Predicting extreme equity returns with binary response models

In this paper a parsimonious methodology for estimating the probability of observing an extreme negative movement in monthly stock returns is proposed. It uses Extreme Value Theory to define an extreme return and exploits dynamic probit models based on (Kauppi and Saikkonen 2008) which are expected to improve the performance of the regression. The results are convincing, as the dynamic feature indeed enhances the models’ performance. Moreover, successive extreme returns are observed, confirming the fact of extremal clustering in the tails of the distribution

Quantifying the impact of chemicals on stable carbon and oxygen isotope values of raw pollen

Purification protocols to extract pollen from lake sediments contain chemicals that alter the carbon and oxygen pollen‐isotope values according to pollen characteristics and family affiliation. Modern (raw) pollen of broad‐leaved (Alnus glutinosa, Betula pendula, Carpinus betulus, Corylus avellana, Fagus sylvatica and Quercus robur) and coniferous tree species (Picea abies and Pinus sylvestris) were treated with potassium hydroxide (KOH), hydrofluoric acid (HF), sodium hypochlorite (NaClO) and sulphuric acid (H2SO4) to test the impact on δ13Cpollen and δ18Opollen and assess the applicability in purification protocols. Pollen of broad‐leaved and coniferous trees reacted differently to chemical exposure, but response patterns are generally alike. Alterations of δ13Cpollen values vary between + 1.0‰ (B. pendula, NaClO‐treatment) and −5.0‰ (P. sylvestris, H2SO4‐treatment). The δ13Cpollen values of raw and chemically treated samples seem to be related after treatments with KOH, NaClO and HF, whereas the application of H2SO4 led to inconsistent changes among species. The impact of chemicals on δ18Opollen are more diverse and offsets range between +1.1‰ (C. avellana, NaClO‐treatment) and −17.9‰ (P. sylvestris, H2SO4‐treatment). In general, the use of isotope‐altering chemicals in purification protocols should be brought to a minimum, but the application of KOH and NaClO seems mostly unproblematic before δ13Cpollen and δ18Opollen analysis

Adaptives luftqualitätsgewichtetes Fahrradrouting mittels Land-use Regression auf Basis offener Daten

Luftschadstoffen ausgesetzt zu sein hat langfristige negative gesundheitliche Folgen, denen besonders Fahrradfahrer im urbanen Raum ausgesetzt sind. Dabei gibt es wahrscheinlich keine unschädliche Dosis: weniger ist immer besser. Diese Arbeit zeigt, dass luftqualitätsgewichtete Fahrradrouten die persönliche Exposition gemäß dem Regressionsmodell deutlich reduzieren können, wobei die errechneten Umwege zumeist nur minimal sind. Auf Basis offener Daten wird ein neuronales Netzwerk zur Schätzung der Luftqualität trainiert. Dabei werden PM10-Daten aus mobilen Messungen als Indikator der Luftqualität verwendet. Das entstehende Land-Use-Regression-Modell bezieht dabei sowohl zeitliche als auch räumliche Features mit ein. Anschließend wird dieses Modell verwendet, um luftqualitätsgewichtete Routen zu berechnen. Dabei wird gezeigt, wie ein solches feingranulare Modell im Routing verwendet werden kann. Anhand von zufällig gewählten Start/Ziel Paaren werden die luftqualitätsgewichteten Routen mit der jeweils kürzesten Strecke verglichen

OCT angiography in optic disc drusen: comparison with structural and functional parameters

Background: Optic disc drusen (ODD) can cause retinal nerve fibre layer (RNFL) defects with progressive visual field (VF) loss. Microvascular changes are discussed as a cause. We measured the vessel density (VD) of the optic disc in ODD using optical coherence tomography angiography and compared it with a normal population. Another intent was to determine the sensitivity and correlations in comparison with functional (VF) and structural parameters (RNFL, minimum rim width (MRW), ganglion cell complex (GCC)). Methods: We analysed the VD of 25 patients with ODD and an age-matched control population including 25 healthy participants using AngioVue (Optovue, Fremont, CA, USA). We obtained data about RNFL, GCC, Bruch's membrane opening MRW (Spectralis HRA & OCT;Heidelberg Engineering, Germany) and VF (standard automated perimetry;SITA 24-2). Low image quality and pathologies interfering with the diagnostics were excluded. Parametric data were analysed using the t-test and non-parametric values using the Mann-Whitney U test. Linear regression analysis was used to determine correlations using the Bravais-Pearson test. Results: The VD was significantly reduced in the ODD group especially the peripapillary capillary VD (n=45 vs 50 eyes;mean 43.15% vs 51.70%). Peripapillary RNFL thickness correlated with the VD significantly (r=0.902 (n=44), 0.901 (n=44), 0.866 (n=45)). The RNFL analysis showed a reduction in ODD, especially the superior hemisphere (mean 107 mu m, 129 mu m;49 vs 50 eyes). The GCC was significantly lower in the ODD group (n=38 vs 40;mean 87 mu m vs 98 mu m). Positive correlation between the VD and the GCC was significant (n=37, r=0.532). There is a significant negative correlation (n=19;r=-0.726) between the VD and the pattern standard deviation (PSD). Conclusion This study reveals significant peripapillary microvascular changes in patients with ODD correlating with the RNFL and GCC reduction. There is a negative correlation between the PSD and the VD

Triphenylene-Derived Electron Acceptors and Donors on Ag(111):Formation of Intermolecular Charge-Transfer Complexes with Common Unoccupied Molecular States

Over the past years, ultrathin films consisting of electron donating and accepting molecules have attracted increasing attention due to their potential usage in optoelectronic devices. Key parameters for understanding and tuning their performance are intermolecular and molecule–substrate interactions. Here, the formation of a monolayer thick blend of triphenylene‐based organic donor and acceptor molecules from 2,3,6,7,10,11‐hexamethoxytriphenylene (HAT) and 1,4,5,8,9,12‐hexaazatriphenylenehexacarbonitrile (HATCN), respectively, on a silver (111) surface is reported. Scanning tunneling microscopy and spectroscopy, valence and core level photoelectron spectroscopy, as well as low‐energy electron diffraction measurements are used, complemented by density functional theory calculations, to investigate both the electronic and structural properties of the homomolecular as well as the intermixed layers. The donor molecules are weakly interacting with the Ag(111) surface, while the acceptor molecules show a strong interaction with the substrate leading to charge transfer and substantial buckling of the top silver layer and of the adsorbates. Upon mixing acceptor and donor molecules, strong hybridization occurs between the two different molecules leading to the emergence of a common unoccupied molecular orbital located at both the donor and acceptor molecules. The donor acceptor blend studied here is, therefore, a compelling candidate for organic electronics based on self‐assembled charge‐transfer complexes

Detection of a New Resistance-Mediating Plasmid Chimera in a blaOXA-48-Positive Klebsiella pneumoniae Strain at a German University Hospital

Mobile genetic elements, such as plasmids, facilitate the spread of antibiotic resistance genes in Enterobacterales. In line with this, we investigated the plasmid-resistome of seven blaOXA-48 gene-carrying Klebsiella pneumoniae isolates, which were isolated between 2013 and 2014 at the University Medical Center in Göttingen, Germany. All isolates were subjected to complete genome sequencing including the reconstruction of entire plasmid sequences. In addition, phenotypic resistance testing was conducted. The seven isolates comprised both disease-associated isolates and colonizers isolated from five patients. They fell into two clusters of three sequence type (ST)101 and two ST11 isolates, respectively; and ST15 and ST23 singletons. The seven isolates harbored various plasmids of the incompatibility (Inc) groups IncF, IncL/M, IncN, IncR, and a novel plasmid chimera. All blaOXA-48 genes were encoded on the IncL/M plasmids. Of note, distinct phenotypical resistance patterns associated with different sets of resistance genes encoded by IncL/M and IncR plasmids were observed among isolates of the ST101 cluster in spite of high phylogenetic relatedness of the bacterial chromosomes, suggesting nosocomial transmission. This highlights the importance of plasmid uptake and plasmid recombination events for the fast generation of resistance variability after clonal transmission. In conclusion, this study contributes a piece in the puzzle of molecular epidemiology of resistance gene-carrying plasmids in K. pneumoniae in Germany.Peer Reviewe

Wicked facets of the German energy transition – examples from the electricity, heating, transport, and industry sectors

We shed light on wicked problems in the German energy transition. Our methods consist of a multiple-case study and multi-criteria analysis, utilising the wicked problems theoretical framework introduced by Horst Rittel and Melvin Webber [1973. “Dilemmas in a General Theory of Planning.” Policy Sciences 4 (2): 155–169. Accessed August 20, 2019. https://doi.org/10.1007/BF01405730]. Results from the energy supply, heating/cooling, transport, and industry sectors illustrate where and how the 10-point frame of wicked problems manifests in the German energy transition. The four cases exhibit more wicked tendencies in the governance domain than the technical domain and differ in their degrees of technology maturity, policy regulation, and knowledge states. We do not find that the German energy transition is inherently wicked. However, wickedness unfolds through the social setting into which technical solutions of the energy transition are embedded. We aim to highlight these intricacies and encourage scrutinising these wicked facets early on

How defects in lanthanum iron manganite perovskite structures promote the catalytic reduction of NO by CO

Adjusting the defect level during synthesis of A- and B-site deficient lanthanum iron manganite (LFM) perovskites shows that non-stoichiometry can beneficially influence the catalytic reactivity to N2 in the reduction of NO by CO on noble metal-free LFM-based perovskites. Optimal steering of La deficiency and the associated redox chemistry to reduce the near-surface regions during catalytic operation at low temperatures is the key factor. Surface enrichment by reducible B site cations and a proper design of structural defects resulting from the optimum introduction of La defects exclusively cause in-situ reduction of surface-near regions by CO oxidation, as well as formation of oxygen vacancies for enhanced NO and N2O reactivity. Excess doping with defects causes structural instability and continuous supply of oxygen from the catalyst bulk to the surface at elevated temperatures. Introduction of B site vacancies leads to surface enrichment by non-reducible lanthanum cations, causing suppressed catalyst activity undercutting even stoichiometric LFM