39 research outputs found
Preliminary geometry and kinematics of multiple surface ruptures during the 2016 MW 7.8 KaikĆura earthquake, North Canterbury region, New Zealand
The Mw 7.8 KaikĆura earthquake ruptured ~200 km at the ground surface across the New Zealand plate boundary zone in the northern South Island. This study was conducted in an area of ~600 km2 in the epicentral region where the faults comprise two main non-coplanar sets that strike E-NE and NNE-NW with mainly steep dips (60ĐŸ-80°). Analysis of the surface rupture using field and LiDAR data provides new information on the dimensions, geometries and kinematics of these faults which was not previously available from pre-earthquake active faults or bedrock structure. The more northerly striking fault set are sub-parallel to basement bedding and accommodated predominantly left-lateral reverse slip with net slips of ~1 and ~5 m for the Stone Jug and Leader faults, respectively. The E-NE striking Conway-Charwell and The Humps faults accrued right-lateral to oblique reverse with net slips of ~2 and ~3 m, respectively. The faults form a hard-linked system dominated by kinematics consistent with the ~260° trend of the relative plate motion vector and the transpressional structures recorded across the plate boundary in the NE South Island. Interaction and intersection of the main fault sets facilitated propagation of the earthquake and transfer of slip northwards across the plate boundary zone
Transient integral boundary layer method to calculate the translesional pressure drop and the fractional flow reserve in myocardial bridges
BACKGROUND: The pressure drop â flow relations in myocardial bridges and the assessment of vascular heart disease via fractional flow reserve (FFR) have motivated many researchers the last decades. The aim of this study is to simulate several clinical conditions present in myocardial bridges to determine the flow reserve and consequently the clinical relevance of the disease. From a fluid mechanical point of view the pathophysiological situation in myocardial bridges involves fluid flow in a time dependent flow geometry, caused by contracting cardiac muscles overlying an intramural segment of the coronary artery. These flows mostly involve flow separation and secondary motions, which are difficult to calculate and analyse. METHODS: Because a three dimensional simulation of the haemodynamic conditions in myocardial bridges in a network of coronary arteries is time-consuming, we present a boundary layer model for the calculation of the pressure drop and flow separation. The approach is based on the assumption that the flow can be sufficiently well described by the interaction of an inviscid core and a viscous boundary layer. Under the assumption that the idealised flow through a constriction is given by near-equilibrium velocity profiles of the Falkner-Skan-Cooke (FSC) family, the evolution of the boundary layer is obtained by the simultaneous solution of the Falkner-Skan equation and the transient von-KĂĄrmĂĄn integral momentum equation. RESULTS: The model was used to investigate the relative importance of several physical parameters present in myocardial bridges. Results have been obtained for steady and unsteady flow through vessels with 0 â 85% diameter stenosis. We compare two clinical relevant cases of a myocardial bridge in the middle segment of the left anterior descending coronary artery (LAD). The pressure derived FFR of fixed and dynamic lesions has shown that the flow is less affected in the dynamic case, because the distal pressure partially recovers during re-opening of the vessel in diastole. We have further calculated the wall shear stress (WSS) distributions in addition to the location and length of the flow reversal zones in dependence on the severity of the disease. CONCLUSION: The described boundary layer method can be used to simulate frictional forces and wall shear stresses in the entrance region of vessels. Earlier models are supplemented by the viscous effects in a quasi three-dimensional vessel geometry with a prescribed wall motion. The results indicate that the translesional pressure drop and the mean FFR compares favourably to clinical findings in the literature. We have further shown that the mean FFR under the assumption of Hagen-Poiseuille flow is overestimated in developing flow conditions
Calculation of molecular thermochemical data and their availability in databases
Thermodynamic properties of molecules can be obtained by experiment, by statistical mechanics in conjunction with electronic structure theory and by empirical rules like group additivity. The latter two methods are briefly re-viewed in this chapter. The overview of electronic structure methods is intended for readers less experienced in electronic structure theory and focuses on concepts without going into mathematical details. This is followed by a brief description of group additivity schemes; finally, an overview of databases listing reliable thermochemical data is given
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Low-intensity cognitive-behaviour therapy interventions for obsessive-compulsive disorder compared to waiting list for therapist-led cognitive-behaviour therapy: 3-arm randomised controlled trial of clinical effectiveness
Background Obsessive-compulsive disorder (OCD) is prevalent and without adequate treatment usually follows a chronic course. âHigh-intensityâ cognitive-behaviour therapy (CBT) from a specialist therapist is current âbest practice.â However, access is difficult because of limited numbers of therapists and because of the disabling effects of OCD symptoms. There is a potential role for âlow-intensityâ interventions as part of a stepped care model. Low-intensity interventions (written or web-based materials with limited therapist support) can be provided remotely, which has the potential to increase access. However, current evidence concerning low-intensity interventions is insufficient. We aimed to determine the clinical effectiveness of 2 forms of low-intensity CBT prior to high-intensity CBT, in adults meeting the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) criteria for OCD. Methods and findings This study was approved by the National Research Ethics Service Committee North WestâLancaster (reference number 11/NW/0276). All participants provided informed consent to take part in the trial. We conducted a 3-arm, multicentre randomised controlled trial in primary- and secondary-care United Kingdom mental health services. All patients were on a waiting list for therapist-led CBT (treatment as usual). Four hundred and seventy-three eligible patients were recruited and randomised. Patients had a median age of 33 years, and 60% were female. The majority were experiencing severe OCD. Patients received 1 of 2 low-intensity interventions: computerised CBT (cCBT; web-based CBT materials and limited telephone support) through âOCFighterâ or guided self-help (written CBT materials with limited telephone or face-to-face support). Primary comparisons concerned OCD symptoms, measured using the Yale-Brown Obsessive Compulsive ScaleâObserver-Rated (Y-BOCS-OR) at 3, 6, and 12 months. Secondary outcomes included health-related quality of life, depression, anxiety, and functioning. At 3 months, guided self-help demonstrated modest benefits over the waiting list in reducing OCD symptoms (adjusted mean difference = â1.91, 95% CI â3.27 to â0.55). These effects did not reach a prespecified level of âclinically significant benefit.â cCBT did not demonstrate significant benefit (adjusted mean difference = â0.71, 95% CI â2.12 to 0.70). At 12 months, neither guided self-help nor cCBT led to differences in OCD symptoms. Early access to low-intensity interventions led to significant reductions in uptake of high-intensity CBT over 12 months; 86% of the patients allocated to the waiting list for high-intensity CBT started treatment by the end of the trial, compared to 62% in supported cCBT and 57% in guided self-help. These reductions did not compromise longer-term patient outcomes. Data suggested small differences in satisfaction at 3 months, with patients more satisfied with guided self-help than supported cCBT. A significant issue in the interpretation of the results concerns the level of access to high-intensity CBT before the primary outcome assessment. Conclusions We have demonstrated that providing low-intensity interventions does not lead to clinically significant benefits but may reduce uptake of therapist-led CBT
Turbulence drives microscale patches of motile phytoplankton
Patchiness plays a fundamental role in phytoplankton ecology by dictating the rate at which individual cells encounter each other and their predators. The distribution of motile phytoplankton species is often considerably more patchy than that of non-motile species at submetre length scales, yet the mechanism generating this patchiness has remained unknown. Here we show that strong patchiness at small scales occurs when motile phytoplankton are exposed to turbulent flow. We demonstrate experimentally that Heterosigma akashiwo forms striking patches within individual vortices and prove with a mathematical model that this patchiness results from the coupling between motility and shear. When implemented within a direct numerical simulation of turbulence, the model reveals that cell motility can prevail over turbulent dispersion to create strong fractal patchiness, where local phytoplankton concentrations are increased more than 10-fold. This "unmixing" mechanism likely enhances ecological interactions in the plankton and offers mechanistic insights into how turbulence intensity impacts ecosystem productivity
The Eruptive History of the Atiamuri Pyroclastics, Maora Volcanic Centre, New Zealand : a project submitted in partial fulfilment of the requirements for the Degree of Bachelor of Science with Honours in Geology at the Department of Geological Sciences, University of Canterbury.
The Atiamuri pyroclastic sequence (229 + 12 ka) is part of the Maroa Volcanic Centre, Taupo
Volcanic Zone (TVZ), New Zealand. Data from stratigraphy, petrography, geochemistry and
comparisons with other research have been gathered to produce a description of the Atiamuri
deposits and their eruptive history. Units from this pyroclastic sequence occupy an area of <1
km3
and includes basal phreatomagmatic airfall layers, three ignimbrite units with different
degrees of welding separated by shower beds, and overlying airfall layers with alternating ash
and lapilli. The Atiamuri pyroclastics are suggested to have erupted from a single vent
beneath Mandarin Dome from a small, un-zoned discrete chamber, or from partial evacuation
of a larger chamber.
Comparisons with other known small ignimbrite-forming events (in particular, the ~AD 1315
Kaharoa eruptive episode at nearby Tarawera Volcanic Centre) have determined that although
the Atiamuri is similar in extent and was followed by dome extrusion, it differs in lithic
content, absence of block-and-ash flows, interaction with water, general chemical
homogeneity and lack of evidence for a mafic eruption trigger.
A suggested model for the eruptive sequence at Atiamuri is as follows: (a) Small
phreatomagmatic airfall eruption into a swampy lakeshore environment with possible early
extrusion of a small proto-dome. (b) Emplacement of pyroclastic flows by a small laterally
directed eruption from the side of the proto-dome. Pyroclastic flows are of HARI-type (high
aspect ratio) and are topographically controlled. (c) Post-ignimbrite airfall with alternating
small eruptions from the vent. Some further minor interaction with water possible. (d)
Extrusion of Mandarin Dome from vent, pushing through the ignimbrite deposits
Authentic collaboration with local communities in post-disaster reconnaissance and beyond: how to create a win-win scenario.
Geological research in the immediate aftermath of the 2016 KaikĆura Earthquake, New Zealand, was necessary due to the importance and perishability of field data. It also reflects a real desire on the part of researchers to contribute not only to immediate scientific understanding but also to the societal recovery effort by enhancing knowledge of the event for the benefit of affected communities, civil defence organizations and regional and national decision makers. This commitment to outreach and engagement is consistent with the recent IAPG statement of Geoethics. More immediately, it was informed by experience of the 2010-2011 Canterbury Earthquake sequence. After that earlier disaster, intense interactions between researchers and various response agencies as well as local communities informed the development and dissemination of a set of ethical guidelines for researchers immediately following the Mw7.8 14 November 2016 KaikĆura Earthquake. In this presentation, I argue that ethical engagement of this kind is the key to gathering high quality research data immediately after the event. Creating trusting and mutually respectful, mutually beneficial relationships is also vital to ongoing engagement to facilitate further âin depthâ research in collaboration with communities
Curriculum restructuring overnight: Teaching large first-year classes after a major earthquake
On 22 February 2011, the second day of the first semester, a devastating magnitude 6.2 earthquake struck the city of Christchurch forcing the campus of the University of Canterbury to close for several weeks. Here, we report on the sudden curriculum and assessment overhaul that needed to be implemented using two large, first-year introductory courses as case studies. We discuss the reasoning and justifications behind these changes, as well as the logistics of this process. We draw conclusions based on student feedback and assessments and formulate lessons learnt