Consensus as a Nash Equilibrium of a Dynamic Game

Consensus formation in a social network is modeled by a dynamic game of a prescribed duration played by members of the network. Each member independently minimizes a cost function that represents his/her motive. An integral cost function penalizes a member's differences of opinion from the others as well as from his/her own initial opinion, weighted by influence and stubbornness parameters. Each member uses its rate of change of opinion as a control input. This defines a dynamic non-cooperative game that turns out to have a unique Nash equilibrium. Analytic explicit expressions are derived for the opinion trajectory of each member for two representative cases obtained by suitable assumptions on the graph topology of the network. These trajectories are then examined under different assumptions on the relative sizes of the influence and stubbornness parameters that appear in the cost functions.Comment: 7 pages, 9 figure, Pre-print from the Proceedings of the 12th International Conference on Signal Image Technology and Internet-based Systems (SITIS), 201

A Game Approach to Multi-dimensional Opinion Dynamics in Social Networks with Stubborn Strategist Agents

In a social network, individuals express their opinions on several interdependent topics, and therefore the evolution of their opinions on these topics is also mutually dependent. In this work, we propose a differential game model for the multi-dimensional opinion formation of a social network whose population of agents interacts according to a communication graph. Each individual's opinion evolves according to an aggregation of disagreements between the agent's opinions and its graph neighbors on multiple interdependent topics exposed to an unknown extraneous disturbance. For a social network with strategist agents the opinions evolve over time with respect to the minimization of a quadratic cost function that solely represents each individual's motives against the disturbance. We find the unique Nash/worst-case equilibrium solution for the proposed differential game model of coupled multi-dimensional opinions under an open-loop information structure. Moreover, we propose a distributed implementation of the Nash/worst-case equilibrium solution. We examine the non-distributed and proposed distributed open-loop Nash/worst-case strategies on a small social network with strategist agents in a two-dimensional opinion space. Then we compare the opinions evolved based on the Nash/worst-case strategy with the opinions corresponding to social optimality actions for non-strategist agents.Comment: Under review in a journa

Polynomial fitting and total variation based techniques on 1-D and 2-D signal denoising

Ankara : The Department of Electrical and Electronics Engineering and the Institute of Engineering and Sciences of Bilkent University, 2010.Thesis (Master's) -- Bilkent University, 2010.Includes bibliographical references leaves 167-176.New techniques are developed for signal denoising and texture recovery. Geometrical theory of total variation (TV) is explored, and an algorithm that uses quadratic programming is introduced for total variation reduction. To minimize the staircase effect associated with commonly used total variation based techniques, robust algorithms are proposed for accurate localization of transition boundaries. For this boundary detection problem, three techniques are proposed. In the first method, the 1−D total variation is applied in first derivative domain. This technique is based on the fact that total variation forms piecewise constant parts and the constant parts in the derivative domain corresponds to lines in time domain. The boundaries of these constant parts are used as the transition boundaries for the line fitting. In the second technique proposed for boundary detection, a wavelet based technique is proposed. Since the mother wavelet can be used to detect local abrupt changes, the Haar wavelet function is used for the purpose of boundary detection. Convolution of a signal or its derivative family with this Haar mother wavelet gives responses at the edge locations, attaining local maxima. A basic local maximization technique is used to find the boundary locations. The last technique proposed for boundary detection is the well known Particle Swarm Optimization (PSO). The locations of the boundaries are randomly perturbed yielding an error for each set of boundaries. Pursuing the personal and global best positions, the boundary locations converge to a set of boundaries. In all of the techniques, polynomial fitting is applied to the part of the signal between the edges. A more complicated scenario for 1−D signal denoising is texture recovery. In the technique proposed in this thesis, the periodicity of the texture is exploited. Periodic and non-periodic parts are distinguished by examining total variation of the autocorrelation of the signal. In the periodic parts, the period size was found by PSO evolution. All the periods were averaged to remove the noise, and the final signal was synthesized. For the purpose of image denoising, optimum one dimensional total variation minimization is carried to two dimensions by Radon transform and slicing method. In the proposed techniques, the stopping criterion for the procedures is chosen as the error norm. The processes are stopped when the residual norm is comparable to noise standard deviation. 1−D and 2−D noise statistics estimation methods based on Maximum Likelihood Estimation (MLE) are presented. The proposed denoising techniques are compared with principal curve projection technique, total variation by Rudin et al, total variation by Willsky et al, and curvelets. The simulations show that our techniques outperform these widely used techniques in the literature.Yıldız, AykutM.S

Effect of adenomyosis on prognosis of patients with endometrial cancer

OBJECTIVE: Our goal was to contrast the prognoses of patients with endometrial cancer who had adenomyosis against those that did not. METHODS: All patients who had received surgical staging for hysterectomy-based endometrial cancer had their medical data retrospectively examined. The analysis covered 397 patients, who were split into two groups depending on the presence of adenomyosis. Comparisons were made between patients covering type of surgery, histopathology, endometrial cancer stage, lymphovascular space invasion, presence of biochemical or histochemical markers, adjuvant therapy, presence of adenomyosis in the myometrial wall, and outcomes in terms of overall survival and disease-free survival. RESULTS: There is no statistically significant difference in the 5-year disease-free survival or overall survival rates between endometrial cancer patients with and without adenomyosis. This is based on comparisons of tumor stage, tumor diameter, histological type and grade of tumor, myometrial invasion, lymphovascular space invasion, and biochemical markers that affect the course of the disease. The median follow-up times were 61 months for the adenomyosis-positive group and 56 months for the group without adenomyosis. CONCLUSION: Coexisting adenomyosis in endometrial cancer has no bearing on survival rates and is not a prognostic factor

Children in 2077: Designing Children’s Technologies in the Age of Transhumanism

What for and how will we design children’s technologies in the transhumanism age, and what stance will we take as designers? This paper aims to answer this question with 13 fictional abstracts from sixteen authors of different countries, institutions and disciplines. Transhumanist thinking envisions enhancing human body and mind by blending human biology with technological augmentations. Fundamentally, it seeks to improve the human species, yet the impacts of such movement are unknown and the implications on children’s lives and technologies were not explored deeply. In an age, where technologies can clearly be defined as transhumanist, such as under-skin chips or brain-machine interfaces, our aim is to reveal probable pitfalls and benefits of those technologies on children’s’ lives by using the power of design fiction

Sürülerin besin kaynağı arama hareketinin diferansiyel oyunların nash dengesi olarak modellenmesi

Cataloged from PDF version of article.Thesis (Ph.D.): Bilkent University, Department of Electrical and Electronic Engineering, İhsan Doğramacı Bilkent University, 2016.Includes bibliographical references (leaves 69-76).The question of whether foraging swarms can form as a result of a non-cooperative game played by individuals is shown here to have an affirmative answer. A dynamic (or, differential) game played by N agents in one-dimensional motion is introduced and models, for instance, a foraging ant colony. Each agent controls its velocity to minimize its total work done in a finite time interval. The agents in the game start from a set of initial positions and migrate towards a target foraging location. Such swarm games are shown to have unique Nash equilibra under two different foraging location specifications and both equilibria display many features of a foraging swarm behavior observed in biological swarms. Explicit expressions are derived for pairwise distances between individuals of the swarm, swarm size, and swarm center location during foraging. Foraging swarms in one-dimensional motion with four different information structures are studied. These are complete and partial information structures, hierarchical leadership and one leader structures. In the complete information structure, every agent observes its distance to every other agent and makes use of this information in its effort optimization. In partial information structure, the agents know the position of only its neighboring agents. In the hierarchical leadership structure, the agents look only forward and measures its distance to the agents ahead. In single leader structure, the agents know the position of only leader. In all cases, a Nash equilibrium exists under some realistic assumptions on the sizes of the weighing parameters in the cost functions. The consequences of having a “passive” leader in a swarm are also investigated. We model foraging swarms with leader and followers again as non-cooperative, multi-agent differential games. We consider two types of leadership structures, namely, hierarchical leadership and a single leader structure. In both games, the type of leadership is assumed to be passive since a leader is singled out only due to its rank in the initial queue. We identify the realistic assumptions under which a unique Nash equilibrium exists in each game and derive the properties of the Nash equilibriums in detail. It is shown that having a passive leader economizes in the total information exchange at the expense of aggregation stability in a swarm.by Aykut Yıldız.Ph.D

The relationship of mobbing and organizational commitment: An application of hospital staff

Rekabetin yoğun yaşandığı günümüz iş dünyasında işletmeler için çalışanların verimliliği, kuruma olan bağlılıkları, işe yönelik olumlu tutumları, büyük önem taşımaktadır. Bireyin psikolojik durumunu ve verimliliğini olumsuz yönde etkileyen psikolojik şiddet(mobbing) kapsamına giren davranışlar bugün işletmelerin üzerinde durdukları önemli bir kavramdır. Örgütün amaç ve değerlerini kabul etmek, örgüt adına çalışmak ve örgütün bir üyesi olmayı devam ettirme isteği davranışları şeklinde ortaya çıkan örgütsel bağlılık ise çalışan sadakatine önem veren tüm işletmeler için önemli bir husustur. Yapılan çalışmalar mobbinge yönelik algının çalışanların örgütsel bağlılığına etki ettiğini göstermektedir. Bu araştırmada, Karaman İli Kamu Hastaneleri Genel Sekreterliği’nde araştırmaya katılmayı kabul eden çalışanlar arasından kolayda örneklem yöntemiyle katılımcılar seçerek, mobbing(psikolojik şiddet) algısının örgütsel bağlılık düzeyine etkisi incelenmiştir. Araştırmaya 67 çalışan katılmıştır. Verilerin toplanması için oluşturulan anket formunda katılımcılara ilişkin demografik bilgiler, “Mobbing ölçeği” ve “Örgütsel bağlılık ölçeği” yer almıştır. Psikolojik şiddet(Mobbing) ölçeği 33 maddeli 5’li Likert tipinde bir ölçek iken, örgütsel bağlılık ölçeği 18 maddeli 5’li Likert tipinde 3 boyutlu bir ölçektir. Veriler Mann Whitney U, Bağımsız Örneklem t Testi, Kruskal Wallis ve Tek Yönlü Varyans Analizi ile analiz edilmiştir. Varyans Analizi sonucunda farklılık tespit edilen grupların belirlenmesinde Tukey HSD çoklu karşılaştırma testi uygulanmıştır. Ölçeklerin kendi aralarındaki ilişkileri Pearson ve Spearman’sRho Korelasyon Katsayısı ile incelenmiştir. İstatistiksel anlamlılık için p<0.05 değeri kullanılmıştır. Yapılan analiz sonucunda çalışanların mobbinge yönelik davranışlara maruz kalmadığı, mobbing algısı ile örgütsel bağlılık düzeyi arasında negatif yönlü anlamlı bir ilişki olduğu tespit edilmiştir. Ayrıca katılımcıların örgütsel bağlılık düzeylerinin orta seviyede olduğu görülmüştürEmployee productivity, commitment to the organization and positive attitudes towards work are of great importance for businesses in today’s competitive business world. Today behaviors within the scope of psychological violence (mobbing) affecting the individual’s psychological status and the efficiency are very important concepts on which businesses focus. Organizational commitment in the form of accepting the values goals of the organization, working on behalf of the organization and the demand of continuing being a member of the organization is a major concern for all the businesses giving importance to employee loyalty. Studies indicate that perception of mobbing affects the organizational commitment. In this study, the effects of mobbing (psychological violence) perception on the organizational commitment level has been examined by selecting participants with the random sample method among the employee who agree to participate in research from Karaman Public Hospital General Secretary. 67 employees participated in the research. There were demographic information about participants, "Mobbing Scale" and "Organizational Commitment Scale” in the questionnaire form created for collecting data. While psychological violence (mobbing)is a five-point Likert type scale consisting of 33 item, organizational commitment scale is a 3D five-point Likert type scale consisting of 18 items. Data has been analyzed with Mann Whitney U, Independent Sample t Test, Kruskal Wallis and one-way variance analysis. Tukey HSD multiple comparison test has been applied in determining the groups found difference according to the result of variance analysis. Relations of the scales with each other have been examined with Pearson and Spearman’s Rho Correlation Coefficient. P<0.05 value has been used for statistical relevance. In result of the analysis it has been determined that employees aren’t exposed to mobbing and there is an important negative relationship between mobbing perception and organizational commitment. It has also found that organizational commitment participants are at the moderate leve

Effectiveness of Patching in Correcting Refractive Errors in Cases with Anisometropic Amblyopia

Pur po se: To evaluate the effects of patching on refractive errors in patients with anisometropic amblyopia. Ma te ri al and Met hod: We evaluated retrospectively 81 cases (5-8 years old) which were applied patching treatment for unilateral anisometropic amblyopia between June 2005 and August 2009. Pre- and post-treatment visual acuities and stereopsis were evaluated and the cases were divided into 4 groups as hyperopia, hyperopic astigmatism, myopia, and myopic astigmatism. Re sults: Mean age was 6.8±0.1 (minimum-maximum: 5-8) years. Visual acuity was 0.57±0.07 log MAR in hyperopias (p=0.001), 0.74±0.07 logMAR (p=0.001) in hypermetropic astigmatisms, 0.1±0.02 log MAR (p=0.02) in myopias, and 0.62±0.08 logMAR (p=0.04) in myopic astigmatisms after treatment. Post-treatment stereoacuity was improved significantly, except for myopic astigmatism (p=0.1). Dis cus si on: Patching treatment in anisometropic amblyopia is safe and effective method in all refraction errors especially hyperopia. (Turk J Ophthalmol 2011; 41: 385-8

Effects of age and Refractive Errors on Stereopsis

Pur po se: To investigate the effects of age and refractive errors on stereopsis. Ma te ri al and Met hod: The present study included 1488 cases which were randomly selected, had full vision and no eye pathology except refractive errors. The patients were divided into six groups according to their age: 10–19 (Group 1, n=258), 20–29 (Group 2, n=264), 30–39 (Group 3, n=246), 40–49 (Group 4, n=246), 50–59 (Group 5, n=246), and 60 years and over (Group 6, n=228). Additionally, each group was divided according to refractive errors: myopia (a), myopic astigmatism (b), hyperopia (c), hyperopic astigmatism (d), emetropia (e). Titmus test was applied to all cases from 16 inches (405 mm) distance with polarized glasses after correcting the refractive errors. Stereoacuity was evaluated using the Titmus circle test. Re sults: Mean stereoacuity was 41.1±3.2 arc\s in group 1, 45.3±24.6 arc\s in group 2, 42.6±5.0 arc\s in group 3, 44.1±10.7 arc\s in group 4, 45.8±24.8 arc\s in group 5, and 41.3±3.4 arc\s in group 6. Mean stereoacuity was found to be 45.4±24.2 arc\s in myopia, 41.3±4.2 arc\s in myopic astigmatism, 45.3±21.4 arc\s in hyperopia, 41.4±3.6 arc\s in hyperopic astigmatism, and 41.9±4.4 arc\s in emetropia in the refractive error groups. No statistically significant differences were detected in evaluation between age groups, refraction groups according to age and refraction groups. Dis cus si on: No significant effects of age and refractive errors on stereoacuity were found in our study. (Turk J Ophthalmol 2011; 41: 372-5

Relationships Among Relational Aggression and Self Esteem, Social Connectedness and Social Anxiety Levels of University Students

Bu araştırmada üniversite öğrencilerinin ilişkisel saldırganlık davranışlarının benlik saygısı, sosyal bağlılık ve sosyal kaygı değişkenleri açısından araştırılması amaçlanmıştır. Bu değişkenler arasındaki ilişkileri içeren hipotetik model mevcut kuramsal açıklamalar (Sosyal Bilgi İşleme Yaklaşımı) ve araştırmalar çerçevesinde önerilmiştir. Hipotetik modelde benlik saygısı ve sosyal bağlılık değişkenlerinin sosyal kaygı değişkenini yordadığı, sosyal kaygı değişkeninin ise ilişkisel saldırganlık davranışlarını yordadığına ilişkin hipotezler ileri sürülmüştür. Böylece, benlik saygısı ve sosyal bağlılık değişkenlerinin sosyal kaygı yoluyla ilişkisel saldırganlığı yordayıcılığının incelenmesi amaçlanmıştır. Bu temel amaç çerçevesinde çalışma 2009-2010 öğretim yılı bahar döneminde Anadolu Üniversitesi'nin dört yıllık fakültelerine devam eden 248'i kadın (%62), 151 (%38)'i erkek olmak üzere toplam 399 öğrenciden elde edilen veriler ile gerçekleştirilmiştir. Çalışma grubunda yer alan katılımcıların ilişkisel saldırganlık düzeylerine ilişkin veriler Arkadaşlık İlişkilerinde İlişkisel Saldırganlık Ölçeği ile, benlik saygılarına ilişkin veriler Rosenberg Benlik Saygısı Ölçeği ile, sosyal bağlılıklarına ilişkin veriler Sosyal Bağlılık Ölçeği ile, sosyal kaygılarına ilişkin veriler ise Sosyal Kaygı Ölçeği ile elde edilmiştir. Ayrıca, katılımcıların yaş, cinsiyet, fakültelerine ilişkin bilgiler Kişisel Bilgi Formu ile toplanmıştır. Araştırmanın verilerinin analizinde betimsel istatistiklerden ve yapısal eşitlik modelinden yararlanılmıştır. Bu sonuçlar benlik saygısı ve sosyal bağlılık değişkenlerinin sosyal kaygı değişkeni üzerinde doğrudan etkiye ve dolayısıyla ilişkisel saldırganlık değişkeni üzerinde dolaylı etkiye sahip olduğunu ortaya koymuştur. Ayrıca, sosyal kaygının ilişkisel saldırganlık üzerinde doğrudan etkiye sahip olduğu da belirlenmiştir. Böylece, üniversite öğrencilerinin benlik saygısı ve sosyal bağlılıklarının sosyal kaygılarını, sosyal kaygılarının da ilişkisel saldırganlıklarını yordadığı belirlenmiştirIt was aimed to investigate university students’ relational aggression in terms of self-esteem, social connectedness and social anxiety variables in this study. Hypothesized model including the relationships among these variables was proposed based on the theoretical explanations (Social Information Processing Approach) and researches in literature. It was hypothesized that both self-esteem and social connectedness would predict social anxiety and then social anxiety would predict relational aggression. Thus, it was intended to investigate the predictive power of self-esteem and social connectedness on relational aggression through social anxiety. In this framework, the research was conducted with 399 students, 248 (62%) of whom were females and 151 of whom were males, attending to the faculties of Anadolu University in the spring semester of 2009-2010 academic year. Data related with relational aggression was gathered by means of the Relational Aggression Scale. The Rosenberg Self Esteem Scale, the Social Connectedness Scale and the Social Anxiety Scale were used to determine the self-esteem, social connectedness and social anxiety levels of participants respectively. In addition, Personal Data Form was used to gather information about participants’ ages, gender and the faculties they attend. In data analysis, descriptive statistics and structural equation modeling were utilized. According to results, it was found that both self-esteem and social connectedness have direct effects on social anxiety and therefore indirect effects on relational aggression. Furthermore, social anxiety was found to have direct effect on relational aggression. As a result, it was found that university students’ selfesteem and social connectedness predicted social anxiety, and social anxiety predicted relational aggression