Generation of near-equipartition magnetic fields in turbulent collisionless plasmas

The mechanisms that generate "seed" magnetic fields in our Universe and that amplify them throughout cosmic time remain poorly understood. By means of fully-kinetic particle-in-cell simulations of turbulent, initially unmagnetized plasmas, we study the genesis of magnetic fields via the Weibel instability and follow their dynamo growth up to near-equipartition levels. In the kinematic stage of the dynamo, we find that the rms magnetic field strength grows exponentially with rate $\gamma_B \simeq 0.4\,u_{\rm rms}/L$, where $L/2 \pi$ is the driving scale and $u_{\rm rms}$ is the rms turbulent velocity. In the saturated stage, the magnetic field energy reaches about half of the turbulent kinetic energy. Here, magnetic field growth is balanced by dissipation via reconnection, as revealed by the appearance of plasmoid chains. At saturation, the integral-scale wavenumber of the magnetic spectrum approaches $k_{\rm int}\simeq 12\pi/L$. Our results show that turbulence -- induced by, e.g., the gravitational build-up of galaxies and galaxy clusters -- can magnetize collisionless plasmas with large-scale near-equipartition fields.Comment: 10 pages, 10 figures, PRL in pres

Collisional cross sections and momentum distributions in astrophysical plasmas: dynamics and statistical mechanics link

We show that, in stellar core plasmas, the one-body momentum distribution function is strongly dependent, at least in the high velocity regime, on the microscopic dynamics of ion elastic collisions and therefore on the effective collisional cross sections, if a random force field is present. We take into account two cross sections describing ion-dipole and ion-ion screened interactions. Furthermore we introduce a third unusual cross section, to link statistical distributions and a quantum effect originated by the energy-momentum uncertainty owing to many-body collisions, and propose a possible physical interpretation in terms of a tidal-like force. We show that each collisional cross section gives rise to a slight peculiar correction on the Maxwellian momentum distribution function in a well defined velocity interval. We also find a possible link between microscopical dynamics of ions and statistical mechanics interpreting our results in the framework of non-extensive statistical mechanics.Comment: 8 page

Tapinarof Cream 1% Once Daily for the Treatment of Plaque Psoriasis: Case Photography of Clinical Outcomes from Three Phase 3 Trials

Tapinarof cream 1% (VTAMA(®); Dermavant Sciences, Inc.) is a non-steroidal, topical, aryl hydrocarbon receptor agonist approved by the US Food and Drug Administration (FDA) to treat plaque psoriasis in adults and under investigation for the treatment of psoriasis in children down to 2 years of age, and for atopic dermatitis in adults and children down to 2 years of age. The PSOARING phase 3 clinical trial program evaluated tapinarof cream 1% once daily (QD) in adults with mild to severe plaque psoriasis for up to 52 weeks (NCT03956355, NCT03983980, NCT04053387). Here we present case photography documenting outcomes in the PSOARING trials. Cases illustrate various outcomes across different body areas, including responses meeting the formal FDA-mandated regulatory endpoint of a Physician Global Assessment (PGA) score of 0 (clear) or 1 (almost clear) and a decrease of at least 2 points from baseline at week 12, meaningful clinical improvement not meeting this formal endpoint, patient-reported outcomes, and pre-specified adverse events of special interest (AESIs). Tapinarof cream 1% QD demonstrated rapid and highly statistically significant efficacy, with improvements in disease activity and quality of life. In addition, a high rate (40.9%; n = 312/763) of complete disease clearance (PGA = 0) was achieved, and improvements exceeding National Psoriasis Foundation treatment goals were demonstrated. After first achieving complete disease clearance (PGA = 0), patients treated with tapinarof experienced an approximately 4-month remittive effect off therapy. Incidence and severity of folliculitis and contact dermatitis AESIs were generally mild or moderate, localized to the site of application, and associated with low discontinuation rates. Medical images are of importance in trials of dermatologic therapies to inform clinical decision-making and enhance patient assessment. Tapinarof cream 1% QD is efficacious and well tolerated in patients with mild to severe plaque psoriasis, with clinically relevant improvements seen early in the course of treatment. Clinicaltrials.gov numbers: NCT03956355, NCT03983980, NCT04053387

Values - reviewing the construct and drawing implications for values work in organisation and leadership. Kap. 2

I: H.Askeland, G. Espedal, B. Jelstad Løvaas & S. Sirris (Eds.), Understanding values work : Institutional perspectives in organizations and leadershipThis chapter outlines the trajectory of values, particularly within streams of organisational institutionalism, in order to analyse its application to values work in organisation and leadership. Conveying a frame for discussing values work, it aims at clarifying how to conceptualise the term values. Discussing classic and recent contributions, the chapter proposes seeing values as individual and collective conceptions of desirable trans-situational behaviours, objectives and ideals, serving to guide or valuate practice. Despite being an essential part of defining organisational institutionalism, and its sub-streams, values are seldom explicated. Utilising values in organisational and leadership research requires attention to their situatedness in contexts, and this chapter argues they are salient to organisations operating in pluralistic institutional environment. Studying values work, attention should be given to who and how such work is performed.publishedVersio

Conceptualizing historical organization studies

© 2016 Academy of Management Review. The promise of a closer union between organizational and historical research has long been recognized. However, its potential remains unfulfilled: The authenticity of theory development expected by organization studies and the authenticity of historical veracity required by historical research place exceptional conceptual and empirical demands on researchers. We elaborate the idea of historical organization studies-organizational research that draws extensively on historical data, methods, and knowledge to promote historically informed theoretical narratives attentive to both disciplines. Building on prior research, we propose a typology of four differing conceptions of history in organizational research: History as evaluating, explicating, conceptualizing, and narrating. We identify five principles of historical organization studies-dual integrity, pluralistic understanding, representational truth, context sensitivity, and theoretical fluency-and illustrate our typology holistically from the perspective of institutional entrepreneurship. We explore practical avenues for a creative synthesis, drawing examples from social movement research and microhistory. Historically informed theoretical narratives whose validity derives from both historical veracity and conceptual rigor afford dual integrity that enhances scholarly legitimacy, enriching understanding of historical, contemporary, and future-directed social realities

Is concern about young people's anti-social behaviour associated with poor health? cross-sectional evidence from residents of deprived urban neighbourhoods

<p><b>Background:</b> Young people in disadvantaged neighbourhoods are often the focus of concerns about anti-social behaviour (ASB). There is inconsistent evidence to support the hypothesis that perceptions of ASB (PASB) are associated with poor health. We ask whether perceptions of young people's ASB are associated with poor health; and whether health, demographic and (psycho)social characteristics can help explain why PASB varies within disadvantaged neighbourhoods (Glasgow, UK).</p> <p><b>Methods:</b> Regression analysis of survey data exploring associations between perceiving teenagers hanging around to be a serious neighbourhood problem and SF-12v2 mental and physical health scores (higher = better), including adjustment for demographic characteristics. Further analysis explored associations with self-reported measures of health service use, psychosocial characteristics of homes and neighbourhoods and social contacts.</p> <p><b>Results:</b> 6008 adults participated (50% response) and 22% (n = 1,332) said teenagers were a serious neighbourhood problem (the most frequently reported local problem). Demographic characteristics associated with perceiving serious teenager problems included regular health service use, age (inverse relationship), financial problems and living with children. Lower SF-12v2 physical health scores were associated with perceiving teenager problems after adjustment for demographic variables (OR 0.98; 95%CI 0.97,0.99; p = < 0.001), whilst adjusted findings for mental health scores were less conclusive (OR 0.99; 95%CI 0.98,1.00; p = 0.103). Further analysis suggested that perceiving teenager problems was more strongly associated with a number of self-reported psychosocial factors: e.g. lacking social support, < weekly family contacts, poor neighbourhood safety, low trust in neighbours, neighbourhood perceived to be a barrier to self-esteem, and neighbourhood decline.</p> <p><b>Conclusions:</b> Given the evidence we found of weak and small associations between PASB and health, we caution against assuming that tackling concern about teenagers' ASB will lead to substantial public health gains in disadvantaged areas. Although the findings do not present a compelling case for making PASB a public health priority, it is still important to address concerns about young people's ASB. Reasons for doing so may include improving social cohesion, reducing fear and isolation, and improving the general quality of people's lives - particularly in neighbourhoods burdened by multiple disadvantages. Future research should evaluate interventions that attempt to reduce PASB in disadvantaged areas. Findings from this study could help inform the targeting of such interventions.</p&gt

Operationalizing frailty among older residents of assisted living facilities

<p>Abstract</p> <p>Background</p> <p>Frailty in later life is viewed as a state of heightened vulnerability to poor outcomes. The utility of frailty as a measure of vulnerability in the assisted living (AL) population remains unexplored. We examined the feasibility and predictive accuracy of two different interpretations of the Cardiovascular Health Study (CHS) frailty criteria in a population-based sample of AL residents.</p> <p>Methods</p> <p>CHS frailty criteria were operationalized using two different approaches in 928 AL residents from the Alberta Continuing Care Epidemiological Studies (ACCES). Risks of one-year mortality and hospitalization were estimated for those categorized as frail or pre-frail (compared with non-frail). The prognostic significance of individual criteria was explored, and the area under the ROC curve (AUC) was calculated for select models to assess the utility of frailty in predicting one-year outcomes.</p> <p>Results</p> <p>Regarding feasibility, complete CHS criteria could not be assessed for 40% of the initial 1,067 residents. Consideration of supplementary items for select criteria reduced this to 12%. Using absolute (CHS-specified) cut-points, 48% of residents were categorized as frail and were at greater risk for death (adjusted risk ratio [RR] 1.75, 95% CI 1.08-2.83) and hospitalization (adjusted RR 1.54, 95% CI 1.20-1.96). Pre-frail residents defined by absolute cut-points (48.6%) showed no increased risk for mortality or hospitalization compared with non-frail residents. Using relative cut-points (derived from AL sample), 19% were defined as frail and 55% as pre-frail and the associated risks for mortality and hospitalization varied by sex. Frail (but not pre-frail) women were more likely to die (RR 1.58 95% CI 1.02-2.44) and be hospitalized (RR 1.53 95% CI 1.25-1.87). Frail and pre-frail men showed an increased mortality risk (RR 3.21 95% CI 1.71-6.00 and RR 2.61 95% CI 1.40-4.85, respectively) while only pre-frail men had an increased risk of hospitalization (RR 1.58 95% CI 1.15-2.17). Although incorporating either frailty measure improved the performance of predictive models, the best AUCs were 0.702 for mortality and 0.633 for hospitalization.</p> <p>Conclusions</p> <p>Application of the CHS criteria for frailty was problematic and only marginally improved the prediction of select adverse outcomes in AL residents. Development and validation of alternative approaches for detecting frailty in this population, including consideration of female/male differences, is warranted.</p