DSM (Canada)

Abstract The typically modest and short-lived outcomes for social influences smoking prevention programs might improve if programs were tailored to needs of high-risk youth. Longitudinal data from the Waterloo Smoking Prevention Project, Study 3 (WSPP3), were used to study degree of risk for the transition from nonsmoking to smoking during three transition periods: grade six to seven, seven to eight, and eight to nine, as a function of gender, predisposing attributes, and participation in a social influences program. Four dispositional factors were studied: rebelliousness, rejection of adult authority, personal dissatisfaction, and peer approval. Annual survey data from 3,566 youth were used in a proportional hazards model survival analysis to determine relative risk. All four dispositions significantly predicted transition for females, but only rebelliousness and rejection of authority did so for males. The degree of increased dispositional risk was consistently greater for females. Social influences programs had a modest tendency to moderate the effects of disposition. The study concludes that dispositional factors are important determinants of smoking onset and the impact of social influences programs, particularly for females. The results are discussed in terms of the evident value of theory to improve both research and practice and the potential to enhance the impact of social influences curricula by addressing individual differences.

SUMMARY The Groningen gas field in the north of the Netherlands is one of the largest gas fields in the world. Since the early 1990s induced seismicity has been recorded. The largest magnitude event observed so far was a Mw = 3.6 event at the town of Huizinge in 2012. The risk posed by the induced events urged the necessity to build comprehensive seismological models capable of explaining the spatial-temporal distribution of the recorded seismicity and evaluating the regional seismic hazard and risk. The link between the occurrence of the seismicity and pressure depletion due to the production of the gas has been firmly established. However, the construction of comprehensive seismological models as well as hazard assessment is complicated by the fact that it is difficult to distinguish between induced and clustered events (events triggered by stress transfer of preceding, neighbouring events). This paper explores the contribution of clustered populations (i.e. aftershocks) to the Groningen induced seismic catalogue based on a statistical methodology in the time–space–magnitude domain. Specifically, the distributions of space–time distances between pairs of nearest-neighbour earthquakes, referred to as cluster style, is analysed. The cluster style of the Groningen induced seismicity is found to be very diffuse and characterized by a very low proportion of fore-/aftershock sequences and swarms (∼5 per cent) and a large proportion of repeater events (∼10 per cent). In contrast to human-induced seismicity in other regions, the background seismicity rate of Groningen is very low. Temporal variations in background seismicity rates can be related to changes in fault loading rates induced by gas production. Furthermore, a significant amount of independent, coincidental events (events occurring very close in time, but long distances apart) are observed. As the large gas field is fully connected, loading of the faults occurs roughly simultaneously throughout the field. Hence, the statistical probability of events occurring very close in time, but spatially far apart is significantly larger than in areas of fluid-injection induced seismicity The significant amount of repeaters and coincidental events cause an overabundance of events at intermediate time- and space-distances. This is further enhanced by the larger location errors in the catalogue increasing the estimated space-distance for non-relocated events. The diffusivity due to this overabundance of events at intermediate time- and space-distances, and the low-proportion of true fore-/aftershocks renders the statistical method used incapable of deriving a proper mode-separation value. However, this is not unique to this method. Any statistical method aimed at resolving two populations will break down if one of the populations analysed is too small. Hence, it is advisable to use caution when distinguishing fore-/aftershocks sequences or swarms for induced seismicity where the relative proportion of clustered events may be significantly lower than for tectonic events. In addition, given the small proportion of clustering and the general uncertainty in earthquake statistics, the results of this paper indicate that a distinction for earthquake risk modelling in Groningen is unnecessary.

In this paper, the modal theory of antennas is re-visited, believing that it brings invaluable information towards facilitating the design of multi-feed multi-band antennas. First, some subtle changes are proposed to enhance the applicability of the theory. Next, using some efficient computational techniques, the proposed formulations are shown to predict, to a very high accuracy, the input impedance of any antenna under study. This greatly simplifies the antenna problem and focuses design efforts on finding the appropriate complex resonance frequency to cover a required band. Finding the appropriate feed location is then a matter of extracting the corresponding impedance map for this antenna through simple field manipulations.

The Dutch National Model was revised during 1995 and 1996 in a task group consisting of representatives of the relevant institutes and universities in the Netherlands. The advanced model 'STACKS' was chosen as the model of departure. From an evaluation some modifications were agreed, in particular for the surface layer and the treatment of directional wind shear in the model. The resulting Reference Model will serve as a calibration standard for a simplified version meant for regulatory purposes.

The fabrication of geotextiles and geomembranes offers advantages in deployment speed and quality over field-installed materials. Traditional fabrication methods have joined one strip of material at a time to create extended panels. Recently, the authors have completed the development of a new fabrication machine that joins five strips of material at a time to create fabricated panels for large projects. The new machine is capable of both welding geomembranes and sewing of high strength geotextiles. This machine was specifically designed to address the problems of scale that need to be dealt with in oil sands tailings ponds. This paper will outline the development of this unique machine and present two case histories; one using high strength sewn geotextile, and one using welded geomembrane. The paper also highlights some exciting new equipment technology and innovation developed specifically for meeting the containment needs of larger scale projects.

ABSTRACT We announce the complete genome sequence of Stutzerimonas stutzeri strain MBI-RS3, a rifampicin-resistant derivative found in a mixed bacterial culture at the University of Waterloo. This strain enhances plant growth via nitrogen fixation, phosphate solubilization, and the production of trehalose and phytohormones.

Summary As underground hydrogen storage (UHS) is expected to play a key role in future renewable energy systems, understanding the potential geomechanical risks, such as induced seismicity, is essential. Therefore, this study aims to assess the probability of induced seismicity associated with the prospect of large-scale UHS plans. We commence by developing simulation models with increasing complexity, starting from the basic characteristics of the salt formation, salt cavern, and operational conditions, and progressing to the inclusion of structural features within the salt formation as well as in the overburden and sideburden. A 2D finite element simulator is used to incorporate deformation and simulate creep behaviour, which is subsequently coupled with a rate-and-state Coulomb threshold model to compute the seismicity rate from stress changes. The developed framework accounts for the geological and mechanical characteristics of the heterogeneities that influence local stress fields, allowing us to identify conditions that may increase seismic risk or enhance stability.

In recent years, the number of newly discovered systems that bacteria use to combat bacteriophages is increasing at an impressive rate. To obtain mechanistic insights into several antiphage systems identified in previous studies, we isolated 66 phage escape mutants which had become insensitive to 13 distinct, plasmid-encoded lactococcal phage resistance systems (i.e. Rhea, Kamadhenu, Rugutis, Audmula, PARIS, type II CBASS, Septu, AbiA, AbiB, AbiD/F, AbiG, AbiJ, AbiP). Genome analysis of these phage escape mutants identified a total of 15 mutated genes. Six of the encoded proteins appear to activate specific antiphage systems. Furthermore, AbiA escape mutants were found to be insensitive to AbiJ, while distinct antiphage systems (AbiG and AbiP) were observed to be activated by a major phage tail protein, indicating mechanistic commonalities. PARIS homologues encoded by members of different bacterial genera appear to share similar sensing mechanisms, whereas our data indicate mechanistic differences between Septu homologues from different genera. Based on our escape mutant sequence analysis, previously predicted domains, and experimental data using the purified endolysin of phage c2, we propose that Audmula modifies the cell wall of the host bacterium, delaying cell lysis and release of progeny phages, protecting the host cell by a heretofore unknown mode of action. The obtained advances in our understanding of lactococcal antiphage mechanisms provide fundamental insights into phage-host interactions, which undoubtedly benefits the dairy industry but may also be useful for biotechnological or biomedical applications.

Construction and cyclic operation of multi-cavern systems within salt pillars present notable geomechanical challenges, including subsidence due to cavern convergence, pressure interactions between caverns, leakage and induced seismicity. Monitoring stations in the northeast of the Netherlands have consistently reported small seismic events (local magnitudes ≥ -2), the underlying physics of which are poorly understood. As the operational activity in the salt domes is expected to scale up due to the prospects of underground hydrogen storage (UHS) in salt caverns, it is crucial to investigate the mechanisms underlying the observed seismic events. More importantly, it is essential to quantify the probability of induced seismic events due to the increase in UHS projects.This study aims to assess the probability of induced seismicity associated with the prospect of large-scale hydrogen storage (UHS) plans. To this end, it is crucial to understand, analyse, and quantify the mechanisms behind induced seismicity observed due to the salt cavern leaching and cyclic storage operations within the Dutch salt domes. As a necessary bench-mark step for our study, it is essential to explain the occurrence of small-scale events for the existing caverns. We commence by constructing simplified yet meaningful simulation models, which include the basic characteristics of the salt formation, salt cavern, operational conditions, and the presence of structural features in the salt formation as well as in the over- and side-burden. Subsequently, the deformation evolution of the system is quantified and the impact of uncertainties on stress and deformation is assessed. The simulation model will be coupled to a seismogenic source model to compute the spatio-temporal development of the seismic activity in the model due to the deformation evolution.