2,231 research outputs found
Event-by-event Simulation of Quantum Cryptography Protocols
We present a new approach to simulate quantum cryptography protocols using
event-based processes. The method is validated by simulating the BB84 protocol
and the Ekert protocol, both without and with the presence of an eavesdropper
Online Popularity and Topical Interests through the Lens of Instagram
Online socio-technical systems can be studied as proxy of the real world to
investigate human behavior and social interactions at scale. Here we focus on
Instagram, a media-sharing online platform whose popularity has been rising up
to gathering hundred millions users. Instagram exhibits a mixture of features
including social structure, social tagging and media sharing. The network of
social interactions among users models various dynamics including
follower/followee relations and users' communication by means of
posts/comments. Users can upload and tag media such as photos and pictures, and
they can "like" and comment each piece of information on the platform. In this
work we investigate three major aspects on our Instagram dataset: (i) the
structural characteristics of its network of heterogeneous interactions, to
unveil the emergence of self organization and topically-induced community
structure; (ii) the dynamics of content production and consumption, to
understand how global trends and popular users emerge; (iii) the behavior of
users labeling media with tags, to determine how they devote their attention
and to explore the variety of their topical interests. Our analysis provides
clues to understand human behavior dynamics on socio-technical systems,
specifically users and content popularity, the mechanisms of users'
interactions in online environments and how collective trends emerge from
individuals' topical interests.Comment: 11 pages, 11 figures, Proceedings of ACM Hypertext 201
Psycholinguistic norms for more than 300 lexical signs in German Sign Language (DGS)
Sign language offers a unique perspective on the human faculty of language by illustrating that linguistic abilities are not bound to speech and writing. In studies of spoken and written language processing, lexical variables such as, for example, age of acquisition have been found to play an important role, but such information is not as yet available for German Sign Language (Deutsche Gebärdensprache, DGS). Here, we present a set of norms for frequency, age of acquisition, and iconicity for more than 300 lexical DGS signs, derived from subjective ratings by 32 deaf signers. We also provide additional norms for iconicity and transparency for the same set of signs derived from ratings by 30 hearing non-signers. In addition to empirical norming data, the dataset includes machine-readable information about a sign’s correspondence in German and English, as well as annotations of lexico-semantic and phonological properties: one-handed vs. two-handed, place of articulation, most likely lexical class, animacy, verb type, (potential) homonymy, and potential dialectal variation. Finally, we include information about sign onset and offset for all stimulus clips from automated motion-tracking data. All norms, stimulus clips, data, as well as code used for analysis are made available through the Open Science Framework in the hope that they may prove to be useful to other researchers: https://osf.io/mz8j4
Roughness gradient induced spontaneous motion of droplets on hydrophobic surfaces: A lattice Boltzmann study
The effect of a step wise change in the pillar density on the dynamics of
droplets is investigated via three-dimensional lattice Boltzmann simulations.
For the same pillar density gradient but different pillar arrangements, both
motion over the gradient zone as well as complete arrest are observed. In the
moving case, the droplet velocity scales approximately linearly with the
texture gradient. A simple model is provided reproducing the observed linear
behavior. The model also predicts a linear dependence of droplet velocity on
surface tension. This prediction is clearly confirmed via our computer
simulations for a wide range of surface tensions.Comment: 6 pages, 8 figure
Relationship between solidification microstructure and hot cracking susceptibility for continuous casting of low-carbon and high-strength low-alloyed steels: A phase-field study
© The Minerals, Metals & Materials Society and ASM International 2013Hot cracking is one of the major defects in continuous casting of steels, frequently limiting the productivity. To understand the factors leading to this defect, microstructure formation is simulated for a low-carbon and two high-strength low-alloyed steels. 2D simulation of the initial stage of solidification is performed in a moving slice of the slab using proprietary multiphase-field software and taking into account all elements which are expected to have a relevant effect on the mechanical properties and structure formation during solidification. To account for the correct thermodynamic and kinetic properties of the multicomponent alloy grades, the simulation software is online coupled to commercial thermodynamic and mobility databases. A moving-frame boundary condition allows traveling through the entire solidification history starting from the slab surface, and tracking the morphology changes during growth of the shell. From the simulation results, significant microstructure differences between the steel grades are quantitatively evaluated and correlated with their hot cracking behavior according to the Rappaz-Drezet-Gremaud (RDG) hot cracking criterion. The possible role of the microalloying elements in hot cracking, in particular of traces of Ti, is analyzed. With the assumption that TiN precipitates trigger coalescence of the primary dendrites, quantitative evaluation of the critical strain rates leads to a full agreement with the observed hot cracking behavior. © 2013 The Minerals, Metals & Materials Society and ASM International
AC-KBO Revisited
Equational theories that contain axioms expressing associativity and
commutativity (AC) of certain operators are ubiquitous. Theorem proving methods
in such theories rely on well-founded orders that are compatible with the AC
axioms. In this paper we consider various definitions of AC-compatible
Knuth-Bendix orders. The orders of Steinbach and of Korovin and Voronkov are
revisited. The former is enhanced to a more powerful version, and we modify the
latter to amend its lack of monotonicity on non-ground terms. We further
present new complexity results. An extension reflecting the recent proposal of
subterm coefficients in standard Knuth-Bendix orders is also given. The various
orders are compared on problems in termination and completion.Comment: 31 pages, To appear in Theory and Practice of Logic Programming
(TPLP) special issue for the 12th International Symposium on Functional and
Logic Programming (FLOPS 2014
Convergence analysis of a multigrid algorithm for the acoustic single layer equation
We present and analyze a multigrid algorithm for the acoustic single layer
equation in two dimensions. The boundary element formulation of the equation is
based on piecewise constant test functions and we make use of a weak inner
product in the multigrid scheme as proposed in \cite{BLP94}. A full error
analysis of the algorithm is presented. We also conduct a numerical study of
the effect of the weak inner product on the oscillatory behavior of the
eigenfunctions for the Laplace single layer operator
Stochastic simulations of the quantum Zeno effect
Published versio
Identification of Novel Cetacean Poxviruses in Cetaceans Stranded in South West England
Poxvirus infections in marine mammals have been mainly reported through their clinical lesions
and electron microscopy (EM). Poxvirus particles in association with such lesions
have been demonstrated by EM and were previously classified as two new viruses, cetacean
poxvirus 1 (CePV-1) and cetacean poxvirus 2 (CePV-2). In this study, epidermal pox
lesions in cetaceans stranded in South West England (Cornwall) between 2008 and 2012
were investigated by electron microscopy and molecular analysis. PCR and sequencing of
a highly conserved region within the viral DNA polymerase gene ruled out both parapoxand
orthopoxviruses. Moreover, phylogenetic analysis of the PCR product clustered the sequences
with those previously described as cetacean poxviruses. However, taking the
close genetic distance of this gene fragment across the family of poxviridae into account, it
is reasonable to postulate further, novel cetacean poxvirus species. The nucleotide similarity
within each cluster (tentative species) detected ranged from 98.6% to 100%, whilst the
similarity between the clusters was no more than 95%. The detection of several species of
poxvirus in different cetacean species confirms the likelihood of a heterogeneous cetacean
poxvirus genus, comparable to the heterogeneity observed in other poxvirus genera
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