Comment on: ``Zero temperature conductance of parallel T-shape double quantum dots'' [Physica E 39 (2007) 214, arXiv:0708.1842v1]

In a recent paper [Physica E 39 (2007) 214, arXiv:0708.1842v1] Crisan, Grosu and Tifrea revisited the problem of the conductance through a double quantum dot molecule connected to electrodes in a T-shape configuration. The authors obtained an expression for the conductance that disagrees with previous results in the literature. We point out an error in their derivation of the conductance formula and show that it gives unphysical results even for non-interacting quantum dots.Comment: 2 pages, no figure

The Effect of Bans and Taxes on Passive Smoking

This paper evaluates the effect of smoking bans in public places on the exposure to tobacco smoke of non-smokers and contrasts it with the effect of excise taxes. Exploiting data on cotinine - a metabolite of nicotine - as well as state and time variation in anti-smoking policies across US states, we show that smoking bans in public places can perversely increase the exposure of non-smokers to tobacco smoke by displacing smokers to private places where they contaminate non-smokers, and in particular young children. In contrast, we find that higher taxes are an efficient way to decrease exposure to tobacco smoke, especially for those most exposed. We supplement this analysis by showing that bans have little effect on smoking cessation, and present evidence of displacement from public places using data on time use.smoking, taxes, bans

Passive smoking: the effect of bans and taxes

Smoking bans have been widely introduced in recent years in an effort to reduce non-smokers' exposure to tobacco smoke. Jérôme Adda and Francesca Cornaglia evaluate the effect of these restrictions - and of taxes on cigarettes - on the incidence of passive smoking and, in particular, their unintended consequences for children.smoking, taxes, bans

The effects of taxes and bans on passive smoking

This paper evaluates the effect of excise taxes and bans on smoking in public places on the exposure to tobacco smoke of non-smokers. We use a novel way of quantifying passive smoking: we use data on cotinine concentration- a metabolite of nicotine- measured in a large population of non-smokers over time. Exploiting state and time variation across US states, we reach two important conclusions. First, excise taxes have a significant effect on passive smoking. Second, smoking bans have on average no effects on non smokers. While bans in public transportation or in schools decrease the exposure of non smokers, bans in recreational public places can in fact perversely increase their exposure by displacing smokers to private places where they contaminate non smokers, and in particular young children. Bans affect socioeconomic groups differently: we find that smoking bans increase the exposure of poorer individuals, while it decreases the exposure of richer individuals, leading to widening health disparities.

Crime and Mental Wellbeing

Most estimates of the cost of crime focus on victims. Yet it is plausible that an even larger cost of crime occurs via its indirect impact on the mental wellbeing of non-victims. To test how crime affects individuals' mental outcomes, we exploit detailed panel data on mental wellbeing, allowing us to observe the relationship between changes in crime in a local area and changes in the mental wellbeing of resident non-victims in that area (controlling for changes in local economic conditions). Our results suggest that increases in crime rates have a negative impact on the mental wellbeing of residents, with the biggest impacts arising from violent crime. We also find that local press coverage of criminal activity enhances the effect of crime on mental well-being.neighbourhood effects, health, mental health, fear of crime

Crime and mental wellbeing

Francesca Cornaglia and Andrew Leigh measure the impact of crime - and media reporting of crime - on the mental wellbeing of both victims and non-victimswellbeing, crime,

On the Magnetic Nature of Quantum Point Contacts

We present results for a model that describes a quantum point contact. We show how electron-electron correlations, within the unrestricted Hartree-Fock approximation, generate a magnetic moment in the point contact. Having characterized the magnetic structure of the contact, we map the problem onto a simple one-channel model and calculate the temperature dependence of the conductance for different gate voltages. Our results are in good agreement with experimental results obtained in GaAs devices and support the idea of Kondo effect in these systems.Comment: 7 pages, 4 figure

Productivity, Wages and Marriage: The Case of Major League Baseball

The effect of marriage on productivity and, consequently, wages has been long debated in economics. A primary explanation for the impact of marriage on wages has been through its impact on productivity, however, there has been no direct evidence for this. In this paper, we aim to fill this gap by directly measuring the impact of marriage on productivity using a sample of professional baseball players from 1871 - 2007. Our results show that only lower ability men see an increase in productivity, though this result is sensitive to the empirical specification and weakly significant. In addition, despite the lack of any effect on productivity, high ability married players earn roughly 16 - 20 percent more than their single counterparts. We discuss possible reasons why employers may favor married men.Productivity, wage gap, marriage, and baseball

Theory of Core-Level Photoemission and the X-ray Edge Singularity Across the Mott Transition

The zero temperature core-level photoemission spectrum is studied across the metal to Mott insulator transition using dynamical mean-field theory and Wilson's numerical renormalization group. An asymmetric power-law divergence is obtained in the metallic phase with an exponent alpha(U,Q)-1 which depends on the strength of both the Hubbard interaction U and the core-hole potential Q. For Q <~ U_c/2 alpha decreases with increasing U and vanishes at the transition (U -> U_c) leading to a symmetric peak in the insulating phase. For Q >~ U_c/2, alpha remains finite close to the transition, but the integrated intensity of the power-law vanishes and there is no associated peak in the insulator. The weight and position of the remaining peaks in the spectra can be understood within a molecular orbital approach.Comment: 5 pages, 6 figure