AN ANALYSIS OF HOW PRESERVICE MATH TEACHERS CONSTRUCT THE CONCEPT OF LIMIT IN THEIR MINDS

Recently, people prefer learning information operationally rather than conceptually. In this context, this study was carried out to uncover how preservice math teachers construct in their minds the conceptual definition of limit within the scope of the Calculus Course. The participants of this study consisted of 62 (30 female, 32 male) sophomore students studying in the Elementary Mathematics Teacher Education Department at Uludağ University Faculty of Education in the 2016–2017 academic year. Midterm and final exam questions requiring the use of prior knowledge were used to help collect data. Interviews were conducted with three participants who were chosen for their success. In these interviews, five questions were asked by the researchers to uncover the mathematical thinking levels and abstraction processes of the participants. The methods of semi-structured interviews and observations were used to collect data. The data were video-recorded and transcribed. The transcripts were analyzed and interpreted according to the cognitive actions of the RBC- model and the steps in Sfard’s theory of mathematics learning. Based on the analysis, the participants were found to be more successful in operational information than in conceptual information. Although the preservice teachers were able to accomplish operational learning, it can be said that they could not fully accomplish conceptual learning because they could not identify algebraic representations and could not use reasoning on these representations. Interviews with the participants revealed that they memorized the characteristics of the concept of limit to be successful in the exams. However, conceptual learning did not take place. Understanding how participants learn is believed to benefit the educators who teach the concept of limit.  Article visualizations

İntrakranial kitlelerin bilgisayarlı tomografi rehberliğinde sterotaktik mikrocerrahi rezeksiyonu]

Stereotactic microsurgical techniques allow for the precise localization and resection of lesions in critical areas of cortex or deep within the brain and minimize operative exposure to the surrounding tissues. This study presents our experience with CT-guided stereotactic microsurgical resection of cerebral lesions using the Leksell frame. A total of 42 patients undergoing computerized tomography guided stereotactic microsurgical resection of cerebral lesions between June 2000 and September 2017 were included in the study. Clinical, radiological, histological and follow-up data were retrospectively evaluated. Pre-and post-operative general status of the patients was assessed by Karnofsky Performance Scale (KPS). Except for the subjects with high-grade gliomas, complete resection could be accomplished in all cases. Of the 24 cases with convulsions, a complete cessation of epileptic attacks was attained in 20 and a decrease in their number and frequency was noted in 4 cases. Overall, 20 patients had no change in the KPS score, while 28 patients had increased and two had decreased KPS scores. No postoperative mortality occurred. CT-guided stereotactic microsurgical craniotomy is a safe, reliable and effective technique, which is particularly useful for the surgical treatment of small, benign cranial lesions and cerebral metastases. © 2018, Logos Medical Publishing. All rights reserved

An efficient algorithm for 3D rectangular box packing

Akyokuş, Selim (Dogus Author) -- Conference full title: 9th International Conference, ETAI 2009, Ohrid, September 26-29, Republic of Macedonia, 2009.Getting highest occupancy rate of capacity of a container is very important for the companies, which deals in shipping or has shipping as a part of their main activities. They have to fit 3D boxes in container with optimum or nearest to optimum placement in order to ship more products with a minimum cost. The problem of fitting the boxes which is different from or the same to each other into a big container in optimum level, is called 3-dimensional packing problem. In this problem, the main objective is to minimize used container volume or wasted container space. This provides the reduction of costs in shipments with the use minimum number of containers

Morphometric and macroanatomic examination of auditory ossicles in male wolves (Canis lupus)

Background: The aim of the study was to determine morphometric and macroanatomic features of auditory ossicles and the tympanic bulla in wolf. Materials and methods: For this purpose, 7 skulls of adult male wolf were used in the study. Auditory ossicles was photographed on a dissection microscope after it was removed from the skull. A total of 14 morphometric measurements were taken among the different points of malleus, incus and stapes in Image J programme. Mean values of the measurements were obtained and statistically compared in terms of sides (right-left). Results: In male wolves, the lengths of the right and left malleus were determined as mean 9.35 ± 0.14 and 9.57 ± 0.25 mm, the lengths of the incus as mean 3.01 ± 0.32 and 2.94 ± 0.16 mm, and the lengths of the stapes as mean 2.57 ± 0.12 and 2.59 ± 0.14 mm, respectively. The differences were not statistically significant when all the morphometric parameters were compared in terms of sides (p > 0.05). Conclusions: It is considered that this study will contribute to the anatomical studies to be conducted in the Canidae family regarding auditory ossicles

Characterization of an embedded RF-MEMS switch

An RF-MEMS capacitive switch for mm-wave integrated circuits, embedded in the BEOL of 0.25μm BiCMOS process, has been characterized. First, a mechanical model based on Finite-Element-Method (FEM) was developed by taking the residual stress of the thin film membrane into account. The pull-in voltage and the capacitance values obtained with the mechanical model agree very well with the measured values. Moreover, S-parameters were extracted using Electromagnetic (EM) solver. The data observed in this way also agree well with the experimental ones measured up to 110GHz. The developed RF model was applied to a transmit/receive (T/R) antenna switch design. The results proved the feasibility of using the FEM model in circuit simulations for the development of RF-MEMS switch embedded, single-chip multi-band RF ICs

Spectral characterization and antimicrobial activity of some transition metal complexes of 2-(5-nitro-1H-benzimidazol-2-yl)-4-bromophenol

ABSTRACT. MnCl2, FeCl3, Ru(DMSO)4Cl2, CoCl2, NiCl2, PdCl2, CuCl2, AgNO3, CdCl2 and HgCl2 complexes of 2-(5-nitro-1H-benzimidazol-2-yl)-4-bromophenol (HL) were synthesized and characterized. The structures of the complexes were confirmed on the basis of elemental analysis, TGA, molar conductivity and magnetic moment measurements, FT-IR, far-IR, FT-Raman, UV-Visible, NMR and fluorescence spectroscopy. According to the analytical and spectral data, the ligand acted as bidentate, via the imine nitrogen and the phenolate oxygen atoms towards to the metal ions except the Ag(I). The complexes were screened for in vitro antibacterial activities against S. aureus, S. epidermidis, E. coli, K. pneumoniae, P. aeruginosa, P. mirabilis and for antifungal activity against C. albicans. Ciprofloxacin and fluconazole were used as reference for antibacterial and antifungal activities of the complexes, respectively. In most cases, the complexes tested showed considerable activity on S. aureus especially, which is a Gram positive bacterium. In addition, the Hg(II) and Ag(I) complexes were found to have superior activity toward all of the microorganisms whereas the Pd(II) and Cd(II) complexes showed considerably antimicrobial effect on S. aureus and C. albicans selectively.               KEY WORDS: Benzimidazole, Bromophenol, Transition metal complexes, Antibacterial, Antifungal Bull. Chem. Soc. Ethiop. 2019, 33(3), 451-466.   DOI: https://dx.doi.org/10.4314/bcse.v33i3.

Öğretmen Adaylarının Çevrimiçi ve Geleneksel Bilgisayar okuryazarlığı Derslerinde Bilgisayara Yönelik Tutumlarının Karşılaştırılması: Bir Durum Çalışması

This study examined the effect of two computer literacy courses at METU, (one offered on-line and the other given by traditional methods. These two courses were compared in terms of their effectiveness on the attitudes of the student-teachers towards computers. Different demographics such as gender, whether any computer-related courses had been taken before, previous computer attitude, and possession of a home computer were taken into consideration. This study also explored the other factors that contributed to changes in attitudes of the student teachers. The study used data from 209 (147 female, 62 male) student-teachers of which 69 attended the on-line computer literacy course IS100 "Introduction to Information Technology and Applications", and 140 attended the traditional computer literacy course SCE300. "Computer Applications in Education", which were offered at the Middle East Technical University (METU) in Turkey.Results of Multiple Regression Analysis indicated that there is a combined effect of gender, computer literacy course type (traditional vs on-line), whether any computer related course had been taken before, previous computer attitude and possession of home computer on student-teachers' post-attitude toward computers. The follow-up study results also supported the results of statistical the analysis, and they investigated student teachers' perceptions about the computer literacy course they attended.Bu çalışmanın amacı, Orta Doğu Teknik Üniversitesi (ODTÜ)'nde çevrimiçi (on-line) olarak yürütülen IS 100 kodlu 'Bilişim Teknolojileri ve Uygulamalarına Giriş' dersi ile geleneksel yöntemlerle yürütülen SCE 300 kodlu 'Eğitimde Bilgisayar Uygulamaları' dersinin öğretmen adaylarının bilgisayara yönelik tutumları üzerindeki etkilerini incelemektir. Çalışmada, öğrencilerin cinsiyet, daha önce bilgisayar dersi alıp almadıkları, dersi almadan önceki bilgisayara yönelik tutumları ve evde bir bilgisayarları olup olmadığı gibi faktörler de göz önünde tutulmuştur Ayrıca, öğrencilerin bilgisayara yönelik tutumlarını başka ne gibi faktörlerin etkilediği niteliksel olarak da araştırılmıştır. Veriler 147'si kız, 62'si erkek, toplam 209 öğretmen adayı öğrenciden toplanmıştır. Bunlardan 69'u çevrimiçi (ISIOO-Bilişim Teknolojileri ve Uygulamalarına Giriş), 140'ı ise geleneksel yöntemlerle verilen (SCE300-Eğitimde Bilgisayar Uygulamaları) bilgisayar okuryazarlığı derslerine katılmıştır. Çok yönlü regrasyon sonuçları, cinsiyet, alman bilgisayar dersinin çeşidi (geleneksel ya da çevrimiçi), daha önce bilgisayarla ilgili derslerin alınıp alınmaması, dersi almadan önceki bilgisayara yönelik tutumları ve evde bilgisayar olup olmaması gibi faktörlerin öğrencilerin ders sonrası tutumları üzerinde birleşik etkisi olduğunu göstermiştir. Niteliksel çalışmanın sonuçları ise istatistiksel sonuçları desteklemiş ve öğrencilerin devam ettikleri bilgisayar dersi ile ilgili düşünce ve görüşlerini analiz etmiştir

Expectations of mental illness disclosure outcomes in the work context:A cross-sectional study among Dutch workers

Purpose The decision whether to disclose mental illness at work can have important positive and negative consequences for sustainable employment and well-being. The aim of the study is (1) to examine workers’ expectations of outcomes of mental illness disclosure in the workplace and to evaluate their expectations regarding which factors are of influence on these outcomes, (2) to identify distinct subgroups of workers, and (3) to characterize these subgroups in terms of personal, sociodemographic, and work-related characteristics. Methods In this cross-sectional survey study, a sample of 1224 Dutch workers was used. Latent Class Analysis (LCA) was used to identify classes of workers based on expected workplace mental illness outcomes. A three-step approach LCA was chosen to investigate whether the classes differed in characteristics. Results The majority of workers expected predominantly positive outcomes of workplace mental illness disclosure (e.g., being able to be one’s authentic self; 82.4%), even though they simultaneously expected disclosure to lead to advancement-related discrimination (e.g., lower chances of contract renewal; or getting a promotion; 68.4% and 57%, respectively). Six distinct subgroups of workers were identified based on expected workplace mental illness disclosure outcomes: two positive classes (50.1%), two negative classes (33.3%), and two classes who indicated not to know what the outcomes would be (16.7%). Significant differences between the classes were found on personal experience, work-related association with mental illness, gender, educational level, and workplace atmosphere. Conclusion The disclosure process is complex, as most workers were optimistic (i.e., expected generally positive outcomes) whilst simultaneously expecting workplace discrimination. Subgroup differences in expectations regarding workplace mental illness disclosure outcomes were found

On the Application of Beamforming in LDACS

Currently, aeronautical communications is under-going a modernization process from analog to digital technology. The L-band Digital Aeronautical Communications System (LDACS) is the upcoming digital data link for air-ground communications and is being standardized within ICAO as well as EUROCAE at the moment. A wireless communication system can be interrupted by intended or unintended jamming signals. Therefore, the robustness of wireless systems is crucial. In this paper, we investigate the use of beamforming in LDACS to improve its performance and robustness. We analyze different antenna array designs and assess their performance to find the most suitable configuration for LDACS. Accordingly, the chosen antenna array design is evaluated for different flight scenarios considering a realistic LDACS link budget. We show that the chosen phased antenna array design improves the signal-to-noise-ratio of the LDACS reverse link by over 10 dB. Hence, using beamforming, the robustness of LDACS can be enhanced and higher data rates can be achieved by applying the built-in LDACS adaptive coding and modulation capabilities

Measuring sustainable employability:psychometric properties of the capability set for work questionnaire

BACKGROUND: The capability set for work questionnaire (CSWQ) is being used to measure the new model of sustainable employability building on the capability approach. However, previous studies on the psychometric properties of the instrument are limited and cross-sectional. This two-way study aimed to (1) evaluate the convergent validity of the CSWQ with the theoretically related constructs person-job fit, strengths use, and opportunity to craft and (2) test the predictive and incremental validity of the questionnaire for the well-established work outcomes, including work ability, work engagement, job satisfaction, and task performance. METHODS: A representative sample of 303 Dutch workers, chosen with probably random sampling, were surveyed using a one-month follow-up, cross-lagged design via the Longitudinal Internet Studies for the Social Sciences panel. The convergent validity was assessed by exploring the strength of associations between the capability set for work questionnaire and the theoretically related constructs using Pearson’s correlations. The predictive and incremental validity was evaluated by performing a series of linear hierarchical regression analyses. RESULTS: We found evidence of the convergent validity of the capability set score by moderate correlations with person-job fit, strengths use, and opportunity to craft (r = 0.51–0.52). A series of multiple regression analyses showed that Time 1 capability set score and its constituents (i.e., importance, ability, and enablement) generally had predictive and incremental validity for work ability, work engagement, job satisfaction, and task performance measured at Time 2. However, the incremental power of the CSWQ over and above conceptually related constructs was modest. CONCLUSIONS: The findings support the convergent, predictive, and incremental validity of the capability set for work questionnaire with not previously investigated work constructs. This provided further evidence to support its utility for assessing a worker’s sustainable employability for future research and practical interventions