05. Fakülteler

Permanent URI for this communityhttps://hdl.handle.net/20.500.11779/7

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Citation - WoS: 1
Citation - Scopus: 1
A Decomposition Algorithm for Single and Multiobjective Integrated Market Selection and Production Planning
(Informs, 2023) van den Heuvel, Wilco; Ağralı, Semra; Taşkın, Z. Caner
We study an integrated market selection and production planning problem. There is a set of markets with deterministic demand, and each market has a certain revenue that is obtained if the market's demand is satisfied throughout a planning horizon. The demand is satisfied with a production scheme that has a lot-sizing structure. The problem is to decide on which markets' demand to satisfy and plan the production simultaneously. We consider both single and multiobjective settings. The single objective problem maximizes the profit, whereas the multiobjective problem includes the maximization of the revenue and the minimization of the production cost objectives. We develop a decomposition-based exact solution algorithm for the single objective setting and show how it can be used in a proposed three-phase algorithm for the multiobjective setting. The master problem chooses a subset of markets, and the subproblem calculates an optimal production plan to satisfy the selected markets' demand. We investigate the subproblem from a cooperative game theory perspective to devise cuts and strengthen them based on lifting. We also propose a set of valid inequalities and preprocessing rules to improve the proposed algorithm. We test the efficacy of our solution method over a suite of problem instances and show that our algorithm substantially decreases solution times for all problem instances.
Citation - WoS: 3
Citation - Scopus: 4
A Novel Graph Transformation Strategy for Optimizing Sptrsv on Cpus
(Wiley, 2023) Yılmaz, Buse
Sparse triangular solve (SpTRSV) is an extensively studied computational kernel. An important obstacle in parallel SpTRSV implementations is that in some parts of a sparse matrix the computation is serial. By transforming the dependency graph, it is possible to increase the parallelism of the parts that lack it. In this work, we present a novel graph transformation strategy to increase the parallelism degree of a sparse matrix and compare it to our previous strategy. It is seen that our transformation strategy can provide a speedup as high as 1.42x$$ 1.42x $$.
Citation - WoS: 37
Citation - Scopus: 44
Adaptive Human Force Scaling Via Admittance Control for Physical Human-Robot Interaction
(IEEE, 2021) Başdoğan, Çağatay; Aydın, Yusuf; Hamad, Yahya M.
The goal of this article is to design an admittance controller for a robot to adaptively change its contribution to a collaborative manipulation task executed with a human partner to improve the task performance. This has been achieved by adaptive scaling of human force based on her/his movement intention while paying attention to the requirements of different task phases. In our approach, movement intentions of human are estimated from measured human force and velocity of manipulated object, and converted to a quantitative value using a fuzzy logic scheme. This value is then utilized as a variable gain in an admittance controller to adaptively adjust the contribution of robot to the task without changing the admittance time constant. We demonstrate the benefits of the proposed approach by a pHRI experiment utilizing Fitts’ reaching movement task. The results of the experiment show that there is a) an optimum admittance time constant maximizing the human force amplification and b) a desirable admittance gain profile which leads to a more effective co-manipulation in terms of overall task performance.
Citation - WoS: 1
Citation - Scopus: 4
All You Fear Is Love: the Roles of Rejection by Intimate Others
(Wiley, 2023) Aracı-İyiaydın, Ayşegül; Toplu-Demirtaş, Ezgi; Rohner, Ronald P. P.; Akçabozan-Kayabol, Nazlı Büşra
Interpersonal acceptance-rejection theory (IPARTheory) asserts that recollections of parental rejection in childhood tend to result in psychological maladjustment and intimacy problems in later romantic relationships. Informed by IPARTheory, we investigated the association between maternal & paternal rejection, and fear of intimacy by the mediating role of psychological maladjustment in a Turkish sample with 462 mostly young adults. We further explored the moderator role of gender in Model 1 and the moderating roles of both gender and intimate partner rejection in Model 2. Model 1 revealed that adults who had experienced maternal and paternal rejection in childhood tended to be psychologically maladjusted. Consequently, they also tended to have a fear of intimacy, regardless of gender. Model 2 revealed that women who recall having been rejected in childhood by their mothers tended to be psychologically maladjusted and to have a significant fear of intimacy when they also experienced moderate or more than moderate intimate-partner rejection. However, both women and men who experienced paternal rejection in childhood tended to be psychologically maladjusted and to experience a greater fear of intimacy when they perceived any degree of intimate partner rejection. Implications of the results for theory, research, and practice are discussed.
An Evaluation of the Psychometric Properties of the Strengths and Difficulties Scale in Turkey: Implications for Other Non-Weird Countries
(Wiley, 2023) Selçuk, Bilge; Tuncay, İpek; Arikan, Kübra; Yavus-Muren, H. Melis; Ruffman, Ted
The Strengths and Difficulties Questionnaire (SDQ) is a very widely used scale in which parents, teachers or the child rate various aspects of the child's well-being. It is widely used in the Western world and is translated into 80+ languages. It is also used in countries that do not classify as WEIRD (Western, educated, industrialized, rich and democratic). However, unlike WEIRD countries, some studies indicate that the psychometric properties of the SDQ when used in non-WEIRD countries are questionable. Therefore, we gave the SDQ to the mothers and teachers of 310 3- to 5-year-olds in urban centres of Turkey and examined its psychometric properties. Turkey is not a WEIRD country because it is not Western, although the participants in our study were well educated, living in an industrialized area, rich relative to others in Turkey (although poor relative to Westerners) and democratic. As such, it is not drastically different from WEIRD countries and our question was whether even relatively small deviations from standard WEIRD criteria could result in questionable psychometric properties for the SDQ.
Citation - WoS: 51
Citation - Scopus: 66
An Investigation of the Neural Correlates of Purchase Behavior Through Fnirs
(2018) Cakir, Murat Perit; Yurdakul, Dicle; Girisken, Yener; Çakar, Tuna
Purpose This study aims to explore the plausibility of the functional near-infrared spectroscopy (fNIRS) methodology for neuromarketing applications and develop a neurophysiologically-informed model of purchasing behavior based on fNIRS measurements. Design/methodology/approach The oxygenation signals extracted from the purchase trials of each subject were temporally averaged to obtain average signals for buy and pass decisions. The obtained data were analyzed via both linear mixed models for each of the 16 optodes to explore their separate role in the purchasing decision process and a discriminant analysis to construct a classifier for buy/pass decisions based on oxygenation measures from multiple optodes. Findings Positive purchasing decisions significantly increase the neural activity through fronto-polar regions, which are closely related to OFC and vmPFC that modulate the computation of subjective values. The results showed that neural activations can be used to decode the buy or pass decisions with 85 per cent accuracy provided that sensitivity to the budget constraint is provided as an additional factor. Research limitations/implications The study shows that the fNIRS measures can provide useful biomarkers for improving the classification accuracy of purchasing tendencies and might be used as a main or complementary method together with traditional research methods in marketing. Future studies might focus on real-time purchasing processes in a more ecologically valid setting such as shopping in supermarkets. Originality/value This paper uses an emerging neuroimaging method in consumer neuroscience, namely, fNIRS. The decoding accuracy of the model is 85 per cent which presents an improvement over the accuracy levels reported in previous studies. The research also contributes to existing knowledge by providing insights in understanding individual differences and heterogeneity in consumer behavior through neural activities.
Ban the Bomb by ... Banning the Bomb? a Turkish Response
(Taylor & Francis, 2017) Kibaroğlu, Mustafa
The golden age of deterrence has reached its end. Nuclear weapons, once a star player on the international stage, no longer enjoy a place in the limelight. To be sure, some policymakers still ascribe to nuclear weapons the same prestige that, during the Cold War, they gained because of their unmatched destructive power and the leverage they provided nuclear weapon states in the international arena. But the Cold War environment, in which nuclear weapons in the hands of two superpowers played a vital role in maintaining strategic stability, does not exist anymore. Nor is it likely to be replicated in the future – despite certain parallels between US–Soviet relations during the Cold War and present-day US–Russia relations. Meanwhile, it is painfully obvious that nuclear deterrence is useless against apocalyptic terrorist organizations motivated by religious extremism. If such a group acquired and used a nuclear weapon, there would be no “return address” toward which retaliation could be directed. And apocalyptic terrorists probably do not fear destruction in the first place. Now that the golden age of deterrence has reached its end, banning nuclear weapons has become achievable – as long as the values that policymakers ascribe to them can be undermined. Now is the time to strip away the handsome mask that hid nuclear weapons’ ugly face throughout the Cold War. It is time for the world to treat nuclear weapons just like chemical and biological weapons – those other weapons of mass destruction – as mere slaughtering weapons, undeserving of prestige. It is time to ban nuclear weapons – just as biological and chemical weapons were banned through the Biological and Toxin Weapons Convention and the Chemical Weapons Convention.
Citation - Scopus: 2
Brief Time Course of Trait Anxiety-Related Attentional Bias To Fearconditioned Stimuli: Evidence From the Dual-Rsvp Task
(Elsevier, 2016) Booth, Robert William
Background and objectives Attentional bias to threat is a much-studied feature of anxiety; it is typically assessed using response time (RT) tasks such as the dot probe. Findings regarding the time course of attentional bias have been inconsistent, possibly because RT tasks are sensitive to processes downstream of attention. Methods Attentional bias was assessed using an accuracy-based task in which participants detected a single digit in two simultaneous rapid serial visual presentation (RSVP) streams of letters. Before the target, two coloured shapes were presented simultaneously, one in each RSVP stream; one shape had previously been associated with threat through Pavlovian fear conditioning. Attentional bias was indicated wherever participants identified targets in the threat’s RSVP stream more accurately than targets in the other RSVP stream. Results In 87 unselected undergraduates, trait anxiety only predicted attentional bias when the target was presented immediately following the shapes, i.e. 160 ms later; by 320 ms the bias had disappeared. This suggests attentional bias in anxiety can be extremely brief and transitory. Limitations This initial study utilised an analogue sample, and was unable to physiologically verify the efficacy of the conditioning. The next steps will be to verify these results in a sample of diagnosed anxious patients, and to use alternative threat stimuli. Conclusions The results of studies using response time to assess the time course of attentional bias may partially reflect later processes such as decision making and response preparation. This may limit the efficacy of therapies aiming to retrain attentional biases using response time tasks.
Citation - WoS: 7
Citation - Scopus: 8
Business People in War Times, the ‘fluid Capital’ and the ‘shy Diaspora’: the Case of Syrians in Turkey
(Oxford University Press, 2021) Akçalı, Emel; Görmüş, Evrim
Due to intensive conflict, a significant amount of Syrian capital flight has funnelled to Turkey since 2011. Drawing upon fieldwork conducted in five major Turkish cities which have hosted the highest number of Syrian business people, this paper first reveals the convergence of the interests of the host state and of the displaced capital owners, as well as the increasing transnationalization of Syrian economic practices. It then assesses the capacity and/or willingness of the Syrian business people to organize themselves as an interest group regarding their interests in Turkey and to assist the process of conflict resolution in Syria. Finally, the paper reflects upon whether a hybrid identity is in the making within the Syrian business diaspora in Turkey. Our findings suggest that the Syrian business diaspora in Turkey is evolving itself into a transnational business community, and developing hybrid socio-economic practices. Yet, we delineate this flourishing community as ‘shy’ because the issues concerning both domestic and Syrian politics are carefully being avoided to keep stability and unity within. This consequently hinders the Syrian business community to form itself as an interest group in Turkey focused on conflict resolution and post-conflict reconstruction in Syria.
Citation - WoS: 15
Citation - Scopus: 13
Calibration of the Effective Spring Constant of Ultra-Short Cantilevers for a High-Speed Atomic Force Microscope
(2015) Xu, Lin-Yan; Wu, Sen; Hu, Xiao-Dong; Song, Yun-Peng; Fu, Xing; Zhang, Jun-Ming; Dorantes-Gonzalez, Dante Jorge
Ultra-short cantilevers are a new type of cantilever designed for the next generation of high-speed atomic force microscope (HS-AFM). Ultra-short cantilevers have smaller dimensions and higher resonant frequency than conventional AFM cantilevers. Moreover, their geometry may also be different from the conventional beam-shape or V-shape. These changes increase the difficulty of determining the spring constant for ultra-short cantilevers, and hence limit the accuracy and precision of force measurement based on a HS-AFM. This paper presents an experimental method to calibrate the effective spring constant of ultra-short cantilevers. By using a home-made AFM head, the cantilever is bent against an electromagnetic compensation balance under servo control. Meanwhile the bending force and the cantilever deflection are synchronously measured by the balance and the optical lever in the AFM head, respectively. Then the effective spring constant is simply determined as the ratio of the force to the corresponding deflection. Four ultra-short trapezoid shape cantilevers were calibrated using this method. A quantitative uncertainty analysis showed that the combined relative standard uncertainty of the calibration result is less than 2%, which is better than the uncertainty of any previously reported techniques.
Citation - WoS: 52
Citation - Scopus: 58
Carbon Price Forecasting Models Based on Big Data Analytics
(Taylor and Francis Ltd., 2019) Çanakoğlu, Ethem; Ağralı, Semra; Yahşi, Mustafa
After the establishment of the European Union's Emissions Trading System (EU-ETS) carbon pricing attracted many researchers. This paper aims to develop a prediction model that anticipates future carbon prices given a real-world data set. We treat the carbon pricing issue as part of big data analytics to achieve this goal. We apply three fundamental methodologies to characterize the carbon price. First method is the artificial neural network, which mimics the principle of human brain to process relevant data. As a second approach, we apply the decision tree algorithm. This algorithm is structured through making multiple binary decisions, and it is mostly used for classification. We employ two different decision tree algorithms, namely traditional and conditional, to determine the type of decision tree that gives better results in terms of prediction. Finally, we exploit the random forest, which is a more complex algorithm compared to the decision tree. Similar to the decision tree, we test both traditional and conditional random forest algorithms to analyze their performances. We use Brent crude futures, coal, electricity and natural gas prices, and DAX and S&P Clean Energy Index as explanatory variables. We analyze the variables' effects on carbon price forecasting. According to our results, S&P Clean Energy Index is the most influential variable in explaining the changes in carbon price, followed by DAX Index and coal price. Moreover, we conclude that the traditional random forest is the best algorithm based on all indicators. We provide the details of these methods and their comparisons.
Citation - WoS: 13
Citation - Scopus: 19
Characterizing a Highly Accomplished Teacher’s Noticing of Third-Grade Students’ Mathematical Thinking
(Springer, 2017) Taylan, Rukiye Didem
This study investigated a highly accomplished third-grade teacher’s noticing of students’ mathematical thinking as she taught multiplication and division. Through an innovative method, which allowed for documenting in-the-moment teacher noticing, the author was able to explore teacher noticing and reflective practices in the context of classroom teaching as opposed to professional development environments. Noticing was conceptualized as both attending to different elements of classroom instruction and making sense of classroom events. The teacher paid most attention to student thinking and was able to offer a variety of rich interpretations of student thinking which were presented in an emergent framework. The results also indicated how the teacher’s noticing might influence her instructional decisions. Implications for both research methods in studying noticing and teacher learning and practices are discussed.
Citation - WoS: 40
Citation - Scopus: 38
Clinical and Economic Burden Associated With Cardiovascular Events Among Patients With Hyperlipidemia: a Retrospective Cohort Study
(2016) Wang, Li; Quek, Ruben G. W; Fox, Kathleen M; Gandra, Shravanthi R; Li, Lu; Başer, Onur
Background: Annual direct costs for cardiovascular (CV) diseases in the United States are approximately $195.6 billion, with many high-risk patients remaining at risk for major cardiovascular events (CVE). This study evaluated the direct clinical and economic burden associated with new CVE up to 3 years post-event among patients with hyperlipidemia. Methods: Hyperlipidemic patients with a primary inpatient claim for new CVE (myocardial infarction, unstable angina, ischemic stroke, transient ischemic attack, coronary artery bypass graft, percutaneous coronary intervention and heart failure) were identified using IMS LifeLink PharMetrics Plus data from January 1, 2006 through June 30, 2012. Patients were stratified by CV risk into history of CVE, modified coronary heart disease risk equivalent, moderate-and low-risk cohorts. Of the eligible patients, propensity score matched 243,640 patients with or without new CVE were included to compare healthcare resource utilization and direct costs ranging from the acute (1-month) phase through 3 years post-CVE date (follow-up period). Results: Myocardial infarction was the most common CVE in all the risk cohorts. During the acute phase, among patients with new CVE, the average incremental inpatient length of stay and incremental costs ranged from 4.4-6.2 days and $25,666-$30,321, respectively. Acute-phase incremental costs accounted for 61-75 % of first-year costs, but incremental costs also remained high during years 2 and 3 post-CVE. Conclusions: Among hyperlipidemic patients with new CVE, healthcare utilization and costs incurred were significantly higher than for those without CVE during the acute phase, and remained higher up to 3 years post-event, across all risk cohorts.
Citation - WoS: 11
Citation - Scopus: 16
Consistency of Adults’ Earliest Memories Across Two Years
(Taylor & Francis, 2019) Gülgöz, Sami; Demiray, Burcu; Ece, Berivan
The consistency of earliest memories in content, dating, and memory qualities was investigated. A total of 84 (27 males; Mage = 24.93, SD = 1.36) adults reported earliest memories, estimated ages, and rated their recollections on memory qualities with a two-year time lag. At Time 2, their original reports at Time 1 were presented and they were asked to report whether the earliest memories they recalled at Time 2 were the same. Fifty-six per cent of the participants reported the same earliest memories and those remembering the same events had earlier memories than those remembering different ones. Although no significant differences were observed in estimated ages on the basis of mean ages, a predating bias of later memories and a tendency to postdate earlier memories were observed on the basis of a 48-month cut-off point. Thus, how the data is analysed is critical in detecting dating biases or errors affecting conclusions and interpretations about the dating consistency of earliest memories. Finally, memory qualities of earliest memories displayed a high level of consistency with a two-year time lag regardless of remembering the same versus different event.
Citation - WoS: 1
Citation - Scopus: 2
Determinants of Turkish Female Labour Force Participation: an Analysis With Manufacturing Firm-Level Data
(Taylor & Francis, 2020) Karamollaoğlu, Nazlı; Soybilgen, Barış
Compared to other developing countries, Turkey has a very low female labour participation rate. Previous studies usually focus on the labour supply side of female employment. Unlike the previous literature, this paper investigates firm-level determinants of female employment in manufacturing firms using a unique micro data set constructed using different sources. After controlling for geographical variation, firm, and industry-specific factors, our results show that larger firms, exporter firms, firms with higher part-time worker ratio, and foreign-owned firms have higher female employment rate whereas younger firms, firms with higher labour productivity, and firms with long working hours have lower female employment rate.
Citation - WoS: 4
Citation - Scopus: 5
Disentangling the Dynamic Digital Capability, Digital Transformation, and Organizational Performance Relationships in Smes: a Configurational Analysis Based on Fsqca
(Springer, 2024) Saunila, Minna; Karadağ, Hande; Şahin, Faruk; Karamollaoğlu, Nazlı
While digitalization has become inevitable for firms of every size, a limited number of studies to date aimed to investigate the impact of digital capabilities and digital transformation on the organizational performance of small businesses. Drawing on the dynamic capabilities view, the current study analyzes the conditions under which the dynamic digital capability of a small and medium-sized enterprise (SME) would lead to higher performance. In this study, a unique fuzzy-set qualitative comparative analysis methodology was used for analyzing the data collected from 136 SMEs for investigating the IT utilization, human capital, digital maturity, and digitalization strategy antecedents of dynamic digital capability. The results reveal that two particular configurations of dynamic digital capability are identified as the main digitalization influencers of organizational performance in SMEs. To the best of our knowledge, this study presents the first empirical findings to the literature about dynamic digital capability and organizational performance relationships in SMEs through the utilization of configurational analysis methodology. Theoretically, the study addresses an acknowledged need for a holistic approach to uncover the underlying mechanisms of dynamic digital capability formation and digital transformation in small firms, with their impact on firm performance. The findings also present vital practical implications for business owners, policy-makers, and bodies responsible for SMEs, by providing new insights about the combination of factors that drive high performance, particularly at times of turbulence, in these units.
Disentangling the Dynamic Digital Capability, Digital Transformation, and Organizational Performance Relationships in Smes: a Configurational Analysis Based on Fsqca (sept, 10.1007/S10799-024-00437-y, 2024)
(Springer, 2024) Karadag, Hande; Sahin, Faruk; Karamollaoglu, Nazli; Saunila, Minna
[No Abstract Available]
Citation - WoS: 3
Citation - Scopus: 4
Does Credit Composition Matter for Current Account Dynamics? Evidence From Turkey
(Taylor & Francis, 2016) Toraganlı, Nazlı; Ertuğrul, Hasan Murat
Based on a dynamic approach using the Kalman filter we depict effects of time-varying interactions between different components of credit stock on the current account in the Turkish Economy for the period 2002Q3–2014Q3. We decompose the credit stock into consumer and non-financial corporate sector credit and show empirically that both types of credit stock have negative effects on the current account dynamics
Citation - WoS: 41
Citation - Scopus: 36
Electric Vehicle Routing With Flexible Time Windows: a Column Generation Solution Approach
(Taylor & Francis, 2020) Taş, Duygu
In this paper, we introduce the Electric Vehicle Routing Problem with Flexible Time Windows (EVRPFTW) in which vehicles are allowed to serve customers before and after the earliest and latest time window bounds, respectively. The objective of this problem is to assign electric vehicles to feasible routes and make schedules with minimum total cost that includes the traveling costs, the costs of using electric vehicles and the penalty costs incurred for earliness and lateness. The proposed mathematical model is solved by a column generation procedure. To generate an integer solution, we solve an integer programming problem using the routes constructed by the column generation algorithm. We further develop a linear programming model to compute the optimal times to start service at each customer for the selected routes. A number of wellknown benchmark instances is solved by our solution procedure to evaluate the operational gains obtained by employing flexible time windows.
Citation - WoS: 9
Citation - Scopus: 12
Elevated White Blood Cell Levels and Thrombotic Events in Patients With Polycythemia Vera: a Real-World Analysis of Veterans Health Administration Data
(Elsevier Inc., 2019) Wang, Li; Parasuraman, Shreekant V.; Sulena Shrestha; Paranagama, Dilan C.; Yu, Jingbo; Scherber, Robyn Marie; Başer, Onur
Background: Patients with polycythemia vera (PV) have a substantial risk of thrombotic events (TEs). The objective of the present analysis was to describe the association between white blood cell (WBC) levels and occurrence of TEs among patients with PV from a large real-world population. Patients and Methods: The present retrospective analysis using Veterans Health Administration claims data (October 1, 2005, to September 30, 2012) evaluated adult patients assigned to 4 WBC count categories (WBC count < 7.0, 7.0-8.4, 8.5 to < 11.0, and ≥ 11.0 × 109/L) to compare the risk of TEs (reference, WBC count, < 7.0 × 109/L group). Analysis was performed using a Cox proportional hazards model, considering WBC status as a time-dependent covariate. Results: Of the 1565 patients with PV included in the present analysis, the WBC count was < 7.0 × 109/L for 428 (27.3%), 7.0 to 8.4 × 109/L for 375 (24.0%), 8.5 to < 11.0 × 109/L for 284 (18.1%), and ≥ 11.0 × 109/L for 478 (30.5%). Of the 1565 patients, 390 (24.9%) had experienced a TE during the study period. The mean follow-up ranged from 3.6 to 4.5 years. Compared with the reference group (WBC count < 7.0 ×109/L), the hazard ratio for TEs was 1.10 (95% confidence interval [CI], 0.82-1.48; P = .5395), 1.47 (95% CI, 1.10-1.96; P = .0097), and 1.87 (95% CI, 1.44-2.43; P < .0001) for patients with a WBC count of 7.0 to 8.4, 8.5 to < 11.0, and ≥ 11.0 ×109/L, respectively. Conclusion: A positive, significant association between an increased WBC count of ≥ 8.5 ×109/L and the occurrence of TEs was observed in patients with PV. The potential thrombogenic role of WBCs in patients with PV supports the continued inclusion of WBC count control in disease management and evaluation of the response to therapy. © 2019 The AuthorsPatients with polycythemia vera (PV) have a substantial risk of thrombotic events (TEs). In the present retrospective analysis using Veterans Health Administration claims data, 25% of 1565 patients experienced a TE during follow-up. We observed a positive, significant association between white blood cell (WBC) counts ≥ 8.5 × 109/L and TE occurrence (reference, WBC count < 7.0 × 109/L), supporting continued inclusion of WBC count control in disease management. © 2019 The Authors

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