Pop-Up Structures and the Fracture Pattern in the Balsam Lake Area, Southern Ontario

An examination of topographic lineaments detectable in Landsat TM images and measurement of joints in outcrop in the Balsam Lake area reveals a systematic bedrock fracture pattern with three principal sets oriented 091°, 027°, and 152°. The 027° trend is parallel to a major aeromagnetic anomaly, the Niagara-Pickering Linear Zone (NPLZ), which underlies the Balsam Lake area and is thought to mark the sub-Paleozoic continuation of the Proterozoic Central Metasedimentary Belt Boundary Zone (CMBBZ). Possible origins of the main joint sets due to Acadian (091° set), Alleghanian (152° set) and St. Lawrence rift system tectonics (091° and 027° sets) are discussed. En-echelon pop-up structures have a mean principal trend of 118°. They displace Lake Algonquin paleobeaches, suggesting formation less than 12,500 years ago. The orientation of the pop-up structures is subnormal to the current in situ maximum horizontal stress direction, SHmax (020°), and is parallel to members of the 091° joint set, indicating possible nuclea-tion on favourably-oriented pre-existing joints. These pop-ups are the only features in the Balsam Lake area with strong evidence for a neotectonic age.L'examen des linéaments topographiques repérables sur les images Landsat (TM) et la mesure des diaclases dans un affleurement de la région de Balsam Lake révèle la présence d'un réseau de fractures dont l'orientation des trois principaux ensembles est 091°, 027° et 152°. La direction 027° est parallèle à une anomalie aéromagnétique majeure, la zone linéaire Niagara-Pickering, présente sous la région de Balsam Lake; on croit qu'elle identifie le prolongement sub-paléozoïque de l'aire limite de la zone méta-sédimentaire centrale protérozoïque. On traite des origines possibles des principaux ensembles de fractures attribuables aux systèmes acadien (091°), alléghanien (152°) et du rift du Saint-Laurent (091 °et 027°). La direction des structures de soulèvement en échelon est de 118°. Elles ont déplacé des paléo-plages du Lac Algonquin, indiquant ainsi une formation postérieure à 12 500 ans. L'orientation des structures de soulèvement est subnormale à la direction de la contrainte horizontale maximale actuelle, SHmax(020°), et est parallèle à des éléments de l'ensemble des fractures de direction 091°, montrant ainsi leur formation possible dans des fractures existantes bien orientées. Ces structures de soulèvement sont les seuls éléments de la région démontrant un âge néotectonique.Eine Untersuchung der topographischen Lineamente die in Landsat TM-Bildern nachweisbar sind und Messungen der Fugen in den Aufschlùssen des Balsam Lake-Gebiets lassen ein systematisches Bruchmuster des anstehenden Gesteins erkennen mit drei nach 091°, 027° und 152° ausgerichteten Haupteinheiten. Die Ausrichtung nach 027° ist parallel zu einer wichtigen aeromagnetischen Anomalie, der linearen Zone von Niagara-Pickering, die unter dem Balsam Lake-Gebiet liegt; man halt sie fur eine subpalàozoische Fortfùhrung des Grenz-bereichs der proterozoischen zentralen metasedimentàren Gùrtel-zone. Man diskutiert môgliche Ursprùnge der Hauptfugen-systeme, die auf die akadische (091° System), alleghanische (152° System) und Sankt-Lorenz-Spaltensystem Tektonik (091° und 027° System) zurùckgefùhrt werden. Die gestaffelten Hebungsstrukturen haben eine durchschnittliche Hauptrichtung von 118°. Sie haben Palào-Strànde vom Lake Algonquin versetzt, und weisen so auf eine Bildung vor weniger als 12,500 Jahren. Die Orientierung der Hebungsstrukturen ist subnormal zu der gegenwàrtigen maximalen horizontalen Stressrichtung, S"m" (020°) und parallel zu Elementen des 091° Fugen-systems, was auf ihre môgliche Bildung auf gùnstig orientierten schon vorhandenen Fugen weist. Dièse Hebungen sind die einzi-gen Strukturen im Balsm Lake-Gebiet, welche deutlich ein neotektonisches Alter belegen

Decision-making in an emergency department: A nursing accountability model

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Introduction Nurses that work in an emergency department regularly care for acute patients in a fast-paced environment, being at risk of suffering high levels of burnout. This situation makes them especially vulnerable to be accountable for decisions they did not have time to consider or have been pressured into. Research objective The objective of this study was to find which factors influence ethical, legal and professional accountability in nursing practice in an emergency department. Research design Data were analysed, codified and triangulated using qualitative ethnographic content analysis. Participants and research context This research is set in a large emergency department in the Midlands area of England. Data was collected from 186 nurses using participant observation, 34 semi-structured interviews with nurses and ethical analysis of 54 applicable clinical policies Ethical considerations Ethical approval was granted by two research ethics committees and the National Health Service Health Research Authority. Results The main result was the clinical nursing accountability cycle model, which showed accountability as a subjective concept that flows between the nurse and the healthcare institution. Moreover, the relations amongst the clinical nursing accountability factors are also analysed to understand which factors affect decision-making. Discussion The retrospective understanding of the factors that regulate nursing accountability is essential to promote that both the nurse and the healthcare institution take responsibility not only for the direct consequences of their actions but also for the indirect consequences derived from previous decisions. Conclusion The decision-making process and the accountability linked to it are affected by several factors that represent the holistic nature of both entities, which are organised and interconnected in a complex grid. This pragmatic interpretation of nursing accountability allows the nurse to comprehend how their decisions are affected, while the healthcare institution could act proactively to avoid any problems before they happen

Effect of coherent noise on single-station direction of arrival estimation

Polarization analysis of multi-component seismic data is used in both exploration seismology and earthquake seismology. In single-station polarization processing, it is generally assumed that any noise present in the window of analysis is incoherent, i.e., does not correlate between components. This assumption is often violated in practice because several overlapping seismic events may be present in the data. The additional arrival(s) to that of interest can be viewed as coherent noise. This paper quantifies the error because of coherent noise interference. We first give a general theoretical analysis of the problem. A simple mathematical wavelet is then used to obtain a closed-form solution to the principal direction estimated for a transient incident signal superposed with a time-shifted, unequal amplitude version of itself, arriving at an arbitrary angle to the first wavelet. The effects of relative amplitude, arrival angle, and the time delay of the two wavelets on directional estimates are investigated. Even for small differences in angle of arrival, there may be significant error (>10°) in the azimuth estimat