8,277 research outputs found
Coupled effects of local movement and global interaction on contagion
By incorporating segregated spatial domain and individual-based linkage into
the SIS (susceptible-infected-susceptible) model, we investigate the coupled
effects of random walk and intragroup interaction on contagion. Compared with
the situation where only local movement or individual-based linkage exists, the
coexistence of them leads to a wider spread of infectious disease. The roles of
narrowing segregated spatial domain and reducing mobility in epidemic control
are checked, these two measures are found to be conducive to curbing the spread
of infectious disease. Considering heterogeneous time scales between local
movement and global interaction, a log-log relation between the change in the
number of infected individuals and the timescale is found. A theoretical
analysis indicates that the evolutionary dynamics in the present model is
related to the encounter probability and the encounter time. A functional
relation between the epidemic threshold and the ratio of shortcuts, and a
functional relation between the encounter time and the timescale are
found
GRB/GW association: Long-short GRB candidates, time-lag, measuring gravitational wave velocity and testing Einstein's equivalence principle
Short-duration gamma-ray bursts (SGRBs) are widely believed to be powered by
the mergers of compact binaries, such as binary neutron stars or possibly
neutron star-black hole binaries. Though the prospect of detecting SGRBs with
gravitational wave (GW) signals by the advanced Laser Interferometer
Gravitational-Wave Observatory (LIGO)/VIRGO network is promising, no known SGRB
has been found within the expected advanced LIGO/VIRGO sensitivity range for
binary neutron star systems. We find, however, that the two long-short GRBs
(GRB 060505 and GRB 060614) may be within the horizon of advanced GW detectors.
In the upcoming era of GW astronomy, the merger origin of some long-short GRBs,
as favored by the macronova signature displayed in GRB 060614, can be
unambiguously tested. The model-dependent time lags between the merger and the
onset of the prompt emission of the GRB are estimated. The comparison of such
time lags between model predictions and the real data expected in the era of
the GW astronomy would be helpful in revealing the physical processes taking
place at the central engine (including the launch of the relativistic outflow,
the emergence of the outflow from the dense material ejected during the merger,
and the radiation of gamma rays). We also show that the speed of GWs, with or
without a simultaneous test of Einstein's equivalence principle, can be
directly measured to an accuracy of or
even better in the advanced LIGO/VIRGO era. The Astrophysical Journal, VolumeComment: 12 pages, 3 figures, published in The Astrophysical Journa
- …