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    Breastfeeding does not protect against the development of carditis in children with acute rheumatic fever
    (Cambridge Univ Press, 2022) Gurbuz, Funda; Sahiner, Nejla Canbulat; Unal, Emin; Gurbuz, Ahmet Seyfeddin; Baysal, Tamer
    Introduction: Acute rheumatic fever is an autoimmune disease that develops due to streptococcal infection. The positive effect of breastfeeding on the development of the child's immune system is well documented. In this study, we aimed to investigate the effect of breast milk intake period on the development of carditis. Materials and methods: Patients (n: 182) who were diagnosed with acute rheumatic fever between 2010 and 2019 were enrolled in the study. The patients were divided into groups according to carditis development. The demographic, socio-economic, and breastfeeding data were compared between groups. Results: The mean age of the patients was 10.5 +/- 3.4, and 43.4 % (n: 79) of them were female. Independent predictors of the development of carditis in the first acute rheumatic fever episode were the number of children at home (OR: 1.773, CI 95%: 1.105, 2.845; p: 0.018) and breast milk intake less than 6 months (OR: 0.404, CI 95%: 0.174, 0.934; p: 0.034). Independent predictors of the development of carditis in any of the acute rheumatic fever episodes were the number of children at home (OR: 1.858, CI 95%: 1.100, 3.137; p: 0.021) and female gender (OR: 3.504, CI 95%: 1.227, 10.008; p: 0.019). The only independently predictor of the development of chorea during acute rheumatic fever was female gender (OR: 3.801, CI 95%: 1.463, 9.874; p: 0.006). Conclusion: Although the occurrence of carditis is less common during the first acute rheumatic fever attack in patients with breast milk intake less than six months, this advantage is lost in recurrent attacks. This study showed that breast milk does not have a negative effect on acute rheumatic fever carditis.
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    A programmable digital metasurface structure designed using ANN technique
    (Taylor & Francis Ltd, 2023) Altintarla, Gizem; Unal, Emin; Altintas, Olcay; Gencoglan, Duygu N.; Colak, Sule; Nazeri, Amir H.; Alkurt, Fatih Ozkan
    In this paper, an 8-bit programmable digital metasurface is designed in the operating frequency range from 4 to 7 GHz. A monopole antenna operating at 5 GHz is characterised by using a metasurface structure as the ground plane. Various combinations of the metasurface structure are examined by altering the state of each unit-cell between `ON (1)' and `OFF (0)' in the coding matrix. The purpose of the 8-bit programmable digital metasurface is to control the electromagnetic wave effectively in the frequency range of interest. Dynamically controllable metasurface structure is utilised to change the unit cells' configurations. In addition, the proposed adjustable metasurface is capable to control the monopole antenna directivity, gain and main lobe magnitude, efficiently. According to various via conditions, different metasurface-based antenna parameters such as return loss (S11), radiation pattern, directivity and surface current distribution are investigated by means of the commercial numerical simulation software, CST microwave studio. Employing the simulation results of the metasurface-based antennas, the artificial neural network (ANN) data set is obtained. 128 activation conditions are trained and tested by Levenberg Marquart learning algorithm. During the ANN procedure, MATLAB is used to obtain accurate results by changing the rate of test and training data set.
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    Radiation pattern reconfigurable cubical antenna array for 2.45 GHz wireless communication applications
    (Springer, 2023) Alkurt, Fatih Ozkan; Unal, Emin; Palandoken, Merih; Abdulkarim, Yadgar, I; Hasar, Ugur Cem; Karaaslan, Muharrem
    In this paper a single-fed four-faced multidirectional compact antenna is introduced for 2.45 GHz indoor wireless applications. Firstly, a slotted patch antenna is designed to operate at 2.45 GHz and its equivalent circuit model is synthesized, and then 2 x 1 patch antenna arrays are modelled and placed over the four faces of a cube structure and the final cube antenna is called as 4 x 2 x 1 antenna array. Meanwhile, a 50 omega fed line is positioned at the bottom of this cube with a power dividing network for the feeding line. For this purpose, a T-junction power divider network is designed at the bottom layer of the cube structure. Besides, the RF switches are located at each arm of four faces to transfer microwave energy selectively to each individual antenna element. Therefore, the reflection and radiation characteristics of proposed compact antenna are analysed to improve the performance under various switching conditions by the numerical analysis. The possibility of controlling selective radiation in a given direction is confirmed. The main advantage of the proposed design is to have capability of radiation control while preserving the reflection coefficient stability by RF switches. Finally, the proposed compact antenna is fabricated using a conventional printed circuit technology and the radiation performance is tested by the experimental measurements conducted. It is observed that measurement results are in a good agreement with the numerical computation results.
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    A study on electronically controllable beamforming monopole antenna for telecommunication applications
    (Taylor & Francis Ltd, 2023) Alkurt, Fatih Ozkan; Unal, Emin; Palandoken, Merih; Altintarla, Gizem; Abdulkarim, Yadgar I.; Hasar, Ugur Cem; Karaaslan, Muharrem
    The design, analysis, and prototyping of an electronically controllable beamforming monopole antenna (ECBMA), which could be a good candidate for ceil-mounted wireless telecommunication systems, are reported. The proposed ECBMA targeting the 2.45 GHz center frequency is based on the 'on-off' ground reflectors, which are connected to the main ground layer by twelve RF switches to implement digital logic states. There are twelve ground reflectors symmetrically positioned over azimuthal angle direction in the ECBMA structure controlled by RF switches and a microcontroller unit, thus resulting in a pattern change when the states of the switches change logically. The designed ECBMA has the following three main features. First, it has a good and stable reflection coefficient (S11) characteristic at the 2.45 GHz centre frequency. Second, it has a wideband characteristic between 2.15 and 2.85 GHz (700 MHz operational bandwidth). Third, it has the capability to create single, double, or multi-beam characteristics (multi-purpose) which is a highly desired feature in many modern wireless communication systems mainly suitable for indoor applications. The prototype of our ECBMA is fabricated, and the performance analysis is investigated experimentally and S11 and radiation characteristics have good performance and are in good agreement with the simulation results. The proposed ECBMA has a good candidate for wireless telecommunication purposes such as WLAN, ISM, Wi-Fi, Bluetooth and other RF peripherals like indoor applications.