Tamsayıların Anlaşılmasında Öğretmenin İmgelemeyi Desteklemedeki Rolü

This paper presents the results of a design experiment conducted in a 7th grade mathematics classroom aimed at improving students’ understanding of integer concepts and operations. The study particularly focuses on an expert teacher’s role in helping students develop meaningful imagery which students can use as a foundation to fold back and rely on as they engage in further mathematical activities. Toulmin’s model of argumentation is used as an analytical tool to document when an image becomes taken-as-shared by the classroom community. The results suggest that the practices of the teacher played an important role in students’ development of various images in understanding and solving integer problems meaningfully as well as communicating their ideas effectively.Bu çalışma, yedinci sınıf matematik öğrencilerinin tamsayı kavramı ve işlemlerini daha iyi anlayabilmeleri için yapılan bir araştırmanın sonuçlarını sunmaktadır. Çalışmada özellikle uzman bir öğretmenin öğrencilerin yeni matematiksel kavramları anlamalarında geriye dönük olarak kullanabilecekleri mantıklı imgelemeyi geliştirmelerindeki rolü araştırılmıştır. Çalışmada Toulmin tartışma modeli öğrencilerin oluşturdukları imgelerin tüm sınıf tarafından kabul edilip ortak olarak kullanılıp kullanılmadığını analiz etmek amacıyla kullanılmıştır. Sonuçlar, öğretmenin kullanmış olduğu yöntemlerin öğrencilerin tamsayı problemlerini anlaması ve doğru çözmesinde olduğu kadar, fikirlerini iletmede de etkili olan imgelemelerin gelişiminde önemli bir rol oynadığını göstermişti

The Role of the Teacher in Supporting Imagery in Understanding Integers

This paper presents the results of a design experiment conducted in a 7th grade mathematics classroom aimed at improving students\u27 understanding of integer concepts and operations. The study particularly focuses on an expert teacher\u27s role in helping students develop meaningful imagery which students can use as a foundation to fold back and rely on as they engage in further mathematical activities. Toulmin\u27s model of argumentation is used as an analytical tool to document when an image becomes taken-as-shared by the classroom community. The results suggest that the practices of the teacher played an important role in students\u27 development of various images in understanding and solving integer problems meaningfully as well as communicating their ideas effectively

ON DERIVATIONS SATISFYING CERTAIN IDENTITIES ON RINGS AND ALGEBRAS

The present paper deals with the commutativity of an associative ring $R$ and a unital Banach Algebra $A$ via derivations. Precisely, the study of multiplicative (generalized)-derivations $F$ and $G$ of semiprime (prime) ring $R$ satisfying the identities $G(xy)\pm [F(x),y]\pm [x,y]\in Z(R)$ and $G(xy)\pm [x,F(y)]\pm [x,y]\in Z(R)$ has been carried out. Moreover, we prove that a unital prime Banach algebra $A$ admitting continuous linear generalized derivations $F$ and $G$ is commutative if for any integer $n>1$ either $G((xy)^{n})+[F(x^{n}),y^{n}]+[x^{n},y^{n}]\in Z(A)$ or $G((xy)^{n})- [F(x^{n}),y^{n}]-[x^{n},y^{n}]\in Z(A)$

Multi-Organs-on-Chips for Testing Small-Molecule Drugs: Challenges and Perspectives.

Organ-on-a-chip technology has been used in testing small-molecule drugs for screening potential therapeutics and regulatory protocols. The technology is expected to boost the development of novel therapies and accelerate the discovery of drug combinations in the coming years. This has led to the development of multi-organ-on-a-chip (MOC) for recapitulating various organs involved in the drug-body interactions. In this review, we discuss the current MOCs used in screening small-molecule drugs and then focus on the dynamic process of drug absorption, distribution, metabolism, and excretion. We also address appropriate materials used for MOCs at low cost and scale-up capacity suitable for high-performance analysis of drugs and commercial high-throughput screening platforms

Reproductive Capacity Evolves in Response to Ecology through Common Changes in Cell Number in Hawaiian Drosophila

© 2019 Elsevier Ltd Lifetime reproductive capacity is a critical fitness component. In insects, female reproductive capacity is largely determined by the number of ovarioles, the egg-producing subunits of the ovary [e.g., 1]. Recent work has provided insights into ovariole number regulation in Drosophila melanogaster. However, whether mechanisms discovered under laboratory conditions explain evolutionary variation in natural populations is an outstanding question. We investigated potential effects of ecology on the developmental processes underlying ovariole number evolution among Hawaiian Drosophila, a large adaptive radiation wherein the highest and lowest ovariole numbers of the family have evolved within 25 million years. Previous studies proposed that ovariole number correlated with oviposition substrate [2–4] but sampled largely one clade of these flies and were limited by a provisional phylogeny and the available comparative methods. We test this hypothesis by applying phylogenetic modeling to an expanded sampling of ovariole numbers and substrate types and show support for these predictions across all major groups of Hawaiian Drosophila, wherein ovariole number variation is best explained by adaptation to specific substrates. Furthermore, we show that oviposition substrate evolution is linked to changes in the allometric relationship between body size and ovariole number. Finally, we provide evidence that the major changes in ovarian cell number that regulate D. melanogaster ovariole number also regulate ovariole number in Hawaiian drosophilids. Thus, we provide evidence that this remarkable adaptive radiation is linked to evolutionary changes in a key reproductive trait regulated at least partly by variation in the same developmental parameters that operate in the model species D. melanogaster. Organisms leaving more offspring likely have higher fitness. Sarikaya et al. use the adaptive radiation of Hawaiian Drosophila to investigate the evolution of fecundity. They find that habitat shifts played a strong role and identify a developmental process that underlies evolutionary change in ovarian development and impacts egg-laying capacity

Impedance testing of porous Si3N4 scaffolds for skeletal implant applications

Si3N4 ceramics show excellent characteristics of mechanical and chemical resistance in combination with good biocompatibility, antibacterial property and radiolucency. Therefore, they are intensively studied as structural materials in skeletal implant applications. Despite their attractive properties, there are limited data in the field about in vitro studies of cellular growth on ceramic implant materials. In this study, the growth of bone cells was investigated on porous Silicon Nitride (Si3N4) ceramic implant by using electrochemical impedance spectroscopy (EIS). Partial sintering was performed at 1700 °C with limited amount of sintering additive for the production of porous Si3N4 scaffolds. All samples were then sterilized by using ethylene oxide followed by culturing MG-63 osteosarcoma cells on the substrates for in vitro assays. At 20 and 36 hours, EIS was performed and results demonstrated that magnitude of the impedance as a result of the changes in the culture media increased after incubation with osteosarcoma cells. The changes are attributed to the cellular uptake of charged molecules from the media. Si3N4 samples appear to show large impedance magnitude changes, especially between 100 Hz and 1 Hz. Impedance changes were also correlated with WST-1 measurements (36 hr) and DAPI results

Flavones as tyrosinase inhibitors: kinetic studies in vitro and in silico.

Collaboration between DMU-Leicester School of Pharmacy (UK), Hacettepe University, Faculty of Pharmacy, Ankara (Turkey) and Karadeniz Technical University, Faculty of Pharmacy, Trabzon (Turkey).Introduction – Tyrosinase is a multifunctional copper-containing oxidase enzyme that catalyzes the first steps in the formation of melanin pigments. Identification of tyrosinase inhibitors is of value for applications in cosmetics, medicine and agriculture. Objective – To develop an analytical method that allows identification of drug-like natural products that can be further developed as tyrosinase inhibitors. Results of in vitro and in silico studies will be compared in order to gain a deeper insight into the mechanism of action of enzyme inhibition. Method – Using an in vitro assay we tested tyrosinase inhibitor effects of five structurally related flavones, i.e. luteolin (1), eupafolin (2), genkwanin (3), nobiletin (4), and chrysosplenetin (5). The strongest inhibitors were further investigated in silico, using enzyme docking simulations. Results - All compounds tested showed modest tyrosinase inhibitory effect compared to the positive control, kojic acid. The polymethoxy flavones 4 and 5 exhibited the strongest tyrosinase inhibitory effect with IC50 values of 131.92 ± 1.75 μM and 99.87 ± 2.38 μM respectively. According to kinetic analysis 2, 4 and 5 were competitive inhibitors, whereas 1 and 3 were noncompetitive inhibitors of tyrosinase. Docking studies indicated that methoxy groups on 4 and 5 caused steric hindrance which prevented alternative binding modes in the tyrosinase; the methoxy groups on the B-ring of these flavones faced the catalytic site in the enzyme. Conclusions – The docking simulations nicely complemented the in vitro kinetic studies, opening the way for the development of predictive models for use in drug design