Asteroseismology of binary stars and a compilation of core overshoot and rotational frequency values of OB stars

After a brief introduction into the asteroseismic modelling of stars, we provide a compilation of the current seismic estimates of the core overshooting parameter and of the rotational frequency of single and binary massive stars. These important stellar parameters have meanwhile become available for eleven OB-type stars, among which three spectroscopic pulsating binaries and one magnetic pulsator. We highlight the potential of ongoing and future analyses of eclipsing binary pulsators as essential laboraties to test stellar structure and evolution models of single and binary stars.Comment: Proceedingspaper, 8 pages, 3 figures, 1 table, to appear in "Setting a New Standard in the Analysis of Binary Stars", Eds K. Pavlovski, A. Tkachenko, and G. Torres, EAS Publications Serie

Massive Star Asteroseismology in Action

After highlighting the principle and power of asteroseismology for stellar physics, we briefly emphasize some recent progress in this research for various types of stars. We give an overview of high-precision high duty-cycle space photometry of OB-type stars. Further, we update the overview of seismic estimates of stellar parameters of OB dwarfs, with specific emphasis on convective core overshoot. We discuss connections between pulsational, rotational, and magnetic variability of massive stars and end with future prospects for asteroseismology of evolved OB stars.Comment: Invited review paper to appear in Proc. IAU307: New windows on massive stars: asteroseismology, interferometry, and spectropolarimetry, Editors: G. Meynet, C. Georgy, J.H. Groh & Ph. Stee, 9 pages, 2 figure

Optimal Use of Labor Market Policies: The Role of Job Search Assistance

This paper studies the role of job search assistance programs in optimal welfare-to-work programs. The analysis is based on a framework, that allows for endogenous choice of benefit types and levels, wage taxes or subsidies, and activation measures such as monitoring and job search assistance for each period of unemployment in a dynamic environment with negative duration dependence in the exit rates to employment and potential depreciation in reemployment wages. We show that the main role of job search assistance is to delay or prevent situations in which it is no longer optimal to incentivize the worker to provide positive search effort. It is used to restore or maintain some minimum exit rate to employment which increases with the cost-effectiveness of job search assistance. We also find that in line with existing policies, these programs should mainly be used at the beginning of unemployment and for short durations. However, contrary to existing schemes, they should be exclusively targeted at unemployed workers with low initial exit rates to employment. For all other workers, they should only be used if they fail to find a job within reasonable time despite high expected initial exit rates.job search, optimal unemployment insurance, welfare-to-work policies, recursive contracts

The Welfare Gains of Improving Risk Sharing in Social Security

This paper shows that improved intergenerational risk sharing in social security may imply very large welfare gains, amounting to up to 15 percent of the per-period consumption relative to the current U.S. consumption. Improved risk sharing raises welfare through a direct effect, i.e., by correcting an initially inefficient allocation of risk, and through a general equilibrium (GE) effect. The GE effect is due to the fact that the allocation of risk in the pay-as-you-go system influences the demand for capital. As a result, with an efficient risk sharing arrangement, the crowding out effect associated with an unfunded system can actually be completely eliminated. Efficient risk sharing in social security implies highly volatile and pro-cyclical benefits, i.e., that retirees' exposure to productivity risk is increased. Consequently, a policy involving completely safe benefits will unambiguously be welfare reducing.Social security; Risk sharing

Optimal Use of Labour Market Policies

Labour market policies for the unemployed combine passive income support with active measures that aim at improving jobseekers' employment prospects. This paper extends the theoretical framework developed by Pavoni and Violante (2005a) for the optimal choice between different active and passive policies for the unemployed to a setting which allows for the use of a job search assistance programme that affects the exit rate to employment by raising search effectiveness but not productivity in the job. These programmes are one of the most widely used activation measures in OECD countries and should, therefore, be taken into account when considering the optimal design of labour market policies. The enriched model allows to answer a wide range of interesting policy questions. It is used to assess the optimality of the West German policy in the period 2000-2002 as well as the benefits from introducing tight monitoring. It is shown that sizeable budget savings could have been realised by switching to the optimal scheme, but that the net gains from monitoring are only small. In addition, some interesting results on the optimal use of job search assistance and training are derived. It is shown that existing policies already share some but not all features of the optimal scheme.Unemployment insurance, active labour market policies, recursive contracts, job search, human capital

Why do Europeans Work so Little?

Market work per person is roughly 10 percent higher in the U.S. than in Sweden. However, if we include the work carried out in home production, the total amount of work only differs by 1 percent. I set up a model with home production, and show that differences in policy - mainly taxes – can account for the discrepancy in labor supply between Sweden and the U.S. Moreover, even though the elasticity of labor supply is rather low for individual households, labor taxes are estimated to be associated with considerable output losses. I also show that policy can account for the falling trend in market work in Sweden since 1960. The largest reduction occurs from 1960 until around 1980, both in the model and the data. After the early 1980s, the trends for both taxes and actual hours worked are basically flat. This is also true for hours worked in the model.Labor supply; Taxes; Home production

Optimal Use of Labor Market Policies: The Role of Job Search Assistance

This paper studies the role of job search assistance programs in optimal welfare-to-work programs. The analysis is based on a framework, that allows for endogenous choice of benefit types and levels, wage taxes or subsidies, and activation measures such as monitoring and job search assistance for each period of unemployment in a dynamic environment with negative duration dependence in the exit rates to employment and potential depreciation in reemployment wages. We show that the main role of job search assistance is to delay or prevent situations in which it is no longer optimal to incentivize the worker to provide positive search effort. It is used to restore or maintain some minimum exit rate to employment which increases with the cost-effectiveness of job search assistance. We also find that in line with existing policies, these programs should mainly be used at the beginning of unemployment and for short durations. However, contrary to existing schemes, they should be exclusively targeted at unemployed workers with low initial exit rates to employment. For all other workers, they should only be used if they fail to find a job within reasonable time despite high expected initial exit rates.job search, optimal unemployment insurance, welfare-to-work policies, recursive contracts

Social Security and the Equity Premium Puzzle

This paper shows that social security may be an important factor in explaining the equity premium puzzle. In the absence of shortselling constraints, the young shortsell bonds to the middle-aged and buy equity. Social security reduces the bond demand of the middle-aged, thereby restricting the possibilities of the young to finance their equity purchases. They demand less equity and the return to equity goes up. Social security also increases the covariance between future consumption and the equity income of the young. The efect on the equity premium is substantial. In fact, a model with social security and borrowing constraints can generate a fairly realistic equity premium.Asset prices; the equity premium puzzle; social security

Working with the CHILDES tools : transcription, coding and analysis

The Child Language Data Exchange System (CHILDES) consists of Codes for the Human Analysis of Transcripts (CHAT), Computerized Language Analysis (CLAN), and a database. There is also an online manual which includes the CHILDES bibliography, the database, and the CHAT conventions as well as the CLAN instructions. The first three parts of this paper concern the CHAT format of transcription, grammatical coding, and analyzing transcripts by using the CLAN programs. The fourth part shows examples of transcribed and coded data