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In this paper, we analyze the problem of throughput-efficient distributed coalition formation (CF) of selfish/altruistic nodes in ad hoc radio networks. We formulate the problem as a hedonic CF game with non-transferable utility and propose different preference relations (CF rules) based on individual/group rate improvement of distributed nodes. We develop a hedonic CF algorithm, through which distributed nodes may self-organize into stable throughput-efficient disjoint coalitions. We apply the concept of frequency reuse over different coalitions, such that the members of each coalition will transmit over orthogonal sub-bands with the available spectrum being optimally allocated among them. We study the computational complexity and convergence properties of the proposed hedonic CF algorithm under selfish and altruistic preferences, and present means to guarantee Nash-stability. In addition, we identify the scenarios in which a CF process might lead to instability (CF cycle), and we propose methods to avoid cycles and define different exit procedures if a CF cycle is inevitable. Performance analysis shows that the proposed algorithm with optimal bandwidth allocation provides a substantial gain, in terms of average payoff per link, over existing coalition formation algorithms for a wide SNR range.

This paper presents the design of a multi-antenna, multi-beam, multi-frequency air surveillance system developed at Prince Sultan Defense Studies and Research Center (PSDSARC), Saudi Arabia. The system is configurable to operate as a bi-static or a multi-static passive radar (PR) using fixed (e.g., roof-top) as well as movable (mobile van) installations. The processing chain of PR system is implemented over CPU-GPU server for real-time 360° surveillance of airspace. Results of field experiments exploiting multiple FM channels from a single non-cooperative transmitter in bi-static configuration, show that the radar is able to reliably detect aerial targets up to 300 Km away from its receiver maintaining high track maintenance probability for targets up to bi-static ranges of 150 Km, with 2D track accuracy better than 1 Km.

In this paper we present the multi-target tracking (MTT) framework for passive radar (PR). We address the problem of target filtering in the presence of clutter and measurement uncertainty by employing a two-stage cascaded logic for track initiation. We discuss target association in both plot-to-plot and plot-to-track association regimes, and give practical solutions for efficient data association in multi-target environment. We demonstrate the effectiveness of proposed framework using Kalman filter (KF) based range-doppler (RD) tracking of multiple targets, and verify the system performance against truth data in both bi-static and cartesian domain. Radar measurements have been taken using a mobile PR system, developed at Prince Sultan Defense Studies and Research Center (PSDSARC), Saudi Arabia. Experiments conducted with arbitrary transmitter-target-receiver geometries, exploiting a single non-cooperative FM broadcast channel in bi-static configuration, show that the radar is able to reliably track aerial targets at bi-static ranges of beyond 300 Km, corresponding to ranges up to 150 Km from the receiver.

Additional file 6: Table S4. List of hypermethylated tumor suppressors and hypomethylated oncogenes in meth-miRNAâ mRNA network.

Passive bistatic radars (PBR) are receiver-only radar systems which utilize available communication signals from the environment for surveillance and tracking applications. An approach to improve the range resolution is to resort to a passive multistatic radar systems where range (and/or Doppler) information from multiple bistatic transmit-receive pairs are fused. However, localization process for multiple targets usually faces ghost-targets problem due to the large number of target-to-measurements associations possibilities. In this paper, we explore the performance of few reported multistatic localization methods in conjunction with a closed-form deghosting technique. Specifically, a novel data-association approach was implemented in a multistatic data fusion set-up to assess the effectiveness for localization and deghosting performance for multiple targets.

Efficient spectrum utilization lies at the heart of next generation (xG) wireless communication networks. In this context, a thorough investigation into new and innovative spectrum management techniques as well as additional regulatory procedures are deemed necessary to evaluate the practical feasibility of these xG networks. This paper reviews the three possible modes for multi-operator spectrum sharing based on dynamic spectrum access (DSA) in 5th Generation (5G) networks, and identifies Licensed/Authorized Shared Access (LSA/ASA) mode to be practically most suitable candidate for better spectrum utilization. Existing spectrum sharing techniques exploiting time, frequency and space domain to realize efficient co-existence of multiple operators are discussed, and game theory (GT) framework has been recognized as an appropriate tool to model the interactions among multiple operators accessing the shared spectrum resources. In particular, the hybrid cooperativecompetitive game has been proposed as a promising model to incorporate key parameters that play a significant role in the practical Deployment of DSA-enabled xG networks.

In this paper, we consider the problem of joint coalition formation CF and bandwidth allocation in cognitive radio networks. We assume that the secondary links will be partitioned into disjoint coalitions, by which the available spectrum will be reused. On the other hand, we assume that the members of each coalition will transmit over orthogonal sub-bands with the available spectrum being optimally allocated among them. We formulate the problem as a coordinated CF game, where the optimization is held at a secondary coordinator that has all the required channel information. Given these assumptions, we derive a closed-form expression of the optimal bandwidth allocation for any given network partition, and we propose an efficient algorithm to reach a Nash-stable partition coalition structure, with the objective of improving the network throughput. Furthermore, we provide a probabilistic analysis of the stability of a grand structure and a singleton structure, and we employ this to obtain a lower bound on the stability of a general coalition structure other than grand and singleton. Performance analysis shows that the proposed CF algorithm with optimal bandwidth allocation provides a substantial gain in the network throughput over existing CF techniques as well as the simple cases of singleton and grand coalitions. Copyright © 2015 John Wiley & Sons, Ltd.

Meme kanseri dünyada en yaygın görülen ikinci kanser olup; kadınlarda kansere bağlı ölümlerin önde gelen nedenidir. Çok sayıda ve farklı çeşitte tedavi ajanlarının varlığına rağmen; kanser hücreleri tedaviye direnç geliştirebilir ve var olan tümör büyümeye devam edebilir ya da uzak organlara metastaz yapabilir. Bu noktada, tedavi yanıtını arttırabilmek ve metastazı engelleyebilmek için altta yatan moleküler mekanizmaları belirlemek önemli bir ihtiyaçtır. Genomun kodlanan bölümünün yanısıra, kodlamayan RNA'lar da kanserde çoğalma, apoptoz, invazyon ve ilaç direncinin kontrolünde aktif rol oynamaktadırlar. Bu nedenle, bu tez çalışmasında meme kanserinde ilaç direncini ve metastazını düzenleyen yeni kodlanan/kodlanmayan moleküler anahtarların belirlenmesi amaçlanmıştır. Bu tezin ilk bölümünde, hem hücre sağkalımını hem de epiteliyal mezenkimal geçişi (EMG) inhibe eden, meme kanserinde birçok ilaca duyarlılığı artıran ve bir tümör baskılayıcı gibi hareket eden miR-644a'yı tanımladım. Hem miR-644a ifadesi hem de gen imzası, tümör gelişmesi ve uzak metastassız sağkalım ile ilişkilidir. Mekanistik olarak, miR-644a doğrudan transkripsiyonel co-repressor (baskılayıcı) olan C-terminale bağlanan proteini (CTBP1) hedef alır ve bu genin CRISPR-Cas9 sistemi ile baskılanması miR-644a'nın ifadesinin indüklenmesi ile sağlanan fenotipleri taklit ederek tümör büyümesini, metastazı ve ilaç direncini inhibe eder. Ayrıca, miR-644a/CTBP1 aracılığıyla ifadesi artırılan yabanıl tip (wild type) veya mutant-p53 sırasıyla p21 veya Noxa'yı indükleyerek, hücre döngüsünün G1 evresinde tutulması ve apoptoz arasında bir 'moleküler anahtar' olarak işlev görür. İlginç olarak, miR-644a'nın aşırı ifadesi veya CTBP1'in ifadesindeki azalma aracılığı ile oluşan mutant-p53'teki artışın, Noxa'nın ifadesinin artışı ile hücre döngüsü-apoptoz dengesinin apoptoz lehine kayması için yeterli olduğu görülmüştür. Yalnızca p53 mutant ve yüksek CTBP1 ifadesine sahip hastarın daha kısa sağkalıma sahip oldukları tespit edilmiş olup; bu sonuç p53 mutasyonu taşıyan meme kanseri hastaları için CTBP1'in potansiyel prognostik bir biyobelirteç olabileceğini düşündürmektedir. Özetle, miR-644a/CTBP1/p53 ekseninin modülasyonun hedeflenmesi, hem tedaviye direnci hem de metastazı yenmek için yeni bir strateji oluşturabilir.Bu tezin ikinci bölümünde, in vivo olarak geliştirilen kemoterapi dirençli triple negatif meme kanseri (TNMK) tümörlerde, yeni nesil dizileme ile tüm genom boyutunda gen ifade profili değerlendirilmiştir. Analiz sonuçları, kemoterapi direncinde hipoksinin ve integrinlerin potansiyel bir rolü olduğunu göstermiştir. Seçilen aday genin hipoksi ile indüklendiği ve kemoterapiye dirençli tümörlerde aşırı ifade edildiği; aynı zamanda ITGA5'i aktive ettiği tespit edilmiştir. Diğer taraftan aday genimizi hedefleyen bir miRNA'nın hipoksi aracılığıyla downregülasyonu sağlanarak ITGA5'in daha çok aktifleşmesine yol açtığı gözlenmiştir. Bu olay, dirence aracılık eden FAK/Src yolağının aktivasyonuyla sonuçlanır. Tez çalışmasının bir diğer önemli bulgusu ise aday genin yüksek anlatımının veya miRNA'nın düşük anlatımının, sadece kemoterapi tedavisi uygulanmış TNMK hastalarında kısa nükssüz sağkalımla ilişkili olduğudur. Son olarak, aday genin agresif TNMK in vivo modellerinde inhibisyonunun kemoterapinin etkinliğini artırması; TNMK hastalarında kemoterapi direncinin üstesinden gelmek amacıyla aday genimize karşı inhibitörlerin test edilmesine ilişkin pre-klinik kanıt sağlamıştır. Breast cancer is the second most common cancer and the leading cause of cancer associated deaths in women worldwide. Despite the availability of large number and various types of therapy agents which are effective in limiting tumor burden at initial stages, cancer cells still manage to resist to therapy treatment and exhibit re-growth of existing tumor or metastasize to distant organs. Therefore, there is a dire need to identify underlying molecular mechanisms to enhance therapy response and to block metastasis. In addition to coding genome, non-coding RNAs have also play active role in controlling proliferation, apoptosis, invasion and drug resistance in cancer. Therefore, I aimed to identify novel coding/non-coding molecular switches regulating drug resistance and metastasis in breast cancer.In the first part of this dissertation, I identified miR-644a as a novel tumor suppressor inhibiting both cell survival and epithelial mesenchymal transition (EMT) whereby acting as pleiotropic therapy-sensitizer in breast cancer. Both miR-644a expression and its gene signature are associated with tumor progression and distant metastasis-free survival. Mechanistically, miR-644a directly targets the transcriptional co-repressor C-terminal binding protein 1 (CTBP1) whose knock-outs by the CRISPR-Cas9 system inhibit tumor growth, metastasis, and drug resistance, mimicking the phenotypes induced by miR-644a. Furthermore, miR-644a/CTBP1-mediated upregulation of wild type- or mutant-p53 acts as a 'molecular switch' between G1-arrest and apoptosis by inducing p21 or Noxa, respectively. Interestingly, an increase in mutant-p53 by either overexpression of miR-644a or downregulation of CTBP1 was enough to shift the balance between cell cycle arrest and apoptosis in favor of apoptosis through the upregulation of Noxa. Notably, p53-mutant patients, but not p53-wild type ones, with high CTBP1 level have a shorter survival suggesting that CTBP1 could be a potential prognostic factor for breast cancer patients with p53 mutations. Overall, modulation of the miR-644a/CTBP1/p53 axis may represent a new strategy for overcoming both therapy resistance and metastasis.In the second part of this dissertation, I performed whole transcriptome sequencing with downstream pathway analysis in the chemoresistant triple negative breast cancer (TNBC) tumors we developed in vivo. This suggested a potential role of integrins and hypoxia in chemoresistance. Mechanistically, we showed that our candidate gene is hypoxia-induced and is overexpressed in resistant tumors, and activates integrin subunit alpha 5 (ITGA5). In the meantime, hypoxia-mediated downregulation of a miRNA targeting our candidate gene, leads to further activation of the ITGA5. This culminates in the activation of FAK/Src signaling thereby mediating resistance. Importantly, higher expression of our candidate gene, or lower expression of miRNA was associated with poorer relapse-free survival only in chemotherapy-treated TNBC patients. Finally, inhibition of candidate gene increased the efficacy of chemotherapy in highly aggressive TNBC models in vivo providing pre-clinical evidence for testing inhibitors against our candidate gene to overcome chemoresistance in TNBC patients. 183

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Spectrum scarcity is impeding practical implementations of emerging wireless multimedia applications requiring significantly more frequency spectrum. Cognitive radio (CR) has emerged as a promising solution to the current spectral congestion problem by imparting intelligence to the conventional software defined radio that allows spectrum sharing through opportunistic spectrum access. The principal objective of CR is to optimize the use of under-utilized spectrum through robust and efficient spectrum sensing (SS). This paper introduces cognitive functionality and provides an in-depth comparative survey of various spectrum awareness techniques in terms of their sensing accuracy and computational complexities along with their merits and demerits. Specifically, key challenges in SS are highlighted and possible solutions are discussed. A classification of SS is presented to address the sensing method selection criterion. Both non-cooperative and cooperative sensing schemes are reviewed and open research problems are highlighted to identify future research directions.

Cognitive Radio (CR) has emerged as a smart solution to spectrum bottleneck faced by current wireless services under which licensed spectrum is made available to unlicensed Secondary Users (SUs) through robust and efficient Spectrum Sensing (SS). Energy Detection (ED) is the dominantly used SS approach owing to its low computational complexity and ability to identify spectrum holes without requiring a priori knowledge of primary transmission characteristics. In this chapter, the authors present an in-depth analysis of the ED test statistic. Based on the double threshold ED, they analyze the performance of a Hybrid PSO-OR (Particle Swarm Optimization and OR) algorithm for cooperative SS. The sensing decision of “fuzzy” SUs is optimized using PSO and the final collective decision is made based on OR rule. The idea of using two thresholds is introduced to reduce the communication overhead in reporting local data/decision to the fusion center, which also offers reduced energy consumption. The Hybrid PSO-OR algorithm is shown to exhibit significant performance gain over the Hybrid EGC-OR algorithm.

Cognitive radio based on dynamic spectrum access has emerged as a promising technology to meet the insatiable demand for radio spectrum by the emerging wireless applications. In this chapter, the authors address the problem of throughput-efficient spectrum access in Cognitive Radio Networks (CRNs) using Coalitional Game-theoretic framework. They model the problem of joint Coalition Formation (CF) and Bandwidth (BW) allocation as a CF game in partition form with non-transferable utility and present a variety of algorithms to dynamically share the available spectrum resources among competing Secondary Users (SUs). First, the authors present a centralized solution to reach a sum-rate maximizing Nash-stable network partition. Next, a distributed CF algorithm is developed through which SUs may join/leave a coalition based on their individual preferences. Performance analysis shows that the CF algorithms with optimal BW allocation provides a substantial gain in the network throughput over existing coalition formation techniques as well as the simple cases of singleton and grand coalition.