951 research outputs found
Measuring, analysing and artificially generating head nodding signals in dyadic social interaction
Social interaction involves rich and complex behaviours where verbal and non-verbal signals are exchanged in dynamic patterns. The aim of this thesis is to explore new ways of measuring and analysing interpersonal coordination as it naturally occurs in social interactions. Specifically, we want to understand what different types of head nods mean in different social contexts, how they are used during face-to-face dyadic conversation, and if they relate to memory and learning. Many current methods are limited by time-consuming and low-resolution data, which cannot capture the full richness of a dyadic social interaction. This thesis explores ways to demonstrate how high-resolution data in this area can give new insights into the study of social interaction. Furthermore, we also want to demonstrate the benefit of using virtual reality to artificially generate interpersonal coordination to test our hypotheses about the meaning of head nodding as a communicative signal.
The first study aims to capture two patterns of head nodding signals – fast nods and slow nods – and determine what they mean and how they are used across different conversational contexts. We find that fast nodding signals receiving new information and has a different meaning than slow nods. The second study aims to investigate a link between memory and head nodding behaviour. This exploratory study provided initial hints that there might be a relationship, though further analyses were less clear. In the third study, we aim to test if interactive head nodding in virtual agents can be used to measure how much we like the virtual agent, and whether we learn better from virtual agents that we like. We find no causal link between memory performance and interactivity. In the fourth study, we perform a cross-experimental analysis of how the level of interactivity in different contexts (i.e., real, virtual, and video), impacts on memory and find clear differences between them
The Unfolding of Digital Transformation in Pre-Digital Companies: A Meta-Case Analysis
Due to the growing dispersion of digital technology, many organizations engage in digital transformation. While digital transformation case studies have increased in the information systems and management domain, different ways in which digital transformation unfolds have been proposed. We perform a qualitative meta-analysis of case studies on digital transformation initiatives. From this analysis, we develop two core narratives (a dialectical and a teleological narrative) that we explain in-depth and derive two research avenues from our analysis. Thus, we are advancing the discussion on the unfolding of digital transformation by 1) summarizing existing case studies into two core narratives and 2) shifting the discussion from an explorative character towards a more explanatory approach to better understand how digital transformation unfolds within pre-digital organizations
Spatial Distribution of Nucleosynthesis Products in Cassiopeia A: Comparison Between Observations and 3D Explosion Models
We examine observed heavy element abundances in the Cassiopeia A supernova
remnant as a constraint on the nature of the Cas A supernova. We compare bulk
abundances from 1D and 3D explosion models and spatial distribution of elements
in 3D models with those derived from X-ray observations. We also examine the
cospatial production of 26Al with other species. We find that the most reliable
indicator of the presence of 26Al in unmixed ejecta is a very low S/Si ratio
(~0.05). Production of N in O/S/Si-rich regions is also indicative. The
biologically important element P is produced at its highest abundance in the
same regions. Proxies should be detectable in supernova ejecta with high
spatial resolution multiwavelength observations.Comment: To appear in the Conference Proceedings for the "10th Symposium on
Nuclei in the Cosmos (NIC X)", July 27 - August 1 2008, Mackinack Island,
Michigan, US
NuGrid: Toward High Precision Double-Degenerate Merger Simulations with SPH in 3D
We present preliminary results from recent high-resolution double-degenerate
merger simulations with the Smooth Particle Hydrodynamics (SPH) technique. We
put particular emphasis on verification and validation in our effort and show
the importance of details in the initial condition setup for the final outcome
of the simulation. We also stress the dynamical importance of including shocks
in the simulations. These results represent a first step toward a suite of
simulations that will shed light on the question whether double-degenerate
mergers are a viable path toward type 1a supernovae. In future simulations, we
will make use of the capabilities of the NuGrid collaboration in
post-processing SPH particle trajectories with a complete nuclear network to
follow the detailed nuclear reactions during the dynamic merger phase.Comment: To appear in the Conference Proceedings for the "10th Symposium on
Nuclei in the Cosmos (NIC X)", July 27 - August 1 2008, Mackinack Island,
Michigan, US
Nucleosynthetic Yields from "Collapsars"
The "collapsar" engine for gamma-ray bursts invokes as its energy source the
failure of a normal supernova and the formation of a black hole. Here we
present the results of the first three-dimensional simulation of the collapse
of a massive star down to a black hole, including the subsequent accretion and
explosion. The explosion differs significantly from the axisymmetric scenario
obtained in two-dimensional simulations; this has important consequences for
the nucleosynthetic yields. We compare the nucleosynthetic yields to those of
hypernovae. Calculating yields from three-dimensional explosions requires new
strategies in post-process nucleosynthesis; we discuss NuGrid's plan for
three-dimensional yields.Comment: To appear in the Conference Proceedings for the "10th Symposium on
Nuclei in the Cosmos (NIC X)", July 27 - August 1 2008, Mackinack Island,
Michigan, US
Difficulties in Probing Nuclear Physics: A Study of Ti and Ni
The nucleosynthetic yield from a supernova explosion depends upon a variety
of effects: progenitor evolution, explosion process, details of the nuclear
network, and nuclear rates. Especially in studies of integrated stellar yields,
simplifications reduce these uncertainties. But nature is much more complex,
and to actually study nuclear rates, we will have to understand the full,
complex set of processes involved in nucleosynthesis. Here we discuss a few of
these complexities and detail how the NuGrid collaboration will address them.Comment: To appear in the Conference Proceedings for the "10th Symposium on
Nuclei in the Cosmos (NIC X)", July 27 - August 1 2008, Mackinack Island,
Michigan, US
Complete nucleosynthesis calculations for low-mass stars from NuGrid
Many nucleosynthesis and mixing processes of low-mass stars as they evolve
from the Main Sequence to the thermal-pulse Asymptotic Giant Branch phase
(TP-AGB) are well understood (although of course important physics components,
e.g. rotation, magnetic fields, gravity wave mixing, remain poorly known).
Nevertheless, in the last years presolar grain measurements with high
resolution have presented new puzzling problems and strong constraints on
nucleosynthesis processes in stars. The goal of the NuGrid collaboration is to
present uniform yields for a large range of masses and metallicities, including
lowmass stars and massive stars and their explosions. Here we present the
first calculations of stellar evolution and high-resolution, post-processing
simulations of an AGB star with an initial mass of 2 M_sun and solar-like
metallicity (Z=0.01), based on the post-processing code PPN. In particular, we
analyze the formation and evolution of the radiative 13C-pocket between the
17th TP and the 18th TP. The s-process nucleosynthesis profile of a sample of
heavy isotopes is also discussed, before the next convective TP occurrence.Comment: To appear in the Conference Proceedings for the "10th Symposium on
Nuclei in the Cosmos (NIC X)", July 27 - August 1 2008, Mackinack Island,
Michigan, US
Nucleosynthesis Calculations from Core-Collapse Supernovae
We review some of the uncertainties in calculating nucleosynthetic yields,
focusing on the explosion mechanism. Current yield calculations tend to either
use a piston, energy injection, or enhancement of neutrino opacities to drive
an explosion. We show that the energy injection, or more accurately, an entropy
injection mechanism is best-suited to mimic our current understanding of the
convection-enhanced supernova engine. The enhanced neutrino-opacity technique
is in qualitative disagreement with simulations of core-collapse supernovae and
will likely produce errors in the yields. But piston-driven explosions are the
most discrepant. Piston-driven explosion severely underestimate the amount of
fallback, leading to order-of-magnitude errors in the yields of heavy elements.
To obtain yields accurate to the factor of a few level, we must use entropy or
energy injection and this has become the NuGrid collaboration approach.Comment: To appear in the Conference Proceedings for the "10th Symposium on
Nuclei in the Cosmos (NIC X)", July 27 - August 1 2008, Mackinack Island,
Michigan, US
44Ti and 56Ni in core-collapse supernovae
We investigate the physical conditions where 44Ti and 56Ni are created in
core-collapse supernovae. In this preliminary work we use a series of
post-processing network calculations with parametrized expansion profiles that
are representative of the wide range of temperatures, densities and
electron-to-baryon ratios found in 3D supernova simulations. Critical flows
that affect the final yields of 44Ti and 56Ni are assessed.Comment: To appear in the Conference Proceedings for the "10th Symposium on
Nuclei in the Cosmos (NIC X)", July 27 - August 1 2008, Mackinack Island,
Michigan, US
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