87 research outputs found
"Dark energy" in the Local Void
The unexpected discovery of the accelerated cosmic expansion in 1998 has
filled the Universe with the embarrassing presence of an unidentified "dark
energy", or cosmological constant, devoid of any physical meaning. While this
standard cosmology seems to work well at the global level, improved knowledge
of the kinematics and other properties of our extragalactic neighborhood
indicates the need for a better theory. We investigate whether the recently
suggested repulsive-gravity scenario can account for some of the features that
are unexplained by the standard model. Through simple dynamical considerations,
we find that the Local Void could host an amount of antimatter
() roughly equivalent to the mass of a typical
supercluster, thus restoring the matter-antimatter symmetry. The antigravity
field produced by this "dark repulsor" can explain the anomalous motion of the
Local Sheet away from the Local Void, as well as several other properties of
nearby galaxies that seem to require void evacuation and structure formation
much faster than expected from the standard model. At the global cosmological
level, gravitational repulsion from antimatter hidden in voids can provide more
than enough potential energy to drive both the cosmic expansion and its
acceleration, with no need for an initial "explosion" and dark energy.
Moreover, the discrete distribution of these dark repulsors, in contrast to the
uniformly permeating dark energy, can also explain dark flows and other
recently observed excessive inhomogeneities and anisotropies of the Universe.Comment: 6 pages, accepted as a Letter to the Editor by Astrophysics and Space
Scienc
Effects of Large CP-violating Soft Phases on Supersymmetric Electroweak Baryogenesis
We revisit the results of recent electroweak baryogenesis calculations and
include all allowed large CP-violating supersymmetric phases. If the phases are
large, the resulting baryon asymmetry can be considerably larger than the
observed value . Much of the asymmetry must
therefore be washed out, and we argue that the upper bound on the light Higgs
mass is larger than the value reported in previous work.Comment: 15 pages, 3 figure
Why do sanctions need time to work? Adjustment, learning and anticipation
Economists disagree on the influence of time on the probability of success of economic sanctions. Some argue that it takes time to convince the sanction target. Others stress that economic adjustment will reduce incentives to comply. We seek to reconcile these different literatures, modelling the target's decision to comply as a function of both (anticipatory) economic adjustment and Bayesian learning. We show that sanctions which do not work instantaneously (ie there is neither political compliance nor economic adjustment) can work in the long run, but only if the learning effect dominates the adjustment effect. A sufficient condition for ultimate compliance is that (potential) sanction damage that cannot be avoided by adjustment in the long run exceeds the yield of misconduct
Attitudes toward sport psychology consulting of adult athletes from the United States, United Kingdom, and Germany
The purpose of this study was to explore attitudes about sport psychology consulting of athletes living in the United States, United Kingdom and Germany. The Sport Psychology Attitudes - Revised form (SPA-R; Martin, Kellmann, Lavallee, & Page, 2002) was administered to 404 athletes from the United States, 147 athletes from the United Kingdom, and 260 athletes from Germany. A 2 (Gender) x 3 (Nationality: American, British and German) x 2 (Type of Sport: physical contact and physical non-contact) MANCOVA was conducted with past sport psychology conducting experience as a covariant and attitudes about sport psychology as dependent variables. Follow-up univariate and discriminant function analyses were then performed to identify the attitiudes that maximized differences related to gender, nationality, and type of sport. Results revealed that attitudes about sport psychology services might be influenced by gender, nationality, and type of sport. Sport psychology practitioners must be sensitive to how personal characteristics and past experiences influence athletes' expectations and attitudes toward sport psychology consulting to improve the services they offer
Tomato stem trichomes and dispersal success ofPhytoseiulus persimilis relative to its preyTetranychus urticae
Tomato varieties used at present for commercial production in Dutch glasshouses have a high density of glandular trichomes on the stem, but a very low density on the leaves. The two-spotted spider mite, Tetranychus urticae Koch, and the predatory mite, Phytoseiulus persimilis Athias-Henriot, usually disperse from leaf to leaf via the stem, thereby incurring high risks of entrapment (and death) in the exudate of the glandular trichomes. These risks have been quantified on the tomato cv. 'Turbo' and an accession of Lycopersicon peruvianum almost free of glandular trichomes. The possible consequences for biological control are discussed and new perspectives for predator release strategies and for plant breeding are considered. © 1987 Elsevier Science Publishers B.V
Narrowband Searches for Continuous and Long-duration Transient Gravitational Waves from Known Pulsars in the LIGO-Virgo Third Observing Run
Isolated neutron stars that are asymmetric with respect to their spin axis are possible sources of detectable continuous gravitational waves. This paper presents a fully coherent search for such signals from eighteen pulsars in data from LIGO and Virgo's third observing run (O3). For known pulsars, efficient and sensitive matched-filter searches can be carried out if one assumes the gravitational radiation is phase-locked to the electromagnetic emission. In the search presented here, we relax this assumption and allow both the frequency and the time derivative of the frequency of the gravitational waves to vary in a small range around those inferred from electromagnetic observations. We find no evidence for continuous gravitational waves, and set upper limits on the strain amplitude for each target. These limits are more constraining for seven of the targets than the spin-down limit defined by ascribing all rotational energy loss to gravitational radiation. In an additional search, we look in O3 data for long-duration (hours-months) transient gravitational waves in the aftermath of pulsar glitches for six targets with a total of nine glitches. We report two marginal outliers from this search, but find no clear evidence for such emission either. The resulting duration-dependent strain upper limits do not surpass indirect energy constraints for any of these targets. © 2022. The Author(s). Published by the American Astronomical Society
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