Experimental observation of three-color optical quantum correlations

Quantum correlations between bright pump, signal, and idler beams produced by an optical parametric oscillator, all with different frequencies, are experimentally demonstrated. We show that the degree of entanglement between signal and idler fields is improved by using information of pump fluctuations. This is the first observation of three-color optical quantum correlations.Comment: 3 pages, 3 figure

The Costs and Benefits of a Comprehensive Induction Program

Until now there have been no benefit-cost studies of mentoring programs for beginning teachers to provide legislators, educational administrators, and program leaders with the kind of economic information they need for informed decision making. In a benefit-cost analysis we estimate the financial benefits of a given course of action against the actual costs, and use the resulting balance to guide decision making. Costs are either one-time, or may be ongoing. Benefits are most often received over time. In its simple form, benefit-cost analysis is carried out using only actual financial costs and financial benefits. A more sophisticated approach attempts also to put a financial value on intangible costs and benefits, a process that can be highly subjective. In order to provide an estimate of the potential return on the investment in a comprehensive mentoring program for beginning teachers we collected actual cost data for the Santa Cruz New Teacher Project across all its local contexts,calculated the measured benefits, assigning them a monetary value where possible, and computed the net present value over five years. We looked at net benefits or costs from multiple perspectives: the state, the district, the school, the teacher, and the student. The total of all these represents the net benefit or cost to society.calculated the measured benefits, assigning them a monetary value where possible, and computed the net present value over five years. We looked at net benefits or costs from multiple perspectives: the state, the district, the school, the teacher, and the student. The total of all these represents the net benefit or cost to society

The Online Faculty Development and Assessment System

This article evaluates the role of the Online Faculty Development and Assessment System (OFDAS), created at universities in the Canary Islands, Spain, in staff development. The evaluation indicates that the system helped staff in learning to teach curriculum and teaching capacities. The tasks, online resources and opportunities for discussions provided within the learning environment created for the system helped shape their attitudes towards learning curriculum and teaching capacities and enabled them to share their concerns about students’ classroom learning environment assessment

Competitive Pricing

Competitive pricing is a pricing rule that combines two principles that are present in competitive markets. The profit principle (an action will be chosen only if it yields maximal payoffs), and the scarcity principle (markets make expensive those commodities that restrict production possibilities). It is shown that, under standard assumptions, these principles imply profit maximization at given prices. But also that they can be applied to economies with non-convex production sets (e.g. firms with S-shaped production functions). The chief properties of this pricing rule, as well as the existence and efficiency of the associated equilibria, are analyzednon-convex production sets, competitive pricing rule, competitive pricing equilibrium.

Does cartel leadership facilitate collusion?

We discuss the implications of a Stackelberg sequence of play between a cartel and the fringe. We consider two different approaches to collusion: (i) one-stage static model and (ii) a multi-period oligopoly model. Our main result is that in the static model with quantity-setting firms a stable cartel only exist when cartel firms behave as a Stackelberg leader. It is also shown that in the supergame approach the cartel is always more easily sustained with the leadership than in the simultaneous-moves game. The opposite result is obtained in a price-setting supergame with differentiated products.Collusion; Leadership; Stability; Sustainability

A Reflection On The Effects Of Transport Costs Within The New Economic Geography

The purpose of this paper is to analyze, in the light of recent contributions of New Economic Geography models, the spatial consequences of transport cost reductions. So far, the role of transport costs have been only partially unveiled, since papers focused either on the Dixit-Stiglitz-Iceberg framework or on the alternative framework put forth by Ottaviano et al. (2002)—which departs from the former in preferences and transport modelling. This paper goes a step further, offering a comprehensive view that includes the two approaches, in contexts both of two and of more than two locations. As opposed to other revisions of the literature, which have focused mainly on the centripetal forces included in these models, we emphasize the role of dispersion forces. The study suggests that in a two-location setting the results seem quite robust against changes in transportation modelling, so that considering either multiplicative transport costs or additive the predictions are identical. However, when allowing for a multilocation setup, the analysis becomes more complex.agglomeration, dispersion, monopolistic competition, transport costs.

ON WELFARE EFFECTS OF HORIZONTAL MERGERS WITH PRODUCT DIFFERENTIATION

We use a non-spatial (Chamberlinian) product differentiation model to analyze the welfare effects of horizontal mergers with quantity competition. We argue that(i) mergers can be welfare enhancing if the degree of product differentiation increases after the merger; and,(ii) privately profitable mergers can also increase welfare. Consequently, in this paper we demonstrate that the degree of product differentiation is a crucial factor to assess the welfare effects of a merger.Horizontal mergers; product differentiation; welfare.

A model of economic geography with demand pull and congestion costs

This paper proposes a simple model of economic geography in which to derive analytical results when jointly considering two centrifugal forces —congestion costs together with the pull demand effect— within the Dixit-Stiglitz-Iceberg framework. In this vein, we develop a unified model with labor mobility that combines some of the features of Tabuchi (1998) with those of Forslid and Ottaviano (2003). We analytically show that when considering the effects of congestion costs, dispersion of economic activity is possible not only at high but also at low transport costs. This result corroborates previous numerical simulations conducted by Tabuchi (1998).Congestion costs, demand pull, urban concentration, transport costs.

MULTIDIMENSIONAL INEQUALITY AND SOCIAL WELFARE

This paper provides a cardinal welfare measure for the allocation of a bundle of goods among a group of people. Social welfare is measured as the sum of n partial indices, one for each good, each of which consists of a function of the amount of the good availabe and its dispersion, measured by Theil's first inequality index. Some applications of this welfare measure are also suggested.Inequality and Welfare; Social Goods; Cardinal Welfare Measures.