26 results on '"POLAT, Ezgi"'
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2. Electricity Demand Prediction: Case of Turkey
- Author
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Polat, Ezgi, Aydin, Nezir, Isikli, Erkan, Daim, Tugrul U., Series Editor, Dabić, Marina, Series Editor, Kayakutlu, Gülgün, editor, and Kayalica, M. Özgür, editor
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- 2023
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3. Türkiye'deki Büyükşehirlerin Konut Su Tarife Yapısının Farklı Ülkeler ile Karşılaştırılmalı Olarak İncelenmesi.
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POLAT, Ezgi, EKERGİL, Vedat, and KAVAK, Sedi
- Abstract
Copyright of Optimum: Journal of Economics & Management Sciences / Ekonomi ve Yönetim Bilimleri Dergisi is the property of Optimum: Journal of Economics & Management Sciences and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
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- 2024
- Full Text
- View/download PDF
4. Prediction of Non-Revenue Water Cost Via Opportunity Cost Modeling Approach for Sustainable Water
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EKERGİL, Vedat, primary and POLAT, Ezgi, additional
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- 2023
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5. Trajectory Optimization for a Single Stage Launcher with Constrained Conditions
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Şengil, Nevşan, primary, Dağli, Tuğrul Eren, additional, Güngör, Begüm, additional, and Polat, Ezgi, additional
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- 2023
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6. Sürdürülebilir Su İçin Fırsat Maliyeti Modelleme Yaklaşımı ile Gelir Getirmeyen Su Maliyeti Tahmini.
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Ekergil, Vedat and Polat, Ezgi
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- 2023
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7. PERFORMANCE OF AIRLINES: TOPSIS ANALYSIS
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Teker, Dilek, primary, Teker, Suat, additional, and Polat, Ezgi, additional
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- 2022
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8. Sales forecasting in the white goods industry: A data mining application
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Polat, Ezgi Demirer, Oğuzlar, Ayşe, and Bursa Uludağ Üniversitesi/Sosyal Bilimler Enstitüsü/Ekonometri Anabilim Dalı/İstatistik Bilim Dalı.
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Sales forecasting ,Artificial neural network ,Support vector machine ,Satış tahmini ,Regresyon ,Weka ,Weka programı ,Destek vektör makinesi ,Data mining ,Veri madenciliği ,Regression ,Yapay sinir ağı - Abstract
Büyüme hedefi olan ve sürekli gelişmeyi hedefleyen firmaların hayatta kalarak varlığını sürdürmeleri için; yeni öngörüler, stratejiler ve en önemlisi onlara yol gösterebilecek veri analizlerine ihtiyaç duymaktadırlar. Bu analizler sayesinde firmalar, yoğun rekabet ortamında hızlı ve en doğru kararı verebilir durumda olabileceklerdir. Varlıklarını devam ettirebilmek isteyen üreticiler, bir yandan artan müşteri beklentilerini karşılamak isterken bir yandan da maliyetlerini en az seviyede tutmayı amaçlamaktadırlar. Firmalar içinde bulundukları mevcut yapı öncesine bir yolculuk yaptıklarında, karar mekanizmalarını daha doğru kullandıklarını düşünerek hareket ederler. Bu sebepledir ki, deneyimler bizlere her zaman doğru yolu gösterir sözü bu noktada kanıtlanabilir nitelikte olmaktadır. Bu çalışmada, firmaların geçmiş yıllara ait ciro ve karlılık durumu analiz edilerek veri madenciliği teknikleri içerisinde yer alan; yapay sinir ağı, destek vektör makineleri ve regresyon ile doğru sonuca ulaşması hedeflenmektedir. Önceki yılların verileri analiz edilerek, yeni bir yılın verileri hakkında ön görü sahibi olmak hedeflenmektedir. Bu doğrultuda, geliştirilebilecek stratejiler sonucunda karlılık seviyesinin artacağını düşünmemek elde değildir. Bu çalışmada amaçlanan, bu doğrusal düşünceyi matematiksel olarak ispatlayarak hedefe sağlam adımlar ile ilerleyebilmektir. Durumun kanıtlanabilmesi amacıyla, beyaz eşya sektöründe faaliyet gösteren firmanın; sevk verileri bağımlı değişken, reel kesim güven endeksi, gayri safi yurtiçi hasıla, sanayi üretim endeksi, evlenme oranı, tüketici güven endeksi ve ekonomi güven endeksi ise bağımsız değişken olarak aylık bazda alınmıştır. Veriler uygulama aşamasında, Weka programında test edilmiştir. Satış tahminleri üç ayrı yöntem ile ayrı ayrı test edilmiş ve sonuçlar birbirleri ile kıyaslanmıştır. For companies with growth targets and continuous development to survive and survive; they need new insights, strategies and, most importantly, analysis of the data that can guide them. Thanks to these analyses, companies will be able to make the fastest and most accurate decision in an intensely competitive environment. In this study, the turnover and profitability status of the companies for the past years are analyzed and included in the data mining techniques; it is aimed to achieve the right result with artificial neural network, support vector machines and regression. By analyzing the data of previous years, it is aimed to have a foresground about the data of a new year. Accordingly, it is notible not to think that the level of profitability will increase as a result of the strategies that can be developed. The aim of this study is to prove this linear thinking mathematically and to move forward with solid steps towards the goal. In order to prove the situation, the company operating in the white goods sector; the referral data are taken on a monthly basis as dependent variable, real sector confidence index, gross domestic product, industrial production index, marriage rate, consumer confidence index and economic confidence index as independent variables. The data was tested in the Weka program during the implementation phase. Sales estimates were tested separately by three different methods and the results were compared with each other.
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- 2022
9. Association Between Serum Gamma-Glutamyltransferase Activity and Carotid Intima-Media Thickness
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Eroglu, Serpil, Sade, Leyla Elif, Polat, Ezgi, Bozbas, Huseyin, Ulus, Taner, and Muderrisoglu, Haldun
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- 2011
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10. MUHASEBE MESLEK MENSUPLARININ MÜŞTERİ KÂRLILIK ANALİZİ VE BİR MODEL ÖNERİSİ
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EKERGİL, Vedat, primary and POLAT, Ezgi, additional
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- 2020
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11. Türkiye'nin aylık elektrik tüketiminin yapay sinir ağlarıyla tahmini
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Polat, Ezgi, Aydın, Nezir, and Endüstri Mühendisliği Anabilim Dalı
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Endüstri ve Endüstri Mühendisliği ,Industrial and Industrial Engineering - Abstract
Nüfusun hızla artması, ekonomik gelişmeler ve sanayileşme faaliyetleri elektrikenerjisine ihtiyacı günden güne arttırmaktadır. Enerji kaynaklarının giderek azalması,elektriğin sürdürülebilir arzının sağlanması için tehlike oluşturmaktadır. Türkiye'debirincil enerji kaynaklarının çoğu ithal edilmekte ve bu yüzden elektrik üretimfaaliyetlerinin planlı şekilde yürütülmesi önem teşkil etmektedir.Çalışmada, Türkiye'nin aylık elektrik tüketimi, ekonomik değişkenler ve hava durumudeğişkenleri bir arada kullanılarak tahmin edilmeye çalışılmıştır. Tahmin yöntemi olarak,istatistiksel tahmin yöntemlerine güçlü bir alternatif olan Yapay Sinir Ağları tercihedilmiştir.Tezin ilk bölümünde elektik tahminiyle ilgili literatür araştırılmış ve kullanılacakyöntemin detaylarına bu bilgiler ışığında karar verilmiştir. Sonrasında Yapay SinirAğlarının teorik altyapısı ve Türkiye'nin elektrik enerjisi genel görünümü incelenmiştir.Uygulama kısmında Çok Katmanlı Yapay Sinir Ağıyla Türkiye'nin Şubat 2019 ve Ocak 2020tarihleri arasındaki aylık elektrik tüketim tahmin edilmiştir. Rapid increase in population, economic developments and industrialization activitiesincrease the need for electric energy day to day. The consistent decline in energyresources poses hazard for sustainable supply of electricity. Turkey imports most of theprimary energy sources therefore it is significant to conduct planned electricitygeneration activities.In this study, monthly electricity consumption, economic variables and weatherconditions of Turkey has been studied together to make an estimation. As an estimationmethod, Artificial Neural Networks, which are a powerful alternative to statisticalestimation methods, are preferred.In the first part of the thesis, literature about electricity estimation is searched and thedetails of the method to be used are determined in light of this information. In thesecond part of the thesis, theoretical background of Artificial Neural Networks and thegeneral overview of electrical energy in Turkey were examined. In practice, theestimation was made with Multilayer Perceptron and monthly electricity consumptionof Turkey between February 2019 and January 2020 are estimated. 88
- Published
- 2019
12. Renewable GenCo bidding strategy using newsvendor-based neural networks: An example from Turkish electricity market.
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Polat, Ezgi, Güler, Mehmet Güray, and Ulukuş, Mehmet Yasin
- Subjects
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BIDDING strategies , *ELECTRICITY markets , *COST functions , *PRICES , *MARKET prices - Abstract
Liberalization policies in the electricity markets have led to an increase in the number of electricity generation companies (GenCos). GenCos develop competitive strategies to thrive in the market and ensure long-term sustainability. In the day-ahead market (DAM), GenCos submit bids for the electricity quantity they plan to generate the next day. Deviating from the committed electricity quantity leads to either selling surplus electricity at a positive imbalance price (lower than the market price) or incurring a penalty for missing electricity at a negative imbalance price (higher than the market price). In this study, we develop a bid strategy for renewable GenCos participating in the Turkish DAM. The proposed approach involves utilizing a neural network (NN) to determine the bid quantity. The proposed NN aims to minimize a cost function considering both negative and positive imbalance prices, as opposed to the classical NN of minimizing the mean squared error. The proposed approach outperforms the classical NN , yielding a 2.38% (potentially reaching up to 7.43%) improvement in revenue generation. Moreover, we perform a comprehensive sensitivity analysis, specifically focusing on changes in penalty coefficients. Notably, as penalty coefficient ranges widen, our approach refines bidding strategy more effectively than alternatives. • The proposed NN model presents a bid strategy for renewable GenCos. • The model cost function takes into account negative and positive imbalance prices. • Thanks to its single-stage structure, the model directly determines the optimal bid. • The model is practical and straightforward to implement. • The model demonstrates superior performance compared to the classical NN. [ABSTRACT FROM AUTHOR]
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- 2024
- Full Text
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13. Ölüm Kavramının Heidegger ve Sartre Felsefesindeki Yeri
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POLAT, Ezgi and AŞKIN, Zehragül
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Death,Heidegger,Sartre,Existence,Absurd ,Ölüm,Heidegger,Sartre,Varoluş,Absürt - Abstract
The concept of death, although appears as one of the fundementalproblematic concepts of the history of philosophy, attained its ontologicaland existential content in Heidegger and Sartre. Heidegger positioned thephenomenon of death as a possibility that determines the existence of Dasein, andgives meaning to life. Unlike in Heidegger, in Sartre we confront with the conceptat stake, as an absurd fact which evokes nausea and anxiety in the human being. , Ölüm kavramı, felsefe tarihinin temel sorunsal kavramlarından biri olarakkarşımıza çıkmakla birlikte ontolojik ve varoluşsal içerimine Heidegger veSartre’da ulaşmıştır. Heidegger, ölüm fenomenini Dasein’ın varoluşunu belirleyenve yaşama anlam veren bir olanak olarak konumlandırmıştır. Sartre’da ise sözkonusu kavram, Heidegger’den farklı olarak yaşamı değerden düşüren, insandabulantı ve kaygı uyandıran absürt bir olgu olarak karşımıza çıkmaktadır. 
- Published
- 2017
14. M. Heidegger ve J. P. Sartre'da ölüm kavramı
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Polat, Ezgi, Aşkın, Zehragül, and Felsefe Anabilim Dalı
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Death ,Philosophy ,Sartre, Jean Paul ,Felsefe ,Heidegger, Martin ,Asset - Abstract
Bu çalışma, felsefe tarihinde temel sorunsal kavramlardan biri olan ölüm kavramının M. Heidegger ve J. P. Sartre'daki izdüşümünü ele almayı amaçlamaktadır. Bu bağlamda ilk olarak M. Heidegger'in Varlık ve Zaman'daki ölüm kavramına ilişkin analizleri açığa çıkarılmaya çalışılmış ve Heidegger'in ölüme verdiği anlamın Sartre'ın Varlık ve Hiçlik yapıtındaki izdüşümlerine geçilmiştir. Tez bu bağlamda üç bölümden oluşmaktadır.Tezin birinci bölümünün konusunu Heidegger'de ölüm kavramı ve analizi oluşturmaktadır. Heidegger'in Varlık ile dünyada Dasein varlık tarzında bulunan insan arasında kurduğu ilişkide Dasein'ın varoluşunun anlamına dönüşen Varlığın anlamı sorununun çözümlenmesinde ölüm kavramının merkezi bir öneme sahip olduğu açığa çıkarılmıştır.Tezin ikinci bölümünün konusunu ise, Sartre'ın Varlık ve Hiçlik yapıtında ortaya koyduğu Varlık anlayışı bağlamında ölüm kavramına ilişkin düşünceleri oluşturmaktadır. Çalışmanın bu bölümü Sartre'ın saçma, ölüm ve özgürlük arasında kurmuş olduğu ilişkiyi analiz etme çabası içinde olmuştur.Tezin üçüncü bölümünde ise, Heidegger'in ve Sartre'ın ölüm kavramına ilişkin düşünceleri karşılaştırmalı olarak analiz edilerek, aralarındaki ortak noktalar ve ayrımlar açığa çıkarılmaya çalışılmıştır. This study aims to deal with projections of the concept of death, which is one of most problematic concepts in the history of philosophy, on M.Heidegger and J.P.Sartre. Within this context, first we have tried to reveal the analysis of Martin Heidegger in Being and Time concerning the concept of death and then moved on to projections of the meaning that Heidegger ascribed to the concept of death on Sartre's work of Being and Nothingness. The thesis, within this context, consists of three chapters.The subject of the first chapter comprises the concept of the death in Heidegger and his analysis regarding that concept. We have uncovered that in the analysis of the problem of the meaning of Being which turns into the meaning of the existence of Dasein in the relationship that Heidegger establishes between the Being and the human that exists in the world in a special mode of Being called Dasein, the concept of death is of a central importance. As for the subject of the second chapter, it comprises thoughts of Sartre in his work of Being and Nothingness, on the concept of death within the context of understanding of Being. This chapter tries to analyze relations which Sartre establishes among the absurd, death and freedom. As for the third chapter, we have analyzed thoughts of Heidegger and Sartre in a comperative way, and tried to uncover common points and distinctions between them. 104
- Published
- 2016
15. Anayasal vatandaşlık
- Author
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Güzel Polat, Ezgi, Çeçen, Anıl, and Kamu Hukuku Ana Bilim Dalı
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Hukuk ,Kamu Yönetimi ,Public Administration ,Constitutional citizenship ,Citizenship ,Law ,Multiculturalism - Abstract
Bu tezde, Türkiye'de son yirmi yıldır, Avrupa'da ise daha uzun bir süredir tartışılan ?Anayasal Vatandandaşlık? kavramının, ulusal vatandaşlık anlayışı ile çokkültürlü vatandaşlık hipotezlerinin çıkmazlarına bir çözüm üretebilmek noktasında işlevselliği incelenmeye çalışılmıştır. Bu amaçla, vatandaşlık kavramının gelişimi tarihsel süreçlerle anlatılmaya çalışılmış, modern vatandaşlık, ulusal vatandaşlık ve çokkültürlü vatandaşlık kavramlarına kapı aralanmıştır. Konuyla ilgili olarak Avrupa ülkelerinden bazı örneklere ve Kanada'ya vatandaşlık uygulamaları kapsamında yer verilmiş; buradan, ülkemizde vatandaşlık kavramının geçirdiği aşamalar ve geldiği son noktaya kısaca göz atılmıştır. Tezin arka planında, hala yaşam mücadelesi veren ulus-devlet yapılanmalarının, ulusal azınlıklar ve göçmenler gerçeği karşısında geliştirilen çokkültürlü vatandaşlık pratikleri ile klasik ulusal vatandaşlık pratiklerinin çekişmeleri arasında, bir seçim yapmak mecburiyetinde kalmaksızın, vatandaşlık sorununu en pratik ve en hasarsız bir şekilde çözüp çözemeyecekleri sorusu yer almaktadır. Bu sebeple ilk olarak ulus devlet yapılanmasının vatandaşlık konusuyla doğrudan ilgisi olduğuna inanılan bazı unsurları incelenmiş; akabinde, ulus-devlet yapılanmalarının anayasal vatandaşlık kavramına körü körüne sırt çevirmeden, kavramı doğru tahlil ederek ve kendi özel şartlarına evirerek bir çözüme kavuşup kavuşamayacakları sorusu, Türkiye örneğinden hareketle cevaplanmaya çalışılmıştır. Osmanlı geleneğine, yeni Türkiye Cumhuriyeti Devleti'nin kuruluş ilkelerine ve anayasalarına değinilerek Türkiye için anayasal vatandaşlık önerisinin gerçekçi bir temeli olabilir mi sorusuna cevap arama çabasıyla sona erdirilen tez, ülkemiz açısından çok tartışmalı olan vatandaşlık konusuna bir ışık tutmak ümidiyle yazılmıştır.Anahtar Kelimeler: Modern Vatandaşlık, Ulusal Vatandaşlık, Anayasal Vatandaşlık, Çokkültürlülük. ?Constitutional Citizenship? has been discussed for the past twenty years in Turkey and longer in Europe. In this thesis, ?Constitutional citizenship? has been tried to analyze that its functionality at the point where to create a solution for dilemma of national citizenship concept and multicultural citizenship hypothesis. For this purpose, the development of citizenship concept is tried to beexplained with historical process, a door has opened to modern citizenship, national citizenship and multicultural citizenship concepts. Relating to the subject, some examples from European countries and Canada -within the concept of citizenship practice- have taken place; hence, the processes that concept of citizenship has developed in our country and its place today, has been glanced shortly. Behind the thesis, there is a question of solving the citizenship problem with a practical and the most 'damage free' way in a situation where nation-state settlements which are still struggling to live, the struggle between classical national citizenship practices and multicultural citizenship practices created due to national minorities and immigrants. Because of this, first of all, some facts that are believed to be related directly with the topic of citizenship in nation-state structure, subsequently, nation-state structures without refusing constitutional citizenship concept, a question tried to be answered in the point of Turkey example with analyzing the concept right and addressing the special conditions. The thesis mentions Ottoman tradition, new TurkishRepublic nations? institution principles and constitutions and it finishes with effort to find an answer to question: ?Could there be a realistic basis of constitutional citizenship for Turkey?? This thesis has been written with the hope to enlighten the citizenship subject that is very controversial for our country.Key Words: Modern Citizenship, National Citizenship, Constitutional Citizenship, Multiculturalism. 422
- Published
- 2011
16. Effect of family history of type-2 diabetes on coronary flow reserve and it’s relationship with insulin resistance: an observational study
- Author
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Caliskan, Mustafa, primary, Pamuk, Baris Onder, additional, Gullu, Hakan, additional, Ciftci, Ozgur, additional, Caliskan, Zuhal, additional, Erdogan, Dogan, additional, Guven, Aytekin, additional, Polat, Ezgi, additional, and Muderrisoglu, Haldun, additional
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- 2012
- Full Text
- View/download PDF
17. PP-009 THE ASSOCIATION BETWEEN SERUM GAMMA-GLUTAMYLTRANSFERASE ACTIVITY AND CAROTID INTIMA MEDIA THICKNESS
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Eroglu, Serpil, primary, Sade, Leyla Elif, additional, Polat, Ezgi, additional, Bozbas, Huseyin, additional, Ulus, Taner, additional, and Muderrisoglu, Haldun, additional
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- 2010
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18. Effect of family history of type-2 diabetes on coronary flow reserve and it's relationship with insulin resistance: an observational study.
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Çalışkan, Mustafa, Pamuk, Barış Önder, Güllü, Hakan, Çiftçi, Özgür, Çaliskan, Zuhal, Erdogan, Dogan, Güven, Aytekin, Polat, Ezgi, and Müderrisoglu, Haldun
- Subjects
SCIENTIFIC observation ,CORONARY circulation ,TYPE 2 diabetes ,INSULIN resistance ,ECHOCARDIOGRAPHY ,REGRESSION analysis ,CHI-squared test - Abstract
Copyright of Anatolian Journal of Cardiology / Anadolu Kardiyoloji Dergisi is the property of KARE Publishing and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
- Published
- 2013
- Full Text
- View/download PDF
19. School Refusal and Determinants: Parental Psychopathology, Family Functioning, Attachment and Temperament.
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Eroglu, Mehtap, Mentese Babayigit, Tugba, Bilgen Ulgar, Sermin, Ozturk Polat, Ezgi, Erguven Demirtas, Merve, Gul Alic, Betül, Temelturk, Duygu, and Yaksi, Nese
- Subjects
- *
FAMILY roles , *SCHOOL building maintenance & repair , *PATHOLOGICAL psychology , *ADOLESCENT psychiatry , *PARENTS , *TEMPERAMENT , *SCHOOL children - Abstract
ABSTRACT In the current study investigated the psychopathologies of parents, family functioning, child temperament characteristics, and attachment of kindergarten and primary school‐age children who were brought to the child and adolescent psychiatry outpatient clinic due to school refusal behavior. Fifty‐two children with school refusal and 64 children without school refusal and their parents participated in the current study. School Refusal Assessment Scale, Systemic Family Functionality Scale(SFFS), Family Harmony Scale(FHS), Kerns Secure Attachment Scale(KSAS), Temperament Scale for Children(TSC), and Depression Anxiety Stress Scales(DASS) for parents were used. It was determined that, compared to children without school refusal, the children with school refusal had lower KSAS score(mother)(
p = 0.049), higher DASS‐stress and anxiety(mother) scores(p = 0.014 andp = 0.020, respectively), lower TSC‐Responsiveness/Reactivity subscale score (p = 0.005), lower SFFS‐intrafamilial support and SFFS‐intrafamilial connection scores (p = 0.002 andp < 0.001, respectively), and lower FHS‐total score (p = 0.002). It was determined that school refusal was 11 times more common in children who had difficulty adjusting to school in previous years. Each point increase in the SFFS‐intrafamilial connection score reduced school refusal by 30%. In the current study shows that among the interventions required for treatment, the family should also be targeted in addition to the child and adolescent. Therefore, it is essential to identify factors such as parents' psychopathology and their roles in the family, family functioning, and family harmony in school refusal. Because parents play a crucial role in both the development and maintenance of school refusal, using more parent‐targeted strategies or techniques is necessary to improve interventions. [ABSTRACT FROM AUTHOR]- Published
- 2024
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20. Association between coronary flow reserve and exercise capacity
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Eroglu, Serpil, Leyla Elif Sade, Polat, Ezgi, Bozbas, Huseyin, and Muderrisoglu, Haldun
21. PERFORMANCE OF AIRLINES: TOPSIS ANALYSIS
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Dilek Teker, Suat Teker, Ezgi Polat, Işık Üniversitesi, İktisadi ve İdari Bilimler Fakültesi, İşletme Bölümü, Işık University, Faculty of Economics and Administrative Sciences, Department of Management, Teker, Dilek, Teker, Suat, and Polat, Ezgi
- Subjects
Airline companies ,Performance ranking ,Multi-criteria decision making ,Financial ratios ,İşletme ,TOPSIS,multi-criteria decision making,financial ratios,airline companies,performance ranking ,Business Finance ,İşletme Finans ,TOPSIS ,Management - Abstract
Purpose- Airline industry is very important for modern society and has a crucial role for globalization and business development by connecting regions, promoting global trade and tourism and hence enabling economic and social development. Over the last two decades, the troubled airlines were oftenly on news delebrating financial difficulties, layouts and distrupted sceduled flights. Covid-19 also has a crucial impact on the deterioration of the industry due to quarantinas and break downs for travel and business. This empricial research intends to analyse and rank the financial performance of the top 11 airlines in the Word for the periods of 2019-2020-2021 (Covid era) and also group and rank these airlines as US Airlines, European Airlines and Chinese Airlines. Methodology- This study employs TOPSIS method. 11 biggest airline companies are selected by the total revenue generated in 2021. A total of 18 financial indicators are used to measure the profitability, liquidity, financial structure and operational efficiency for the period of 2019-2021. Utilizing a TOPSIS analysis, the performance scores of these airline companies are calculated and a ranking is determined according to these scores. Findings- United Airlines, Delta Airlines and Southwest Airlines are the top performers in 2019. These airlines have a big drop in 2020 and their performance ranks are 8, 10 and 7, respectively. The best performer in 2020 is the Turkish Airlines. Also, United Airlines and Southwest Airlines show a fast recovery in 2021 by ranking 2 and 1, respectively. When performance ranking is applied for the groups of companies (namely; USA based, Europe based and China based companies), the USA based group is the best performer in 2019, the worst performer in 2020 and the second best performer in 2021. Meanwhile, China based group are the best performer in 2020 and 2021. Conclusion- This study shows that the Covid era has affected profitability and operational efficiency of airline companies significantly. As a result of the study, it is observed that China based airline companies managed the Covid era better than the USA based and European based airline companies. Keywords: TOPSIS, multi-criteria decision making, financial ratios, airline companies, performance ranking. JEL Codes: C02, D22, D53
- Published
- 2022
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22. Customer Profitability analysis of accounting professional members and a model proposal
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Anadolu Üniversitesi, Açıköğretim Fakültesi, Ekergil, Vedat, and Polat, Ezgi
- Subjects
Cost Systems ,Maliyet Sistemleri ,Müşteri Kârlılık Analizi ,Zaman Temelli Faaliyete Dayalı Maliyetleme Sistemi ,Muhasebe Meslek Mensubu ,Customer Profitability Analysis ,Accountant ,Time - Driven Activity Based Costing - Abstract
Zaman temelli faaliyete dayalı maliyet sistemi, geleneksel ve faaliyet tabanlı maliyet sistemlerinin eksik yanları dikkate alınarak geliştirilmiştir. Bu sistem özellikle faaliyetlere ait maliyetlerin daha doğru şekilde belirlenmesine olanak sağlamaktadır. Günümüzde yoğun rekabette ayakta kalmak isteyen işletmeler müşteri kârlılığına odaklanmaktadır. Müşteri kârlılık analizi, müşteri maliyetlerinin doğru şekilde hesaplanmasını temel almaktadır. Müşteri maliyetlerinin hesaplanmasında Zaman temelli faaliyete dayalı maliyet sistemi gerekli bilgiyi sağlayarak doğru maliyet ölçümü yapabilmek için harcanan zaman faktörünü hesaba katmaktadır. Çalışmada muhasebe meslek mensuplarının maliyetleri, zaman temelli faaliyete dayalı maliyetleme yaklaşımına göre yeniden hesaplanmakta ve bu müşterilerin kârlılık analizi yapılmaktadır. Bu kapsamda faaliyetlerin tanımlanması ve faaliyetlere ilişkin zamanların belirlenmesinde, nitel ve nicel yöntemlerin bir arada kullanılmasını sağlayan karma araştırma yönteminden yararlanılmıştır. Sonuç olarak, bir hizmet işletmesi olan SMMM’lerin her bir müşterisine ilişkin zaman temelli faaliyet maliyetleri hesaplanmış ve bu müşterilerden elde edilen hasılat ile karşılaştırılarak her bir müşteriden elde edilen kâr veya zarar tespit edilmiştir., The time-based activity-based cost system has been developed taking into account the shortcomings of traditional and activity-based cost systems. This system enables the costs of the activities to be determined more accurately. Businesses that want to survive in an intense competitive environment focus on customer profitability. Customer profitability analysis is based on accurate calculation of customer costs. In the calculation of customer costs, the time-based activity-based cost system takes into account the time factor spent in making the right cost measurement by providing the necessary information. In the study, the costs of professional accountants are recalculated according to the time-based activitybased costing approach and the profitability analysis of these customers is performed. In this context, a mixed research method, which enables the use of qualitative and quantitative methods together, was used in defining the activities and determining the time related to the activities. As a result, the time-based activity costs for each customer of SMMM, which is a service business, were calculated and profit or loss from each customer was determined by comparing them with the revenue obtained from these customers.
- Published
- 2020
23. Muhasebe meslek mensuplarının müşteri kârlılık analizi ve bir model önerisi
- Author
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Ekergil, Vedat, Anadolu Üniversitesi, Sosyal Bilimler Enstitüsü, İşletme Anabilim Dalı, and Polat, Ezgi
- Subjects
Maliyet Sistemleri ,Müşteri Kârlılık Analizi ,Muhasebe Meslek Mensubu - Abstract
Zaman temelli faaliyete dayalı maliyet sistemi (ZTFDM), geleneksel maliyet ve faaliyet tabanlı maliyet sistemlerinin eksik yanları dikkate alınarak geliştirilmiştir. Bu sistem özellikle faaliyetlere ait maliyetlerin daha doğru ve daha etkin bir şekilde belirlenmesine olanak sağlamaktadır. ZTFDM güncellenmesi kolay, sürdürülebilirliği basit olan ve atıl kapasite maliyetini de en doğru şekilde hesaplayan bir sistemdir. Günümüzde yoğun rekabette ayakta kalmak isteyen işletmeler müşteri kârlılığına odaklanmaktadır. Müşteri kârlılık analizi, müşteri maliyetlerinin doğru şekilde hesaplanmasını temel almaktadır. Müşteri maliyetlerinin hesaplanmasında Zaman temelli faaliyete dayalı maliyetleme sistemi gerekli bilgiyi sağlayarak doğru maliyet ölçümü yapabilmek için harcanan zaman faktörünü hesaba katmaktadır. Çalışmada muhasebe meslek mensuplarına ZTFDM uygulanarak müşteri kârlılık analizinde kullanılmasına yönelik sonuçlar analiz edilmeye çalışılmıştır. Sistemin, muhasebe meslek mensuplarının müşteri kârlılık analizinde kullanılmasının neden olduğu farklılıklar ve sağladığı yararlar üzerinde durulmuştur. Bu çerçevede, nitel ve nicel yöntemlerin birlikte barındıran karma araştırma yöntemi kullanılarak ZTFDM sisteminin analiz sonuçlarını ne şekilde etkilediği gösterilmeye çalışılmıştır.
- Published
- 2019
24. Association between coronary flow reserve and exercise capacity.
- Author
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Eroglu S, Sade LE, Polat E, Bozbas H, and Muderrisoğlu H
- Subjects
- Adult, Aged, Cardiovascular Physiological Phenomena drug effects, Coronary Circulation drug effects, Coronary Circulation physiology, Coronary Vessels physiopathology, Diastole drug effects, Diastole physiology, Dipyridamole administration & dosage, Dipyridamole adverse effects, Echocardiography, Doppler methods, Echocardiography, Doppler, Pulsed, Exercise Test methods, Female, Humans, Male, Microvessels physiopathology, Middle Aged, Observer Variation, Blood Flow Velocity physiology, Exercise physiology
- Abstract
Introduction: Reduced exercise capacity is of clinical importance. Sometimes no corresponding cardiovascular disease can be found to explain this condition. We hypothesized that coronary microvascular dysfunction may have an effect on exercise capacity in patients without apparent cardiovascular disease., Methods: Fifty patients (33 female, mean age 46.8 ± 12.4 years) without coronary artery or other cardiac disease were enrolled. Coronary microvascular function was evaluated by measurement of coronary flow reserve (CFR) during transthoracic pulsed-wave Doppler echocardiography with pharmacological stress. CFR was calculated as the ratio of hyperemic to baseline peak diastolic velocities after dipyridamole infusion. Exercise capacity was determined by treadmill exercise testing. Exercise time, metabolic equivalent (MET), and Duke treadmill score (DTS) were recorded and compared with the CFR data., Results: CFR was correlated with exercise time (r=0.376, p=0.007), MET (r=0.435, p=0.002) and DTS (r=0.458, p=0.001). Exercise time, MET, and DTS were lower in patients with impaired CFR (<2) than in those with normal CFR (2) (5.3 ± 1.8 min vs. 8.6 ± 2.7 min, p<0.001; 7.3 ± 3.1 vs. 11.4 ± 2.8, p=0.002; -1.75 (-5.9, 5.0) vs. 7.5 (5.2, 9.41), p<0.001; respectively). CFR was lower in patients with MET7 as compared to patients with MET>7 (2.0 ± 0.5 vs. 2.6 ± 0.6, p=0.015)., Conclusions: CFR is associated with exercise capacity. Thus coronary microvascular dysfunction may be a reason for reduced exercise capacity in patients who have no apparent cardiovascular disease.
- Published
- 2015
25. Effect of family history of type-2 diabetes on coronary flow reserve and it's relationship with insulin resistance: an observational study.
- Author
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Calişkan M, Pamuk BÖ, Güllü H, Çiftçi Ö, Çalişkan Z, Erdoğan D, Güven A, Polat E, and Müderrisoğlu H
- Subjects
- Adolescent, Adult, Case-Control Studies, Cross-Sectional Studies, Diabetes Mellitus, Type 2 genetics, Echocardiography, Family, Female, Genetic Predisposition to Disease, Homeostasis, Humans, Male, Middle Aged, Models, Biological, Regression Analysis, Coronary Circulation physiology, Diabetes Mellitus, Type 2 complications, Insulin Resistance
- Abstract
Objective: Coronary microvascular function among offspring of patients with diabetes mellitus might be compromised when compared to persons with no first-degree relative with diabetes mellitus. The aim of the study was to evaluate effect of family history of type-2 diabetes on coronary flow reserve., Methods: In this observational study, we evaluated coronary flow reserve (CFR) via echocardiography of 95 subjects having a biological parent with type-2 diabetes and 34 healthy volunteers without any biological parent with type-2 diabetes. We have analyzed possible association with CFR and homeostasis model assessment - insulin resistance (HOMA-IR). Comparison analyses were made using independent samples t test, Chi-square test and one-way ANOVA. Association of independent variables with CFR was obtained by correlation analysis and stepwise linear regression model including potential confounders., Results: CFR was significantly lower in the positive family history group than in the controls. Moreover, when compared with controls, the subgroup of insulin-sensitive subjects in the positive family history group also had significantly reduced CFR (2.67±0.28 vs. 2.83±0.19; p=0.01). Correlation analysis revealed that CFR was inversely correlated with HOMA-IR, (r=-0.433), fasting glucose (r=-0.331), fasting insulin (r=-0.396), and hemoglobin (Hb)A1c (r=-0.405). When the positive family history group was divided into tertiles of insulin resistance (HOMA-IR <1.3, 1.3-2.6, and >2.6; Groups 1-2, and 3), there was a significant difference in CFR between Groups 1 and 2 and between Groups 1 and 3 (p<0.05 for all). Though statistically not significant, there was also a difference in CFR between Groups 2 and 3. In a linear regression model, only fasting glucose level was independent predictor of CFR (β=-677; p value =0.001, 95% CI: -0.061 and -0.019)., Conclusion: Nondiabetic first-degree relatives of patients with type-2 diabetes are at increased risk of developing coronary microvascular dysfunction.
- Published
- 2013
- Full Text
- View/download PDF
26. Serum gamma-glutamyl transferase activity: new high-risk criteria in acute coronary syndrome patients?
- Author
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Ulus T, Yildirir A, Sade LE, Temiz A, Polat E, Bozbaş H, Aydinalp A, Eroğlu S, Ozin B, and Müderrisoğlu H
- Subjects
- Acute Coronary Syndrome complications, Acute Coronary Syndrome mortality, Adult, Aged, Aged, 80 and over, Biomarkers blood, Cardiovascular Diseases enzymology, Cardiovascular Diseases mortality, Coronary Care Units, Female, Hospitalization, Humans, Male, Middle Aged, Myocardial Revascularization, Odds Ratio, Proportional Hazards Models, Recurrence, Risk Assessment, Risk Factors, Time Factors, Treatment Outcome, Up-Regulation, Acute Coronary Syndrome enzymology, Acute Coronary Syndrome therapy, Cardiovascular Diseases etiology, gamma-Glutamyltransferase blood
- Abstract
In acute coronary syndromes (ACS), oxidation and inflammation have very important roles and in-vitro studies have demonstrated that gamma-glutamyl transferase (GGT) participates in such oxidative and inflammatory reactions. We aimed to evaluate the prognostic value of baseline serum GGT activity on the development of major adverse cardiac event (MACE) in the follow-up of the patients with ACS in coronary care unit (CCU), after 1 and 6 month periods. We included 117 patients (mean age: 61.2+/-11.3 years, 93 males) hospitalized in CCU with the diagnosis of ACS. All had baseline serum GGT activity and were free of systemic and hepatobiliary disease. MACE was defined as the composite of mortality from cardiac causes, recurrent hospitalization with ACS and nonfatal recurrent myocardial infarction diagnoses, to need for coronary revascularization during CCU, over 1 and 6 month follow-up periods. During the follow-up of CCU, MACE occurred in 17 (14.5%) patients (two died). Serum GGT activity was significantly higher in the patients with MACE than those free of MACE (P=0.001) and GGT was found as the independent predictor of the development of MACE-CCU [relative hazard: 1.05, 95% confidence interval (CI): 1.01-1.09, P=0.007]. During the follow-up of 1 month, MACE occurred in 23 (20.0%) patients (five died). Serum GGT activity was significantly higher in patients with MACE than those free of MACE (P=0.021) and GGT was found as the independent predictor of the development of MACE-1 month (relative hazard: 1.04, 95% CI: 1.01-1.08, P=0.039). During the follow-up of 6 months, MACE occurred in 24 (21.8%) patients (two died). Again, GGT was significantly higher in patients who developed MACE than those free of MACE (P=0.001) and GGT was found as the independent predictor of the development of MACE-6 months (relative hazard 1.06, 95% CI: 1.03-1.10, P<0.001). Serum GGT activity was found to be an independent predictor of the development of MACE in the patients with ACS during CCU, over 1 and 6 month follow-up periods.
- Published
- 2008
- Full Text
- View/download PDF
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