163,215 research outputs found
Chaos synchronization in gap-junction-coupled neurons
Depending on temperature the modified Hodgkin-Huxley (MHH) equations exhibit
a variety of dynamical behavior including intrinsic chaotic firing. We analyze
synchronization in a large ensemble of MHH neurons that are interconnected with
gap junctions. By evaluating tangential Lyapunov exponents we clarify whether
synchronous state of neurons is chaotic or periodic. Then, we evaluate
transversal Lyapunov exponents to elucidate if this synchronous state is stable
against infinitesimal perturbations. Our analysis elucidates that with weak gap
junctions, stability of synchronization of MHH neurons shows rather complicated
change with temperature. We, however, find that with strong gap junctions,
synchronous state is stable over the wide range of temperature irrespective of
whether synchronous state is chaotic or periodic. It turns out that strong gap
junctions realize the robust synchronization mechanism, which well explains
synchronization in interneurons in the real nervous system.Comment: Accepted for publication in Phys. Rev.
Fluctuation-dissipation theorem for chiral systems in non-equilibrium steady states
We consider a three-terminal system with a chiral edge channel connecting the
source and drain terminals. Charge can tunnel between the chiral edge and a
third terminal. The third terminal is maintained at a different temperature and
voltage than the source and drain. We prove a general relation for the current
noises detected in the drain and third terminal. It has the same structure as
an equilibrium fluctuation-dissipation relation with the nonlinear response in
place of the linear conductance. The result applies to a general chiral system
and can be useful for detecting "upstream" modes on quantum Hall edges.Comment: detailed proo
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COTS simulation package (CSP) interoperability - A solution to synchronous entity passing
In this paper we examine Commercial-Off-The- Shelf (COTS) Simulation Package (CSP) interoperability for one type of distributed simulation problem, namely synchronous entity passing. Synchronous entity passing is also referred to as the bounded buffer interoperability reference model. It deals with the case where for entities passed between models the receiving queue is bounded or the receiving workstation has limited capacity. This means the sending model must check the status of the receiving model before it can send entities. Correspondingly, the receiving model should update the status information dynamically when it changes. Similar to the work done on asynchronous entity passing, the High Level Architecture is chosen as the underlying standard to support reuse and interoperability. To simplify the integration of the CSP and the HLA, a middleware layer called DSManager is provided. Some new problems generated for synchronous entity passing are discussed and solutions are proposed together with a description of their implementation. Two sets of experiments are conducted to evaluate the solutions using a CSP Emulator (CSPE) which supports both standalone and distributed simulation
A unique distant submillimeter galaxy with an X-ray-obscured radio-luminous active galactic nucleus
We present a multiwavelength study of an atypical submillimeter galaxy in the
GOODS-North field, with the aim to understand its physical properties of
stellar and dust emission, as well as the central AGN activity. Although it is
shown that the source is likely an extremely dusty galaxy at high redshift, its
exact position of submillimeter emission is unknown. With the new NOEMA
interferometric imaging, we confirm that the source is a unique dusty galaxy.
It has no obvious counterpart in the optical and even NIR images observed with
HST at lambda~<1.4um. Photometric-redshift analyses from both stellar and dust
SED suggest it to likely be at z~>4, though a lower redshift at z~>3.1 cannot
be fully ruled out (at 90% confidence interval). Explaining its unusual
optical-to-NIR properties requires an old stellar population (~0.67 Gyr),
coexisting with a very dusty ongoing starburst component. The latter is
contributing to the FIR emission, with its rest-frame UV and optical light
being largely obscured along our line of sight. If the observed fluxes at the
rest-frame optical/NIR wavelengths were mainly contributed by old stars, a
total stellar mass of ~3.5x10^11Msun would be obtained. An X-ray spectral
analysis suggests that this galaxy harbors a heavily obscured AGN with
N_H=3.3x10^23 cm^-2 and an intrinsic 2-10 keV luminosity of L_X~2.6x10^44
erg/s, which places this object among distant type 2 quasars. The radio
emission of the source is extremely bright, which is an order of magnitude
higher than the star-formation-powered emission, making it one of the most
distant radio-luminous dusty galaxies. The combined characteristics of the
galaxy suggest that the source appears to have been caught in a rare but
critical transition stage in the evolution of submillimeter galaxies, where we
are witnessing the birth of a young AGN and possibly the earliest stage of its
jet formation and feedback.Comment: 13 pages in printer format, 10 figures, 1 table, accepted for
publication in the A&
Domain wall propagation through spin wave emission
We theoretically study field-induced domain wall (DW) motion in an
electrically insulating ferromagnet with hard- and easy-axis anisotropies. DWs
can propagate along a dissipationless wire through spin wave emission locked
into the known soliton velocity at low fields. In the presence of damping, the
mode appears before the Walker breakdown field for strong out-of-plane magnetic
anisotropy, and the usual Walker rigid-body propagation mode becomes unstable
when the field is between the maximal-DW-speed field and Walker breakdown
field.Comment: 4 pages, 4 figure
Dual-mode mechanical resonance of individual ZnO nanobelts
©2003 American Institute of Physics. The electronic version of this article is the complete one and can be found online at: http://link.aip.org/link/?APPLAB/82/4806/1DOI:10.1063/1.1587878The mechanical resonance of a single ZnO nanobelt, induced by an alternative electric field, was studied by in situ transmission electron microscopy. Due to the rectangular cross section of the nanobelt, two fundamental resonance modes have been observed corresponding to two orthogonal transverse vibration directions, showing the versatile applications of nanobelts as nanocantilevers and nanoresonators. The bending modulus of the ZnO nanobelts was measured to be ~52 GPa and the damping time constant of the resonance in a vacuum of 5×10–8 Torr was ~1.2 ms and quality factor Q = 500
Probing the topcolor-assisted technicolor model via the single t-quark production at Hadron colliders
In this paper, we systematically study the contribution of the TC2 model to
the single t-quark production at the Hadron colliders, specially at the LHC.
The TC2 model can contribute to the cross section of the single t-quark
production in two different ways. First, the existence of the top-pions and
top-higgs can modify the coupling via their loop contributions, and such
modification can cause the correction to the cross sections of all three
production modes. Our study shows that this kind of correction is negative and
very small in all cases. Thus it is difficult to observe such correction even
at the LHC. On the other hand, there exist the tree-level FC couplings in the
TC2 model which can also contribute to the cross sections of the and
production processes. The resonant effect can greatly enhance the
cross sections of the and productions. The first evidence of
the single t-quark production has been reported by the collaboration and
the measured cross section for the single t-quark production of
is compatible at the 10% level with the
standard model prediction. Because the light top-pion can make great
contribution to the production, the top-pion mass should be very
large in order to make the predicted cross section in the TC2 model be
consistent with the Tevatron experiments. More detailed information about the
top-pion mass and the FC couplings in the TC2 model should be obtained with the
running of the LHC.Comment: 30 pages, 3 tables, 10 figure
From Bardeen-boson stars to black holes without event horizon
In a talk given in 2013, S. Hawking conjectured that the event horizon of
black holes does not exist and suggested redefining black holes as bound states
of the gravitational field. Inspired by this idea, we investigated the coupling
of the Bardeen action and a complex scalar field model. Numerically, we
obtained a class of boson stars solutions with the magnetic monopole charge
. When the constant exceeds a certain threshold, we observed that as the
frequency approaches zero, a critical position emerges where the scalar
field concentrates within its interior. Outside this critical position, these
boson star solutions tend to infinitely approach what is known as an extreme
black hole. However, there is no event horizon present. While our results are
model-dependent and their generality remains uncertain, they align well with
Hawking's conjecture that real, regular black holes do not have an event
horizon and provided valuable insights into the understanding and development
of concepts such as fuzzballs, firewalls and black hole soft hairs.Comment: 10 pages, 3 figure
Effect of feedback on the control of a two-level dissipative quantum system
We show that it is possible to modify the stationary state by a feedback
control in a two-level dissipative quantum system. Based on the geometric
control theory, we also analyze the effect of the feedback on the time-optimal
control in the dissipative system governed by the Lindblad master equation.
These effects are reflected in the function and
that characterize the optimal trajectories, as well as the
switching function and which characterize the switching
point in time for the time-optimal trajectory.Comment: 5 pages, 5 figure
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