266,433 research outputs found
Electron-deuteron DIS with spectator tagging at EIC: Development of theoretical framework
An Electron-Ion Collider (EIC) would enable next-generation measurements of
deep-inelastic scattering (DIS) on the deuteron with detection of a
forward-moving nucleon (p, n) and measurement of its recoil momentum
("spectator tagging"). Such experiments offer full control of the nuclear
configuration during the high-energy process and can be used for precision
studies of the neutron's partonic structure and its spin dependence, nuclear
modifications of partonic structure, and nuclear shadowing at small x. We
review the theoretical description of spectator tagging at EIC energies
(light-front nuclear structure, on-shell extrapolation in the recoil nucleon
momentum, final-state interactions, diffractive effects at small x) and report
about on-going developments.Comment: 7 pages, 3 figures. Proceedings of 6th International Conference on
Physics Opportunities at an Electron-Ion Collider (POETIC6), Palaiseau,
France, 7-11 September 201
Detecting Low Rapport During Natural Interactions in Small Groups from Non-Verbal Behaviour
Rapport, the close and harmonious relationship in which interaction partners
are "in sync" with each other, was shown to result in smoother social
interactions, improved collaboration, and improved interpersonal outcomes. In
this work, we are first to investigate automatic prediction of low rapport
during natural interactions within small groups. This task is challenging given
that rapport only manifests in subtle non-verbal signals that are, in addition,
subject to influences of group dynamics as well as inter-personal
idiosyncrasies. We record videos of unscripted discussions of three to four
people using a multi-view camera system and microphones. We analyse a rich set
of non-verbal signals for rapport detection, namely facial expressions, hand
motion, gaze, speaker turns, and speech prosody. Using facial features, we can
detect low rapport with an average precision of 0.7 (chance level at 0.25),
while incorporating prior knowledge of participants' personalities can even
achieve early prediction without a drop in performance. We further provide a
detailed analysis of different feature sets and the amount of information
contained in different temporal segments of the interactions.Comment: 12 pages, 6 figure
Distinguishing Topical and Social Groups Based on Common Identity and Bond Theory
Social groups play a crucial role in social media platforms because they form
the basis for user participation and engagement. Groups are created explicitly
by members of the community, but also form organically as members interact. Due
to their importance, they have been studied widely (e.g., community detection,
evolution, activity, etc.). One of the key questions for understanding how such
groups evolve is whether there are different types of groups and how they
differ. In Sociology, theories have been proposed to help explain how such
groups form. In particular, the common identity and common bond theory states
that people join groups based on identity (i.e., interest in the topics
discussed) or bond attachment (i.e., social relationships). The theory has been
applied qualitatively to small groups to classify them as either topical or
social. We use the identity and bond theory to define a set of features to
classify groups into those two categories. Using a dataset from Flickr, we
extract user-defined groups and automatically-detected groups, obtained from a
community detection algorithm. We discuss the process of manual labeling of
groups into social or topical and present results of predicting the group label
based on the defined features. We directly validate the predictions of the
theory showing that the metrics are able to forecast the group type with high
accuracy. In addition, we present a comparison between declared and detected
groups along topicality and sociality dimensions.Comment: 10 pages, 6 figures, 2 table
Decays into {\pi}+{\pi}- of the f0(1370) scalar glueball candidate in pp central exclusive production experiments
The existence and properties of the f0(1370) scalar meson are rather well
established from data of antiproton annihilations at rest. However conflicting
results from Central Exclusive Production (CEP) experiments of the last
millennium and ignorance of data from antiproton annihilations at rest in H2
and D2 bubble chambers have generated doubts on the very existence of the
f0(1370). Properties of {\pi}+{\pi}- pairs produced in central exclusive
production (CEP) reactions observed in old data together with data collected in
the current decade at high energy colliders permit to show that {\pi}+{\pi}-
decays of the f0(1370) meson are directly observable as an isolated peak
between 1.1 and 1.6 GeV. Consequences of this observation and prospects for the
identification of the scalar glueball ground-state are discussed.Comment: 20 pages, 11 figure
Signatures of LCDM substructure in tidal debris
In the past decade, surveys of the stellar component of the Galaxy have
revealed a number of streams from tidally disrupted dwarf galaxies and globular
clusters. Simulations of hierarchical structure formation in LCDM cosmologies
predict that the dark matter halo of a galaxy like the Milky Way contains
hundreds of subhalos with masses of ~10^8 solar masses and greater, and it has
been suggested that the existence of coherent tidal streams is incompatible
with the expected abundance of substructure. We investigate the effects of dark
matter substructure on tidal streams by simulating the disruption of a
self-gravitating satellite on a wide range of orbits in different host models
both with and without substructure. We find that the halo shape and the
specific orbital path more strongly determine the overall degree of disruption
of the satellite than does the presence or absence of substructure, i.e., the
changes in the large-scale properties of the tidal debris due to substructure
are small compared to variations in the debris from different orbits in a
smooth potential. Substructure typically leads to an increase in the degree of
clumpiness of the tidal debris in sky projection, and in some cases a more
compact distribution in line-of-sight velocity. Substructure also leads to
differences in the location of sections of debris compared to the results of
the smooth halo model, which may have important implications for the
interpretation of observed tidal streams. A unique signature of the presence of
substructure in the halo which may be detectable by upcoming surveys is
identified. We conclude, however, that predicted levels of substructure are
consistent with a detection of a coherent tidal stream from a dwarf galaxy.Comment: 15 pages, 13 figures, accepted for publication in ApJ. Matches
accepted versio
Automatic detection of accommodation steps as an indicator of knowledge maturing
Jointly working on shared digital artifacts â such as wikis â is a well-tried method of developing knowledge collectively within a group or organization. Our assumption is that such knowledge maturing is an accommodation process that can be measured by taking the writing process itself into account. This paper describes the development of a tool that detects accommodation automatically with the help of machine learning algorithms. We applied a software framework for task detection to the automatic identification of accommodation processes within a wiki. To set up the learning algorithms and test its performance, we conducted an empirical study, in which participants had to contribute to a wiki and, at the same time, identify their own tasks. Two domain experts evaluated the participantsâ micro-tasks with regard to accommodation. We then applied an ontology-based task detection approach that identified accommodation with a rate of 79.12%. The potential use of our tool for measuring knowledge maturing online is discussed
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