The Behavior of compressively loaded stiffener runout specimens - Part II: Finite element analysis

The termination of stiffeners in composite aircraft structures give rise to regions of high interlaminar shear and peel stresses as the load in the stiffener is diffused into the skin. This is of particular concern in co-cured composite stiffened structures where there is a relatively low resistance to through-thickness stress components at the skin-stiffener interface. In Part I, experimental results of tested specimens highlighted the influence of local design parameters on their structural response. Indeed some of the observed behavior was unexpected. There is a need to be able to analyse a range of changes in geometry rapidly to allow the analysis to form an integral part of the structural design process.

This work presents the development of a finite element methodology for modelling the failure process of these critical regions. An efficient thick shell element formulation is presented and this element is used in conjuction with the Virtual Crack Closure Technique (VCCT) to predict the crack growth characteristics of the modelled specimens. Three specimens were modelled and the qualitative aspects of crack growth were captured successfully. The shortcomings in the quantitative correlation between the predicted and observed failure loads are discussed. There was evidence to suggest that high through-thickness compressive stresses enhanced the fracture toughness in these critical regions.

A low-cost solution for the restoration of femoral head centre during total hip arthroplasty

Restoration of joint centre during total hip arthroplasty is critical. While computer-aided navigation can improve accuracy during total hip arthroplasty, its expense makes it inaccessible to the majority of surgeons. This article evaluates the use, in the laboratory, of a calliper with a simple computer application to measure changes in femoral head centres during total hip arthroplasty. The computer application was designed using Microsoft Excel and used calliper measurements taken pre- and post-femoral head resection to predict the change in head centre in terms of offset and vertical height between the femoral head and newly inserted prosthesis. Its accuracy was assessed using a coordinate measuring machine to compare changes in preoperative and post-operative head centre when simulating stem insertion on 10 sawbone femurs. A femoral stem with a modular neck was used, which meant nine possible head centre configurations were available for each femur, giving 90 results. The results show that using this technique during a simulated total hip arthroplasty, it was possible to restore femoral head centre to within 6?mm for offset (mean 1.67?±?1.16?mm) and vertical height (mean 2.14?±?1.51?mm). It is intended that this low-cost technique be extended to inform the surgeon of a best-fit solution in terms of neck length and neck type for a specific prosthesis.

Comparison of lagrangian and eulerian simulations of slurry flows in a sudden expansion

From a review of technical literature, it was not apparent if the Lagrangian or the Eulerian dispersed phase modeling approach was more valid to simulate dilute erosive slurry flow. In this study, both modeling approaches were employed and a comparative analysis of performances and accuracy between the two models was carried out. Due to an impossibility to define, for the Eulerian model already implemented in FLUENT, a set of boundary conditions consistent with the Lagrangian impulsive equations, an Eulerian dispersed phase model was integrated in the FLUENT code using subroutines and user-defined scalar equations. Numerical predictions obtained from the two different approaches for two-phase flow in a sudden expansion were compared with the measured data. Excellent agreement was attained between the predicted and observed fluid and particle velocity in the axial direction and for the kinetic energy. Erosion profiles in a sudden expansion computed using the Lagrangian scheme yielded good qualitative agreement with measured data and predicted a maximum impact angle of 29 deg at the fluid reattachment point. The Eulerian model was adversely affected by the reattachment of the fluid phase to the wall and the simulated erosion profiles were not in agreement with the Lagrangian or measured data. Furthermore, the Eulerian model under-predicted the Lagrangian impact angle at all locations except the reattachment point. © 2010 American Society of Mechanical Engineers.

An efficacy and mechanism evaluation study of Levosimendan for the Prevention of Acute oRgan Dysfunction in Sepsis (LeoPARDS): Protocol for a randomized controlled trial

Background

Organ dysfunction consequent to infection (‘severe sepsis’) is the leading cause of admission to an intensive care unit (ICU). In both animal models and early clinical studies the calcium channel sensitizer levosimendan has been demonstrated to have potentially beneficial effects on organ function. The aims of the Levosimendan for the Prevention of Acute oRgan Dysfunction in Sepsis (LeoPARDS) trial are to identify whether a 24-hour infusion of levosimendan will improve organ dysfunction in adults who have septic shock and to establish the safety profile of levosimendan in this group of patients.

This is a multicenter, randomized, double-blind, parallel group, placebo-controlled trial. Adults fulfilling the criteria for systemic inflammatory response syndrome due to infection, and requiring vasopressor therapy, will be eligible for inclusion in the trial. Within 24 hours of meeting these inclusion criteria, patients will be randomized in a 1:1 ratio stratified by the ICU to receive either levosimendan (0.05 to 0.2 μg.kg^-1.min^-1 or placebo for 24 hours in addition to standard care. The primary outcome measure is the mean Sequential Organ Failure Assessment (SOFA) score while in the ICU. Secondary outcomes include: central venous oxygen saturations and cardiac output; incidence and severity of renal failure using the Acute Kidney Injury Network criteria; duration of renal replacement therapy; serum bilirubin; time to liberation from mechanical ventilation; 28-day, hospital, 3 and 6 month survival; ICU and hospital length-of-stay; and days free from catecholamine therapy. Blood and urine samples will be collected on the day of inclusion, at 24 hours, and on days 4 and 6 post-inclusion for investigation of the mechanisms by which levosimendan might improve organ function. Eighty patients will have additional blood samples taken to measure levels of levosimendan and its active metabolites OR-1896 and OR-1855. A total of 516 patients will be recruited from approximately 25 ICUs in the United Kingdom.

This trial will test the efficacy of levosimendan to reduce acute organ dysfunction in adult patients who have septic shock and evaluate its biological mechanisms of action.

Microstructure, mechanical properties and fractography of heat-treated manganese steel

A Fe-8.46%Mn-0.24%Nb-0.038%C (wt.%) manganese steel was investigated. The steel has a 100% bcc structure after heat treatment at 850°C for 1.5 h, water quenching or air cooling. Martensite interlocked microstructure consisting of fine martensite plates/needles with different spatial orientations was found. Austenite forms, in small amounts, after a 600°C reheating treatment. Scanning electron microscopy images and energy dispersive spectrometry of the fracture surfaces revealed both ductile and brittle types of failure and precipitates. Deep quenching after the heat treatments does not change the phase composition or the hardness. NbC is formed in the steel, in high number densities. It plays a role in the impact fracture process, by acting as void nucleation sites, facilitating ductile fracture with dimples appearing on the fracture surface.

In women, increased dietary antioxidants are associated with reduced risk of developing heart failure

Commentary on

Rautiainen S, Levitan EB, Mittleman MA, et al. Total antioxidant capacity of diet and risk of heart failure: a population-based prospective cohort of women. Am J Med 2013;126:494–500.

Sedentary behaviour and physical activity in bronchiectasis: a cross-sectional study

BACKGROUND: The impact of bronchiectasis on sedentary behaviour and physical activity is unknown. It is important to explore this to identify the need for physical activity interventions and how to tailor interventions to this patient population. We aimed to explore the patterns and correlates of sedentary behaviour and physical activity in bronchiectasis.

METHODS: Physical activity was assessed in 63 patients with bronchiectasis using an ActiGraph GT3X+ accelerometer over seven days. Patients completed: questionnaires on health-related quality-of-life and attitudes to physical activity (questions based on an adaption of the transtheoretical model (TTM) of behaviour change); spirometry; and the modified shuttle test (MST). Multiple linear regression analysis using forward selection based on likelihood ratio statistics explored the correlates of sedentary behaviour and physical activity dimensions. Between-group analysis using independent sample t-tests were used to explore differences for selected variables.

RESULTS: Fifty-five patients had complete datasets. Average daily time, mean(standard deviation) spent in sedentary behaviour was 634(77)mins, light-lifestyle physical activity was 207(63)mins and moderate-vigorous physical activity (MVPA) was 25(20)mins. Only 11% of patients met recommended guidelines. Forced expiratory volume in one-second percentage predicted (FEV1% predicted) and disease severity were not correlates of sedentary behaviour or physical activity. For sedentary behaviour, decisional balance 'pros' score was the only correlate. Performance on the MST was the strongest correlate of physical activity. In addition to the MST, there were other important correlate variables for MVPA accumulated in ≥10-minute bouts (QOL-B Social Functioning) and for activity energy expenditure (Body Mass Index and QOL-B Respiratory Symptoms).

CONCLUSIONS: Patients with bronchiectasis demonstrated a largely inactive lifestyle and few met the recommended physical activity guidelines. Exercise capacity was the strongest correlate of physical activity, and dimensions of the QOL-B were also important. FEV1% predicted and disease severity were not correlates of sedentary behaviour or physical activity. The inclusion of a range of physical activity dimensions could facilitate in-depth exploration of patterns of physical activity. This study demonstrates the need for interventions targeted at reducing sedentary behaviour and increasing physical activity, and provides information to tailor interventions to the bronchiectasis population.

What counts and what is being counted – The social organization of knowledge on the front lines of emergency medical services.

Paramedics are trained to use specialized medical knowledge and a variety of medical procedures and pharmaceutical interventions to “save patients and prevent further damage” in emergency situations, both as members of “health-care teams” in hospital emergency departments (Swanson, 2005: 96) and on the streets – unstandardized contexts “rife with chaotic, dangerous, and often uncontrollable elements” (Campeau, 2008: 3). The paramedic’s unique skill-set and ability to function in diverse situations have resulted in the occupation becoming ever more important to health care systems (Alberta Health and Wellness, 2008: 12).
Today, prehospital emergency services, while varying, exist in every major city and many rural areas throughout North America (Paramedics Association of Canada, 2008) and other countries around the world (Roudsari et al., 2007). Services in North America, for instance, treat and/or transport 2 million Canadians (over 250,000 in Alberta alone ) and between 25 and 30 million Americans annually (Emergency Medical Services Chiefs of Canada, 2006; National EMS Research Agenda, 2001). In Canada, paramedics make up one of the largest groups of health care professionals, with numbers exceeding 20,000 (Pike and Gibbons, 2008; Paramedics Association of Canada, 2008). However, there is little known about the work practices of paramedics, especially in light of recent changes to how their work is organized, making the profession “rich with unexplored opportunities for research on the full range of paramedic work” (Campeau, 2008: 2).

This presentation reports on findings from an institutional ethnography that explored the work of paramedics and different technologies of knowledge and governance that intersect with and organize their work practices. More specifically, my tentative focus of this presentation is on discussing some of the ruling discourses central to many of the technologies used on the front lines of EMS in Alberta and the consequences of such governance practices for both the front line workers and their patients. In doing so, I will demonstrate how IE can be used to answer Rankin and Campbell’s (2006) call for additional research into “the social organization of information in health care and attention to the (often unintended) ways ‘such textual products may accomplish…ruling purposes but otherwise fail people and, moreover, obscure that failure’ (p. 182)” (cited in McCoy, 2008: 709).

Technologies of Knowledge and Governance on the Front Lines of Emergency Services.

Using institutional ethnography, a sociology and critical method of inquiry used primarily in North America, this presentation discusses new forms and technologies of knowledge and governance – “forms of language, technologies of representation and communication, and text-based, objectified modes of knowledge through which local particularities are interpreted or rendered actionable in abstract, translocal terms” (McCoy, 2008: 701) on the front line of emergency medical services. I focus specifically on technologies central to health reforms that attempt to reshape how health care is delivered, experienced, and made accountable (Anantharaman, 2004; Ball, 2005; Alberta Health Services, 2008). In additional to exemplifying how institutional ethnography can be used to answer Rankin and Campbell’s (2006) call for additional research into “the social organization of information in health care and attention to the (often unintended) ways ‘such textual products may accomplish…ruling purposes but otherwise fail people and, moreover, obscure that failure’ (p. 182)” (cited in McCoy, 2008: 709), this presentation will introduce the audience to a critical approach to social inquiry that explores how knowledge is socially organized.

Symposium - Organisational transformation in policing: Leadership and change in extreme contexts

Nearly 4000 people died in Northern Ireland’s long running conflict, 314 of them police officers (Brewer and Magee 1991, Brewer 1996, Hennessey 1999, Guelke and Milton-Edwards 2000). The republican and loyalist ceasefires of 1994 were the first significant signal that NI society was moving beyond the ‘troubles’ and towards a normalised political environment. The Belfast (Good Friday) Agreement of 1998 cemented that movement (Hennessey 1999). Policing was a key and seemingly unresolvable element of the conflict, seen as unrepresentative and partisan. Its reform or ‘recasting’ in a new dispensation was an integral part of the conflict transformation endeavour(Ellison 2010). As one of the most controversial elements of the conflicted past, it had remained outside the Agreement and was subject to a specific commission of interest (1999), generally known as the Patten Commission. The Commission’s far reaching proposals included a change of name, badge and uniform, the introduction of 50/50 recruitment (50% Roman Catholic and 50% other), a new focus on human rights, a new district command and headquarter structure, a review of ‘Special Branch’ and covert techniques, a concern for ‘policing with the community’ and a significant voluntary severance process to make room for new recruits, unconnected with the past history of the organisation(Murphy 2013).

This paper reflects upon the first data collection phase of a long term processual study of organisational change within the Royal Ulster Constabulary / Police Service of Northern Ireland. This phase (1996-2002) covers early organisational change initiation (including the pre-change period) and implementation including the instigation of symbolic changes (name, badge, and crest) and structural changes (new HQ structure and District Command structure). It utilises internal documentation including messages from the organisations leaders, interviews with forty key informants (identified through a combination of snow-balling from referrals by initial contacts, and key interviews with significant individuals), as well as external documentation and commentary on public perceptions of the change. Using a processual lens (Langley, Smallman et al. 2013) it seeks to understand this initial change phase and its relative success in a highly politicised environment.

By engaging key individuals internally and externally, setting up a dedicated change team, adopting a non normative, non urgent, calming approach to dissent, communicating in orthodox and unorthodox ways with members, acknowledging the huge emotional strain of letting go of the organisation’s name and all it embodied, and re-emphasising the role of officers as ‘police first’, rather than ‘RUC first’, the organisations leadership remained in control of a volatile and unhappy organisational body and succeeded in moving it on through this initial phase, even while much of the political establishment lambasted them externally. Three years into this change process the organisation had a new name, a new crest, new structures, procedures and was deeply engaged in embedding the joint principles of human rights and community policing within its re-woven fabric. While significant problems remained, the new Police Service of Northern Ireland had successfully begun a long journey to full community acceptance in a post conflict context.

This case illustrates the significant challenges of leading change under political pressure, with external oversight and no space for failure(Hannah, Uhl-Bien et al. 2009). It empirically reflects the reality of change implementation as messy, disruptive and unpredictable and highlights the significance of political skill and contextual understanding to success in the early stages(Buchanan and Boddy 1992). The implications of this for change theory and the practice of change implementation are explored (Eisenhardt and Graebner 2007) and some conclusions drawn about what such an extreme case tells us about change generally and change implementation under pressure.

Glucagon-like peptide-1 based therapies as a novel approach for chronic heart failure

Glucagon-like peptide-1 (GLP-1) is an endogenous peptide hormone whose metabolic effects have been exploited for glycaemic control in diabetes, but which also exerts important cardiovascular actions. We have recently reported that the GLP-1 mimetic, exendin-4, exerts clear benefits post-myocardial infarction via specific effects on extracellular matrix remodelling which is dysregulated in the diabetic heart (Robinson E et al, Basic Res Cardiol 2015; 110: 20), and have now shown similar cardioprotective actions in experimental diabetes, which are mediated via direct effects on infiltrating macrophages (Tate M et al, Basic Res Cardiol 2015; in press). Taken together with the apparent complexity of GLP-1 signalling and disappointing results of recent cardiovascular trials, our work strongly suggests that selective targeting of GLP-1 may be required in order to realise therapeutic benefit for both diabetic and non-diabetic heart failure patients. This is particularly important given the epidemic increase in the incidence of diabetes which is associated with a markedly enhanced susceptibility to cardiovascular stress.

Interpretable and Reconfigurable Clustering of Document Datasets by Deriving Word-based Rules

Clusters of text documents output by clustering algorithms are often hard to interpret. We describe motivating real-world scenarios that necessitate reconfigurability and high interpretability of clusters and outline the problem of generating clusterings with interpretable and reconfigurable cluster models. We develop two clustering algorithms toward the outlined goal of building interpretable and reconfigurable cluster models. They generate clusters with associated rules that are composed of conditions on word occurrences or nonoccurrences. The proposed approaches vary in the complexity of the format of the rules; RGC employs disjunctions and conjunctions in rule generation whereas RGC-D rules are simple disjunctions of conditions signifying presence of various words. In both the cases, each cluster is comprised of precisely the set of documents that satisfy the corresponding rule. Rules of the latter kind are easy to interpret, whereas the former leads to more accurate clustering. We show that our approaches outperform the unsupervised decision tree approach for rule-generating clustering and also an approach we provide for generating interpretable models for general clusterings, both by significant margins. We empirically show that the purity and f-measure losses to achieve interpretability can be as little as 3 and 5%, respectively using the algorithms presented herein.

Glucagon-like peptide-1 based therapies as a novel approach for chronic heart failure

Glucagon-like peptide-1 (GLP-1) is an endogenous peptide hormone whose metabolic effects have been exploited for glycaemic control in diabetes, but which also exerts important cardiovascular actions. We have recently reported that the GLP-1 mimetic, exendin-4, exerts clear benefits post-myocardial infarction via specific effects on extracellular matrix remodelling which is dysregulated in the diabetic heart (Robinson E et al, Basic Res Cardiol 2015; 110: 20), and have now shown similar cardioprotective actions in experimental diabetes, which are mediated via direct effects on infiltrating macrophages (Tate M et al, Basic Res Cardiol 2016; 111: 1). Taken together with the apparent complexity of GLP-1 signalling and disappointing results of recent cardiovascular trials, our work strongly suggests that selective targeting of GLP-1 may be required in order to realise therapeutic benefit for both diabetic and non-diabetic heart failure patients. This is particularly important given the epidemic increase in the incidence of diabetes which is associated with a markedly enhanced susceptibility to cardiovascular stress.

Integration of design of experiment, surface response methodology and multi-layer validation to predict the effect of blanching on colour of tomato juice

Response surface methodology was used to develop models to predict the effect of tomato cultivar, juice pH, blanching temperature and time on colour change of tomato juice after blanching. The juice from three tomato cultivars with adjusted pH levels ranging from 3.9 to 4.6 were blanched at temperatures from 60-100 °C for 1-5 min using the central composite design (CCD). The colour change was assessed by calculating the redness (a/b) and total colour change (∆E) after measuring the Hunter L, a and b values. Developed models for both redness and ∆E were significant (p<0.0001) with satisfactory coefficient of determination (R2 = 0.99 and 0.97) and low coefficient of variation (CV% = 1.89 and 7.23), respectively. Multilevel validation that was implemented revealed that the variation between the predicted and experimental values obtained for redness and ∆E were within the acceptable error range of 7.3 and 22.4%, respectively

Structural and Functional Lung Impairment in Adult Survivors of Bronchopulmonary Dysplasia

RATIONALE: As more preterm infants recover from severe bronchopulmonary dysplasia (BPD), it is critical to understand the clinical consequences of this condition on the lung health of adult survivors.

OBJECTIVES: To assess structural and functional lung parameters in young adult BPD survivors and preterm and term controls Methods: Young adult survivors of BPD (mean age 24) underwent spirometry, lung volumes, transfer factor, lung clearance index and fractional exhaled nitric oxide measurements together with high-resolution chest tomographic (CT) imaging and cardiopulmonary exercise testing.

MEASUREMENTS AND MAIN RESULTS: 25 adult BPD survivors, (mean ± SD gestational age 26.8 ± 2.3 weeks; birth weight 866 ± 255 g), 24 adult prematurely born non-BPD controls (gestational age 30.6 ± 1.9 weeks; birth weight 1234 ± 207 g) and 25 adult term birth control subjects (gestational age 38.5 ± 0.9 weeks; and birth weight 3569 ± 2979 g) were studied. BPD subjects were more likely to be wakened by cough (OR 9.7, 95% CI: 1.8 to 52.6), p<0.01), wheeze and breathlessness (OR 12.2, 95%CI: 1.3 to 112), p<0.05) than term controls after adjusting for sex and current smoking. Preterm subjects had greater airways obstruction than term subjects. BPD subjects had significantly lower values for FEV1 and FEF25-75 (% predicted and z scores) than term controls (both p<0.001). Although non-BPD subjects also had lower spirometric values than term controls, none of the differences reached statistical significance. More BPD subjects (25%) had fixed airflow obstruction than non-BPD (12.5%) and term (0%) subjects (p=0.004). Both BPD and non-BPD subjects had significantly greater impairment in gas transfer (KCO % predicted) than term subjects (both p<0.05). Eighteen (37%) preterm participants were classified as small for gestational age (birth weight < 10th percentile for gestational age). These subjects had significantly greater impairment in FEV1 (% predicted and z scores) than those born appropriate for gestational age. BPD survivors had significantly more severe radiographic structural lung impairment than non-BPD subjects. Both preterm groups had impaired exercise capacity compared to term controls. There was a trend for greater limitation and leg discomfort in BPD survivors.

CONCLUSIONS: Adult preterm birth survivors, especially those who developed BPD, continue to experience respiratory symptoms and exhibit clinically important levels of pulmonary impairment.