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New Analytical and Algorithmic Framework for Hybrid Wireless Localization
No full textIn recent years, due to the fast development of Wireless Sensor Networks in terms of size, energy and processing capability, and their growing penetration into new areas of application, wireless localization as one of the key features in this field has developed significant research interest amongst academia and industry community. Researchers and engineers conduct numerous attempts to design optimum wireless localization systems with high location precision and low energy consumption. A well known mechanism to improve accuracy is to rely on multiple types of information, which leads to hybrid or heterogeneous algorithms that have been shown to have advantages over algorithms admitting only a given type of input. For this reason, such algorithms have gained prominent importance in the recent years.
Based on the well theorem of Cram`er-Rao lower bound, in this work we introduce a new generic analytical framework in which the fundamental performance limit of hybrid localization algorithms can be easily addressed.
Furthermore, focusing on the design of new hybrid algorithms with the aim to improve localization accuracy and/or computational complexity, we introduce a new algorithmic framework from which many algorithms with different complexity/performance tradeoffs can be tailor designed for different scenarios of information availability. We revisit the super multidimensional scaling (SMDS) wireless localization algorithm first proposed a decade ago, recasting it onto the complex-domain. Under this new formulation, the edge kernel which carries both angle and distance information simultaneously and plays a central role in the SMDS algorithm, becomes a complex-valued rank-one matrix, resulting in a new complex-domain SMDS framework which yields several advantages over the original, including the elimination of redundancy, the enhancement of conditions to handle information erasure, and the possibility of designing a new hybrid algorithmic framework
Mass Spectrometrical Analysis of Flavonoids and Glucose Esters of Hydroxycinnamic Acids in Dietary Plants
No full textThe present work describes the development and use of various mass spectrometry-based analytical tools for the investigation of particular members of the two most prominent classes of polyphenols, namely flavonoids and hydroxycinnamic acids in dietary plant of great economical importance.
The first part is dedicated to the investigation of the polyphenolic fraction of cocoa. Both top down and a bottom up approaches were used in the investigation. In the top down approach, methanolic extracts of raw fermented cocoa beans from different origins were analyzed for the first time in literature by Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS. With approximately 11 000 peaks, cocoa was shown to be one of the most complex organic mixtures ever analyzed. In the bottom up approach, the methanolic extracts were analyzed by HPLC-MSn. The optimized method revealed a greater extract complexity than previously reported and allowed the identification of novel compounds.
The second part is dedicated to the investigation of glycosylated derivatives of hydroxycinnamic acids, with particular emphasis on hydroxycinnamoylglucose esters.
Authentic reference standards of hydroxycinnamoyl glucoses were selectively synthesized and subsequently used to develop a hierarchical HPLC-MSn scheme for the identification of all ten regioisomeric esters.
Different edible plant sources of great economical relevance, including berries and Solanaceae vegetables, were analyzed qualitatively and quantitatively for their hydroxycinnamoyl glucose contents. Furthermore, a quantitative HPLC-MS method was developed and validated using authentic reference standards and applied to over fourty different samples, thus providing the first set of quantitative data ever reported for this class of compounds.
The third part of the present work was dedicated to the in-depth study of the fragmentation mechanism of D-glucose, employing all 13C and all 2H labeled isotopomers
Antibody micropatterns as a tool to study MHC class I molecules
No full textPlanar surfaces with geometric protein patterns have been developed for various applications in biotechnology, such as orienting cells, arranging membrane proteins, or studying protein-ligand binding in massively parallel approaches. Geometric shapes and dimensions of protein patterns vary depending on the application. For the study of proteins in living cells, protein patterns in the micrometer range are commonly used; these are called protein micropatterns. Diverse lithography techniques have been used and were further developed to fabricate even complicated protein micropatterns on various surfaces. One of the first techniques to immobilize proteins in geometric patterns on glass surfaces was microcontact printing, which is a rather simple stamping approach that immobilizes proteins by physical absorption onto surfaces.
MHC class I are peptide receptors that present the cell´s proteome at the cell surface to T cells. They thus play an essential role in the adaptive immune response against cells that are infected by viruses, bacteria, or that carry tumorigenic mutations. We have adapted the technology of protein micropatterns to the field of MHC class I and have used microcontact printing to immobilize anti-MHC class I antibodies on glass surfaces to develop an MHC class I capture assay. The development of this assay consisted of optimization and trial experiments; they finally established a robust assay that can be used to specifically capture MHC class I in living cells.
In the field of MHC class I antigen presentation, we have identified two applications for the capture assay. First, a novel peptide binding assay was developed that allows for the monitoring of specific peptide binding to captured MHC class I in living cells. Further development of the assay led to the finding that the use of conformation-specific antibodies allows for differential capture of different structural forms of MHC class I. Excitingly, this enables the investigation of conformation-s
Structure-Activity Relationship of Polyoxopalladates as Hydrogenation Catalysts & Synthesis and Structural Characterization of Thallium-Containing Polyoxometalates
No full textPolyoxometalates (POMs) are a well-known class of discrete, anionic, metal-oxo clusters comprising early transition metals in high oxidation states. The structural and compositional variety is unmatched, and hence, such compounds are of interest in many different areas such as catalysis, medicine, magnetism and materials science. However, POMs exclusively based on d8 metal centers (PdII, PtIII, and AuIII) as addenda have undergone a recent renaissance – in particular polyoxopalladates(II). These noble metal-based heterogeneous catalysts represent a promising platform. The first part of this work focuses on investigating the structure-activity relationship of polyoxopalladates as hydrogenation catalysts (industrial project with ExxonMobil Chemical Europe Inc.). The second part of this thesis focuses on the synthesis of novel thallium-containing POMs (academic project)
Novel approaches to identify small molecules modulating E.coli TolC protein function
No full textThe urge of new strategies to overcome the world wide health problem of antibiotic resistance induced researchers as well governmental and private institution to come together to increase the medical and scientific knowledge on this topic.
This PhD project is part of the ITN Translocation, whose aim was to investigate the molecular and cellular mechanism at the basis of influx and efflux processes in gram-negative bacteria. The work behind the scientific advances reached during my 3-year-journey has been accomplished mainly between the Fraunhofer IME ScreeningPort in Hamburg and the Jacobs University Bremen, enriched by external collaborations with the University of Frankfurt and the Helmholtz Center for Infection Research.
Through an interdisciplinary approach, from in silico studies to biophysical characterization in vitro, small molecules hits to be developed as efflux pump inhibitors (EPIs) were identified. In particular, these compounds were shown to bind TolC, part of the major efflux systems in E.coli, in docking studies targeting an acidic pocket present in the periplasmic tip of the channel; to selectively bind TolCWT against a recombinant version, where key residues in the target site are mutated, in a biophysical setup allowing the determination of binding constant; to modulate ion current in reconstituted TolCWT in single-channel electrophysiology measurements.
Overall, the findings reported in this PhD thesis increase the knowledge of the biophysical characteristics of TolC through the use of cutting-edge methods and technologies, in particular in the field of membrane channels, and allowed the identification of promising compounds hits to support the development of EPIs to be employed as adjuvants in antimicrobial therapies
Preparation of polymer/clay hybrid encapsulation for barrier applications controlled by Hansen Solubility Parameters
No full textBarrier materials play important roles in modern food packaging or as a protection of electronics/metals against water permeation. There are often a combination of permeable and impermeable materials and can be divided into inorganic coatings, multilayer structures or nanocomposites. Impermeable layered materials can play an important role in such composites. Studies have shown that layer materials can have a high impact on nanocomposite-based barrier applications, described by the tortuous path model.
In this work, 2D materials (organophilic fluoromica, graphene and molybdenum disulfide (MoS2)) have been used to prepare such inorganic coatings and nanocomposites. Nevertheless, for a high impact, complete delamination (exfoliation) is needed for each particle into separate layers. Exfoliation needs to be energetically favorable, which means that interface interactions must be precisely adjusted between 2D material and dispersant/matrix. Such energetically favorable systems can be described by there surface energies via Hansen Solubility Parameters (HSP). Those parameters are known for more than 1200 materials like solvents, polymers, and optical absorbing materials, such as graphene or MoS2.
I, therefore, have investigated whether it is possible to determine HSP of organophilic fluoromica. The results have shown, that experimental determinate HSP are more accurate than those calculated theoretically, using group-contribution approach. Such precise HSP values are important for the prediction of dispersion interactions of those fluoromicas with dispersants and polymers. Furthermore, I have investigated whether such HSP values have an impact on barrier applications.
The result of this work shows, that experimentally determined HSP are a helpful tool for selecting suitable dispersants and 2D materials to prepare favorable multilayer structures or nanocomposites in specific matrices. This approach is beneficial to functional coating and adhesive applications
A Consistent Method for Learning OOMs from Asymptotically Stationary Time Series Data Containing Missing Values
No full textIn the traditional framework of spectral learning of stochastic time series models, model parameters are estimated based on trajectories of fully recorded observations. However, real-world time series data often contain missing values, and worse, the distributions of missingness events over time are often not independent of the visible process. Recently, a spectral OOM learning algorithm for time series with missing data was introduced and proved to be consistent, albeit under quite strong conditions. Here we refine the algorithm and prove that the original strong conditions can be very much relaxed. We validate our theoretical findings by numerical experiments, showing that the algorithm can consistently handle missingness patterns whose dynamic interacts with the visible process
Reverse engineering of Saccharomyces cerevisiae CEN.PK strains for growth in synthetic glycerol medium and the characterization of glycerol positive promoters
No full textIn the past decade, the use of biodiesel as a fuel was considered as an alternative to reduce reliance on fossil resources and the resulting greenhouse effect. During biodiesel production, glycerol is generated as a by-product in excess. The economy of biodiesel industry is thus expected to benefit from the valorization of glycerol. One of the valorization avenues is employing glycerol as a substrate in microbial bioprocesses.
The yeast Saccharomyces cerevisiae is a popular cell-factory in industrial biotechnology and a suitable chassis in synthetic biology. This status is the result of many factors, such as the vast knowledge available regarding the physiology and genetics of this species, the intense experience with this organism in industrial fermentations, S. cerevisiae’s robustness under process conditions, and the ease to genetically engineer this microorganism.
Using glycerol as a carbon source for growing S. cerevisiae would bring about several assets for yeast-based bioprocesses. On one hand, glycerol does not trigger Crabtree effect in S. cerevisiae, which is in favor of bioprocesses aiming at high biomass production or biomass-associated products. On the other hand, glycerol is more reduced than sugars, which would be an advantage for the production of small-molecule compounds with a high degree of reduction.
One of the main objectives of this thesis was to better understand glycerol utilization in S. cerevisiae and identify the underlying determinants for the better growth of certain strains on glycerol. The major focus was set on improving strains of the popular CEN.PK strain family. Another goal of the thesis was to provide thoroughly characterized S. cerevisiae promoters for the given cultivation conditions. Such information is required for achieving optimal metabolic engineering outcomes if glycerol is to be used as the sole carbon source
Finding sustainability: Advancing multiple methods to apply the social-ecological systems framework
No full textThe social-ecological systems framework (SESF) was proposed by Elinor Ostrom in 2007 as a diagnostic tool to examine what influences collective action in the commons by identifying the social and ecological variables which interact and shape sustainability outcomes. Many have since cited the framework as a useful conceptual tool. However, substantially less literature has applied the framework empirically or examined the methodological challenges for using the framework. Rigorous exploration and analysis of the different methods and challenges for applying the framework and its conceptual development are largely absent in the literature, but are needed to guide future progress. I argue that a primary barrier for future research using the framework is a lack of knowledge on different methods and challenges for applying it. This thesis is a compilation of eight research articles building this knowledge. I explore different concepts and methods to continue building a research program with the SESF. The thesis is split into four parts. In Part 1: Introduction, I provide an overview of commons scholarship, and argue that the development of new interdisciplinary methodologies have been an essential feature of past progress and thus need to be an integral feature the SESF’s progress. In Part 2: Context and Concepts, I present a review article on the field of tropical marine science, to situate the context of this thesis. Two articles then explore conceptual development of the SESF, linking the framework to the closely associated concepts of ecosystem services and sustainability science. In Part 3: Empirical Research, the core of this thesis is presented. Each of the four articles applies the SESF in a different way in three small-scale fisheries cases and one pond aquaculture case. Finally, in Part 4: Synthesis and Conclusions, I provide an article which reviews all the existing literature applying the SESF to orient the contributions of this thesis
Experimental evidence of factors influencing voluntary contributions to marine conservation
No full textConserving the Earth’s natural resources is of great importance to the future of all living things. The science behind conservation is dominated by the natural sciences although it is clear that human behavior is at the root of most environmental degradation problems as well as the solutions. The behavioral social sciences offer relevant theory and valuable methodological tools to understand human behavior. Yet, research on human behavior remains underrepresented in the conservation sciences. Voluntary contributions are widely accepted mechanisms for promoting conservation and for measuring individual economic behavior. This thesis aims to address several aspects of human behavior and how they relate to contributions to marine conservation. This thesis consists of an introduction followed by three self-contained chapters and a conclusion.
Proximate stressors such as destructive fishing are key drivers damaging coral reef public goods. Conservation strategies that marshal local action and are tailored to the preferences of the target group are thus needed to sustain coral resources. Research 1 uses data from field experiments with a fishing community in Indonesia to test economic theory regarding preferences for giving time and money to environmental and other charitable causes. Each person is subject to one of four treatments: monetary donation, monetary donation match, volunteer time donation, and volunteer time donation match. Contrasting with the existing literature, we find that participants give significantly more when donating money compared to time. We also find that matching donations increases the percent of people giving but does not increase the amount donated. This research furthers our understanding of what motivates resource users in a developing country to contribute to the provision of public goods.
Using data collected from the same study population, research 2 examines the effect of social and psychographic characteristics on giving to public good