What Do We Work For? An Anatomy of Pre- and Post-Tax Earnings Growth

Promotions and cross-firm mobility provide substantial gains in earnings – a well established finding based on gross income data. Yet, what matters for incentives is how much an individual can consume or save after taxation. We show that net and gross income growth patterns may differ substantially when a progressive tax system allows for deduction opportunities. Exploiting unique matched employer-employee data with information on tax payments and employee mobility, we find that gross income gains from promotions and cross-firm mobility do not translate into significantly higher net income growth, because employees adjust their tax-shielded consumption and savings (in particular, deductible private pension contributions and mortgage-financed housing) to maintain constant net income growth.earnings growth, promotions, mobility, taxable income, dynamic panel data models, matched employer-employee data

Resistive magnetohydrodynamic reconnection : resolving long-term, chaotic dynamics

We acknowledge financial support from the EC FP7/2007-2013 Grant Agreement SWIFF (No. 263340) and from project GOA/2009/009 (KU Leuven). This research has been funded by the Interuniversity Attraction Poles Programme initiated by the Belgian Science Policy Office (IAP P7/08 CHARM). Part of the simulations used the infrastructure of the VSC-Flemish Supercomputer Center, funded by the Hercules Foundation and the Flemish Government-Department EWI. Another part of the simulations was done at the former Danish Center for Scientific Computing at Copenhagen University which is now part of DeIC Danish e-Infrastructure Cooperation.In this paper, we address the long-term evolution of an idealised double current system entering reconnection regimes where chaotic behavior plays a prominent role. Our aim is to quantify the energetics in high magnetic Reynolds number evolutions, enriched by secondary tearing events, multiple magnetic island coalescence, and compressive versus resistive heating scenarios. Our study will pay particular attention to the required numerical resolutions achievable by modern (grid-adaptive) computations, and comment on the challenge associated with resolving chaotic island formation and interaction. We will use shock-capturing, conservative, grid-adaptive simulations for investigating trends dominated by both physical (resistivity) and numerical (resolution) parameters, and confront them with (visco-)resistive magnetohydrodynamic simulations performed with very different, but equally widely used discretization schemes. This will allow us to comment on the obtained evolutions in a manner irrespective of the adopted discretization strategy. Our findings demonstrate that all schemes used (finite volume based shock-capturing, high order finite differences, and particle in cell-like methods) qualitatively agree on the various evolutionary stages, and that resistivity values of order 0.001 already can lead to chaotic island appearance. However, none of the methods exploited demonstrates convergence in the strong sense in these chaotic regimes. At the same time, nonperturbed tests for showing convergence over long time scales in ideal to resistive regimes are provided as well, where all methods are shown to agree. Both the advantages and disadvantages of specific discretizations as applied to this challenging problem are discussed.Publisher PDFPeer reviewe

Within- and cross-firm mobility and earnings growth

While it is well established that both promotions within firms and mobility across firms lead to significant earnings progression, little is known about the interaction between these types of mobility. Exploiting a large Danish panel data set and controlling for unobserved individual heterogeneity, we show that cross-firm moves at the non-executive level provide sizeable short-run gains (similar to the effect of a promotion), consistent with the existing literature. These gains, however, appear modest when compared with the persistent impact on earnings growth of promotions (either within or across firms) and subsequent mobility at a higher hierarchy level

What do we work for? An anatomy of pre- and post-tax earnings growth

Promotions and cross-firm mobility provide substantial gains in earnings - a well established finding based on gross income data. Yet, what matters for incentives is how much an individual can consume or save after taxation. We show that net and gross income growth patterns may differ substantially when a progressive tax system allows for deduction opportunities. Exploiting unique matched employer-employee data with information on tax payments and employee mobility, we find that gross income gains from promotions and cross-firm mobility do not translate into significantly higher net income growth, because employees adjust their tax-shielded consumption and savings (in particular, deductible private pension contributions and mortgage-financed housing) to maintain constant net income growth

Impacts of climate change on seabirds, relevant to the coastal and marine environment around the UK

• The seabird declines that commenced at the end of the last century have continued during the last two decades. • Further research into the causes of these declines is required if we are to fully understand the complex mechanisms operating, which are known to vary geographically. Climate change is considered to be one of the main causes of the declines. The principal mechanism is the effect of climate warming on food supply. • There is growing evidence that short-term weather conditions have an important effect, including extreme weather events. Climate models predict further warming and increased severity and frequency of extreme weather events in UK waters. • Seabirds face an uncertain future and may decline further in the coming decades, as the interacting effects of new and existing influences will pose additional challenges

Bayesian Error Estimation in Density Functional Theory

We present a practical scheme for performing error estimates for Density Functional Theory calculations. The approach which is based on ideas from Bayesian statistics involves creating an ensemble of exchange-correlation functionals by comparing with an experimental database of binding energies for molecules and solids. Fluctuations within the ensemble can then be used to estimate errors relative to experiment on calculated quantities like binding energies, bond lengths, and vibrational frequencies. It is demonstrated that the error bars on energy differences may vary by orders of magnitude for different systems in good agreement with existing experience.Comment: 5 pages, 3 figure

Particle Acceleration, Magnetic Field Generation, and Emission in Relativistic Shocks

Shock acceleration is an ubiquitous phenomenon in astrophysical plasmas. Plasma waves and their associated instabilities (e.g., Buneman, Weibel and other two-stream instabilities) created in collisionless shocks are responsible for particle (electron, positron, and ion) acceleration. Using a 3-D relativistic electromagnetic particle (REMP) code, we have investigated particle acceleration associated with a relativistic jet front propagating into an ambient plasma. We find small differences in the results for no ambient and modest ambient magnetic fields. Simulations show that the Weibel instability created in the collisionless shock front accelerates jet and ambient particles both perpendicular and parallel to the jet propagation direction. The small scale magnetic field structure generated by the Weibel instability is appropriate to the generation of ``jitter'' radiation from deflected electrons (positrons) as opposed to synchrotron radiation. The jitter radiation resulting from small scale magnetic field structures may be important for understanding the complex time structure and spectral evolution observed in gamma-ray bursts or other astrophysical sources containing relativistic jets and relativistic collisionless shocks.Comment: 6 pages, 1 figure, revised and accepted for Advances in Space Research (35th COSPAR Scientific Assembly, Paris, 18-25 July 2004

Radiation from relativistic jets

Nonthermal radiation observed from astrophysical systems containing relativistic jets and shocks, e.g., gamma-ray bursts (GRBs), active galactic nuclei (AGNs), and Galactic microquasar systems usually have power-law emission spectra. Recent PIC simulations of relativistic electron-ion (electron-positron) jets injected into a stationary medium show that particle acceleration occurs within the downstream jet. In the presence of relativistic jets, instabilities such as the Buneman instability, other two-streaming instability, and the Weibel (filamentation) instability create collisionless shocks, which are responsible for particle (electron, positron, and ion) acceleration. The simulation results show that the Weibel instability is responsible for generating and amplifying highly nonuniform, small-scale magnetic fields. These magnetic fields contribute to the electron's transverse deflection behind the jet head. The ``jitter'' radiation from deflected electrons in small-scale magnetic fields has different properties than synchrotron radiation which is calculated in a uniform magnetic field. This jitter radiation, a case of diffusive synchrotron radiation, may be important to understand the complex time evolution and/or spectral structure in gamma-ray bursts, relativistic jets, and supernova remnants.Comment: 8 pages,3 figures, accepted for the Proceedings of Science of the Workshop on Blazar Variability across the Electromagnetic Spectrum, April 22 to 25, 200