Challenges in quantifying biosphere-atmosphere exchange of nitrogen species.

Recent research in nitrogen exchange with the atmosphere has separated research communities according to N form. The integrated perspective needed to quantify the net effect of N on greenhouse-gas balance is being addressed by the NitroEurope Integrated Project (NEU). Recent advances have depended on improved methodologies, while ongoing challenges include gas-aerosol interactions, organic nitrogen and N(2) fluxes. The NEU strategy applies a 3-tier Flux Network together with a Manipulation Network of global-change experiments, linked by common protocols to facilitate model application. Substantial progress has been made in modelling N fluxes, especially for N(2)O, NO and bi-directional NH(3) exchange. Landscape analysis represents an emerging challenge to address the spatial interactions between farms, fields, ecosystems, catchments and air dispersion/deposition. European up-scaling of N fluxes is highly uncertain and a key priority is for better data on agricultural practices. Finally, attention is needed to develop N flux verification procedures to assess compliance with international protocols.

Epithelial malignancies of the salivary glands: clinical experience of a single institution-a review.

In this retrospective study we give a clinical review of our experience with different subtypes of salivary gland cancer. Between January 1983 and December 2002, a total of 155 patients with carcinomas of the salivary glands received initial treatment at the Department of Oral and Maxillofacial Surgery, Hanover Medical School. There were 79 (51.0%) adenoid cystic carcinomas, 42 (27.1%) mucoepidermoid carcinomas, 12 (7.7%) adenocarcinomas, 10 (6.5%) polymorphous adenocarcinomas and 12 (7.7%) other tumor entities of smaller number. Complete resection was reached for 63.5% of patients with high grade carcinomas and for 80.0% of patients with low grade carcinomas. 26.2% of patients with high grade carcinomas and 13.3% of patients with low grade carcinomas received postoperative radiation. Overall survival rates at 5, 10 and 15 years were 65.9, 48.0 and 39.8% with significant difference for patients with high grade and low grade carcinomas. Histopathologic subtype, tumor stage and margin status significantly influenced prognosis. Statistically, we were not able to demonstrate a positive effect for postoperative radiation. In the future, patients with salivary gland carcinomas should be randomised for prospective multicentric clinical trials, which could provide reliable information about adjuvant treatment modalities and their results even for rare subtypes of salivary gland cancer.