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

Innovation and market concentration with asymmetric firms

This paper considers a theoretical model of n asymmetric firms that reduce their initial unit costs by spending on R&D activities. In accordance with Schumpeterian hypotheses we obtain that more efficient (bigger) firms spend more in R&D and this leads to a more concentrated market structure. We also find a positive relationship between innovation and market concentration. This calls for a corrective tax on R&D activities to curtail strategic incentives to over-invest in R&D trying to achieve a higher market share. Klassifikation: L11, L52, O31 . February, 2004

A New Approach to Multidimensional Poverty Measurement

We present here a multidimensional poverty index that measures poverty as a function of the extent and the intensity of poverty. Extent is given by the share of the poor in the population. To measure intensity we start by defining individual unidimensional deprivation indices (one for each individual and each dimension) and then aggregating them as a geometric mean. Each individual deprivation index is simply the inverse of the share of individual achievements in the poverty thresholds. Our approach involves an elementary characterization, the determination of a specific formula, and the endogeneous identification of the poor.multidimensional poverty, ratio monotonicity, geometric mean, endogenous identification.

The Welfare Evaluation of Primary Goods: A Suggestion

This paper presents a characterization of a welfare index for the evaluation of primary goods (to be understood as those goods that all agents should enjoy equally). The welfare associated with a given distribution of n primary goods among m agents is measured as the sum of n real-valued functions, one for each good, which are increasing in the aggregate consumption and decreasing in its dispersion (measured by Theil's first inequality index).Welfare evaluation, Inequality, Primary goods

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

Distribution Sensitive Multidimensional Development Indices

This paper provides an elementary characterization of a family of multi-dimensional development indices that allows introducing distributive considerations. It consists of the generalized mean of the egalitarian equivalent values of the different dimensions. The key property that defines that family of indices is that of separability.multidimensional well-being, distribution sensitive indices, separability, human development.

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.

Spin bath interactions effects on the geometric phase

We calculate the geometric phase of a spin-1/2 particle coupled to an external environment comprising N spin-1/2 particle in the framework of open quantum systems. We analyze the decoherence factor and the deviation of the geometric phase under a nonunitary evolution from the one gained under an unitary one. We show the dependence upon the system's and bath's parameter and analyze the range of validity of the perturbative approximation. Finally, we discuss the implications of our results.Comment: 8 pages, 5 figures. Version to appear in Phys. Lett.