1,335 research outputs found
Optimal order finite difference approximation of generalized solutions to the biharmonic equation in a cube
We prove an optimal order error bound in the discrete norm for
finite difference approximations of the first boundary-value problem for the
biharmonic equation in space dimensions, with , whose
generalized solution belongs to the Sobolev space , for , where . The result extends the range of the Sobolev index in the best
convergence results currently available in the literature to the maximal range
admitted by the Sobolev embedding of into in
space dimensions
Hard exclusive photoproduction of charmed mesons
{We investigate the photoproduction process within the handbag approach, which we assume
to be the dominant mechanism at energies well above the production threshold
and in the forward scattering hemisphere.Comment: proceedings of Photon 2013, May 20-24 2013, Paris, Franc
Confirmation Bias in Information Search with Social Tags
Confirmation bias is the tendency of information searchers to select and evaluate information that supports pre-existing attitudes favourably. The current dissertation investigates whether confirmation bias affects health-related search in online environments, where users share content and social tag clouds are the navigation interface for searchers. I assumed that when individuals search health-related issues, they are motivated to find accurate information (accuracy motivation), in contrast to defending their self-concept (defense motivation). To determine what information is accurate, I expect that searchers attend to internal, individual evaluations (prior knowledge, prior attitudes, and attitude confidence), and external, collective cues (tag popularity and source credibility).
Regarding the influence of individual evaluations, in studies 2 and 3, a linear influence of prior attitudes on the selection of blog posts (but not tags), and the evaluation of blog posts was found. In studies 2 and 3, I tested whether the influence of prior attitudes was moderated by confidence. I found that high confidence did affect the selection of blog posts but not tags in both studies, and confidence influenced the evaluation of tag-related blog posts.
Regarding the influence of the collective cues, tag popularity was manipulated in studies 1 and 3, where I found a main effect of tag popularity on the selection of tags, blog posts, and evaluation of content, showing that tag size influenced confirmation bias in a moderate to strong way. In the student sample (study 2), I found that high credibility reduced the influence of prior attitudes on the selection of tags and consequently blog posts. However, using a representative sample (study 3), no influence of source credibility was found. With respect to the searchersâ evaluation of content, credibility had no influence in study 2, but in study 3, under high source credibility and low attitude confidence, searchers evaluated content more favourably when content was attitude consistent.
In conclusion, the present dissertation shows that confirmation bias and individual evaluations guide information searchers in tag-based navigation, extending the literature which showed behaviour in social tagging environments follows semantic associations. The results are interesting for the construction of content aggregation or social tagging platforms, and practitioners who provide health-related online content. Practitioners and platform providers pay attention to their target audience, as this will either elicit accuracy or defense motivation. So, different strategies can be implemented when the aim is to reduce the influence of confirmation bias on information search behaviour.Der BestĂ€tigungsfehler ist die Tendenz Informationen so auszuwĂ€hlen und zu bewerten, dass bestehende Einstellungen verstĂ€rkt werden. In dieser Dissertation untersuche ich, ob der BestĂ€tigungsfehler auch in Online-Umgebungen auftritt, wo Nutzer auf geteilte Inhalte ĂŒber Social Tag Clouds zugreifen. Personen sollten bei der gesundheitsbezogenen Suche nicht dazu tendieren, dass sie ihr Selbstkonzept aufrechterhalten (Verteidigungsmotiv), sondern sie sollten Inhalte gemÀà ihrer Korrektheit auswĂ€hlen (Genauigkeitsmotiv). Um die Korrektheit der Inhalte einzuschĂ€tzen berĂŒcksichtigen Nutzer internale, individuelle Bewertungen (Vorwissen, Voreinstellungen, Einstellungsgewissheit), sowie externale, kollektive Reize (Tag PopularitĂ€t, GlaubwĂŒrdigkeit). Dies ist eine bedeutsame Erweiterung zur Literatur Sozialer Tagging Systeme, die bisher ausschlieĂlich den Einfluss semantischer Assoziationen im menschlichen GedĂ€chtnis und den Einfluss aggregierter, kollektiver Assoziationen untersucht.
In den Studien 2 und 3 zeigte sich ein linearer Einfluss von Voreinstellungen auf die Auswahl und Bewertung von BlogeintrĂ€gen. Hier testete ich auch, ob der Einfluss der Voreinstellungen durch Einstellungsgewissheit moderiert wĂŒrde. Einstellungsgewissheit beeinflusste die Auswahl von BlogeintrĂ€gen und deren Bewertung.
In den Studien 1 und 3 zeigte sich ein Effekt der Tag-PopularitĂ€t auf die Auswahl von Tags, BlogeintrĂ€gen und die Bewertung von Inhalten. AuĂerdem zeigte sich in der Studierendenstichprobe (Studie 2), dass hohe GlaubwĂŒrdigkeit den Einfluss von Einstellungen auf die Navigation reduzierte. In Studie 3, mit einer reprĂ€sentativen Stichprobe, wurde dies jedoch nicht gefunden. In Bezug auf die Bewertung von Inhalten hatte die GlaubwĂŒrdigkeit keinen Einfluss in Studie 2, aber in Studie 3 bewertete die reprĂ€sentative Stichprobe von Suchenden bei hoher GlaubwĂŒrdigkeit und gleichzeitig geringer Einstellungsgewissheit Inhalte gĂŒnstiger, wenn sie einstellungs-kongruent waren.
Somit zeigte sich, dass Informationssuchende in der Tag-basierten Navigation dem BestĂ€tigungsfehler unterliegen. Dies ist eine bedeutende Erweiterung zur Literatur, die gezeigt hat, dass Informationssuche und Bewertung in Social-Tagging-Umgebungen semantischen Assoziationen folgen. Die vorliegenden Ergebnisse zeigen interessante Implikationen fĂŒr die Gestaltung von Social-Tagging Plattformen. So ist es beispielsweise wichtig, die Zielgruppe zu berĂŒcksichtigen, da sie bestimmt, ob Suchende im gesundheitsbezogenen Kontext durch Genauigkeits- oder Verteidigungsmotive geleitet sind
Medial vermittelte Narrationen ĂŒber die Energiewende in energieintensiven Unternehmen
In dem Beitrag wird das in weiten Teilen konfliktĂ€re VerhĂ€ltnis energieintensiver Unternehmen der Stahl- und Chemiebranche zur deutschen Energiewende â insbesondere mit Blick auf die EEG-Umlage und deren Ausnahmeregelungen â analysiert. Ausgangslage des Forschungsinteresses war das im öffentlich-medialen Diskurs prĂ€sente SpannungsverhĂ€ltnis ökonomischer Partikularinteressen (der deutschen Industrie) und ökologischer Zielvorgaben zur CO2-Reduktion. Ziel war es, dieses SpannungsverhĂ€ltnis im Zuge einer Medienanalyse im Zeitraum vom 01.07.2013 bis 30.06.2016 nĂ€her und mit Blick auf abzuleitende idealtypische Narrationen zu bestimmen. Es wurden sieben idealtypische Narrationen herausgearbeitet, welche das VerhĂ€ltnis der energieintensiven Stahl- und Chemiebranche zur Energiewende und ihren gesetzlichen Rahmenbedingungen beschreibt. Diese Narrationen reichen von der ErzĂ€hlung der deutschen Industrie als Held und Opfer ĂŒber die ErzĂ€hlung vom Kulturopfer bis hin zur ErzĂ€hlung von der Harmonisierung von Ăkologie und Ăkonomie.
The article analyses the conflicting relationship between energy-intensive companies in the steel and chemical industry and the German energy transition, especially in reference to the EEG reallocation charge and its special equalization scheme. Our research interest is based on the public media discourse on the tense relationship between economic interests (of German industry) and ecological targets for CO2-reduction. The goal was to determine this relationship through a media analysis in the period from 01.07.2013 to 30.06.2016 to derive ideal-typical narratives. In the end seven ideal-typical narratives were identified. These narratives range from the story of German industry as a hero and victim to the story of the sacrifice of culture up to the story of the harmonisation of ecology and economy.
(peer reviewed
ProGIRH-DLR: Remote sensing of water quality in the Mantaro River basin through spaceborne and ground-based acquisition of multi- and hyperspectral data
Peru is amongst the most affected countries by climate change in the world, with severe consequences on the availability of water across the country. The GIZ funded project "Multisectoral management of water resources in the Mantaro River basin" (ProGIRH) aims to improve the integrated and climate-sensitive water resource management in the Mantaro River basin. Within this framework, an IMF Team supports the Peruvian national water authority (ANA) in establishing remote sensing methodologies as a complement to traditional sampling-based water analysis. With a permanent focus on capacity building of the regional partners, the Team combines multi- and hyperspectral satellite imagery with in-situ spectral data, in order to define the possibilities and technical requirements necessary to establish a self-dependent and locally managed long-term observation of water quality and availability
A matrix-free algorithm for multiple wavelength fluorescence tomography
In the recent years, there has been an increase in applications of non-contact diffusion optical tomography. Especially when the objective is the recovery of fluorescence targets. The non-contact acquisition systems with the use of a CCD-camera produce much denser sampled boundary data sets than fibre-based systems. When model-based reconstruction methods are used, that rely on the inversion of a derivative operator, the large number of measurements poses a challenge since the explicit formulation and storage of the Jacobian matrix could be in general not feasible. This problem is aggravated further in applications, where measurements at multiple wavelengths are used. We present a matrix-free model-based reconstruction method, that addresses the problems of large data sets and reduces the computational cost and memory requirements for the reconstruction. The idea behind the matrix-free method is that information about the Jacobian matrix could be available through matrix times vector products so that the creation and storage of big matrices can be avoided. We tested the method for multiple wavelength fluorescence tomography with simulated and experimental data from phantom experiments, and we found substantial benefits in computational times and memory requirements. (C) 2009 Optical Society of Americ
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