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Publication Metadata only 1200 nm pumped Tm3+:Lu2O3 ceramic lasers(Optical Soc Amer, 2018) Özharar, Sarper; N/A; Department of Physics; Toker, Işınsu Baylam; Sennaroğlu, Alphan; PhD Student; Faculty Member; Department of Physics; N/A; College of Sciences; N/A; 23851We report on an experimental demonstration of a 1200-nm pumped Tm3+:Lu2O3 ceramic laser. By using a gain-switched, tunable Cr4+:forsterite laser, the excitation spectrum was measured, with optimum pumping bands centered near 1198 nm, 1204 nm, and 1211 nm. The highest slope efficiency of 21.5% was obtained at the pump wavelength of 1204 nm. Comparative energy efficiency measurements performed near 1200-nm and 800-nm pumping further showed that nearly 40% improvement was obtained in slope efficiency measured with respect to the incident pump energy for 1200-nm pumping. A transition was further observed from single-wavelength operation at 2066 nm to dual-wavelength operation near 2066 nm and 1967 nm for absorbed pump energies above 50 mu J. In this regime, two consecutive output pulses were observed in the time domain. The shortest temporal duration of the first pulse was 1.1 mu s at the incident pulse energy of 105 mu J. The duration and build-up time of the second pulse remained around 5.9 mu s and 18.5 mu s. We believe that the improved energy efficiency demonstrated for the 1.5% Tm3+:Lu2O3 ceramic with 1200-nm pumping can be used as an alternative scheme for the excitation of Tm3+:Lu2O3 ceramic lasers.Publication Metadata only A biallelic ANTXR1 variant expands the anthrax toxin receptor associated phenotype to tooth agenesis(Wiley, 2018) Dinckan, Nuriye; Du, Renqian; Akdemir, Zeynep C.; Bayram, Yavuz; Jhangiani, Shalini N.; Doddapaneni, Harsha; Hu, Jianhong; Muzny, Donna M.; Guven, Yeliz; Aktoren, Oya; Boerwinkle, Eric; Gibbs, Richard A.; Posey, Jennifer E.; Lupski, James R.; Uyguner, Zehra O.; Letra, Ariadne; N/A; Kayserili, Hülya; Faculty Member; School of Medicine; 7945Tooth development is regulated by multiple genetic pathways, which ultimately drive the complex interactions between the oral epithelium and mesenchyme. Disruptions at any time point during this process may lead to failure of tooth development, also known as tooth agenesis (TA). TA is a common craniofacial abnormality in humans and represents the failure to develop one or more permanent teeth. Many genes and potentially subtle variants in these genes contribute to the TA phenotype. We report the clinical and genetic impact of a rare homozygous ANTXR1 variant (c.1312C>T), identified by whole exome sequencing (WES), in a consanguineous Turkish family with TA. Mutations in ANTXR1 have been associated with GAPO (growth retardation, alopecia, pseudoanodontia, and optic atrophy) syndrome and infantile hemangioma, however no clinical characteristics associated with these conditions were observed in our study family. We detected the expression of Antxr1 in oral and dental tissues of developing mouse embryos, further supporting a role for this gene in tooth development. Our findings implicate ANTXR1 as a candidate gene for isolated TA, suggest the involvement of specific hypomorphic alleles, and expand the previously known ANTXR1-associated phenotypes.Publication Metadata only A case of drop foot due to piriformis syndrome(Springer Heidelberg, 2015) Yıldırım, Pelin; Güler, Tuba; Özer, Tülay; Gündüz, Osman Hakan; N/A; Mısırlıoğlu, Tuğçe Özekli; Doctor; N/A; Koç University Hospital; 175999N/APublication Open Access A clinical scoring system to predict the development of bronchopulmonary dysplasia(Thieme Medical Publishers, 2015) Hayran, Mutlu; Derin, Hatice; Ovalı, Fahri; N/A; Gürsoy, Tuğba; Faculty Member; School of Medicine; 214691Objective: This study aims to develop a scoring system for the prediction of bronchopulmonary dysplasia (BPD). Methods: Medical records of 652 infants whose gestational age and birth weight were below 32 weeks and 1,500g, respectively, and who survived beyond 28th postnatal day were reviewed retrospectively. Logistic regression methods were used to determine the clinical and demographic risk factors within the first 72 hours of life associated with BPD, as well as the weights of these factors on developing BPD. Predictive accuracy of the scoring system was tested prospectively at the same unit. ResultsBirth weight, gestational age, gender, presence of respiratory distress syndrome, patent ductus arteriosus, intraventricular hemorrhage, hypotension were the most important risk factors for BPD. Therefore, a scoring system (BPD-TM score) ranging from 0 to 13 and grouped in four tiers (0-3: low, 4-6: low intermediate, 7-9: high intermediate, and 10-13: high risk) was developed based on these factors. Below the score of 4, 4.1% of infants (18/436), above the score of 9, 100% (29/29) of the infants developed BPD. The score was validated successfully in 172 infants. Conclusion: With this easy to use scoring system, one can predict the neonate at risk for BPD at 72 hours of life and direct preventive measures toward these infants.Publication Metadata only A combined clinical and computational approach to understand the SOD1(A4T)-mediated pathogenesis of rapidly progressive familial amyotrophic lateral sclerosis(Springer Heidelberg, 2022) Diker, Sevda; Gelener, Pınar; Teralı, Kerem; Ergören, Mahmut Çerkez; Ersin, Tan; N/A; N/A; Tunca, Ceren; Başak, Ayşe Nazlı; Researcher; Faculty Member; Koç University Research Center for Translational Medicine (KUTTAM) / Koç Üniversitesi Translasyonel Tıp Araştırma Merkezi (KUTTAM); N/A; School of Medicine; N/A; 1512Here, we aim to provide a comprehensive clinical and biomolecular description of familial amyotrophic lateral sclerosis (fALS) in a 25-year-old female patient with respect to the SOD1(A4T) genotype. The clinical diagnosis of the disease was based on family history, neurological examination, electroneurophysiological studies, and revised El Escorial criteria. The heterozygous presence of the A4T mutation in the proband was confirmed by PCR coupled with Sanger sequencing of exon 1 of the SOD1 gene. The mutation was introduced in silico into the three-dimensional structure of the native protein. After energy minimization and quality assessment, non-covalent interactions around threonine-4 and changes in protein stability were calculated computationally. The patient differed widely in age at onset, initial neurological symptoms and findings, and survival time from her kindred, in which several members are affected. SOD1(A4T)-linked fALS in this case had bulbar involvement at onset, a combination of lower and upper motor neuron signs and showed rapid progression. Unlike alanine-4, threonine-4 failed to engage in hydrophobic interactions with the vicinal non-polar amino acids. The overall fold of the modeled SOD1(A4T) mutant remained intact, but unfolding free energy estimations disclosed a decrease in the protein's stability. We report a phenotypically distinct patient with fALS due to the SOD1(A4T) mutation and further expand the largest pedigree ever published for SOD1(A4T)-linked fALS. Genotype-phenotype correlation in fALS is complex, and it demands detailed clinical investigation and advanced scientific research. Awareness of the broadened phenotypic spectrum might potentially enhance the diagnosis and genetic counseling of fALS.Publication Open Access A combined VBM and DTI study of schizophrenia: bilateral decreased insula volume and cerebral white matter disintegrity corresponding to subinsular white matter projections unlinked to clinical symptomatology(Aves, 2017) Ulaşoğlu-Yıldız, Çiğdem; Aslan, Selçuk; Talı, Erhan Turgut; N/A; N/A; Onay, Aslıhan; Eser, Hale Yapıcı; Faculty Member; School of Medicine; N/A; 134359PURPOSE: Grey matter and white matter changes within the brain are well defined in schizophrenia. However, most studies focused on either grey matter changes or white matter integrity separately; only in limited number of studies these changes were interpreted in the same frame. In addition, the relationship of these findings with clinical variables is not clearly established. Here, we aimed to investigate the grey matter and white matter changes in schizophrenia patients and exhibit the relation of these imaging findings with clinical variables. METHODS: A total of 20 schizophrenia patients and 16 matched healthy controls underwent magnetic resonance imaging to investigate the grey matter and white matter alterations that occur in schizophrenia patients using voxel-based morphometry (VBM) and whole brain voxel-wise analysis of diffusion tensor imaging (DTI) parameters with SPM8, respectively. While the preprocessing steps ofVBM were performed with the default parameters of VBM8 toolbox, the preprocessing steps of DTI were carried out using FSL. Additionally, VBM results were correlated with clinical variables. RESULTS: Bilateral insula showed decreased grey matter volume in schizophrenia patients compared with healthy controls (P < 0.01). The opposite contrast did not show a significant difference. Psychiatric scores, duration of illness, and age were not correlated with the decreased grey matter volume of insula in schizophrenia patients. DTI analysis revealed a significant increase in mean, radial, and axial diffusivity, mainly of the fibers of bilateral anterior thalamic radiation and superior longitudinal fasciculus with left predominance, which intersected with bilateral subinsular white matter (P < 0.05). CONCLUSION: Our findings suggest that insula may be the main affected brain region in schizophrenia, which is also well supported by the literature. Our results were independent of disease duration and schizophrenia symptoms. White matter alterations were observed within bilateral anterior thalamic radiation and superior longitudinal fasciculus that intersects with subinsular white matter. Studies with larger sample sizes and more detailed clinical assessments are required to understand the function of insula in the neurobiology of schizophrenia.Publication Metadata only A communication theoretical modeling of axonal propagation in hippocampal pyramidal neurons(IEEE-Inst Electrical Electronics Engineers Inc, 2017) N/A; N/A; Department of Electrical and Electronics Engineering; Ramezani, Hamideh; Akan, Özgür Barış; PhD Student; Faculty Member; Department of Electrical and Electronics Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; 6647Understandingthe fundamentals of communication among neurons, known as neuro-spike communication, leads to reach bio-inspired nanoscale communication paradigms. In this paper, we focus on a part of neuro-spike communication, known as axonal transmission, and propose a realistic model for it. The shape of the spike during axonal transmission varies according to previously applied stimulations to the neuron, and these variations affect the amount of information communicated between neurons. Hence, to reach an accurate model for neuro-spike communication, the memory of axon and its effect on the axonal transmission should be considered, which are not studied in the existing literature. In this paper, we extract the important factors on the memory of axon and define memory states based on these factors. We also describe the transition among these states and the properties of axonal transmission in each of them. Finally, we demonstrate that the proposed model can follow changes in the axonal functionality properly by simulating the proposed model and reporting the root mean square error between simulation results and experimental data.Publication Metadata only A comparison of parenting dimensions between deaf and hearing children(Sage Publications Inc, 2016) Ekim, Ayfer; N/A; Ocakçı, Ayşe Ferda; Faculty Member; School of Nursing; 1729Effective parenting is vital for intellectual, physical, social, and emotional development of a child. This study examined the differences between the parenting dimensions of deaf children and healthy ones. The sample of the study consisted of 292 children and their parents (146 of them deaf children and 146 of them healthy ones). Dimensions of parenting (warmth, rejection, structure, chaos, autonomy, and coercion) were measured using the Parent as Social Context Questionnaire. The mean scores of the positive parenting dimensions of warmth and autonomy of deaf children were significantly lower; however, the mean scores of the negative dimensions of chaos and coercion of deaf children were significantly higher than those of healthy ones. Deaf children can become successful adults with the help of their parents. Our results regarding parenting dimensions will be a guide for future nursing interventions planned to develop the relationships between deaf children and their parents.Publication Metadata only A deformation-based approach to tuning of magnetic micromechanical resonators(2018) Yalçınkaya, Arda D.; Department of Mechanical Engineering; N/A; Department of Mechanical Engineering; Biçer, Mahmut; Esfahani, Mohammad Nasr; Alaca, Burhanettin Erdem; Researcher; PhD Student; Faculty Member; Department of Mechanical Engineering; Koç University Surface Science and Technology Center (KUYTAM) / Koç Üniversitesi Yüzey Teknolojileri Araştırmaları Merkezi (KUYTAM); College of Engineering; Graduate School of Sciences and Engineering; College of Engineering; N/A; N/A; 115108Resonance frequency tuning in magnetic micromechanical resonators remains a primary field of study for frequency reference applications. The use of magnetic micromechanical resonators for innovative timing, oscillator and sensing applications necessitates a platform for the precise control of the resonance frequency. The present work addresses a deformation based technique for tuning the resonance frequency of nickel micromechanical resonators. Frequency response is measured through magnetic actuation and optical readout. The tuning approach is based on a combination of flexural deformation and uniaxial strain. The bending deformation is achieved by using a DC current through the microbeam. This magnetomotive mechanism reduces the resonance frequency by about 13% for a maximum DC current of 80 mA. A substrate bending method is used for applying uniaxial strain to increase the resonance frequency by about 8%. A bidirectional frequency modulation is thus demonstrated by utilizing both deformation techniques. The interpretation of results is carried out by finite element analysis and electromechanical analogy in an equivalent circuit. Using deformation techniques, this study provides a rigorous approach to control the resonance frequency of magnetic micromechanical resonators.Publication Metadata only A dynamic model of an overhung rotor with ball bearings(Sage, 2011) Şanlıtürk, K. Y.; N/A; Çakmak, Onur; PhD Student; Graduate School of Sciences and Engineering; N/AA ball bearing comprising rolling elements, inner and outer rings, and a cage structure can be described as a multi-body system (MBS). In order to predict the dynamic behaviour and resonance characteristics of a rotor-ball bearing system, it can be modelled and analysed as a MBS with flexible and rigid parts. In this study, a ball bearing is modelled with MBS approach using MSC ADAMS commercial software. The Hertzian theory is used for modelling the contact dynamics between the balls and the rings. The ball bearing model is then assembled with the rotor model which comprised a shaft and a disc positioned at the free end of the shaft. The ball bearing model is used with both flexible and rigid shaft assumptions in order to highlight the differences between the two cases. For the flexible shaft case, the MBS model also included a finite element model of the shaft. As expected, it is necessary to include the flexibility of the shaft in the model in order to to predict the changes in the modal characteristics of the system as a function of the rotor speed. Furthermore, including the gyroscopic effects leads to observe the forward and backward travelling modes with different natural frequencies. The effects of the bearing diametral clearance and localized defects on the inner and outer rings are modelled and analysed using the model developed. Also, the effects of the rotor unbalance on the vibration level of the whole system are examined. A test rig - consisting of two ball bearings, a shaft, and a disc - is also designed and developed so as to validate the theoretical model using experimental data. Order tracking and modal analyses are carried out and Campbell diagrams are obtained. Finally, the theoretical and the experimental results are compared and a refined MBS model is obtained for further analyses.