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        An assessment of machine learning models for slump flow and examining redundant features

        Ramazan Ünlü 사단법인 한국계산역학회 2020 Computers and Concrete, An International Journal Vol.25 No.6

        Over the years, several machine learning approaches have been proposed and utilized to create a prediction model for the high-performance concrete (HPC) slump flow. Despite HPC is a highly complex material, predicting its pattern is a rather ambitious process. Hence, choosing and applying the correct method remain a crucial task. Like some other problems, prediction of HPC slump flow suffers from abnormal attributes which might both have an influence on prediction accuracy and increases variance. In recent years, different studies are proposed to optimize the prediction accuracy for HPC slump flow. However, more state-of-the-art regression algorithms can be implemented to create a better model. This study focuses on several methods with different mathematical backgrounds to get the best possible results. Four well-known algorithms Support Vector Regression, M5P Trees, Random Forest, and MLPReg are implemented with optimum parameters as base learners. Also, redundant features are examined to better understand both how ingredients influence on prediction models and whether possible to achieve acceptable results with a few components. Based on the findings, the MLPReg algorithm with optimum parameters gives better results than others in terms of commonly used statistical error evaluation metrics. Besides, chosen algorithms can give rather accurate results using just a few attributes of a slump flow dataset.

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        Antithrombotic effect of epigallocatechin gallate on the patency of arterial microvascular anastomoses

        Murat İğde,Mehmet Onur Öztürk,Burak Yaşar,Mehmet Hakan Bulam,Hasan Murat Ergani,Ramazan Erkin Ünlü 대한성형외과학회 2019 Archives of Plastic Surgery Vol.46 No.3

        Background Microvascular anastomosis patency is adversely affected by local and systemic factors. Impaired intimal recovery and endothelial mechanisms promoting thrombus formation at the anastomotic site are common etiological factors of reduced anastomosis patency. Epigallocatechin gallate (EGCG) is a catechin derivative belonging to the flavonoid subgroup and is present in green tea (Camellia sinensis). This study investigated the effects of EGCG on the structure of vessel tips used in microvascular anastomoses and evaluated its effects on thrombus formation at an anastomotic site. Methods Thirty-six adult male Wistar albino rats were used in the study. The right femoral artery was cut and reanastomosed. The rats were divided into two groups (18 per group) and were systemically administered either EGCG or saline. Each group were then subdivided into three groups, each with six rats. Axial histological sections were taken from segments 1 cm proximal and 1 cm distal to the microvascular anastomosis site on days 5, 10, and 14. Results Thrombus formation was significantly different between the EGCG and control groups on day 5 (P=0.015) but not on days 10 or 14. The mean luminal diameter was significantly greater in the EGCG group on days 5 (P=0.002), 10 (P=0.026), and 14 (P=0.002). Intimal thickening was significantly higher on days 5 (P=0.041) and 10 (P=0.02). Conclusions EGCG showed vasodilatory effects and led to reduced early thrombus formation after microvascular repair. Similar studies on venous anastomoses and random or axial pedunculated skin flaps would also contribute valuable findings relevant to this topic.

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