We have discovered lines of highly ionized fluorine (F  and F ) in the far-UV spectra of extremely hot (Teff=85 000–150 000 K) post-AGB stars. Our sample comprises H-rich central stars of planetary nebulae as well as H-deficient PG1159 stars. We performed non-LTE calculations and find strong F overabundances (up to 10−4 by mass, i.e., 250 times solar) in a number of PG1159 stars, while F is ...

When treating infertile couples by assisted reproductive technologies (ART), all aspects of their care in individual clinics should be evaluated frequently. Results should then be compared with other clinics offering similar treatment. Evaluation of possible adverse longterm outcomes can be achieved by pooling results from individual clinics in national, regional and international registers and...

Although long term survivors are well documented, infants with the autosomal trisomies 18 (Edwards syndrome) or 13 (Patau syndrome) usually die in the first few days or weeks of life. Accurate estimates of life expectancy are few, particularly in the case of trisomy 13. There have been six population surveys of survival in trisomy 18, comprising 430 unselected cases. In contrast there have been...