在低维空间实现的基于MP的图像稀疏分解

研究利用Matching Pursuit(MP)方法实现的图像稀疏分解算法，针对其中关键难题，提出利用在低维空间的搜索实现高维空间的搜索的快速方法。算法的有效性为实验结果所证实。     

The Macroeconomic Consequences of Reciprocity in Labor Relations*

We develop and analyze a structural model of efficiency wages founded on reciprocity. Workers are assumed to face an explicit trade‐off between the disutility of providing effort and the psychological benefit of reciprocating the gift of a wage offer above some reference level. The model provides a rationale for rent sharing—a feature that is very much present in the data but absent from previous formulations of the efficiency wage hypothesis. This firm‐internal perspective on efficiency wages has potentially important macroeconomic consequences: rent‐sharing considerations promote wage rigidity, internal amplification and differential responses to technology and demand shocks.     

The information content of implied volatility in agricultural commodity markets

In this article we compare the incremental information content of lagged implied volatility to GARCH models of conditional volatility for a collection of agricultural commodities traded on the New York Board of Trade. We also assess the relevance of the additional information provided by the implied volatility in a risk management framework. It is first shown that past squared returns only marginally improve the information content provided by the lagged implied volatility. Secondly, value‐at‐risk (VaR) models that rely exclusively on lagged implied volatility perform as well as VaR models where the conditional variance is modelled according to GARCH type processes. These results indicate that the implied volatility for options on futures contracts in agricultural commodity markets provides relevant volatility information that can be used as an input to VaR models. © 2003 Wiley Periodicals, Inc. Jrl Fut Mark 23:441–454, 2003     

HYPERINFLATIONS: THEIR ORIGINS, DEVELOPMENT AND TERMINATION

Abstract. This paper summarizes and critically surveys research on hyperinflation. Appraisal and review of the literature considers the origins, development, termination, and the lessons to be learned from hyperinflations. The historical evidence as well as the econometric evidence is analyzed. It is concluded that while the lessons to be learned from such episodes perhaps have been overstated a number of useful implications may be derived from studying hyperinflations, such as an understanding of the forces which link monetary and fiscal policies to inflation, and policy makers'role in influencing individuals'expectations.     

Long-term care social insurance: How to avoid big losses?

Long-term care (LTC) needs are expected to rapidly increase in the next decades, and at the same time, the main provider of LTC, namely the family, is stalling. This calls for more involvement of the state that today covers <20% of these needs and most often in an inconsistent way. Besides the need to help the dependent poor, there is a mounting concern in the middle class that a number of dependent people are incurring costs that could force them to sell all their assets. In this paper, we study the design of a social insurance program that meets this concern. Following Arrow (Am Econ Rev 53:941–973, 1963), we suggest a policy that is characterized by complete insurance above a deductible amount.     

Investment and dynamic DEA

A dynamic version of data envelopment analysis (DEA) is developed in the present paper. Our model introduces investment in traditional DEA and imposes intertemporal cost minimization. Adding an intertemporal adjustment constraint into the cost minimization problem, we derive the relation between the DEA variables of the variable cost function and those of the primary production frontiers’ coefficients. The augmented DEA model can be solved using standard linear programming. This dynamic framework enables computing the production frontiers, measuring the productive efficiencies and evaluating the potential economies all in the presence of adjustment costs.