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Fatma Emel Kocak Bahadir Ozturk Ozben Ozden Isiklar Ozlem Genc Ali Unlu Irfan Altuntas 《Biochemia medica : ?asopis Hrvatskoga dru?tva medicinskih biokemi?ara / HDMB》2015,25(3):430-438
Introduction
Total 25-hydroxyvitamin D [25(OH)D] is the most reliable indicator of vitamin D status. In this study, we compared two automated immunoassay methods, the Abbott Architect 25-OH Vitamin D assay and the Roche Cobas Vitamin D total assay, with the liquid chromatography-tandem mass spectrometry (LC-MS/MS).Materials and methods
One hundred venous blood samples were randomly selected from routine vitamin D tests. Two of the serum aliquots were analyzed at the Abbott Architect i2000 and the Roche Cobas 6000’s module e601 in our laboratory within the same day. The other serum aliquots were analyzed at the LC-MS/MS in different laboratory. Passing-Bablok regression analysis and Bland-Altman plot were used to compare methods. Inter-rater agreement was analyzed using kappa (κ) analysis.Results
The Roche assay showed acceptable agreement with the LC-MS/MS based on Passing-Bablok analysis (intercept: -5.23 nmol/L, 95% CI: -8.73 to 0.19; slope: 0.97, 95% CI: 0.77 to 1.15). The Abbott assay showed proportional (slope: 0.77, 95% CI: 0.67 to 0.85) and constant differences (intercept: 17.08 nmol/L; 95% CI: 12.98 to 21.39). A mean bias of 15.1% was observed for the Abbott and a mean bias of -14.1% was observed for the Roche based on the Bland-Altman plots. We found strong to nearly perfect agreement in vitamin D status between the immunoassays and LC-MS/MS. (κ: 0.83 for Abbott, κ: 0.93 for Roche) using kappa analysis.Conclusion
Both immunoassays demonstrated acceptable performance, but the Roche Cobas assay demonstrated better performance than the Abbott Architect in the studied samples.Key words: 25-Hydroxyvitamin D, chromatography, immunoassay, methods, tandem mass spectrometry 相似文献2.
Bahadir Namdar 《International Journal of Science Education》2013,35(7):993-1023
Scientific modeling has been advocated as one of the core practices in recent science education policy initiatives. In modeling-based instruction (MBI), students use, construct, and revise models to gain scientific knowledge and inquiry skills. Oftentimes, the benefits of MBI have been documented using assessments targeting students’ conceptual understanding or affective domains. Fewer studies have used assessments directly built on the ideas of modeling. The purpose of this study is to synthesize and examine modeling-oriented assessments (MOA) in the last three decades and propose new directions for research in this area. The study uses a collection of 30 empirical research articles that report MOA from an initial library of 153 articles focusing on MBI in K-12 science education from 1980 to 2013. The findings include the variety of themes within each of the three MOA dimensions (modeling products, modeling practices, and meta-modeling knowledge) and the areas of MOA still in need of much work. Based on the review, three guiding principles are proposed for future work in MOA: (a) framing MOA in an ecology of assessment, (b) providing authentic modeling contexts for assessment, and (c) spelling out the connections between MOA items and the essential aspects of modeling to be assessed. 相似文献
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Using multiple representations and argumentation are two fundamental processes in science. With the advancements of information communication technologies, these two processes are blended more so than ever before. However, little is known about how these two processes interact with each other in student learning. Hence, we conducted a design-based study in order to distill the relationship between these two processes. Specifically, we designed a learning unit on nuclear energy and implemented it with a group of preservice middle school teachers. The participants used a web-based knowledge organization platform that incorporated three representational modes: textual, concept map, and pictorial. The participants organized their knowledge on nuclear energy by searching, sorting, clustering information through the use of these representational modes and argued about the nuclear energy issue. We found that the use of multiple representations and argumentation interacted with each other in a complex way. Based on our findings, we argue that the complexity can be unfolded in two aspects: (a) the use of multiple representations mediates argumentation in different forms and for different purposes; (b) the type of argumentation that leads to refinement of the use of multiple representations is often non-mediated and drawn from personal experience. 相似文献
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H. Bahadir Yanik 《Educational Studies in Mathematics》2011,78(2):231-260
This article reports an analysis of 44 prospective middle school mathematics teachers’ pre-existing knowledge of rigid geometric
transformations, specifically the geometric translations. The main data source for this study was the participants’ responses
to the tasks that were presented during semi-structured clinical interviews. The findings of the study revealed that prospective
teachers had difficulties recognizing, describing, executing, and representing geometric translations. The results indicated
that teacher candidates held various views about the geometric translations: (1) translation as rotational motion, (2) translation
as translational motion, and (3) translation as mapping. The results further revealed various interpretations of the vector
that defines translations: (1) vector as a force, (2) vector as a line of symmetry, (3) vector as a direction indicator, and
(4) vector as a displacement. Although many of the teacher candidates interviewed knew that a vector has a magnitude and a
direction, this knowledge did not generally lead them to conclude that vectors define translations. 相似文献
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The purpose of this study was to investigate the types, sources, and cognitive levels of tasks that included real-life situations used in science and mathematics lessons in the classrooms of two 5th-grade teachers at an urban elementary school in Turkey. A qualitative approach was used to analyze data that included classroom observations, teacher interviews, and document collection. Results showed that in contrast to mathematics instruction, science instruction often relied on real-life situations in explaining scientific concepts. Mathematics lessons mainly included textbook-oriented real-life situations. On the other hand, the science lessons relied primarily on teacher- and student-oriented real-life contexts. While science instruction included personal, social, global, and historical situations, mathematics instruction involved only personal and educational situations in making real-life connections. Results further showed that, in contrast to science instruction, many of the real-life tasks used by the teacher in the mathematics lessons were cognitively demanding. 相似文献
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Computer-supported collaborative learning (CSCL) environments provide learners with multiple representational tools for storing, sharing, and constructing knowledge. However, little is known about how learners organize knowledge through multiple representations about complex socioscientific issues. Therefore, the purpose of this study was to investigate learners’ knowledge organization (KO) through multiple representations in a CSCL environment. We designed a learning unit on nuclear energy and implemented it with a group of 20 college students. The participants used a web-based hypertext KO platform that incorporated three representational modes: textual, pictorial, and concept map. The platform interlinked learners’ knowledge entries based on similar keywords. Utilizing mixed methods research we analyzed the individual entries and the knowledge base to determine KO both at the individual and the collective levels. We found that the density of the knowledge base was high; the learners mostly benefited from their text- and concept map-based entries, though the picture-based entries were also an important means for connecting entries with similar content and hence creating a dense knowledge base. Our results suggest that KO with multiple representations can create a more comprehensive knowledge base. Using distinct analytical approaches will allow CSCL researchers to better identify KO both at the individual and collective levels. 相似文献
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Bahadir Namdar 《Research in Science & Technological Education》2018,36(4):440-462
Background Global climate change (GCC) has become one of the most debated socio-scientific issues after an increase in media attention. Recently, there have also been several studies describing students’ and teachers’ alternative conceptions about GCC. Therefore, designing learning environments at the college level that focus on accurate conceptions of GCC has become important in order for pre-service teachers to correct their alternative conceptions. There are, however, a limited number of studies that aim to both increase pre-service teachers’ knowledge about these issues and explore their perceptions of teaching this subject.
Purpose The purpose of this study was to investigate the effects of inquiry-based activities on pre-service teachers’ knowledge about GCC and their perceptions of teaching this subject.
Sample The participants were 102 pre-service middle school mathematics and science teachers who were enrolled in an environmental education course.
Design and methods A one group pre-test–post-test design was employed to identify changes after pre-service teachers engaged in a learning unit on GCC. The inquiry-based GCC unit was implemented during the spring semester at a public university in northeastern Turkey. The unit was implemented over seven sessions. Data were collected through two questionnaires: the ‘GCC content questionnaire’ and the ‘perceptions of teaching GCC questionnaire’. Each questionnaire was administered both before and after implementation of the unit. Content questionnaire responses were analyzed using a paired-samples t-test. Responses to the perceptions of teaching questionnaire were analyzed using inductive open coding.
Results Results indicated that after the implementation the pre-service teachers significantly improved their understanding of GCC across all items in the content questionnaire, saw several benefits of and challenges about teaching GCC, and perceived themselves as better prepared to teach about GCC in their future classrooms.
Conclusions Teacher education programs should integrate inquiry-based GCC instruction to increase pre-service teachers’ knowledge as well as their preparedness to teach about this important planetary issue. 相似文献
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Using a dog's paw as a basis for numerical representation, sixth grade students explored how to count and regroup using the dog's four digital pads. Teachers can connect these base-4 explorations to the conceptual meaning of place value and regrouping using base-10. 相似文献
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