4,327 research outputs found
Empirical properties of inter-cancellation durations in the Chinese stock market
Order cancellation process plays a crucial role in the dynamics of price
formation in order-driven stock markets and is important in the construction
and validation of computational finance models. Based on the order flow data of
18 liquid stocks traded on the Shenzhen Stock Exchange in 2003, we investigate
the empirical statistical properties of inter-cancellation durations in units
of events defined as the waiting times between two consecutive cancellations.
The inter-cancellation durations for both buy and sell orders of all the stocks
favor a -exponential distribution when the maximum likelihood estimation
method is adopted; In contrast, both cancelled buy orders of 6 stocks and
cancelled sell orders of 3 stocks prefer Weibull distribution when the
nonlinear least-square estimation is used. Applying detrended fluctuation
analysis (DFA), centered detrending moving average (CDMA) and multifractal
detrended fluctuation analysis (MF-DFA) methods, we unveil that the
inter-cancellation duration time series process long memory and multifractal
nature for both buy and sell cancellations of all the stocks. Our findings show
that order cancellation processes exhibit long-range correlated bursty
behaviors and are thus not Poissonian.Comment: 14 pages, 7 figures and 5 table
Optical spin pumping induced pseudo-magnetic field in two dimensional heterostructures
Two dimensional heterostructures are likely to provide new avenues for the
manipulation of magnetization that is crucial for spintronics or
magnetoelectronics. Here, we demonstrate that optical spin pumping can generate
a large effective magnetic field in two dimensional MoSe2/WSe2
heterostructures. We determine the strength of the generated field by
polarization-resolved measurement of the interlayer exciton photoluminescence
spectrum: the measured splitting exceeding 10 milli-electron volts (meV)
between the emission originating from the two valleys corresponds to an
effective magnetic field of ~ 30 T. The strength of this optically induced
field can be controlled by the excitation light polarization. Our finding opens
up new possibilities for optically controlled spintronic devices based on van
der Waals heterostructures
5,11,17,23-Tetra-tert-butyl-25,26,27,28-tetrapropynyloxy-2,8,14,20-tetrathiacalix[4]arene
The title compound [systematic name: 5,11,17,23-tetra-tert-butyl-25,26,27,28-tetrapropynyloxy-2,8,14,20-tetrathiacalix[4]arene], C52H56O4S4, is an alkylated product bearing four propyne groups at the lower rim of a 5,11,17,23-tetra-tert-butyl-tetrathiacalix[4]arene. The molecule is located on a crystallographic twofold rotation axis, running through two S atoms and perpendicular to the long axis of the molecule. The four propyne groups, located in an alternate fashion above and below the mean plane of the four S atoms, are almost parallel to the calixarene long axis. The dihedral angle between the two crystallographically independent benzene rings is 86.77 (14)°. Two tert-butyl groups are disordered over two positions with site occupancies of 0.59 (2) and 0.41 (2)
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