4,195 research outputs found
Photoluminescence studies of selected styrylquinolinium thin films made using thermal evaporation deposition technique
In this paper we present a photoluminescence (PL) study of new styrylquinolinium dyes. We made a comparative study of the luminescent properties of thin films grown on quartz substrates using thermal evaporation deposition method. Investigated films show PL emission from the violet to near-IR region at room temperature
Space, Time and Color in Hadron Production Via e+e- -> Z0 and e+e- -> W+W-
The time-evolution of jets in hadronic e+e- events at LEP is investigated in
both position- and momentum-space, with emphasis on effects due to color flow
and particle correlations. We address dynamical aspects of the four
simultanously-evolving, cross-talking parton cascades that appear in the
reaction e+e- -> gamma/Z0 -> W+W- -> q1 q~2 q3 q~4, and compare with the
familiar two-parton cascades in e+e- -> Z0 -> q1 q~2. We use a QCD statistical
transport approach, in which the multiparticle final state is treated as an
evolving mixture of partons and hadrons, whose proportions are controlled by
their local space-time geography via standard perturbative QCD parton shower
evolution and a phenomenological model for non-perturbative parton-cluster
formation followed by cluster decays into hadrons. Our numerical simulations
exhibit a characteristic `inside-outside' evolution simultanously in position
and momentum space. We compare three different model treatments of color flow,
and find large effects due to cluster formation by the combination of partons
from different W parents. In particular, we find in our preferred model a shift
of several hundred MeV in the apparent mass of the W, which is considerably
larger than in previous model calculations. This suggests that the
determination of the W mass at LEP2 may turn out to be a sensitive probe of
spatial correlations and hadronization dynamics.Comment: 52 pages, latex, 18 figures as uu-encoded postscript fil
Information professionals and copyright literacy: a multinational study
Purpose: The purpose of this paper is to present findings from a multinational survey on copyright literacy of specialists from libraries and other cultural institutions.
Design/methodology/approach: This paper is based on a multinational survey of copyright literacy competencies of Library and Information Science (LIS) professionals and those who work in the cultural heritage sector (archives and museums), conducted in 13 countries, namely Bulgaria (BG), Croatia (CR), Finland (FI), France (FR), Hungary (HU), Lithuania (LT), Mexico (MX), Norway (NO), Portugal (PT), Romania (RO), Turkey (TR), UK and USA in the period July 2013-March 2015. An online survey instrument was developed in order to collect data from professionals regarding their familiarity with, knowledge and awareness of, and opinions on copyright-related issues.
Findings: Findings of this study highlight gaps in existing knowledge of copyright, and information about the level of copyright literacy of LIS and cultural sector professionals. Also attitudes toward copyright learning content in academic education and continuing professional development training programs are investigated.
Originality/value: This study aimed to address a gap in the literature by encompassing specialists from the cultural institutions in an international comparative context. The paper offers guidance for further understanding of copyright in a wider framework of digital and information literacy; and for the implementation of copyright policy, and the establishment of copyright advisor positions in cultural institutions. The recommendations support a revision of academic and continuing education programs learning curriculum and methods
Ab initio van der Waals interactions in simulations of water alter structure from mainly tetrahedral to high-density-like
The structure of liquid water at ambient conditions is studied in ab initio
molecular dynamics simulations using van der Waals (vdW) density-functional
theory, i.e. using the new exchange-correlation functionals optPBE-vdW and
vdW-DF2. Inclusion of the more isotropic vdW interactions counteracts highly
directional hydrogen-bonds, which are enhanced by standard functionals. This
brings about a softening of the microscopic structure of water, as seen from
the broadening of angular distribution functions and, in particular, from the
much lower and broader first peak in the oxygen-oxygen pair-correlation
function (PCF), indicating loss of structure in the outer solvation shells. In
combination with softer non-local correlation terms, as in the new
parameterization of vdW-DF, inclusion of vdW interactions is shown to shift the
balance of resulting structures from open tetrahedral to more close-packed. The
resulting O-O PCF shows some resemblance with experiment for high-density water
(A. K. Soper and M. A. Ricci, Phys. Rev. Lett., 84:2881, 2000), but not
directly with experiment for ambient water. However, an O-O PCF consisting of a
linear combination of 70% from vdW-DF2 and 30% from experiment on low-density
liquid water reproduces near-quantitatively the experimental O-O PCF for
ambient water, indicating consistency with a two-liquid model with fluctuations
between high- and low-density regions
Evidence for Colour-Octet Mechanism from CERN LEP2 gamma gamma -> J/psi + X Data
We present theoretical predictions for the transverse-momentum distribution
of J/psi mesons promptly produced in gamma gamma collisions within the
factorization formalism of nonrelativistic quantum chromodynamics, including
the contributions from both direct and resolved photons, and we perform a
conservative error analysis. The fraction of J/psi mesons from decays of
bottom-flavoured hadrons is estimated to be negligibly small. New data taken by
the DELPHI Collaboration at LEP2 nicely confirm these predictions, while they
disfavour those obtained within the traditional colour-singlet model.Comment: 11 pages (Latex), 3 figures (Postscript); updated experimental data
included, references added, accepted for publication in Phys. Rev. Let
Database Species-Area Relationships in Palaearctic Grasslands.
The database collects the data resulting from the sampling of species-area relationships (SARs) in grassland communities in the
Palaearctic. The core features of the database are the complete data from the EDGG Research Expeditions, but similar data from other studies
are also included. Main features of the majority of relevés are: (i) they are part of nested-plot series (typically 0.0001-100 m²), (ii) bryophytes and
lichens are treated comprehensively; (iii) detailed soil and other environmental data
European Union enlargement, post-accession migration and imaginative geographies of the ‘New Europe’: media discourses in Romania and the United Kingdom.
This paper is concerned with re-imaginings of ‘Europe’ following the accession to the European Union (EU) of former ‘Eastern European’ countries. In particular it explores media representations of post-EU accession migration from Romania to the United Kingdom in the UK and Romanian newspaper press. Todorova’s (1997) notion of Balkanism is deployed as a theoretical construct to facilitate the analysis of these representations as first, the continuation of long-standing and deeply embedded imaginings of the ‘East’ of Europe and, second, as a means of contesting these discourses. The paper explores the way in which the UK press construct Balkanist discourses about Romania and Romanian migrants, and then analyses how the Romanian press has contested such discourses. The paper argues that the idea of the ‘East’ remains important in constructing notions of ‘Europe’ within popular media geographies
Mechanical and Electronic Properties of MoS Nanoribbons and Their Defects
We present our study on atomic, electronic, magnetic and phonon properties of
one dimensional honeycomb structure of molybdenum disulfide (MoS) using
first-principles plane wave method. Calculated phonon frequencies of bare
armchair nanoribbon reveal the fourth acoustic branch and indicate the
stability. Force constant and in-plane stiffness calculated in the harmonic
elastic deformation range signify that the MoS nanoribbons are stiff quasi
one dimensional structures, but not as strong as graphene and BN nanoribbons.
Bare MoS armchair nanoribbons are nonmagnetic, direct band gap
semiconductors. Bare zigzag MoS nanoribbons become half-metallic as a
result of the (2x1) reconstruction of edge atoms and are semiconductor for
minority spins, but metallic for the majority spins. Their magnetic moments and
spin-polarizations at the Fermi level are reduced as a result of the
passivation of edge atoms by hydrogen. The functionalization of MoS
nanoribbons by adatom adsorption and vacancy defect creation are also studied.
The nonmagnetic armchair nanoribbons attain net magnetic moment depending on
where the foreign atoms are adsorbed and what kind of vacancy defect is
created. The magnetization of zigzag nanoribbons due to the edge states is
suppressed in the presence of vacancy defects.Comment: 11 pages, 5 figures, first submitted at November 23th, 200
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