194 research outputs found
Relativistic strong-field ionization of hydrogen-like atomic systems in constant crossed electromagnetic fields
Relativistic strong-field ionization of hydrogen-like atoms or ions in a
constant crossed electromagnetic field is studied. The transition amplitude is
formulated within the strong-field approximation in G\"oppert-Mayer gauge, with
initial and final electron states being described by the corresponding
Dirac-Coulomb and Dirac-Volkov wave functions, respectively. Coulomb
corrections to the electron motion during tunneling are taken into account by
adjusting an established method to the present situation. Total and
energy-differential ionization rates are calculated and compared with
predictions from other theories in a wide range of atomic numbers and applied
field strengths.Comment: 9 pages, 4 figure
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Assessment of the tissue distribution of transplanted human endothelial progenitor cells by radioactive labeling
Background— Transplantation of endothelial progenitor cells (EPCs) improves vascularization and left ventricular function after experimental myocardial ischemia. However, tissue distribution of transplanted EPCs has not yet been monitored in living animals. Therefore, we tested whether radioactive labeling allows us to detect injected EPCs
Do higher corporate taxes reduce wages? : Micro evidence from Germany
Because of endogeneity problems very few studies have been able to identify
the incidence of corporate taxes on wages. We circumvent these problems
by using an 11-year panel of data on 11,441 German municipalities' tax
rates, 8 percent of which change each year, linked to administrative matched
employer-employee data. Consistent with our theoretical model, we find a
negative effect of corporate taxation on wages: a 1 euro increase in tax liabilities
yields a 77 cent decrease in the wage bill. The direct wage effect, arising
in a collective bargaining context, dominates, while the conventional indirect
wage effect through reduced investment is empirically small due to regional labor
mobility. High and medium-skilled workers, who arguably extract higher
rents in collective agreements, bear a larger share of the corporate tax burden
The chromatin remodelling enzymes SNF2H and SNF2L position nucleosomes adjacent to CTCF and other transcription
Within the genomes of metazoans, nucleosomes are highly organised adjacent to the binding sites for a subset of transcription factors. Here we have sought to investigate which chromatin remodelling enzymes are responsible for this. We find that the ATP-dependent chromatin remodelling enzyme SNF2H plays a major role organising arrays of nucleosomes adjacent to the binding sites for the architectural transcription factor CTCF sites and acts to promote CTCF binding. At many other factor binding sites SNF2H and the related enzyme SNF2L contribute to nucleosome organisation. The action of SNF2H at CTCF sites is functionally important as depletion of CTCF or SNF2H affects transcription of a common group of genes. This suggests that chromatin remodelling ATPase's most closely related to the Drosophila ISWI protein contribute to the function of many human gene regulatory elements
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