Essays on nonlinear dynamics in optimal growth models

Ankara : Department of Economics İhsan Doğramacı Bilkent University, 2014.Thesis (Ph. D.) -- Bilkent University, 2014.Includes bibliographical references leaves 79-84.Economic models with time delay have long been considered in economic theory. It is considered that delay forces the economic system into persistent cycles which can be interpreted as intrinsic crises of the capitalist economy. The e§ect of delay on economic dynamics is analyzed by Hopf bifurcation according to the recent developments in economics and mathematics. Hopf bifurcation depends on the existence of a pair of pure imaginary eigenvalues of the Jacobian matrix evaluated at the steady state. However, recent studies are inconsistent in a determinate way to decide whether the optimal growth model with investment lags admits persistent cycles or not. In the second chapter of this thesis, the author tries to sharpen the analysis of one sector optimal growth model with one control and one state variables and time delay. We Örstly give a brief outline of the mathematical history and ëknow-howíof delays in economic models, as well as its interpretation, and then, we further the analysis set of the model of Asea and Zak (1999) and try to introduce of a new technique for the exposition of the eigenvalues of the characteristic equation of these type of models in a generalized framework. In the third chapter we introduce a new technique (see Louisell, 2001) to the study of economic models with delays and incorporate this technique to evaluate the cycleinducing e§ects of capital dependent population growth in economic models with time delay. We employ the Solow-Kalecki framework and show that the presence of capital dependent population growth induces cycles. Other than the introduction of a new technique into the area of economics, one particular contribution of this chapter is that the results clearly shows that delay is not su¢ cient in inducing cycles even in the most simple economic models. In the forth chapter, we show that Hopf bifurcation may emerge in an overlapping generations resource economy through a feedback mechanism between population and resource availability. In overlapping generations resource economy models, the cycle inducing factor is mainly the nonlinearity of the regeneration of the resources. On the contrary, we assume linear regeneration and yet, endogenize the population growth rate. We show that the interaction between instantenous population growth and regeneration rate triggers persistent cycles in the economy. In the Öfth chapter, we employ a continuous delay structure in the process of recruitment in the population growth in an optimal growth model and hence obtain cyclic solutions. We exploit Erlangian process in the population growth mechanism. As far as we know, the incorporation of Erlangian process in optimal growth models is handled in this chapter for the Örst time in economic literature. Through this mechanism, not only the population is considered as a function of per capita capital, or in other words, population growth is endogenized, but also the current level of population growth is linked with those of older generations. We Önd out that the interaction between the e§ect of older generationsífertility choices and the accumulation of capital induces cyclic behaviour in the economy. The sixth and the last chapter concludes with future research agenda. Overall, the thesis considers the e§ects of delay and endogenized population on the economies of interest (Solow, overlapping generations, optimal growth model) economically and tries to introduce the existing methods and develop new ones to investigate the e§ects of delay and endogenized population on the eigenvalues of the Jacobians that the drive the economies of interest at their steady states.Yüksel, Mustafa KeremPh.D

On the existence of Hopf cycles in optimal growth models with time delay

Ankara : The Department of Economics and the Institute of Economics and Social Sciences of Bilkent University, 2008.Thesis (Master's) -- Bilkent University, 2008.Includes bibliographical refences.In this thesis, we analyzed the existence of cycles `a la Poincar´e-AndronovHopf in optimal growth models with time delay. The analysis builds upon a new method developed, which investigates the number of pure imaginary roots of the characteristic equation. The method was applied to the time-tobuild models of Asea and Zak (1999) and Winkler (2004).Yüksel, Mustafa KeremM.S

Investigation of teachers’ stress level caused by applications of supervision

Bu araştırmanın amacı, ilköğretim kurumlarındaki teftiş uygulamalarının öğretmenlerde yarattığı stres düzeyini ortaya koymaktır. Araştırmada tarama modeli kullanılmıştır. Araştırmanın evrenini, 2009-2010 öğretim yılında Samsun ili Merkez, Asarcık, Vezirköprü ve Lâdik ilçelerindeki ilköğretim okullarında görev yapan 3163 öğretmen oluşturmaktadır. Örneklemini ise, evrenden “tesadüfî örnekleme yöntemiyle seçilen 402 öğretmen oluşturmaktadır. Veriler araştırmacılar tarafından geliştirilen 34 maddelik bir ölçekle toplanmıştır. Ölçeğin Cronbach Alfa değeri 0,94’dür. Ölçekle elde edilen veriler ortalama, standart sapma, t testi ve tek yönlü varyans analizi ile çözümlenmiştir. Araştırmada elde edilen sonuçlara göre, öğretmenler, “müfettişin olumsuz davranışları” ve “değerlendirme kriterleri”nden dolayı “ortalama değerin üstünde” bir stres yaşarken, “teftiş sisteminin genel olumsuz etkileri”nden dolayı “ortalama değere oldukça yakın” bir düzeyde stres yaşamışlardır. Öğretmenlerin teftiş uygulamalarından dolayı genel olarak “orta düzeyin üzerinde” bir stres yaşamışlardır. Öğretmen görüşleri arasında bölge, cinsiyet, mesleki kıdem ve ödül değişkenine göre anlamlı farklılıklar bulunurken, yaş, eğitim ve hizmet içi eğitim değişkenine göre anlamlı bir fark bulunamamıştır.The purpose of this study is to determine level of stress on elementary school teachers which applications of supervision cause. In the study survey method was used. The universe of the research consisted of 3163 elemetary school teacher who worked in schools in Samsun, Asarcik, Lâdik, Vezirkopru. Sample of the study consisted of 402 elementary school teachers who were chosen randomly. Data was collected through the scale with 34 items which was developed by the researchers. The scale’s value of Cronbach Alpha is 0.94. The data that was collected by means of the scale, was analyzed in terms of means, standart deviation, t-test and one way ANOVA. According to results the teacher experienced more stress than the mean because of “the supervisor’s negative behaviours” and “evaluation criteria” and they had a stres level that was very close to the mean because of general negative effects of supervision. the Teachers generally experienced more stress than means due to the applications of supervision. While significant differences were found according to district, gender, professional experience and professional awards, no significant difference was defined with respect to age, edecational level and in-service education

Türkiye’de bütçe harcamaları: Farklı dağılımların ekonomik büyümeye etkisi

Bu çalışma, Türkiye'nin 2001 krizi sonrasında uyguladığı maliye politikasına bütçe harcamaları perspektifinden baktıktan sonra, kamu harcamalarının büyümeye katkısını, dinamik bir model çerçevesinde incelenmektedir. Sonuçlar, 2001 sonrasında izlenen maliye politikasının bütçe disiplini üzerindeki olumlu etkilerini göstermekle beraber, son dönemde bütçenin harcama katılığında ve yapısal bütçe dengesinde bazı olumsuzlukları da tartışmaya açmaktadır. Bununla beraber, kamunun üretimi arttıracak altyapı yatırımlarına daha fazla ağırlık vermesi gerektiği bulunmaktadır. Eğitim ve sağlığa ayrılan kamu sermaye stokunun büyüme üzerindeki etkileri ise fiziksel altyapı yatırımlarına ayrılan kamu sermaye stoku kadar yüksek değildir. Son olarak, kamunun idari harcamalarında verimlilik yoluyla sağlanacak bir azalmanın toplumsal fayda üzerinde önemli ve pozitif etkileri görülmektedir. Bu sonuç da, önümüzdeki dönemde kamu verimliliğini arttırıp idari harcamaları kısacak önlemlerin bir politika önceliği olması gerektiğini söylemektedir