We examine Lyman's (Appl. Mech. Rev., vol. 43, issue 8, 1990, pp. 157–158) proposed definition of the boundary vorticity flux, as an alternative to the traditional definition provided by Lighthill (Introduction: boundary layer theory. In Laminar Boundary Layers (ed. L. Rosenhead), chap. 2, 1963, pp. 46–109. Oxford University Press). While either definition may be used to describe the generation and diffusion of vorticity, Lyman's definition offers several conceptual benefits. First, Lyman's definition can be interpreted as the transfer of circulation across a boundary, due to the acceleration of that boundary, and is therefore closely tied to the dynamics of linear momentum. Second, Lyman's definition allows the vorticity creation process on a solid boundary to be considered essentially inviscid, effectively extending Morton's (Geophys. Astrophys. Fluid Dyn., vol. 28, 1984, pp. 277–308) two-dimensional description to three-dimensional flows. Third, Lyman's definition describes the fluxes of circulation acting in any two-dimensional reference surface, enabling a control-surface analysis of three-dimensional vortical flows. Finally, Lyman's definition more clearly illustrates how the kinematic condition that vortex lines do not end in the fluid is maintained, providing an elegant description of viscous processes such as vortex reconnection. The flow over a sphere, in either translational or rotational motion, is examined using Lyman's definition of the vorticity flux, demonstrating the benefits of the proposed framework in understanding the dynamics of vortical flows.

This article examines numerically the two-dimensional fluid–structure interaction problem of a circular cylinder rolling under gravity along an inclined surface under the assumption of a fixed but small gap. The motion of the cylinder is governed by the ratio of cylinder and fluid densities and the Reynolds number based on a velocity scale derived from the momentum balance in the asymptotic regime. For increasing Reynolds number, the cylinder wake undergoes a transition from steady to periodic flow, causing oscillations of the cylinder motion. The critical Reynolds number increases for light cylinders. Whereas the time-averaged characteristics of the asymptotic rolling states depend only on the Reynolds number, the density ratio has an additional influence on the vibration amplitude and on the cylinder motion during a start-up transient from rest. Light cylinders reach their final state quickly after the initial acceleration; heavier cylinders traverse a series of quasi-steady states, including a temporary velocity overshoot, before settling in the asymptotic regime. The amplitudes of the flow-induced vibrations remain small over the entire parameter range, which can be attributed to the value of the added-mass force associated with a rolling cylinder. Special attention is paid to the influence of the small but finite gap between cylinder and wall, since lubrication theory predicts a diverging pressure drag for a vanishing gap. The variations with gap size of the forces, torque and added mass are explored. The gap also influences the characteristics of the cylinder vibrations in the unsteady wake regime, in particular their amplitude.

This article argues that the politics of extraterritorial jurisdiction in the 1920s reshaped relations between ethnicity and territorial sovereignty in Ethiopia's eastern borderlands. A 1925 criminal trial involving Gadabursi Somalis began as what Britons deemed a ‘tribal matter’ to be settled through customary means, but became a struggle for Ethiopia's regent, Ras Tafari, to assert Ethiopia's territorial authority and imperial sovereignty. British claims of extraterritorial jurisdiction over Somalis amidst 1920s global geopolitical shifts disrupted existing practices of governance in Ethiopia's eastern borderlands and created a dilemma for Ethiopian authorities. In order to uphold international obligations, Ethiopian officials effectively had to revoke their sovereignty over some Somalis indigenous to Ethiopia. Yet Britons’ practical application of extraterritoriality to Somalis was predicated on assumed racial differences between Somalis and highland Ethiopians (‘Abyssinians’). Thus, Ethiopia's recognition of British extraterritorial jurisdiction would lend legitimacy to claims exempting Somalis from Ethiopian sovereignty due to differences in identity. The case reveals how assertions about race, nationality and ‘tribal’ identity articulated to subordinate Ethiopian rule to British interests and, in the longer term, to delegitimize Ethiopian governance over Somalis.

The evolution of resistance to multiple herbicides in Palmer amaranth is a major challenge for its management. In this study, a Palmer amaranth population from Hutchinson, Kansas (HMR), was characterized for resistance to inhibitors of photosystem II (PSII) (e.g., atrazine), acetolactate synthase (ALS) (e.g., chlorsulfuron), and EPSP synthase (EPSPS) (e.g., glyphosate), and this resistance was investigated. About 100 HMR plants were treated with field-recommended doses (1×) of atrazine, chlorsulfuron, and glyphosate, separately along with Hutchinson multiple-herbicide (atrazine, chlorsulfuron, and glyphosate)–susceptible (HMS) Palmer amaranth as control. The mechanism of resistance to these herbicides was investigated by sequencing or amplifying the psbA, ALS, and EPSPS genes, the molecular targets of atrazine, chlorsulfuron, and glyphosate, respectively. Fifty-two percent of plants survived a 1× (2,240 g ai ha−1) atrazine application with no known psbA gene mutation, indicating the predominance of a non–target site resistance mechanism to this herbicide. Forty-two percent of plants survived a 1× (18 g ai ha−1) dose of chlorsulfuron with proline197serine, proline197threonine, proline197alanine, and proline197asparagine, or tryptophan574leucine mutations in the ALS gene. About 40% of the plants survived a 1× (840 g ae ha−1) dose of glyphosate with no known mutations in the EPSPS gene. Quantitative PCR results revealed increased EPSPS copy number (50 to 140) as the mechanism of glyphosate resistance in the survivors. The most important finding of this study was the evolution of resistance to at least two sites of action (SOAs) (~50% of plants) and to all three herbicides due to target site as well as non–target site mechanisms. The high incidence of individual plants with resistance to multiple SOAs poses a challenge for effective management of this weed.

We identify an incorrect term in the expression for the rate of change of circulation of a material volume including an interface between two fluids which appears in Brøns et al. (J. Fluid Mech., vol. 758, 2014, pp. 63–93).

In the last three decades, early intervention for psychosis (EIP) services have been established worldwide and have resulted in superior symptomatic and functional outcomes for people affected by psychotic disorders. These improved outcomes are a result of reducing delays to treatment and the provision of specialised, holistic interventions. The COVID-19 pandemic poses significant challenges to the delivery of these services, such as undetected cases or long delays to treatment. Furthermore, the COVID-19 pandemic will likely increase the mental health needs of communities, including the incidence of psychotic disorders. In this perspective piece, we provide suggestions as to how EIP services can adapt within this environment, such as utilising novel technologies. Finally, we argue that despite the economic consequences of the pandemic, the funding for mental health services, including EI services, should be increased in line with the need for these services during and beyond the pandemic.

Introduction: The emergency department (ED) is often the first point of health care contact for patients with mild traumatic brain injury (MTBI). Spontaneous resolution occurs in most patients within 7 days, yet 15-30% will develop post-concussion syndrome (PCS). Given the paucity of effective management strategies to prevent PCS and emerging evidence supporting exercise, the objective of this study was to evaluate the impact of prescribed early light exercise compared to standard discharge instructions for acute MTBI patients in the ED. Methods: This was a randomized controlled trial conducted in three Canadian EDs. Consecutive, adult (18-64 years) ED patients with a MTBI sustained within the preceding 48 hours were eligible for enrollment. The intervention group received discharge instructions prescribing 30 minutes of daily light exercise (e.g., walking), and the control group was given standard MTBI instructions advising gradual return to exercise following symptom resolution. Participants documented their daily physical activities and completed follow-up questionnaires at 7, 14, and 30 days. The primary outcome was the proportion of patients with PCS at 30 days, defined as the presence of ≥ 3 symptoms on the Rivermead Post-concussion Symptoms Questionnaire (RPQ) at 30 days. Results: 367 patients were enrolled (control n = 184; intervention n = 183). Median age was 32 years and 201 (57.6%) were female. There was no difference in the proportion of patients with PCS at 30 days (control 13.4 vs intervention 14.6; Δ1.2, 95% CI: -6.2 to 8.5). There were no differences in median change of RPQ scores (control 14 vs intervention 13; Δ1, 95% CI: -1 to 4), median number of return health care provider visits (control 1 vs intervention 1; Δ0, 95% CI: 0 to 0), or median number of missed school or work days (control 2 vs intervention 2; Δ0, 95% CI: 0 to 1) at 30 days. There was a nonsignificant difference in unplanned return ED visits within 30 days (control 9.9% vs intervention 5.6%; Δ1, 95% CI: -1.4 to 10.3). Participants in the control group reported fewer minutes of light exercise at 7 days (30 vs 35; Δ5, 95% CI: 2 to 15). Conclusion: To our knowledge, this is the first randomized trial of prescribed early light exercise for adults with acute MTBI. There were no differences in recovery or healthcare utilization outcomes. Results suggest prescribed early light exercise should be encouraged as tolerated at ED discharge following MTBI, but exercise prescription alone is not sufficient to prevent PCS.

Introduction: eCTAS is a real time electronic triage decision-support tool designed to improve patient safety and quality of care by standardizing the application of the Canadian Triage and Acuity Scale (CTAS). The tool dynamically calculates a recommended CTAS score based on the presenting complaint, vital signs and selected clinical modifiers. The primary objective was to assess consistency of CTAS score distributions across 35 emergency departments (EDs) by 16 presenting complaints pre and post eCTAS implementation. Methods: This retrospective cohort study used population-based administrative data from January 2016 to December 2018 from all hospital EDs in Ontario that had implemented eCTAS with at least 9 months of data. Following a 3-month stabilization period, we compared data for 6 months post-eCTAS implementation to the same 6-month period the previous year (pre-implementation) to account for potential seasonal variation, patient volume and case-mix. We included triage encounters of adult (≥18 years) patients if they had one of 16 pre-specified high-volume, presenting complaints. A paired-samples t-test was used to determine consistency by estimating the absolute difference in CTAS distribution for each presenting complaint, by each hospital, pre and post eCTAS implementation, compared to the overall average of the 35 EDs. Results: There were 183,231 triage encounters in the pre-eCTAS cohort and 179,983 in the post-eCTAS cohort from 35 EDs across the province. Triage scores were more consistent with the overall average after eCTAS implementation in 6 (37.5%) presenting complaints: chest pain (cardiac features) (p < 0.001), extremity weakness/symptoms of cerebrovascular accident (p < 0.001), fever (p < 0.001), shortness of breath (p < 0.001), syncope (p = 0.02), and hyperglycemia (p = 0.03). Triage consistency was similar pre and post eCTAS implementation for the presenting complaints of altered level of consciousness, anxiety/situational crisis, confusion, depression/suicidal/deliberate self-harm, general weakness, head injury, palpitations, seizure, substance misuse/intoxication or vertigo. Conclusion: A standardized, electronic approach to performing triage assessments increased consistency in CTAS scores across many, but not all, high-volume CEDIS complaints. This does not reflect triage accuracy, as there are no known benchmarks for triage accuracy. Improvements in consistency were greatest for sentinel presenting complaints with a minimum allowable CTAS score.

Background: Massive hemorrhage protocols (MHPs) streamline the complex logistics required for prompt care of the bleeding patient, but their uptake has been variable and few regions have a system to measure outcomes from these events. Aim Statement: We aim to implement a standardized MHP with uniform quality improvement (QI) metrics to increase uptake of evidence-based MHPs across 150-hospitals in Ontario between 2017 and 2021. Measures & Design: We performed ongoing PDSA cycles; 1) stakeholder analysis by surveying the Ontario Regional Blood Coordinating Network (ORBCoN), 2) problem characterization and Ishikawa analysis for key QI metrics based on areas of MHP variability in 150 Ontario hospitals using a web-based survey, 3) creation of a consensus MHP via a modified Delphi process, 4) problem characterization at ORBCoN for the design of a freely available toolkit for provincial implementation by expert working groups, 5) design of 8 key QI metrics by a modified Delphi process, and 6) identification of process measures for QI data collection by implementation metrics. Evaluation/Results: PDSA1-2; 150-hospitals were surveyed. 33% of hospitals lacked MHPs, mostly in smaller sites. Major areas for QI were related to activation criteria, hemostatic agents, protocolized hypothermia management, variable MHP naming, QI metrics and serial blood work requirements. PDSA3; 3 Delphi rounds were held to reach 100% expert consensus for 42 statements and 8 CQI metrics. Major areas for modification were protocol name, laboratory resuscitation targets, cooler configurations, and role of factor VIIa. PDSA4; adaptable toolkit is under development by the steering committee and expert working groups. Implementation is scheduled for Spring 2020. PDSA5; the 8 CQI metrics are: TXA administration < 1 h, RBC transfusion < 15 min, call to transfer for definitive care < 60 min, temp >35°C at end of protocol, Hgb kept between 60-110g/L, transition to group-specific RBC by 90 min, appropriate activation defined by ≥6 units RBC in the first 24 hours, and any blood component wastage. Discussion/Impact: MHP uptake, content, and tracking is variable. A standardized MHP that is adaptable to diverse settings decreases complexity, improves use of evidence-based practices, and provides a platform for continuous QI. PDSA6 will occur after implementation; we will complete an implementation survey, and design a pilot and feasibility study for prospective tracking of patient outcomes using existing prospectively collected inter-hospital and provincial databases.

Introduction: The emergency department (ED) is the first point of health care contact for most head injured patients. Although early and spontaneous resolution occurs in most patients with mild traumatic brain injury (MTBI), between 15-30% develop post-concussion syndrome (PCS). To date, clinical prediction tools do not yet exist to accurately identify adult MTBI patients at risk of PCS. The objective of this study was to identify predictors of PCS within 30 days in adults with acute MTBI presenting to the ED. Methods: This was a secondary analysis of a randomized controlled trial conducted in three Canadian EDs evaluating prescribed light exercise compared to standard care. Adult (18-64 years) patients with a MTBI sustained within the preceding 48 hours were eligible for enrollment. Participants completed follow-up questionnaires at 7, 14, and 30 days. The primary outcome was the presence of PCS at 30 days, defined as the presence of ≥ 3 symptoms on the Rivermead Post-concussion Symptoms Questionnaire (RPQ) at 30 days. Backward, stepwise, multivariable logistic regression with a removal criterion probability of 0.05 was conducted to determine predictor variables independently associated with PCS at 30 days. Likelihood ratio tests were used to determine appropriate inclusion of variables in the multivariable model. Results are reported as odds ratios (OR) with 95% confidence intervals (CIs). Results: A total of 367 patients were enrolled, 18 (4.9%) withdrew, and 108 (29.4%) were lost to follow-up. Median (IQR) age was 32 (25 to 48) years, and 201 (57.6%) were female. Of the 241 patients who completed follow-up, 49 (20.3%) had PCS at 30 days. Headache at ED presentation (OR = 6.59; 95% CI: 1.31 to 33.11), being under the influence of drugs or alcohol at the time of injury (OR = 4.42; 95% CI: 1.31 to 14.88), the injury occurring via bike or motor vehicle collision (OR = 2.98; 95% CI: 1.39 to 6.40), history of anxiety or depression (OR = 2.49; 95% CI: 1.23 to 5.03), and the sensation of numbness or tingling at ED presentation (OR = 2.25; 95% CI: 1.04 to 4.88), were independently associated with PCS at 30 days. Conclusion: Five variables were found to be significant predictors of PCS. Although MTBI is a self-limited condition in the majority of patients, patients with these risk factors should be considered high risk and flagged for early follow-up. There continues to be an urgent need for a clinical prognostic tool that accurately identifies adult patients at risk for PCS early in their injury.

This article presents a revised formulation of the generation and transport of vorticity at generalised fluid–fluid interfaces, substantially extending the work of Brøns et al. (J. Fluid Mech., vol. 758, 2014, pp. 63–93). Importantly, the formulation is effectively expressed in terms of the conservation of vorticity, and the latter is shown to hold for arbitrary deformation and normal motion of the interface; previously, vorticity conservation had only been demonstrated for stationary interfaces. The present formulation also affords a simple physical description of the generation of vorticity in incompressible, Newtonian flows: the only mechanism by which vorticity may be generated on an interface is the inviscid relative acceleration of fluid elements on each side of the interface, due to pressure gradients or body forces. Viscous forces act to transfer circulation between the vortex sheet representing the interface slip velocity, and the fluid interior, but do not create vorticity on the interface. Several representative example flows are considered and interpreted under the proposed framework, illustrating the generation, transport and, importantly, the conservation of vorticity within these flows.

Animal disease events can lead to international trade restrictions which can vary in duration, products included, and geographical extent. Accounting for multilateral resistance between trading partners, a general gravity model of trade is estimated with a Hausman-Taylor and a Hausman-Taylor seemingly unrelated estimator to evaluate the trade quantity impact by commodity resulting from highly pathogenic poultry disease events in 24 exporting markets. Commodity specific results show that quantity traded and products demanded during a disease event differ by commodities. Understanding these impacts can better prepare exporters for potential changes in trade quantity given a disease event.

Conditions and evidence continue to evolve related to the prediction of the prevalence of immunodeficiency-associated long-term vaccine-derived poliovirus (iVDPV) excreters, which affect assumptions related to forecasting risks and evaluating potential risk management options. Multiple recent reviews provided information about individual iVDPV excreters, but inconsistencies among the reviews raise some challenges. This analysis revisits the available evidence related to iVDPV excreters and provides updated model estimates that can support future risk management decisions. The results suggest that the prevalence of iVDPV excreters remains highly uncertain and variable, but generally confirms the importance of managing the risks associated with iVDPV excreters throughout the polio endgame in the context of successful cessation of all oral poliovirus vaccine use.

Herbicides have been a primary means of managing undesirable brush on grazing lands across the southwestern United States for decades. Continued encroachment of honey mesquite and huisache on grazing lands warrants evaluation of treatment life and economics of current and experimental treatments. Treatment life is defined as the time between treatment application and when canopy cover of undesirable brush returns to a competitive level with native forage grasses (i.e., 25% canopy cover for mesquite and 30% canopy cover for huisache). Treatment life of industry-standard herbicides was compared with that of aminocyclopyrachlor plus triclopyr amine (ACP+T) from 10 broadcast-applied honey mesquite and five broadcast-applied huisache trials established from 2007 through 2013 across Texas. On average, the treatment life of industry standard treatments (IST) for huisache was 3 yr. In comparison, huisache canopy cover was only 2.5% in plots treated with ACP+T 3 yr after treatment. The average treatment life of IST for honey mesquite was 8.6 yr, whereas plots treated with ACP+T had just 2% mesquite canopy cover at that time. Improved treatment life of ACP+T compared with IST life was due to higher mortality resulting in more consistent brush canopy reduction. The net present values (NPVs) of ACP+T and IST for both huisache and mesquite were similar until the treatment life of the IST application was reached (3 yr for huisache and 8.6 yr for honey mesquite). At that point, NPVs of the programs diverged as a result of brush competition with desirable forage grasses and additional input costs associated with theoretical follow-up IST necessary to maintain optimum livestock forage production. The ACP+T treatments did not warrant a sequential application over the 12-yr analysis for huisache or 20-yr analysis for honey mesquite that this research covered. These results indicate ACP+T provides cost-effective, long-term control of honey mesquite and huisache.