5,631 research outputs found
Object-guided Spatial Attention in Touch: Holding the Same Object with Both Hands Delays Attentional Selection
Abstract
Previous research has shown that attention to a specific location on a uniform visual object spreads throughout the entire object. Here we demonstrate that, similar to the visual system, spatial attention in touch can be object guided. We measured event-related brain potentials to tactile stimuli arising from objects held by observers' hands, when the hands were placed either near each other or far apart, holding two separate objects, or when they were far apart but holding a common object. Observers covertly oriented their attention to the left, to the right, or to both hands, following bilaterally presented tactile cues indicating likely tactile target location(s). Attentional modulations for tactile stimuli at attended compared to unattended locations were present in the time range of early somatosensory components only when the hands were far apart, but not when they were near. This was found to reflect enhanced somatosensory processing at attended locations rather than suppressed processing at unattended locations. Crucially, holding a common object with both hands delayed attentional selection, similar to when the hands were near. This shows that the proprioceptive distance effect on tactile attentional selection arises when distant event locations can be treated as separate and unconnected sources of tactile stimulation, but not when they form part of the same object. These findings suggest that, similar to visual attention, both space- and object-based attentional mechanisms can operate when we select between tactile events on our body surface.</jats:p
The Truth in Compatibilism and the truth of Libertarianism
The paper offers the outlines of a response to the often-made suggestion is that it is impossible to see how indeterminism could possibly provide us with anything that we might want in the way of freedom, anything that could really amount to control, as opposed merely to an openness in the flow of reality that would constitute merely the injection of chance, or randomness, into the unfolding of the processes which underlie our activity. It is suggested that the best first move for the libertarian is to make a number of important concessions to the compatibilist. It should be conceded, in particular, that certain sorts of alternative possibilities are neither truly available to real, worldly agents, nor required in order that those agents should act freely; and it should be admitted also that it is the compatibilist who tends to give the most plausible sorts of analyses of many of the ‘can’ and ‘could have’ statements which seem to need to be assertible of those agents we regard as free. But these concessions do not bring compatibilism itself in their wake. The most promising version of libertarianism, it is argued, should be based on the idea that agency itself (and not merely some special instances of it which we might designate with the honorific appellation ‘free’) is inconsistent with determinism. This version of libertarianism, it is claimed, can avoid the objection that indeterminism is as difficult to square with true agential control as determinism can sometimes seem to be
Non-linear Microwave Surface Impedance of Epitaxial HTS Thin Films in Low DC Magnetic Fields
We have carried out non-linear microwave (8 GHz) surface impedance
measurements of three YBaCuO thin films in dc magnetic fields
(parallel to c axis) up to 12 mT using a coplanar resonator technique. In zero
dc field the three films, deposited by the same method, show a spread of
low-power residual surface resistance, and penetration depth,
(T=15 K) within a factor of 1.9. However, they exhibit dramatically
different microwave field, dependences of the surface resistance,
, but universal dependence. Application of a dc field was
found to affect not only absolute values of and , but the functional
dependences and as well. For some of the samples
the dc field was found to decrease below its zero-field low-power value.Comment: 4 pages, 4 figures. To be published in IEEE Trans. Appl. Supercond.,
June 199
The Asymmetric Thick Disk: A Star Count and Kinematic Analysis. II The Kinematics
We report a kinematic signature associated with the observed asymmetry in the
distribution of thick disk/inner halo stars interior to the Solar circle
described in Paper I. In that paper we found a statistically significant excess
(20% to 25 %) of stars in quadrant I (l ~ 20 deg to 55 deg) both above and
below the plane (b ~ +/- 25 deg to +/- 45 deg) compared to the complementary
region in quadrant IV. We have measured Doppler velocities for 741 stars,
selected according to the same magnitude and color criteria, in the direction
of the asymmetry and in the corresponding fields in quadrant IV. We have also
determined spectral types and metallicities measured from the same spectra. We
not only find an asymmetric distribution in the V_LSR velocities for the stars
in the two regions, but the angular rate of rotation, w, for the stars in
quadrant I reveals a slower effective rotation rate compared to the
corresponding quadrant IV stars. We use our [Fe/H] measurements to separate the
stars into the three primary population groups, halo, thick disk, and disk, and
conclude that it is primarily the thick disk stars that show the slower
rotation in quadrant I. A solution for the radial, tangential and vertical
components of the V_LSR velocities, reveals a significant lag of ~ 80 to 90
km/s in the direction of Galactic rotation for the thick disk stars in quadrant
I, while in quadrant IV, the same population has only a ~ 20 km/s lag. The
results reported here support a rotational lag among the thick disk stars due
to a gravitational interaction with the bar as the most likely explanation for
the asymmetry in both the star counts and the kinematics. The affected thick
disk stars, however, may be associated with the recently discovered Canis Major
debris stream or a similar merger event (abridged).Comment: Accepted for publication in the Astronomical Journa
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Results of an aqueous source term model for a radiological risk assessment of the Drigg LLW Site, U.K.
A radionuclide source term model has been developed which simulates the biogeochemical evolution of the Drigg low level waste (LLW) disposal site. The DRINK (DRIgg Near field Kinetic) model provides data regarding radionuclide concentrations in groundwater over a period of 100,000 years, which are used as input to assessment calculations for a groundwater pathway. The DRINK model also provides input to human intrusion and gaseous assessment calculations through simulation of the solid radionuclide inventory. These calculations are being used to support the Drigg post closure safety case. The DRINK model considers the coupled interaction of the effects of fluid flow, microbiology, corrosion, chemical reaction, sorption and radioactive decay. It represents the first direct use of a mechanistic reaction-transport model in risk assessment calculations
Identifying the causal mechanisms of the quiet eye
Scientists who have examined the gaze strategies employed by athletes have determined that longer quiet eye (QE) durations (QED) are characteristic of skilled compared to less-skilled performers. However, the cognitive mechanisms of the QE and, specifically, how the QED affects performance are not yet fully understood. We review research that has examined the functional mechanism underlying QE and discuss the neural networks that may be involved. We also highlight the limitations surrounding QE measurement and its definition and propose future research directions to address these shortcomings. Investigations into the behavioural and neural mechanisms of QE will aid the understanding of the perceptual and cognitive processes underlying expert performance and the factors that change as expertise develops
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