A Viscoelastic Model for the Long‐Term Deflection of Segmental Prestressed Box Girders

Most of segmental prestressed concrete box girders exhibit excessive multidecade deflections unforeseeable by past and current design codes. To investigate such a behavior, mainly caused by creep and shrinkage phenomena, an effective finite element (FE) formulation is presented in this article. This formulation is developed by invoking the stationarity of an energetic principle for linear viscoelastic problems and relies on the Bazant creep constitutive law. A case study representative of segmental prestressed concrete box girders susceptible to creep is also analyzed in the article, that is, the Colle Isarco viaduct. Its FE model, based on the aforementioned energetic formulation, was successfully validated through the comparison with monitoring field data. As a result, the proposed 1D FE model can effectively reproduce the past behavior of the viaduct and predict its future behavior with a reasonable run time, which represents a decisive factor for the model implementation in a decision support system.     

Antibacterial activity of four glass ionomer cements used in atraumatic restorative treatment

The in vitro antibacterial activity of four glass ionomer cements (Fuji IX, Ketac Molar, Vidrion R and Vitromolar) indicated for Atraumatic Restorative Treatment (ART) was studied against strains of bacteria involved in the development of oral diseases, Streptococcus mutans, Streptococcus sobrinus, Lactobacillus acidophilus and Actinomyces viscosus. The agar plate diffusion test was used for the cultures, which included chlorhexidine as a positive control. The results demonstrated that all the cements evaluated presented antibacterial activity. Based on the results of this study, it can be concluded that Fuji IX and Ketac Molar presented the most effective antibacterial activity considering the ART approach.     

Costs and benefits of smoking cessation aids: making a case for public reimbursement of nicotine replacement therapy in Australia

Background

Tobacco smoking is the leading preventable cause of morbidity and mortality in Australia and other developed countries. Of the pharmacological aids that are available for smoking cessation, bupropion (Zyban SR) is eligible for public reimbursement on the Australian Pharmaceutical Benefits Scheme (PBS), whereas nicotine replacement therapy (NRT) is not. Information on the cost‐effectiveness and financial impact of public reimbursement of these strategies can better inform debate about their inclusion or exclusion in public reimbursement schemes.

Objective

To estimate the cost‐effectiveness of bupropion and NRT, and the potential financial impact of public reimbursement of NRT in Australia.

Design

A cost‐effectiveness analysis using a deterministic Markov model, and cost per disability‐adjusted life year (DALY) averted over a lifetime as the outcome measure.

Population

Current smokers, motivated to quit, in Australia in 2000.

Interventions

(1) NRT; (2) bupropion; and (3) a combined strategy using bupropion as the first‐line treatment and NRT in those who fail to quit smoking or have adverse reactions to bupropion.

Results

Quitting smoking can increase life expectancy of current smokers by 1–7.6 years depending on age at cessation and sex. Providing bupropion to current smokers who are motivated to quit would cost A$7900 (95% uncertainty interval A$6000 to A$10 500) for each DALY averted; NRT patches would cost A$17 000 (A$9000 to A$28 000) for each DALY averted, with similar results even if used as a second‐line treatment following initial failure to quit using bupropion. If 6% of current smokers were to use NRT following inclusion on the PBS, this would result in an annual cost of A$40–110 million to the PBS depending on the listed price.

Conclusions

Compared with other drugs included on the PBS, bupropion and NRT are both highly cost‐effective smoking cessation interventions, and including NRT on the PBS would have a moderate financial impact. Given the sizeable health burden of smoking, and the large individual benefits of quitting smoking, increasing the availability of alternative aids and uptake of these strategies through public reimbursement would be a positive and rational step towards further reducing tobacco‐related disease burden in Australia and other countries where NRT is currently not subsidised.Tobacco smoking is the largest preventable cause of morbidity and mortality in Australia and other developed countries. Despite projected declines in tobacco‐related diseases in line with decreasing prevalence, tobacco is still expected to be among the leading causes of disease burden in 2016.¹ Worldwide, it is the second highest cause of death and fourth highest cause of disease burden.Effective policies to control tobacco use are crucial. Although preventing individuals from starting smoking is an important aim of tobacco control, cessation in current smokers is also critical. As nicotine is highly addictive, smokers often require assistance to maintain abstinence. Modestly effective cessation aids are available, including pharmacological agents, such as bupropion (Zyban SR) and nicotine replacement therapy (NRT).^2,3Australia has implemented many strong tobacco control policies. The retail price of tobacco in Australia is among the top three worldwide.⁴ Advertising and promoting tobacco products has been totally banned, pictorial pack warnings have recently been implemented, opportunities to smoke cigarettes in public places are severely limited and there is legislation in place forcing an upcoming ban of smoking in bars and hotels.^5,6,7 Despite these measures, nearly one in five Australian adults still smoke daily, indicating the need for further strategies to encourage cessation.⁸In 1995, the Australian government rejected a recommendation by the Pharmaceutical Benefits Advisory Committee to include NRT on the public reimbursement scheme—the Pharmaceutical Benefits Scheme (PBS).⁹ By contrast, bupropion was made available on the PBS in February 2001.¹⁰ The continued exclusion of NRT and inclusion of bupropion may or may not be a rational decision. Valid and comparable information on the cost‐effectiveness and financial implications of including these interventions on the PBS are important inputs into this debate.The cost‐effectiveness of both NRT and bupropion has been studied previously.² A lack of consistency in the methods of these studies, however, makes comparisons difficult, and the context‐specific nature of inputs into cost‐effectiveness analyses such as disease outcomes means that these results may not be applicable to the Australian setting.^2,11 This study aims to evaluate the cost‐effectiveness of NRT and bupropion in the Australian context, as well as the potential financial impact of including NRT on the PBS.     

Square wave voltcoulometry: a tool for the study of strongly adsorbed redox molecules

A new multipotential pulse technique called square wave voltcoulometry (SWVC), based on the analysis of the difference of converted charge signals obtained between two successive half-cycles when a square wave potential is applied, is developed to study charge-transfer processes taking place in electroactive monolayers. The use of SWVC presents the advantage of giving rise to a peak-shaped response, which evolves to a charge plateau at high square wave pulse amplitudes, from which the total surface excess and the formal potential can be immediately measured for quasi-reversible and reversible processes. This characteristic represents its main advantage versus other multipotential step techniques, which lead to a negligible current under reversible conditions. The formal potential of the electroactive systems can be measured from the peak potential of the SWVC curves, even for quasi-reversible behavior. Moreover, the non-faradic effects on the response can be easily evaluated and avoided as is demonstrated in this paper. Experimental verification of the theoretical predictions is given for reversible and quasi-reversible systems.     

Development and validation of safety climate scales for mobile remote workers using utility/electrical workers as exemplar

Purpose

The objective of this study was to develop and test the reliability and validity of a new scale designed for measuring safety climate among mobile remote workers, using utility/electrical workers as exemplar. The new scale employs perceived safety priority as the metric of safety climate and a multi-level framework, separating the measurement of organization- and group-level safety climate items into two sub-scales. The question of the emergence of shared perceptions among remote workers was also examined.

Method

For the initial survey development, several items were adopted from a generic safety climate scale and new industry-specific items were generated based on an extensive literature review, expert judgment, 15-day field observations, and 38 in-depth individual interviews with subject matter experts (i.e., utility industry electrical workers, trainers and supervisors of electrical workers). The items were revised after 45 cognitive interviews and a pre-test with 139 additional utility/electrical workers. The revised scale was subsequently implemented with a total of 2421 workers at two large US electric utility companies (1560 participants for the pilot company and 861 for the second company). Both exploratory (EFA) and confirmatory factor analyses (CFA) were adopted to finalize the items and to ensure construct validity. Reliability of the scale was tested based on Cronbach's α. Homogeneity tests examined whether utility/electrical workers’ safety climate perceptions were shared within the same supervisor group. This was followed by an analysis of the criterion-related validity, which linked the safety climate scores to self-reports of safety behavior and injury outcomes (i.e., recordable incidents, missing days due to work-related injuries, vehicle accidents, and near misses).

Results

Six dimensions (Safety pro-activity, General training, Trucks and equipment, Field orientation, Financial Investment, and Schedule flexibility) with 29 items were extracted from the EFA to measure the organization-level safety climate. Three dimensions (Supervisory care, Participation encouragement, and Safety straight talk) with 19 items were extracted to measure the group-level safety climate. Acceptable ranges of internal consistency statistics for the sub-scales were observed. Whether or not to aggregate these multi-dimensions of safety climate into a single higher-order construct (overall safety climate) was discussed. CFAs confirmed the construct validity of the developed safety climate scale for utility/electrical workers. Homogeneity tests showed that utility/electrical workers’ safety climate perceptions were shared within the same supervisor group. Both the organization- and group-level safety climate scores showed a statistically significant relationship with workers’ self-reported safety behaviors and injury outcomes.

Implications

A valid and reliable instrument to measure the essential elements of safety climate for utility/electrical workers in the remote working situation has been introduced. The scale can provide an in-depth understanding of safety climate based on its key dimensions and show where improvements can be made at both group and organization levels. As such, it may also offer a valuable starting point for future safety interventions.     

Selective excitation of LP01 mode in multimode fiber using solid-core photonic crystal fiber

To address the overwhelming bandwidth increase in premise backbones, an attractive alternative for selective mode excitation in multimode fiber (MMF) using solid-core photonic crystal fiber (PCF) is presented. The power coupling efficiency, differential mode delay, and bit-error rate performance of several structural designs of solid-core PCF waveguides are investigated for the selective excitation of mode LP01 in a MMF. The achieved coupling efficiency into mode LP01 is above 90% for PCF profiles with seven rings.     

Planar interface between a chiral medium and a metal: Surface wave excitation

Abstract

The feasibility of excitation of surface waves at a single planar interface is demonstrated numerically. The interface separates a chiral medium from an isotropic and achiral medium; this latter could be a metal. Both media are characterized by their dielectric permittivity and their magnetic permeability. The chiral is also specified by its chiral parameter. As a result it is found that surface wave excitation is theoretically possible. The range of values of the chiral parameter in which surface waves can be excited is very narrow and depends on the constants of both media. The condition that at least one of the media must be dissipative seems to be necessary to have excitation. To obtain these results, the dispersion relation of the interface is deduced. Chiral media are described by the Drude–Born–Fedorov constitutive equations. The exact dependence of the fields on the chiral parameter is kept in the computation.