15,818 research outputs found
Counterterms in Gravity in the Light-Front Formulation and a D=2 Conformal-like Symmetry in Gravity
In this paper we discuss gravity in the light-front formulation (light-cone
gauge) and show how possible counterterms arise. We find that Poincare
invariance is not enough to find the three-point counterterms uniquely.
Higher-spin fields can intrude and mimic three-point higher derivative gravity
terms. To select the correct term we have to use the remaining
reparametrization invariance that exists after the gauge choice. We finally
sketch how the corresponding programme for N=8 Supergravity should work.Comment: 26 pages, references added, published versio
Implication of Cotton Price Behavior on Market Integration
The cotton market in China is highly interactive with international markets, especially, the US market. The prices in these two markets can reveal important market relations. Investigating the data of futures prices from the New York Board of Trade (NYBOT) and the Zhengzhou Commodity Exchange (CZCE) using several time series methods, we find a long-run cointegration relationship between these I(1) series. Furthermore, a bi-directional Granger Causality between these two futures markets is detected with Generalized Autoregressive Conditional Heteroskedasticity (GARCH) error specifications. We also find the relationship is impacted by the Chinese exchange rate policy change in the 2005.cotton futures prices, cointegration, granger causality test, AR-GARCH., Agricultural Finance,
Trade and Integration of the US and China’s Cotton Markets
The cotton market in China is highly interactive with international markets, especially, the US market. The prices in these two markets can reveal important market relations. Investigating the data of futures prices from the New York Board of Trade (NYBOT) and the Zhengzhou Commodity Exchange (CZCE) using several time series methods, we find a long-run cointegration relationship between these I(1) series. Furthermore, a bi-directional Granger Causality between these two futures markets is detected with Generalized Autoregressive Conditional Heteroskedasticity (GARCH) error specifications. We also find the relationship is impacted by the Chinese exchange rate policy change in the 2005.cotton futures prices, cointegration, granger causality test, AR-GARCH, Agricultural Finance, Demand and Price Analysis, International Relations/Trade,
Stochastic Reinforcement Learning
In reinforcement learning episodes, the rewards and punishments are often
non-deterministic, and there are invariably stochastic elements governing the
underlying situation. Such stochastic elements are often numerous and cannot be
known in advance, and they have a tendency to obscure the underlying rewards
and punishments patterns. Indeed, if stochastic elements were absent, the same
outcome would occur every time and the learning problems involved could be
greatly simplified. In addition, in most practical situations, the cost of an
observation to receive either a reward or punishment can be significant, and
one would wish to arrive at the correct learning conclusion by incurring
minimum cost. In this paper, we present a stochastic approach to reinforcement
learning which explicitly models the variability present in the learning
environment and the cost of observation. Criteria and rules for learning
success are quantitatively analyzed, and probabilities of exceeding the
observation cost bounds are also obtained.Comment: AIKE 201
Non-monotonic temperature dependent transport in graphene grown by Chemical Vapor Deposition
Temperature-dependent resistivity of graphene grown by chemical vapor
deposition (CVD) is investigated. We observe in low mobility CVD graphene
device a strong insulating behavior at low temperatures and a metallic behavior
at high temperatures manifesting a non-monotonic in the temperature dependent
resistivity.This feature is strongly affected by carrier density modulation. To
understand this anomalous temperature dependence, we introduce thermal
activation of charge carriers in electron-hole puddles induced by randomly
distributed charged impurities. Observed temperature evolution of resistivity
is then understood from the competition among thermal activation of charge
carriers, temperature-dependent screening and phonon scattering effects. Our
results imply that the transport property of transferred CVD-grown graphene is
strongly influenced by the details of the environmentComment: 7 pages, 3 figure
Muon-Spin-Rotation Measurements of the Penetration Depth in the Infinite-Layer Electron-Doped Cuprate Superconductor Sr0.9La0.1CuO2
Muon spin rotation (mSR) measurements of the in-plane penetration depth
lambda_ab have been performed in the electron-doped infinite layer high-Tc
superconductor (HTS) Sr0.9La0.1CuO2. Absence of the magnetic rare-earth ions in
this compound allowed to measure for the first time the absolute value of
lambda_ab(0) in electron-doped HTS using mSR. We found lambda_ab(0)=116(2) nm.
The zero-temperature depolarization rate sigma(0)?1/lambda_ab(0)^2=4.6(1) MHz
is more than four times higher than expected from the Uemura line. Therefore
this electron-doped HTS does not follow the Uemura relation found for
hole-doped HTS.Comment: to be published in Physical Review Letter
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