Learning From Lived Experience: Substance Use Policies, Emergency Shelters, and Harm Reduction in London, ON

Since 2018, the number of overdoses reported by London housing and emergency shelter agencies to the city of London has increased by 790%.These agencies currently have inconsistent overdose response policies that lack research-based support, and want to establish comprehensive best practices that support those involved at all levels. Through a community based course, we initially collected and analyzed survey data from managers and staff from various London housing and emergency shelter agencies with the aim of understanding the limitations of the current approaches to the opioid crisis. Wanting to expand on this, our current project focuses on those who are experiencing homelessness or substance use personally. With a focus on lived experience, we hope to expand the conversation surrounding homelessness/precarious housing and substance use to include their stories as we continue to develop new substance use policies for housing and emergency shelter agencies in London

A cultural study of social disagreement strategies by Iranian EFL male and female learners

The speech act of disagreement is one of the neglected areas of research in the Iranian context. This study seeks to investigate the ways in which this act is expressed by young male and female Persian speakers. To collect the data 100 participants (50 males, 50 females,) were selected randomly from among undergraduate and graduate students of University of Isfahan and Islamic Azad University (Najafabad branch). The focus of this study was the role that gender and power might play in the employment of strategies to mitigate the threat of the act of disagreement. Students were asked to complete a discourse completion test (DCT) designed by the researcher. They were supposed to read nine situations, and react to them via making disagreements. Respondents were expected to disagree with three interlocutors with higher status, three peers and three with lower status. In order to analyze the utterances of disagreement, Muntigl and Turnbull’s taxonomy (1998) was employed. The results revealed that although both males and females were concerned about the power status of interlocutors and try to apply the appropriate strategies while expressing their disagreements, females were more cautious

Self-organized criticality of turbulence in strongly stratified mixing layers

Motivated by the importance of stratified shear flows in geophysical and environmental circumstances, we characterize their energetics, mixing and spectral behaviour through a series of direct numerical simulations of turbulence generated by Holmboe wave instability (HWI) under various initial conditions. We focus on circumstances where the stratification is sufficiently ‘strong’ so that HWI is the dominant primary instability of the flow. Our numerical findings demonstrate the emergence of self-organized criticality (SOC) that is manifest as an adjustment of an appropriately defined gradient Richardson number, $Ri_{g}$, associated with the horizontally averaged mean flow, in such a way that it is continuously attracted towards a critical value of $Ri_{g}\sim 1/4$. This self-organization occurs through a continuously reinforced localization of the ‘scouring’ motions (i.e. ‘avalanches’) that are characteristic of the turbulence induced by the breakdown of Holmboe wave instabilities and are developed on the upper and lower flanks of the sharply localized density interface, embedded within a much more diffuse shear layer. These localized ‘avalanches’ are also found to exhibit the expected scale-invariant characteristics. From an energetics perspective, the emergence of SOC is expressed in the form of a long-lived turbulent flow that remains in a ‘quasi-equilibrium’ state for an extended period of time. Most importantly, the irreversible mixing that results from such self-organized behaviour appears to be characterized generically by a universal cumulative turbulent flux coefficient of \unicode[STIX]{x1D6E4}_{c}\sim 0.2 only for turbulent flows engendered by Holmboe wave instability. The existence of this self-organized critical state corroborates the original physical arguments associated with self-regulation of stratified turbulent flows as involving a ‘kind of equilibrium’ as described by Turner (1973, Buoyancy Effects in Fluids, Cambridge University Press).H.S. acknowledges the SOSCIP TalentEdge post doctoral fellowship and is grateful to the David Crighton Fellowship from D.A.M.T.P., University of Cambridge. All the computations were performed on the BG/Q supercomputer at the University of Toronto which is operated by SciNet for the Southern Ontario Smart Computing Innovation Platform. SciNet is funded by: the Canada Foundation for Innovation under the auspices of Compute Canada; the Government of Ontario; Ontario Research Fund - Research Excellence; and the University of Toronto. The research of W.R.P. at the University of Toronto is sponsored by NSERC Discovery Grant A9627. The research activity of C.P.C. is supported by EPSRC Programme Grant EP/K034529/1 entitled `Mathematical Underpinning of Stratified Turbulence'

Turbulent mixing due to the Holmboe wave instability at high Reynolds number

We consider numerically the transition to turbulence and associated mixing in stratified shear flows with initial velocity distribution $\overline{U}(z,0)\,\boldsymbol{e}_{x}=U_{0}\,\boldsymbol{e}_{x}\tanh (z/d)$ and initial density distribution \overline{\unicode[STIX]{x1D70C}}(z,0)=\unicode[STIX]{x1D70C}_{0}[1-\tanh (z/\unicode[STIX]{x1D6FF})] away from a hydrostatic reference state \unicode[STIX]{x1D70C}_{r}\gg \unicode[STIX]{x1D70C}_{0}. When the ratio R=d/\unicode[STIX]{x1D6FF} of the characteristic length scales over which the velocity and density vary is equal to one, this flow is primarily susceptible to the classic well-known Kelvin–Helmholtz instability (KHI). This instability, which typically manifests at finite amplitude as an array of elliptical vortices, strongly ‘overturns’ the density interface of strong initial gradient, which nevertheless is the location of minimum initial gradient Richardson number Ri_{g}(0)=Ri_{b}=g\unicode[STIX]{x1D70C}_{0}d/\unicode[STIX]{x1D70C}_{r}U_{0}^{2}, where Ri_{g}(z)=-([g/\unicode[STIX]{x1D70C}_{r}]\,\text{d}\overline{\unicode[STIX]{x1D70C}}/\text{d}z)/(\text{d}\overline{U}/\text{d}z)^{2} and $Ri_{b}$ is a bulk Richardson number. As is well known, at sufficiently high Reynolds numbers ($Re$), the primary KHI induces a vigorous but inherently transient burst of turbulence and associated irreversible mixing localised in the vicinity of the density interface, leading to a relatively well-mixed region bounded by stronger density gradients above and below. We explore the qualitatively different behaviour that arises when $R\gg 1$, and so the density interface is sharp, with $Ri_{g}(z)$ now being maximum at the density interface $Ri_{g}(0)=RRi_{b}$. This flow is primarily susceptible to Holmboe wave instability (HWI) (Holmboe, Geophys. Publ., vol. 24, 1962, pp. 67–113), which manifests at finite amplitude in this symmetric flow as counter-propagating trains of elliptical vortices above and below the density interface, thus perturbing the interface so as to exhibit characteristically cusped interfacial waves which thereby ‘scour’ the density interface. Unlike previous lower-$Re$ experimental and numerical studies, when $Re$ is sufficiently high the primary HWI becomes increasingly more three-dimensional due to the emergence of shear-aligned secondary convective instabilities. As $Re$ increases, (i) the growth rate of secondary instabilities appears to saturate and (ii) the perturbation kinetic energy exhibits a $k^{-5/3}$ spectrum for sufficiently large length scales that are influenced by anisotropic buoyancy effects. Therefore, at sufficiently high $Re$, vigorous turbulence is triggered that also significantly ‘scours’ the primary density interface, leading to substantial irreversible mixing and vertical transport of mass above and below the (robust) primary density interface. Furthermore, HWI produces a markedly more long-lived turbulence event compared to KHI at a similarly high $Re$. Despite their vastly different mechanics (i.e. ‘overturning’ versus ‘scouring’) and localisation, the mixing induced by KHI and HWI is comparable in both absolute terms and relative efficiency. Our results establish that, provided the flow Reynolds number is sufficiently high, shear layers with sharp density interfaces and associated locally high values of the gradient Richardson number may still be sites of substantial and efficient irreversible mixing.This research has been conducted in part while H.S. visited DAMTP, University of Cambridge. H.S. is grateful to the David Crighton Fellowship from DAMTP. All the computations were performed on the BG/Q supercomputer of SOSCIP (the Southern Ontario Smart Computing Innovation Platform) which is hosted by the University of Toronto. The research activity of C.P.C. is supported by EPSRC Programme Grant EP/K034529/1 entitled `Mathematical Underpinning of Strati ed Turbulence'. The research of W.R.P. at the University of Toronto is supported by NSERC Discovery Grant A9627.This is the author accepted manuscript. It is currently under an indefinite embargo pending publication by Cambridge University Press

The study of disagreement strategies to suggestions used by Iranian male and female learners

This study seeks to investigate the ways in which the speech act of disagreement is expressed by young male and female Persian speakers. To collect the data 100 participants (50 males, 50 females,) were selected randomly from among undergraduate and graduate students of University of Isfahan and Islamic Azad University (Najafabad branch). The focus of this study was on the role that gender and power might play in the employment of strategies to mitigate the threat of disagreement. Students were asked to complete a discourse completion test (DCT) designed by the researcher. They were supposed to read nine suggestions situations, and react to them via making disagreements. Respondents were expected to disagree with three interlocutors with higher status, three peers and three with lower status. In order to analyze the utterances of disagreement, Muntigl and Turnbull’s taxonomy (1998) was employed. The results revealed that although both males and females were concerned about the power status of interlocutors and try to apply the appropriate strategies while expressing their disagreements, females were more cautious and used different strategies from those of males

Impact of variable fluid properties on forced convection of Fe3O4/CNT/water hybrid nanofluid in a double-pipe mini-channel heat exchanger

The objective of this study is to assess the hydrothermal performance of a non-Newtonian hybrid nanofluid with temperature-dependent thermal conductivity and viscosity compared with a Newtonian hybrid nanofluid with constant thermophysical properties. A counter-current double-pipe mini-channel heat exchanger is studied to analyze the effects of the hybrid nanofluid. The nanofluid is employed as the coolant in the tube side, while the hot water flows in the annulus side. Two different nanoparticles including tetramethylammonium hydroxide-coated Fe3O4 (magnetite) nanoparticles and gum arabic-coated carbon nanotubes are used to prepare the water-based hybrid nanofluid. The results demonstrated that the non-Newtonian hybrid nanofluid always has a higher heat transfer rate, overall heat transfer coefficient, and effectiveness than those of the Newtonian hybrid nanofluid, while the opposite is true for the pressure drop, pumping power, and performance evaluation criterion. Supposing that the Fe3O4-carbon nanotube/water hybrid nanofluid is a Newtonian fluid with constant thermal conductivity and viscosity, there leads to large error in the computation of pressure drop (1.5–9.71%), pumping power (1.5–9.71%), and performance evaluation criterion (18.24–19.60%), whereas the errors in the computation of heat transfer rate, overall heat transfer coefficient, and effectiveness are not considerable (less than 2.91%)