A note on the existence of unique equivalent martingale measures in a Markovian setting

Simple sufficient conditions for the existence of a unique equivalent martingale measure are provided. Furthermore, these conditions give us a handle on situations where an equivalent martingale measure cannot exist. The existence of a unique equivalent martingale measure is of relevance to problems in mathematical finance. Two examples of models for which the question of existence was unresolved are studied. By means of our results existence of a unique equivalent measure up to an explosion time is proved.     

Skill Loss, Ranking of Job Applicants and the Dynamics of Unemployment

Abstract. This paper investigates the consequences of skill loss as a result of unemployment in an efficiency wage model with turnover costs and on-the-job search. Firms are unable to differentiate wages and therefore prefer to hire employed searchers or unemployed workers who have not lost human capital. It is shown that if some fundamental factor in the economy changes, this will result in a lengthy adjustment process with substantial long-run unemployment effects. Moreover, the model is capable of generating persistence, but the amount depends on the duration of the shock itself.     

Golden cages for showy birds: Optimal switching costs in labor contracts

Under what circumstances do workers sign contracts with high quitting penalties? Our answer points to market transparency. When the worker's performance is privately observed by the incumbent firm, alternative employers face an adverse selection problem. As a result, efficient separations can only take place through involuntary layoffs and there is no role for quitting fees. In contrast, when performance is public, quitting fees are useful devices to appropriate the surplus from workers’ reallocation. Separations are amicable and take the form of quitting after downwardly renegotiating the fees. Qualitative features of contracts are independent of the distribution of ex-post bargaining power. The impact of switching costs on total welfare and its distribution depends on the degree of market transparency and the ex-ante distribution of market power.     

Forms of Foreign Investment Liberalization and Risk in Emerging Stock Markets

I examine the effect of different forms of foreign investment liberalization on risk in emerging equity markets, including international cross-listings and closed-end country funds, and in the domestic equity market as foreign investment restrictions are eliminated. I find that in Latin American markets volatility declines significantly with different forms of foreign investment liberalization, and in Asian markets volatility does not increase significantly. Volatility is driven by domestic factors in South America, but the transmission of volatility from the United States to Mexico increases after liberalization. The market risk exposure increases in Argentina after liberalization, in Chile with an index of American Depositary Receipts, and in Thailand with greater foreign ownership, reducing the diversification benefits of these markets.     

Equity‐Based Compensation for Employees: Firm Performance and Determinants

I examine the effect of employee equity‐based compensation (EBC) on firm performance and the determinants of EBC. Using two samples, I find that firms have come to rely more heavily on EBC than in the past. For both samples, I document a significant, positive relation between Tobin's q and the percentage of employee compensation that is equity based. For accounting returns, I find a positive relation with the earlier sample. However, for the later sample I find that greater use of EBC leads to lower levels of future accounting returns. I also find that the determinants of the proportion of EBC are different between the two samples.     

Demographic and Economic Pressure on Emigration out of Africa*

Two of the main forces driving European emigration in the late nineteenth century were real wage gaps between sending and receiving regions and demographic booms in the low‐wage sending regions. Our new estimates of net migration for the countries of sub‐Saharan Africa show that exactly the same forces driving African across‐border migration are at work today. The results suggest that rapid growth in the cohort of potential young emigrants, population pressure on the resource base, and slow economic growth are likely to intensify the pressure for migration out of Africa and into high‐wage OECD countries over the next two decades.     

Markets and pro-poor agricultural growth: insights from livelihood and informal rural economy models in Malawi

This article presents the development of a set of programming models describing the major features of different rural livelihoods and of the informal rural economy they together make up in Malawi. The models allow for differentiated responses by different household types to change and for the partial equilibrium effects of consequent supply, demand, and price adjustments in labor and grain markets. The models provide insights into the relations between own‐farm and nonown‐farm activities in different households' livelihoods and in the informal rural economy as a whole, and are used to investigate possible impacts of increasing cash crop prices and of a more open rural economy. Impacts of these changes on the poor are found to be critically dependent upon supply and demand elasticities in labor and grain markets, but the poor could potentially suffer significant losses from increased openness of the local economy leading to increased expenditure by less poor households on imported goods and services.     

Fertility,Taxation and Family Policy*

Historically, there is clear evidence of an inverse relationship between female labour supply and fertility. However, the relationship across countries is now positive. Countries like Germany and Italy, with the lowest fertility, also have the lowest female participation rates. This paper analyses the extent to which this can be explained by public policy, in particular taxation and the system of child support. The results suggest that countries which have individual rather than joint taxation, and which support families through child care facilities rather than child payments, are likely to have both higher female labour supply and higher fertility.     

Teams,Teamwork and Absence*

We argue that firms with interdependent worker productivity, team production, have a higher cost of absence and, as a consequence, spend additional resources on monitoring absence. As a result, firms with team production should have lower absence rates. We estimate the determinants of absence for blue‐collar workers using a sample of German manufacturing establishments. Workplace teams are used as a proxy for team production. The estimates reveal that firms with teams have lower absence rates, as do smaller establishments. The size effect, however, is unique to establishments with teams, which fits prior theoretical work that has not been previously tested.     

科技英语中数量增减的译法

本文系统地归纳了在科技文献中常见的涉及到倍数增减的结构及其表达方式