6,318 research outputs found
Visuo-tactile links in covert exogenous spatial attention remap across changes in unseen hand posture
We investigated the effect of unseen hand posture on cross-modal, visuo-tactile links in covert spatial attention. In Experiment 1, a spatially nonpredictive visual cue was presented to the left or right hemifleld shortly before a tactile target on either hand. To examine the spatial coordinates of any cross-modal cuing, the unseen hands were either uncrossed or crossed so that the left hand lay to the right and vice versa. Tactile up/down (i.e., index finger/thumb) judgments were better on the same side of external space as the visual cue, for both crossed and uncrossed postures. Thus, which hand was advantaged by a visual cue in a particular hemifield reversed across the different unseen postures. In Experiment 2, nonpredictive tactile cues now preceded visual targets. Up/down judgments for the latter were better on the same. side of external space as the tactile cue, again for both postures. These results demonstrate cross-modal links between vision and touch in exogenous covert spatial attention that remap across changes in unseen hand posture, suggesting a modulatory role for proprioception
Dynamics of Three Agent Games
We study the dynamics and resulting score distribution of three-agent games
where after each competition a single agent wins and scores a point. A single
competition is described by a triplet of numbers , and denoting the
probabilities that the team with the highest, middle or lowest accumulated
score wins. We study the full family of solutions in the regime, where the
number of agents and competitions is large, which can be regarded as a
hydrodynamic limit. Depending on the parameter values , we find six
qualitatively different asymptotic score distributions and we also provide a
qualitative understanding of these results. We checked our analytical results
against numerical simulations of the microscopic model and find these to be in
excellent agreement. The three agent game can be regarded as a social model
where a player can be favored or disfavored for advancement, based on his/her
accumulated score. It is also possible to decide the outcome of a three agent
game through a mini tournament of two-a gent competitions among the
participating players and it turns out that the resulting possible score
distributions are a subset of those obtained for the general three agent-games.
We discuss how one can add a steady and democratic decline rate to the model
and present a simple geometric construction that allows one to write down the
corresponding score evolution equations for -agent games
How to get unlimited observing time on a 4 metre telescope
As the astronomical community moves ever more towards fewer and larger telescopes it is not just desirable but essential to make the maximum possible use of these new facilities. The Hitchhiker parallel CCD camera has been specially designed to increase the scientific output of a large telescope by imaging the off-axis field of view. The large data set collected by this instrument consists of deep CCD multicolor data of the distant Universe and is extremely well suited to the study of faint galaxies and their evolution, as well as other areas. The instrument's design and some of its projects are briefly discussed below and demonstrates the scientific value such instruments could have if incorporated on all new telescopes
The GALEX-SDSS NUV & FUV Flux Density and Local Star-Formation Rate
We calculate the local UV flux density in the GALEX MIS FUV and NUV bands
using redshifts provided by SDSS DR7. Luminosity functions are calculated for
the overlapping MIS and SDSS sample, allowing flux densities to be measured and
the local star formation rate (SFR) to be calculated using volumes much larger
than previous FUV based estimates. We calculate flux densities for a dust
corrected low redshift (0.013 < z < 0.1) sample of f[FUV] = 22.24 \pm 3.13
\times 10^25 h ergs s^-1 Hz^-1 Mpc^-3, f[NUV] = 38.54 \pm 5.30 \times 10^25 h
ergs s^-1 Hz^-1 Mpc^-3. The star formation rate density found is
0.0312\pm0.0045 h M\odot yr^-1 Mpc^-3. This is larger than published rates
recently found using the UV implied SFR, though the major discrepancy is the
correction made for dust attenuation and once this is dealt with consistently
the results agree well. These values are also consistent with recent Halpha
derived SFRs. Once cosmic variance is taken into account most of the recent
SFRs at low redshift (z < 0.3) found in the literature can be brought into
agreement, however the lowest redshift values (z < 0.045) do appear to be
significantly lower.Comment: 14 pages, 10 figures, accepted for publication in MNRA
Attentional load and sensory competition in human vision: Modulation of fMRI responses by load fixation during task-irrelevant stimulation in the peripheral visual field.
Perceptual suppression of distractors may depend on both endogenous and exogenous factors, such as attentional load of the current task and sensory competition among simultaneous stimuli, respectively. We used functional magnetic resonance imaging (fMRI) to compare these two types of attentional effects and examine how they may interact in the human brain. We varied the attentional load of a visual monitoring task performed on a rapid stream at central fixation without altering the central stimuli themselves, while measuring the impact on fMRI responses to task-irrelevant peripheral checkerboards presented either unilaterally or bilaterally. Activations in visual cortex for irrelevant peripheral stimulation decreased with increasing attentional load at fixation. This relative decrease was present even in V1, but became larger for successive visual areas through to V4. Decreases in activation for contralateral peripheral checkerboards due to higher central load were more pronounced within retinotopic cortex corresponding to 'inner' peripheral locations relatively near the central targets than for more eccentric 'outer' locations, demonstrating a predominant suppression of nearby surround rather than strict 'tunnel vision' during higher task load at central fixation. Contralateral activations for peripheral stimulation in one hemifield were reduced by competition with concurrent stimulation in the other hemifield only in inferior parietal cortex, not in retinotopic areas of occipital visual cortex. In addition, central attentional load interacted with competition due to bilateral versus unilateral peripheral stimuli specifically in posterior parietal and fusiform regions. These results reveal that task-dependent attentional load, and interhemifield stimulus-competition, can produce distinct influences on the neural responses to peripheral visual stimuli within the human visual system. These distinct mechanisms in selective visual processing may be integrated within posterior parietal areas, rather than earlier occipital cortex
From Old Labour to New Labour: a comment on Rubinstein
In a critique of our book New Labour, David Rubinstein has argued that we exaggerate the degree of difference between Old and New Labour and underplay the similarities. In this article we agree with many of the continuities that Rubinstein outlines. However, we argue that he himself gives plenty of evidence in favour of our thesis that change has been marked in many policy areas. We argue that we give a good account of the wider social factors that he says accounts for such change. In this article we offer a restatement of the view that New Labour offers a `post-Thatcherite politics. New Labour breaks both with post-war social democracy and with Thatcherism
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