57 research outputs found

    GAME THEORETIC FLOW AND ROUTING CONTROL FOR COMMUNICATION NETWORKS

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    As the need to support high speed data exchange in modern communication networks grows rapidly, effective and fair sharing of the network resources becomes very important. Today's communication networks typically involve a large number of users that share the same network resources but may have different, and often competing, objectives. Advanced network protocols that are implemented to optimize the performance of such networks typically assume that the users are passive and are willing to accept compromising their own performance for the sake of optimizing the performance of the overall network. However, considering the trend towards more decentralization in the future, it is natural to assume that the users in a large network may take a more active approach and become more interested in optimizing their own individual performances without giving much consideration to the overall performance of the network. A similar situation occurs when the users are members of teams that are sharing the network resources. A user may find itself cooperating with other members of its team which itself is competing with the other teams in the network. Game theory appears to provide the necessary framework and mathematical tools for formulating and analyzing the strategic interactions among users, or teams of users, of such networks. In this thesis, we investigate networks in which users, or teams of users, either compete or cooperate for the same network resources. We considered two important network topologies and used many examples to illustrate the various solution concepts that we have investigated.. First we consider two-nodeiiiparallel link networks with non-cooperative users trying to optimally distribute their flows among the links. For these networks, we established a condition which guarantees the existence and uniqueness of a Nash equilibrium for the link flows. We derived an analytical expression for the Nash equilibrium and investigated its properties in terms of the network parameters and the users preferences. We showed that in a competitive environment users can achieve larger flow rates by properly emphasizing the corresponding term in their utility functions, but that this can only be done at the expense of an increase in the expected delay. Next, we considered a general network structure with multiple links, multiple nodes, and multiple competing users. We proved the existence of a unique Nash equilibrium. We also investigated many of its intuitive properties. We also extended the model to a network where multiple teams of users compete with each other while cooperating within the teams to optimize a team level performance. For this model, we studied the Noninferior Nash solution and compared its results with the standard Nash equilibrium solution

    Relationship between maternal blood ceruloplasmin level, catalase and myeloperoxidase activity and neural tube defects

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    Objectives: The exact pathogenesis of neural tube defects (NTDs) is poorly understood. We aimed at evaluating maternal anti-oxidant capacity (ceruloplasmin level, myeloperoxidase and catalase activity) in pregnancies complicated by NTDs. Material and methods: Fifty-four mothers with NTD-affected pregnancies and 61 healthy mothers, matched for gestational age, were recruited. Maternal venous blood samples were obtained after detailed fetal ultrasound examination to measure myeloperoxidase, catalase activity and ceruloplasmin levels. The clinical characteristics of all participants were collected. Results: Maternal blood catalase activity was significantly lower in the study group (117.1 ± 64.8 kU/L) as compared to controls (152.2 ± 110.6 kU/L) (p = 0.044). Maternal blood ceruloplasmin levels were also significantly lower in the study group (180.5 ± 37.7 U/L) as compared to controls (197.9 ± 35.9 U/L) (p = 0.012). Myeloperoxidase activity was similar in both groups (112.6 ± 22.2 U/L vs. 113.6 ± 38.1 U/L) (p = 0.869). Conclusions: In the present study, maternal blood ceruloplasmin level and catalase activity were found to be lower in NTD-affected pregnancies as compared to healthy controls. Thus, it seems safe to conclude that impaired antioxidant capacity may play a role in the development of NTDs during pregnancy, in addition to the genetic, environmental and metabolic factors

    Phase 2 study of vismodegib, a hedgehog inhibitor, combined with gemcitabine and nab-paclitaxel in patients with untreated metastatic pancreatic adenocarcinoma

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    Background: The Hedgehog (Hh) signalling pathway is overexpressed in pancreatic ductal adenocarcinoma (PDA). Preclinical studies have shown that Hh inhibitors reduce pancreatic cancer stem cells (pCSC), stroma and Hh signalling. Methods: Patients with previously untreated metastatic PDA were treated with gemcitabine and nab-paclitaxel. Vismodegib was added starting on the second cycle. The primary endpoint was progression-free survival (PFS) as compared with historical controls. Tumour biopsies to assess pCSC, stroma and Hh signalling were obtained before treatment and after cycle 1 (gemcitabine and nab-paclitaxel) or after cycle 2 (gemcitabine and nab-paclitaxel plus vismodegib). Results: Seventy-one patients were enrolled. Median PFS and overall survival (OS) were 5.42 months (95% confidence interval [CI]: 4.37–6.97) and 9.79 months (95% CI: 7.85–10.97), respectively. Of the 67 patients evaluable for response, 27 (40%) had a response: 26 (38.8%) partial responses and 1 complete response. In the tumour samples, there were no significant changes in ALDH + pCSC following treatment. Conclusions: Adding vismodegib to chemotherapy did not improve efficacy as compared with historical rates observed with chemotherapy alone in patients with newly diagnosed metastatic pancreatic cancer. This study does not support the further evaluation of Hh inhibitors in this patient population. Trial registration: ClinicalTrials.gov Identifier: NCT01088815

    Technical Efficiency And Total Factor Productivity Measurement Of Social Security Institution Hospitals Transferred To Ministry Of Health Of Turkey

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    Technical efficiency and total factor productivity measurement of Social Security Institution hospitals transferred to Ministry of Health of Turkey The purpose of this study, we analyse the changes in the technical efficiencies, production performances and total factor productivity of the Social Security Institution (SSI) general hospitals transferred to the Ministry of Health (Moll) within the context of the Health Transformation Program are measured comparatively over the period 2004-8. The efficiencies of a sample of 46 general acute SSI hospitals have been comparatively examined before and after the transfer to the Moll. DEA was employed with included inputs being the number of physicians, nurses, other employees and staffed beds, whereas outputs were the inpatients, outpatients and surgical operations performed. The analysis indicates a considerably improvement in the productivity over the period considered. The results of the measurement show that there is a progress of 15% in the total factor productivities of SSI hospitals over the 2004-8 periods that is technological change plays a determining role in this progress.Wo

    Sınıftan Kaçan Çocuk

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    8-9 Kasım 2012’de, Hacettepe Üniversitesi İngilizce İktisat Bölümü tarafından düzenlenen “Marx, Marksizmler ve Özgürlük” konferansı uzun zamandır üzerinde çalıştığım konular ile ilgili görüşlerimi sunma fırsatı verdi. Praksis dergisini ilk yayınladığım 1996 yılında aşağıda sunduğum düşüncelerimin temellerini atmıştım aslında. Ancak hala teoride ki sorunu bir bütün olarak, Marx ve Engels’te değil Marksizmin kavranılışında olduğunda ısrarcıydım. Çalışmalarım, Marx’ın tarih, diyalektik yöntem, sınıf savaşımı, kapitalizm eleştirisi ve bilim anlayışı gibi pek çok temel konuda tamamen farklı teorik perspektif ve anlayış geliştirmemle sonuçlandı. Bu görüşlerimi kamuoyu ile ilk paylaştığım zemin yukarıda adı geçen bilimsel konferans oldu. Kendi teorik geçmişimle de bir hesaplaşma olan bu metin kuşkusuz okuru tatmin etmekten uzaktır. Çünkü yeni bir bilim teorisi için bir başlangıç metnidir; 19. yüz yıl sosyal teorileri üzerinde yükselen geleneksel ideolojik ön yargılardan kurtulmuş aklın, çağdaş bilimsel verilere yaslanarak yeni maceralara cesaretle atılmayı özendirecek olan bir başlangıç metni

    Quantum Filozofi

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    Bu çalışma kitap olmayan bir kitaptır. Okur klasik kitaplarda alıştığı tamamlanmış metinler, çözümlenmiş bilimsel ve felsefi problemler beklemesin bu çalışmada. Sunduğum şey üzerinde çalıştığım konular ve o konularla ilgili geliştirdiğim düşünceler, aforizmalar yer yer dağınık önermelerdir. Bu iki nedenden dolayı böyledir: Birincisi bilgi kuramsal açıdan tamamlanmış önermeler dizgesinin yanlış olmasıdır. Quantum çağında her gün yeni bir keşif yaptığımız nesneler ile ilgili büyük anlatılar ve tamamlanmış, sistematik görüşler geliştirilemez. Geleneksel tüm kitaplar ilgilendikleri nesneyi tüm bağıntılarıyla çözdükleri iddiasındadır. Örneğin tüm çağdaş fizik kitapları yaklaşık yüz yıldır atomun ağırlığını çözdüklerini düşünerek yayınlanıyordu. Ancak 2017 Ocağında quarkların dışarıdan enerji alışverişi yaptıkları ve oluşturdukları atom ağırlığının sürekli değişti keşfedildi. Bu tüm yazılmış fizik kitaplarının çöpe atılması anlamına gelir. Bu nedenlerden ötürü tamamlanmış çalışmalar değil, sürekli gelişen Wikipedia tarzında, yazılan metinlerin sürekli güncellendiği çalışmalar, bilimsel anlatıma daha uygundur. Okur, bu metnin sürekli işlenen biçimini bloğumda takip edebilecek. İkincisi kişisel olarak çalışmalarımdan asla tatmin olamadım ve vardığım teorik sonuçları dışarı açarak çalışmalarıma dışsal bir motivasyon ve eleştirel bir geri dönüşüm almak istedim. O nedenle okur bu çalışmamı kendisiyle tartışmaya açtığım el yazmalarım olarak değerlendirsin. Tüm bunlarla birlikte okuru son derece geniş bir entelektüel alanda yaratıcı bir çalışma ve tamamiyle sadece yazara ait yeni önermeler bekliyor. Bu çalışma esas olarak aydınlanmadan başlayan ve günümüze kadar gelen, quantum fizikçilerinin de yaslandıkları, tüm sosyal kuramların sonunu ilan etmektedir. Salt bu iddia bile çalışmamı dikkate değer kılar

    Minimization over randomly selected lines

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    This paper presents a population-based evolutionary optimization method for minimizing a given cost function. The mutation operator of this method selects randomly oriented lines in the cost function domain, constructs quadratic functions interpolating the cost function at three different points over each line, and uses extrema of the quadratics as mutated points. The crossover operator modifies each mutated point based on components of two points in population, instead of one point as is usually performed in other evolutionary algorithms. The stopping criterion of this method depends on the number of almost degenerate quadratics. We demonstrate that the proposed method with these mutation and crossover operations achieves faster and more robust convergence than the well-known Differential Evolution and Particle Swarm algorithms

    Badanie poziomu wiedzy menedżerów w zakresie wykorzystania narzędzi zarządzania strategicznego w instytucjach publicznych w Turcji na przykładzie prowincji Ankara

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    W praktykach zarządzania strategicznego wykorzystanie narzędzi strategicznych ma ogromne znaczenie dla menedżerów w określaniu właściwych strategii, dla stosowalności i trwałości zarządzania strategicznego. Niniejsze badanie zostało przeprowadzone w celu określenia perspektyw zarządzania strategicznego menedżerów 3 Instytucji Publicznych w Turcji/Prowincji Ankara oraz określenia ich wiedzy na temat narzędzi strategicznych, ich wykorzystania i poziomu satysfakcji. W tym celu w raporcie „Management Tools and Trends 2009” przygotowanym przez Rigby i Bilodeau (2009), który zawiera spojrzenie menedżerów na zarządzanie strategiczne oraz informacje o narzędziach strategii, a także sugestie dotyczące wykorzystania i satysfakcji z korzystania z narzędzi ; Opiera się na wersji, która mierzy wykorzystanie i satysfakcję 25 narzędzi do zarządzania oraz ocenia priorytety w doborze narzędzi do zarządzania. W ankiecie wybrano 23 narzędzia strategiczne, które można znaleźć w literaturze i często wykorzystywane przez organizacje. Odpowiedzi udzielone przez 188 uczestników kwestionariusza zostały ocenione za pomocą analizy SPSS, testu T i jednokierunkowej analizy wariancji (ANOVA) oraz testu wielokrotnych porównań Tukeya-B (post hoc).In strategic management practices, the use of strategic tools is of great importance for managers to determine the right strategies, for the applicability and sustainability of strategic management. This study was carried out in order to determine the strategic management perspectives of the managers of 3 Public Institutions in Turkey / Ankara Province, and to determine their knowledge about strategic tools, their use and their satisfaction levels. For this purpose, in the report titled "Management Tools and Trends 2009" prepared by Rigby and Bilodeau (2009), which includes the managers' perspectives on strategic management and information about strategy tools, and suggestions for the use and satisfaction of using the tools; It is based on the version that measures the usage and satisfaction levels of 25 management tools and evaluates the priorities in the selection of management tools. In the survey, 23 strategy tools, which are found in the literature and frequently used by organizations, were selected. The answers given by 188 participants to the questionnaire have been evaluated by using SPSS Analysis, T-Test and One-Way Analysis of Variance (ANOVA) test, and Tukey-B (Post Hoc) multiple comparison test
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