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We consider a system of infinitely many hard balls in Rd undergoing Brownian motions and submitted to a smooth pair potential. It is modelized by an infinite-dimensional Stochastic Differential Equation with a local time term. We prove that the set of all equilibrium measures, solution of a Detailed Balance Equation, coincides with the set of canonical Gibbs measures associated to the hard core potential added to the smooth interaction potential.
We consider an infinite system of non overlaping globules undergoing Brownian motions in R3. The term globules means that the objects we are dealing with are spherical, but with a radius which is random and time-dependent. The dynamics is modelized by an infinitedimensional Stochastic Differential Equation with local time. Existence and uniqueness of a strong solution is proven for such an equation with fixed deterministic initial condition. We also find a class of reversible measures.
We consider an infinite system of hard balls in Rd undergoing Brownian motions and submitted to a pair potential with infinite range and quasi polynomial decay. It is modelized by an infinite-dimensional Stochastic Differential Equation with an infinite-dimensional local time term. Existence and uniqueness of a strong solution is proven for such an equation with deterministic initial condition. We also show that the set of all equilibrium measures, solution of a Detailed Balance Equation, coincides with the set of canonical Gibbs measures associated to the hard core potential.
Solar-like stars maintain their magnetic fields thanks to a dynamo mechanism. The Babcock-Leighton dynamo is one possible dynamo that has the particularity to require magnetic flux tubes. Magnetic flux tubes are assumed to form at the bottom of the convective zone and rise buoyantly to the surface. A delayed dynamo model has been suggested, where the delay accounts for the rise time of the magnetic flux tubes; a time, that has been ignored by former studies.
The present thesis aims to study the applicability of the flux tube/Babcock-Leighton dynamo to other stars. To do so, we attempt to constrain the rise time of magnetic flux tubes thanks to the first fully compressible MHD simulations of rising magnetic flux tubes in stratified rotating spherical shells.
Such simulations are limited to an unrealistic parameter space, therefore, a scaling relation is required to scale the results to realistic physical regimes. We extended earlier works on 2D scaling relations and derived a general scaling law valid for both 2D and 3D. We then carried out two large series of numerical experiments and verified that the scaling law we have derived indeed applies to the fully non-linear case. It allowed us to extract a constraint for the rise time of magnetic flux tubes that is valid for any solar-like star. We finally introduced this constraint to a delayed dynamo model.
By carrying out simulations of a mean-field, delayed, flux tube/Babcock-Leighton dynamo, we were able to identify a new dynamo regime resulting from the delay. This regime requires delays about an entire cycle and exhibits subequipartition magnetic activity. Revealing this new regime shows that even for long delays the flux tube/Babcock-Leighton dynamo can still deliver non-decaying solutions and remains a good candidate for a wide range of solar-like stars.
In this work the human AOX1 was characterized and detailed aspects regarding the expression, the enzyme kinetics and the production of reactive oxygen species (ROS) were investigated. The hAOX1 is a cytosolic enzyme belonging to the molybdenum hydroxylase family. Its catalytically active form is a homodimer with a molecular weight of 300 kDa. Each monomer (150 kDa) consists of three domains: a N-terminal domain (20 kDa) containing two [2Fe-2S] clusters, a 40 kDa intermediate domain containing a flavin adenine dinucleotide (FAD), and a C-terminal domain (85 kDa) containing the substrate binding pocket and the molybdenum cofactor (Moco). The hAOX1 has an emerging role in the metabolism and pharmacokinetics of many drugs, especially aldehydes and N- heterocyclic compounds.
In this study, the hAOX1 was hetereogously expressed in E. coli TP1000 cells, using a new codon optimized gene sequence which improved the expressed protein yield of around 10-fold compared to the previous expression systems for this enzyme. To increase the catalytic activity of hAOX1, an in vitro chemical sulfuration was performed to favor the insertion of the equatorial sulfido ligand at the Moco with consequent increased enzymatic activity of around 10-fold. Steady-state kinetics and inhibition studies were performed using several substrates, electron acceptors and inhibitors. The recombinant hAOX1 showed higher catalytic activity when molecular oxygen was used as electron acceptor. The highest turn over values were obtained with phenanthridine as substrate. Inhibition studies using thioridazine (phenothiazine family), in combination with structural studies performed in the group of Prof. M.J. Romão, Nova Universidade de Lisboa, showed a new inhibition site located in proximity of the dimerization site of hAOX1. The inhibition mode of thioridazine resulted in a noncompetitive inhibition type. Further inhibition studies with loxapine, a thioridazine-related molecule, showed the same type of inhibition. Additional inhibition studies using DCPIP and raloxifene were carried out.
Extensive studies on the FAD active site of the hAOX1 were performed. Twenty new hAOX1 variants were produced and characterized. The hAOX1 variants generated in this work were divided in three groups: I) hAOX1 single nucleotide polymorphisms (SNP) variants; II) XOR- FAD loop hAOX1 variants; III) additional single point hAOX1 variants. The hAOX1 SNP variants G46E, G50D, G346R, R433P, A439E, K1231N showed clear alterations in their catalytic activity, indicating a crucial role of these residues into the FAD active site and in relation to the overall reactivity of hAOX1.
Furthermore, residues of the bovine XOR FAD flexible loop (Q423ASRREDDIAK433) were introduced in the hAOX1. FAD loop hAOX1 variants were produced and characterized for their stability and catalytic activity. Especially the variants hAOX1 N436D/A437D/L438I, N436D/A437D/L438I/I440K and Q434R/N436D/A437D/L438I/I440K showed decreased catalytic activity and stability. hAOX1 wild type and variants were tested for reactivity toward NADH but no reaction was observed.
Additionally, the hAOX1 wild type and variants were tested for the generation of reactive oxygen species (ROS). Interestingly, one of the SNP variants, hAOX1 L438V, showed a high ratio of superoxide prodction. This result showed a critical role for the residue Leu438 in the mechanism of oxygen radicals formation by hAOX1. Subsequently, further hAOX1 variants having the mutated Leu438 residue were produced. The variants hAOX1 L438A, L438F and L438K showed superoxide overproduction of around 85%, 65% and 35% of the total reducing equivalent obtained from the substrate oxidation.
The results of this work show for the first time a characterization of the FAD active site of the hAOX1, revealing the importance of specific residues involved in the generation of ROS and effecting the overall enzymatic activity of hAOX1. The hAOX1 SNP variants presented here indicate that those allelic variations in humans might cause alterations ROS balancing and clearance of drugs in humans.
The hyperthermal events of the Cenozoic, including the Paleocene-Eocene Thermal Maximum, provide an opportunity to investigate the potential effects of climate warming on marine ecosystems. Here, we examine the shallow benthic marine communities preserved in the late Cretaceous to Eocene strata on the Gulf Coastal Plain (United States). In stark contrast to the ecological shifts following the end-Cretaceous mass extinction, our data show that the early Cenozoic hyperthermals did not have a long-term impact on the generic diversity nor composition of the Gulf Coastal Plain molluscan communities. We propose that these communities were resilient to climate change because molluscs are better adapted to high temperatures than other taxa, as demonstrated by their physiology and evolutionary history. In terms of resilience, these communities differ from other shallow-water carbonate ecosystems, such as reef communities, which record significant changes during the early Cenozoic hyperthermals. These data highlight the strikingly different responses of community types, i.e., the almost imperceptible response of molluscs versus the marked turnover of foraminifera and reef faunas. The impact on molluscan communities may have been low because detrimental conditions did not devastate the entire Gulf Coastal Plain, allowing molluscs to rapidly recolonise vacated areas once harsh environmental conditions ameliorated.
X-rays are integral to furthering our knowledge of exoplanetary systems. In this work we discuss the use of X-ray observations to understand star-planet interac- tions, mass-loss rates of an exoplanet’s atmosphere and the study of an exoplanet’s atmospheric components using future X-ray spectroscopy.
The low-mass star GJ 1151 was reported to display variable low-frequency radio emission, which is an indication of coronal star-planet interactions with an unseen exoplanet. In chapter 5 we report the first X-ray detection of GJ 1151’s corona based on XMM-Newton data. Averaged over the observation, we detect the star with a low coronal temperature of 1.6 MK and an X-ray luminosity of LX = 5.5 × 1026 erg/s. This is compatible with the coronal assumptions for a sub-Alfvénic star- planet interaction origin of the observed radio signals from this star.
In chapter 6, we aim to characterise the high-energy environment of known ex- oplanets and estimate their mass-loss rates. This work is based on the soft X-ray instrument on board the Spectrum Roentgen Gamma (SRG) mission, eROSITA, along with archival data from ROSAT, XMM-Newton, and Chandra. We use these four X-ray source catalogues to derive X-ray luminosities of exoplanet host stars in the 0.2-2 keV energy band. A catalogue of the mass-loss rates of 287 exoplan- ets is presented, with 96 of these planets characterised for the first time using new eROSITA detections. Of these first time detections, 14 are of transiting exoplanets that undergo irradiation from their host stars that is of a level known to cause ob- servable evaporation signals in other systems, making them suitable for follow-up observations.
In the next generation of space observatories, X-ray transmission spectroscopy of an exoplanet’s atmosphere will be possible, allowing for a detailed look into the atmospheric composition of these planets. In chapter 7, we model sample spectra using a toy model of an exoplanetary atmosphere to predict what exoplanet transit observations with future X-ray missions such as Athena will look like. We then estimate the observable X-ray transmission spectrum for a typical Hot Jupiter-type exoplanet, giving us insights into the advances in X-ray observations of exoplanets in the decades to come.
Hybrid nanomaterials offer the combination of individual properties of different types of nanoparticles. Some strategies for the development of new nanostructures in larger scale rely on the self-assembly of nanoparticles as a bottom-up approach. The use of templates provides ordered assemblies in defined patterns. In a typical soft-template, nanoparticles and other surface-active agents are incorporated into non-miscible liquids. The resulting self-organized dispersions will mediate nanoparticle interactions to control the subsequent self-assembly. Especially interactions between nanoparticles of very different dispersibility and functionality can be directed at a liquid-liquid interface.
In this project, water-in-oil microemulsions were formulated from quasi-ternary mixtures with Aerosol-OT as surfactant. Oleyl-capped superparamagnetic iron oxide and/or silver nanoparticles were incorporated in the continuous organic phase, while polyethyleneimine-stabilized gold nanoparticles were confined in the dispersed water droplets. Each type of nanoparticle can modulate the surfactant film and the inter-droplet interactions in diverse ways, and their combination causes synergistic effects. Interfacial assemblies of nanoparticles resulted after phase-separation. On one hand, from a biphasic Winsor type II system at low surfactant concentration, drop-casting of the upper phase afforded thin films of ordered nanoparticles in filament-like networks. Detailed characterization proved that this templated assembly over a surface is based on the controlled clustering of nanoparticles and the elongation of the microemulsion droplets. This process offers versatility to use different nanoparticle compositions by keeping the surface functionalization, in different solvents and over different surfaces. On the other hand, a magnetic heterocoagulate was formed at higher surfactant concentration, whose phase-transfer from oleic acid to water was possible with another auxiliary surfactant in ethanol-water mixture. When the original components were initially mixed under heating, defined oil-in-water, magnetic-responsive nanostructures were obtained, consisting on water-dispersible nanoparticle domains embedded by a matrix-shell of oil-dispersible nanoparticles.
Herein, two different approaches were demonstrated to form diverse hybrid nanostructures from reverse microemulsions as self-organized dispersions of the same components. This shows that microemulsions are versatile soft-templates not only for the synthesis of nanoparticles, but also for their self-assembly, which suggest new approaches towards the production of new sophisticated nanomaterials in larger scale.
In my doctoral thesis, I examine continuous gravity measurements for monitoring of the geothermal site at Þeistareykir in North Iceland. With the help of high-precision superconducting gravity meters (iGravs), I investigate underground mass changes that are caused by operation of the geothermal power plant (i.e. by extraction of hot water and reinjection of cold water). The overall goal of this research project is to make a statement about the sustainable use of the geothermal reservoir, from which also the Icelandic energy supplier and power plant operator Landsvirkjun should benefit.
As a first step, for investigating the performance and measurement stability of the gravity meters, in summer 2017, I performed comparative measurements at the gravimetric observatory J9 in Strasbourg. From the three-month gravity time series, I examined calibration, noise and drift behaviour of the iGravs in comparison to stable long-term time series of the observatory superconducting gravity meters. After preparatory work in Iceland (setup of gravity stations, additional measuring equipment and infrastructure, discussions with Landsvirkjun and meetings with the Icelandic partner institute ISOR), gravity monitoring at Þeistareykir was started in December 2017. With the help of the iGrav records of the initial 18 months after start of measurements, I carried out the same investigations (on calibration, noise and drift behaviour) as in J9 to understand how the transport of the superconducting gravity meters to Iceland may influence instrumental parameters.
In the further course of this work, I focus on modelling and reduction of local gravity contributions at Þeistareykir. These comprise additional mass changes due to rain, snowfall and vertical surface displacements that superimpose onto the geothermal signal of the gravity measurements. For this purpose, I used data sets from additional monitoring sensors that are installed at each gravity station and adapted scripts for hydro-gravitational modelling. The third part of my thesis targets geothermal signals in the gravity measurements.
Together with my PhD colleague Nolwenn Portier from France, I carried out additional gravity measurements with a Scintrex CG5 gravity meter at 26 measuring points within the geothermal field in the summers of 2017, 2018 and 2019. These annual time-lapse gravity measurements are intended to increase the spatial coverage of gravity data from the three continuous monitoring stations to the entire geothermal field. The combination of CG5 and iGrav observations, as well as annual reference measurements with an FG5 absolute gravity meter represent the hybrid gravimetric monitoring method for Þeistareykir. Comparison of the gravimetric data to local borehole measurements (of groundwater levels, geothermal extraction and injection rates) is used to relate the observed gravity changes to the actually extracted (and reinjected) geothermal fluids. An approach to explain the observed gravity signals by means of forward modelling of the geothermal production rate is presented at the end of the third (hybrid gravimetric) study. Further modelling with the help of the processed gravity data is planned by Landsvirkjun. In addition, the experience from time-lapse and continuous gravity monitoring will be used for future gravity measurements at the Krafla geothermal field 22 km south-east of Þeistareykir.
The end of the Cold War opened a window for a new era in world security. Instead of rising to this extraordinary occasion, the United States has adopted a regressive Great Power approach to military security. Rather than promote 'win-win' solutions for peace, security, disarmament, and democracy, it treats international security as a 'zero-sum' game. This article discusses examples in the areas of military spending, military research and development, and arms production and export. It also looks at US policy regarding the use of force, including the role of the United Nations, military intervention in other nations, military alliances, and multilateral military action. In conclusion, the article comments on whether we can expect more constructive action under a new administration and congress.
Multiple health behaviour change (MHBC) represents one of the best ways to prevent reoccurrence of cardiovascular events. However, few
individuals with cardiovascular diseases engage in this process. The
present study examined the role of compensatory health beliefs (CHB;
i.e., belief that a healthy behaviour compensates an unhealthy one)as
a drag to engagement in this process. Some studies have shown that
CHBs predict intention to engage in healthy behaviours, but no study
has investigated CHBs in individuals who actually need to change
multiple health behaviours. The goal was to better understand the
role of CHBs in intentions formation process among individuals with
cardiac diseases in an MHBC context. One hundred and four patients
completed a questionnaire at the beginning of their cardiac rehabilitation program. Results showed that: (1) CHBs negatively predicted intentions (2) but only for participants with high self-efficacy or low risk perception; (3) CHBs predictions differed depending on the nature of the compensating behaviour, and were more predictive when medication intake was the compensating one. Findings only partially confirmed previous research conducted on healthy individuals who were not in an MHBC process, and emphasized the importance of considering CHBs for individuals in this process.
Cardiac valves are essential for the continuous and unidirectional flow of blood throughout the body. During embryonic development, their formation is strictly connected to the mechanical forces exerted by blood flow. The endocardium that lines the interior of the heart is a specialized endothelial tissue and is highly sensitive to fluid shear stress. Endocardial cells harbor a signal transduction machinery required for the translation of these forces into biochemical signaling, which strongly impacts cardiac morphogenesis and physiology. To date, we lack a solid understanding on the mechanisms by which endocardial cells sense the dynamic mechanical stimuli and how they trigger different cellular responses. In the zebrafish embryo, endocardial cells at the atrioventricular canal respond to blood flow by rearranging from a monolayer to a double-layer, composed of a luminal cell population subjected to blood flow and an abluminal one that is not exposed to it. These early morphological changes lead to the formation of an immature valve leaflet. While previous studies mainly focused on genes that are positively regulated by shear stress, the mechanisms regulating cell behaviors and fates in cells that lack the stimulus of blood flow are largely unknown. One key discovery of my work is that the flow-sensitive Notch receptor and Krüppel-like factor (Klf) 2, one of the best characterized flow-regulated transcriptional factors, are activated by shear stress but that they function in two parallel signal transduction pathways. Each of these two pathways is essential for the rearrangement of atrioventricular cells into an immature double-layered valve leaflets. A second key discovery of my study is the finding that both Notch and Klf2 signaling negatively regulate the expression of the angiogenesis receptor Vegfr3/Flt4, which becomes restricted to abluminal endocardial cells of the valve leaflet. Within these cells, Flt4 downregulates the expressions of the cell adhesion proteins Alcam and VE-cadherin. A loss of Flt4 causes abluminal endocardial cells to ectopically express Notch, which is normally restricted to luminal cells, and impairs valve morphology. My study suggests that abluminal endocardial cells that do not experience mechanical stimuli loose Notch expression and this triggers expression of Flt4. In turn, Flt4 negatively regulates Notch on the abluminal side of the valve leaflet. These antagonistic signaling activities and fine-tuned gene regulatory mechanisms ultimately shape cardiac valve leaflets by inducing unique differences in the fates of endocardial cells.
We present a setup combining a liquid flatjet sample delivery and a MHz laser system for time-resolved soft X-ray absorption measurements of liquid samples at the high brilliance undulator beamline UE52-SGM at Bessy II yielding unprecedented statistics in this spectral range. We demonstrate that the efficient detection of transient absorption changes in transmission mode enables the identification of photoexcited species in dilute samples. With iron(II)-trisbipyridine in aqueous solution as a benchmark system, we present absorption measurements at various edges in the soft X-ray regime. In combination with the wavelength tunability of the laser system, the set-up opens up opportunities to study the photochemistry of many systems at low concentrations, relevant to materials sciences, chemistry, and biology.
This project describes the nominal, verbal and ‘truncation’ systems of Awing and explains the syntactic and semantic functions of the multifunctional l<-><-> (LE) morpheme in copular and wh-focused constructions. Awing is a Bantu Grassfields language spoken in the North West region of Cameroon. The work begins with morphological processes viz. deverbals, compounding, reduplication, borrowing and a thorough presentation of the pronominal system and takes on verbal categories viz. tense, aspect, mood, verbal extensions, negation, adverbs and triggers of a homorganic N(asal)-prefix that attaches to the verb and other verbal categories. Awing grammar also has a very unusual phenomenon whereby nouns and verbs take long and short forms. A chapter entitled truncation is dedicated to the phenomenon. It is observed that the truncation process does not apply to bare singular NPs, proper names and nouns derived via morphological processes. On the other hand, with the exception of the 1st person non-emphatic possessive determiner and the class 7 noun prefix, nouns generally take the truncated form with modifiers (i.e., articles, demonstratives and other possessives). It is concluded that nominal truncation depicts movement within the DP system (Abney 1987). Truncation of the verb occurs in three contexts: a mass/plurality conspiracy (or lattice structuring in terms of Link 1983) between the verb and its internal argument (i.e., direct object); a means to align (exhaustive) focus (in terms of Fery’s 2013), and a means to form polar questions.
The second part of the work focuses on the role of the LE morpheme in copular and wh-focused clauses. Firstly, the syntax of the Awing copular clause is presented and it is shown that copular clauses in Awing have ‘subject-focus’ vs ‘topic-focus’ partitions and that the LE morpheme indirectly relates such functions. Semantically, it is shown that LE does not express contrast or exhaustivity in copular clauses. Turning to wh-constructions, the work adheres to Hamblin’s (1973) idea that the meaning of a question is the set of its possible answers and based on Rooth’s (1985) underspecified semantic notion of alternative focus, concludes that the LE morpheme is not a Focus Marker (FM) in Awing: LE does not generate or indicate the presence of alternatives (Krifka 2007); The LE morpheme can associate with wh-elements as a focus-sensitive operator with semantic import that operates on the focus alternatives by presupposing an exhaustive answer, among other notions. With focalized categories, the project further substantiates the claim in Fominyam & Šimík (2017), namely that exhaustivity is part of the semantics of the LE morpheme and not derived via contextual implicature, via a number of diagnostics. Hence, unlike in copular clauses, the LE morpheme with wh-focused categories is analysed as a morphological exponent of a functional head Exh corresponding to Horvath's (2010) EI (Exhaustive Identification). The work ends with the syntax of verb focus and negation and modifies the idea in Fominyam & Šimík (2017), namely that the focalized verb that associates with the exhaustive (LE) particle is a lower copy of the finite verb that has been moved to Agr. It is argued that the LE-focused verb ‘cluster’ is an instantiation of adjunction. The conclusion is that verb doubling with verb focus in Awing is neither a realization of two copies of one and the same verb (Fominyam and Šimík 2017), nor a result of a copy triggered by a focus marker (Aboh and Dyakonova 2009). Rather, the focalized copy is said to be merged directly as the complement of LE forming a type of adjoining cluster.
According to Aikhenvald (2007:5), descriptive linguistics or linguistic
fieldwork “ideally involves observing the language as it is used,
becoming a member of the community, and often being adopted into
the kinship system”. Descriptive linguistics therefore differs from
theoretical linguistics in that while the former seeks to describe natural
languages as they are used, the latter, other than describing, attempts
to give explanations on how or why language phenomena behave in
certain ways. Thus, I will abstract away from any preconceived ideas
on how sentences ought to be in Awing and take the linguist/reader
through focus and interrogative constructions to get a feeling of how
the Awing people interact verbally.
»Plus outre« – immer weiter
(2022)
The complete mitochondrial genome of the common vole, Microtus arvalis (Rodentia: Arvicolinae)
(2018)
The common vole, Microtus arvalis belongs to the genus Microtus in the subfamily Arvicolinae. In this study, the complete mitochondrial genome of M. arvalis was recovered using shotgun sequencing and an iterative mapping approach using three related species. Phylogenetic analyses using the sequence of 21 arvicoline species place the common vole as a sister species to the East European vole (Microtus levis), but as opposed to previous results we find no support for the recognition of the genus Neodon within the subfamily Arvicolinae, as this is, as well as the genus Lasiopodomys, found within the Microtus genus.
Understanding how organisms adapt to their local environment is a major focus of evolutionary biology. Local adaptation occurs when the forces of divergent natural selection are strong enough compared to the action of other evolutionary forces. An improved understanding of the genetic basis of local adaptation can inform about the evolutionary processes in populations and is of major importance because of its relevance to altered selection pressures due to climate change. So far, most insights have been gained by studying model organisms, but our understanding about the genetic basis of local adaptation in wild populations of species with little genomic resources is still limited.
With the work presented in this thesis I therefore set out to provide insights into the genetic basis of local adaptation in populations of two voles species: the common vole (Microtus arvalis) and the bank vole (Myodes glareolus). Both voles species are small mammals, they have a high evolutionary potential compared to their dispersal capabilities and are thus likely to show genetic responses to local conditions, moreover, they have a wide distribution in which they experience a broad range of different environmental conditions, this makes them an ideal species to study local adaptation.
The first study focused on producing a novel mitochondrial genome to facilitate further research in M. arvalis. To this end, I generated the first mitochondrial genome of M. arvalis using shotgun sequencing and an iterative mapping approach. This was subsequently used in a phylogenetic analysis that produced novel insights into the phylogenetic relationships of the Arvicolinae.
The following two studies then focused on the genetic basis of local adaptation using ddRAD-sequencing data and genome scan methods. The first of these involved sequencing the genomic DNA of individuals from three low-altitude and three high-altitude M. arvalis study sites in the Swiss Alps. High-altitude environments with their low temperatures and low levels of oxygen (hypoxia) pose considerable challenges for small mammals. With their small body size and proportional large body surface they have to sustain high rates of aerobic metabolism to support thermogenesis and locomotion, which can be restricted with only limited levels of oxygen available. To generate insights into high-altitude adaptation I identified a large number of single nucleotide polymorphisms (SNPs). These data were first used to identify high levels of differentiation between study sites and a clear pattern of population structure, in line with a signal of isolation by distance. Using genome scan methods, I then identified signals of selection associated with differences in altitude in genes with functions related to oxygen transport into tissue and genes related to aerobic metabolic pathways. This indicates that hypoxia is an important selection pressure driving local adaptation at high altitude in M. arvalis. A number of these genes were linked with high-altitude adaptation in other species before, which lead to the suggestion that high-altitude populations of several species have evolved in a similar manner as a response to the unique conditions at high altitude
The next study also involved the genetic basis of local adaptation, here I provided insights into climate-related adaptation in M. glareolus across its European distribution. Climate is an important environmental factor affecting the physiology of all organisms. In this study I identified a large number of SNPs in individuals from twelve M. glareolus populations distributed across Europe. I used these, to first establish that populations are highly differentiated and found a strong pattern of population structure with signal of isolation by distance. I then employed genome scan methods to identify candidate loci showing signals of selection associated with climate, with a particular emphasis on polygenic loci. A multivariate analysis was used to determine that temperature was the most important climate variable responsible for adaptive genetic variation among all variables tested. By using novel methods and genome annotation of related species I identified the function of genes of candidate loci. This showed that genes under selection have functions related to energy homeostasis and immune processes. Suggesting that M. glareolus populations have evolved in response to local temperature and specific local pathogenic selection pressures.
The studies presented in this thesis provide evidence for the genetic basis of local adaptation in two vole species across different environmental gradients, suggesting that the identified genes are involved in local adaptation. This demonstrates that with the help of novel methods the study of wild populations, which often have little genomic resources available, can provide unique insights into evolutionary processes.
Stimuli-promoted in situ formation of hydrogels with thiol/thioester containing peptide precursors
(2022)
Hydrogels are potential synthetic ECM-like substitutes since they provide functional and structural similarities compared to soft tissues. They can be prepared by crosslinking of macromolecules or by polymerizing suitable precursors. The crosslinks are not necessarily covalent bonds, but could also be formed by physical interactions such as π-π interactions, hydrophobic interactions, or H-bonding. On demand in situ forming hydrogels have garnered increased interest especially for biomedical applications over preformed gels due to the relative ease of in vivo delivery and filling of cavities. The thiol-Michael addition reaction provides a straightforward and robust strategy for in situ gel formation with its fast reaction kinetics and ability to proceed under physiological conditions. The incorporation of a trigger function into a crosslinking system becomes even more interesting since gelling can be controlled with stimulus of choice. The use of small molar mass crosslinker precursors with active groups orthogonal to thiol-Michael reaction type electrophile provides the opportunity to implement an on-demand in situ crosslinking without compromising the fast reaction kinetics.
It was postulated that short peptide sequences due to the broad range structural-function relations available with the different constituent amino acids, can be exploited for the realisation of stimuli-promoted in situ covalent crosslinking and gelation applications. The advantages of this system over conventional polymer-polymer hydrogel systems are the ability tune and predict material property at the molecular level.
The main aim of this work was to develop a simplified and biologically-friendly stimuli-promoted in situ crosslinking and hydrogelation system using peptide mimetics as latent crosslinkers. The approach aims at using a single thiodepsipeptide sequence to achieve separate pH- and enzyme-promoted gelation systems with little modification to the thiodepsipeptide sequence. The realization of this aim required the completion of three milestones.
In the first place, after deciding on the thiol-Michael reaction as an effective in situ crosslinking strategy, a thiodepsipeptide, Ac-Pro-Leu-Gly-SLeu-Leu-Gly-NEtSH (TDP) with expected propensity towards pH-dependent thiol-thioester exchange (TTE) activation, was proposed as a suitable crosslinker precursor for pH-promoted gelation system. Prior to the synthesis of the proposed peptide-mimetic, knowledge of the thiol-Michael reactivity of the would-be activated thiol moiety SH-Leu, which is internally embedded in the thiodepsipeptide was required. In line with pKa requirements for a successful TTE, the reactivity of a more acidic thiol, SH-Phe was also investigated to aid the selection of the best thiol to be incorporated in the thioester bearing peptide based crosslinker precursor. Using ‘pseudo’ 2D-NMR investigations, it was found that only reactions involving SH-Leu yielded the expected thiol-Michael product, an observation that was attributed to the steric hindrance of the bulkier nature of SH-Phe. The fast reaction rates and complete acrylate/maleimide conversion obtained with SH-Leu at pH 7.2 and higher aided the direct elimination of SH-Phe as a potential thiol for the synthesis of the peptide mimetic.
Based on the initial studies, for the pH-promoted gelation system, the proposed Ac-Pro-Leu-Gly-SLeu-Leu-Gly-NEtSH was kept unmodified. The subtle difference in pKa values between SH-Leu (thioester thiol) and the terminal cysteamine thiol from theoretical conditions should be enough to effect a ‘pseudo’ intramolecular TTE. In polar protic solvents and under basic aqueous conditions, TDP successfully undergoes a ‘pseudo’ intramolecular TTE reaction to yield an α,ω-dithiol tripeptide, HSLeu-Leu-Gly-NEtSH. The pH dependence of thiolate ion generation by the cysteamine thiol aided the incorporation of the needed stimulus (pH) for the overall success of TTE (activation step) – thiol-Michael addition (crosslinking) strategy.
Secondly, with potential biomedical applications in focus, the susceptibility of TDP, like other thioesters, to intermolecular TTE reaction was probed with a group of thiols of varying thiol pKa values, since biological milieu characteristically contain peptide/protein thiols. L-cysteine, which is a biologically relevant thiol, and a small molecular weight thiol, methylthioglycolate both with relatively similar thiol pKa, values, led to an increase concentration of the dithiol crosslinker when reacted with TDP. In the presence of acidic thiols (p-NTP and 4MBA), a decrease in the dithiol concentration was observed, an observation that can be attributed to the inability of the TTE tetrahedral intermediate to dissociate into exchange products and is in line with pKa requirements for successful TTE reaction. These results additionally makes TDP more attractive and the potentially the first crosslinker precursor for applications in biologically relevant media.
Finally, the ability of TDP to promote pH-sensitive in situ gel formation was probed with maleimide functionalized 4-arm polyethylene glycol polymers in tris-buffered media of varying pHs. When a 1:1 thiol: maleimide molar ratio was used, TDP-PEG4MAL hydrogels formed within 3, 12 and 24 hours at pH values of 8.5, 8.0 and 7.5 respectively. However, gelation times of 3, 5 and 30 mins were observed for the same pH trend when the thiol: maleimide molar was increased to 2:1.
A direct correlation of thiol content with G’ of the gels at each pH could also be drawn by comparing gels with thiol: maleimide ratios of 1:1 to those with 2:1 thiol: maleimide mole ratios. This is supported by the fact that the storage modulus (G') is linearly dependent on the crosslinking density of the polymer. The values of initial G′ for all gels ranged between (200 – 5000 Pa), which falls in the range of elasticities of certain tissue microenvironments for example brain tissue 200 – 1000 Pa and adipose tissue (2500 – 3500 Pa).
Knowledge so far gained from the study on the ability to design and tune the exchange reaction of thioester containing peptide mimetic will give those working in the field further insight into the development of new sequences tailored towards specific applications.
TTE substrate design using peptide mimetic as presented in this work has revealed interesting new insights considering the state-of-the-art. Using the results obtained as reference, the strategy provides a possibility to extend the concept to the controlled delivery of active molecules needed for other robust and high yielding crosslinking reactions for biomedical applications. Application for this sequentially coupled functional system could be seen e.g. in the treatment of inflamed tissues associated with urinary tract like bladder infections for which pH levels above 7 were reported. By the inclusion of cell adhesion peptide motifs, the hydrogel network formed at this pH could act as a new support layer for the healing of damage epithelium as shown in interfacial gel formation experiments using TDP and PEG4MAL droplets.
The versatility of the thiodepsipeptide sequence, Ac-Pro-Leu-Gly-SLeu-Leu-Gly-(TDPo) was extended for the design and synthesis of a MMP-sensitive 4-arm PEG-TDPo conjugate. The purported cleavage of TDPo at the Gly-SLeu bond yields active thiol units for subsequent reaction of orthogonal Michael acceptor moieties. One of the advantages of stimuli-promoted in situ crosslinking systems using short peptides should be the ease of design of required peptide molecules due to the predictability of peptide functions their sequence structure. Consequently the functionalisation of a 4-arm PEG core with the collagenase active TDPo sequence yielded an MMP-sensitive 4-arm thiodepsipeptide-PEG conjugate (PEG4TDPo) substrate.
Cleavage studies using thiol flourometric assay in the presence of MMPs -2 and -9 confirmed the susceptibility of PEG4TDPo towards these enzymes. The resulting time-dependent increase in fluorescence intensity in the presence of thiol assay signifies the successful cleavage of TDPo at the Gly-SLeu bond as expected. It was observed that the cleavage studies with thiol flourometric assay introduces a sigmoid non-Michaelis-Menten type kinetic profile, hence making it difficult to accurately determine the enzyme cycling parameters, kcat and KM .
Gelation studies with PEG4MAL at 10 % wt. concentrations revealed faster gelation with MMP-2 than MMP-9 with 28 and 40 min gelation times respectively. Possible contributions by hydrolytic cleavage of PEG4TDPo has resulted in the gelation of PEG4MAL blank samples but only after 60 minutes of reaction. From theoretical considerations, the simultaneous gelation reaction would be expected to more negatively impact the enzymatic than hydrolytic cleavage. The exact contributions from hydrolytic cleavage of PEG4TDPo would however require additional studies.
In summary this new and simplified in situ crosslinking system using peptide-based crosslinker precursors with tuneable properties exhibited in situ crosslinking gelation kinetics on similar levels with already active dithiols reported. The advantageous on-demand functionality associated with its pH-sensitivity and physiological compatibility makes it a strong candidate worth further research as biomedical applications in general and on-demand material synthesis is concerned.
Results from MMP-promoted gelation system unveils a simple but unexplored approach for in situ synthesis of covalently crosslinked soft materials, that could lead to the development of an alternative pathway in addressing cancer metastasis by making use of MMP overexpression as a trigger. This goal has so far not being reach with MMP inhibitors despite the extensive work this regard.
Gute Brücke
(2016)
Modern biological analysis techniques supply scientists with various forms of data. One category of such data are the so called "expression data". These data indicate the quantities of biochemical compounds present in tissue samples. Recently, expression data can be generated at a high speed. This leads in turn to amounts of data no longer analysable by classical statistical techniques. Systems biology is the new field that focuses on the modelling of this information. At present, various methods are used for this purpose. One superordinate class of these methods is machine learning. Methods of this kind had, until recently, predominantly been used for classification and prediction tasks. This neglected a powerful secondary benefit: the ability to induce interpretable models. Obtaining such models from data has become a key issue within Systems biology. Numerous approaches have been proposed and intensively discussed. This thesis focuses on the examination and exploitation of one basic technique: decision trees. The concept of comparing sets of decision trees is developed. This method offers the possibility of identifying significant thresholds in continuous or discrete valued attributes through their corresponding set of decision trees. Finding significant thresholds in attributes is a means of identifying states in living organisms. Knowing about states is an invaluable clue to the understanding of dynamic processes in organisms. Applied to metabolite concentration data, the proposed method was able to identify states which were not found with conventional techniques for threshold extraction. A second approach exploits the structure of sets of decision trees for the discovery of combinatorial dependencies between attributes. Previous work on this issue has focused either on expensive computational methods or the interpretation of single decision trees a very limited exploitation of the data. This has led to incomplete or unstable results. That is why a new method is developed that uses sets of decision trees to overcome these limitations. Both the introduced methods are available as software tools. They can be applied consecutively or separately. That way they make up a package of analytical tools that usefully supplement existing methods. By means of these tools, the newly introduced methods were able to confirm existing knowledge and to suggest interesting and new relationships between metabolites.
Human development has far-reaching impacts on the surface of the globe. The transformation of natural land cover occurs in different forms, and urban growth is one of the most eminent transformative processes. We analyze global land cover data and extract cities as defined by maximally connected urban clusters. The analysis of the city size distribution for all cities on the globe confirms Zipf’s law. Moreover, by investigating the percolation properties of the clustering of urban areas we assess the closeness to criticality for various countries. At the critical thresholds, the urban land cover of the countries undergoes a transition from separated clusters to a gigantic component on the country scale. We study the Zipf-exponents as a function of the closeness to percolation and find a systematic dependence, which could be the reason for deviating exponents reported in the literature. Moreover, we investigate the average size of the clusters as a function of the proximity to percolation and find country specific behavior. By relating the standard deviation and the average of cluster sizes—analogous to Taylor’s law—we suggest an alternative way to identify the percolation transition. We calculate spatial correlations of the urban land cover and find long-range correlations. Finally, by relating the areas of cities with population figures we address the global aspect of the allometry of cities, finding an exponent δ ≈ 0.85, i.e., large cities have lower densities.
Besteuerung von Unternehmensgewinnen im Licht des Konzepts der konsumorientierten Einkommensteuer
(2011)
Die Dissertation widmet sich dem Problem der fiskalischen Konsequenzen der konsumorientierten Steuern, die die unternehmerischen Gewinne unabhängig von der Rechtsform belasten. Im empirischen Teil der Arbeit wird der Untersuchungsgegenstand auf die zinsbereinigte Gewinnsteuer (allowance for corporate equity) eingegrenzt. Die Untersuchung beruht auf theoretischen Überlegungen sowie einer eigenen Simulationsanalyse. Den Schwerpunkt bilden dabei zwei Kategorien, zwischen denen ein kausaler Zusammenhang vorliegt: die Gestaltung der Bemessungsgrundlage einerseits und die Erfüllung der Fiskalfunktion andererseits. Das Hauptziel der Arbeit ist es, die fiskalischen Konsequenzen einer nach dem Konzept der Konsumorientierung modifizierten Bemessungsgrundlage der Gewinnsteuern zu überprüfen. Die Abschätzung der fiskalischen Konsequenzen wird aufgrund der vier folgenden Bereiche vorgenommen: (1) theoretische Konzepte der konsumorientierten Einkommensteuer, (2) bisherige Umsetzungen der Konzepte der konsumorientierten Gewinnsteuer, (3) bisherige Untersuchungen der konsumorientierten Gewinnsteuer, (4) eine eigene Simulation der fiskalischen Konsequenzen der konsumorientierten Gewinnsteuer. Um das Hauptziel der Arbeit zu erreichen, werden acht in Form von Teilfragen ausformulierte Untersuchungsprobleme gelöst. Sie betreffen sowohl die theoretischen Ausführungen, als auch die empirische Untersuchung. Dabei entsprechen sie den einzelnen Untersuchungsschritten, die in den aufeinander folgenden Kapiteln der Arbeit durchgeführt werden. Anhand der Analyse der bisherigen wissenschaftlichen Erkenntnisse und der praktischen Umsetzungen des Konzepts der konsumorientierten Steuern wurde die folgende Haupthypothese aufgestellt: Der Ausfall des Steueraufkommens, der ein direkter Effekt der Gestaltung der Bemessungsgrundlage nach dem Konzept der Konsumorientierung ist, schließt die Fiskalfunktion der Gewinnsteuern nicht aus. Das Verfahren, das eine Verifizierung der Haupthypothese zum Ziel hat, erfolgt durch eine Untersuchung von drei Teilhypothesen: der Hypothese über die Nullsteuer, der Hypothese über den differenzierten Aufkommensausfall und der Hypothese über die Konzentration der Steuerschuld. In der Dissertation werden empirische Daten aus drei Quellen benutzt. Sie umfassen einen Teil der in Polen in den Jahren 2004-2008 tätigen Unternehmen und ermöglichen es, eine Simulationsanalyse des Aufkommensausfalls durchzuführen. Diese bedient sich der Methodik der Mikro- und Gruppensimulation, was in den bisherigen Untersuchungen zur Unternehmensbesteuerung ein eher selten anzutreffender Ansatz ist. Die gewonnenen Ergebnisse zeigen, dass die Steuereinnahmen aus der Einkommensteuer und der Körperschaftsteuer durch die Modifizierung der Bemessungsgrundlage deutlich reduziert werden. Die relativ große fiskalische Bedeutung der beiden Steuern bleibt jedoch erhalten und der Ausfall des Steueraufkommens, der direkt nach der Einführung einer konsumorientierten Steuerreform eintreten würde, wäre der „Preis“ für eine bessere, weniger verzerrende Bemessungsgrundlage. Die Dissertation liefert Ergebnisse, die für die Gestaltung der Steuerpolitik in Polen wie auch in anderen Ländern relevant sind. Dies scheint insbesondere im Kontext des häufig diskutierten Umbaus des Systems der Einkommen- und Gewinnbesteuerung bedeutsam. Darüber hinaus bildet die Arbeit einen Ausgangspunkt für weitere, vertiefte Untersuchungen zu den möglichen Gestaltungsformen der Einkommen- und Gewinnsteuern wie auch zu deren Folgen. Die Methode der Steuersimulation kann weiterentwickelt werden und in anderen Analysen der potenziellen Konsequenzen von Steuerreformen Anwendung finden.
Modeling and Formal Analysis of Meta-Ecosystems with Dynamic Structure using Graph Transformation
(2022)
The dynamics of ecosystems is of crucial importance. Various model-based approaches exist to understand and analyze their internal effects. In this paper, we model the space structure dynamics and ecological dynamics of meta-ecosystems using the formal technique of Graph Transformation (short GT). We build GT models to describe how a meta-ecosystem (modeled as a graph) can evolve over time (modeled by GT rules) and to analyze these GT models with respect to qualitative properties such as the existence of structural stabilities. As a case study, we build three GT models describing the space structure dynamics and ecological dynamics of three different savanna meta-ecosystems. The first GT model considers a savanna meta-ecosystem that is limited in space to two ecosystem patches, whereas the other two GT models consider two savanna meta-ecosystems that are unlimited in the number of ecosystem patches and only differ in one GT rule describing how the space structure of the meta-ecosystem grows. In the first two GT models, the space structure dynamics and ecological dynamics of the meta-ecosystem shows two main structural stabilities: the first one based on grassland-savanna-woodland transitions and the second one based on grassland-desert transitions. The transition between these two structural stabilities is driven by high-intensity fires affecting the tree components. In the third GT model, the GT rule for savanna regeneration induces desertification and therefore a collapse of the meta-ecosystem. We believe that GT models provide a complementary avenue to that of existing approaches to rigorously study ecological phenomena.
A key non-destructive technique for analysis, optimization and developing of new functional materials such as sensors, transducers, electro-optical and memory devices is presented. The Thermal-Pulse Tomography (TPT) provides high-resolution three-dimensional images of electric field and polarization distribution in a material. This thermal technique use a pulsed heating by means of focused laser light which is absorbed by opaque electrodes. The diffusion of the heat causes changes in the sample geometry, generating a short-circuit current or change in surface potential, which contains information about the spatial distribution of electric dipoles or space charges. Afterwards, a reconstruction of the internal electric field and polarization distribution in the material is possible via Scale Transformation or Regularization methods. In this way, the TPT was used for the first time to image the inhomogeneous ferroelectric switching in polymer ferroelectric films (candidates to memory devices). The results shows the typical pinning of electric dipoles in the ferroelectric polymer under study and support the previous hypotheses of a ferroelectric reversal at a grain level via nucleation and growth. In order to obtain more information about the impact of the lateral and depth resolution of the thermal techniques, the TPT and its counterpart called Focused Laser Intensity Modulation Method (FLIMM) were implemented in ferroelectric films with grid-shaped electrodes. The results from both techniques, after the data analysis with different regularization and scale methods, are in total agreement. It was also revealed a possible overestimated lateral resolution of the FLIMM and highlights the TPT method as the most efficient and reliable thermal technique. After an improvement in the optics, the Thermal-Pulse Tomography method was implemented in polymer-dispersed liquid crystals (PDLCs) films, which are used in electro-optical applications. The results indicated a possible electrostatic interaction between the COH group in the liquid crystals and the fluorinate atoms of the used ferroelectric matrix. The geometrical parameters of the LC droplets were partially reproduced as they were compared with Scanning Electron Microscopy (SEM) images. For further applications, it is suggested the use of a non-strong-ferroelectric polymer matrix. In an effort to develop new polymerferroelectrets and for optimizing their properties, new multilayer systems were inspected. The results of the TPT method showed the non-uniformity of the internal electric-field distribution in the shaped-macrodipoles and thus suggested the instability of the sample. Further investigation on multilayers ferroelectrets was suggested and the implementation of less conductive polymers layers too.
Starch is a biopolymer for which, despite its simple composition, understanding the precise mechanism behind its formation and regulation has been challenging. Several approaches and bioanalytical tools can be used to expand the knowledge on the different parts involved in the starch metabolism. In this sense, a comprehensive analysis targeting two of the main groups of molecules involved in this process: proteins, as effectors/regulators of the starch metabolism, and maltodextrins as starch components and degradation products, was conducted in this research work using potato plants (Solanum tuberosum L. cv. Desiree) as model of study. On one side, proteins physically interacting to potato starch were isolated and analyzed through mass spectrometry and western blot for their identification. Alternatively, starch interacting proteins were explored in potato tubers from transgenic plants having antisense inhibition of starch-related enzymes and on tubers stored under variable environmental conditions. Most of the proteins recovered from the starch granules corresponded to previously described proteins having a specific role in the starch metabolic pathway. Another set of proteins could be grouped as protease inhibitors, which were found weakly interacting to starch. Variations in the protein profile obtained after electrophoresis separation became clear when tubers were stored under different temperatures, indicating a differential expression of proteins in response to changing environmental conditions.
On the other side, since maltodextrin metabolism is thought to be involved in both starch initiation and degradation, soluble maltooligosaccharide content in potato tubers was analyzed in this work under diverse experimental variables. For this, tuber disc samples from wild type and transgenic lines strongly repressing either the plastidial or cytosolic form of the -glucan phosphorylase and phosphoglucomutase were incubated with glucose, glucose-6-phosphate, and glucose-1-phosphate solutions to evaluate the influence of such enzymes on the conversion of the carbon sources into soluble maltodextrins, in comparison to wild-type samples. Relative maltodextrin amounts analyzed through capillary electrophoresis equipped with laser-induced fluorescence (CE-LIF) revealed that tuber discs could immediately uptake glucose-1-phosphate and use it to produce maltooligosaccharides with a degree of polymerization of up to 30 (DP30), in contrast to transgenic tubers with strong repression of the plastidial glucan phosphorylase. The results obtained from the maltodextrin analysis support previous indications that a specific transporter for glucose-1-phosphate may exist in both the plant cells and the plastidial membranes, thereby allowing a glucose-6-phosphate independent transport. Furthermore, it confirms that the plastidial glucan phosphorylase is responsible for producing longer maltooligosaccharides in the plastids by catalyzing a glucan polymerization reaction when glucose-1-phosphate is available. All these findings contribute to a better understanding of the role of the plastidial glucan phosphorylase as a key enzyme directly involved in the synthesis and degradation of glucans and their implication on starch metabolism.
Adieu à l'école unique socialiste : transformations de l'école en Allemagne après la réunification
(2003)
Das Mädchen aus dem Urwald
(2005)
Die Autorinnen berichten Ergebnisse einer Befragung von 76 Kindern zwischen fünf und zwölf Jahren. Zur Interpretation der Entwicklung des Geheimnisbegriffs verbinden sie kognitionstheoretische mit sozialisationstheoretischen Überlegungen. Anhand von GEORG SIMMELS Essay über „Das Geheimnis und die geheime Gesellschaft" deuten sie das Geheimnis als Element der Entwicklung individueller Autonomie. - Erwachsene und Schülerkultur fördern diese Entwicklung offenbar durch Anerkennung, aber auch durch beträchtlichen Druck. Das führt zu der Kritik, daß wir allgemein noch zu wenig über die Bedeutung des sozialen „Zwangs" wissen, der nach PIAGET allen Fortschritt des Denkens begleitet.
Los niños tienen secretos: secretos para sí solos o secretos que comparten con otros; lenguajes secretos, escrituras secretas y signos distintivos secretos. Nosotros recordamos una fase de nuestra época escolar en que la mayor parte de las noticias entre amigos eran tratadas como algo secreto, que no debía ser comunicado a personas extrañas - era la edad entre los 11 y los 13 años, cuando se formaron en el aulas aquellas agrupaciones que luego se mantuvieron casi inalterables hasta el bachillerato: ¿ los secretos y el secreto como elementos de la «socialización consciente»? Ya en las clases escolares, escribe G. SlMMEL, se hace perceptible cómo los círculos de amigos, por el simple hecho formal de constituir un grupo particular, se conciben como una élite frente a lo no organizado y cuya superioridad los otros también reconocen por la envidia y recelo que suscitan (1958. 296). Por eso también era irrelevante el contenido del respectivo «secreto», no bien aparecía uno: sólo cuchicheaban entre ellos y hacían como que tuvieran que conversar algo, a fin de fortalecer el sentido de compañerismo y para delimitarse frente a los demás, que entonces mostraban curiosidad y recién de esa manera habían de ser rechazados.
Die Verführungsdiskussion, die von feministischen Autorinnen ausging und in der Psychoanalyse aufgenommen wurde, blockiert sich selbst in der Alternative „Phantasie oder Realität?". Unsere These ist, daß es sich dabei aus der Perspektive der Freudschen Theorie um eine falsche Alternative handelt, die in Freuds ersten Entwürfen einer Verführungstheorie schon überwunden ist. Wir stellen Freuds Verführungstheorie aus den Jahren 1894-1897 anhand aller einschlägigen Texte dieser Epoche dar. Im Zentrum steht dabei das Konzept der „posthumen Wirkung des Traumas". Anschließend diskutieren wir theorie-immanente Gründe für die Aufgabe der Verführungstheorie.
Prenant comme arrière-plan la discussion française sur l'immigration, l'article étudie le débat correspondant dans la sociologie allemande. Nous nous concentrons sur le devenir scolaire et les perspectives professionnelles des jeunes immigrés dont nous examinons les conditions politiques, économiques et familiales. Les principaux résultats de la recherche empirique de la décennie 1980-1990 sont présentés et la discussion théorique est restituée dans ses grandes lignes.
Cet article compare quelques points de départ de l'éducation civique en France, système laïque, et en R.F.A., système où les organisations religieuses sont établies au sein de l'État. Une analyse de développements récents suggère que les différences entre les deux systèmes se réduisent. En Allemagne comme en France, l'éducation civique s'organise de plus en plus autour d'une conception individualiste de citoyenneté. Nous faisons l'hypothèse que ce rapprochement est un effet concomitant de la massification de l'enseignement secondaire, commune aux deux pays.
Max Weber
(2005)
Die Website beinhaltet ausgewählte Werke Max Webers im Volltext.Die Potsdamer Internet-Ausgabe "PIA" folgt den alten Ausgaben der zwanziger Jahre (den "Marianne-Ausgaben"), die auch dem größten Teil der bisherigen Weber-Forschung zugrundeliegen. Das Projekt, Webers Werke der EDV zugänglich zu machen, entstand zunächst aus dem Bedürfnis nach neuen Registern. Wir arbeiten in der Erziehungswissenschaft. Für diesen Bereich sind die bisher verfügbaren Register ganz unzulänglich. Dem ist nun abgeholfen. Künftig können Weber-Interessierte aller Disziplinen ihre eigenen Register erstellen. Alle folgenden Texte können heruntergeladen und zur Schlagwort- und Zitatensuche, aber, versteht sich, auch zu anspruchsvolleren Inhaltsanalysen, sprachlichen Untersuchungen und anderen Vorhaben mithilfe spezieller Programme weiter bearbeitet werden. Die Auswahl der hier aufgenommenen Werke hat keine systematischen Gründe. Wir wollten einen Anfang machen und haben uns auf diejenigen Texte beschränkt, die uns in alten Ausgaben zur Hand waren, weil die jüngeren Ausgaben urheberrechtlich geschützt sind. Wichtiges fehlt: die Börsenschriften, "Wirtschaft und Gesellschaft", die Konfuzianismusstudie, die Musiksoziologie, die Schriften zur Russischen Revolution und andere.
Inhalt: - Stimmt es wirklich: Außenseiter in zwei Kulturen? - Stimmt es wirklich: Die Stellung der Frau verbessert sich in der neuen Umgebung? - Stimmt es wirklich: Der traditionelle Familienzusammenhalt ist gefährdet? - Stimmt es wirklich: Notwendig ist ein Wertwandel? - Ausländische Kinder - eine »Begabungsreserve« - Moderne Familien...
Die französische Bildungssoziologie interessiert sich vor allem für die Reproduktion sozialer Schichtung; weil dazu zahlreiche und detaillierte Untersuchungen vorliegen, kann die Erforschung von Geschlechtsunterschieden das relative Gewicht von Schicht und Geschlecht bei der Entstehung von Schulnoten, Schullaufbahnen, Schulabschlüssen und Berufsentscheidungen gut vergleichen. In der Herstellung solcher Querverbindungen zwischen zwei Dimensionen sozialer Ungleichheit, die häufig getrennt untersucht werden, liegt eine der Stärken eines neuen französischen Buches über „Mädchen und Schule", das die folgende Übersicht in den Mittelpunkt stellt.
Wenn man fragt, unter welchen gesellschaftlichen Bedingungen Eheleute und Geliebte sich heute zurechtfinden müssen, kann man an drei auffälligen Entwicklungen nicht vorbeisehen: erstens an der zunehmenden Integration der Mittelschicht-Frauen in den Arbeitsmarkt, zweitens an der Randposition der Männer in der modernen Familie und drittens an der Zunahme der Scheidungszahlen. Es handelt sich um drei Bedingungen, mit denen Ehen und andere Liebesbeziehungen heute konfrontiert sind. Ich überlege in meinem Aufsatz, was sie insbesondere für die Rolle der Geliebten bedeuten.
Inhalt: - Zum Wissenschaftsbegriff der älteren Pädagogik - Religiöse und ständische Elemente des überlieferten Praxisanspruchs - Ist praktisches Engagement rationalisierbar? - Zur pädagogischen Kritik der „positiven Wissenschaft" - Zum praktischen Wert von Forschung - Zum Gegenstand der Erziehungswissenschaft
Obwohl der sozioökonomische Status (SES) eine in der Sozialepidemiologie häufig gebrauchte Variable darstellt, ist seine Verwendung mit methodischen Problemen verknüpft: Seine latente Struktur führt dazu, dass sich verschiedene Möglichkeiten der Operationalisierung eröffnen. Diese reichen von klassischen Ungleichheitsindikatoren wie Bildung, Einkommen oder Berufsposition, über multidimensionale oder über Nachbarschaftsmerkmale konstruierte Indizes, bis hin zu subjektiven Statuseinschätzungen. Problematisch ist dies insofern, als verschiedene Indikatoren auf unterschiedlichen theoretischen Konstrukten beruhen und unterschiedliche Schlussfolgerungen erlauben.
In dieser Arbeit wird deshalb in einem ersten Schritt anhand eines systematischen Reviews zum Zusammenhang von SES und Rückenschmerzen überprüft, welche Indikatoren in wissenschaftlichen Publikationen eingesetzt werden und wie die Auswahl begründet wird. Das Ergebnis zeigt eine klare Präferenz für klassische Indikatoren (Bildung, Einkommen und Berufsposition). Erläutert wurde die jeweilige Auswahl allerdings nur in einem geringen Prozentsatz der untersuchten Artikel, obwohl die unterschiedlichen Studienergebnisse nahelegen, dass der gewählte Indikator einen Einfluss auf den gefundenen Zusammenhang ausüben könnte.
Deshalb wurde in einem weiteren Schritt überprüft, wie unterschiedliche SES-Indikatoren mit der Verbesserung von Rückenschmerzen nach einer Rehabilitation (Studie 1) und der Neuentstehung von Rückenschmerzen (Studie 2) zusammenhängen. Außerdem wurde untersucht, ob ein einfaches Modell den Zusammenhang von SES und Gesundheit so darstellen kann, dass a priori abzuschätzen ist, wie hoch der Einfluss unterschiedlicher Indikatoren auf einen bestimmten Gesundheitsoutput sein könnte.
Es zeigt sich, dass sich der errechnete Zusammenhang zwischen den verschiedenen Indikatoren und chronischen Rückenschmerzen erheblich unterscheidet: Für Menschen, die bereits wegen Rückenschmerzen in Rehabilitation waren, erwiesen sich Bildung und Berufsposition als ähnlich einflussreiche Einflussfaktoren, während für das Einkommen kein bedeutender Zusammenhang festgestellt werden konnte. Für die Neuentstehung chronischer Rückenschmerzen zeigte sich die Berufsposition als wichtigster Indikator, gefolgt von Bildung, während für Einkommen kein signifikanter Zusammenhang gefunden werden konnte.
Folglich bestimmt die Wahl des Indikators die Höhe des festgestellten Zusammenhangs stark mit. Unterschiedliche Indikatoren dürfen deshalb nicht als austauschbar betrachtet werden und es muss bei jeder Forschungsfrage genau überlegt werden, welcher Indikator für die jeweilige Fragestellung am besten verwendet werden kann. Das vorgeschlagene theoretische Modell kann dabei als Unterstützung dienen.
Background
In health research, indicators of socioeconomic status (SES) are often used interchangeably and often lack theoretical foundation. This makes it difficult to compare results from different studies and to explore the relationship between SES and health outcomes. To aid researchers in choosing appropriate indicators of SES, this article proposes and tests a theory-based selection of SES indicators using chronic back pain as a health outcome.
Methods
Strength of relationship predictions were made using Brunner & Marmot’s model of ‘social determinants of health’. Subsequently, a longitudinal study was conducted with 66 patients receiving in-patient treatment for chronic back pain. Sociodemographic variables, four SES indicators (education, job position, income, multidimensional index) and back pain intensity and disability were obtained at baseline. Both pain dimensions were assessed again 6 months later. Using linear regression, the predictive strength of each SES indicator on pain intensity and disability was estimated and compared to the theory based prediction.
Results
Chronic back pain intensity was best predicted by the multidimensional index (beta = 0.31, p < 0.05), followed by job position (beta = 0.29, p < 0.05) and education (beta = −0.29, p < 0.05); whereas, income exerted no significant influence. Back pain disability was predicted strongest by education (beta = −0.30, p < 0.05) and job position (beta = 0.29, p < 0.05). Here, multidimensional index and income had no significant influence.
Conclusions
The choice of SES indicators influences predictive power on both back pain dimensions, suggesting SES predictors cannot be used interchangeably. Therefore, researchers should carefully consider prior to each study which SES indicator to use. The introduced framework can be valuable in supporting this decision because it allows for a stable prediction of SES indicator influence and their hierarchy on a specific health outcomes.
Objective: To investigate associations between socioeconomic status (SES) indicators (education, job position, income, multidimensional index) and the genesis of chronic low back pain (CLBP).
Design: Longitudinal field study (baseline and 6-month follow-up).
Setting: Four medical clinics across Germany.
Participants: 352 people were included according to the following criteria: (1) between 18 and 65 years of age, (2) intermittent pain and (3) an understanding of the study and the ability to answer a questionnaire without help. Exclusion criteria were: (1) pregnancy, (2) inability to stand upright, (3) inability to give sick leave information, (4) signs of serious spinal pathology, (5) acute pain in the past 7 days or (6) an incomplete SES indicators questionnaire.
Outcome measures: Subjective intensity and disability of CLBP.
Results Analysis: showed that job position was the best single predictor of CLBP intensity, followed by a multidimensional index. Education and income had no significant association with intensity. Subjective disability was best predicted by job position, succeeded by the multidimensional index and education, while income again had no significant association.
Conclusion: The results showed that SES indicators have different strong associations with the genesis of CLBP and should therefore not be used interchangeably. Job position was found to be the single most important indicator. These results could be helpful in the planning of back pain care programmes, but in general, more research on the relationship between SES and health outcomes is needed.
Organized drug trafficking and transnationally networked terrorism are transnational threats in Latin America. Security experts see the first as the paramount problem, but regard the second as a mere potential security risk. Latin America’s specific conditions allow limited options for containing non-military threats. Should actors and instruments for containing crime and terrorism be organized on a subregional level, in the Latin American or in the Inter-American context? The author documents promising subregional approaches, especially in the extended Mercosur.
Im Rahmen des ersten Teils der vorliegenden Doktorarbeit konnten zwei nicht-essentielle (rps15, rpl36) und fünf essentielle (rps3, rps16, rpl22, rpl23, rpl32) im Plastom von Nicotiana tabacum kodierte Proteine des plastidären Ribosoms bezüglich ihrer Essentialität charakterisiert werden. Diese Gene wurden durch gezielte Knockout-Experimente inaktiviert und die resultierenden Effekte untersucht. Die Ergebnisse lassen einen Rückschluss auf die Lokalisation der Gene der insgesamt sieben untersuchten ribosomalen Proteine zu, die im Plastom mehrerer parasitischer, Plastiden-besitzender Spezies nicht mehr nachweisbar sind. Im Fall von rps15 könnte tatsächlich ein Verlust des Genes stattgefunden haben, im Fall der restlichen Gene ist eher mit einem Transfer in den Nukleus zu rechnen (rpl36 ausgenommen). Dies würde bedeuten, dass die Geschwindigkeit der erfolgreichen Etablierung eines Gentransfers in vielen parasitischen Spezies gegenüber grünen Pflanzen stark erhöht ist. Alle in E. coli nicht-essentiellen Proteine mit Homologen in Plastiden (rps15, rpl33, rpl36) sind auch dort, trotz ~1,5 Milliarden Jahren getrennter Evolution, nicht essentiell. Dieses Ergebnis bestätigt den schon früher festgestellten hohen Konservierungsgrad der bakteriellen und plastidären Translationsmaschinerien. Die Phänotypen der KO-Pflanzen der nicht-essentiellen Gene (rps15, rpl36) weisen auf eine interessante Rolle von S15 während der Ribosomenassemblierung hin und im Fall von L36 auf eine wichtige funktionelle Rolle im Plastiden-Ribosomen sowie auf eine Involvierung der Plastidentranslation in der Generierung eines retrograden Signals, welches die Blattform zu beeinflussen im Stande ist. Des Weiteren konnte eine Verbindung der Translationsaktivität mit der Ausbildung von Seitentrieben hergestellt werden, die vermutlich auf veränderte Auxinsynthese im Chloroplast zurückzuführen ist. Aus dem Folgeprojekt, bei dem Doppel-KO-Pflanzen nicht-essentieller ribosomaler Proteine erzeugt wurden, lässt sich auf eine relativ große Plastizität der Architektur von Plastidenribosomen schließen. Im zweiten Teil der Arbeit konnte erfolgreich ein Hochdurchsatz-Screeningsystem zur semiquantitativen Analyse von 192 verschiedenen miRNAs aus Chlamydomonas reinhardtii etabliert werden. Es gelang durch die Untersuchung von 23 verschiedenen Wachstums- und Stressbedingungen sowie Entwicklungsstadien mehrere miRNAs zu identifizieren, die eine differenzielle Expression zeigen sowie unter allen untersuchten Bedingungen konstant bleibende miRNAs nachzuweisen. Dadurch konnten mehrere vielversprechende Kandidaten-miRNAs ausgemacht werden, die nun eingehender untersucht werden können.
An important strand of research has investigated the question of how children acquire a morphological system using offline data from spontaneous or elicited child language. Most of these studies have found dissociations in how children apply regular and irregular inflection (Marcus et al. 1992, Weyerts & Clahsen 1994, Rothweiler & Clahsen 1993). These studies have considerably deepened our understanding of how linguistic knowledge is acquired and organised in the human mind. Their methodological procedures, however, do not involve measurements of how children process morphologically complex forms in real time. To date, little is known about how children process inflected word forms. The aim of this study is to investigate children’s processing of inflected words in a series of on-line reaction time experiments. We used a cross-modal priming experiment to test for decompositional effects on the central level. We used a speeded production task and a lexical decision task to test for frequency effects on access level in production and recognition. Children’s behaviour was compared to adults’ behaviour towards three participle types (-t participles, e.g. getanzt ‘danced’ vs. -n participles with stem change, e.g. gebrochen ‘broken’ vs.-n participles without stem change, e.g. geschlafen ‘slept’). For the central level, results indicate that -t participles but not -n participles have decomposed representations. For the access level, results indicate that -t participles are represented according to their morphemes and additionally as full forms, at least from the age of nine years onwards (Pinker 1999 and Clahsen et al. 2004). Further evidence suggested that -n participles are represented as full-form entries on access level and that -n participles without stem change may encode morphological structure (cf. Clahsen et al. 2003). Out data also suggests that processing strategies for -t participles are differently applied in recognition and production. These results provide evidence that children (within the age range tested) employ the same mechanisms for processing participles as adults. The child lexicon grows as children form additional full-form representations for -t participles on access level and elaborate their full-form lexical representations of -n participles on central level. These results are consistent with processing as explained in dual-system theories.
This article expands our current knowledge about ministerial selection in coalition governments and analyses why ministerial candidates succeed in acquiring a cabinet position after general elections. It argues that political parties bargain over potential office-holders during government-formation processes, selecting future cabinet ministers from an emerging bargaining pool'. The article draws upon a new dataset comprising all ministrable candidates discussed by political parties during eight government-formation processes in Germany between 1983 and 2009. The conditional logit regression analysis reveals that temporal dynamics, such as the day she enters the pool, have a significant effect on her success in achieving a cabinet position. Other determinants of ministerial selection discussed in the existing literature, such as party and parliamentary expertise, are less relevant for achieving ministerial office. The article concludes that scholarship on ministerial selection requires a stronger emphasis for its endogenous nature in government-formation as well as the relevance of temporal dynamics in such processes.
This study follows the debate in comparative public administration research on the role of advisory arrangements in central governments. The aim of this study is to explain the mechanisms by which these actors gain their alleged role in government decision-making. Hence, it analyses advisory arrangements that are proactively involved in executive decision-making and may compete with the permanent bureaucracy by offering policy advice to political executives. The study argues that these advisory arrangements influence government policy-making by "institutional politics", i.e. by shaping the institutional underpinnings to govern or rather the "rules of the executive game" in order to strengthen their own position or that of their clients. The theoretical argument of this study follows the neo-institutionalist turn in organization theory and defines institutional politics as gradual institutionalization processes between institutions and organizational actors. It applies a broader definition of institutions as sets of regulative, normative and cognitive pillars. Following the "power-distributional approach" such gradual institutionalization processes are influenced by structure-oriented characteristics, i.e. the nature of the objects of institutional politics, in particular the freedom of interpretation in their application, as well as the distinct constraints of the institutional context. In addition, institutional politics are influenced by agency-oriented characteristics, i.e. the ambitions of actors to act as "would-be change agents". These two explanatory dimensions result in four ideal-typical mechanisms of institutional politics: layering, displacement, drift, and conversion, which correspond to four ideal-types of would-be change agents. The study examines the ambitions of advisory arrangements in institutional politics in an exploratory manner, the relevance of the institutional context is analyzed via expectation hypotheses on the effects of four institutional context features that are regarded as relevant in the scholarly debate: (1) the party composition of governments, (2) the structuring principles in cabinet, (3) the administrative tradition, and (4) the formal politicization of the ministerial bureaucracy. The study follows a "most similar systems design" and conducts qualitative case studies on the role of advisory arrangements at the center of German and British governments, i.e. the Prime Minister’s Office and the Ministry of Finance, for a longer period (1969/1970-2005). Three time periods are scrutinized per country; the British case studies examine the role of advisory arrangements at the Cabinet Office, the Prime Minister's Office, and the Ministry of Finance under Prime Ministers Heath (1970-74), Thatcher (1979-87) and Blair (1997-2005). The German case studies study the role of advisory arrangements at the Federal Chancellery and the Federal Ministry of Finance during the Brandt government (1969-74), the Kohl government (1982-1987) and the Schröder government (1998-2005). For the empirical analysis, the results of a document analysis and the findings of 75 semi-structured expert interviews have been triangulated. The comparative analysis reveals different patterns of institutional politics. The German advisory arrangements engaged initially in displacement but turned soon towards layering and drift, i.e. after an initial displacement of the pre-existing institutional underpinnings to govern they laid increasingly new elements onto existing ones and took the non-deliberative decision to neglect the adaption of existing rules of the executive game towards changing environmental demands. The British advisory arrangements were mostly involved in displacement and conversion, despite occasional layering, i.e. they displaced the pre-existing institutional underpinnings to govern with new rules of the executive game and transformed and realigned them, sometimes also layering new elements onto pre-existing ones. The structure- and agency-oriented characteristics explain these patterns of institutional politics. First, the study shows that the institutional context limits the institutional politics in Germany and facilitates the institutional politics in the UK. Second, the freedom of interpreting the application of institutional targets is relevant and could be observed via the different ambitions of advisory arrangements across countries and over time, confirming, third, that the interests of such would-be change agents are likewise important to understand the patterns of institutional politics. The study concludes that the role of advisory arrangements in government policy-making rests not only upon their policy-related, party-political or media-advisory role for political executives, but especially upon their activities in institutional politics, resulting in distinct institutional constraints on all actors in government policy-making – including their own role in these processes.
As climate change worsens, there is a growing urgency to promote renewable energies and improve their accessibility to society. Here, solar energy harvesting is of particular importance. Currently, metal halide perovskite (MHP) solar cells are indispensable in future solar energy generation research. MHPs are crystalline semiconductors increasingly relevant as low-cost, high-performance materials for optoelectronics. Their processing from solution at low temperature enables easy fabrication of thin film elements, encompassing solar cells and light-emitting diodes or photodetectors. Understanding the coordination chemistry of MHPs in their precursor solution would allow control over the thin film crystallization, the material properties and the final device performance.
In this work, we elaborate on the key parameters to manipulate the precursor solution with the long-term objective of enabling systematic process control. We focus on the nanostructural characterization of the initial arrangements of MHPs in the precursor solutions. Small-angle scattering is particularly well suited for measuring nanoparticles in solution. This technique proved to be valuable for the direct analyzes of perovskite precursor solutions in standard processing concentrations without causing radiation damage. We gain insights into the chemical nature of widely used precursor structures such as methylammonium lead iodide (MAPbI3), presenting first insights into the complex arrangements and interaction within this precursor state. Furthermore, we transfer the preceding results to other more complex perovskite precursors. The influence of compositional engineering is investigated using the addition of alkali cations as an example. As a result, we propose a detailed working mechanism on how the alkali cations suppress the formation of intermediate phases and improve the quality of the crystalline thin film. In addition, we investigate the crystallization process of a tin-based perovskite composition (FASnI3) under the influence of fluoride chemistry. We prove that the frequently used additive, tin fluoride (SnF2), selectively binds undesired oxidized tin (Sn(IV)) in the precursor solution. This prevents its incorporation into the actual crystal structure and thus reduces the defect density of the material. Furthermore, SnF2 leads to a more homogeneous crystal growth process, which results in improved crystal quality of the thin film material.
In total, this study provides a detailed characterization of the complex system of perovskite precursor chemistry. We thereby cover relevant parameters for future MHP solar cell process control, such as (I) the environmental impact based on concentration and temperature (II) the addition of counter ions to reduce the diffuse layer surrounding the precursor nanostructures and (III) the targeted use of additives to eliminate unwanted components selectively and to ensure a more homogeneous crystal growth.
Recently, several faint ringlets in the Saturnian ring system were found to maintain a peculiar orientation relative to Sun. The Encke gap ringlets as well as the ringlet in the outer rift of the Cassini division were found to have distinct spatial displacements of several tens of kilometers away from Saturn towards Sun, referred to as heliotropicity (Hedman et al., 2007). This is quite exceptional, since dynamically one would expect eccentric features in the Saturnian rings to precess around Saturn over periods of months. In our study we address this exceptional behavior by investigating the dynamics of circumplanetary dust particles with sizes in the range of 1-100 µm. These small particles are perturbed by non-gravitational forces, in particular, solar radiation pres- sure, Lorentz force, and planetary oblateness, on time-scales of the order of days. The combined influences of these forces cause periodical evolutions of grains’ orbital ec- centricities as well as precession of their pericenters, which can be shown by secular perturbation theory. We show that this interaction results in a stationary eccentric ringlet, oriented with its apocenter towards the Sun, which is consistent with obser- vational findings. By applying this heliotropic dynamics to the central Encke gap ringlet, we can give a limit for the expected smallest grain size in the ringlet of about 8.7 microns, and constrain the minimal lifetime to lie in the order of months. Furthermore, our model matches fairly well the observed ringlet eccentricity in the Encke gap, which supports recent estimates on the size distribution of the ringlet material (Hedman et al., 2007). The ringlet-width however, that results from our modeling based on heliotropic dynamics, slightly overestimates the observed confined ringlet-width by a factor of 3 to 10, depending on the width-measure being used. This is indicative for mechanisms, not included in the heliotropic model, which potentially confine the ringlet to its observed width, including shepherding and scattering by embedded moonlets in the ringlet region. Based on these results, early investigations (Cuzzi et al., 1984, Spahn and Wiebicke, 1989, Spahn and Sponholz, 1989), and recent work that has been published on the F ring (Murray et al., 2008) - to which the Encke gap ringlets are found to share similar morphological structures - we model the maintenance of the central ringlet by embedded moonlets. These moonlets, believed to have sizes of hundreds of meters across, release material into space, which is eroded by micrometeoroid bombardment (Divine, 1993). We further argue that Pan - one of Saturn’s moons, which shares its orbit with the central ringlet of the Encke gap - is a rather weak source of ringlet material that efficiently confines the ringlet sources (moonlets) to move on horseshoe-like orbits. Moreover, we suppose that most of the narrow heliotropic ringlets are fed by a moonlet population, which is held together by the largest member to move on horseshoe-like orbits. Modeling the equilibrium between particle source and sinks with a primitive balance equation based on photometric observations (Porco et al., 2005), we find the minimal effective source mass of the order of 3 · 10-2MPan, which is needed to keep the central ringlet from disappearing.
The author argues that growth determines employment and not the other way around. He opposes the widespread view among German economists that more employment generated by wage cuts or increased labour market flexibility will stimulate growth. For him, this view relies on theoretical prejudices that have to be rejected in light of some recent, simple evidence. The fact that all cyclical rebounds during the 1990s have been cut short by restrictive monetary policy explains the inability of the German labour market to regain full employment.
The zero-noise limit of differential equations with singular coefficients is investigated for the first time in the case when the noise is a general alpha-stable process. It is proved that extremal solutions are selected and the probability of selection is computed. Detailed analysis of the characteristic function of an exit time form on the half-line is performed, with a suitable decomposition in small and large jumps adapted to the singular drift.
We study the asymptotic regularity of solutions of Hartree-Fock equations for Coulomb systems. In order to deal with singular Coulomb potentials, Fock operators are discussed within the calculus of pseudo-differential operators on conical manifolds. First, the non-self-consistent-field case is considered which means that the functions that enter into the nonlinear terms are not the eigenfunctions of the Fock operator itself. We introduce asymptotic regularity conditions on the functions that build up the Fock operator which guarantee ellipticity for the local part of the Fock operator on the open stretched cone R+ × S². This proves existence of a parametrix with a corresponding smoothing remainder from which it follows, via a bootstrap argument, that the eigenfunctions of the Fock operator again satisfy asymptotic regularity conditions. Using a fixed-point approach based on Cances and Le Bris analysis of the level-shifting algorithm, we show via another bootstrap argument, that the corresponding self-consistent-field solutions of the Hartree-Fock equation have the same type of asymptotic regularity.
The primary motivation for systematic bases in first principles electronic structure simulations is to derive physical and chemical properties of molecules and solids with predetermined accuracy. This requires a detailed understanding of the asymptotic behaviour of many-particle Coulomb systems near coalescence points of particles. Singular analysis provides a convenient framework to study the asymptotic behaviour of wavefunctions near these singularities. In the present work, we want to introduce the mathematical framework of singular analysis and discuss a novel asymptotic parametrix construction for Hamiltonians of many-particle Coulomb systems. This corresponds to the construction of an approximate inverse of a Hamiltonian operator with remainder given by a so-called Green operator. The Green operator encodes essential asymptotic information and we present as our main result an explicit asymptotic formula for this operator. First applications to many-particle models in quantum chemistry are presented in order to demonstrate the feasibility of our approach. The focus is on the asymptotic behaviour of ladder diagrams, which provide the dominant contribution to shortrange correlation in coupled cluster theory. Furthermore, we discuss possible consequences of our asymptotic analysis with respect to adaptive wavelet approximation.
Inhalt: Die Veranlagungssimulation im Kontext anderer Methoden zur Beurteilung von Steuerwirkungen -Steuerwirkungsanalyse in der betriebswirtschaftlichen Steuerlehre und der Finanzwissenschaft im Vergleich -Abgrenzung der Veranlagungssimulation von der Teilsteuerrechnung -Die Veranlagungssimulation als Komponente eines Simulationsmodells zur Politikanalyse Das System der deutschen Unternehmensbesteuerung in Abhängigkeit von der Rechtsform -Einzelunternehmen und Personengesellschaften -Kapitalgesellschaften Die Reform der Unternehmensbesteuerung -Gründe und Ziele der Reform der Unternehmensbesteuerung -Die Maßnahmen der Unternehmenssteuerreform im Überblick Entwicklung des Simulationsmodells -Datengrundlage der Untersuchung -Die Grundstruktur des Modells -Entwicklung der Veranlagungscodes: Veranlagung der Gewerbesteuer, Grundlagen der Gewerbesteuerfestsetzung, Veranlagung der Körperschaftsteuer, Veranlagung der Einkommensteuer Darstellung der Ergebnisse der Veranlagungssimulation -Überblick über die konstituierenden Merkmale der Modellunternehmen -Die Steuerbelastungen der Unternehmen bei Veranlagung nach altem und neuem Steuerrecht im Überblick Der Rechtsformvergleich mit abgewandelten Modellunternehmen -Der Rechtsformvergleich bei Variation steuerlicher Sachverhaltsgestaltungen -Der Rechtsformvergleich bei Variation des Gewinns Zusammenfassung der Ergebnisse des Steuerbelastungs- und des Rechtsformvergleichs Kritische Betrachtung der durch den Gesetzgeber und die Brühler Kommission gesetzten Ziele anhand der generierten Ergebnisse Steuerwirkungen auf Investitionen und Finanzierung Modellkritik
With the many challenges facing the agricultural system, such as water scarcity, loss of arable land due to climate change, population growth, urbanization or trade disruptions, new agri-food systems are needed to ensure food security in the future. In addition, healthy diets are needed to combat non-communicable diseases. Therefore, plant-based diets rich in health-promoting plant secondary metabolites are desirable. A saline indoor farming system is representing a sustainable and resilient new agrifood system and can preserve valuable fresh water. Since indoor farming relies on artificial lighting, assessment of lighting conditions is essential. In this thesis, the cultivation of halophytes in a saline indoor farming system was evaluated and the influence of cultivation conditions were assessed in favor of improving the nutritional quality of halophytes for human consumption. Therefore, five selected edible halophyte species (Brassica oleracea var. palmifolia, Cochlearia officinalis, Atriplex hortensis, Chenopodium quinoa, and Salicornia europaea) were cultivated in saline indoor farming. The halophyte species were selected for to their salt tolerance levels and mechanisms. First, the suitability of halophytes for saline indoor farming and the influence of salinity on their nutritional properties, e.g. plant secondary metabolites and minerals, were investigated. Changes in plant performance and nutritional properties were observed as a function of salinity. The response to salinity was found to be species-specific and related to the salt tolerance mechanism of the halophytes. At their optimal salinity levels, the halophytes showed improved carotenoid content. In addition, a negative correlation was found between the nitrate and chloride content of halophytes as a function of salinity. Since chloride and nitrate can be antinutrient compounds, depending on their content, monitoring is essential, especially in halophytes. Second, regional brine water was introduced as an alternative saline water resource in the saline indoor farming system. Brine water was shown to be feasible for saline indoor farming
of halophytes, as there was no adverse effect on growth or nutritional properties, e.g. carotenoids. Carotenoids were shown to be less affected by salt composition than by salt concentration. In addition, the interaction between the salinity and the light regime in indoor farming and greenhouse cultivation has been studied. There it was shown that interacting light regime and salinity alters the content of carotenoids and chlorophylls. Further, glucosinolate and nitrate content were also shown to be influenced by light regime. Finally, the influence of UVB light on halophytes was investigated using supplemental narrow-band UVB LEDs. It was shown that UVB light affects the growth, phenotype and metabolite profile of halophytes and that the UVB response is species specific. Furthermore, a modulation of carotenoid content in S. europaea could be achieved to enhance health-promoting properties and thus improve nutritional quality. This was shown to be dose-dependent and the underlying mechanisms of carotenoid accumulation were also investigated. Here it was revealed that carotenoid accumulation is related to oxidative stress.
In conclusion, this work demonstrated the potential of halophytes as alternative vegetables produced in a saline indoor farming system for future diets that could contribute to ensuring food security in the future. To improve the sustainability of the saline indoor farming system, LED lamps and regional brine water could be integrated into the system. Since the nutritional properties have been shown to be influenced by salt, light regime and UVB light, these abiotic stressors must be taken into account when considering halophytes as alternative vegetables for human nutrition.
Am 30. Juni 2018 fand die vierzehnte Konferenz des Forschungskreises Vereinte Nationen zum Thema „Herausforderungen für die gegenwärtige deutsche UN-Politik“ statt.
Die Konferenz widmet sich ihrem Schwerpunktthema in drei Vorträgen, in denen einerseits die offizielle Sicht des Auswärtigen Amtes dargestellt und andererseits die Herausforderungen aus wissenschaftlicher Perspektive analysiert werden. Tanja Brühl nimmt hierzu eine Gesamtbetrachtung der deutschen UN-Politik aus rollentheoretischer Sicht vor, während Theodor Rathgeber die deutsche Menschenrechtspolitik angesichts der im UN-Menschenrechtsrat bestehenden Herausforderungen untersucht.
Der Band enthält drei weitere Texte, die Forschungsergebnisse zu aktuellen Entwicklungen präsentieren. Klaus Hüfner erörtert das aktuelle finanzielle Engagement Deutschlands in den Vereinten Nationen. Yanina Bloch zieht eine Bilanz nach den ersten acht Jahren der Tätigkeit von UN Women. Helmut Volger analysiert neue Fortschritte bei der Reform der Arbeitsmethoden des UN-Sicherheitsrates.
Nach dem Review 2014
(2017)
The Book of Radiance
(2019)
Zeit-Not / Not-Zeit
(2017)
Die Beeinflussung optischer Eigenschaften durch Bestrahlung stellt eine Grundlage für die Herstellung anisotroper optischer Komponenten dar. In dünnen Schichten von Azobenzen-Polymeren kann optische Anisotropie durch linear polarisierte Bestrahlung induziert oder modifiziert werden. Ziel der Arbeit war es, wesentliche Struktur-Eigenschafts-Beziehungen zum Prozess der Photoorientierung zu erarbeiten, um so eine Optimierung der Materialien für verschiedene Anwendungen ermöglichen. In isotropen Schichten flüssigkristalliner und amorpher Azobenzen-Polymeren wird das Ausmaß der induzierten optischen Anisotropie günstig durch eine Donor/Akzeptor-Substitution in 4,4'-Position beeinflusst. Die Induktionsgeschwindigkeit ist in Schichten flüssigkristalliner Polymeren deutlich geringer, jedoch lassen sich höhere Werte der Doppelbrechung und des Dichroismus erreichen. In Copolymeren bewirkt die Photoorientierung der Azobenzen-Seitengruppen eine kooperative Orientierung von formanisotropen Seitengruppen. Die Mesogenität der nicht-photochromen Seitengruppen erhöht das Ausmaß der induzierten optischen Anisotropie. Die Stabilität der induzierten Doppelbrechung und des Dichroismus wird durch diese Gruppen gesteigert. In Schichten flüssigkristalliner Polymeren wird die induzierte optische Anisotropie beim Tempern im Bereich der Mesophasen erheblich verstärkt. Dabei reicht ein geringes Maß an induzierter Anisotropie aus, um Doppelbrechungs- und Dichroismuswerte zu erzielen, wie sie für LC-Domänen typisch sind. In orientierten Schichten von Azobenzen-Polymeren wird das Resultat der linear polarisierten Bestrahlung durch die Stärke der anisotropen Wechselwirkungen in den flüssigkristallinen Domänen oder den LB-Multilayern bestimmt. Eine lichtinduzierte Reorientierung kann nur erreicht werden, wenn diese Wechselwirkungen überwunden werden können. Erfolgt eine Photoreorientierung in den orientierten Polymerschichten, werden in Copolymeren formanisotrope Seitengruppen ebenfalls kooperativ reorientiert. Eine vorgelagerte UV-Bestrahlung kann durch Erzeugung eines hohen Anteils an nicht-mesogenen Z-Isomeren die anisotropen Wechselwirkungen stark schwächen und so die Seitengruppen entkoppeln. Aus diesem Zustand erfolgt die Photoreorientierung mit einer der Photoorientierung in isotropen Schichten vergleichbaren Effizienz. Die erarbeiteten Struktur-Eigenschafts-Beziehungen liefern einen Beitrag zur Optimierung derartiger Materialien für Anwendungen in den Bereichen optischer Funktionsschichten, holographischer Datenspeicherung oder der Generierung von Oberflächenreliefgittern.
The present paper addresses a current view in the psycholinguistic literature that case exhibits processing properties distinct from those of other morphological features such as number (cf. Fodor & Inoue, 2000; Meng & Bader, 2000a/b). In a speeded-acceptability judgement experiment, we show that the low performance previously found for case in contrast to number violations is limited to nominative case, whereas violations involving accusative and dative are judged more accurately. The data thus do not support the proposal that case per se is associated with special properties (in contrast to other features such as number) in reanalysis processes. Rather, there are significant judgement differences between the object cases accusative and dative on the one hand and the subject nominative case on the other. This may be explained by the fact that nominative has a specific status in German (and many other languages) as a default case.
Glacial lakes in the Hindu Kush–Karakoram–Himalayas–Nyainqentanglha (HKKHN) region have grown rapidly in number and area in past decades, and some dozens have drained in catastrophic glacial lake outburst floods (GLOFs). Estimating regional susceptibility of glacial lakes has largely relied on qualitative assessments by experts, thus motivating a more systematic and quantitative appraisal. Before the backdrop of current climate-change projections and the potential of elevation-dependent warming, an objective and regionally consistent assessment is urgently needed. We use an inventory of 3390 moraine-dammed lakes and their documented outburst history in the past four decades to test whether elevation, lake area and its rate of change, glacier-mass balance, and monsoonality are useful inputs to a probabilistic classification model. We implement these candidate predictors in four Bayesian multi-level logistic regression models to estimate the posterior susceptibility to GLOFs. We find that mostly larger lakes have been more prone to GLOFs in the past four decades regardless of the elevation band in which they occurred. We also find that including the regional average glacier-mass balance improves the model classification. In contrast, changes in lake area and monsoonality play ambiguous roles. Our study provides first quantitative evidence that GLOF susceptibility in the HKKHN scales with lake area, though less so with its dynamics. Our probabilistic prognoses offer improvement compared to a random classification based on average GLOF frequency. Yet they also reveal some major uncertainties that have remained largely unquantified previously and that challenge the applicability of single models. Ensembles of multiple models could be a viable alternative for more accurately classifying the susceptibility of moraine-dammed lakes to GLOFs.
Pokhara (ca. 850 m a.s.l.), Nepal's second-largest city, lies at the foot of the Higher Himalayas and has more than tripled its population in the past 3 decades. Construction materials are in high demand in rapidly expanding built-up areas, and several informal settlements cater to unregulated sand and gravel mining in the Pokhara Valley's main river, the Seti Khola. This river is fed by the Sabche glacier below Annapurna III (7555 m a.s.l.), some 35 km upstream of the city, and traverses one of the steepest topographic gradients in the Himalayas. In May 2012 a sudden flood caused >70 fatalities and intense damage along this river and rekindled concerns about flood risk management. We estimate the flow dynamics and inundation depths of flood scenarios using the hydrodynamic model HEC-RAS (Hydrologic Engineering Center’s River Analysis System). We simulate the potential impacts of peak discharges from 1000 to 10 000 m3 s−1 on land cover based on high-resolution Maxar satellite imagery and OpenStreetMap data (buildings and road network). We also trace the dynamics of two informal settlements near Kaseri and Yamdi with high potential flood impact from RapidEye, PlanetScope, and Google Earth imagery of the past 2 decades. Our hydrodynamic simulations highlight several sites of potential hydraulic ponding that would largely affect these informal settlements and sites of sand and gravel mining. These built-up areas grew between 3- and 20-fold, thus likely raising local flood exposure well beyond changes in flood hazard. Besides these drastic local changes, about 1 % of Pokhara's built-up urban area and essential rural road network is in the highest-hazard zones highlighted by our flood simulations. Our results stress the need to adapt early-warning strategies for locally differing hydrological and geomorphic conditions in this rapidly growing urban watershed.
High-mountain regions provide valuable ecosystem services, including food, water, and energy production, to more than 900 million people worldwide. Projections hold, that this population number will rapidly increase in the next decades, accompanied by a continued urbanisation of cities located in mountain valleys. One of the manifestations of this ongoing socio-economic change of mountain societies is a rise in settlement areas and transportation infrastructure while an increased power need fuels the construction of hydropower plants along rivers in the high-mountain regions of the world. However, physical processes governing the cryosphere of these regions are highly sensitive to changes in climate and a global warming will likely alter the conditions in the headwaters of high-mountain rivers. One of the potential implications of this change is an increase in frequency and magnitude of outburst floods – highly dynamic flows capable of carrying large amounts of water and sediments. Sudden outbursts from lakes formed behind natural dams are complex geomorphological processes and are often part of a hazard cascade. In contrast to other types of natural hazards in high-alpine areas, for example landslides or avalanches, outburst floods are highly infrequent. Therefore, observations and data describing for example the mode of outburst or the hydraulic properties of the downstream propagating flow are very limited, which is a major challenge in contemporary (glacial) lake outburst flood research. Although glacial lake outburst floods (GLOFs) and landslide-dammed lake outburst floods (LLOFs) are rare, a number of documented events caused high fatality counts and damage. The highest documented losses due to outburst floods since the start of the 20th century were induced by only a few high-discharge events. Thus, outburst floods can be a significant hazard to downvalley communities and infrastructure in high-mountain regions worldwide.
This thesis focuses on the Greater Himalayan region, a vast mountain belt stretching across 0.89 million km2. Although potentially hundreds of outburst floods have occurred there since the beginning of the 20th century, data on these events is still scarce. Projections of cryospheric change, including glacier-mass wastage and permafrost degradation, will likely result in an overall increase of the water volume stored in meltwater lakes as well as the destabilisation of mountain slopes in the Greater Himalayan region. Thus, the potential for outburst floods to affect the increasingly more densely populated valleys of this mountain belt is also likely to increase in the future. A prime example of one of these valleys is the Pokhara valley in Nepal, which is drained by the Seti Khola, a river crossing one of the steepest topographic gradients in the Himalayas. This valley is also home to Nepal’s second largest, rapidly growing city, Pokhara, which currently has a population of more than half a million people – some of which live in informal settlements within the floodplain of the Seti Khola. Although there is ample evidence for past outburst floods along this river in recent and historic times, these events have hardly been quantified.
The main motivation of my thesis is to address the data scarcity on past and potential future outburst floods in the Greater Himalayan region, both at a regional and at a local scale. For the former, I compiled an inventory of >3,000 moraine-dammed lakes, of which about 1% had a documented sudden failure in the past four decades. I used this data to test whether a number of predictors that have been widely applied in previous GLOF assessments are statistically relevant when estimating past GLOF susceptibility. For this, I set up four Bayesian multi-level logistic regression models, in which I explored the credibility of the predictors lake area, lake-area dynamics, lake elevation, parent-glacier-mass balance, and monsoonality. By using a hierarchical approach consisting of two levels, this probabilistic framework also allowed for spatial variability on GLOF susceptibility across the vast study area, which until now had not been considered in studies of this scale. The model results suggest that in the Nyainqentanglha and Eastern Himalayas – regions with strong negative glacier-mass balances – lakes have been more prone to release GLOFs than in regions with less negative or even stable glacier-mass balances. Similarly, larger lakes in larger catchments had, on average, a higher probability to have had a GLOF in the past four decades. Yet, monsoonality, lake elevation, and lake-area dynamics were more ambiguous. This challenges the credibility of a lake’s rapid growth in surface area as an indicator of a pending outburst; a metric that has been applied to regional GLOF assessments worldwide.
At a local scale, my thesis aims to overcome data scarcity concerning the flow characteristics of the catastrophic May 2012 flood along the Seti Khola, which caused 72 fatalities, as well as potentially much larger predecessors, which deposited >1 km³ of sediment in the Pokhara valley between the 12th and 14th century CE. To reconstruct peak discharges, flow depths, and flow velocities of the 2012 flood, I mapped the extents of flood sediments from RapidEye satellite imagery and used these as a proxy for inundation limits. To constrain the latter for the Mediaeval events, I utilised outcrops of slackwater deposits in the fills of tributary valleys. Using steady-state hydrodynamic modelling for a wide range of plausible scenarios, from meteorological (1,000 m³ s-1) to cataclysmic outburst floods (600,000 m³ s-1), I assessed the likely initial discharges of the recent and the Mediaeval floods based on the lowest mismatch between sedimentary evidence and simulated flood limits. One-dimensional HEC-RAS simulations suggest, that the 2012 flood most likely had a peak discharge of 3,700 m³ s-1 in the upper Seti Khola and attenuated to 500 m³ s-1 when arriving in Pokhara’s suburbs some 15 km downstream.
Simulations of flow in two-dimensions with orders of magnitude higher peak discharges in ANUGA show extensive backwater effects in the main tributary valleys. These backwater effects match the locations of slackwater deposits and, hence, attest for the flood character of Mediaeval sediment pulses. This thesis provides first quantitative proof for the hypothesis, that the latter were linked to earthquake-triggered outbursts of large former lakes in the headwaters of the Seti Khola – producing floods with peak discharges of >50,000 m³ s-1.
Building on this improved understanding of past floods along the Seti Khola, my thesis continues with an analysis of the impacts of potential future outburst floods on land cover, including built-up areas and infrastructure mapped from high-resolution satellite and OpenStreetMap data. HEC-RAS simulations of ten flood scenarios, with peak discharges ranging from 1,000 to 10,000 m³ s-1, show that the relative inundation hazard is highest in Pokhara’s north-western suburbs. There, the potential effects of hydraulic ponding upstream of narrow gorges might locally sustain higher flow depths. Yet, along this reach, informal settlements and gravel mining activities are close to the active channel. By tracing the construction dynamics in two of these potentially affected informal settlements on multi-temporal RapidEye, PlanetScope, and Google Earth imagery, I found that exposure increased locally between three- to twentyfold in just over a decade (2008 to 2021).
In conclusion, this thesis provides new quantitative insights into the past controls on the susceptibility of glacial lakes to sudden outburst at a regional scale and the flow dynamics of propagating flood waves released by past events at a local scale, which can aid future hazard assessments on transient scales in the Greater Himalayan region. My subsequent exploration of the impacts of potential future outburst floods to exposed infrastructure and (informal) settlements might provide valuable inputs to anticipatory assessments of multiple risks in the Pokhara valley.
Research on problem solving offers insights into how humans process task-related information and which strategies they use (Newell and Simon, 1972; Öllinger et al., 2014). Problem solving can be defined as the search for possible changes in one's mind (Kahneman, 2003). In a recent study, Adams et al. (2021) assessed whether the predominant problem solving strategy when making changes involves adding or subtracting elements. In order to do this, they used several examples of simple problems, such as editing text or making visual patterns symmetrical, either in naturalistic settings or on-line. The essence of the authors' findings is a strong preference to add rather than subtract elements across a diverse range of problems, including the stabilizing of artifacts, creating symmetrical patterns, or editing texts. More specifically, they succeeded in demonstrating that “participants were less likely to identify advantageous subtractive changes when the task did not (vs. did) cue them to consider subtraction, when they had only one opportunity (vs. several) to recognize the shortcomings of an additive search strategy or when they were under a higher (vs. lower) cognitive load” (Adams et al., 2021, p. 258).
Addition and subtraction are generally defined as de-contextualized mathematical operations using abstract symbols (Russell, 1903/1938). Nevertheless, understanding of both symbols and operations is informed by everyday activities, such as making or breaking objects (Lakoff and Núñez, 2000; Fischer and Shaki, 2018). The universal attribution of “addition bias” or “subtraction neglect” to problem solving activities is perhaps a convenient shorthand but it overlooks influential framing effects beyond those already acknowledged in the report and the accompanying commentary (Meyvis and Yoon, 2021).
Most importantly, while Adams et al.'s study addresses an important issue, their very method of verbally instructing participants, together with lack of control over several known biases, might render their findings less than conclusive. Below, we discuss our concerns that emerged from the identified biases, namely those regarding the instructions and the experimental materials. Moreover, we refer to research from mathematical cognition that provides new insights into Adams et al.'s findings.
Commentary
(2015)
Nach wie vor ist es der internationalen Gemeinschaft nicht gelungen, eine Lösung für die afghanische Krise zu präsentieren. Dabei macht die gegenwärtige Situation eine Beendigung des Kriegszustands sowie die Aufnahme von konstruktiven Verhandlungen unerlässlich. Die Genfer Verhandlungen der 1980er Jahre über den Abzug der Sowjetarmee aus Afghanistan könnten hierbei als Vorbild dienen.
In dieser Arbeit werden nichtlineare Kopplungsmechanismen von akustischen Oszillatoren untersucht, die zu Synchronisation führen können. Aufbauend auf die Fragestellungen vorangegangener Arbeiten werden mit Hilfe theoretischer und experimenteller Studien sowie mit Hilfe numerischer Simulationen die Elemente der Tonentstehung in der Orgelpfeife und die Mechanismen der gegenseitigen Wechselwirkung von Orgelpfeifen identifiziert. Daraus wird erstmalig ein vollständig auf den aeroakustischen und fluiddynamischen Grundprinzipien basierendes nichtlinear gekoppeltes Modell selbst-erregter Oszillatoren für die Beschreibung des Verhaltens zweier wechselwirkender Orgelpfeifen entwickelt. Die durchgeführten Modellrechnungen werden mit den experimentellen Befunden verglichen. Es zeigt sich, dass die Tonentstehung und die Kopplungsmechanismen von Orgelpfeifen durch das entwickelte Oszillatormodell in weiten Teilen richtig beschrieben werden. Insbesondere kann damit die Ursache für den nichtlinearen Zusammenhang von Kopplungsstärke und Synchronisation des gekoppelten Zwei-Pfeifen Systems, welcher sich in einem nichtlinearen Verlauf der Arnoldzunge darstellt, geklärt werden. Mit den gewonnenen Erkenntnissen wird der Einfluss des Raumes auf die Tonentstehung bei Orgelpfeifen betrachtet. Dafür werden numerische Simulationen der Wechselwirkung einer Orgelpfeife mit verschiedenen Raumgeometrien, wie z. B. ebene, konvexe, konkave, und gezahnte Geometrien, exemplarisch untersucht. Auch der Einfluss von Schwellkästen auf die Tonentstehung und die Klangbildung der Orgelpfeife wird studiert. In weiteren, neuartigen Synchronisationsexperimenten mit identisch gestimmten Orgelpfeifen, sowie mit Mixturen wird die Synchronisation für verschiedene, horizontale und vertikale Pfeifenabstände in der Ebene der Schallabstrahlung, untersucht. Die dabei erstmalig beobachteten räumlich isotropen Unstetigkeiten im Schwingungsverhalten der gekoppelten Pfeifensysteme, deuten auf abstandsabhängige Wechsel zwischen gegen- und gleichphasigen Sychronisationsregimen hin. Abschließend wird die Möglichkeit dokumentiert, das Phänomen der Synchronisation zweier Orgelpfeifen durch numerische Simulationen, also der Behandlung der kompressiblen Navier-Stokes Gleichungen mit entsprechenden Rand- und Anfangsbedingungen, realitätsnah abzubilden. Auch dies stellt ein Novum dar.
In dieser Arbeit werden die Effekte der Synchronisation nichtlinearer, akustischer Oszillatoren am Beispiel zweier Orgelpfeifen untersucht. Aus vorhandenen, experimentellen Messdaten werden die typischen Merkmale der Synchronisation extrahiert und dargestellt. Es folgt eine detaillierte Analyse der Übergangsbereiche in das Synchronisationsplateau, der Phänomene während der Synchronisation, als auch das Austreten aus der Synchronisationsregion beider Orgelpfeifen, bei verschiedenen Kopplungsstärken. Die experimentellen Befunde werfen Fragestellungen nach der Kopplungsfunktion auf. Dazu wird die Tonentstehung in einer Orgelpfeife untersucht. Mit Hilfe von numerischen Simulationen der Tonentstehung wird der Frage nachgegangen, welche fluiddynamischen und aero-akustischen Ursachen die Tonentstehung in der Orgelpfeife hat und inwiefern sich die Mechanismen auf das Modell eines selbsterregten akustischen Oszillators abbilden lässt. Mit der Methode des Coarse Graining wird ein Modellansatz formuliert.
The echo chamber model describes the development of groups in heterogeneous social networks. By heterogeneous social network we mean a set of individuals, each of whom represents exactly one opinion. The existing relationships between individuals can then be represented by a graph. The echo chamber model is a time-discrete model which, like a board game, is played in rounds. In each round, an existing relationship is randomly and uniformly selected from the network and the two connected individuals interact. If the opinions of the individuals involved are sufficiently similar, they continue to move closer together in their opinions, whereas in the case of opinions that are too far apart, they break off their relationship and one of the individuals seeks a new relationship. In this paper we examine the building blocks of this model. We start from the observation that changes in the structure of relationships in the network can be described by a system of interacting particles in a more abstract space.
These reflections lead to the definition of a new abstract graph that encompasses all possible relational configurations of the social network. This provides us with the geometric understanding necessary to analyse the dynamic components of the echo chamber model in Part III. As a first step, in Part 7, we leave aside the opinions of the inidividuals and assume that the position of the edges changes with each move as described above, in order to obtain a basic understanding of the underlying dynamics. Using Markov chain theory, we find upper bounds on the speed of convergence of an associated Markov chain to its unique stationary distribution and show that there are mutually identifiable networks that are not apparent in the dynamics under analysis, in the sense that the stationary distribution of the associated Markov chain gives equal weight to these networks.
In the reversible cases, we focus in particular on the explicit form of the stationary distribution as well as on the lower bounds of the Cheeger constant to describe the convergence speed.
The final result of Section 8, based on absorbing Markov chains, shows that in a reduced version of the echo chamber model, a hierarchical structure of the number of conflicting relations can be identified.
We can use this structure to determine an upper bound on the expected absorption time, using a quasi-stationary distribution. This hierarchy of structure also provides a bridge to classical theories of pure death processes. We conclude by showing how future research can exploit this link and by discussing the importance of the results as building blocks for a full theoretical understanding of the echo chamber model. Finally, Part IV presents a published paper on the birth-death process with partial catastrophe. The paper is based on the explicit calculation of the first moment of a catastrophe. This first part is entirely based on an analytical approach to second degree recurrences with linear coefficients. The convergence to 0 of the resulting sequence as well as the speed of convergence are proved. On the other hand, the determination of the upper bounds of the expected value of the population size as well as its variance and the difference between the determined upper bound and the actual value of the expected value. For these results we use almost exclusively the theory of ordinary nonlinear differential equations.
Das Zentrum für Lehrerbildung und Bildungsforschung (ZeLB) verantwortet im Projekt „PSI-Potsdam“ die Unterstützung der Qualifizierung in der Medienbildung/Digitalisierung der Lehrkräftebildung an der Universität Potsdam. Der Schwerpunkt der Tätigkeit lag zunächst auf der mediendidaktischen Qualifizierung und wurde ab der zweiten Förderphase des Programms 2018 mit Akzentuierung auf Herausforderungen und Chancen von Digitalisierung für das Lehren und Lernen in der Lehrkräftebildung fortgeführt. In diesem Beitrag werden die Entwicklungen und Beiträge in Bezug auf die digitale Medienbildung und Digitalisierung an der Universität Potsdam für die Lehrkräftebildung dargestellt. Weiterführend werden Perspektiven aufgezeigt, wie zukünftig digitale Medienbildung in der universitären Lehrkräftebildung verankert werden kann.
This paper deals with the teaching of grammar in the English as a foreign language (EFL) classroom. In this context, a course book (English G 21 A2) is examined in regard to whether it is compatible with current theories about second language acquisition (SLA).
At the beginning of this paper, views on grammar teaching from the past and the present are summarized and this is followed by an analysis of the current curriculum concerning its guidelines for grammar teaching in the foreign language classroom. This analysis concludes that the curriculum of Brandenburg hardly gives any recommendations regarding the question of which grammatical phenomena should to be taught. This explains, at least partly, the important position course books take in the foreign language classroom. Teachers use them as a source of material as well has a guideline for which topics can be taught and in which order.
The following part gives an overview of cognitive models of SLA and foreign language teaching, among others Krashen’s Monitor Hypothesis, R. Ellis’ Weak Interface Model and Pienemann’s Processability Theory. On the basis of these models criteria for the ideal design of a course book, which would support grammar teaching according to current findings, are developed. Among those criteria are the offering of a lot of input in the target language, provision of practice activities and consciousness-raising activities, taking into consideration the sequence of acquisition and the provision of a diagnostic tool which enables the students to find out in which areas of the target language they need to improve. Furthermore, the inclusion of opportunities for (individual) revision is regarded as essential. All of those criteria are of course given under the reservation that the influence of course books on the happenings in the classroom is restricted as the final decisions are made by the teacher in the teaching situation.
In the analysis, one communicative intention which is usually a topic in the English lessons between the third and sixth year of learning is focused on. This communicative intention is talking about the future. First, the possibilities to express futurity in the English language are analysed and reduced for the use in teaching. The chosen course book is then described and analysed and the way the book deals with the topic of talking about the future is compared to the criteria which where specified earlier in the paper. This comparison showed that the book is compatible with SLA theories in many ways (e.g. concerning the explanations of grammatical structures) but that there is still room for improvement (e.g. concerning the amount of input and the number of consciousness-raising activities).
Molecules are often naturally embedded in a complex environment. As a consequence, characteristic properties of a molecular subsystem can be substantially altered or new properties emerge due to interactions between molecular and environmental degrees of freedom. The present thesis is concerned with the numerical study of quantum dynamical and stationary properties of molecular vibrational systems embedded in selected complex environments.
In the first part, we discuss "strong-coupling" model scenarios for molecular vibrations interacting with few quantized electromagnetic field modes of an optical Fabry-Pérot cavity. We thoroughly elaborate on properties of emerging "vibrational polariton" light-matter hybrid states and examine the relevance of the dipole self-energy. Further, we identify cavity-induced quantum effects and an emergent dynamical resonance in a cavity-altered thermal isomerization model, which lead to significant suppression of thermal reaction rates. Moreover, for a single rovibrating diatomic molecule in an optical cavity, we observe non-adiabatic signatures in dynamics due to "vibro-polaritonic conical intersections" and discuss spectroscopically accessible "rovibro-polaritonic" light-matter hybrid states.
In the second part, we study a weakly coupled but numerically challenging quantum mechanical adsorbate-surface model system comprising a few thousand surface modes. We introduce an efficient construction scheme for a "hierarchical effective mode" approach to reduce the number of surface modes in a controlled manner. In combination with the multilayer multiconfigurational time-dependent Hartree (ML-MCTDH) method, we examine the vibrational adsorbate relaxation dynamics from different excited adsorbate states by solving the full non-Markovian system-bath dynamics for the characteristic relaxation time scale. We examine half-lifetime scaling laws from vibrational populations and identify prominent non-Markovian signatures as deviations from Markovian reduced system density matrix theory in vibrational coherences, system-bath entanglement and energy transfer dynamics.
In the final part of this thesis, we approach the dynamics and spectroscopy of vibronic model systems at finite temperature by formulating the ML-MCTDH method in the non-stochastic framework of thermofield dynamics. We apply our method to thermally-altered ultrafast internal conversion in the well-known vibronic coupling model of pyrazine. Numerically beneficial representations of multilayer wave functions ("ML-trees") are identified for different temperature regimes, which allow us to access thermal effects on both electronic and vibrational dynamics as well as spectroscopic properties for several pyrazine models.
This article examines public service resilience during the COVID-19 pandemic and studies the switch to telework due to social distancing measures. We argue that the pandemic and related policies led to increasing demands on public organisations and their employees. Following the job demands-resources model, we argue that resilience only can arise in the presence of resources for buffering these demands. Survey data were collected from 1,189 German public employees, 380 participants were included for analysis. The results suggest that the public service was resilient against the crisis and that the shift to telework was not as demanding as expected.
Dieses Sonderheft der Schriftenreihe des Lehrstuhls für Public und Nonprofit Management präsentiert Ergebnisse eines studentischen Beratungsprojekts aus dem Wintersemester 2018/19. Dabei wurde eine Vision für eine digitalisierte öffentliche Verwaltung entworfen. Unter Anwendung von Szenariomethoden wurden Zukunftsszenarien entwickelt und getestet, die sich entweder mit Bürger*innen und Unternehmen als Kund*innen der Verwaltung, den öffentlich Beschäftigen oder der Aufbau- und Ablauforganisation in der Verwaltung beschäftigen.
Neue Talente braucht das Amt
(2018)
Stellenabbau und demografischer Wandel führen zu Rekrutierungsschwierigkeiten und einem Mangel an talentierten Nachwuchskräften in der öffentlichen Verwaltung. Gleichzeitig stellen sich neue Anforderungen an öffentliche Behörden, die eine andere Qualifikation der Beschäftigten nach sich ziehen. Gerade öffentliche Dienste mit geschlossenen Personalsystemen brauchen daher eine stärkere Flexibilität in der Nachwuchsrekrutierung und -ausbildung. Traineeprogramme können hier Abhilfe schaffen.
Traineeprogramme können im öffentlichen Dienst zur Rekrutierung und Ausbildung von Nachwuchskräften dienen. Solche Programme werden, im Gegensatz zur Privatwirtschaft, wo diese schon seit einigen Jahrzehnten Anwendung finden, im deutschen öffentlichen Dienst erst seit einigen Jahren durchgeführt. Eine erste empirische Erhebung zeigt nun, dass Traineeprogramme im öffentlichen Sektor gut geeignet sind, um Nachwuchskräfte auszubilden und in der Organisation zu sozialisieren. Als entscheidende Einflussfaktoren konnten eine klare Struktur des Programms, ein effektives off-the-job Training, bereichsübergreifende Projektarbeit, der Umfang der Betreuung der Trainees und der Einsatz der jeweiligen Behördenleitung für das Programm identifiziert werden. Deutlich wurde auch, dass während der Einführung eines Traineeprogramms die Trainee-Betreuer entsprechend vorbereitet werden müssen und in den Behörden Akzeptanz für diese neue Form der Nachwuchsgewinnung geschaffen werden muss (Change Management). Die Ergebnisse zeigen jedoch ebenso, dass sich solche Programme nicht zur Personalentwicklung bereits Beschäftigter eignen.