Universitätspublikationen
Refine
Year of publication
Document Type
- Article (14065)
- Part of Periodical (3508)
- Doctoral Thesis (3364)
- Contribution to a Periodical (2193)
- Book (2123)
- Preprint (1904)
- Working Paper (1903)
- Review (1065)
- Report (909)
- Conference Proceeding (706)
Language
- English (18008)
- German (14120)
- Portuguese (231)
- Spanish (123)
- Italian (66)
- French (64)
- Multiple languages (64)
- Turkish (12)
- Ukrainian (10)
- slo (7)
Keywords
- Deutschland (132)
- COVID-19 (103)
- inflammation (97)
- Financial Institutions (94)
- ECB (69)
- Capital Markets Union (67)
- SARS-CoV-2 (67)
- Financial Markets (63)
- Adorno (58)
- Banking Union (55)
Institute
- Medizin (6773)
- Präsidium (5178)
- Physik (3941)
- Wirtschaftswissenschaften (2324)
- Gesellschaftswissenschaften (2026)
- Frankfurt Institute for Advanced Studies (FIAS) (1788)
- Biowissenschaften (1781)
- Informatik (1509)
- Sustainable Architecture for Finance in Europe (SAFE) (1422)
- Biochemie und Chemie (1407)
Der Leiter des ethnografischen Bildarchivs und Mitherausgeber der Studien zur Kulturkunde Dr. Richard Kuba und die Kunsthistorikerin und Mitarbeiterin des Frobenius-Instituts Dr. Hélène Ivanoff sprechen mit Hadi Khatib Slgini, Student der Ethnologie an der Universität Frankfurt, über das von ANR und DFG geförderte „Anthropos-Projekt“.
[Nachruf] Negasso Gidada
(2019)
The authors examine the effectiveness of labor cost reductions as a means to stimulate economic activity and assesses the differences which may occur with the prevailing exchange rate regime. They develop a medium-scale three-region DSGE model and show that the impact of a cut in the employers’ social security contributions rate does not vary significantly under different exchange rate regimes. They find that both the interest rate and the exchange rate channel matters. Furthermore, the measure appears to be effective even if it comes along with a consumption tax increase to preserve long-term fiscal sustainability.
Finally, they assess whether obtained theoretical results hold up empirically by applying the local projection method. Regression results suggest that changes in employers’ social security contributions rates have statistically significant real effects – a one percentage point reduction leads to an average cumulative rise in output of around 1.3 percent in the medium term. Moreover, the outcome does not differ significantly across the different exchange rate regimes.
How people form beliefs is crucial for understanding decision-making un- der uncertainty. This is particularly true in a situation such as a pandemic, where beliefs will affect behaviors that impact public health as well as the aggregate economy. We conduct two survey experiments to shed light on potential biases in belief formation, focusing in particular on the tone of information people choose to consume and how they incorporate this information into their beliefs. In the first experiment, people express their preferences over pandemic-related articles with optimistic and pessimistic headlines, and are then randomly shown one of the articles. We find that respondents with more pessimistic prior beliefs about the pandemic are substantially more likely to prefer pessimistic articles, which we interpret as evidence of confirmation bias. In line with this, respondents assigned to the less preferred article rate it as less reliable and informative (relative to those who prefer it); they also discount information from the article when it is less preferred. We further find that these motivated beliefs end up impacting incentivized behavior. In a second experiment, we study how partisan views interact with information selection and processing. We find strong evidence of source dependence: revealing the news source further distorts information acquisition and processing, eliminating the role of prior beliefs in article choice.
We assess the effect and the timing of the corporate arm of the ECB quantitative easing (CSPP) on corporate bond issuance. Because of several contemporaneous measures, to isolate the programme effects we rely on one key eligibility feature: the euro denomination of newly issued bonds. We find that the significant increase in bonds issuance by eligible firms is due to the CSPP and that this effect took at least six months to unfold. This result holds even when comparing firms with similar ratings, thus providing evidence that unconventional monetary policy can foster a financing diversification regardless of firms’ risk profile. We also highlight the impact of the programme on the real economic activity. The evidence suggests that while all firms increased investment in capital expenditures and intangible assets, the CSPP induced eligible firms to invest in marketable and equity securities, to repurchase their own stocks, to hold cash and to carry out short-term investment.
By focusing on the cost conditions at issuance, I find that not only the Covid-19 pandemic effects were different across bonds and firms at different stages, but also that the market composition was significantly affected, collapsing on investment- grade bonds, a segment in which the share of bonds eligible to the ECB corporate programmes strikingly increased from 15% to 40%. At the same time the high-yield segment shrunk to almost disappear at 4%. In addition to a market segmentation along the bond grade and the eligibility to the ECB programmes, another source of risk detected in the pricing mechanism is the weak resilience to pandemic: the premium requested is around 30 basis points and started to be priced only after the early containment actions taken by the national authorities. On the contrary, I do not find evidence supporting an increased risk for corporations headquartered in countries with a reduced fiscal space, nor the existence of a premium in favour of green bonds, which should be the backbone of a possible “green recovery”.
Relying on a perspective borrowed from monetary policy announcements and introducing an econometric twist in the traditional event study analysis, we document the existence of an .event risk transfer., namely a significant credit risk transmission from the sovereign to the corporate sector after a sovereign rating downgrade. We find that after the delivery of the downgrade, corporate CDS spreads rise by 36% per annum and there is a widespread contagion across countries, in particular among those which were most exposed to the sovereign debt crisis. This effect exists on top of the standard relation between sovereign and corporate credit risk.
As fossil resources are diminishing, environmental concerns arise and chemical synthesis often involves expensive catalysts or extensive extraction procedures, the demand for production of industrially relevant compounds from renewable resources increases. In this context, engineering microorganisms for production of specialty chemicals, such as 3-alkylphenols, presents an attractive, environmental-friendly approach. 3-alkylphenols have various applications: due to their antiseptic and stabilizing properties many 3-alkylphenols, including 3-methylphenol (3-MP), are utilized as additives in disinfectant reagents and biological products, while they can be also implemented as platform chemicals for production of lubricating oil additives or flavors. Some 3-akylphenols have potential for transmission control of the disease sleeping sickness that is transmitted by tsetse flies in sub-saharan Africa, since 3-ethylphenol (3-EP) and 3-propylphenol (3-PP) and to a lesser degree 3-MP were found to attract tsetse flies and improved catch rates in impregnated tsetse fly traps. Microbial fermentation of 3-alkylphenols would provide a simple and inexpensive way for local communities in Africa to produce these compounds and prepare their own tsetse fly traps.
Some molds synthesize 3-MP as an intermediate during biosynthesis of the mycotoxin patulin. However, the heterologous host Saccharomyces cerevisiae has advantageous traits for industrial application, since it is well characterized, robust, simple to handle and easily genetically accessible. In this thesis, genetical engineering approaches were utilized to establish the yeast S. cerevisiae for biotechnological production of 3-alkylphenols. As a proof of concept, the iterative polyketide synthase from Penicillium patulum, 6-methylsalicylic acid synthase (MSAS), and 6-methylsalicylic acid (6-MSA) decarboxylase PatG from Aspergillus clavatus were heterologously expressed in S. cerevisiae resulting in the first reported de novo biosynthesis of 3-MP via 6-MSA in yeast from sugars (Hitschler & Boles, 2019). It was shown that codon-optimization and genomic integration of heterologous genes, high initial cell densities and a balanced expression of PatG were beneficial for heterologous production of up to 589 mg/L 3-MP in S. cerevisiae. However, toxicity of 3-MP limited higher product accumulation.
Different in vivo detoxification strategies were implemented to face this bottleneck. Growth tests revealed that 3-methylanisole (3-MA) is less toxic to the yeast cells than 3-MP. Expression of an orcinol-O-methyltransferase from chinese rose hybrids (OOMT2) was combined with in situ extraction converting the toxic 3-MP product into the volatile 3-MA and accumulating up to 211 mg/L 3-MA in the dodecane phase. Alternatively, up to 533 mg/L 3-MP glucoside were synthesized by expression of a UDP-glycosyltransferase (UGT72B27) from Vitis vinifera in the 3-MP producing strain, revealing saccharose as beneficial carbon source and ethanol growth phase as essential for high 3-MP production, although 3-MP conversions were not yet complete. Both detoxification strategies allowed circumvention of the toxicity imposed limited product accumulation. This was demonstrated when both detoxification strategies were combined with redirection of the carbon flux through deletion of phosphoglucose isomerase gene PGI1 and feeding a mixture of fructose and glucose leading to majorly improved product formation, with up to 899 mg/L 3-MA/3-MP and 873 mg/L 3-MP/3-MP glucoside, compared to less than 313 mg/L product titers in the wild type controls (Hitschler & Boles, 2020).
For provision of the tsetse fly attractants 3-EP from propionyl-CoA and 3-PP from butyryl-CoA, the substrate promiscuities of MSAS and PatG were exploited. However, slower formation rates with the alternative substrates propionyl-CoA and butyryl-CoA suggested that competing formation of 6-MSA from the preferred priming unit acetyl-CoA was dominating in vivo. Indeed, 3-EP or 3-PP formation was not observed in 3-MP producing yeast strains. Assuming that intracellular levels of propionyl-CoA and butyryl-CoA were limiting 3-EP and 3-PP formation, different strategies were implemented to raise the supply of these alternative priming units and successfully compete with acetyl-CoA for MSAS priming.
Supplementation of propionate increased propionyl-CoA levels by endogenous pathways sufficiently to enable 3-EP formation in yeast mediated by MSAS and PatG. Deletion of the 2-methylcitrate synthases CIT2 and CIT3 revealed that degradation of propionyl-CoA was not limiting 3-EP formation at this stage. In order to raise propionyl-CoA levels further, a heterologous propionyl-CoA synthase (PrpE) was expressed in the 3-MP producing yeast strain leading to up to 12.5 mg/L 3-EP with propionate feeding and blockage of degradation. Moreover, PrpE enabled also 3-EP formation without propionate supplementation suggesting that an endogenous supply of propionate existed that was reactivated by PrpE. As threonine or 2-ketobutyrate feeding increased 3-EP titers in combination with PrpE, this indicated that threonine degradation via 2-ketobutyrate was responsible for the endogenous propionate supply. Moreover, expression of branched-chain ketoacid dehydrogenase complex from Pseudomonas putida combined with PrpE provided propionyl-CoA from endogenous 2-ketobutyrate and raised 3-EP titers up to 5.9 mg/L compared to 2.8 mg/L with only PrpE indicating a potential route for optimization of 3-EP titers independent of propionate or threonine feeding.
For 3-PP production from butyryl-CoA, a heterologous ‘reverse ß-oxidation’ pathway was introduced in the 3-MP producing yeast strain providing sufficient butyryl-CoA for biosynthesis of up to 2 mg/L 3-PP. Degradation of the precursor via ß-oxidation was slightly limiting, since deletion of fatty acyl-CoA oxidase POX1 increased 3-PP titers slightly to 2.6 mg/L.
As the concentrations of 3-alkylphenols are close to the concentrations implemented in tsetse fly traps, the engineered yeast strains have the potential for simple and inexpensive on-site production of 3-alkylphenols as tsetse fly attractants by local rural communities in Africa. In spite of this success, 3-MP remained the main product in the developed yeast strains. Since 3-EP and 3-PP are more efficient tsetse fly attractants, a shift in substrate specificities of MSAS and PatG is desirable for a more favorable 3-EP/3-MP and 3-PP/3-MP product ratio regarding tsetse fly attraction. During rational engineering of MSAS, the MSASQ625A/I752V mutant showed a beneficial shift of product ratios with up to 11 mg/L 3-EP/63 mg/L 3-MP and 4.5 mg/L 3-PP/116 mg/L 3-MP, compared to a higher proportion of 3-MP with up to 343 mg/L, 11 mg/L 3-EP and 1.5 mg/L 3-PP in the wild type controls. Further engineering of MSAS and PatG might majorly improve production of 3-EP and 3-PP.
In summary, this thesis successfully established the yeast S. cerevisiae as cell factory for production of different 3-alkylphenols optimizing expression of the heterologous production pathway, elucidating means to detoxify products and establishing different approaches to increase intracellular levels of acyl-CoA precursors. The engineered yeast strains can be potentially implemented for simple and inexpensive fermentation of tsetse fly attractants in Africa.
Diese Arbeit behandelt die Rolle der Proteinkinasen IKKe und TBK1 in der Progression von humanen malignene Melanomen und die Rolle von alpha-Synuclein in der Schmerzwahrnehmung von Mäusen.
Grenzen überschreiten mit »Imara« : Baraa Abu El-Khair entwickelt Empfehlungen für Moscheegemeinden
(2019)
Für die vorliegende Arbeit wurden zur Analyse des Auger-Zerfalls kleiner Moleküle nach Photoionisation die aus der Zerfallsreaktion resultierenden Impuls- und Energiespektren von Photo- und Auger-Elektronen in Koinzidenz mit denen der ionischen Fragmente aufgenommen. Dies ermöglichte eine getrennte Betrachtung der während des Ionisationsschrittes und des Zerfallsschrittes dieses Prozesses besetzten Molekülzustände. Um weitere Einsicht in die Dynamik des Zerfalls zu erhalten, wurden vorhandene theoretische Modelle, welche insbesondere die Interaktion der durch die Reaktion produzierten geladenen Teilchen (Post Collision Interaction) einbeziehen, an die gemessenen Energiespektren angepasst. Dies ermöglichte die separate Betrachtung der im Ionisationsschritt besetzten Molekülzustände. So konnten die Emissionswinkelverteilungen der Photoelektronen im molekülfesten Koordinatensystem für jeden besetzten Anfangszustand einzeln betrachtet werden. Die Trennung der Endzustände des Zerfalls erfolgte über die Analyse des Spektrums der Ionen-Aufbruchsenergie (Kinetic Energy Release) und den Vergleich mit berechneten Potentialkurven der beitragenden Endzustände.
Durch die nach den Anfangszuständen separierte Betrachtung des Auger-Zerfalls wurde es auch möglich, die Auswirkungen dieser Zustände auf die Zerfallsdynamik zu analysieren. Dafür lieferte die Anpassung der Modellprofile die Lebensdauer des jeweiligen 1s-Lochzustandes in dem entsprechenden Zerfallskanal. Diese jeweiligen Lebensdauern eines jeden Zustandes wurden abhängig von verschiedenen Parametern mit einer Genauigkeit im Attosekunden-Bereich aus den Energiespektren der Photoelektronen ermittelt.
We study continuous dually epi-translation invariant valuations on certain cones of convex functions containing the space of finite-valued convex functions. Using the homogeneous decomposition of this space, we associate a certain distribution to any homogeneous valuation similar to the Goodey-Weil embedding for translation invariant valuations on convex bodies. The support of these distributions induces a corresponding notion of support for the underlying valuations, which imposes certain restrictions on these functionals, and we study the relation between the support of a valuation and its domain. This gives a partial answer to the question which dually epi-translation invariant valuations on finite-valued convex functions can be extended to larger cones of convex functions.
We also study topological properties of spaces of valuations with support contained in a fixed compact set. As an application of these results, we introduce the class of smooth valuations on convex functions and show that the subspace of smooth dually epi-translation invariant valuations is dense in the space of continuous dually epi-translation invariant valuation on finite-valued convex functions. These smooth valuations are given by integrating certain smooth differential forms over the graph of the differential of a convex function. We use this construction to give a characterization of a dense subspace of all continuous valuations on finite-valued convex functions that are rotation invariant as well as dually epi-translation invariant.
Using results from Alesker's theory of smooth valuations on convex bodies, we also show that any smooth valuation can be written as a convergent sum of mixed Hessian valuations. In particular, mixed Hessian valuations span a dense subspace, which is a version of McMullen’s conjecture for valuations on convex functions.
Die Akademische Feier der Vereinigung von Freunden und Förderern der Goethe-Universität schafft es wie keine andere Veranstaltung, jedes Jahr aufs Neue in nur knapp zwei Stunden den Wissenschaftskosmos dieser Universität abzubilden: In kurzweiligen, auch für Laien verständlichen Vorstellungen skizzierten die Laudatoren, worüber die 13 Preisträgerinnen und Preisträger in ihren ausgezeichneten Arbeiten geforscht hatten.