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Design and simulation of double-mass dynamic vibration absorber with residual vibration mode
Nanako Miura,Naoki Matsuo,Saiji Fukada,Sawako Tomioka 대한기계학회 2023 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.37 No.6
This paper presents a double-mass dynamic vibration absorber (DVA) that rapidly reduces the motion of the object to be damped (main system) and converts it to the motion of the DVA. In this way, the DVA attenuates the vibration of the main system. A DVA is usually designed to improve the resonance amplitude and convergence time of the main system vibration, and the kinetic energy of the main system is dissipated as heat in the damping element of the DVA. We describe a novel configuration consisting of two DVAs connected by a spring and an inerter. This new structure enables a rapid response reduction of the main system and residual vibration in the DVA. By tuning the responses of both the main system and the DVA, two vibration modes can be realized: a damping mode and a residual vibration mode. The proposed device is optimized using a genetic algorithm and applied to a bridge to demonstrate its performance.
Masaya Uno,Rie Matsuo,Naoki Maezawa,Tomoyasu Kato 대한산부인과학회 2023 Obstetrics & Gynecology Science Vol.66 No.4
Objective We evaluated the usefulness of human epididymis protein 4 (HE4), a tumor marker, during and after treatment in patients with ovarian cancer (OC). Methods We included Japanese patients newly diagnosed with OC treated at the National Cancer Center Hospital between 2014 and 2021. The HE4 levels were measured in the serum stored during diagnosis. To evaluate the concordance between HE4 and the imaging results, we employed sequential pairs of blood sampling points and the results of imaging examinations. We compared the timing of the elevated HE4 levels, imaging diagnoses, and elevated cancer antigen 125 (CA125) levels in patients with recurrence. The Ethics Review Committee of our institution (2021-056) reviewed this study. Results Forty-eight patients with epithelial OC were eligible for enrollment. The sensitivity, specificity, and positive and negative predictive values of HE4 (criterion, 70 pmol/L) for disease progression during the follow-up period were 79.4%, 59.1%, 32.5%, and 92.0%, respectively (time point, n=317). We evaluated the relationship between HE4 and CA125 variability and disease status (recurrence or no recurrence). For recurrence, the sensitivity and negative predictive value of HE4 (criterion, 70 pmol/L), CA125 (criterion, 35 U/mL), and combination of HE4 and CA125 were 77.8%, 85.2%, and 92.6% and 75.0%, 82.6%, and 88.9%, respectively (n=48). Among the 27 patients who exhibited recurrence, 16 and nine showed earlier increased HE4 levels than the relevant imaging and CA125 levels, respectively. Conclusion HE4 may be a valuable marker for follow-up during and after OC therapy. A complementary role for HE4 and CA125 measurements was suggested for follow-up observations.
Ioku Tetsuya,Ohshima Tomotaka,Yokota Mao,Matsuo Naoki,Miyachi Shigeru 대한신경중재치료의학회 2023 Neurointervention Vol.18 No.3
Transarterial embolization using Onyx is a well-established treatment for dural arteriovenous fistulas (DAVFs). However, complications can arise when Onyx migrates into the venous side, impairing the draining veins. We encountered a case where Onyx, injected through the arterial side, strayed into the jugular vein, forming a hairball-like structure. Our study aimed to investigate the underlying mechanism of this unusual phenomenon. We postulated that Onyx precipitates into thread-like shapes when passing through extremely narrow openings. To test this, we extruded Onyx from a syringe through a 27-gauge needle into a silicone tube with flowing water. By varying the flow speed, we observed the hardening behavior of Onyx. Under slow flow, the extruded Onyx quickly solidified at the needle tip, forming a round mass. Conversely, high-speed flow resulted in Onyx being dispersed as small pieces. We successfully replicated the formation of “Onyx threads” under continuous slow flow conditions, similar to our case. This phenomenon occurs when Onyx unexpectedly migrates to the draining vein through a tiny opening during transarterial embolization for arteriovenous shunt diseases. Early recognition and appropriate measures are necessary to prevent occlusive complications in the draining veins and the pulmonary system.
Unruptured Paraclinoid Carotid Aneurysms Occur More Frequently in Younger Ages
Shigeru Miyachi,Reo Kawaguchi,Tomotaka Ohshima,Naoki Matsuo 대한신경중재치료의학회 2021 Neurointervention Vol.16 No.2
Purpose We investigated the age distribution of cerebral saccular aneurysms in various locations to clarify the differences by location and discuss the mechanism of formation. Materials and Methods We retrospectively assessed clinical material obtained from 1,252 unruptured aneurysms treated with endovascular embolization between 2004 and 2019. Age, sex, laterality, and size were investigated by the location of aneurysms, classified as cavernous internal carotid artery (ICA), paraclinoid ICA, supraclinoid ICA, anterior communicating artery, anterior cerebral artery, middle cerebral artery, basilar artery complex, and posterior inferior cerebellar artery. Paraclinoid aneurysms were subclassified into 3 patterns according to their projecting direction: S-type, with superior protrusion; M-type, with medial protrusion; and P-type, with posteroinferior protrusion. Results There was no significant difference by location for sex, laterality, and size. The mean age of patients with paraclinoid aneurysms (56.5 years old) was significantly lower than that of other aneurysm patients (64.3 years old). Notably, 40% of the patients with M-type aneurysms were <50 years old. This percentage was significantly higher than that of aneurysms at other locations (P<0.05). Conclusion We found a young female predominance for patients with paraclinoid carotid aneurysms. This study may suggest that congenital factors contribute to paraclinoid aneurysm formation as well acquired factors, such as hemodynamic stress, atherosclerotic wall damage, and local inflammation.
Yasuyuki Nakamura,Daisuke Hokuto,Fumikazu Koyama,Yasuko Matsuo,Takeo Nomi,Takahiro Yoshikawa,Naoki Kamitani,Tomomi Sadamitsu,Takeshi Takei,Yayoi Matsumoto,Yosuke Iwasa,Kohei Fukuoka,Shinsaku Obara,Tak 대한대장항문학회 2021 Annals of Coloproctolgy Vol.37 No.5
Purpose: Primary tumor location of colon cancer has been reported to affect the prognosis after curative resection. However, some reports suggested the impact was varied by tumor stage. This study analyzed the prognostic impact of the sidedness of colon cancer in stages II, III, and liver metastasis after curative resection using propensity-matched analysis.Methods: Right-sided colon cancer was defined as a tumor located from cecum to splenic flexure, while any more distal colon cancer was defined as left-sided colon cancer. Patients who underwent curative resection at Nara Medical University hospital between 2000 and 2016 were analyzed.Results: There were 110 patients with stage II, 100 patients with stage III, and 106 patients with liver metastasis. After propensity matching, 28 pairs with stage II and 32 pairs with stage III were identified. In the patients with stage II, overall survival (OS) and recurrence-free survival (RFS) were not significantly different for right- and left-sided colon cancers. In the patients with stage III, OS and RFS were significantly worse in right-sided colon cancer. In those with liver metastasis, OS of right-sided colon cancer was significantly worse than left-sided disease, while RFS was similar. Regarding metachronous liver metastasis, the difference was observed only in the patients whose primary colon cancer was stage III. In each stage, significantly higher rate of peritoneal recurrence was found in those with right-sided colon cancer.Conclusion: Sidedness of colon cancer had a significant and varied prognostic impact in patients with stage II, III, and liver metastasis after curative resection.
A Novel Training Method for Endovascular Clot Retrieval Using a Portable Vascular Model and Red Film
Ioku Tetsuya,Ohshima Tomotaka,Kawaguchi Reo,Matsuo Naoki,Miyachi Shigeru 대한신경중재치료의학회 2024 Neurointervention Vol.19 No.2
Hands-on training is a crucial part of education in neuroendovascular treatment to ensure safe and rapid acquisition of techniques. However, there is a significant gap between training and actual clinical practice. This study will introduce innovations for more practical thrombus retrieval training that was developed in this process. A Smart Vascular Model 3 in 1 was used. A pink pseudothrombus was inserted into the M1 (horizontal segment of the middle cerebral artery) section of the model. Then, a “red underlay” purchased at a stationery store was placed to cover the proximal part of M1 and beyond so that the pseudothrombus was not visible. The thrombus was retrieved during training by looking for the location of the thrombus based on the behavior and resistance of the tip of the guidewire and deployment of the stent retriever. The participants were required to have detailed observation skills and precise manipulation skills using a red film to prevent the direct visualization of the pseudothrombus. The implementation of this innovation to the previous hands-on training made the training more practical and effective. If the exact thrombus location can be determined by the behavior of the wire tip, the device’s capabilities can be maximized, and rapid retrieval can be expected. It could also reduce complications, as unnecessary peripheral guidance of the device could be avoided.