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Magmatic-hydrothermal fluids are responsible for numerous mineralization types, including porphyry copper and granite related tin-tungsten (Sn-W) deposits. Ore formation is dependent on various factors, including, the pressure and temperature regime of the intrusions, the chemical composition of the magma and hydrothermal fluids, and fluid rock interaction during the ascent. Fluid inclusions have potential to provide direct information on the temperature, salinity, pressure and chemical composition of fluids responsible for ore formation. Numerical modeling allows the parametrization of pluton features that cannot be analyzed directly via geological observations.
Microthermometry of fluid inclusions from the Zinnwald Sn-W deposit, Erzgebirge, Germany / Czech Republic, provide evidence that the greisen mineralization is associated with a low salinity (2-10 wt.% NaCl eq.) fluid with homogenization temperatures between 350°C and 400°C. Quartzes from numerous veins are host to inclusions with the same temperatures and salinities, whereas cassiterite- and wolframite-hosted assemblages with slightly lower temperatures (around 350°C) and higher salinities (ca. 15 wt. NaCl eq.). Further, rare quartz samples contained boiling assemblages consisting of coexisting brine and vapor phases. The formation of ore minerals within the greisen is driven by invasive fluid-rock interaction, resulting in the loss of complexing agents (Cl-) leading to precipitation of cassiterite. The fluid inclusion record in the veins suggests boiling as the main reason for cassiterite and wolframite mineralization. Ore and coexisting gangue minerals hosted different types of fluid inclusions where the beginning boiling processes are solely preserved by the ore minerals emphasizing the importance of microthermometry in ore minerals. Further, the study indicates that boiling as a precipitation mechanism can only occur in mineralization related to shallow intrusions whereas deeper plutons prevent the fluid from boiling and can therefore form tungsten mineralization in the distal regions.
The tin mineralization in the Hämmerlein deposit, Erzgebirge, Germany, occurs within a skarn horizon and the underlying schist. Cassiterite within the skarn contains highly saline (30-50 wt% NaCl eq.) fluid inclusions, with homogenization temperatures up to 500°C, whereas cassiterites from the schist and additional greisen samples contain inclusions of lower salinity (~5 wt% NaCl eq.) and temperature (between 350 and 400°C). Inclusions in the gangue minerals (quartz, fluorite) preserve homogenization temperatures below 350°C and sphalerite showed the lowest homogenization temperatures (ca. 200°C) whereby all minerals (cassiterite from schist and greisen, gangue minerals and sphalerite) show similar salinity ranges (2-5 wt% NaCl eq.). Similar trace element contents and linear trends in the chemistry of the inclusions suggest a common source fluid. The inclusion record in the Hämmerlein deposit documents an early exsolution of hot brines from the underlying granite which is responsible for the mineralization hosted by the skarn. Cassiterites in schist and greisen are mainly forming due to fluid-rock interaction at lower temperatures. The low temperature inclusions documented in the sphalerite mineralization as well as their generally low trace element composition in comparison to the other minerals suggests that their formation was induced by mixing with meteoric fluids.
Numerical simulations of magma chambers and overlying copper distribution document the importance of incremental growth by sills. We analyzed the cooling behavior at variable injection intervals as well as sill thicknesses. The models suggest that magma accumulation requires volumetric injection rates of at least 4 x 10-4 km³/y. These injection rates are further needed to form a stable magmatic-hydrothermal fluid plume above the magma chamber to ensure a constant copper precipitation and enrichment within a confined location in order to form high-grade ore shells within a narrow geological timeframe between 50 and 100 kyrs as suggested for porphyry copper deposits. The highest copper enrichment can be found in regions with steep temperature gradients, typical of regions where the magmatic-hydrothermal fluid meets the cooler ambient fluids.
Das Preußische Erbrecht in der Judikatur des Berliner Obertribunals in den Jahren 1836 bis 1865
(2019)
Die Dissertation befasst sich mit dem Allgemeinen Preußischen Landrecht von 1794 und der hierzu ergangenen Rechtsprechung des Berliner Obertribunals. Im Fokus der Untersuchung stehen die erbrechtlichen Regelungen des Landrechts und deren Anwendung sowie Auslegung in der Judikatur des höchsten preußischen Gerichts. Der Forschungsgegenstand ergibt sich aus dem im Landrecht kodifizierten speziellen Gesetzesverständnisses. Nach diesem sollte die Gesetzesauslegung durch die Rechtsprechung auf ein Minimum, nämlich die Auslegung allein anhand des Wortlauts der Regelung reduziert werden, um dem absolutistischen Regierungsanspruch der preußischen Monarchen, namentlich Friedrich des Großen, hinreichend Rechnung zu tragen. In diesem Kontext wird der Frage nachgegangen, inwieweit das preußische Obertribunal das im Landrecht statuierte „Auslegungsverbot“ beachtet hat und in welchen Fällen sich das Gericht von der Vorgabe emanzipierte und weitere Auslegungsmethoden anwendete und sich so eine unabhängige Rechtsprechung entwickeln konnte.
Die Arbeit gliedert sich in drei Hauptabschnitte. Im Anschluss an die Einleitung, in der zunächst die rechtshistorische Bedeutung des Landrechts und des Erbrechts sowie der Untersuchungsgegenstand umrissen werden, folgt die Darstellung der Entstehungsgeschichte des Landrechts und des Berliner Obertribunals.
Hieran schließt sich in einem dritten Abschnitt eine Analyse der erbrechtlichen Vorschriften des Landrechts an. In dieser wird auf die Entstehungsgeschichte der verschiedenen erbrechtlichen Institute wie beispielsweise der gesetzlichen und gewillkürten Erbfolge, dem Pflichtteilsrecht etc., unter Berücksichtigung des zeitgenössischen wissenschaftlichen Diskurses eingegangen.
Im vierten Abschnitt geht es um die Judikate des Berliner Obertribunals aus den Jahren 1836-1865 in denen die zuvor dargestellten erbrechtlichen Regelungen entscheidungserheblich waren. Dabei wird der Forschungsfrage, inwieweit das Obertribunal das im Landrecht statuierte Auslegungsverbot beachtet hat und in welchen Fällen es von diesem abwich bzw. weitere Auslegungsmethoden anwendete, konkret nachgegangen wird. Insgesamt werden 26 Entscheidungen des Obertribunals unter dem Aspekt der Auslegungspraxis, der Kontinuität und der Beschleunigung der Rechtsprechung analysiert und ausgewertet.
Since half a century, cytometry has been a major scientific discipline in the field of cytomics - the study of system’s biology at single cell level. It enables the investigation of physiological processes, functional characteristics and rare events with proteins by analysing multiple parameters on an individual cell basis. In the last decade, mass cytometry has been established which increased the parallel measurement to up to 50 proteins. This has shifted the analysis strategy from conventional consecutive manual gates towards multi-dimensional data processing. Novel algorithms have been developed to tackle these high-dimensional protein combinations in the data. They are mainly based on clustering or non-linear dimension reduction techniques, or both, often combined with an upstream downsampling procedure. However, these tools have obstacles either in comprehensible interpretability, reproducibility, computational complexity or in comparability between samples and groups.
To address this bottleneck, a reproducible, semi-automated cytometric data mining workflow PRI (pattern recognition of immune cells) is proposed which combines three main steps: i) data preparation and storage; ii) bin-based combinatorial variable engineering of three protein markers, the so called triploTs, and subsequent sectioning of these triploTs in four parts; and iii) deployment of a data-driven supervised learning algorithm, the cross-validated elastic-net regularized logistic regression, with these triploT sections as input variables. As a result, the selected variables from the models are ranked by their prevalence, which potentially have discriminative value. The purpose is to significantly facilitate the identification of meaningful subpopulations, which are most distinguish between two groups. The proposed workflow PRI is exemplified by a recently published public mass cytometry data set. The authors found a T cell subpopulation which is discriminative between effective and ineffective treatment of breast carcinomas in mice. With PRI, that subpopulation was not only validated, but was further narrowed down as a particular Th1 cell population. Moreover, additional insights of combinatorial protein expressions are revealed in a traceable manner. An essential element in the workflow is the reproducible variable engineering. These variables serve as basis for a clearly interpretable visualization, for a structured variable exploration and as input layers in neural network constructs.
PRI facilitates the determination of marker levels in a semi-continuous manner. Jointly with the combinatorial display, it allows a straightforward observation of correlating patterns, and thus, the dominant expressed markers and cell hierarchies. Furthermore, it enables the identification and complex characterization of discriminating subpopulations due to its reproducible and pseudo-multi-parametric pattern presentation. This endorses its applicability as a tool for unbiased investigations on cell subsets within multi-dimensional cytometric data sets.
Medical imaging plays an important role in disease diagnosis, treatment planning, and clinical monitoring. One of the major challenges in medical image analysis is imbalanced training data, in which the class of interest is much rarer than the other classes. Canonical machine learning algorithms suppose that the number of samples from different classes in the training dataset is roughly similar or balance. Training a machine learning model on an imbalanced dataset can introduce unique challenges to the learning problem.
A model learned from imbalanced training data is biased towards the high-frequency samples. The predicted results of such networks have low sensitivity and high precision. In medical applications, the cost of misclassification of the minority class could be more than the cost of misclassification of the majority class. For example, the risk of not detecting a tumor could be much higher than referring to a healthy subject to a doctor. The current Ph.D. thesis introduces several deep learning-based approaches for handling class imbalanced problems for learning multi-task such as disease classification and semantic segmentation.
At the data-level, the objective is to balance the data distribution through re-sampling the data space: we propose novel approaches to correct internal bias towards fewer frequency samples. These approaches include patient-wise batch sampling, complimentary labels, supervised and unsupervised minority oversampling using generative adversarial networks for all.
On the other hand, at algorithm-level, we modify the learning algorithm to alleviate the bias towards majority classes. In this regard, we propose different generative adversarial networks for cost-sensitive learning, ensemble learning, and mutual learning to deal with highly imbalanced imaging data.
We show evidence that the proposed approaches are applicable to different types of medical images of varied sizes on different applications of routine clinical tasks, such as disease classification and semantic segmentation. Our various implemented algorithms have shown outstanding results on different medical imaging challenges.
Light-switchable proteins are being used increasingly to understand and manipulate complex molecular systems. The success of this approach has fueled the development of tailored photo-switchable proteins, to enable targeted molecular events to be studied using light. The development of novel photo-switchable tools has to date largely relied on rational design. Complementing this approach with directed evolution would be expected to facilitate these efforts. Directed evolution, however, has been relatively infrequently used to develop photo-switchable proteins due to the challenge presented by high-throughput evaluation of switchable protein activity. This thesis describes the development of two genetic circuits that can be used to evaluate libraries of switchable proteins, enabling optimization of both the on- and off-states. A screening system is described, which permits detection of DNA-binding activity based on conditional expression of a fluorescent protein. In addition, a tunable selection system is presented, which allows for the targeted selection of protein-protein interactions of a desired affinity range. This thesis additionally describes the development and characterization of a synthetic protein that was designed to investigate chromophore reconstitution in photoactive yellow protein (PYP), a promising scaffold for engineering photo-controlled protein tools.
Earthquake swarms are characterized by large numbers of events occurring in a short period of time within a confined source volume and without significant mainshock aftershock pattern as opposed to tectonic sequences. Intraplate swarms in the absence of active volcanism usually occur in continental rifts as for example in the Eger Rift zone in North West Bohemia, Czech Republic. A common hypothesis links event triggering to pressurized fluids. However, the exact causal chain is often poorly understood since the underlying geotectonic processes are slow compared to tectonic sequences. The high event rate during active periods challenges standard seismological routines as these are often designed for single events and therefore costly in terms of human resources when working with phase picks or computationally costly when exploiting full waveforms.
This methodological thesis develops new approaches to analyze earthquake swarm seismicity as well as the underlying seismogenic volume. It focuses on the region of North West (NW) Bohemia, a well studied, well monitored earthquake swarm region.
In this work I develop and test an innovative approach to detect and locate earthquakes using deep convolutional neural networks. This technology offers great potential as it allows to efficiently process large amounts of data which becomes increasingly important given that seismological data storage grows at increasing pace. The proposed deep neural network trained on NW Bohemian earthquake swarm records is able to locate 1000 events in less than 1 second using full waveforms while approaching precision of double difference relocated catalogs. A further technological novelty is that the trained filters of the deep neural network’s first layer can be repurposed to function as a pattern matching event detector without additional training on noise datasets. For further methodological development and benchmarking, I present a new toolbox to generate realistic earthquake cluster catalogs as well as synthetic full waveforms of those clusters in an automated fashion. The input is parameterized using constraints on source volume geometry, nucleation and frequency-magnitude relations. It harnesses recorded noise to produce highly realistic synthetic data for benchmarking and development. This tool is used to study and assess detection performance in terms of magnitude of completeness Mc of a full waveform detector applied to synthetic data of a hydrofracturing experiment at the Wysin site, Poland.
Finally, I present and demonstrate a novel approach to overcome the masking effects of wave propagation between earthquake and stations and to determine source volume attenuation directly in the source volume where clustered earthquakes occur. The new event couple spectral ratio approach exploits high frequency spectral slopes of two events sharing the greater part of their rays. Synthetic tests based on the toolbox mentioned before show that this method is able to infer seismic wave attenuation within the source volume at high spatial resolution. Furthermore, it is independent from the distance towards a station as well as the complexity of the attenuation and velocity structure outside of the source volume of swarms. The application to recordings of the NW Bohemian earthquake swarm shows increased P phase attenuation within the source volume (Qp < 100) based on results at a station located close to the village Luby (LBC). The recordings of a station located in epicentral proximity, close to Nový Kostel (NKC), show a relatively high complexity indicating that waves arriving at that station experience more scattering than signals recorded at other stations. The high level of complexity destabilizes the inversion. Therefore, the Q estimate at NKC is not reliable and an independent proof of the high attenuation finding given the geometrical and frequency constraints is still to be done. However, a high attenuation in the source volume of NW Bohemian swarms has been postulated before in relation to an expected, highly damaged zone bearing CO 2 at high pressure.
The methods developed in the course of this thesis yield the potential to improve our understanding regarding the role of fluids and gases in intraplate event clustering.
Die Anfechtbarkeit und die Feststellbarkeit der Mutterschaft de lege lata und de lege ferenda
(2019)
Der althergebrachte Grundsatz, wonach das Kind von der Frau abstammt, welche es geboren hat, ist durch die moderne Fortpflanzungsmedizin ins Wanken geraten. Dennoch ordnet § 1591 BGB das Kind unanfechtbar der Geburtsmutter zu. Rechtliche und genetische Mutterschaft fallen deshalb dauerhaft auseinander, wenn das Kind im Wege der Leihmutterschaft oder nach einer Eizell- bzw. Embryospende zur Welt kommt. Die auf diese Methoden der artifiziellen Reproduktion bezogenen, im Inland bestehenden Verbote halten Paare mit Kinderwunsch nicht davon ab, auf entsprechende Angebote im Ausland zurückzugreifen. Daraus resultierende kollisions- und verfassungsrechtliche Probleme sind Gegenstand der vorliegenden Arbeit.
Für den Bereich der Leihmutterschaft wird der Frage nachgegangen, ob die mit dem Anfechtungsausschluss verfolgten Ziele des Gesetzgebers die damit einhergehenden Beeinträchtigungen grundrechtlich geschützter Rechtspositionen von genetischer Mutter und Kind rechtfertigen können. Besonderes Augenmerk liegt auf dem von Art. 6 Abs. 2 S. 1 GG geschützten Interesse von leiblichen Eltern und Kindern, die verfahrensrechtliche Möglichkeit zu erhalten, rechtlich einander zugeordnet zu werden. Dieses Interesse wird den Zielen des Gesetzgebers, der mit dem Anfechtungsausschluss die Rechte von Leihmüttern und Kindern zu schützen beabsichtigt, im Rahmen einer umfassenden Verhältnismäßigkeitsprüfung gegenübergestellt.
In den Konstellationen der Eizell- und Embryospende tritt schwerpunktmäßig das Recht des Kindes auf Kenntnis der eigenen Abstammung in den Vordergrund und mit ihm die Frage, ob sich daraus eine Verpflichtung des Gesetzgebers ableiten lässt, den Tatbestand von § 1598a BGB so zu erweitern, dass die vermuteten genetischen Eltern für den Bereich der artifiziellen Reproduktion in den Kreis der Klärungsverpflichteten aufgenommen werden.
Neben diesen Schwerpunkten werden viele weitere Probleme angesprochen. Im Ergebnis mündet die Arbeit in einen Vorschlag für die Legislative.
In this thesis we introduce the concept of the degree of formality. It is directed against a dualistic point of view, which only distinguishes between formal and informal proofs. This dualistic attitude does not respect the differences between the argumentations classified as informal and it is unproductive because the individual potential of the respective argumentation styles cannot be appreciated and remains untapped.
This thesis has two parts. In the first of them we analyse the concept of the degree of formality (including a discussion about the respective benefits for each degree) while in the second we demonstrate its usefulness in three case studies. In the first case study we will repair Haskell B. Curry's view of mathematics, which incidentally is of great importance in the first part of this thesis, in light of the different degrees of formality. In the second case study we delineate how awareness of the different degrees of formality can be used to help students to learn how to prove. Third, we will show how the advantages of proofs of different degrees of formality can be combined by the development of so called tactics having a medium degree of formality. Together the three case studies show that the degrees of formality provide a convincing solution to the problem of untapped potential.
With the growth of information technology, patient attitudes are shifting – away from passively receiving care towards actively taking responsibility for their well- being. Handling doctor-patient relationships collaboratively and providing patients access to their health information are crucial steps in empowering patients. In mental healthcare, the implicit consensus amongst practitioners has been that sharing medical records with patients may have an unpredictable, harmful impact on clinical practice. In order to involve patients more actively in mental healthcare processes, Tele-Board MED (TBM) allows for digital collaborative documentation in therapist-patient sessions. The TBM software system offers a whiteboard-inspired graphical user interface that allows therapist and patient to jointly take notes during the treatment session. Furthermore, it provides features to automatically reuse the digital treatment session notes for the creation of treatment session summaries and clinical case reports. This thesis presents the development of the TBM system and evaluates its effects on 1) the fulfillment of the therapist’s duties of clinical case documentation, 2) patient engagement in care processes, and 3) the therapist-patient relationship. Following the design research methodology, TBM was developed and tested in multiple evaluation studies in the domains of cognitive behavioral psychotherapy and addiction care. The results show that therapists are likely to use TBM with patients if they have a technology-friendly attitude and when its use suits the treatment context. Support in carrying out documentation duties as well as fulfilling legal requirements contributes to therapist acceptance. Furthermore, therapists value TBM as a tool to provide a discussion framework and quick access to worksheets during treatment sessions. Therapists express skepticism, however, regarding technology use in patient sessions and towards complete record transparency in general. Patients expect TBM to improve the communication with their therapist and to offer a better recall of discussed topics when taking a copy of their notes home after the session. Patients are doubtful regarding a possible distraction of the therapist and usage in situations when relationship-building is crucial. When applied in a clinical environment, collaborative note-taking with TBM encourages patient engagement and a team feeling between therapist and patient. Furthermore, it increases the patient’s acceptance of their diagnosis, which in turn is an important predictor for therapy success. In summary, TBM has a high potential to deliver more than documentation support and record transparency for patients, but also to contribute to a collaborative doctor-patient relationship. This thesis provides design implications for the development of digital collaborative documentation systems in (mental) healthcare as well as recommendations for a successful implementation in clinical practice.
One method of embedding groups into skew fields was introduced by A. I. Mal'tsev and B. H. Neumann (cf. [18, 19]). If G is an ordered group and F is a skew field, the set F((G)) of formal power series over F in G with well-ordered support forms a skew field into which the group ring F[G] can be embedded. Unfortunately it is not suficient that G is left-ordered since F((G)) is only an F-vector space in this case as there is no natural way to define a multiplication on F((G)). One way to extend the original idea onto left-ordered groups is to examine the endomorphism ring of F((G)) as explored by N. I. Dubrovin (cf. [5, 6]). It is possible to embed any crossed product ring F[G; η, σ] into the endomorphism ring of F((G)) such that each non-zero element of F[G; η, σ] defines an automorphism of F((G)) (cf. [5, 10]). Thus, the rational closure of F[G; η, σ] in the endomorphism ring of F((G)), which we will call the Dubrovin-ring of F[G; η, σ], is a potential candidate for a skew field of fractions of F[G; η, σ]. The methods of N. I. Dubrovin allowed to show that specific classes of groups can be embedded into a skew field. For example, N. I. Dubrovin contrived some special criteria, which are applicable on the universal covering group of SL(2, R). These methods have also been explored by J. Gräter and R. P. Sperner (cf. [10]) as well as N.H. Halimi and T. Ito (cf. [11]). Furthermore, it is of interest to know if skew fields of fractions are unique. For example, left and right Ore domains have unique skew fields of fractions (cf. [2]). This is not the general case as for example the free group with 2 generators can be embedded into non-isomorphic skew fields of fractions (cf. [12]). It seems likely that Ore domains are the most general case for which unique skew fields of fractions exist. One approach to gain uniqueness is to restrict the search to skew fields of fractions with additional properties. I. Hughes has defined skew fields of fractions of crossed product rings F[G; η, σ] with locally indicable G which fulfill a special condition. These are called Hughes-free skew fields of fractions and I. Hughes has proven that they are unique if they exist [13, 14]. This thesis will connect the ideas of N. I. Dubrovin and I. Hughes. The first chapter contains the basic terminology and concepts used in this thesis. We present methods provided by N. I. Dubrovin such as the complexity of elements in rational closures and special properties of endomorphisms of the vector space of formal power series F((G)). To combine the ideas of N.I. Dubrovin and I. Hughes we introduce Conradian left-ordered groups of maximal rank and examine their connection to locally indicable groups. Furthermore we provide notations for crossed product rings, skew fields of fractions as well as Dubrovin-rings and prove some technical statements which are used in later parts. The second chapter focuses on Hughes-free skew fields of fractions and their connection to Dubrovin-rings. For that purpose we introduce series representations to interpret elements of Hughes-free skew fields of fractions as skew formal Laurent series. This 1 Introduction allows us to prove that for Conradian left-ordered groups G of maximal rank the statement "F[G; η, σ] has a Hughes-free skew field of fractions" implies "The Dubrovin ring of F [G; η, σ] is a skew field". We will also prove the reverse and apply the results to give a new prove of Theorem 1 in [13]. Furthermore we will show how to extend injective ring homomorphisms of some crossed product rings onto their Hughes-free skew fields of fractions. At last we will be able to answer the open question whether Hughes--free skew fields are strongly Hughes-free (cf. [17, page 53]).
Geomagnetic paleosecular variations (PSVs) are an expression of geodynamo processes inside the Earth’s liquid outer core. These paleomagnetic time series provide insights into the properties of the Earth’s magnetic field, from normal behavior with a dominating dipolar geometry, over field crises, such as pronounced intensity lows and geomagnetic excursions with a distorted field geometry, to the complete reversal of the dominating dipole contribution. Particularly, long-term high-resolution and high-quality PSV time series are needed for properly reconstructing the higher frequency components in the spectrum of geomagnetic field variations and for a better understanding of the effects of smoothing during the recording of such paleomagnetic records by sedimentary archives.
In this doctorate study, full vector paleomagnetic records were derived from 16 sediment cores recovered from the southeastern Black Sea. Age models are based on radiocarbon dating and correlations of warming/cooling cycles monitored by high-resolution X-ray fluorescence (XRF) elementary ratios as well as ice-rafted debris (IRD) in Black Sea sediments to the sequence of ‘Dansgaard-Oeschger’ (DO) events defined from Greenland ice core oxygen isotope stratigraphy.
In order to identify the carriers of magnetization in Black Sea sediments, core MSM33-55-1 recovered from the southeast Black Sea was subjected to detailed rock magnetic and electron microscopy investigations. The younger part of core MSM33-55-1 was continuously deposited since 41 ka. Before 17.5 ka, the magnetic minerals were dominated by a mixture of greigite (Fe3S4) and titanomagnetite (Fe3-xTixO4) in samples with SIRM/κLF >10 kAm-1, or exclusively by titanomagnetite in samples with SIRM/κLF ≤10 kAm-1. It was found that greigite is generally present as crustal aggregates in locally reducing micro-environments. From 17.5 ka to 8.3 ka, the dominant magnetic mineral in this transition phase was changing from greigite (17.5 – ~10.0 ka) to probably silicate-hosted titanomagnetite (~10.0 – 8.3 ka). After 8.3 ka, the anoxic Black Sea was a favorable environment for the formation of non-magnetic pyrite (FeS2) framboids.
Aiming to avoid compromising of paleomagnetic data by erroneous directions carried by greigite, paleomagnetic data from samples with SIRM/κLF >10 kAm-1, shown to contain greigite by various methods, were removed from obtained records. Consequently, full vector paleomagnetic records, comprising directional data and relative paleointensity (rPI), were derived only from samples with SIRM/κLF ≤10 kAm-1 from 16 Black Sea sediment cores. The obtained data sets were used to create a stack covering the time window between 68.9 and 14.5 ka with temporal resolution between 40 and 100 years, depending on sedimentation rates.
At 64.5 ka, according to obtained results from Black Sea sediments, the second deepest minimum in relative paleointensity during the past 69 ka occurred. The field minimum during MIS 4 is associated with large declination swings beginning about 3 ka before the minimum. While a swing to 50°E is associated with steep inclinations (50-60°) according to the coring site at 42°N, the subsequent declination swing to 30°W is associated with shallow inclinations of down to 40°. Nevertheless, these large deviations from the direction of a geocentric axial dipole field (I=61°, D=0°) still can not yet be termed as 'excursional', since latitudes of corresponding VGPs only reach down to 51.5°N (120°E) and 61.5°N (75°W), respectively. However, these VGP positions at opposite sides of the globe are linked with VGP drift rates of up to 0.2° per year in between. These extreme secular variations might be the mid-latitude expression of the Norwegian–Greenland Sea excursion found at several sites much further North in Arctic marine sediments between 69°N and 81°N.
At about 34.5 ka, the Mono Lake excursion is evidenced in the stacked Black Sea PSV record by both a rPI minimum and directional shifts. Associated VGPs from stacked Black Sea data migrated from Alaska, via central Asia and the Tibetan Plateau, to Greenland, performing a clockwise loop. This agrees with data recorded in the Wilson Creek Formation, USA., and Arctic sediment core PS2644-5 from the Iceland Sea, suggesting a dominant dipole field. On the other hand, the Auckland lava flows, New Zealand, the Summer Lake, USA., and Arctic sediment core from ODP Site-919 yield distinct VGPs located in the central Pacific Ocean due to a presumably non-dipole (multi-pole) field configuration.
A directional anomaly at 18.5 ka, associated with pronounced swings in inclination and declination, as well as a low in rPI, is probably contemporaneous with the Hilina Pali excursion, originally reported from Hawaiian lava flows. However, virtual geomagnetic poles (VGPs) calculated from Black Sea sediments are not located at latitudes lower than 60° N, which denotes normal, though pronounced secular variations. During the postulated Hilina Pali excursion, the VGPs calculated from Black Sea data migrated clockwise only along the coasts of the Arctic Ocean from NE Canada (20.0 ka), via Alaska (18.6 ka) and NE Siberia (18.0 ka) to Svalbard (17.0 ka), then looping clockwise through the Eastern Arctic Ocean.
In addition to the Mono Lake and the Norwegian–Greenland Sea excursions, the Laschamp excursion was evidenced in the Black Sea PSV record with the lowest paleointensities at about 41.6 ka and a short-term (~500 years) full reversal centered at 41 ka. These excursions are further evidenced by an abnormal PSV index, though only the Laschamp and the Mono Lake excursions exhibit excursional VGP positions. The stacked Black Sea paleomagnetic record was also converted into one component parallel to the direction expected from a geocentric axial dipole (GAD) and two components perpendicular to it, representing only non-GAD components of the geomagnetic field. The Laschamp and the Norwegian–Greenland Sea excursions are characterized by extremely low GAD components, while the Mono Lake excursion is marked by large non-GAD contributions. Notably, negative values of the GAD component, indicating a fully reversed geomagnetic field, are observed only during the Laschamp excursion.
In summary, this doctoral thesis reconstructed high-resolution and high-fidelity PSV records from SE Black Sea sediments. The obtained record comprises three geomagnetic excursions, the Norwegian–Greenland Sea excursion, the Laschamp excursion, and the Mono Lake excursion. They are characterized by abnormal secular variations of different amplitudes centered at about 64.5 ka, 41.0 ka and 34.5 ka, respectively. In addition, the obtained PSV record from the Black Sea do not provide evidence for the postulated 'Hilina Pali excursion' at about 18.5 ka. Anyway, the obtained Black Sea paleomagnetic record, covering field fluctuations from normal secular variations, over excursions, to a short but full reversal, points to a geomagnetic field characterized by a large dynamic range in intensity and a highly variable superposition of dipole and non-dipole contributions from the geodynamo during the past 68.9 to 14.5 ka.
Phytoplankton growth depends not only on the mean intensity but also on the dynamics of the light supply. The nonlinear light-dependency of growth is characterized by a small number of basic parameters: the compensation light intensity PARcompμ, where production and losses are balanced, the growth efficiency at sub-saturating light αµ, and the maximum growth rate at saturating light µmax. In surface mixed layers, phytoplankton may rapidly move between high light intensities and almost darkness. Because of the different frequency distribution of light and/or acclimation processes, the light-dependency of growth may differ between constant and fluctuating light. Very few studies measured growth under fluctuating light at a sufficient number of mean light intensities to estimate the parameters of the growth-irradiance relationship. Hence, the influence of light dynamics on µmax, αµ and PARcompμ are still largely unknown. By extension, accurate modelling predictions of phytoplankton development under fluctuating light exposure remain difficult to make. This PhD thesis does not intend to directly extrapolate few experimental results to aquatic systems – but rather improving the mechanistic understanding of the variation of the light-dependency of growth under light fluctuations and effects on phytoplankton development.
In Lake TaiHu and at the Three Gorges Reservoir (China), we incubated phytoplankton communities in bottles placed either at fixed depths or moved vertically through the water column to mimic vertical mixing. Phytoplankton at fixed depths received only the diurnal changes in light (defined as constant light regime), while phytoplankton received rapidly fluctuating light by superimposing the vertical light gradient on the natural sinusoidal diurnal sunlight. The vertically moved samples followed a circular movement with 20 min per revolution, replicating to some extent the full overturn of typical Langmuir cells. Growth, photosynthesis, oxygen production and respiration of communities (at Lake TaiHu) were
measured. To complete these investigations, a physiological experiment was performed in the laboratory on a toxic strain of Microcystis aeruginosa (FACBH 1322) incubated under 20 min period fluctuating light. Here, we measured electron transport rates and net oxygen production at a much higher time resolution (single minute timescale).
The present PhD thesis provides evidence for substantial effects of fluctuating light on the eco-physiology of phytoplankton. Both experiments performed under semi-natural conditions in Lake TaiHu and at the Three Gorges Reservoir gave similar results. The significant decline in community growth efficiencies αµ under fluctuating light was caused for a great share by different frequency distribution of light intensities that shortened the effective daylength for production. The remaining gap in community αµ was attributed to species-specific photoacclimation mechanisms and to light-dependent respiratory losses. In contrast, community maximal growth rates µmax were similar between incubations at constant and fluctuating light. At daily growth saturating light supply, differences in losses for biosynthesis between the two light regimes were observed. Phytoplankton experiencing constant light suffered photo-inhibition - leading to photosynthesis foregone and additional respiratory costs for photosystems repair. On the contrary, intermittent exposure to low and high light intensities prevented photo-inhibition of mixed algae but forced them to develop alternative light strategy. They better harvested and exploited surface irradiance by enhancing their photosynthesis. In the laboratory, we showed that Microcystis aeruginosa increased its oxygen consumption by dark respiration in the light few minutes only after exposure to increasing light intensities. More, we proved that within a simulated Langmuir cell, the net production at saturating light and the compensation light intensity for production at limiting light are positively related. These results are best explained by an accumulation of photosynthetic products at increasing irradiance and mobilization of these fresh resources by rapid enhancement of dark respiration for maintenance and biosynthesis at decreasing irradiance. At the daily timescale, we showed that the enhancement of photosynthesis at high irradiance for biosynthesis of species increased their maintenance respiratory costs at limiting light. Species-specific growth at saturating light µmax and compensation light intensity for growth PARcompμ of species incubated in Lake TaiHu were positively related. Because of this species-specific physiological tradeoff, species displayed different light affinities to limiting and saturating light - thereby exhibiting a gleaner-opportunist tradeoff. In Lake TaiHu, we showed that inter-specific differences in light acquisition traits (µmax and PARcompμ) allowed coexis¬tence of species on a gradient of constant
light while avoiding competitive exclusion. More interestingly we demonstrated for the first time that vertical mixing (inducing fluctuating light supply for phytoplankton) may alter or even reverse the light utilization strategies of species within couple of days. The intra-specific variation in traits under fluctuating light increased the niche space for acclimated species, precluding competitive exclusion.
Overall, this PhD thesis contributes to a better understanding of phytoplankton eco-physiology under fluctuating light supply. This work could enhance the quality of predictions of phytoplankton development under certain weather conditions or climate change scenarios.
A contemporary challenge in Ecology and Evolutionary Biology is to anticipate the fate of populations of organisms in the context of a changing world. Climate change and landscape changes due to anthropic activities have been of major concern in the contemporary history. Organisms facing these threats are expected to respond by local adaptation (i.e., genetic changes or phenotypic plasticity) or by shifting their distributional range (migration). However, there are limits to their responses. For example, isolated populations will have more difficulties in developing adaptive innovations by means of genetic changes than interconnected metapopulations. Similarly, the topography of the environment can limit dispersal opportunities for crawling organisms as compared to those that rely on wind. Thus, populations of species with different life history strategy may differ in their ability to cope with changing environmental conditions. However, depending on the taxon, empirical studies investigating organisms’ responses to environmental change may become too complex, long and expensive; plus, complications arising from dealing with endangered species. In consequence, eco-evolutionary modeling offers an opportunity to overcome these limitations and complement empirical studies, understand the action and limitations of underlying mechanisms, and project into possible future scenarios. In this work I take a modeling approach and investigate the effect and relative importance of evolutionary mechanisms (including phenotypic plasticity) on the ability for local adaptation of populations with different life strategy experiencing climate change scenarios. For this, I performed a review on the state of the art of eco-evolutionary Individual-Based Models (IBMs) and identify gaps for future research. Then, I used the results from the review to develop an eco-evolutionary individual-based modeling tool to study the role of genetic and plastic mechanisms in promoting local adaption of populations of organisms with different life strategies experiencing scenarios of climate change and environmental stochasticity. The environment was simulated through a climate variable (e.g., temperature) defining a phenotypic optimum moving at a given rate of change. The rate of change was changed to simulate different scenarios of climate change (no change, slow, medium, rapid climate change). Several scenarios of stochastic noise color resembling different climatic conditions were explored. Results show that populations of sexual species will rely mainly on standing genetic variation and phenotypic plasticity for local adaptation. Population of species with relatively slow growth rate (e.g., large mammals) – especially those of small size – are the most vulnerable, particularly if their plasticity is limited (i.e., specialist species). In addition, whenever organisms from these populations are capable of adaptive plasticity, they can buffer fitness losses in reddish climatic conditions. Likewise, whenever they can adjust their plastic response (e.g., bed-hedging strategy) they will cope with bluish environmental conditions as well. In contrast, life strategies of high fecundity can rely on non-adaptive plasticity for their local adaptation to novel environmental conditions, unless the rate of change is too rapid. A recommended management measure is to guarantee interconnection of isolated populations into metapopulations, such that the supply of useful genetic variation can be increased, and, at the same time, provide them with movement opportunities to follow their preferred niche, when local adaptation becomes problematic. This is particularly important for bluish and reddish climatic conditions, when the rate of change is slow, or for any climatic condition when the level of stress (rate of change) is relatively high.
In der Dissertationsarbeit mit dem Titel „Eine Hypothese über die Grundlagen von Moral und einige Implikationen“ unternimmt die Autorin den Versuch, die anthropologischen Prämissen moralischen Handelns herauszuarbeiten. Es wird eine Hypothese aufgestellt und erläutert, die behauptet, dass moralisches Handeln nur dann verständlich wird, wenn der Handelnde erstens die Fähigkeit der Phantasie aufweist, zweitens auf Erfahrungen (mittels seines Gedächtnisses) zugreifen kann und durch Konversation mit anderen Personen interagierte und interagiert, denn nur auf der Basis dieser drei Grundlagen von Moral können sich diejenigen Fähigkeiten ent¬wickeln, die als Voraussetzungen moralischen Handeln gesehen werden müssen: Selbstbewusstsein, Freiheit, die Entwicklung eines Wir-Gefühls, die Genese eines moralischen Ideals und die Fähigkeit, sich im Entscheiden und Handeln nach diesem Ideal richten zu können. Außerdem werden in dieser Dissertation einige Implikationen dieser Hypothese auf individueller und zwischenmenschlicher Ebene diskutiert.
Electrets are dielectrics with quasi-permanent electric charge and/or dipoles, sometimes can be regarded as an electric analogy to a magnet. Since the discovery of the excellent charge retention capacity of poly(tetrafluoro ethylene) and the invention of the electret microphone, electrets have grown out of a scientific curiosity to an important application both in science and technology. The history of electret research goes hand in hand with the quest for new materials with better capacity at charge and/or dipole retention. To be useful, electrets normally have to be charged/poled to render them electro-active. This process involves electric-charge deposition and/or electric dipole orientation within the dielectrics ` surfaces and bulk. Knowledge of the spatial distribution of electric charge and/or dipole polarization after their deposition and subsequent decay is crucial in the task to improve their stability in the dielectrics.
Likewise, for dielectrics used in electrical insulation applications, there are also needs for accumulated space-charge and polarization spatial profiling. Traditionally, space-charge accumulation and large dipole polarization within insulating dielectrics is considered undesirable and harmful to the insulating dielectrics as they might cause dielectric loss and could lead to internal electric field distortion and local field enhancement. High local electric field could trigger several aging processes and reduce the insulating dielectrics' lifetime. However, with the advent of high-voltage DC transmission and high-voltage capacitor for energy storage, these are no longer the case. There are some overlapped between the two fields of electrets and electric insulation. While quasi-permanently trapped electric-charge and/or large remanent dipole polarization are the requisites for electret operation, stably trapped electric charge in electric insulation helps reduce electric charge transport and overall reduced electric conductivity. Controlled charge trapping can help in preventing further charge injection and accumulation as well as serving as field grading purpose in insulating dielectrics whereas large dipole polarization can be utilized in energy storage applications.
In this thesis, the Piezoelectrically-generated Pressure Steps (PPSs) were employed as a nondestructive method to probe the electric-charge and dipole polarization distribution in a range of thin film (several hundred micron) polymer-based materials, namely polypropylene (PP), low-density polyethylene/magnesium oxide (LDPE/MgO) nanocomposites and poly(vinylidene fluoride-co- trifluoro ethylene) (P(VDF-TrFE)) copolymer. PP film surface-treated with phosphoric acid to introduce surfacial isolated nanostructures serves as example of 2-dimensional nano-composites whereas LDPE/MgO serves as the case of 3-dimensional nano-composites with MgO nano-particles dispersed in LDPE polymer matrix. It is evidenced that the nanoparticles on the surface of acid-treated PP and in the bulk of LDPE/MgO nanocomposites improve charge trapping capacity of the respective material and prevent further charge injection and transport and that the enhanced charge trapping capacity makes PP and LDPE/MgO nanocomposites potential materials for both electret and electrical insulation applications. As for PVDF and VDF-based copolymers, the remanent spatial polarization distribution depends critically on poling method as well as specific parameters used in the respective poling method. In this work, homogeneous polarization poling of P(VDF-TrFE) copolymers with different VDF-contents have been attempted with hysteresis cyclical poling. The behaviour of remanent polarization growth and spatial polarization distribution are reported and discussed. The Piezoelectrically-generated Pressure Steps (PPSs) method has proven as a powerful method for the charge storage and transport characterization of a wide range of polymer material from nonpolar, to polar, to polymer nanocomposites category.
In den letzten Jahrzehnten fand auch in der Beschichtungsindustrie ein Umdenken hin zu umweltfreundlicheren Farben und Lacken statt. Allerdings basieren auch neue Lösungen meist nicht auf Biopolymeren und in einem noch geringeren Anteil auf wasserbasierten Beschichtungssystemen aus nachwachsenden Rohstoffen. Dies stellt den Anknüpfungspunkt dieser Arbeit dar, in der untersucht wurde, ob das Biopolymer Stärke das Potenzial zum wasserbasierten Filmbildner für Farben und Lacke besitzt. Dabei müssen angelehnt an etablierte synthetische Marktprodukte die folgenden Kriterien erfüllt werden: Die wässrige Dispersion muss mindestens einen 30%igen Feststoffgehalt haben, bei Raumtemperatur verarbeitet werden können und Viskositäten zwischen 10^2-10^3 mPa·s aufweisen. Die finale Beschichtung muss einen geschlossenen Film bilden und sehr gute Haftfestigkeiten zu einer spezifischen Oberfläche, in dieser Arbeit Glas, besitzen. Als Grundlage für die Modifizierung der Stärke wurde eine Kombination von molekularem Abbau und chemischer Funktionalisierung ausgewählt. Da nicht bekannt war, welchen Einfluss die Stärkeart, die gewählte Abbaureaktion als auch verschiedene Substituenten auf die Dispersionsherstellung und deren Eigenschaften sowie die Beschichtungseigenschaften ausüben könnten, wurden die strukturellen Parameter getrennt voneinander untersucht.
Das erste Themengebiet beinhaltete den oxidativen Abbau von Kartoffel- und Palerbsenstärke mittels des Hypochlorit-Abbaus (OCl-) und des ManOx-Abbaus (H2O2, KMnO4). Mit beiden Abbaureaktionen konnten vergleichbare gewichtsmittlere Molmassen (Mw) von 2·10^5-10^6 g/mol (GPC-MALS) hergestellt werden. Allerdings führten die gewählten Reaktionsbedingungen beim ManOx-Abbau zur Bildung von Gelpartikeln. Diese lagen im µm-Bereich (DLS und Kryo-REM-Messungen) und hatten zur Folge, dass die ManOx-Proben deutlich erhöhte Viskositäten (c: 7,5 %; 9-260 mPa·s) im Vergleich zu den OCl--Proben (4-10 mPa·s) bei scherverdünnendem Verhalten besaßen und die Eigenschaften von viskoelastischen Gelen (G‘ > G‘‘) zeigten. Des Weiteren wiesen sie reduzierte Heißwasserlöslichkeiten (95 °C, vorrangig: 70-99 %) auf. Der OCl--Abbau führte zu hydrophileren (Carboxylgruppengehalt bis zu 6,1 %; ManOx: bis zu 3,1 %), nach 95 °C-Behandlung vollständig wasserlöslichen abgebauten Stärken, die ein Newtonsches Fließverhalten mit Eigenschaften einer viskoelastischen Flüssigkeit (G‘‘ > G‘) hatten. Die OCl--Proben konnten im Vergleich zu den ManOx-Produkten (10-20 %) zu konzentrierteren Dispersionen (20-40 %) verarbeitet werden, die gleichzeitig die Einschränkung von anwendungsrelevanten Mw auf < 7·10^5 g/mol zuließen (Konzentration sollte > 30 % sein). Außerdem führten nur die OCl--Proben der Kartoffelstärke zu transparenten (alle anderen waren opak) geschlossenen Beschichtungsfilmen. Somit hebt sich die Kombination von OCl--Abbau und Kartoffelstärke mit Hinblick auf die Endanwendung ab.
Das zweite Themengebiet umfasste Untersuchungen zum Einfluss von Ester- und Hydroxyalkylether-Substituenten auf Basis einer industriell abgebauten Kartoffelstärke (Mw: 1,2·10^5 g/mol) vor allem auf die Dispersionsherstellung, die rheologischen Eigenschaften der Dispersionen und die Beschichtungseigenschaften in Kombination mit Glassubstraten. Dazu wurden Ester und Ether mit DS/MS-Werten von 0,07-0,91 synthetisiert. Die Derivate konnten zu wasserbasierten Dispersionen mit Konzentrationen von 30-45 % verarbeitet werden, wobei bei hydrophoberen Modifikaten ein Co-Lösemittel, Diethylenglycolmonobutylether (DEGBE), eingesetzt werden musste. Die Feststoffgehalte sanken dabei für beide Derivatklassen vor allem mit zunehmender Alkylkettenlänge. Die anwendungsrelevanten Viskositäten (323-1240 mPa·s) stiegen auf Grund von Wechselwirkungen tendenziell mit DS/MS und Alkylkettenlänge an. Hinsichtlich der Beschichtungseigenschaften erwiesen sich die Ester vergleichend zu den Ethern als die bevorzugte Substituentenklasse, da nur die Ester geschlossene, defektfreie und mehrheitlich transparente Beschichtungsfilme bildeten, die exzellente bis sehr gute Haftfestigkeiten (ISO Klasse: 0 und 1) auf Glas besaßen. Die Ether bildeten mehrheitlich brüchige Filme. Basierend auf der Kombination der Ergebnisse aus Lösemittelaustausch, den rheologischen Untersuchungen und zusätzlichen Oberflächenspannungsmessungen (30-61 mN/m) konnte geschlossen werden, dass wahrscheinlich fehlende oder schlechte Haftfestigkeiten vorrangig akkumuliertem Wasser in den Beschichtungsfilmen (visuell: trüb oder weiß) geschuldet sind, während die Brüchigkeit vermutlich auf Wechselwirkungen (H-Brücken Wechselwirkungen, hydrophobe Wechselwirkungen) zwischen den Polymeren zurückgeführt werden kann.
Insgesamt scheint die Kombination aus Kartoffelstärke basierend auf dem OCl--Abbau mit Mw < 7·10^5 g/mol und einem Estersubstituenten eine gute Wahl für wasserbasierte Dispersionen mit hohen Feststoffkonzentrationen (> 30 %), guter Filmbildung und exzellenten Haftungen auf Glas zu sein.
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.
Im Rahmen dieser Arbeit wird anhand von neuartigen Materialien das Potential der Europium-Lumineszenz für die strukturelle Analyse dargestellt. Bei diesen Materialien handelt es sich zum einen um Nanopartikel mit Matrizes aus mehreren Metall-Mischoxiden und Dotierungen durch die Sonde Europium und zum anderen um Metallorganische Netzwerke (MOFs), die mit Neodym , Samarium- und Europium-Ionen beladen sind.
Die Synthese der aus der Kombination von Metalloxiden enthaltenen Nanopartikel ist unter milden Bedingungen mithilfe von speziell dafür hergestellten Reagenzien erfolgt und hat zu sehr kleinen, amorphen Nanopartikeln geführt. Durch eine nachfolgende Temperaturbehandlung hat sich die Kristallinität erhöht. Damit verbunden haben sich auch die Kristallstruktur sowie die Position des Dotanden Europium verändert.
Während die etablierte Methode der Röntgendiffraktometrie einen Blick auf das Kristallgitter als Gesamtes ermöglicht, so trifft die Lumineszenz des Europiums durch die Sichtbarkeit einzelner Stark-Aufspaltungen Aussagen über dessen lokale Symmetrien. Die Symmetrie wird durch Sauerstofffehlstellen verändert, welche die Sauerstoffleitfähigkeit der Nanopartikel beeinflussen. Diese ist für die Anwendung als Katalysatoren in industriellen Prozessen und ebenso als Sensoren und Therapeutika in biologischen Systemen von Bedeutung.
Zur ersten katalytischen Charakterisierung werden die Proben mittels Temperatur-programmierter Reduktion untersucht. Des Weiteren werden die Mischoxid-Nanopartikel auch hinsichtlich ihrer Verwendbarkeit als Matrix in Aufkonversionsprozessen untersucht.
Die Metallorganischen Netzwerke eignen sich aufgrund ihrer mikroporösen Struktur für Anwendungen in der Speicherung gleichermaßen von Nutzgasen wie auch von Schadstoffen. Ebenfalls ist eine biologische Anwendung denkbar, die insbesondere den Bereich der drug delivery-Reagenzien betrifft.
Erfolgt in die mikroporösen Strukturen der Metallorganischen Netzwerke die Einlagerung von Lanthanoid-Ionen, so können diese bei der entsprechenden Kombination als Weißlicht-Emittierer fungieren. Dabei ist neben den Verhältnissen zwischen den Lanthanoid-Ionen auch die genaue Position innerhalb des Netzwerks sowie die Distanz zu anderen Ionen von Interesse. Zur Untersuchung dieser Fragestellungen wird die Umgebungssensitivität der Europium-Lumineszenz ausgenutzt. Die auf diese Weise festgestellte Formiat-Bildung hängt von zahlreichen Parametern ab.
Insgesamt stellt sich die im Rahmen dieser Arbeit verwendete Methodik des Einsatzes von Europium als strukturelle Sonde in höchstem Maße vielseitig dar und zeigt seine größte Stärke in der Kombination mit weiteren Methoden der Strukturanalytik. Die auf diese Weise genauestens charakterisierten neuartigen Materialien können nun gezielt und anwendungsfokussiert weiterentwickelt werden.
Business process management (BPM) deals with modeling, executing, monitoring, analyzing, and improving business processes. During execution, the process communicates with its environment to get relevant contextual information represented as events. Recent development of big data and the Internet of Things (IoT) enables sources like smart devices and sensors to generate tons of events which can be filtered, grouped, and composed to trigger and drive business processes.
The industry standard Business Process Model and Notation (BPMN) provides several event constructs to capture the interaction possibilities between a process and its environment, e.g., to instantiate a process, to abort an ongoing activity in an exceptional situation, to take decisions based on the information carried by the events, as well as to choose among the alternative paths for further process execution. The specifications of such interactions are termed as event handling. However, in a distributed setup, the event sources are most often unaware of the status of process execution and therefore, an event is produced irrespective of the process being ready to consume it. BPMN semantics does not support such scenarios and thus increases the chance of processes getting delayed or getting in a deadlock by missing out on event occurrences which might still be relevant.
The work in this thesis reviews the challenges and shortcomings of integrating real-world events into business processes, especially the subscription management. The basic integration is achieved with an architecture consisting of a process modeler, a process engine, and an event processing platform. Further, points of subscription and unsubscription along the process execution timeline are defined for different BPMN event constructs. Semantic and temporal dependencies among event subscription, event occurrence, event consumption and event unsubscription are considered. To this end, an event buffer with policies for updating the buffer, retrieving the most suitable event for the current process instance, and reusing the event has been discussed that supports issuing of early subscription.
The Petri net mapping of the event handling model provides our approach with a translation of semantics from a business process perspective. Two applications based on this formal foundation are presented to support the significance of different event handling configurations on correct process execution and reachability of a process path. Prototype implementations of the approaches show that realizing flexible event handling is feasible with minor extensions of off-the-shelf process engines and event platforms.
Increasing concerns regarding the environmental impact of our chemical production have shifted attention towards possibilities for sustainable biotechnology. One-carbon (C1) compounds, including methane, methanol, formate and CO, are promising feedstocks for future bioindustry. CO2 is another interesting feedstock, as it can also be transformed using renewable energy to other C1 feedstocks for use. While formaldehyde is not suitable as a feedstock due to its high toxicity, it is a central intermediate in the process of C1 assimilation. This thesis explores formaldehyde metabolism and aims to engineer formaldehyde assimilation in the model organism Escherichia coli for the future C1-based bioindustry.
The first chapter of the thesis aims to establish growth of E. coli on formaldehyde via the most efficient naturally occurring route, the ribulose monophosphate pathway. Linear variants of the pathway were constructed in multiple-gene knockouts strains, coupling E. coli growth to the activities of the key enzymes of the pathway. Formaldehyde-dependent growth was achieved in rationally designed strains. In the final strain, the synthetic pathway provides the cell with almost all biomass and energy requirements.
In the second chapter, taking advantage of the unique feature of its reactivity, formaldehyde assimilation via condensation with glycine and pyruvate by two promiscuous aldolases was explored. Facilitated by these two reactions, the newly designed homoserine cycle is expected to support higher yields of a wide array of products than its counterparts. By dividing the pathway into segments and coupling them to the growth of dedicated strains, all pathway reactions were demonstrated to be sufficiently active. The work paves a way for future implementation of a highly efficient route for C1 feedstocks into commodity chemicals.
In the third chapter, the in vivo rate of the spontaneous formaldehyde tetrahydrofolate condensation to methylene-tetrahydrofolate was assessed in order to evaluate its applicability as a biotechnological process. Tested within an E. coli strain deleted in essential genes for native methylene-tetrahydrofolate biosynthesis, the reaction was shown to support the production of this essential intermediate. However, only low growth rates were observed and only at high formaldehyde concentrations. Computational analysis dependent on in vivo evidence from this strain deduced the slow rate of this spontaneous reaction, thus ruling out its substantial contribution to growth on C1 feedstocks.
The reactivity of formaldehyde makes it highly toxic. In the last chapter, the formation of thioproline, the condensation product of cysteine and formaldehyde, was confirmed to contribute this toxicity effect. Xaa-Pro aminopeptidase (PepP), which genetically links with folate metabolism, was shown to hydrolyze thioproline-containing peptides. Deleting pepP increased strain sensitivity to formaldehyde, pointing towards the toxicity of thioproline-containing peptides and the importance of their removal. The characterization in this study could be useful in handling this toxic intermediate.
Overall, this thesis identified challenges related to formaldehyde metabolism and provided novel solutions towards a future bioindustry based on sustainable C1 feedstocks in which formaldehyde serves as a key intermediate.
Ficción herética
(2019)
La metáfora de la «isla» en la narrativa cubana contemporánea engloba toda una serie de complejidades simbólicas dependientes de la vivencia del espacio y el tiempo. Su potencial visual se manifiesta u oculta las propias vivencias insulares de los escritores cubanos. En los últimos 30 años en Cuba, los fenómenos políticos económicos y sociales han modificado categóricamente la percepción y la configuración del plano social e individual frente a las exigencias globales (Fornet 2006, Rojas 1999, 2002, 2006). Se ha confirmado una sensación de acinesia e ingravidez (Casamayor 2013) y se ha presentado una actitud «herética» por parte de los narradores cubanos, quienes se confrontan con las ideas de la postmodernidad, lo postsoviético o postutópico, reafirmando así una sensibilidad presentista (Guerrero 2016). Estos autores presentan resonancias y reivindicaciones de los imaginarios insulares de autores y de tradiciones estéticas dentro y fuera de la isla como José Lezama Lima, Virgilio Piñera, Guillermo Cabrera Infante, Reinaldo Arenas y Severo Sarduy). El análisis de las écfrasis insulares permite examinar las dinámicas de representación y de sentido: disimulación: la disimulación, la anamorfosis y la trompe l’oeil (Sarduy 1981). La novela Tuyo es el reino (1998) de Abilio Estévez es un modelo desde el que se localizará las relaciones de sentido entre canon literario y los referentes socioculturales de las variaciones somatopológicas de la isla en la narrativa cubana actual: Ena Lucía Portela, Atilio Caballero, Antonio José Ponte, Daniel Díaz Mantilla, Emerio Medina, Orlando Luis Pardo, Anisley Negrin y Ahmel Echeverría, entre otros.
Die funktionelle Charakterisierung von therapeutisch relevanten Proteinen kann bereits durch die Bereitstellung des Zielproteins in adäquaten Mengen limitierend sein. Dies trifft besonders auf Membranproteine zu, die aufgrund von zytotoxischen Effekten auf die Produktionszelllinie und der Tendenz Aggregate zu bilden, in niedrigen Ausbeuten an aktivem Protein resultieren können. Der lebende Organismus kann durch die Verwendung von translationsaktiven Zelllysaten umgangen werden- die Grundlage der zellfreien Proteinsynthese. Zu Beginn der Arbeit wurde die ATP-abhängige Translation eines Lysates auf der Basis von kultivierten Insektenzellen (Sf21) analysiert. Für diesen Zweck wurde ein ATP-bindendes Aptamer eingesetzt, durch welches die Translation der Nanoluziferase reguliert werden konnte. Durch die dargestellte Applizierung von Aptameren, könnten diese zukünftig in zellfreien Systemen für die Visualisierung der Transkription und Translation eingesetzt werden, wodurch zum Beispiel komplexe Prozesse validiert werden können.
Neben der reinen Proteinherstellung können Faktoren wie posttranslationale Modifikationen sowie eine Integration in eine lipidische Membran essentiell für die Funktionalität des Membranproteins sein. Im zweiten Abschnitt konnte, im zellfreien Sf21-System, für den G-Protein-gekoppelten Rezeptor Endothelin B sowohl eine Integration in die endogen vorhandenen Endoplasmatisch Retikulum-basierten Membranstrukturen als auch Glykosylierungen, identifiziert werden.
Auf der Grundlage der erfolgreichen Synthese des ET-B-Rezeptors wurden verschiedene Methoden zur Fluoreszenzmarkierung des Adenosin-Rezeptors A2a (Adora2a) angewandt und optimiert. Im dritten Abschnitt wurde der Adora2a mit Hilfe einer vorbeladenen tRNA, welche an eine fluoreszierende Aminosäure gekoppelt war, im zellfreien Chinesischen Zwerghamster Ovarien (CHO)-System markiert. Zusätzlich konnte durch den Einsatz eines modifizierten tRNA/Aminoacyl-tRNA-Synthetase-Paares eine nicht-kanonische Aminosäure an Position eines integrierten Amber-Stopcodon in die Polypeptidkette eingebaut und die funktionelle Gruppe im Anschluss an einen Fluoreszenzfarbstoff gekoppelt werden. Aufgrund des offenen Charakters eignen sich zellfreie Proteinsynthesesysteme besonders für eine Integration von exogenen Komponenten in den Translationsprozess. Mit Hilfe der Fluoreszenzmarkierung wurde eine ligandvermittelte Konformationsänderung im Adora2a über einen Biolumineszenz-Resonanzenergietransfer detektiert. Durch die Etablierung der Amber-Suppression wurde darüber hinaus das Hormon Erythropoetin pegyliert, wodurch Eigenschaften wie Stabilität und Halbwertszeit des Proteins verändert wurden.
Zu guter Letzt wurde ein neues tRNA/Aminoacyl-tRNA-Synthetase-Paar auf Basis der Methanosarcina mazei Pyrrolysin-Synthetase etabliert, um das Repertoire an nicht-kanonischen Aminosäuren und den damit verbundenen Kopplungsreaktionen zu erweitern. Zusammenfassend wurden die Potenziale zellfreier Systeme in Bezug auf der Herstellung von komplexen Membranproteinen und der Charakterisierung dieser durch die Einbringung einer positionsspezifischen Fluoreszenzmarkierung verdeutlicht, wodurch neue Möglichkeiten für die Analyse und Funktionalisierung von komplexen Proteinen geschaffen wurden.
For millennia, humans have affected landscapes all over the world. Due to horizontal expansion, agriculture plays a major role in the process of fragmentation. This process is caused by a substitution of natural habitats by agricultural land leading to agricultural landscapes. These landscapes are characterized by an alternation of agriculture and other land use like forests. In addition, there are landscape elements of natural origin like small water bodies. Areas of different land use are beside each other like patches, or fragments. They are physically distinguishable which makes them look like a patchwork from an aerial perspective. These fragments are each an own ecosystem with conditions and properties that differ from their adjacent fragments. As open systems, they are in exchange of information, matter and energy across their boundaries. These boundary areas are called transition zones. Here, the habitat properties and environmental conditions are altered compared to the interior of the fragments. This changes the abundance and the composition of species in the transition zones, which in turn has a feedback effect on the environmental conditions.
The literature mainly offers information and insights on species abundance and composition in forested transition zones. Abiotic effects, the gradual changes in energy and matter, received less attention. In addition, little is known about non-forested transition zones. For example, the effects on agricultural yield in transition zones of an altered microclimate, matter dynamics or different light regimes are hardly researched or understood. The processes in transition zones are closely connected with altered provisioning and regulating ecosystem services. To disentangle the mechanisms and to upscale the effects, models can be used.
My thesis provides insights into these topics: literature was reviewed and a conceptual framework for the quantitative description of gradients of matter and energy in transition zones was introduced. The results of measurements of environmental gradients like microclimate, aboveground biomass and soil carbon and nitrogen content are presented that span from within the forest into arable land. Both the measurements and the literature review could not validate a transition zone of 100 m for abiotic effects. Although this value is often reported and used in the literature, it is likely to be smaller.
Further, the measurements suggest that on the one hand trees in transition zones are smaller compared to those in the interior of the fragments, while on the other hand less biomass was measured in the arable lands’ transition zone. These results support the hypothesis that less carbon is stored in the aboveground biomass in transition zones. The soil at the edge (zero line) between adjacent forest and arable land contains more nitrogen and carbon content compared to the interior of the fragments. One-year measurements in the transition zone also provided evidence that microclimate is different compared to the fragments’ interior.
To predict the possible yield decreases that transition zones might cause, a modelling approach was developed. Using a small virtual landscape, I modelled the effect of a forest fragment shading the adjacent arable land and the effects of this on yield using the MONICA crop growth model. In the transition zone yield was less compared to the interior due to shading. The results of the simulations were upscaled to the landscape level and exemplarily calculated for the arable land of a whole region in Brandenburg, Germany.
The major findings of my thesis are: (1) Transition zones are likely to be much smaller than assumed in the scientific literature; (2) transition zones aren’t solely a phenomenon of forested ecosystems, but significantly extend into arable land as well; (3) empirical and modelling results show that transition zones encompass biotic and abiotic changes that are likely to be important to a variety of agricultural landscape ecosystem services.
Species assembly from a regional pool into local metacommunities and how they colonize and coexist over time and space is essential to understand how communities response to their environment including abiotic and biotic factors. In highly disturbed landscapes, connectivity of isolated habitat patches is essential to maintain biodiversity and the entire ecosystem functioning. In northeast Germany, a high density of the small water bodies called kettle holes, are good systems to study metacommunities due to their condition as “aquatic islands” suitable for hygrophilous species that are surrounded by in unsuitable matrix of crop fields. The main objective of this thesis was to infer the main ecological processes shaping plant communities and their response to the environment, from biodiversity patterns and key life-history traits involved in connectivity using ecological and genetic approaches; and to provide first insights of the role of kettle holes harboring wild-bee species as important mobile linkers connecting plant communities in this insular system.
t a community level, I compared plant diversity patterns and trait composition in ephemeral vs. permanent kettle holes). My results showed that types of kettle holes act as environmental filers shaping plant diversity, community-composition and trait-distribution, suggesting species sorting and niche processes in both types of kettle holes. At a population level, I further analyzed the role of dispersal and reproductive strategies of four selected species occurring in permanent kettle holes. Using microsatellites, I found that breeding system (degree of clonality), is the main factor shaping genetic diversity and genetic divergence. Although, higher gene flow and lower genetic differentiation among populations in wind vs. insect pollinated species was also found, suggesting that dispersal mechanisms played a role related to gene flow and connectivity. For most flowering plants, pollinators play an important role connecting communities. Therefore, as a first insight of the potential mobile linkers of these plant communities, I investigated the diversity wild-bees occurring in these kettle holes. My main results showed that local habitat quality (flower resources) had a positive effect on bee diversity, while habitat heterogeneity (number of natural landscape elements surrounding kettle holes 100–300m), was negatively correlated.
This thesis covers from genetic flow at individual and population level to plant community assembly. My results showed how patterns of biodiversity, dispersal and reproduction strategies in plant population and communities can be used to infer ecological processes. In addition, I showed the importance of life-history traits and the relationship between species and their abiotic and biotic interactions. Furthermore, I included a different level of mobile linkers (pollinators) for a better understanding of another level of the system. This integration is essential to understand how communities respond to their surrounding environment and how disturbances such as agriculture, land-use and climate change might affect them. I highlight the need to integrate many scientific areas covering from genes to ecosystems at different spatiotemporal scales for a better understanding, management and conservation of our ecosystems.
Aluminum oxide is an Earth-abundant geological material, and its interaction with water is of crucial importance for geochemical and environmental processes. Some aluminum oxide surfaces are also known to be useful in heterogeneous catalysis, while the surface chemistry of aqueous oxide interfaces determines the corrosion, growth and dissolution of such materials. In this doctoral work, we looked mainly at the (0001) surface of α-Al 2 O 3 and its reactivity towards water. In particular, a great focus of this work is dedicated to simulate and address the vibrational spectra of water adsorbed on the α-alumina(0001) surface in various conditions and at different coverages. In fact, the main source of comparison and inspiration for this work comes from the collaboration with the “Interfacial Molecular Spectroscopy” group led by Dr. R. Kramer Campen at the Fritz-Haber Institute of the MPG in Berlin. The expertise of our project partners in surface-sensitive Vibrational Sum Frequency (VSF) generation spectroscopy was crucial to develop and adapt specific simulation schemes used in this work. Methodologically, the main approach employed in this thesis is Ab Initio Molecular Dynamics (AIMD) based on periodic Density Functional Theory (DFT) using the PBE functional with D2 dispersion correction. The analysis of vibrational frequencies from both a static and a dynamic, finite-temperature perspective offers the ability to investigate the water / aluminum oxide interface in close connection to experiment.
The first project presented in this work considers the characterization of dissociatively adsorbed deuterated water on the Al-terminated (0001) surface. This particular structure is known from both experiment and theory to be the thermodynamically most stable surface termination of α-alumina in Ultra-High Vacuum (UHV) conditions. Based on experiments performed by our colleagues at FHI, different adsorption sites and products have been proposed and identified for D 2 O. While previous theoretical investigations only looked at vibrational frequencies of dissociated OD groups by staticNormal Modes Analysis (NMA), we rather employed a more sophisticated approach to directly assess vibrational spectra (like IR and VSF) at finite temperature from AIMD. In this work, we have employed a recent implementation which makes use of velocity-velocity autocorrelation functions to simulate such spectral responses of O-H(D) bonds. This approach allows for an efficient and qualitatively accurate estimation of Vibrational Densities of States (VDOS) as well as IR and VSF spectra, which are then tested against experimental spectra from our collaborators.
In order to extend previous work on unimolecularly dissociated water on α-Al 2 O 3 , we then considered a different system, namely, a fully hydroxylated (0001) surface, which results from the reconstruction of the UHV-stable Al-terminated surface at high water contents. This model is then further extended by considering a hydroxylated surface with additional water molecules, forming a two-dimensional layer which serves as a potential template to simulate an aqueous interface in environmental conditions. Again, employing finite-temperature AIMD trajectories at the PBE+D2 level, we investigated the behaviour of both hydroxylated surface (HS) and the water-covered structure derived from it (known as HS+2ML). A full range of spectra, from VDOS to IR and VSF, is then calculated using the same methodology, as described above. This is the main focus of the second project, reported in Chapter 5. In this case, comparison between theoretical spectra and experimental data is definitely good. In particular, we underline the nature of high-frequency resonances observed above 3700 cm −1 in VSF experiments to be associated with surface OH-groups, known as “aluminols” which are a key fingerprint of the fully hydroxylated surface.
In the third and last project, which is presented in Chapter 6, the extension of VSF spectroscopy experiments to the time-resolved regime offered us the opportunity to investigate vibrational energy relaxation at the α-alumina / water interface. Specifically, using again DFT-based AIMD simulations, we simulated vibrational lifetimes for surface aluminols as experimentally detected via pump-probe VSF. We considered the water-covered HS model as a potential candidate to address this problem. The vibrational (IR) excitation and subsequent relaxation is performed by means of a non-equilibrium molecular dynamics scheme. In such a scheme, we specifically looked at the O-H stretching mode of surface aluminols. Afterwards, the analysis of non-equilibrium trajectories allows for an estimation of relaxation times in the order of 2-4 ps which are in overall agreement with measured ones.
The aim of this work has been to provide, within a consistent theoretical framework, a better understanding of vibrational spectroscopy and dynamics for water on the α-alumina(0001) surface,ranging from very low water coverage (similar to the UHV case) up to medium-high coverages, resembling the hydroxylated oxide in environmental moist conditions.
The present work is a compilation of three original research articles submitted (or already published) in international peer-reviewed venues of the field of speech science. These three articles address the topics of fundamental motor laws in speech and dynamics of corresponding speech movements:
1. Kuberski, Stephan R. and Adamantios I. Gafos (2019). "The speed-curvature power law in tongue movements of repetitive speech". PLOS ONE 14(3). Public Library of Science. doi: 10.1371/journal.pone.0213851.
2. Kuberski, Stephan R. and Adamantios I. Gafos (In press). "Fitts' law in tongue movements of repetitive speech". Phonetica: International Journal of Phonetic Science. Karger Publishers. doi: 10.1159/000501644
3. Kuberski, Stephan R. and Adamantios I. Gafos (submitted). "Distinct phase space topologies of identical phonemic sequences". Language. Linguistic Society of America.
The present work introduces a metronome-driven speech elicitation paradigm in which participants were asked to utter repetitive sequences of elementary consonant-vowel syllables. This paradigm, explicitly designed to cover speech rates from a substantially wider range than has been explored so far in previous work, is demonstrated to satisfy the important prerequisites for assessing so far difficult to access aspects of speech. Specifically, the paradigm's extensive speech rate manipulation enabled elicitation of a great range of movement speeds as well as movement durations and excursions of the relevant effectors. The presence of such variation is a prerequisite to assessing whether invariant relations between these and other parameters exist and thus provides the foundation for a rigorous evaluation of the two laws examined in the first two contributions of this work.
In the data resulting from this paradigm, it is shown that speech movements obey the same fundamental laws as movements from other domains of motor control do. In particular, it is demonstrated that speech strongly adheres to the power law relation between speed and curvature of movement with a clear speech rate dependency of the power law's exponent. The often-sought or reported exponent of one third in the statement of the law is unique to a subclass of movements which corresponds to the range of faster rates under which a particular utterance is produced. For slower rates, significantly larger values than one third are observed. Furthermore, for the first time in speech this work uncovers evidence for the presence of Fitts' law. It is shown that, beyond a speaker-specific speech rate, speech movements of the tongue clearly obey Fitts' law by emergence of its characteristic linear relation between movement time and index of difficulty. For slower speech rates (when temporal pressure is small), no such relation is observed. The methods and datasets obtained in the two assessment above provide a rigorous foundation both for addressing implications for theories and models of speech as well as for better understanding the status of speech movements in the context of human movements in general.
All modern theories of language rely on a fundamental segmental hypothesis according to which the phonological message of an utterance is represented by a sequence of segments or phonemes. It is commonly assumed that each of these phonemes can be mapped to some unit of speech motor action, a so-called speech gesture.
For the first time here, it is demonstrated that the relation between the phonological description of simple utterances and the corresponding speech motor action is non-unique. Specifically, by the extensive speech rate manipulation in the herein used experimental paradigm it is demonstrated that speech exhibits clearly distinct dynamical organizations underlying the production of simple utterances. At slower speech rates, the dynamical organization underlying the repetitive production of elementary /CV/ syllables can be described by successive concatenations of closing and opening gestures, each with its own equilibrium point. As speech rate increases, the equilibria of opening and closing gestures are not equally stable yielding qualitatively different modes of organization with either a single equilibrium point of a combined opening-closing gesture or a periodic attractor unleashed by the disappearance of both equilibria. This observation, the non-uniqueness of the dynamical organization underlying what on the surface appear to be identical phonemic sequences, is an entirely new result in the domain of speech. Beyond that, the demonstration of periodic attractors in speech reveals that dynamical equilibrium point models do not account for all possible modes of speech motor behavior.
Seit 2003 hat sich das politische Bild des Irak stark verändert. Dadurch begann der Prozess der Neugestaltung der irakischen Rechtsordnung. Die irakische Verfassung von 2005 legt erstmalig in der Geschichte des Irak den Islam und die Demokratie als zwei nebeneinander zu beachtende Grundprinzipien bei der Gesetzgebung fest. Trotz dieser signifikanten Veränderung im irakischen Rechtssystem und erheblicher Entwicklungen im internationalen Privat- und Zivilverfahrensrecht (IPR/IZVR) im internationalen Vergleich gilt die hauptsächlich im irakischen Zivilgesetzbuch (ZGB) von 1951 enthaltene gesetzliche Regelung des IPR/IZVR im Irak weiterhin. Deshalb entstand diese Arbeit für eine Reformierung des irakischen IPR/IZVR.
Die Arbeit gilt als erste umfassende wissenschaftliche Untersuchung, die sich mit dem jetzigen Inhalt und der zukünftigen Reformierung des irakischen internationalen Privatrecht- und Zivilverfahrensrechts (IPR/IZVR) beschäftigt.
Die Verfasserin vermittelt einen Gesamtüberblick über das jetzt geltende irakische internationale Privat- und Zivilverfahrensrecht mit gelegentlicher punktueller und stichwortartiger Heranziehung des deutschen, islamischen, türkischen und tunesischen Rechts, zeigt dessen Schwachstellen auf und unterbreitet entsprechende Reformvorschläge.
Wegen der besonderen Bedeutung des internationalen Vertragsrechts für die Wirtschaft im Irak und auch zum Teil für Deutschland gibt die Verfasserin einen genaueren Überblick über das irakische internationale Vertragsrecht und bekräftigt gleichzeitig dessen Reformbedürftigkeit.
Die Darstellung der wichtigen Entwicklungen im deutsch-europäischen, im traditionellen islamischen Recht und im türkischen und tunesischen internationalen Privat- und Zivilverfahrensrecht im zweiten Kapitel dienen als Grundlage, auf die bei der Reformierung des irakischen IPR/ IZVR zurück gegriffen werden kann. Da die Kenntnisse des islamischen Rechts nicht zwingend zum Rechtsstudium gehören, wird das islamische Recht dazu in Bezug auf seine Entstehung und die Rechtsquellen dargestellt.
Am Ende der Arbeit wird ein Entwurf eines föderalen Gesetzes zum internationalen Privatrecht im Irak katalogisiert, der sich im Rahmen der irakischen Verfassung gleichzeitig mit dem Islam und der Demokratie vereinbaren lässt.
Floral scent is an important way for plants to communicate with insects, but scent emission has been lost or strongly reduced during the transition from pollinator-mediated outbreeding to selfing. The shift from outcrossing to selfing is not only accompanied by scent loss, but also by a reduction in other pollinator-attracting traits like petal size and can be observed multiple times among angiosperms. These changes are summarized by the term selfing syndrome and represent one of the most prominent examples of convergent evolution within the plant kingdom. In this work the genus Capsella was used as a model to study convergent evolution in two closely related selfers with separate transitions to self-fertilization.
Compared to their outbreeding ancestor C. grandiflora, the emission of benzaldehyde as main compound of floral scent is lacking or strongly reduced in the selfing species C. rubella and C. orientalis. In C. rubella the loss of benzaldehyde was caused by mutations to cinnamate:CoA ligase CNL1, but the biochemical basis and evolutionary history of this loss remained unknown, together with the genetic basis of scent loss in C. orientalis. Here, a combination of plant transformations, in vitro enzyme assays, population genetics and quantitative genetics has been used to address these questions. The results indicate that CNL1 has been inactivated twice independently by point mutations in C. rubella, leading to a loss of benzaldehyde emission. Both inactivated haplotypes can be found around the Mediterranean Sea, indicating that they arose before the species´ geographical spread. This study confirmed CNL1 as a hotspot for mutations to eliminate benzaldehyde emission, as it has been suggested by previous studies. In contrast to these findings, CNL1 in C. orientalis remains active. To test whether similar mechanisms underlie the convergent evolution of scent loss in C. orientalis a QTL mapping approach was used and the results suggest that this closely related species followed a different evolutionary route to reduce floral scent, possibly reflecting that the convergent evolution of floral scent is driven by ecological rather than genetic factors.
In parallel with studying the genetic basis of repeated scent loss a method for testing the adaptive value of individual selfing syndrome traits was established. The established method allows estimating outcrossing rates with a high throughput of samples and detects successfully insect-mediated outcrossing events, providing major advantages regarding time and effort compared to other approaches. It can be applied to correlate outcrossing rates with differences in individual traits by using quasi-isogenic lines as demonstrated here or with environmental or morphological parameters.
Convergent evolution can not only be observed for scent loss in Capsella but also for the morphological evolution of petal size. Previous studies detected several QTLs underlying the petal size reduction in C. orientalis and C. rubella, some of them shared among both species. One shared QTL is PAQTL1 which might map to NUBBIN, a growth factor. To better understand the morphological evolution and genetic basis of petal size reduction, this QTL was studied. Mapping this QTL to a gene might identify another example for a hotspot gene, in this case for the convergent evolution of petal size.
Quantum field theory on curved spacetimes is understood as a semiclassical approximation of some quantum theory of gravitation, which models a quantum field under the influence of a classical gravitational field, that is, a curved spacetime. The most remarkable effect predicted by this approach is the creation of particles by the spacetime itself, represented, for instance, by Hawking's evaporation of black holes or the Unruh effect. On the other hand, these aspects already suggest that certain cornerstones of Minkowski quantum field theory, more precisely a preferred vacuum state and, consequently, the concept of particles, do not have sensible counterparts within a theory on general curved spacetimes. Likewise, the implementation of covariance in the model has to be reconsidered, as curved spacetimes usually lack any non-trivial global symmetry. Whereas this latter issue has been resolved by introducing the paradigm of locally covariant quantum field theory (LCQFT), the absence of a reasonable concept for distinct vacuum and particle states on general curved spacetimes has become manifest even in the form of no-go-theorems.
Within the framework of algebraic quantum field theory, one first introduces observables, while states enter the game only afterwards by assigning expectation values to them. Even though the construction of observables is based on physically motivated concepts, there is still a vast number of possible states, and many of them are not reasonable from a physical point of view. We infer that this notion is still too general, that is, further physical constraints are required. For instance, when dealing with a free quantum field theory driven by a linear field equation, it is natural to focus on so-called quasifree states. Furthermore, a suitable renormalization procedure for products of field operators is vitally important. This particularly concerns the expectation values of the energy momentum tensor, which correspond to distributional bisolutions of the field equation on the curved spacetime. J. Hadamard's theory of hyperbolic equations provides a certain class of bisolutions with fixed singular part, which therefore allow for an appropriate renormalization scheme.
By now, this specification of the singularity structure is known as the Hadamard condition and widely accepted as the natural generalization of the spectral condition of flat quantum field theory. Moreover, due to Radzikowski's celebrated results, it is equivalent to a local condition, namely on the wave front set of the bisolution. This formulation made the powerful tools of microlocal analysis, developed by Duistermaat and Hörmander, available for the verification of the Hadamard property as well as the construction of corresponding Hadamard states, which initiated much progress in this field. However, although indispensable for the investigation in the characteristics of operators and their parametrices, microlocal analyis is not practicable for the study of their non-singular features and central results are typically stated only up to smooth objects. Consequently, Radzikowski's work almost directly led to existence results and, moreover, a concrete pattern for the construction of Hadamard bidistributions via a Hadamard series. Nevertheless, the remaining properties (bisolution, causality, positivity) are ensured only modulo smooth functions.
It is the subject of this thesis to complete this construction for linear and formally self-adjoint wave operators acting on sections in a vector bundle over a globally hyperbolic Lorentzian manifold. Based on Wightman's solution of d'Alembert's equation on Minkowski space and the construction for the advanced and retarded fundamental solution, we set up a Hadamard series for local parametrices and derive global bisolutions from them. These are of Hadamard form and we show existence of smooth bisections such that the sum also satisfies the remaining properties exactly.
Die vorliegende Dissertation zielt generell darauf ab, die Anwendung der dialektischen Methodologie auf den Bereich der Sprachphilosophie zu rechtfertigen und eine systematische Bearbeitung eines begrenzten Teils der Sprachphilosophie mithilfe der Dialektik durchzuführen. Um diese Herangehensweise, die in der Forschung kaum oder gar nicht vertreten ist, aufzuklären und festzustellen, werde ich zuerst auf die philosophischen Überlegungen von zwei Autoren zurückgreifen: Hegel und Wittgenstein.
Hegel und Wittgenstein sind, auf den ersten Blick, Autoren, die kaum Gemeinsamkeiten haben, außer dass sie sich beide mit der Philosophie als Fach beschäftigt und unvermeidlich ein gemeinschaftliches Thema, die Sprache, behandelt haben, wobei jedoch weder eine inhaltliche noch eine methodologische Verbindung hervorgehoben werden könnte. Die erste Voraussetzung dieser Dissertation, in Bezug auf die Geschichte der Idee, besteht darin, darauf hinzudeuten, dass der hegelsche Geistesbegriff und Wittgensteins Lebensform zwei Ansätze und Resultat einer philosophischen Bemühung sind, die gemeinsam die notwendige Auflösung bzw. Überwindung skeptischer Argumentation vornehmen. Tatsächlich hat Wittgenstein in seinen Philosophischen Untersuchungen eine Argumentation entwickelt, die als „Paradox des Regelfolgens“ bezeichnet und in der sekundären Literatur (hauptsächlich bei Kripke) als eine Art skeptische Argumentation betrachtet wurde. Demnach wird Wittgensteins Theorie der Sprache entweder als eine Auflösung dieses Skeptizismus oder einfach als ein skeptischer Text selbst ausgelegt (Brandom). Das erste Ziel meiner Dissertation besteht darin, zu zeigen, dass dieses Paradox als skeptische Argumentation allerdings unvollständig geblieben ist dass dieses Paradox als der erster entscheidender Moment zu der höchsten Form der skeptischen Herausforderung, der Antinomie, betrachtet werden kann. Eine vollständige skeptische Argumentation heißt, dass die alleinige Auflösung des Paradoxes, der Dispositionalismus und die Negation dieser Theorie, beide beweisbar sind. Ich werde also versuchen, aus der in den PU dargestellten Auflösung des Paradoxes des Regelfolgens die Vervollständigung einer Antinomie des Begriffes der Normativität in Bezug auf die Sprachregeln festzulegen, ähnlich der von Kant entwickelten kosmologischen Antinomie (Thesis cum Antithesis). Das zweite Ziel meiner Dissertation besteht folglich darin, zu zeigen, 1. dass die kantische Auflösung der Antinomie unwirksam bezüglich der Antinomie der Normativität ist, 2. dass diese Antinomie eine notwendige Auseinandersetzung mit einem radikalen Skeptizismus bedeutet und dass wir logisch gezwungen sind, nicht nur irgendeine Theorie der Sprachphilosophie neu zu bestimmen, sondern unsere Methodologie – das heißt die Anwendung der üblichen Normen der Rationalität – selbst grundsätzlich tiefer gehend in Frage zu stellen, und 3. dass die hegelsche Dialektik sich als die methodologische Auflösung einer solchen radikalen skeptischen Herausforderung bzw. als die Auflösung einer Antinomie überhaupt ergibt. Anlässlich dieser methodologischen Revidierung wird auf die hegelsche Dialektik zurückgegriffen.
Dennoch begrenzt sich der Zweck dieser Dissertation nicht darauf, eine Interpretation von Hegels Dialektik oder eine Überwindung von Wittgensteins Lebensform darzustellen, vielmehr geht es darum, auf die Problematik und die Grundsätze des Begriffs der Lebensform bzw. des theoretischen Geistes zurückzugreifen und kraft Hegels Dialektik darüber hinauszuführen, um den Platz und die Funktion der Sprache besser zu verstehen. Diese Arbeit erfolgt vielmehr im Rahmen eines wissenschaftlichen Projekts, oder anders gesagt, sie nutzt die methodologischen Resultate von zwei Autoren der Philosophie, um ein wissenschaftliches Programm vorzustellen. Der Anspruch dieser Arbeit ist dementsprechend, durch das Zurückgreifen auf Hegels Dialektik eine neue Erkenntnis über die Sprache zu gewinnen, wobei die beiden kontradiktorischen Momente der Kognition – die Normativität, die durch das Bewusstsein erfolgt und diejenige, die durch Dispositionen erfolgt –, konstruktiv verbinden sind. Der konkrete Gewinn dieser Methodologie ist es demnach, eine Sprachphilosophie überhaupt als System festlegen zu können, ein System, das es ermöglicht, sprachliche Phänomene in all ihren Aspekten in kohärenter Weise zu fassen. Inhaltlich betrachtet zielt dieses Programm darauf ab, die allgemeine Stufe des Begriffs der Sprache als Moment des Begriffs des Geistes dialektisch abzuleiten, d. h. den richtigen Sinn der Sprache festzulegen. Eine vollständige Bearbeitung der Sprachphilosophie mithilfe der Dialektik konnte ich allerdings nicht durchführen, und der Umfang der mithilfe der Dialektik hergeleiteten Sprachkategorien begrenzt sich auf die Lehre der Einbildungskraft, die die Lehre der allgemeinen Semiologie und der Grammatik einschließt.
Hyperspectral remote sensing of the spatial and temporal heterogeneity of low Arctic vegetation
(2019)
Arctic tundra ecosystems are experiencing warming twice the global average and Arctic vegetation is responding in complex and heterogeneous ways. Shifting productivity, growth, species composition, and phenology at local and regional scales have implications for ecosystem functioning as well as the global carbon and energy balance. Optical remote sensing is an effective tool for monitoring ecosystem functioning in this remote biome. However, limited field-based spectral characterization of the spatial and temporal heterogeneity limits the accuracy of quantitative optical remote sensing at landscape scales. To address this research gap and support current and future satellite missions, three central research questions were posed:
• Does canopy-level spectral variability differ between dominant low Arctic vegetation communities and does this variability change between major phenological phases?
• How does canopy-level vegetation colour images recorded with high and low spectral resolution devices relate to phenological changes in leaf-level photosynthetic pigment concentrations?
• How does spatial aggregation of high spectral resolution data from the ground to satellite scale influence low Arctic tundra vegetation signatures and thereby what is the potential of upcoming hyperspectral spaceborne systems for low Arctic vegetation characterization?
To answer these questions a unique and detailed database was assembled. Field-based canopy-level spectral reflectance measurements, nadir digital photographs, and photosynthetic pigment concentrations of dominant low Arctic vegetation communities were acquired at three major phenological phases representing early, peak and late season. Data were collected in 2015 and 2016 in the Toolik Lake Research Natural Area located in north central Alaska on the North Slope of the Brooks Range. In addition to field data an aerial AISA hyperspectral image was acquired in the late season of 2016. Simulations of broadband Sentinel-2 and hyperspectral Environmental and Mapping Analysis Program (EnMAP) satellite reflectance spectra from ground-based reflectance spectra as well as simulations of EnMAP imagery from aerial hyperspectral imagery were also obtained.
Results showed that canopy-level spectral variability within and between vegetation communities differed by phenological phase. The late season was identified as the most discriminative for identifying many dominant vegetation communities using both ground-based and simulated hyperspectral reflectance spectra. This was due to an overall reduction in spectral variability and comparable or greater differences in spectral reflectance between vegetation communities in the visible near infrared spectrum.
Red, green, and blue (RGB) indices extracted from nadir digital photographs and pigment-driven vegetation indices extracted from ground-based spectral measurements showed strong significant relationships. RGB indices also showed moderate relationships with chlorophyll and carotenoid pigment concentrations. The observed relationships with the broadband RGB channels of the digital camera indicate that vegetation colour strongly influences the response of pigment-driven spectral indices and digital cameras can track the seasonal development and degradation of photosynthetic pigments.
Spatial aggregation of hyperspectral data from the ground to airborne, to simulated satel-lite scale was influenced by non-photosynthetic components as demonstrated by the distinct shift of the red edge to shorter wavelengths. Correspondence between spectral reflectance at the three scales was highest in the red spectrum and lowest in the near infra-red. By artificially mixing litter spectra at different proportions to ground-based spectra, correspondence with aerial and satellite spectra increased. Greater proportions of litter were required to achieve correspondence at the satellite scale.
Overall this thesis found that integrating multiple temporal, spectral, and spatial data is necessary to monitor the complexity and heterogeneity of Arctic tundra ecosystems. The identification of spectrally similar vegetation communities can be optimized using non-peak season hyperspectral data leading to more detailed identification of vegetation communities. The results also highlight the power of vegetation colour to link ground-based and satellite data. Finally, a detailed characterization non-photosynthetic ecosystem components is crucial for accurate interpretation of vegetation signals at landscape scales.
The unprecedented increase in atmospheric concentrations of carbon dioxide (CO2) and other greenhouse gases (GHG) by anthropogenic activities since the Industrial Revolution impacts on various earth system processes, commonly referred to as `climate change´ (CC). CC faces aquatic ecosystems with extreme abiotic perturbations that potentially alter the interrelations between functional autotrophic and heterotrophic plankton groups. These relations, however, modulate biogeochemical cycling and mediate the functioning of aquatic ecosystems as C sources or sinks to the atmosphere. The aim of this thesis was therefore to investigate how different aspects of CC influence community composition and functioning of pelagic heterotrophic bacteria. These organisms constitute a major component of biogeochemical cycling and largely determine the balance between autotrophic and heterotrophic processes.
Due to the vast amount of potential CC impacts, this thesis focuses on the following two aspects: (1) Increased exchange of CO2 across the atmosphere-water interface and reaction of CO2 with seawater leads to profound shifts in seawater carbonate chemistry, commonly termed as `ocean acidification´ (OA), with consequences for organism physiology and the availability of dissolved inorganic carbon (DIC) in seawater. (2) The increase in atmospheric GHG concentration impacts on the efficiency with which the Earth cools to space, affecting global surface temperature and climate. With ongoing CC, shifts in frequency and severity of episodic weather events, such as storms, are expected that in particular might affect lake ecosystems by disrupting thermal summer stratification. Both aspects of CC were studied at the ecosystem-level in large-volume mesocosm experiments by using the Kiel Off-shore Mesocosms for Future Ocean Simulations (KOSMOS) deployed at different coastal marine locations, and the LakeLab facility in Lake Stechlin.
We evaluated the impact of OA on heterotrophic bacterial metabolism in a brackish coastal ecosystem during low-nutrient summer months in the Baltic Sea. There are several in situ experiments that already assessed potential OA-induced changes in natural plankton communities at diverse spatial and seasonal conditions. However, most studies were performed at high phytoplankton biomass conditions, partly provoked by nutrient amendments. Our study highlights potential OA effects at low-nutrient conditions that are representative for most parts of the ocean and of particular interest in current OA research. The results suggest that during extended periods at low-nutrient concentrations, increasing pCO2 levels indirectly impact the growth balance of heterotrophic bacteria via trophic bacteria-phytoplankton interactions and shift the ecosystem to a more autotrophic system.
Further work investigated how OA affects heterotrophic bacterial dissolved organic matter (DOM) transformation in two mesocsom studies, performed at different nutrient conditions. We observed similar succession patterns for individual compound pools during a phytoplankton bloom and subsequent accumulation of these compounds irrespective of the pCO2 treatment. Our results indicate that OA-induced changes in the dynamics of bacterial DOM transformation and potential impacts on DOM quality are unlikely. In addition, there have been no indications that in dependence of nutrient conditions, different amounts of photosynthetic organic matter are channelled into the more recalcitrant DOM pool. This provides novel insights into the general dynamics of the marine DOM pool.
A fourth enclosure experiment in oligo-mesotrophic Lake Stechlin assessed the impact of a severe summer storm on lake bacterial communities during thermal stratification by artificially mixing. Mixing disrupted and lowered the thermocline, increasing the upper mixed layer and substantially changed water physical-chemical variables. Deep water entrainment and associated changes in water physical-chemical variables significantly affected relative bacterial abundances for about one week. Afterwards a pronounced cyanobacterial bloom developed in response to mixing which affected community assembly of heterotrophic bacteria. Colonization and mineralization of senescent phytoplankton cells by heterotrophic bacteria largely determined C-sequestration to the sediment. About six weeks after mixing, bacterial communities and measured activity parameters converged to control conditions. As such, summer storms have the potential to affect bacterial communities for a prolonged period during summer stratification. The results highlight effects on community assembly and heterotrophic bacterial metabolism that are associated to entrainment of deep water into the mixed water layer and assess consequences of an episodic disturbance event for the coupling between bacterial metabolism and autochthonous DOM production in large volume clear-water lakes.
Altogether, this doctoral thesis reveales substantial sensitivities of heterotrophic bacterial metabolism and community structure in response to OA and a simulated summer storm event, which should be considered when assessing the impact of climate change on marine and lake ecosystems.
The trace gases CO2 and CH4 pertain to the most relevant greenhouse gases and are important exchange fluxes of the global carbon (C) cycle. Their atmospheric quantity increased significantly as a result of the intensification of anthropogenic activities, such as especially land-use and land-use change, since the mid of the 18th century. To mitigate global climate change and ensure food security, land-use systems need to be developed, which favor reduced trace gas emissions and a sustainable soil carbon management. This requires the accurate and precise quantification of the influence of land-use and land-use change on CO2 and CH4 emissions. A common method to determine the trace gas dynamics and C sink or source function of a particular ecosystem is the closed chamber method. This method is often used assuming that accuracy and precision are high enough to determine differences in C gas emissions for e.g., treatment comparisons or different ecosystem components.
However, the broad range of different chamber designs, related operational procedures and data-processing strategies which are described in the scientific literature contribute to the overall uncertainty of closed chamber-based emission estimates. Hence, the outcomes of meta-analyses are limited, since these methodical differences hamper the comparability between studies. Thus, a standardization of closed chamber data acquisition and processing is much-needed.
Within this thesis, a set of case studies were performed to: (I) develop standardized routines for an unbiased data acquisition and processing, with the aim of providing traceable, reproducible and comparable closed chamber based C emission estimates; (II) validate those routines by comparing C emissions derived using closed chambers with independent C emission estimates; and (III) reveal processes driving the spatio-temporal dynamics of C emissions by developing (data processing based) flux separation approaches.
The case studies showed: (I) the importance to test chamber designs under field conditions for an appropriate sealing integrity and to ensure an unbiased flux measurement. Compared to the sealing integrity, the use of a pressure vent and fan was of minor importance, affecting mainly measurement precision; (II) that the developed standardized data processing routines proved to be a powerful and flexible tool to estimate C gas emissions and that this tool can be successfully applied on a broad range of flux data sets from very different ecosystem; (III) that automatic chamber measurements display temporal dynamics of CO2 and CH4 fluxes very well and most importantly, that they accurately detect small-scale spatial differences in the development of soil C when validated against repeated soil inventories; and (IV) that a simple algorithm to separate CH4 fluxes into ebullition and diffusion improves the identification of environmental drivers, which allows for an accurate gap-filling of measured CH4 fluxes.
Overall, the proposed standardized data acquisition and processing routines strongly improved the detection accuracy and precision of source/sink patterns of gaseous C emissions. Hence, future studies, which consider the recommended improvements, will deliver valuable new data and insights to broaden our understanding of spatio-temporal C gas dynamics, their particular environmental drivers and underlying processes.
A reliable inference of networks from data is of key interest in many scientific fields. Several methods have been suggested in the literature to reliably determine links in a network. These techniques rely on statistical methods, typically controlling the number of false positive links, but not considering false negative links. In this thesis new methodologies to improve network inference are suggested. Initial analyses demonstrate the impact of falsepositive and false negative conclusions about the presence or absence of links on the resulting inferred network. Consequently, revealing the importance of making well-considered choices leads to suggest new approaches to enhance existing network reconstruction methods.
A simulation study, presented in Chapter 3, shows that different values to balance false positive and false negative conclusions about links should be used in order to reliably estimate network characteristics. The existence of type I and type II errors in the reconstructed network, also called biased network, is accepted. Consequently, an analytic method that describes the influence of these two errors on the network structure is explored. As a result of this analysis, an analytic formula of the density of the biased vertex degree distribution is found (Chapter 4).
In the inverse problem, the vertex degree distribution of the true underlying network is analytically reconstructed, assuming the probabilities of type I and type II errors. Chapters 4-5 show that the method is robust to incorrect estimates of α and β within reasonable limits. In Chapter 6, an iterative procedure to enhance this method is presented in the case of large errors on the estimates of α and β.
The investigations presented so far focus on the influence of false positive and false negative links on the network characteristics. In Chapter 7, the analysis is reversed - the study focuses on the influence of network characteristics on the probability of type I and type II errors, in the case of networks of coupled oscillators. The probabilities of α and β are influenced by the shortest path length and the detour degree, respectively. These results have been used to improve the network reconstruction, when the true underlying network is not known a priori, introducing a novel and advanced concept of threshold.
Carbonfasern haben sich in der Luft- und Raumfahrt etabliert und gewinnen in Alltagsanwendungen wie dem Automobilbereich, Windkraft- und Sportbereich durch ihre hohen Zugfestigkeiten, insbesondere ihrer hohen E-Moduli, und ihrer geringen Dichte immer mehr an Bedeutung. Auf Grund ihrer hohen Kosten, welche sich zur Hälfte aus der Precursorherstellung, inklusive seiner Synthese und seinem Verspinnprozess, dem Lösungsspinnverfahren, ergeben, erhalten zunehmend alternative und schmelzspinnbare Precursoren Interesse. Für die Carbonfaserherstellung wird fast ausschließlich Polyacrylnitril (PAN) verwendet, das vor dem Schmelzen irreversible exotherme Zyklisierungsreaktionen aufweist, welchen sich seine Zersetzung anschließt. Eine Möglichkeit der Reduzierung der Schmelztemperatur von Polymeren ist die Einbringung von Comonomeren zur Erhöhung des freien Volumens und die Reduzierung der intermolekularen Wechselwirkungen als interne Weichmacher. Wie am Fraunhofer IAP gezeigt wurde, kann mittels 2-Methoxyethylacrylat (MEA) die Schmelztemperatur zu neuartigen PAN-basierten Precursoren verringert werden. Um den PAN-co-MEA-Precursor für die nachfolgenden Prozessschritte der Carbonfaserherstellung zu verwenden, müssen die thermoplastischen Fasern in thermisch stabile Fasern ohne thermoplastisches Verhalten überführt werden. Es wurde ein neuer Prozessschritt (Prästabilisierung) eingeführt, welcher unter alkalischen Bedingungen zur Abspaltung der Comonomerseitenkette führt. Neben der Esterhydrolyse finden Reaktionen statt, welche an diesem Material noch nicht hinreichend untersucht wurden. Weiterhin stellt sich die Frage nach der Kinetik der Prästabilisierung und der Ermittlung einer geeigneten Prozessführung.
Hierzu wurde die Prästabilisierung in den Labormaßstab überführt und die möglichen Zusammensetzungen des aus DMSO und einer KOH-Lösung bestehenden Reaktionsmediums evaluiert. Weiterhin wurde die Behandlung bei verschiedenen Prästabilisierungszeiten von maximal 30 min und Temperaturen von 40, 50 und 60 °C durchgeführt, um primär mittels NMR-Spektroskopie die chemischen Strukturänderungen aufzuklären. Die Esterhydrolyse des Comonomers, welche zur Abspaltung des 2-Methoxyethanols führt, wurde mittels 1H-NMR-spektroskopischer Untersuchungen detektiert.
Es wurde ein Modell aufgestellt, das die chemisch-physikalischen Strukturänderungen während der Prästabilisierung aufzeigt. Die zuerst ablaufende Reaktion ist die Esterhydrolyse am Comonomer, welche vom Faserrand nach innen verläuft und durch die Präsenz des DMSO in Kombination mit der KOH-Lösung (Superbase) initiiert wird. Der zeitliche Reaktionsverlauf der Esterhydrolyse kann in drei Bereiche eingeteilt werden. Der erste Bereich ab dem Prästabilisierungsbeginn wird durch die Diffusion der basischen Anionen in die Faser, der zweite Bereich durch die Reaktion an der Estergruppe des Comonomers und der dritte Bereich durch letzte Reaktionen im Faserinneren und diffusiven Prozessen der Produkte und Edukte charakterisiert. Der zweite Bereich kann mit einer Reaktion pseudo 1. Ordnung abgebildet werden, da in diesem Bereich bereits eine ausreichende Diffusion der Edukte in die Faser stattgefunden hat. Bei 50 °C spielt die Diffusion im ersten Bereich im Vergleich zur Reaktion eine untergeordnete Rolle. Mit Erhöhung der Temperatur auf 60 °C kann eine im Verhältnis geringere Diffusions- als Reaktionsgeschwindigkeit beobachtet werden. Die Nebenreaktionen wurden mittels 13C-CP/MAS-NMR-spektroskopischen, elementaranlaytischen Untersuchungen sowie Doppelbrechungsmessungen charakterisiert. Während der alkalischen Esterhydrolyse beginnt die Reduzierung der Nitrilgruppen unter der Bildung von primären Carbonsäureamiden und Carbonsäuren. Zur Beschreibung dieser Umsetzung wurde eine Methode entwickelt, welche die Addition von 13C-CP/MAS-NMR-Spektren der Modellsubstanzen PAN, PAM und PAA beinhaltet. Weitere stattfindende Reaktionen sind die Bildung von konjugierten Doppelbindungen, welche insbesondere auf eine Zyklisierung der Nitrile hinweisen. Die nasschemisch initiierte Zyklisierung der Nitrilgruppen kann zu kürzeren Stabilisierungszeiten und einem besser kontrollierbaren Stabilisierungsprozess durch geringere Wärmefreisetzung und schlussendlich zu einer Kostenersparnis des gesamten Verfahrens führen. Die Umsetzung der Nitrilgruppen konnte mit einer Reaktion pseudo 1. Ordnung gut abgebildet werden. DMSO initiiert die Esterhydrolyse, wobei die KOH-Konzentration einen höheren Einfluss auf die Reaktionsgeschwindigkeit der Ester- und Nitrilhydrolyse als die DMSO-Konzentration besitzt. Beide Reaktionen zeigen eine vergleichbare Abhängigkeit von der Temperatur. Die Erhöhung der Prästabilisierungszeit und der KOH- bzw. DMSO-Konzentration führt zur Migration niedermolekularer Bestandteile des Fasermaterials an die Oberfläche und der Bildung punktueller Ablagerungen bis hin zu miteinander verbundenen Einzelfasern. Eine weitere Erhöhung der Prästabilisierungszeit bzw. der Konzentration führt zu einem steigenden Carbonsäureanteil und zur Quellung des Fasermaterials, wodurch die Ablagerungen in das Reaktionsmedium diffundieren. Die Ablagerungen enthalten Chlor, welches durch den Waschvorgang mit HCl in das Materialsystem gelangt ist und durch Parameteranpassungen reduziert wurde. Die schmelzbaren Fasern konnten durch die Prästabilisierung erfolgreich über eine Kern-Mantel-Struktur in nicht-thermoplastische Fasern überführt werden.
Zur Ermittlung eines geeigneten Prozessfensters für nachfolgende thermische Beanspruchungen der prästabilisierten Fasern wurden drei Kriterien identifiziert, anhand welcher die Evaluation erfolgte. Das erste Kriterium beinhaltet die Notwendigkeit der vollständigen Aufhebung der thermoplastischen Eigenschaft der Fasern. Als zweites Kriterium diente die Fasermorphologie. Anhand von REM-Aufnahmen wurden Faserbündel mit separierten Einzelfasern ohne Ablagerungen für die nachfolgende Stabilisierung ausgewählt. Das dritte Kriterium bezieht sich auf eine möglichst geringe Umsetzung der Nitrilgruppen, um Prästabilisierungsbedingungen mit Nebenreaktionen zu vermeiden.
Aus den Untersuchungen konnte eine Prästabilisierungstemperatur von 60 °C als geeignet identifiziert werden. Weiterhin führen hoch alkalische Zusammensetzungen des Reaktionsmediums mit KOH-Konzentrationen von 1, 1,5 und 2 M, vorzugsweise 1,5 M und 50 vol% DMSO mit Reaktionszeiten von unter 10 min zu geeigneten Fasern. Ein MEA-Anteil unterhalb von 2 mol% bewirkt eine Überführung in die Unschmelzbarkeit. Thermisch stabile und für die nachfolgende Stabilisierung geeignete Fasern besitzen weiterhin 68 – 80 mol% Nitrilgruppen, 20 – 25 mol% Carbonsäuren, bis zu 15 mol% primäre Carbonsäureamide und zyklisierte Strukturen.
Sin pragmática no sería posible la comunicación, puesto que no podríamos interpretar enunciados lingüísticos. A cualquier aprendiente de una lengua que no domina, no le basta con ser competente lingüísticamente, puesto que su fin es comunicarse con otras personas y en contextos determinados. Solo una enseñanza que facilite la habilidad de producir y comprender enunciados para realizar actos de lengua, seleccionando los más apropiados para un contexto determinado, podrá preciarse de ser eficiente.
El trabajo que aquí se presenta pretende dar a conocer a la comunidad científica y, en especial, a los y las involucradas directa e indirectamente en el proceso de enseñanza, el concepto de pragmática verbal y contrastarlo con otros como gramática, cultura o interculturalidad, así como concienciarlos de la importancia y de la necesidad imperiosa del establecimiento de la pragmática como disciplina relevante en el proceso comunicativo y, en especial, de su inclusión sistemática y manifiesta en los libros de texto de español como lengua extranjera elaborados para el contexto escolar. Para ello se investiga la presencia de elementos pragmáticos y el fomento de la competencia pragmática en libros de texto para principiantes, por ser estos el material utilizado por excelencia en las escuelas y por su relevancia a la hora de especificar contenidos, tipo de progresión y metodología.
L’extériorisation de toute communication est assujettie à un mode d’accès du locuteur aux informations véhiculées. Les constatations faites de nos données prouvent que tous les huit verbes étudiés traduisent des mécanismes d’acquisition des connaissances que nous avons appelés en emprunt à (Vogeleer, 1995 :92) « l’accès cognitif au savoir ». C’est cette valeur intrinsèque qui vaut à ces termes la dénomination de verbes médiatifs. En d’autres mots, ce sont des éléments qui explicitent des processus d’accès du locuteur au savoir. Une source du savoir qui peut être directe (la vue, le touché, l’ouïe, l’odorat…) ou indirecte (ouï-dire) et surtout inférée. Nous entendons par inférence un processus d’analyse et de mise en relation d’éléments (prémisses), lesquelles permettent de tirer une conclusion par déduction, induction ou par abduction. Et selon que lesdites prémisses tendent à être plus ou moins fiables, ces processus inférentiels impliqueront des valeurs épistémiques à des degrés divers.
Sur le plan rhétorico-syntaxique, nos analyses ont montré tous les verbes cognitifs (VC) de cette étude exigent l’occurrence d’autres constituants (actants) phrastiques qu’ils régissent. C’est grâce à cette valence verbale qu’ils gardent un pouvoir rectionnel dans les constructions asyndétiques. Ce sont donc les matrices des éléments sur lesquels ils se rapportent. Quant au cinétisme de ces verbes, il possède une fonction rhétorique et syntaxique. En effet, cet agencement particulier et souvent perturbant permet de traduire l’expression d’une figure de syntaxe à effet rhétorique : l’hyperbate. Une construction atypique qui, à travers les agencements anticonformistes, donne un sens de regressivité à l’énoncé et confère une saillance à des termes mis ce fait en exergue.
Light-induced pH cycle
(2019)
Background Many biochemical reactions depend on the pH of their environment and some are strongly accelerated in an acidic surrounding. A classical approach to control biochemical reactions non-invasivly is by changing the temperature. However, if the pH could be controlled by optical means using photo-active chemicals, this would mean to be able to accelerate suitable biochemical reactions. Optically switching the pH can be achieved by using photoacids. A photoacid is a molecule with a functional group that releases a proton upon irradiation with the suitable wavelength, acidifying the environmental aqueous surrounding. A major goal of this work was to establish a non-invasive method of optically controlling the pH in aqueous solutions, offering the opportunity to enhance the known chemical reactions portfolio. To demonstrate the photo-switchable pH cycling we chose an enzymatic assay using acid phosphatase, which is an enzyme with a strong pH dependent activity.
Results In this work we could demonstrate a light-induced, reversible control of the enzymatic activity of acid phosphatase non-invasivly. To successfully conduct those experiments a high power LED array was designed and built, suitable for a 96 well standard microtiter plate, not being commercially available. Heat management and a lateral ventilation system to avoid heat accumulation were established and a stable light intensity achieved. Different photoacids were characterised and their pH dependent absorption spectra recorded. By using the reversible photoacid G-acid as a proton donor, the pH can be changed reversibly using high power UV 365 nm LEDs. To demonstrate the pH cycling, acid phosphatase with hydrolytic activity under acidic conditions was chosen. An assay using the photoacid together with the enzyme was established, also providing that G-acid does not inhibit acid phosphatase. The feasibility of reversibly regulating the enzyme’s pH dependent activity by optical means was demonstrated, by controlling the enzymatic activity with light. It was demonstrated that the enzyme activity depends on the light exposure time only. When samples are not illuminated and left in the dark, no enzymatic activity was recorded. The process can be rapidly controlled by simply switching the light on and off and should be applicable to a wide range of enzymes and biochemical reactions.
Conclusions Reversible photoacids offer a light-dependent regulation of pH, making them extremely attractive for miniaturizable, non-invasive and time-resolved control of biochemical reactions. Many enzymes have a sharp pH dependent activity, thus the established setup in this thesis could be used for a versatile enzyme portfolio. Even though the demonstrated photo-switchable strategy could also be used for non-enzymatic assays, greatly facilitating the assay establishment. Photoacids have the potential for high throughput methods and automation. We demonstrated that it is possible to control photoacids using commonly available LEDs, making their use in highly integrated devices and instruments more attractive. The successfully designed 96 well high power UV LED array presents an opportunity for general combinatorial analysis in e.g. photochemistry, where a high light intensity is needed for the investigation of various reactions.
Interlocutors typically link their utterances to the discourse environment and enrich communication by linguistic (e.g., information packaging) and extra-linguistic (e.g., eye gaze, gestures) means to optimize information transfer. Psycholinguistic studies underline that ‒for meaning computation‒ listeners profit from linguistic and visual cues that draw their focus of attention to salient information. This dissertation is the first work that examines how linguistic compared to visual salience cues influence sentence comprehension using the very same experimental paradigms and materials, that is, German subject-before-object (SO) and object-before-subject (OS) sentences, across the two cue modalities. Linguistic salience was induced by indicating a referent as the aboutness topic. Visual salience was induced by implicit (i.e., unconscious) or explicit (i.e., shared) manipulations of listeners’ attention to a depicted referent.
In Study 1, a selective, facilitative impact of linguistic salience on the context-sensitive OS word order was found using offline comprehensibility judgments. More precisely, during online sentence processing, this impact was characterized by a reduced sentence-initial Late positivity which reflects reduced processing costs for updating the current mental representation of discourse. This facilitative impact of linguistic salience was not replicated by means of an implicit visual cue (Study 2) shown to modulate word order preferences during sentence production. However, a gaze shift to a depicted referent as an indicator of shared attention eased sentence-initial processing similar to linguistic salience as revealed by reduced reading times (Study 3). Yet, this cue did not modulate the strong subject-antecedent preference during later pronoun resolution like linguistic salience. Taken together, these findings suggest a significant impact of linguistic and visual salience cues on sentence comprehension, which substantiates that both the information delivered via language and via the visual environment is integrated into the mental representation of the discourse; but, the way how salience is induced is crucial to its impact.
The goal of this thesis is to broaden the empirical basis for a better, comprehensive understanding
of massive star evolution, star formation and feedback at low metallicity. Low metallicity massive stars are a key to understand the early universe. Quantitative information on metal-poor massive stars was sparse before. The quantitative spectroscopic studies of massive star populations associated with large-scale ISM structures were not performed at low metallicity before, but are important to investigate star-formation histories and feedback in detail. Much of this work relies on spectroscopic observations with VLT-FLAMES of ~500 OB stars in the Magellanic Clouds. When available, the optical spectroscopy was complemented by UV spectra from the HST, IUE, and FUSE archives. The two representative young stellar populations that have been studied are associated with the superbubble N 206 in the Large Magellanic Cloud (LMC) and with the supergiant shell SMC-SGS 1 in the Wing of the Small Magellanic Cloud (SMC), respectively. We performed spectroscopic analyses of the massive stars using the nonLTE Potsdam Wolf-Rayet (PoWR) model atmosphere code. We estimated the stellar, wind, and feedback parameters of the individual massive stars and established their statistical distributions.
The mass-loss rates of N206 OB stars are consistent with theoretical expectations for LMC metallicity. The most massive and youngest stars show nitrogen enrichment at their surface and are found to be slower rotators than the rest of the sample. The N 206 complex has undergone star formation episodes since more than 30 Myr, with a current star formation rate higher than average in the LMC. The spatial age distribution of stars across the complex possibly indicates triggered star formation due to the expansion of the superbubble. Three very massive, young Of stars in the region dominate the ionizing and mechanical feedback among hundreds of other OB stars in the sample. The current stellar wind feedback rate from the two WR stars in the complex is comparable to that released by the whole OB sample. We see only a minor fraction of this stellar wind feedback converted into X-ray emission. In this LMC complex, stellar winds and supernovae equally contribute to the total energy feedback, which eventually powered the central superbubble. However, the total energy input accumulated over the time scale of the superbubble significantly exceeds the observed energy content of the complex. The lack of energy along with the morphology of the complex suggests a leakage of hot gas from the superbubble.
With a detailed spectroscopic study of massive stars in SMC-SGS 1, we provide the stellar and wind parameters of a large sample of OB stars at low metallicity, including those in the lower mass-range. The stellar rotation velocities show a broad, tentatively bimodal distribution, with Be stars being among the fastest. A few very luminous O stars are found close to the main sequence, while all other, slightly evolved stars obey a strict luminosity limit. Considering additional massive stars in evolved stages, with published parameters and located all over the SMC, essentially confirms this picture. The comparison with single-star evolutionary tracks suggests a dichotomy in the fate of massive stars in the SMC. Only stars with an initial mass below 30 solar masses seem to evolve from the main sequence to the cool side of the HRD to become a red supergiant and to explode as type II-P supernova. In contrast, more massive stars appear to stay always hot and might evolve quasi chemically homogeneously, finally collapsing to relatively massive black holes. However, we find no indication that chemical mixing is correlated with rapid rotation. We measured the key parameters of stellar feedback and established the links between the rates of star formation and supernovae. Our study demonstrates that in metal-poor environments stellar feedback is dominated by core-collapse supernovae in combination with winds and ionizing radiation supplied by a few of the most massive stars. We found indications of the stochastic mode of star formation, where the resulting stellar population is fully capable of producing large-scale structures such as the supergiant shell SMC-SGS 1 in the Wing. The low level of feedback in metal-poor stellar populations allows star formation episodes to persist over long timescales.
Our study showcases the importance of quantitative spectroscopy of massive stars with adequate stellar-atmosphere models in order to understand star-formation, evolution, and feedback. The stellar population analyses in the LMC and SMC make us understand that massive stars and their impact can be very different depending on their environment. Obviously, due to their different metallicity, the massive stars in the LMC and the SMC follow different evolutionary paths. Their winds differ significantly, and the key feedback agents are different. As a consequence, the star formation can proceed in different modes.
Membrane adhesion is a fundamental biological process in which membranes are attached to neighboring membranes or surfaces. Membrane adhesion emerges from a complex interplay between the binding of membrane-anchored receptors/ligands and the membrane properties. In this work, we study membrane adhesion mediated by lipid-anchored saccharides using microsecond-long full-atomistic molecular dynamics simulations. Motivated by neutron scattering experiments on membrane adhesion via lipid-anchored saccharides, we investigate the role of LeX, Lac1, and Lac2 saccharides and membrane fluctuations in membrane adhesion.
We study the binding of saccharides in three different systems: for saccharides in water, for saccharides anchored to essentially planar membranes at fixed separations, and for saccharides anchored to apposing fluctuating membranes. Our simulations of two saccharides in water indicate that the saccharides engage in weak interactions to form dimers. We find that the binding occurs in a continuum of bound states instead of a certain number of well-defined bound structures, which we term as "diffuse binding".
The binding of saccharides anchored to essentially planar membranes strongly depends on separation of the membranes, which is fixed in our simulation system. We show that the binding constants for trans-interactions of two lipid-anchored saccharides monotonically decrease with increasing separation. Saccharides anchored to the same membrane leaflet engage in cis-interactions with binding constants comparable to the trans-binding constants at the smallest membrane separations. The interplay of cis- and trans-binding can be investigated in simulation systems with many lipid-anchored saccharides. For Lac2, our simulation results indicate a positive cooperativity of trans- and cis-binding. In this cooperative binding the trans-binding constant is enhanced by the cis-interactions. For LeX, in contrast, we observe no cooperativity between trans- and cis-binding. In addition, we determine the forces generated by trans-binding of lipid-anchored saccharides in planar membranes from the binding-induced deviations of the lipid-anchors. We find that the forces acting on trans-bound saccharides increase with increasing membrane separation to values of the order of 10 pN.
The binding of saccharides anchored to the fluctuating membranes results from an interplay between the binding properties of the lipid-anchored saccharides and membrane fluctuations. Our simulations, which have the same average separation of the membranes as obtained from the neutron scattering experiments, yield a binding constant larger than in planar membranes with the same separation. This result demonstrates that membrane fluctuations play an important role at average membrane separations which are seemingly too large for effective binding. We further show that the probability distribution of the local separation can be well approximated by a Gaussian distribution. We calculate the relative membrane roughness and show that our results are in good agreement with the roughness values reported from the neutron scattering experiments.
Domestication syndrome has resulted in the large loss of genetic variation of crop plants. Because of such genetic loss, productivity of various beneficial secondary (specialized) metabolites that protect against abiotic/biotic stresses, has been narrowed in many domesticated crops. Many key regulators or structural genes of secondary metabolic pathways in the domesticated as well as wild tomatoes are still largely unknown. In recent studies, metabolic quantitative trait loci (mQTL) analysis using the population of introgression lines (ILs), each containing a single introgression from Solanum pennellii (wild tomato) in the genetic background of domesticated tomato (M82, Solanum lycopersicum), has been used for investigation of metabolic regulation and key genes involved in both primary and secondary metabolism. In this thesis, three research projects, i) understanding of metabolic linkage between branched chain amino acids (BCAAs) and secondary metabolism using antisense lines of BCAAs metabolic genes, ii) investigation of novel key genes involved in tomato secondary metabolism and fruit ripening, iii) mapping of drought stress responsive mQTLs in tomato, are presented and discussed. In the first part, metabolic linkage between leucine and secondary metabolism is investigated by analyzing antisense lines of four key genes (ketol-acid reductoisomerase, KARI; dihydroxy-acid dehydratase, DHAD; isopropylmalate dehydratase, IPMD and branched chain aminotransferases1, BCAT1) found previously in mQTL of leucine contents. Obtained results indicate that KARI might be a rate limiting enzyme for iC5 acyl-sucrose synthesis in young leaf but not in red ripe fruits. By integrating obtained results with previous reports, inductive metabolic linkage between BCAAs and other secondary metabolic pathways at DHAD transcriptional levels in fruit is proposed. In the second part, candidate genes that are involved in secondary metabolism and fruit ripening in tomato were found by the approach of expression quantitative trait loci (eQTL) analysis. To predict functions of those candidate genes, functional validation by virus induced gene silencing and transient overexpression were performed. Results obtained by analyzing T0 overexpression and artificial miRNA lines for some of those candidates confirm their predicted functions, for example involved in fruit ripening (WD40, Solyc04g005020) and iC5 acyl-sucrose synthesis (P450, Solyc03g111940). In the third part, mapping of drought stress responsive mQTLs was performed using 57 S. pennellii ILs population. Evaluation of genetic architecture of mQTL analysis resulted in identifying drought responsive ILs (11-2, 8-3-1, 10-1-1 and 3-1). Location of well characterized regulators in these ILs helped to filter potential new key genes involved in drought stress tolerance. Obtained results suggests us our approaches could be viable for narrowing down potential candidates involved in creating interspecific variation in secondary metabolite content and at the level of fruit ripening.
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.
Continuous insight into biological processes has led to the development of large-scale, mechanistic systems biology models of pharmacologically relevant networks. While these models are typically designed to study the impact of diverse stimuli or perturbations on multiple system variables, the focus in pharmacological research is often on a specific input, e.g., the dose of a drug, and a specific output related to the drug effect or response in terms of some surrogate marker.
To study a chosen input-output pair, the complexity of the interactions as well as the size of the models hinders easy access and understanding of the details of the input-output relationship.
The objective of this thesis is the development of a mathematical approach, in specific a model reduction technique, that allows (i) to quantify the importance of the different state variables for a given input-output relationship, and (ii) to reduce the dynamics to its essential features -- allowing for a physiological interpretation of state variables as well as parameter estimation in the statistical analysis of clinical data. We develop a model reduction technique using a control theoretic setting by first defining a novel type of time-limited controllability and observability gramians for nonlinear systems. We then show the superiority of the time-limited generalised gramians for nonlinear systems in the context of balanced truncation for a benchmark system from control theory.
The concept of time-limited controllability and observability gramians is subsequently used to introduce a state and time-dependent quantity called the input-response (ir) index that quantifies the importance of state variables for a given input-response relationship at a particular time.
We subsequently link our approach to sensitivity analysis, thus, enabling for the first time the use of sensitivity coefficients for state space reduction. The sensitivity based ir-indices are given as a product of two sensitivity coefficients. This allows not only for a computational more efficient calculation but also for a clear distinction of the extent to which the input impacts a state variable and the extent to which a state variable impacts the output.
The ir-indices give insight into the coordinated action of specific state variables for a chosen input-response relationship.
Our developed model reduction technique results in reduced models that still allow for a mechanistic interpretation in terms of the quantities/state variables of the original system, which is a key requirement in the field of systems pharmacology and systems biology and distinguished the reduced models from so-called empirical drug effect models. The ir-indices are explicitly defined with respect to a reference trajectory and thereby dependent on the initial state (this is an important feature of the measure). This is demonstrated for an example from the field of systems pharmacology, showing that the reduced models are very informative in their ability to detect (genetic) deficiencies in certain physiological entities. Comparing our novel model reduction technique to the already existing techniques shows its superiority.
The novel input-response index as a measure of the importance of state variables provides a powerful tool for understanding the complex dynamics of large-scale systems in the context of a specific drug-response relationship. Furthermore, the indices provide a means for a very efficient model order reduction and, thus, an important step towards translating insight from biological processes incorporated in detailed systems pharmacology models into the population analysis of clinical data.
The North China Plain (NCP) is one of the most productive and intensive agricultural regions in China. High doses of mineral nitrogen (N) fertiliser, often combined with flood irrigation, are applied, resulting in N surplus, groundwater depletion and environmental pollution. The objectives of this thesis were to use the HERMES model to simulate the N cycle in winter wheat (Triticum aestivum L.)–summer maize (Zea mays L.) double crop rotations and show the performance of the HERMES model, of the new ammonia volatilisation sub-module and of the new nitrification inhibition tool in the NCP. Further objectives were to assess the models potential to save N and water on plot and county scale, as well as on short and long-term. Additionally, improved management strategies with the help of a model-based nitrogen fertiliser recommendation (NFR) and adapted irrigation, should be found.
Results showed that the HERMES model performed well under growing conditions of the NCP and was able to describe the relevant processes related to soil–plant interactions concerning N and water during a 2.5 year field experiment. No differences in grain yield between the real-time model-based NFR and the other treatments of the experiments on plot scale in Quzhou County could be found. Simulations with increasing amounts of irrigation resulted in significantly higher N leaching, higher N requirements of the NFR and reduced yields. Thus, conventional flood irrigation as currently practised by the farmers bears great uncertainties and exact irrigation amounts should be known for future simulation studies. In the best-practice scenario simulation on plot-scale, N input and N leaching, but also irrigation water could be reduced strongly within 2 years. Thus, the model-based NFR in combination with adapted irrigation had the highest potential to reduce nitrate leaching, compared to farmers practice and mineral N (Nmin)-reduced treatments. Also the calibrated and validated ammonia volatilisation sub-module of the HERMES model worked well under the climatic and soil conditions of northern China. Simple ammonia volatilisation approaches gave also satisfying results compared to process-oriented approaches. During the simulation with Ammonium sulphate Nitrate with nitrification inhibitor (ASNDMPP) ammonia volatilisation was higher than in the simulation without nitrification inhibitor, while the result for nitrate leaching was the opposite. Although nitrification worked well in the model, nitrification-born nitrous oxide emissions should be considered in future. Results of the simulated annual long-term (31 years) N losses in whole Quzhou County in Hebei Province were 296.8 kg N ha−1 under common farmers practice treatment and 101.7 kg N ha−1 under optimised treatment including NFR and automated irrigation (OPTai). Spatial differences in simulated N losses throughout Quzhou County, could only be found due to different N inputs. Simulations of an optimised treatment, could save on average more than 260 kg N ha−1a−1 from fertiliser input and 190 kg N ha−1a−1 from N losses and around 115.7 mm a−1 of water, compared to farmers practice. These long-term simulation results showed lower N and water saving potential, compared to short-term simulations and underline the necessity of long-term simulations to overcome the effect of high initial N stocks in soil.
Additionally, the OPTai worked best on clay loam soil except for a high simulated denitrification loss, while the simulations using farmers practice irrigation could not match the actual water needs resulting in yield decline, especially for winter wheat. Thus, a precise adaption of management to actual weather conditions and plant growth needs is necessary for future simulations. However, the optimised treatments did not seem to be able to maintain the soil organic matter pools, even with full crop residue input. Extra organic inputs seem to be required to maintain soil quality in the optimised treatments.
HERMES is a relatively simple model, with regard to data input requirements, to simulate the N cycle. It can offer interpretation of management options on plot, on county and regional scale for extension and research staff. Also in combination with other N and water saving methods the model promises to be a useful tool.
The growing energy demand of the modern economies leads to the increased consumption of fossil fuels in form of coal, oil, and natural gases, as the mains sources. The combustion of these carbon-based fossil fuels is inevitably producing greenhouse gases, especially CO2. Approaches to tackle the CO2 problem are to capture it from the combustion sources or directly from air, as well as to avoid CO2 production in energy consuming sources (e.g., in the refrigeration sector). In the former, relatively low CO2 concentrations and competitive adsorption of other gases is often leading to low CO2 capacities and selectivities. In both approaches, the interaction of gas molecules with porous materials plays a key role. Porous carbon materials possess unique properties including electric conductivity, tunable porosity, as well as thermal and chemical stability. Nevertheless, pristine carbon materials offer weak polarity and thus low CO2 affinity. This can be overcome by nitrogen doping, which enhances the affinity of carbon materials towards acidic or polar guest molecules (e.g., CO2, H2O, or NH3). In contrast to heteroatom-free materials, such carbon materials are in most cases “noble”, that is, they oxidize other matter rather than being oxidized due to the very positive working potential of their electrons. The challenging task here is to achieve homogenous distribution of significant nitrogen content with similar bonding motives throughout the carbon framework and a uniform pore size/distribution to maximize host-guest interactions. The aim of this thesis is the development of novel synthesis pathways towards nitrogen-doped nanoporous noble carbon materials with precise design on a molecular level and understanding of their structure-related performance in energy and environmental applications, namely gas adsorption and electrochemical energy storage.
A template-free synthesis approach towards nitrogen-doped noble microporous carbon materials with high pyrazinic nitrogen content and C2N-type stoichiometry was established via thermal condensation of a hexaazatriphenylene derivative. The materials exhibited high uptake of guest molecules, such as H2O and CO2 at low concentrations, as well as moderate CO2/N2 selectivities. In the following step, the CO2/N2 selectivity was enhanced towards molecular sieving of CO2 via kinetic size exclusion of N2. The precise control over the condensation degree, and thus, atomic construction and porosity of the resulting materials led to remarkable CO2/N2 selectivities, CO2 capacities, and heat of CO2 adsorption. The ultrahydrophilic nature of the pore walls and the narrow microporosity of these carbon materials served as ideal basis for the investigation of interface effects with more polar guest molecules than CO2, namely H2O and NH3.
H2O vapor physisorption measurements, as well as NH3-temperature programmed desorption and thermal response measurements showed exceptionally high affinity towards H2O vapor and NH3 gas. Another series of nitrogen-doped carbon materials was synthesized by direct condensation of a pyrazine-fused conjugated microporous polymer and their structure-related performance in electrochemical energy storage, namely as anode materials for sodium-ion battery, was investigated.
All in all, the findings in this thesis exemplify the value of molecularly designed nitrogen-doped carbon materials with remarkable heteroatom content implemented as well-defined structure motives. The simultaneous adjustment of the porosity renders these materials suitable candidates for fundamental studies about the interactions between nitrogen-doped carbon materials and different guest species.
Supercapacitors are electrochemical energy storage devices with rapid charge/discharge rate and long cycle life. Their biggest challenge is the inferior energy density compared to other electrochemical energy storage devices such as batteries. Being the most widely spread type of supercapacitors, electrochemical double-layer capacitors (EDLCs) store energy by electrosorption of electrolyte ions on the surface of charged electrodes. As a more recent development, Na-ion capacitors (NICs) are expected to be a more promising tactic to tackle the inferior energy density due to their higher-capacity electrodes and larger operating voltage. The charges are simultaneously stored by ion adsorption on the capacitive-type cathode surface and via faradic process in the battery-type anode, respectively. Porous carbon electrodes are of great importance in these devices, but the paramount problems are the facile synthetic routes for high-performance carbons and the lack of fundamental understanding of the energy storage mechanisms. Therefore, the aim of the present dissertation is to develop novel synthetic methods for (nitrogen-doped) porous carbon materials with superior performance, and to reveal a deeper understanding energy storage mechanisms of EDLCs and NICs.
The first part introduces a novel synthetic method towards hierarchical ordered meso-microporous carbon electrode materials for EDLCs. The large amount of micropores and highly ordered mesopores endow abundant sites for charge storage and efficient electrolyte transport, respectively, giving rise to superior EDLC performance in different electrolytes. More importantly, the controversial energy storage mechanism of EDLCs employing ionic liquid (IL) electrolytes is investigated by employing a series of porous model carbons as electrodes. The results not only allow to conclude on the relations between the porosity and ion transport dynamics, but also deliver deeper insights into the energy storage mechanism of IL-based EDLCs which is different from the one usually dominating in solvent-based electrolytes leading to compression double-layers.
The other part focuses on anodes of NICs, where novel synthesis of nitrogen-rich porous carbon electrodes and their sodium storage mechanism are investigated. Free-standing fibrous nitrogen-doped carbon materials are synthesized by electrospinning using the nitrogen-rich monomer (hexaazatriphenylene-hexacarbonitrile, C18N12) as the precursor followed by condensation at high temperature. These fibers provide superior capacity and desirable charge/discharge rate for sodium storage. This work also allows insights into the sodium storage mechanism in nitrogen-doped carbons. Based on this mechanism, further optimization is done by designing a composite material composed of nitrogen-rich carbon nanoparticles embedded in conductive carbon matrix for a better charge/discharge rate. The energy density of the assembled NICs significantly prevails that of common EDLCs while maintaining the high power density and long cycle life.
The Central Andes host large reserves of base and precious metals. The region represented, in 2017, an important part of the worldwide mining activity. Three principal types of deposits have been identified and studied: 1) porphyry type deposits extending from central Chile and Argentina to Bolivia, and Northern Peru, 2) iron oxide-copper-gold (IOCG) deposits, extending from central Peru to central Chile, and 3) epithermal tin polymetallic deposits extending from Southern Peru to Northern Argentina, which compose a large part of the deposits of the Bolivian Tin Belt (BTB). Deposits in the BTB can be divided into two major types: (1) tin-tungsten-zinc pluton-related polymetallic deposits, and (2) tin-silver-lead-zinc epithermal polymetallic vein deposits.
Mina Pirquitas is a tin-silver-lead-zinc epithermal polymetallic vein deposit, located in north-west Argentina, that used to be one of the most important tin-silver producing mine of the country. It was interpreted to be part of the BTB and it shares similar mineral associations with southern pluton related BTB epithermal deposits. Two major mineralization events related to three pulses of magmatic fluids mixed with meteoric water have been identified. The first event can be divided in two stages: 1) stage I-1 with quartz, pyrite, and cassiterite precipitating from fluids between 233 and 370 °C and salinity between 0 and 7.5 wt%, corresponding to a first pulse of fluids, and 2) stage I-2 with sphalerite and tin-silver-lead-antimony sulfosalts precipitating from fluids between 213 and 274 °C with salinity up to 10.6 wt%, corresponding to a new pulse of magmatic fluids in the hydrothermal system. The mineralization event II deposited the richest silver ores at Pirquitas. Event II fluids temperatures and salinities range between 190 and 252 °C and between 0.9 and 4.3 wt% respectively. This corresponds to the waning supply of magmatic fluids. Noble gas isotopic compositions and concentrations in ore-hosted fluid inclusions demonstrate a significant contribution of magmatic fluids to the Pirquitas mineralization although no intrusive rocks are exposed in the mine area.
Lead and sulfur isotopic measurements on ore minerals show that Pirquitas shares a similar signature with southern pluton related polymetallic deposits in the BTB. Furthermore, the major part of the sulfur isotopic values of sulfide and sulfosalt minerals from Pirquitas ranges in the field for sulfur derived from igneous rocks. This suggests that the main contribution of sulfur to the hydrothermal system at Pirquitas is likely to be magma-derived. The precise age of the deposit is still unknown but the results of wolframite dating of 2.9 ± 9.1 Ma and local structural observations suggest that the late mineralization event is younger than 12 Ma.
Predation drives coexistence, evolution and population dynamics of species in food webs, and has strong impacts on related ecosystem functions (e.g. primary production). The effect of predation on these processes largely depends on the trade-offs between functional traits in the predator and prey community. Trade-offs between defence against predation and competitive ability, for example, allow for prey speciation and predator-mediated coexistence of prey species with different strategies (defended or competitive), which may stabilize the overall food web dynamics. While the importance of such trade-offs for coexistence is widely known, we lack an understanding and the empirical evidence of how the variety of differently shaped trade-offs at multiple trophic levels affect biodiversity, trait adaptation and biomass dynamics in food webs. Such mechanistic understanding is crucial for predictions and management decisions that aim to maintain biodiversity and the capability of communities to adapt to environmental change ensuring their persistence.
In this dissertation, after a general introduction to predator-prey interactions and tradeoffs, I first focus on trade-offs in the prey between qualitatively different types of defence (e.g. camouflage or escape behaviour) and their costs. I show that these different types lead to different patterns of predator-mediated coexistence and population dynamics, by using a simple predator-prey model. In a second step, I elaborate quantitative aspects of trade-offs and demonstrates that the shape of the trade-off curve in combination with trait-fitness relationships strongly affects competition among different prey types: Either specialized species with extreme trait combinations (undefended or completely defended) coexist, or a species with an intermediate defence level dominates. The developed theory on trade-off shapes and coexistence is kept general, allowing for applications apart from defence-competitiveness trade-offs. Thirdly, I tested the theory on trade-off shapes on a long-term field data set of phytoplankton from Lake Constance. The measured concave trade-off between defence and growth governs seasonal trait changes of phytoplankton in response to an altering grazing pressure by zooplankton, and affects the maintenance of trait variation in the community. In a fourth step, I analyse the interplay of different tradeoffs at multiple trophic levels with plankton data of Lake Constance and a corresponding tritrophic food web model. The results show that the trait and biomass dynamics of the different three trophic levels are interrelated in a trophic biomass-trait cascade, leading to unintuitive patterns of trait changes that are reversed in comparison to predictions from bitrophic systems. Finally, in the general discussion, I extract main ideas on trade-offs in multitrophic systems, develop a graphical theory on trade-off-based coexistence, discuss the interplay of intra- and interspecific trade-offs, and end with a management-oriented view on the results of the dissertation, describing how food webs may respond to future global changes, given their trade-offs.
The Himalayas are a region that is most dependent, but also frequently prone to hazards from changing meltwater resources. This mountain belt hosts the highest mountain peaks on earth, has the largest reserve of ice outside the polar regions, and is home to a rapidly growing population in recent decades. One source of hazard has attracted scientific research in particular in the past two decades: glacial lake outburst floods (GLOFs) occurred rarely, but mostly with fatal and catastrophic consequences for downstream communities and infrastructure. Such GLOFs can suddenly release several million cubic meters of water from naturally impounded meltwater lakes. Glacial lakes have grown in number and size by ongoing glacial mass losses in the Himalayas. Theory holds that enhanced meltwater production may increase GLOF frequency, but has never been tested so far. The key challenge to test this notion are the high altitudes of >4000 m, at which lakes occur, making field work impractical. Moreover, flood waves can attenuate rapidly in mountain channels downstream, so that many GLOFs have likely gone unnoticed in past decades. Our knowledge on GLOFs is hence likely biased towards larger, destructive cases, which challenges a detailed quantification of their frequency and their response to atmospheric warming. Robustly quantifying the magnitude and frequency of GLOFs is essential for risk assessment and management along mountain rivers, not least to implement their return periods in building design codes.
Motivated by this limited knowledge of GLOF frequency and hazard, I developed an algorithm that efficiently detects GLOFs from satellite images. In essence, this algorithm classifies land cover in 30 years (~1988–2017) of continuously recorded Landsat images over the Himalayas, and calculates likelihoods for rapidly shrinking water bodies in the stack of land cover images. I visually assessed such detected tell-tale sites for sediment fans in the river channel downstream, a second key diagnostic of GLOFs. Rigorous tests and validation with known cases from roughly 10% of the Himalayas suggested that this algorithm is robust against frequent image noise, and hence capable to identify previously unknown GLOFs. Extending the search radius to the entire Himalayan mountain range revealed some 22 newly detected GLOFs. I thus more than doubled the existing GLOF count from 16 previously known cases since 1988, and found a dominant cluster of GLOFs in the Central and Eastern Himalayas (Bhutan and Eastern Nepal), compared to the rarer affected ranges in the North. Yet, the total of 38 GLOFs showed no change in the annual frequency, so that the activity of GLOFs per unit glacial lake area has decreased in the past 30 years. I discussed possible drivers for this finding, but left a further attribution to distinct GLOF-triggering mechanisms open to future research.
This updated GLOF frequency was the key input for assessing GLOF hazard for the entire Himalayan mountain belt and several subregions. I used standard definitions in flood hydrology, describing hazard as the annual exceedance probability of a given flood peak discharge [m3 s-1] or larger at the breach location. I coupled the empirical frequency of GLOFs per region to simulations of physically plausible peak discharges from all existing ~5,000 lakes in the Himalayas. Using an extreme-value model, I could hence calculate flood return periods. I found that the contemporary 100-year GLOF discharge (the flood level that is reached or exceeded on average once in 100 years) is 20,600+2,200/–2,300 m3 s-1 for the entire Himalayas. Given the spatial and temporal distribution of historic GLOFs, contemporary GLOF hazard is highest in the Eastern Himalayas, and lower for regions with rarer GLOF abundance. I also calculated GLOF hazard for some 9,500 overdeepenings, which could expose and fill with water, if all Himalayan glaciers have melted eventually. Assuming that the current GLOF rate remains unchanged, the 100-year GLOF discharge could double (41,700+5,500/–4,700 m3 s-1), while the regional GLOF hazard may increase largest in the Karakoram.
To conclude, these three stages–from GLOF detection, to analysing their frequency and estimating regional GLOF hazard–provide a framework for modern GLOF hazard assessment. Given the rapidly growing population, infrastructure, and hydropower projects in the Himalayas, this thesis assists in quantifying the purely climate-driven contribution to hazard and risk from GLOFs.