Antioxidants in aqueous extract of Myristica fragrans (Houtt.) suppress mitosis and cyclophosphamide-induced chromosomal aberrations in Allium cepa L. cells     

Akinboro A  Mohamed KB  Asmawi MZ  Sulaiman SF  Sofiman OA 《Journal of Zhejiang University. Science. B》2011,12(11):915-922

In this study, freeze-dried water extract from the leaves of Myristica fragrans (Houtt.) was tested for mutagenic and antimutagenic potentials using the Allium cepa assay. Freeze-dried water extract alone and its combination with cyclophosphamide (CP) (50 mg/kg) were separately dissolved in tap water at 500, 1000, 2000, and 4000 mg/kg. Onions (A. cepa) were suspended in the solutions and controls for 48 h in the dark. Root tips were prepared for microscopic evaluation. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) free radicals’ scavenging power of the extract was tested using butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) as standards. Water extract of Myristica fragrans scavenged free radicals better than BHA, but worse than BHT. The extract alone, as well as in combination with CP suppressed cell division, and induced chromosomal aberrations that were insignificantly different from the negative control (P≤0.05). However, cytotoxic and mutagenic actions of CP were considerably suppressed. The observed effects on cell division and chromosomes of A. cepa may be principally connected to the antioxidant properties of the extract. The obtained results suggest mitodepressive and antimutagenic potentials of water extract of the leaves of M. fragrans as desirable properties of a promising anticancer agent.  相似文献   

Palestinian media landscape: Experiences,narratives, and agendas of journalists under restrictions     

Ibrahim Hazboun  Ifat Maoz  Menahem Blondheim 《The Communication Review》2019,22(1):1-25

This study aims to increase our understanding of the dynamics of the Palestinian media and the conditions and circumstances in which they work, including both the conflict with Israel and the internal political strife within Palestinian society. It is based on the use of qualitative research methods and was conducted in two stages. First, we performed a mapping of Palestinian media outlets. Data on these Palestinian media outlets were collected online from the West Bank-based Palestinian Authority’s Ministry of Information website, the Gaza-based Hamas government’s Ministry of Information website, and statements published by Palestinian media outlets on their websites describing their affiliation and ownership. Second, to gain a more in-depth understanding of the dynamics and experience of practicing journalism in a situation of asymmetrical conflict, semistructured in-depth interviews were conducted with 25 professional local Palestinian journalists working for local media outlets in the Gaza Strip, the West Bank, and East Jerusalem. Through this study we aim to learn more about how groups shape and express their narratives and agendas through the media when restricted by the conditions, pressures, and limitations of asymmetrical conflict.  相似文献   

A corpus-based discourse analysis of the vision and mission statements of universities in Turkey     

Ibrahim Efe 《高等教育研究与发展》2015,34(6):1110-1122

This article presents findings from a corpus-assisted discourse analysis of mission and vision statements of 105 state and 66 private/foundation universities in Turkey. The paper combines a corpus-based approach with critical discourse analysis to interpret the data in relation to its institutional as well as socio-political context. It argues that the mission and vision statements are marked by a need for reassuring their legitimacy and the demands of a growing tertiary market. The historical and cultural backgrounds of the development of universities in Turkey, as well as political and economic conditions, are also decisive in the shaping of mission and vision statement of universities.  相似文献   

Gender Difference in Teachers’ Mathematical Knowledge for Teaching in the Context of Single-Sex Classrooms     

Haroun  Ramzi F.  Ng  Dicky  Abdelfattah  Faisal A.  AlSalouli  Misfer S. 《International Journal of Science and Mathematics Education》2015,14(2):383-396

This study examines gender differences of teachers on their mathematical knowledge for teaching in the context of single-sex classrooms in Saudi Arabia. A translated version of the Mathematical Knowledge for Teaching (MKT) instrument (Learning Mathematics for Teaching [LMT], 2008) in Number and Operation Content Knowledge (CK) and Knowledge of Content and Student (KCS) scales were administered to 197 teachers (146 male and 51 female). Two-sample t test and multiple regression were conducted to compare the two groups and test the effect of teacher background variables. Female teachers significantly scored better than their male counterpart. Gender, years of teaching experience, and specialization significantly predicted teachers’ content knowledge, F(3, 187) = 13.180, explaining 41.8 % of the variance. Only gender and specialization significantly predicted teachers’ knowledge of content and student, F(2, 191) = 6.335, explaining 24.9 % of the variance. Further comparing items in the MKT instrument where female teachers outperformed male teachers confirmed that female teachers were better in attending to the content knowledge in the context of student’s learning.

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Legendre wavelet operational matrix of derivative for optimal control in a convective–diffusive fluid problem     

Taher Abualrub  Ibrahim Sadek 《Journal of The Franklin Institute》2014

We consider the problem of controlling the model of one-dimensional fluid flow through a soil packed tube in which a contaminant is initially distributed. A fluid is pumped through a tube to remove the contaminant. The control problem is to determine the optimal convective velocity due to the fluid being pumped by minimizing a given performance criterion. The performance criterion is chosen to be a combination of the total contaminant at the final time and the cost of the control. The set of orthogonal Fourier trigonometry series is used as a basis function of the Galerkin procedure to lump the distributed parameter system. A Legendre wavelet operational matrix of derivative is used to approximate the control and modal state variables. The main characteristics of this technique is that it reduces these problems to those of solving a system of algebraic equations, thus greatly simplifying the problem. The effectiveness of the proposed approach is illustrated numerically and the results are quite satisfactory.  相似文献   

Biological variations of ADAMTS13 and von Willebrand factor in human adults     

Meltem Kilercik  Abdurrahman Coskun  Mustafa Serteser  Deniz Inan  Ibrahim Unsal 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2014,24(1):138-145

Background:

The ultra-large von Willebrand factor (vWF) multimers are very active and must be degraded by ADAMTS13 for optimal activity. A severe functional deficiency of ADAMTS13 has been associated with thrombotic thrombocytopenic purpura. The correct interpretation of patient vWF and ADAMTS13 plasma levels requires an understanding of the biological variation associated with these analytes. In the present paper, we aimed to determine the biological variation of ADAMTS13 and vWF in human adults.

Materials and methods:

Blood samples were collected weekly from 19 healthy subjects for 5 consecutive weeks. vWF activity and antigenicity were determined using aggregometric and immunoturbidimetric methods. ADAMTS13 antigenicity and activity were determined by ELISA.

Results:

The within-subject biological variations for vWF activity and antigenicity were 8.06% and 14.37%, respectively, while the between-subject biological variations were 18.5% and 22.59%, respectively. The index of individuality for vWF activity was 0.44, while vWF antigenicity was 0.64. Similarly, ADAMTS13 activity and antigenicity within-subject biological variations were 12.73% and 9.75%, respectively, while between-subject biological variations were 9.63% and 6.28%, respectively. The ADAMTS13 indexes of individuality were 1.32 and 1.55, respectively.

Conclusion:

We report high biological variation and individuality in vWF antigenicity and activity levels. However, ADAMTS13 antigenicity and activity displayed high biological variation, but low individuality. Thus, population-based reference intervals may be useful for monitoring ADAMTS13 antigenicity and activity, but not for vWF, which displays high individuality. These findings should be considered when determining the reference interval and other clinical variables associated with ADAMTS13 and vWF levels.  相似文献   

Off line simulation system of machining processes     

Ibrahim M. Deiab  Stephen C. Veldhuis 《Journal of The Franklin Institute》2007,344(5):565-576

The primary objective for modeling of machining processes is to develop a predictive capability of machining performance in order to facilitate effective planning of machining operations. This capability leads to faster implementation, higher performance, quality at a lower cost. This comes about due to improved selection of machining parameters, optimal fixture design and the avoidance of tool failure. The simulation system presented simultaneously considers the effect of cutter geometry, the cutter's initial position errors, workpiece geometry, machine tool dynamics, and workpiece/fixture system dynamics on the machining process.The integration of all of the above in one model provides an off-line tool to simulate and optimize the machining parameters and the fixture configuration cutting both lead and production time. The modular nature of the simulation system presented allows for the study of many different machining processes. The cutting forces in this system are modeled using a mechanistic approach. NURBS curves and surfaces are utilized for the geometric modeling and simulation of the machining process. While a finite element method is used to model and analyze the workpiece/fixture dynamics. Two case studies are presented to demonstrate the practical application of the presented simulation. The first case presents the optimization of the fixture configuration of a generic automotive component. While the second case presents the results of simulations performed on a novel mill/grind machining process. This process is a combination of face milling and grinding in one operation. Some simulated results are presented along with experimental validation.  相似文献   

Optimization of fuzzy model using genetic algorithm for process control application     

Rubiyah Yusof  Ribhan Zafira Abdul Rahman  Marzuki Khalid  Mohd Faisal Ibrahim 《Journal of The Franklin Institute》2011,348(7):1717-1737

A technique for the modeling of nonlinear control processes using fuzzy modeling approach based on the Takagi-Sugeno fuzzy model with a combination of genetic algorithm and recursive least square is proposed. This paper discusses the identification of the parameters at the antecedent and consequent parts of the fuzzy model. For the antecedent fuzzy parameters, genetic algorithm is used to tune them while at the consequent part, recursive least squares approach is used to identify the system parameters. This approach is applied to a process control rig with three subsystems: a heating element, a heat exchanger and a compartment tank. Experimental results show that the proposed approach provides better modeling when compared with Takagi Sugeno fuzzy modeling technique and the linear modeling approach.  相似文献   

Quality of work life of librarians in government academic libraries in the Klang Valley, Malaysia     

Rafidah Abdul Aziz  Fuziah Mohd Nadzar  Haslinda Husaini  Asmah Maarof  Salleh Mohd Radzi  Izhairi Ismail 《International Information and Library Review》2011,43(3):149-158

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Students’ Perceptions of Their Science Teachers’ Pedagogical Content Knowledge     

Lilia Halim  Sharifah Intan Sharina Syed Abdullah  T. Subahan Mohd Meerah 《Journal of Science Education and Technology》2014,23(2):227-237

Pedagogical content knowledge (PCK) is a type of teacher knowledge to be developed by a teacher. PCK is said to contribute to effective teaching. Most studies investigated the development of PCK and its influence on students’ learning from the teachers’ perspectives. Only a limited number of studies have investigated the components of science teachers’ PCK that helped students’ learning from the perspective of students. Thus, it is the aim of this study to investigate the level of science teachers’ PCK from students’ perspective, in particular whether or not students of different achieving ability had different views of teachers’ PCK in assisting their learning and understanding. Based on the PCK research literature, six components of PCK have been identified, which were as follows: (1) subject matter knowledge, (2) knowledge of teaching strategies, (3) knowledge of concept representation, (4) knowledge of teaching context, (5) knowledge of students, and (6) knowledge of assessment in learning science. A questionnaire consisting of 56 items on a five-point Likert-type scale were used for data collection from 316 Form Four students (16 years old). One-way analysis of variance revealed that the differences in science teachers’ PCK identified by students of different achieving abilities were statistically significant. Overall, students of various academic achieving abilities considered all the components of PCK as important. The low-achieving students viewed all the components of PCK as being less important compared to the high and moderate achievers. In particular, low-achieving students do not view ‘knowledge of concept representation’ as important for effective teaching. They valued the fact that teachers should be alert to their needs, such as being sensitive to students’ reactions and preparing additional learning materials. This study has revealed that PCK of science teachers should be different for high and low-achieving students and knowledge of students’ understanding plays a critical role in shaping teachers PCK.  相似文献