1,192 research outputs found

    Key actors leading knowledge brokerage for sustainable school improvement with PLCs:Who brokers what?

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    This study investigated knowledge brokerage key actors, in schools that realized sustainable school improvement through professional learning communities (PLCs). To gain insight into what knowledge key actors brokered and how they brokered knowledge, key actors at five secondary schools that worked sustainably with PLCs participated in an in-depth mixed-method study. The findings showed what types of knowledge were brokered and through what activities, what characteristics of key actors were important for knowledge brokerage, and how key actors fit different profiles. These insights can help schools improve their knowledge brokerage as they work towards sustainable school improvement

    Mental models of the protein shift: Exploring consumers' perceptions of the transition

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    The protein transition is one of today's major societal challenges to mitigate climate change. To support lasting consumer engagement, it has been suggested to look into consumers' understanding of the protein transition to identify barriers that go beyond the practical issues of changing one's diet. The current study explored consumers' mental models of how the transition unfolds to examine which factors consumers perceive as important drivers of the transition. With a fixed set of factors and actors identified with a questionnaire, Dutch consumers (N = 214) mapped their mental models. The content and structure of the mental models were analyzed with a focus on how consumers perceive their own role. Animal well-being and environmental concerns were most often included as important drivers. The findings showed a lack of consensus about which actor(s) drive the transition (i.e., none of the actors were included by a majority of the participants). This diffusion of responsibility may be a barrier for consumers to act. Moreover, the relative simplicity of the observed mental models suggests that consumers do not yet employ systems thinking. A systems thinking mindset may help consumers understand how the system behind the transition works and how their individual contributions matter. Two avenues to encourage consumer engagement were identified: 1) emphasizing the responsibility of different actors and what consumers can contribute, and 2) encouraging a systems thinking mindset

    Change in Tetracene Polymorphism Facilitates Triplet Transfer in Singlet Fission-Sensitized Silicon Solar Cells

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    Singlet fission in tetracene generates two triplet excitons per absorbed photon. If these triplet excitons can be effectively transferred into silicon (Si) then additional photocurrent can be generated from photons above the bandgap of Si. This could alleviate the thermalization loss and increase the efficiency of conventional Si solar cells. Here we show that a change in the polymorphism of tetracene deposited on Si due to air exposure, facilitates triplet transfer from tetracene into Si. Magnetic field-dependent photocurrent measurements confirm that triplet excitons contribute to the photocurrent. The decay of tetracene delayed photoluminescence was used to determine a triplet transfer time of 215 ns and a maximum yield of triplet transfer into Si of ~50 %. Our study suggests that control over the morphology of tetracene during deposition will be of great importance to boost the triplet transfer yield further

    Magnetic properties of the frustrated AFM spinel ZnCr_2O_4 and the spin-glass Zn_{1-x}Cd_xCr_2O_4 (x=0.05,0.10)

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    The TT-dependence (2- 400 K) of the electron paramagnetic resonance (EPR), magnetic susceptibility, χ(T)\chi (T), and specific heat, Cv(T)C_{v}(T), of the normalnormal antiferromagnetic (AFM) spinel ZnCr2_{2}O4_{4} and the spin-glass (SG) Zn1x_{1-x}Cdx_{x}Cr2_{2}O4_{4} (x=0.05,0.10x=0.05,0.10) is reported. These systems behave as a strongly frustrated AFM and SG with % T_{N} TG12 \approx T_{G}\approx 12 K and -400 K ΘCW500\gtrsim \Theta_{CW}\gtrsim -500 K. At high-TT the EPR intensity follows the χ(T)\chi (T) and the gg-value is TT-independent. The linewidth broadens as the temperature is lowered, suggesting the existence of short range AFM correlations in the paramagnetic phase. For ZnCr2_{2}O4_{4} the EPR intensity and χ(T)\chi (T) decreases below 90 K and 50 K, respectively. These results are discussed in terms of nearest-neighbor Cr3+^{3+} (S =3/2=3/2%) spin-coupled pairs with an exchange coupling of J/k| J/k| \approx 50 K. The appearance of small resonance modes for T17T\lesssim 17 K, the observation of a sharp drop in χ(T)\chi (T) and a strong peak in Cv(T)C_{v}(T) at TN=12T_{N}=12 K confirms, as previously reported, the existence of long range AFM correlations in the low-TT phase. A comparison with recent neutron diffraction experiments that found a near dispersionless excitation at 4.5 meV for TTNT\lesssim T_{N} and a continuous gapless spectrum for TTNT\gtrsim T_{N}, is also given.Comment: 17 pages, 8 figures, 1 Table. Submitted to Physical Review

    Identification of adults with symptoms suggestive of obstructive airways disease: Validation of a postal respiratory questionnaire

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    BACKGROUND: Two simples scoring systems for a self-completed postal respiratory questionnaire were developed to identify adults who may have obstructive airways disease. The objective of this study was to validate these scoring systems. METHOD: A two-stage design was used. All adults in two practice populations were sent the questionnaire and a stratified random sample of respondents was selected to undergo full clinical evaluation. Three respiratory physicians reviewed the results of each evaluation. A majority decision was reached as to whether the subject merited a trial of obstructive airways disease medication. This clinical decision was compared with two scoring systems based on the questionnaire in order to determine their positive predictive value, sensitivity and specificity. RESULTS: The PPV (positive predictive value) of the first scoring system was 75.1% (95% CI 68.6–82.3), whilst that of the second system was 82.3% (95% CI 75.9–89.2). The more stringent second system had the greater specificity, 97.1% (95% CI 96.0–98.2) versus 95.3% (95% CI 94.0–96.7), but poorer sensitivity 46.9% (95% CI 33.0–66.8) versus 50.3% (95% CI 35.3–71.6). CONCLUSION: This scoring system based on the number of symptoms/risk factors reported via a postal questionnaire could be used to identify adults who would benefit from a trial of treatment for obstructive airways disease

    2 days versus 5 days of postoperative antibiotics for complex appendicitis:a pragmatic, open-label, multicentre, non-inferiority randomised trial

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    Background: The appropriate duration of postoperative antibiotics for complex appendicitis is unclear. The increasing global threat of antimicrobial resistance warrants restrictive antibiotic use, which could also reduce side-effects, length of hospital stay, and costs. Methods: In this pragmatic, open-label, non-inferiority trial in 15 hospitals in the Netherlands, patients with complex appendicitis (aged ≥8 years) were randomly assigned (1:1) to receive 2 days or 5 days of intravenous antibiotics after appendicectomy. Randomisation was stratified by centre, and treating physicians and patients were not masked to treatment allocation. The primary endpoint was a composite endpoint of infectious complications and mortality within 90 days. The main outcome was the absolute risk difference (95% CI) in the primary endpoint, adjusted for age and severity of appendicitis, with a non-inferiority margin of 7·5%. Outcome assessment was based on electronic patient records and a telephone consultation 90 days after appendicectomy. Efficacy was analysed in the intention-to-treat and per-protocol populations. Safety outcomes were analysed in the intention-to-treat population. This trial was registered with the Netherlands Trial Register, NL5946. Findings: Between April 12, 2017, and June 3, 2021, 13 267 patients were screened and 1066 were randomly assigned, 533 to each group. 31 were excluded from intention-to-treat analysis of the 2-day group and 30 from the 5-day group owing to errors in recruitment or consent. Appendicectomy was done laparoscopically in 955 (95%) of 1005 patients. The telephone follow-up was completed in 664 (66%) of 1005 patients. The primary endpoint occurred in 51 (10%) of 502 patients analysed in the 2-day group and 41 (8%) of 503 patients analysed in the 5-day group (adjusted absolute risk difference 2·0%, 95% CI −1·6 to 5·6). Rates of complications and re-interventions were similar between trial groups. Fewer patients had adverse effects of antibiotics in the 2-day group (45 [9%] of 502 patients) than in the 5-day group (112 [22%] of 503 patients; odds ratio [OR] 0·344, 95% CI 0·237 to 0·498). Re-admission to hospital was more frequent in the 2-day group (58 [12%] of 502 patients) than in the 5-day group (29 [6%] of 503 patients; OR 2·135, 1·342 to 3·396). There were no treatment-related deaths. Interpretation: 2 days of postoperative intravenous antibiotics for complex appendicitis is non-inferior to 5 days in terms of infectious complications and mortality within 90 days, based on a non-inferiority margin of 7·5%. These findings apply to laparoscopic appendicectomy conducted in a well resourced health-care setting. Adopting this strategy will reduce adverse effects of antibiotics and length of hospital stay. Funding: The Netherlands Organization for Health Research and Development.</p
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