On the molecular correlations that result in field-dependent conductivities in electrolyte solutions.

Employing recent advances in response theory and nonequilibrium ensemble reweighting, we study the dynamic and static correlations that give rise to an electric field-dependent ionic conductivity in electrolyte solutions. We consider solutions modeled with both implicit and explicit solvents, with different dielectric properties, and at multiple concentrations. Implicit solvent models at low concentrations and small dielectric constants exhibit strongly field-dependent conductivities. We compare these results to Onsager-Wilson theory of the Wien effect, which provides a qualitatively consistent prediction at low concentrations and high static dielectric constants but is inconsistent away from these regimes. The origin of the discrepancy is found to be increased ion correlations under these conditions. Explicit solvent effects act to suppress nonlinear responses, yielding a weakly field-dependent conductivity over the range of physically realizable field strengths. By decomposing the relevant time correlation functions, we find that the insensitivity of the conductivity to the field results from the persistent frictional forces on the ions from the solvent. Our findings illustrate the utility of nonequilibrium response theory in rationalizing nonlinear transport behavior.

Field-Dependent Ionic Conductivities from Generalized Fluctuation-Dissipation Relations.

We derive a relationship for the electric field dependent ionic conductivity in terms of fluctuations of time integrated microscopic variables. We demonstrate this formalism with molecular dynamics simulations of solutions of differing ionic strength with implicit solvent conditions and molten salts. These calculations are aided by a novel nonequilibrium statistical reweighting scheme that allows for the conductivity to be computed as a continuous function of the applied field. In strong electrolytes, we find the fluctuations of the ionic current are Gaussian, and subsequently, the conductivity is constant with applied field. In weaker electrolytes and molten salts, we find the fluctuations of the ionic current are strongly non-Gaussian, and the conductivity increases with applied field. This nonlinear behavior, known phenomenologically for dilute electrolytes as the Onsager-Wien effect, is general and results from the suppression of ionic correlations at large applied fields, as we elucidate through both dynamic and static correlations within nonequilibrium steady states.

Nonlinear transport coefficients from large deviation functions.

Nonlinear response occurs naturally when a strong perturbation takes a system far from equilibrium. Despite its omnipresence in nanoscale systems, it is difficult to predict in a general and efficient way. Here, we introduce a way to compute arbitrarily high order transport coefficients of stochastic systems, using the framework of large deviation theory. Leveraging time reversibility in the microscopic dynamics, we relate nonlinear response to equilibrium multitime correlation functions among both time reversal symmetric and asymmetric observables, which can be evaluated from derivatives of large deviation functions. This connection establishes a thermodynamiclike relation for nonequilibrium response and provides a practical route to its evaluation, as large deviation functions are amenable to importance sampling. We demonstrate the generality and efficiency of this method in predicting transport coefficients in single particle systems and an interacting system exhibiting thermal rectification.

Implementing Foundry: A cohort study describing the regional and virtual expansion of a youth integrated service in British Columbia, Canada.

AIM: Integrated youth services (IYS) have been identified as a national priority in response to the youth mental health and substance use (MHSU) crisis in Canada. In British Columbia (BC), an IYS initiative called Foundry expanded to 11 physical centres and launched a virtual service. The aim of the study was to describe the demographics of Foundry clients and patterns of service utilization during this expansion, along with the impact of the COVID-19 pandemic. METHODS: Data were analysed for all youth (ages 12-24) accessing both in-person (April 27th, 2018-March 31st, 2021) and virtual (May 1st, 2020-March 31st, 2021) services. Cohorts containing all clients from before (April 27th, 2018-March 16th, 2020) and during (March 17th, 2020-March 31st, 2021) the COVID-19 pandemic were also examined. RESULTS: A total of 23 749 unique youth accessed Foundry during the study period, with 110 145 services provided. Mean client age was 19.54 years (SD = 3.45) and 62% identified as female. Over 60% of youth scored 'high' or 'very high' for distress and 29% had a self-rated mental health of 'poor', with similar percentages seen for all services and virtual services. These ratings stayed consistent before and during the COVID-19 pandemic. CONCLUSIONS: Foundry has continued to reach the target age group, with a 65% increase in number of clients during the study period compared with the pilot stage. This study highlights lessons learned and next steps to promote youth-centred data capture practices over time within an integrated youth services context.

Informing youth-centred opioid agonist treatment: Findings from a retrospective chart review of youths' characteristics and patterns of opioid agonist treatment engagement in a novel integrated youth services program.

AIM: Youth ages 12-24 account for approximately 20% of overdoses and yet are poorly reached by opioid agonist treatment (OAT), the most widely recommended treatment for opioid use disorder (OUD). This study contributes to understanding this critical gap by describing youths' patterns of OAT engagement at a novel integrated youth-specific OAT program. METHODS: A retrospective chart review was carried out on electronic medical records of n = 23 youth with OUD accessing a community-based integrated youth services (IYS) centre. Data abstraction focused on four domains: sociodemographic, social determinants of health, patterns of OAT engagement, and other services utilized. RESULTS: Youths' mean age was 22.6 years (SD = 2.1), with a mean age of first opioid use of 17.4 (SD = 2.7). Youth reported extensive histories of adverse childhood experiences, concurrent mental and physical health complications, and poly-substance use. All youth were offered OAT and 83% initiated treatment with buprenorphine/naloxone, methadone, or slow-release oral morphine. Among those initiating OAT, 42.1% were considered stable on OAT. CONCLUSIONS: To our knowledge, this is the first empirical study to describe youths' OAT engagement in an integrated youth-specific OAT program. Our findings demonstrated that a high proportion of youth with OUD initiated OAT in this novel program with varying degrees of OAT stability. These findings can be used to inform the development and implementation of youth-specific and integrated OAT. To account for the novelty of this area of study and small sample sizes, future collaborative efforts across IYS initiatives should be considered, including mixed method approaches to understand outcomes and experiences.

Rasch analysis of the beck depression inventory in a homeless and precariously housed sample.

The approach to analysis of and interpretation of findings from the Beck Depression Inventory (BDI), a self-report questionnaire, depends on sample characteristics. To extend work using conventional BDI scoring, the BDI's suitability in assessing symptom severity in a homeless and precariously housed sample was examined using Rasch analysis. Participants (n=478) recruited from an impoverished neighbourhood in Vancouver, Canada, completed the BDI. Rasch analysis using the partial credit model was done, and the structural validity, unidimensionality, and reliability of the BDI were studied. A receiver operating characteristic curve determined a Rasch cut-off score consistent with clinical depression, and Rasch scores were correlated with raw scores. Good fit to the Rasch model was observed after rescoring all items and removing Item 19 (Weight Loss), and unidimensionality and reliability were satisfactory. Item 9 (Suicidal Wishes) represented the most severe symptom. Rasch-based scores detected clinical depression with moderate sensitivity and specificity, and were positively correlated with conventional scores. The BDI in a community-based sample of homeless and precariously housed adults satisfied Rasch model expectations in a 20-item format, and is suitable for assessing symptom severity. Future research on depression in similar samples may reveal more information on using specific symptoms to determine clinical significance.

Remote Aerosol Simulated During the Atmospheric Tomography (ATom) Campaign and Implications for Aerosol Lifetime.

We investigate and assess how well a global chemical transport model (GEOS-Chem) simulates submicron aerosol mass concentrations in the remote troposphere. The simulated speciated aerosol (organic aerosol (OA), black carbon, sulfate, nitrate, and ammonium) mass concentrations are evaluated against airborne observations made during all four seasons of the NASA Atmospheric Tomography Mission (ATom) deployments over the remote Pacific and Atlantic Oceans. Such measurements over pristine environments offer fresh insights into the spatial (Northern [NH] and Southern Hemispheres [SH], Atlantic, and Pacific Oceans) and temporal (all seasons) variability in aerosol composition and lifetime, away from continental sources. The model captures the dominance of fine OA and sulfate aerosol mass concentrations in all seasons. There is a high bias across all species in the ATom-2 (NH winter) simulations; implementing recent updates to the wet scavenging parameterization improves our simulations, eliminating the large ATom-2 (NH winter) bias, improving the ATom-1 (NH summer) and ATom-3 (NH fall) simulations, but producing a model underestimate in aerosol mass concentrations for the ATom-4 (NH spring) simulations. Following the wet scavenging updates, simulated global annual mean aerosol lifetimes vary from 1.9 to 4.0 days, depending on species. Aerosol lifetimes in each hemisphere vary by season, and are longest for carbonaceous aerosol during the southern hemispheric fire season. The updated wet scavenging parameterization brings simulated concentrations closer to observations and reduces global aerosol lifetime for all species, indicating the sensitivity of global aerosol lifetime and burden to wet removal processes.

The effects of dietary nitrate supplementation on endurance exercise performance and cardiorespiratory measures in healthy adults: a systematic review and meta-analysis.

BACKGROUND: Nitrate supplementation is thought to improve performance in endurance sports. OBJECTIVE: To meta-analyze studies evaluating the effect of nitrate supplementation on endurance sports performance among adults. DATA SOURCES: We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, EMBASE, Web of Science and CINAHL without language restrictions. METHODS: We included studies that: 1) compared nitrate supplementation with placebo; 2) enrolled adults engaging in an endurance-based activity; and 3) reported a performance measure or surrogate physiologic outcome. We evaluated risk of bias using the Cochrane Collaboration tool and pooled data with a random-effects model. We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to evaluate confidence in estimates. RESULTS: We included 73 studies (n = 1061). Nitrate supplementation improved power output (MD 4.6 watts, P < 0.0001), time to exhaustion (MD 25.3 s, P < 0.00001), and distance travelled (MD 163.7 m, P = 0.03). We found no significant difference on perceived exertion, time trial performance and work done. Nitrate supplementation decreased VO2 (MD - 0.04 L/min, P < 0.00001) but had no significant effect on VO2max or blood lactate levels. CONCLUSION: The available evidence suggests that dietary nitrate supplementation benefits performance-related outcomes for endurance sports.

Atmospheric boundary layer turbulence structure for severe foggy haze episodes in north China in December 2016.

This paper aims to identify the atmospheric boundary layer turbulence structure and its effect on severe foggy haze events frequently occurring in Northern China. We use data collected from a ground eddy covariance system, meteorology tower, and a PM2.5 collector in Baoding, China during December 2016. The data shows that 73.5% of PM2.5 concentration is greater than 100 µg m-3 with a maximum of 522 µg m-3. Analyses on vertical turbulence spectrum also reveal that 1) during the pollution period, lower wind can suppress large-scale turbulence eddies, which are more likely inhomogeneous, breaking into small-scale eddies, and 2) the air pollutant scattering effect for radiation could decrease the air temperature near the ground and generate weak vertical turbulence during the daytime. At night, air pollutants suppress the land surface cooling and decrease the air temperature difference as well as the vertical turbulence intensity difference. The vertical turbulence impact analysis reveals that the percentage of large-scale turbulence eddies can also change the atmospheric vertical mixing capacity. During the daytime, the air pollution evolution is controlled by the wind speed and vertical turbulence intensity. While at night, the vertical turbulence is weak and the atmospheric vertical mixing capacity is mainly controlled by the large-scale eddies' percentage. The increased number of large-scale turbulence eddies led by low wind at night could increase the vertical mixing of air pollutants and decrease its concentration near the ground.

Parabolic dependence of the drag coefficient on wind speed from aircraft eddy-covariance measurements over the tropical Eastern Pacific.

In this study, we examine and present the relationship between drag coefficient and wind speed. We used an observational dataset that consists of 806 estimates of the mean flow and fluxes from aircraft eddy-covariance measurements over the tropical Eastern Pacific. To estimate the saturated wind speed threshold, we regressed the drag coefficients for wind speed scope from 10 ms-1 to 28 ms-1. Results show that the relationship between drag coefficient and wind speed is parabolic. Additionally, the saturated wind speed threshold is 22.33 ms-1 when regressed from drag coefficient, and it is 22.65 ms-1 when regressed from the medium number of drag coefficient for each bin.

Why and how to use patient-oriented research to promote translational research.

As we discussed in our first editorial in the December 2018 issue (Polaha & Sunderji, 2018), an emerging science of knowledge translation (also known as implementation and dissemination science) aims to bridge the disconnect between evidence and practice. Researchers are increasingly engaging with knowledge users and other stakeholders as a key strategy to promote uptake. This may include policymakers, payers, and-the focus of this editorial-patients. Patient-oriented research is featured in national research agendas around the world including in Canada (Canadian Institutes of Health Research, 2018) and the United States (Patient-Centered Outcomes Research Institute, see https://www.pcori.org/), in part as it may contribute one solution to the "bench to bedside" gap (Greenhalgh, Jackson, Shaw, & Janamian, 2016; Jull, Giles, & Graham, 2017; McGavin, 2017). In this editorial, we provide a general introduction to research, its potential, and its realized value. We also suggest strategies for conducting patient-oriented research effectively, including a description of common barriers and how they can be dealt with. We hope this background will inspire you to get started with patient-oriented research and to learn more, as well as to share your patient-oriented research through Families, Systems, & Health. (PsycINFO Database Record (c) 2019 APA, all rights reserved).