The use of mineral trioxide aggregate in endodontics - status report

Mineral trioxide aggregate (MTA) is a clinical product comprising a mixture of Portland cement and bismuth oxide which is currently used as a root−filling material in dentistry. It has good biological compatibility, is capable of promoting both osteogenesis and cementogensis, and is finding increasing use in endodontic therapy. It is dimensionally stable, and provides an acceptable and durable seal for endodontically treated teeth. This article reviews the chemistry and applications of MTA, and highlights the fact that very little is currently known about the hydration chemistry, phase evolution and stability of this cement in physiological environments. However, biological effects of MTA have been well documented and are considered in detail. The article concludes that this material is a useful addition to the range of materials available for clinical application in endodontics.

A preliminary investigation of the in vitro bioactivity of white Portland cement

Freshly-mixed and partially-cured ordinary Portland cement (OPC) pastes have been shown to exhibit good biological compatibility with a range of cells and tissue-types; particularly those associated with bone formation. Formulations based on OPC have been used as dental restoratives and are now being investigated for their potential use in orthopaedic repair. Despite the current clinical interest in OPCs, very little is known about their chemistry in the physiological environment. In this respect, research to investigate aspects of the interactions between a white Portland cement (WPC) paste and simulated body fluid (SBF) has been carried out in vitro. Exposure to SBF has been found to promote the precipitation of a layer of 'bone-like' hydroxyapatite on the surface of WPC paste which underpins its ability to integrate with living tissue. The dissolution of portlandite and formation of calcite were also observed on contact with SBF.

Strategies for water pollution control in Dhaka, Bangladesh: an institutional and economic analysis

This paper presents primary data based on research carried out as part of a large World Bank project. Results from our survey show that water pollution in Dhaka watershed has reached alarming levels and is posing significant threats to health and economic activity, particularly among the poor and vulnerable. Rice productivity in the watershed area, for example, has declined by 40% in recent years and vegetable cultivation in the riverbeds has been severely damaged. We also found significant correlation between water pollution and diseases such as jaundice, diarrhoea and skin problems. It was reported that the cost of treatment of skin diseases for one episode could be as high as 29% of the weekly earnings of poor households. Given the magnitude of the contamination problem, a multi-agent stakeholder approach was necessary to analyse the institutional and economic constraints that would need to be addressed in order to improve environmental management. This approach, in turn, enabled core strategies to be developed. The strategies were better understood around three types of actors in industrial pollution, i.e. (1) principal actors, who contribute directly to industrial pollution; (2) stakeholders, who exacerbate the situation by inaction; and (3) the potential actors in mitigation of water contamination. Within a carrot-and-stick framework, nine strategies leading to the strengthening of environmental management were explored. They aim at improving governance and transparency within public agencies and private industry through the setting up of incentive structures to advance compliance and enforcement of environmental standards. Civil society and the population at large are, on the other hand, encouraged to contribute actively to the mitigation of water pollution by improving the management of environmental information and by raising public awareness.

Using WebCT to Support a Community of Practice

Reflecting a view of “teaching as both an intellectual and practical activity” the Queen’s University Bachelor of Education program has multi-week in-school practicum sessions separated by periods of on-campus course work. The expectation is that teacher candidates will bring together theory and practice as they reflect upon their daily classroom experiences. The reality often is that, while isolated from the university environment and caught up in the pressures of teaching, little deep reflection takes place. For reflection and critical examination of experience to occur, teacher candidates need to share and discuss on a daily basis their practice teaching experience. For the past few years, students in my secondary school mathematics curriculum course, through a WebCT based conference, have been provided, while away from campus, with a place for on-going sharing of teaching stories and dilemmas. In the Fall of 2004 eight-five percent of the class took part in the discussions, posting a total of 667 messages over a 9 week period. In an effort to increase the value of this practicum conference we have analysed the topic threads arising in the conversation, surveyed the participants concerning their impressions of the sharing experience, and conducted in-depth interviews with a sampling of the class. This session will present the results of this study and provide an opportunity to discuss ways in which an online discussion can support the building of community and the exchange of experience while students in professional programs are disbursed in practice/clinical settings.

WLAN Security Processor

A novel wireless local area network (WLAN) security processor is described in this paper. It is designed to offload security encapsulation processing from the host microprocessor in an IEEE 802.11i compliant medium access control layer to a programmable hardware accelerator. The unique design, which comprises dedicated cryptographic instructions and hardware coprocessors, is capable of performing wired equivalent privacy, temporal key integrity protocol, counter mode with cipher block chaining message authentication code protocol, and wireless robust authentication protocol. Existing solutions to wireless security have been implemented on hardware devices and target specific WLAN protocols whereas the programmable security processor proposed in this paper provides support for all WLAN protocols and thus, can offer backwards compatibility as well as future upgrade ability as standards evolve. It provides this additional functionality while still achieving equivalent throughput rates to existing architectures. © 2006 IEEE.

The Tragedy of Darfur and the Limits of the Responsibility to Protect

The view that states which claim sovereign status must comply with the responsibility to protect their own citizens is gaining ground in international politics. When a state is unable or unwilling to meet this responsibility, the international community is justified in intervening militarily to end widespread human rights violations. This article argues that a diffuse responsibility to protect, as currently conceived, may have important negative consequences. By using the ongoing tragedy of Darfur as an example, the article argues that the responsibility to protect is reactive and focused on the short term, contributes to the outbreak of violence and perversely provides repressed groups with a further incentive to continue their armed struggle after war breaks out. The tragedy of Darfur shows that effective protection requires case-specific policies aimed at prevention, democratization and economic and political development.

Factores determinantes del uso de Internet en la comercialización del aceite de oliva. Análisis del sector en Cataluña

Las cooperativas son entidades con una gran presencia económica y social en España, y tienen una gran influencia en la economía rural de las zonas donde están ubicadas. El principal objetivo del presente trabajo es el análisis del uso de las nuevas tecnologías por parte de las cooperativas agroalimentarias, centrándose en las productoras de aceite de oliva para determinar los principales factores que condicionan su comportamiento en la Red. En el presente estudio se analizan sus sitios web y se determina qué tipo de información aporta, tanto datos generales como datos de comercialización. A partir de los resultados obtenidos, se busca la relación que pueda existir entre el tamaño de la cooperativa, su actividad exportadora o la actividad de comercio electrónico con la presencia online, mediante una regresión logística. De esta manera podremos conocer si realmente la implantación de nuevas tecnologías en las cooperativas permite desarrollar una óptima actividad económica.

Germanium on sapphire

This paper explores the potential of germanium on sapphire (GeOS) wafers as a universal substrate for System on a Chip (SOC), mm wave integrated circuits (MMICs) and optical imagers. Ge has a lattice constant close to that of GaAs enabling epitaxial growth. Ge, GaAs and sapphire have relatively close temperature coefficients of expansion (TCE), enabling them to be combined without stress problems. Sapphire is transparent over the range 0.17 to 5.5 µm and has a very low loss tangent (a) for frequencies up to 72 GHz. Ge bonding to sapphire substrates has been investigated with regard to micro-voids and electrical quality of the Ge back interface. The advantages of a sapphire substrate for integrated inductors, coplanar waveguides and crosstalk suppression are also highlighted. MOS transistors have been fabricated on GeOS substrates, produced by the Smart-cut process, to illustrate the compatibility of the substrate with device processing. © 2008 World Scientific Publishing Company.

Photosensitiser delivery for photodynamic therapy. Part 1: Topical carrier platforms

Photodynamic therapy (PDT) is a medical treatment in which a combination of a photosensitising drug and visible light causes destruction of selected cells. Due to the lack of true selectivity of preformed photosensitisers for neoplastic tissue and their high molecular weights, PDT of superficial skin lesions has traditionally been mediated by topical application of the porphyrin precursor 5-aminolevulinic acid (ALA). Objective: This article aims to review the traditional formulation-based approaches taken to topical delivery of ALA and discusses the more innovative strategies investigated for enhancement of PDT mediated by topical application of ALA and preformed photosensitisers. Methods: All of the available published print and online literature in this area was reviewed. As drug delivery of agents used in PDT is still something of an emerging field, it was not necessary to go beyond literature from the last 30 years. Results/conclusion: PDT of neoplastic skin lesions is currently based almost exclusively on topical application of simple semisolid dosage forms containing ALA or its methyl ester. Until expiry of patents on the current market-leading products, there is unlikely to be a great incentive to engage in design and evaluation of innovative formulations for topical PDT, especially those containing the more difficult-to-deliver preformed photosensitisers.

Mixed-dimensional coupling in finite element models

In many finite element analysis models it would be desirable to combine reduced- or lower-dimensional element types with higher-dimensional element types in a single model. In order to achieve compatibility of displacements and stress equilibrium at the junction or interface between the differing element types, it is important in such cases to integrate into the analysis some scheme for coupling the element types. A novel and effective scheme for establishing compatibility and equilibrium at the dimensional interface is described and its merits and capabilities are demonstrated. Copyright (C) 2000 John Wiley & Sons, Ltd.

Journal article: Indoctrination, Secularism, Religious Liberty and the ECHR

This article examines the recent developments in religious freedom before the European Court of Human Rights Two major trends can be distinguished. On the one hand, the Court considers cases that are focused on individuals and it emphasises values such as the prevention of indoctrination, neutrality, secularism and laïcité. On the other hand, the Court deals with cases involving the compatibility of entire domestic regimes regulating religious affairs with the Convention. It will be shown that these two trends in the caselaw do not always sit happily together and have serious repercussions for religious liberty.

Dielectric constant characterization using a numerical method for the microstrip ring resonator

A new method of dielectric-constant measurement is developed. The dielectric constant epsilon(r) RF/microwave substrate is extracted by combining the microstrip ring resonator measurement with Ansoft HFSS electromagnetic simulation software. The developed method has two advantages: (i) characterization of dielectric constant versus multiple frequency points, and (ii) compatibility with electronics design automation (EDA) software tools. This characterization method can reduce the design cycle of microwave circuits and devices. (C) 2004 Wiley Periodicals, Inc.

The determinants of knowledge transfer within collaborative new product development projects

Purpose – This paper explores the factors which determine the degree of knowledge transfer in inter-firm new product development projects. We test a theoretical model exploring how inter-firm knowledge transfer is enabled or hindered by a buyer’s learning intent, the degree of supplier protectiveness, inter-firm knowledge ambiguity, and absorptive capacity. Design/methodology/approach – A sample of 153 R&D intensive manufacturing firms in the UK automotive, aerospace, pharmaceutical, electrical, chemical, and general manufacturing industries were used to test the framework. Two-step structural equation modeling in AMOS 7.0 was used to analyse the data. Findings – Our results indicate that a buyer’s learning intent increases inter-firm knowledge transfer, but also acts as an incentive for suppliers to protect their knowledge. Such defensive measures increase the degree of inter-firm knowledge ambiguity, encouraging buyer firms to invest in absorptive capacity as a means to interpret supplier knowledge, but also increase the degree of knowledge transfer. Practical implications – Our paper illustrates the effects of focusing on acquisition, rather than accessing, supplier technological knowledge. We show that an overt learning strategy can be detrimental to knowledge transfer between buyer-supplier, as supplier’s react by restricting the flow of information. Organisations are encouraged to consider this dynamic when engaging in multi-organisational new product development projects. Originality/value – This paper examines the dynamics of knowledge transfer within inter-firm NPD projects, showing how transfer is influenced by the buyer firm’s learning intention, supplier’s response, characteristics of the relationship and knowledge to be transferred.

The Effect of Risk Sensitivity on Collaborative New Product Development in a Supply Chain

The increasing risks and costs of new product development require firms to collaborate with their supply chain partners in product management. In this paper, a supply chain model is proposed with one risk-neutral supplier and one risk-averse manufacturer. The manufacturer has an opportunity to enhance demand by developing a new product, but both the actual demand for new product and the supplier’s wholesale price are uncertain. The supplier has an incentive to share risks of new product development via an advance commitment to wholesale price for its own profit maximization. The effects of the manufacturer’s risk sensitivity on the players’ optimal strategies are analyzed and the trade-off between innovation incentives and pricing flexibility is investigated from the perspective of the supplier. The results highlight the significant role of risk sensitivity in collaborative new product development, and it is found that the manufacturer’s innovation level and retail price are always decreasing in the risk sensitivity, and the supplier prefers commitment to wholesale price only when the risk sensitivity is below a certain threshold.

Use of a novel micro-fluidic device to create arrays for multiplex analysis of large and small molecular weight compounds by surface plasmon resonance

There is an increasing demand to develop biosensor monitoring devices capable of biomarker profiling for predicting animal adulteration and detecting multiple chemical contaminants or toxins in food produce. Surface plasmon resonance (SPR) biosensors are label free detection systems that monitor the binding of specific biomolecular recognition elements with binding partners. Essential to this technology are the production of biochips where a selected binding partner, antibody, biomarker protein or low molecular weight contaminant, is immobilised. A micro-fluidic immobilisation device allowing the covalent attachment of up to 16 binding partners in a linear array on a single surface has been developed for compatibility with a prototype multiplex SPR analyser.

The immobilisation unit and multiplex SPR analyser were respectively evaluated in their ability to be fit-for-purpose for binding partner attachment and detection of high and low molecular weight molecules. The multiplexing capability of the dual technology was assessed using phycotoxin concentration analysis as a model system. The parent compounds of four toxin groups were immobilised within a single chip format and calibration curves were achieved. The chip design and SPR technology allowed the compartmentalisation of the binding interactions for each toxin group offering the added benefit of being able to distinguish between toxin families and perform concentration analysis. This model is particularly contemporary with the current drive to replace biological methods for phycotoxin screening.