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Volk und Proletariat
(1889)
We test whether investor mood affects trading with data on all stock market transactions in Finland, utilizing variation in daylight and local weather. We find some evidence that environmental mood variables (local weather, length of day, daylight saving and lunar phase) affect investors’ direction of trade and volume. The effect magnitudes are roughly comparable to those of classical seasonals, such as the Monday effect. The statistical significance of the mood variables is weak in many cases, however. Only very little of the day-to-day variation in trading is collectively explained by all mood variables and calendar effects, but lower frequency variation seems connected to holiday seasons.
We use unique data from financial advisers’ professional exam scores and combine it with other variables to create an index of financial sophistication. Using this index to explain long-term stock return expectations, we find that more sophisticated financial advisers tend to have lower return expectations. A one standard deviation increase in the sophistication index reduces expected returns by 1.1 percentage points. The effect is stronger for emerging market stocks (2.3 percentage points). The sophistication effect contributes 60% to the model fit, while employer fixed effects combined contribute less than 30%. These results help understand the formation of potentially excessively optimistic expectations.
A natural experiment in which customer-owned mutual companies converted to publicly listed firms created a plausibly exogenous shock to the stock market participation status of tens of thousands of people. We find the shock changed the way people vote in the affected areas, with a 10% increase in share-ownership rate being followed by a 1.3%–3.1% increase in right-of-center vote share. The institutional details and additional tests suggest that wealth, liquidity, and tax-related incentives cannot fully explain the results. A plausible explanation is that the associated increase in the salience of stock ownership causes a shift in voters’ attention.
It’s intuitively plausible to suppose that there are many things that we can be rationally certain of, at least in many contexts. The present paper argues that, given this principle of Abundancy, there is a Preface Paradox for (rational) credence. Section 1 gives a statement of the paradox, discusses its relation to its familiar counterpart for (rational) belief, and points out the congeniality between Abundancy and broadly contextualist trends in epistemology. This leads to the question whether considerations of context-sensitivity might lend themselves to solving the Preface for credence. Sections 2 and 3 scrutinize two approaches in this spirit—one mimicking Hawthorne’s (2002) Semantic Contextualist approach to an epistemic version of the Preface, the other one analogous to Clarke’s (2015) Sensitivist approach to the doxastic version—arguing that neither approach succeeds as it stands.
We investigate complexes of two paramagnetic metal ions Gd3+ and Mn2+ to serve as polarizing agents for solid-state dynamic nuclear polarization (DNP) of 1H, 13C, and 15N at magnetic fields of 5, 9.4, and 14.1 T. Both ions are half-integer high-spin systems with a zero-field splitting and therefore exhibit a broadening of the mS = −1/2 ↔ +1/2 central transition which scales inversely with the external field strength. We investigate experimentally the influence of the chelator molecule, strong hyperfine coupling to the metal nucleus, and deuteration of the bulk matrix on DNP properties. At small Gd-DOTA concentrations the narrow central transition allows us to polarize nuclei with small gyromagnetic ratio such as 13C and even 15N via the solid effect. We demonstrate that enhancements observed are limited by the available microwave power and that large enhancement factors of >100 (for 1H) and on the order of 1000 (for 13C) can be achieved in the saturation limit even at 80 K. At larger Gd(III) concentrations (≥10 mM) where dipolar couplings between two neighboring Gd3+ complexes become substantial a transition towards cross effect as dominating DNP mechanism is observed. Furthermore, the slow spin-diffusion between 13C and 15N, respectively, allows for temporally resolved observation of enhanced polarization spreading from nuclei close to the paramagnetic ion towards nuclei further removed. Subsequently, we present preliminary DNP experiments on ubiquitin by site-directed spin-labeling with Gd3+ chelator tags. The results hold promise towards applications of such paramagnetically labeled proteins for DNP applications in biophysical chemistry and/or structural biology.
Metal ions as novel polarizing agents for dynamic nuclear polarization enhanced NMR spectroscopy
(2017)
High-spin complexes of Gd(III) and Mn(II) were introduced as polarizing agents (PAs) for solid-state dynamic nuclear polarization (DNP) in 2011. This dissertation was undertaken in 2013, with the intention of exploring these PAs further. Major goals of this work were to understand their DNP mechanism(s) and explore their application in biomolecular research. This cumulative thesis details the methods, advantages, and practical implications of using high-spin PAs for MAS DNP. Data from electron paramagnetic resonance (EPR) and NMR spectroscopy are discussed for a complete understanding of DNP mechanisms.
Out of the two main mechanisms − solid effect (SE) and cross effect (CE − active under experimental conditions of solid-state DNP, commonly used nitroxide PAs evoke CE owing to their broad EPR spectra. On the other hand, DNP mechanisms evoked by high-spin metal ions seem non-trivial due to additional features (originating from spin-orbit coupling or zero field splitting) in their EPR spectra. The features of the EPR signal generally influence the shape of enhancement profiles. Therefore, the metal ion with a simpler EPR signal i.e., Gd(III) , is chosen as the starting point for the investigation of DNP mechanisms. Varying concentrations (2, 10, 20 mM) of a water-soluble and stable complex Gd-DOTA was dissolved as the PA in a glycerol-water solution of 13C,15N - urea. Field profiles of DNP enhancement on each nuclear type (1H, 13C, and 15N) establishes SE as the active DNP mechanism at the smallest PA concentration (2 mM). This confirms the theoretical predictions that narrow line width of the Gd(III) EPR signal arising from the central transition (CT, ms = -1/2 +1/2) allows for resolved SE DNP. However, that is no longer the case at higher PA concentrations of 10 and 20 mM. At higher Gd(III) concentrations, the CE mechanism contributes significantly and varies with nuclear Larmor frequency (ωn) of the concerned nuclei. The enhancement maxima shifts towards the EPR resonance as the contribution from CE increases. This shift is evident in the field profiles of 15N and 13C, whereas that of 1H is least influenced. This observation can be explained by combining theoretical estimates with the experimental data; the CE is evoked by increased dipolar coupling (Dee) – a prerequisite for CE – between neighboring Gd(III) spins as the statistical inter-spin distance shortens at elevated concentrations. This finding is important because the knowledge of active DNP mechanisms is essential for accurate interpretation of results from DNP experiments.
From the experiments on Gd-DOTA it becomes clear that concentration, inter-spin distances, and hence induced Dee are intertwined. In order to explicitly address the influence of inter-spin distances on DNP mechanisms we started a collaboration with the group of Adelheid Godt (Bielefeld). In this collaborative project, bis-complexes of the type Gd(III)-spacer-Gd(III) with variable spacer lengths were investigated. These PAs provided an excellent model system where the influence of only inter-spin distances can be determined for a fixed Gd(III) concentration. A small PA concentration of 4 mM is used to ensure absence of significant inter-molecular dipolar interactions. A mono-Gd complex of similar geometry and chemistry is taken as a reference for SE DNP.
The mono-Gd complex yields enhancements arising from SE as expected from negligible inter-molecular Dee. The contribution of CE increases as the inter-spin distances between Gd(III) ions become shorter going from 3.4 nm 2.1 nm 1.4 nm 1.2 nm due to corresponding increase in Dee. The extent of CE on ωn follows the same trend as for Gd-DOTA. Highest CE contribution is observed on nuclei with the smallest ωn 15N because smaller ωn approaches the width of the EPR signal, this is an additional requirement for CE DNP.
The field position for maximum DNP enhancement corresponding to Gd-DOTA, is used for DNP experiments on Ubiquitin with an attached Gd-tag as PA. The success of DNP on this sample illustrates the possibility of site-directed DNP with metal ions tags as PAs. As a perspective Gd-tags can be used to examine change in conformation of a protein that would give higher enhancements due to CE if two Gd(III) labeled domains are closer in space. In a separate project, Mn(II) (s=5/2) bound to the divalent site of a hammerhead ribozyme was used as a PA which resulted in the first demonstration of intra-complex DNP using an intrinsically bound metal ion PA.
Der Drömling ist mit einer Fläche von ca. 320 km2 das größte Feucht- und Niedermoorgebiet im deutschen Altpleistozän, das noch große geschlossene Niedermoorkomplexe aufweist. Das Gebiet ist Lebensraum zahlreicher seltener und vom Aussterben bedrohter Tier- und Pflanzenarten. Mit dem im Zuge der Kultivierung entstandenen umfangreichen Graben- und Stauanlagensystem und den historisch bedeutsamen Rimpau’schen Moordammkulturen ist die Drömlingsniederung zugleich eine einmalige Kulturlandschaft.
The title compound, C22H18N2O2, was derived from 1-(2-hydroxyphenyl)-3-(4-methoxyphenyl)propane-1,3-dione. The central pyrazole ring forms dihedral angles of 16.83 (5), 48.97 (4) and 51.68 (4)°, respectively, with the methoxyphenyl, phenyl and hydroxyphenyl rings. The crystal packing is stabilized by O-H...N hydrogen bonding. Key indicators: single-crystal X-ray study; T = 173 K; mean σ(C–C) = 0.002 Å; R factor = 0.037; wR factor = 0.096; data-to-parameter ratio = 17.0.
ATP-binding cassette (ABC) transporters, a superfamily of integral membrane proteins, catalyse the translocation of substrates across the cellular membrane by ATP hydrolysis. Here we demonstrate by nucleotide turnover and binding studies based on 31P solid-state NMR spectroscopy that the ABC exporter and lipid A flippase MsbA can couple ATP hydrolysis to an adenylate kinase activity, where ADP is converted into AMP and ATP. Single-point mutations reveal that both ATPase and adenylate kinase mechanisms are associated with the same conserved motifs of the nucleotide-binding domain. Based on these results, we propose a model for the coupled ATPase-adenylate kinase mechanism, involving the canonical and an additional nucleotide-binding site. We extend these findings to other prokaryotic ABC exporters, namely LmrA and TmrAB, suggesting that the coupled activities are a general feature of ABC exporters.
G-protein-coupled receptor (GPCR) expression is extensively studied in bulk cDNA, but heterogeneity and functional patterning of GPCR expression in individual vascular cells is poorly understood. Here, we perform a microfluidic-based single-cell GPCR expression analysis in primary smooth muscle cells (SMC) and endothelial cells (EC). GPCR expression is highly heterogeneous in all cell types, which is confirmed in reporter mice, on the protein level and in human cells. Inflammatory activation in murine models of sepsis or atherosclerosis results in characteristic changes in the GPCR repertoire, and we identify functionally relevant subgroups of cells that are characterized by specific GPCR patterns. We further show that dedifferentiating SMC upregulate GPCRs such as Gpr39, Gprc5b, Gprc5c or Gpr124, and that selective targeting of Gprc5b modulates their differentiation state. Taken together, single-cell profiling identifies receptors expressed on pathologically relevant subpopulations and provides a basis for the development of new therapeutic strategies in vascular diseases.
The re-emergence of tuberculosis in its present-day manifestations - single, multiple and extensive drug-resistant forms and as HIV-TB coinfections - has resulted in renewed research on fundamental questions such as the nature of the organism itself, Mycobacterium tuberculosis, the molecular basis of its pathogenesis, definition of the immunological response in animal models and humans, and development of new intervention strategies such as vaccines and drugs. Foremost among these developments has been the precise chemical definition of the complex and distinctive cell wall of M. tuberculosis, elucidation of the relevant pathways and underlying genetics responsible for the synthesis of the hallmark moieties of the tubercle bacillus such as the mycolic acid-arabinogalactan-peptidoglycan complex, the phthiocerol- and trehalose-containing effector lipids, the phosphatidylinositol-containing mannosides, lipomannosides and lipoarabinomannosides, major immunomodulators, and others. In this review, the laboratory personnel who have been the focal point of some to these developments review recent progress towards a comprehensive understanding of the basic physiology and functions of the cell wall of M. tuberculosis.
Seit 2000 ist die promovierte Geoökologin als Referatsleiterin in der Berliner Senatsverwaltung u.a. für die atomrechtliche Aufsichts- und Genehmigungsbehörde, die Katastrophenschutzbehörde, die Strahlenmessstelle Berlin und das Berliner Luftgütemessnetz zuständig. Seit 2010 ist Heike Kaupp stellvertretende Abteilungsleiterin der Abteilung Integrativer Umweltschutz. Sie ist Fellow des Mercator Science-Policy Fellowship-Programms an den Rhein-Main-Universitäten.
Background: Computed tomography (CT) low-dose (LD) imaging is used to lower radiation exposure, especially in vascular imaging; in current literature, this is mostly on latest generation high-end CT systems.
Purpose: To evaluate the effects of reduced tube current on objective and subjective image quality of a 15-year-old 16-slice CT system for pulmonary angiography (CTPA).
Material and Methods: CTPA scans from 60 prospectively randomized patients (28 men, 32 women) were examined in this study on a 15-year-old 16-slice CT scanner system. Standard CT (SD) settings were 100 kV and 150 mAs, LD settings were 100 kV and 50 mAs. Attenuation of the pulmonary trunk, various anatomic landmarks, and image noise were quantitatively measured; contrast-to-noise ratios (CNR) and signal-to-noise ratios (SNR) were calculated. Three independent blinded radiologists subjectively rated each image series using a 5-point grading scale.
Results: CT dose index (CTDI) in the LD series was 66.46% lower compared to the SD settings (2.49 ± 0.55 mGy versus 7.42 ± 1.17 mGy). Attenuation of the pulmonary trunk showed similar results for both series (SD 409.55 ± 91.04 HU; LD 380.43 HU ± 93.11 HU; P = 0.768). Subjective image analysis showed no significant differences between SD and LD settings regarding the suitability for detection of central and peripheral PE (central SD/LD, 4.88; intra-class correlation coefficients [ICC], 0.894/4.83; ICC, 0.745; peripheral SD/LD, 4.70; ICC, 0.943/4.57; ICC, 0.919; all P > 0.4).
Conclusion: The LD protocol, on a 15-year-old CT scanner system without current high-end hardware or post-processing tools, led to a dose reduction of approximately 67% with similar subjective image quality and delineation of central and peripheral pulmonary arteries.
During early G1 phase, Rb is exclusively mono-phosphorylated by cyclin D:Cdk4/6, generating 14 different isoforms with specific binding patterns to E2Fs and other cellular protein targets. While mono-phosphorylated Rb is dispensable for early G1 phase progression, interfering with cyclin D:Cdk4/6 kinase activity prevents G1 phase progression, questioning the role of cyclin D:Cdk4/6 in Rb inactivation. To dissect the molecular functions of cyclin D:Cdk4/6 during cell cycle entry, we generated a single cell reporter for Cdk2 activation, RB inactivation and cell cycle entry by CRISPR/Cas9 tagging endogenous p27 with mCherry. Through single cell tracing of Cdk4i cells, we identified a time-sensitive early G1 phase specific Cdk4/6-dependent phosphorylation gradient that regulates cell cycle entry timing and resides between serum-sensing and cyclin E:Cdk2 activation. To reveal the substrate identity of the Cdk4/6 phosphorylation gradient, we performed whole proteomic and phospho-proteomic mass spectrometry, and identified 147 proteins and 82 phospho-peptides that significantly changed due to Cdk4 inhibition in early G1 phase. In summary, we identified novel (non-Rb) cyclin D:Cdk4/6 substrates that connects early G1 phase functions with cyclin E:Cdk2 activation and Rb inactivation by hyper-phosphorylation.
Hocherfreut zeigten sich die US-amerikanischen Wissenschaftler Prof. Michael R. Silverman Ph.D. (77) und Prof. Bonnie L. Bassler Ph.D. (58), als der Vorsitzende des Stiftungsrats Prof. Thomas Boehm sie informierte: Sie erhalten den Paul Ehrlich- und Ludwig Darmstaedter-Preis 2021 für ihre Entdeckungen zur bakteriellen Kommunikation. Die feierliche Würdigung der Preisträger in der Paulskirche – auch der mit dem Nachwuchspreis ausgezeichneten Prof. Dr. Elvira Mass (34) – wird allerdings wegen der Corona-Pandemie erst im nächsten Jahr stattfinden können.
Gen- und Stammzelltherapie stehen für das, wovon die Medizin schon immer geträumt hat: geschädigtes Gewebe durch gesundes ersetzen und die Wirkung defekter Gene durch intakte Kopien korrigieren. Wie ist der Stand der weltweiten Forschung? Welche Hindernisse sind zu überwinden, damit mehr Patienten von der regenerativen Medizin profi tieren werden?
Editionen separieren Texte von den Kontexten, in denen sie bei ihrem Entstehungsprozess mit der Hand und technischen Schreibwerkzeugen unterschiedlichster Art geschrieben, als Erstdruck publiziert und von den Zeitgenossen ursprünglich rezipiert worden sind. Zugleich generieren sie, je nach ihren editorischen Prämissen, für die späteren Leser durch die von ihnen vollzogene Selektion, die Anordnung nach Textsorten oder die Anwendung anderer Strukturierungsregeln sowie durch die dabei vorgenommene Hierarchisierung, Kommentierung oder auch Nicht-Kommentierung ihrerseits neue Kontexte und konstruieren so ein bestimmtes, die Rezeption lenkendes Profil von Autor und Werk. Das ist, wie bei anderen prominenten Autoren, auch in der Wirkungsgeschichte Walter Benjamins der Fall. Ich möchte diesem Spannungsverhältnis von Dekontextualisierung und Rekontextualisierung im Folgenden am Beispiel der sogenannten 'kleineren' literaturkritischen Arbeiten - schon das Epitheton ist ein Beispiel für den erwähnten Selektions- und Hierarchisierungsprozess - nachgehen, also anhand der 'Kritiken und Rezensionen', die Benjamin seit der zweiten Hälfte der 1920er Jahre in der 'Frankfurter Zeitung', der 'Literarischen Welt' und an anderer Stelle veröffentlicht hat und deren Korpus im Wesentlichen in dem 1972 publizierten dritten Band der 'Gesammelten Schriften' publiziert worden ist. Ich werde mich dabei, in Blick auf den für diesen Beitrag zur Verfügung stehenden Raum, auf die Skizze zentraler Grundprobleme, auf pointierte Thesen und exemplarische Beispiele beschränken – in der Hoffnung, gerade durch solche Verknappung und Pointierung Impulse für eine weiterführende Diskussion der angesprochenen Probleme zu liefern. Einleitend werde ich zunächst einige grundsätzliche Fragen der Benjamin-Edition skizzieren. Im Anschluss daran werde ich die aktuelle Editionslage von Benjamins Arbeiten zur Literaturkritik im Hinblick auf die Leitfrage meines Beitrags, also auf das Spannungsverhältnis von Text(en) und Kontext(en), kritisch analysieren. Schließlich soll anhand einiger ausgewählter Rezensionen exemplarisch gezeigt werden, welche Bedeutung die in der bisherigen Editionspraxis meist ausgeblendeten Kontexte (z.B. Publikations-, Medien-, Wissenschaftskontexte, biografisch-soziale Kontexte, historische und politische Kontexte etc.) für ein Verständnis des Literaturkritikers Benjamin gewinnen können, sofern man ihnen editorisch die gebührende Beachtung schenkt. Dabei werden Umrisse eines neuen und anderen Benjamin-Bildes sichtbar, das sich von dem bisher verbreiteten nicht nur in Nuancen unterscheidet.