Refine
Year of publication
- 2016 (1203) (remove)
Document Type
- Article (1203) (remove)
Language
- English (1203) (remove)
Keywords
- Magellanic Clouds (8)
- German (7)
- Eye movements (6)
- Sun: magnetic fields (6)
- climate change (6)
- intergalactic medium (6)
- methods: data analysis (6)
- techniques: spectroscopic (6)
- children (5)
- galaxies: formation (5)
Institute
- Institut für Geowissenschaften (216)
- Institut für Physik und Astronomie (201)
- Institut für Biochemie und Biologie (190)
- Institut für Chemie (155)
- Institut für Ernährungswissenschaft (49)
- Institut für Mathematik (48)
- Department Psychologie (41)
- Department Linguistik (30)
- Wirtschaftswissenschaften (27)
- Sozialwissenschaften (16)
We investigate the ensemble and time averaged mean squared displacements for particle diffusion in a simple model for disordered media by assuming that the local diffusivity is both fluctuating in time and has a deterministic average growth or decay in time. In this study we compare computer simulations of the stochastic Langevin equation for this random diffusion process with analytical results. We explore the regimes of normal Brownian motion as well as anomalous diffusion in the sub- and superdiffusive regimes. We also consider effects of the inertial term on the particle motion. The investigation of the resulting diffusion is performed for unconfined and confined motion.
Background
Non-typhoid Salmonella Typhimurium (S. Typhimurium) accounts for a high number of registered salmonellosis cases, and O-serotyping is one important tool for monitoring epidemiology and spread of the disease. Moreover, variations in glucosylated O-antigens are related to immunogenicity and spread in the host. However, classical autoagglutination tests combined with the analysis of specific genetic markers cannot always reliably register phase variable glucose modifications expressed on Salmonella O-antigens and additional tools to monitor O-antigen glucosylation phenotypes of S. Typhimurium would be desirable.
Results
We developed a test for the phase variable O-antigen glucosylation state of S. Typhimurium using the tailspike proteins (TSP) of Salmonella phages 9NA and P22. We used this ELISA like tailspike adsorption (ELITA) assay to analyze a library of 44 Salmonella strains. ELITA was successful in discriminating strains that carried glucose 1-6 linked to the galactose of O-polysaccharide backbone (serotype O1) from non-glucosylated strains. This was shown by O-antigen compositional analyses of the respective strains with mass spectrometry and capillary electrophoresis. The ELITA test worked rapidly in a microtiter plate format and was highly O-antigen specific. Moreover, TSP as probes could also detect glucosylated strains in flow cytometry and distinguish multiphasic cultures differing in their glucosylation state.
Conclusions
Tailspike proteins contain large binding sites with precisely defined specificities and are therefore promising tools to be included in serotyping procedures as rapid serotyping agents in addition to antibodies. In this study, 9NA and P22TSP as probes could specifically distinguish glucosylation phenotypes of Salmonella on microtiter plate assays and in flow cytometry. This opens the possibility for flow sorting of cell populations for subsequent genetic analyses or for monitoring phase variations during large scale O-antigen preparations necessary for vaccine production.
The title compounds, [(1R,3R,4R,5R,6S)-4,5-bis(acetyloxy)-7-oxo-2-oxabicyclo-
[4.2.0]octan-3-yl]methyl acetate, C14H18O8, (I), [(1S,4R,5S,6R)-5-acetyloxy-7-
hydroxyimino-2-oxobicyclo[4.2.0]octan-4-yl acetate, C11H15NO6, (II), and
[(3aR,5R,6R,7R,7aS)-6,7-bis(acetyloxy)-2-oxooctahydropyrano[3,2-b]pyrrol-5-
yl]methyl acetate, C14H19NO8, (III), are stable bicyclic carbohydrate derivatives.
They can easily be synthesized in a few steps from commercially available
glycals. As a result of the ring strain from the four-membered rings in (I) and
(II), the conformations of the carbohydrates deviate strongly from the ideal
chair form. Compound (II) occurs in the boat form. In the five-membered
lactam (III), on the other hand, the carbohydrate adopts an almost ideal chair
conformation. As a result of the distortion of the sugar rings, the configurations
of the three bicyclic carbohydrate derivatives could not be determined from
their NMR coupling constants. From our three crystal structure determinations,
we were able to establish for the first time the absolute configurations of all new
stereocenters of the carbohydrate rings.
We study the adsorption–desorption transition of polyelectrolyte chains onto planar, cylindrical and spherical surfaces with arbitrarily high surface charge densities by massive Monte Carlo computer simulations. We examine in detail how the well known scaling relations for the threshold transition—demarcating the adsorbed and desorbed domains of a polyelectrolyte near weakly charged surfaces—are altered for highly charged interfaces. In virtue of high surface potentials and large surface charge densities, the Debye–Hückel approximation is often not feasible and the nonlinear Poisson–Boltzmann approach should be implemented. At low salt conditions, for instance, the electrostatic potential from the nonlinear Poisson–Boltzmann equation is smaller than the Debye–Hückel result, such that the required critical surface charge density for polyelectrolyte adsorption σc increases. The nonlinear relation between the surface charge density and electrostatic potential leads to a sharply increasing critical surface charge density with growing ionic strength, imposing an additional limit to the critical salt concentration above which no polyelectrolyte adsorption occurs at all. We contrast our simulations findings with the known scaling results for weak critical polyelectrolyte adsorption onto oppositely charged surfaces for the three standard geometries. Finally, we discuss some applications of our results for some physical–chemical and biophysical systems.
Referential Choice
(2016)
We report a study of referential choice in discourse production, understood as the choice between various types of referential devices, such as pronouns and full noun phrases. Our goal is to predict referential choice, and to explore to what extent such prediction is possible. Our approach to referential choice includes a cognitively informed theoretical component, corpus analysis, machine learning methods and experimentation with human participants. Machine learning algorithms make use of 25 factors, including referent’s properties (such as animacy and protagonism), the distance between a referential expression and its antecedent, the antecedent’s syntactic role, and so on. Having found the predictions of our algorithm to coincide with the original almost 90% of the time, we hypothesized that fully accurate prediction is not possible because, in many situations, more than one referential option is available. This hypothesis was supported by an experimental study, in which participants answered questions about either the original text in the corpus, or about a text modified in accordance with the algorithm’s prediction. Proportions of correct answers to these questions, as well as participants’ rating of the questions’ difficulty, suggested that divergences between the algorithm’s prediction and the original referential device in the corpus occur overwhelmingly in situations where the referential choice is not categorical.
Loss to follow-up in a randomized controlled trial study for pediatric weight management (EPOC)
(2016)
Background
Attrition is a serious problem in intervention studies. The current study analyzed the attrition rate during follow-up in a randomized controlled pediatric weight management program (EPOC study) within a tertiary care setting.
Methods
Five hundred twenty-three parents and their 7–13-year-old children with obesity participated in the randomized controlled intervention trial. Follow-up data were assessed 6 and 12 months after the end of treatment. Attrition was defined as providing no objective weight data. Demographic and psychological baseline characteristics were used to predict attrition at 6- and 12-month follow-up using multivariate logistic regression analyses.
Results
Objective weight data were available for 49.6 (67.0) % of the children 6 (12) months after the end of treatment. Completers and non-completers at the 6- and 12-month follow-up differed in the amount of weight loss during their inpatient stay, their initial BMI-SDS, educational level of the parents, and child’s quality of life and well-being. Additionally, completers supported their child more than non-completers, and at the 12-month follow-up, families with a more structured eating environment were less likely to drop out. On a multivariate level, only educational background and structure of the eating environment remained significant.
Conclusions
The minor differences between the completers and the non-completers suggest that our retention strategies were successful. Further research should focus on prevention of attrition in families with a lower educational background.
Due to their multifunctionality, tablets offer tremendous advantages for research on handwriting dynamics or for interactive use of learning apps in schools. Further, the widespread use of tablet computers has had a great impact on handwriting in the current generation. But, is it advisable to teach how to write and to assess handwriting in pre- and primary schoolchildren on tablets rather than on paper? Since handwriting is not automatized before the age of 10 years, children's handwriting movements require graphomotor and visual feedback as well as permanent control of movement execution during handwriting. Modifications in writing conditions, for instance the smoother writing surface of a tablet, might influence handwriting performance in general and in particular those of non-automatized beginning writers. In order to investigate how handwriting performance is affected by a difference in friction of the writing surface, we recruited three groups with varying levels of handwriting automaticity: 25 preschoolers, 27 second graders, and 25 adults. We administered three tasks measuring graphomotor abilities, visuomotor abilities, and handwriting performance (only second graders and adults). We evaluated two aspects of handwriting performance: the handwriting quality with a visual score and the handwriting dynamics using online handwriting measures [e.g., writing duration, writing velocity, strokes and number of inversions in velocity (NIV)]. In particular, NIVs which describe the number of velocity peaks during handwriting are directly related to the level of handwriting automaticity. In general, we found differences between writing on paper compared to the tablet. These differences were partly task-dependent. The comparison between tablet and paper revealed a faster writing velocity for all groups and all tasks on the tablet which indicates that all participants—even the experienced writers—were influenced by the lower friction of the tablet surface. Our results for the group-comparison show advancing levels in handwriting automaticity from preschoolers to second graders to adults, which confirms that our method depicts handwriting performance in groups with varying degrees of handwriting automaticity. We conclude that the smoother tablet surface requires additional control of handwriting movements and therefore might present an additional challenge for learners of handwriting.
Hybrid terrain models combine large regular data sets and high-resolution irregular meshes [triangulated irregular network (TIN)] for topographically and morphologically complex terrain features such as man-made microstructures or cliffs. In this paper, a new method to generate and visualize this kind of 3D hybrid terrain models is presented. This method can integrate geographic data sets from multiple sources without a remeshing process to combine the heterogeneous data of the different models. At the same time, the original data sets are preserved without modification, and, thus, TIN meshes can be easily edited and replaced, among other features. Specifically, our approach is based on the utilization of the external edges of convexified TINs as the fundamental primitive to tessellate the space between both types of meshes. Our proposal is eminently parallel, requires only a minimal preprocessing phase, and minimizes the storage requirements when compared with the previous proposals.
This paper presents an interactive system for transforming images into an oil paint look. The system comprises two major stages. First, it derives dominant colors from an input image for feature-aware recolorization and quantization to conform with a global color palette. Afterwards, it employs non-linear filtering based on the smoothed structure adapted to the main feature contours of the quantized image to synthesize a paint texture in real-time. Our filtering approach leads to homogeneous outputs in the color domain and enables creative control over the visual output, such as color adjustments and per-pixel parametrizations by means of interactive painting. To this end, our system introduces a generalized brush-based painting interface that operates within parameter spaces to locally adjust the level of abstraction of the filtering effects. Several results demonstrate the various applications of our filtering approach to different genres of photography. (C) 2015 Elsevier Ltd. All rights reserved.
Arabidopsis FORGETTER1 mediates stress-induced chromatin memory through nucleosome remodeling
(2016)
Plants as sessile organisms can adapt to environmental stress to mitigate its adverse effects. As part of such adaptation they maintain an active memory of heat stress for several days that promotes a more efficient response to recurring stress. We show that this heat stress memory requires the activity of the FORGETTER1 (FGT1) locus, with fgt1 mutants displaying reduced maintenance of heat-induced gene expression. FGT1 encodes the Arabidopsis thaliana orthologue of Strawberry notch (Sno), and the protein globally associates with the promoter regions of actively expressed genes in a heat-dependent fashion. FGT1 interacts with chromatin remodelers of the SWI/ SNF and ISWI families, which also display reduced heat stress memory. Genomic targets of the BRM remodeler overlap significantly with FGT1 targets. Accordingly, nucleosome dynamics at loci with altered maintenance of heat-induced expression are affected in fgt1. Together, our results suggest that by modulating nucleosome occupancy, FGT1 mediates stress-induced chromatin memory.
The novel combination of infrared matrix-assisted laser dispersion and ionization (IR-MALDI) with ion mobility (IM) spectrometry makes it possible to investigate biomolecules in their natural environment, liquid water. As an alternative to an ESI source, the IR-MALDI source was implemented in an in-house-developed ion mobility (IM) spectrometer. The release of ions directly from an aqueous solution is based on a phase explosion, induced by the absorption of an IR laser pulse (lambda = 2.94 mu m, 6 ns pulse width), which disperses the liquid as nano- and micro-droplets. The prerequisites for the application of IR-MALDI-IM spectrometry as an analytical method are narrow analyte ion signal peaks for a high spectrometer resolution. This can only be achieved by improving the desolvation of ions. One way to full desolvation is to give the cluster ions sufficient time to desolvate. Two methods for achieving this are studied: the implementation of an additional drift tube, as in ESI-IM-spectrometry, and the delayed extraction of the ions. As a result of this optimization procedure, limits of detection between 5 nM and 2.5 mu M as well as linear dynamic ranges of 2-3 orders of magnitude were obtained for a number of substances. The ability of this method to analyze simple mixtures is illustrated by the separation of two different surfactant mixtures.
Background
Doping presents a potential health risk for young athletes. Prevention programs are intended to prevent doping by educating athletes about banned substances. However, such programs have their limitations in practice. This led Germany to introduce the National Doping Prevention Plan (NDPP), in hopes of ameliorating the situation among young elite athletes. Two studies examined 1) the degree to which the NDPP led to improved prevention efforts in elite sport schools, and 2) the extent to which newly developed prevention activities of the national anti-doping agency (NADA) based on the NDPP have improved knowledge among young athletes within elite sports schools.
Methods
The first objective was investigated in a longitudinal study (Study I: t0 = baseline, t1 = follow-up 4 years after NDPP introduction) with N = 22 teachers engaged in doping prevention in elite sports schools. The second objective was evaluated in a cross-sectional comparison study (Study II) in N = 213 elite sports school students (54.5 % male, 45.5 % female, age M = 16.7 ± 1.3 years (all students had received the improved NDDP measure in school; one student group had received additionally NADA anti-doping activities and a control group did not). Descriptive statistics were calculated, followed by McNemar tests, Wilcoxon tests and Analysis of Covariance (ANCOVA).
Results
Results indicate that 4 years after the introduction of the NDPP there have been limited structural changes with regard to the frequency, type, and scope of doping prevention in elite sport schools. On the other hand, in study II, elite sport school students who received further NADA anti-doping activities performed better on an anti-doping knowledge test than students who did not take part (F(1, 207) = 33.99, p <0.001), although this difference was small.
Conclusion
The integration of doping-prevention in elite sport schools as part of the NDPP was only partially successful. The results of the evaluation indicate that the introduction of the NDPP has contributed more to a change in the content of doping prevention activities than to a structural transformation in anti-doping education in elite sport schools. Moreover, while students who did receive additional education in the form of the NDPP“booster sessions” had significantly more knowledge about doping than students who did not receive such education, this difference was only small and may not translate to actual behavior.
Infrared matrix-assisted laser dispersion and ionization (IR-MALDI) in combination with ion mobility (IM) spectrometry enables the direct analysis of biomolecules in aqueous solution. The release of ions directly from an aqueous solution is based on a phase explosion, induced by the absorption of an IR laser pulse, which disperses the liquid as vapor, nano-and micro-droplets. The ionization process is characterized initially by a broad spatial distribution of the ions, which is a result of complex fluid dynamics and desolvation kinetics. These processes have a profound effect on the shape and width of the peaks in the IM spectra. In this work, the transport of ions by the phase explosion-induced shockwave could be studied independently from the transport by the electric field. The shockwave-induced mean velocities of the ions at different time scales were determined through IM spectrometry and shadowgraphy. The results show a deceleration of the ions from 118 m.s(-1) at a distance of 400 mu m from the liquid surface to 7.1 m.s(-1) at a distance of 10 mm, which is caused by a pile-up effect. Furthermore, the desolvation kinetics were investigated and a first-order desolvation constant of 325 +/- 50 s(-1) was obtained. In the second part, the IR-MALDI-IM spectrometer is used as an HPLC detector for the two-dimensional separation of a pesticide mixture.
National doping prevention guidelines: Intent, efficacy and lessons learned - A 4-year evaluation
(2016)
Background: Doping presents a potential health risk for young athletes. Prevention programs are intended to prevent doping by educating athletes about banned substances. However, such programs have their limitations in practice. This led Germany to introduce the National Doping Prevention Plan (NDPP), in hopes of ameliorating the situation among young elite athletes. Two studies examined 1) the degree to which the NDPP led to improved prevention efforts in elite sport schools, and 2) the extent to which newly developed prevention activities of the national anti-doping agency (NADA) based on the NDPP have improved knowledge among young athletes within elite sports schools. Methods: The first objective was investigated in a longitudinal study (Study I: t0 = baseline, t1 = follow-up 4 years after NDPP introduction) with N = 22 teachers engaged in doping prevention in elite sports schools. The second objective was evaluated in a cross-sectional comparison study (Study II) in N = 213 elite sports school students (54. 5 % male, 45.5 % female, age M = 16.7 +/- 1.3 years (all students had received the improved NDDP measure in school; one student group had received additionally NADA anti-doping activities and a control group did not). Descriptive statistics were calculated, followed by McNemar tests, Wilcoxon tests and Analysis of Covariance (ANCOVA). Results: Results indicate that 4 years after the introduction of the NDPP there have been limited structural changes with regard to the frequency, type, and scope of doping prevention in elite sport schools. On the other hand, in study II, elite sport school students who received further NADA anti-doping activities performed better on an anti-doping knowledge test than students who did not take part (F(1, 207) = 33.99, p < 0.001), although this difference was small. Conclusion: The integration of doping-prevention in elite sport schools as part of the NDPP was only partially successful. The results of the evaluation indicate that the introduction of the NDPP has contributed more to a change in the content of doping prevention activities than to a structural transformation in anti-doping education in elite sport schools. Moreover, while students who did receive additional education in the form of the NDPP "booster sessions" had significantly more knowledge about doping than students who did not receive such education, this difference was only small and may not translate to actual behavior.
Recently, ant colony optimization (ACO) algorithms have proven to be efficient in uncertain environments, such as noisy or dynamically changing fitness functions. Most of these analyses have focused on combinatorial problems such as path finding. We rigorously analyze an ACO algorithm optimizing linear pseudo- Boolean functions under additive posterior noise. We study noise distributions whose tails decay exponentially fast, including the classical case of additive Gaussian noise. Without noise, the classical (mu + 1) EA outperforms any ACO algorithm, with smaller mu being better; however, in the case of large noise, the (mu + 1) EA fails, even for high values of mu (which are known to help against small noise). In this article, we show that ACO is able to deal with arbitrarily large noise in a graceful manner; that is, as long as the evaporation factor. is small enough, dependent on the variance s2 of the noise and the dimension n of the search space, optimization will be successful. We also briefly consider the case of prior noise and prove that ACO can also efficiently optimize linear functions under this noise model.
Monitoring the apple polyphenol oxidase-modulated adduct formation of phenolic and amino compounds
(2016)
Minimally processed fruit products such as smoothies are increasingly coming into demand. However, they are often combined with dairy ingredients. In this combination, phenolic compounds, polyphenoloxidases, and amino compounds could interact. In this work, a model approach is presented where apple serves as a source for a high polyphenoloxidase activity for modulating the reactions. The polyphenoloxidase activity ranged from 128 to 333 nakt/mL in different apple varieties. From these, ‘Braeburn’ was found to provide the highest enzymatic activity. The formation and stability of resulting chromogenic conjugates was investigated. The results show that such adducts are not stable and possible degradation mechanisms leading to follow-up products formed are proposed. Finally, apple extracts were used to modify proteins and their functional properties characterized. There were retaining antioxidant properties inherent to phenolic compounds after adduct formation. Consequently, such interactions may also be utilized to improve the textural quality of food products.
In this study, the applicability of semi-direct cold atmospheric pressure plasma (CAPP) during postharvest processing of Tenebrio molitor flour is investigated. Besides analyzing the decontamination efficacy, plasma induced impact on techno-functionality, protein solubility, composition and structure was determined and compared to heat induced effects. Following CAPP treatment, the total microbial load of the Tenebrio flour of 7.72 log(10) cfu/g was reduced to 7.10 (1 min), 6.72 (2.5 min), 5.79 (5 min), 5.19 (7.5 min), 521 (10 min) and 4.73 (15 min) log(10) cfu/g. With increasing exposure to CAPP, protein solubility at pH 4 almost linearly decreased to a minimum of 54%. Water binding capacity decreased from 0.79 to 0.64 gwatedg whereas oil binding capacity increased from 0.59 to 0.66 g(oil)/g. Gel electrophoresis revealed a decrease of all protein fractions at pH 4 whereas at pH 10 the band pattern significantly shifted to protein fractions with higher molecular weights. Industrial relevance: Edible insects are rich in valuable protein, fat, fibre, minerals and micronutrients. Although a wide range of species represent a valuable alternative protein source that could contribute to food and feed security, they are industrially hardly exploited. The tailored application of proper processing technologies could lead to novel insect-based high-protein food and feed products with unique functional properties supporting the increase in acceptability among potential consumers. Current research concentrates on developing processing chains including innovative nonthermal approaches. Cold atmospheric pressure plasma (CAPP) has gained attention as an effective technology for the decontamination and modification of fresh and dry agricultural products. In the postharvest chain of edible insects, the application of CAPP could contribute to the development of safe and high-quality insect-based products in the food and feed sector. (C) 2016 Published by Elsevier Ltd.
Two visual world eyetracking experiments investigated how acoustic cue value and statistical variance affect perceptual uncertainty during Cantonese consonant (Experiment 1) and tone perception (Experiment 2). Participants heard low- or high-variance acoustic stimuli. Euclidean distance of fixations from target and competitor pictures over time was analysed using Generalised Additive Mixed Modelling. Distance of fixations from target and competitor pictures varied as a function of acoustic cue, providing evidence for gradient, nonlinear sensitivity to cue values. Moreover, cue value effects significantly interacted with statistical variance, indicating that the cue distribution directly affects perceptual uncertainty. Interestingly, the time course of effects differed between target distance and competitor distance models. The pattern of effects over time suggests a global strategy in response to the level of uncertainty: as uncertainty increases, verification looks increase accordingly. Low variance generally creates less uncertainty, but can lead to greater uncertainty in the face of unexpected speech tokens. (C) 2016 Elsevier Inc. All rights reserved.
When sampling animal movement paths, the frequency at which location measurements are attempted is a critical feature for data analysis. Important quantities derived from raw data, e.g. travel distance or sinuosity, can differ largely based on the temporal resolution of the data. Likewise, when movement models are fitted to data, parameter estimates have been demonstrated to vary with sampling rate. Thus, biological statements derived from such analyses can only be made with respect to the resolution of the underlying data, limiting extrapolation of results and comparison between studies. To address this problem, we investigate whether there are models that are robust against changes in temporal resolution. First, we propose a mathematically rigorous framework, in which we formally define robustness as a model property. We then use the framework for a thorough assessment of a range of basic random walk models, in which we also show how robustness relates to other probabilistic concepts. While we found robustness to be a strong condition met by few models only, we suggest a new method to extend models so as to make them robust. Our framework provides a new systematic, mathematically founded approach to the question if, and how, sampling rate of movement paths affects statistical inference.