A QUASI-GROUP ASSOCIATED WITH THE WEB FORMED BY THREE PENCILS OF CIRCLES WHICH BELONG TO THE SAME BUNDLE

It is well-known that the 3-web formed by three pencils of straight lines is topologically equivalent to the hexagonal 3-web composed of three pencils of circles which belong to the same bundle. In this work, corresponding to the web under consideration a quasi-group is constructed with the help of the property mentioned

Comparative evaluation of shear bond strength of three flowable compomers on enamel of primary teeth: An in-vitro study

Background: The aim of the present study was to determine Shear bond strength (SBS) of different flowable compomers on the enamel surface of primary teeth. The null hypothesis to be tested was that none of the flowable compomer would differ significantly from the other two with respect to SBS. As a result, the tested materials that have the easiest application on child patient is preferred. Material and Methods: Sixty newly extracted non carious primary molars were selected. The buccal surface was cleaned and polished to obtain a flat enamel surface. The specimens were randomly divided into three groups of 20 teeth each, based on the flowable compomers applied, as follows: group I: Dyract Flow® (Dentsply, Konstanz, Germany); group II: Twinky Star Flow® (Voco, Cuxhaven, Germany); and group III: R&D Series Nova Compomer Flow® (Imicryl, Konya, Turkey). Results: SBS in group II (6.78± 0.45 MPa) were significantly lower than groups I and III (8.30 ± 0.29 and 8.43 ± 0.66 MPa, respectively) (P<.001). No significant difference was found between groups I and III (P<.05). Conclusions: Significant differences existed between the SBS of the groups. Therefore, the null hypothesis was rejected. Flowable compomers can provide adequate SBS with self-etching system at restoration of primary teeth. Thus, successful restorations in pediatric patients can be done in a practical way. © Medicina Oral S.L

Near-linear dynamics in KdV with periodic boundary conditions

Near linear evolution in Korteweg de Vries (KdV) equation with periodic boundary conditions is established under the assumption of high frequency initial data. This result is obtained by the method of normal form reduction

A novel index in healthy infants and children — subarachnoid space: ventricle ratio

Background: The subarachnoid space (SAS) and ventricular width (VW) in normalinfants and children were studied with ultrasonography to provide the objectivemeasurement and define a normal range for these measurements. The additional aim was to determine the stable ratio as a SAS/VW.Materials and methods: A total of 100 healthy subjects, including 48 males and52 females, were studied. The cases were divided into 3 age groups: 0–6 months(n = 65), 7–12 months (n = 24) and &gt; 13 months (n = 11). Transfontanel ultrasonography was performed in all the cases. SAS, VW and the SAS/VW ratios were calculated. The study was approved by the ethical committee. All parents wereinformed about the sonographic examination and their approvals were taken.Results: SAS was calculated as 3.1 (0.5–6) mm and VW was calculated as 3.6(1.3–5) mm. SAS/VW ratio was 0.9 ± 0.3. There was no statistically significant difference among SAS, VW and SAS/VW ratios in 3–97 percentile group (p &gt; 0.05).Conclusions: Ultrasonography can be used as a practicable and reproducible modalityin the measurement of SAS and VW in healthy children. It is a non-invasivemethod and allows for serial follow-up. SAS/VW ratio can be used as an index inhealthy children

Determination of periodic deformation from InSAR results using the FFT time series analysis method in Gediz Graben

Permanent Scatterers (PS) point velocities obtained by the interferometric synthetic aperture radar (InSAR) method are generally determined using the linear regression model, which ignores periodic and seasonal effects. In this study, software was developed that can detect periodic effects by applying fast Fourier transformation (FFT) time series analysis to InSAR results. Using the FFT time series analysis, the periodic components of the surface movements at the PS points were determined, and then the annual velocity values free from periodic effects were obtained. The study area was chosen as the Gediz Graben, a tectonically active region where aseismic surface deformations have been observed in recent years. As a result, using the developed method, seasonal effects were successfully determined with the InSAR method at the PS points in the study area with a period of 384 days and an average amplitude of 19 mm. In addition, groundwater level changes of a water well in the region were modeled, and 0.93 correlation coefficient values were calculated between seasonal InSAR displacement values and water level changes. Thus, using the developed methodology, the relationship between the tectonic movement in the Gediz Graben in Turkey and the seasonal movements and the change in the groundwater level was determined

Preservice Teachers' Beliefs, Attitudes, and Motivation about Technology Integration

The Theory of Planned Behavior was used as a framework, along with Self-Determination Theory, to examine preservice teachers' motivation to include technology in their future teaching. We modified instruments to measure theoretical constructs to be applied to plans for the use of technology. Measured were: perceived behavioral control, attitudes toward technology use, perceived social norms, intrinsic and extrinsic motivation and amotivation. One hundred and fourteen preservice teachers completed the instrumentation and 67 completed a pre/post activity and reflective task concerning their attitudes and beliefs on technology, technology integration, and its role in the classroom. The best single predictor of both intrinsic and extrinsic motivation was positive attitudes toward technology use. For amotivation, the best predictors were negative attitudes toward technology use and negative social norms. The pre-post activity demonstrated that participants struggled to design meaningful technology integration activities.Yeshttps://us.sagepub.com/en-us/nam/manuscript-submission-guideline

Rethinking mobility of international university students during COVID-19 pandemic

Purpose – The purpose of the study is to examine the relationship between the COVID-19 pandemic and international student mobility from an alternative perspective and to reveal descriptive findings. Design/methodology/approach – This study follows qualitative research methodology. In accordance with the purpose of the study, the data were collected by the literature review and then it was analyzed by the descriptive analysis method. The effect of the COVID-19 pandemic on international student mobility and the relationships between these variables are explained by tables and classifications. Findings – According to the findings obtained, the restrictions in physical student mobility and shutdown are observed as the biggest challenges that occurred in higher education during the COVID-19. On a global scope, international student mobility has experienced a major break. Physical campus life is still on standby. Online higher education does not give any campus life as before. Students cannot benefit form city's or country's facilities when studying online at home country. The collaboration between university and business has been declined and this is even more discouraging for international students. The hybrid education model produced an intermediate solution in this period. On the other hand, the rise of online education has created new techniques for higher education. University students who cannot go abroad attend different countries lectures and education programs. But also a new challenge has come as the access of online platforms in under developing countries university students. Online education system also discussed in terms of creating inequality in higher education. Research limitations/implications – This study focused on student mobility and not focused about academic mobility. Practical implications – It is seen that the traditional higher education system has been adapted into online distance higher education system since COVID-19 crises began globally. On the other side, it is observed that most of studies have focused the effect of COVID-19 on university students based on the transition to online education. When considering the effect of pandemic process on the mobility of international students and higher education, the authors can suggest policy makers to develop new higher education protocols and teaching models supporting key issues (economic, social, health, education and equalization) in the long-term. Higher education institutes have been able to produce creative and innovative solutions for both education and communication during the pandemic process. Social implications – University students who cannot go abroad attend different countries lectures and education programs. But also a new challenge has come as the access of online platforms in under developing countries university students. Online education system also discussed in terms of creating inequality in higher education. Originality/value – This study provides a new perspective for international student mobility in the context of COVID-19 pandemic. This is an emerging issue for the literature. This study is original with its approach to the subject from a global perspective through reviewing the studies of different countries. This study points out key variables for determining the effect of COVID-19 on international student mobility for future studies. When employing quantitative research models, the current key variables can guide them

On non-local variational problems with lack of compactness related to non-linear optics

We give a simple proof of existence of solutions of the dispersion manage- ment and diffraction management equations for zero average dispersion, respectively diffraction. These solutions are found as maximizers of non-linear and non-local vari- ational problems which are invariant under a large non-compact group. Our proof of existence of maximizer is rather direct and avoids the use of Lions' concentration compactness argument or Ekeland's variational principle.Comment: 30 page