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.     

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...     

Relation of resemblance in information retrieval

A method using the amount of semantic information of query terms as weight in a fuzzy relation of resemblance is presented. The relation can be used to partially order documents in decreasing order of resemblance with the query. Large operational bibliographic data bases are used to test the validity of the approach.     

Das MINERVA-Projekt: Datenbankselektion für Peer-to-Peer-Websuche

Zusammenfassung In diesem Artikel wird MINERVA pr?sentiert, eine prototypische Implementierung einer verteilten Suchmaschine basierend auf einer Peer-to-Peer (P2P)-Architektur. MINERVA setzt auf die in der P2P-Welt verbreitete Technik verteilter Hash-Tabellen auf und benutzt diese zum Aufbau eines verteilten Verzeichnisses. Peers in unserem Ansatz entsprechen v?llig autonomen Benutzern mit ihren lokalen Suchm"oglichkeiten, die bereit sind, ihr lokales Wissen und ihre lokalen Suchm?glichkeiten im Rahmen einer Kollaboration zur Verfügung zu stellen. Wir formalisieren unsere Systemarchitektur und beschreiben das zentrale Problem einer effizienten Suche nach vielversprechenden Peers für eine konkrete Anfrage innerhalb des Verbundes. Wir greifen dabei auf existierende Methoden zurück and passen diese an unseren Systemkontext an. Wir pr?sentieren Experimente auf realen Daten, die verschiedene dieser Ans?tze vergleichen. Diese Experimente zeigen, dass die Qualit?t der Ans?tze variiert und untermauern damit die Wichtigkeit und den Einfluss einer leistungsstarken Methode zur Auswahl guter Datenbanken. Unsere Experimente deuten an, dass eine geringe Anzahl sorgf?ltig ausgew?hlter Datenbanken typischerweise bereits einen Gro?teil aller relevanten Ergebnisse des Gesamtsystems liefert.

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This paper presents the MINERVA project that protoypes a distributed search engine based on P2P techniques. MINERVA is layered on top of a Chord-style overlay network and uses a powerful crawling, indexing, and search engine on every autonomous peer. We formalize our system model and identify the problem of efficiently selecting promising peers for a query as a pivotal issue. We revisit existing approaches to the database selection problem and adapt them to our system environment. Measurements are performed to compare different selection strategies using real-world data. The experiments show significant performance differences between the strategies and prove the importance of a judicious peer selection strategy. The experiments also present first evidence that a small number of carefully selected peers already provide the vast majority of all relevant results.

CR Subject Classification H.4,H.3.3,H3.4