Recently two different concepts of covers of acts over monoids have been studied by a number of authors and many interesting results discovered. One of these concepts is based on coessential epimorphisms and the other is based on Enochs’ definition of a flat cover of a module over a ring. Two recent papers have suggested that in the former case, strongly flat covers are not unique. We show that...

Economic theory suggests that the use of flat-rate compensation for military recruiters is sub-optimal. We elicited the preferences of U.S. Navy recruiters for a piece-rate compensation scheme, and find many would prefer a modest decrease in fixed salary in exchange for the opportunity to receive a small monetary bonus per high-quality recruit. Under such a bonus scheme, the Navy could hire few...

This paper investigates some major changes in the wealth distribution in China using the data from two national household surveys conducted in 1995 and 2002. The surveys collected rich information on household wealth and its components, enabling a detailed analysis of changes in wealth distribution among Chinese households. Our analysis indicates that the wealth distribution in China as a whole...

This paper introduces an artificial payment card market in which we model the interactions between consumers, merchants and competing card issuers with the aim of determining the optimal pricing structure for card issuers. We allow card issuers to charge consumers and merchants with fixed fees, provide net benefits from card usage and engage in marketing activities. The demand by consumers and ...

Should Old-Age Benefits Be Earnings-Tested? We study the welfare effects of earnings testing flat-rate old-age benefits in a quantitative overlapping generations model with idiosyncratic labor income risk. In our model economy, even a moderate earnings testing reduces individuals’ expected lifetime utility, whenever other taxes are taken into account. Moreover, it also lowers the realized lifet...

The problem considered in the paper can be described as follows. We are given a continuous mapping from one metric space into another which is regular (in the sense of metric regularity or, equivalently, controllability at a linear rate) near a certain point. How small may be an additive perturbation of the mapping which destroys regularity? The paper contains a new proof of a recent theorem of...

November 1998 2 medicamundi X-ray examinations of the skeleton are, after chest exposures, the most frequently performed type of radiological examination, representing about 30 % of the total. With a few exceptions, projection radiography forms the basis for the diagnosis of skeletal disorders and, in most cases, provides the information for the definitive diagnosis. In traumatology, rheumatolo...