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In this paper, we propose two methods for subspace based support vector machines (SS-SVMs) which are subspace based least squares support vector machines (SSLS-SVMs) and subspace based linear programming support vector machines (SSLP-SVMs): 1) optimum selection of the dictionaries of each class subspace from the standpoint of classification separability, and 2) speeding up training SS-SVMs. In method 1), for SSLS-SVMs, we select the dictionaries with optimized weights, and for SSLP-SVMs, we select the dictionaries without non-negative constraints. In method 2), the empirical feature space is obtained by using only the training data belonging to a class instead of using all the training data. Thus the dimension of the empirical feature space and training cost become lower. We demonstrate the effectiveness of the proposed methods over the conventional method for two-class bench mark datasets.

The use of antiplatelet therapy (APT) and/or anticoagulant therapy (ACT) continues to increase due to the aging population. Because the management of patients with acute cholecystitis receiving APT/ACTis still unclear, surgeons are sometimes faced with the difficult decision to delay surgery. We aimed to analyze characteristics and surgical risks of patients who underwent emergency cholecystectomy for acute cholecystitis without discontinuing APT. We conducted a retrospective review of 113 patients between 2006 and 2014. Treatment outcomes among 13 patients who underwent cholecystectomy without discontinuing APT (the cAPT group), 11 patients who discontinued APT and ACT (the D group), and 89 patients who did not receive preoperative APT and/or ACT (the No APT group) were compared. There were no significant differences in intraoperative blood loss, conversion to open surgery, and bleeding-related complications. However, the incidence of intraoperative blood transfusion was higher in the cAPT group (P = 0.04). They presented with severe local inflammation; thus, it was difficult to stop bleeding from the gallbladder bed. Hemostatic tools for liver surgery were used to control bleeding. Emergency cholecystectomy was tolerable for patients with acute cholecystitis while continuing APT. However, in case of severe local inflammation, there is a greater risk for massive hemorrhage.