| 1. |
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| 2. |
- Ehnert, Franziska, et al.
(författare)
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The Acceleration of Urban Sustainability Transitions: a Comparison of Brighton, Budapest, Dresden, Genk, and Stockholm
- 2018
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Ingår i: Sustainability. - : MDPI. - 2071-1050. ; 10:3
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Tidskriftsartikel (refereegranskat)abstract
- City-regions as sites of sustainability transitions have remained under-explored so far. With our comparative analysis of five diverse European city-regions, we offer new insights on contemporary sustainability transitions at the urban level. In a similar vein, the pre-development and the take-off phase of sustainability transitions have been studied in depth while the acceleration phase remains a research gap. We address this research gap by exploring how transitions can move beyond the seeding of alternative experiments and the activation of civil society initiatives. This raises the question of what commonalities and differences can be found between urban sustainability transitions. In our explorative study, we employ a newly developed framework of the acceleration mechanisms of sustainability transitions. We offer new insights on the multi-phase model of sustainability transitions. Our findings illustrate that there are no clear demarcations between the phases of transitions. From the perspective of city-regions, we rather found dynamics of acceleration, deceleration, and stagnation to unfold in parallel. We observed several transitions—transitions towards both sustainability and un-sustainability—to co-evolve. This suggests that the politics of persistence—the inertia and path dependencies of un-sustainability—should be considered in the study of urban sustainability transitions.
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| 3. |
- Ehnert, Franziska, et al.
(författare)
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Urban sustainability transitions in a context of multi-level governance : A comparison of four European states
- 2018
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Ingår i: Environmental Innovation and Societal Transitions. - : Elsevier. - 2210-4224 .- 2210-4232. ; 26, s. 101-116
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Tidskriftsartikel (refereegranskat)abstract
- Urban sustainability transitions have attracted increasing academic interest. However, the political-institutional contexts, in which these urban sustainability transitions unfold and by which they are incited, shaped, or inhibited, have received much less attention. This is why we aim at extending previous studies of sustainability transitions by incorporating a multi-level governance perspective. While multi-level governance has been a long-standing theme in political science research, it has remained under-explored in the study of sustainability transitions. This claim is the starting point of our comparative analysis of urban sustainability transitions in Brighton (UK), Dresden (Germany), Genk (Belgium) and Stockholm (Sweden). Our approach “brings the politics back in” by elucidating the dynamics of power concentration and power dispersion generated by different national governance contexts. In our analysis, we explore which opportunities and obstacles these diverse governance contexts provide for urban sustainability transitions.
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| 4. |
- Fuller, Franklin D, et al.
(författare)
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Drop-on-demand sample delivery for studying biocatalysts in action at X-ray free-electron lasers
- 2017
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Ingår i: Nature Methods. - : Macmillan Publishers Ltd.. - 1548-7091 .- 1548-7105. ; 14, s. 443-449
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Tidskriftsartikel (refereegranskat)abstract
- X-ray crystallography at X-ray free-electron laser sources is a powerful method for studying macromolecules at biologically relevant temperatures. Moreover, when combined with complementary techniques like X-ray emission spectroscopy, both global structures and chemical properties of metalloenzymes can be obtained concurrently, providing insights into the interplay between the protein structure and dynamics and the chemistry at an active site. The implementation of such a multimodal approach can be compromised by conflicting requirements to optimize each individual method. In particular, the method used for sample delivery greatly affects the data quality. We present here a robust way of delivering controlled sample amounts on demand using acoustic droplet ejection coupled with a conveyor belt drive that is optimized for crystallography and spectroscopy measurements of photochemical and chemical reactions over a wide range of time scales. Studies with photosystem II, the phytochrome photoreceptor, and ribonucleotide reductase R2 illustrate the power and versatility of this method.
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| 5. |
- Jansen, Iris E, et al.
(författare)
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Genome-wide meta-analysis for Alzheimer's disease cerebrospinal fluid biomarkers.
- 2022
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Ingår i: Acta neuropathologica. - : Springer Science and Business Media LLC. - 1432-0533 .- 0001-6322. ; 144:5, s. 821-842
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Tidskriftsartikel (refereegranskat)abstract
- Amyloid-beta 42 (Aβ42) and phosphorylated tau (pTau) levels in cerebrospinal fluid (CSF) reflect core features of the pathogenesis of Alzheimer's disease (AD) more directly than clinical diagnosis. Initiated by the European Alzheimer & Dementia Biobank (EADB), the largest collaborative effort on genetics underlying CSF biomarkers was established, including 31 cohorts with a total of 13,116 individuals (discovery n=8074; replication n=5042 individuals). Besides the APOE locus, novel associations with two other well-established AD risk loci were observed; CR1 was shown a locus for Aβ42 and BIN1 for pTau. GMNC and C16orf95 were further identified as loci for pTau, of which the latter is novel. Clustering methods exploring the influence of all known AD risk loci on the CSF protein levels, revealed 4 biological categories suggesting multiple Aβ42 and pTau related biological pathways involved in the etiology of AD. In functional follow-up analyses, GMNC and C16orf95 both associated with lateral ventricular volume, implying an overlap in genetic etiology for tau levels and brain ventricular volume.
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| 6. |
- Kern, M., et al.
(författare)
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Integrating static code analysis toolchains
- 2019
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Ingår i: Proceedings 43rd IEEE Annual Computer Software and Applications Conference, COMPSAC 2019. - : IEEE Computer Society. - 9781728126074 ; , s. 523-528
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Konferensbidrag (refereegranskat)abstract
- This paper proposes an approach for a tool-agnostic and heterogeneous static code analysis toolchain in combination with an exchange format. This approach enhances both traceability and comparability of analysis results. State of the art toolchains support features for either test execution and build automation or traceability between tests, requirements and design information. Our approach combines all those features and extends traceability to the source code level, incorporating static code analysis. As part of our approach we introduce the "ASSUME Static Code Analysis tool exchange format" that facilitates the comparability of different static code analysis results. We demonstrate how this approach enhances the usability and efficiency of static code analysis in a development process. On the one hand, our approach enables the exchange of results and evaluations between static code analysis tools. On the other hand, it enables a complete traceability between requirements, designs, implementation, and the results of static code analysis. Within our approach we also propose an OSLC specification for static code analysis tools and an OSLC communication framework.
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| 7. |
- Kubin, Markus, et al.
(författare)
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Cr L-Edge X-ray Absorption Spectroscopy of CrIII(acac)3 in Solution with Measured and Calculated Absolute Absorption Cross Sections
- 2018
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Ingår i: Journal of Physical Chemistry B. - : American Chemical Society (ACS). - 1520-6106 .- 1520-5207. ; 122:29, s. 7375-7384
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Tidskriftsartikel (refereegranskat)abstract
- X-ray absorption spectroscopy at the L-edge of 3d transition metals is widely used for probing the valence electronic structure at the metal site via 2p–3d transitions. Assessing the information contained in L-edge absorption spectra requires systematic comparison of experiment and theory. We here investigate the Cr L-edge absorption spectrum of high-spin chromium acetylacetonate CrIII(acac)3 in solution. Using a transmission flatjet enables determining absolute absorption cross sections and spectra free from X-ray-induced sample damage. We address the challenges of measuring Cr L absorption edges spectrally close to the O K absorption edge of the solvent. We critically assess how experimental absorption cross sections can be used to extract information on the electronic structure of the studied system by comparing our results of this CrIII (3d3) complex to our previous work on L-edge absorption cross sections of MnIII(acac)3 (3d4) and MnII(acac)2 (3d5). Considering our experimental uncertainties, the most insightful experimental observable for this d3(CrIII)–d4(MnIII)–d5(MnII) series is the L-edge branching ratio, and we discuss it in comparison to semiempirical multiplet theory and ab initio restricted active space calculations. We further discuss and analyze trends in integrated absorption cross sections and correlate the spectral shapes with the local electronic structure at the metal sites.
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| 8. |
- Kubin, Markus, et al.
(författare)
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Direct Determination of Absolute Absorption Cross Sections at the L-Edge of Dilute Mn Complexes in Solution Using a Transmission Flatjet
- 2018
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Ingår i: Inorganic Chemistry. - : AMER CHEMICAL SOC. - 0020-1669 .- 1520-510X. ; 57:9, s. 5449-5462
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Tidskriftsartikel (refereegranskat)abstract
- The 3d transition metals play a pivotal role in many charge transfer processes in catalysis and biology. X-ray absorption spectroscopy at the L-edge of metal sites probes metal 2p–3d excitations, providing key access to their valence electronic structure, which is crucial for understanding these processes. We report L-edge absorption spectra of MnII(acac)2 and MnIII(acac)3 complexes in solution, utilizing a liquid flatjet for X-ray absorption spectroscopy in transmission mode. With this, we derive absolute absorption cross-sections for the L-edge transitions with peak magnitudes as large as 12 and 9 Mb for MnII(acac)2 and MnIII(acac)3, respectively. We provide insight into the electronic structure with ab initio restricted active space calculations of these L-edge transitions, reproducing the experimental spectra with excellent agreement in terms of shapes, relative energies, and relative intensities for the two complexes. Crystal field multiplet theory is used to assign spectral features in terms of the electronic structure. Comparison to charge transfer multiplet calculations reveals the importance of charge transfer in the core-excited final states. On the basis of our experimental observations, we extrapolate the feasibility of 3d transition metal L-edge absorption spectroscopy using the liquid flatjet approach in probing highly dilute biological solution samples and possible extensions to table-top soft X-ray sources.
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| 9. |
- Kubin, Markus, et al.
(författare)
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Probing the oxidation state of transition metal complexes : a case study on how charge and spin densities determine Mn L-edge X-ray absorption energies
- 2018
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Ingår i: Chem. Sci.. - : The Royal Society of Chemistry. ; 9:33, s. 6813-6829
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Tidskriftsartikel (refereegranskat)abstract
- Transition metals in inorganic systems and metalloproteins can occur in different oxidation states, which makes them ideal redox-active catalysts. To gain a mechanistic understanding of the catalytic reactions, knowledge of the oxidation state of the active metals, ideally in operando, is therefore critical. L-edge X-ray absorption spectroscopy (XAS) is a powerful technique that is frequently used to infer the oxidation state via a distinct blue shift of L-edge absorption energies with increasing oxidation state. A unified description accounting for quantum-chemical notions whereupon oxidation does not occur locally on the metal but on the whole molecule and the basic understanding that L-edge XAS probes the electronic structure locally at the metal has been missing to date. Here we quantify how charge and spin densities change at the metal and throughout the molecule for both redox and core-excitation processes. We explain the origin of the L-edge XAS shift between the high-spin complexes MnII(acac)2 and MnIII(acac)3 as representative model systems and use ab initio theory to uncouple effects of oxidation-state changes from geometric effects. The shift reflects an increased electron affinity of MnIII in the core-excited states compared to the ground state due to a contraction of the Mn 3d shell upon core-excitation with accompanied changes in the classical Coulomb interactions. This new picture quantifies how the metal-centered core hole probes changes in formal oxidation state and encloses and substantiates earlier explanations. The approach is broadly applicable to mechanistic studies of redox-catalytic reactions in molecular systems where charge and spin localization/delocalization determine reaction pathways.
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| 10. |
- Kubin, Markus, et al.
(författare)
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Soft x-ray absorption spectroscopy of metalloproteins and high-valent metal-complexes at room temperature using free-electron lasers
- 2017
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Ingår i: Structural Dynamics. - : AMER INST PHYSICS. - 2329-7778. ; 4:5
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Tidskriftsartikel (refereegranskat)abstract
- X-ray absorption spectroscopy at the L-edge of 3d transition metals provides unique information on the local metal charge and spin states by directly probing 3d-derived molecular orbitals through 2p-3d transitions. However, this soft x-ray technique has been rarely used at synchrotron facilities for mechanistic studies of metalloenzymes due to the difficulties of x-ray-induced sample damage and strong background signals from light elements that can dominate the low metal signal. Here, we combine femtosecond soft x-ray pulses from a free-electron laser with a novel x-ray fluorescence-yield spectrometer to overcome these difficulties. We present L-edge absorption spectra of inorganic high-valent Mn complexes (Mn similar to 6-15 mmol/l) with no visible effects of radiation damage. We also present the first L-edge absorption spectra of the oxygen evolving complex (Mn4CaO5) in Photosystem II (Mn < 1 mmol/l) at room temperature, measured under similar conditions. Our approach opens new ways to study metalloenzymes under functional conditions. (C) 2017 Author(s).
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