81 research outputs found
The Market Performance of Initial Public Offerings in the Istanbul Stock Exchange
No full textThis study examines the long-standing IPO performance in the Istanbul Stock Exchange (ISE) by using new factors such as source of shares (new issue or sale of large shareholders), allocation of shares and dispersion of investors as well as existing factors such as market conditions (hot/cold), underwriters’ reputation, and firm characteristics (firm size, E/P, and B/M ratios) in the period of 1990-2000. Our results differ from the previous studies at least three ways. First, the magnitude of underpricing is significantly lower, while underperformance is higher than those of in other studies. Our strong evidence supports the existence of the underpricing by positive initial excess returns (5.94%) and the long-term underperformance up to three-year holding period (-84.5%) in the ISE. Second, underperformance starts much earlier than in other markets i.e. at the end of first month following the IPO because of myopic behavior of investors seeking short-term returns. Third, the underperformance disappears for IPOs made in a cold market, and those made through the sale of large shareholders. Allocation of shares in an IPO and firm size also impact after-market performance of sharesInitial Public Offerings, Underperformance, Underpricing, Market Efficiency, Emerging Markets
THE SOLUTION OF LATERAL HEAT LOSS PROBLEM USING COLLOCATION METHOD WITH CUBIC B-SPLINES FINITE ELEMENT
No full textThis paper deals with the solutions of lateral heat loss equation by using collocation method with cubic B-splines finite elements. The stability analysis of this method is investigated by considering Fourier stability method. The comparison of the numerical solutions obtained by using this method with the analytic solutions is given by the tables and the figure
Modelling Wind turbine diffusion: A comparative simulation study of California and Denmark for 1980-1995
No full textDiffusion of renewable technologies are in the policy makers’ minds since the 1970s to deal with depleting resources and finding solutions to environmental concerns. Therefore, understanding the mechanisms behind a diffusion process becomes quite important for policy makers to manage the process effectively. A new understanding of innovation diffusion was introduced in the recent years, suggesting a dynamic understanding of the phenomenon. With this aim, this research used system dynamics modelling as a dynamic tool for modelling wind turbine diffusion. To be able to see to what extent system dynamics is able to capture the underlying mechanisms of diffusion processes, a known case of wind turbine diffusion in California and Denmark is chosen as a comparative case study. The results showed that Denmark was more successful with a higher diffusion rate due to various reasons; high oil prices, strong networks enabling knowledge share, and determination of the government. This research also showed that system dynamics is a promising approach for understanding innovation diffusion.Policy AnalysisSystems Engineering Policy Analysis and ManagementTechnology, Policy and Managemen
Market Microstructure in Emerging and Developed Markets
No full textNazli Sila Alan, with R. Bildik and R. Schwartz, is a contributing author, Microstructure of Equity Markets, 17-38.
Book Description: Interest in market microstructure has grown dramatically in recent years due largely in part to the rapid transformation of the financial market environment by technology, regulation, and globalization. Looking at market transactions at the most granular level—and taking into account market structure, price discovery, information flows, transaction costs, and the trading process—market microstructure also forms the basis of high-frequency trading strategies that can help professional investors generate profits and/or execute optimal transactions. Part of the Robert W. Kolb Series in Finance, Market Microstructure skillfully puts this discipline in perspective and examines how the working processes of markets impact transaction costs, prices, quotes, volume, and trading behavior. Along the way, it offers valuable insights on how specific features of the trading process like the existence of intermediaries or the environment in which trading takes place affect the price formation process.https://digitalcommons.fairfield.edu/business-books/1036/thumbnail.jp
The Solution of Lateral Heat Loss Problem Using Collocation Method with Cubic B-Splines Finite Element
No full textThis paper deals with the solutions of lateral heat loss equation by using collocation method with cubic B-splines finite elements. The stability analysis of this method is investigated by considering Fourier stability method. The comparison of the numerical solutions obtained by using this method with the analytic solutions is given by the tables and the figure.</jats:p
The role of lung ultrasound in dyspneic patients at emergency department
No full textGiriş: Dispne; yaygın görülen ve hastaların hayat kalitesini önemli ölçüde düşüren bir semptomdur.[2] Dispne ayırıcı tanısında başta kardiyovasküler ve solunum sistemi olmak üzere birçok sistem akla gelmelidir. [4] Dispneye neden olan kardiyak ve kalp dışı nedenleri birbirinden ayırt etmek ise büyük bir sorundur.[5] Akciğer ultrasonografisi (USG), son dönemlerde plevral ve perikardiyal effüzyon, ampiyem, pnömotoraks, pulmoner tromboembolizm (PTE) ve pnömoni gibi torasik patolojilerin tanısını hızlı koymada çok başarılı bir yatak başı tanı aracı haline gelmiştir.[10] Bu çalışmada, acil servise dispne şikayeti ile başvuran hastalarda akciğer USG'nin diğer tanı yöntemleri ile karşılaştırılıp, acil servislerde hızlı ve güvenilir bir tanı aracı olup olmadığının araştırılması amaçlanmıştır. Gereç ve Yöntem: Çalışma; prospektif gözlemsel klinik bir çalışma olarak dizayn edilmiş, acil servisimizde 01.12.2012-28.02.2013 tarihleri arasında yapılmıştır. Birincil şikayeti dispne olan tüm hastalara, hastanın kliniğinden habersiz olan acil tıp hekimlerince akciğer USG ile BLUE protokol uygulanmıştır. Bulgular: Akciğer USG ile BLUE protokol uygulanan ve B profili saptanan hastaların (n=92) KKY tanısındaki duyarlılığı %87,6 ve özgüllüğü %97,6 saptanmıştır. BLUE protokol algoritmalarında PLAPS (n=23), AB profili (n=40), C profili (n=10) ve B' profili (n=5) saptanmasının pnömoni tanısındaki duyarlılığı 82,4 ve özgüllüğü 99,0'dır. A profili saptanan hastalarda (n=196) astım/KOAH tanısı koymadaki duyarlılığı %98,6 ve özgüllüğü %67,5 olarak bulunmuştur. A profili ile beraber alt ekstremite venlerinde tromboz saptanan hastalarda (n=6) PTE tanısı koymadaki duyarlılığı %46,2 ve özgüllüğü %100 saptanmıştır. Akciğer noktası bulgusunun (n=5) pnömotoraks tanısındaki duyarlılığı %71,4, özgüllüğü ise %100 olarak bulunmuştur. Çalışmada BLUE protokol algoritması içerisinde olmamasına rağmen plevral ve perikardiyal efüzyona bakılmış ve 82 hastada plevral yada perikardiyal efüzyon saptanmştır. Normalde astım/KOAH grubundaki 23 hastada plevral, perikardiyal ya da pleval+perikardiyal efüzyon saptanmış ve bu hastaların acil servis yönetimi değişmiştir. Sonuç: Acil servislerde sık karşılaşılan ve ciddi bir dispne nedeni olan plevral ve perikardiyal efüzyonun BLUE protokol algoritmalarına eklenmesi, acil tıp hekimlerine dispne nedenini belirlemede daha doğru bir şekilde yardımcı olabilir.Objective: Dispnea; a common symptom that significantly reduces the quality of life of the patients. In the differential diagnosis of dyspnea, many systems should be considered especially including the cardiovascular and respiratory systems. It's a big issue to distinguish between the cardiac or non-cardiac causes of the dispnea. Recently lung ultrasonography (USG) is a successful bedside diagnostic tool to establish the diagnosis of thoracic pathologies such as pleural-pericardial effusion, empyema, pneumothorax, pulmonary thromboembolism (PTE) and pneumonia. In this study, we aimed to compare lung USG with other diagnostic methods on patients who presented to the emergency department with dyspnea, and investigate whether lung USG is rapid and reliable diagnostic tool in the emergency department. Method: This study was performed as a prospective observational study in Gazi University Emergency Department between January 2012-February 2013. The BLUE-protocol was applied to all patients with a primary complaint of dyspnea by emergency physicians who are unaware of patient's clinical information. Results: Patients were performed BLUE-protocol and determined the B profile in the diagnosis of patients (n=92) with CHF 87,6% sensitivity and 97,6% specificity was detected. In BLUE-protochol algorithms, the sensitivitiy and specifity of determining PLAPS (n=23), AB profile (n=40), C profile (n=10) and B' profile (n=5) in the pneumonia diagnosis were 82,4% and 99,0%, respectively. It was found that sensitivity and specifity were 98,6% and 67,5%, respectively for Asthma / COPD diagnosis in patients (n=196) with A profile. It was determined that sensitivity and specifity were 46,2% and 100%, respectively for PTE diagnosis in patients with A profile and lower extremity venous thrombosis. It was found that sensitivity and specifity were 71,4% and 100%, respectively for the diagnosis of pneumothorax in patients with lung point. The pleural and pericardial effusion were evaluated in the study, although they are not included in BLUE-protocol algorithm, and the pleural or pericardial effusion was detected in 82 patients. The pleural, pericardial or pleural+pericardial effusion were detected in 23 patients of Asthma/COPD group, and the management of these patients was changed in the emergency department. Conclusion: The evaluation of pleural and pericardial effusion which are the cause of severe dyspne and frequently encountered in emergency service, in BLUE protochol algorithm may help the emergency service physicians to determining the cause of dyspnea
Levels of interleukin 6 and tumor necrosis factor alfa in serum from fibrosarcoma induced rats
No full textSitokinler vücutta değişik hücreler tarafından sentezlenen, multi fonksiyonel polipeptitlerdir. TNF-alfa ? doğal ve kazanılmış bağışıklık, hücre regülasyonu, farklılaşması ve apoptosis süreçlerinde önemli rollere sahip pleitropik bir sitokindir. IL-6 doğal ve kazanılmış bağışıklık, karsinoma ve B hücresiz leukimelerde çoğalmayı önleyici, değişik dokuların büyümesini, farklılaşmasını düzenleyen bir çok işleve sahiptir. Kanserlerde erken teşhis yanında prognozun tayini, hastanın yaşamını uzatmada ve daha uygun tedavi şekillerinin tespit edilmesinde büyük önem taşımaktadır. Çalışmada ratlarda deneysel olarak 3-metilkolantren ile oluşturulan fibrosarkomlarda IL-6 ve TNF-alfa ? düzeyleri belirlendi. Araştırmanın materyalini 16 adet 8 haftalık ağırlıkları 150?200 gram olan erkek Spraque Dawley türü rat oluşturdu. Ratlar her grupta 8 adet olmak üzere iki gruba ayrıldı. Birinci grup kontrol, ikinci grup deneme grubunu oluşturdu. Hayvanlara tüm deney boyunca kuru pelet yem ve içme suyu adlibitium olarak verildi. Deneme süresi 150-210 gün sürdü. Deneme süresinin başında deneme grubundaki ratların boyun bölgelerinin dorsaline 0,25 ml susam yağında çözdürülen 0,2 mg 3-metilcholantren fibrosarkoma oluşturmak üzere deri altı yolla tek doz enjekte edildi. Kontrol grubuna ise tek doz 0,25 ml susam yağı deri altı yolla enjekte edildi. Deney süresi boyunca hayvanlar periyodik olarak kontrol edilip tümoral oluşum yönünden palpe edildi. Deney süresinin sonunda ratlara eter anestezisi altında kalbin atrium kısmından alınan kanlar santrifüj edilerek serumları ayırıldı. Hazırlanan serumlarda IL-6 ve TNF-alfa ? düzeylerine ?? , ELISA yöntemiyle BioSource firmasının kitleriyle bakıldı. Deneme grubundaki ratlarda serum IL-6 düzeyleri 67,85 ± 3,13 pg/ml, kontrol grubunda ise 38,45 ± 3,39 pg/ml olarak tespit edilmiş olup deneme grubundaki serum IL-6 düzeyinin kontrol grubuna göre 1,8 kat arttığı belirlendi. TNF-alfa ? düzeyleri ise deneme grubunda 53,35 ± 9,08 pg/ml, kontrol grubunda ise 26,42 ± 2,22 pg/ml olarak tespit edilmiş olup deneme grubundaki serum TNF-alfa düzeyinin kontrol grubuna göre 2 kat arttığı belirlendi. Elde edilen bulgular sonucunda, çalışma sonuçlarının, kanserin patognezinin aydınlatılması ve prognozu alanında yapılacak çalışmalara katkıda bulunacağı, kanısına varılmıştır. Anahtar kelimeler; Fibrosarkoma, IL-6, TNF-alfa ?
Cytokines, produced by virtually all types of cells, are multifunctional polypeptide. TNF-alfa is a plethoric cytokine that has a major role in natural and acquired immune, cell regulation and differentiation and apoptosis. IL-6 has a lot of functions in natural and acquired immune, inhibit cell growth at carcinoma and leukemia without B cell, tissue?s growthing and differential. It is very important at the prognosis, survival, available therapy in cancer. In this study, serum IL-6 and TNF-alfa ? levels were investigated in fibrosarcoma induced by 3-methylcholantrene. Sixteen male Spraque Dawley rats were used in this study. They were 8 weeks old and the body weights of the rats were between 150-200 grams. Rats were allocated into two groups each containing 8 rats. During the experiment which took between 150-210 days depending on the apperance of tumor tissue. They were allowed free access to water and feed in order to induce fibrosarcoma in rats, at the beginning of the experiment animals were injected subcutaneously on the neck with 0,2 mg 3- methylcholantrene solved in 0,25 ml sesame oil. To find out weather any tumor tissue occurred animals were palpated daily. At the end of the experiment, the blood of animals was taken from atrium of the hearth under the ether anesthesia and than serum was prepared. Serum IL-6 and TNF-alfa ?? levels were analyzed using BioSource kits at ELISA. Serum IL-6 levels were found 67, 85 ± 3,13 pg/ml in experimental group, 38, 45 ± 3,39 pg/ml in control group. It was 1, 8 times higher than controls. Serum TNF-alfa ? levels were 53, 35 ± 9,08 pg/ml in experimental group, 26, 42 ± 2,22 pg/ml in control group. It was 2 times higher than controls. In the light of this finding ıt is thought that results of study are beneficial to understand pathogenesis and prognosis of cancer. Key words; Fibrocarcoma, IL-6, TNF-alfa
Role of using metronome for improving the quality of cardiopulmonary resuscitation
No full textGiriş ve amaç: Kardiyopulmoner resüsitasyon (KPR) kılavuzları kaliteli KPR'nin hasta sağ kalım ve nörolojik sonuçlarını olumlu etkilediğini belirtmektedir. Bu çalışmada metronom cihazının profesyonel sağlık çalışanlarının uyguladığı KPR kalitesi üzerine etkisinin araştırılması amaçlanmıştır. Gereç ve Yöntem: Bu çalışma prospektif, simülasyon tabanlı, tek kör bir klinik çalışma olarak tasarlanmıştır. Haziran ve Ağustos 2017 tarihleri arasında Gazi Üniversitesi Tıp Fakültesi Hastanesi Yoğun bakımlarında çalışan 102 araştırma görevlisi çalışmaya katılmıştır. KPR performansları klasik tipte ve metronom cihazı eşliğinde olmak üzere iki oturum şeklinde yapılmıştır. Erişkin tip maket üzerinde 2 dakika süren KPR performansları TrueCPR Coaching Device® ile kayıt edilmiştir. KPR performansları boyunca kompresyon kalitesi, dekompresyon kalitesi ve dakikada ortalama göğüs kompresyon hızı kaydedilmiştir. Araştırmaya katılan hekimlerin cinsiyet, boy, kilo, beden kitle indeksi (BKİ) gibi özellikleri kaydedilmiştir. Ayrıca katılımcılara metronom cihazının uyguladıkları KPR üzerine etkileri sorulmuştur. Bulgular: Çalışmaya katılanların 39'u (%32,8) bayan, yaş ortalaması 28,02±2,6 yıl, BKİ ortalaması 24,52±2,92 kg/m2 idi. Metronom cihazı eşliğinde yapılan KPR'de klasik yönteme kıyasla kompresyon kalitesi, dekompresyon kalitesi ve bası hızlarında istatistiksel olarak anlamlı iyileşme bulunmuştur (sırasıyla, p=0.001 p=0.001, p=0.001). Metronom kullanımı BKİ <25 kg/m2 olanlarda kompresyon kalitesini anlamlı oranda artırmaktadır (p=0.015). BKİ'nde 1 birimlik artışın kompresyon skorunda yaklaşık 2,5 birim artışa neden olduğu belirlenmiştir (B=2,45, p<0,001). Katılımcıların 68'i (%66,7) KPR sırasında kesinlikle metronom cihazı kullanmayı tercih edeceklerini belirtmiştir. Sonuç: Kardiyopulmoner resüsitasyon esnasında metronom cihazı kullanılması kompresyon ve dekompresyon kalitesini arttırmaktadır ve göğüs basısı hızını iyileştirmektedir.Introduction: Cardiopulmonary resuscitation (CPR) guidelines emphasize the importance of quality of CPR in improving outcomes. In this study, We was aimed to investigate the effect of metronome device on CPR quality. Materials and Methods: This study was designed as a prospective, simulation-based, single-blind clinical trial. The residents working in intensive care unit at Gazi University Medical Faculty Hospital were enrolled to the study between June and August 2017. CPR performances were conducted in two sessions, classical type and with metronome device. An adult type manikin was used in this study. CPR was applied for two minutes and performances were recorded with TrueCPR Coaching Device®. Compression quality, decompression quality and mean chest compression rate were recorded at both sessions. Participants's characteristics such as gender, height, weight, body mass index (BMI) were recorded. In addition, participants were asked about the effects of the metronome device on CPR. Results: Hundred and two residents were enrolled in the trial (32,8% female, average age 28,02±2,6 years and average BMI 24,52±2,92 kg/m2). The compression quality, decompression quality and mean chest compression rate were statistically significantly improved in CPR with metronome device. (respectively,p=0,001, p=0,001 and p=0,001). Metronome use statistically significantly improved compression quality in BMI <25 kg/m2 (p=0.015). One kg/m2 increase in the BMI was found to cause an increase of about 2.5% in the compression quality score (B = 2.45, p <0.001). 66.7% of the respondents said they would definitely prefer to use the metronome device during CPR. Conclusion: Using a metronome device during CPR increases the quality of compression and decompression. Also the rate of chest compressions during CPR can be optimized by the use of a metronome device
Optimal perturbation iteration method for Bratu-type problems
No full textIn this paper, we introduce the new optimal perturbation iteration method based on the perturbation iteration algorithms for the approximate solutions of nonlinear differential equations of many types. The proposed method is illustrated by studying Bratu-type equations. Our results show that only a few terms are required to obtain an approximate solution which is more accurate and efficient than many other methods in the literature. © 2016 The Author
Modification of perturbation-iteration method to solve different types of nonlinear differential equations
No full textPerturbation iteration method has been recently constructed by Pakdemirli and co-workers. It has been also proven that this technique is very effective and applicable for solving some nonlinear differential equations. In this study we suggest a modification to expedite the solution process of perturbation-iteration algorithms. This work might greatly improve the computational efficiency of the perturbation iteration method and also its Mathematica package to solve nonlinear equations. Numerical illustrations are also given to show how modified method eliminates cumbersome computational work needed by perturbation iteration method. © 2017 Author(s)
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