1,265 research outputs found
Impact of information cost and switching of trading strategies in an artificial stock market
This paper studies the switching of trading strategies and its effect on the
market volatility in a continuous double auction market. We describe the
behavior when some uninformed agents, who we call switchers, decide whether or
not to pay for information before they trade. By paying for the information
they behave as informed traders. First we verify that our model is able to
reproduce some of the stylized facts in real financial markets. Next we
consider the relationship between switching and the market volatility under
different structures of investors. We find that there exists a positive
relationship between the market volatility and the percentage of switchers. We
therefore conclude that the switchers are a destabilizing factor in the market.
However, for a given fixed percentage of switchers, the proportion of switchers
that decide to buy information at a given moment of time is negatively related
to the current market volatility. In other words, if more agents pay for
information to know the fundamental value at some time, the market volatility
will be lower. This is because the market price is closer to the fundamental
value due to information diffusion between switchers.Comment: 15 pages, 9 figures, Physica A, 201
A fast two-level Strang splitting method for multi-dimensional spatial fractional Allen-Cahn equations with discrete maximum principle
In this paper, we study the numerical solutions of the multi-dimensional
spatial fractional Allen-Cahn equations. After semi-discretization for the
spatial fractional Riesz derivative, a system of nonlinear ordinary
differential equations with Toeplitz structure is obtained. For the sake of
reducing the computational complexity, a two-level Strang splitting method is
proposed, where the Toeplitz matrix in the system is split into the sum of a
circulant matrix and a skew-circulant matrix. Therefore, the proposed method
can be quickly implemented by the fast Fourier transform, substituting to
calculate the expensive Toeplitz matrix exponential. Theoretically, the
discrete maximum principle of our method is unconditionally preserved.
Moreover, the analysis of error in the infinite norm with second-order accuracy
is conducted in both time and space. Finally, numerical tests are given to
corroborate our theoretical conclusions and the efficiency of the proposed
method
Nonlinearity in the Dark: Broadband Terahertz Generation with Extremely High Efficiency
Plasmonic metamaterials and metasurfaces offer new opportunities in
developing high performance terahertz emitters and detectors beyond the
limitations of conventional nonlinear materials. However, simple meta-atoms for
second-order nonlinear applications encounter fundamental trade-offs in the
necessary symmetry breaking and local-field enhancement due to radiation
damping that is inherent to the operating resonant mode and cannot be
controlled separately. Here we present a novel concept that eliminates this
restriction obstructing the improvement of terahertz generation efficiency in
nonlinear metasurfaces based on metallic nanoresonators. This is achieved by
combining a resonant dark-state metasurface, which locally drives nonlinear
nanoresonators in the near field, with a specific spatial symmetry that enables
destructive interference of the radiating linear moments of the nanoresonators,
and perfect absorption via simultaneous electric and magnetic critical coupling
of the pump radiation to the dark mode. Our proposal allows eliminating linear
radiation damping, while maintaining constructive interference and effective
radiation of the nonlinear components. We numerically demonstrate a giant
second-order nonlinear susceptibility around Hundred-Billionth m/V, a one order
improvement compared with the previously reported split-ring-resonator
metasurface, and correspondingly, a 2 orders of magnitude enhanced terahertz
energy extraction should be expected with our configuration under the same
conditions. Our study offers a paradigm of high efficiency tunable nonlinear
metadevices and paves the way to revolutionary terahertz technologies and
optoelectronic nanocircuitry.Comment: 6 pages, 4 figure
N-(3,4-Dichlorophenyl)thiourea
In the title compound, C7H6Cl2N2S, the benzene ring and the mean plane of the thiourea fragment [—N—C(=S)—N] make a dihedral angle of 66.77 (3)°. Intermolecular N—H⋯S and N—H⋯Cl hydrogen bonds link the molecules into a three-dimensional network
2-[4-(Benzyloxy)benzylidene]malononitrile
In the title molecule, C17H12N2O, the dihedral angle between the two benzene rings is 84.98 (10)°. The dicyanoethylene group is coplanar with the benzene ring to which it is bonded. No classic hydrogen bonds were found in the crystal
Study on the weak decay between two heavy baryons in the light-front quark model
In this work, we study the weak decay between two heavy baryons in the
light-front quark model where three-quark picture is employed for baryon. We
derive general form of transition amplitude of , and analyze two
specific cases of transitions: the weak decays of single heavy baryon
and the decays of double-charmed baryon
. We compute the hadronic form factors for
the transitions and apply them to study the decay widths of the semi-leptonic
and
non-leptonic .
Previously we studied the transition with the
quark-diquark picture of baryon in the light-front quark model. Here we revisit
this transition with three-quark picture of baryon. At the quark level, the
transition is induced by the
transition.The subsystem of the two unchanged light quarks which possesses
definite and same spin in initial and final state can be viewed as a spectator,
so the spectator approximation can be applied directly. For the weak decay of
doubly charmed baryon , a quark decays to a light quark , so
both the initial state and final state ( and the original
in initial state may be the same flavor quarks) which possess definite
spin are no longer spectators. A rearrangement of quarks for initial and final
states is adopted to isolate the unchanged subsystem which can be viewed
as the spectator approximately. Future measurements on these channels will
constrain the nonperturbative parameter in the wavefunctions and test the model
predictions.Comment: 20 pages, 6 figures and 10 table
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