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The investigators report the analysis of coupons of mineral flint and chert of archaeological interest and various provenances in comparison to uranium-doped glass, mineral single crystal quartz and thermally grown silicon dioxide. The measurements are motivated by a desire to quantify the concentration of uranium in lithic sources of paleoindian artifacts; uranyl oxide is suspected to be the origin of the observed UV fluorescence. Rutherford backscattering spectrometry (RBS) confirmed the concentration of uranium in these minerals is on the order of tens of ppm as γ-ray spectroscopy analysis suggested previously. The level of uranium present does not correlate, however, with the observed fluorescence behaviors. Optical effects such as absorption and quenching due to other impurities is suspected to be the cause of the differences.

Through statistical analysis of atomic force micrographs of sputtered-silicon films, we examine the determination of surface roughness parameters, and how this determination is affected by probe characteristics, such as sharpness and aspect ratio. We compare values for the roughness exponent, a, and the lateral correlation length, n, calculated from micrographs obtained with multiple standard atomic force microscopy (AFM) probes in contact and noncontact modes, as well as from micrographs obtained with a multiwalled-nanotube-enhanced AFM probe. The sharper, loweraspect-ratio nanotube probe is expected to provide a truer picture of the roughness parameters for these films. Using the nanotube probe, we obtained a ¼ 0:61 � 0:02, as compared to a � 0:83 obtained with conventional probes. We have also found the nanotube probe is able to detect a smaller lateral correlation length compared to that of the conventional AFM probes. 2002 Elsevier Science B.V. All rights reserved.

were recorded including rates of endoleaks, neurological complication, repeat procedures, and left arm claudication. Results: Median follow up was 552.5 days. LSCA was embolized in 41/104 (39%) of procedures. Indication for TEVAR in the embolized and non-embolized groups was dissection in 23/41 (56%) and 28/63 (44%), aneurysm 11/41 (26%) and 19/63 (30%), pseudoaneurysm 6/41 (14%) and 4/ 64 (6%), transection 1/41 (2%) and 9/64 (14%), and penetrating ulcers 0/41 (0%) and 3/64 (4%), respectively. The cerebrovascular accident (CVA) rate was 7/41 (17%) and 7/63(11%) and paralysis rate was 0/41 (0%) and 1/63 (2%) for the embolized and non-embolized groups respectively. The endoleak rate was 24/41 (58%) for the embolized group; 7/41 (17%) were persistent and resulted in aneurysm sac enlargement (6 type Ia and 1 type II endoleak) treated with sac embolization (n1⁄45), stent graft extension (n1⁄41), or surgical repair (n1⁄41). Endoleak rate was 22/63 (35%) for the non-embolized group; 5/63 (8%) were persistent and resulted in aneurysm sac enlargement (3 type Ia and 2 type II endoleaks) treated with LSCA embolization (n1⁄44) and both LSCA and sac embolization (n1⁄41). LSCA was covered without a carotid-subclavian bypass in 58/104 (56%). CVA rates for bypass and no bypass groups were 5/46 (11%) and 6/58 (10%) and paralysis rates were 1/46 (2%) and 0%, respectively. 10/58 (17%) patients required a subsequent carotid-subclavian bypass for left arm claudication. Conclusion: Coverage of the left subclavian artery during endovascular repair of the thoracic aorta is feasible with low complication rates. Embolization of the LSCA may be required to prevent or treat endoleaks.