Labour Supply Implications of a Negative Income Tax Plan

À partir du modèle économique traditionnel du choix entre le loisir et le revenu, sont estimées séparément à l'aide de régression linéaire à deux étapes dites des moindres carrés doubles les fonctions d'offre de travail pour jeunes hommes et jeunes femmes.Cette procédure permet d'obtenir des simulations de l'effet de diverses combinaisons de taux de taxation négative et de transferts absolus de revenus sur l'offre de travail de ces groupes.L'étude démontre qu'un programme de taxation négative du revenu conduit à de fortes réductions dans l'offre de travail de ces groupes. Elle démontre aussi qu'un programme de taxation négative du revenu conduit à de fortes réductions dans l'offre de travail des jeunes gens et plus particulièrement chez les femmes.This study demonstrates that a Negative Income Tax Plan can be expected to result in fairly large reductions in the supply of work effort in the case of younger workers. The potential reductions in labour supply of female workers appear to be particularly large

DeepMasterPrints: Generating MasterPrints for Dictionary Attacks via Latent Variable Evolution

Recent research has demonstrated the vulnerability of fingerprint recognition systems to dictionary attacks based on MasterPrints. MasterPrints are real or synthetic fingerprints that can fortuitously match with a large number of fingerprints thereby undermining the security afforded by fingerprint systems. Previous work by Roy et al. generated synthetic MasterPrints at the feature-level. In this work we generate complete image-level MasterPrints known as DeepMasterPrints, whose attack accuracy is found to be much superior than that of previous methods. The proposed method, referred to as Latent Variable Evolution, is based on training a Generative Adversarial Network on a set of real fingerprint images. Stochastic search in the form of the Covariance Matrix Adaptation Evolution Strategy is then used to search for latent input variables to the generator network that can maximize the number of impostor matches as assessed by a fingerprint recognizer. Experiments convey the efficacy of the proposed method in generating DeepMasterPrints. The underlying method is likely to have broad applications in fingerprint security as well as fingerprint synthesis.Comment: 8 pages; added new verification systems and diagrams. Accepted to conference Biometrics: Theory, Applications, and Systems 201

Dynamic Pricing of Network Goods with Boundedly Rational Consumers

An important simplifying assumption made when analyzing goods that display positive network effects is that potential consumers can form a rational expectation of the equilibrium demand for the good, and that they all form the same expectation, which is then fulfilled based on their consumption choices - sometimes called a rational expectations equilibrium (REE). We examine whether the results of these models are robust to the relaxation of this assumption. In our model, consumers differ in their marginal utility of total demand (intensity of the network effect), which varies according to a given distribution (the distribution of consumer "types"), and are boundedly rational in two ways. First, only a fraction of consumers "pay attention" to price announcements in any interval of time. Second, those consumers who pay attention make their consumption choices based on a boundedly rational expectation of future demand. Our benchmark model is of myopic expectations, although we show how our results generalize (1) to a case in which the population of consumers contains both those who are myopic and those who are "fully rational," and (2) to a case in which consumers have expectations that are partly "stubborn". We base our analysis on a continuous-time approximation of an underlying discrete-time model. Under this approximation, the instantaneous choices of consumers continuously influence the rate at which demand adjusts over time, and a monopolist chooses a price trajectory to maximize profit. First, we show that, under fairly general assumptions about the distribution of types, the profit-maximizing rational expectations equilibrium is not a steady state of the optimal trajectory with boundedly rational consumers. Our second theorem shows that if consumer types are uniformly distributed and consumers form myopic (or more rational) expectations, the monopolistâÃÂÃÂs optimal pricing trajectory is generated by a "target policy" with the following properties: when current demand is below the target, the price is zero; when current demand is above the target, the price is the maximum possible, and when current demand is at the target, the price is chosen to keep demand stationary. We also show that the optimal demand target with boundedly rational consumers is always strictly lower than the equilibrium level of demand predicted by a model with rational expectations. Furthermore, the difference between the target demand and the rational expectations demand is higher when consumers pay attention to the monopolistâÃÂÃÂs price announcements at a lower rate. We generalize the results from this example in two ways. Our third theorem examines the case of myopic consumers and strictly concave distributions of consumer types. To find an optimal policy one must expand the set of controls to include measure-valued controls. The optimal policy is similar to the target policy of Theorem 2, except that when current demand is at the target, the monopolist chooses the "mixture" between a price of zero and the maximum possible price that keeps demand stationary. For convex consumer type distributions in the neighborhood of the uniform distribution, we give a heuristic argument to support a conjecture that the monopolist continues to choose a demand target lower than the rational expectations demand, but varies price gradually in the neighborhood of the demand target. Finally, for uniformly distributed types and consumer expectations that are both myopic and "stubborn", we show that the monopolistâÃÂÃÂs optimal pricing trajectory is generated by a target policy with the same properties as those in Theorem 2, although with a target that is strictly lower, and that increases as consumers become progressively less stubborn. (This paper is part of a program of research whose broad objective is to explore the conditions under which the assumption of unbounded rationality in economic models is a reasonable one).Information Systems Working Papers Serie

Dynamic Pricing of Network Goods with Boundedly Rational Consumers

We present a model of dynamic monopoly pricing for a good that displays network effects. In contrast with the standard notion of a rational-expectations equilibrium, we model consumers as boundedly rational, and unable either to pay immediate attention to each price change, or to make accurate forecasts of the adoption of the network good. Our analysis shows that the sellerâÂÂs optimal price trajectory has the following simple structure: the price is zero when the product user base is below a specific threshold, and is chosen to keep user base stationary once this threshold demand level has been attained. We show that our prescribed pricing policy is robust to a number of extensions, which include the productâÂÂs user base evolving over time, a fraction of consumers being sufficiently rational to make accurate adoption forecasts, and consumers basing their choices on a mixture of a myopic and a "stubborn" expectation of adoption. Our results differ significantly from those that would be predicted by a model based on rational-expectations equilibrium, and are more consistent with the pricing of network goods observed in practice.Information Systems Working Papers Serie

A simple model for self-propulsion of microdroplets in surfactant solution

We propose a simple active hydrodynamic model for the self-propulsion of a liquid droplet suspended in micellar solutions. The self-propulsion of the droplet occurs by spontaneous breaking of isotropic symmetry and is studied using both analytical and numerical methods. The emergence of self-propulsion arises from the slow dissolution of the inner fluid into the outer micellar solution as filled micelles. We propose that the surface generation of filled micelles is the dominant reason for the self-propulsion of the droplet. The flow instability is due to the Marangoni stress generated by the non-uniform distribution of the surfactant molecules on the droplet interface. In our model, the driving parameter of the instability is the excess surfactant concentration above the critical micellar concentration which directly correlates with the experimental observations. We consider various low-order modes of flow instability and show that the first mode becomes unstable through a supercritical bifurcation and is the only mode contributing to the swimming of the droplet. The flow fields around the droplet for these modes and their combined effects are also discussed.Comment: 8 pages, 5 figure

A Statistical Approach for Study of Roundness in Commercially Produced Round Metal Bars

Commercially produced ferrous and non-ferrous metal round bars are available at various sizes. These bars have tremendous engineering use in multiple areas like automobile, aerospace, power, manufacturing, paper, printing, packaging and construction industries. Due to its wide range of utility of round bars, it is naturally pertinent to understand and ascertain quality aspect of these bars. Quite often it has been observed that round bars as available are not completely geometrically round at various sections along the length, also straightness is also somewhat compromised. Therefore, it is necessary to check the uniformity of diameters at various sections. In this paper statistical process control has been used to ascertain whether such round bars as commercially available can be utilized for industrial application or not. Control limits in terms of diameter measurement along the length of bars help to evaluate the characteristics of data variation which is needed to take decision about confirmation of utility of commercially produced bar