Lefschetz fibrations on compact Stein surfaces

The existence of a positive allowable Lefschetz fibration on a compact Stein surface with boundary was established by Loi and Piergallini by using branched covering techniques. Here we give an alternative simple proof of this fact and construct explicitly the vanishing cycles of the Lefschetz fibration, obtaining a direct identification of the set of compact Stein manifolds with positive allowable Lefschetz fibrations over a 2-disk. In the process we associate to every compact Stein manifold infinitely many nonequivalent such Lefschetz fibrations.Comment: This is the corrected full-version of what has already appeared in GT. (Later GT may re-post its own corrected short-version

Hydraulic conductivity and undrained shear strength of clay-construction and demolition solid waste materials mixtures

The study aims to investigate the effects of three different construction and demolition materials (CDMs), including crushed waste asphalt (CWA), crushed waste bricks (CWB), and crushed waste concrete (CWC), on some geotechnical properties of low plastic clayey soil, particularly, the undrained shear strength (Su ) and the hydraulic conductivity (k). A set of experimental tests were performed on clayey soil and on clayey soil-CDM mixtures at mixing ratios of 5%, 10%, 15%, and 20% by dry weight. The results show that the soil plasticity decreases as the CDMs increase. Quantitatively, it is found a maximum of 12%, 6%, and 6% decrease in the liquid limits (LL) and a maximum of 9%, 4%, and 6% decrease in the plasticity limit (PI) of the mixtures with 20% of CWA, CWB, and CWC, respectively. The results of the Su estimated empirically from the fall cone tests show that the Su decreases as the CDMs increase. The Su reduces by approximately 10% and 2% of the mixtures with 20% CWA and CWB, respectively. But the Su is not affected by the CWC additive for water content lower than approximately 35%. The k value increases as the CDMs increase. The results show that the reported k value increases by 75%, 79%, and 247% of the mixtures with 20% of CWA, CWB, and CWC, respectively. Additionally, the k values obtained from the consolidation test confirm the findings of the effect of the CDMs on the coefficient of hydraulic conductivity. © 2021, Associacao Brasileira de Mecanica dos Solos. All rights reserved

Çeşitli Antiseptik Taşıyıcılarla Karıştırılan Kalsiyum Hidroksitin Enterococcus faecalis üzerindeki Antimikrobiyal Etkinliği

Amaç: Bu in vitro çalışmanın amacı farklı antiseptik taşıyıcı-kalsiyum hidroksit (KH) kombinasyonlarının Enterococcusfaecalis(E. faecalis) ile enfekte kök kanallarındaki antibakteriyel etkinliğini dentin blok modeli kullanarak test etmektir.Gereç ve Yöntemler: Kalsiyum hidroksit ile karıştırılmak üzere kullanılan taşıyıcılar gliserin distile su karışımı (7:1), oktenidinhidroklorit, %2’lik klorheksidinglukonat, %15’lik setrimit + %1.5’luk klorheksidinglukonat, %5.25’lik sodyum hipoklorittir. Altmış adet çekilmiş insan dişi örnekleri hazırlandı. Elli-beş tane kök segmenti E. faecalis ile 2 hafta boyunca enfekte edildi. Örnekler 5 deney grubu (n=10) ve pozitif kontrol grubuna (n=5) ayrıldı. Antiseptik-kalsiyum hidroksit karışımları 7 gün boyunca kök kanallarında bekletildi. Beş örnek sterilliği kontrol etmek için kullanıldı (negatif kontrol). Gates glidden frezler (# 3, 4, 5) yardımıyla kanal duvarlarından elde edilen dentin örnekleri fosfat-tamponlu salin (PBS) ve cam boncuk içeren şişelere aktarıldı ve 30 sn vortekslendi.  Bakteri içeren PBS’e seri dilüsyon yapıldı. Her bir dilüsyondan 25 μL halinde damlalar tripton soya agar plakları üzerine ekildi ve 37°C ‘de 48 saat inkübe edildi. Görünür koloni sayıları incelendi ve log10 değerlerine dönüştürüldü. İstatistiksel analiz için Kruskal-Wallis ve Mann Whitney-U testleri kullanıldı.Bulgular: Negatif kontrol grubunda bakteri üremesi görülmezken pozitif  kontrol grubunun bütün örneklerinde bakteri üremesi gözlemlenmiştir (log103,47 CFU ml-1). Deney grupları arasında istatistiksel olarak anlamlı bir fark bulunmamıştır (p>0.05).  KH +%2 klorheksidin ve KH+ setrimit-klorheksidin gruplarında E. faecalis biyofilmi tamamen elimine edilmiştir.  Sonuçlar: Setrimit-klorheksidin, oktenidin hidroklorit ve sodyum hipoklorit gibi çeşitli antiseptik ajanlar kalsiyum hidroksit ile karıştırılarak kullanıldığında kök kanallarından E. faecalis’i elimine etmede etkili bulunmuştur. Anahtar Kelimeler: antimikrobiyal,  E. faecalis,  kök dentini,  kanal-içi medikamen

Canonical contact structures on some singularity links

We identify the canonical contact structure on the link of a simple elliptic or cusp singularity by drawing a Legendrian handlebody diagram of one of its Stein fillings. We also show that the canonical contact structure on the link of a numerically Gorenstein surface singularity is trivial considered as a real plane bundle.Comment: The second version is substantially different from the first version. Bulletin of the London Mathematical Society, 201

The psychometric properties of school belonging scale for primary school students: a validity and reliability study

This study aims at developing a valid and reliable scale to determine primary school students’ sense of school belonging. In this respect, the relevant literature on the concept of belonging was reviewed; interviews were conducted with field experts and primary school students to determine items to be included in the scale. An item pool was created based on the findings of these processes. Later, a pilot form was prepared by taking the opinions of 2 field and 2 measurement and evaluation experts to ensure that the scale items represent the structure measured. This form was administered to 254 primary school students studying in the 2018-2019 academic year, and the final scale was obtained as a result of exploratory factor analysis was applied to 287 primary school students in a different school. For validity evidence, exploratory factor analysis (EFA), confirmatory factor analysis (CFA), convergent and discriminant analysis and item analysis; for reliability, findings of Cronbach Alpha and composite reliability coefficients were used. According to the exploratory factor analysis, the scale consisted of 3 factors with 13 items, and the total variance explained was 52.57%. As a result of the second-order confirmatory factor analysis of the obtained structure, the fit indices of the model showed that it was verified. The internal consistency coefficient of the developed model was α = .92 and the composite reliability coefficient was .93. These findings showed that the scale had psychometric properties to be used in future research

Predictive factor for lymph node metastasis in non-metastatic colorectal adenocarcinomas

Objectives: To evaluate the predictive factors of lymph node involvement in non-metastatic colorectal adenocarcinomas (nmCRC). Methods: A total of 453 patients diagnosed with nmCRC were analyzed regarding T stage, lymphovascular invasion status, tumor grade and proposed risk score (RS), determined by the combination of these three factors for lymph node metastasis. Results: The median age was 62 (25-90 years), M/F ratio was 1.4:1 and majority of the patients had tumors localized on the left colon (70.6%). The number of excised lymph nodes was ≥12 in 77% of the cases. The postoperative pathological assessments revealed that 57.2% of patie,nts had N0 disease, 29.1% had N1 disease, and 13.7% had N2 disease. The T stages (p=0.007), grade (p<0.001), lymphovascular invasion (p=0.002), RS (p<0.001), and number of excised lymph nodes (p=0.029) were significantly different between N0, N1, and N2 patients. Higher RS was associated with lymph node metastasis (p<0.001). Conclusion: The risk score may predict lymph node metastasis in patients with nmCRC and if validated may be helpful in the decision-making of adjuvant chemotherapy, especially in the elderly and patients with inadequate lymph node dissection

Real-world efficacy and safety of Ledipasvir plus Sofosbuvir and Ombitasvir/Paritaprevir/Ritonavir +/- Dasabuvir combination therapies for chronic hepatitis C: A Turkish experience

Background/Aims: This study aimed to evaluate the real-life efficacy and tolerability of direct-acting antiviral treatments for patients with chronic hepatitis C (CHC) with/without cirrhosis in the Turkish population.Material and Methods: A total of 4,352 patients with CHC from 36 different institutions in Turkey were enrolled. They received ledipasvir (LDV) and sofosbuvir (SOF)+/- ribavirin (RBV) ombitasvir/paritaprevir/ritonavir +/- dasabuvir (PrOD)+/- RBV for 12 or 24 weeks. Sustained virologic response (SVR) rates, factors affecting SVR, safety profile, and hepatocellular cancer (HCC) occurrence were analyzed.Results: SVR12 was achieved in 92.8% of the patients (4,040/4,352) according to intention-to-treat and in 98.3% of the patients (4,040/4,108) according to per-protocol analysis. The SVR12 rates were similar between the treatment regimens (97.2%-100%) and genotypes (95.6%-100%). Patients achieving SVR showed a significant decrease in the mean serum alanine transaminase (ALT) levels (50.90 +/- 54.60 U/L to 17.00 +/- 14.50 U/L) and model for end-stage liver disease (MELD) scores (7.51 +/- 4.54 to 7.32 +/- 3.40) (p<0.05). Of the patients, 2 were diagnosed with HCC during the treatment and 14 were diagnosed with HCC 37.0 +/- 16.0 weeks post-treatment. Higher initial MELD score (odds ratio [OR]: 1.92, 95% confidence interval [CI]: 1.22-2.38; p=0.023]), higher hepatitis C virus (HCV) RNA levels (OR: 1.44, 95% CI: 1.31-2.28; p=0.038), and higher serum ALT levels (OR: 1.38, 95% CI: 1.21-1.83; p=0.042) were associated with poor SVR12. The most common adverse events were fatigue (12.6%), pruritis (7.3%), increased serum ALT (4.7%) and bilirubin (3.8%) levels, and anemia (3.1%).Conclusion: LDV/SOF or PrOD +/- RBV were effective and tolerable treatments for patients with CHC and with or without advanced liver disease before and after liver transplantation. Although HCV eradication improves the liver function, there is a risk of developing HCC.Turkish Association for the Study of The Liver (TASL

Titreşim temelli ve küçültülebilir uydu yönelim eyleyicisi.

Major malfunctions are originated from bearing mechanisms of reaction wheels, momentum wheels and control moment gyroscopes. Current research investigates the theoretical background for attitude actuators depending on oscillatory actuation which can be implemented without bearings. The approximate angular momentum and dynamics of such a device is formulated. A prototype vibration based attitude control actuator was designed and produced. Design implications originating from the mathematical model of the actuator were incorporated into its mechanical design. An experimental setup consisting of a load cell and a frictionless air bearing was utilized. Experiments were carried in which the device successfully rotated the experimental setup; proving the concept of vibration based attitude actuation. Furthermore, a scale-down study was carried out to assess the novel concept’s suitability for miniaturization. Later, a MEMS based actuator was designed and its functioning was exhibited through simulations.Thesis (Ph.D.) -- Graduate School of Natural and Applied Sciences. Aerospace Engineering