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"Tobias, Klaus"
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International organizations under pressure : legitimating global governance in challenging times
International organizations like the United Nations, the International Monetary Fund, or the European Union are a defining feature of contemporary world politics. In recent years, many of them have also become heavily politicized. 0In this book, we examine how the norms and values that underpin the evaluations of international organizations have changed over the past 50 years. Looking at five organizations in depth, we observe two major trends. Taken together, both trends make the legitimation of international organizations more challenging today. First, people-based legitimacy standards are on the rise: international organizations are increasingly asked to demonstrate not only what they do for their member states, but0also for the people living in these states. Second, procedural legitimacy standards gain ground: international organizations are increasingly evaluated not only based on what they accomplish, but also based on how they arrive at decisions, manage themselves, or coordinate with other organizations in the field. In sum, the study thus documents how the list of expectations international organizations need to fulfil to count as 'legitimate' has expanded over time. The sources of this expansion are manifold. Among others, they include the politicization of expanded international authority and the rise of non-state actors as new audiences from which international organizations seek legitimacy.
Book
Systematics of the dipole polarizability
The electric dipole polarizability is a key observable to set constraints to the symmetry energy parameters of the equation of state and the neutron skin thickness of nuclei. The electric dipole response of a nucleus can be probed with inelastic proton scattering at very forward angles and proton energies of several hundred MeV, where relativistic Coulomb excitation dominates. In the last decade, the electric dipole response in numerous nuclei has been measured at the Research Center for Nuclear Physics in Osaka, Japan. In this work new results about the dipole response and dipole polarizability of 58 Ni will be shown. The now available systematics of polarizability data will be discussed within the framework of the Migdal model.
Journal Article
An Enzyme Cascade Synthesis of Vanillin
A novel approach for the synthesis of vanillin employing a three-step two-enzymatic cascade sequence is reported. Cytochrome P450 monooxygenases are known to catalyse the selective hydroxylation of aromatic compounds, which is one of the most challenging chemical reactions. A set of rationally designed variants of CYP102A1 (P450 BM3) from Bacillus megaterium at the amino acid positions 47, 51, 87, 328 and 437 was screened for conversion of the substrate 3-methylanisole to vanillyl alcohol via the intermediate product 4-methylguaiacol. Furthermore, a vanillyl alcohol oxidase (VAO) variant (F454Y) was selected as an alternative enzyme for the transformation of one of the intermediate compounds via vanillyl alcohol to vanillin. As a proof of concept, the bi-enzymatic three-step cascade conversion of 3-methylanisole to vanillin was successfully evaluated both in vitro and in vivo.
Journal Article
Characterization of the versatile monooxygenase CYP109B1 from Bacillus subtilis
The oxidizing activity of CYP109B1 from Bacillus subtilis was reconstituted in vitro with various artificial redox proteins including putidaredoxin reductase and putidaredoxin from Pseudomonas putida, truncated bovine adrenodoxin reductase and adrenodoxin, flavodoxin reductase and flavodoxin from Escherichia coli, and two flavodoxins from B. subtilis (YkuN and YkuP). Binding and oxidation of a broad range of chemically different substrates (fatty acids, n-alkanes, primary n-alcohols, terpenoids like (+)-valencene, α- and β-ionone, and the steroid testosterone) were investigated. CYP109B1was found to oxidize saturated fatty acids (conversion up to 99%) and their methyl and ethyl esters (conversion up to 80%) at subterminal positions with a preference for the carbon atoms C11 and C12 counted from the carboxyl group. For the hydroxylation of primary n-alcohols, the ω−₂ position was preferred. n-Alkanes were not accepted as substrates by CYP109B1. Regioselective hydroxylation of terpenoids α-ionone (∼70% conversion) and β-ionone (∼ 91% conversion) yielded the allylic alcohols 3-hydroxy-α-ionone and 4-hydroxy-β-ionone, respectively. Furthermore, indole was demonstrated to inhibit fatty acid oxidation.
Journal Article
A superfluid liquid helium target for low-momentum electron scattering experiments at the S-DALINAC
The superconducting electron accelerator S-DALINAC enables electron scattering experiments with low momentum transfer and high energy resolution. In order to perform experiments on helium with high precision and high luminosity, a superfluid liquid helium target with good temperature stability was developed. The functionality of this target could be confirmed and its properties were characterized in a commissioning experiment.
Paper
Closed and open superconducting microwave waveguide networks as a model for quantum graphs
We report on high-precision measurements that were performed with superconducting waveguide networks with the geometry of a tetrahedral and a honeycomb graph. They consist of junctions of valency three that connect straight rectangular waveguides of incommensurable lengths. The experiments were performed in the frequency range of a single transversal mode, where the associated Helmholtz equation is effectively one dimensional and waveguide networks may serve as models of quantum graphs with the joints and waveguides corresponding to the vertices and bonds. The tetrahedral network comprises T junctions, while the honeycomb network exclusively consists of Y junctions, that join waveguides with relative angles 90 degree and 120 degree, respectively. We demonstrate that the vertex scattering matrix, which describes the propagation of the modes through the junctions strongly depends on frequency and is non-symmetric at a T junction and thus differs from that of a quantum graph with Neumann boundary conditions at the vertices. On the contrary, at a Y junction, similarity can be achieved in a certain frequeny range. We investigate the spectral properties of closed waveguide networks and fluctuation properties of the scattering matrix of open ones and find good agreement with random matrix theory predictions for the honeycomb waveguide graph.
Paper
Energy Dissipation of P- and S-Waves in Fluid-Saturated Rocks： An Overview Focusing on Hydraulically Connected Fractures
An important characteristic of fractured rocks is their high seismic attenuation, which so far has been mainly attributed to wave-induced fluid flow（WIFF） between the fractures and the embedding matrix. The influence of fracture connectivity on seismic attenuation has, however, recently, only been investigated. Numerical compressibility and shear tests based on Biot＇s quasi-static poro-elastic equations illustrate that an important manifestation of WIFF arises in the presence of fracture connectivity. The corresponding energy loss, which can be significant for both P- and S-waves, is mainly due to fluid flow within the connected fractures and is sensitive to the permeabilities as well as the lengths and intersection angles of the fractures. Correspondingly, this phenomenon contains valuable information on the governing hydraulic properties of fractured rocks and hence should be accounted for whenever realistic seismic models of such media are needed.
Journal Article
The lactonase BxdA mediates metabolic specialisation of maize root bacteria to benzoxazinoids
Root exudates contain specialised metabolites that shape the plant’s root microbiome. How host-specific microbes cope with these bioactive compounds, and how this ability affects root microbiomes, remains largely unknown. We investigated how maize root bacteria metabolise benzoxazinoids, the main specialised metabolites of maize. Diverse and abundant bacteria metabolised the major compound in the maize rhizosphere MBOA (6-methoxybenzoxazolin-2(3H)-one) and formed AMPO (2-amino-7-methoxy-phenoxazin-3-one). AMPO forming bacteria were enriched in the rhizosphere of benzoxazinoid-producing maize and could use MBOA as carbon source. We identified a gene cluster associated with AMPO formation in microbacteria. The first gene in this cluster,
bxdA
encodes a lactonase that converts MBOA to AMPO in vitro. A deletion mutant of the homologous
bxdA
genes in the genus
Sphingobium
, did not form AMPO nor was it able to use MBOA as a carbon source. BxdA was identified in different genera of maize root bacteria. Here we show that plant-specialised metabolites select for metabolisation-competent root bacteria.
BxdA
represents a benzoxazinoid metabolisation gene whose carriers successfully colonize the maize rhizosphere and thereby shape the plant’s chemical environmental footprint.
Maize root bacteria were investigated for how they cope with the antimicrobial root exudates of their host plant. A gene cluster was identified, allowing the bacteria to metabolise these compounds and to specialize on the exudates of their host.
Journal Article
Biology, detection, and clinical implications of circulating tumor cells
Cancer metastasis is the main cause of cancer‐related death, and dissemination of tumor cells through the blood circulation is an important intermediate step that also exemplifies the switch from localized to systemic disease. Early detection and characterization of circulating tumor cells (CTCs) is therefore important as a general strategy to monitor and prevent the development of overt metastatic disease. Furthermore, sequential analysis of CTCs can provide clinically relevant information on the effectiveness and progression of systemic therapies (e.g., chemo‐, hormonal, or targeted therapies with antibodies or small inhibitors). Although many advances have been made regarding the detection and molecular characterization of CTCs, several challenges still exist that limit the current use of this important diagnostic approach. In this review, we discuss the biology of tumor cell dissemination, technical advances, as well as the challenges and potential clinical implications of CTC detection and characterization.
Graphical Abstract
An overview of the biology of tumor cell dissemination, including an in depth discussion of the current advances and limitations in the detection/isolation of circulating tumor cells and their potential prognostic and diagnostic value.
Journal Article