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Adaptive diffusion priors for accelerated MRI reconstruction
No full textDeep MRI reconstruction is commonly performed with conditional models that de-alias undersampled acquisitions to recover images consistent with fully-sampled data. Since conditional models are trained with knowledge of the imaging operator, they can show poor generalization across variable operators. Unconditional models instead learn generative image priors decoupled from the operator to improve reliability against domain shifts related to the imaging operator. Recent diffusion models are particularly promising given their high sample fidelity. Nevertheless, inference with a static image prior can perform suboptimally. Here we propose the first adaptive diffusion prior for MRI reconstruction, AdaDiff, to improve performance and reliability against domain shifts. AdaDiff leverages an efficient diffusion prior trained via adversarial mapping over large reverse diffusion steps. A two-phase reconstruction is executed following training: a rapid-diffusion phase that produces an initial reconstruction with the trained prior, and an adaptation phase that further refines the result by updating the prior to minimize data-consistency loss. Demonstrations on multi-contrast brain MRI clearly indicate that AdaDiff outperforms competing conditional and unconditional methods under domain shifts, and achieves superior or on par within-domain performance.TUBITAK BIDEB scholarship; TUBITAK 1001 Research Grant [121E488]; TUBA GEBIP 2015 fellowship; BAGEP 2017 fellowshipThis study was supported in part by a TUBITAK BIDEB scholarship awarded to A. Gungor, by a TUBITAK BIDEB scholarship awarded to S. Ozturk, and by a TUBITAK 1001 Research Grant (121E488) , a TUBA GEBIP 2015 fellowship, and a BAGEP 2017 fellowship awarded to T. Cukur
Rıza Tevfik’in Felsefi Kimliği ve Tarih Felsefesi Hakkındaki Yaklaşımları
No full textOsmanlı düşünce tarihinin ele alındığı kayıtlar arasında Rıza Tevfik’in yazıları önemli yer tutar. Rıza Tevfik, felsefe, tarih, edebiyat, eğitim ve bürokrasinin de dahil oldu- ğu pek çok alanla meşgul olmuş, Osmanlı döneminde felsefenin ilk kurucularından sayılmıştır. Felsefi problemleri ortaya koyuş biçimi, yorumlaması ve kendine has üslubuyla döneminde iz bırakmıştır. Bu alanda belli bir sistem oluşturamamış bile olsa felsefeyi sevdirmeye çalışmış, orta öğretim programlarına felsefeyi ders olarak koydurmayı başarmıştır. Rıza Tevfik, modern Türk tarihinin ilk felsefe ders kitabını yazmış ve hem lisede hem de Darülfünunda felsefe okutmuştur. Tarih felsefesi ile de ilgilenen düşünür, tarihî kayıtların tutulmasındaki ilkelere işaret ederken, Osman- lı dönemi eserlerini de kesin bir dille eleştirmekten çekinmemiştir. Bu araştırmada, Rıza Tevfik’in tarih felsefesi üzerine görüşlerini ortaya konmaya çalışılmıştır. Bu amaçla, düşünürün Musavver Muhit Dergisinde “Tarih ve Felsefe-i Tarih Hakkında” başlıklı makalesi analiz edilmiştir. Araştırmadan elde edilecek sonuçların tarihçilik, tarih felsefesi alanı ve tarih öğretimine katkı sağlayacağı düşünülmektedir
Investigation of the Genotoxic Effects of the Analgesic Drugs Piroxicam and Tenoxicam in Human Lymphocytes
No full textAnalgesics are one of the most widely used drug groups in the world. Since the genotoxic and carcinogenic effects of some analgesic drugs have been detected, studies investigating these effects have increased. In this study, the genotoxic effects of the analgesic drugs Tenoxicam and Piroxicam were investigated in vitro in human peripheral lymphocytes by chromosomal aberrations (CAs) and micronucleus (MN) assays. In addition, mitotic index (MI) and nuclear division index (NDI) values were also determined. As a result, no difference in chromosomal abnormalities was observed in both 24 and 48 hours of Piroxicam treatment. Micronucleus frequency was increased at the three highest concentrations (0.94, 1.88 and 3.75 µg/mL) compared to the control. Piroxicam significantly decreased MI compared to both control and solvent control at concentrations of 1.88 and 3.75 µg/mL at all exposure times. Tenoxicam showed a statistically significant increase at the highest concentration (10 ?g/mL) compared to the control in the 24 h CA treatment. On the other hand, no effect was observed in 48-hour CA treatment. It was concluded that tenoxicam did not cause a toxic effect at any concentration except the highest concentration (10 ?g/mL) in the MN assay results. Mitotic index (MI) significantly decreased at concentrations of 1.25, 2.5, 5 and 10 ?g/mL. Nuclear division index (NDI) results did not change for both agents. In conclusion, both agents were found to be genotoxic only at high concentrations and the effect was weak. This study is pioneering as there have been no previous in vitro studies in human peripheral lymphocytes for both Piroxicam and Tenoxicam. These results need to be supported by different cell groups and in vivo assays
Assessment of the genotoxic effects of antihypertensive drug active ingredient indapamide in human lymphocytes
No full textHypertension is the most common cardiovascular disease and is also known as high blood pressure. The large majority of hypertensive patients need long-term administration of antihypertensive agents. Indapamide is an orally administered diuretic antihypertensive drug. The present work aimed to assess the possible genotoxic effects of indapamide using four different assays: chromosomal aberration (CA), sister chromatid exchange (SCE), micronucleus (MN), and comet. Lymphocytes from three different donors were exposed to 18.75, 37.50, 75.00, and 100.00 ?g/ml indapamide. Additionally, a negative, a positive (mitomycin C = MMC, 0.20 ?g/ml), and a solvent control (5.4 ?l/ml methanol) were also applied. As a result, it was seen that indapamide did not cause a significant change in CAs and MN frequencies compared to the control. It caused significant damage only at the highest concentration in the comet assay. Similarly, while it did not affect the number of SCEs in the 24-h treatment, it increased the SCE frequency at the two highest concentrations in the 48-h. Mitotic index (MI) decreased at almost all concentrations. Considering all these results, this study revealed that indapamide did not have a significant genotoxic effect in these conditions. To the best of our knowledge, this is the first investigation about the genotoxic effect of indapamide in human lymphocytes in vitro. © 2022 Informa UK Limited, trading as Taylor & Francis Group.05/2015–16This work was supported by the Gazi University Research Fund under Grant number 05/2015–16. Graphical abstract was created using BioRender App
Optimum Torque Distribution During Regenerative Braking in a Fully Electrical Vehicle via Dynamic Programming
No full text7th International Symposium on Multidisciplinary Studies and Innovative Technologies, ISMSIT 2023 -- 26 October 2023 through 28 October 2023 -- -- 194332In electric vehicles, it is important to maximize their regenerative braking performances for obtaining longer driving distances. In this study, for an electric vehicle having motors on the front and rear axles, an optimum torque distribution algorithm based on dynamic programming method is proposed for maximizing the regenerative braking energy. Electric motor limits, efficiency maps, battery model and braking force constraints given in the European regulations are considered in the proposed algorithm. The dynamic programming algorithm code and simulation studies for different braking scenarios are carried out via MATLAB. Simulation studies show that via the proposed torque distribution algorithm, significant improvements in the regenerated braking energy are obtained with respect to the fixed-rate torque distribution algorithm. © 2023 IEEE.Türkiye Bilimsel ve Teknolojik Araştırma Kurumu, TÜBİTAK: 122M994ACKNOWLEDGMENT The authors gratefully acknowledge support of the Turkish National Research Council (TUBITAK) under grant no: 122M994
Content-based medical image retrieval with opponent class adaptive margin loss
No full textThe increasing utilization of medical imaging technology with digital storage capabilities has facilitated the compilation of large-scale data repositories. Fast access to image samples with similar appearance to suspected cases in these repositories can help establish a consulting system for healthcare professionals, and improve diagnostic procedures while minimizing processing delays. However, manual querying of large repositories is labor intensive. Content-based image retrieval (CBIR) offers an automated solution based on quantitative assessment of image simi-larity based on image features in a latent space. Since conventional methods based on hand-crafted features typically show poor generalization performance, learning-based CBIR methods have received attention recently. A common framework in this domain involves classifier-guided models that are trained to detect different image classes. Similarity assessments are then per-formed on the features captured by the intermediate stages of the trained models. While classifier -guided methods are powerful in inter-class discrimination, they are suboptimally sensitive to within-class differences in image features. An alternative framework instead performs task -agnostic training to learn an embedding space that enforces the representational discriminabil-ity of images. Within this representational-learning framework, a powerful method is triplet-wise learning that addresses the deficiencies of point-wise and pair-wise learning in characterizing the similarity relationships between image classes. However, the traditional triplet loss enforces separation between only a subset of image samples within the triplet via a manually-set constant margin value, so it can lead to suboptimal segregation of opponent classes and limited general-ization performance. To address these limitations, we introduce a triplet-learning method for automated querying of medical image repositories based on a novel Opponent Class Adaptive Margin (OCAM) loss. To maintain optimally discriminative representations, OCAM considers relationships among all image pairs within the triplet and utilizes an adaptive margin value that is automatically selected per dataset and during the course of training iterations. CBIR performance of OCAM is compared against state-of-the-art loss functions for representational learning on three public databases (gastrointestinal disease, skin lesion, lung disease). On average, OCAM shows an mAP performance of 86.30% in the KVASIR dataset, 70.30% in the ISIC 2019 dataset, and 85.57% in the X-RAY dataset. Comprehensive experiments in each application domain demonstrate the superior performance of OCAM against competing triplet-wise methods at 1.52%, classifier -guided methods at 2.29%, and non-triplet representational-learning methods at 4.56%
On Curvatures of Semi-invariant Submanifolds of Lorentzian Para-Sasakian Manifolds
No full textA Lorentzian para-Sasakian (LP-Sasakian) space form is a kind of para-Sasakian manifold with constant φ− holomorphic sectional curvature. The presented paper is on the curvatures of semi-invariant submanifolds of an LP-Sasakian space form. Firstly, the definition of a semi-invariant submanifold of LP-Sasakian space form is given and an example is presented. Then, some important results on Ricci and scalar curvatures have been obtained by using the Gauss equation related to curvatures. Furthermore, by suffering from these results, the conditions of a distribution is being Einstein have been examined. Finally, semi-invariant products of Lorentzian para-Sasakian manifolds have been considered and an important inequality for the second fundamental form is proved. © MatDer
Village novel in the example of Three Novels: Bahtiyarlık, Karabibik, Küçük Paşa
No full text"Köy romanı" kavramı, roman türleri arasında her milletin edebiyat dünyası içinde farklı gelişim evreleri izleyen bir tür olarak edebiyat araştırmacılarının başlıca konuları arasındadır. Türk romanı içinde de kendi alanında müstakil bir tür olarak gelişme imkânı bulan "Köy romanı" edebiyatımıza 1950 yılından itibaren damga vurduğu görülmektedir. Özellikle 1950-80 yılları Türk romanının başlıca odak noktası olan köy romancılığının kökenine gelindiğinde Tanzimat dönemi eserlerinden Milli edebiyat dönemi eserlerine uzanan bir gelişim evresi izlediği gerçeği karşımıza çıkmaktadır. Tanzimat dönemi eserleri arasında sıkça yer almasa da "köy teması" Ahmet Mithat Efendi ve Nabizade Nazım'ın romanlarına konu olmuş, Milli edebiyat döneminde de roman mekânının İstanbul'dan Anadolu'ya taşınmasıyla Ebubekir Hazım Tepeyran'ın romanında kendine önemli bir yer edinmiştir. Bu bakımdan edebiyatımızda köy romanı denildiğinde akla gelen ilk eserler olan Bahtiyarlık, Karabibik ve Küçük Paşa, köy romanı serüvenimizin başlangıç noktalarıdır. Kendi içlerinde köy kavramına oldukça farklı yönlerden yaklaşan bu eserler, köy romanının oluşmasında oldukça önemli bir zemin hazırlamakla yetinmeyip Türk köylüsünün yaşayışını, dünyaya bakışını ve köylülerin sorunlarını edebiyat dünyasında dile getirilmesinde önemli rol oynamışlardır. Çalışmamız bir tür olarak "köy romanının" edebiyat tarihimiz açısından gelişimini Bahtiyarlık, Karabibik ve Küçük Paşa romanları örneğinde ele almakta, romanları köy romanı açısından incelemektedir.The concept of "village novel" is among the main topics of literary researchers as a genre that follows different stages of development in the literary world of each nation among the novel genres. It is seen that the "Village novel", which has the opportunity to develop as an seperate genre in Turkish novel, has left its mark on our literature for certain periods.Especially when it comes to the origin of the village novel, which was the primary focus of the Turkish novel between the years 1950-80, we encounter the fact that it followed a developmental stage from the works of the Tanzimat (Reorganization) period to the works of the National literature period. Although it is not constantly included in the works of the Tanzimat period, the "village theme" has been the topic of the novels of Ahmet Mithat Efendi and Nabizade Nazım, in the period of National literature with the movement of the novel from Istanbul to Anatolia it has gained an important place in Ebubekir Hazım Tepeyran's novel. In this respect when village novels are mentioned in our literature the first works that come to mind; Bahtiyarlık, Karabibik and Küçük Paşa are the starting points of our village novel adventure. These works, which approach the concept of village from quite different aspects in themselves, not only prepare a very important ground for the formation of the village novel, but also had played an important role in expressing the living, their view of the world and the problems of the Turkish peasant, in the world of literature. Our study deals with the development of the "village novel" as a genre in terms of our literary history, in the example of Bahtiyarlık, Karabibik and Küçük Paşa novels, and examines the novels in terms of village novels
A preliminary research regarding the role of price and promotion on customers’ restaurant selections in Muscat/Oman
No full textThis study aimed to examine the customer selection of restaurants in Muscat based on the effectiveness of the prices and promotions. Besides, this study focused on the factors affecting the customer's selection of restaurants. The survey questionnaire was applied to a sample of customers living in Muscat. A convenient sampling technique was adopted for data collection, and the collected data was processed and analysed using Mini-tab software. The findings indicate that the menu price affects restaurant customers’ selection, and restaurants with a high price have better service. As for promotion, the most effective method to advertise is through social media. In addition, the most important factors for Omani people that affect their restaurant selections are tasty food, food quality, cleanliness, quick service, price and value, and sales promotion and discounts, respectively. The current study is preliminary in nature but an unstudied one from the price and promotion approach in Muscat, so it makes an addition to the hospitality literature and sheds light on future studies. The study also provides recommendations for practitioners