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Simulation-based fatigue life assessment of a mercantile vessel
Ahmet H. Ertas,Ahmet F. Yilmaz 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.6
Despite the availability of other transport methods such as land and air transportations, marine transportation is the most preferred and widely used transportation method in the world because of its economical advantages. In service, ships experience cyclic loading. Hence, it can be said that fatigue fracture, which occurs due to cyclic loading, is one of the most critical failure modes for vessels. Accordingly, this makes fatigue failure prevention an important design requirement in naval architecture. Ingeneral, a ship structure contains many structural components. Because of this, structural modeling typically relies on Finite Element Analysis (FEA) techniques. It is possible to increase fatigue performance of the ship structures by using FEA in computer aided engineering environment. Even if literature papers as well as rules of classification societies are available to assess effect of fatigue cracks onto the whole ship structure, analytical studies are relatively scarce because of the difficulties of modeling the whole structure and obtaining reliable fatigue life predictions. As a consequence, the objective of this study is to improve fatigue strength of a mercantile vessel against fatigue loads via analytical method. For this purpose, the fatigue lifeof the mercantile vessel has been investigated. Two different type of fatigue assessment models, namely Coffin-Manson and Morrow Mean stress approaches, were used and the results were compared. In order to accurately determine the fatigue life of the ship, a nonlinear finite element analysis was conducted considering plastic deformations and residual stresses. The results of this study will provide the designer with some guidelines in designing mercantile vessels.
Xanthogranulomatous cholecystitis: a rare gallbladder pathology from a single-center perspective
Ahmet Gokhan Saritas,Mehmet Onur Gul,Zafer Teke,Abdullah Ulku,Ahmet Rencuzogullari,Ishak Aydin,Atilgan Tolga Akcam 대한외과학회 2020 Annals of Surgical Treatment and Research(ASRT) Vol.99 No.4
Purpose: The aim of this study was to review patients with xanthogranulomatous cholecystitis (XGC). Methods: A total of 79 patients diagnosed with XGC were included in the study. The criteria for XGC in the pathology specimens were the presence of histiocytes, cholesterol deposits, lipids, and focal or widespread wall enlargement. Results: Patients were diagnosed with XGC, of which 52 (65.8%) were male and 27 (34.2%) were female, creating a male-to-female ratio of 2:1. The mean age was 65.8 ± 14.3 years (range, 36–97 years). The most common presenting symptom was abdominal pain (63.3%), and the least common presenting symptom was jaundice (8.9%). Of the total, 25 patients were found to have pathological conditions with the potential to obstruct the bile duct or to slow bile flow. A frozen section examination was performed on 20 patients due to suspicion of a tumor by intraoperative macroscopic examination. However, no malignancy was detected in the cases who underwent a frozen section examination. An increase in wall thickness of the gallbladder was observed in 81.6% (n = 31) of the patients on computed tomography scans and in 81.8% (n = 18) of the patients on magnetic resonance imaging scans in which possible tumor lesions were reported, but no tumor was detected. Conclusion: It is difficult to diagnose XGC either preoperatively or intraoperatively, and further imaging methods are needed in the preoperative period other than ultrasonography. However, a definitive diagnosis depends exclusively on pathologic examination.
Ahmet Kale,Gulfem Basol,Ahmet C. Topcu,Elif C. Gundogdu,Taner Usta,Recep Demirhan 대한배뇨장애요실금학회 2021 International Neurourology Journal Vol.25 No.2
Entrapment neuropathy of the sciatic nerve and pudendal nerve are painful syndromes that are often overlooked by physicians. Laparoscopic surgical interventions for nerve entrapment syndromes of the posterior pelvis focus on removing the compression lesion with the purpose of eliminating the suspected cause of sciatica, as well as pudendal neuralgia. Herein, the authors report the rare event of sciatic and pudendal nerve entrapment, which was caused by aberrant vessels and a variant piriformis muscle bundle, as a seldom-diagnosed cause of sciatica and pelvic pain, for both neurosurgeons and neuropelveologists. The authors present the laparoscopic decompression technique for the pudendal and sciatic nerves by giving our technical “tips and tricks” enriched by a surgical video.
Ahmet A. Kiykim,Ahmet Camsari,Serkan Kahraman,Mustafa Arici,Bulent Altun,Dilek Cicek,Yunus Erdem,Unal Yasavul,Cetin Turgan,Sali Caglar,Aytekin Oto 연세대학교의과대학 2004 Yonsei medical journal Vol.45 No.2
Cardiovascular disease (CVD) is still the major cause of the morbidity and mortality in hemodialysis (HD) patients. The characteristics of major arterial changes, atherosclerosis and related risk factors in HD patients remain unclear. We aimed to evaluate the atherosclerotic process in asymptomatic HD patients and healthy volunteers, and to determine the association between the risk factor(s) and the atherosclerotic process in these groups. 92 HD patients (female: 43, male: 49) and 62 age and sex matched healthy volunteers (female: 27, male: 35) were enrolled in this study. Diabetics, smokers, and patients with symptomatic CVD were excluded. The right and left carotid intima-media thicknesses (CIMTs) were measured and plaque structures were studied by B-mode ultrasound. The mean CIMT in patients and control group were 0.79±0.16 mm and 0.54±0.09mm, respectively. Mean CIMT in HD patients was thicker (p<0.001) and the presence ratio of plaque was higher in patients group (n=38, %61.2 vs n=9, %17.3) (p<0.001). Calcified type of plaque was more frequent in HD patients than control group. Age (r=0.48, p<0.001), left ventricular mass (r=0.42, p<0.05), and homocysteine (r=0.46, p<0.01), mean hematocrit (r=-0.36, p<0.05), plasma CRP (r=0.50, p<0.001), ESR (r=0.43, p<0.01) and albumin (r= -0.34, p<0.05) levels were correlated with the CIMT measurements and plaque presence, significantly. -CIMT as an atherosclerotic process indicator is thicker in asymptomatic HD patients than healthy subjects. We concluded that in addition to various classical risk factors, uremic environment may also contribute to acceleration of the atherosclerotic process.
Durability of Sustained Virologic Response in Chronic Hepatitis C
( Ahmet Uyanikoglu ),( Sabahattin Kaymakoglu ),( Ahmet Danalioglu ),( Filiz Akyuz ),( Fatih Ermis ),( Binnur Pinarbasi ),( Kadir Demir ),( Fatih Besisik ),( Yilmaz Cakaloglu ) 대한소화기학회 2013 Gut and Liver Vol.7 No.4
Background/Aims: The aim of this study is to investigate the rate of sustained virologic response (SVR) in chronic hepatitis C patients receiving antiviral treatment. Methods: The files of patients with chronic hepatitis C treated with interferon±ribavirin between 1995 and 2009 were reviewed retrospectively. Six months after the end of treatment, patients with negative hepatitis C virus (HCV)-RNA (<50 IU/mL, as determined by the polymerase chain reaction method) were enrolled in the study. Results: The mean age of 196 patients (89 males) was 46.13±11.10 years (range, 17 to 73 years). In biopsies, the mean stage was 1.50±0.94; histological activity index was 7.18±2.43. In total, 139 patients received pegylated interferon (IFN) +ribavirin, 21 patients received classical IFN+ribavirin, and 36 patients received IFN alone. The HCV genotypes of 138 patients were checked: 77.5% were genotype 1b, and 22.5% were other genotypes. After achievement of SVR, the median follow-up period was 33.5 months (range, 6 to 112 months), and in this period relapse was only detected in two patients (1.02%) at 18 and 48 months after treatment. Conclusions: In total, 98.9% of patients with SVR in chronic hepatitis C demonstrated truly durable responses over the long-term follow-up period of 3 years; relapsed patients had intermittent or low-grade viremia. (Gut Liver 2013; 7:458-461)
Ahmet Goktug Ertem,Filiz Ozcelik,Haci Ahmet Kasapkara,Cemal Koseoglu,Serdal Bastug,Huseyin Ayhan,Cenk Sari,Nihal Akar Bayram,Emine Bilen,Tahir Durmaz,Telat Keles,Engin Bozkurt 대한심장학회 2016 Korean Circulation Journal Vol.46 No.6
Background and Objectives: In this study, we examined the role of inflammatory parameters in an apical mural thrombus with a reduced ejection fraction due to large anterior myocardial infarction (MI). Subjects and Methods: A total of 103 patients who had suffered from heart failure, 45 of whom had left ventricular apical thrombus (AT) after a large anterior MI, were enrolled in the study. A detailed clinical history was taken of each participant, biochemical inflammatory markers, which were obtained during admission, were analyzed and an echocardiographical and angiographical evaluation of specific parameters were performed. Results: There were no statistically significant differences in terms of age, gender, and history of hypertension, diabetes mellitus, and atrial fibrillation between both groups (p>0.05). Similarly there were no statistically significant differences in terms of biochemical and echocardiographic parameters (p>0.05). However, there were significant differences in terms of neutrophil lymphocyte ratio (p=0.032). After a multivariate regression analysis, neutrophil lymphocyte ratio (NLR) was an independent predictor of thrombus formation (ß: 0.296, p=0.024). The NLR >2.74 had a 78% sensivity and 61% specifity in predicting thrombus in patients with a low left ventricular ejection fraction. Conclusion: In this study, neutrophil lymphocyte ratios were significantly higher in patients with apical thrombus.
Simulation-based fatigue life assessment of a mercantile vessel
Ertas, Ahmet H.,Yilmaz, Ahmet F. Techno-Press 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.50 No.6
Despite the availability of other transport methods such as land and air transportations, marine transportation is the most preferred and widely used transportation method in the world because of its economical advantages. In service, ships experience cyclic loading. Hence, it can be said that fatigue fracture, which occurs due to cyclic loading, is one of the most critical failure modes for vessels. Accordingly, this makes fatigue failure prevention an important design requirement in naval architecture. In general, a ship structure contains many structural components. Because of this, structural modeling typically relies on Finite Element Analysis (FEA) techniques. It is possible to increase fatigue performance of the ship structures by using FEA in computer aided engineering environment. Even if literature papers as well as rules of classification societies are available to assess effect of fatigue cracks onto the whole ship structure, analytical studies are relatively scarce because of the difficulties of modeling the whole structure and obtaining reliable fatigue life predictions. As a consequence, the objective of this study is to improve fatigue strength of a mercantile vessel against fatigue loads via analytical method. For this purpose, the fatigue life of the mercantile vessel has been investigated. Two different type of fatigue assessment models, namely Coffin-Manson and Morrow Mean stress approaches, were used and the results were compared. In order to accurately determine the fatigue life of the ship, a nonlinear finite element analysis was conducted considering plastic deformations and residual stresses. The results of this study will provide the designer with some guidelines in designing mercantile vessels.
Alacacioglu, Ahmet,Ulger, Eda,Varol, Umut,Yildiz, Ibrahim,Salman, Tarik,Bayoglu, Vedat,Dirican, Ahmet,Demir, Lutfiye,Akyol, Murat,Yildiz, Yasar,Kucukzeybek, Yuksel,Ataman, Gorkem,Can, Huseyin,Alacacio Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.24
Background: We aimed to investigate anxiety, depression and sexual satisfaction levels and the effects of depression and anxiety upon the sexual satisfaction of Turkish breast cancer patients and their partners. Materials and Methods: Data were collected from one hundred breast cancer patients and their partners, using three forms: one covering information about socio-demographic characteristics of the patients, the Hospital Anxiety and Depression Scale (HADs) and the Golombok-Rust Inventory of Sexual Satisfaction (GRISS). Results: The frequencies, avoidance and touch subscores were statistically significantly high in the patients. Among those with high anxiety scores, the frequency, communication, satisfaction, touch, and anorgasmic subscale scores of GRISS were found to be significantly high. Among the partners whose anxiety scores were high, only the premature ejaculation subscale was statistically significant. It was determined that for partners with higher depression scores, the communication, satisfaction, avoidance, premature ejaculation and erectile dysfunction subscores of GRISS were statistically higher compared to partners with lower depression scores. Conclusions: Patients' quality of life may be increased by taking precautions to reduce their and their partners' psychosocial and psychosexual concerns.
Dirican, Ahmet,Kucukzeybek, Yuksel,Erten, Cigdem,Somali, Isil,Demir, Lutfiye,Can, Alper,Payzin, Kadriye Bahriye,Bayoglu, Ibrahim Vedat,Akyol, Murat,Yildiz, Yasar,Koseoglu, Mehmet,Alacacioglu, Ahmet,Ta Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.3
Background: Long-term survival is a problem with locally advanced and metastatic renal cell carcinomas. Sunitinib malate is an oral multitargeted tyrosine kinase inhibitor, but data on sunitinib use as a second line treatment in metastatic renal cell carcinoma (mRCC) are limited. Prognostic and predictive value of peripheral blood markers has been shown for many cancers. Materials and Methods: Efficacy and safety profiles of sunitinib after interferon alpha (IFN-${\alpha}$) were evaluated based on retrospective data for 23 patients with mRCC. Hematological parameters (neutrophils, lymphocytes, platelets, mean platelet volume, neutrophil/lymphocyte ratio, platelet/lymphocyte ratio) were recorded at the time of metastasis. It was evaluated whether hematological parameters were prognostic and predictive factors. Results: Median progression-free survival (PFS) time was 16.5 months (95%CI: 0-34.5). Median overall survival (OS) time was 25.7 months (95%CI: 10.8-40.0). Most common side effects were neutropenia (52.2%), stomatitis (26.1%) and hand-food syndrome (26.1%). PFS was found 3.13 vs 17.1 months in patients with neutrophil / lymphocyte ratio (NLR)>3 vs $NLR{\leq}3$ (p:0.012). Median OS was 6.96 vs 27.1 months in patients with NLR>3 vs $NLR{\leq}3$ (p:0.001).While 75% of patients who responded to sunitinib had $NLR{\leq}3$, in 72% of patients with no response to sunitinib NLR>3 was detected (p:0.036). The association between the Memorial Sloan-Kettering Cancer Center (MSKCC) criteria and NLR was statistically significant (p:0.022). Conclusions: Data on second line sunitinib treatment following cytokine in mRCC are limited. In our study, we observed second line sunitinib treatment following IFN-${\alpha}$ to be effective and tolerable. NLRappeared to have prognostic and predictive value.