248 research outputs found
Phase diagram of turbulent Taylor-Couette flow
No full textWe will present the results of our recent numerical work on the nature of the phase diagram of turbulent Taylor-Couette (TC) flow, both with co- and counterrotating cylinder. The work can be seen as the extension of the famous experimental Andereck et al. phase diagram for Taylor-Couette flow just above the onset of instabilities, towards the ultimate turbulence regime, and now obtained numerically. In particular, we will understand when and why optimal transport of angular velocity from the inner to the outer cylinder is achieved and how this is connected to the angular velocity profile and the structures in the flow
Double diffusive convection between two parallel plates with different boundary conditions
No full textWe investigate the double diffusive convection between two parallel plates with either no-slip or free-slip boundary conditions. Direct numerical simulations have been conducted systematically for a series of control parameters. Salt fingers can be observed for both boundary conditions and all parameters explored. Compared to the no-slip case, salt fingers are stronger in the free-slip case, which is accompanied by larger salinity flux and flow velocity. For both boundary conditions, thin boundary regions develop adjacent to two plates. The salinity flux and the Reynolds number show similar dependences on the control parameter, namely, the Rayleigh number of the salinity field
The scientific author
No full textThis presentation connects developments in the science studies with those in scientific discourse analysis. Science studies has undergone a veritable anthropological revolution and come to pay more attention to the concrete situations in which science is elaborated in the laboratory. The focus is now on the rhetoric mobilised to convince peers or potential funding bodies, and on genres that had been heretofore neglected such as letter writing, oral exchanges, notes, memos, reports and paper submissions. A parallel renewal of linguistic and rhetorical approaches is all the more necessary because of this empirical focus: how is the writing process – with its linguistic and iconic characteristics – informed by production conditions? How is it informed by cognitive, epistemological and social issues? However, the role of the scientific author must not be forgotten as it is central to understanding scientific positioning. To succeed in initiating much-needed interdisciplinary dialogue, we need to clarify the subjects at stake – authorship and scientific discourse –, as well as their connection to linguistic and semiotic forms.On se propose ici de mettre en relation les évolutions des études de la science avec celles de l’analyse des discours scientifiques. Une véritable révolution anthropologique a conduit les Science Studies à porter plus d’attention aux conditions concrètes dans lesquelles se fabrique la science au sein du laboratoire. Les chercheurs se sont davantage intéressés aux rhétoriques mobilisées pour convaincre les pairs ou les éventuels financeurs, et ont pris en compte des genres de discours parfois peu étudiés : échanges épistolaires ou oraux, notes, mémos, rapports, propositions de communication. Cette attention au concret montre tout l’intérêt d’un renouvellement parallèle des approches linguistiques et rhétoriques, qui ont à mieux comprendre comment l’écriture scientifique – texte et image – est informée par la situation de production, mais aussi par les enjeux cognitifs, épistémologiques et sociaux d’une recherche. La question de l’auteur scientifique n’est pas pour autant évacuée : elle reste centrale pour mieux comprendre les jeux du positionnement scientifique. Si l’on veut initier efficacement le nécessaire dialogue pluridisciplinaire, des clarifications s’imposent, concernant les objets concernés – l’auctorialité et les discours scientifiques – dans leurs rapports avec les formes linguistiques ou sémiotiques.La problemática de esta presentación busca entrecruzar las evoluciones de los estudios de la ciencia con las evoluciones del análisis de discursos científicos. En efecto, una verdadera revolución antropológica ha llevado los estudios de ciencia a prestar más atención a las condiciones concretas en las cuales se fabrica la ciencia al interior del laboratorio. Nos interesamos igualmente de manera especial a las retoricas movilizadas para convencer a los colegas investigadores o a las personas que eventualmente financian la investigación y tomamos en cuenta géneros de discurso muchas veces poco estudiados: intercambios epistolares u orales, notas, memorandos, reportes, proposiciones de comunicación. La atención que se presta a estos objetos concretos muestra el gran interés que representa una renovación paralela de los análisis lingüísticos y retóricos, que permiten comprender como la realización del texto y, algunas veces, la realización de la imagen, se dan a conocer gracias a la situación de producción, y a los aportes cognitivos, epistemológicos y sociales de una investigación. La cuestión del autor científico no está sin embargo resuelta: esta cuestión sigue siendo central para comprender el rol de la position científica. Si se quiere maniobrar eficazmente el ineludible dialogo pluridisciplinario, algunas clarificaciones son necesarias, estas tienen que ver con los objetos implicados –la «autorialidad» y los discursos científicos – en sus relaciones con las formas lingüísticas o semiótica
Evidence of Cascaded Third-Harmonic Generation in Noncentrosymmetric Gold Nanoantennas
No full textThe optimization of nonlinear optical processes on the nanoscale is a crucial step for the integration of complex functionalities into compact photonic devices and metasurfaces. In such systems, photon upconversion can be achieved with higher efficiencies via third-order processes, such as third-harmonic generation (THG), thanks to the resonantly enhanced volume currents. Conversely, second-order processes, such as second-harmonic generation (SHG), are often inhibited by the symmetry of metal lattices and of common nanoantenna geometries. SHG and THG processes in plasmonic nanostructures are generally treated independently because they typically represent small perturbations in the light-matter interaction mechanisms. In this work, we demonstrate that this paradigm does not hold for plasmon-enhanced nonlinear optics by providing evidence of a sum-frequency generation (SFG) process seeded by SHG, which sizably contributes to the overall THG yield. We address this mechanism by unveiling a characteristic fingerprint in the polarization state of the THG emission from gold noncentrosymmetric nanoantennas, which directly reflects the asymmetric distribution of second-harmonic fields within the structure and does not depend on the model one employs to describe photon upconversion. We suggest that such cascaded processes may also appear for structures that exhibit only moderate SHG yields. The presence of this peculiar mechanism in THG from plasmonic nanoantennas at telecommunication wavelengths allows us to gain further insight into the physics of plasmon-enhanced nonlinear optical processes. This could be crucial in the realization of nanoscale elements for photon conversion and manipulation operating at room temperature
The Fourth Way
No full textReinhardt Grossmann holds that a realistic ontology in regard to perceptual, physical, and mathematical objects can be combined with an empiricistic theory of knowledge. In the first part of the book he shows that the traditional distinction between primary and secondary qualities leads to idealism, while the common Cartesian conception of knowledge by way of ideas leads to skepticism. In an effort to avoid these twin scourges of modem philosophy, the author argues for the existence of ordinary perceptual objects and explains how we know these objects directly through simple acts of perception. The second part of the book is concerned with the way in which we know what is in our minds. Grossmann maintains that this kind of knowledge is just as fallible as perception. In the third part the author concludes that logic, arithmetic, and set theory concern matters of fact and that we discover these facts through empirical knowledge
Figures de l’auteur en didactique
No full textLes contributions réunies dans ce numéro traitent sous des angles très différents, les questions fondamentales qui visent à dessiner la figure complexe de l’auteur en didactique. The contributions gathered in this issue address, from varying points of view, the fundamental questions that aim to outline the complex figure of the author in didactics
Comparison of Currents derived from X-band Radar and collected In-situ Data in Ameland Inlet
No full textVelocities derived from X-band radar were compared to depth averaged ADCP measurements in a complex tidal inlet system at Ameland, the Netherlands. Inclusion of depth assimilation and ensemble averaging in radar calculations led to smaller differences between ADCP and radar. The observed differences were clustered and related to water level elevations, wind velocities, wave periods, wave heights, spatial coherence in radar output and error metrics of the radar fitting procedure. Larger waves and higher wind velocities were observed to benefit radar agreement with ADCP results. Rising water levels benefitted agreement in east west direction. Falling water levels benefitted agreement in north south direction. Confidence intervals of the fitting procedure were observed to coincide with differences between ADCP and radar and potential for filtering based on them was shown. Nevertheless, an unclarified tendency towards northwestern bias, which may be specific to the comparison locations, remains. The radar at Ameland monitors the whole inlet system and provides current velocities everywhere in its range. This study shows that its currents are in good agreement with ADCP depth averaged currents throughout most of the tidal cycle. Furthermore, it stresses radar’s potential for better monitoring of the coast and for cost effective coastal field measurements to obtain large datasets, even in hydrodynamically very complex regions.SEAWAD: research into a sand engine for the Wadden IslandsKustGenese 2.0Coastal and Marine Engineering and Management (CoMEM
Collision risk assessment in coastal waters
No full textThe amount of international shipped cargo grows steadily, and seas are exploited for seabed mining and energy production more than ever. As a result, there is an increase in traffic density and decrease in free navigational space, potentially causing a higher incidence of dangerous navigation situations that may lead to ship collisions. This thesis establishes a hypothesis that there are coastal areas where the risk of collision is unexplored and abnormally high and has not been analysed yet. Therefore, the thesis aims to develop a method suitable to assess the risk of collision in coastal waters. A thesis literature review primarily focuses on the current collision risk assessment methods, circumstances of collisions, and sources of navigational information for coastal waters. The literature review concludes that a promising and novel approach is to detect near-collision situations based on the data from the Automatic Identification System (AIS). The near-collision exists when a ship's safety domain is violated and, simultaneously, the ship performed a last-moment evasive manoeuvre, which is identified by an abnormal ship's rate of turn. Building on a previous basic version of the near-collision detection method and AIS data provided by Safetec Nordic AS, this thesis develops a collision risk assessing tool that significantly outperforms the original method. The performance of the designed method was evaluated using AIS data from the Vestfjorden area in Norwegian coast during 2013-2015. The case study shows that this approach effectively detects near-collision situations but identifies a considerable number of new false near-collisions. The details and spatial distribution of detected near-collisions provide valuable insight into navigational areas vulnerable to collisions, collision circumstances, and frequency of collisions
Datasets for a data-centric image classification benchmark for noisy and ambiguous label estimation
No full textThis is the official data repository of the Data-Centric Image Classification (DCIC) Benchmark.
The goal of this benchmark is to measure the impact of tuning the dataset instead of the model for a variety of image classification datasets.
Paper: https://arxiv.org/abs/2207.06214
Source Code: https://github.com/Emprime/dcic
## Citation
Please cite as
@article{schmarje2022benchmark,
author = {Schmarje, Lars and Grossmann, Vasco and Zelenka, Claudius and Dippel, Sabine and Kiko, Rainer and Oszust, Mariusz and Pastell, Matti and Stracke, Jenny and Valros, Anna and Volkmann, Nina and Koch, Reinahrd},
journal = {36th Conference on Neural Information Processing Systems (NeurIPS 2022) Track on Datasets and Benchmarks},
title = {{Is one annotation enough? A data-centric image classification benchmark for noisy and ambiguous label estimation}},
year = {2022}
}
Please see the full details about the used datasets below, which should also be cited as part of the license
Genetic alterations of the skin adnexal tumours
No full text1. CYLD gene 1.7 Summary Our team discovered 19 new germinal mutations (22% of all known), with author participating on finding of seven of them. Particularly interesting is the discovery of new intronic mutation of CYLD gene and characterization of molecular biologic processes causing inactivation of the gene. Author also confirmed presence of LOH being the most frequent second inactivating hit. At the same time author found a group of patients with BSS/MFT phenotype carrying no mutation of CYLD gene suggesting that there might exist another gene participating in BSS/MFT pathogenesis. Furthermore genotype-phenotype analysis was performed resulting in no significant correlation. 2. Mismatch repair genes hMLH1, hMSH2, hMSH6 2.9 Summary In this study we have analyzed one patient with Muir-Torre syndrome (MTS) phenotype for causal mutation in mismatch repair (MMR) genes. Most patients with MTS carry mutations in MSH2 and MLH1 gene. Germline mutations in MSH6 are extremely rare, with only 3 cases reported thus far. Here we have described a germline mutation in MSH6 gene in three members of one family. This greatly extends previously published group of patients with MTS syndrome carrying mutation in MSH6 gene. 3. PRKAR1A gene 3.7 Summary In this study we have investigated patient with Carney complex for a..
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