Two-dimensional crossover and strong coupling of plasmon excitations in arrays of one-dimensional atomic wires

The collective electronic excitations of arrays of Au chains on regularly stepped Si(553) and Si(775) surfaces were studied using electron loss spectroscopy with simultaneous high energy and momentum resolution (ELS-LEED) in combination with low energy electron diffraction (SPA-LEED) and tunneling microscopy. Both surfaces contain a double chain of gold atoms per terrace. Although one-dimensional metallicity and plasmon dispersion is observed only along the wires, two-dimensional effects are important, since plasmon dispersion explicitly depends both on the structural motif of the wires and the terrace width. The electron density on each terrace turns out to be modulated, as seen by tunneling spectroscopy (STS). The effective wire width of 7.5\,\AA\ for Si(553)-Au -- 10.2\,\AA\ for Si(775)-Au -- , determined from plasmon dispersion is in good agreement with STS data. Clear evidence for coupling between wires is seen beyond nearest neighbor coupling.Comment: 5 pages, 4 figure

Automatic Identification of Faked and Fraudulent Interviews in Surveys by Two Different Methods

This paper presents two new tools for the identification of faking interviewers in surveys. One method is based on Benford's Law, and the other exploits the empirical observation that fakers most often produce answers with less variability than could be expected from the whole survey. We focus on fabricated data, which were taken out of the survey before the data were disseminated in the German Socio-Economic Panel (SOEP). For two samples, the resulting rankings of the interviewers with respect to their cheating behavior are given. For both methods all of the evident fakers are identified.

Efficient Nearest Neighbor Search on Metric Time Series

While Deep-Learning approaches beat Nearest-Neighbor classifiers in an increasing number of areas, searching existing uncertain data remains an exclusive task for similarity search. Numerous specific solutions exist for different types of data and queries. This thesis aims at finding fast and general solutions for searching and indexing arbitrarily typed time series. A time series is considered a sequence of elements where the elements' order matters but not their actual time stamps. Since this thesis focuses on measuring distances between time series, the metric space is the most appropriate concept where the time series' elements come from. Hence, this thesis mainly considers metric time series as data type. Simple examples include time series in Euclidean vector spaces or graphs. For general similarity search solutions in time series, two primitive comparison semantics need to be distinguished, the first of which compares the time series' trajectories ignoring time warping. A ubiquitous example of such a distance function is the Dynamic Time Warping distance (DTW) developed in the area of speech recognition. The Dog Keeper distance (DK) is another time-warping distance that, opposed to DTW, is truly invariant under time warping and yields a metric space. After canonically extending DTW to accept multi-dimensional time series, this thesis contributes a new algorithm computing DK that outperforms DTW on time series in high-dimensional vector spaces by more than one order of magnitude. An analytical study of both distance functions reveals the reasons for the superiority of DK over DTW in high-dimensional spaces. The second comparison semantic compares time series in Euclidean vector spaces regardless of their position or orientation. This thesis proposes the Congruence distance that is the Euclidean distance minimized under all isometric transformations; thus, it is invariant under translation, rotation, and reflection of the time series and therefore disregards the position or orientation of the time series. A proof contributed in this thesis shows that there can be no efficient algorithm computing this distance function (unless P=NP). Therefore, this thesis contributes the Delta distance, a metric distance function serving as a lower bound for the Congruence distance. While the Delta distance has quadratic time complexity, the provided evaluation shows a speedup of more than two orders of magnitude against the Congruence distance. Furthermore, the Delta distance is shown to be tight on random time series, although the tightness can be arbitrarily bad in corner-case situations. Orthogonally to the previous mentioned comparison semantics, similarity search on time series consists of two different types of queries: whole sequence matching and subsequence search. Metric index structures (e. g., the M-Tree) only provide whole matching queries natively. This thesis contributes the concept of metric subset spaces and the SuperM-Tree for indexing metric subset spaces as a generic solution for subsequence search. Examples for metric subset spaces include subsequence search regarding the distance functions from the comparison semantics mentioned above. The provided evaluation shows that the SuperM-Tree outperforms a linear search by multiple orders of magnitude

Absorption and metabolism of modified mycotoxins of alternariol, alternariol monomethyl ether, and zearalenone in Caco-2 cells

Background and objectives Various cereals, fruits, and vegetables are commonly contaminated with mycotoxins such as zearalenone (ZEN), alternariol (AOH), and alternariol monomethyl ether (AME). More recently, their glucosidic metabolites formed in the plant have gained increasing attention. Experimental data on the contribution of modified mycotoxins to total toxicity are either controversy or lacking. Thus, the aim of this study was to investigate the absorption and metabolism of ZEN‐, AOH‐, and AME‐glucosides using the Caco‐2 cell system. Findings No quantifiable amounts of ZEN‐14‐glucoside, ZEN‐16‐glucoside, free ZEN, and ZEN metabolites were found in Caco‐2 cells and in the basolateral compartment. In contrast, glucosides of AOH and AME were absorbed and released their parental toxins, which were further metabolized to form glucuronides and sulfates to a variable extent. Metabolites were found on the basolateral site, too. There is also evidence that AOH‐9‐diglucoside is hydrolyzed to AOH‐9‐glucoside. Conclusion Our results demonstrate that modified ZEN is less absorbed whereas modified Alternaria toxins are taken up to a higher extent by Caco‐2 cells, followed by deglucosylation, metabolization, and transport to the basolateral site, suggesting a potential contribution to overall toxicity of these modified mycotoxins. Significance and novelty For the first time, absorption studies using modified Alternaria toxins in the Caco‐2 cell system were carried out

Demineralised skim milk concentrates by means of dynamic cross-flow microfiltration

At ambient temperature and native pH of milk, approx. 66 % of milk containing calcium is bound onto the casein micelles (micellar calcium), whereas approx. 34 % is in the serum phase presented as free serum calcium (Koutina et al. 2014). In membrane filtration processes such as microfiltration (nominal pore size 0.1 µm), the casein fraction is retained so that micellar calcium is enriched in the retentate and is subsequently in the final product. Micellar calcium can be solubilised by reducing pH and/or temperature. This can be applied to reduce the calcium content of the retentate via membrane fractionation. However, under certain temperature and pH combinations, casein micelles change from sol to the gel state and an enhanced gel layer is built up on the membrane surface and flux decreases rapidly (Brandsma & Rizvi 1999). We combined small amplitude oscillation shear rheology and photon correlation spectroscopy to examine the sol-gel-transition behaviour of pasteurised skim milk (protein content = 3.4 %) and microfiltrated (nominal pore size = 0.1 µm) skim milk retentates (protein content = 6 to 12 %) between pH 4.6 and 6.8 at temperatures ranging from 1 to 65 °C. The aim of this study was to predict pH-temperature-protein content combinations for membrane separation while maintaining adequate flux to get skim milk retentates with defined calcium content without macroscopic aggregated casein micelles. To proof the concept filtration experiments comparing appropriate and unappropriate pH-temperature combinations to get particle free calcium degraded skim milk retentates by means of a novel dynamic cross-microfiltration (nominal pore size: 0.06 and 0.2 µm) were carried out. Results will be shown and discussed. [1] Brandsma, R. L.; Rizvi, S.S.H. (1999): Depletion of Whey Proteins and Calcium by Microfiltration of Acidified Skim Milk Prior to Cheese Making. In: Journal of Dairy Science 82 (10), p. 2063–2069. [2] Koutina, G.; Knudsen, J. C.; Andersen, U.; Skibsted, L. H. (2014): Temperature effect on calcium and phosphorus equilibria in relation to gel formation during acidification of skim milk. In: International Dairy Journal 36 (1), p. 65–73

A Method for the Structural Investigation of Membrane Proteins

We investigated in meso crystallization of membrane proteins to develop a fast screening technology which combines features of the well established classical vapor diffusion experiment with the batch meso phase crystallization, but without premixing of protein and monoolein. It inherits the advantages of both methods, namely (i) the stabilization of membrane proteins in the meso phase, (ii) the control of hydration level and additive concentration by vapor diffusion. The new technology (iii) significantly simplifies in meso crystallization experiments and allows the use of standard liquid handling robots suitable for 96 well formats. CIMP crystallization furthermore allows (iv) direct monitoring of phase transformation and crystallization events. Bacteriorhodopsin (BR) crystals of high quality and diffraction up to 1.3 Å resolution have been obtained in this approach. CIMP and the developed consumables and protocols have been successfully applied to obtain crystals of sensory rhodopsin II (SRII) from Halobacterium salinarum for the first time

Post-depositional redistribution of trace metals in reservoir sediments of a mining/smelting-impacted watershed (the Lot River, SW France)

International audienceMining/smelting wastes and reservoir sediment cores from the Lot River watershed were studied using mineralogical (XRD, SEM-EDS, EMPA) and geochemical (redox dynamics, selective extractions) approaches to characterize the main carrier phases of trace metals. These two approaches permitted determining the role of post-depositional redistribution processes in sediments and their effects on the fate and mobility of trace metals. The mining/smelting wastes showed heterogeneous mineral compositions with highly variable contents of trace metals. The main trace metal-bearing phases include spinels affected by secondary processes, silicates and sulfates. The results indicate a clear change in the chemical partitioning of trace metals between the reservoir sediments upstream and downstream of the mining/smelting activities, with the downstream sediments showing a 2-fold to 5-fold greater contribution of the oxidizable fraction. This increase was ascribed to stronger post-depositional redistribution of trace metals related to intense early diagenetic processes, including dissolution of trace metal-bearing phases and precipitation of authigenic sulfide phases through organic matter (OM) mineralization. This redistribution is due to high inputs (derived from mining/smelting waste weathering) at the water-sediment interface of (i) dissolved SO4 promoting more efficient OM mineralization, and (ii) highly reactive trace metal-bearing particles. As a result, the main trace metal-bearing phases in the downstream sediments are represented by Zn- and Fe-sulfides, with minor occurrence of detrital zincian spinels, sulfates and Fe oxyhydroxides. Sequestration of trace metals in sulfides at depth in reservoir sediments does not represent long term sequestration owing to possible resuspension of anoxic sediments by natural (floods) and/or anthropogenic (dredging, dam flush) events that might promote trace metal mobilization through sulfide oxidation. It is estimated that, during a major flood event, about 870 t of Zn, 18 t of Cd, 25 t of Pb and 17 t of Cu could be mobilized from the downstream reservoir sediments along the Lot River by resuspension-induced oxidation of sulfide phases. These amounts are equivalent to 13-fold (Cd), not, vert, similar6-fold (Zn), 4-fold (Pb) the mean annual inputs of the respective dissolved trace metals into the Gironde estuary