Hadronic vacuum polarization correction to atomic energy levels

The shift of atomic energy levels due to hadronic vacuum polarization is evaluated in a semiempirical way for hydrogenlike ions and for muonic hydrogen. A parametric hadronic polarization function obtained from experimental crosssections of e- e+ annihilation into hadrons is applied to derive an effective relativistic Uehling potential. The energy corrections originating from hadronic vacuum polarization are calculated for low-lying levels using analytical Dirac-Coulomb wave functions, as well as bound wave functions accounting for the finite nuclear size. Closed formulas for the hadronic Uehling potential of an extended nucleus as well as for the relativistic energy shift in case of a point-like nucleus are derived. These results are compared to existing analytic formulas from non-relativistic theory

Soft X-ray analysis of a loop flare on the Sun

We present the results of an analysis of soft X-ray images for a solar flare which occurred on 1992 July 11. This flare, as seen in Yohkoh Soft X-ray Telescope (SXT) images was of comparatively simple geometry, consisting of two bright footpoints early in the flare with a bright loop seen later in the flare. We examine how closely this flare compares with the supposed paradigm of a confined simple-loop flare. Closer examination of the SXT images reveals that the flare structure consisted of at least two adjacent loops, one much fainter than the other. We examine the brighter of the two soft X-ray loops. The SXT images reveal an apparent slow, northward motion of this loop (roughly transverse to its major axis). Examination of derived emission measure and temperature images also indicate an apparent northward motion. In addition, we find an increase in the cross-sectional width at the top of the loop with time. Emission measure maps derived from the SXT images also indicates an apparent broadening of the loop-top region. We infer that the apparent northward motion and the apparent broadening of the soft X-ray emission can be explained in a reconnection scenario where successive magnetic field structures do not lie in a plane but are tilted to the south of the line of sight but with successively brightening loops oriented at less tilted angles. Halpha images for this flare reveal an evolution from a few brilliant points to a short two- ribbon-like appearance. Comparison of the SXT images with the Halpha images shows that the Halpha patches are aligned with the footpoints of the soft X-ray loops, suggesting the presence of a small arcade structure. There is no clear evidence for an eruptive signature in our observations nor in reports from other observations. The lack of an eruptive signature could suggest that the flare may have been a confined simple-loop flare, but this is not compelling due to a gap in the coronal observations prior to and early in the event. Analysis of our observations indicate that the flare exhibited characteristics suggesting that it may be better understood as a mini-arcade flare. These results casts doubt on the validity of the supposed paradigm of a confined simple-loop flare, at least for this flare. They indicate that even an apparently simple-loop flare may be considered to be a variety of arcade flare. We also find an effect which, to our knowledge, has not been reported before: the hot flaring regions later become cooler than the surrounding quiescent corona. That is, the flare loops do not evolve into bright active region loops, but into cooler loops. This may indicate an increase in the efficiency of the cooling mechanism or a transformed equilibrium state within the flaring loops

Antibody Seroprevalence of Diphtheria in Young Adults

Our study has been planned to search for the susceptibility of the young adult population to diphtheria. For this purpose, 410 soldiers in 20-25 age group have been tested for their antibodies against diphteriae. We have also recorded their ages, education status and geographic regions. Blood samples were taken from a research group of mean age 20.89 ± 0.095 and then 0.5 mL adult type diphtheria-tetanus vaccine (Imogam dT, Pasteur-Merieux, France) was applied. Of 410, the second blood samples of 316 subjects were taken for searching the diphtheria antibodies. Diphtheriae antibody levels were tested by using of Gen-enzyme Virotech GmbH (Löwenplatz 5, Rüsselsheim, Germany) test kit in the first and the second blood samples of these 316 subjects. 24.5% (50/204) of the 20 years age group, 29.4% (30/102) of the 21-24 years age group and 30% (3/10) of the 25 years age group had antibodies under the protective level of 0.01 IU/mL. Prior to vaccination period a statistically insignificant difference between the groups was determined with respect to age, educational status and geographic area (p> 0.05 for all groups). After the vaccination, in all age groups the antibody levels were found as above the protective level. According to these results, it can be concluded that dT vaccination should be considered for the 20 years age group