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There is a need for more students to be interested in science, technology, engineering, and mathematics (STEM) careers to advance U.S. competitiveness and economic growth. A consensus exists that improving STEM education is necessary for motivating more students to pursue STEM careers. In this study, a survey to measure student (grades 4–6) attitudes toward STEM and STEM careers was developed and administered to 662 students from two STEM‐focused and three comprehensive (non‐STEM‐focused) schools. Cronbach's alphas for the whole survey and subscales indicated a high internal consistency. Statistically significant difference in means between students attending the STEM‐focused and comprehensive schools on the two subscales of the survey and the overall survey were found. However, the explained variance for these results was approximately 1%. The survey is a useful tool to assess efficacy of STEM education programs on student attitudes toward STEM and STEM careers.  相似文献   
2.
With the increasing emphasis on integrating engineering into K‐12 classrooms to help meet the needs of our complex and multidisciplinary society, there is an urgent need to investigate teachers' engineering‐focused professional development experiences as they relate to teacher learning, implementation, and student achievement. This study addresses this need by examining the effects of a professional development program focused on engineering integration, and how teachers chose to implement engineering in their classrooms as a result of the professional development. 198 teachers in grades 3–6 from 43 schools in 17 districts participated in a yearlong professional development program designed to help integrate the new state science standards, with a focus on engineering, into their teaching. Posters including lesson plans and student artifacts were used to assess teachers' engineering practices and the implementation in their classrooms. Results indicated that the majority of the teachers who participated in the professional development were able to effectively implement engineering design lessons in their classrooms suggesting that the teachers' success in implementing engineering lessons in their classroom was closely related to the structure of the professional development program.  相似文献   
3.
The current study presents the results of the activity of radionuclides in spa waters, and evaluates their radiological influences on the population consuming these waters in the Central and Eastern Black Sea regions of Turkey. Since these waters are used for therapy and consumption purposes unconsciously, their radiological impact on the people was computed by taking into consideration the annual intake through ingestion of 226Ra, 232Th, 40K, 137Cs and 222Rn. The mean activities were estimated to be 11.35 for gross alpha, 6.23 for gross beta, 2.96 for 226Ra, 0.42 for 232Th, 0.069 for 137Cs, 0.19 for 40K, and 267 Bq L–1 for 222Rn, respectively. The estimated effective doses from spa water were found to be 49.77 µSv a–1 (226Ra), 5.95 µSv a–1 (232Th), 0.07 µSv a–1 (137Cs), 0.83 µSv a–1 (40K) and 56.03 µSv a–1 (222Rn). These values were evaluated and compared with related verified values from literature. Also, physico-chemical characterizations of spa water samples considered in the current study were investigated. This study would be useful for consumers and official authorities for the assessment of radiation exposure risk due to usage of the considered spa waters.  相似文献   
4.
Hierarchical linear models have become a familiar method for accounting for a hierarchical data structure in studies of science and mathematics achievement. This paper illustrates the use of cross‐classified random effects models (CCREMs), which are likely less familiar. The defining characteristic of CCREMs is a hierarchical data structure defined by multiple random factors at higher levels. We illustrate CCREMs using data for approximately 10,000 students from more than 250 high schools who attended one of 27 four‐year postsecondary institutions. The appropriate use of CCREMs helps to ensure unbiased estimates of effects and credible inferences.  相似文献   
5.
The evaluation of cell wellness is an important task for molecular biology research. This mainly comprises the assessment for morphology and viability of culturing cells. Annexin V-Propidium iodide counterstaining has been currently one of the common and easy methods to discriminate apoptotic and necrotic cell profiles. The method is operated by fluorescence-based detection of counterstain via laser beam-employed instruments including flow cytometer, fluorescence microscope and automated cell counter. The detection is primarily conducted based on the same principle; however the efficiency of instruments may vary. Here we evaluated the efficiency of those instruments for the clear-cut detection of cell death through various mammalian and microalgae cell lines. To the best of our knowledge, this is the first study revealing comparative analyses of apoptotic and necrotic cells in mammalian and microalgae cells using Annexin V-PI counterstain detected by flow cytometer, fluorescence microscope and automated cell counter. Fluorescence microscope and cell counter instruments were also tested and compared for the traditional trypan blue-based cell viability detection performance. For these, cell death was induced by UV-irradiation and/or bee venom for mammalian (pancreatic cancer, metastatic breast cancer and mouse fibroblasts) and microalgae cells (Chlorella vulgaris), respectfully. Findings postulated that automated cell counter and fluorescence microscopy revealed similar patterns for the detection by both counterstain and trypan blue in mammalian cells. Interestingly, flow cytometry did provide an accurate and significant detection for only one mammalian cell line when UV-treatment was followed by routine Annexin V-Propidium iodide counterstaining. Unlike, only flow cytometry revealed a significant change in the detection of death of microalgae cells by Annexin V-Propidium iodide method, but both Annexin and conventional trypan blue methods were not applicable for the automated cell counter and microscopic detections for microalgae cells. The related outputs propose that the obtaining reliable quantitation strongly depends on cell type and instruments used. These suggest the necessity of optimization and validation endeavors before any cell death detection initiative. The analytical outcomes present insights into detailed assessment of cell death detection of eukaryotic cells and provide a direction to researchers to consider.  相似文献   
6.
In this study, the raw materials and their structural properties were analyzed in synthetic polymer pipe production by the following events: 1) The effect of extruder processes to dynamic-mechanical properties of polyethylene (PE) and polypropylene (PP) pipes in pipe production; 2) The effect of the fiber direction on dynamic-mechanical properties and extruder materials; 3) The heat process on welding during the pipe production and the effect of polymer structure on welding duration; 4) Physical properties and structural changes of pigmented PE and PP raw materials. 5) The relationship between dynamic-mechanical properties of polymers with thermodynamic and kinetic concepts and effect of temperature. The results (that were) derived after several measurements are as follows: 1) The best stability properties were observed on the pipe samples which have same fibre direction. In samples with opposite and vertical fiber directions the stability properties are 30% lower. 2) The maximum dynamic-mechanical properties of the pipe samples were observed when the extruder temp. Is 463 k. These properties were lower in the pipe compared to the samples taken from the inner and outer part of the extruder. For the sample during this time the concentration of the oxygen groups are at the lowest and amorphous regions are at the highest level. These results prove that the temperature, the pressure and the cooling rate of the material taken from the extruder have too much effect on polymer structure. 3) Welding duration is investigated without changing the fibrillar structure. The best welding conditions have been obtained in case of deformation graphs with minimum areas. The results can be explained with the difference in polymer structures at different temperatures during pipe manufacturing process. 4) The σ, τ, γ values differ greatly in the samples taken from different companies (∼ 50%). The analyses of IR spectra and microphotographs show that this difference depends on the differences of the polymer structures and the initial data.  相似文献   
7.
The purpose of this study was to develop, scale, and validate assessments in engineering, science, and mathematics with grade appropriate items that were sensitive to the curriculum developed by teachers. The use of item response theory to assess item functioning was a focus of the study. The work is part of a larger project focused on increasing student learning in science, technology, engineering, and mathematics (STEM)‐related areas in grades 4–8 through an engineering design‐based, integrated approach to STEM instruction and assessment. The fact that the assessments are available to school districts at no cost, and represent psychometrically sound instruments that are sensitive to STEM‐oriented curriculum, offers schools an important tool for gauging students' understanding of engineering, science, and mathematics concepts.  相似文献   
8.
A new analytical method for the simultaneous determination of two natural hormones (progesterone and estrone) and two selected endocrine disrupter compounds (EDCs) (diltiazem and carbamazepine (Cbz)) was developed by liquid chromatography electrospray ionization tandem mass spectrometry (LC-ESI-MS/MS) after pre-concentration with solid phase extraction (SPE). Influent and effluent samples taken from five different wastewater treatment plants throughout Turkey namely Hurma/Antalya, Lara/Antalya, Kemer-1 and Kemer-2 and METU/Ankara were analyzed for their EDCs contents under the optimum conditions. All of the parameters in the pre-concentration step were optimized and the best recoveries for all compounds of interest were achieved at pH 7 (about 100%). Progesterone was not detected in any of the treatment plants while diltiazem was found in all samples with the exception of Lara effluent.  相似文献   
9.
Current reform efforts in science education around the world call on teachers to use integrated approaches to teach science. As a part of such reform efforts in the United States, engineering practices and engineering design have been identified in K–12 science education standards. However, there is relatively little is known about effective ways of teaching science through engineering design. The study explores the approaches or strategies used by a sixth grade science teacher to teach science and engineering in an integrative manner. Classroom observations, teacher interview, and student surveys were used to study the features of engineering integration implemented by the teacher and the changes in student interest in science and engineering by participating in an engineering design‐based science unit. Findings suggest that the teacher explicitly included practices and core ideas from engineering and science; used an engaging, motivating engineering challenge; and provided students with opportunities to be autonomous. Students engaged in the activities in the engineering unit and their interest level slightly increased. The results suggest that the three strategies that the teacher used to teach engineering and science are important foundations of integrated science and engineering education.  相似文献   
10.
Nationally, there is a steadily increasing emphasis on the improvement of STEM education. This includes the integration of STEM subjects that have been traditionally taught separately, making it critical that prospective STEM educators are equipped to teach using integrated STEM approaches. Connected, an important challenge is providing preservice STEM teachers with experiences in which they can develop an understanding of how to optimize learning through integrated STEM instruction. A potentially effective way to foster this conceptualization is through video analysis of integrated STEM practices. To investigate this possibility, here we present a semester‐long study focused on engaging preservice STEM teachers with observing, analyzing, and reflecting about instructional STEM practices through a video‐based intervention. Findings suggest that viewing and reflecting on integrated STEM practices may enhance preservice STEM teachers' conceptions of integrated STEM approaches, representing a practical method of preservice STEM teacher professional development.  相似文献   
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