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Interest in stratospheric aerosol and its role in climate have increased over the last decade due to the observed increase in stratospheric aerosol since 2000 and the potential for changes in the sulfur cycle induced by climate change. This review provides an overview about the advances in stratospheric aerosol research since the last comprehensive assessment of stratospheric aerosol was published in 2006. A crucial development since 2006 is the substantial improvement in the agreement between in situ and space-based inferences of stratospheric aerosol properties during volcanically quiescent periods. Furthermore, new measurement systems and techniques, both in situ and space based, have been developed for measuring physical aerosol properties with greater accuracy and for characterizing aerosol composition. However, these changes induce challenges to constructing a long-term stratospheric aerosol climatology. Currently, changes in stratospheric aerosol levels less than 20% cannot be confidently quantified. The volcanic signals tend to mask any nonvolcanically driven change, making them difficult to understand. While the role of carbonyl sulfide as a substantial and relatively constant source of stratospheric sulfur has been confirmed by new observations and model simulations, large uncertainties remain with respect to the contribution from anthropogenic sulfur dioxide emissions. New evidence has been provided that stratospheric aerosol can also contain small amounts of nonsulfate matter such as black carbon and organics. Chemistry-climate models have substantially increased in quantity and sophistication. In many models the implementation of stratospheric aerosol processes is coupled to radiation and/or stratospheric chemistry modules to account for relevant feedback processes.

A randomized comparative study was made in New Zealand of 3 models of copper IUDs, the Nova-T, MLCu375 and MLAgCu250, with interval acceptors. Completing 3 years of use, there were 608 Nova-T (14,011 woman-months), 586 MLCu375 (14,161 woman-months) and 596 MLAgCu250 (14,614 woman-months). At 3 years, loss to follow-up was 5.2% for the Nova-T, 5.1% for the MLCu375 and 4.1% for the MLAgCu250. The Multiloads were significantly easier to insert and were preferred by the operators, as the insertion technique for the Nova-T was complicated. However, the Nova-T was significantly easier to remove. There was one perforation with a Nova-T in a puerperal breastfeeding woman. In the only 2 parameters that are comparable between series, accidental pregnancy and expulsion [1], the Multiloads have been shown to be superior with higher relevant continuation rates. At 3 years, the MLCu375 had a significantly lower accidental pregnancy rate and higher relevant continuation rate. The results obtained with the Nova-T are similar to those of the WHO study [2]. The MLCu375, with its potential for use up to 5 years, has been shown to be the superior device.

A randomized comparative study was made in New Zealand of three models of copper IUDs, the Nova-T, MLCu375 and MLAgCu250, with interval acceptors. At 1 year, the Multiloads (MLs) had lower net termination rates for accidental pregnancy, expulsion, pain/bleeding, other medical removals and infections (use-related terminations) than the Nova-T. These rates were significantly lower for the MLAgCu250 than the Nova-T for accidental pregnancy, expulsion and infection. The MLCu375 had significantly fewer removals for pain/bleeding and for other medical removals than the Nova-T. The MLAgCu250 had a significantly lower accidental pregnancy rate than the MLCu375. The Multiloads had significantly higher relevant use-related continuation rates than the Nova-T.

Streptococcus penumoniae is a major human pathogen responsible for respiratory tract infections, septicemia, and meningitis and continues to produce numerous cases of disease with relatively high mortalities. S. pneumoniae encodes up to three sialidases, NanA, NanB, and NanC, that have been implicated in pathogenesis and are potential drug targets. NanA has been shown to be a promiscuous sialidase, hydrolyzing the removal of Neu5Ac from a variety of glycoconjugates with retention of configuration at the anomeric center, as we confirm by NMR. NanB is an intramolecular trans-sialidase producing 2,7-anhydro-Neu5Ac selectively from α2,3-sialosides. Here, we show that the first product of NanC is 2-deoxy-2,3-didehydro-N-acetylneuraminic acid (Neu5Ac2en) that can be slowly hydrated by the enzyme to Neu5Ac. We propose that the three pneumococcal sialidases share a common catalytic mechanism up to the final product formation step, and speculate on the roles of the enzymes in the lifecycle of the bacterium.