Approximate solutions for nonlinear oscillation of a mass attached to a stretched elastic wire

AbstractIn this paper, the approximate solutions of the mathematical model of a mass attached to a stretched elastic wire are presented. At the beginning of the study, the equation of motion is derived in a detailed way. He’s max–min approach, He’s frequency–amplitude method and the parameter-expansion method are implemented to solve the established model. The numerical results are further compared with the approximate analytical solutions for both a small and large amplitude of oscillations, and a very good agreement is observed. The relative errors are computed to illustrate the strength of agreement between the numerical and approximate analytical results

High-Order Energy Balance Method to Nonlinear Oscillators

Energy balance method (EBM) is extended for high-order nonlinear oscillators. To illustrate the effectiveness of the method, a cubic-quintic Duffing oscillator was chosen. The maximum relative errors of the frequencies of the oscillator read 1.25% and 0.6% for the first- and second-order approximation, respectively. The third-order approximation has an accuracy as high as 0.008%. Excellent agreement of the approximated frequencies and periodic solutions with the exact ones is demonstrated for several values of parameters of the oscillator

Kersetinin Ratlarda, Yanık Staz Bölgesi Üzerindeki Etkisi

Yanık tedavisinde esas amaç hasarlanan doku miktarının minimal seviyede tutmaktır. Yanık alanın genişlik ve derinliğinin miktarı hastaların mortalite ve morbiditesini belirleyen temel faktördür. Staz zonu olarak tanımlanan ve koagulasyon alanını çevreleyen alan yanık sonrası oluşacak nekrozun derinlik ve genişliğini belirleyen kritik bölgedir. Birçok ajan staz zonundaki dokularının korunması için denenmiştir. Bu deneysel çalışmada birçok değişik doku üzerinde antioksidan, antiinflamatuar ve antiapoptotik etkisi olduğu bilen kersetinin yanık staz zonu üzerindeki etkisi incelenmektedir. Çalışmada kersetin tedavisi yapılmayan, akut(yanık sonrası tedaviye başlanan) kersetin tedavisi yapılan ve kronik(yanık öncesi tedaviye başlanan) kersetin tedavisi yapılan gruplar karşılaştırıldı. Tedavi sonrası yanık yarası genişliği planimetrik ve sintigrafik olarak değerlendirildi. Ek olarak doku örnekleri alınarak malondialdehyde(MDA), myeloperoksidaz(MPO) ve nitrotirozin seviyeleri, kersetinin antiinflamatuar ve antioksidan etkisinin gösterilmesi için ölçüldü ve doku örneklerinde apoptoz ve otofaji seviyesi belirlendi. Kersetin ile tedavi edilen gruplarda nekroz miktarının ve apoptozun kontrole göre istatistiksel olarak anlamlı olacak şekilde daha az olduğu, otofajinin de kontrol grubunda, kersetin ile tedavi edilen gruplara göre istatistiksel olarak anlamlı olacak şekilde daha fazla olduğu görüldü. MDA,MPO and nitrotirozin ölçüm değerlerini bakımında gruplar arasında istatistiksel olarak anlamlı olacak şekilde bir fark tespit edilmedi. Sonuç olarak bu çalışma da kersetinin staz zonu üzerinde koruyucu etkisi olduğunu göstermiştir.Keeping the amount of damaged tissue at a minimum is one of the primary goals of treatment in burns. The width and depth of the burned area is at the top of the factors affecting mortality and morbidity in patients.The zone of stasis, the encircling area of the zone of coagulation, is a critical area which determines the depth and width of the necrosis in burns. Many agents were proposed to salvage the zone of stasis. Due to the known antioxidant, antiinflammatory and antiapoptotic effects of quercetin on multiple tissue, the effect of quercetin on saving the zone of stasis was investigated in this experimental study. No quercetin treatment, acute (treatment started after burn injury) quercetin treatment and chronic(treatment started before burn injury) quercetin treatment was compared in a rat comb-burn model. The extent of burn wounds was evaluated by planimetry and scintigraphy in the groups. Additionally, skin samples were obtained to analyze malondialdehyde (MDA), myeloperoxidase (MPO), nitrotyrosine to see antiinflamatuary and antioxidant effect of quercetin and apoptosis and autophagy levels were evaluate. Necrosis rate and apoptosis were statisticaly significant lower in quercetin treatment groups and autophagy level were statisticaly significant lower in control group. There were no difference between the groups in terms of MDA,MPO and nitrotyrosine concentrations. In conclusion, this study showed us the possible saving effect of quercetin on the zone of stasis

The hemostatic effect of calcium alginate in experimental splenic injury model

Ankarali, Seyit/0000-0003-3752-0846WOS: 000319368700002PubMed: 23720104BACKGROUND We evaluated the effect of calcium alginate as a hemostatic agent in a splenic injury model. METHODS Experimental rats (Wistar albino) were divided into four groups. Group I: Laparotomy was not performed. Group II: After laparotomy, the abdomen was closed without any splenic injury. Group III: After laparotomy, splenic injury about 0.5 cm in depth and 0.3 cm in length was created by standard Rochester pean forceps. Physiological serum treated gauze dressing, about 2x2 cm in size, was applied to the injured splenic tissue for 3 minutes. Group IV: After laparotomy, standard splenic injury about 0.5 cm in length and 0.3 cm in depth was created. Calcium alginate wound dressing, 1x1 cm in size, was applied to the splenic wound. In all groups, blood samples for bleeding time and hemogram were taken. Peroperative blood loss, pre- and post-operative hemoglobin and hematocrit values were calculated. RESULTS Comparing hematocrit values and peroperative bleeding in Groups III and IV, Group IV had a lower decline in hematocrit values and lower peroperative bleeding. CONCLUSION Calcium alginate has hemostatic capacity. It may be used in splenic injuries, especially for Grades I and II

Assessment of Red Cell Distribution Width (RDW) in Patients With Coronary Artery Ectasia

Objectives: Coronary artery ectasia (CAE) is characterized by an abnormal dilatation of the coronary arteries. Red cell distribution width (RDW) is a measure of heterogeneity in the size of red blood cell. In this study, we aimed to investigate RDW levels in patients with CAE. Methods: The study population included 54 patients with CAE (28 males; mean age, 59 +/- 12) and 40 individuals comprising the control group who had normal coronary arteries (17 males; mean age, 56 +/- 10). Admission RDW was measured as part of the automated complete blood count. Results: The RDW was significantly higher in the CAE group than the control (P < .001). Also, high-sensitive C-reactive protein (hs-CRP) levels in patients with CAE were significantly higher as compared with controls (P < .001). Conclusion: This study demonstrates that RDW and hs-CRP were higher in the CAE group compared with the control group. These results show that RDW is a reliable, simple, and inexpensive marker for patients with CAE

Changes in the Expression of c-fos and AQP4 in the Hippocampus and Amygdala Regions of Rats with Kainic Acid-Induced Temporal Lobe Epilepsy and Their Role in the Pathogenesis of Disease

Objective: Aquaporin4 is the main water channel in the brain that is associated with neurological disorders. The role and the expressive changes of aquaporin4 in epilepsy are still limited and controversial. The study aims to evaluate the expression of c-fos and aquaporin4 during epileptogenesis after systemic kainic acid-induced status epilepticus in the temporal lobe epilepsy animal model and to investigate their alterations in both hippocampus and amygdala. Methods:Intraperitoneal injections of kainic acid (5-15 mg/kg) by repeated low kainic acid protocol were given to young adult 32 Wistar albino rats for status epilepticus. Aquaporin4 and c-fos were investigated in the hippocampus and amygdala on days 1 and 60 after status epilepticus by immunostaining methods in brain slices.Results:The intensity of c-fos immunostaining rose considerably in the hippocampus CA1 area of rats during the acute period (P < 0.05) and in the amygdala during the chronic period. The immunostaining intensity of aquaporin4in the hippocampus of rats with acute kainic acid increased significantly (P < .05). It was also raised in the hippocampal region of the rats in the acute sham and chronic kainic acid groups.Discussion:The results of this study support a link between aquaporin4 and epilepsy. It can be speculated that aquaporin4 change is primarily a defense mechanism immediately after status epilepticus, and then, it can evolve into a causal factor with exhaustion as a result of overuse