Embolectomy procedures can be performed under conditions to effectively remove thrombusemboli with little risk of injuring the vessel wall and while effectively capturing and removing emboli. The sub-exlons are then used to scan for exlons, which are combinations of horizontal and vertical sub-exlons that make up the four possible types of corner. Each of the upper rails includes a first notch and a second notch. After the extraction of the contour pixels, the procedure selects one of the at least two variable-size dots, which is to be created in each of the extracted contour pixels, based on information on a higher resolution than the printing resolution. A treated feedstock substantially free of said polar compounds is withdrawn from the adsorption zone and fed to an alkylation zone for contact under liquid phase alkylation conditions with an alkylating agent in the presence of an alkylation catalyst. A first set of inputoutput requests is satisfied from the first file system while the second file system is undergoing defragmentation.