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Yayın The function of regressions in reading: Backward eye movements allow rereading(Springer, 2013-01) Booth, Robert William; Weger, Ulrich W.Standard text reading involves frequent eye movements that go against normal reading order. The function of these "regressions" is still largely unknown. The most obvious explanation is that regressions allow for the rereading of previously fixated words. Alternatively, physically returning the eyes to a word's location could cue the reader's memory for that word, effectively aiding the comprehension process via location priming (the "deictic pointer hypothesis"). In Experiment 1, regression frequency was reduced when readers knew that information was no longer available for rereading. In Experiment 2, readers listened to auditorily presented text while moving their eyes across visual placeholders on the screen. Here, rereading was impossible, but deictic pointers remained available, yet the readers did not make targeted regressions in this experiment. In Experiment 3, target words in normal sentences were changed after reading. Where the eyes later regressed to these words, participants generally remained unaware of the change, and their answers to comprehension questions indicated that the new meaning of the changed word was what determined their sentence representations. These results suggest that readers use regressions to reread words and not to cue their memory for previously read words.Yayın Power control for fading cooperative multiple access channels(IEEE, 2007-08) Kaya, Onur; Ulukuş, ŞennurFor a fading Gaussian multiple access channel with user cooperation, we obtain the power allocation policies that maximize the average rates achievable by block Markov superposition coding, subject to average power constraints. The optimal policies result in a coding scheme that is simpler than the one for a general multiple access channel with generalized feedback. This simpler coding scheme also leads to the possibility of formulating an otherwise non-concave optimization problem as a concave one. Using the perfect channel state information available at the transmitters to adapt the powers, we demonstrate gains over the achievable rates for existing cooperative systems.Yayın Biometric identification using fingertip electrocardiogram signals(Springer London Ltd, 2018-07) Güven, Gökhan; Gürkan, Hakan; Güz, ÜmitIn this research work, we present a newly fingertip electrocardiogram (ECG) data acquisition device capable of recording the lead-1 ECG signal through the right- and left-hand thumb fingers. The proposed device is high-sensitive, dry-contact, portable, user-friendly, inexpensive, and does not require using conventional components which are cumbersome and irritating such as wet adhesive Ag/AgCl electrodes. One of the other advantages of this device is to make it possible to record and use the lead-1 ECG signal easily in any condition and anywhere incorporating with any platform to use for advanced applications such as biometric recognition and clinical diagnostics. Furthermore, we proposed a biometric identification method based on combining autocorrelation and discrete cosine transform-based features, cepstral features, and QRS beat information. The proposed method was evaluated on three fingertip ECG signal databases recorded by utilizing the proposed device. The experimental results demonstrate that the proposed biometric identification method achieves person recognition rate values of 100% (30 out of 30), 100% (45 out of 45), and 98.33% (59 out of 60) for 30, 45, and 60 subjects, respectively.Yayın Achieving the capacity region boundary of fading CDMA channels via generalized iterative waterfilling(IEEE, 2006-11) Kaya, Onur; Ulukuş, ŞennurWe characterize the optimum power control policies that achieve arbitrary rate tuples on the boundary of the, capacity region of a power controlled, code division multiple access (CDMA) system in a fading channel with perfect channel state information (CSI). We propose a "generalized" waterfilling approach, and provide an iterative algorithm that solves for the optimum power allocation policy, for A given arbitrary rate tuple on the boundary of the capacity region. We then investigate the effects of limited feedback on the capacity region, and demonstrate that a good power control policy may require only a very low rate feedback.Yayın Modeling repair demand in existence of a nonstationary installed base(Elsevier B.V., 2023-09) Hekimoğlu, Mustafa; Karlı, DenizLife cycles of products consist of 3 phases, namely growth, maturity, and decline phases. Modeling repair demand is particularly difficult in the growth and decline stages due to nonstationarity. In this study, we suggest respective stochastic models that capture the dynamics of repair demand in these two phases. We apply our theory to two different operations management problems. First, using the moments of spare parts demand, we suggest an algorithm that selects a parametric distribution from the hypergeometric family (Ord, 1967) for each period in time. We utilize the algorithm in a single echelon inventory control problem. Second, we focus on investment decisions of Original Equipment Manufacturers (OEMs) to extend economic lifetimes of products with technology upgrades. Our results indicate that the second moment is sufficient for growing customer bases, whereas using the third moment doubles the approximation quality of theoretical distributions for a declining customer base. From a cost minimization perspective, using higher moments of demand leads to savings up to 13.6% compared to the single-moment approach. Also, we characterize the optimal investment policy for lifetime extension decisions from risk-neutral and risk-averse perspectives. We find that there exists a critical level of investment cost and installed base size for profitability of lifetime extension for OEMs. From a managerial point of view, we find that a risk-neutral decision maker finds the lifetime extension problem profitable. In contrast, even a slight risk aversion can make the lifetime extension decision economically undesirable.Yayın The internet and political participation : exploring the explanatory links(Sage Publications Ltd, 2005-12) Karakaya Polat, RabiaThere is a growing literature exploring the role of the Internet in influencing levels and styles of political participation. However, it is not yet clear why the Internet is perceived as a medium that can, at least potentially, increase participation. Moreover, putting the emphasis on the Internet as a technology rather than on its information and communication capabilities signals a tendency for technological determinism. In order to avoid this, the article explores the relation between the Internet and political participation by examining three different facets of the Internet: the Internet as an information source, as a communication medium and as a virtual public sphere. The main argument of the article is that it is these facets of the Internet that may affect levels and styles of political participation and hence are of interest for political scientists. The article also emphasizes the relevance of established theories of participation within political science in evaluating the potential role of the Internet for affecting levels and styles of political participation.Yayın Uncontrolled avoidance of threat: Vigilance-avoidance, executive control, inhibition and shifting(Routledge Journals, 2014) Booth, Robert WilliamIt has been argued that anxious individuals orient their attention initially towards and then away from threat; this pattern is known as vigilance-avoidance. While the mechanisms underlying the initial vigilance have been subject to intense speculation and study, mechanisms underlying any subsequent avoidance have been neglected, although it has often been assumed that avoidance is a controlled coping strategy. Using a correlational design, the present study assessed avoidance in a dot-probe task, along with anxiety and two aspects of goal-driven executive control: Shifting and inhibition. Avoidance of threat correlated with state of anxiety; separate from this, avoidance also correlated negatively with shifting performance and was unrelated to inhibition performance. In other words, avoidance appeared to represent a shifting failure in this study. These results suggest that avoidance may occur ballistically in any individual as a consequence of threat exposure and does not necessarily represent a controlled coping response.
