Mother-of-pearl cloud particle size and composition from aircraft-based photography of coloration and lidar measurements.

During a Stratospheric Aerosol and Gas (SAGE)-III Ozone Loss and Validation Experiment (SOLVE)-II science flight on 4 February 2003, a mother-of-pearl cloud over Iceland was underflown by the NASA DC-8 and measured with the lidars onboard. In addition, color photos were taken during the approach. Aided by extensive modeling of cloud coloration, the main results of the analysis of this unique data set are: (1) the polar stratospheric cloud was mountain wave-induced and of type II; (2) the spectacular color display was caused by ice particles with sizes around 2 µm.

Unprecedented Arctic ozone loss in 2011.

Chemical ozone destruction occurs over both polar regions in local winter-spring. In the Antarctic, essentially complete removal of lower-stratospheric ozone currently results in an ozone hole every year, whereas in the Arctic, ozone loss is highly variable and has until now been much more limited. Here we demonstrate that chemical ozone destruction over the Arctic in early 2011 was--for the first time in the observational record--comparable to that in the Antarctic ozone hole. Unusually long-lasting cold conditions in the Arctic lower stratosphere led to persistent enhancement in ozone-destroying forms of chlorine and to unprecedented ozone loss, which exceeded 80 per cent over 18-20 kilometres altitude. Our results show that Arctic ozone holes are possible even with temperatures much milder than those in the Antarctic. We cannot at present predict when such severe Arctic ozone depletion may be matched or exceeded.

A model for the behavior of beta-hCG after evacuation of hydatidiform moles.

OBJECTIVES: The objective of this study is to develop a physical model of the behavior of beta-hCG following the complete evacuation of a hydatidiform mole. Because hCG is an excellent marker for continued trophoblastic activity, the model can be used for early detection of persistent sites. METHOD: The model was developed from analysis of the post surgical hCG decrease in a patient with Stage III gestational trophoblastic neoplasia. As found in previous molar pregnancy studies, hCG follows a log-linear decrease after resolution. In contrast to those studies, however, we assume that the decrease can be explained by the dilution of the residual hCG from two different tissue reservoirs, a tissue reservoir with a half-life of approximately 4 days and a reservoir with a longer half-life, in this case approximately 18 days. RESULTS: Simple dilution of two tissue reservoirs explains behavior of hCG following tumor removal. The model also explains the hCG decrease in a larger study of Japanese and Dutch women following the evacuation of uneventful hydatidiform moles. CONCLUSIONS: Following an initial rapid drop in hCG after resolution of the mole, the patient should experience a slower drop associated with the dilution of residual hCG in the deep tissue reservoir. This is normal. The physical model suggests that even earlier detection of chemotherapy resistant persistent trophoblastic disease is possible if the patient's decrease in hCG is slower than a log-linear fit to the patient's previous data. The results also suggest an alternative approach to processing patient statistics in analysis of carcinomas with large variations in the tumor marker concentrations.