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Publication Metadata only Three-dimensional echocardiographic demonstration of aortic wall erosion after percutaneous atrial septal defect closure(WILEY, 2019) Mohamed, Ahmed Mohsen; Turkmen, Irem; Abdrabou, Mostafa Mahmoud Mohamed; Oz, Tugba Kemaloglu; Egyptian Knowledge Bank (EKB); Cairo University; Bahcesehir University; Istanbul Medipol UniversityAlthough late complications of percutaneous closure of atrial septal defect (ASD), including cardiac erosion and thrombosis, are rare, they are the most lethal. Data are still lacking regarding the usefulness of new imagining modalities, such as three-dimensional echocardiography (3DE), for the detection of these complications. Here, we report the case of a 57-year-old woman in whom cardiac erosion was very well visualized by 3D transesophageal echocardiography (3D TEE) after percutaneous ASD closure.Publication Metadata only Coupled Shape Priors for Dynamic Segmentation of Dendritic Spines(IEEE, 2017) Atabakilachini, Naeimeh; Erdil, Ertunc; Argunsah, A. Ozgur; Rada, Lavdie; Unay, Devrim; Cetin, Mujdat; Sabanci University; University of Zurich; Bahcesehir University; Izmir Ekonomi UniversitesiSegmentation of biomedical images is a challenging task, especially when there is low quality or missing data. The use of prior information can provide significant assistance for obtaining more accurate results. In this paper we propose a new approach for dendritic spine segmentation from microscopic images over time, which is motivated by incorporating shape information from previous time points to segment a spine in the current time point. In particular, using a training set consisting of spines in two consecutive time points to construct coupled shape priors, and given the segmentation in the previous time point, we can improve the segmentation process of the spine in the current time point. Our approach has been evaluated on 2-photon microscopy images of dendritic spines and its effectiveness has been demonstrated by both visual and quantitative results.Publication Metadata only Prenatal Diagnosis and Outcomes of Fetal Teratomas(WILEY, 2016) Arisoy, Resul; Erdogdu, Emre; Kumru, Pinar; Demirci, Oya; Ergin, Nida; Pekin, Oya; Sahinoglu, Zeki; Tugrul, Ahmet Semih; Sancak, Selim; Cetiner, Handan; Celayir, Aysenur; Istanbul Zeynep Kamil Maternity & Children's Diseases Training & Research Hospital; Bahcesehir University; Istanbul Zeynep Kamil Maternity & Children's Diseases Training & Research Hospital; Istanbul Zeynep Kamil Maternity & Children's Diseases Training & Research Hospital; Istanbul Zeynep Kamil Maternity & Children's Diseases Training & Research HospitalPurpose. Our aim was to evaluate the diagnostic performance of ultrasonography (US) in the prenatal identification of teratomas and the perinatal outcome of the fetuses with those teratomas. Methods. In this retrospective case series study, we searched the archives using the keywords fetal mass or fetal tumor or fetal teratoma and sacrococcygeal teratoma,diagnosed between 2009 and 2014, within the US database of our center. Results. One hundred seven fetuses were prenatally diagnosed as having a cystic or solid mass, tumor, or teratoma. Nineteen of those cases were diagnosed prenatally as having fetal teratoma, but that diagnosis could not be verified in three cases. In one fetus, the prenatal diagnosis could not be confirmed. The sensitivity of US in identifying fetal teratoma was 100% and the false-positive rate, 3.3%. Six pregnancies complicated by a fetal teratoma were terminated. A normal karyotype was identified in all fetuses that underwent karyotyping. Among the nine women who continued their pregnancy, polyhydramnios was identified in four fetuses, although high-output heart failure was also identified in two of those fetuses during prenatal follow-up, none developed hydrops. On delivery, nine infants were born alive, but three (33.3%) of them died within the early neonatal period. Conclusions. US has very high sensitivity and low false-positive rates in identifying fetal teratoma pre-natally. The risk of chromosomal abnormalities is very low in fetuses with teratoma, and their prognosis depends on the location and size of the tumor and any associated perinatal complications. (C) 2015 Wiley Periodicals, Inc.Publication Metadata only A wavelet packet adaptive filtering algorithm for enhancing manatee vocalizations(ACOUSTICAL SOC AMER AMER INST PHYSICS, 2011) Gur, M. Berke; Niezrecki, Christopher; Bahcesehir University; University of Massachusetts System; University of Massachusetts LowellApproximately a quarter of all West Indian manatee (Trichechus manatus latirostris) mortalities are attributed to collisions with watercraft. A boater warning system based on the passive acoustic detection of manatee vocalizations is one possible solution to reduce manatee-watercraft collisions. The success of such a warning system depends on effective enhancement of the vocalization signals in the presence of high levels of background noise, in particular, noise emitted from watercraft. Recent research has indicated that wavelet domain pre-processing of the noisy vocalizations is capable of significantly improving the detection ranges of passive acoustic vocalization detectors. In this paper, an adaptive denoising procedure, implemented on the wavelet packet transform coefficients obtained from the noisy vocalization signals, is investigated. The proposed denoising algorithm is shown to improve the manatee detection ranges by a factor ranging from two (minimum) to sixteen (maximum) compared to high-pass filtering alone, when evaluated using real manatee vocalization and background noise signals of varying signal-to-noise ratios (SNR). Furthermore, the proposed method is also shown to outperform a previously suggested feedback adaptive line enhancer (FALE) filter on average 3.4 dB in terms of noise suppression and 0.6 dB in terms of waveform preservation. (C) 2011 Acoustical Society of America. [DOI: 10.1121/1.3557031]Publication Metadata only Active vibration control of a blade element with uncertainty modeling in PZT actuator force(SAGE PUBLICATIONS LTD, 2019) Sivrioglu, Selim; Bolat, Fevzi Cakmak; Erturk, Ercan; Gebze Technical University; Bayburt University; Bahcesehir UniversityThe aim of this research is to attenuate the vibrations of a blade structure with an attached piezoelectric actuator using robust multi-objective control. The force obtained from a piezoelectric patch loading has uncertainties due to the complicated shape (airfoil) of the blade element. A parameter-dependent model of the force equation is developed to understand the possible variation range of the actuation force. The modal analysis of the blade is performed to find vibration mode frequencies, and an aerodynamic load is generated experimentally to create steady-state vibration on the blade. A state-space model is obtained by considering certain vibration modes and the parameter-dependent part of the force in the input vector is taken outside of the plant model. The robust stability filter is modified with parameter dependency to have a cluster of the filter. Two different multi-objective controllers are designed with different design objectives. The designed controllers are implemented in experiments and performances of the controllers are compared using frequency and time domain responses. It is shown that the flexible blade vibrations are successfully suppressed with the proposed mixed norm robust controllers under the effect of steady-state aerodynamic disturbance with different air speeds. It is observed in experimental results that the performances of the H infinity/H2controller are better than theH2/H infinity controller.Publication Metadata only Formant position based weighted spectral features for emotion recognition(ELSEVIER, 2011) Bozkurt, Elif; Erzin, Engin; Erdem, Cigdem Eroglu; Erdem, A. Tanju; Koc University; Bahcesehir University; Ozyegin UniversityIn this paper, we propose novel spectrally weighted mel-frequency cepstral coefficient (WMFCC) features for emotion recognition from speech. The idea is based on the fact that formant locations carry emotion-related information, and therefore critical spectral bands around formant locations can be emphasized during the calculation of MFCC features. The spectral weighting is derived from the normalized inverse harmonic mean function of the line spectral frequency (LSF) features, which are known to be localized around formant frequencies. The above approach can be considered as an early data fusion of spectral content and formant location information. We also investigate methods for late decision fusion of unimodal classifiers. We evaluate the proposed WMFCC features together with the standard spectral and prosody features using HMM based classifiers on the spontaneous FAU Aibo emotional speech corpus. The results show that unimodal classifiers with the WMFCC features perform significantly better than the classifiers with standard spectral features. Late decision fusion of classifiers provide further significant performance improvements. (C) 2011 Elsevier B.V. All rights reserved.Publication Metadata only Energy and Spectral Efficiency for Heterogeneous Cellular Networks with Stochastic Deployment(IEEE, 2017) Demirtas, Mahmut; Saginda, Cagatay; Soysal, Alkan; Bahcesehir UniversityIn this paper, we investigate the energy efficiency and spectral efficiency of heterogeneous networks, where macro cell and microcell base stations are deployed according to two separate stochastic geometry based processes. Here, micro base stations are placed over the regions for which the received signal strength is below a certain limit. By employing the deployment model we propose, we investigate the effects of certain parameters like macro and micro base station densities, and user density on energy efficiency of heterogeneous networks. The results show that deploying micro base stations considerably improves both energy efficiency and spectral efficiency in a dense user scenario.Publication Metadata only Large-amplitude vibration of the geometrically imperfect FGM truncated conical shell(SAGE PUBLICATIONS LTD, 2015) Sofiyev, A. H.; Kuruoglu, N.; Suleyman Demirel University; Bahcesehir UniversityIn this study, the large-amplitude vibration of a functionally graded (FG) truncated conical shell with an initial geometric imperfection has been investigated using large deformation theory with a von Karman-Donnell type of kinematic nonlinearity. The material properties of an FG truncated conical shell are assumed to vary continuously through the thickness. The fundamental relations, the modified Donnell-type nonlinear motion, and compatibility equations of the FG truncated conical shell with an initial geometric imperfection are derived. The relation between nonlinear frequency parameters with the dimensionless amplitude of imperfect FG truncated conical shells is obtained. Finally, the influences of variations of the initial geometric imperfection, compositional profiles, and shell characteristics on the dimensionless nonlinear frequency parameter and frequency-amplitude relations are investigated. The present results are compared with the available data for a special case.Publication Metadata only ESTIMATION OF THE NEUTRAL FACE SHAPE USING GAUSSIAN MIXTURE MODELS(IEEE, 2012) Ulukaya, Sezer; Erdem, Cigdem Eroglu; Bogazici University; Bahcesehir UniversityWe present a Gaussian Mixture Model (GMM) fitting method for estimating the unknown neutral face shape for frontal facial expression recognition using geometrical features. Subtracting the estimated neutral face, which is related to the identity-specific component of the shape leaves us with the component related to the variations resulting from facial expressions. Experimental results on the Extended Cohn-Kanade (CK+) database show that subtracting the estimated neutral face shape gives better emotion recognition rates as compared to classifying the geometrical facial features directly, when the person-specific neutral face shape is not available. We also experimentally evaluate two different geometric facial feature extraction methods for emotion recognition. The average emotion recognition rates achieved with the proposed neutral shape estimation method and coordinate based features is 88%, which is higher than the baseline results presented in the literature, although we do not use the person-specific neutral shapes (94% if we use), and any appearance based features.Publication Metadata only Classification of Band-Specific Regional Hemispheric Connectivity in Obsessive Compulsive Disorder(IEEE, 2017) Aydin, Serap; Tan, Oguz; Bahcesehir University; Uskudar UniversityIn the present study, inter-electrode hemispheric dependency has been estimated by using frequency, time and phase domain methods (Fourier Correlation, Wavelet Correlation (WC), Hilbert Correlation) for eight individual brain lobes (pre-frontal, anterio-frontal, central, occipital, parietal, posterio-frontal, anterio-temporal, posterio-temporal) in five frequency band activities (Delta (0.5 - 4 Hz), Theta (4 - 8 Hz), Alpha (8-16 Hz), Beta (16-32 Hz) and, Gamma (32-64 Hz)) for detection of obsessive compulsive disorder (OCD). For this purpose, patients and controls are classified by using non-linear Least-Squares Support-Vector-Machine with 10-fold cross validation for both eight features in each sub-band and single ban-specific feature at each lobe. The best classification performance (87, 15% and 96, 65% in Beta and Gamma) is obtained for eight features estimated by using WC. In particular, single feature through WC has provided the relatively lower but useful classification performance in Beta (72, 34% at prefrontal, (72, 59% at occipital, 76, 39% at posterio-frontal, 70, 89% at anterio-temporal, 71, 14% at posterio-temporal) and Gamma (71, 84% at prefrontal, 76, 39% at occipital, 76, 39% at posterio-frontal, 70, 89% at anterio-temporal, 71, 77% at posterio-temporal). In detail, OCD is found to be characterized by low hemispheric dependency in Gamma over cortex. In conclusion, OCD causes abnormalities at almost every hemispheric lobe. WC provides the best estimations to compute band specific asymmetry levels due to non-linear and non-stationary nature of EEG.