Frictional melt homogenisation during fault slip: Geochemical, textural and rheological fingerprints

info:eu-repo/semantics/publishe

Integrated constraints on explosive eruption intensification at Santiaguito dome complex, Guatemala

Protracted volcanic eruptions may exhibit unanticipated intensifications in explosive behaviour and attendant hazards. Santiaguito dome complex, Guatemala, has been characterised by century-long effusion interspersed with frequent, small-to-moderate (<2 km high plumes) gas-and-ash explosions. During 2015–2016, explosions intensified generating hazardous ash-rich plumes (up to 7 km high) and pyroclastic flows. Here, we integrate petrological, geochemical and geophysical evidence to evaluate the causes of explosion intensification. Seismic and infrasound signals reveal progressively longer repose intervals between explosions and deeper fragmentation levels as the seismic energy of these events increased by up to four orders of magnitude. Evidence from geothermobarometry, bulk geochemistry and groundmass microlite textures reveal that the onset of large explosions was concordant with a relatively fast ascent of a deeper-sourced (∼17–24 km), higher temperature (∼960–1020◦C) and relatively volatile-rich magma compared to the previous erupted lavas, which stalled at ∼2 km depth and mingled with the left-over mush that resided beneath the pre-2015 lava dome. We interpret that purging driven by the injection of this deep-sourced magma disrupted the long-term activity, driving a transition from low energy shallow shear-driven fragmentation, to high energy deeper overpressure-driven fragmentation that excavated significant portions of the conduit and intensified local volcanic hazards. Our findings demonstrate the value of multi-parametric approaches for understanding volcanic processes and the triggers for enigmatic shifts in eruption style, with the detection of vicissitudes in both monitoring signals and petrological signatures of the eruptive products proving paramount

Acceptability and feasibility of peer assisted supervision and support for intervention practitioners: a Q-methodology evaluation

Evidence-based interventions often include quality improvement methods to support fidelity and improve client outcomes. Clinical supervision is promoted as an effective way of developing practitioner confidence and competence in delivery; however, supervision is often inconsistent and embedded in hierarchical line management structures that may limit the opportunity for reflective learning. The Peer Assisted Supervision and Support (PASS) supervision model uses peer relationships to promote the self-regulatory capacity of practitioners to improve intervention delivery. The aim of the present study was to assess the acceptability and feasibility of PASS amongst parenting intervention practitioners. A Q-methodology approach was used to generate data and 30 practitioners volunteered to participate in the study. Data were analyzed and interpreted using standard Q-methodology procedures and by-person factor analysis yielded three factors. There was consensus that PASS was acceptable. Participants shared the view that PASS facilitated an environment of support where negative aspects of interpersonal relationships that might develop in supervision were not evident. Two factors represented the viewpoint that PASS was also a feasible model of supervision. However, the third factor was comprised of practitioners who reported that PASS could be time consuming and difficult to fit into existing work demands. There were differences across the three factors in the extent to which practitioners considered PASS impacted on their intervention delivery. The findings highlight the importance of organizational mechanisms that support practitioner engagement in supervision

Influence of mechanical and geometrical properties of embedded long-gauge strain sensors on the accuracy of strain measurement

In many civil and geotechnical applications it is of interest to monitor the strain deep inside the structure; consequently, it is necessary to embed the sensors into the structure's material. Construction and geotechnical materials, such as concrete and soil, can be affected by local defects, e.g. cracks, air pockets and inclusions. To monitor these materials at a structural level it is necessary to use long-gauge sensors. As the sensor has to be embedded in the host material, its presence causes perturbation of the strain field and influences the accuracy of the strain measurement. The aim of this research was to identify the critical parameters that influence the accuracy of the strain measurement, to study how these parameters affect the accuracy, and to give recommendations for sensor users. The study was based on finite element analysis and all involved materials were assumed to have the MöhrCoulomb elastic, perfectly plastic behavior. A suitability of the numerical model for the analysis was verified using the experimental results of two cases reported in the literature and one on-site application. The study revealed that the most important parameters that influence the accuracy of the strain measurement are the goodness of interaction (strain transfer) between the host material and the anchor pieces of the sensor, the ratio between equivalent Young's modulus of the sensor and the Young's modulus of the host material, the radius of the anchor piece and the gauge length. The numerical model and parametric study are presented in detail along with practical recommendations. © 2012 IOP Publishing Ltd.The authors would like to thank the Spanish Ministry of Education, with support received under the National Program for Mobility of Researchers (O.M. EDU/1456/2010, ref. PR2010-0293) which enabled the joint work that made this study possible. The Streicker Bridge project was realized with help of Turner Construction Co., HNTB, AG Construction Corp., Vollers Excavating & Constr., SMARTEC SA, Micron Optics, Princeton Facilities, and staff and students of CEE department of Princeton University.Calderón García, PA.; Glisic, B. (2012). Influence of mechanical and geometrical properties of embedded long-gauge strain sensors on the accuracy of strain measurement. Measurement Science and Technology. (23):1-15. https://doi.org/10.1088/0957-0233/23/6/065604S11523Glišić, B., & Inaudi, D. (2007). Fibre Optic Methods for Structural Health Monitoring. doi:10.1002/9780470517819Ansari, F. (2007). Practical Implementation of Optical Fiber Sensors in Civil Structural Health Monitoring. Journal of Intelligent Material Systems and Structures, 18(8), 879-889. doi:10.1177/1045389x06075760Li, H.-N., Zhou, G.-D., Ren, L., & Li, D.-S. (2009). Strain Transfer Coefficient Analyses for Embedded Fiber Bragg Grating Sensors in Different Host Materials. Journal of Engineering Mechanics, 135(12), 1343-1353. doi:10.1061/(asce)0733-9399(2009)135:12(1343)Torres, B., Payá-Zaforteza, I., Calderón, P. A., & Adam, J. M. (2011). Analysis of the strain transfer in a new FBG sensor for Structural Health Monitoring. Engineering Structures, 33(2), 539-548. doi:10.1016/j.engstruct.2010.11.012Kesavan, K., Ravisankar, K., Parivallal, S., Sreeshylam, P., & Sridhar, S. (2010). Experimental studies on fiber optic sensors embedded in concrete. Measurement, 43(2), 157-163. doi:10.1016/j.measurement.2009.08.010Azenha, M., Faria, R., & Ferreira, D. (2009). Identification of early-age concrete temperatures and strains: Monitoring and numerical simulation. Cement and Concrete Composites, 31(6), 369-378. doi:10.1016/j.cemconcomp.2009.03.004Glisic, B. (2011). Influence of the gauge length on the accuracy of long-gauge sensors employed in monitoring of prismatic beams. Measurement Science and Technology, 22(3), 035206. doi:10.1088/0957-0233/22/3/035206Leng, J. S., Winter, D., Barnes, R. A., Mays, G. C., & Fernando, G. F. (2006). Structural health monitoring of concrete cylinders using protected fibre optic sensors. Smart Materials and Structures, 15(2), 302-308. doi:10.1088/0964-1726/15/2/009Calderón, P. A., Adam, J. M., Ivorra, S., Pallarés, F. J., & Giménez, E. (2009). Design strength of axially loaded RC columns strengthened by steel caging. Materials & Design, 30(10), 4069-4080. doi:10.1016/j.matdes.2009.05.014Adam, J. M., Ivorra, S., Pallarés, F. J., Giménez, E., & Calderón, P. A. (2009). Axially loaded RC columns strengthened by steel caging. Finite element modelling. Construction and Building Materials, 23(6), 2265-2276. doi:10.1016/j.conbuildmat.2008.11.014Adam, J. M., Ivorra, S., Pallares, F. J., Jiménez, E., & Calderón, P. A. (2008). Column–joint assembly in RC columns strengthened by steel caging. Proceedings of the Institution of Civil Engineers - Structures and Buildings, 161(6), 337-348. doi:10.1680/stbu.2008.161.6.337Adam, J. M., Ivorra, S., Pallares, F. J., Giménez, E., & Calderón, P. A. (2009). Axially loaded RC columns strengthened by steel cages. Proceedings of the Institution of Civil Engineers - Structures and Buildings, 162(3), 199-208. doi:10.1680/stbu.2009.162.3.199Johansson, M., & Gylltoft, K. (2001). Structural behavior of slender circular steel-concrete composite columns under various means of load application. Steel and Composite Structures, 1(4), 393-410. doi:10.12989/scs.2001.1.4.393Johansson, M., & Gylltoft, K. (2002). Mechanical Behavior of Circular Steel–Concrete Composite Stub Columns. Journal of Structural Engineering, 128(8), 1073-1081. doi:10.1061/(asce)0733-9445(2002)128:8(1073

The medical student

The Medical Student was published from 1888-1921 by the students of Boston University School of Medicine

The forms of repetition in social and environmental reports: insights from Hume's notion of ?impressions?

This paper focuses on the use of repetition, both in narrative and visual forms, in social and environmental reports. It investigates the forms of repetition as a rhetorical device adopted by the preparer of a social and environmental report in helping the process of knowledge acquisition, as outlined by Hume (1739). Drawing from Hume?s (1739) philosophical idea of an ?impression?, and the work of Davison (2014a) we classify repetitions into ?identical?, ?similar? and ?accumulated? forms. It is argued that the rationale for distinguishing between the different forms of repetition can be linked to their different potential or intensity in acting on different stimuli with a view to enhance learning. The empirical element of this study is based on the stand-alone social and environmental reports of a sample of 86 cooperative banks in Northern Italy; the analysis of these reports indicates that repetition is widespread and that cooperative banks use all forms of repetition, albeit to a varying extent within the different reported themes. The paper contributes to the literature by offering an alternative interpretation of repetition using an interdisciplinary perspective and by providing new insights on social and environmental reporting practices in the cooperative banking sector

Utilisation of an operative difficulty grading scale for laparoscopic cholecystectomy

Background A reliable system for grading operative difficulty of laparoscopic cholecystectomy would standardise description of findings and reporting of outcomes. The aim of this study was to validate a difficulty grading system (Nassar scale), testing its applicability and consistency in two large prospective datasets. Methods Patient and disease-related variables and 30-day outcomes were identified in two prospective cholecystectomy databases: the multi-centre prospective cohort of 8820 patients from the recent CholeS Study and the single-surgeon series containing 4089 patients. Operative data and patient outcomes were correlated with Nassar operative difficultly scale, using Kendall’s tau for dichotomous variables, or Jonckheere–Terpstra tests for continuous variables. A ROC curve analysis was performed, to quantify the predictive accuracy of the scale for each outcome, with continuous outcomes dichotomised, prior to analysis. Results A higher operative difficulty grade was consistently associated with worse outcomes for the patients in both the reference and CholeS cohorts. The median length of stay increased from 0 to 4 days, and the 30-day complication rate from 7.6 to 24.4% as the difficulty grade increased from 1 to 4/5 (both p < 0.001). In the CholeS cohort, a higher difficulty grade was found to be most strongly associated with conversion to open and 30-day mortality (AUROC = 0.903, 0.822, respectively). On multivariable analysis, the Nassar operative difficultly scale was found to be a significant independent predictor of operative duration, conversion to open surgery, 30-day complications and 30-day reintervention (all p < 0.001). Conclusion We have shown that an operative difficulty scale can standardise the description of operative findings by multiple grades of surgeons to facilitate audit, training assessment and research. It provides a tool for reporting operative findings, disease severity and technical difficulty and can be utilised in future research to reliably compare outcomes according to case mix and intra-operative difficulty

A nomenclature for restriction enzymes, DNA methyltransferases, homing endonucleases and their genes

A nomenclature is described for restriction endonucleases, DNA methyltransferases, homing endonucleases and related genes and gene products. It provides explicit categories for the many different Type II enzymes now identified and provides a system for naming the putative genes found by sequence analysis of microbial genomes