47 research outputs found
Analysis of shear forces during mash disk formation
This report concerns a forming process in which mash is forced from a spreading manifold into moulds on a rotating drum, transported in the moulds underneath a surface held flush with the drum (the shoe), and ejected from the moulds. The quality of the final product is understood to be related to the shear stresses experienced by the mash in the moulds as it is transported under the shoe. We describe and analyse mathematical models of the forming process, focusing on the fluid mechanics of mash in a mould. We treat this as a driven cavity flow and obtain flow profiles, stress profiles, and expressions for the maximum shear stress for different rheological models of the mash (Newtonian fluid, power-law fluid, and Bingham plastic)
Sustaining a new model of acute stroke care : A mixed-method process evaluation of the Melbourne Mobile Stroke Unit
Background
Internationally, Mobile Stroke Unit (MSU) ambulances have changed pre-hospital acute stroke care delivery. MSU clinical and cost-effectiveness studies are emerging, but little is known about important factors for achieving sustainability of this innovative model of care.
Methods
Mixed-methods study from the Melbourne MSU (operational since November 2017) process evaluation. Participant purposive sampling included clinical, operational and executive/management representatives from Ambulance Victoria (AV) (emergency medical service provider), the MSU clinical team, and receiving hospitals. Sustainability was defined as ongoing MSU operations, including MSU workforce and future model considerations. Theoretically-based on-line survey with Unified Theory of Acceptance and Use of Technology (UTAUT), Self Determination Theory (SDT, Intrinsic Motivation), and open-text questions targeting barriers and benefits was administered (June-September 2019). Individual/group interviews were conducted, eliciting improvement suggestions and requirements for ongoing use. Descriptive and regression analyses (quantitative data) and directed content and thematic analysis (open text and interview data) were conducted.
Results
There were 135 surveys completed. Identifying that the MSU was beneficial to daily work (ÎČ = 0.61), not experiencing pressure/tension about working on the MSU (ÎČ = 0.17) and thinking they did well working within the team model (ÎČ = 0.17) were significantly associated with wanting to continue working within the MSU model [R2 = 0.76; F(15, 60) = 12.76, P < .001]. Experiences varied between those on the MSU team and those working with the MSU. Advantages were identified for patients (better, faster care) and clinicians (interdisciplinary learning). Disadvantages included challenges integrating into established systems, and establishing working relationships. Themes identified from 35 interviews were MSU team composition, MSU vehicle design and layout, personnel recruitment and rostering, communication improvements between organisations, telemedicine options, MSU operations and dispatch specificity.
Conclusion
Important factors affecting the sustainability of the MSU model of stroke care emerged. A cohesive team approach, with identifiable benefits and good communication between participating organisations is important for clinical and operational sustainability
Development and evaluation of a community-engaged research training program: Building capacity of Marshallese stakeholders and academic researchers to conduct health research
Pacific Islanders are a growing, yet understudied population who suffer from high rates of chronic diseases such as obesity and diabetes. Given the historical trauma experienced by Pacific Islanders, community-based participatory research (CBPR) is an appropriate way to conduct research focused on reducing the health disparities observed in this population. This paper presents the process of engaging the Marshallese community to design, conduct, and evaluate a community-engaged research training program. The goal of the program was to build the capacity of both academic researchers and community stakeholders to conduct CBPR for the purpose of addressing health disparities identified and prioritized by the Marshallese community. The program included both didactic training and experiential mentored research components delivered over a period of two years. Eleven Marshallese community stakeholders and eleven academic researchers participated in the program. Results indicated that the program successfully increased participantsâ knowledge regarding the CBPR process. Groups of participants have completed exploratory research projects based on the topics identified by the community. The evaluation adds important insights to the current CBPR training literature and can inform future CBPR trainings.
Keywords
community-basead participatory research, community-engaged research, Pacific Islanders, minority health, health disparities, interprofessional trainin
Land use and soil characteristics affect soil organisms differently from above-ground assemblages
Background:
Land-use is a major driver of changes in biodiversity worldwide, but studies have overwhelmingly focused on above-ground taxa: the effects on soil biodiversity are less well known, despite the importance of soil organisms in ecosystem functioning. We modelled data from a global biodiversity database to compare how the abundance of soil-dwelling and above-ground organisms responded to land use and soil properties.
Results:
We found that land use affects overall abundance differently in soil and above-ground assemblages. The abundance of soil organisms was markedly lower in cropland and plantation habitats than in primary vegetation and pasture. Soil properties influenced the abundance of soil biota in ways that differed among land uses, suggesting they shape both abundance and its response to land use.
Conclusions:
Our results caution against assuming models or indicators derived from above-ground data can apply to soil assemblages and highlight the potential value of incorporating soil properties into biodiversity models.Natural Environment Research Council (NERC): NE/L002515/1 and NE/M014533/1.
European Union funding: 81794
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Effect of Hydrocortisone on Mortality and Organ Support in Patients With Severe COVID-19: The REMAP-CAP COVID-19 Corticosteroid Domain Randomized Clinical Trial.
Importance: Evidence regarding corticosteroid use for severe coronavirus disease 2019 (COVID-19) is limited. Objective: To determine whether hydrocortisone improves outcome for patients with severe COVID-19. Design, Setting, and Participants: An ongoing adaptive platform trial testing multiple interventions within multiple therapeutic domains, for example, antiviral agents, corticosteroids, or immunoglobulin. Between March 9 and June 17, 2020, 614 adult patients with suspected or confirmed COVID-19 were enrolled and randomized within at least 1 domain following admission to an intensive care unit (ICU) for respiratory or cardiovascular organ support at 121 sites in 8 countries. Of these, 403 were randomized to open-label interventions within the corticosteroid domain. The domain was halted after results from another trial were released. Follow-up ended August 12, 2020. Interventions: The corticosteroid domain randomized participants to a fixed 7-day course of intravenous hydrocortisone (50 mg or 100 mg every 6 hours) (nâ=â143), a shock-dependent course (50 mg every 6 hours when shock was clinically evident) (nâ=â152), or no hydrocortisone (nâ=â108). Main Outcomes and Measures: The primary end point was organ support-free days (days alive and free of ICU-based respiratory or cardiovascular support) within 21 days, where patients who died were assigned -1 day. The primary analysis was a bayesian cumulative logistic model that included all patients enrolled with severe COVID-19, adjusting for age, sex, site, region, time, assignment to interventions within other domains, and domain and intervention eligibility. Superiority was defined as the posterior probability of an odds ratio greater than 1 (threshold for trial conclusion of superiority >99%). Results: After excluding 19 participants who withdrew consent, there were 384 patients (mean age, 60 years; 29% female) randomized to the fixed-dose (nâ=â137), shock-dependent (nâ=â146), and no (nâ=â101) hydrocortisone groups; 379 (99%) completed the study and were included in the analysis. The mean age for the 3 groups ranged between 59.5 and 60.4 years; most patients were male (range, 70.6%-71.5%); mean body mass index ranged between 29.7 and 30.9; and patients receiving mechanical ventilation ranged between 50.0% and 63.5%. For the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively, the median organ support-free days were 0 (IQR, -1 to 15), 0 (IQR, -1 to 13), and 0 (-1 to 11) days (composed of 30%, 26%, and 33% mortality rates and 11.5, 9.5, and 6 median organ support-free days among survivors). The median adjusted odds ratio and bayesian probability of superiority were 1.43 (95% credible interval, 0.91-2.27) and 93% for fixed-dose hydrocortisone, respectively, and were 1.22 (95% credible interval, 0.76-1.94) and 80% for shock-dependent hydrocortisone compared with no hydrocortisone. Serious adverse events were reported in 4 (3%), 5 (3%), and 1 (1%) patients in the fixed-dose, shock-dependent, and no hydrocortisone groups, respectively. Conclusions and Relevance: Among patients with severe COVID-19, treatment with a 7-day fixed-dose course of hydrocortisone or shock-dependent dosing of hydrocortisone, compared with no hydrocortisone, resulted in 93% and 80% probabilities of superiority with regard to the odds of improvement in organ support-free days within 21 days. However, the trial was stopped early and no treatment strategy met prespecified criteria for statistical superiority, precluding definitive conclusions. Trial Registration: ClinicalTrials.gov Identifier: NCT02735707
Effect of angiotensin-converting enzyme inhibitor and angiotensin receptor blocker initiation on organ support-free days in patients hospitalized with COVID-19
IMPORTANCE Overactivation of the renin-angiotensin system (RAS) may contribute to poor clinical outcomes in patients with COVID-19.
Objective To determine whether angiotensin-converting enzyme (ACE) inhibitor or angiotensin receptor blocker (ARB) initiation improves outcomes in patients hospitalized for COVID-19.
DESIGN, SETTING, AND PARTICIPANTS In an ongoing, adaptive platform randomized clinical trial, 721 critically ill and 58 nonâcritically ill hospitalized adults were randomized to receive an RAS inhibitor or control between March 16, 2021, and February 25, 2022, at 69 sites in 7 countries (final follow-up on June 1, 2022).
INTERVENTIONS Patients were randomized to receive open-label initiation of an ACE inhibitor (nâ=â257), ARB (nâ=â248), ARB in combination with DMX-200 (a chemokine receptor-2 inhibitor; nâ=â10), or no RAS inhibitor (control; nâ=â264) for up to 10 days.
MAIN OUTCOMES AND MEASURES The primary outcome was organ supportâfree days, a composite of hospital survival and days alive without cardiovascular or respiratory organ support through 21 days. The primary analysis was a bayesian cumulative logistic model. Odds ratios (ORs) greater than 1 represent improved outcomes.
RESULTS On February 25, 2022, enrollment was discontinued due to safety concerns. Among 679 critically ill patients with available primary outcome data, the median age was 56 years and 239 participants (35.2%) were women. Median (IQR) organ supportâfree days among critically ill patients was 10 (â1 to 16) in the ACE inhibitor group (nâ=â231), 8 (â1 to 17) in the ARB group (nâ=â217), and 12 (0 to 17) in the control group (nâ=â231) (median adjusted odds ratios of 0.77 [95% bayesian credible interval, 0.58-1.06] for improvement for ACE inhibitor and 0.76 [95% credible interval, 0.56-1.05] for ARB compared with control). The posterior probabilities that ACE inhibitors and ARBs worsened organ supportâfree days compared with control were 94.9% and 95.4%, respectively. Hospital survival occurred in 166 of 231 critically ill participants (71.9%) in the ACE inhibitor group, 152 of 217 (70.0%) in the ARB group, and 182 of 231 (78.8%) in the control group (posterior probabilities that ACE inhibitor and ARB worsened hospital survival compared with control were 95.3% and 98.1%, respectively).
CONCLUSIONS AND RELEVANCE In this trial, among critically ill adults with COVID-19, initiation of an ACE inhibitor or ARB did not improve, and likely worsened, clinical outcomes.
TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT0273570
Contrasting cognitive abilities in children with attention deficit hyperactivity disorder and reading disability
grantor:
University of TorontoAttention Deficit Hyperactivity Disorder (ADHD) and Reading Disabilities (RD) are common developmental disorders that frequently co-occur. In children who meet criteria for both disorders, it is not known if one disorder is primary, the other secondary or if both true disorders are present. The overall objective of this investigation was to test for the distinctiveness or independence of the two single disorders (ADHD-only, RD-only) and the independence of the two cognitive domains, executive function (EF) and phonological processing (PP), which are proposed as central to ADHD and RD respectively, using a classic double dissociation design. A 2 (ADHD vs. no ADHD) x 2 (RD vs. no RD) model was used to examine the cognitive profile of 4 groups of 17 children each, aged 7-11 years: ADHD, RD, ADHD+RD and controls. The EF tasks involved two measures of inhibitory control, while the phonological measures consisted of 3 tasks varying in level of phonemic processing required. A third measure, locus of control, was employed to investigate the role of attributions in the performance of children on these tasks. The two RD groups (RD, ADHD+RD) were significantly impaired relative to the two non-RD groups (controls, ADHD) on all phonological processing measures. The two ADHD groups were significantly impaired in terms of simple go-task responding relative to the non-ADHD groups and in terms of inhibitory control on both EF measures. Contrary to predictions, an RD effect on inhibitory control was found on one EF measure which involved rapid sequential processing. This finding, together with the ADHD impairment on non-EF aspects of the EF tasks, question the role of inhibitory control as a unique cognitive marker for ADHD. The comorbid group (ADHD+RD) generally exhibited the deficits of both single groups in an additive fashion, suggesting true comorbidity. An external locus of control was found to be associated with ADHD, not RD.Ph.D
Evaluation of the 1993-94 Bangladesh Demographic and Health Survey within the Matlab area
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