Central limit theorems and uniform laws of large numbers for arrays of random fields

Over the last decades, spatial-interaction models have been increasingly used in economics. However, the development of a sufficiently general asymptotic theory for nonlinear spatial models has been hampered by a lack of relevant central limit theorems (CLTs), uniform laws of large numbers (ULLNs) and pointwise laws of large numbers (LLNs). These limit theorems form the essential building blocks towards developing the asymptotic theory of M-estimators, including maximum likelihood and generalized method of moments estimators. The paper establishes a CLT, ULLN, and LLN for spatial processes or random fields that should be applicable to a broad range of data processes.     

Good timing: The economics of optimal stopping

This paper presents an economic interpretation of the optimal “stopping” of perpetual project opportunities under both certainty and uncertainty. Prior to stopping, the expected rate of return from delay exceeds the rate of interest. The expected rate of return from delay is the sum of the expected rate of change in project value and the expected rate of change in the option premium associated with waiting. At stopping the expected rate of return from delay has fallen to the rate of interest. Viewing stopping in this way unifies the theoretical and practical insights of the theory of stopping under certainty and uncertainty.     

C2C交易中的消费者购物心理分析

C2C电子商务就是消费者与消费者之间的电子商务,简单的说就是消费者通过网络将本身提供的服务或产品与其他消费者进行交易。本文在分析C2C市场现状的基础上,对消费者的购物心理进行了探析,提出了对卖家的指导性建议。     

Premia for correlated default risk

Using data on corporate default experience in the U.S. and market rates of CDX index and tranche swaps of various maturities, we estimate reduced-form models of correlated default timing in the CDX High Yield and Investment Grade portfolios under actual and risk-neutral probabilities. The striking contrast between the estimated processes followed by the actual and risk-neutral arrival intensities of defaults, and between the parameters governing the actual and risk-neutral dynamics of the risk-neutral intensities, indicates the presence of substantial default risk premia in CDX swap market rates. The effects of risk premia on swap rates covary strongly across maturities, and depend on general stock market volatility and several measures of credit spreads. Large moves in the effects of these premia on swap rates have natural interpretations in terms of economic and financial market developments during the sample period, April 2004 to October 2007. Our results suggest that a large portion of the movements in CDX swap market rates observed during the sample period may be caused by changing attitudes toward correlated default risk rather than changes in the economic factors affecting the actual risk of clustered defaults, which ultimately governs swap payoffs.     

空间信息传输中的多天线技术综述

近年来,空间信息传输中的多天线技术得到了广泛关注和大量研究。首先介绍了多天线技术的信息论基础和演进过程;然后综述了多天线通信和雷达技术的研究进展,包括多输入多输出(Multiple-Input Multiple-Output,MIMO)卫星通信技术、深空天线组阵技术、空间多维协同传输理论与技术、MIMO雷达技术和分布式孔径相参合成雷达技术,分析了其中的关键技术及未来可研究的方向;最后,总结了多天线技术在航天测控领域应用的优势,展望了基于多天线的测控技术。     

Stock markets’ bubbles burst and volatility spillovers in agricultural commodity markets

Our paper focuses on commodity financialization and the gradual integration between commodity and financial markets, investigating to what extent shocks in stock markets impact commodity price volatility, and the persistency of the phenomenon. To this end, we estimate Volatility Impulse Response Function from stock markets to agricultural commodity markets over a symmetric window before and after two of the most important bubble bursts since the new millennium, the 2000 dot.com bubble and the 2008 financial crises. Results highlight that volatility spillover increased significantly after the 2008 financial crises, signalling a rising interconnection between financial and agricultural commodity markets.