Color characterization of coatings with diffraction pigments.

Coatings with diffraction pigments present high iridescence, which needs to be characterized in order to describe their appearance. The spectral bidirectional reflectance distribution functions (BRDFs) of six coatings with SpectraFlair diffraction pigments were measured using the robot-arm-based goniospectrophotometer GEFE, designed and developed at CSIC. Principal component analysis has been applied to study the coatings of BRDF data. From data evaluation and based on theoretical considerations, we propose a relevant geometric factor to study the spectral reflectance and color gamut variation of coatings with diffraction pigments. At fixed values of this geometric factor, the spectral BRDF component due to diffraction is almost constant. Commercially available portable goniospectrophotometers, extensively used in several industries (automotive and others), should be provided with more aspecular measurement angles to characterize the complex reflectance of goniochromatic coatings based on diffraction pigments, but they would not require either more than one irradiation angle or additional out-of-plane geometries.

Impact of antiplatelet therapy in the development of severe ischemic complications and in the outcome of patients with giant cell arteritis.

OBJECTIVE: To evaluate whether concomitant treatment with low-dose aspirin or other antiplatelet agents have an impact on the risk of severe ischemic complications and in the outcome of patients with giant cell arteritis (GCA). METHODS: A retrospective follow-up study of an unselected population of 121 patients with GCA. RESULTS: Thirty-seven patients (30.5%) received antiplatelet therapy before the onset of GCA symptoms and continued taking it during the corticosteroid treatment (30 received aspirin and 7 other antiplatelet agents). No statistically significant reduction in the incidence of ischemic manifestations (including jaw claudication, visual manifestations, cerebrovascular accidents, ischemic heart disease, and limb claudication due to large artery stenosis) was observed in this group compared with the remaining patients. When we analyzed follow-up data, we found no significant differences between groups in terms of frequency of relapses and percentage of patients recovered from GCA. Corticosteroid requirements among patients in long-lasting remission were lower in those under antiplatelet therapy, but this reduction was fairly modest, statistically non significant and thus of uncertain clinical significance. Similar results were found when only aspirin exposed patients (n=30) were compared to non-exposed patients. Logistic regression analysis showed that antiplatelet therapy (p=0.54, OR 1.31; 95% CI: 0.54-3.19) had not an independent protective effect against ischemic events when adjusted for age, sex, and the presence of atherosclerotic risk factors. CONCLUSION: We did not observe a significant benefit derived from the use of antiplatelet therapy in either the incidence of severe ischemic events or the disease outcome. Although our results do not discard a potential therapeutic effect of high-dose aspirin, they do not confirm its suggested protective effect in preventing ischemic complications when used at antiplatelet doses.