Role of surface microgeometries on electron escape probability and secondary electron yield of metal surfaces.

The influence of microgeometries on the Secondary Electron Yield (SEY) of surfaces is investigated. Laser written structures of different aspect ratio (height to width) on a copper surface tuned the SEY of the surface and reduced its value to less than unity. The aspect ratio of microstructures was methodically controlled by varying the laser parameters. The results obtained corroborate a recent theoretical model of SEY reduction as a function of the aspect ratio of microstructures. Nanostructures - which are formed inside the microstructures during the interaction with the laser beam - provided further reduction in SEY comparable to that obtained in the simulation of structures which were coated with an absorptive layer suppressing secondary electron emission.

Gemcitabine as single agent therapy in advanced non small cell lung cancer and quality of life in the elderly.

BACKGROUND: The aim of this study is to test the efficacy of gemcitabine as single agent therapy in advanced non-small cell lung cancer in the elderly by the evaluation of the clinical response, the survival increase and the quality of life. METHODS: Nineteen patients (age >65 years) with a PS >2, bearing an advanced non-small cell lung cancer (IIIb-IV) not treated with chemotherapy before, were charged between December 1996 and December 1998. Sixteen patients were treated with gemcitabine at the dose of 1000 mg/mq 1-8-15 every 28 days. CT scan, X-rays and skeletal scintigraphy were used in the evaluation of the therapeutic response. The toxicity was estimated by following WHO indexes. The quality of life and the modification of the specific symptoms were estimated by particular tests (Spitzer Index, IADL, EORTC-LC13). RESULTS: One complete response (6%), 4 partial responses (25%), 7 cases of illness stabilization (43%), 4 cases of illness progression, were shown. One year of survival was found in 43% of cases with a 14 week of therapeutic response and a global survival ratio of 12.4 weeks. Only 2 cases (12.5) of medium grade G3-leucopenia were found. All patients improved their quality of life (IADL and Spitzer indexes) with reduction of symptoms, (EORTC-LC13) and increase of self-agin and relationships. CONCLUSIONS: The effectiveness of gemcitabine as single agent therapy as not yet been tested due to the scanty number of patients, nevertheless it must be considered in relation to the improvement of the patient s quality of life.