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Permanent URI for this collectionhttps://hdl.handle.net/20.500.14288/6
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Publication Open Access Uluslararası çocuk kaçırmanın hukuki veçhelerine dair Lahey Sözleşmesi çerçevesinde aile hakkına saygı hakkı ve çocuğun üstün menfaatinin korunması: Marcus Frank Cerny başvurusu üzerinden bir inceleme(N/A, 2017) Oba, Meltem Ece; Law SchoolIn this study, the 1980 Hague Convention on the Civil Aspects of International Child Abductions is briefly explained and the Constitutional Court judgement on the Marcus Frank Cerny application is evaluated within the framework of the case law of the European Court of Human Rights.;TR: Bu çalışmada 1980 tarihli Uluslararası Çocuk Kaçırmaların Hukuki Veçhelerine Dair Lahey Sözleşmesi kısaca açıklanarak Marcus Frank Cerny başvurusuna ilişkin Anayasa mahkemesi kararı, İnsan Hakları Avrupa Mahkemesi içtihadı çerçevesinde değerlendirilmiştir.Publication Open Access Female labor force participation in Turkey: a synthetic cohort analysis, 1988-2013(2017) Kırdar, Murat Güray; Dayıoğlu, Meltem; Department of Economics; Tunalı, Fehmi İnsan; Faculty Member; Department of Economics; College of Administrative Sciences and Economics; 105635We study the aggregate labor force participation behavior of women over a 25-year period in Turkey using a synthetic panel analysis. In our decomposition of age, year, and cohort effects, we use three APC models that have survived the scrutiny of the demography community. We rely on predictions from just-identified models that render different methods comparable. The exercise is carried out by rural/urban status and by education to tease out some key differences in behavior. Our comparative methodology yields remarkably robust age-profiles that represent the behavior of a typical woman over her life-cycle. Notably an M-shape attributable to child-bearing related concerns is detected in rural areas and for low-educated women in urban areas. We also find that later birth-cohorts among the less-educated women—which constitutes the majority of the female workforce—are significantly more likely to participate, which implies that the recent rise in the aggregate participation rates is not only due to rising education levels and that the current substantial gap in participation by education will decrease.Publication Open Access Dynamic accommodation measurement using Purkinje reflections and ML algorithms(Society of Photo-optical Instrumentation Engineers (SPIE), 2023) Department of Electrical and Electronics Engineering; N/A; Aygün, Uğur; Şahin, Afsun; Ürey, Hakan; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); College of Engineering; School of Medicine; N/A; N/A; N/A; 171267; 8579We developed a prototype device for dynamic gaze and accommodation measurements based on 4 Purkinje reflections (PR) suitable for use in AR and ophthalmology applications. PR1&2 and PR3&4 are used for accurate gaze and accommodation measurements, respectively. Our eye-model was developed in Zemax and matches the experiments well. Our model predicts the accommodation from 25cm to infinity (<4 diopters) with better than 0,25D accuracy. We performed repeatability tests and obtained accurate gaze and accommodation estimations using 15 subjects. We are generating a large synthetic data set using physically accurate models and machine learning algorithms.Publication Open Access Wearable multi-color RAPD screening device(Society of Photo-optical Instrumentation Engineers (SPIE), 2023) Department of Electrical and Electronics Engineering; Aygün, Uğur; Şahin, Afsun; Ürey, Hakan; Hasanreisoğlu, Murat; Kavaklı, Koray; Küçüködük, Abdullah; Faculty Member; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; School of Medicine; Koç University Hospital; N/A; N/A; 171267; 8579; 182001; N/A; N/A; N/A; N/A; N/AIn this work, we developed a wearable, head-mounted device that automatically calculates the precise Relative Afferent Pupillary Defect (RAPD) value of a patient. The device consists of two RGB LEDs, two infrared cameras, and one microcontroller. In the RAPD test, the parameters like LED on-off durations, brightness level, and color of the light can be controlled by the user. Upon data acquisition, a computational unit processes the data, calculates the RAPD score and visualizes the test results with a user-friendly interface. Multiprocessing methods used on GUI to optimize the processing pipeline. We have shown that our head-worn instrument is easy to use, fast, and suitable for early-diagnostics and screening purposes for various neurological conditions such as RAPD, glaucoma, asymmetric glaucoma, and anisocoria.Publication Open Access Cluster index modulation for mmWave communication systems(Frontiers, 2022) Koç, Asil; Le-Ngoc, Tho; Department of Electrical and Electronics Engineering; Başar, Ertuğrul; Raeisi, Mahmoud; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 149116; N/AIn this study, a novel cluster index modulation (CIM) scheme, which is based on indexing the available clusters in the environment, is proposed for future mmWave communication systems. Exploiting the fact that the available clusters in the system are well separated in terms of their angular distribution, we selected the best path for each of them and then performed IM in an algorithmic manner to convey information bits. It is shown that by means of large antenna arrays and analog RF beamforming with the indexed clusters, the destructive effect of inter-beam/cluster interference can be remarkably mitigated. Also, we designed a hybrid beamforming architecture at the transmitter to further reduce the effect of residual inter-beam/cluster interference, where the analog RF beamformer is followed by a digital baseband precoder using the zero-forcing technique. Computer simulations reveal that the proposed scheme can provide better error performance than traditional mmWave communication, and the proposed hybrid architecture outperforms beam index modulation (BIM) for a point-to-point scenario. Semi-analytical derivations and closedform unconditional pairwise error probability (UPEP) expressions are derived for both analog and hybrid architectures, which confirm the validity and superiority of our proposed scheme.Publication Open Access Universal transceivers: opportunities and future directions for the Internet of Everything (IoE)(Frontiers, 2021) Department of Electrical and Electronics Engineering; Kuşcu, Murat; Civaş, Meltem; Çetinkaya, Oktay; Akan, Özgür Barış; Researcher; Faculty Member; Department of Electrical and Electronics Engineering; College of Engineering; Graduate School of Sciences and Engineering; 316349; N/A; N/A; 6647The Internet of Everything (IoE) is a recently introduced information and communication technology (ICT) framework promising for extending the human connectivity to the entire universe, which itself can be regarded as a natural IoE, an interconnected network of everything we perceive. The countless number of opportunities that can be enabled by IoE through a blend of heterogeneous ICT technologies across different scales and environments and a seamless interface with the natural IoE impose several fundamental challenges, such as interoperability, ubiquitous connectivity, energy efficiency, and miniaturization. The key to address these challenges is to advance our communication technology to match the multi-scale, multi-modal, and dynamic features of the natural IoE. To this end, we introduce a new communication device concept, namely the universal IoE transceiver, that encompasses transceiver architectures that are characterized by multi-modality in communication (with modalities such as molecular, RF/THz, optical and acoustic) and in energy harvesting (with modalities such as mechanical, solar, biochemical), modularity, tunability, and scalability. Focusing on these fundamental traits, we provide an overview of the opportunities that can be opened up by micro/nanoscale universal transceiver architectures towards realizing the IoE applications. We also discuss the most pressing challenges in implementing such transceivers and briefly review the open research directions. Our discussion is particularly focused on the opportunities and challenges pertaining to the IoE physical layer, which can enable the efficient and effective design of higher-level techniques. We believe that such universal transceivers can pave the way for seamless connection and communication with the universe at a deeper level and pioneer the construction of the forthcoming IoE landscape.Publication Open Access Raman spectroscopic and microscopic analysis of tissue type, molecular composition, and glioblastoma identification in brain tissue sections(Koç University, 2021) N/A; Torun, Hülya; Graduate School of Sciences and EngineeringGlioblastoma (GB) is the most common primary malignant brain tumor. Despite improvements in treatments, survival probability has remained shorter than 2 years for most patients over the last 20 years. Accurate diagnosis of GB requires pathological evaluation of the tumor tissues using light microscopy, along with routine or specialized staining. Recent research also identified significant genetic/epigenetic alterations that influence diagnosis, prognosis, and treatment in addition to routine pathological evaluation. Identification requires the tissue to be sampled many times and analyzed using different methods that require additional time, resources, and expertise. To determine whether the tissue used for routine analysis can also be used to perform more detailed and comprehensive analysis without staining, we propose to use Raman Spectroscopy (RS), which is a label-free and non-destructive technique. RS provides molecule-specific spectra from the chemical composition of the sample for rapid analysis. In this thesis, we investigated GB, white matter (WM), gray matter (GM), and necrosis (NC) regions of GB patients using RS to determine whether a similar precision can be achieved as the routine histomorphologic diagnostic process. First, we proposed a refined protocol for effectively clearing paraffin from Formalin-Fixed Paraffin-Embedded brain tissue sections, without destroying the sample morphology and chemical composition, for eliminating the substantial Raman spectra of paraffin. We demonstrated that the less expensive and less toxic clearing agent CleareneTM removes paraffin as effectively as p-Xylene, the mostly used clearing agent in histopathology laboratories. Thus, we suggest substituting CleareneTM with p-Xylene for deparaffinization of brain tissue sections for Raman spectral analysis. Second, we optimized the choice of Raman spectrum acquisition parameters (excitation wavelength, acquisition time, accumulation count,), tissue thickness, and Raman substrate type (CaF2, glass). Third, we acquired the Raman spectra of GB, WM, GM, and NC regions and analyzed the spectral profile regarding the Raman peaks given in the literature. Raman spectra of GB and WM regions (nGB = 20, nWM = 18), which were annotated by an expert neuropathologist, have been classified with 87.2±1% GB and 90.7±1% WM training/test accuracies using machine learning models (SVM, kNN, RF). The effect of pre-processing of Raman spectra on classification accuracies has been investigated. Sample preparation conditions, Raman acquisition protocols, and machine learning classification models showed a successful proof-of-concept demonstration for the proposed Raman-based GB identification workflow. While there is room for further refining the machine learning models for improved training and validation accuracies, these protocols could be improved for eventual clinical utility. Once the clinical applicability and refined classification accuracies are demonstrated, these protocols might assist neuropathologists in error-free identification of GB in the clinics.Publication Open Access Artificial eye model and holographic display based IOL simulator(Society of Photo-optical Instrumentation Engineers (SPIE), 2023) N/A; Department of Electrical and Electronics Engineering; N/A; Şahin, Afsun; Ürey, Hakan; Aygün, Uğur; Kavaklı, Koray; Akyazı, Deniz; Faculty Member; Faculty Member; Department of Electrical and Electronics Engineering; School of Medicine; College of Engineering; Graduate School of Sciences and Engineering; 171267; 8579; N/A; N/A; N/ACataract is a common ophthalmic disease in which a cloudy area is formed in the lens of the eye and requires surgical removal and replacement of eye lens. Careful selection of the intraocular lens (IOL) is critical for the post-surgery satisfaction of the patient. Although there are various types of IOLs in the market with different properties, it is challenging for the patient to imagine how they will perceive the world after the surgery. We propose a novel holographic vision simulator which utilizes non-cataractous regions on eye lens to allow the cataract patients to experience post-operative visual acuity before surgery. Computer generated holography display technology enables to shape and steer the light beam through the relatively clear areas of the patient’s lens. Another challenge for cataract surgeries is to match the right patient with the right IOL. To evaluate various IOLs, we developed an artificial human eye composed of a scleral lens, a glass retina, an iris, and a replaceable IOL holder. Next, we tested different IOLs (monofocal and multifocal) by capturing real-world scenes to demonstrate visual artifacts. Then, the artificial eye was implemented in the benchtop holographic simulator to evaluate various IOLs using different light sources and holographic contents.Publication Open Access On the number of solutions to the asymptotic plateau problem(Gökova Geometry Topology (GGT) Conferences, 2011) Department of Mathematics; Coşkunüzer, Barış; Faculty Member; Department of Mathematics; College of SciencesBy using a simple topological argument, we show that the space of closed, orientable, codimension-1 submanifolds of Sn−1 1 (Hn) which bound a unique absolutely area minimizing hypersurface in Hn is dense in the space of closed, orientable, codimension-1 submanifolds of Sn−1 1 (Hn). In particular, in dimension 3, we prove that the set of simple closed curves in S2 1(H3) bounding a unique absolutely area minimizing surface in H3 is not only dense, but also a countable intersection of open dense subsets of the space of simple closed curves in S2 1(H3) with C0 topology. We also show that the same is true for least area planes in H3. Moreover, we give some non-uniqueness results in dimension 3.Publication Open Access Interval timing, dopamine, and motivation(Brill, 2014) Department of Psychology; Balcı, Fuat; Faculty Member; Department of Psychology; College of Social Sciences and Humanities; 51269The dopamine clock hypothesis suggests that the dopamine level determines the speed of the hypothetical internal clock. However, dopaminergic function has also been implicated for motivation and thus the effect of dopaminergic manipulations on timing behavior might also be independently mediated by altered motivational state. Studies that investigated the effect of motivational manipulations on peak responding are reviewed in this paper. The majority of these studies show that a higher reward magnitude leads to a leftward shift, whereas reward devaluation leads to a rightward shift in the initiation of timed anticipatory behavior, typically in the absence of an effect on the timing of response termination. Similar behavioral effects are also present in a number of studies that investigated the effect of dopamine agonists and dopamine-related genetic factors on peak responding. These results can be readily accounted for by independent modulation of decision-thresholds for the initiation and termination of timed responding.