physical fitness components on executive function in children with physical fitness deficits.
Methods: Using physical fitness data from the EMOTIKON study, 76 third graders with physical fitness deficits were identified in 11 schools in Brandenburg state that met the requirements for implementing a remedial physical education intervention (i.e., employing specially trained physical education teachers). The fitness intervention was implemented in a cross-over design and schools were randomly assigned to either an intervention-control or control-intervention group. The remedial physical education intervention consisted of a 14 week, 2 x 45 minutes per week remedial physical education curriculum supplemented by a physical exercise homework program. Assessments were conducted at the beginning and end of each intervention and control period, and further assessments were conducted at the beginning and end of each school year until the end of sixth grade. Physical fitness as the primary outcome was assessed using fitness tests implemented in the EMOTIKON study (i.e., lower body muscular strength (standing long jump), speed (20 m sprint), cardiorespiratory fitness (6 min run), agility (star run), upper body muscular strength (ball push test), and balance (one leg balance)). Executive functions as a secondary outcome were assessed using attention and psychomotor processing speed (digit symbol substitution test), mental flexibility and fine motor skills (trail making test), and inhibitory control (Simon task). Anthropometric measures such as body height, body mass, maturity offset, and body composition parameters, as well as socioeconomic information were recorded as potential moderators.
Results: (1) The evaluation of possible effects of the remedial physical education intervention on physical fitness and executive functions of children with deficits in their physical fitness did not reveal any detectable intervention-related improvements in physical fitness or executive functions. The implemented analysis strategies also showed moderating effects of body mass index (BMI) on performance in 6 min run, star run, and standing long jump, with children with a lower BMI performing better, moderating effects of proximity to Berlin on performance in the 6 min run and standing long jump, better performances being found in children living closer to Berlin, and overall gendered differences in executive function test performance, with boys performing better compared to girls. (2) Analysing moderating effects of body height and body mass on physical fitness performance, better overall physical fitness performance was found for taller children. For body mass, a negative effect was found on performance in the 6 min run (linear), standing long jump (linear), and 20 m sprint (quadratic), with better performance associated with lighter children, and a positive effect of body mass on performance in the ball push test, with heavier children performing better. In addition, the analysis revealed significant interactions between body height and body mass on performance in 6 min run and 20 m sprint, with higher body mass being associated with performance improvements in larger children, while higher body mass was associated with performance declines in smaller children. In addition, the analysis revealed overall age-related improvements in physical fitness and was able to show that children with better overall physical fitness also elicit greater age-related improvements. (3) In the analysis of moderating effects of age and maturity offset on physical fitness performances, two unrotated principal components of z-transformed age and maturity offset values were calculated (i.e., relative growth = (age + maturity offset)/2; growth delay = (age - maturity offset)) to avoid colinearity. Analysing these constructs revealed positive effects of relative growth on performances in star run, 20 m sprint, and standing long jump, with children of higher relative growth performing better. For growth delay, positive effects were found on performances in 6 min run and 20 m sprint, with children having larger growth delays showing better performances. Further, the model revealed gendered differences in 6 min run and 20 m sprint performances with girls performing better than boys. (4) Analysing the effects of physical fitness tests on executive function revealed a positive effect of star run and one leg balance performance and a negative effect of 6 min run performance on reaction speed in the Simon task. However, these effects were not detectable when individual differences were accounted for. Then these effects showed overall positive effects, with better performances being associated with faster reaction speeds. In addition, the analysis revealed a positive correlation between overall reaction speed and effects of the 6 min run, suggesting that children with greater effects of 6 min run had faster overall reaction speeds. Negative correlations were found between star run effects and age effects on Simon task reaction speed, meaning that children with larger star run effects had smaller age effects, and between 6 min run effects and star run effects on Simon task reaction speed, meaning that children with larger 6 min run effects tended to have smaller star run effects on Simon task reaction speed and vice versa.
Conclusions: (1) The lack of detectable intervention-related effects could have been caused by an insufficient intervention period, by the implementation of comprehensive and thus non- specific exercises, or by both. Accordingly, longer intervention periods and/or more specific exercises may have been more beneficial and could have led to detectable improvements in physical fitness and/or executive function. However, it remains unclear whether these interventions can benefit children with deficits in physical fitness, as it is possible that their deficits are not caused by a mere lack of exercise, but rather depend on the socioeconomic conditions of the children and their families and areas. Therefore, further research is needed to assess the moderation of physical fitness in children with physical fitness deficits and, in particular, the links between children’s environment and their physical fitness trajectories. (2) Findings from this work suggest that using BMI as a composite of body height and body mass may not be able to capture the variation associated with these parameters and their interactions. In particular, because of their multidirectional associations, further research would help elucidate how BMI and its subcomponents influence physical fitness and how they vary between children with and without physical fitness deficits. (3) The assessment of growth- related changes indicated negative effects associated with the growth spurt approaching age of peak height velocity, and furthermore showed significant differences in these effects between children. Thus, these effects and possible interindividual differences should be considered in the assessment of the development of physical fitness in children. (4) Furthermore, this work has shown that the associations between physical fitness and executive functions vary between children and may be moderated by children’s socioeconomic conditions and the structure of their daily activities. Further research is needed to explore these associations using approaches that account for individual variance.
En el presente trabajo se realizó una investigación multidisciplinaria combinando métodos de geomorfología tectónica con estudios geofisicos y estructurales, focalizados principalmente en la caracterización neotectónica de ambos faldeos de la sierra de La Candelaria y del extremo sur de la cuenca de Metán. La zona de estudio se encuentra ubicada en la región limítrofe entre las provincias de Salta y Tucumán y pertenece a la provincia geológica del Sistema Santa Bárbara.
El principal objetivo consistió en contextualizar las evidencias de actividad tectónica cuaternaria de la región mediante la propuesta de un modelo estructural novedoso, con el propósito de incrementar la información disponible sobre estructuras neotectónicas y su potencial sismogénico. Con este fin, se aplicaron e integraron diversas técnicas tales como la interpretación de líneas sísmicas de reflexión, construcción de secciones estructurales balanceadas, y métodos geofísicos someros, para constatar el comportamiento en profundidad tanto de las estructuras geológicas identificadas en superficie como de las posibles fallas ciegas corticales involucradas.
En primer lugar, se realizó un relevamiento regional del área de estudio empleando imágenes satelitales multiespectrales LANDSAT y SENTINEL 2, que permitieron reconocer diferentes niveles de abanicos aluviales y terrazas fluviales cuaternarios. Mediante la determinación de diferentes indicadores morfométricos en modelos de elevación digital (MED), junto con observaciones de campo, fue posible identificar evidencias de deformación sobre dichos niveles cuaternarios que han sido relacionadas genéticamente con cuatro fallas neotectónicas. Tres de ellas (fallas Arias, El Quemado y Copo Quile) fueron seleccionadas para efectuar estudios de mayor detalle por medio de la aplicación de métodos de geofísica somera (tomografía eléctrica resistiva (ERT) y tomografía sísmica de refracción Sísmica (SRT)), que permitieron corroborar su existencia en profundidad, realizar inferencias geométricas y cinemáticas, y estimar la magnitud de la deformación reciente. Las fallas Arias y El Quemado fueron interpretadas como fallas inversas relacionadas con deslizamiento flexural interstratal, mientras que la falla Copo Quile se interpretó como una falla inversa ciega de bajo ángulo.También se realizó una interpretación conjunta de líneas sísmicas de reflexión y pozos exploratorios pertenecientes a áreas hidrocarburíferas de las cuencas de Choromoro y Metán con el fin de contextualizar las principales estructuras reconocidas en el marco estratigráfico y tectónico regional. Toda la información fue integrada en una sección estructural balanceada mediante técnicas de modelado cinemático. Dicho modelo permite inferir que la deformación cuaternaria reconocida está relacionada al desplazamiento del basamento a lo largo de un corrimiento ciego, responsable del levantamiento de la sierra de La Candelaria y el cerr Cantero. Asimismo, el modelo cinemático permite interpretar la ubicación aproximada de los principales niveles de despegue que controlan el estilo de deformación. El nivel de despegue más somero, que controla la deformación de la cobertura sedimentaria se encuentra a 4 km de profundidad, a 21 km se estima la presencia de otra zona de cizalla subhorizontal dentro del basamento.
Finalmente, a partir de la integración de todos los resultados obtenidos, se evaluó el potencial sismogénico de las fallas en la zona de estudio. Las fallas de primer orden que controlan la deformación en la zona son las responsables de los grandes terremotos. Mientras, las fallas Cuaternarias flexodeslizantes e inversas afectan solamente a la cobertura sedimentaria y serían estructuras de segundo orden que acomodan la deformación y fueron activadas durante el cuaternario con movimientos asísmicos y/o sísmicos de muy baja magnitud.
Estos resultados permiten inferir que el corrimiento La Candelaria constituye una fuente sismogénica potencial de importancia para la región, donde se ubican numerosas poblaciones y obras civiles de envergadura. Por otra parte, la sección estructural balanceada implica la presencia de otras fallas ciegas de distinto orden de magnitud que podrían ser posibles fuentes sismogénicas profundas adicionales, marcando la necesidad de continuar con el desarrollo de este tipo de estudios en esta región tectónicamente activa.
Mathematical modeling of biological systems is a powerful tool to systematically investigate the functions of biological processes and their relationship with the environment. To obtain accurate and biologically interpretable predictions, a modeling framework has to be devised whose assumptions best approximate the examined scenario and which copes with the trade-off of complexity of the underlying mathematical description: with attention to detail or high coverage. Correspondingly, the system can be examined in detail on a smaller scale or in a simplified manner on a larger scale. In this thesis, the role of photosynthesis and its related biochemical processes in the context of plant metabolism was dissected by employing modeling approaches ranging from kinetic to stoichiometric models. The Calvin-Benson cycle, as primary pathway of carbon fixation in C3 plants, is the initial step for producing starch and sucrose, necessary for plant growth. Based on an integrative analysis for model ranking applied on the largest compendium of (kinetic) models for the Calvin-Benson cycle, those suitable for development of metabolic engineering strategies were identified. Driven by the question why starch rather than sucrose is the predominant transitory carbon storage in higher plants, the metabolic costs for their synthesis were examined. The incorporation of the maintenance costs for the involved enzymes provided a model-based support for the preference of starch as transitory carbon storage, by only exploiting the stoichiometry of synthesis pathways. Many photosynthetic organisms have to cope with processes which compete with carbon fixation, such as photorespiration whose impact on plant metabolism is still controversial. A systematic model-oriented review provided a detailed assessment for the role of this pathway in inhibiting the rate of carbon fixation, bridging carbon and nitrogen metabolism, shaping the C1 metabolism, and influencing redox signal transduction. The demand of understanding photosynthesis in its metabolic context calls for the examination of the related processes of the primary carbon metabolism. To this end, the Arabidopsis core model was assembled via a bottom-up approach. This large-scale model can be used to simulate photoautotrophic biomass production, as an indicator for plant growth, under so-called optimal, carbon-limiting and nitrogen-limiting growth conditions. Finally, the introduced model was employed to investigate the effects of the environment, in particular, nitrogen, carbon and energy sources, on the metabolic behavior. This resulted in a purely stoichiometry-based explanation for the experimental evidence for preferred simultaneous acquisition of nitrogen in both forms, as nitrate and ammonium, for optimal growth in various plant species. The findings presented in this thesis provide new insights into plant system's behavior, further support existing opinions for which mounting experimental evidences arise, and posit novel hypotheses for further directed large-scale experiments.
Plastic pollution is ubiquitous on the planet since several millions of tons of plastic waste enter aquatic ecosystems each year. Furthermore, the amount of plastic produced is expected to increase exponentially shortly. The heterogeneity of materials, additives and physical characteristics of plastics are typical of these emerging contaminants and affect their environmental fate in marine and freshwaters. Consequently, plastics can be found in the water column, sediments or littoral habitats of all aquatic ecosystems. Most of this plastic debris will fragment as a product of physical, chemical and biological forces, producing particles of small size. These particles (< 5mm) are known as “microplastics” (MP). Given their high surface-to-volume ratio, MP stimulate biofouling and the formation of biofilms in aquatic systems.
As a result of their unique structure and composition, the microbial communities in MP biofilms are referred to as the “Plastisphere.” While there is increasing data regarding the distinctive composition and structure of the microbial communities that form part of the plastisphere, scarce information exists regarding the activity of microorganisms in MP biofilms. This surface-attached lifestyle is often associated with the increase in horizontal gene transfer (HGT) among bacteria. Therefore, this type of microbial activity represents a relevant function worth to be analyzed in MP biofilms. The horizontal exchange of mobile genetic elements (MGEs) is an essential feature of bacteria. It accounts for the rapid evolution of these prokaryotes and their adaptation to a wide variety of environments. The process of HGT is also crucial for spreading antibiotic resistance and for the evolution of pathogens, as many MGEs are known to contain antibiotic resistance genes (ARGs) and genetic determinants of pathogenicity.
In general, the research presented in this Ph.D. thesis focuses on the analysis of HGT and heterotrophic activity in MP biofilms in aquatic ecosystems. The primary objective was to analyze the potential of gene exchange between MP bacterial communities vs. that of the surrounding water, including bacteria from natural aggregates. Moreover, the thesis addressed the potential of MP biofilms for the proliferation of biohazardous bacteria and MGEs from wastewater treatment plants (WWTPs) and associated with antibiotic resistance. Finally, it seeks to prove if the physiological profile of MP biofilms under different limnological conditions is divergent from that of the water communities. Accordingly, the thesis is composed of three independent studies published in peer-reviewed journals. The two laboratory studies were performed using both model and environmental microbial communities. In the field experiment, natural communities from freshwater ecosystems were examined.
In Chapter I, the inflow of treated wastewater into a temperate lake was simulated with a concentration gradient of MP particles. The effects of MP on the microbial community structure and the occurrence of integrase 1 (int 1) were followed. The int 1 is a marker associated with mobile genetic elements and known as a proxy for anthropogenic effects on the spread of antimicrobial resistance genes. During the experiment, the abundance of int1 increased in the plastisphere with increasing MP particle concentration, but not in the surrounding water. In addition, the microbial community on MP was more similar to the original wastewater community with increasing microplastic concentrations. Our results show that microplastic particles indeed promote persistence of standard indicators of microbial anthropogenic pollution in natural waters.
In Chapter II, the experiments aimed to compare the permissiveness of aquatic bacteria towards model antibiotic resistance plasmid pKJK5, between communities that form biofilms on MP vs. those that are free-living. The frequency of plasmid transfer in bacteria associated with MP was higher when compared to bacteria that are free-living or in natural aggregates. Moreover, comparison increased gene exchange occurred in a broad range of phylogenetically-diverse bacteria. The results indicate a different activity of HGT in MP biofilms, which could affect the ecology of aquatic microbial communities on a global scale and the spread of antibiotic resistance.
Finally, in Chapter III, physiological measurements were performed to assess whether microorganisms on MP had a different functional diversity from those in water. General heterotrophic activity such as oxygen consumption was compared in microcosm assays with and without MP, while diversity and richness of heterotrophic activities were calculated by using Biolog® EcoPlates. Three lakes with different nutrient statuses presented differences in MP-associated biomass build up. Functional diversity profiles of MP biofilms in all lakes differed from those of the communities in the surrounding water, but only in the oligo-mesotrophic lake MP biofilms had a higher functional richness compared to the ambient water. The results support that MP surfaces act as new niches for aquatic microorganisms and can affect global carbon dynamics of pelagic environments.
Overall, the experimental works presented in Chapters I and II support a scenario where MP pollution affects HGT dynamics among aquatic bacteria. Among the consequences of this alteration is an increase in the mobilization and transfer efficiency of ARGs. Moreover, it supposes that changes in HGT can affect the evolution of bacteria and the processing of organic matter, leading to different catabolic profiles such as demonstrated in Chapter III. The results are discussed in the context of the fate and magnitude of plastic pollution and the importance of HGT for bacterial evolution and the microbial loop, i.e., at the base of aquatic food webs. The thesis supports a relevant role of MP biofilm communities for the changes observed in the aquatic microbiome as a product of intense human intervention.
Since 1980 Iraq passed through various wars and conflicts including Iraq-Iran war, Saddam Hussein’s the Anfals and Halabja campaigns against the Kurds and the killing campaigns against Shiite in 1986, Saddam Hussein’s invasion of Kuwait in August 1990, the Gulf war in 1990, Iraq war in 2003 and the fall of Saddam, the conflicts and chaos in the transmission of power after the death of Saddam, and the war against ISIS . All these wars left severe impacts in most households in Iraq; on women and children in particular.
The consequences of such long wars could be observed in all sectors including economic, social, cultural and religious sectors. The social structure, norms and attitudes are intensely affected. Many women specifically divorced women found them-selves in challenging different difficulties such as social as well as economic situations. Thus the divorced women in Iraqi Kurdistan are the focus of this research.
Considering the fact that there is very few empirical researches on this topic, a constructivist grounded theory methodology (CGT) is viewed as reliable in order to come up with a comprehensive picture about the everyday life of divorced women in Iraqi Kurdistan. Data collected in Sulaimani city in Iraqi Kurdistan. The work of Kathy Charmaz was chosen to be the main methodological context of the research and the main data collection method was individual intensive narrative interviews with divorced women.
Women generally and divorced women specifically in Iraqi Kurdistan are living in a patriarchal society that passing through many changes due to the above mentioned wars among many other factors. This research is trying to study the everyday life of divorced women in such situations and the forms of social insecurity they are experiencing. The social institutions starting from the family as a very significant institution for women to the governmental and non-governmental institutions that are working to support women, and the copying strategies, are in focus in this research. The main research argument is that the family is playing ambivalent roles in divorced women’s life. For instance, on one side families are revealed to be an essential source of security to most respondents, on the other side families posed also many threats and restrictions on those women. This argument supported by what called by Suad joseph "the paradox of support and suppression" . Another important finding is that the stat institution(laws , constitutions ,Offices of combating violence against woman and family) are supporting women somehow and offering them protection from the insecurities but it is clear that the existence of the laws does not stop the violence against women in Iraqi Kurdistan, As explained by Pateman because the laws /the contract is a sexual-social contract that upholds the sex rights of males and grants them more privileges than females. The political instability, Tribal social norms also play a major role in influencing the rule of law.
It is noteworthy to refer that analyzing the interviews in this research showed that in spite that divorced women living in insecurities and facing difficulties but most of the respondents try to find a coping strategies to tackle difficult situations and to deal with the violence they face; these strategies are bargaining, sometimes compromising or resisting …etc. Different theories used to explain these coping strategies such as bargaining with patriarchy. Kandiyoti who stated that women living under certain restraints struggle to find way and strategies to enhance their situations. The research finding also revealed that the western liberal feminist view of agency is limited this is agree with Saba Mahmood and what she explained about Muslim women agency. For my respondents, who are divorced women, their agency reveals itself in different ways, in resisting or compromising with or even obeying the power of male relatives, and the normative system in the society. Agency is also explained the behavior of women contacting formal state institutions in cases of violence like the police or Offices of combating violence against woman and family.
Kosmologie beschreibt die Entwicklung des Universums als Ganzes. Kosmologische Entdeckungen in Theorie und Praxis haben daher unser modernes wissenschaftliches Weltbild entscheidend geprägt. Die Vermittlung eines modernen Weltbildes durch Unterricht ist ein häufiger Wunsch in der naturwissenschaftlichen Bildungsdiskussion. Dennoch existieren weiterhin Forschungs- und Entwicklungsbedarfe. Kosmologische Themen finden sich häufig in den Medien und sind gleichzeitig weiter vom Alltag entfernt, so dass sich hier besonders leicht wissenschaftlich inkorrekte Vorstellungen entwickeln können, die zu Problemen im Unterricht führen können.
Das Ziel dieser wissenschaftlichen Arbeit ist es, zu diesem Forschungsgebiet beizutragen und die Voraussetzungen hinsichtlich vorhandener Vorkenntnisse und Präkonzepte in Kosmologie, mit denen Schülerinnen und Schüler in den Unterricht kommen, zu untersuchen und anschließend mit denen anderer Länder zu vergleichen. Dies erfolgt anhand einer qualitativen Inhaltsanalyse eines offenen Fragebogens. Auf dieser Grundlage wird schließlich ein Multiple-Choice Fragebogen entwickelt, angewendet und evaluiert.
Die Ergebnisse zeigen große Wissenslücken im Bereich der Kosmologie auf und geben erste Hinweise auf vorhandene Unterschiede zwischen den Ländern. Es existieren ebenfalls einige teils weit verbreitete wissenschaftlich inkorrekte Vorstellungen wie beispielsweise die Assoziation des Urknalls mit einer Explosion, der Urknall verursacht durch eine Kollision von Teilchen oder größeren Objekten, oder die Vorstellung der Ausdehnung des Universums als neue Entdeckungen und/oder Wissen. Des Weiteren gab nur etwa jeder Fünfte das korrekte Alter des Universums oder die Ausdehnung des Universums als einen der drei Belege der Urknalltheorie an, während fast 40% keinen einzigen Beleg nennen konnten. Für den geschlossenen Fragebogen konnten gute Hinweise für verschiedene Validitätsaspekte herausgearbeitet werden und es existieren erste Hinweise darauf, dass der Fragebogen Wissenszuwachs messen kann und damit wahrscheinlich zur Untersuchung der Wirksamkeit von Lerneinheiten eingesetzt werden kann. Auch ein entsprechendes Modell zur Verständnisentwicklung der Ausdehnung des Universums zeigte sich vielversprechend.
Diese Arbeit liefert insgesamt einen Forschungsbeitrag zum Schülervorwissen und Vorstellungen in der Kosmologie und deren Large Scale Assessment. Dies eröffnet die Möglichkeit zukünftiger Forschungen im Bereich von Gruppenvergleichen insbesondere hinsichtlich objektiver Ländervergleiche sowie der Untersuchungen der Wirksamkeit von einzelnen Lerneinheiten als auch Vergleiche verschiedener Lerneinheiten untereinander.
During a dark night, it is possible to observe thousands of stars by eye. All these stars are located within the Milky Way, our home. Not all stars are the same, they can have different sizes, masses, temperatures and ages. Heavy stars do not live long (in astronomical terms), only a few million years, but stars less massive than the Sun can get more than ten billion years old. Such small stars that formed in the beginning of the Universe still shine today. These ancient stars are very helpful to learn more about the early Universe, the First Stars and the history of the Milky Way. But how do you recognise an ancient star? Using their chemical fingerprints! In the beginning of the Universe, there were only two chemical elements: hydrogen and helium (and a tiny bit of lithium). All the heavier elements like carbon, calcium and iron were only made later within stars and their explosions. The amount of chemical elements in the Universe increases with the number of stars that are born, evolve and explode. Stars that form later are born with more heavy elements, or a greater metallicity. In the field of astronomy that is called “Galactic Archaeology”, stars of various metallicities are used to study the history of the Milky Way. In this doctoral thesis, the focus is on metal-poor stars because these are expected to be the oldest and can therefore tell us a lot about the early history of our Galaxy.
Until today, we still have not discovered a metal-free star. The most metal-poor stars, however, give us important insights in the lives and deaths of the First Stars. Many of the oldest, most metal-poor stars have an unexpectedly large amount of carbon, compared to for example iron. These carbon-enhanced metal-poor (CEMP) stars tell us something about the very first stars in the Universe: they somehow produced a lot of carbon. If we look at the precise chemical fingerprints of the CEMP stars, we can learn a lot more. But our interpretation depends on the assumption that the chemical fingerprint of a star does not change during its life. In this thesis, new data is presented that shows that this assumption may be too simple: many extremely metal-poor CEMP stars are members of binary systems. Interactions between two stars in a binary system can pollute the surface of the stars. Likely not all of the CEMP stars in binary systems were actually polluted, but we should be very careful in our interpretations of the fingerprints of these stars.
The CEMP stars and other metal-poor stars are also important for our understanding of the early history of the Milky Way. Most researchers who study metal-poor stars look for these stars in the halo of the Milky Way: a huge diffuse Galactic component containing about 1% of the stars in our Galaxy. However, models predict that the oldest metal-poor stars are located in the center of the Milky Way, in the bulge. The metal-poor inner Galaxy is unfortunately difficult to study due to large amounts of dust between us and the center and an overwhelming majority of metal-rich stars. This thesis presents results from the successful Pristine Inner Galaxy Survey (PIGS), a new survey looking for (and finding) the oldest stars in the bulge of the Milky Way. PIGS is using images with a specific color that is sensitive to the metallicity of stars, and can therefore efficiently select the metal-poor stars among millions of other, more metal-rich stars. The interesting candidates are followed up with spectroscopy, which is then analysed using two independent methods. With this strategy, PIGS has discovered the largest sample of metal-poor stars in the inner Galaxy to date. A new result from the PIGS data is that the metal-poor stars rotate more slowly around the Galactic center compared to the more metal-rich stars, and they show larger randomness in their motions as well. Another important contribution from PIGS is the discovery of tens of CEMP stars in the inner Galaxy, where previously only two such stars were known.
The new results from this thesis help us to understand the First Stars and the early history of the Milky Way. Ongoing and future large surveys will provide us with a lot of additional data in the coming years. It is an exciting time for the field of Galactic Archaeology.
The electrical resistivity tomography (ERT) method is widely used to investigate geological, geotechnical, and hydrogeological problems in inland and aquatic environments (i.e., lakes, rivers, and seas). The objective of the ERT method is to obtain reliable resistivity models of the subsurface that can be interpreted in terms of the subsurface structure and petrophysical properties. The reliability of the resulting resistivity models depends not only on the quality of the acquired data, but also on the employed inversion strategy. Inversion of ERT data results in multiple solutions that explain the measured data equally well. Typical inversion approaches rely on different deterministic (local) strategies that consider different smoothing and damping strategies to stabilize the inversion. However, such strategies suffer from the trade-off of smearing possible sharp subsurface interfaces separating layers with resistivity contrasts of up to several orders of magnitude. When prior information (e.g., from outcrops, boreholes, or other geophysical surveys) suggests sharp resistivity variations, it might be advantageous to adapt the parameterization and inversion strategies to obtain more stable and geologically reliable model solutions. Adaptations to traditional local inversions, for example, by using different structural and/or geostatistical constraints, may help to retrieve sharper model solutions. In addition, layer-based model parameterization in combination with local or global inversion approaches can be used to obtain models with sharp boundaries.
In this thesis, I study three typical layered near-surface environments in which prior information is used to adapt 2D inversion strategies to favor layered model solutions. In cooperation with the coauthors of Chapters 2-4, I consider two general strategies. Our first approach uses a layer-based model parameterization and a well-established global inversion strategy to generate ensembles of model solutions and assess uncertainties related to the non-uniqueness of the inverse problem. We apply this method to invert ERT data sets collected in an inland coastal area of northern France (Chapter~2) and offshore of two Arctic regions (Chapter~3). Our second approach consists of using geostatistical regularizations with different correlation lengths. We apply this strategy to a more complex subsurface scenario on a local intermountain alluvial fan in southwestern Germany (Chapter~4). Overall, our inversion approaches allow us to obtain resistivity models that agree with the general geological understanding of the studied field sites. These strategies are rather general and can be applied to various geological environments where a layered subsurface structure is expected. The flexibility of our strategies allows adaptations to invert other kinds of geophysical data sets such as seismic refraction or electromagnetic induction methods, and could be considered for joint inversion approaches.
Biochemical and physiological studies of Arabidopsis thaliana Diacylglycerol Kinase 7 (AtDGK7)
(2006)
A family of diacylglycerol kinases (DGK) phosphorylates the substrate diacylglycerol (DAG) to generate phosphatidic acid (PA) . Both molecules, DAG and PA, are involved in signal transduction pathways. In the model plant Arabidopsis thaliana, seven candidate genes (named AtDGK1 to AtDGK7) code for putative DGK isoforms. Here I report the molecular cloning and characterization of AtDGK7. Biochemical, molecular and physiological experiments of AtDGK7 and their corresponding enzyme are analyzed. Information from Genevestigator says that AtDGK7 gene is expressed in seedlings and adult Arabidopsis plants, especially in flowers. The AtDGK7 gene encodes the smallest functional DGK predicted in higher plants; but also, has an alternative coding sequence containing an extended AtDGK7 open reading frame, confirmed by PCR and submitted to the GenBank database (under the accession number DQ350135). The new cDNA has an extension of 439 nucleotides coding for 118 additional amino acids The former AtDGK7 enzyme has a predicted molecular mass of ~41 kDa and its activity is affected by pH and detergents. The DGK inhibitor R59022 also affects AtDGK7 activity, although at higher concentrations (i.e. IC50 ~380 µM). The AtDGK7 enzyme also shows a Michaelis-Menten type saturation curve for 1,2-DOG. Calculated Km and Vmax were 36 µM 1,2-DOG and 0.18 pmol PA min-1 mg of protein-1, respectively, under the assay conditions. Former protein AtDGK7 are able to phosphorylate different DAG analogs that are typically found in plants. The new deduced AtDGK7 protein harbors the catalytic DGKc and accessory domains DGKa, instead the truncated one as the former AtDGK7 protein (Gomez-Merino et al., 2005).
The central melanin-concentrating hormone (MCH) system has been intensively studied for its involvement in the regulation of feeding behaviour and body weight regulation. The importance of the neuropeptide MCH in the control of energy balance has been underlined by MCH knock out and Melanin-concentrating hormone receptor subtype 1 (MCHR-1) knock-out animals. The anorectic and anti-obesity effects of selective MCHR-1 antagonists have confirmed the notion that pharmacological blockade of MCHR-1 is a potential therapeutic approach for obesity. First aim of this work is to study the neurochemical “equipment” of MCHR-1 immunoreactive neurons by double-labelling immunohistochemistry within the rat hypothalamus. Of special interest is the neuroanatomical identification of other hypothalamic neuropeptides that are co-distributed with MCHR-1. A second part of this study deals with the examination of neuronal activation patterns after pharmacological or physiological, feeding-related stimuli and was introduced to further understand central regulatory mechanisms of the MCH system. In the first part of work, I wanted to neurochemically characterize MCHR-1 immunoreactive neurons in the rat hypothalamus for colocalisation with neuropeptides of interest. Therefore I performed an immunohistochemical colocalisation study using a specific antibody against MCHR-1 in combination with antibodies against hypothalamic neuropeptides. I showed that MCHR-1 immunoreactivity (IR) was co-localised with orexin A in the lateral hypothalamus, and with adrenocorticotropic hormone and neuropeptide Y in the arcuate nucleus. Additionally, MCHR-1 IR was co-localised with the neuropeptides vasopressin and oxytocin in magnocellular neurons of the supraoptic and paraventricular hypothalamic nucleus and corticotrophin releasing hormone in the parvocellular division of the paraventricular hypothalamic nucleus. Moreover, for the first time MCHR-1 immunoreactivity was found in both the adenohypophyseal and neurohypophyseal part of the rat pituitary. These results provide the neurochemical basis for previously described potential physiological actions of MCH at its target receptor. In particular, the MCHR-1 may be involved not only in food intake regulation, but also in other physiological actions such as fluid regulation, reproduction and stress response, possibly through here examined neuropeptides. Central activation patterns induced by pharmacological or physiological stimulation can be mapped using c-Fos immunohistochemistry. In the first experimental design, central administration (icv) of MCH in the rat brain resulted in acute and significant increase of food and water intake, but this animal treatment did not induce a specific c-Fos induction pattern in hypothalamic nuclei. In contrast, sub-chronic application of MCHR-1 antagonist promoted a significant decrease in food- and water intake during an eight day treatment period. A qualitative analysis of c-Fos immunohistochemistry of sections derived from MCHR-1 antagonist treated animals showed a specific neuronal activation in the paraventricular nucleus, the supraoptic nucleus and the dorsomedial hypothalamus. These results could be substantiated by quantitative evaluation of an automated, software-supported analysis of the c-Fos signal. Additionally, I examined the activation pattern of rats in a restricted feeding schedule (RFS) to identify pathways involved in hunger and satiety. Animals were trained for 9 days to feed during a three hour period. On the last day, food restricted animals was also allowed to feed for the three hours, while food deprived (FD) animals did not receive food. Mapping of neuronal activation showed a clear difference between stareved (FD) and satiated (FR) rats. FD animals showed significant induction of c-Fos in forebrain regions, several hypothalamic nuclei, amygdaloid thalamus and FR animals in the supraoptic nucleus and the paraventricular nucleus of the hypothalamus, and the nucleus of the solitary tract. In the lateral hypothalamus of FD rats, c-Fos IR showed strong colocalisation for Orexin A, but no co-staining for MCH immunoreactivity. However, a large number of c-Fos IR neurons within activated regions of FD and FR animals was co-localised with MCHR-1 within selected regions. To conclude, the experimental set-up of scheduled feeding can be used to induce a specific hunger or satiety activation pattern within the rat brain. My results show a differential activation by hunger signals of MCH neurons and furthermore, demonstrates that MCHR-1 expressing neurons may be essential parts of downstream processing of physiological feeding/hunger stimuli. In the final part of my work, the relevance of here presented studies is discussed with respect to possible introduction of MCHR-1 antagonists as drug candidates for the treatment of obesity.
Back pain is a problem in adolescent athletes affecting postural control which is an important requirement for physical and daily activities whether under static or dynamic conditions. One leg stance and star excursion balance postural control tests are effective in measuring static and dynamic postural control respectively. These tests have been used in individuals with back pain, athletes and non-athletes without first establishing their reliabilities. In addition to this, there is no published literature investigating dynamic posture in adolescent athletes with back pain using the star excursion balance test. Therefore, the aim of the thesis was to assess deficit in postural control in adolescent athletes with and without back pain using static (one leg stance test) and dynamic postural (SEBT) control tests.
Adolescent athletes with and without back pain participated in the study. Static and dynamic postural control tests were performed using one leg stance and SEBT respectively. The reproducibility of both tests was established. Afterwards, it was determined whether there was an association between static and dynamic posture using the measure of displacement of the centre pressure and reach distance respectively. Finally, it was investigated whether there was a difference in postural control in adolescent athletes with and without back pain using the one leg stance test and the SEBT.
Fair to excellent reliabilities was recorded for the static (one leg stance) and dynamic (star excursion balance) postural control tests in the subjects of interest. No association was found between variables of the static and dynamic tests for the adolescent athletes with and without back pain. Also, no statistically significant difference was obtained between adolescent athletics with and without back pain using the static and dynamic postural control test.
One leg stance test and SEBT can be used as measures of postural control in adolescent athletes with and without back pain. Although static and dynamic postural control might be related, adolescent athletes with and without back pain might be using different mechanisms in controlling their static and dynamic posture. Consequently, static and dynamic postural control in adolescent athletes with back pain was not different from those without back pain. These outcome measures might not be challenging enough to detect deficit in postural control in our study group of interest.
Polymer optical fibers (POFs) are a rather new tool for high-speed data transfer by modulated light. They allow the transport of high amounts of data over distances up to about 100 m without be influenced by external electromagnetic fields. Due to organic chemical nature of POFs, they are sensitive to the climate of their environment and therefore the optical fiber properties are as well. Hence, the optical stability is a key issue for long-term applications of POFs. The causes for a loss of optical transmission due to climatic exposures (aging/degradation) are researched by means of chemical analytical tools such as chemiluminescence (CL) and Fourier transform infrared (FTIR) spectroscopy for five different (with respect to manufacturers) step-index multimode PMMA based POFs and for seven different climatic conditions. Three of the five POF samples are studied more in detail to realize the effects of individual parameters and for forecasting longterm optical stability by short-term exposure tests. At first, the unexposed POF components (core, cladding, and bare POF as combination of core and cladding) are characterized with respect to important physical and chemical properties. The glass transition temperature Tg, and the melting temperature Tm are in the region of 120 °C to 140 °C, the molecular weight (Mw) of cores is in the order of 105 g mol-1. POFs are found to have different chemical compositions of their claddings as could be detected by FTIR, but identical compositions of their cores. Two of the POFs are exposed as cables (core, cladding and jacket) for about 3300 hours to the climate 92 °C / 95 % relative humidity (RH) resulting in a different transmission decrease. Investigating the related unexposed and exposed bare POFs for degradation using CL, FTIR, thermogravimetry (TG), UV/visible transmittance and gel permeation chromatography (GPC) suggest that claddings of POFs are more affected than cores. Probably the observed loss of transmission is mainly due to increased light absorption and imperfections at the core-cladding boundary caused by a large degradation of claddings. Hence, it is highly possible that the optical transmission stability of POFs is governed mainly by the thermo-oxidative stability of the cladding and minor of the core. Three bare POFs (core and cladding only) are exposed for different duration of exposure time (30 hours to 4500 hours) to 92 °C / 95 %RH, 92 °C / 50 %RH, 50 °C / 95 %RH, 90 °C / low humidity, 100 °C / low humidity, 110 °C / low humidity and 120 °C / low humidity. In these climates their transmission variations are found to be different from each other, too. The outcomes strongly inform that under high temperature and high humid climates physical changes such as volume expansion, are the main sources for the loss of optical transmission. Also, the optical transmission stability of POFs is found to be dependent on chemical compositions of claddings. Under high temperature and low humid conditions, a loss of transmission at the early stages of the exposure is mainly caused by physical changes, presumable by corecladding interface imperfections. For the later stages of exposures it is proposed to an additional increase of light absorption by core and cladding owes to degradation. Optical simulation results obtained parallel by Mr. L. Jankowski (a PhD student of BAM) are found to confirm these results. For bare POFs, too, the optical stability of POFs seems to depend on their thermo-oxidative stability. Some short-term exposure tests are conducted to realize influences of individual climatic parameters on the transmission property of POFs. It is found that at stationary high temperature and variable humidity conditions POFs display to a certain amount a reversible transmission loss due to physically absorbed water. But in the case of varying temperature and constant high humidity such reversibility is hardly noticeable. However, at room temperature and varying humidity, POFs display fully reversible transmission loss. The whole research described above has to be regarded as a starting point for further investigations. The restricted distribution of fundamental POF data by the manufacturers and the time consuming aging by climatic exposures restrict the results more or less to the samples, investigated here. Significant general statements require for example additional information concerning the variation of POF properties due to production. Nevertheless the tests, described here, have the capability for approximating and forecasting the long-term optical transmission stability of POFs. -------------- Auch im Druck erschienen: Appajaiah, Anilkumar: Climatic stability of polymer optical fibers (POF) / Anilkumar Appajaiah. - Bremerhaven : Wirtschaftsverl. NW, Verl. für neue Wiss., 2005. - Getr. Zählung [ca. 175 S.]. : Ill., graph. Darst. - (BAM-Dissertationsreihe ; 9) ISBN 3-86509-302-7
The Central Andean region is characterized by diverse climate zones with sharp transitions between them. In this work, the area of interest is the South-Central Andes in northwestern Argentina that borders with Bolivia and Chile. The focus is the observation of soil moisture and water vapour with Global Navigation Satellite System (GNSS) remote-sensing methodologies. Because of the rapid temporal and spatial variations of water vapour and moisture circulations, monitoring this part of the hydrological cycle is crucial for understanding the mechanisms that control the local climate. Moreover, GNSS-based techniques have previously shown high potential and are appropriate for further investigation. This study includes both logistic-organization effort and data analysis. As for the prior, three GNSS ground stations were installed in remote locations in northwestern Argentina to acquire observations, where there was no availability of third-party data.
The methodological development for the observation of the climate variables of soil moisture and water vapour is independent and relies on different approaches. The soil-moisture estimation with GNSS reflectometry is an approximation that has demonstrated promising results, but it has yet to be operationally employed. Thus, a more advanced algorithm that exploits more observations from multiple satellite constellations was developed using data from two pilot stations in Germany. Additionally, this algorithm was slightly modified and used in a sea-level measurement campaign. Although the objective of this application is not related to monitoring hydrological parameters, its methodology is based on the same principles and helps to evaluate the core algorithm. On the other hand, water-vapour monitoring with GNSS observations is a well-established technique that is utilized operationally. Hence, the scope of this study is conducting a meteorological analysis by examining the along-the-zenith air-moisture levels and introducing indices related to the azimuthal gradient.
The results of the experiments indicate higher-quality soil moisture observations with the new algorithm. Furthermore, the analysis using the stations in northwestern Argentina illustrates the limits of this technology because of varying soil conditions and shows future research directions. The water-vapour analysis points out the strong influence of the topography on atmospheric moisture circulation and rainfall generation. Moreover, the GNSS time series allows for the identification of seasonal signatures, and the azimuthal-gradient indices permit the detection of main circulation pathways.
Changing the perspective sometimes offers completely new insights to an already well-known phenomenon. Exercising behavior, defined as planned, structured and repeated bodily movements with the intention to maintain or increase the physical fitness (Caspersen, Powell, & Christenson, 1985), can be thought of as such a well-known phenomenon that has been in the scientific focus for many decades (Dishman & O’Connor, 2005). Within these decades a perspective that assumes rational and controlled evaluations as the basis for decision making, was predominantly used to understand why some people engage in physical activity and others do not (Ekkekakis & Zenko, 2015).
Dual-process theories (Ekkekakis & Zenko, 2015; Payne & Gawronski, 2010) provide another perspective, that is not exclusively influenced by rational reasoning. These theories differentiate two different processes that guide behavior “depending on whether they operate automatically or in a controlled fashion“ (Gawronski & Creighton, 2012, p. 282). Following this line of thought, exercise behavior is not solely influenced by thoughtful deliberations (e.g. concluding that exercising is healthy) but also by spontaneous affective reactions (e.g. disliking being sweaty while exercising). The theoretical frameworks of dual-process models are not new in psychology (Chaiken & Trope, 1999) and have already been used for the explanation of numerous behaviors (e.g. Hofmann, Friese, & Wiers, 2008; Huijding, de Jong, Wiers, & Verkooijen, 2005). However, they have only rarely been used for the explanation of exercise behavior (e.g. Bluemke, Brand, Schweizer, & Kahlert, 2010; Conroy, Hyde, Doerksen, & Ribeiro, 2010; Hyde, Doerksen, Ribeiro, & Conroy, 2010). The assumption of two dissimilar behavior influencing processes, differs fundamentally from previous theories and thus from the research that has been conducted in the last decades in exercise psychology. Research mainly concentrated on predictors of the controlled processes and addressed the identified predictors in exercise interventions (Ekkekakis & Zenko, 2015; Hagger, Chatzisarantis, & Biddle, 2002).
Predictors arising from the described automatic processes, for example automatic evaluations for exercising (AEE), have been neglected in exercise psychology for many years. Until now, only a few researchers investigated the influence of these AEE for exercising behavior (Bluemke et al., 2010; Brand & Schweizer, 2015; Markland, Hall, Duncan, & Simatovic, 2015). Marginally more researchers focused on the impact of AEE for physical activity behavior (Calitri, Lowe, Eves, & Bennett, 2009; Conroy et al., 2010; Hyde et al., 2010; Hyde, Elavsky, Doerksen, & Conroy, 2012). The extant studies mainly focused on the quality of AEE and the associated quantity of exercise (exercise much or little; Bluemke et al., 2010; Calitri et al., 2009; Conroy et al., 2010; Hyde et al., 2012). In sum, there is still a dramatic lack of empirical knowledge, when applying dual-process theories to exercising behavior, even though these theories have proven to be successful in explaining behavior in many other health-relevant domains like eating, drinking or smoking behavior (e.g. Hofmann et al., 2008).
The main goal of the present dissertation was to collect empirical evidence for the influence of AEE on exercise behavior and to expand the so far exclusively correlational studies by experimentally controlled studies. By doing so, the ongoing debate on a paradigm shift from controlled and deliberative influences of exercise behavior towards approaches that consider automatic and affective influences (Ekkekakis & Zenko, 2015) should be encouraged. All three conducted publications are embedded in dual-process theorizing (Gawronski & Bodenhausen, 2006, 2014; Strack & Deutsch, 2004). These theories offer a theoretical framework that could integrate the established controlled variables of exercise behavior explanation and additionally consider automatic factors for exercise behavior like AEE.
Taken together, the empirical findings collected suggest that AEE play an important and diverse role for exercise behavior. They represent exercise setting preferences, are a cause for short-term exercise decisions and are decisive for long-term exercise adherence. Adding to the few already present studies in this field, the influence of (positive) AEE for exercise behavior was confirmed in all three presented publications. Even though the available set of studies needs to be extended in prospectively studies, first steps towards a more complete picture have been taken. Closing with the beginning of the synopsis: I think that time is right for a change of perspectives! This means a careful extension of the present theories with controlled evaluations explaining exercise behavior. Dual-process theories including controlled and automatic evaluations could provide such a basis for future research endeavors in exercise psychology.
Gravitational-wave (GW) astrophysics is a field in full blossom. Since the landmark detection of GWs from a binary black hole on September 14th 2015, fifty-two compact-object binaries have been reported by the LIGO-Virgo collaboration. Such events carry astrophysical and cosmological information ranging from an understanding of how black holes and neutron stars are formed, what neutron stars are composed of, how the Universe expands, and allow testing general relativity in the highly-dynamical strong-field regime. It is the goal of GW astrophysics to extract such information as accurately as possible. Yet, this is only possible if the tools and technology used to detect and analyze GWs are advanced enough. A key aspect of GW searches are waveform models, which encapsulate our best predictions for the gravitational radiation under a certain set of parameters, and that need to be cross-correlated with data to extract GW signals. Waveforms must be very accurate to avoid missing important physics in the data, which might be the key to answer the fundamental questions of GW astrophysics. The continuous improvements of the current LIGO-Virgo detectors, the development of next-generation ground-based detectors such as the Einstein Telescope or the Cosmic Explorer, as well as the development of the Laser Interferometer Space Antenna (LISA), demand accurate waveform models. While available models are enough to capture the low spins, comparable-mass binaries routinely detected in LIGO-Virgo searches, those for sources from both current and next-generation ground-based and spaceborne detectors must be accurate enough to detect binaries with large spins and asymmetry in the masses. Moreover, the thousands of sources that we expect to detect with future detectors demand accurate waveforms to mitigate biases in the estimation of signals’ parameters due to the presence of a foreground of many sources that overlap in the frequency band. This is recognized as one of the biggest challenges for the analysis of future-detectors’ data, since biases might hinder the extraction of important astrophysical and cosmological information from future detectors’ data. In the first part of this thesis, we discuss how to improve waveform models for binaries with high spins and asymmetry in the masses. In the second, we present the first generic metrics that have been proposed to predict biases in the presence of a foreground of many overlapping signals in GW data.
For the first task, we will focus on several classes of analytical techniques. Current models for LIGO and Virgo studies are based on the post-Newtonian (PN, weak-field, small velocities) approximation that is most natural for the bound orbits that are routinely detected in GW searches. However, two other approximations have risen in prominence, the post-Minkowskian (PM, weak- field only) approximation natural for unbound (scattering) orbits and the small-mass-ratio (SMR) approximation typical of binaries in which the mass of one body is much bigger than the other. These are most appropriate to binaries with high asymmetry in the masses that challenge current waveform models. Moreover, they allow one to “cover” regions of the parameter space of coalescing binaries, thereby improving the interpolation (and faithfulness) of waveform models. The analytical approximations to the relativistic two-body problem can synergically be included within the effective-one-body (EOB) formalism, in which the two-body information from each approximation can be recast into an effective problem of a mass orbiting a deformed Schwarzschild (or Kerr) black hole. The hope is that the resultant models can cover both the low-spin comparable-mass binaries that are routinely detected, and the ones that challenge current models. The first part of this thesis is dedicated to a study about how to best incorporate information from the PN, PM, SMR and EOB approaches in a synergistic way. We also discuss how accurate the resulting waveforms are, as compared against numerical-relativity (NR) simulations. We begin by comparing PM models, whether alone or recast in the EOB framework, against PN models and NR simulations. We will show that PM information has the potential to improve currently-employed models for LIGO and Virgo, especially if recast within the EOB formalism. This is very important, as the PM approximation comes with a host of new computational techniques from particle physics to exploit. Then, we show how a combination of PM and SMR approximations can be employed to access previously-unknown PN orders, deriving the third subleading PN dynamics for spin-orbit and (aligned) spin1-spin2 couplings. Such new results can then be included in the EOB models currently used in GW searches and parameter estimation studies, thereby improving them when the binaries have high spins. Finally, we build an EOB model for quasi-circular nonspinning binaries based on the SMR approximation (rather than the PN one as usually done). We show how this is done in detail without incurring in the divergences that had affected previous attempts, and compare the resultant model against NR simulations. We find that the SMR approximation is an excellent approximation for all (quasi-circular nonspinning) binaries, including both the equal-mass binaries that are routinely detected in GW searches and the ones with highly asymmetric masses. In particular, the SMR-based models compare much better than the PN models, suggesting that SMR-informed EOB models might be the key to model binaries in the future. In the second task of this thesis, we work within the linear-signal ap- proximation and describe generic metrics to predict inference biases on the parameters of a GW source of interest in the presence of confusion noise from unfitted foregrounds and from residuals of other signals that have been incorrectly fitted out. We illustrate the formalism with simple (yet realistic) LISA sources, and demonstrate its validity against Monte-Carlo simulations. The metrics we describe pave the way for more realistic studies to quantify the biases with future ground-based and spaceborne detectors.
Um die gegenwärtige Transformation der Öffentlichkeit im digitalen Zeitalter erfassen zu können, ist in der Öffentlichkeitstheorie eine erweiterte Perspektive notwendig, die nicht nur den massenmedialen Diskurs, sondern auch die Veränderung sozialer Praktiken und institutioneller Strukturen in den Blick nimmt. Das Ziel dieses Buches besteht darin, die Grundlagen einer solchen Perspektive auf die Theorie digitaler Öffentlichkeiten zu entwickeln. Im vorgeschlagenen Ansatz wird Öffentlichkeit im Anschluss an John Dewey als Prozess verstanden. In seiner prozessualen und funktionalen Bestimmung von Öffentlichkeit liegt eine besondere Originalität, die seinen Ansatz von anderen Öffentlichkeitskonzeptionen unterscheidet. Das Buch liefert sowohl eine systematische Rekonstruktion und Interpretation der Philosophie John Deweys als auch einen Vorschlag zur gesellschaftstheoretischen Deutung des digitalen Wandels.
Data assimilation has been an active area of research in recent years, owing to its wide utility. At the core of data assimilation are filtering, prediction, and smoothing procedures. Filtering entails incorporation of measurements' information into the model to gain more insight into a given state governed by a noisy state space model. Most natural laws are governed by time-continuous nonlinear models. For the most part, the knowledge available about a model is incomplete; and hence uncertainties are approximated by means of probabilities. Time-continuous filtering, therefore, holds promise for wider usefulness, for it offers a means of combining noisy measurements with imperfect model to provide more insight on a given state.
The solution to time-continuous nonlinear Gaussian filtering problem is provided for by the Kushner-Stratonovich equation. Unfortunately, the Kushner-Stratonovich equation lacks a closed-form solution. Moreover, the numerical approximations based on Taylor expansion above third order are fraught with computational complications. For this reason, numerical methods based on Monte Carlo methods have been resorted to. Chief among these methods are sequential Monte-Carlo methods (or particle filters), for they allow for online assimilation of data. Particle filters are not without challenges: they suffer from particle degeneracy, sample impoverishment, and computational costs arising from resampling.
The goal of this thesis is to:— i) Review the derivation of Kushner-Stratonovich equation from first principles and its extant numerical approximation methods, ii) Study the feedback particle filters as a way of avoiding resampling in particle filters, iii) Study joint state and parameter estimation in time-continuous settings, iv) Apply the notions studied to linear hyperbolic stochastic differential equations.
The interconnection between Itô integrals and stochastic partial differential equations and those of Stratonovich is introduced in anticipation of feedback particle filters. With these ideas and motivated by the variants of ensemble Kalman-Bucy filters founded on the structure of the innovation process, a feedback particle filter with randomly perturbed innovation is proposed. Moreover, feedback particle filters based on coupling of prediction and analysis measures are proposed. They register a better performance than the bootstrap particle filter at lower ensemble sizes.
We study joint state and parameter estimation, both by means of extended state spaces and by use of dual filters. Feedback particle filters seem to perform well in both cases. Finally, we apply joint state and parameter estimation in the advection and wave equation, whose velocity is spatially varying. Two methods are employed: Metropolis Hastings with filter likelihood and a dual filter comprising of Kalman-Bucy filter and ensemble Kalman-Bucy filter. The former performs better than the latter.
The concept of hydrologic connectivity summarizes all flow processes that link separate regions of a landscape. As such, it is a central theme in the field of catchment hydrology, with influence on neighboring disciplines such as ecology and geomorphology. It is widely acknowledged to be an important key in understanding the response behavior of a catchment and has at the same time inspired research on internal processes over a broad range of scales. From this process-hydrological point of view, hydrological connectivity is the conceptual framework to link local observations across space and scales.
This is the context in which the four studies this thesis comprises of were conducted. The focus was on structures and their spatial organization as important control on preferential subsurface flow. Each experiment covered a part of the conceptualized flow path from hillslopes to the stream: soil profile, hillslope, riparian zone, and stream.
For each study site, the most characteristic structures of the investigated domain and scale, such as slope deposits and peat layers were identified based on preliminary or previous investigations or literature reviews. Additionally, further structural data was collected and topographical analyses were carried out. Flow processes were observed either based on response observations (soil moisture changes or discharge patterns) or direct measurement (advective heat transport). Based on these data, the flow-relevance of the characteristic structures was evaluated, especially with regard to hillslope to stream connectivity.
Results of the four studies revealed a clear relationship between characteristic spatial structures and the hydrological behavior of the catchment. Especially the spatial distribution of structures throughout the study domain and their interconnectedness were crucial for the establishment of preferential flow paths and their relevance for large-scale processes. Plot and hillslope-scale irrigation experiments showed that the macropores of a heterogeneous, skeletal soil enabled preferential flow paths at the scale of centimeters through the otherwise unsaturated soil. These flow paths connected throughout the soil column and across the hillslope and facilitated substantial amounts of vertical and lateral flow through periglacial slope deposits.
In the riparian zone of the same headwater catchment, the connectivity between hillslopes and stream was controlled by topography and the dualism between characteristic subsurface structures and the geomorphological heterogeneity of the stream channel. At the small scale (1 m to 10 m) highest gains always occurred at steps along the longitudinal streambed profile, which also controlled discharge patterns at the large scale (100 m) during base flow conditions (number of steps per section). During medium and high flow conditions, however, the impact of topography and parafluvial flow through riparian zone structures prevailed and dominated the large-scale response patterns.
In the streambed of a lowland river, low permeability peat layers affected the connectivity between surface water and groundwater, but also between surface water and the hyporheic zone. The crucial factor was not the permeability of the streambed itself, but rather the spatial arrangement of flow-impeding peat layers, causing increased vertical flow through narrow “windows” in contrast to predominantly lateral flow in extended areas of high hydraulic conductivity sediments.
These results show that the spatial organization of structures was an important control for hydrological processes at all scales and study areas. In a final step, the observations from different scales and catchment elements were put in relation and compared. The main focus was on the theoretical analysis of the scale hierarchies of structures and processes and the direction of causal dependencies in this context. Based on the resulting hierarchical structure, a conceptual framework was developed which is capable of representing the system’s complexity while allowing for adequate simplifications.
The resulting concept of the parabolic scale series is based on the insight that flow processes in the terrestrial part of the catchment (soil and hillslopes) converge. This means that small-scale processes assemble and form large-scale processes and responses. Processes in the riparian zone and the streambed, however, are not well represented by the idea of convergence. Here, the large-scale catchment signal arrives and is modified by structures in the riparian zone, stream morphology, and the small-scale interactions between surface water and groundwater. Flow paths diverge and processes can better be represented by proceeding from large scales to smaller ones. The catchment-scale representation of processes and structures is thus the conceptual link between terrestrial hillslope processes and processes in the riparian corridor.
Potato is the 4th most important food crop in the world. Especially in tropical and sub-tropical potato production, drought is a yield limiting factor. Potato is sensitive to water stress. Potato yield loss under water stress could be reduced by using tolerant varieties and adjusted agronomic practices. Direct selection for yield under water-stressed conditions requires long selection cycles. Thus, identification of markers for marker-assisted selection may speed up breeding. The objective of this thesis is to identify morphological markers for drought tolerance by continuously monitoring plant growth and canopy temperature with an automatic phenotyping system.
The phenotyping was performed in drought-stress experiments that were conducted in population A with 64 genotypes and population B with 21 genotypes in the screenhouse in 2015 and 2016 (population A) and in 2017 and 2018 (population B). Drought tolerance was quantified as deviation of the relative tuber starch yield from the experimental median (DRYM) and parent median (DRYMp). Relative tuber starch yield is starch yield under drought stress relative to the average starch yield of the respective cultivar under control conditions in the same experiment. The specific DRYM value was calculated based on the yield data of the same experiment or the global DRYM that was calculated from yield data derived from data combined over yeas of respective population or across multiple experiments including VALDIS and TROST experiments (2011-2016).
Analysis of variance found a significant effect of genotype on DRYM indicating that the tolerance variation required for marker identification was given in both populations.
Canopy growth was monitored continuously six times a day over five to ten weeks by a laser scanner system and yielded information on leaf area, plant height and leaf angle for population A and additionally on leaf inclination and light penetration depth for population B. Canopy temperature was measured 48 times a day over six to seven weeks by infrared thermometry in population B. From the continuous IRT surface temperature data set, the canopy temperature for each plant was selected by matching the time stamp of the IRT data with laser scanner data.
Mean, maximum, range and growth rate values were calculated from continuous laser scanner measurements of respective canopy parameters. Among the canopy parameters, the maximum and mean values in long-term stress conditions showed better correlation with DRYM values calculated in the same experiment than growth rate and diurnal range values. Therefore, drought tolerance index prediction was done from maximum and mean values of canopy parameters.
The tolerance index in specific experiment condition was linearly predicted by simple regression model from different single canopy parameters under long-term stress condition in population A (2016) and population B (2017 and 2018). Among the canopy parameters maximum light penetration depth (2017), mean leaf angle (2017, 2018, and 2016), mean leaf inclination or mean canopy temperature depression (2017 and 2018), maximum plant height (2017) were selected as tolerance predictors. However, no single parameters were sufficient to predict DRYM. Therefore, several independent parameters were integrated in a multiple regression model.
In multiple regression model, specific experiment DRYM values in population A was predicted from mean leaf angle (2016). In population B, specific tolerance could be predicted from maximum light penetration depth and mean leaf inclination (2017) and mean leaf inclination (2018) or mean canopy temperature depression and mean leaf angle (2018).
In data combined over season of population A, the multiple linear regression model selected maximum plant height and mean leaf angle as tolerance predictor. In Population B, mean leaf inclination was selected as tolerance predictor. However, in population A, the variation explained by the final model was too low.
Furthermore, the average tolerances respective to parent median (2011-2018) across FGH plants or all plants (FGH and field) were predicted from maximum plant height (population A) and maximum plant height and mean leaf inclination (population B). Altogether, canopy parameters could be used as markers for drought tolerance. Therefore, water stress breeding in potato could be speed up through using leaf inclination, light penetration depth, plant height and canopy temperature depression as markers for drought tolerance, especially in long-term stress conditions.
In der molekularen Diagnostik besteht ein Bedarf an schnellen und spezifischen Testsystemen, die entweder für die Labordiagnostik oder in Point of Care-Umgebungen eingesetzt werden können. Um dieses Ziel zu erreichen, stehen die Miniaturisierung und Parallelisierung im Mittelpunkt des Forschungsinteresses. Die führende Methode im Bereich der DNA-Analytik ist derzeit die Realtime-PCR. Dieser Technologie sind hinsichtlich der Multiplexfähigkeit technologischen Hürden gesetzt, da derzeit nur eine Analyse von maximal vier Parametern parallel in einem Versuchsansatz erfolgen kann. Microarrays stellen hingegen die benötigten Voraussetzungen zur Verfügung, um als Werkzeuge für die Multiparameteranalyse in verschiedensten Anwendungsbereichen zu dienen. Ein Schwerpunkt dieser Arbeit war es, Multiplex-PCRs und diagnostische Microarrays zu entwickeln, die für analytische Fragestellungen eine schnelle und zuverlässige Multiparameteranalytik ermöglichen, um die bisherigen Einschränkungen aktueller Nachweisverfahren zu vermeiden. Als Anwendungen wurden zum einen ein Nachweissystem für acht relevante Geflügelpathogene zur Überwachung in der Geflügelzucht, zum anderen ein Nachweissystem zur Identifikation potentiell allergener Lebensmittelinhaltstoffe entwickelt. Neben der Entwicklung geeigneter PCR und Multiplex-PCR-Verfahren sowie spezifischer Microarrays für die Detektion der gesuchten Zielsequenzen stand auch die weiterführende Integration von DNA-Amplifikation und Microarray-Technologie im Fokus dieser Arbeit. Die OnChip-Amplifikation stellt eine Möglichkeit dar, um DNA-Analytik und Detektion in einem Reaktionsschritt zu integrieren. Entsprechend wurden die in der Arbeit entwickelten PCR- und Multiplex-PCR-Verfahren zum Nachweis potentieller allergener Lebensmittelinhaltsstoffe für die OnChip-Amplifikation adaptiert und Reaktionsbedingungen getestet, die eine Multiparameteranalyse auf dem Chip ermöglichen. Die entwickelten OnChip-PCR-Verfahren zeigten eine hohe Spezifität sowohl in Single- als auch in der Multiplex-OnChip-PCR. Eine Sensitivität von 10 Kopien bzw. <10ppm konnte in Single-OnChip-PCRs für den Nachweis allergener Lebensmittelinhaltsstoffe gezeigt werden. In Multiplex-OnChip-PCRs konnten 10-100ppm allergene Verunreinigungen spezifisch in unterschiedlichen Lebensmitteln nachgewiesen werden. Ein weiterer Schritt in Richtung einer möglichen Verwendung im Point of Care-Bereich stellt der Einsatz eines isothermalen Amplifikationsverfahrens dar. Vorteil eines solchen Verfahrens ist die Möglichkeit, auf das ansonsten benötigte Thermocycling zu verzichten. Dies vereinfacht eine Integration der OnChip-Amplifikation in mobile Analysegeräte oder Lab on Chip-Systeme und qualifiziert das Verfahren für den Einsatz in Point of Care-Umgebungen. In dieser Arbeit wurde eine noch junge isothermale Amplifikationsmethode, die helikase-abhängige Amplifikation (HDA), hinsichtlich ihrer Eignung für die Integration auf einem Microarray getestet. Hierfür konnte die bislang erste OnChip-HDA für Einzel- und Duplex-Nachweise von Pathogenen entwickelt werden.
Die 11beta-HSD1 reguliert intrazellulär die Cortisolkonzentration durch Regeneration von Cortison z.B. aus dem Blutkreislauf, zu Cortisol. Daher stellt diese ein wichtiges Element in der Glucocorticoid-vermittelten Genregulation dar. Die 11beta-HSD1 wird ubiquitär exprimiert, auf hohem Niveau besonders in Leber, Fettgewebe und glatten Muskelzellen. Insbesondere die Bedeutung der 11beta-HSD1 in Leber und Fettgewebe konnte mehrfach nachgewiesen werden. In der Leber führte eine erhöhte Aktivität aufgrund einer Überexpression in Mäusen zu einer verstärkten Gluconeogeneserate. Des Weiteren konnte gezeigt werden, dass eine erhöhte Expression und erhöhte Enzymaktivität der 11beta-HSD1 im subkutanen und viszeralen Fettgewebe assoziiert ist mit Fettleibigkeit, Insulinresistenz und Dyslipidämie. Über die Regulation ist jedoch noch wenig bekannt. Zur Untersuchung der Promotoraktivität wurde der Promotorbereich von -3034 bis +188, vor und nach dem Translations- und Transkriptionsstart, der 11beta-HSD1 kloniert. 8 Promotorfragmente wurden mittels Dual-Luciferase-Assay in humanen HepG2-Zellen sowie undifferenzierten und differenzierten murinen 3T3-L1-Zellen untersucht. Anschließend wurde mittels nicht-radioaktiven EMSA die Bindung des TATA-Binding Proteins (TBP) sowie von CCAAT/Enhancer-Binding-Proteinen (C/EBP) an ausgewählte Promotorregionen analysiert. Nach der Charakterisierung des Promotors wurden spezifische endogene und exogene Regulatoren untersucht. Fettsäuren modifizieren die Entstehung von Adipositas und Insulinresistenz. Ihre Wirkung wird u.a. PPARgamma-abhängig vermittelt und kann durch das Inkretin (Glucose-dependent insulinotropic Peptide) GIP modifiziert werden. So wurden die Effekte von unterschiedlichen Fettsäuren, vom PPARgamma Agonisten Rosiglitazon sowie dem Inkretin GIP auf die Expression und Enzymaktivität der 11beta-HSD1 untersucht. Dies wurde in-vitro-, tierexperimentell und in humanen in-vivo-Studien realisiert. Zuletzt wurden 2 Single Nucleotide Polymorphismen (SNP) im Promotorbereich der 11beta-HSD1 in der Zellkultur im Hinblick auf potentielle Funktionalität analysiert sowie die Assoziation mit Diabetes mellitus Typ 2 und Körpergewicht in der MeSyBePo-Kohorte bei rund 1.800 Personen untersucht. Die Luciferase-Assays zeigten basal eine zell-spezifische Regulation der 11beta-HSD1, wobei in allen 3 untersuchten Zelltypen die Bindung eines Repressors nachgewiesen werden konnte. Zudem konnte eine mögliche Bindung des TBPs sowie von C/EBP-Proteinen an verschiedene Positionen gezeigt werden. Die Transaktivierungsassays mit den C/EBP-Proteinen -alpha, -beta und -delta zeigten eben-falls eine zellspezifische Regulation des 11beta-HSD1-Promotors. Die Aktivität und Expression der 11beta-HSD1 wurde durch die hier untersuchten endogenen und exogenen Faktoren spezifisch modifiziert, was sowohl in-vitro als auch in-vivo in unterschiedlichen Modellsystemen dargestellt werden konnte. Die Charakterisierung der MeSyBePo-Kohorte ergab keine direkten Assoziationen zwischen Polymorphismus und klinischem Phänotyp, jedoch Tendenzen für eine erhöhtes Körper-gewicht und Typ 2 Diabetes mellitus in Abhängigkeit des Genotyps. Der Promotor der 11beta-HSD1 konnte aufgrund der Daten aus den Luciferaseassays sowie den Daten aus den EMSA-Analysen näher charakterisiert werden. Dieser zeigt eine variable und zell-spezifische Regulation. Ein wichtiger Regulator stellen insbesondere in den HepG2-Zellen die C/EBP-Proteine -alpha, -beta und -delta dar. Aus den in-vivo-Studien ergab sich eine Regulation der 11beta-HSD1 durch endogene, exogene und pharmakologische Substanzen, die durch die Zellkulturversuche bestätigt und näher charakterisiert werden konnten.
Carbohydrate recognition is a ubiquitous principle underlying many fundamental biological processes like fertilization, embryogenesis and viral infections. But how carbohydrate specificity and affinity induce a molecular event is not well understood. One of these examples is bacteriophage P22 that binds and infects three distinct Salmonella enterica (S.) hosts. It recognizes and depolymerizes repetitive carbohydrate structures of O antigen in its host´s outer membrane lipopolysaccharide molecule. This is mediated by tailspikes, mainly β helical appendages on phage P22 short non contractile tail apparatus (podovirus). The O antigen of all three Salmonella enterica hosts is built from tetrasaccharide repeating units consisting of an identical main chain with a distinguished 3,6 dideoxyhexose substituent that is crucial for P22 tailspike recognition: tyvelose in S. Enteritidis, abequose in S. Typhimurium and paratose in S. Paratyphi. In the first study the complexes of P22 tailspike with its host’s O antigen octasaccharide were characterized. S. Paratyphi octasaccharide binds less tightly (ΔΔG≈7 kJ/mol) to the tailspike than the other two hosts. Crystal structure analysis of P22 tailspike co crystallized with S. Paratyphi octasaccharides revealed different interactions than those observed before in tailspike complexes with S. Enteritidis and S. Typhimurium octasaccharides. These different interactions occur due to a structural rearrangement in the S. Paratyphi octasaccharide. It results in an unfavorable glycosidic bond Φ/Ψ angle combination that also had occurred when the S. Paratyphi octasaccharide conformation was analyzed in an aprotic environment. Contributions of individual protein surface contacts to binding affinity were analyzed showing that conserved structural waters mediate specific recognition of all three different Salmonella host O antigens. Although different O antigen structures possess distinct binding behavior on the tailspike surface, all are recognized and infected by phage P22. Hence, in a second study, binding measurements revealed that multivalent O antigen was able to bind with high avidity to P22 tailspike. Dissociation rates of the polymer were three times slower than for an octasaccharide fragment pointing towards high affinity for O antigen polysaccharide. Furthermore, when phage P22 was incubated with lipopolysaccharide aggregates before plating on S. Typhimurium cells, P22 infectivity became significantly reduced. Therefore, in a third study, the function of carbohydrate recognition on the infection process was characterized. It was shown that large S. Typhimurium lipopolysaccharide aggregates triggered DNA release from the phage capsid in vitro. This provides evidence that phage P22 does not use a second receptor on the Salmonella surface for infection. P22 tailspike binding and cleavage activity modulate DNA egress from the phage capsid. DNA release occurred more slowly when the phage possessed mutant tailspikes with less hydrolytic activity and was not induced if lipopolysaccharides contained tailspike shortened O antigen polymer. Furthermore, the onset of DNA release was delayed by tailspikes with reduced binding affinity. The results suggest a model for P22 infection induced by carbohydrate recognition: tailspikes position the phage on Salmonella enterica and their hydrolytic activity forces a central structural protein of the phage assembly, the plug protein, onto the host´s membrane surface. Upon membrane contact, a conformational change has to occur in the assembly to eject DNA and pilot proteins from the phage to establish infection. Earlier studies had investigated DNA ejection in vitro solely for viruses with long non contractile tails (siphovirus) recognizing protein receptors. Podovirus P22 in this work was therefore the first example for a short tailed phage with an LPS recognition organelle that can trigger DNA ejection in vitro. However, O antigen binding and cleaving tailspikes are widely distributed in the phage biosphere, for example in siphovirus 9NA. Crystal structure analysis of 9NA tailspike revealed a complete similar fold to P22 tailspike although they only share 36 % sequence identity. Moreover, 9NA tailspike possesses similar enzyme activity towards S. Typhimurium O antigen within conserved amino acids. These are responsible for a DNA ejection process from siphovirus 9NA triggered by lipopolysaccharide aggregates. 9NA expelled its DNA 30 times faster than podovirus P22 although the associated conformational change is controlled with a similar high activation barrier. The difference in DNA ejection velocity mirrors different tail morphologies and their efficiency to translate a carbohydrate recognition signal into action.
Fusionen stellen einen zentralen Baustein der Industrieökonomik dar. In diesem Buch wird der Frage nachgegangen, welchen Einfluss die räumliche Dimension auf eine Fusion ausübt. Dabei wird ein Grundmodell entwickelt und über dieses hinaus eine Vielzahl Erweiterungen präsentiert. Der Leser erhält somit die Möglichkeit ein tiefes Verständnis für Fusionen bei räumlichem Wettbewerb zu erlangen.
Non-mycorrhizal fungal endophytes are able to colonize internally roots without causing visible disease symptoms establishing neutral or mutualistic associations with plants. These fungi known as non-clavicipitaceous endophytes have a broad host range of monocot and eudicot plants and are highly diverse. Some of them promote plant growth and confer increased abiotic-stress tolerance and disease resistance. According to such possible effects on host plants, it was aimed to isolate and to characterize native fungal root endophytes from tomato (Lycopersicon esculentum Mill.) and to analyze their effects on plant development, plant resistance and fruit yield and quality together with the model endophyte Piriformospora indica. Fifty one new fungal strains were isolated from desinfected tomato roots of four different crop sites in Colombia. These isolates were roughly characterized and fourteen potential endophytes were further analyzed concerning their taxonomy, their root colonization capacity and their impact on plant growth. Sequencing of the ITS region from the ribosomal RNA gene cluster and in-depth morphological characterisation revealed that they correspond to different phylogenetic groups among the phylum Ascomycota. Nine different morphotypes were described including six dark septate endophytes (DSE) that did not correspond to the Phialocephala group. Detailed confocal microscopy analysis showed various colonization patterns of the endophytes inside the roots ranging from epidermal penetration to hyphal growth through the cortex. Tomato pot experiments under glass house conditions showed that they differentially affect plant growth depending on colonization time and inoculum concentration. Three new isolates (two unknown fungal endophyte DSE48, DSE49 and one identified as Leptodontidium orchidicola) with neutral or positiv effects were selected and tested in several experiments for their influence on vegetative growth, fruit yield and quality and their ability to diminish the impact of the pathogen Verticillium dahliae on tomato plants. Although plant growth promotion by all three fungi was observed in young plants, vegetative growth parameters were not affected after 22 weeks of cultivation except a reproducible increase of root diameter by the endophyte DSE49. Additionally, L. orchidicola increased biomass and glucose content of tomato fruits, but only at an early date of harvest and at a certain level of root colonization. Concerning bioprotective effects, the endophytes DSE49 and L. orchidicola decreased significantly disease symptoms caused by the pathogen V. dahliae, but only at a low dosis of the pathogen. In order to analyze, if the model root endophytic fungus Piriformospora indica could be suitable for application in production systems, its impact on tomato was evaluated. Similarly to the new fungal isolates, significant differences for vegetative growth parameters were only observable in young plants and, but protection against V. dahliae could be seen in one experiment also at high dosage of the pathogen. As the DSE L. orchidicola, P. indica increased the number and biomass of marketable tomatoes only at the beginning of fruit setting, but this did not lead to a significant higher total yield. If the effects on growth are due to a better nutrition of the plant with mineral element was analyzed in barley in comparison to the arbuscular mycorrhizal fungus Glomus mosseae. While the mycorrhizal fungus increased nitrogen and phosphate uptake of the plant, no such effect was observed for P. indica. In summary this work shows that many different fungal endophytes can be also isolated from roots of crops and, that these isolates can have positive effects on early plant development. This does, however, not lead to an increase in total yield or in improvement of fruit quality of tomatoes under greenhouse conditions.
A systems biological approach towards the molecular basis of heterosis in Arabidopsis thaliana
(2011)
Heterosis is defined as the superiority in performance of heterozygous genotypes compared to their corresponding genetically different homozygous parents. This phenomenon is already known since the beginning of the last century and it has been widely used in plant breeding, but the underlying genetic and molecular mechanisms are not well understood. In this work, a systems biological approach based on molecular network structures is proposed to contribute to the understanding of heterosis. Hybrids are likely to contain additional regulatory possibilities compared to their homozygous parents and, therefore, they may be able to correctly respond to a higher number of environmental challenges, which leads to a higher adaptability and, thus, the heterosis phenomenon. In the network hypothesis for heterosis, presented in this work, more regulatory interactions are expected in the molecular networks of the hybrids compared to the homozygous parents. Partial correlations were used to assess this difference in the global interaction structure of regulatory networks between the hybrids and the homozygous genotypes. This network hypothesis for heterosis was tested on metabolite profiles as well as gene expression data of the two parental Arabidopsis thaliana accessions C24 and Col-0 and their reciprocal crosses. These plants are known to show a heterosis effect in their biomass phenotype. The hypothesis was confirmed for mid-parent and best-parent heterosis for either hybrid of our experimental metabolite as well as gene expression data. It was shown that this result is influenced by the used cutoffs during the analyses. Too strict filtering resulted in sets of metabolites and genes for which the network hypothesis for heterosis does not hold true for either hybrid regarding mid-parent as well as best-parent heterosis. In an over-representation analysis, the genes that show the largest heterosis effects according to our network hypothesis were compared to genes of heterotic quantitative trait loci (QTL) regions. Separately for either hybrid regarding mid-parent as well as best-parent heterosis, a significantly larger overlap between the resulting gene lists of the two different approaches towards biomass heterosis was detected than expected by chance. This suggests that each heterotic QTL region contains many genes influencing biomass heterosis in the early development of Arabidopsis thaliana. Furthermore, this integrative analysis led to a confinement and an increased confidence in the group of candidate genes for biomass heterosis in Arabidopsis thaliana identified by both approaches.
With the downscaling of CMOS technologies, the radiation-induced Single Event Transient (SET) effects in combinational logic have become a critical reliability issue for modern integrated circuits (ICs) intended for operation under harsh radiation conditions. The SET pulses generated in combinational logic may propagate through the circuit and eventually result in soft errors. It has thus become an imperative to address the SET effects in the early phases of the radiation-hard IC design. In general, the soft error mitigation solutions should accommodate both static and dynamic measures to ensure the optimal utilization of available resources. An efficient soft-error-aware design should address synergistically three main aspects: (i) characterization and modeling of soft errors, (ii) multi-level soft error mitigation, and (iii) online soft error monitoring. Although significant results have been achieved, the effectiveness of SET characterization methods, accuracy of predictive SET models, and efficiency of SET mitigation measures are still critical issues. Therefore, this work addresses the following topics: (i) Characterization and modeling of SET effects in standard combinational cells, (ii) Static mitigation of SET effects in standard combinational cells, and (iii) Online particle detection, as a support for dynamic soft error mitigation.
Since the standard digital libraries are widely used in the design of radiation-hard ICs, the characterization of SET effects in standard cells and the availability of accurate SET models for the Soft Error Rate (SER) evaluation are the main prerequisites for efficient radiation-hard design. This work introduces an approach for the SPICE-based standard cell characterization with the reduced number of simulations, improved SET models and optimized SET sensitivity database. It has been shown that the inherent similarities in the SET response of logic cells for different input levels can be utilized to reduce the number of required simulations. Based on characterization results, the fitting models for the SET sensitivity metrics (critical charge, generated SET pulse width and propagated SET pulse width) have been developed. The proposed models are based on the principle of superposition, and they express explicitly the dependence of the SET sensitivity of individual combinational cells on design, operating and irradiation parameters. In contrast to the state-of-the-art characterization methodologies which employ extensive look-up tables (LUTs) for storing the simulation results, this work proposes the use of LUTs for storing the fitting coefficients of the SET sensitivity models derived from the characterization results. In that way the amount of characterization data in the SET sensitivity database is reduced significantly.
The initial step in enhancing the robustness of combinational logic is the application of gate-level mitigation techniques. As a result, significant improvement of the overall SER can be achieved with minimum area, delay and power overheads. For the SET mitigation in standard cells, it is essential to employ the techniques that do not require modifying the cell structure. This work introduces the use of decoupling cells for improving the robustness of standard combinational cells. By insertion of two decoupling cells at the output of a target cell, the critical charge of the cell’s output node is increased and the attenuation of short SETs is enhanced. In comparison to the most common gate-level techniques (gate upsizing and gate duplication), the proposed approach provides better SET filtering. However, as there is no single gate-level mitigation technique with optimal performance, a combination of multiple techniques is required. This work introduces a comprehensive characterization of gate-level mitigation techniques aimed to quantify their impact on the SET robustness improvement, as well as introduced area, delay and power overhead per gate. By characterizing the gate-level mitigation techniques together with the standard cells, the required effort in subsequent SER analysis of a target design can be reduced. The characterization database of the hardened standard cells can be utilized as a guideline for selection of the most appropriate mitigation solution for a given design.
As a support for dynamic soft error mitigation techniques, it is important to enable the online detection of energetic particles causing the soft errors. This allows activating the power-greedy fault-tolerant configurations based on N-modular redundancy only at the high radiation levels. To enable such a functionality, it is necessary to monitor both the particle flux and the variation of particle LET, as these two parameters contribute significantly to the system SER. In this work, a particle detection approach based on custom-sized pulse stretching inverters is proposed. Employing the pulse stretching inverters connected in parallel enables to measure the particle flux in terms of the number of detected SETs, while the particle LET variations can be estimated from the distribution of SET pulse widths. This approach requires a purely digital processing logic, in contrast to the standard detectors which require complex mixed-signal processing. Besides the possibility of LET monitoring, additional advantages of the proposed particle detector are low detection latency and power consumption, and immunity to error accumulation.
The results achieved in this thesis can serve as a basis for establishment of an overall soft-error-aware database for a given digital library, and a comprehensive multi-level radiation-hard design flow that can be implemented with the standard IC design tools. The following step will be to evaluate the achieved results with the irradiation experiments.
Adsorption layers of soluble surfactants enable and govern a variety of phenomena in surface and colloidal sciences, such as foams. The ability of a surfactant solution to form wet foam lamellae is governed by the surface dilatational rheology. Only systems having a non-vanishing imaginary part in their surface dilatational modulus, E, are able to form wet foams. The aim of this thesis is to illuminate the dissipative processes that give rise to the imaginary part of the modulus. There are two controversial models discussed in the literature. The reorientation model assumes that the surfactants adsorb in two distinct states, differing in their orientation. This model is able to describe the frequency dependence of the modulus E. However, it assumes reorientation dynamics in the millisecond time regime. In order to assess this model, we designed a SHG pump-probe experiment that addresses the orientation dynamics. Results obtained reveal that the orientation dynamics occur in the picosecond time regime, being in strong contradiction with the two states model. The second model regards the interface as an interphase. The adsorption layer consists of a topmost monolayer and an adjacent sublayer. The dissipative process is due to the molecular exchange between both layers. The assessment of this model required the design of an experiment that discriminates between the surface compositional term and the sublayer contribution. Such an experiment has been successfully designed and results on elastic and viscoelastic surfactant provided evidence for the correctness of the model. Because of its inherent surface specificity, surface SHG is a powerful analytical tool that can be used to gain information on molecular dynamics and reorganization of soluble surfactants. They are central elements of both experiments. However, they impose several structural elements of the model system. During the course of this thesis, a proper model system has been identified and characterized. The combination of several linear and nonlinear optical techniques, allowed for a detailed picture of the interfacial architecture of these surfactants.
Galaxies are among the most complex systems that can currently be modelled with a computer. A realistic simulation must take into account cosmology and gravitation as well as effects of plasma, nuclear, and particle physics that occur on very different time, length, and energy scales. The Milky Way is the ideal test bench for such simulations, because we can observe millions of its individual stars whose kinematics and chemical composition are records of the evolution of our Galaxy. Thanks to the advent of multi-object spectroscopic surveys, we can systematically study stellar populations in a much larger volume of the Milky Way. While the wealth of new data will certainly revolutionise our picture of the formation and evolution of our Galaxy and galaxies in general, the big-data era of Galactic astronomy also confronts us with new observational, theoretical, and computational challenges.
This thesis aims at finding new observational constraints to test Milky-Way models, primarily based on infra-red spectroscopy from the Apache Point Observatory Galactic Evolution Experiment (APOGEE) and asteroseismic data from the CoRoT mission. We compare our findings with chemical-evolution models and more sophisticated chemodynamical simulations. In particular we use the new powerful technique of combining asteroseismic and spectroscopic observations that allows us to test the time dimension of such models for the first time. With CoRoT and APOGEE (CoRoGEE) we can infer much more precise ages for distant field red-giant stars, opening up a new window for Galactic archaeology.
Another important aspect of this work is the forward-simulation approach that we pursued when interpreting these complex datasets and comparing them to chemodynamical models.
The first part of the thesis contains the first chemodynamical study conducted with the APOGEE survey. Our sample comprises more than 20,000 red-giant stars located within 6 kpc from the Sun, and thus greatly enlarges the Galactic volume covered with high-resolution spectroscopic observations. Because APOGEE is much less affected by interstellar dust extinction, the sample covers the disc regions very close to the Galactic plane that are typically avoided by optical surveys. This allows us to investigate the chemo-kinematic properties of the Milky Way's thin disc outside the solar vicinity. We measure, for the first time with high-resolution data, the radial metallicity gradient of the disc as a function of distance from the Galactic plane, demonstrating that the gradient flattens and even changes its sign for mid-plane distances greater than 1 kpc.
Furthermore, we detect a gap between the high- and low-[$\alpha$/Fe] sequences in the chemical-abundance diagram (associated with the thin and thick disc) that unlike in previous surveys can hardly be explained by selection effects. Using 6D kinematic information, we also present chemical-abundance diagrams cleaned from stars on kinematically hot orbits. The data allow us to confirm without doubt that the scale length of the (chemically-defined) thick disc is significantly shorter than that of the thin disc.
In the second part, we present our results of the first combination of asteroseismic and spectroscopic data in the context of Galactic Archaeology. We analyse APOGEE follow-up observations of 606 solar-like oscillating red giants in two CoRoT fields close to the Galactic plane. These stars cover a large radial range of the Galactic disc (4.5 kpc $\lesssim R_{\rm Gal}\lesssim15$ kpc) and a large age baseline (0.5 Gyr $\lesssim \tau\lesssim$ 13 Gyr), allowing us to study the age- and radius-dependence of the [$\alpha$/Fe] vs. [Fe/H] distributions. We find that the age distribution of the high-[$\alpha$/Fe] sequence appears to be broader than expected from a monolithically-formed old thick disc that stopped to form stars 10 Gyr ago. In particular, we discover a significant population of apparently young, [$\alpha$/Fe]-rich stars in the CoRoGEE data whose existence cannot be explained by standard chemical-evolution models. These peculiar stars are much more abundant in the inner CoRoT field LRc01 than in the outer-disc field LRc01, suggesting that at least part of this population has a chemical-evolution rather than a stellar-evolution origin, possibly due to a peculiar chemical-enrichment history of the inner disc. We also find that strong radial migration is needed to explain the abundance of super-metal-rich stars in the outer disc.
Finally, we use the CoRoGEE sample to study the time evolution of the radial metallicity gradient in the thin disc, an observable that has been the subject of observational and theoretical debate for more than 20 years. By dividing the CoRoGEE dataset into six age bins, performing a careful statistical analysis of the radial [Fe/H], [O/H], and [Mg/Fe] distributions, and accounting for the biases introduced by the observation strategy, we obtain reliable gradient measurements. The slope of the radial [Fe/H] gradient of the young red-giant population ($-0.058\pm0.008$ [stat.] $\pm0.003$ [syst.] dex/kpc) is consistent with recent Cepheid data. For the age range of $1-4$ Gyr, the gradient steepens slightly ($-0.066\pm0.007\pm0.002$ dex/kpc), before flattening again to reach a value of $\sim-0.03$ dex/kpc for stars with ages between 6 and 10 Gyr. This age dependence of the [Fe/H] gradient can be explained by a nearly constant negative [Fe/H] gradient of $\sim-0.07$ dex/kpc in the interstellar medium over the past 10 Gyr, together with stellar heating and migration. Radial migration also offers a new explanation for the puzzling observation that intermediate-age open clusters in the solar vicinity (unlike field stars) tend to have higher metallicities than their younger counterparts. We suggest that non-migrating clusters are more likely to be kinematically disrupted, which creates a bias towards high-metallicity migrators from the inner disc and may even steepen the intermediate-age cluster abundance gradient.
Vor dem Hintergrund der Auffassung, dass ethnische Minderheiten eine Form so-zialer Organisation darstellen, verfolgt die Studie – unter Berücksichtigung der Mehr-deutigkeit des Raumbegriffs – das Ziel, anhand von Beispielen aus Rumänien ein Konzept zu entwickeln, mit dem sich die aktuelle Beziehung von Ethnizität und Raum im Transformationsprozess adäquat analysieren und beschreiben lässt.
Die vorliegende Arbeit untersucht Urlaubsfotografien bei Facebook und beschreibt, welche sozio-technischen Medienpraktiken sich innerhalb der Social-Media Plattform über die Fotografien vollziehen. Fotografische Praktiken sind durch aktive Handlungen und soziale Gebrauchsweisen bestimmt. Urlaubsfotografien tragen zum Beispiel zur Strukturierung von Reiserouten und Vorstellungen bei, indem genrespezifische Motive und Rahmungen mit Hilfe von Medien reproduziert und wiederholt werden. Praktiken des Zeigens, Teilens und Kommunizierens werden durch Social Plug-Ins (Like/Share Buttons) und Tagging-Funktionen auch in die Benutzeroberflächen von Facebook integriert. Dadurch werden Nutzer*innen Aktivitäten und technische Prozesse miteinander verbunden. Am Beispiel der automatischen Generierung von Urlaubsfotografien auf Geotagseiten wird gezeigt, dass Social-Tagging zur Entstehung und Aushandlung geographischer Räume und Ortsvorstellungen beiträgt. Mithilfe technischer Strukturierungen von Fotografien auf Taggingseiten werden genrespezifische Motive, fotografische Trends und Ästhetiken besonders sichtbar. Allerdings wird ihre Visualisierung auch durch algorithmische Priorisierung einzelner Inhalte mitbestimmt. Dadurch werden Urlaubsfotografien für ein fotografisches Profiling genutzt, da sie das algorithmische Erfassen und Auswerten von Nutzer*innen-Informationen ermöglichen. Die Arbeit zeigt, dass der Einsatz von Bilderkennungsverfahren und fotografischen Datenanalysen zu einer optimierten Informationsgewinnung und zu einer Standardisierung von Fotografien beiträgt.
This text is a contribution to the research on the worldwide success of evangelical Christianity and offers a new perspective on the relationship between late modern capitalism and evangelicalism. For this purpose, the utilization of affect and emotion in evangelicalism towards the mobilization of its members will be examined in order to find out what similarities to their employment in late modern capitalism can be found. Different examples from within the evangelical spectrum will be analyzed as affective economies in order to elaborate how affective mobilization is crucial for evangelicalism’s worldwide success. Pivotal point of this text is the exploration of how evangelicalism is able to activate the voluntary commitment of its members, financiers, and missionaries. Gathered here are examples where both spheres—evangelicalism and late modern capitalism—overlap and reciprocate, followed by a theoretical exploration of how the findings presented support a view of evangelicalism as an inner-worldly narcissism that contributes to an assumed re-enchantment of the world.
The study of outcrop modeling is located at the interface between two fields of expertise, Sedimentology and Computing Geoscience, which respectively investigates and simulates geological heterogeneity observed in the sedimentary record. During the last past years, modeling tools and techniques were constantly improved. In parallel, the study of Phanerozoic carbonate deposits emphasized the common occurrence of a random facies distribution along single depositional domain. Although both fields of expertise are intrinsically linked during outcrop simulation, their respective advances have not been combined in literature to enhance carbonate modeling studies. The present study re-examines the modeling strategy adapted to the simulation of shallow-water carbonate systems, based on a close relationship between field sedimentology and modeling capabilities. In the present study, the evaluation of three commonly used algorithms Truncated Gaussian Simulation (TGSim), Sequential Indicator Simulation (SISim), and Indicator Kriging (IK), were performed for the first time using visual and quantitative comparisons on an ideally suited carbonate outcrop. The results show that the heterogeneity of carbonate rocks cannot be fully simulated using one single algorithm. The operating mode of each algorithm involves capabilities as well as drawbacks that are not capable to match all field observations carried out across the modeling area. Two end members in the spectrum of carbonate depositional settings, a low-angle Jurassic ramp (High Atlas, Morocco) and a Triassic isolated platform (Dolomites, Italy), were investigated to obtain a complete overview of the geological heterogeneity in shallow-water carbonate systems. Field sedimentology and statistical analysis performed on the type, morphology, distribution, and association of carbonate bodies and combined with palaeodepositional reconstructions, emphasize similar results. At the basin scale (x 1 km), facies association, composed of facies recording similar depositional conditions, displays linear and ordered transitions between depositional domains. Contrarily, at the bedding scale (x 0.1 km), individual lithofacies type shows a mosaic-like distribution consisting of an arrangement of spatially independent lithofacies bodies along the depositional profile. The increase of spatial disorder from the basin to bedding scale results from the influence of autocyclic factors on the transport and deposition of carbonate sediments. Scale-dependent types of carbonate heterogeneity are linked with the evaluation of algorithms in order to establish a modeling strategy that considers both the sedimentary characteristics of the outcrop and the modeling capabilities. A surface-based modeling approach was used to model depositional sequences. Facies associations were populated using TGSim to preserve ordered trends between depositional domains. At the lithofacies scale, a fully stochastic approach with SISim was applied to simulate a mosaic-like lithofacies distribution. This new workflow is designed to improve the simulation of carbonate rocks, based on the modeling of each scale of heterogeneity individually. Contrarily to simulation methods applied in literature, the present study considers that the use of one single simulation technique is unlikely to correctly model the natural patterns and variability of carbonate rocks. The implementation of different techniques customized for each level of the stratigraphic hierarchy provides the essential computing flexibility to model carbonate systems. Closer feedback between advances carried out in the field of Sedimentology and Computing Geoscience should be promoted during future outcrop simulations for the enhancement of 3-D geological models.
In the era of social networks, internet of things and location-based services, many online services produce a huge amount of data that have valuable objective information, such as geographic coordinates and date time. These characteristics (parameters) in the combination with a textual parameter bring the challenge for the discovery of geospatiotemporal knowledge. This challenge requires efficient methods for clustering and pattern mining in spatial, temporal and textual spaces.
In this thesis, we address the challenge of providing methods and frameworks for geospatiotemporal data analytics. As an initial step, we address the challenges of geospatial data processing: data gathering, normalization, geolocation, and storage. That initial step is the basement to tackle the next challenge -- geospatial clustering challenge. The first step of this challenge is to design the method for online clustering of georeferenced data. This algorithm can be used as a server-side clustering algorithm for online maps that visualize massive georeferenced data. As the second step, we develop the extension of this method that considers, additionally, the temporal aspect of data. For that, we propose the density and intensity-based geospatiotemporal clustering algorithm with fixed distance and time radius.
Each version of the clustering algorithm has its own use case that we show in the thesis.
In the next chapter of the thesis, we look at the spatiotemporal analytics from the perspective of the sequential rule mining challenge. We design and implement the framework that transfers data into textual geospatiotemporal data - data that contain geographic coordinates, time and textual parameters. By this way, we address the challenge of applying pattern/rule mining algorithms in geospatiotemporal space. As the applicable use case study, we propose spatiotemporal crime analytics -- discovery spatiotemporal patterns of crimes in publicly available crime data.
The second part of the thesis, we dedicate to the application part and use case studies. We design and implement the application that uses the proposed clustering algorithms to discover knowledge in data. Jointly with the application, we propose the use case studies for analysis of georeferenced data in terms of situational and public safety awareness.
The Indian summer monsoon (ISM) is one of the largest climate systems on earth and impacts the livelihood of nearly 40% of the world’s population. Despite dedicated efforts, a comprehensive picture of monsoon variability has proved elusive largely due to the absence of long term high resolution records, spatial inhomogeneity of the monsoon precipitation, and the complex forcing mechanisms (solar insolation, internal teleconnections for e.g., El Niño-Southern Oscillation, tropical-midlatitude interactions). My work aims to improve the understanding of monsoon variability through generation of long term high resolution palaeoclimate data from climatically sensitive regions in the ISM and westerlies domain. To achieve this aim I have (i) identified proxies (sedimentological, geochemical, isotopic, and mineralogical) that are sensitive to environmental changes; (ii) used the identified proxies to generate long term palaeoclimate data from two climatically sensitive regions, one in NW Himalayas (transitional westerlies and ISM domain in the Spiti valley and one in the core monsoon zone (Lonar lake) in central India); (iii) undertaken a regional overview to generate “snapshots” of selected time slices; and (iv) interpreted the spatial precipitation anomalies in terms of those caused by modern teleconnections. This approach must be considered only as the first step towards identifying the past teleconnections as the boundary conditions in the past were significantly different from today and would have impacted the precipitation anomalies. As the Spiti valley is located in the in the active tectonic orogen of Himalayas, it was essential to understand the role of regional tectonics to make valid interpretations of catchment erosion and detrital influx into the lake. My approach of using integrated structural/morphometric and geomorphic signatures provided clear evidence for active tectonics in this area and demonstrated the suitability of these lacustrine sediments as palaleoseismic archives. The investigations on the lacustrine outcrops in Spiti valley also provided information on changes in seasonality of precipitation and occurrence of frequent and intense periods (ca. 6.8-6.1 cal ka BP) of detrital influx indicating extreme hydrological events in the past. Regional comparison for this time slice indicates a possible extended “break-monsoon like” mode for the monsoon that favors enhanced precipitation over the Tibetan plateau, Himalayas and their foothills. My studies on surface sediments from Lonar lake helped to identify environmentally sensitive proxies which could also be used to interpret palaeodata obtained from a ca. 10m long core raised from the lake in 2008. The core encompasses the entire Holocene and is the first well dated (by 14C) archive from the core monsoon zone of central India. My identification of authigenic evaporite gaylussite crystals within the core sediments provided evidence of exceptionally drier conditions during 4.7-3.9 and 2.0-0.5 cal ka BP. Additionally, isotopic investigations on these crystals provided information on eutrophication, stratification, and carbon cycling processes in the lake.
In this thesis, I examine different A-bar movement dependencies in Igbo, a Benue-Congo language spoken in southern Nigeria. Movement dependencies are found in constructions where an element is moved to the left edge of the clause to express information-structural categories such as in questions, relativization and focus. I show that these constructions in Igbo are very uniform from a syntactic point of view. The constructions are built on two basic fronting operations: relativization and focus movement, and are biclausal. I further investigate several morphophonological effects that are found in these A-bar constructions. I propose that these effects are reflexes of movement that are triggered when an element is moved overtly in relativization or focus. This proposal helps to explain the tone patterns that have previously been assumed to be a property of relative clauses. The thesis adds to the growing body of tonal reflexes of A-bar movement reported for a few African languages. The thesis also provides an insight into the complementizer domain (C-domain) of Igbo.
תקציר
מצוות הפריון הינה אחת מן המצוות החשובות ביהדות ומגדירה במובנים רבים את מהות קיומו של האדם היהודי הדתי. זוגות דתיים אשר סובלים מבעיית פריון נקרעים לא פעם בין מחוייבותם הדתית והלחץ החברתי בקהילתם לבין אי יכולתם להביא ילדים לעולם בדרך טבעית. החל מאמצע המאה ה 20- הפכו טכנולוגיות פריון רפואיות לנגישות לציבור הרחב בישראל ובעולם והובילו למהפכה חברתית אשר אפשרה לזוגות חשוכי ילדים להגשים את חלומם בפעם הראשונה ולהפוך להורים. פריצת דרך רפואית זו לא נעלמה מעיני הציבור הדתי על זרמיו השונים וגרמה לטלטלה בתפיסת עולמם של מנהיגיהם, אשר נדרשו לתת מענה הלכתי הולם המאזן בין רווחת קהילותיהם לבין שמירה על ערכי ומצוות הדת היהודית. על רקע תמורות אלו התפתח שיח הלכתי ואקדמי חשוב ומעניין באשר למקומה של טכנולוגיה מודרנית בחברה המתנהלת על פי קודים מסורתיים. עם זאת, הדיאלוג החי המתקיים בין מנהיגי היהדות לבין קהילותיהם, אשר מתועד כאוסף שאלות ותשובות (שו"ת) לבעיות הלכתיות אקטואליות בתחום הפריון, לא נחקר דיו.
עבודתנו עוסקת במחקר ספרות השו"ת ובגישת פוסקי ההלכה להסתייעות בטכנולוגיית ההזרעה המלאכותית ובטיפולי פוריות חדשניים נוספים שהתפתחו בעקבותיה כגון הפריה חוץ גופית, פונדקאות ותרומת ביציות. העבודה סוקרת את התגבשות ועיצוב ההלכה בשאלה זו, כפי שעולה מספרות השו"ת החל מתקופת הראשונים (המאות ה 11- עד ה- 16 ) ועד לפוסקים מתקופת האחרונים (המאה ה- 16 ואילך), ומתמקדת בעיקר בתקופה המודרנית של המאה האחרונה. במרכז העבודה יעמדו מעמדם ההלכתי של האם והוולד בעקבות שימוש בהזרעה והפריה מלאכותית וכן השלכותיהן ההלכתיות של השימוש הרפואי בזרע.
תרומתו של מחקר זה הינה בהצגת וניתוח התמודדות הפוסקים עם העימות הערכי וההלכתי שמעוררות תמורות במבנה המשפחה ובדפוסי הורות מסורתיים כתוצאה משימוש הולך וגובר בטכנולוגיות פריון מתקדמות בחברה המודרנית. יתר על כן, מחקר זה מרחיב את הדיון ההלכתי אל מעבר לעמדות הפוסקים ביהדות האורתודוקסית, הנצמדים לעקרונות ההלכה ההיסטורית, ומציג לראשונה אף את קשת הדעות של רבנים המשתייכים לזרמי היהדות המתקדמת והקונסרבטיבית, הדוגלים בפיתוח ההלכה והתאמתה למציאות החיים המשתנה. כך, מעניקה עבודת מחקר זו תמונה שלמה ומקיפה יותר באשר להתמודדות הרבנים עם שאלת ההזרעה המלאכותית ומציגה את רב גוניותה של ההלכה כפי שמשתקפת בזרמי היהדות השונים בישראל ובתפוצות.
העבודה מחולקת לשישה חלקים אשר יפורטו בקצרה להלן.
חלק ראשון - מבוא לשאלת ההזרעה המלאכותית בספרות השו"ת
חלק זה מהווה מבוא והקדמה תיאורטית ומחקרית לשאלת ההזרעה המלאכותית ומטרתו לצייד את הקורא ברקע ההיסטורי ובכלים המחקריים הדרושים להמשך העבודה. הפרק הראשון סוקר מצוות דתיות והשקפות תרבותיות בנוגע לילודה בחברה היהודית ואילו הפרק השני מניח יסודות מתודולוגיים והיסטוריים הנחוצים לחקר שאלת ההזרעה המלאכותית בספרות השו"ת.
פרק ראשון - מצוות דתיות והשקפות תרבותיות בנוגע לילודה בחברה היהודית
פרק זה מציג את המשנה האידיאולוגית העומדת בבסיס ההצדקה ההלכתית להתרתם של טיפולי הפוריות. הפרק דן בחשיבות מצוות הפריון כפי שעולה ממקורות הלכתיים קדומים וברקע ההיסטורי והתרבותי למרכזיותה של מצווה זו ומצוות נלוות לה בדת היהודית. הפרק מדגים כיצד עיצבה חשיבות המצווה את דפוס המשפחה היהודית לאורך ההיסטוריה ועד לימינו ומסתיים בדיון קצר בשאלות רפואיות מוסריות העולות מהנגשת טכנולוגיות פריון מתקדמות במדינת ישראל המודרנית.
פרק שני - יסודות מתודולוגיים והיסטוריים בחקר שאלת ההזרעה המלאכותית בספרות השו"ת
בפרק זה מוצגים תחילה מטרות ושיטות המחקר אשר נבחרו לשם ניתוח הפסיקה בשאלת ההזרעה המלאכותית. מכיוון שהעבודה עוסקת בשאלה רפואית חדשנית והשפעתה על העולם הדתי, יערך מחקר זה תוך שימוש בניתוח רב מימדי המשלב מספר שיטות מחקר ובראשן השיטה הדוגמטית-היסטורית, כמו גם בניתוח ביקורתי של שיקולי המדיניות העומדים בבסיס שיקולי הפוסקים לפי אסוכלת הריאליזים ההלכתי. לאחר מכן נסקרים ונידונים המקורות ההיסטוריים העיקריים אשר עוסקים בהתעברות על טבעית באמבט או באמצעות שכיבה על סדינים והעומדים בבסיס הכרעות הפוסקים בהשלכות הזרעה מלאכותית על מעמדם ההלכתי של האישה והילוד.
חלק שני- ספרות השו"ת האורתודוקסית בשאלת הזרעה מלאכותית מן הבעל
חלקו שני של המחקר עוסק בניתוח ספרות השו"ת האורתודוקסית בשאלת הזרעה מלאכותית מן הבעל ובוחן את התפתחותו הרעיונית של איסור השחתת זרע ואת עמדות הפוסקים בשאלת הזרעה מלאכותית מן הבעל כפי שנידונה בספרות השו"ת.
פרק ראשון - התפתחותו הרעיונית של איסור השחתת זרע
בפרק זה נסקרים מקורותיו ההיסטוריים של האיסור להשחתת זרע. איסור זה נושק לכל תחומי חייו של הזוג הדתי ובעיקר לתחום המיניות והפריון ובעל השפעה מהותית על מגבלות הצניעות שהוחלו בעקבותיו על המיניות הגברית. קיים ויכוח בין החוקרים האם נובע האיסור מן המקורות העתיקים כגון התלמוד או לחילופין התעצם בעקבות החמרות הרבנים. מחקרינו מציע כי האפשרות השניה היא הסבירה יותר. חכמי התלמוד מפגינים גישה מקלה כלפי האיסור אך מביעים סלידה מהוצאת זרע לבטלה מתוך חשיבה חסידית או אמונה כי עיסוק בעינוג מיני עצמי עלול להסיט את האדם מקיום מצוות הפריון. לעומת זאת, בספרות הקבלה ובמיוחד בזוהר ניכרת החמרה במימדי האיסור החודרת מאוחר יותר אל עולם ההלכה.
פרק שני - דיון בהזרעה מן הבעל בספרות השו"ת
הפרק דן בפסיקותיהם של רבנים בולטים בזרם האורתודוקסי בשאלת ההזרעה מן הבעל. בספרות השו"ת האורתודוקסית ניכרת השפעתו של איסור הוצאת זרע לבטלה על שיקולי הפוסקים באם להתיר את הטיפול בהזרעה מלאכותית מן הבעל. פוסקים מקלים כגון הרבנים פיינשטיין, נבנצל ויוסף מייחסים משקל רב יותר לחשיבות מצוות הפריון ומצמצמים בשל כך את תחולת האיסור. לעומתם, פוסקים מחמירים ובראשם הרבנים טננבוים, קוק, עוזיאל, הדאיה ולדנברג מתנגדים לטיפולי פוריות מחשש השחתת זרע ובשל השלכותיה הרוחניות של העבירה על האיסור. שאלה מהותית נוספת בשיח ההלכתי בה נחלקו הרבנים הינה באשר לאפשרות קיומה של מצוות הפריה והרביה באמצעות הריון שהושג בסיוע רפואי. פוסקים מדור האחרונים, כגון הרבנים טננבוים, סגל ואזולאי (החיד"א), ובעקבותיהם פוסקים בולטים במאה ה- 20 וה- 21 כמו הרבנים עוזיאל, הדאיה, ולדנברג וקניבסקי סברו כי ניתן לקיים את המצווה באופן טבעי בלבד. לעומת זאת, הרבנים נבנצל, יוסף, וינברג ואוירבך ייחסו חשיבות רבה יותר לכוונת העושה ולתוצאה המיוחלת של ההריון אשר מגשימה לדעתם את הרציונל העומד בבסיס מצוות הפרייה הרבייה ובמצוות ישוב העולם.
שאלה נוספת המתעוררת בעניין הזרעה מן הבעל ונידונה בפרק זה עוסקת בבעיית העקרות ההלכתית. התעקשות הרבנים לשמור על הלכות הנידה במתכונתן המסורתית חושפת נשים דתיות לאי ודאות באשר לטהרתן ומכפיפה את חיי המין והפריון של משפחות שלמות למרות הסמכות הרבנית.
חלק שלישי- ספרות השו"ת האורתודוקסית בשאלת הזרעה מלאכותית מתורם
חלקו השלישי של המחקר עוסק בדיון ההלכתי האורתודוקסי בשאלת ההזרעה המלאכותית מתורם יהודי או נוכרי לאישה נשואה. מרבית הפוסקים הסתייגו מתרומת זרע לאישה נשואה מתורם יהודי כמו גם מנוכרי משיקולים הלכתיים ואידיאולוגיים.
פרק ראשון - שאלת ההזרעה המלאכותית מתורם יהודי
תרומת זרע מתורם יהודי זר מעלה חששות הלכתיים רבים לגבי מעמדה ההלכתי של האישה כגון ניאוף וקיום מצוות הייבום והחליצה. כמו כן הועלו חששות לגבי יחוסו וכשרותו ההלכתית של הקטין כגון חשש ממזרות, גילוי עריות בין ילדי התורם, פגיעה במעמד הכהונה ובעיות בתחום המעמד האישי בשל אי ודאות לגבי זהות התורם. בנוסף, משליכה הכרעה בשאלות אלה על זכאות הקטין לזכויות סוציאליות המגיעות לו מאביו, כגון הזכות למזונות ולירושה. פסיקת ההלכה במאה האחרונה אימצה את עמדתו של הרב פיינשטיין, לפיה רק הריון הנובע ממגע מיני ישיר בין אישה נשואה לגבר זר, בניגוד להזרעה מלאכותית, יכול לפגוע במעמד האישה והילוד. עם זאת, פוסקים רבים אסרו לבצע הזרעה מלאכותית מגבר יהודי מטעמי זהירות, בגין חששות אלו.
פרק שני - הזרעה מלאכותית מתורם לא יהודי לאישה נשואה
על אף שבמקרה של תרומת זרע מנוכרי נעדר הילוד יחוס לאביו הנוכרי וכשרותו נקבעת על פי מעמד האם בלבד, מסתייגים פוסקים רבים מן הפעולה. הפוסקים מונים טיעונים רבים לאיסור תרומת זרע מגבר נוכרי וביניהם חילול השם, פגיעה בביצוע מנהג הייבום והחליצה, ספקות לגבי זכויות הירושה, עידוד ההפקרות המינית ופגיעה ביציבות התא המשפחתי המסורתי. בנוסף חוששים הם מבלבול לגבי זהות אבי הילוד ופגיעה במעמד הכהונה. במהלך המאה ה- 20 ניכרת מגמה בקרב פוסקים העוסקים בקבלה לייחוס תכונות שליליות לזרע נוכרי, אשר עוברות לילוד ובאופן זה פוגעות בקדושת העם היהודי. מעבר לשאלות ההלכתיות מועלים בפרק זה קשיים אתיים אשר מעוררת תרומת זרע אנונימית, המונעת מן הילוד לברר את שורשיו הביולוגיים.
חלק רביעי- יחס הפסיקה האורתודוקסית לשינויים במבנה המשפחה המסורתית
בעקבות שימוש בטכנולוגיות פריון חלק זה מנתח את יחס הפסיקה האורתודוקסית לשינויים במבנה המשפחה המסורתית בעקבות שימוש בטכנולוגיות פריון ומורכב משלושה פרקים: הזרעה מלאכותית לאישה פנויה, הפריה חוץ גופית והקמת משפחה אלטרנטיבית בפרספקטיבה הלכתית אורתודוקסית.
פרק ראשון - הזרעה מלאכותית לאישה פנויה
המוסכמה ההלכתית הינה כי ילדה של אישה פנויה לא ייחשב לממזר, אפילו אם אביו הביולוגי הוא יהודי. למרות זאת אסרו פוסקים מסויימים על הזרעה מלאכותית במקרה זה בגין חששות לייחוס הילוד, גילוי עריות וגזילת ירושת שאר האחים. חלק מן הפוסקים קוראים לאסור הזרעה מלאכותית לאישה פנויה בשם טובת הילד ולא מסיבות הלכתיות. אפשרות נוספת אשר השלכותיה ההלכתיות נידונות בפרק זה הינה ביצוע הזרעה מלאכותית באישה רווקה או אלמנה באמצעות שימוש בזרעו של אדם שנפטר. חשוב לציין כי השימוש בטכנולוגיה זו שנוי במחלוקת בקרב הרבנים בגין החשיבות אותה מייחסת היהדות לערך כבוד המת.
פרק שני - הפריה חוץ גופית
הפריית מבחנה יכולה להתבצע בין בני זוג נשואים בסיוע או ללא היזקקות לתרומת ביצית או זרע. פוסקים אשר התירו את השימוש בטכנולוגיה זו הביעו את חששותיהם בנוגע להשלכותיה ההלכתיות של הפריה החוץ גופית בשל הקושי לפקח על התהליך, הנעשה מחוץ לגוף האדם. מתנגדי הפריית המבחנה סברו כי היא מתערבת במלאכת הבריאה האלוהית ועשויה לדרדר את האנושות מבחינה מוסרית לתכנון ולשיבוט בני אדם.
הפריה חוץ גופית מעוררות שאלות הלכתיות חדשניות ובראשן שאלת הגדרת האמהות, כגון במקרי פונדקאות ותרומת ביציות, מהן הסתייגו מרבית פוסקי הדור במאה ה 20- . הקביעה שאומצה בשיח ההלכתי העכשווי גורסת כי אמו של התינוק תהיה האישה שילדה אותו, גם אם נולד מתרומת ביצית. הכרעה זו מובלעת ברציונל החוקים המסדירים את הפונדקאות במדינת ישראל ואשר מטילים מגבלות הלכתיות על בחירת הפונדקאית לשם מניעת חשש ממזרות או שאלה לגבי יהדותו של הילוד.
פרק שלישי - הקמת משפחה אלטרנטיבית בפרספקטיבה הלכתית אורתודוקסית
קיימת בעיה הלכתית מהותית במיסוד הקשר החד-מיני ביהדות האורתודוקסית. ספרות השו"ת האורתודוקסית אינה עוסקת במפורש בשאלת השימוש בהזרעה מלאכותית לצורך הקמת המשפחה החד- מינית. עם זאת, ניתן ללמוד רבות על גישת האורתודוקסיה משו"תים עכשוויים העוסקים בתופעת ההומוסקסואליות ובקיום מצוות הפריון במקרה זה. הדעה הרווחת היום בקרב הפוסקים הינה כי קשר חד- מיני אסור, כמו גם מיסודו וקיום מצוות פרו ורבו במסגרת זו. בשל כך ניתן להסיק כי הרבנים לא יתירו שימוש בהזרעה מלאכותית לצורך קיום מצוות הפריון במשפחה חד-מינית.
חלק חמישי- עמדת רבני הזרם רפורמי והקונסרבטיבי בשאלת ההזרעה המלאכותית
חלק זה מתמקד בזרמי היהדות הרפורמית והקונסרבטיבית ומציג את עמדות רבני זרמים אלו בעניין ההזרעה המלאכותית תוך עימותן עם עמדות פוסקים אורתודוקסיים.
פרק ראשון - עמדת הרבנות הרפורמית בשאלת ההזרעה המלאכותית
חשיבות מצוות הפריון מודגשת בספרות השו"ת הרפורמית, אולם טיפולי פוריות אינם מתפרשים כדרך היחידה לקיומה. על מנת שלא לפגוע במרקם החיים המשפחתי מוצעת לא אחת חלופת האימוץ לטיפולי פוריות מייגעים, תרומת זרע והיזקקות לפונדקאות ותרומת ביציות. שאלת השחתת הזרע, המעסיקה רבות את רבני הזרם האורתודוקסי, כמעט שאינה נידונה על ידי רבני הזרם הרפורמי. באשר לשאלות של כשרות וייחוס, רווחת הדעה בקרב רבנים רפורמיים בולטים כגון הרב הומולקה ורומיין, כי מעמד הממזרות איננו רלוונטי עוד בימינו ולכן ממילא לא נשקפת לילד הסכנה שזכויותיו הדתיות ייפגעו.
ועד הרבנים הרפורמיים התיר לחבריו לפעול לפי שיקול דעתם בעניין עריכת טקס נישואין דתי בין בני זוג בני אותו המין, תוך הדגשת הויכוח הפנימי בתנועה ומורת הרוח הקיימת מצד הזרמים האחרים ביהדות.
פרק שני - עמדת הרבנות הקונסרבטיבית בשאלת ההזרעה המלאכותית
עמדת רבני היהדות הקונסרבטיבית גורסת כי טיפולי פוריות מהווים רשות, אך אינם בגדר חובה עבור זוגות הרוצים לקיים את מצוות הפריה והרבייה ומתקשים בכך. בדומה לביטולה של גזירת הממזרות בזרם הרפורמי, בוטל מעמד זה לאחרונה גם ביהדות הקונסרבטיבית. אוננות במסגרת טיפולי פוריות הינה מותרת ואיננה מוגדרת כהשחתת זרע לבטלה ואף מותרת גם לשם תרומת זרע של יהודי לאישה לא יהודיה. כמו בזרם הרפורמי גם כאן מונחת אופציית האימוץ על סדר היום.
כנסת הרבנים הקונסרבטיבים בארצות הברית קיבלה החלטה ברוב זעום להכרה אזרחית בהומוסקסואלים, אך עם זאת השאירה על כנו את האיסור לקדש זוגות אלה. אין בהחלטה זו הכרה הלכתית בזוגיות החד-מינית אלא קבלתם החברתית של זוגות אלה ועידודם להשתלב בקהילות הקונסרבטיביות.
חלק שישי - סיכום ודיון בהשלכות המחקר
בחלקו השישי והאחרון בעבודת מחקר זו נסכם ונדון בהשלכותיה האתיות והגלובליולת של הפסיקה ההלכית בשאלה הנידונה.
כפי שניתן לראות מעבודת מחקר זו, הרבנים האורתודוקסיים מסתמכים בהכרעותיהם בעיקר על שיקולים הלכתיים ופחות על שיקולים אתיים ואוניברסליים. מחד, מסתייגים פוסקים אורתודוקסיים מסויימים משימוש לרעה בטיפולי פוריות, אך מאידך מוכנים הם בשם עקרונות דתיים להתיר שימוש בטכנולוגיות אלו במקרים שאינם מצריכים זאת משיקולים רפואיים. במיוחד בולט העדר התייחסותם של הפוסקים האורתודוקסיים לשיקולים מוסריים חברתיים, כמו גם לרצונה ולרווחתה של האישה העוברת טיפולי פוריות. לעומתם מביעים רבני הזרם הרפורמי והקונסרבטיבי את דאגתם להשלכותיהם של טיפולים אלו על נשים הנזקקות להתערבות רפואית מעין זו לשם התעברות ואלו העובדות בתעשיית הפריון. יש לציין כי הדיון ההלכתי עוסק בהיבט צר בלבד של שאלת ההזרעה המלאכותית ואינו נוגע ברבות מן השאלות המורכבות שמעוררות טכנולוגיות פריון מתקדמות. עם זאת הדיון ההלכתי הינו חשוב ביותר ומציף אף שאלות נוספות בדבר הסכנה הצפויה מהפיכתן של טכנולוגיות אלה לכלי שרת בידי אידאולוגיות דתיות או פוליטיות.
The controlled dosage of substances from a device to its environment, such as a tissue or an organ in medical applications or a reactor, room, machinery or ecosystem in technical, should ideally match the requirements of the applications, e.g. in terms of the time point at which the cargo is released. On-demand dosage systems may enable such a desired release pattern, if the device contain suitable features that can translate external signals into a release function. This study is motivated by the opportunities arising from microsystems capable of an on-demand release and the contributions that geometrical design may have in realizing such features. The goals of this work included the design, fabrication, characterization and experimental proof-of-concept of geometry-assisted triggerable dosing effect (a) with a sequential dosing release and (b) in a self-sufficient dosage system. Structure-function relationships were addressed on the molecular, morphological and, with a particular attention, the device design level, which is on the micrometer scale. Models and/or computational tools were used to screen the parameter space and provide guidance for experiments.