434 research outputs found
Attribute-based Access Control on Solid Pods using Privacy-friendly Credentials
Our demo showcases how a user is granted access to resources stored on a Solid Pod, i. e., a web server that adheres to the Solid Protocol, using Web-based Verifiable Credentials. To protect the privacy of the user, we rely on the BBS+ signatures scheme allowing for selective disclosure of only those attributes necessary. We present a PWA where a user can (a) request a Verifiable Credential from another user, (b) store it on their own Solid Pod, and (c) use it to gain access to a resource on a third userâs Solid Pod
Quantifiable integrity for Linked Data on the web
We present an approach to publish Linked Data on the Web with quantifiable integrity using Web technologies, and in which rational agents are incentivised to contribute to the integrity of the link network. To this end, we introduce self-verifying resource representations, that include Linked Data Signatures whose signature value is used as a suffix in the resourceâs URI. Links among such representations, typically managed as web documents, contribute therefore to preserving the integrity of the resulting document graphs. To quantify how well a documentâs integrity can be relied on, we introduce the notion of trust scores and present an interpretation based on hubs and authorities. In addition, we present how specific agent behaviour may be induced by the choice of trust score regarding their optimisation, e.g., in general but also using a heuristic strategy called Additional Reach Strategy (ARS). We discuss our approach in a three-fold evaluation: First, we evaluate the effect of different graph metrics as trust scores on induced agent behaviour and resulting evolution of the document graph. We show that trust scores based on hubs and authorities induce agent behaviour that contributes to integrity preservation in the document graph. Next, we evaluate different heuristics for agents to optimise trust scores when general optimisation strategies are not applicable. We show that ARS outperforms other potential optimisation strategies. Last, we evaluate the whole approach by examining the resilience of integrity preservation in a document graph when resources are deleted. To this end, we propose a simulation system based on the WattsâStrogatz model for simulating a social network. We show that our approach produces a document graph that can recover from such attacks or failures in the document graph
A SoLiD app to participate in a scalable semantic supply chain network on the blockchain (Demo)
To allow for inter-organisational processes in networks withlow trust, Supply Chains and corresponding information are moving tothe blockchain. On the blockchain, this information poses a scalabilitychallenge. To tackle this challenge, we propose a solution that minimisesthe data stored on the blockchain, which we base on semantic datamodelling in knowledge graphs, decentralised management of interlinkeddata, and a light-weight Smart Contract. In this demo, we focus onthe web agent to participate in Supply Chain networks built using ourapproach, and our corresponding data modellin
Influence of steps on the tilting and adsorption dynamics of ordered Pn films on vicinal Ag(111) surfaces
Here we present a structural study of pentacene (Pn) thin films on vicinal
Ag(111) surfaces by He atom diffraction measurements and density functional
theory (DFT) calculations supplemented with van der Waals (vdW) interactions.
Our He atom diffraction results suggest initial adsorption at the step edges
evidenced by initial slow specular reflection intensity decay rate as a
function of Pn deposition time. In parallel with the experimental findings, our
DFT+vdW calculations predict the step edges as the most stable adsorption site
on the surface. An isolated molecule adsorbs as tilted on the step edge with a
binding energy of 1.4 eV. In addition, a complete monolayer (ML) with
pentacenes flat on the terraces and tilted only at the step edges is found to
be more stable than one with all lying flat or tilted molecules, which in turn
influences multilayers. Hence our results suggest that step edges can trap Pn
molecules and act as nucleation sites for the growth of ordered thin films with
a crystal structure similar to that of bulk Pn.Comment: 4 pages, 4 figures, 1 tabl
Bilateral proximal tibia fracture
A bilateral fracture of the proximal tibia is rare in children. We describe a girl with a bilateral fracture just distal of the epiphyseal plate after minimal trauma
Chronic y-secretase inhibition reduces amyloid plaque-associated instability of pre- and postsynaptic structures
The loss of synapses is a strong histological correlate of the cognitive decline in Alzheimerâs disease (AD). Amyloid bpeptide (Ab), a cleavage product of the amyloid precursor protein (APP), exerts detrimental effects on synapses, a process thought to be causally related to the cognitive deficits in AD. Here, we used in vivo two-photon microscopy to characterize the dynamics of axonal boutons and dendritic spines in APP/Presenilin 1 (APPswe/PS1L166P)âgreen fluorescent protein (GFP) transgenic mice. Time-lapse imaging over 4 weeks revealed a pronounced, concerted instability of pre- and postsynaptic structures within the vicinity of amyloid plaques. Treatment with a novel sulfonamide-type g-secretase inhibitor (GSI) attenuated the formation and growth of new plaques and, most importantly, led to a normalization of the enhanced dynamics of synaptic structures close to plaques. GSI treatment did neither affect spines and boutons distant from plaques in amyloid precursor protein/presenilin 1-GFP (APPPS1-GFP) nor those in GFP-control mice, suggesting no obvious neuropathological side effects of the drug
Synthetic simulations of the extragalactic sky seen by eROSITA I. Pre-launch selection functions from Monte-Carlo simulations
Context. Studies of galaxy clusters provide stringent constraints on models of structure formation. Provided that selection effects are under control, large X-ray surveys are well suited to derive cosmological parameters, in particular those governing the dark energy equation of state. Aims. We forecast the capabilities of the all-sky eROSITA (extended ROentgen Survey with an Imaging Telescope Array) survey to be achieved by the early 2020s. We bring special attention to modelling the entire chain from photon emission to source detection and cataloguing. Methods. The selection function of galaxy clusters for the upcoming eROSITA mission is investigated by means of extensive and dedicated Monte-Carlo simulations. Employing a combination of accurate instrument characterisation and a state-of-the-art source detection technique, we determine a cluster detection efficiency based on the cluster fluxes and sizes. Results. Using this eROSITA cluster selection function, we find that eROSITA will detect a total of approximately 10(5) clusters in the extra-galactic sky. This number of clusters will allow eROSITA to put stringent constraints on cosmological models. We show that incomplete assumptions on selection effects, such as neglecting the distribution of cluster sizes, induce a bias in the derived value of cosmological parameters. Conclusions. Synthetic simulations of the eROSITA sky capture the essential characteristics impacting the next-generation galaxy cluster surveys and they highlight parameters requiring tight monitoring in order to avoid biases in cosmological analyses.Peer reviewe
A Fly in the Ointment: Evaluation of Traditional Use of Plants to Repel and Kill Blowfly Larvae in Fermented Fish
Introduction: In rural areas in Laos, fly larvae infestations are common in fermenting fish. Blowflies (Chrysomyamegacephala, Diptera: Calliphoridae) are attracted to oviposit (and/or larviposit) onto fermenting fish which results ininfestations with fly larvae. Knowledge of traditional use of plants to repel larvae during the production of fermented fish iscommon and widespread in Lao PDR. Research Questions: How effective are the most salient species in repelling, and killing fly larvae in fermenting fish? Material and Methods: The three plant species most frequently reported to repel fly larvae during an ethnobotanical surveythroughout Lao PDR were tested for repellence and larvicidal activity of fly larvae infesting fermented fish. The lethality andrepellence of Tadehagi triquetrum (L.) H. Ohashi (Fabaceae), Uraria crinita (L.) Desv. ex DC. (Fabaceae) and Bambusa multiplex(Lour.) Raeusch. ex Schult. & Schult. f. (Poaceae) were tested in an experimental design using fermenting fish in Vientiane,Lao PDR. Results: The repellent effect of fresh material of T. triquetrum and U. crinita, and the larvicidal effect of fresh B. multiplex, issignificantly more effective than that of dried material of the same species, and the total effect (repellence and larvicidaleffect combined) for each of the three species was significantly more effective for fresh than for dry material. Fresh materialof T. triquetrum, U. crinita, or B. multiplex added on top of the fermenting fish repelled 50%, 54%, 37%, and killed 22%, 28%,and 40% of fly larvae. The total effect was not significantly different per species at 72%, 82%, and 77%, respectively. Discussion and Conclusions: The three most salient species are effective in repelling and killing fly larvae in the productionof fermented fish, and may be essential to augment food safety during traditional fermentation in open jars
Measurement of W Polarisation at LEP
The three different helicity states of W bosons produced in the reaction e+
e- -> W+ W- -> l nu q q~ at LEP are studied using leptonic and hadronic W
decays. Data at centre-of-mass energies \sqrt s = 183-209 GeV are used to
measure the polarisation of W bosons, and its dependence on the W boson
production angle. The fraction of longitudinally polarised W bosons is measured
to be 0.218 \pm 0.027 \pm 0.016 where the first uncertainty is statistical and
the second systematic, in agreement with the Standard Model expectation
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