RESUMEN
Quantum electrodynamics (QED), the quantum field theory that describes the interaction between light and matter, is commonly regarded as the best-tested quantum theory in modern physics. However, this claim is mostly based on extremely precise studies performed in the domain of relatively low field strengths and light atoms and ions1-6. In the realm of very strong electromagnetic fields such as in the heaviest highly charged ions (with nuclear charge Z â« 1), QED calculations enter a qualitatively different, non-perturbative regime. Yet, the corresponding experimental studies are very challenging, and theoretical predictions are only partially tested. Here we present an experiment sensitive to higher-order QED effects and electron-electron interactions in the high-Z regime. This is achieved by using a multi-reference method based on Doppler-tuned X-ray emission from stored relativistic uranium ions with different charge states. The energy of the 1s1/22p3/2 J = 2 â 1s1/22s1/2 J = 1 intrashell transition in the heaviest two-electron ion (U90+) is obtained with an accuracy of 37 ppm. Furthermore, a comparison of uranium ions with different numbers of bound electrons enables us to disentangle and to test separately the one-electron higher-order QED effects and the bound electron-electron interaction terms without the uncertainty related to the nuclear radius. Moreover, our experimental result can discriminate between several state-of-the-art theoretical approaches and provides an important benchmark for calculations in the strong-field domain.
RESUMEN
BACKGROUND/AIMS: Recently, GB virus C (GBV-C) has been identified as another virus potentially causing viral hepatitis. However, its hepatotropism and pattern of infection in humans is still unknown. To elucidate the presence and replication of GBV-C in the human liver, we investigated tissue samples of six explanted livers from five GBV-C mono- or GBV-C/HCV co-infected patients for GBV-C RNA plus- and minus-strand RNA. METHODS: These tissues were examined using nested RT-PCR followed by Southern blot hybridization as well as fluorescence in situ hybridization on liver cryosections. To further substantiate susceptibility of liver cells for GBV-C, in vitro infection of human hepatoma cells (HuH7, HepG2) with GBV-C mono-infected serum was performed. RESULTS: By reverse transcription followed by nested PCR (RT-PCR), 5 of 6 liver specimens (4/5 patients) were positive for GBV-C plus-strand RNA, and viral minus-strand RNA could be detected in 4 of 6 liver specimens (4/5 patients). One liver sample was negative for GBV-C RNA. In two specimens we could identify GBV-C infection by in situ hybridization. Virus infection appeared to be restricted to hepatocytes and detection of minus-strand RNA showed viral replication in a few highly infected liver cells. In vitro infection of HepG2 or HuH7 cells confirmed these findings by a release of virions into supernatant. CONCLUSION: In conclusion, our results establish GBV-C as a hepatotropic virus infecting human cells of hepatic origin in vivo and in vitro.
