The development of Puccinia hordei on different barley cultivars

Imperial Users onl

Essays in dynamic public finance

An upcoming trend in public finance is applying economic theory to understand how private agents' incentives, expectations, and perceptions affect the efficiency and sustainability of government policies. This doctoral dissertation presents novel studies that fall into this category. The first three chapters examine many aspects of tax amnesties from this perspective, while the last chapter studies intergenerational risk-sharing under limited enforcement. The first chapter introduces a selection of stylized facts about tax amnesties by examining the recent state-level tax amnesty experiences in the US. We provide observational evidence on the heterogeneity of tax amnesty implementations among US states. The heterogeneity is also persistent throughout the last four decades. We show that a few states declaring amnesties very rarely in the 80s and 90s start to implement amnesties much more frequently in recent decades. We also observe that the tax amnesty declarations of US states cluster around the US recession periods. The second chapter introduces a theoretical framework to investigate the strategic interaction between a government and taxpayers in an economy. Our model predicts four factors that make a tax amnesty more likely in an economy: high personal income; high tax rates; low political cost for declaring an amnesty; and low audit rates. We examine US statelevel data to test this prediction and show that the states with high personal income and high tax rates are using tax amnesties more frequently. We also show that the self-fulfilling characteristic of tax amnesties may lead to sub-optimal outcomes under lack of commitment. In the third chapter, we present a theoretical framework to explain the recurring nature of tax amnesties. We construct a model with the strategic interaction of a government and a mass of taxpayers. The government and the taxpayers interact repeatedly, and each interaction can result in a tax amnesty. We show that an amnesty can cause another amnesty in the near future by altering taxpayers' beliefs about unobservable government characteristics. Therefore, an economy may get into a sequence of successive tax amnesties through a reputational channel referred to as an "expectation trap." The expectation trap mechanism can explain the series of tax amnesties in some US states that rarely experienced tax amnesties in the past. Extending our baseline model shows that a recession may cause a tax amnesty, which can trigger a sequence of further amnesties that can spread into the years after recovery from the recession. In the fourth chapter, we study the sustainable intergenerational insurance schemes under lack of enforcement. The welfare improving insurance policies may not be implementable under limited enforcement since any agent can opt-out of the insurance scheme if it does not benefit her. We develop a 2-period overlapping generations model to study the impact of different government policies. A standard tax-and-transfer scheme cannot provide perfect risk-sharing. To improve intergenerational risk sharing, we first introduce money into the system. We show that introducing money into the baseline model may improve risk-sharing. We also investigate the possibility of providing further risk-sharing by using monetary policy. We show that a monetary policy rule improves welfare under a numerical example.Programa de Doctorado en Economía por la Universidad Carlos III de MadridPresidente: Nicola Pavoni.- Secretario: Piero Gottardi.- Vocal: Andrés Erosa Etchebeher

Higher education during times of crisis in Türkiye

In this special issue, Yaprak Gürsoy and Özge Onsural-Beşgül bring together Turkish academics and scholars to discuss the recent and ongoing crises in Türkiye and their impact on the higher education secto

Instruments of right costs with activity based costing system: An application in automotive sector

Geleneksel maliyet sistemi ile yapılan hesaplamaların etkin ve reel olmaması işletmeleri çağdaş maliyetlendirme sistemlerini araştırmaya ve uygulamaya yönlendirmiştir. Bu çalışmada, faaliyet tabanlı maliyet (FTM) sisteminin, otomotiv sektöründeki bir işletmede uygulanmasına yer verilmiştir. Çalışmanın amacı, işletmenin nihai zararını engelleyebilmek ve doğru maliyetlendirme yapabilmek için hangi süreçlerde hangi araçlardan yararlanacağını tespit etmek ve FTM’nin geleneksel maliyet yöntemi ile arasındaki farkı ortaya koymaktır. Uygulama sonucunda FTM yöntemine göre hesaplanan ürün maliyetleri ile geleneksel maliyet yöntemlerine göre hesaplanan ürün maliyetleri karşılaştırılarak, farklılıklar ortaya konulmuş ve yapılan çalışma ile ürün maliyetleri daha doğru hesaplanarak daha yüksek kazanç elde edilebilmiştir.Ineffective and unrealistic cost calculations of traditional costing systems led the businesses to the search and application of modern costing systems. This study includes an application of activity based costing (ABC) method in a company operating in automotive industry. The purpose of the study is to determine the instruments that should be utilized under different costing systems to avoid losses and to ensure the accuracy of the costing and to introduce the differences between ABC and traditional costing systems. The results obtained through the comparison of ABC and traditional costing system showed that companies may obtain higher earnings by using more accurate product costing systems

Hidden hazard in appendix in children: Carcinoid tumors

Introduction: Carcinoid tumors (CT) are the most common tumors of the appendix. The incidence of CT of the appendix is generally 1–2 in every 1000 appendectomy material. Objectives: The objectives of the study were to discuss the follow-up and treatment of CT of the appendix in the specimen of patients who underwent an appendectomy. Materials and Methods: This retrospective study enrolled the patients who were diagnosed with CT of the appendix as a result of an examination of the appendix specimen after the patients underwent an appendectomy. All the patients, who underwent appendectomy in the pediatric surgery clinic of our hospital between November 2015 and November 2018, were included in the study. Patients’ demographic characteristics, clinical findings, pre-operative laboratory and imaging results, location, diameter and size of the tumor, mesoappendix invasion status, mitotic index and Ki-67 elevation, hospital stay duration, surgical types and complications, and results of laboratory and imaging tests were evaluated. Findings: Eight of the 621 patients (1.2%) who underwent an appendectomy were diagnosed with CT of the appendix. The median age of the patients was 13 years (range, 11–16 years). Of the eight patients, five (62.5%) were female and three (37.5%) were male. All patients presented to our clinic with abdominal pain. No surgical complications were observed during the operation and in the early post-operative period. The mean hospital stay was 2.7 days (2–5 days). In all the patients, the tumor size was <2 cm, the surgical margins were clean, the mitotic index was <2%, the Ki-67 index was below 1%, and the tumor had not spread to the mesoappendix. Only in one of the patients, the CT was located in the appendix radix; in the other seven patients, the tumor was in the middle and end of the appendix. Conclusion: CT of the appendix are clinically similar to acute appendicitis but may be found incidentally during other surgical procedures other than an appendectomy. Diagnosis is made after the pathological specimen diagnosed with CT is histopathologically evaluated. The size, diameter, and depth of the tumor, mesoappendix invasion, mitotic index, and Ki-67 elevation are used in the evaluation and treatment of the tumor

Pierre Robin sequence in association with tracheoesophageal fistula and esophageal atresia

The first symptom of esophageal atresia and tracheoesophageal fistula is the inability to eat and respiratory distress after feeding. The coexistence of Pierre Robin Sequence (PRS) with esophageal atresia and tracheoesophageal fistula is a rare clinical condition. In infants with PRS, evaluation of respiratory and nutritional problems is important. The coexistence of esophageal atresia and tracheoesophageal fistula leads to increased nutritional and respiratory problems. Problems that may occur in the airways may occur late. In this case report, we aimed to present a case of neonatal infant with rare esophageal atresia, tracheoesophageal fistula, and PRS

Yapay sinir ağlarının uyarlanabilir donanımsal yapılarda gerçeklenmesi

06.03.2018 tarihli ve 30352 sayılı Resmi Gazetede yayımlanan “Yükseköğretim Kanunu İle Bazı Kanun Ve Kanun Hükmünde Kararnamelerde Değişiklik Yapılması Hakkında Kanun” ile 18.06.2018 tarihli “Lisansüstü Tezlerin Elektronik Ortamda Toplanması, Düzenlenmesi ve Erişime Açılmasına İlişkin Yönerge” gereğince tam metin erişime açılmıştır.Yapay Sinir Ağları (YSA'lar), biyolojik sinir sistemine dayalı elektronik modellerdir. YSA'lar girişlerden gelen verileri işleyen birbirine bağlı yapay nöronlardan oluşmaktadır. Bu mimariler, yazılım ya da donanım olarak gerçekleştirilebilirler. YSA'nın yazılım uygulamasının avantajı, tasarımcının YSA bileşenlerinin iç işleyişini bilmesine gerek olmamasıdır. Bununla birlikte, gerçek zamanlı uygulamalarda, yazılım tabanlı YSA'lar donanım tabanlı YSA'lardan daha yavaştır. YSA hesaplamaları paralel olarak gerçekleştirilmektedir ve paralel işlem için özel donanım aygıtları gereklidir. Birçok alandan araştırmacılar optimizasyon, sınıflandırma, kontrol, görüntü işleme vb. problemlerin çözümü için YSA donanım uygulamaları gerçekleştirmişlerdir. Bu uygulamalar, YSA'ların paralel doğasından yararlanmak için farklı türde cihazlar üzerinde gerçekleştirilmiştir. YSA'nın FPGA uygulamaları, yeniden yapılandırılabilir yapısı ve paralel mimarisi nedeniyle son yirmi yılda büyük ilgi uyandırmıştır. Bu tez çalışmasında, Quartus II şematik tasarım kullanılarak eğitilebilir çok katmanlı sinir ağı (MLNN) yapısının donanım uygulaması FPGA üzerinde tamamen kombinasyonel mantık olarak gerçekleştirilmiştir. Yapay sinir ağını eğitmek için eğim düşüm metodunu kullanan geri yayılım algoritması uygulanmıştır. Nümerik tanımlama için IEEE tek-hassasiyetli kayan-noktalı format kullanılmıştır. Bu çalışma aynı zamanda IEEE tek-hassasiyetli kayan-noktalı format ile tam uyumlu hızlı bir kayan noktalı toplayıcı, bir paralel çarpıcı ve bir sigmoid aktivasyon fonksiyonu bloğunu sunmaktadır. İşlemleri paralel olarak gerçekleştiren toplayıcı, paralel çarpıcı ve aktivasyon fonksiyonu bloğu tamamen kombinasyonel mantık olarak tasarlanmıştır. Bu yeni tasarımda, gecikmeyi azaltmak için kaydırma işlemlerinde kaydırmalı yazmaçlar yerine üç-durumlu tampon serileri kullanılmıştır. Üç-durumlu tampon serileri kullanıldığından kaydırma işlemi için saat darbesi gerekli değildir ve böylece sonuç tek bir çevrimde üretilir. Sadece kapı gecikmesi maliyetli önerilen tasarım, YSA'nın donanım uygulamaları için uygundur.Artificial Neural Networks (ANNs) are electronic models based on biological nervous system. ANNs are made up of interconnected artificial neurons which can process values from inputs. These architectures can be implemented either in software or in hardware. The advantage of the software implementation of ANN is that the designer does not need to know the inner workings of ANN components. However, in real time applications, software based ANNs are slower than hardware based ANNs. ANN computations are carried out in parallel and special hardware devices are required for parallel processing. Researchers from many disciplines have been performing ANN hardware implementations to solve a variety of problems in optimization, classification, control, image processing etc. These applications have been performed on different types of devices to take advantage of the parallel nature inherent to ANNs. FPGA implementations of ANN have aroused great interest during the last two decades due to its reconfigurable structure and parallel architecture. In this thesis, hardware implementation of trainable Multi Layer Neural Network (MLNN) structure on FPGA (Field Programmable Gate Array) is realized as entirely combinational logic by using Quartus II schematic design. The back propagation algortihm, which uses gradient descent metod is implemented in order to train the neural network. IEEE single-precision floating-point format is used for numerical description. This study also presents the hardware designs of a fast floating point adder, a parallel multiplier and a sigmoid activation function block that are fully compliant with the IEEE single-precision floating-point format. The adder, parallel multiplier and the activation function block are designed as entirely combinational logic that perform operations in parallel. In this novel design, tri state buffer series are used for shifting operations instead of shift registers for reducing latency. Because the use of tri-state buffer series, clock pulse is not required for shifting and thus the result is generated in only a single clock-cycle. The proposed design is suitable for hardware implementation of ANN at the cost of gate delays only

An Analysis on compositional effect during the great trade collapse

Ankara : Department of Economics İhsan Doğramacı Bilkent University, 2014.Thesis (Master's) -- Bilkent University, 2014.Includes bibliographical refences 40-41.This thesis focuses on one of the famous hypotheses on The Great Trade Collapse which is compositional effect hypothesis. It includes three different parts. The first part examines the method of Levchenko, Lewis, Tesar (2010) for testing compositional effect, attempts to reproduce the results and conducts some robustness analysis of their results. The second part suggests some modifications on the existing model and applies the newly modified model to the US data. The findings suggest that compositional effect is an important factor of the US trade collapse during the The Great Recession. In the last part, the new model is applied to Turkey and the findings show that the compositional effect is not a significant factor of the trade reduction in Turkey. This result could be an indicator which shows that trade of the emerging countries are not governed by the same factors that drive developed country trade falls during the recent economic crisis.Bağırgan, OnursalM.S

Z Plasty Single Center Results in The Treatment of Pilonidal Sinus Disease in Children: Z Plasty Results in the Treatment of Pilonidal Sinus Disease

Pilonidal sinus is a common chronic disease of the sacrococcygeal region. Treatment varies according to the clinical presentation of the disease. Although many surgical methods have proposed, the ideal approach is still lacking due to high recurrence rates. This study aimed to evaluate the role of Z-plasty in achieving primary recovery in pilonidal disease and morbidity and recurrence. Twenty-four patients (15 males and nine females) who underwent sinus excision and Z-plasty closure for the sacrococcygeal pilonidal sinus included in this study. Follow-up ranged from 6 to 12 months. There were 15 males and nine females with a median age of 16 years. The mean hospital stay was two days. There was no recurrence, and all patients were satisfied with the cosmetics. Two patients (5%) had numbness on the flap. No flap necrosis observed in any patient. Only three patients had a wound infection (7.5%). Wound seroma developed in five patients (12.5%). Although some technical expertise is required, excision of sinus and Z-plasty provides superior results in terms of recurrence and hospitalization of pilonidal sinus patients during hospitalization