4,688 research outputs found
Investigations of the g factors and local structure for orthorhombic Cu^{2+}(1) site in fresh PrBa_{2}Cu_{3}O_{6+x} powders
The electron paramagnetic resonance (EPR) g factors g_x, g_y and g_z of the
orthorhombic Cu^{2+}(1) site in fresh PrBa_{2}Cu_{3}O_{6+x} powders are
theoretically investigated using the perturbation formulas of the g factors for
a 3d^9 ion under orthorhombically elongated octahedra. The local orthorhombic
distortion around the Cu^{2+}(1) site due to the Jahn-Teller effect is
described by the orthorhombic field parameters from the superposition model.
The [CuO6]^{10-} complex is found to experience an axial elongation of about
0.04 {\AA} along c axis and the relative bond length variation of about 0.09
{\AA} along a and b axes of the Jahn-Teller nature. The theoretical results of
the g factors based on the above local structure are in reasonable agreement
with the experimental data.Comment: 6 pages, 1 figur
Remarks on the stability of the Navier-Stokes equations supplemented with stress-free boundary conditions
The purpose of this note is to analyze the long term stability of the
Navier-Stokes equations supplemented with the Coriolis force and the
stress-free boundary condition. It is shown that, if the flow domain is
axisymmetric, spurious stability behaviors can occur depending whether the
Coriolis force is active or not
Distinguishing technicolor models via tt-bar productions at polarized photon colliders
We study top quark pair productions at a polarized photon collider from an
e(+)e(-) linear collider (LC) in various improved technicolor model, namely,
the one-family walking technicolor model, the top-color-assisted technicolor
model, and the top-color-assisted multiscale technicolor model. Recent
constraint on the top-pion mass from the precision data of R(b) is considered.
It is shown that, considering only the statistical errors, a polarized photon
collider from a 500 GeV LC with an integrated luminosity of 500 inverse fb is
sufficient for distinguishing the three improved technicolor models
experimentally.Comment: 7 pages, 6 figures, to appear in Physical Review
Complex Behavior in Simple Models of Biological Coevolution
We explore the complex dynamical behavior of simple predator-prey models of
biological coevolution that account for interspecific and intraspecific
competition for resources, as well as adaptive foraging behavior. In long
kinetic Monte Carlo simulations of these models we find quite robust 1/f-like
noise in species diversity and population sizes, as well as power-law
distributions for the lifetimes of individual species and the durations of
quiet periods of relative evolutionary stasis. In one model, based on the
Holling Type II functional response, adaptive foraging produces a metastable
low-diversity phase and a stable high-diversity phase.Comment: 8 pages, 5 figure
Selective Communication for Cooperative Perception in End-to-End Autonomous Driving
The reliability of current autonomous driving systems is often jeopardized in
situations when the vehicle's field-of-view is limited by nearby occluding
objects. To mitigate this problem, vehicle-to-vehicle communication to share
sensor information among multiple autonomous driving vehicles has been
proposed. However, to enable timely processing and use of shared sensor data,
it is necessary to constrain communication bandwidth, and prior work has done
so by restricting the number of other cooperative vehicles and randomly
selecting the subset of vehicles to exchange information with from all those
that are within communication range. Although simple and cost effective from a
communication perspective, this selection approach suffers from its
susceptibility to missing those vehicles that possess the perception
information most critical to navigation planning. Inspired by recent
multi-agent path finding research, we propose a novel selective communication
algorithm for cooperative perception to address this shortcoming. Implemented
with a lightweight perception network and a previously developed control
network, our algorithm is shown to produce higher success rates than a random
selection approach on previously studied safety-critical driving scenario
simulations, with minimal additional communication overhead.Comment: Scalable Autonomous Driving Workshop of IEEE International Conference
on Robotics and Automation (ICRA Workshop), 202
DAMA/NaI results
The DAMA/NaI set-up of the DAMA experiment has been operative during seven
annual cycles and has investigated several rare processes. In particular, it
has been realised in order to investigate the model independent annual
modulation signature for Dark Matter particles in the galactic halo. With the
total exposure collected in the seven annual cycles (107731 kg day) a model
independent evidence for the presence of a Dark Matter particle component in
the galactic halo has been pointed out at 6.3 sigma C.L.. Some of the many
possible corollary model dependent quests for the candidate particle have been
presented as well.Comment: Contributed paper to the Rencontres de Moriond "Electroweak
Interactions and Unified Theories", La Thuile, Aosta Valley, Italy, March
200
- …