16,948 research outputs found
Efficiency of the Wang-Landau algorithm: a simple test case
We analyze the efficiency of the Wang-Landau algorithm to sample a multimodal
distribution on a prototypical simple test case. We show that the exit time
from a metastable state is much smaller for the Wang Landau dynamics than for
the original standard Metropolis-Hastings algorithm, in some asymptotic regime.
Our results are confirmed by numerical experiments on a more realistic test
case
Integrating Item Accuracy and Reaction Time to Improve the Measurement of Inhibitory Control Abilities in Early Childhood
Efforts to improve children’s executive function are often hampered by the lack of measures that are optimized for use during the transition from preschool to elementary school. Whereas preschool-based measures often emphasize response accuracy, elementary school-based measures emphasize reaction time (RT)—especially for measures inhibitory control (IC) tasks that typically have a speeded component. The primary objective of this study was to test in a preschool-aged sample whether the joint use of item-level accuracy and RT data resulted in improved scoring for three IC tasks relative to scores derived from accuracy data alone. Generally, the joint use of item-level accuracy and RT data resulted in modest improvements in the measurement precision of IC abilities. Moreover, the joint use of item-level accuracy and RT helped eliminate floor and ceiling effects that occurred when accuracy data were considered alone. Results are discussed with respect to the importance of scoring IC tasks in ways that are maximally informative for program evaluation and longitudinal modeling
Collective Identities, European Solidarity: Identification Patterns and Preferences for European Social Insurance
A degree of collective identity is often perceived to be a requirement for integration of core state powers, and even more so when redistributive measures are at stake. Existing research has shown that European identity is an important correlate of support for European social policy in general. This article explores the ways in which collective identities relate to the multidimensional nature of social policy at the European level. We explore in particular the features of European social policy that receive the most support from European publics, and how local, national and European identity moderates these preferences. We expect that people who have primarily sub-national or national attachments are less supportive of generous schemes and schemes that involve greater cross-country redistribution, and are more in favour of decentralized schemes administered by the member states than those with stronger European identities. We find support for these expectations in a conjoint survey experiment fielded in autumn 2018 in 13 EU member states
Doenças de uva.
São conhecidas na videira (Vitis spp.) dezenas de doenças consideradas de origem viral. A videira, por ser propagada vegetativamente, facilita a disseminação destes patógenos e favorece o aparecimento de doenças complexas, pelo acúmulo de diferentes vÃrus numa mesma planta
Importância da origem do material de propagação na qualidade da muda de videira.
bitstream/CNPUV/8128/1/cir050.pdfDisponÃvel também no formato online
Electroweak Sudakov Logarithms and Real Gauge-Boson Radiation in the TeV Region
Electroweak radiative corrections give rise to large negative,
double-logarithmically enhanced corrections in the TeV region. These are partly
compensated by real radiation and, moreover, affected by selecting
isospin-noninvariant external states. We investigate the impact of real gauge
boson radiation more quantitatively by considering different restricted final
state configurations. We consider successively a massive abelian gauge theory,
a spontaneously broken SU(2) theory and the electroweak Standard Model. We find
that details of the choice of the phase space cuts, in particular whether a
fraction of collinear and soft radiation is included, have a strong impact on
the relative amount of real and virtual corrections.Comment: 20 pages, 4 figure
Low-Temperature Orientation Dependence of Step Stiffness on {111} Surfaces
For hexagonal nets, descriptive of {111} fcc surfaces, we derive from
combinatoric arguments a simple, low-temperature formula for the orientation
dependence of the surface step line tension and stiffness, as well as the
leading correction, based on the Ising model with nearest-neighbor (NN)
interactions. Our formula agrees well with experimental data for both Ag and
Cu{111} surfaces, indicating that NN-interactions alone can account for the
data in these cases (in contrast to results for Cu{001}). Experimentally
significant corollaries of the low-temperature derivation show that the step
line tension cannot be extracted from the stiffness and that with plausible
assumptions the low-temperature stiffness should have 6-fold symmetry, in
contrast to the 3-fold symmetry of the crystal shape. We examine Zia's exact
implicit solution in detail, using numerical methods for general orientations
and deriving many analytic results including explicit solutions in the two
high-symmetry directions. From these exact results we rederive our simple
result and explore subtle behavior near close-packed directions. To account for
the 3-fold symmetry in a lattice gas model, we invoke a novel
orientation-dependent trio interaction and examine its consequences.Comment: 11 pages, 8 figure
A Unified Nanopublication Model for Effective and User-Friendly Access to the Elements of Scientific Publishing
Scientific publishing is the means by which we communicate and share
scientific knowledge, but this process currently often lacks transparency and
machine-interpretable representations. Scientific articles are published in
long coarse-grained text with complicated structures, and they are optimized
for human readers and not for automated means of organization and access. Peer
reviewing is the main method of quality assessment, but these peer reviews are
nowadays rarely published and their own complicated structure and linking to
the respective articles is not accessible. In order to address these problems
and to better align scientific publishing with the principles of the Web and
Linked Data, we propose here an approach to use nanopublications as a unifying
model to represent in a semantic way the elements of publications, their
assessments, as well as the involved processes, actors, and provenance in
general. To evaluate our approach, we present a dataset of 627 nanopublications
representing an interlinked network of the elements of articles (such as
individual paragraphs) and their reviews (such as individual review comments).
Focusing on the specific scenario of editors performing a meta-review, we
introduce seven competency questions and show how they can be executed as
SPARQL queries. We then present a prototype of a user interface for that
scenario that shows different views on the set of review comments provided for
a given manuscript, and we show in a user study that editors find the interface
useful to answer their competency questions. In summary, we demonstrate that a
unified and semantic publication model based on nanopublications can make
scientific communication more effective and user-friendly
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