1,571 research outputs found
Effects of crowding and attention on high-levels of motion processing and motion adaptation
The motion after-effect (MAE) persists in crowding conditions, i.e., when the adaptation direction cannot be reliably perceived. The MAE originating from complex moving patterns spreads into non-adapted sectors of a multi-sector adapting display (i.e., phantom MAE). In the present study we used global rotating patterns to measure the strength of the conventional and phantom MAEs in crowded and non-crowded conditions, and when attention was directed to the adapting stimulus and when it was diverted away from the adapting stimulus. The results show that: (i) the phantom MAE is weaker than the conventional MAE, for both non-crowded and crowded conditions, and when attention was focused on the adapting stimulus and when it was diverted from it, (ii) conventional and phantom MAEs in the crowded condition are weaker than in the non-crowded condition. Analysis conducted to assess the effect of crowding on high-level of motion adaptation suggests that crowding is likely to affect the awareness of the adapting stimulus rather than degrading its sensory representation, (iii) for high-level of motion processing the attentional manipulation does not affect the strength of either conventional or phantom MAEs, neither in the non-crowded nor in the crowded conditions. These results suggest that high-level MAEs do not depend on attention and that at high-level of motion adaptation the effects of crowding are not modulated by attention
The strange quark condensate in the nucleon in 2+1 flavor QCD
We calculate the "strange quark content of the nucleon", ,
which is important for interpreting the results of some dark matter detection
experiments. The method is to evaluate quark-line disconnected correlations on
the MILC lattice ensembles, which include the effects of dynamical strange
quarks. After continuum and chiral extrapolations, the result is <N |s s_bar
|N> = 0.69 +- 0.07(statistical) +- 0.09(systematic), in the modified minimal
subtraction scheme (2 GeV), or for the renormalization scheme invariant form,
m_s partial{M_N}/partial{m_s} = 59(6)(8) MeV.Comment: Added figures and references, especially for fit range choice. Other
changes for clarity. Version to appear in publicatio
Focus Point Supersymmetry Redux
Recent results from Higgs boson and supersymmetry searches at the Large
Hadron Collider provide strong new motivations for supersymmetric theories with
heavy superpartners. We reconsider focus point supersymmetry (FP SUSY), in
which all squarks and sleptons may have multi-TeV masses without introducing
fine-tuning in the weak scale with respect to variations in the fundamental
SUSY-breaking parameters. We examine both FP SUSY and its familiar special
case, the FP region of mSUGRA/CMSSM, and show that they are beautifully
consistent with all particle, astroparticle, and cosmological data, including
Higgs boson mass limits, null results from SUSY searches, electric dipole
moments, b -> s gamma, B_s -> mu^+ mu^-, the thermal relic density of
neutralinos, and dark matter searches. The observed deviation of the muon's
anomalous magnetic moment from its standard model value may also be explained
in FP SUSY, although not in the FP region of mSUGRA/CMSSM. In light of recent
data, we advocate refined searches for FP SUSY and related scenarios with heavy
squarks and sleptons, and we present a simplified parameter space to aid such
analyses.Comment: v3: 20 pages, 20 figures, minor numerical error in relic density
calculation corrected, fixed contours in figure
The Contribution of the Light Quark Condensate to the Pion-Nucleon Sigma Term
There has been a discrepancy between values of the pion-nucleon sigma term
extracted by two different methods for many years. Analysis of recent high
precision pion-nucleon data has widened the gap between the two determinations.
It is argued that the two extractions correspond to different quantities and
that the difference between them can be understood and calculated.Comment: Modern Physics Letters A (in press
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