On stability and efficiency in different economic environments

Ankara : The Department of Economics, İhsan Doğramacı Bilkent University, 2011.Thesis (Ph. D.) -- Bilkent University, 2011.Includes bibliographical references leaves 161-165.This thesis consists of four main chapters. In the first main part, hedonic coalition formation games where each player’s preferences rely only upon the members of her coalition are studied. A new stability notion under free exit-free entry membership rights, referred to as strong Nash stability, is introduced which is stronger than both core and Nash stabilities studied earlier in the literature. The weak top-choice property is introduced and shown to be sufficient for the existence of a strongly Nash stable partition. It is also shown that descending separable preferences guarantee the existence of a strongly Nash stable partition. Strong Nash stability under different membership rights is also studied. In the first main part, hedonic coalition formation games are also extended to cover formation games, where a player can be a member of several different coalitions, and these games are studied. In the second main part, Nash implementability of a social choice rule (via a mechanism) which is implementable via a Rechtsstaat is studied. A new condition on a Rechtsstaat, referred to as equal treatment of equivalent alternatives (ET EA), is introduced, and it is shown that if a social choice rule is implementable via some Rechtsstaat satisfying ET EA then it is Nash implementable via a mechanism provided that there are at least three agents in the society. In the third main part, a characterization of the Borda rule on the domain of weak preferences is studied. A new property, which is referred to as the degree equality, is introduced, and it is shown that the Borda rule is characterized by weak neutrality, reinforcement, faithfulness and degree equality. In the fourth main part, the graduate admissions problem with quota and budget constraints is studied as a two sided many to one matching market. The students proposing algorithm, which is an extension of the Gale-Shapley algorithm, is constructed, and it is shown that the students proposing algorithm ends up with a core stable matching if the algorithm stops. However, there exist graduate admissions problems for which there exist core stable matchings, while neither the departments proposing nor the students proposing algorithm stops. It is proved that the students proposing algorithm stops if and only if no cycle occurs in the algorithm. It is also shown that no random path to core stability for the graduate admissions problem exists.Karakaya, MehmetPh.D

Design and analysis of lightweight automotive component for turbocharger units

Nowadays global warming in parallel with air pollution is a significant problem. One of the major causes is the conventional fuel-powered automobile. This study focuses on reducing global warming caused by automobiles. This paper presents the results of redesign and analysis of piping component of a turbocharger unit from a new material in order to reduce the weight and unify the component from only one material. The existing component is composed of three different parts and materials. With the new design, in addition to the lightweight property, the component is designed in such a way that two separate parts of existing design are unified in a single part which simplifies the assembly of the component to the turbocharger unit. The design starts with choosing the convenient material to satisfy the necessary service conditions such as high temperature and pressure. Two different materials are considered for the analyses which are aluminium alloy and PA66+PA6-HI glass fiber reinforced plastic matrix composite material. Firstly, finite element analyses were performed by using a commercial software. The results of the finite element analyses showed that both materials showed resistance to tensile load of 4000 N and pressure of 0.4 MPa at 22°C. However, if two separate parts were unified with a single part made of aluminium alloy, this component would fail under pressure of 0.4 MPa at 150°C and 210°C, while the component made of PA66+PA6-HI glass fiber reinforced plastic matrix composite material resisted the pressure at higher temperatures. Tensile tests under 4000 N and pressure tests under 0.4 MPa at temperatures of 22°C, 150°C and 210°C were carried out on the component produced by PA66+PA6-HI glass fiber reinforced plastic matrix composite material. The same results were observed with those obtained by the finite element analyses. The design with the composite material satisfies both the mechanical and lightweight considerations.This work is supported by TUBITAK-Turkish Scientific and Technological Research Council under the project number: 7130723

Graduate admission problem with quota and budget constraints

Cataloged from PDF version of article.In this thesis, we have studied the graduate admission problem with quota and budget constraints as a two sided matching market. We constructed algorithms which are extensions of the Gale - Shapley algorithm and showed that if the algorithms stop then the resulting matchings are core stable (and thus Pareto optimal). However the algorithms may not stop for some problems. Also it is possible that the algorithms do not stop and there is a core stable matching. Also there is no department optimal matching and no student optimal matching under budget constraints. Hence straightforward extensions of the Gale - Shapley algorithm do not work for the graduate admission problem with quota and budget constraints. The presence of budget constraints play an important role in these results.Karakaya, MehmetM.S

Ethical Reasoning in STEM Disciplines

In this study, it was aimed to determine ethical reasoning of lecturers in STEM disciplines in terms of several independent variables (gender, working another institution, age, academic title, academic discipline, service period). This study was designed as a survey research. Lecturers in STEM disciplines in Kahramanmaras Sutçuimam University were selected as participants of the study. ‘‘Ethical Reasoning Instrument (ERI)’ which was developed by Titus, Zoltowski, Huyck, and Oakes (2011) was used in order to collect data by adapting into Turkish. Data were analyzed by the help of independent sample t-test, one-way ANOVA and Kruskal-Wallis tests. The findings indicated that for all independent variables there were no statistically significant difference (p>.05) in ethical reasoning of lecturers. As an interesting result, it was determined that lecturers in engineering discipline have less ethical awareness than lecturers in medicine and science disciplines. Keywords: STEM, STEM Disciplines, Ethics, Ethical Reasoning

Making Yogurt: A Practical Study to Develop an Understanding of Useful Bacteria

This study aims for students to comprehend the beneficial functions of bacteria with the traditional home yogurt leavening activity. Also, it aims to identify alternative concepts related to leavening and contribute to students' home yogurt consumption habits. The study is a case study. The study was conducted with 29 fifth-grade students studying at a public school in Istanbul in the 2019-2020 academic year and their parents. Questionnaire forms and student observation forms developed by the researchers were used as data collection tools. The obtained data were described by content analysis. Before the application, the participant students were given these three statements; microbes as a sample of microscopic creatures, yeast fungi caused yogurt formation, and yogurt is healthy because it was a dairy product. While after the application, participant students changed their statements to these three; the term microbe was not used as a sample of microscopic creatures, bacteria took part in the formation of yogurt, and yogurt is healthy because it contains microscopic creatures beneficial for the digestive system. The educational activities integrated into daily life contribute to students' conceptual learning

Evaluation of university students’ rating behaviors in self and peer rating process via many facet rasch model

Purpose: When self and peer assessment methods become commonly used in the teaching process, the most important problem turns out to be the reliability of the ratings acquired from these sources. Increasing the rater reliability has great importance in the performance evaluation for the reliability of the measurement. This study aimed to determine rater behaviors university students display in the process of self and peer assessment. The research was based on a descriptive model. The participants were 58 students at the Guidance and Psychological Counseling Program in 2017-2018 academic year at a foundation university in Ankara. Findings: Many Facet Rasch Model (MFRM) analysis was applied, and no statistically significant difference of raters' severity and leniency behaviors in the ratings was observed in terms of gender, but there was a statistically significant difference based on the rater types (self and peer). The raters seemed to be more lenient in self-assessments. The study also showed that while raters showed central tendency behavior on individual level, they did not show such tendency at the group level. It was concluded that individuals' ratings are more biased than group ratings when they evaluate group performance. Implications for Research and Practice: Some of the raters had differentiating rating behaviors based on the groups. The teacher candidates made systematic mistakes in the performance evaluation process and showed behaviors that had negative effect on the validity of the rating. It is important for the raters to conduct studies to reduce the scoring bias of the raters. (C) 2020 Ani Publishing Ltd. All rights reserve

DETERMINATION OF MIDDLE SCHOOL STUDENTS' VIEWS ABOUT STEM ACTIVITIES

In this research, it is aimed to determine the opinions of middle school students about STEM activities. The research, which used case study from qualitative research designs, was conducted in 2018-2019 academic year. The research working group is composed of 27 middle school students studying in a private school in Turkey. In the data collection, semi-structured interview forms prepared by the researchers were used. The data were analyzed in accordance with the content analysis steps. According to the findings of the research, it was determined that STEM activities were related to daily life problems, and that students' lessons, occupational preferences and communication skills were affected. In addition, lack of time and material and lack of information have been found to have problems in the realization of STEM activities

Caracterización química y morfológica de Allium tuncelianum (Amaryllidaceae) y potenciales antioxidantes y anticolinesterasa

Alzheimer’s disease is the main reason for dementia, which increases with age. Cholinesterase inhibition and antioxidant potentials of extracts and essential oils from bulbs of A. tuncelianum (Kollmann) Özhatay & al., an endemic species to Tunceli (easthern Turkey), were evaluated. The fraction extracted of ethyl acetate had the highest phenolics level, 1,1-diphenyl-2-picrylhydrazyl, and thiobarbituric acid antioxidant capacity. Also, the ethyl acetate fraction presented the highest acetylcholinesterase (15.98 ± 2.76%), and butyrylcholinesterase inhibition (47.33 ± 3.27%). Diallyl disulfide (49.8%), diallyl trisulfide (27.9%) and allyl methyl trisulfide (6.9%) were found to be the major components of essential oil. This paper shows that the ethyl acetate fraction of A. tuncelianum could be a potent source of antioxidant and anticholinesterase components.La enfermedad de Alzheimer es la causa principal de la demencia, cuya aparición aumenta según la edad. Se evaluaron la inhibición de la colinesterasa y el potencial antioxidante de los extractos y los aceites esenciales de los bulbos de A. tuncelianum (Kollmann) Özhatay & al., una especie endémica de Tunceli (este de Turquía). La fracción extraida de acetato de etilo presentó los niveles más altos de fenoles, 1,1-difenil- 2-picrilhidrazilo y capacidad antioxidante, ácido tiobarbitúrico. Asimismo, la fracción de etil acetato presentó la mayor capacidad de inhibición de acetilcolinesterasa (15.98 ± 2.76%) y butirilcolinesterasa (47.33 ± 3.27%). El disulfuro de dialilo (49.8%), el trisulfuro de dialilo (27.9%) y el trisulfuro de metil alilo (6.9%) fueron los componentes principales del aceite esencial. Este artículo muestra que la fracción de etil acetato de A. tuncelianum podría ser una fuente potencial novedosa de componentes antioxidantes y anticolinesterasa

İstanbul’daki Vakıf Üniversitelerinin Kuruluş Dönemlerine göre Etkinlik Analizi

Bu çalışmada Veri Zarflama Analizi (VZA) yöntemiyle İstanbul’da bulunan vakıf üniversitelerinin etkinliklerinin belirlenmesi, etkin olmayan üniversiteler için referans alabileceği referans kümesinin belirlenmesi ve kuruluş dönemlerine göre etkinlik düzeyleri arasında farklılık olup olmadığının belirlenmesi amaçlanmıştır. Literatür taraması sonrası üniversitelerin etkinlik analizinde kullanılan girdi ve çıktı değişkenleri belirlenmiştir. İstanbul’da bulunan 31 vakıf üniversitesinin etkinlik analizleri yapılmıştır. İstanbul’da bulunan vakıf üniversitelerinden önlisans ve lisans bölümlerinden mezuniyet sayısına göre 2 tanesinin etkin, lisansüstü programlardan mezuniyet sayısına göre 1 tanesinin etkin, akademik değerlendirme puanına göre 3 tanesinin etkin ve genel olarak 9 tanesinin etkin olduğu belirlenmiştir. Ayrıca, kuruluş dönemlerine göre İstanbul’da bulunan vakıf üniversitelerinin etkinlik düzeyleri arasında anlamlı bir farklılık olmadığı görülmüştür