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10 result(s) for "Hawker, Rachel E."
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The temperature dependence of ice-nucleating particle concentrations affects the radiative properties of tropical convective cloud systems
Convective cloud systems in the maritime tropics play a critical role in global climate, but accurately representing aerosol interactions within these clouds persists as a major challenge for weather and climate modelling. We quantify the effect of ice-nucleating particles (INPs) on the radiative properties of a complex tropical Atlantic deep convective cloud field using a regional model with an advanced double-moment microphysics scheme. Our results show that the domain-mean daylight outgoing radiation varies by up to 18 W m−2 depending on the chosen INP parameterisation. The key distinction between different INP parameterisations is the temperature dependence of ice formation, which alters the vertical distribution of cloud microphysical processes. The controlling effect of the INP temperature dependence is substantial even in the presence of Hallett–Mossop secondary ice production, and the effects of secondary ice formation depend strongly on the chosen INP parameterisation. Our results have implications for climate model simulations of tropical clouds and radiation, which currently do not consider a link between INP particle type and ice water content. The results also provide a challenge to the INP measurement community, as we demonstrate that INP concentration measurements are required over the full mixed-phase temperature regime, which covers around 10 orders of magnitude.
Model emulation to understand the joint effects of ice-nucleating particles and secondary ice production on deep convective anvil cirrus
Ice crystal formation in the mixed-phase region of deep convective clouds can affect the properties of climatically important convectively generated anvil clouds. Small ice crystals in the mixed-phase cloud region can be formed by heterogeneous ice nucleation by ice-nucleating particles (INPs) and secondary ice production (SIP) by, for example, the Hallett–Mossop process. We quantify the effects of INP number concentration, the temperature dependence of the INP number concentration at mixed-phase temperatures, and the Hallett–Mossop splinter production efficiency on the anvil of an idealised deep convective cloud using a Latin hypercube sampling method, which allows optimal coverage of a multidimensional parameter space, and statistical emulation, which allows us to identify interdependencies between the three uncertain inputs. Our results show that anvil ice crystal number concentration (ICNC) is determined predominately by INP number concentration, with the temperature dependence of ice-nucleating aerosol activity having a secondary role. Conversely, anvil ice crystal size is determined predominately by the temperature dependence of ice-nucleating aerosol activity, with INP number concentration having a secondary role. This is because in our simulations ICNC is predominately controlled by the number concentration of cloud droplets reaching the homogeneous freezing level which is in turn determined by INP number concentrations at low temperatures. Ice crystal size, however, is more strongly affected by the amount of liquid available for riming and the time available for deposition growth which is determined by INP number concentrations at higher temperatures. This work indicates that the amount of ice particle production by the Hallett–Mossop process is determined jointly by the prescribed Hallett–Mossop splinter production efficiency and the temperature dependence of ice-nucleating aerosol activity. In particular, our sampling of the joint parameter space shows that high rates of SIP do not occur unless the INP parameterisation slope (the temperature dependence of the number concentration of particles which nucleate ice) is shallow, regardless of the prescribed Hallett–Mossop splinter production efficiency. A shallow INP parameterisation slope and consequently high ice particle production by the Hallett–Mossop process in our simulations leads to a sharp transition to a cloud with extensive glaciation at warm temperatures, higher cloud updraughts, enhanced vertical mass flux, and condensate divergence at the outflow level, all of which leads to a larger convectively generated anvil comprised of larger ice crystals. This work highlights the importance of quantifying the full spectrum of INP number concentrations across all mixed-phase altitudes and the ways in which INP and SIP interact to control anvil properties.
Design of Polymeric Zwitterionic Solid Electrolytes with Superionic Lithium Transport
Progress toward durable and energy-dense lithium-ion batteries has been hindered by instabilities at electrolyte–electrode interfaces, leading to poor cycling stability, and by safety concerns associated with energy-dense lithium metal anodes. Solid polymeric electrolytes (SPEs) can help mitigate these issues; however, the SPE conductivity is limited by sluggish polymer segmental dynamics. We overcome this limitation via zwitterionic SPEs that self-assemble into superionically conductive domains, permitting decoupling of ion motion and polymer segmental rearrangement. Although crystalline domains are conventionally detrimental to ion conduction in SPEs, we demonstrate that semicrystalline polymer electrolytes with labile ion–ion interactions and tailored ion sizes exhibit excellent lithium conductivity (1.6 mS/cm) and selectivity (t + ≈ 0.6–0.8). This new design paradigm for SPEs allows for simultaneous optimization of previously orthogonal properties, including conductivity, Li selectivity, mechanics, and processability.
Interventions on gender equity in the workplace: a scoping review
Background Various studies have demonstrated gender disparities in workplace settings and the need for further intervention. This study identifies and examines evidence from randomized controlled trials (RCTs) on interventions examining gender equity in workplace or volunteer settings. An additional aim was to determine whether interventions considered intersection of gender and other variables, including PROGRESS-Plus equity variables (e.g., race/ethnicity). Methods Scoping review conducted using the JBI guide. Literature was searched in MEDLINE, Embase, PsycINFO, CINAHL, Web of Science, ERIC, Index to Legal Periodicals and Books, PAIS Index, Policy Index File, and the Canadian Business & Current Affairs Database from inception to May 9, 2022, with an updated search on October 17, 2022. Results were reported using Preferred Reporting Items for Systematic Reviews and Meta-Analyses extension to scoping reviews (PRISMA-ScR), Sex and Gender Equity in Research (SAGER) guidance, Strengthening the Integration of Intersectionality Theory in Health Inequality Analysis (SIITHIA) checklist, and Guidance for Reporting Involvement of Patients and the Public (GRIPP) version 2 checklist. All employment or volunteer sectors settings were included. Included interventions were designed to promote workplace gender equity that targeted: (a) individuals, (b) organizations, or (c) systems. Any comparator was eligible. Outcomes measures included any gender equity related outcome, whether it was measuring intervention effectiveness (as defined by included studies) or implementation. Data analyses were descriptive in nature. As recommended in the JBI guide to scoping reviews, only high-level content analysis was conducted to categorize the interventions, which were reported using a previously published framework. Results We screened 8855 citations, 803 grey literature sources, and 663 full-text articles, resulting in 24 unique RCTs and one companion report that met inclusion criteria. Most studies (91.7%) failed to report how they established sex or gender. Twenty-three of 24 (95.8%) studies reported at least one PROGRESS-Plus variable: typically sex or gender or occupation. Two RCTs (8.3%) identified a non-binary gender identity. None of the RCTs reported on relationships between gender and other characteristics (e.g., disability, age, etc.). We identified 24 gender equity promoting interventions in the workplace that were evaluated and categorized into one or more of the following themes: (i) quantifying gender impacts; (ii) behavioural or systemic changes; (iii) career flexibility; (iv) increased visibility, recognition, and representation; (v) creating opportunities for development, mentorship, and sponsorship; and (vi) financial support. Of these interventions, 20/24 (83.3%) had positive conclusion statements for their primary outcomes (e.g., improved academic productivity, increased self-esteem) across heterogeneous outcomes. Conclusions There is a paucity of literature on interventions to promote workplace gender equity. While some interventions elicited positive conclusions across a variety of outcomes, standardized outcome measures considering specific contexts and cultures are required. Few PROGRESS-Plus items were reported. Non-binary gender identities and issues related to intersectionality were not adequately considered. Future research should provide consistent and contemporary definitions of gender and sex. Trial registration Open Science Framework https://osf.io/x8yae .
The ice-nucleating activity of African mineral dust in the Caribbean boundary layer
African mineral dust is transported many thousands of kilometres from its source regions, and, because of its ability to nucleate ice, it plays a major role in cloud glaciation around the globe. The ice-nucleating activity of desert dust is influenced by its mineralogy, which varies substantially between source regions and across particle sizes. However, in models it is often assumed that the activity (expressed as active sites per unit surface area as a function of temperature) of atmospheric mineral dust is the same everywhere on the globe. Here, we find that the ice-nucleating activity of African desert dust sampled in the summertime marine boundary layer of Barbados (July and August 2017) is substantially lower than parameterizations based on soil from specific locations in the Sahara or dust sedimented from dust storms. We conclude that the activity of dust in Barbados' boundary layer is primarily defined by the low K-feldspar content of the dust, which is around 1 %. We propose that the dust we sampled in the Caribbean was from a region in western Africa (in and around the Sahel in Mauritania and Mali), which has a much lower feldspar content than other African sources across the Sahara and Sahel.
Global evidence of gender equity in academic health research: a scoping review
ObjectivesTo chart the global literature on gender equity in academic health research.DesignScoping review.ParticipantsQuantitative studies were eligible if they examined gender equity within academic institutions including health researchers.Primary and secondary outcome measuresOutcomes related to equity across gender and other social identities in academia: (1) faculty workforce: representation of all genders in university/faculty departments, academic rank or position and salary; (2) service: teaching obligations and administrative/non-teaching activities; (3) recruitment and hiring data: number of applicants by gender, interviews and new hires for various rank; (4) promotion: opportunities for promotion and time to progress through academic ranks; (5) academic leadership: type of leadership positions, opportunities for leadership promotion or training, opportunities to supervise/mentor and support for leadership bids; (6) scholarly output or productivity: number/type of publications and presentations, position of authorship, number/value of grants or awards and intellectual property ownership; (7) contextual factors of universities; (8) infrastructure; (9) knowledge and technology translation activities; (10) availability of maternity/paternity/parental/family leave; (11) collaboration activities/opportunities for collaboration; (12) qualitative considerations: perceptions around promotion, finances and support.ResultsLiterature search yielded 94 798 citations; 4753 full-text articles were screened, and 562 studies were included. Most studies originated from North America (462/562, 82.2%). Few studies (27/562, 4.8%) reported race and fewer reported sex/gender (which were used interchangeably in most studies) other than male/female (11/562, 2.0%). Only one study provided data on religion. No other PROGRESS-PLUS variables were reported. A total of 2996 outcomes were reported, with most studies examining academic output (371/562, 66.0%).ConclusionsReviewed literature suggest a lack in analytic approaches that consider genders beyond the binary categories of man and woman, additional social identities (race, religion, social capital and disability) and an intersectionality lens examining the interconnection of multiple social identities in understanding discrimination and disadvantage. All of these are necessary to tailor strategies that promote gender equity.Trial registration numberOpen Science Framework: https://osf.io/8wk7e/.
Vaccinating healthcare workers against influenza to protect the vulnerable—Is it a good use of healthcare resources?A systematic review of the evidence and an economic evaluation
Influenza causes substantial mortality in high-risk groups despite targeted vaccination programmes. This paper considers whether it is worth vaccinating healthcare workers (HCWs) against influenza to protect high-risk patients in a series of systematic reviews and an economic evaluation. Eighteen studies are included. Vaccination was highly effective in HCWs, with minimal adverse effects. Two trials assessed patient mortality after vaccinating HCWs, both of which showed a reduction. Despite recommendations, less than 25% of HCW in Europe and the UK are vaccinated. Five studies looked at programmes to increase uptake; these produced increases of 5%-45%. Published economic evaluations did not include patient benefit; therefore, an economic evaluation using UK data was undertaken. In the base case, vaccination was cost saving (pounds 12/vaccinee). In the most pessimistic scenario it cost pounds 405/life-year gained. Effective implementation should be a priority.
Universal vaccination of children against influenza: Are there indirect benefits to the community?A systematic review of the evidence
We present a systematic review of the effectiveness of vaccinating healthy children to protect others. Primary studies were identified by searching standard electronic databases, internet sites, trials registers and citation lists to January 2004 and subjected to critical appraisal. Eight randomised controlled trials, three community studies and three economic evaluations met the inclusion criteria. The evidence suggests that vaccinating healthy children against influenza has the potential for reducing the impact of influenza epidemics. However, further evidence is needed as limitations of study design or execution mean that the community benefits are difficult to quantify.
Influenza vaccine in the over 65s
Probably has important benefits, despite recent doubts about its effectiveness