345 research outputs found
Identification of everyday objects on the basis of kinetic contours
Using kinetic contours derived from everyday objects, we investigated how motion affects object identification. In order not to be distinguishable when static, kinetic contours were made from random dot displays consisting of two regions, inside and outside the object contour. In Experiment 1, the dots were moving in only one of two regions. The objects were identified nearly equally well as soon as the dots either in the figure or in the background started to move. RTs decreased with increasing motion coherence levels and were shorter for complex, less compact objects than for simple, more compact objects. In Experiment 2, objects could be identified when the dots were moving both in the figure and in the background with speed and direction differences between the two. A linear increase in either the speed difference or the direction difference caused a linear decrease in RT for correct identification. In addition, the combination of speed and motion differences appeared to be super-additive
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Perceptual Grouping and Distance Estimates in Typical and Atypical Development: Comparing Performance across Perception, Drawing and Construction Tasks
Perceptual grouping is a pre-attentive process which serves to group local elements into global wholes, based on shared properties. One effect of perceptual grouping is to distort the ability to estimate the distance between two elements. In this study, biases in distance estimates, caused by four types of perceptual grouping, were measured across three tasks, a perception, a drawing and a construction task in both typical development (TD; Experiment 1) and in individuals with Williams syndrome (WS; Experiment 2). In Experiment 1, perceptual grouping distorted distance estimates across all three tasks. Interestingly, the effect of grouping by luminance was in the opposite direction to the effects of the remaining grouping types. We relate this to differences in the ability to inhibit perceptual grouping effects on distance estimates. Additive distorting influences were also observed in the drawing and the construction task, which are explained in terms of the points of reference employed in each task. Experiment 2 demonstrated that the above distortion effects are also observed in WS. Given the known deficit in the ability to use perceptual grouping in WS, this suggests a dissociation between the pre-attentive influence of and the attentive deployment of perceptual grouping in WS. The typical distortion in relation to drawing and construction points towards the presence of some typical location coding strategies in WS. The performance of the WS group differed from the TD participants on two counts. First, the pattern of overall distance estimates (averaged across interior and exterior distances) across the four perceptual grouping types, differed between groups. Second, the distorting influence of perceptual grouping was strongest for grouping by shape similarity in WS, which contrasts to a strength in grouping by proximity observed in the TD participants
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Evaluating the Use of Digital Creativity Support by Journalists in Newsrooms
This paper reports the evaluation of a new digital support tool designed to increase journalist creativity and productivity in newsrooms. After outlining the tool’s principles, interactive features and architecture, the paper reports the installation and use of the tool over 2 months by 12 journalists in the newsrooms of 3 newspapers. Results from this evaluation revealed that tool use was associated with published news articles rated as more novel but not more valuable than published articles written by the same journalists without the tool. However, tool use did not increase journalist productivity. The evaluation results were used to inform future changes to the digital creativity support tool
N=3 Warped Compactifications
Orientifolds with three-form flux provide some of the simplest string
examples of warped compactification. In this paper we show that some models of
this type have the unusual feature of D=4, N=3 spacetime supersymmetry. We
discuss their construction and low energy physics. Although the local form of
the moduli space is fully determined by supersymmetry, to find its global form
requires a careful study of the BPS spectrum.Comment: 27 pages, v2: 32pp., RevTeX4, fixed factors, slightly improved
sections 3D and 4B, v3: added referenc
Scaling Laws and Transient Times in 3He Induced Nuclear Fission
Fission excitation functions of compound nuclei in a mass region where shell
effects are expected to be very strong are shown to scale exactly according to
the transition state prediction once these shell effects are accounted for. The
fact that no deviations from the transition state method have been observed
within the experimentally investigated excitation energy regime allows one to
assign an upper limit for the transient time of 10 zs.Comment: 7 pages, TeX type, psfig, submitted to Phys. Rev. C, also available
at http://csa5.lbl.gov/moretto/ps/he3_paper.p
Fission barriers and asymmetric ground states in the relativistic mean field theory
The symmetric and asymmetric fission path for 240Pu, 232Th, and 226Ra is
investigated within the relativistic mean field model. Standard
parametrizations which are well fitted to nuclear ground state properties are
found to deliver reasonable qualitative and quantitative features of fission,
comparable to similar nonrelativstic calculations. Furthermore, stable octupole
deformations in the ground states of Radium isotopes are investigated. They are
found in a series of isotopes, qualitatively in agreement with nonrelativistic
models. But the quantitative details differ amongst the models and between the
various relativsitic parametrizations.Comment: 30 pages RevTeX, 7 tables, 12 low resolution Gif figures (high
resolution PostScript versions are available at
http://www.th.physik.uni-frankfurt.de/~bender/nucl_struct_publications.html
or at ftp://th.physik.uni-frankfurt.de/pub/bender
Fission fragment mass and total kinetic energy distributions of spontaneously fissioning plutonium isotopes
Perception of Symmetries in Drawings of Graphs
Symmetry is an important factor in human perception in general, as well as in
the visualization of graphs in particular. There are three main types of
symmetry: reflective, translational, and rotational. We report the results of a
human subjects experiment to determine what types of symmetries are more
salient in drawings of graphs. We found statistically significant evidence that
vertical reflective symmetry is the most dominant (when selecting among
vertical reflective, horizontal reflective, and translational). We also found
statistically significant evidence that rotational symmetry is affected by the
number of radial axes (the more, the better), with a notable exception at four
axes.Comment: Appears in the Proceedings of the 26th International Symposium on
Graph Drawing and Network Visualization (GD 2018
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