Phospholipid fatty acid biomarkers in a freshwater periphyton community exposed to uranium: discovery by non-linear statistical learning

Phospholipid fatty acids (PLFA) have been widely used to characterize environmental microbial communities, generating community profiles that can distinguish phylogenetic or functional groups within the community. The poor specificity of organism groups with fatty acid biomarkers in the classic PLFA-microorganism associations is a confounding factor in many of the statistical classification/clustering approaches traditionally used to interpret PLFA profiles. In this paper we demonstrate that non-linear statistical learning methods, such as a support vector machine (SVM), can more accurately find patterns related to uranyl nitrate exposure in a freshwater periphyton community than linear methods, such as partial least squares discriminant analysis. In addition, probabilistic models of exposure can be derived from the identified lipid biomarkers to demonstrate the potential model-based approach that could be used in remediation. The SVM probability model separates dose groups at accuracies of ∼87.0%, ∼71.4%, ∼87.5%, and 100% for the four groups; Control (non-amended system), low dose (amended at 10 μg U L⁻¹), medium dose (amended at 100 μg U L⁻¹), and high dose (500 μg U L⁻¹). The SVM model achieved an overall cross-validated classification accuracy of ∼87% in contrast to ∼59% for the best linear classifier.     

A viscosity correction factor for shear-thinning liquid flows in safety valves

At the moment there is lack in the existing standards of a sizing procedure for media of more complex rheological behavior than Newtonian. A formulation for the generalized Reynolds number to calculate the viscosity correction factor and size safety valves for the flows of shear-thinning media is proposed in this work. The various formulations in the literature are validated in their accuracy of estimation of the mass flow rates of aqueous solutions of polyvinylpyrrolidone. Among them the generalized Reynolds number defined using the wall viscosity of the annulus between the seat and the disk gives the highest accuracy without overestimating the measured mass flow rates. On the base of these results this generalized Reynolds number is recommended for introduction in the next review of both ISO 4126-1 Part 1 and API 520 for the sizing of safety valves for shear-thinning media.     

Twenty-five years of HAZOPs

The HAZOP or hazard and operability study was developed by ICI over 25 years ago and is in wide use today throughout the world. The technique is intended to review, in a formalized manner, the design of a system such as a chemical process production plant to detect potential problems in the operation of the system. The system has been extended for use on all types of production, storage and distribution units. Experience in the use of hazard studies has lead to the development of a phased approach with three distinct design phases.     

Exploring the perceived influence of safety management practices on project performance in the construction industry

Although safety management is known to be vital to construction projects, very few studies have solicited views from construction practitioners about their perceptions of which safety management practices (SMPs) are important to construction projects and related to project performance. An empirical study was undertaken in Hong Kong in order to shed more light on this topic. In the study, the importance levels of 15 popular SMPs and five project performance criteria were rated by 232 respondents. An exploratory factor analysis was conducted, and three SMP categories - information, process, and committees - were extracted. Of these three categories, safety management process was perceived by the construction practitioners as being the most important, followed by safety management information and committees. Moreover, the effect of the three SMP categories on a composite project performance variable was tested using hierarchical regression analysis. Results indicate that the “information” and “committees” categories were associated with project performance positively and significantly. One of the major conclusions of the study is that the construction industry has paid relatively less attention to safety management committees, which were empirically analyzed as having a strong perceived impact on project performance. In order to improve project performance, construction companies should promote the criticality of safety management committees.     

The nature and structure of workers' trust in management

This paper presents a theoretical and empirical analysis of the nature of trust at work. Use is made of the facet approach to generate a definitional framework of trust, and this is proposed as a theoretical basis for the analysis of the structural characteristics of trust. Hypotheses regarding the relations between the definitional framework and empirical observations were tested by applying Smallest Space Analysis to analyse data collected from a sample of 398 colliery workmen, using questionnaires developed on the basis of the faceted definition. The results demonstrate strong support for the definitional framework suggested for the concept of trust and its construct validity. The results also suggest a possible distinction workers make between trust and mistrust and, between the specifics of activities to do with the job itself versus managers in general. © 1997 John Wiley & Sons, Ltd.     

Dealing with SMEs as a whole in OHS issues: Warnings from empirical evidence

Not surprisingly it has been shown that there are higher accident rates and larger magnitudes in Small- and Medium-sized Enterprises (SMEs) if compared with the case of the larger ones. Some studies suggest that SMEs have serious problems aggravated by limited access to human, economic and technological resources. Moreover, it is now acknowledged that methods developed specifically for Large Enterprises (LEs) cannot be simply transferred to smaller enterprises. Although the debate concerning essentially the size of the enterprises and their corresponding accident rates is ongoing, very little attention is paid to the difference between the Micro- (MiEs), the Small- (SEs), and the Medium-sized Enterprises (MEs). Indeed, in most of the cases, SMEs are bundled together and considered as a whole, in opposition to LEs. In some cases SEs and MEs are studied separately, but only the difference in terms of accident rates is highlighted. Instead, important information in terms of performance and organizational, cultural and economic differences between MiEs, SEs and MEs exist. Within the implementation of the E-merging project (financed by the Italian National Institute for Insurance against Occupational Accidents – INAIL), some differences have been identified on the basis of two existing data sources.