1,019 research outputs found
Analysis of Pilot Distance Estimation in Different Lighting and Visibility Conditions
Several studies on distance and size estimation have focused on normal and night vision goggles (NVGs), but none of them have been performed during the twilight period. Hence, in this study, distance was estimated for the first time during nautical twilight. According to the findings, the accuracy of distance estimation reduces as visibility decreases and is restricted. When compared with Day Limited Helmet Mounted Display Vision (M = 5.27, SD = .59), Twilight Normal Vision (M = 5.33, SD = .69) and Twilight Helmet Mounted Display Vision (M = 5.20, SD = .61), NVG (M = 4.79, SD = .57) appears to have a lower error rate. In this study, distance was estimated considering objects determined during the helicopter flight by the pilots in different visibility conditions, which are significant in the field of aviation. This work is unique owing to its coverage of helicopter pilots and the estimation during the twilight period. In view of our findings, it may be reasonable to postpone the planned helicopter flights during poor visibility conditions
Role of Antioxidant Phytochemicals in Prevention, Formation and Treatment of Cancer
Reactive oxygen species (ROS) played an important role in cancer. Although low levels of ROS can be beneficial in normal physiological functions, chronic exposure to ROS is associated with increased risk of cancers. Increased ROS levels can also induce apoptosis and cell death in various types of cancer. Taken together, the role of ROS in cancer prevention, formation and therapy is extremely complex and very challenging to study. Although the antioxidant activity of phytochemicals is well recognized and generally used to prevent cancer, they can have pro-oxidant and ROS generating activities under certain conditions, especially at high doses or in the presence of metal ions. The basal redox levels of cancer cells are also different from those of normal cells. Therefore, higher levels of free form of metal ions and higher levels of endogenous ROS production in cancer cells sensitizes them to phytochemicals mediated pro-oxidant cytotoxicity. In conclusion, people tend to intake of antioxidant phytochemicals for the detrimental effects of ROS. However, excessive intake of phytochemicals could have cancer development or therapeutic potential by generating ROS. In this section, the role of phytochemicals in the prevention, development and removal of cancer has been discussed
Microstructural Characterization and Mechanical Properties of Volcanic Tuff (Malatya, Turkey) Used as Building Stone for the Restoring Cultural Heritage
Old stone buildings constitute a significant percentage of the residential buildings in many countries. These structures are highly vulnerable, and important losses in masonry structures occur even in moderate earthquakes. Therefore, safety evaluations of these structures have gained significant attention in recent years. In this study, the mechanical, physical and microstructural characteristics of tuff samples used in the old buildings were investigated in Battalgazi within the boundaries of Malatya Province during the Seljuk time. The characteristics of the building materials were examined in detail using in-situ and laboratory tests. Because adequate samples could not be obtained from the historical buildings, quarry areas with the same characteristics were identified. First, original building stone (OBS) used in construction was taken from fallen and unusable blocks. Then, the properties of the restoration building stones (RBS) brought from the quarries were investigated. The RBS samples were also examined using in the laboratory, and the mechanical and microstructural properties of the building components were determined. The dynamic and static moduli of elasticity were determined using ultrasonic pulse velocity and uniaxial compression test. The OBS and RBS samples yielded similar results after the microstructural analyses. Our results showed that the dynamic elastic modulus value was higher than the static elastic modulus value. The results revealed by both methods showed that the static and dynamic elastic moduli were closely linked. The OBS and RBS samples exhibited microlitic porphyritic and vesicular textures and nearly the same mineralogical and textural characteristics
D-DSC: Decoding Delay-based Distributed Source Coding for Internet of Sensing Things.
Spatial correlation between densely deployed sensor nodes in a wireless sensor network (WSN) can be exploited to reduce the power consumption through a proper source coding mechanism such as distributed source coding (DSC). In this paper, we propose the Decoding Delay-based Distributed Source Coding (D-DSC) to improve the energy efficiency of the classical DSC by employing the decoding delay concept which enables the use of the maximum correlated portion of sensor samples during the event estimation. In D-DSC, network is partitioned into clusters, where the clusterheads communicate their uncompressed samples carrying the side information, and the cluster members send their compressed samples. Sink performs joint decoding of the compressed and uncompressed samples and then reconstructs the event signal using the decoded sensor readings. Based on the observed degree of the correlation among sensor samples, the sink dynamically updates and broadcasts the varying compression rates back to the sensor nodes. Simulation results for the performance evaluation reveal that D-DSC can achieve reliable and energy-efficient event communication and estimation for practical signal detection/estimation applications having massive number of sensors towards the realization of Internet of Sensing Things (IoST)
Vibration Mitigation of Railway Bridge Using Magnetorheological Damper
The purpose of this study is to analyze the railway bridge vibrations and control their negative effects through semi-active magnetorheological (MR) damper. Dynamic analysis of a railway bridge subjected to the moving load is performed. The real structural parameters are used, and the six-axle train is simulated as moving loads. The railway bridge is modeled as Euler-Bernoulli beam theory, and it is discretized through Galerkin method. To mitigate the bridge vibrations, MR damper with a fuzzy logic-based controller (FLC) is positioned at the ends of the bridge. The simulations of the system are performed by MatLab software. Finally, the results are examined both in the time and frequency domains
Investigation on the Accuracy of Existing Qibla Directions of the Mosques from Different Periods: A Case Study in Çorum City, Turkey
The main goal of this study is to introduce two different approaches (i.e. based on spherical trigonometric formula and using sun qibla time) that can be used to determine the qibla directions of the existing mosques were oriented with sufficient accuracy according to Islamic criteria. In order to do this, eight mosques which were constructed in different periods, 14th, 16th, 17th and 21st centuries in Çorum City, Turkey, were handled. The existing qibla directions of each mosque were calculated with spherical trigonometric formula and compared with the precisely calculated real qibla directions. The existing qibla directions of the same mosques were once more compared with the real qibla directions which were determined by using the qibla time calculated based on the location and the time of the measurement. The results show that the qibla directions of the recently built mosques were oriented to Kâ’ba with higher accuracy while the earlier with more deviations. However, the results show that all the deviations were at acceptable levels in terms of Islamic criteria
Recent protectionism policies in G-8 countries
2008 yılı sonunda başlayan ve tüm dünyayı etkileyen küresel kriz sonrası ülkeler, 1929 yılında olduğu gibi kendilerini korumak için çeşitli politikalar yürürlüğe koymuşlardır. GATT sonrasında ülkeler ticareti kısıtlayıcı, korumacı davranışlara istediklerinde başvuramamışlardır. Anlaşma ülkelere belirli şartlarda korumacı politikaları kullanabilecekleri yönünde imkan sağlamıştır. Ülkeler de bu durumu göz önüne alarak daha çok görünmez engeller olarak tabir edilen ticareti açıktan, direk etkileyen önlemler değil de, tespit edilmesi güç ancak koruma anlamında etkili önlemler almışlardır. 2008 yılında yaklaşık 200 olan önlemler, 2010 yılında yaklaşık 1000, 2012 yılı sonunda 2200, 2015 yılı sonunda korumacı önlem sayısı yaklaşık 4800 olmuştur. 2016 yılına gelindiğinde geçen 8 yıla rağmen uygulanan önlemlerin 5100‟ün üzerinde olduğu değerlendirilmiştir. 2008 yılından günümüze kadar uygulanan 5100‟ün üzerinde önlemi uygulayan ilk beş ülke (Hindistan 510, Rusya 490, ABD 390, Arjantin 350, Brezilya 290) 2030 önlem uygulamıştır.G-8 ülkeleri tarafından uygulanan 200 üzeri korumacı önlemden etkilenen ülkelere bakıldığında; Kanada 228, Çin 544, Fransa 279, Almanya 301, Hindistan 211, Polonya 208, Kore 266, İspanya 212, Türkiye 208, Ukrayna 207, İngiltere 251, Amerika Birleşik Devletleri 278 önlemden zarar görmüştür. Bu önlemler aslında G-8 ülkelerinin kendi uyguladıkları korumacı önlemlerden yine kendilerinin etkilendiğini ortaya çıkarmaktadır.Following the global crisis started towards the end of 2008 and affected the whole world, the countries put various policies into action in order to protect themselves as in 1929. After GATT, the countries couldn‟t implement trade restricting, protectionist actions whenever they wanted. The agreement provided countries the opportunity of using protectionist policies under certain circumstances. Taking those situations into consideration, the countries took measures which were commonly described as invisible handicaps, and in terms of trade, not directly affecting measures but hard to identify and effective in protecting. The number of protectionist measures that were nearly 200 in 2008 increased to 1000 in 2010, to 2200 at the end of 2012, and to 4800 at the end of 2015. When it comes to 2016, it has been assessed that the measures taken have already been over 5100 when compared to the last 8 years. Among the countries that have taken over 5100 measures from 2008 till now, the first five countries (India 510, Russia 490, USA 390, Argentina 350, Brazil 290) have taken 2030 measures in total themselves. When looked at the countries that are affected from over 200 protectionist policies implemented by G-8 countries, Canada has been affected from 228, China from 544, France from 279, Germany from 301, India from 211, Poland from 208, Korea from 266, Spain from 212, Turkey from 208, Ukraine from 207, England from 251 and USA from 278
Endovascular treatment of aorto-iliac occlusive disease using the kissing balloon technique: mid-term follow-up
This study aimed to present our mid-term experience in the endovascular treatment of aortoiliac occlusive disease using the kissing balloon technique. Materials and Methods: This two-center, retrospective study included 36 patients (male, n=23; female, n=13; mean age 62.7±9.7 years) with an aortoiliac occlusive disease, who received intervention using the kissing balloon technique between January 2017 and December 2019. Results: Thirty-six patients with aortoiliac occlusive disease underwent percutaneous intervention. The procedure could not be continued in three patients because of technical failure. Hence, 33 patients were successfully treated using the kissing balloon technique. The technical success rate was 91.6% and the one year patency rate was 83.3%. Of the 33 patients, 3 underwent surgery because of stent occlusion. After 1-year follow-up, in all 30 patients, all the vessels and stents were patent and no re-stenosis, no occlusion and no procedure related morbidity and mortality occurred. Conclusion: The endovascular treatment of aortoiliac occlusive diseases with kissing balloon technique demonstrated high success and patency rates in appropriate cases. However, in some patients technical failure may occure and the procedure could not be completed. The use of newer recanalization devices, materials or techniques, enrollment of larger cohort and more than 1 year of follow-up may clarify the long-term results of the kissing balloon technique
The role of simple elbow dislocations in cubitus valgus development in children
We investigated the functional and radiological outcomes of conservatively treated simple traumatic elbow dislocations and subsequent incidence of cubitus valgus development in children. Eleven patients (one female, ten male; mean age 9.8 years, range seven to 12 years) who presented to our hospital with simple elbow dislocations and were conservatively treated between July 2008 and September 2010 were included in the study. All were posterolateral closed dislocations. None of the patients had accompanying elbow fractures. All patients had pre- and postoperative radiographic examinations. The carrying angle of the involved elbow was measured and compared to the contralateral non-injured elbow during follow-up. The incidence and severity of cubitus valgus development was assessed. The functional and clinical outcomes were evaluated using the Mayo Elbow Performance Scale. The mean monitoring period was 24.3 months (range 19-30 months). All patients had satisfactory good and excellent results (85-100 points; mean 96.8 points) according to the Mayo Elbow Performance Scale. The final average elbow flexion was 137A degrees (range, 130-145A degrees) and average extension was 8.6A degrees (range 0-20A degrees) with full supination and pronation in traumatic elbow. Four patients (36.4 %) had an average increase (cubitus valgus) of 14.5A degrees (10-20A degrees) in carrying angle compared to the other elbow. While isolated traumatic dislocation of the elbow is uncommon among children, it can be successfully treated by urgent closed reduction, proper fixation of the elbow and appropriate timely rehabilitation. However, it should be considered that some patients may develop cubitus valgus deformity in a later period. Therefore, each patient with a simple traumatic elbow dislocation should be followed, and the parents should be informed of the potential for any deformity development
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