Approximate Computation of DFT without Performing Any Multiplications: Applications to Radar Signal Processing

In many practical problems it is not necessary to compute the DFT in a perfect manner including some radar problems. In this article a new multiplication free algorithm for approximate computation of the DFT is introduced. All multiplications $(a\times b)$ in DFT are replaced by an operator which computes $sign(a\times b)(|a|+|b|)$. The new transform is especially useful when the signal processing algorithm requires correlations. Ambiguity function in radar signal processing requires high number of multiplications to compute the correlations. This new additive operator is used to decrease the number of multiplications. Simulation examples involving passive radars are presented

The Surgical Management of Hydatid Cyst of the Liver: What is New?

Liver hydatid cyst is a disease of zoonosis caused by Echinococcus granulosus or less frequently by Echinococcus multilocularis and Echinococcus oligarthrus. The primary carriers are canines, while human beings are secondary hosts. Early diagnosis is important for cysts not to become complicated and for the treatment not to get difficult. The most effective treatment of uncomplicated hydatid cyst is to reduce the dead space of the cavity and to discharge the fluid as much as possible. However, if the cysts get complex, there is no standard treatment management defined other than offered management options by authors. In complex conditions, the treatment is determined according to the stage of the cyst and the relation of the cyst with biliary ducts or surrounding organs. In this chapter, the treatment regimens of liver hydatid disease mainly based on interventions and surgical operations are going to take a part

NOKTA DİRENÇ KAYNAK ELEKTROTLARINA TiC-Co KAPLAMANIN ETKİSİ

Nokta direnç kaynak yöntemi otomotiv endüstrisinde yaygın olarak kullanılmaktadır. Diğer kaynak yöntemlerine göre oldukça hızlı, ekonomik, güvenilir bir yöntemdir. Kaynak işlemi sırasında elektrotların iş parçalarına temas eden yüzeyinde lokal olarak yüksek sıcaklıklara çıkılmaktadır ve kaynak çevrimi boyunca da elektrotlar iş parçalarına belli bir basınç uygularlar. Basınç ve sıcaklık elektrot yüzeyinde deformasyon oluşturur. Nokta direnç kaynağında kullanılan Cu-Cr-Zr elektrotların ömürlerini uzatmak için kaplama işlemi uygulanmaktadır. Bu çalışmada, elektrotların uç yüzeylerine TiC-Co malzeme elektrospark yöntemiyle farklı kaplama parametrelerinde kaplanmış, böylece kaplamanın DP600 çelik saç çifti birleştirmesi özelliklerine etkisi araştırılmıştır

Co-existence of cecal volvulus with situs inversus totalis: A case report

AbstractDetorsion, cecopexy, cecostomy and tube cecostomy are the treatment options for acute cecal volvulus if there is no intestinal ischemia. Resection required if intestinal viability, necrosis, gangrene or perforation exists. After resection, primary anastomosis or ileostomy can be performed. First colonoscopic decompression testing may be appropriate in terms of saving time for elective surgery. The co-existance of situs inversus totalis with cecal volvulus may cause uncertainty of the definite diagnosis and delay of surgical procedure. This is a case report about cecal volvulus together with situs inversus totalis

Bioaggregate ile kapatılan kök ucu dolgularının kalınlığının apikal sızdırmazlığa etkisi

Objectives: The purpose of this study was to compare the ability of different cavity thickness of Bioaggragate to prevent microleakage using computerized fluid filtration method. Materials and Methods: Fifty single- rooted human teeth were selected for this study. The root canals were prepared with Ni-Ti rotary files with 5% Sodium hypocloride (NaOCl) solution as the irrigant. Then sealed with gutta-percha points(DiaDent®GuttaPercha Points, Seul, SouthCorea) and AH Plus (Dentsply Maillefer, Ballaigues, İsviçre). After root end resection, fifty theeth were randomly selected into 1 of 4 test groups containing 10 teeth each, and positive and negative control groups containing 5 teeth each. Group 1: 1mm, Group 2: 2mm, Group 3: 3mm, Group 4: 6mm cavity thickness. And then all prepared root-end cavities filled with Bioaggregate. Leakage was evaluated using with a computarized fluid filtration model. Results: Statistical analysis showed that group 1 leaked more than all other groups (p<0.001). There was a significant difference between group 1 and group 3(p<0.001),and also there was a significant difference between group 2 and group 3. In contrast there was no significant difference between group 3 and group 4 (p>0.001). Conclusions: According to this study, the thickness of root end cavity must be minimum 3 mm and more when Bioaggregate root end filling material is used. Keywords: Apical leakage, root end filling material, ceramics. ÖZET Amaç: Bu çalışmanın amacı, Bioaggregate’in farklı kalınlıklarda uygulayarak sızıntı miktarlarını bilgisayarlı sıvı filtrasyon yöntemiyle sızıntı miktarlarını belirlemektir. Gereç ve Yöntem: Bu çalışma için 50 adet tek köklü insan dişi seçildi. Kök kanalları Ni-Ti aletler yardımıyla şekillendirildi, irrigasyon ajanı olarak %5 Sodyum hipoklorit (NaOCl) solüsyonu kullanıldı. Daha sonra guta perka ve AH plus kanal patı ile dolduruldu. Kök ucu rezeksiyonunu ardından dişler her biri 10 örnek içeren 4 deney grubuna, her biri 5 örnek içeren pozitif ve negatif kontrol gruplarına ayrıldı. Kök ucu kavite derinlikleri sırasıyla; Grup 1: 1mm, Grup 2: 2mm, Grup 3: 3mm, Grup 4: 6mm. Kök ucu kaviteleri irrige edildi ve kurulandı. Sonrasında bütün kök ucu kaviteleri Bioaggregate ile dolduruldu. Sızıntı miktarı, bilgisayarlı sıvı filtrasyon modeli kullanılarak belirlendi. Bulgular: Pozitif kontrol grubunda yüksek balon hareketi gözlendi. Negatif kontrol grubunda ise herhangi bir hareket gözlenmedi. İstatistiksel analiz sonuçlarına göre; grup 1 diğer tüm gruplardan daha fazla sızıntı gösterdi (p<0.001). Grup 1 ile grup 3 arasında istatistiksel fark bulunmazken, grup 2 ile grup 3 arasındaki fark ise istatistiksel olarak anlamsız bulundu. Ayrıca, grup 3 ve grup 4 arasında da istatistiksel olarak fark bulunamadı (p>0.001). Sonuç: Bu çalışmaya göre Bioaggregate kök ucu dolgu materyali kullanıldığında, kök ucu kavitesi kalınlığı minimum 3mm ve üstü olmalıdır

Factors associated with acetabular degeneration and protrusion in bipolar hip hemiarthroplasty

Purpose This study aims to investigate the effect of some factors such as the diameter of bipolar prosthetic heads, body mass index (BMI), age, gender, bone mineral density (BMD) and leg length discrepancy (LLD) on the acetabular protrusion in elderly patients who had hip bipolar hemiarthroplasty (BHA) after femoral neck fractures. Methods The study included a total of 209 patients with a mean age of 77.4 ± 6.0 years who underwent BHA. The difference between the femoral head diameter of the patients and the diameter of the bipolar prosthetic head was divided into two groups, ranging from 0 to -2 mm (same and 1,2 mm small size) . Acetabular enlargement and cartilage degeneration were followed by standard AP pelvis radiographs and clinical outcomes were evaluated by the Harris Hip Score (HHS) after surgery and during 5 years of follow-up. Results During the 5-year follow-up, while HHS values decreased, acetabular diameter increased. Acetabular protrusion developed in 21 (10%) patients, acetabular revision surgery was performed for 36 (17%) patients, the difference between native femoral head diameter and prosthetic head diameter was significantly higher in these groups, as was mean LLD (p = 0.0001). Mean T scores obtained with BMD were lower in these groups (p = 0.0001). Conclusion It is safer and more reliable to use a bipolar prosthetic head the same size as the patient’s native femoral head in BHA. When considering the acetabular protrusion and revision surgery rate in this study, small-size bipolar prosthetic head implantation is not recommended and may cause devastating complications

The effect of anesthesia type on stress hormone response: Comparison of general versus epidural anesthesia

Aim: The aim of this study was to investigate the effect of different types of anesthesia on stress hormones.Materials and Methods: The study was included 60 ASAI-II cases scheduled for major lower extremity surgery. The cases were randomized into 2  groups: The EA group was administered epidural anesthesia and the GA group was administered standard general anesthesia. In order to evaluate the surgical trauma - related stress response, CRP, TSH, cortisol, and fasting blood sugar(FBS) levels were measured preoperatively, 30 min after surgical incision, and 24 h post surgery.Results: Between-group comparisons; Preoperative values were not  significantly different between the groups.(P > 0,05) Pulse rate and cortisol values significantly higher in general group at 30 min. (P < 0,05), and the FBS values were significantly higher in the epidural group at 24 h.(P < 0,05) There were not found differences for other parameters at evaluation times.Conclusion: No differences were observed between the two anesthesia methods, in terms of minimizing the stress response due to surgical trauma during major low extremity surgery.Key words: Epidural anesthesia, general anesthesia, stress hormone

Electrically conductive high–performance thermoplastic filaments for fused filament fabrication

Conductive polyetherimide (PEI)-based filaments can fill the gap between the design and manufacturing of functional and structural components through additive manufacturing. This study systematically describes the fabrication of carbon nanotube (CNTs)-reinforced PEI filaments, complemented by a custom-built extrusion process facilitating low weight fraction of nanomaterials. Neat PEI and CNTs/PEI filaments at different CNTs fractions ranging from 0.1 to 7 wt. % were fabricated. Supported by morphology analysis, the rheological percolation was found to be higher (0.25 wt. % CNTs/PEI) than electrical percolation (0.1 wt. % CNTs/PEI) since the system reached an electrical percolation within the formation of a continuous conductive path at lower CNTs loadings. With the 7 wt. % CNTs loading, the highest electrical conductivity of CNTs/PEI filaments was reported as 2.57 × 10−1 S/cm. A 55% enhancement in tensile modulus was achieved when 5 wt. % CNTs were introduced, but in a trade-off in elongation at break ca. 65%

Research Tendencies in the Discipline of Distance Education (2015-2022): Examination of Doctoral Theses in Higher Education in Turkey

The discipline of distance education is evolving and becoming mainstream, and this view requires examining research tendencies in the field. Motivated by this justification, it can be argued that understanding distance education to the fullest extent is possible partially through examining changes in theory and practice, as research conducted in the field reflects changes, dynamics, and perspectives. In this regard, the purpose of this paper is to present the research tendencies in doctoral theses in the Turkish higher education context with a specific focus on distance education. In line with this aim, a total of 265 doctoral theses published between 2015 and 2022 were examined through data mining and analytics approaches. The analysis of the titles through t-SNE analysis revealed four broad themes. These are: (1) more emphasis on learning processes; (2) the comparison of online technologies and online learning spaces; (3) a strong focus on educational technologies; and (4) the limitations emerging from comparative studies. The examination of the abstracts through text-mining identified the following themes: (1) the methodological vicious circle, the pursuit of methodological perfection, and lack of critical perspectives; (2) the tendency to use online [educational] technologies; (3) the comparison of distance and face-to-face education; and (4) the design of social interaction and communication in distance education processes. Finally, the analysis of the keywords through word clouds surfaced the following research tendencies: (1) Technology-supported distance education processes; (2) the wide use of educational technologies; (3) focusing on issues related to the learners in distance education. The paper concludes with implications and recommendations for future research directions

Is Placing Prophylactic Dural Tenting Sutures a Dogma?

Objective In this study, we investigated if and when dural tenting sutures are necessary during craniotomy. Methods Results from 437 patients aged 18 to 91 years (average, 43.5 years) who underwent supratentorial craniotomy between 2014 and 2019 were evaluated. The patients were categorized into 1 of 3 groups, patients who had at least 3 prophylactic dural tenting sutures placed before opening of the dura (group 1), at least 3 dural tenting sutures placed after surgery was completed, during closure (group 2), or no dural tenting sutures (group 3 [control]). All such sutures in groups 1 and 2 were placed in the circumference of the craniotomy and dural junction. No central dural tenting sutures were placed in any of the patients. Results Among the 437 patients, 344 underwent surgery for the first time and 93 were undergoing a second surgery. Cranial computed tomography imaging was performed for each patient 1 hour, 3 days, and 1 month after surgery. In group 1, 3 patients had a cerebral cortex contusion and 2 patients had acute subdural hematoma after the sutures were placed. In groups 2 and 3, none of the patients had a cerebral cortex contusion or acute subdural hematoma. Fewer complications were observed when dural tenting sutures were placed during postsurgical closure. Conclusion Placing dural tenting sutures is an important technique for ensuring hemostasis. However, when not needed, they seem to cause inadvertent complications. As our results suggest, knowing when and where to use them is equally important