Disturbance caused by aircraft noise

Noise pollution caused by the presence of airfields adjacent to residential areas is studied. Noise effects on the sleep of residents near airports and the degree of the residents noise tolerance are evaluated. What aircraft noises are annoying and to what extent the annoyance varies with sound level are discussed

On the class of caustics by reflection

Given any light position S in the complex projective plane P^2 and any algebraic curve C of P^2 (with any kind of singularities), we consider the incident lines coming from S (i.e. the lines containing S) and their reflected lines after reflection off the mirror curve C. The caustic by reflection is the Zariski clusure of the envelope of these reflected lines. We introduce the notion of reflected polar curve and express the class of the caustic by reflection in terms of intersection numbers of C with the reflected polar curve, thanks to a fundamental lemma established in [14]. This approach enables us to get an explicit formula for the class of the caustic by reflection in every case in terms of intersection numbers of the initial curve C.Comment: 21 pages, 1 figur

Multiple Correspondence Analysis & the Multilogit Bilinear Model

Multiple Correspondence Analysis (MCA) is a dimension reduction method which plays a large role in the analysis of tables with categorical nominal variables such as survey data. Though it is usually motivated and derived using geometric considerations, in fact we prove that it amounts to a single proximal Newtown step of a natural bilinear exponential family model for categorical data the multinomial logit bilinear model. We compare and contrast the behavior of MCA with that of the model on simulations and discuss new insights on the properties of both exploratory multivariate methods and their cognate models. One main conclusion is that we could recommend to approximate the multilogit model parameters using MCA. Indeed, estimating the parameters of the model is not a trivial task whereas MCA has the great advantage of being easily solved by singular value decomposition and scalable to large data

Degree and class of caustics by reflection for a generic source

We are interested in the study of caustics by reflection of irreducible algebraic planar curves (in the complex projective plane). We prove the birationality of the caustic map (for a generic light position). We also give simple formulas for the degree and the class of caustics by reflection valid for any irreducible algebraic curve of degree at least 2 and for a generic light position.Comment: 5 page

Incentives and Workers’ Motivation in the Public Sector

Civil servants have a bad reputation of being lazy. However, citizens' personal experiences with civil servants appear to be significantly better. We develop a model of an economy in which workers differ in laziness and in public service motivation, and characterise optimal incentive contracts for public sector workers under different informational assumptions. When civil servants' effort is unverifiable, lazy workers find working in the public sector highly attractive and may crowd out workers with a public service motivation. When effort is verifiable, the government optimally attracts motivated workers as well as the economy's laziest workers by offering separating contracts, which are both distorted. Even though contract distortions reduce aggregate welfare, a majority of society may be better off as public goods come at a lower cost.public sector labour markets, incentive contracts, work ethics, public service motivation

Managerial Talent, Motivation, and Self-Selection into Public Management

The quality of public management is a recurrent concern in many countries. Calls to attract the economy’s best and brightest managers to the public sector abound. This paper studies self-selection into managerial and non-managerial positions in the public and private sector,using a model of a perfectly competitive economy where people differ in managerial ability and in public service motivation. We find that, if demand for public sector output is not too high, the equilibrium return to managerial ability is always highest in the private sector. As aresult, relatively many of the more able managers self-select into the private sector. Since this outcome is efficient, our analysis implies that attracting a more able managerial workforce to the public sector by increasing remuneration to private-sector levels is not cost-efficient.public management, public service motivation, managerial ability, self-selection

Signaling and Screening of Workers' motivation

This paper develops a model in which workers to a certain extent enjoy working. We examine the implications of workers’ intrinsic motivation for optimal monetary incentive schemes. We show that motivated workers work harder and, for a given level of e.ort, are willing to work for a lower wage. When people di.er in their motivation to work at a particular firm, the profits of the firm depend on its capability to attract and select highly motivated workers. We show that when the firm has all the bargaining power and workers face application cost, the firm needs to commit to a minimum wage o.er in order to attract workers. A higher minimum wage increases the probability to fill the vacancy, but decreases the expected average quality of job applicants, as it induces lower motivated workers to apply. The optimal level of the minimum wage depends on whether or not the firm can observe the motivation of the applicants. If applicants can credibly signal their motivation, a minimum wage not only helps to attract workers, but also to select the best-motivated worker among the job applicants.signaling and screening models, intrinsic motivation, monetary incentive schemes, wage posting, minimum wage, worker selection