1,254 research outputs found
Valley depolarization in monolayer WSe2
We have systematically examined the circular polarization of monolayer WSe2
at different temperature, excitation energy and exciton density. The valley
depolarization in WSe2 is experimentally confirmed to be governed by the
intervalley electron-hole exchange interaction. More importantly, a
non-monotonic dependence of valley circular polarization on the excitation
power density has been observed, providing the experimental evidence for the
non-monotonic dependence of exciton intervalley scattering rate on the excited
exciton density. The physical origination of our experimental observations has
been proposed, which is in analogy to the D'yakonov-Perel' mechanism that is
operative in conventional GaAs quantum well systems. Our experimental results
are fundamentally important for well understanding the valley psudospin
relaxation in atomically thin transition metal dichalcogenides
Accelerated Stochastic ADMM with Variance Reduction
Alternating Direction Method of Multipliers (ADMM) is a popular method in
solving Machine Learning problems. Stochastic ADMM was firstly proposed in
order to reduce the per iteration computational complexity, which is more
suitable for big data problems. Recently, variance reduction techniques have
been integrated with stochastic ADMM in order to get a fast convergence rate,
such as SAG-ADMM and SVRG-ADMM,but the convergence is still suboptimal w.r.t
the smoothness constant. In this paper, we propose a new accelerated stochastic
ADMM algorithm with variance reduction, which enjoys a faster convergence than
all the other stochastic ADMM algorithms. We theoretically analyze its
convergence rate and show its dependence on the smoothness constant is optimal.
We also empirically validate its effectiveness and show its priority over other
stochastic ADMM algorithms
TESTING FOR COMPLETE PASS-THROUGH OF EX ASS-THROUGH OF EXCHANGE RA ANGE RATE WITHOUT TRADE BARRIERS
The objective of this paper is to test whether the complete pass-through of exchange rate exists when there are almost no transaction costs and in the environment of competitive market. In general, the literature claims that the pass-through of exchange rate is incomplete due to imperfect market, i.e. the presence of transaction costs and imperfect competition. The quasi-experimental case of the food import to Hong Kong from Mainland China is considered in the analysis. The results show that the pass-through of the exchange rate of Chinese RMB against to US dollar to Hong Kong\u27s food import price is complete in long-run equilibrium. Besides, the short-run adjustment significantly contributes to correcting the deviation from the long-run pass-through effect. Moreover, the complete pass-through still exists after accounting for the effects of asymmetry and volatility. Therefore, this paper contributes to the literature by providing empirical evidence that the complete pass-through of exchange rate can exist in the real world
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