酪蛋白磷酸肽-无定形磷酸钙、不同玷污层的处理和储存时间对牙本质粘接的影响(英文)

研究目的:评价含有酪蛋白磷酸肽-无定形磷酸钙(CPP-ACP)的再矿化剂Tooth Mousse(TM)的使用、不同玷污层的处理以及样本储存时间对牙本质粘接微拉伸性能的影响。研究方法:将牙本质样本分成保留玷污层组和用15%乙二胺四乙酸(EDTA)处理90秒去除玷污层组。每组根据是否使用TM处理再分亚组。每个亚组分别用三种不同的粘结剂(两步法自酸蚀Clearfil SE Bond(CSE)、一步法自酸蚀G-Bond(GB)和全酸蚀Adper Single Bond 2(SB))与牙本质样本粘接,分别经过3天和6个月的去离子水储存。样本进行切割微拉伸测试并通过扫描电镜分析断裂界面模式。重要结论:经过再矿化剂TM预处理,可以减少牙齿的敏感性,并且对于这三种粘结系统经过长时间储存后的粘结性能没有影响。EDTA的处理对于长期储存的粘结性能没有显著影响。额外的TM和EDTA对短期(3天)粘接力会有效应,但对长期(6个月)的粘接力没有影响。     

Identification of Core Competencies for an Undergraduate Food Safety Curriculum Using a Modified Delphi Approach

Identification of core competencies for undergraduates in food safety is critical to assure courses and curricula are appropriate in maintaining a well‐qualified food safety workforce. The purpose of this study was to identify and refine core competencies relevant to postsecondary food safety education using a modified Delphi method. Twenty‐nine experts representing food safety professionals in academia, government, and industry were given 2 rounds of questionnaires that specified initial food safety competencies, core domains, and subdomains. Competencies were defined as a set of skills, knowledge, and abilities that correlate to success of a trainee. The framework for which competencies were classified consisted of (1) core domains, defined as broad food safety subjects; and (2) subdomains, or more specific food safety subjects. The expert panel used a 5‐point Likert scale with an acceptance criterion, or consensus, of 75%, with a rating of “4” or greater. After 2 rounds of questionnaires and revisions from the expert panel, 5 core domains were established: (1) Food Production, Manufacturing, Retail, and Consumer; (2) Foodborne Hazards; (3) Public Health; (4) Legislation and Policy; and (5) Communication and Education. Specific responses from the experts highlighted areas in which further curriculum revision would be beneficial. This study provides a framework for the development of a vetted, standardized undergraduate food safety curriculum. The Delphi method, with its inclusion of professionals representing various sectors of food safety, provided relevant perspectives for curriculum design, and also allowed participants the opportunity to contribute to the education of future food safety professionals.     

Accelerometry to Assess Preschooler's Free-Play: Issues with Count Thresholds and Epoch Durations

This study examines the utility of current accelerometer threshold definitions and epoch durations for physical activity intensity classification in preschool-aged children. Using video footage of children engaged in active play, directly observed 1-sec epoch physical activity intensity scores were derived from a modified version of the Children's Activity Rating Scale, averaged into 15-sec epochs (corresponding to the accelerometer scale), and compared to accelerometer-measured classifications. Overall, 6,540 individual 1-sec epochs were captured and classified from six children, yielding 429 time-matched 15-sec epoch physical activity intensity classifications from both methods. Children participated in 25 distinct physical activity behaviors and spent 75% of free-play in one intensity level for ≤5 sec. The maximum amount of time spent participating in an activity prior to changing activity intensity was 98 sec. Agreement between methods was generally poor (overall: κ = .22; child range: κ = .00 to .66), and the difference between methods was significantly asymmetrical (McNemar's test overall: p = .01). Accelerometer thresholds and epoch durations used to classify preschoolers' physical activity intensity yielded biased estimates in the current study. Further investigation is necessary to establish optimal physical activity measurement methods with this population.     

Identification of Accelerometer Nonwear Time and Sedentary Behavior

Abstract

This study was designed to investigate the swimming endurance trainability of smokers as compared to nonsmokers. Nonsmokers (N = 47) and smokers (N = 34) of college age were selected from intermediate swimming classes and timed while swimming distances of 100 yd. and 200 yd. prior to participation in an 8-week training program. After 4 weeks of training, swimming times were again recorded for these same distances. At the end of eight weeks, swimming times were taken for distances of 100, 200, and 400 yards. The mean changes of both smokers and nonsmokers during the pretraining to 4-week period, the 4-week to 8-week period, and the pretraining to 8-week period were all significant at the .05 level. However, no significant differences were found between the mean swimming times of smokers and nonsmokers for any of the pretraining, 4-week, or 8-week distances.     

Mocking God and Celebrating Satan: Parodies and Profanities in Philip Pullman’s His Dark Materials

Given its stance against organised religion, it is perhaps not surprising that Philip Pullman’s award-winning trilogy His Dark Materials has, alongside the plaudits and praise, invited controversy and debate. Jacobs (The Weekly Standard, 2000), for instance, views the “anti-Christian” theme in Pullman’s work as both misleading and dishonest, whilst Hitchens (The Mail on Sunday, 2002) denounces it as atheistic “propaganda.” Of central concern to these critics, and others, is the impact of Pullman’s heretical understandings on impressionable young readers. I would suggest that such concern implies a somewhat questionable homogenisation of young readers, and fails to recognise the empowering potential residing in Pullman’s text. Indeed, by drawing on Mikhail Bakhtin’s theory of “carnival,” a literary mode which subverts official culture through laughter and role reversals, it can be argued that far from indoctrinating the reader or promoting uncontested atheistic understandings, the heretical disruptions and inversions in Pullman’s religious theme encourage an altogether more positive and plural response.     

Education research and educational practice: The qualities of a close relationship

The relationship between education practice and education research has a long history. In modern times, education practice and its relation to education research has been central to debates about the nature and quality of education as an academic discipline in universities. This article reports an empirical study that investigated a new instantiation of the practice–theory debate: ‘close-to-practice’ research in education. The research sought to (a) define and further articulate the concept of close-to-practice research and (b) provide reflections on the quality of close-to-practice research. The orientation of the work reported in this article is informed by theory on traditions of knowledge in the organisation of education that have contributed to the development of education as an academic discipline. The main section of the article reports the findings of the empirical study. The research design was a rapid evidence assessment (REA), and a series of interviews with education researchers whose experiences were highly relevant to understanding of close-to-practice research issues. The conclusions of the research are reported in relation to how close-to-practice research might be defined, including in relation to quality, but also implications for education as a discipline in universities subject to nationwide assessments of quality.     

An instructional design framework for authentic learning environments

The instructional technology community is in the midst of a philosophical shift from a behaviorist to a constructivist framework, a move that may begin to address the growing rift between formal school learning and real-life learning. One theory of learning that has the capacity to promote authentic learning is that of situated learning. The purpose of this three-part study was first, to identify critical characteristics of a situated learning environment from the extensive literature base on the subject; second, to operationalize the critical characteristics of a situated learning environment by designing a multimedia program that incorporated the identified characteristics; and third, to investigate students' perceptions of their experiences using a multimedia package based on a situated learning framework. The learning environment, for preservice teachers, comprised a multimedia program on assessment in mathematics together with recommended implementation conditions for the classroom. Eight students were observed and interviewed to explore their perceptions of the situated learning environment. Findings suggest that the use of the situated learning framework provided effective instructional design guidelines for the design of an environment for the acquisition of advanced knowledge. Since 1992, as a Senior Instructional Designer, she has worked principally in multimedia and Web-based projects. He has been teaching with, and researching innovative uses of, instructional technologies in secondary schools and universities for the past 20 years. The authors would like to thank Professor Tom Reeves for his encouragement and support, and to acknowledge the significant role he has played in the development of our ideas and research direction.     

Global-local divides and ontological politics: feminist STS perspectives on mobile learning for community health workers in Kenya

ABSTRACT

This theoretical paper argues that Feminist Science and Technology Studies (FSTS) can help advance the emancipatory project in critical Ed Tech research. To support this claim, we deploy Tsing’s concept of ‘scale-making projects’ (2005. Friction: An Ethnography of Global Connection. Princeton, NJ: Princeton University Press) to connect ‘global’ narratives to ‘local’ users in a mobile learning project for Kenyan health workers. Drawing from this exemplar case, we discuss more broadly how FSTS provides useful theory and methods for tracing the trans-national power relations of digital technologies ‘on the ground’. The paper concludes by advocating for new forms of emancipatory Ed Tech research – ones framed not only within oppositional pairings such as ‘global’ versus ‘local’, but which elucidate how binaries themselves are constituted through far-flung trans-national arrays of sociomaterial practice.     

Portable X-ray fluorescence analysis of pesticides in the textile collection at the German Historical Museum,Berlin

The majority of the objects found in the textiles collection at the German Historical Museum in Berlin have been treated with different biocides at various points in the past. Prior to this study, the presence of organochlorinated pesticides in rooms and storage cabinets had already been proven in an analysis of air samples that employed gas chromatography and mass spectroscopy. To estimate the risks these toxins pose to both collections and museum staff, we conducted a field study with the help of a portable X-ray fluorescence spectrometer. In this study, we present an attempt at a reliable quantitative analysis. In addition to chlorine, other potentially hazardous elements such as lead, arsenic, and mercury were found in the majority of the objects. In some cases, however, it has to be taken into account that the detected elements might have originated from manufacturing processes rather than biocide treatments. Such knowledge is a crucial prerequisite to proper risk prediction.