Variations in the propagation of UH-nuclei

Calculations of the propagation of UH-nuclei were improved by extending the number of individual nuclides considered, and by using more recent evaluations of the rigidity dependence of the escape length, the possible source composition, and altered cross sections. The effects of using different expressions for the dependence of abundances on first ionization potentials (FIP) are outlined. The sensitivity of the calculated elemental abundances to the various changes made in the propagation assumptions are discussed

Interactions of heavy nuclei, Kr, Xe and Ho, in light targets

Over the past few years, the HEAO-3 measurements of the abundances of ultra-heavy cosmic ray nuclei (Z 26) at earth have been analyzed. In order to interpret these abundances in terms of a source composition, allowance must be made for the propagation of the nuclei in the interstellar medium. Vital to any calculation of the propagation is a knowlege of the total and partial interaction cross sections for these heavy nuclei on hydrogen. Until recently, data on such reactions have been scarce. However, now that relativistic heavy ion beams are available at the LBL Bevalac, some of the cross sections of interest can be measured at energies close to those of the cosmic ray nuclei being observed. During a recent calibration at the Bevalac of an array similar to the HEAO-C3 UH-nuclei detector, targets of raphite (C), polyethylene (CH2), and aluminum were exposed to five heavy ion beams ranging in charge (Z) from 36 to 92. Total and partial charge changing cross sections for the various beam nuclei on hydrogen can be determined from the measured cross sections on C and CH2, and will be applied to the propagation problem. The cross sections on Al can be used to correct the abundances of UH cosmic rays observed in the HEAO C-3 detector for interactions in the detector itself

Comparison of simulated longitudinal profiles of hadronic air showers with MASS2 balloon data

The KASKADE and CORSIKA air shower generators are compared to the data collected by MASS2 balloon experiment in 1991. The test of longitudinal profile for proton, helium and muon flux production provide good constraints on these air shower generators. KASKADE and CORSIKA especially with the new simulator UrQMD for low energies are found to fit these data well. This study is limited to a comparison of longitudinal profiles and therefore does not provide constraints on the overall shower development.Comment: to be published in Astroparticle Physic

Radial extracorporeal shock wave therapy is efficient and safe in the treatment of fracture nonunions of superficial bones: a retrospective case series

Background: A substantial body of evidence supports the use of focused extracorporeal shock wave therapy (fESWT) in the non-invasive treatment of fracture nonunions. On the other hand, virtually no studies exist on the use of radial extracorporeal shock wave therapy (rESWT) for this indication. Methods: We retrospectively analyzed 22 patients treated with rESWT for fracture nonunions of superficial bones that failed to heal despite initial surgical fixation in most cases. Radial extracorporeal shock wave therapy was applied without anesthesia in three rESWT sessions on average, with one rESWT session per week and 3000 radial extracorporeal shock waves at an energy flux density of 0.18 mJ/mm(2) per session. Treatment success was monitored with radiographs and clinical examinations. Results: Six months after rESWT radiographic union was confirmed in 16 out of 22 patients (73%), which is similar to the success rate achieved in comparable studies using fESWT. There were no side effects. The tibia was the most common treatment site (10/22) and 70% of tibia nonunions healed within 6 months after rESWT. Overall, successfully treated patients showed a mean time interval of 8.8 +/- 0.8 (mean +/- standard error of the mean) months between initial fracture and commencement of rESWT whereas in unsuccessfully treated patients the mean interval was 26.0 +/- 10.1 months (p < 0.05). In unsuccessful tibia cases, the mean interval was 43.3 +/- 13.9 months. Conclusions: Radial extracorporeal shock wave therapy appears to be an effective and safe alternative in the management of fracture nonunions of superficial bones if diagnosed early and no fESWT device is available. The promising preliminary results of the present case series should encourage the implementation of randomized controlled trials for the early use of rESWT in fracture nonunions

The Abundances of Ultraheavy Elements in the Cosmic Radiation

Analysis of a new, higher resolution data set from the Heavy Nuclei Experiment on the HEA0-3 spacecraft has yielded the cosmic ray abundances relative to iron of oddeven element pairs with atomic number, Z, in the range 33≤Z≤60. The abundances are consistent with a solar-system source provided an allowance is made for a source fraetionation based on first ionization potential (FIP). However, extending this analysis· to element groups with Z>60, we find enhancements of the Pt group (74≤Z≤80) abundance relative to the solar system and a corresponding increase in the largely secondary nuclei in the range 62≤Z≤73, in agreement with recent Ariel-6 results. These abundances suggest an enhancement of the r-process contribution to the source of the Z > 60 nuclei

Direct measurement of stellar angular diameters by the VERITAS Cherenkov Telescopes

The angular size of a star is a critical factor in determining its basic properties. Direct measurement of stellar angular diameters is difficult: at interstellar distances stars are generally too small to resolve by any individual imaging telescope. This fundamental limitation can be overcome by studying the diffraction pattern in the shadow cast when an asteroid occults a star, but only when the photometric uncertainty is smaller than the noise added by atmospheric scintillation. Atmospheric Cherenkov telescopes used for particle astrophysics observations have not generally been exploited for optical astronomy due to the modest optical quality of the mirror surface. However, their large mirror area makes them well suited for such high-time-resolution precision photometry measurements. Here we report two occultations of stars observed by the VERITAS Cherenkov telescopes with millisecond sampling, from which we are able to provide a direct measurement of the occulted stars' angular diameter at the $\leq0.1$ milliarcsecond scale. This is a resolution never achieved before with optical measurements and represents an order of magnitude improvement over the equivalent lunar occultation method. We compare the resulting stellar radius with empirically derived estimates from temperature and brightness measurements, confirming the latter can be biased for stars with ambiguous stellar classifications.Comment: Accepted for publication in Nature Astronom