Ticari Bilimler Fakültesi / Faculty of Commercial Science
Permanent URI for this collectionhttps://hdl.handle.net/11727/2074
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Item Temel istatistik yöntemleri(2018) Cula, Serpil; Muluk, ZehraItem Young tableaux and Arf partitions(2019) Tutas, Nesrin; Karakas, Halil İbrahim; Gumusbas, NihalThe aim of this work is to exhibit some relations between partitions of natural numbers and Arf semigroups. We also give characterizations of Arf semigroups via the hook-sets of Young tableaux of partitions.Item Staff Task-Based Shift Scheduling Solution with an ANP and Goal Programming Method in a Natural Gas Combined Cycle Power Plant(2019) Ozder, Emir Huseyin; Ozcan, Evrencan; Eren, Tamer; 0000-0002-1895-8060; Q-4772-2017Shift scheduling problems (SSPs) are advanced NP-hard problems which are generally evaluated with integer programming. This study presents an applicable shift schedule of workers in a large-scale natural gas combined cycle power plant (NGCCPP), which realize 35.17% of the total electricity generation in Turkey alone, as at of the end of 2018. This study included 80 workers who worked three shifts in the selected NGCCPP for 30 days. The proposed scheduling model was solved according to the skills of the workers, and there were nine criteria by which the workers were evaluated for their abilities. Analytic network process (ANP) is a method used for obtaining the weights of workers' abilities in a particular skill. These weights are used in the proposed scheduling model as concepts in goal programming (GP). The SSP-ANP-GP model sees employees' everyday preferences as their main feature, bringing high-performance to the highest level, and bringing an objective functionality, and lowering the lowest success of daily choice. At the same time, the model introduced large-scale and soft constraints that reflect the nature of the shift requirements of this program by specifying the most appropriate program. The required data were obtained from the selected NGCCPP and the model solutions were approved by the plant experts. The SSP-ANP-GP model was resolved at a reasonable time. Monthly acquisition time was significantly reduced, and the satisfaction of the employees was significantly increased by using the obtained program. When past studies were examined, it was determined that a shift scheduling problem of this size in the energy sector had not previously been studied.Item Employee deviant behavior: role of culture and organizational relevant support(2019) Kalemci, R. Arzu; Kalemci-Tuzun, Ipek; Ozkan-Canbolat, Ela; 0000-0001-6979-2040; ABB-5350-2020Purpose The purpose of this paper is to increase the knowledge and understanding of organizational and supervisory support in the context of employee deviant workplace behavior (DWB) by examining the potential associations of employees' cultural value orientations. This paper aims to: clarify DWB; review perceived organizational support (POS) and perceived supervisory support (PSS); discuss the meaning of employees' cultural value orientations (individualism-collectivism, power distance and paternalism); use the fuzzy logic model to analyze relationships between DWB and POS, as well as PSS and employees' cultural value orientations. Design/methodology/approach This research applies a fuzzy-set qualitative comparative analysis. Findings The results show the role of employee perceived organizational and supervisory support and cultural dimension (power distance and paternalism) configurations on employee DWB. Originality/value The main originality of this study is to further increase the understanding of organizational and supervisory support in the context of employee DWB by examining the potential associations of employees' cultural value orientations. This study extends the previous research by providing evidence that organizational and supervisory support influences employees' DWB.Item Sustainable Personnel Scheduling Problem Optimization in a Natural Gas Combined-Cycle Power Plant(2019) Ozder, Emir Huseyin; Ozcan, Evrencan; Eren, Tamer; 0000-0002-1895-8060; Q-4772-2017This paper deals with a sustainable personnel scheduling problem of personnel working in a large-scale natural gas combined-cycle power plant in Turkey. The proposed model focuses on employee complaints due to unfair work schedules and the results of balanced assignments based on power plant interruptions. Eighty personnel work in three shifts at this natural gas combined-cycle power plant. The model is solved with respect to some of the workers' skills, and there are 20 criteria regarding skills. The analytic network process method is used to get the weights of workers' skills, which are calculated and included in the model. Goal programming is used in this paper. Our proposed model gives cost minimization and fair work schedules for the power plant. Compared with the literature, the number and set of criteria are unique in terms of personnel competency in the energy sector. Minimizing cost and imbalanced assignments was achieved by the proposed model for the first time without considering the sector.Item Platform-switched implants vs platform-matched implants placed in different implant-abutment interface positions: A prospective randomized clinical and microbiological study(2019) Uraz, Ahu; Isler, Sila C.; Cula, Serpil; Tunc, Samet; Yalim, Mehmet; Cetiner, Deniz; 31808297Background Placement of the implant-abutment interface (IAI) away from the bone crest has been suggested to have positive impacts on maintenance of peri-implant tissues. Purpose To assess the effects of platform-switched and platform-matched implants, taking into consideration the IAI at different positions relative to the bone crest, on clinical, radiographic, and microbiological outcomes during 12 months following functional loading. Materials and Methods The present prospective randomized study was performed upon 70 patients. Group I (n = 23) implants presenting a platform-switched implant-abutment connection design was inserted 1 mm subcrestally. Group II (n = 22) implants with similar properties were inserted crestally. Group III (n = 25) implants presenting a platform-matched approach with an internal hexagon connection design was inserted crestally. The periodontal parameters were assessed at baseline, and 3, 6, and 12 months postloading. Radiographic marginal bone level (MBL) changes were analyzed at the 12-month follow-up. The amount of DNA copies of Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Tannerella forsythia, Provetalla intermedia and total bacterial mean load in peri-implant sulcus fluid (PISF) were assessed at the same periods. Results There were no significant differences among the groups with respect to the periodontal parameters for all time periods. At 12-month follow-up, the MBL changes were 0.16 +/- 0.29 mm and 0.17 +/- 0.23 mm for group I, 0.15 +/- 0.25 mm and 0.17 +/- 0.26 mm for group II, 0.17 +/- 0.26 mm and for group III in mesial and distal sites, respectively. The mean total bacterial load was found significantly higher for group III compared to the other groups in the three interval times (P < .05). Conclusion Implants restored with platform-switching and platform-matching performed equally regarding clinical and radiographic outcomes. Platform-matched implants inserted at the crestal level presented higher the mean bacterial total load in PISF.Item Is crystalloid cardioplegia a strong predictor of intra-operative hemodilution?(2014) Gunday, Murat; Bingol, HakanIntroduction: Complications due to hemodilution (hematocrit value less than 22%) after cardiopulmonary bypass inevitably resulted with significantly greater intensive care requirements, long hospital stays, more operative costs, and increased mortality rates. We tried to identify whether crystalloid cardioplegia is the strongest predictor of intraoperative hemodilution or not. Materials and methods: One hundred patients were included into this randomized prospective study. Patients were divided into the two groups. Crystalloid cardioplegia were given to the odd-numbered patients (Group 1, n = 50 patients) and blood cardioplegia were given to the even-numbered patients (Group 2, n = 50 patients). St. Thomas-II solution was used in Group-1 and Calafiore cold blood cardioplegia was in Group-2. Results: Average intraoperative hematocrit value was 18.4% +/- 2.3 in crystalloid group 24.2% +/- 3.4 in blood cardioplegia group (p < 0.001). The lowest hematocrit value was 15% and 20% in two groups respectively (p < 0.001). In crystalloid group average intraoperative packed red blood cell (RBC) transfusion was 2.3 +/- 0.41 units, 0.7 +/- 0.6 units blood cardioplegia group (p = 0.001). Average transfused RBC was 2.7 +/- 0.8 units in crystalloid group, 0.9 +/- 0.4 units blood cardioplegia group (p < 0.001). Multivariate analyses confirmed age (p = 0.005, OR = 3.78), female gender (p = 0.003, OR = 2.91), longer cross-clamp time (>60 minutes) (p = 0.001, OD = 0.97), body surface area <1.6 m(2) (p = 0.001, OR = 6.01) and crystalloid cardioplegia (p < 0.001, OR = 0.19) as predictor of intraoperative hemodilution. Conclusion: Crystalloid cardioplegia, compared to blood cardioplegia not only causes much more intra-operative hemodilution but also increases the blood transfusion requirement. Hemodilution and increased transfusion increases the intensive care unit and hospital stay, in the early postoperative period.Item Concurrent Chemoradiotherapy with Vinorelbine plus Split-Dose Cisplatin may be an Option in Inoperable Stage III Non-Small Cell Lung Cancer: A Single-Center Experience(2015) Mertsoylu, Huseyin; Kose, Fatih; Sumbul, Ahmet Taner; Sedef, Ali Murat; Dogan, Ozlem; Besen, Ali Ayberk; Parlak, Cem; Findikcioglu, Alper; Muallaoglu, Sadik; Sezer, Ahmet; Sakalli, Hakan; Ozyilkan, Ozgur; 25731741Background: Concurrent chemoradiotherapy is the current standard treatment for inoperable stage III non-small cell lung cancer (NSCLC). In this study we aimed to investigate the efficacy and toxicity of CCRT with split dose of cisplatin (30 mg/m(2)) and vinorelbine (20 mg/m(2)) in patients with inoperable stage III NSCLC followed in our oncology clinic. Material/Methods: Medical records of 97 patients with inoperable stage III NSCLC treated with concurrent chemoradiotherapy with cisplatin-vinorelbine were retrospectively analyzed. Cisplatin (30 mg/m(2)) and vinorelbine (20 mg/m(2)) were administered on days 1, 8, 22, and 29 during radiotherapy. Two cycles of consolidation chemotherapy were given. All patient data, including pathological, clinical, radiological, biochemical, and hematological data, were assessed retrospectively using our database system. Results: Our study included 97 unresectable stage III NSCLC patients who were treated with CCRT. Median age was 58 years old (range 39-75) and 87 (89.7%) of the patients were men. ECOG performance score was 0-1 in 93 patients (95.9%). Squamous histology, the most common histology, was diagnosed in 46 patients (47.4%). Median follow-up time was 23.8 months. Median progression-free survival (PFS) and median overall survival time (OS) were 10.3 months and 17.8 months, respectively. Objective response rate and clinical benefit rate were 75.3% and 83.5%, respectively. Distant and local relapse rate were 57.1% and 42.9%, respectively. Hematological and non-hematological grade 3-4 toxicities were seen in 13 (13.4%) and 16 (16.5%) patients, respectively. Six (6.1%) patients died due to toxicity. Conclusions: The results of this study suggest that split-dose cisplatin may offer fewer grade III-IV toxicities without sacrificing efficacy and could be an option in patients with inoperable stage III NSCLC during CCRT. Similar to past studies, despite high response rate during CCRT, distant relapse is the major parameter that influences patient survival in long-term in NSCLC.Item Quality of Life in Panic Disorder: Follow Up Study for 3 Months(2015) Altintas, Ebru; Uguz, Sukru; Levent, Bekir AydinPurpose: Panic Disorder is a common psychiatric condition which is higher risk for substance abuse, suicide attempts and functional disability. It is 2-3 times more common in women and estimated to range from 1,4% to 3,8% of the general population. Studies reported that quality of life in Panic Disorder is negatively affected and overall health (emotional and psyhical health), social activities, risk of unemployment increases. The aim of this study was investigate the affects of quality of life on panic disorder and depression and follow the treatment response after the 3 months. Material and Methods: 22 women and 9 men (total 31) within in age range of 20-73(mean age 40,3 +/- 12,9) diagnosed as Panic Disorder; 27 women and 15 men (total 42) within in age range of 18-57(mean age 33,6 +/- 11,5) diagnosed as Panic Disorder with Agoraphobia; 54 women and 19 men (total 73) within in age 20-69(mean age 38,5 +/- 11,7) diagnosed on Major Depression were included to study. Psychiatric interview were carried out using Structured Clinical Interview for Diagnose(SCID-I), Sociodemographic Data Form, Hamilton Anxiety Scale (HAM-A), Hamilton Depression Scale(HAM-D), Panic and Agoraphobia Scale and Endicott's Work Productivity Scale (EWPS) were applied in 0., 1., 3. months. Results: Quality of life had negatively affected in all of the groups. In this study we found significant impairment in pain, general health, energy, social function, emotional role disability and mental health subgroups of quality of life scale (SF-36) in Depression group than Panic Disorder group. Panic Disorder with Agoraphobia had affected the quality of life worse than comparison with Panic Disorder without Agoraphobia. Conclusion: At the end of the treatment, there were no differences in quality of life between all of the groups statistically.Item Iatrogenic vascular injuries due to spinal surgeries: Endovascular perspective(2018) Gok, M.; Aydin, E.; Güneyli, S.; Akay, A.; Cinar, C.; Oran, I.; 0000-0003-0907-3647; 28191625; AAI-8276-2021AIM: Iatrogenic vascular injuries due to spinal surgeries are rare but serious complications. Surgical management of these injuries is challenging with high morbidity rates. In this study we aim to present the results of endovascular management of iatrogenic vascular injuries due to spinal surgeries. MATERIAL and METHODS: We retrospectively reviewed 11 patients (5 male, 6 female) who had vascular injuries due to cervical and lumbar spinal surgeries. Clinical findings were bleeding (n=5), leg edema (n=6) and right heart failure with severe dyspnea (n=1). The age range of the patients were between 42-67 (mean: 57.1). Six patients were reviewed with imaging before the procedures and the rest of the patients (n=5) were directly referred to the angiography unit for diagnosis and possible endovascular treatment. RESULTS: The types of surgeries were; cervical surgery (n=5) and lumbar disc operation (n=6). The type of vascular injuries were; vertebral artery stenosis (n=1), vertebral artery pseudoaneurysm (n=3), vertebral artery occlusion (n=1) and iliac arteriovenous fistula (n=6). The type of endovascular treatments were; parent artery occlusion (PAO) (n=2), covered stent graft implantation (n=6) and intrasaccular coil embolization of pseudoaneurysm (n=1). The remaining 2 patients were managed conservatively. No major complications or mortality occured during endovascular interventions. No bleeding or ischemia occured in the follow-up period. CONCLUSION: Iatrogenic vascular injuries due to spinal surgeries are rare but serious complications. Endovascular interventions are safe and effective in the diagnosis and treatment of such vascular injuries. © 2017, Turkish Neurosurgical Society.