Influence of casein phosphopeptide-amorphous calcium phosphate application,smear layer removal,and storage time on resin-dentin bonding

The aim of this study is to evaluate the influence of Tooth Mousse (TM) application, smear layer removal, and storage time on resin-dentin microtensile bond strength (μTBS). Dentin specimens were divided into two groups: (1) smear layer covered; (2) smear layer removed using 15% EDTA for 90 s. In each group, half the specimens were treated once with TM for 60 min. After bonding procedures using a two-step self-etching adhesive (Clearfil SE Bond (CSE); Kuraray Medical, Tokyo, Japan), an all-in-one adhesive (G-Bond (GB); GC Corp, Tokyo, Japan), and a total-etch adhesive (Adper Single Bond 2 (SB); 3M ESPE, St. Paul, MN, USA), the specimens were stored for 3 d or 6 months in deionized water at 37 °C, and μTBS was tested and analyzed. With the exception of SB (no TM application) and GB, the μTBS was significantly increased for CSE and SB using EDTA pre-conditioning and 3 d of storage (P≤0.001). Bond strength of GB decreased significantly when using EDTA (3 d storage, P<0.05). TM application only increased the μTBS of GB (no EDTA) and SB (with EDTA) after 3 d (P≤0.02). Comparing the adhesives after 3 d of storage, CSE exhibited the greatest μTBS values followed by GB and SB (P≤0.02). The factors of adhesive, EDTA, and TM did not show any significant impact on μTBS when specimens were stored for 6 months (P>0.05). The additional application of TM and EDTA for cavity preparation seems only to have a short-term effect, and no influence on μTBS of dentin bonds after a period of 6 months.     

Toppling hierarchies? Media and information literacies,ethnicity, and performative media practices

This article suggests how we should study media and information literacies (MIL) and do so at a time, when young people nurture these literacies through multiple media practices and across spaces of learning. Our basic argument is this: in order to gain a robust knowledge base for the development of MIL we need to study literacy practices beyond print literacy and numeracy, and we need to study these practices beyond formal spaces of learning. The argument is unfolded with particular focus on ethnic minority youth since this group routinely figures as under-achieving in studies of school literacy, such as Programme for International Student Assessment. Based on a brief overview of literacy studies in view of digitization and a critical examination of recent studies of youthful media practices and ethnicity, the argument is illustrated through an empirical analysis that draws on results from a nationally representative survey of media uses among Danes aged 13–23 years. The analysis demonstrates that ethnic minority youth offer the most serious challenge to existing literacy hierarchies found in formal education. We discuss the implications of these results for educational policy-making and for future research on MIL, advocating inclusive approaches in terms of media for learning and spaces of learning.     

Technology use and mathematics teaching: teacher change as discursive identity work

Teacher change towards developing competences for technology use in mathematics teaching has been the focus of current educational reforms worldwide. However, a considerable amount of research denotes the extent to which teachers resist a full integration of technology in mathematics classrooms. The present paper is based on an ethnographic study and focuses on how mathematics teachers – as they participate in an intensive training course – perform identity work whilst collectively articulating meanings concerning the potential of technology-based mathematics learning. By means of discourse theory, we analyse how they try to fix meaning as they engage and interact with varied discourses of ‘change’. Our findings indicate that mathematics teachers' attempts to articulate meaning are organised around discourses that concern directly societal and learning issues of technology use in mathematics teaching.     

In the physics class: university physics students’ enactment of class and gender in the context of laboratory work

This article explores how the doing of social class and gender can intersect with the learning of science, through case studies of two male, working-class university students’ constitutions of identities as physics students. In doing so, I challenge the taken-for-granted notion that male physics students have an unproblematic relation to their chosen discipline, and nuance the picture of how working-class students relate to higher education by the explicit focus on one disciplinary culture. Working from the perspective of situated learning theory, the interviews with the two male students were analysed for how they negotiated the practice of the physics student laboratory and their own classed and gendered participation in this practice. By drawing on the heterogeneity of the practice of physics the two students were able to use the practical and technological aspects of physics as a gateway into the discipline. However, this is not to say that their participation in physics was completely frictionless. The students were both engaged in a continuous negotiation of how skills they had learned to value in the background may or may not be compatible with the ones they perceived to be valued in the university physicist community.     

Gender performativity in physics: affordances or only constraints?

In this forum we engage in a dialogue with Allison Gonsalves’s paper ‘“Physics and the girly girl—there is a contradiction somewhere”: Doctoral students’ positioning around discourses of gender and competence in physics’. In her paper Gonsalves uses a sociocultural approach to examine women doctoral students’ stories about becoming physicists. In doing so her paper focuses on how discourses of masculinity and femininity can create available and unavailable positions for the women students. In this dialogue we do a parallel reading of two of the student narratives presented by Gonsalves, using Judith Butler’s (1990) concept of discursive agency as a means to more explicitly bring the affordances for women identity constitution offered by their localized physicist context to the fore, rather focusing on its, often more visible, constraints.     

A note on the construction of test panels for the spectral imaging of paintings

The construction and examination of test panels is an ad hoc procedure, necessary for every spectral imaging study of paintings. Despite the common features, almost every scientific team follows a different way of construction. Furthermore, many of these approaches are not adequately documented in the relevant papers. Failure to use common language and practice leads to confusion about properties of materials and paint layers that have been overall examined by the scientists, as well as the validity of the results and their exploitation in several conservation applications. The present theoretical approach points out the need for common protocols for the construction of test panels and draws general principles as a flow chart on which they should be based.     

Intellectual property and optimal copyright protection

Copyright protection, or more generally, intellectual property rights, can be regarded as a means for the stimulation of production of information goods. This paper analyses the basic problem of production and dissemination of information and the role of copyright protection as an incentive for the producers of creative works. Using a simple model, it is shown that not only a cause for limiting the extent of copyright protection does exist, but that also an argument for a minimum level of protection can be found. Even optimal copyright protection, given the restriction that production and dissemination of information goods has to be co-ordinated by a market mechanism, however, does not lead to a first-best (allocatively efficient) solution. Hence, the judgment that copyright protection is the best solution to the basic problem can be grounded only on a comparative institutional approach.Indeed, one has ample reason to despair of finding a legal tenet that governs the rights of authors and artists. There exists no legal principle by which the state is forced to grant to authors a right in their creation. They cannot claim any right thereupon. This is not to say that the state shall not award such a right. On the contrary, there is every reason to treat them like the most favoured workers, as they deliver a work that is more robust than ashlar, and bring food that does not decay...