302 research outputs found

    Private Information, Wage Bargaining and Employment Fluctuations

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    Shimer (2005) pointed out that although we have a satisfactory theory of why some workers are unemployed at any given time, we don?t know why the number of unemployed workers varies so much over time. The basic Mortensen-Pissarides (1994) model does not generate nearly enough volatility in unemployment, for plausible parameter values. This paper extends the Mortensen-Pissarides model to allow for informational rents. Productivity is subject to publicly observed aggregate shocks, and to idiosyncratic shocks that are seen only by the employer. It is shown that there is a unique equilibrium, provided that the idiosyncratic shocks are not too large. The main result is that small fluctuations in productivity that are privately observed by employers can give rise to a kind of wage stickiness in equilibrium, and the informational rents associated with this stickiness are sufficient to generate relatively large unemployment fluctuations.

    The Effect of Expected Income on Individual Migration Decisions

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    The paper develops a tractable econometric model of optimal migration, focusing on expected income as the main economic influence on migration. The model improves on previous work in two respects: it covers optimal sequences of location decisions (rather than a single once-for-all choice), and it allows for many alternative location choices. The model is estimated using panel data from the NLSY on white males with a high school education. Our main conclusion is that interstate migration decisions are influenced to a substantial extent by income prospects. The results suggest that the link between income and migration decisions is driven both by geographic differences in mean wages and by a tendency to move in search of a better locational match when the income realization in the current location is unfavorable.

    Optimal monetary impulse-response functions in a matching model

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    The effects on ex ante optima of a lag in seeing monetary realizations are studied using a matching model of money. The main new ingredient in the model is meetings in which producers have more information than consumers. A consequence is that increases in the amount of money that occur with small enough probability can have negative impact effects on output, because it is optimal to shut down trade in such low probability meetings rather than have lower output when high probability realizations occur. The information lag also produces prices that do not respond much to current monetary realizations.Money supply ; Prices ; Production (Economic theory)

    Optimal Monetary Impulse-Response Functions in a Matching Model

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    The effects on ex ante optima of a lag in seeing monetary realizations are studied using a matching model of money. The main new ingredient in the model is meetings in which producers have more information than consumers. A consequence is that increases in the amount of money that occur with small enough probability can have negative impact effects on output, because it is optimal to shut down trade in such low probability meetings rather than have lower output when high probability realizations occur. The information lag also produces prices that do not respond much to current monetary realizations.

    Coalition-Proof Trade and the Friedman Rule in the Lagos-Wright Model

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    The Lagos-Wright model -- a monetary model in which pairwise meetings alternate in time with a centralized meeting -- has been extensively analyzed, but always using particular trading protocols. Here, trading protocols are replaced by two alternative notions of implementability: one that allows only individual defections and one that also allows cooperative defections in meetings. It is shown that the first-best allocation is implementable under the stricter notion with- out taxation if people are sufficiently patient. And, if people are free to skip the centralized meeting, then lump-sum taxation used to pay interest on money does not enlarge the set of implementable allocations.

    Optimal Tariff Equilibria with Customs Unions

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    Skill uncertainty, skill accumulation, and occupational choice.

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    Abstract Workers entering the labor market are uncertain about their skill set. Standard human capital theory assumes workers have perfect information about their skills. In this paper, I argue that skill uncertainty can explain one type of worker moves that standard human capital theory cannot: moves between jobs where they perform different kinds of tasks. I consider workers who have a multi-dimensional bundle of labor market skills and begin their careers uncertain about their skill levels. I construct a model that links learning about skills to the tasks performed in jobs: the more intensely a job uses a particular skill, the more the workers learn about their true level of that skill. The model also contains a skill accumulation motive: as workers use a skill they gain additional amounts of it. A simplified version of the model suggests that if skill uncertainty were the dominant force workers would switch between jobs that use skills in different ratios but similar total levels. On the other hand, if skill accumulation were the dominant force they would switch between jobs that use similar ratios of skills but higher total levels. Linking data on workers from the National Longitudinal Study of Youth 1979 with occupational characteristics from the US Department of Labor O*NET database, I show that worker mobility across different task mixes is common and I estimate the model parameters. The current results indicate that skill uncertainty explains approximately 30% of worker mobility across different task ratios.

    Measurements of the Relaxivity of Contrast Agent in Rat Tissues

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    测量了钆螯合物的磁共振成像(MRI)对比度增强试剂钆双胺(omniscan)在大鼠不同组织,包括肝、脾、肾、心脏、肌肉和血液中的核磁共振(NMR)弛豫度,以及在不同的大分子介质环境,如小牛血清白蛋白(BSA)和甲基纤维素(MC)溶液中的弛豫度。实验数据表明:增强试剂钆双胺在小鼠的不同组织中的弛豫度互不相同,在大分子介质溶液中弛豫度随介质大分子浓度的增大而提高。With a paramagnetic gadodiamide contrast agent,NMR relaxivity was measured in rat tissues such as liver,spleen,kidney,heartand blood,as well as in various media of macromolecules such as methyl celluˉlose and albumin.The results of this study demonstrate that the relaxivity varies between different tissues and increases with the concentration of macromolecules.福建省自然科学基金资助项目(C0110024);; 国家自然科学基金资助项目(20172042
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