Bond Strength and Etching Pattern of Adhesive Systems to Enamel: Effects of Conditioning Time and Enamel Preparation

Statement of the problem: The performance of self-etch systems on enamel is controversial and seems to be dependent on the application technique and the enamel preparation. Purpose of the Study: To examine the effects of conditioning time and enamel surface preparation on bond strength and etching pattern of adhesive systems to enamel. Materials and Methods: Ninety-six teeth were divided into 16 conditions (N = 6) in function of enamel preparation and conditioning time for bond strength test. The adhesive systems OptiBond FL (Kerr, Orange, CA, USA), OptiBond SOLO Plus (Kerr), Clearfil SE Bond (Kuraray, Osaka, Japan), and Adper Prompt L-Pop (3M ESPE, St. Paul, MN, USA) were applied on unground or ground enamel following the manufacturers` directions or doubling the conditioning time. Cylinders of Filtek Flow (0.5-mm height) were applied to each bonded enamel surface using a Tygon tube (0.7 mm in diameter; Saint-Gobain Corp., Aurora, OH, USA). After storage (24 h/37 degrees C), the specimens were subjected to shear force (0.5 mm/min). The data were treated by a three-way analysis of variance and Tukey`s test (alpha = 0.05). The failure modes of the debonded interfaces and the etching pattern of adhesives were observed using scanning electron microscopy. Results: Only the main factor ""adhesive"" was statistically significant (p < 0.001). The lowest bond strength value was observed for OptiBond FL. The most defined etching pattern was observed for 35% phosphoric acid and for Adper Prompt L-Pop. Mixed failures were observed for all adhesives, but OptiBond FL showed cohesive failures in resin predominantly. Conclusions: The increase in the conditioning time as well as the enamel pretreatment did not provide an increase in the resin-enamel bond strength values for the studied adhesives. CLINICAL SIGNIFICANCE The surface enamel preparation and the conditioning time do not affect the performance of self-etch systems to enamel. (J Esthet Restor Dent 20:322-336, 2008)

Identification of lift-off mechanism failure for salt drill-in drilling fluid containing polymer filter cake through adsorption/desorption studies

Drilling fluid`s contact with the productive zone of horizontal or complex wells can reduce well productivity by fluid invasion in the borehole wall. Salted drilling drill-in fluid containing polymers has often been applied in horizontal or complex petroleum wells in the poorly consolidated sandstone reservoirs of the Campos basin, Rio de Janeiro, Brazil. This fluid usually consists of natural polymers such as starch and xanthan gum, which are deposited as a filter cake on the wellbore wall during the drilling. Therefore, the identification of a lift-off mechanism failure, which can be detachment or blistering and pinholing, will enable formulation improvements. increasing the chances of success during filter cake removal in open hole operations. Likewise, knowledge of drill-in drilling fluid adsorption/desorption onto sand can help understand the filter cake-rock adhesion mechanism and consequently filter cake lift-off mechanism failures. The present study aimed to identify the lift-off failure mechanism for this type of fluid filter cake studying adsorption/desorption onto SiO(2) using solutions of natural polymers, lubricants, besides the fluid itself. Ellipsometry was employed to measure this process. The adsorption/desorption studies showed that the adsorbed layer of drilling fluid onto the walls of the rock pores is made up of clusters of polymers, linked by hydrogen bonds, which results in a force of lower cohesion compared to the electrostatic interaction between silica and polymers. Consequently, it was found that the most probable filter cake failure mechanism is rupture (blistering and pinholing), which results in the formation of ducts within the filter cake. (C) 2009 Elsevier B.V. All rights reserved.

Determination of the susceptibility of Rhipicephalus (Boophilus) microplus (Acari: Ixodidae) to ivermectin and fipronil by Larval Immersion Test (LIT) in Uruguay

Rhipicephalus (Boophilus) microplus is an important cattle pest in Uruguay, and the law regulates its control. It is resistant to organophosphates, synthetic pyrethroids and, as recently discovered, to fipronil. Resistance to macrocyclic lactones (MLs) and amitraz have not been documented; however, veterinarians and farmers have reported treatment failures. The objective of the present work was to study the susceptibility of cattle tick strains from different Uruguayan counties to ivermectin (IVM) and fipronil by using the Larval Immersion Test (LIT). The Mozo strain was used as the susceptible reference strain. From 2007 to 2009, twenty-eight tick populations were collected from different cattle farms with and without history of IVM or fipronil use. A probit analysis estimated dose-mortality regressions, lethal concentrations (LC), and confidence intervals. The resistance ratio (RR) was determined at the LC(50) and LC(90) estimates. To classify a tick population in relation to resistance, three categories based on a statistical analysis of LC and RR between field populations and Mozo strains were defined: susceptible (no differences), incipient resistance (differences and RR(50) < 2) and resistant (differences and RR(50) >= 2). Eighteen field populations were tested with IVM and five of them presented a RR(50) range between 1.35 and 1.98 and the LC(50/90), which is statistically different from the Mozo strain (incipient resistance). However, the RR(90) increases >= 2 in four of the populations, confirming that tick resistance to IVM is emergent. The low RR values obtained could be a result of a low frequency of treatments with IVM. Twenty-seven tick populations were tested with fipronil and six were diagnosed as resistant according to the LIT. Cross-resistance was not observed between fipronil and IVM on these tick populations. The current study presents different R. (B.) microplus populations with an incipient resistance to IVM, and indicates that the fipronil tick resistance is restricted to certain areas in Uruguay. (c) 2011 Elsevier B.V. All rights reserved.

An introduction to CLERP 9

An Introduction to CLERP 9, as its title suggests, is aimed at providing legal practitioners and students with an overview of Australia’s corporate governance reforms, but more than that, it also analyses the events that led to the reforms and provides practical examples of how the amendments will change corporate practices.

The book begins by defining what is generally meant by good corporate governance. It then outlines the relevant recent events that led to introduction and commencement of the Corporate Law Economic Reform Program (Audit Reform and Corporate Disclosure) Act 2004 (CLERP 9) on 1 July this year. The corporate failures of Enron and HIH – and subsequent Royal Commission – in 2001, and the failure of private auditing firms to warn of their client’s problems are well summarised.

As well as the Sarbanes Oxley Act of 2002, the US equivalent to CLERP 9, the establishment of the ASX Corporate Governance Council and the release of its Principles of Good Corporate Governance and Best Practice Recommendations are examined in detail.

The book covers all the chief changes, including the new rules for audit independence, financial disclosure, whistleblowing, remuneration for directors and executives and continuous disclosure.

Throughout, the book provides a comprehensive and easy to understand commentary on how the CLERP 9 Act alters the Corporations Act 2001 and the ASIC Act 2001, as well as highlighting important changes that affect present practice. For example, the author notes that under the auditor independence rules, when an audit firm contravenes an independence requirement, liability is placed on all members and directors of the audit firm, not just the lead auditor responsible for a particular audit. This, he says, is aimed at introducing a “culture of compliance”.

As well as providing a quick reference guide to how the CLERP 9 Act amends the Corporations and ASIC Acts at the beginning of the book, the table at the end of the book comparing the corporate governance reforms in the US, UK and Australia will be very useful for practitioners trying to make sense of how multinational clients might be liable across different jurisdictions.

Resistance: a medium for the successful implementation of technological innovation

Resistance to change has long been recognised as a critically important factor that can influence the success or otherwise of implementing any 'technological innovation. Information technology (IT) focused interventions, for example, business process re-engineering (BPR) and enterprise resource planning (ERP), are often quoted as examples of costly failures, with reported levels of dissatisfaction ·with strategic IT investments ranging from 20-70 percent and that employee resistance was to blame. The intention of this chapter is to rethink resistance. The author suggests that resistance remains to this day a complex, multifaceted phenomenon that continues to affect the outcomes of change, both negatively and positively. Although research has procured a solid understanding of resistance- and the benefits that can accrue to an organisation through its proper utilisation, it appears that the classical adversarial approach remains the dominant means ofmanaging resistance because such learning is not reflected in modern management techniques. The author concludes that as companies in every industry are now translating the power and possibilities 0/ e-business into strategic and operational realities, newapproaches in change managementare required to help organisations to understand the complex dynamics o/technological innovation and especially the multifaceted nature o/resistance.

Analysis of a large-scale IT outsourcing "failure": what lessons can we learn?

Much of the research that has been carried out into outsourcing is based on relatively successful case studies. Yet drawing inferences from case studies when those with largely negative outcomes rarely see the light of day represents a significant problem. When negative cases are systematically unrepresented, there is less opportunity to subject theory to scrutiny. This chapter goes some way towards redressing this trend, by reporting on a large scale “selective” outsourcing arrangement that has been publicly described as a failure — the Australian Federal Government’s “whole of government” IT infrastructure outsourcing initiative. This initiative, originally promoted as likely to lead to a billion dollar saving, was abandoned early in 2001, after a damning public report by the Australian Auditor General. However, a detailed study of the initiative suggests that the “failure” occurred despite the project adhering to many of the recommended guidelines for successful outsourcing that had been derived from earlier case analysis. The findings have important implications for decision makers confronted with outsourcing choices. The study suggests that the risks of outsourcing are often downplayed, or ignored in the rush to reap the expected benefits. The study also suggests that expectations of savings from outsourcing IT are often substantially higher than those that have been empirically confirmed in the field. Decision makers are advised that key assumptions about costs, savings, managerial effort, and the effects of outsourcing on operational performance might be incorrect, and to plan for their outsourcing activity accordingly. They should pay particular attention to coordination and transaction costs, as these tend to be overlooked in the business case. These costs will be magnified if “best in breed” multiple-vendor outsourcing is chosen, and if contracts are kept short. Decision-makers are also warned of the difficulties they are likely to have at the end of an outsourcing contract if there is not a large and robust pool of alternative vendors willing to bid against the incumbent.

Comparing alternate teaching styles to teach computing skills to girls in their English classes

Low female participation rates in computing are a current concern of the education sector. To address this problem an intervention was developed — computing skills were introduced to girls in their English classes using three different teaching styles: peer tutoring, cross-age tutoring and teacher instruction (control). The sample comprised 136 girls from Years 8 and 10 from a single-sex government school. A pre-test post-test quantitative design was used. To describe the students perspectives, qualitative data were collected from six focus groups conducted with 8–10 students — one from each of the six classes. It was predicted that cross-age tutoring would yield more positive effects than peer tutoring which, in turn, would yield more positive effects than traditional teacher instruction as assessed by achievement on class tasks and attitudes towards computing. The hypothesis was not supported by the quantitative analysis, however in the qualitative data cross-age tutoring was appraised more favourably than peer tutoring or teacher instruction. The latter was the least preferred condition due to: (1) inefficiency; (2) difficulty understanding teachers' explanations; and (3) lack of teacher knowledge. Problems with the implementation of the intervention identified in the focus groups were teacher differences, system failures, missed classes, lack of communication, and selection of computing activities. Practical suggestions were provided relevant to the introduction of cross-age tutoring and the use of computers within secondary level English classes.

Financial characteristics of Australian initial public offerings from 1994 to 1999

A variety of financial characteristics of Australian initial public offerings (IPOs) for the period 1994-1999 are explored. A number of previous Australian studies have investigated the initial day underpricing and longer term underperformance of IPOs and this study updates those papers. This paper partitions the IPO data into no liability/limited liability; share option/no share option; underwriter option/no underwriter option and dividend reinvestment/no dividend reinvestment characteristics to better understand the types of IPOs that list on the Australian Stock Exchange. The data supports the findings of previous studies in that IPOs are underpriced at the time of listing and underperform the market in the first year following their listing.

Fault detection service architecture for grid computing systems

The ability to tolerate failures while effectively exploiting the grid computing resources in an scalable and transparent manner must be an integral part of grid computing infrastructure. Hence, fault-detection service is a necessary prerequisite to fault tolerance and fault recovery in grid computing. To this end, we present an scalable fault detection service architecture. The proposed fault-detection system provides services that monitors user applications, grid middlewares and the dynamically changing state of a collection of distributed resources. It reports summaries of this information to the appropriate agents on demand or instantaneously in the event of failures.

The importance of audit committees in initial public offerings

This paper follows Balvers, McDonald and Miller (1988), and Beatty (1989), who find lower underpricing in Initial Public Offerings (IPOs) when prestigious auditors are used to attest to the IPO's financial statements. Australian IPOs are not obliged to nominate audit firms in the prospectus, but often identify that they will have audit committees so as to assist in more appropriate corporate governance. This paper analyzes if IPOs identifying the existence of audit committees in the prospectus have a lower underpricing return. While our findings are consistent with previous studies concluding that both the size of the new issue and the use of an underwriter are important ingredients in the level of underpricing return, the inclusion of an audit committee in the prospectuses has actually increased underpricing returns. The capital market may view the audit committee identification with some skepticism.

Information disclosure and corporate governance in listed companies in China: from Yinguangxia to Enron

China's path to the development of a modern securities market has not been a smooth one. This article argues that efforts to impose Western securities market models on China have been fraught with difficulty. This is especially clear from the adoption of information disclosure principles and practices. While the integrity of disclosure practices is a fundamental element in maintaining investors' confidence in securities markets, disclosure practices need to be attuned to China '5 systemic features, especially in regard to its legal structure and rules. Market failures, such as the collapse of Enron in the United States, have led to a realisation that US disclosure models have their own difficulties and that these should not be uncritically used. This article reviews recent Chinese law andpractice (using the Yinguangxia false disclosure scandal as an example) in this area and calls for the adoption of a more critical approach towards the use of Western models with particular regard to China's own distinctive pathways of reform.

The importance of intangible assets in initial public offerings

This paper follows Beatty and Ritter (1986), who argue that lower uncertainty about the value of an initial public offering (IPO) reduces the 'need' for the underpricing of an IPo. Australian IPOs often identify the existence of intangible assets such as goodwill, licenses, brand names, trademarks, patents and capitalized research and development costs in the prospectus. This paper analyses if IPOs identifying the existence of such intangible assets in the prospectus might reduce uncertainty about their valuation and hence allow a lower underpricing return. While the reporting of intangible assets such as goodwill and license costs in the prospectus are not significant ingredients in the level of underpricing, the identification and valuation of intangible assets such as brand names, trademarks, patents and capitalized research and development costs is significant in reducing the level of underpricing return. Our findings are also consistent with previous studies concluding that both the size of the new issue and the use of an underwriter are important in the level of underpricing return.

An efficient replicated data management approach for peer-to-peer systems

The availability of critical services and their data can be significantly increased by replicating them on multiple systems connected with each other, even in the face of system and network failures. In some platforms such as peer-to-peer (P2P) systems, their inherent characteristic mandates the employment of some form of replication to provide acceptable service to their users. However, the problem of how best to replicate data to build highly available peer-to-peer systems is still an open problem. In this paper, we propose an approach to address the data replication problem on P2P systems. The proposed scheme is compared with other techniques and is shown to require less communication cost for an operation as well as provide higher degree of data availability.

Toward self discovery for an autonomic cluster

Nondedicated clusters are currently at the forefront of the development of high performance computing systems. These clusters are relatively intolerant of hardware failures and cannot manage dynamic cluster membership efficiently. This report presents the logical design of an innovative self discovery service that provides for automated cluster management and resource discovery. The proposed service has an ability to share or recover unused computing resources, and to adapt to transient conditions autonomically, as well as the capability of providing dynamically scalable virtual computers on demand.

An analysis of the environment as a means of assessing training needs in the Insurance industry in Australia

In the five years leading up to 2002 there were many significant changes in
the insurance industry in Australia that brought about a range of training
needs. These training needs arose from matters as diverse as mergers, increased competition, corporate failures, and legislative changes. This study includes findings from a survey of the insurance industry in Australia in the period 2000·2002 asa means of exploring the importance of the environment (marketplace) in predicting aspects of training needs. The findings demonstrate that an environmental analysis approach to training needs analysis can predict the type of training that organisations will subsequently need to provide, and thus has the potential to produce a more accurate assessment of training needs in the future. The findings also have application to more broadly based businesses operating in the financial services sector of the economy