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Scratch iridescence: Wave-optical rendering of diffractive surface structure [article]

Sebastian Werner, Zdravko Velinov, Wenzel Jakob, Matthias B. Hullin
2017 arXiv   pre-print
The surface of metal, glass and plastic objects is often characterized by microscopic scratches caused by manufacturing and/or wear. A closer look onto such scratches reveals iridescent colors with a complex dependency on viewing and lighting conditions. The physics behind this phenomenon is well understood; it is caused by diffraction of the incident light by surface features on the order of the optical wavelength. Existing analytic models are able to reproduce spatially unresolved
more » ... re such as the iridescent appearance of compact disks and similar materials. Spatially resolved scratches, on the other hand, have proven elusive due to the highly complex wave-optical light transport simulations needed to account for their appearance. In this paper, we propose a wave-optical shading model based on non-paraxial scalar diffraction theory to render this class of effects. Our model expresses surface roughness as a collection of line segments. To shade a point on the surface, the individual diffraction patterns for contributing scratch segments are computed analytically and superimposed coherently. This provides natural transitions from localized glint-like iridescence to smooth BRDFs representing the superposition of many reflections at large viewing distances. We demonstrate that our model is capable of recreating the overall appearance as well as characteristic detail effects observed on real-world examples.
arXiv:1705.06086v1 fatcat:is2op3nqazf4rdpg3vqaxx3fou

In Situ Experiments To Reveal the Role of Surface Feature Sidewalls in the Cassie–Wenzel Transition

René Hensel, Andreas Finn, Ralf Helbig, Sebastian Killge, Hans-Georg Braun, Carsten Werner
2014 Langmuir  
Figure 4 . 4 In situ observations of the Cassie−Wenzel transition.  ...  Two different scenarios have been discussed for the Cassie− Wenzel transition, namely, sagging and depinning.  ... 
doi:10.1021/la503601u pmid:25496232 pmcid:PMC4284134 fatcat:pi6ncuiu3jdvbdh5aakyclafim

Defects in active nematics: algorithms for identification and tracking [article]

Dennis Wenzel, Michael Nestler, Sebastian Reuther, Maximilian Simon, Axel Voigt
2020 arXiv   pre-print
The growing interest in active nematics and the emerging evidence of the relevance of topological defects in biology asks for reliable data analysis tools to identify, classify and track such defects in simulation and microscopy data. We here provide such tools and demonstrate on two examples, on an active turbulent state in an active nematodynamic model and on emerging nematic order in a multi-phase field model, the possibility to compare statistical data on defect velocities with experimental
more » ... results. The considered tools, which are physics based and data driven, are compared with each other.
arXiv:2002.02748v1 fatcat:jir6t43nmzeq3arlz4oxvlyjqu

A reliable modifier-adaptation strategy for real-time optimization

Weihua Gao, Simon Wenzel, Sebastian Engell
2016 Computers and Chemical Engineering  
In model-based real-time optimization, plant-model mismatch can be handled by applying bias-and gradient-corrections to the cost and constraint functions in an iterative optimization procedure. One of the major challenges in practice is the estimation of the plant gradients from noisy measurement data, in particular for several optimization variables. In this paper we propose a new real-time optimization scheme that explores the inherent smoothness of the plant mapping to enable a reliable
more » ... ization. The idea here is to combine the quadratic approximation approach used in derivative-free optimization techniques with the iterative gradient-modification optimization scheme. The convergence of the scheme is analyzed. Simulation studies for the optimization of a ten-variable synthetic example and a reactor benchmark problem with considerable plant-model mismatch show its promising performance.
doi:10.1016/j.compchemeng.2016.03.019 fatcat:hzrdlkwgkfhzfclqsvu2zyssnm

Formation of Tankyrase Inhibitor-Induced Degradasomes Requires Proteasome Activity

Nina Marie Pedersen, Tor Espen Thorvaldsen, Sebastian Wolfgang Schultz, Eva Maria Wenzel, Harald Stenmark, David Wai Chan
2016 PLoS ONE  
In canonical Wnt signaling, the protein levels of the key signaling mediator β-catenin are under tight regulation by the multimeric destruction complex that mediates proteasomal degradation of β-catenin. In colorectal cancer, destruction complex activity is often compromised due to mutations in the multifunctional scaffolding protein Adenomatous Polyposis Coli (APC), leading to a stabilization of β-catenin. Recently, tankyrase inhibitors (TNKSi), a novel class of small molecule inhibitors, were
more » ... shown to re-establish a functional destruction complex in APC-mutant cancer cell lines by stabilizing AXIN1/2, whose protein levels are usually kept low via poly(ADP-ribosyl)ation by the tankyrase enzymes (TNKS1/2). Surprisingly, we found that for the formation of the morphological correlates of destruction complexes, called degradasomes, functional proteasomes are required. In addition we found that AXIN2 is strongly upregulated after 6 h of TNKS inhibition. The proteasome inhibitor MG132 counteracted TNKSi-induced degradasome formation and AXIN2 stabilization, and this was accompanied by reduced transcription of AXIN2. Mechanistically we could implicate the transcription factor FoxM1 in this process, which was recently shown to be a transcriptional activator of AXIN2. We observed a substantial reduction in TNKSi-induced stabilization of AXIN2 after siRNA-mediated depletion of FoxM1 and found that proteasome inhibition reduced the active (phosphorylated) fraction of FoxM1. This can explain the decreased protein levels of AXIN2 after MG132 treatment. Our findings have implications for the design of in vitro studies on the destruction complex and for clinical applications of TNKSi.
doi:10.1371/journal.pone.0160507 pmid:27482906 pmcid:PMC4970726 fatcat:hbvzv5zarjfzflcss4wbg5xccy

Sirolimus-Induced Vascular Dysfunction

Alexander Jabs, Sebastian Göbel, Philip Wenzel, Andrei L. Kleschyov, Marcus Hortmann, Matthias Oelze, Andreas Daiber, Thomas Münzel
2008 Journal of the American College of Cardiology  
This article contains results that are part of the thesis work of Sebastian Göbel.  ... 
doi:10.1016/j.jacc.2008.01.058 pmid:18510959 fatcat:farwinaqkrcdvizlm3wjbg6tsu

REPRODUCIBLE FUNCTIONAL CONNECTIVITY ENDOPHENOTYPE CONFERS HIGH AUTISM RISK IN SUBSET OF INDIVIDUALS

Sebastian Georg Wenzel Urchs, Hien Duy Nguyen, Clara Moreau, Christian Dansereau, Angela Tam, Alan Evans, Pierre Bellec
2020 Zenodo  
Functional connectivity (FC) analyses of individuals with autism spectrum disorder (ASD) have established robust alterations at the group level. Yet, the translation of these imaging findings into robust markers of individual risk is hampered by the extensive heterogeneity among ASD individuals. Here, we report an FC endophenotype that confers a greater than 7-fold risk increase of ASD diagnosis in the general population. By focusing on a subset of individuals with highly predictive FC
more » ... ns, we achieved a greater than 3-fold increase in risk over previous predictive models. The FC risk endophenotype was characterized by underconnectivity of transmodal brain networks and generalized to independent data. Our results demonstrate the ability of a highly targeted prediction model to meaningfully decompose part of the heterogeneity of the autism spectrum. The identified FC signature may help better delineate the multitude of etiological pathways and behavioural symptoms that challenge our understanding of the autism spectrum.
doi:10.5281/zenodo.3909636 fatcat:fvtwwp5eujf7tiobsxi46qhkp4

Protein Crowding mediates Passive Membrane Remodeling in ESCRT-induced Formation of Intraluminal Vesicles [article]

Susanne Liese, Eva Maria Wenzel, Rossana Virginia Rojas Molina, Sebastian Wolfgang Schultz, Harald Stenmark, Camilla Raiborg, Andreas Carlson
2019 bioRxiv   pre-print
As part of the lyosomal degradation pathway, the endosomal sorting complex required for transport (ESCRT) machinery sequester receptors at the endosome and simultaneously deform the membrane to generate intraluminal vesicles (ILVs). The role ESCRTs play in the membrane shape remodeling is not understood. We present a mathematical model, where ESCRT-induced alteration of the Gaussian bending rigidity and their crowding on the membrane facilitate ILV formation. The combination of mathematical
more » ... ling and experimental measurements shows that early ESCRT-driven budding does not require ATP consumption as only a small energy barrier needs to be overcome. Our model predicts that an ESCRT-free ILV forms, i.e., ESCRTs do not become part of the vesicle, but localize with a high density at the membrane neck, where the steep decline in the Gaussian curvature might trigger ESCRT-III/Vps4 assembly to enable neck constriction and scission.
doi:10.1101/834457 fatcat:qbojnf7ve5gqzp5tskb46ezujm

Quantification of tremor severity with a mobile tremor pen

Tibor Zajki-Zechmeister, Mariella Kögl, Kerstin Kalsberger, Sebastian Franthal, Nina Homayoon, Petra Katschnig-Winter, Karoline Wenzel, László Zajki-Zechmeister, Petra Schwingenschuh
2020 Heliyon  
Mariella K€ ogl, Kerstin Kalsberger, Sebastian Franthal, Nina Homayoon, Petra Katschnig-Winter, Karoline Wenzel: Conceived and designed the experiments; Performed the experiments; Wrote the paper.  ...  Mariella K€ ogl, Kerstin Kalsberger, Sebastian Franthal, Nina Homayoon, Petra Katschnig-Winter, Karoline Wenzel and Petra Schwingenschuh (principal investigator) work on a regular basis at the Medical  ... 
doi:10.1016/j.heliyon.2020.e04702 pmid:32904326 pmcid:PMC7452531 fatcat:wb6u3s3o7re7hcwxm4xmwbw5pu

Optimization of MOVPE growth for 650nm-emitting VCSELs

A Bhattacharya, M Zorn, A Oster, M Nasarek, H Wenzel, J Sebastian, M Weyers, G Tränkle
2000 Journal of Crystal Growth  
This paper reports on the optimization of the growth of visible-wavelength vertical-cavity surface-emitting laser (VCSEL) diodes by metalorganic vapour-phase epitaxy (MOVPE). The VCSEL structure has an GaInP/AlGaInP quantum well active zone (AZ) sandwiched between AlGaAs/AlAs distributed Bragg re#ectors (DBRs). We present results on the optimization of the DBR re#ectivity and the electrical resistance of the p-DBR and discuss the switching sequence at the AZ to p-DBR interface which is critical
more » ... due to the change of the group V component. Using these optimized parameters 640}655 nm emitting VCSELs could be demonstrated, with a minimum threshold current density of 2.8 kA/cm at 654 nm. (A. Bhattacharya), zorn@fbh-berlin.de (M. Zorn). 0022-0248/00/$ -see front matter 2000 Elsevier Science B.V. All rights reserved. PII: S 0 0 2 2 -0 2 4 8 ( 0 0 ) 0 0 7 9 6 -X
doi:10.1016/s0022-0248(00)00796-x fatcat:2fl5ktt265dfnm26mpq4yrj57u

Bayesian Neural Network Priors Revisited [article]

Vincent Fortuin, Adrià Garriga-Alonso, Sebastian W. Ober, Florian Wenzel, Gunnar Rätsch, Richard E. Turner, Mark van der Wilk, Laurence Aitchison
2022 arXiv   pre-print
Anqi Wu, Sebastian Nowozin, Edward Meeds, Richard E Turner, José Miguel Hernández-Lobato, and Alexander L Gaunt.  ...  ., Heek & Kalchbrenner, 2019; Wenzel et al., 2020a) . Surprisingly, these issues can largely be fixed by artificially reducing posterior uncertainty using "cold posteriors" (Wenzel et al., 2020a) .  ... 
arXiv:2102.06571v3 fatcat:w47k7msg4rardptftchevuymrq

Room-temperature sodium-ion batteries: Improving the rate capability of carbon anode materials by templating strategies

Sebastian Wenzel, Takeshi Hara, Jürgen Janek, Philipp Adelhelm
2011 Energy & Environmental Science  
Current kinetic limitations of carbon anode materials in sodium-ion batteries can be effectively tackled by using tailor-made carbon materials with hierarchical porosity prepared via the nanocasting route. Capacities exceeding 100 mA h g À1 at C/5 are found while exhibiting excellent rate capability and reasonable cycle life. The development of rechargeable batteries as energy storage devices is a key issue for many future applications. Lithium is the key element utilized, but its abundance and
more » ... geographical distribution are a matter of controversial debate. Sodium based batteries could be an attractive alternative, and the high temperature sodium/sulfur battery operating between 310 and 350 C has been already commercialized for stationary applications. 1,2 Also all solid-state concepts operating at elevated temperatures using polymer electrolytes have been proposed. 3,4 To date, however, no suitable (combinations of) electrode materials exist that allow satisfying performance at room temperature exists, even though the chemistry of a Na-ion battery could be very similar to its Li-ion battery counterpart. Recently, several studies on possible cathode materials have been published, 5-9 but much less has been reported on potential anode materials. 3342
doi:10.1039/c1ee01744f fatcat:z5vouzxenzaffa4klcuxdhgosu

Organic Matter Composition and Phosphorus Speciation of Solid Waste from an African Catfish Recirculating Aquaculture System

Julia Prüter, Sebastian Marcus Strauch, Lisa Carolina Wenzel, Wantana Klysubun, Harry Wilhelm Palm, Peter Leinweber
2020 Agriculture  
Recycling of phosphorus (P) from feed input in aquaculture systems gains increasing importance, especially relating to sustainable agriculture and food production. In order to find possible areas of application of African catfish solid waste, the purpose of this study was to characterize the elemental and organic matter composition and P speciation in the aquaculture fish waste. Pyrolysis-field ionization mass spectrometry (Py-FIMS) was used to investigate the composition of organic matter and
more » ... K-edge X-ray absorption near edge structure (XANES) spectroscopy to describe the occurring P-containing compounds in African catfish solid waste from an intensive recirculation aquaculture system (RAS). The solid fish waste was mainly composed of sterols, free fatty acids and alkylaromatics, as it is common for digestive systems of animals. Ingredients such as the phytosterol beta-sitosterin confirm plant-based feed ingredients and some recalcitrance against digestion in the African catfish gut. The P in the solid fish waste was exclusively bound as calcium-phosphates. These calcium-phosphate minerals as major constituents of African catfish waste may have beneficial effects when applied to soils, suggesting the use of this waste as possible soil amendment in the future.
doi:10.3390/agriculture10100466 fatcat:m3modv3gb5aazhv5xfkdml35pm

Nigral iron deposition in common tremor disorders

Nina Homayoon, Lukas Pirpamer, Sebastian Franthal, Petra Katschnig‐Winter, Mariella Kögl, Stephan Seiler, Karoline Wenzel, Edith Hofer, Hannes Deutschmann, Franz Fazekas, Christian Langkammer, Stefan Ropele (+2 others)
2018 Movement Disorders  
We investigated R2* relaxation rates as a marker of iron content in the substantia nigra in patients with common tremor disorders and explored their diagnostic properties.
doi:10.1002/mds.27549 pmid:30536988 pmcid:PMC6590652 fatcat:aj64owiflnft5ghxtvtd7vttwu

Molecular Determinants of the Interaction betweenClostridium perfringensEnterotoxin Fragments and Claudin-3

Lars Winkler, Claudia Gehring, Ariane Wenzel, Sebastian L. Müller, Christian Piehl, Gerd Krause, Ingolf E. Blasig, Jörg Piontek
2009 Journal of Biological Chemistry  
Clostridium perfringens enterotoxin (CPE) binds to the extracellular loop 2 of a subset of claudins, e.g. claudin-3. Here, the molecular mechanism of the CPE-claudin interaction was analyzed. Using peptide arrays, recombinant CPE-(116 -319) bound to loop 2 peptides of mouse claudin-3, -6, -7, -9, and -14 but not of 1, 2, 4, 5, 8, 10 -13, 15, 16, 18 -20, and 22. Substitution peptide mapping identified the central motif 148 NPL 150 VP, supposed to represent a turn region in the loop 2, as
more » ... l for the interaction between CPE and murine claudin-3 peptides. CPEbinding assays with claudin-3 mutant-transfected HEK293 cells or lysates thereof demonstrated the involvement of Asn 148 and Leu 150 of full-length claudin-3 in the binding. CPE-(116 -319) and CPE-(194 -319) bound to HEK293 cells expressing claudin-3, whereas CPE-(116 -319) bound to claudin-5-expressing HEK293 cells, also. This binding was inhibited by substitutions T151A and Q156E in claudin-5. In contrast, removal of the aromatic side chains in the loop 2 of claudin-3 and -5, involved in trans-interaction between claudins, increased the amount of CPE-(116 -319) bound. These findings and molecular modeling indicate different molecular mechanisms of claudin-claudin trans-interaction and claudin-CPE interaction. Confocal microscopy showed that CPE-(116 -319) and CPE-(194 -319) bind to claudin-3 at the plasma membrane, outside cell-cell contacts. Together, these findings demonstrate that CPE binds to the hydrophobic turn and flanking polar residues in the loop 2 of claudin-3 outside tight junctions. The data can be used for the specific design of CPE-based modulators of tight junctions, to improve drug delivery, and as chemotherapeutics for tumors overexpressing claudins. The clinical use of many promising drug candidates is impeded by unacceptable pharmacokinetics (1). The ability of a drug to pass through tissue barriers is a major determinant for its delivery. In epithelia and endothelia, the paracellular route is blocked by tight junctions (TJ). 4 Different approaches have □ S The on-line version of this article (available at http://www.jbc.org) contains supplemental Figs. S1 and S2.
doi:10.1074/jbc.m109.008623 pmid:19429681 pmcid:PMC2707212 fatcat:kkjgww7gajelxd65ais7ygcoji
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