Dispersion of biased swimming microorganisms in a fluid flowing through a tube

Classical Taylor-Aris dispersion theory is extended to describe the transport of suspensions of self-propelled dipolar cells in a tubular flow. General expressions for the mean drift and effective diffusivity are determined exactly in terms of axial moments, and compared with an approximation a la Taylor. As in the Taylor-Aris case, the skewness of a finite distribution of biased swimming cells vanishes at long times. The general expressions can be applied to particular models of swimming microorganisms, and thus be used to predict swimming drift and diffusion in tubular bioreactors, and to elucidate competing unbounded swimming drift and diffusion descriptions. Here, specific examples are presented for gyrotactic swimming algae.Comment: 20 pages, 4 figures. Published version available at http://rspa.royalsocietypublishing.org/content/early/2010/02/09/rspa.2009.0606.short?rss=

Full throttle: Are motorcyclists as risk-taking as we think?

Background:Motorcycling, whether thought of as a leisure activity, hobby, or social activity, can add quality to one’s life. Being a member of a motorcycle club may promote a sense of community, while motorcycling itself may increase feelings of awe and joy. When conceptualized as part of one’s social identity, motorcycling tends to be associated with an unfavourable image or stereotype, wherein motorcyclists’ personalities are characterized as rebellious, prone to risk-taking behaviour, and masculine (regardless of the motorcyclist’s gender). The accuracy of this stereotype is unclear, particularly as perceived by non-motorcyclists, such as car drivers. Accordingly, the overall purpose of this exploratory study was to describe the personality profile of motorcyclists from a basic trait perspective (Big 5) and assess its congruence with non-motorcyclists’ perceptions of the “typical” motorcyclist’s personality.Participants and procedure:A cross-sectional online survey (N = 376) consisting of motorcyclists (n = 194) and car drivers (n = 182) collected information on personality traits (self-report or perceived), riding behaviour (motorcyclists only), and well-being.Results:The results show that car drivers perceive motorcyclists to be more disinhibited, less open, more neurotic, less agreeable, and less conscientious than motorcyclists self-report.Conclusions:Car drivers’ perceptions of motorcyclists seem to be more negative than their actual personalities, suggesting an unfavoura-ble judgement of that community

Loneliness and sense of community are not two sides of the same coin: Identifying different determinants using the 2019 Nova Scotia Quality of Life data

The purpose of this study was to explore the relative importance of lifestyle factors and living conditions when predicting loneliness and sense of community (SOC) in a representative sample of 12,871 participants from Nova Scotia collected in 2019. Using multiple regression and measures of relative importance based on the Lindeman, Merenda and Gold (lmg) method, we identified which variables are most important to predicting measures of loneliness and SOC. Twenty-two predictors accounted for 46% of the variance in SOC and the top 10 predictors accounted for 36% of the variance: satisfaction with quality of the natural environment in the neighborhood (ri = 0.09), life satisfaction (ri = 0.05), number of neighbors one can rely on (ri = 0.05), confidence in institutions (ri = 0.05), feeling better off due to government policy or programming (ri = 0.04), feeling safe walking in neighborhood after dark (ri = 0.03), mental health (ri = 0.02), number of friends one can rely on (ri = 0.02), volunteering (ri = 0.02), and perceptions of time adequacy (ri = 0.02). Only six of these variables were also the top predictors of loneliness. These results show that both community- and individual-level variables are substantial predictors of social well-being. The effect sizes differ between models, which suggests that there may be important predictors of loneliness that we have not accounted for. This study may inform community-level programming and policy that seeks to promote social well-being for individuals and their communities.</p

Clarifying the concept of mental health literacy:Protocol for a scoping review

This scoping review will chart the peer-reviewed literature to clarify the concept of mental health literacy (MHL) and how it can be measured. MHL is an emerging area of study within mental health promotion, as programming and policy efforts devoted to promoting mental health emerge. Enhancing MHL in the general population is a strategy for promoting mental health by reducing stigma and empowering individuals to recognize, interpret, and understand their mental health, and know when to seek help for themselves and others. Despite the positive outcomes associated with MHL, conceptualization varies in scope, purpose, process, and outcome; there is little consensus of what “counts” as MHL. A clearly defined conceptualization of MHL is needed to support research, programming, and policy in mental health promotion. Papers on the theoretical and conceptual principles underlying MHL and primary studies documenting MHL initiatives and methods will be included. A scoping literature search will be performed following the search protocol for scoping reviews by JBI to identify all relevant literature on MHL. Searches will be conducted in five scientific databases; there will be no time limit imposed, although all sources must be written in English or French. Identifying the conceptualization and measurement of MHL in research that is guiding mental health interventions will provide conceptual clarity, ultimately advancing knowledge of mental health literacy

Relative Importance of Individual and Community Predictors of Wellbeing

Inspired by theory in wellbeing science, we examined the relative importance of lifestyle factors and living conditions when predicting two dimensions of wellbeing (hedonic and eudaimonic) in a representative sample of 12,826 participants from Nova Scotia collected in 2019. Using multiple regression and measures of relative importance based on the Lindeman, Merenda and Gold (lmg) method, we identified which variables are most important to predicting life satisfaction and life worth. Twenty-two predictors accounted for 51% of the variance in life satisfaction, of which six accounted for 40% of the variance: self-rated mental health (11%), time adequacy (8%), satisfaction with natural environment (7%), sense of community (5%), financial insecurity (5%), and self-rated physical health (3%). These variables were also the top predictors of life worthwhileness, although all 22 predictors (R2 = 0.42) and these six predictors (R2 = 0.26) accounted for less variance than for life satisfaction. These results show that both community-level (i.e., environmental quality of neighbourhood, sense of community) and individual-level (i.e., mental health, time adequacy, financial insecurity, and physical health) factors are substantial predictors of wellbeing. The effect sizes differ between the hedonistic and eudaimonic dimensions of wellbeing, suggesting there may be important predictors of eudaimonic wellbeing not accounted for. This study may inform where community-level programming and policy could focus resources more effectively to promote wellbeing for individuals and their communities

Validation of magnetophonon spectroscopy as a tool for analyzing hot-electron effects in devices

It is shown that very high precision hot-electron magnetophonon experiments made on n+n−n+-GaAs sandwich device structures which are customized for magnetoresistance measurements can be very accurately modeled by a new Monte Carlo technique. The latter takes account of the Landau quantization and device architecture as well as material parameters. It is proposed that this combination of experiment and modeling yields a quantitative tool for the direct analysis of spatially localized very nonequilibrium electron distributions in small devices and low dimensional structures

Crafting happiness from everyday life:Personality, personal projects, basic psychological need satisfaction, and well-being

Introduction: Feeling competent, related, and autonomous promotes well-being through satisfying basic psychological needs, according to self-determination theory’s basic psychological need satisfaction mini-theory. Personal projects are personally relevant goal-directed activities that take place over an extended period. The quality of life elicited from pursuing personal projects depends on the degree to which projects provide a sense of relatedness, competence, and autonomy. We expected that, when controlling for perfectionistic standards and discrepancies, achievement striving would lead to the pursual of projects that provide a sense of competence, which in turn leads to well-being. We also explored autonomy and relatedness as mediators. Methods: The sample (N = 327) was composed of students and the general adult population who provided information on positive mental health, passion, zest for life, life purpose, personality, basic psychological need satisfaction, and personal projects. We used a cross-sectional survey design and tested hypotheses with twelve serial mediation models. Results: Achievement striving and personal standards were positively associated with competence, which in turn predicted well-being in 12 of 12 indirect effects tested. Achievement striving, personal standards and discrepancies contributed to change in well-being through relatedness or autonomy in 9 of 24 of exploratory indirect effects tested. Discussion: Those oriented toward achievement motivation are likely to feel competent in their pursuits (personal projects), which in turn promotes well-being. Pursuing personal projects that suit one’s personality (i.e., make it more likely to meet basic psychological needs) may be a tool to boost well-being

The association of self-efficacy, anxiety sensitivity, and perfectionism with statistics and math anxiety

Statistics and math anxiety are pervasive problems for post-secondary students. We hypothesized that self-efficacy would be negatively related to math/statistics anxiety, and that anxiety sensitivity and perfectionism would be positively related to math/statistics anxiety, even when controlling for gender, university program, and education level. Method: Graduate and undergraduate students (N = 447, after exclusions) completed an online self-report questionnaire, including an abbreviated version of the Statistics Anxiety Rating Scale (STARS), math anxiety, self-efficacy, anxiety sensitivity, perfectionism, and demographics. Results: Exploratory factor analysis supported a six-factor structure for statistics anxiety. Self-efficacy was negatively associated with math/statistics anxiety, whereas anxiety sensitivity and perfectionism were positively associated with math/statistics anxiety. Relationships ranged from small-to-moderate, and most relationships persisted after adding covariates. Discussion: Our study suggests the feasibility of a short-form version of the STARS. Moreover, it provides important information on how personality is associated with domain-specific anxiety that can impede statistics education

The transition to irreversibility in sheared suspensions: An analysis based on a mesoscopic entropy production

We study the shear-induced diffusion effect and the transition to irreversibility in suspensions under oscillatory shear flow by performing an analysis of the entropy production associated to the motion of the particles. We show that the Onsager coupling between different contributions to the entropy production is responsible for the scaling of the mean square displacement on particle diameter and applied strain. We also show that the shear-induced effective diffusion coefficient depends on the volume fraction and use Lattice-Boltzmann simulations to characterize the effect through the power spectrum of particle positions for different Reynolds numbers and volume fractions. Our study gives a thermodynamic explanation of the the transition to irreversibility through a pertinent analysis of the second law of thermodynamics.Comment: 17 pages, 3 figures, paper submitted tp phys rev

Length Scales of Acceleration for Locally Isotropic Turbulence

Length scales are determined that govern the behavior at small separations of the correlations of fluid-particle acceleration, viscous force, and pressure gradient. The length scales and an associated universal constant are quantified on the basis of published data. The length scale governing pressure spectra at high wave numbers is discussed. Fluid-particle acceleration correlation is governed by two length scales; one arises from the pressure gradient, the other from the viscous force.Comment: 2 figures, 4 pages. Physical Review Letters, accepted August 200